Circuit board

Abstract

Printed circuit board (1, 1a, 1b, 1c, 1d, 1e, 1f, 1g, 1h, 1i, 1j), comprising: a printed circuit board (9) comprising an insulating substrate (10) containing a first main surface (10a), a first grounding structure (11), a second grounding structure (15) and a first signal line structure (13a, 13b); a first integrated circuit chip (40) mounted on the circuit board (9); a connector (20) which is mounted on the circuit board (9) and can be connected to an electrical cable (30); and a first capacitor (50) mounted on the circuit board (9), wherein In a plan view of the first main surface (10a), the first earthing structure (11) has a wider surface than the second earthing structure (15), the second earthing structure (15) is separated from the first earthing structure (11) and is directly opposite the first earthing structure (11) in the top view of the first main surface (10a), the first signal line structure (13a, 13b) is isolated from the first earthing structure (11) and the second earthing structure (15), the connector (20) includes a housing (21), a connector earthing wiring (25c) provided inside the housing (21), and a first connector signal wiring (25a, 25b) provided inside the housing (21), the first integrated circuit chip (40) includes a first grounding terminal (42c) and a first signal terminal (42a, 42b), the first earthing terminal (42c) is electrically connected to the first earthing structure (11) and is opposite the second earthing structure (15) in the top view of the first main surface (10a), the first signal connection (42a, 42b) is electrically connected to the first connector signal wiring (25a, 25b) via the first signal line structure (13a, 13b), the second earthing structure (15) is electrically connected to the housing (21) or the connector earthing wiring (25c) and the first capacitor (50) is connected to the first earthing structure (11) and the second earthing structure (15) and is arranged on a straight line (50a) which defines a shortest distance between the first earthing terminal (42c) and the second earthing structure (15) in the top view of the first main surface (10a).

Description

TECHNICAL AREA

[0001] The present disclosure relates to a printed circuit board. STATE OF THE ART

[0002] Japanese Patent Interpretation JP 2020-53491 A (PTL 1) discloses an electronic control device comprising a metal housing and a printed circuit board. The housing includes an upper housing section and a lower housing section. The lower housing section is attached to the upper housing section by several screws. The printed circuit board is located inside the housing. A connector is provided on the printed circuit board. A grounding structure and a protective structure are formed on the printed circuit board. The protective structure is formed in an outer peripheral section of the printed circuit board and is separate from the grounding structure. The grounding structure and the protective structure are connected to each other by a capacitor near an intermediate point of fixed positions where the upper housing section and the lower housing section are attached to each other.

[0003] Japanese patent JP 6 843 312 B1 (PTL2) relates to a circuit board to which a signal power group, including a grounding conductor, is connected and on which a communication circuit is mounted. The circuit board comprises a first grounding structure, a second grounding structure, and a third grounding structure.

[0004] The Japanese patent interpretation JP 2016 - 219 553 A (PTL3) describes a circuit chip that is arranged on a first ground structure which is connected to a second ground structure via a capacitor. LIST OF QUOTE PATENT LITERATURE PTL 1: Japanese Patent Interpretation JP 2020-53491 A PTL 2: Japanese patent JP 6 843 312 B1 PTL 3: Japanese Patent Interpretation JP 2016 - 219 553 A BRIEF DESCRIPTION OF THE INVENTIONAL PROBLEM

[0005] When an integrated circuit chip is mounted on the printed circuit board of the electronic control device disclosed in PTL 1, the grounding structure provides a reference potential for the integrated circuit chip. In this electronic control device, electromagnetic noise can sometimes propagate to the grounding structure through an electrical cable connected to the connector. When electromagnetic noise propagates to the entire grounding structure, malfunction or electrical breakdown of an electronic component can sometimes occur. The present disclosure was made in light of the aforementioned problem, and its objective is to provide a printed circuit board capable of preventing malfunction or electrical breakdown of an electronic component electrically connected to a grounding structure. SOLUTION TO THE PROBLEM

[0006] A printed circuit board according to the present disclosure comprises a circuit board, a first integrated circuit chip, a connector, and a first capacitor. The circuit board includes an insulating substrate that contains a first main surface, a first grounding structure, a second grounding structure, and a first signal line structure. The first integrated circuit chip is mounted on the circuit board. The connector is mounted on the circuit board and can be connected to an electrical cable. The first capacitor is mounted on the circuit board. In a plan view of the first main surface, the first grounding structure has a wider area than the second grounding structure. The second grounding structure is separate from the first grounding structure and is located directly opposite the first grounding structure in the plan view of the first main surface. The first signal line structure is isolated from the first grounding structure and the second grounding structure.The connector comprises a housing, connector grounding wiring located inside the housing, and first connector signal wiring, also located inside the housing. The first integrated circuit chip includes a first grounding terminal and a first signal terminal. The first grounding terminal is electrically connected to the first grounding structure and opposite the second grounding structure in the top view of the first main surface. The first signal terminal is electrically connected to the first connector signal wiring via the first signal conductor structure. The second grounding structure is electrically connected to the housing or the connector grounding wiring.The first capacitor is connected to the first grounding structure and the second grounding structure and is arranged on a straight line that defines a shortest distance between the first grounding terminal and the second grounding structure in the top view of the first main surface. ADVANTAGEOUS EFFECTS OF THE INVENTION

[0007] Thus, electromagnetic noise from an electrical cable into the first integrated circuit chip does not propagate to the entire first grounding structure, but instead flows through the first capacitor into the second grounding structure. In the printed circuit board of the present disclosure, malfunction or electrical breakdown of an electronic component (for example, the first integrated circuit chip) that is electrically connected to the first grounding structure can be prevented. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a perspective view of an electronic device in a first embodiment. Fig. Figure 2 is a schematic top view of a printed circuit board in the first embodiment. Fig. Figure 3 is a circuit diagram of the printed circuit board in the first embodiment, showing a path of electromagnetic noise. Fig. Figure 4 is a schematic top view of the circuit board in the first embodiment, showing a path of electromagnetic noise. Fig. Figure 5 is a schematic top view of a printed circuit board in a comparative example. Fig. Figure 6 is a schematic top view of the circuit board in the comparison example, showing a path of electromagnetic noise. Fig. Figure 7 is a schematic top view of the circuit board in the comparison example, showing a path of electromagnetic noise. Fig. Figure 8 is a graph showing the extent of coupling of electromagnetic noise to an integrated circuit chip in the first embodiment and the comparison example. Fig. Figure 9 is a graph showing the extent of coupling of electromagnetic noise to an integrated circuit chip in relation to the capacitance of a capacitor in the first embodiment. Fig. Figure 10 is a perspective view of an electronic device in a modification of the first embodiment. Fig. Figure 11 is a schematic top view of a printed circuit board in a second embodiment. Fig. Figure 12 is a schematic top view of a printed circuit board in a third embodiment. Fig. Figure 13 is a schematic top view of a printed circuit board in a fourth embodiment. Fig. Figure 14 is a schematic view from below of the printed circuit board in the fourth embodiment. Fig. Figure 15 is a schematic top view of a printed circuit board in a modification of the fourth embodiment. Fig. Figure 16 is a schematic view from below of the printed circuit board in the modification of the fourth embodiment. Fig. Figure 17 is a schematic top view of a printed circuit board in a fifth embodiment. Fig. Figure 18 is a schematic top view of the circuit board in the fifth embodiment, showing a path of electromagnetic noise. Fig. Figure 19 is a schematic top view of a printed circuit board in a sixth embodiment. Fig. Figure 20 is a schematic top view of a printed circuit board in a seventh embodiment. Fig. Figure 21 is a graph showing the extent of coupling of electromagnetic noise to an integrated circuit chip in the first embodiment and the seventh embodiment. Fig. Figure 22 is a schematic top view of a printed circuit board in a modification of the seventh embodiment. Fig. Figure 23 is a perspective view of an electronic device in an eighth embodiment. DESCRIPTION OF EXECUTION FORMS

[0008] Embodiments of the present disclosure are described below. The same configuration is designated by the same reference numeral and its description is not repeated. First embodiment

[0009] With reference to Fig. 1 to Fig. In Section 10, a printed circuit board 1 in a first embodiment is described. The printed circuit board 1 is used, for example, in an electronic device 2. The electronic device 2 can be, for example, but is not limited to, a control device for manufacturing automation (MA) systems, an electronic device with a control panel, such as a smartphone, an electronic device installed in an environment where electromagnetic noise occurs, such as a power plant or factory, an electronic device installed in motor vehicles, aircraft, or artificial satellites, or a consumer device such as an air conditioner. The electronic device 2 includes, for example, a printed circuit board 1 and a housing 60. The printed circuit board 1 is, for example, attached to the housing 60.

[0010] The circuit board 1 mainly contains a circuit board 9, a connector 20, a first integrated circuit chip 40 and a capacitor 50.

[0011] The circuit board 9 contains an insulating substrate 10, a first earthing structure 11, a second earthing structure 15 and at least one first signal line structure.

[0012] The insulating substrate 10 is, for example, a glass epoxy substrate such as FR-4 substrate, a glass composite substrate such as CEM-3 substrate, a paper phenol substrate such as FR-1 substrate, or a paper epoxy substrate. The insulating substrate 10 has, for example, a relative permittivity of 3.0 or higher and 5.0 or lower.

[0013] The insulating substrate 10 comprises a first main surface 10a and a second main surface 10b opposite the first main surface 10a. In a top view of the first main surface 10a of the insulating substrate 10, the insulating substrate 10 (circuit board 9) has, for example, a rectangular shape. The first main surface 10a and the second main surface 10b each extend along a first direction (x-direction) and a second direction (y-direction) that intersects the first direction (x-direction). In particular, the second direction (y-direction) is perpendicular to the first direction (x-direction). The thickness direction of the insulating substrate 10 is a third direction (z-direction) perpendicular to both the first direction (x-direction) and the second direction (y-direction). The insulating substrate 10 includes an outer edge section 10c in which the connector 20 is located.

[0014] The size of each side of insulating substrate 10 (circuit board 9) in a top view of the first main surface 10a of insulating substrate 10 is, for example, 5 cm or more. The size of each side of insulating substrate 10 (circuit board 9) in a top view of the first main surface 10a of insulating substrate 10 is, for example, 30 cm or less. The size of each side of insulating substrate 10 (circuit board 9) in a top view of the first main surface 10a of insulating substrate 10 can be 15 cm or less.

[0015] The first grounding structure 11 is, for example, made of a conductive material such as copper or aluminum. The first grounding structure 11 is electrically connected to a first grounding terminal 42c of the first integrated circuit chip 40 and provides a reference potential for the first integrated circuit chip 40. Due to the residual inductance of a conductor (for example, conductive wire 55), the reference potential provided by the first grounding structure 11 for the first integrated circuit chip 40 differs from a later described reference potential for alternating voltage. The first grounding structure 11 is, for example, located on the first main surface 10a. In a top view of the first main surface 10a of insulating substrate 10, the first grounding structure 11 is located in the center of the insulating substrate 10 relative to the second grounding structure 15.

[0016] In a plan view of the first main surface 10a of insulating substrate 10, the first grounding structure 11 has a wider area than the second grounding structure 15. In other words, in a plan view of the first main surface 10a of insulating substrate 10, the first grounding structure 11 has a greater width than the second grounding structure 15. The first grounding structure 11 has a larger cross-sectional area than the second grounding structure 15. Thus, the first grounding structure 11 has a lower residual inductance than the second grounding structure 15. The cross-sectional area of ​​the first grounding structure 11, for example, denotes the area of ​​the first grounding structure 11 in a cross-section perpendicular to the first main surface 10a of insulating substrate 10 and the longitudinal direction of the first grounding structure 11.The cross-sectional area of ​​the second earthing structure 15, for example, denotes the area of ​​the second earthing structure 15 in a cross-section perpendicular to the first main surface 10a of insulating substrate 10 and the longitudinal direction of the second earthing structure 15.

[0017] In a plan view of the first main surface 10a of insulating substrate 10, the first grounding structure 11 includes an outer edge section 11a, an outer edge section 11b opposite outer edge section 11a, and an outer edge section 11c. The outer edge section 11a is opposite the outer edge section 10c of insulating substrate 10. For example, the outer edge section 11a is the section closest to the outer edge section 10c of insulating substrate 10 in the outer edge of the first grounding structure 11. The outer edge section 11b is, for example, the section furthest from the outer edge section 10c of insulating substrate 10 in the outer edge of the first grounding structure 11. The outer edge sections 11a and 11b extend, for example, along the first direction (x-direction). The outer edge section 11c is connected to the outer edge section 11a and outer edge section 11b.The outer boundary section 11c extends in a different direction from the outer boundary sections 11a and 11b. For example, the outer boundary section 11c extends along the second direction (y-direction).

[0018] The second grounding structure 15 is, for example, made of a conductive material such as copper or aluminum. The second grounding structure 15 is, for example, provided on the first main surface 10a. In a plan view of the first main surface 10a of insulating substrate 10, the second grounding structure 15 is located in an outer peripheral region of insulating substrate 10 relative to the first grounding structure 11. The second grounding structure 15 extends, for example, along the outer edge section 11c of the first grounding structure 11. The second grounding structure 15 extends, for example, along the second direction (y-direction). The second grounding structure 15 can, for example, have a strip shape. The longitudinal direction of the second grounding structure 15 is, for example, the second direction (y-direction). The lateral direction of the second grounding structure 15 is, for example, the first direction (x-direction).

[0019] The second grounding structure 15 is separated from the first grounding structure 11 (outer edge section 11c), for example, in the first direction (x-direction). The second grounding structure 15 is directly opposite the first grounding structure 11 (outer edge section 11c) in a plan view of the first main surface 10a of the insulating substrate 10. In other words, in a plan view of the first main surface 10a of the insulating substrate 10, the circuit board 9 does not contain any conductive structure between the first grounding structure 11 (outer edge section 11c) and the second grounding structure 15. No electronic component (excluding capacitor 50) is located on or above the second grounding structure 15 in a plan view of the first main surface 10a of the insulating substrate 10.

[0020] The second grounding structure 15 is electrically connected to the reference potential 59, similar to the ground potential. More precisely, the second grounding structure 15 is connected to the ground potential via a conductor, similar to a grounded conductor. The ground potential is the potential of the earth. The conductor is, for example, a conductive wire 55. Due to the residual inductance of the conductor (for example, the conductive wire 55), the potential of the second grounding structure 15 differs from the reference potential 59 for alternating current.

[0021] More precisely, the conductor (for example, conductive wire 55) is attached to the second grounding structure 15 using a fastening element 56, such as a screw. As an example, a screw is screwed into a screw hole provided in the insulating substrate 10. The conductive wire 55 lies between the head of the screw and the second grounding structure 15. The conductor (for example, conductive wire 55) is attached, for example, to a distal end of the second grounding structure 15 relative to the outer edge section 11a of the first grounding structure 11 (outer edge section 10c of the insulating substrate 10) (a proximal end of the second grounding structure 15 relative to the outer edge section 11b of the first grounding structure 11). The conductor (for example, conductive wire 55) is also in contact with the housing 60 of the electronic device 2.

[0022] The second grounding structure 15 is electrically connected to a housing 21 or to a connector grounding wire 25c of connector 20. Thus, when an electrical cable 30 is connected to connector 20, the second grounding structure 15 is electrically connected to a sheath 32 of the electrical cable 30 via a terminal 24c, housing 21, and connector body 31 of the electrical cable 30. Alternatively, when the electrical cable 30 is connected to connector 20, the second grounding structure 15 is electrically connected to a cable grounding wire 35c of the electrical cable 30 via terminal 24c, connector grounding wire 25c, a terminal 23c, and a terminal 33c.

[0023] At least one first signal line structure (for example, first signal line structures 13a, 13b) is formed, for example, from a conductive material such as copper or aluminum. At least one first signal line structure is provided, for example, on the first main surface 10a. At least one first signal line structure is separated from and insulated from the first grounding structure 11 and the second grounding structure 15. At least one first signal line structure corresponds to at least one first cable signal wiring. The printed circuit board 9 contains, for example, two first signal line structures 13a, 13b.

[0024] The connector 20 is mounted on the circuit board 9. The connector 20 can be connected to the electrical cable 30. For example, the connector 20 can be a socket that can accept the connector body 31 of the electrical cable 30. The connector 20 is electrically isolated from the first grounding structure 11. The connector 20 includes, for example, a housing 21, at least one first connector signal wiring (for example, first connector signal wiring 25a, 25b), and terminals 23a, 23b, 24a, 24b. The connector 20 can further include a connector grounding wire 25c and terminals 23c, 24c.

[0025] The housing 21 can be a conductive housing, such as a metal housing, or it can be an insulated housing formed from an insulator, such as insulating resin. If the connector 20 is a socket, the housing 21 has a receiving section 22 that can receive a plug of the electrical cable 30.

[0026] At least one first connector signal wiring (for example, first connector signal wiring 25a, 25b) is provided inside the housing 21. At least one first connector signal wiring corresponds to at least one first cable signal wiring. The connector 20 contains, for example, two sets of first connector signal wiring 25a, 25b. The first connector signal wiring 25a is connected to terminal 23a and terminal 24a. The first connector signal wiring 25b is connected to terminal 23b and terminal 24b. Terminal 24a is in contact with and electrically connected to the first signal line structure 13a. Terminal 24b is in contact with and electrically connected to the first signal line structure 13b.

[0027] The connector grounding wire 25c is located inside the housing 21. The connector grounding wire 25c is connected to terminal 23c and terminal 24c. Terminal 24c is in contact with and connected to the second grounding structure 15.

[0028] The electrical cable 30 includes, for example, the connector body 31, the sheath 32, at least one first cable signal wiring (for example, first cable signal wiring 35a, 35b) and terminals 33a, 33b. The electrical cable 30 may further include a cable earthing wiring 35c and terminal 33c.

[0029] The connector body 31 can, for example, be a plug that is inserted into the receiving section 22 of housing 21. The sheath 32 is connected to the connector body 31 and accommodates at least one first cable signal wire (for example, first cable signal wire 35a, 35b). The sheath 32 can also accommodate the cable ground wire 35c. The sheath 32 can be made of a conductive material such as metal and can be a conductive sheath. The sheath 32 can be made of an insulating material such as insulating resin and can be an insulating sheath.

[0030] For example, electrical cable 30 contains two sets of a first cable signal wiring 35a, 35b. The first cable signal wiring 35a, 35b is, for example, a pair of differential signal wiring. The first cable signal wiring 35a is connected to terminal 33a. The first cable signal wiring 35b is connected to terminal 33b. When electrical cable 30 is connected to connector 20, terminal 33a makes contact with terminal 23a and terminal 33b makes contact with terminal 23b. In this way, the first cable signal wiring 35a is electrically connected to the first connector signal wiring 25a via terminal 33a and terminal 23a. The first cable signal wiring 35b is electrically connected to the first connector signal wiring 25b via terminal 33b and terminal 23b.

[0031] The cable grounding wire 35c is connected to terminal 33c. When the electrical cable 30 is connected to the connector 20, terminal 33c comes into contact with terminal 23c. In this way, the cable grounding wire 35c is electrically connected to the connector grounding wire 25c via terminals 33c and 23c.

[0032] The first integrated circuit chip 40 is, for example, but not limited to, an application-specific integrated circuit (ASIC) chip containing a communication circuit. The first integrated circuit chip 40 is mounted on the printed circuit board 9. The first integrated circuit chip 40 is arranged on the first grounding structure 11. In a top view of the first main surface 10a of insulating substrate 10, the first integrated circuit chip 40 is located inside the outer edge of the first grounding structure 11. The first integrated circuit chip 40 includes at least one first signal terminal (for example, first signal terminals 42a, 42b) and the first ground terminal 42c.

[0033] At least one first signal connection (for example, first signal connections 42a, 42b) corresponds to at least one first signal line structure (for example, first signal line structures 13a, 13b). At least one first signal connection is electrically connected to at least one first connector signal wiring (for example, first connector signal wiring 25a, 25b) by at least one first signal line structure.

[0034] For example, the first integrated circuit chip 40 contains two first signal terminals 42a and 42b. The first signal terminal 42a is in contact with and electrically connected to the first signal line structure 13a. The first signal terminal 42a is electrically connected to the first connector signal wiring 25a via the first signal line structure 13a and terminal 24a. The first signal terminal 42b is in contact with and electrically connected to the first signal line structure 13b. The first signal terminal 42b is electrically connected to the first connector signal wiring 25b via the first signal line structure 13b and terminal 24b.

[0035] The first grounding terminal 42c is in contact with and electrically connected to the first grounding structure 11. The first grounding terminal 42c is opposite the second grounding structure 15 in a top view of the first main surface 10a of insulating substrate 10. For example, the first grounding terminal 42c is opposite the second grounding structure in the first direction (x-direction).

[0036] High-frequency electromagnetic noise from a typical electronic device or the like (for example, general-mode electromagnetic noise with a frequency of 1 MHz or higher) flows from connector 20 into the printed circuit board 9. The shortest distance between the first ground terminal 42c and the second ground structure 15 is, for example, one-tenth or less of the electrical length of this electromagnetic noise inside the printed circuit board 9. The shortest distance between the first ground terminal 42c and the second ground structure 15 could be one-twentieth or less of the electrical length, one-fiftieth or less of the electrical length, or one-hundredth or less of the electrical length. For example, if the relative permittivity of the printed circuit board 9 is 4 and the frequency of the electromagnetic noise is 100 MHz, the electrical length inside the printed circuit board 9 is approximately 1.5 m.

[0037] Capacitor 50 is, for example, a multilayer ceramic capacitor or an electrolytic aluminum capacitor. Capacitor 50 is mounted on circuit board 9. Capacitor 50 is connected to the first grounding structure 11 and the second grounding structure 15. Capacitor 50 may be the only capacitor connected to the first grounding structure 11 and the second grounding structure 15.

[0038] The capacitance of capacitor 50 is, for example, 0.5 µF or more. In particular, the capacitance of capacitor 50 can be, for example, 0.9 µF or more.

[0039] Generally, as the frequency of the alternating voltage through a capacitor increases, the capacitor's impedance decreases. Electromagnetic noise from a typical electronic device has a relatively high frequency (for example, 1 MHz or higher). This high-frequency electromagnetic noise, propagating through the sheath 32 of the electrical cable 30, is coupled to the first cable signal wiring 35a, 35b due to parasitic capacitance inside the electrical cable 30, or to the first connector signal wiring 25a, 25b due to parasitic capacitance inside the connector 20. In this way, the high-frequency electromagnetic noise flows from the electrical cable 30 into the first signal line structures 13a, 13b and the first ground structure 11.

[0040] Generally, as the capacitance of a capacitor decreases, its impedance increases. Since the capacitance of capacitor 50 is 0.5 µF or greater, an excessive increase in the impedance of capacitor 50 for this high-frequency electromagnetic noise is prevented. The high-frequency electromagnetic noise flows easily through capacitor 50 from the first ground structure 11 to the second ground structure 15. Capacitor 50, with a capacitance of 0.5 µF or greater, prevents the high-frequency electromagnetic noise flowing into the first ground structure 11 from propagating throughout the entire first ground structure 11 and allows the high-frequency electromagnetic noise to escape to the outside of the circuit board 1 (for example, reference potential 59) via capacitor 50 and the second ground structure 15.Variation in the potential of the first grounding structure 11 resulting from high-frequency electromagnetic noise is suppressed, and malfunction or electrical breakdown of the first integrated circuit chip 40, which is electrically connected to the first grounding structure 11, can be prevented.

[0041] The capacitance of capacitor 50 is, for example, 5.0 µF or less. Specifically, the capacitance of capacitor 50 could be, for example, 2.0 µF or less, or it could be 1.1 µF or less.

[0042] Generally, when the frequency of the alternating voltage through a capacitor decreases, the impedance of the capacitor increases. Electromagnetic noise resulting from lighting or the like has a relatively low frequency (for example, 100 kHz or lower). This low-frequency electromagnetic noise, propagating through the sheath 32 of the electrical cable 30, does not flow into the first connector signal wiring 25a, 25b and the first signal line structure 13a, 13b due to parasitic capacitance inside the electrical cable 30 or parasitic capacitance inside the connector 20, but instead flows through the housing 21 into the second grounding structure 15.

[0043] Generally, the capacitance of a capacitor increases when its impedance decreases. Since the capacitance of capacitor 50 is 5.0 µF or less, an excessive decrease in the impedance of capacitor 50 for low-frequency electromagnetic noise is prevented. Capacitor 50, with a capacitance of 5.0 µF or less, prevents the low-frequency electromagnetic noise from flowing from the second ground structure 15 through capacitor 50 to the first ground structure 11, and allows the low-frequency electromagnetic noise to escape to the outside of the circuit board 1 (for example, reference potential 59).A variation in the potential of the first grounding structure 11 resulting from low-frequency electromagnetic noise is suppressed, and malfunction or electrical breakdown of an electronic component (for example, first integrated circuit chip 40) electrically connected to the first grounding structure 11 can be prevented.

[0044] Furthermore, since the capacitance of capacitor 50 is 5.0 µF or less, a capacitor with a high voltage rating (for example, a voltage rating of 500 V or higher) can be used as capacitor 50. Electromagnetic noise emitted from the first grounding structure 11 to the second grounding structure 15 may be increased.

[0045] In a top view of the first main surface 10a of insulating substrate 10, the capacitor 50 is arranged on a straight line 50a that defines the shortest distance between the first grounding terminal 42c and the second grounding structure 15. The straight line 50a extends, for example, along the first direction (x-direction).

[0046] With reference to Fig. 3 to Fig. 8 The operation of the printed circuit board 1 in the present embodiment is compared with a printed circuit board 1a in a comparative example.

[0047] With reference to Fig. 3 and Fig. 4. When the electrical cable 30 is connected to the connector 20, the second grounding structure 15 is electrically connected to the sheath 32 of the electrical cable 30 via terminal 24c, housing 21, and connector body 31, or electrically connected to the cable grounding 35c of the electrical cable 30 via terminal 24c, connector grounding wire 25c, terminal 23c, and terminal 33c. For example, electromagnetic noise with a frequency of 1 MHz or higher can sometimes propagate from a noise source to the outside of the printed circuit board 1 through the electrical cable 30 and flow into the printed circuit board 1. The majority of electromagnetic noise passes through housing 21 or connector grounding wiring 25c and terminal 24c and flows into the second grounding structure 15 instead of flowing into the first grounding structure 11 (see a noise path 61 in Fig. 3) In this way, the majority of electromagnetic noise from the second grounding structure 15 can be released to the grounding potential.

[0048] However, the electrical cable 30 exhibits residual inductance. Therefore, due to electrical crosstalk in the electrical cable 30, some electromagnetic noise propagates through at least one first cable signal wiring (for example, first cable signal wiring 35a, 35b). Electromagnetic noise passes through at least one first cable signal wiring, at least one first connector signal wiring (for example, first connector signal wiring 25a, 25b), and at least one first signal line structure (for example, first signal line structures 13a, 13b) and flows from at least one first signal terminal (for example, first signal terminals 42a, 42b) into the first integrated circuit chip 40. Electromagnetic noise flows from the first ground terminal 42c of the first integrated circuit chip 40 into the first ground structure 11 (see a noise path 64 in [reference]). Fig. 3 and Fig. 4).

[0049] In the present embodiment, the second grounding structure 15 is located directly opposite the first grounding structure 11 in a plan view of the first main surface 10a of the insulating substrate 10. The first grounding terminal 42c is electrically connected to the first grounding structure 11 and is located opposite the second grounding structure 15 in a plan view of the first main surface 10a of the insulating substrate 10. The capacitor 50 is connected to the first grounding structure 11 and the second grounding structure 15 and is arranged on the straight line 50a, which defines the shortest distance between the first grounding terminal 42c and the second grounding structure 15 in a plan view of the first main surface 10a of the insulating substrate 10. Thus, electromagnetic noise flowing into the first integrated circuit chip 40 does not propagate across the entire first grounding structure 11, but flows through the capacitor 50 into the second grounding structure 15 (see noise path 64 in Figure 64). Fig. 3 and Fig. 4) Malfunction or electrical breakdown of an electronic component (for example, an active electronic component such as integrated circuit chip 40b or a light-emitting diode) that is not the first integrated circuit chip 40 electrically connected to the first grounding structure 11 can be prevented.

[0050] For comparison, with reference to Fig. 5 to Fig. 7, in the circuit board 1a of the comparative example, the capacitor 51 is connected to the first grounding structure 11 and the second grounding structure 15, similar to the capacitor 50 of the circuit board 1 in the present embodiment. The capacitor 51 is configured similarly to the capacitor 50. However, in the circuit board 1a of the comparative example, the first grounding terminal 42c of the second grounding structure 15 is not opposite the first main surface 10a of the insulating substrate 10 in a plan view. Additionally, the capacitor 51 is located far from the straight line 50a, which defines the shortest distance between the first grounding terminal 42c and the second grounding structure 15 in a plan view of the first main surface 10a of the insulating substrate 10.Moreover, as previously described, the first grounding structure 11 has a smaller residual inductance than the second grounding structure 15, and electromagnetic noise flows more easily to the first grounding structure 11 than to the second grounding structure 15.

[0051] Thus, electromagnetic noise flowing into the first integrated circuit chip 40 spreads to the entire first grounding structure 11 (see noise paths 64a, 64b in Fig. 6 and Fig. 7). For example, as in Fig. As shown in Figure 6, electromagnetic noise propagating from the first ground terminal 42c of the first integrated circuit chip 40 to the capacitor 50 crosses a wiring such as at least one first signal line structure (for example, first signal line structures 13a, 13b) (see noise path 64a in Figure 6). Fig. 6) A portion of the electromagnetic noise flows into an electronic component (for example, the first integrated circuit chip 40) that is connected to this wiring. As in Fig. As shown in Figure 7, electromagnetic noise propagating from the first ground terminal 42c of the first integrated circuit chip 40 to the capacitor 51 is propagated through an electronic component other than the first integrated circuit chip 40 (for example, an active electronic component such as the integrated circuit chip 40b or a light-emitting diode) (see noise path 64b in Figure 7). Fig. 7) In this way, the reference potential of an electronic component (first integrated circuit chip 40 and another electronic component other than the first integrated circuit chip 40) connected to the first grounding structure 11 is varied. Due to electromagnetic noise, an electronic component electrically connected to the first grounding structure 11 (first integrated circuit chip 40 and another electronic component other than the first integrated circuit chip 40) may malfunction or experience electrical breakdown.

[0052] Fig. Figure 8 shows the extent of coupling of electromagnetic noise to an electronic component other than the first integrated circuit chip 40 (for example, integrated circuit chip 40b (see Figure 8)). Fig. 4, Fig. 6 and Fig. 7)) in the present embodiment and the comparative example, when electromagnetic noise is applied to an electrical cable 30. The degree of coupling of electromagnetic noise to the integrated circuit chip 40b is measured by bringing an electromagnetic noise detection probe into contact with a signal terminal and a ground terminal of the integrated circuit chip 40b. It is clear that the degree of coupling of electromagnetic noise to the integrated circuit chip 40b (see Fig. 4) in the present embodiment is less than the degree of coupling of electromagnetic noise to the integrated circuit chip 40b (see Fig. 6 and Fig. 7) in the comparative example.

[0053] With reference to Fig. It is clear that in the printed circuit board 1 in the present embodiment, if the capacitance of the capacitor 50 is increased from 0.1 µF to 1.0 µF, the degree of coupling of electromagnetic noise to an electronic component other than the first integrated circuit chip 40 (for example, integrated circuit chip 40b (see Figure 9)) will be reduced. Fig. 4)) is reduced. The reason is that the impedance of capacitor 50 decreases due to the increase in capacitance of capacitor 50, so electromagnetic noise flows easily from the first ground structure 11 through capacitor 50 to the second ground structure 15. However, even if the capacitance of capacitor 50 is increased from 1.0 µF to 10 µF, the degree of coupling of electromagnetic noise to the integrated circuit chip 40b changes only slightly. If a capacitor 50 with a low capacitance (for example, a capacitance of 2.0 µF or less) is used, a capacitor with a high voltage rating (for example, a voltage rating of 500 V or higher) can be used as capacitor 50. Electromagnetic noise released from the first ground structure 11 to the second ground structure 15 may increase. (Modifications)

[0054] With reference to Fig. In a first modification of the present embodiment, the printed circuit board 1 is separated from the housing 60 in the electronic device 2. The conductive wire 55 is connected to a conductive rod 57, such as a metal rod, on a surface of the housing 60. A first end of the conductive rod 57 is attached to the housing 60. A second end of the conductive rod 57, opposite the first end, is inserted into a hole provided in the insulating substrate 10. The conductive rod 57 is attached to the second grounding structure 15 by a fastening element 56, such as a screw. For example, the screw is screwed into a screw hole provided at the second end of the conductive rod 57.

[0055] In the present embodiment, which is described in Fig. 1 and Fig. As shown in Figure 2, the printed circuit board 9 is a single-sided printed circuit board with a first grounding structure 11, a second grounding structure 15, and the first signal line structure formed on the first main surface 10a of insulating substrate 10. In a second modification of the present embodiment, the printed circuit board 9 can be a double-sided printed circuit board or a multilayer printed circuit board.

[0056] In a double-sided printed circuit board, conductive structures, which include a first earthing structure 11, a second earthing structure 15 and at least one first signal line structure (for example, first signal line structures 13a, 13b), are formed on both the first main surface 10a and the second main surface 10b of insulating substrate 10.

[0057] In a multilayer printed circuit board, conductive structures comprising a first grounding structure 11, a second grounding structure 15, and at least one first signal line structure (for example, first signal line structures 13a, 13b) are formed on the first main surface 10a and second main surface 10b of insulating substrate 10 and within the insulating substrate 10. The conductive structures formed within the insulating substrate 10 are electrically connected to the first integrated circuit chip 40 and to an electronic component other than the first integrated circuit chip 40 (for example, an active electronic component such as integrated circuit chip 40b or a light-emitting diode) using conductive vias (not shown) extending in the thickness direction (third direction (z-direction)) of insulating substrate 10.When the first grounding structure 11 is formed inside insulating substrate 10, the first integrated circuit chip 40 and another electronic component other than the first integrated circuit chip 40 are arranged above the first grounding structure 11 in a top view of the first main surface 10a of insulating substrate 10.

[0058] In a third modification of the present embodiment, the first integrated circuit chip 40 can be a power supply IC chip and at least one first signal line structure (for example, first signal line structures 13a, 13b) can be a power supply wiring.

[0059] In a fourth modification of the present embodiment, the reference potential 59 can be a potential of a conductor serving as a reference potential of the electronic device 2 (for example, a potential of the negative electrode of a battery when the housing 60 floats from the potential of the earth, as in a motor vehicle, aircraft or artificial satellite), instead of the ground potential.

[0060] The effect of the circuit board 1 in the present embodiment is described.

[0061] In the present embodiment, the printed circuit board 1 comprises the circuit board 9, the first integrated circuit chip 40, the connector 20, and a first capacitor (for example, capacitor 50). The circuit board 9 includes the insulating substrate 10, comprising the main area 10a, the first grounding structure 11, the second grounding structure 15, and a first signal line structure (for example, first signal line structures 13a, 13b). The first integrated circuit chip 40 is mounted on the circuit board 9. The connector 20 is mounted on the circuit board 9 and can be connected to the electrical cable 30. The first capacitor is mounted on the circuit board 9. In a top view of the first main area 10a of the insulating substrate 10, the first grounding structure 11 has a wider area than the second grounding structure 15.The second grounding structure 15 is separate from the first grounding structure 11 and is located directly opposite the first grounding structure 11 in a top view of the first main surface 10a of insulating substrate 10. The first signal conductor structure is isolated from the first grounding structure 11 and the second grounding structure 15. The connector 20 includes the housing 21, the connector grounding wiring 25c provided inside the housing 21, and the first connector signal wiring (for example, first connector signal wiring 25a, 25b) provided inside the housing 21. The first integrated circuit chip 40 includes a first grounding terminal 42c and a first signal terminal (for example, first signal terminals 42a, 42b). The first earthing terminal 42c is electrically connected to the first earthing structure 11 and is opposite the second earthing structure 15 in a top view of the first main surface 10a of insulating substrate 10.The first signal terminal is electrically connected to the first connector signal wiring via the first signal line structure. The second grounding structure 15 is electrically connected to the housing 21 or the connector grounding wiring 25c. The first capacitor is connected to the first grounding structure 11 and the second grounding structure 15 and is located on the straight line 50a, which defines the shortest distance between the first grounding terminal 42c and the second grounding structure 15 in a plan view of the first main surface 10a of insulating substrate 10.

[0062] Thus, electromagnetic noise from the electrical cable 30 into the first integrated circuit chip 40 does not propagate to the entire first grounding structure 11, but flows through the first capacitor (for example, capacitor 50) into the second grounding structure 15. Malfunction or electrical breakdown of an electronic component that is electrically connected to the first grounding structure 11 (first integrated circuit chip 40 and an electronic component other than the first integrated circuit chip 40 (for example, an active electronic component such as integrated circuit chip 40b or a light-emitting diode)) can be prevented.

[0063] In the printed circuit board 1 in the present embodiment, the shortest distance between the first grounding terminal 42c and the second grounding structure 15 is one tenth or less of the electrical length inside the printed circuit board 9 from electromagnetic noise from the connector 20.

[0064] Thus, electromagnetic noise from the electrical cable 30 into the first integrated circuit chip 40 does not propagate to the entire first grounding structure 11, but flows through the first capacitor (for example, capacitor 50) into the second grounding structure 15. Malfunction or electrical breakdown of an electronic component that is electrically connected to the first grounding structure 11 (for example, the first integrated circuit chip 40 and a different electronic component than the first integrated circuit chip 40 (for example, an active electronic component such as integrated circuit chip 40b or a light-emitting diode)) can be prevented.

[0065] In the printed circuit board 1 in the present embodiment, the first capacitor (for example, capacitor 50) is the only capacitor connected to the first grounding structure 11 and the second grounding structure 15.

[0066] Thus, electromagnetic noise entering the second grounding structure 15 via the first capacitor (for example, capacitor 50) can be prevented from returning to the first grounding structure 11 via another capacitor. Malfunction or electrical breakdown of an electronic component electrically connected to the first grounding structure 11 (first integrated circuit chip 40 and another electronic component besides the first integrated circuit chip 40 (for example, an active electronic component such as integrated circuit chip 40b or a light-emitting diode)) can be prevented.

[0067] In the printed circuit board 1 of the present embodiment, the printed circuit board 9 has a rectangular shape in a top view of the first main surface 10a of insulating substrate 10. The size of each side of the printed circuit board 9 in a top view of the first main surface 10a of insulating substrate 10 is 5 cm or more and 15 cm or less. The capacitance of the first capacitor (for example, capacitor 50) is 0.5 µF or more and 5.0 µF or less.

[0068] The capacitance of the first capacitor (for example, capacitor 50) is 0.5 µF or greater. This prevents an excessive increase in the impedance of the first capacitor for high-frequency electromagnetic noise (for example, electromagnetic noise with a frequency of 1 MHz or higher) from a typical electronic device. The high-frequency electromagnetic noise from the electrical cable 30 into the first grounding structure 11 flows easily from the first grounding structure 11 through the first capacitor to the second grounding structure 15. The first capacitor, with a capacitance of 0.5 µF or greater, prevents the high-frequency electromagnetic noise from propagating throughout the first grounding structure 11 and allows it to escape to the outside of the circuit board 1 (for example, reference potential 59) via the first capacitor and the second grounding structure 15.Variation in the potential of the first grounding structure 11 resulting from high-frequency electromagnetic noise is suppressed, and malfunction or electrical breakdown of an electronic component electrically connected to the first grounding structure 11 (for example, first integrated circuit chip 40 and another electronic component other than the first integrated circuit chip 40 (for example, an active electronic component such as integrated circuit chip 40b or a light-emitting diode)) can be prevented.

[0069] The capacitance of the first capacitor (for example, capacitor 50) is 5.0 µF or less. This prevents an excessive drop in the impedance of the first capacitor due to low-frequency electromagnetic noise (for example, electromagnetic noise with a frequency of 100 kHz or lower) resulting from lighting or similar sources. Capacitor 50, with a capacitance of 5.0 µF or less, prevents the low-frequency electromagnetic noise propagating through the electrical cable 30 from flowing from the second grounding structure 15 through the first capacitor into the first grounding structure 11, and allows the low-frequency electromagnetic noise to escape to the outside of the circuit board 1 (for example, reference potential 59).Variation in the potential of the first grounding structure 11 resulting from low-frequency electromagnetic noise is suppressed, and malfunction or electrical breakdown of an electronic component electrically connected to the first grounding structure 11 (first integrated circuit chip 40 and an electronic component other than the first integrated circuit chip 40 (for example, an active electronic component such as integrated circuit chip 40b or a light-emitting diode)) can be prevented.

[0070] Furthermore, since the capacitance of the first capacitor (for example, capacitor 50) is 5.0 µF or less, a capacitor with a high voltage rating (for example, a voltage rating of 500 V or higher) can be used as the first capacitor. Electromagnetic noise that can be emitted from the first grounding structure 11 to the second grounding structure 15 can be increased. Malfunction or electrical breakdown of an electronic component that is electrically connected to the first grounding structure 11 (first integrated circuit chip 40 and another electronic component besides the first integrated circuit chip 40 (for example, an active electronic component such as integrated circuit chip 40b or a light-emitting diode)) can be prevented. Second embodiment

[0071] With reference to Fig. Section 11 describes a printed circuit board 1b in a second embodiment. The printed circuit board 1b in the present embodiment has a similar configuration to the printed circuit board 1 in the first embodiment, but differs mainly in the following points.

[0072] The first grounding structure 11 in the present embodiment has a recess 12 that accommodates the second grounding structure. More precisely, the recess 12 is provided on the outer edge section 11c of the first grounding structure 11.

[0073] In the present embodiment, the second earthing structure 15 includes a first earthing structure section 16a and a second earthing structure section 16b.

[0074] The first grounding structure section 16a extends along the outer edge section 11c of the first grounding structure 11. The first grounding structure section 16a extends, for example, along the second direction (y-direction). The first grounding structure section 16a can, for example, have a strip shape. The longitudinal direction of the first grounding structure section 16a is, for example, the second direction (y-direction). The lateral direction of the first grounding structure section 16a is, for example, the first direction (x-direction).

[0075] The first grounding structure section 16a is separated from the first grounding structure 11 (outer edge section 11c). More precisely, the first grounding structure section 16a is separated from the first grounding structure 11 (outer edge section 11c) in the first direction (x-direction). The first grounding structure section 16a is directly opposite the first grounding structure 11 (outer edge section 11c) in a plan view of the first main surface 10a of insulating substrate 10. In other words, in a plan view of the first main surface 10a of insulating substrate 10, the circuit board 9 contains no conductive structure (excluding the second grounding structure section 16b) between the first grounding structure 11 (outer edge section 11c) and the first grounding structure section 16a.

[0076] The conductor (for example, conductive wire 55) is attached to the first earthing structure section 16a using a fastening element 56 such as a screw at a distal end of the first earthing structure section 16a relative to the outer edge section 11a of the first earthing structure 11 (outer edge section 10c of insulating substrate 10) (a proximal end of the first earthing structure section 16a relative to the outer edge section 11b of the first earthing structure 11).

[0077] The second grounding structure section 16b is connected to the first grounding structure section 16a in an intermediate region of the first grounding structure section 16a, exclusively at both ends of the first grounding structure section 16a in the longitudinal direction of the first grounding structure section 16a. The second grounding structure section 16b projects from the first grounding structure section 16a towards the first grounding structure 11. The direction of the projection of the second grounding structure section 16b from the first grounding structure section 16a is, for example, the first direction (x-direction).

[0078] The second grounding structure section 16b is separate from the first grounding structure 11. The second grounding structure section 16b is directly opposite the first grounding structure 11 in a plan view of the first main surface 10a of insulating substrate 10. In other words, in a plan view of the first main surface 10a of insulating substrate 10, the circuit board 9 contains no conductive structure between the first grounding structure 11 and the second grounding structure section 16b. The second grounding structure section 16b extends inside the recess 12 of the first grounding structure 11.

[0079] The first integrated circuit chip 40 in the present embodiment is similar to the first integrated circuit chip 40 in the first embodiment, but differs from the first integrated circuit chip 40 in the first embodiment in the following points. In the present embodiment, the first grounding terminal 42c is opposite the second grounding structure section 16b in the second direction (y-direction).

[0080] The capacitor 50 is connected to the first grounding structure 11 and the second grounding structure section 16b. In a plan view of the first main surface 10a of insulating substrate 10, the capacitor 50 is arranged on the straight line 50a, which defines the shortest distance between the first grounding terminal 42c and the second grounding structure section 16b. The straight line 50a can extend in a direction that differs from the direction of the projection (for example, the first direction (x-direction)) of the second grounding structure section 16b from the first grounding structure section 16a. For example, the straight line 50a can extend along the second direction (y-direction).

[0081] The circuit board 1b in the present embodiment achieves the following effects similar to the effects of the circuit board 1 in the first embodiment.

[0082] In the printed circuit board 1b of the present embodiment, the second grounding structure 15 comprises the first grounding structure section 16a and the second grounding structure section 16b. The second grounding structure section 16b projects from the first grounding structure section 16a to the first grounding structure 11. The first grounding structure 11 has a recess 12 that accommodates the second grounding structure section 16b. In a top view of the first main surface 10a of insulating substrate 10, the first grounding terminal 42c is opposite the second grounding structure section 16b. The first capacitor (capacitor 50) is connected to the first earthing structure 11 and the second earthing structure section 16b and is arranged on the straight line 50a which defines the shortest distance between the first earthing terminal 42c and the second earthing structure section 16b in a plan view of the first main surface 10a of insulating substrate 10.

[0083] Thus, electromagnetic noise from the electrical cable 30 into the first integrated circuit chip 40 does not propagate to the entire first grounding structure 11, but flows through the first capacitor (capacitor 50) into the second grounding structure 15 without changing the orientation of the first integrated circuit chip 40. This can lead to a malfunction or electrical breakdown of an electronic component electrically connected to the first grounding structure 11 (first integrated circuit chip 40) and another electronic component other than the first integrated circuit chip 40 (for example, an active electronic component such as integrated circuit chip 40b (see figure). Fig. 4) or a light-emitting diode)), can be prevented. Third embodiment

[0084] With reference to Fig. Section 12 describes a printed circuit board 1c in a third embodiment. The printed circuit board 1c in the present embodiment has a similar configuration to the printed circuit board 1 in the first embodiment, but differs mainly in the following points.

[0085] In the present embodiment, the second earthing structure 15 includes a first earthing structure section 16a and a second earthing structure section 16b.

[0086] The first earthing structure section 16a in the present embodiment is similar to the first earthing structure section 16a in the second embodiment.

[0087] The second earthing structure section 16b in the present embodiment is similar to the second earthing structure section 16b in the second embodiment, but differs from the second earthing structure section 16b in the second embodiment in the following points.

[0088] The second grounding structure section 16b extends along the outer edge section 11a of the first grounding structure 11. The second grounding structure section 16b extends, for example, along the first direction (x-direction). The second grounding structure section 16b may, for example, have a strip shape. The longitudinal direction of the second grounding structure section 16b is, for example, the first direction (x-direction). The lateral direction of the second grounding structure section 16b is, for example, the second direction (y-direction). The second grounding structure section 16b is connected to the first grounding structure section 16a at a proximal end of the first grounding structure section 16a relative to the outer edge section 11a of the first grounding structure 11 (outer edge section 10c of insulating substrate 10). In a top view of the first main surface 10a of insulating substrate 10, the second grounding structure 15 has, for example, the shape of the letter L.

[0089] The second grounding structure section 16b is separated from the first grounding structure 11 (outer edge section 11a). More precisely, the second grounding structure section 16b is separated from the first grounding structure 11 (outer edge section 11a) in the second direction (y-direction). The second grounding structure section 16b is directly opposite the first grounding structure 11 (outer edge section 11a) in a top view of the first main surface 10a of insulating substrate 10. In other words, in a top view of the first main surface 10a of insulating substrate 10, the printed circuit board 9 contains no conductive structure between the first grounding structure 11 (outer edge section 11a) and the second grounding structure section 16b.

[0090] The printed circuit board 9 further contains a second signal conductor structure 13d. The second signal conductor structure 13d is formed, for example, from a conductive material such as copper or aluminum. The second signal conductor structure 13d is provided, for example, on the first main surface 10a. The second signal conductor structure 13d can be formed inside insulating substrate 10. The second signal conductor structure 13d is separated from and insulated from the first grounding structure 11 and the second grounding structure 15. The second signal conductor structure 13d corresponds to the second cable signal wiring 35d.

[0091] Connector 20 further includes a second connector signal wiring 25d and terminals 23d and 24d. The second connector signal wiring 25d is located inside housing 21. The second connector signal wiring 25d corresponds to the second cable signal wiring 35d. The second connector signal wiring 25d is connected to terminals 23d and 24d. Terminal 24d is in contact with and electrically connected to the second signal conductor structure 13d.

[0092] The electrical cable 30 contains the second cable signal wiring 35d and the terminal 33d. The sheath 32 also accommodates the second cable signal wiring 35d. The second cable signal wiring 35d is connected to terminal 33d. When the electrical cable 30 is connected to the connector 20, terminal 33d comes into contact with terminal 23d. In this way, the second cable signal wiring 35d is electrically connected to the second connector signal wiring 25d via terminal 33d and terminal 23d.

[0093] The first grounding terminal 42c of the first integrated circuit chip 40 is opposite the first grounding structure section 16a in a top view of the first main surface 10a of insulating substrate 10.

[0094] Capacitor 50 is connected to the first grounding structure 11 and the first grounding structure section 16a. Capacitor 50 can be the only capacitor connected to the first grounding structure 11 and the first grounding structure section 16a. In a plan view of the first main surface 10a of insulating substrate 10, capacitor 50 is located on the straight line 50a, which defines the shortest distance between the first grounding terminal 42c and the first grounding structure section 16a. The straight line 50a extends, for example, along the first direction (x-direction).

[0095] The circuit board 1c further contains a second integrated circuit chip 45 and a capacitor 52.

[0096] The second integrated circuit chip 45 is, for example, but not limited to, an application-specific integrated circuit (ASIC) chip containing a communication circuit, or a power supply IC chip. The second integrated circuit chip 45 is mounted on the printed circuit board 9. The second integrated circuit chip 45 is located on the first grounding structure 11. In a top view of the first main surface 10a of the insulating substrate 10, the first integrated circuit chip 45 is located inside the outer edge of the first grounding structure 11. The second integrated circuit chip 45 includes a second grounding terminal 46c and a second signal terminal 46a.

[0097] The second signal terminal 46a corresponds to the second signal line structure 13d. The second signal terminal 46a is in contact with the second signal line structure 13d and electrically connected to it. The second signal terminal 46a is electrically connected to the second connector signal wiring 25d via the second signal line structure 13d. More precisely, the second signal terminal 46a is electrically connected to the second connector signal wiring 25d via the second signal line structure 13d and terminal 24d.

[0098] The second grounding terminal 46c is in contact with and electrically connected to the first grounding structure 11. The second grounding terminal 46c is opposite the second grounding structure 15 in a plan view of the first main surface 10a of insulating substrate 10. In particular, the second grounding terminal 46c is opposite the second grounding structure section 16b in a plan view of the first main surface 10a of insulating substrate 10. The shortest distance between the second grounding terminal 46c and the second grounding structure 15 (second grounding structure section 16b) is, for example, one-tenth or less of the electrical length inside the printed circuit board 9 of electromagnetic noise (for example, general-mode noise) from the connector 20.The shortest distance between the second earthing terminal 46c and the second earthing structure 15 (second earthing structure section 16b) can be one twentieth or less of the electrical length, one fiftieth or less of the electrical length, or one hundredth or less of the electrical length.

[0099] Capacitor 52 is, for example, a multilayer ceramic capacitor or an electrolytic aluminum capacitor. Capacitor 52 is mounted on circuit board 9. Capacitor 52 is connected to the first grounding structure 11 and the second grounding structure 15 (second grounding structure section 16b). Capacitor 52 can be the only capacitor connected to the first grounding structure 11 and the second grounding structure section 16b.

[0100] The capacitance of capacitor 52 is, for example, 0.5 µF or more. The capacitance of capacitor 52 can be, for example, 0.9 µF or more.

[0101] Thus, an excessive increase in the impedance of capacitor 52 for high-frequency electromagnetic noise (for example, electromagnetic noise with a frequency of 1 MHz or higher) from a typical electronic device is prevented. The high-frequency electromagnetic noise from the electrical cable 30 into the first grounding structure 11 flows easily from the first grounding structure 11 through capacitor 52 to the second grounding structure 15 (second grounding structure section 16b).Variation in the potential of the first grounding structure 11 resulting from high-frequency electromagnetic noise is suppressed, and malfunction or electrical breakdown of an electronic component electrically connected to the first grounding structure 11 (first integrated circuit chip 40 and an electronic component other than the first integrated circuit chip 40 (for example, an active electronic component such as integrated circuit chip 40b (see . Fig. 4) or a light-emitting diode)), can be prevented.

[0102] The capacitance of capacitor 52 is, for example, 5.0 µF or less. The capacitance of capacitor 52 can be, for example, 2.0 µF or less, or it can be 1.1 µF or less.

[0103] This prevents an excessive drop in the impedance of capacitor 52 due to low-frequency electromagnetic noise (for example, electromagnetic noise of 100 kHz or lower) resulting from lighting or the like. Capacitor 52, with a capacitance of 5.0 µF or less, prevents the low-frequency electromagnetic noise propagating through the electrical cable 30 from flowing from the second grounding structure 15 (second grounding structure section 16b) through the capacitor 52 into the first grounding structure 11, and allows the low-frequency electromagnetic noise to escape to the outside of the circuit board 1 (for example, reference potential 59).Variation in the potential of the first grounding structure 11 resulting from low-frequency electromagnetic noise is suppressed, and malfunction or electrical breakdown of an electronic component electrically connected to the first grounding structure 11 (first integrated circuit chip 40 and an electronic component other than the first integrated circuit chip 40 (for example, an active electronic component such as integrated circuit chip 40b (see . Fig. 4) or a light-emitting diode)), can be prevented.

[0104] Furthermore, since the capacitance of capacitor 52 is 5.0 µF or less, a capacitor with a high voltage rating (for example, a voltage rating of 500 V or higher) can be used as capacitor 52. Electromagnetic noise flowing from the first grounding structure 11 to the second grounding structure 15 (second grounding structure section 16b) may be increased.

[0105] In a plan view of the first main surface 10a of insulating substrate 10, the capacitor 52 is arranged on a straight line 52 that defines the shortest distance between the second grounding terminal 46c and the second grounding structure 15 (second grounding structure section 16b). The straight line 52a can extend in a direction different from the straight line 50a. For example, the straight line 52a extends along the second direction (y-direction).

[0106] The circuit board 1c in the present embodiment achieves the following effects in addition to the effects of the circuit board 1 in the first embodiment.

[0107] In the present embodiment, the printed circuit board 1c further includes the second integrated circuit chip 45 and a second capacitor (for example, capacitor 52). The printed circuit board 9 further includes the second signal conductor structure 13d. The connector 20 further includes the second connector signal wiring 25d, which is provided inside the housing 21. The second integrated circuit chip 45 is placed on the printed circuit board 9. The second integrated circuit chip 45 includes the second grounding terminal 46c and the second signal terminal 46a. The second signal terminal 46a is electrically connected to the second connector signal wiring 25d via the second signal conductor structure 13d. The second grounding terminal 46c is electrically connected to the first grounding structure 11 and is opposite the second grounding structure 15 in a top view of the first main surface 10a of insulating substrate 10.The second capacitor is mounted on the circuit board 9. The second capacitor is connected to the first grounding structure 11 and the second grounding structure 15 and is arranged on the straight line 52a, which defines the shortest distance between the second grounding terminal 46c and the second grounding structure 15 in a plan view of the first main surface 10a of insulating substrate 10.

[0108] Thus, electromagnetic noise from the electrical cable 30 into the second integrated circuit chip 45 does not propagate to the entire first grounding structure 11, but flows through the second capacitor (for example, capacitor 52) into the second grounding structure 15. This can lead to a malfunction or electrical breakdown of an electronic component electrically connected to the first grounding structure 11 (first integrated circuit chip 40, second integrated circuit chip 45, and an electronic component other than the first integrated circuit chip 40 and second integrated circuit chip 45 (for example, an active electronic component such as integrated circuit chip 40b (see figure). Fig. 4) or a light-emitting diode)), can be prevented.

[0109] In the printed circuit board 1c of the present embodiment, in a plan view of the first main surface 10a of insulating substrate 10, the first grounding structure 11 comprises a first outer edge section (outer edge section 11a) and a second outer edge section (outer edge section 11c). The second outer edge section is connected to the first outer edge section and extends in a direction different from that of the first outer edge section. The second grounding structure 15 comprises the first grounding structure section 16a and the second grounding structure section 16b. The first grounding structure section 16a extends along the second outer edge section. The second grounding structure section 16b extends along the first outer edge section and is connected to the first grounding structure section 16a.The first capacitor (for example, capacitor 50) is connected to the first grounding structure 11 and the first grounding structure section 16a and is arranged on the straight line 50a, which defines the shortest distance between the first grounding terminal 42c and the first grounding structure section 16a in a plan view of the first main surface 10a of insulating substrate 10. The second capacitor (for example, capacitor 52) is connected to the first grounding structure 11 and the second grounding structure section 16b and is arranged on the straight line 52a, which defines the shortest distance between the second grounding terminal 46c and the second grounding structure section 16b in a plan view of the first main surface 10a of insulating substrate 10.

[0110] Thus, electromagnetic noise from the electrical cable 30 into the first integrated circuit chip 40 and second integrated circuit chip 45 does not propagate to the entire first grounding structure 11, but flows through the first capacitor (for example, capacitor 50) and the second capacitor (for example, capacitor 52) into the second grounding structure 15. This can lead to a malfunction or electrical breakdown of an electronic component electrically connected to the first grounding structure 11 (first integrated circuit chip 40, second integrated circuit chip 45, and an electronic component other than the first integrated circuit chip 40 and second integrated circuit chip 45 (for example, an active electronic component such as integrated circuit chip 40b (see Fig. 4) or a light-emitting diode)), can be prevented. Fourth embodiment

[0111] With reference to Fig. 13 and Fig. Section 14 describes a printed circuit board 1d in a fourth embodiment. The printed circuit board 1d in the present embodiment has a similar configuration to the printed circuit board 1 in the first embodiment, but differs mainly in the following points.

[0112] In the present embodiment, the printed circuit board 9 is, for example, a double-sided printed circuit board. More precisely, the printed circuit board 9 further comprises a third grounding structure 71, a fourth grounding structure 75, a second signal line structure 13d, at least one first conductive via 73 and a second conductive via 77.

[0113] The third grounding structure 71 is formed, for example, from a conductive material such as copper or aluminum. The third grounding structure 71 is electrically connected to the second grounding terminal 46c of the second integrated circuit chip 45 and provides a reference potential to the second integrated circuit chip 45. The third grounding structure 71 is provided, for example, on the second main surface 10b. In a top view of the first main surface 10a (second main surface 10b) of insulating substrate 10, the third grounding structure 71 overlaps the first grounding structure 11. In particular, in a top view of the first main surface 10a (second main surface 10b) of insulating substrate 10, the third grounding structure 71 can completely overlap the first grounding structure 11. In a top view of the second main surface 10b of insulating substrate 10, the third earthing structure 71 is arranged in the middle of insulating substrate 10 relative to the fourth earthing structure 75.

[0114] In a plan view of the second main surface 10b of insulating substrate 10, the third grounding structure 71 has a wider area than the fourth grounding structure 75. In other words, in a plan view of the first main surface 10a of insulating substrate 10, the third grounding structure 71 has a greater width than the fourth grounding structure 75. The third grounding structure 71 has a larger cross-sectional area than the fourth grounding structure 75. Thus, the third grounding structure 71 has a lower residual inductance than the fourth grounding structure 75. The cross-sectional area of ​​the third grounding structure 71, for example, denotes the area of ​​the third grounding structure 71 in a cross-section perpendicular to the first main surface 10a of insulating substrate 10 and the longitudinal direction of the third grounding structure 71.The cross-sectional area of ​​the fourth earthing structure 75, for example, denotes the area of ​​the fourth earthing structure 75 in a cross-section perpendicular to the first main surface 10a of insulating substrate 10 and the longitudinal direction of the fourth earthing structure 75.

[0115] In a plan view of the first main surface 10a of insulating substrate 10, the third grounding structure 71 includes an outer edge section 71a, an outer edge section 71b opposite outer edge section 71a, and an outer edge section 71c. Outer edge section 71a is opposite outer edge section 10c of insulating substrate 10. For example, outer edge section 71a is the section closest to outer edge section 10c of insulating substrate 10 in the outer edge of the third grounding structure 71. Outer edge section 71b is, for example, the section furthest from outer edge section 10c of insulating substrate 10 in the outer edge of the third grounding structure 71. Outer edge sections 71a and 71b extend, for example, along the first direction (x-direction). The outer edge section 71c is connected to the outer edge section 71a and outer edge section 71b.The outer boundary section 71c extends in a direction that differs from the outer boundary sections 71a and 71b. For example, the outer boundary section 71c extends along the second direction (y-direction).

[0116] At least one first conductive via 73 extends along the direction in which the first main surface 10a and the second main surface 10b are separated from each other, i.e., the thickness direction of the insulating substrate 10 (third direction (z-direction)). At least one first conductive via 73 is connected to the first grounding structure 11 and the third grounding structure 71. At least one first conductive via 73 can consist of several first conductive vias 73. In other words, the third grounding structure 71 can be electrically connected to the first grounding structure 11 by several first conductive vias 73.

[0117] In a top view of the first main surface 10a (second main surface 10b) of insulating substrate 10, at least one first conductive via 73 can be arranged near the first grounding terminal 42c of the first integrated circuit chip 40 and the second grounding terminal 46c of the second integrated circuit chip 45.

[0118] In a top view of the first main surface 10a (second main surface 10b) of insulating substrate 10, the distance between at least one first conductive via 73 and the first grounding terminal 42c is, for example, one hundredth or less of the electrical length inside the printed circuit board 9 from the connector 20. Thus, the potential difference between at least one first conductive via 73 and the first grounding terminal 42c resulting from electromagnetic noise is reduced, and a standing wave of electromagnetic noise in the first grounding structure 11 can be prevented.Variation in the potential of the first grounding structure 11 resulting from electromagnetic noise is suppressed, and malfunction or electrical breakdown of an electronic component electrically connected to the first grounding structure 11 (first integrated circuit chip 40 and an electronic component other than the first integrated circuit chip 40 (for example, an active electronic component such as integrated circuit chip 40b (see . Fig. 4) or a light-emitting diode)), can be prevented.

[0119] In a top view of the first main surface 10a (second main surface 10b) of insulating substrate 10, the distance between at least one first conductive via 73 and the second grounding terminal 46c is, for example, one hundredth or less of the electrical length inside the printed circuit board 9 from the connector 20. Thus, the potential difference between at least one first conductive via 73 and the second grounding terminal 46c resulting from electromagnetic noise is reduced, and a standing wave of electromagnetic noise in the third grounding structure 71 can be prevented.Variation in the potential of the third grounding structure 71 resulting from electromagnetic noise is suppressed, and malfunction or electrical breakdown of an electronic component electrically connected to the third grounding structure 71 (second integrated circuit chip 45 and an electronic component other than the second integrated circuit chip 45 (for example, an active electronic component such as an integrated circuit chip or a light-emitting diode)) can be prevented.

[0120] The fourth grounding structure 75 is, for example, made of a conductive material such as copper or aluminum. The fourth grounding structure 75 is, for example, provided on the second main surface 10b. In a top view of the first main surface 10a (second main surface 10b) of insulating substrate 10, the fourth grounding structure 75 overlaps the second grounding structure 15. In particular, in a top view of the first main surface 10a (second main surface 10b) of insulating substrate 10, the fourth grounding structure 75 can completely overlap the second grounding structure 15.

[0121] In a plan view of the second main surface 10b of insulating substrate 10, the fourth grounding structure 75 is located in an outer peripheral region of insulating substrate 10 relative to the third grounding structure 71. The fourth grounding structure 75 extends along the outer edge section 71c of the third grounding structure 71. The fourth grounding structure 75 extends, for example, along the second direction (y-direction). The fourth grounding structure 75 may, for example, have a strip shape. The longitudinal direction of the fourth grounding structure 75 is, for example, the second direction (y-direction). The lateral direction of the fourth grounding structure 75 is, for example, the first direction (x-direction).

[0122] The fourth grounding structure 75 is separated from the third grounding structure 71. More precisely, the fourth grounding structure 75 is separated from the third grounding structure 71 in the first direction (x-direction). The fourth grounding structure 75 is directly opposite the third grounding structure 71 (outer edge section 71c) in a top view of the second main surface 10b of insulating substrate 10. In other words, in a top view of the second main surface 10b of insulating substrate 10, the circuit board 9 contains no conductive structure between the third grounding structure 71 (outer edge section 71c) and the fourth grounding structure 75. There is no electronic component (excluding capacitor 52, as shown in Fig. 16) on the fourth earthing structure 75 or above the fourth earthing structure 75 in a plan view of the second main surface 10b of insulating substrate 10 (a plan view of the first main surface 10a of insulating substrate 10).

[0123] The fourth grounding structure 75 is electrically connected to a reference potential 59, such as ground potential. More precisely, the second conductive via 77 extends along the direction in which the first main surface 10a and the second main surface 10b are separated from each other, that is, the thickness direction of the insulating substrate 10 (third direction (z-direction)). The second conductive via 77 is connected to the second grounding structure 15 and the fourth grounding structure 75. The fourth grounding structure 75 is electrically connected to the second grounding structure 15 via the second conductive via 77. The fourth grounding structure 75 is connected to the reference potential 59 via a conductor, such as the conductive wire 55, the second grounding structure 15, and the second conductive via 77.For example, the second conductive via 77 is a hollow conductive element and part of the fastening element 56, such as the body of a screw, can be inserted or screwed into the hole of the second conductive via 77.

[0124] When the electrical cable 30 is connected to the connector 20, the fourth grounding structure 75 is electrically connected to the sheath 32 of the electrical cable 30 via terminal 24c, housing 21, connector body 31, and the second grounding structure 15. Alternatively, when the electrical cable 30 is connected to the connector 20, the fourth grounding structure 75 is electrically connected to the cable grounding wiring 35c of the electrical cable 30 via terminal 24c, connector grounding wire 25c, terminal 23c, terminal 33c, and the second grounding structure 15.

[0125] The second signal conductor structure 13d is, for example, made of a conductive material such as copper or aluminum. The second signal conductor structure 13d is, for example, located on the second main surface 10b. The second signal conductor structure 13d is separated from and insulated from the third grounding structure 71 and the fourth grounding structure 75. The second signal conductor structure 13d corresponds to the second cable signal wiring 35d.

[0126] The connector 20 further includes the second connector signal wiring 25d and terminals 23d and 24d. The connector 20 in the present embodiment is similar to the connector 20 in the third embodiment, but differs from the connector 20 in the third embodiment in the following points. Terminal 24d is in contact with and electrically connected to the second signal wiring structure 13d. Terminal 24d is, for example, inserted into a hole (not shown) provided in the insulating substrate 10. Terminal 24d can penetrate the insulating substrate 10.

[0127] The printed circuit board 1d further includes a second integrated circuit chip 45. The second integrated circuit chip 45 in the present embodiment is similar to the second integrated circuit chip 45 in the third embodiment, but differs from the second integrated circuit chip 45 in the third embodiment in the following points. The second integrated circuit chip 45 is arranged on the third grounding structure 71. In a top view of the second main surface 10b of insulating substrate 10 (a top view of the first main surface 10a of insulating substrate 10), the second integrated circuit chip 45 is arranged inside the outer edge of the third grounding structure 71. In a top view of the second main surface 10b of insulating substrate 10 (a top view of the first main surface 10a of insulating substrate 10), the second integrated circuit chip 45 can be arranged in the same position as the first integrated circuit chip 40.

[0128] The second signal pin 46a of the second integrated circuit chip 45 corresponds to the second signal line structure 13d. The second signal pin 46a is in contact with the second signal line structure 13d and electrically connected to it. The second signal pin 46a is electrically connected to the second connector signal wiring 25d via the second signal line structure 13d. More precisely, the second signal pin 46a is electrically connected to the second connector signal wiring 25d via the second signal line structure 13d and pin 24d.

[0129] The second grounding terminal 46c of the second integrated circuit chip 45 is in contact with and electrically connected to the third grounding structure 71. The second grounding terminal 46c is opposite the fourth grounding structure 75 in a top view of the second main surface 10b of insulating substrate 10 (a top view of the first main surface 10a of insulating substrate 10). The shortest distance between the second grounding terminal 46c and the fourth grounding structure 75 is, for example, one-tenth or less of the electrical length inside the circuit board 9 from the connector 20. The shortest distance between the second grounding terminal 46c and the fourth grounding structure 75 could be one-twentieth or less of the electrical length, one-fiftieth or less of the electrical length, or one-hundredth or less of the electrical length.

[0130] With reference to Fig. 15 and Fig. Section 16 describes a printed circuit board 1e in a modification of the present embodiment. The printed circuit board 1e has a similar configuration to the printed circuit board 1d, but differs mainly in the following points.

[0131] The circuit board 1e further contains a capacitor 52. The capacitor 52 in the modification of the present embodiment is similar to the capacitor 52 in the third embodiment, but differs from the capacitor 52 in the third embodiment in the following points.

[0132] Capacitor 52 is connected to the third grounding structure 71 and the fourth grounding structure 75. Capacitor 52 can be the only capacitor connected to the third grounding structure 71 and the fourth grounding structure 75. In a plan view of the first main surface 10a of insulating substrate 10, capacitor 52 is positioned along a straight line 52a that defines the shortest distance between the second grounding terminal 46c and the fourth grounding structure 75. The straight line 52a extends, for example, along the first direction (x-direction). In a plan view of the first main surface 10a (second main surface 10b), capacitor 52 can be positioned in the same location as capacitor 50.

[0133] The printed circuit board 1d, 1e in the present embodiment achieves the following effects similar to the effects of the printed circuit board 1c in the third embodiment.

[0134] The printed circuit board 1d, 1e in the present embodiment further includes the second integrated circuit chip 45. The insulating substrate 10 contains the second main area 10b opposite the first main area 10a. The printed circuit board 9 further includes the third grounding structure 71, fourth grounding structure 75, second signal line structure 13d, at least one first conductive via 73, and a second conductive via 77. The fourth grounding structure 75 is separated from the third grounding structure 71 and is located directly opposite the third grounding structure 71 in a top view of the first main area 10a of the insulating substrate 10. The second signal line structure 13d is isolated from the third grounding structure 71 and the fourth grounding structure 75.At least one first conductive via 73 is connected to the first grounding structure 11 and the third grounding structure 71 and extends in the direction separating the first main surface 10a and the second main surface 10b. The second conductive via 77 is connected to the second grounding structure 15 and the fourth grounding structure 75 and extends in the direction separating the first main surface 10a and the second main surface 10b. The connector 20 further includes the second connector signal wiring 25d, which is provided inside the housing 21. The second integrated circuit chip 45 includes the second grounding terminal 46c and the second signal terminal 46a. The second grounding terminal 46c is electrically connected to the third grounding structure 71 and is opposite the fourth grounding structure 75 in a top view of the first main surface 10a of insulating substrate 10.The second signal terminal 46a is electrically connected to the second connector signal wiring 25d via the second signal line structure 13d.

[0135] Thus, electromagnetic noise from the electrical cable 30 into the second integrated circuit chip 45 does not propagate to the entire third grounding structure 71, but flows through the first capacitor (capacitor 50) into the second grounding structure 15. Malfunction or electrical breakdown of an electronic component electrically connected to the third grounding structure 71 (second integrated circuit chip 45 and a different electronic component than the second integrated circuit chip 45 (for example, an active electronic component such as an integrated circuit chip or a light-emitting diode)) can be prevented.

[0136] In the printed circuit board 1d, 1e in the present embodiment, at least one first conductive via 73 consists of several first conductive vias 73.

[0137] Thus, the inductance of the conductor (multiple first conductive vias 73) connecting the first grounding structure 11 and the third grounding structure 71 is reduced. Electromagnetic noise from the electrical cable 30 to the second integrated circuit chip 45 does not propagate through the entire third grounding structure 71, but instead flows through multiple first conductive vias 73, the first grounding structure 11, and the first capacitor (capacitor 50) into the second grounding structure 15. Malfunction or electrical breakdown of an electronic component electrically connected to the third grounding structure 71 (second integrated circuit chip 45 and a different electronic component than the second integrated circuit chip 45 (for example, an active electronic component such as an integrated circuit chip or a light-emitting diode)) can be prevented.

[0138] The printed circuit board 1e in the present embodiment further includes a second capacitor (for example, capacitor 52) mounted on the printed circuit board 9. The second capacitor is connected to the third grounding structure 71 and the fourth grounding structure 75 and is arranged on the straight line 52a, which defines the shortest distance between the second grounding terminal 46c and the fourth grounding structure 75 in a top view of the first main surface 10a of insulating substrate 10.

[0139] Thus, electromagnetic noise from the electrical cable 30 into the second integrated circuit chip 45 does not propagate to the entire third grounding structure 71, but also flows through the second capacitor (for example, capacitor 52) into the fourth grounding structure 75. Malfunction or electrical breakdown of an electronic component electrically connected to the third grounding structure 71 (second integrated circuit chip 45 and a different electronic component than the second integrated circuit chip 45 (for example, an active electronic component such as an integrated circuit chip or a light-emitting diode)) can be prevented.

[0140] In the printed circuit board 1e in the present embodiment, in a top view of the first main surface 10a of insulating substrate 10, the second capacitor (for example capacitor 52) is arranged in the same position as the first capacitor (for example capacitor 50).

[0141] Thus, electromagnetic noise from the electrical cable 30 into the first integrated circuit chip 40 and second integrated circuit chip 45 does not propagate to the entire first grounding structure 11 and the entire third grounding structure 71, but instead flows through the first capacitor (for example, capacitor 50) and the second capacitor (for example, capacitor 52) into the second grounding structure 15 and fourth grounding structure 75. This can result in a malfunction or electrical breakdown of an electronic component electrically connected to the first grounding structure 11 (first integrated circuit chip 40) and another electronic component other than the first integrated circuit chip 40 (for example, an active electronic component such as integrated circuit chip 40b (see Fig. 4) or a light-emitting diode)), and an electronic component that is electrically connected to the third grounding structure 71 (second integrated circuit chip 45 and a different electronic component than the second integrated circuit chip 45 (for example, an active electronic component such as an integrated circuit chip or a light-emitting diode)), can be prevented. Fifth embodiment

[0142] With reference to Fig. In section 17, a printed circuit board 1f in a fifth embodiment is described. The printed circuit board 1f in the present embodiment has a similar configuration to the printed circuit board 1 in the first embodiment, but differs mainly in the following points.

[0143] In the present embodiment, the second earthing structure 15 includes a first earthing structure section 16a and a second earthing structure section 16b.

[0144] The first grounding structure section 16a in the present embodiment is similar to the first grounding structure section 16a in the third embodiment. The first grounding structure section 16a is arranged at a gap d1 of the first grounding structure 11 (outer edge section 11c).

[0145] The second earthing structure section 16b is similar to the second earthing structure section 16b in the third embodiment, but differs in the following points.

[0146] The second grounding structure section 16b is connected to the first grounding structure section 16a at a distal end of the first grounding structure section 16a relative to the outer edge section 11a of the first grounding structure 11 (outer edge section 10c of insulating substrate 10). The second grounding structure section 16b is separated from the first grounding structure 11 (outer edge section 11b). More precisely, the second grounding structure section 16b is separated from the first grounding structure 11 (outer edge section 11b) in the second direction (y-direction). The second grounding structure section 16b is arranged at a gap d2 from the first grounding structure 11 (outer edge section 11b).

[0147] The second grounding structure section 16b is directly opposite the first grounding structure 11 (outer edge section 11b) in a plan view of the first main surface 10a of insulating substrate 10. In other words, in a plan view of the first main surface 10a of insulating substrate 10, the printed circuit board 9 contains no conductive structure between the first grounding structure 11 (outer edge section 11b) and the second grounding structure section 16b. No electronic component can be located on or above the second grounding structure section 16b in a plan view of the second main surface 10b of insulating substrate 10 (a plan view of the first main surface 10a of insulating substrate 10).

[0148] The gap d1 between the first earthing structure section 16a and the first earthing structure 11 is smaller than the gap d2 between the second earthing structure section 16b and the first earthing structure 11.

[0149] The conductor (for example, conductive wire 55) is attached to the second earthing structure section 16b, using a fastening element 56 such as a screw, at a distal end of the second earthing structure section 16b relative to the first earthing structure section 16a.

[0150] The capacitor 50 in the present embodiment is connected to the first earthing structure 11 and the first earthing structure section 16a and is arranged on the straight line 50a which defines the shortest distance between the first earthing terminal 42c and the first earthing structure section 16a in a plan view of the first main surface 10a of insulating substrate 10, similar to the capacitor 50 in the third embodiment.

[0151] With reference to Fig. Section 18 describes the operation of the printed circuit board 1f in the present embodiment.

[0152] In the present embodiment, the gap d1 between the first grounding structure section 16a and the first grounding structure 11 is smaller than the gap d2 between the second grounding structure section 16b and the first grounding structure 11. Thus, electromagnetic noise from the electrical cable 30 into the first integrated circuit chip 40 does not flow directly from the first grounding structure 11 into the second grounding structure section 16b, but flows through the capacitor 50 into the first grounding structure section 16a (see noise path 64 in Figure 1). Fig. 18) Propagation of electromagnetic noise to the entire first grounding structure 11 can be prevented. Malfunction or electrical breakdown of an electronic component electrically connected to the first grounding structure 11 (first integrated circuit chip 40) and an electronic component other than the first integrated circuit chip 40 (for example, an active electronic component such as integrated circuit chip 40b (see Fig. 4) or a light-emitting diode)), can be prevented.

[0153] Furthermore, even if the capacitor 51, which is electrically connected to the second grounding structure section 16b and the first grounding structure 11, is arranged between the second grounding structure section 16b and the first grounding structure 11, it is possible to reduce electromagnetic noise that propagates over the entire first grounding structure 11 and from the first grounding structure 11 to the second grounding structure section 16b via capacitor 51 (see noise path 65 in Fig. 18) flows.

[0154] For the following reason, it is preferred that the capacitor 51, which is electrically connected to the second grounding structure section 16b and the first grounding structure 11, is not located between the second grounding structure section 16b and the first grounding structure 11: some electromagnetic noise from the electrical cable 30 into the first integrated circuit chip 40 can sometimes flow through capacitor 51 from the first grounding structure 11 into the second grounding structure section 16b (see noise path 65 in Figure 1). Fig. 18). A portion of electromagnetic noise propagates over the entire first grounding structure 11. An electronic component electrically connected to the first grounding structure 11 (first integrated circuit chip 40) and another electronic component other than the first integrated circuit chip 40 (for example, an active electronic component such as integrated circuit chip 40b (see Fig. 4) or a light-emitting diode)) may have a malfunction or an electrical breakdown.

[0155] The circuit board 1f in the present embodiment achieves the following effects in addition to the effects of the circuit board 1 in the first embodiment.

[0156] In the printed circuit board 1f of the present embodiment, in a top view of the first main surface 10a of insulating substrate 10, the first grounding structure 11 comprises a first outer edge section (for example, outer edge section 11b) and a second outer edge section (for example, outer edge section 11c). The second outer edge section is connected to the first outer edge section and extends in a direction different from that of the first outer edge section. The second grounding structure 15 comprises a first grounding structure section 16a and a second grounding structure section 16b. The first grounding structure section 16a extends along the second outer edge section. The second grounding structure section 16b extends along the first outer edge section and is connected to the first grounding structure section 16a.The first capacitor (capacitor 50) is connected to the first grounding structure 11 and the first grounding structure section 16a and is arranged on the straight line 50a, which defines the shortest distance between the first grounding terminal 42c and the first grounding structure section 16a in a plan view of the first main surface 10a of insulating substrate 10. The gap d1 between the first grounding structure section 16a and the first grounding structure 11 is smaller than the gap d2 between the second grounding structure section 16b and the first grounding structure 11.

[0157] Thus, electromagnetic noise from the electrical cable 30 into the first integrated circuit chip 40 does not flow directly from the first grounding structure 11 into the second grounding structure section 16b, but instead flows through the capacitor 50 into the first grounding structure section 16a. Propagation of electromagnetic noise to the entire first grounding structure 11 can be prevented. This prevents malfunction or electrical breakdown of an electronic component electrically connected to the first grounding structure 11 (first integrated circuit chip 40) and another electronic component other than the first integrated circuit chip 40 (for example, an active electronic component such as integrated circuit chip 40b (see figure). Fig. 4) or a light-emitting diode)), can be prevented. Sixth embodiment

[0158] With reference to Fig. Section 19 describes a printed circuit board 1g in a sixth embodiment. The printed circuit board 1g in the present embodiment has a similar configuration to the printed circuit board 1b in the second embodiment, but differs mainly in the following points.

[0159] The first grounding structure 11 in the present embodiment is similar to the first grounding structure 11 in the second embodiment, but differs from the first grounding structure 11 in the second embodiment in the following points. The recess 12 (see Fig. 11) in the second embodiment is not provided in the first grounding structure 11 in the present embodiment. In other words, the first grounding structure 11 in the present embodiment is similar to the first grounding structure 11 in the first embodiment.

[0160] In the present embodiment, the second grounding structure 15 comprises a first grounding structure section 16a and a second grounding structure section 16b. The first grounding structure section 16a in the present embodiment is similar to the first grounding structure section 16a in the second embodiment. The first grounding structure section 16a is arranged at a gap d3 of the first grounding structure 11 (outer edge section 11c).

[0161] The second grounding structure section 16b in the present embodiment is similar to the second grounding structure section 16b in the second embodiment, but differs from it in the following ways. The second grounding structure section 16b is separated from the first grounding structure 11 (outer edge section 11c) in the first direction (x-direction). The second grounding structure section 16b is arranged at a gap d4 from the first grounding structure 11 (outer edge section 11c). The gap d4 between the second grounding structure section 16b and the first grounding structure 11 in the direction of the projection of the second grounding structure section 16b from the first grounding structure section 16a (for example, in the first direction (x-direction)) is smaller than the gap d3 between the first grounding structure section 16a and the first grounding structure 11 in the direction of the projection.

[0162] The first integrated circuit chip 40 in the present embodiment is similar to the first integrated circuit chip 40 in the second embodiment, but differs from the first integrated circuit chip 40 in the second embodiment in the following points. The first grounding terminal 42c in the present embodiment is opposite the second grounding structure section 16b in the first direction (x-direction).

[0163] The capacitor 50 in the present embodiment is similar to the capacitor 50 in the second embodiment, but differs from the capacitor 50 in the second embodiment in the following points. The straight line 50a, which defines the shortest distance between the first grounding terminal 42c and the second grounding structure section 16b, extends along the direction of the projection of the second grounding structure section 16b from the first grounding structure section 16a (for example, the first direction (x-direction)). The capacitor 50 is arranged on this straight line 50a. In other words, the capacitor 50 is connected to the first grounding structure 11 and the second grounding structure 15 (second grounding structure section 16b) at a point where there is a relatively small gap between the first grounding structure 11 and the second grounding structure 15 within the second grounding structure 15.

[0164] The circuit board 1g in the present embodiment achieves the following effects in addition to the effects of the circuit board 1 in the first embodiment.

[0165] In the printed circuit board 1g of the present embodiment, the second grounding structure 15 comprises the first grounding structure section 16a and the second grounding structure section 16b. The second grounding structure section 16b projects from the first grounding structure section 16a to the first grounding structure 11. The gap d4 between the second grounding structure section 16b and the first grounding structure 11 in the direction of the projection of the second grounding structure section 16b from the first grounding structure section 16a is smaller than the gap d3 between the first grounding structure section 16a and the first grounding structure 11 in the direction of the projection. In a top view of the first main surface 10a of insulating substrate 10, the first grounding terminal 42c is opposite the second grounding structure section 16b.The first capacitor (capacitor 50) is connected to the first grounding structure 11 and the second grounding structure section 16b and is arranged on the straight line 50a which defines the shortest distance between the first grounding terminal 42c and the second grounding structure section 16b, and extends along the direction of the projection of the second grounding structure section 16b.

[0166] This further prevents electromagnetic noise from propagating from the electrical cable 30 in the first integrated circuit chip 40 to the entire first grounding structure 11. This prevents malfunction or electrical breakdown of an electronic component electrically connected to the first grounding structure 11 (first integrated circuit chip 40) and another electronic component other than the first integrated circuit chip 40 (for example, an active electronic component such as integrated circuit chip 40b (see Fig. 4) or a light-emitting diode)), can be prevented. Seventh embodiment

[0167] With reference to Fig. Section 20 describes a printed circuit board 1h in a seventh embodiment. The printed circuit board 1h in the present embodiment has a similar configuration to the printed circuit board 1c in the third embodiment, but differs mainly in the following points.

[0168] In the present embodiment, the housing 21 is a conductive housing. Electromagnetic noise flows into the circuit board 9 through the housing 21.

[0169] The second earthing structure 15 contains a first earthing structure section 16a and a second earthing structure section 16b.

[0170] The first grounding structure section 16a in the present embodiment is similar to the first grounding structure section 16a in the third embodiment, but differs from it in the following ways: The length of the first grounding structure section 16a in the present embodiment in the longitudinal direction (second direction (y-direction)) is shorter than the length of the first grounding structure section 16a in the third embodiment in the longitudinal direction. The first grounding structure section 16a is not in contact with the housing 21 and terminal 24c and is located far from the housing 21 and terminal 24c.

[0171] The second earthing structure section 16b in the present embodiment is similar to the second earthing structure section 16b in the third embodiment, but differs from the second earthing structure section 16b in the third embodiment in the following points.

[0172] The second grounding structure section 16b is separated from the first grounding structure section 16a. For example, the second grounding structure section 16b is separated from the first grounding structure section 16a in the longitudinal direction (second direction (y-direction)) of the first grounding structure section 16a. The second grounding structure section 16b extends along the outer edge section 11c of the first grounding structure 11. The second grounding structure section 16b extends, for example, in the second direction (y-direction). The second grounding structure section 16b may, for example, have a strip shape. The longitudinal direction of the second grounding structure section 16b is, for example, the second direction (y-direction). The lateral direction of the second grounding structure section 16b is, for example, the first direction (x-direction).

[0173] The second grounding structure section 16b is separated from the first grounding structure 11 (outer edge section 11c). More precisely, the second grounding structure section 16b is separated from the first grounding structure 11 (outer edge section 11c) in the first direction (x-direction). The second grounding structure section 16b is directly opposite the first grounding structure 11 (outer edge section 11c) in a top view of the first main surface 10a of insulating substrate 10. In other words, in a top view of the first main surface 10a of insulating substrate 10, the printed circuit board 9 contains no conductive structure between the first grounding structure 11 (outer edge section 11c) and the second grounding structure section 16b.

[0174] The second grounding structure section 16b is electrically connected to the conductive housing (housing 21). The second grounding structure section 16b can be in contact with the conductive housing or can be electrically connected to the conductive housing via terminal 24c.

[0175] The circuit board 1h further contains a capacitor 53. The capacitor 53 is, for example, a multilayer ceramic capacitor or an electrolytic aluminum capacitor. The capacitor 53 is mounted on the circuit board 9. The capacitor 53 is connected to the first grounding structure section 16a and the second grounding structure section 16b. The capacitor 53 can reflect electromagnetic noise from the conductive housing (housing 21) into the second grounding structure section 16b, thereby reducing or eliminating electromagnetic noise from the second grounding structure section 16b into the first grounding structure section 16a. The capacitor 53 can reduce or eliminate electromagnetic noise from the first grounding structure section 16a into the first grounding structure 11 via the capacitor 50.

[0176] With reference to Fig. 21 describes the operation of the circuit board 1h in the present embodiment with capacitor 53. Fig. Figure 21 shows the degree of coupling of electromagnetic noise to the first integrated circuit chip 40 in the present embodiment and the first embodiment when electromagnetic noise is applied to the electrical cable 30. The degree of coupling of electromagnetic noise to the first integrated circuit chip 40 is measured by bringing a probe for detecting electromagnetic noise into contact with the first signal terminals 42a, 42b of the first integrated circuit chip 40. It is evident that the degree of coupling of electromagnetic noise to the first integrated circuit chip 40 in the present embodiment is less than the degree of coupling of electromagnetic noise to the first integrated circuit chip 40 in the first embodiment.

[0177] The capacitance of capacitor 53 is, for example, 5.0 µF or less. The capacitance of capacitor 53 can be, for example, 2.0 µF or less, or 1.0 µF or less. This prevents an excessive drop in the impedance of capacitor 53 due to low-frequency electromagnetic noise (for example, electromagnetic noise with a frequency of 100 kHz or lower) resulting from lighting or the like. Capacitor 53 can reflect more low-frequency electromagnetic noise or further reduce or eliminate low-frequency electromagnetic noise from the first grounding structure section 16a and capacitor 50 into the first grounding structure 11.Variation in the potential of the first grounding structure 11 resulting from low-frequency electromagnetic noise is suppressed, and malfunction or electrical breakdown of an electronic component electrically connected to the first grounding structure 11 (first integrated circuit chip 40 and an electronic component other than the first integrated circuit chip 40 (for example, an active electronic component such as integrated circuit chip 40b (see . Fig. 4) or a light-emitting diode)), can be prevented.

[0178] The capacitance of capacitor 53 is, for example, 0.01 µF or more. This prevents an excessive increase in the impedance of capacitor 53 due to high-frequency electromagnetic noise (for example, electromagnetic noise with a frequency of 1 MHz or higher) resulting from a typical electronic device. High-frequency electromagnetic noise from the electrical cable 30 to the second grounding structure section 16b can be reflected by capacitor 53 and prevented from flowing into the first signal line structures 13a, 13b and the first grounding structure 11 due to parasitic capacitance inside the electrical cable 30 or parasitic capacitance inside the connector 20.Variation in the potential of the first grounding structure 11 resulting from high-frequency electromagnetic noise is suppressed, and malfunction or electrical breakdown of an electronic component electrically connected to the first grounding structure 11 (first integrated circuit chip 40 and an electronic component other than the first integrated circuit chip 40 (for example, an active electronic component such as integrated circuit chip 40b (see . Fig. 4) or a light-emitting diode)), can be prevented.

[0179] With reference to Fig. 22 describes a printed circuit board 1i in a modification of the present embodiment.

[0180] Circuit board 1i also contains a resistor 54. Resistor 54 is mounted on circuit board 9. More precisely, resistor 54 is connected to the first grounding structure section 16a and the second grounding structure section 16b. The second capacitor (for example, capacitor 53) and resistor 54 are arranged in parallel between the first grounding structure section 16a and the second grounding structure section 16b. Resistor 54 prevents circuit board 9 from being charged.

[0181] The impedance of resistor 54 is, for example, 10 kΩ or more. The reason for this is that if the impedance of resistor 54 is excessively low, low-frequency electromagnetic noise (for example, electromagnetic noise with a frequency of 100 kHz or lower), resulting from lighting or the like, will pass through resistor 54, and the effect of blocking low-frequency electromagnetic noise by capacitor 53 cannot be sufficiently achieved. The impedance of resistor 54 is, for example, 10 MΩ or less. The impedance of resistor 54 can be, for example, 1 MΩ or less. Thus, an excessive increase in the impedance of resistor 54 can be prevented. Resistor 54 can effectively prevent the circuit board 9 from being charged.

[0182] In the present embodiment, the circuit board 1h, 1i achieves the following effects in addition to the effects of the circuit board 1 in the first embodiment.

[0183] The printed circuit board 1h, 1i in the present embodiment further includes a second capacitor (capacitor 53) mounted on the printed circuit board 9. The housing 21 is a conductive housing. The second grounding structure 15 includes the first grounding structure section 16a and the second grounding structure section 16b, which is separate from the first grounding structure section 16a. The second grounding structure section 16b is electrically connected to the conductive housing. The first capacitor (for example, capacitor 50) is connected to the first grounding structure 11 and the first grounding structure section 16a and is arranged on the straight line 50a, which defines the shortest distance between the first grounding terminal 42c and the first grounding structure section 16a in a plan view of the first main surface 10a of insulating substrate 10. The second capacitor is connected to the first grounding structure section 16a and the second grounding structure section 16b.

[0184] The second capacitor (capacitor 53) can reflect electromagnetic noise from the conductive housing (housing 21) into the second grounding structure section 16b, thereby reducing or eliminating electromagnetic noise from the second grounding structure section 16b into the first grounding structure section 16a. The second capacitor can reduce or eliminate electromagnetic noise from the first grounding structure section 16a into the first grounding structure 11 through the first capacitor (capacitor 50). This can prevent malfunction or electrical breakdown of an electronic component electrically connected to the first grounding structure 11 (first integrated circuit chip 40) and another electronic component other than the first integrated circuit chip 40 (for example, an active electronic component such as integrated circuit chip 40b (see [reference])). Fig. 4) or a light-emitting diode)), can be prevented.

[0185] The circuit board 1i in the present embodiment further includes the resistor 54, which is mounted on the circuit board 9. The resistor 54 is connected to the first grounding structure section 16a and the second grounding structure section 16b. The second capacitor (capacitor 53) and the resistor 54 are arranged in parallel between the first grounding structure section 16a and the second grounding structure section 16b.

[0186] Resistor 54 can prevent the circuit board 1i from being charged. Malfunction or electrical breakdown of an electronic component mounted on the circuit board 1i (first integrated circuit chip 40) and another electronic component other than the first integrated circuit chip 40 (for example, an active electronic component such as integrated circuit chip 40b (see Fig. 4) or a light-emitting diode)), can be prevented. Eighth embodiment

[0187] With reference to Fig. In section 23, an electronic device 2j and a printed circuit board 1j in an eighth embodiment are described. The electronic device 2j and printed circuit board 1j in the present embodiment have a similar configuration to the electronic device 2 and printed circuit board 1 in the first embodiment, but differ mainly in the following points.

[0188] The electronic device 2j in the present embodiment includes the printed circuit board 1j in the present embodiment, instead of the printed circuit board 1 in the first embodiment. The printed circuit board 1j in the present embodiment further includes a heat sink 80 and heat transfer materials 83, 84 in addition to the printed circuit board 9 in the first embodiment. In this description, the heat transfer element is defined as an element made of a material with a thermal conductivity of 0.1 W / (m / K) or more.

[0189] The heat sink 80 contains, for example, a heat dissipation plate 81 and heat dissipation fins 82. The heat sink 80 (heat dissipation plate 81) is located opposite the first main surface 10a of the insulating substrate 10. The heat sink 80 (heat dissipation plate 81) is arranged such that it is separated from the first main surface 10a of the insulating substrate 10. The heat dissipation fins 82 are connected to the heat dissipation plate 81. More precisely, the heat dissipation fins 82 are formed on a front surface of the heat dissipation plate 81 opposite a rear surface of the heat dissipation plate 81 opposite the first main surface 10a of the insulating substrate 10.

[0190] The heat transfer material 83 is connected to the first integrated circuit chip 40 and the heat sink 80 (for example, heat dissipation plate 81). The heat transfer material 83 can be an insulating spacer or a conductive spacer. The heat transfer material 83 is, for example, thermal paste or a heat-dissipating plate. The thermal paste can, for example, be made of silicone resin containing a filler such as a magnetic filler. The heat transfer material 84 is connected to the second grounding structure 15 and the heat sink 80 (for example, heat dissipation plate 81). The heat transfer material 84 is a conductive spacer. The heat transfer material 84 is, for example, made of metal. The heat transfer material 84 can, for example, be a screw that fastens the heat sink 80 to the insulating substrate 10.

[0191] The heat sink 80 is separated from the connector 20. This prevents electromagnetic noise from entering the sheath 32 of the electrical cable 30 (see Fig. 2) be prevented from passing through the housing 21 (see Fig. 2) of the connector 20, the heat sink 80 and the heat transfer material 83 to go to the first integrated circuit chip 40 and an electronic component other than the first integrated circuit chip 40, which is electrically connected to the first grounding structure 11 (for example, an active electronic component such as integrated circuit chip 40b (see Fig. 4) or a light-emitting diode). Malfunction or electrical breakdown of an electronic component electrically connected to the first grounding structure 11 (first integrated circuit chip 40 and an electronic component other than the first integrated circuit chip 40) can be prevented.

[0192] In a modification of the present embodiment, the heat sink 80 can be in contact with the connector 20 (housing 21). If, for example, an electrical filter is provided inside the housing 21 of the connector 20, the temperature of the connector 20 can sometimes become high during operation of the electronic device 2j. The heat sink 80 is brought into contact with the connector 20 so that the heat sink 80 can cool the connector 20.

[0193] When the heat sink 80 is in contact with the connector 20 (housing 21), electromagnetic noise from the connector 20 can couple to the first integrated circuit chip 40 in the heat sink 80 due to a parasitic capacitance in the heat transfer material 83, and the first integrated circuit chip 40 and another electronic component other than the first integrated circuit chip 40 that is electrically connected to the first grounding structure 11 (for example, an active electronic component such as integrated circuit chip 40b (see Fig. 4) or a light-emitting diode) may malfunction or experience electrical breakdown. Since the height of the heat transfer material 83 is set to 1 mm or more, the parasitic capacitance in the heat transfer material 83 is reduced, and electromagnetic noise coupled to the first integrated circuit chip 40 and any other electronic component (other than the first integrated circuit chip 40) electrically connected to the first grounding structure 11 is reduced. Malfunction or electrical breakdown of an electronic component electrically connected to the first grounding structure 11 (first integrated circuit chip 40 and any other electronic component) can be prevented.

[0194] The heat transfer material 84, which acts as a conductive spacer, allows electromagnetic noise from the connector 20 (housing 21) to escape via the second grounding structure 15 into the heat sink 80 to the reference potential 59. This prevents malfunction or electrical breakdown of an electronic component electrically connected to the first grounding structure 11 (first integrated circuit chip 40 and any other electronic component besides the first integrated circuit chip 40).

[0195] The circuit board 1j in the present embodiment achieves the following effects in addition to the effects of the circuit board 1 in the first embodiment.

[0196] The printed circuit board 1j in the present embodiment further comprises the heat sink 80 and the heat transfer material 83. The heat sink 80 is located opposite the first main surface 10a and is arranged such that it is separated from the first main surface 10a. The heat transfer material 83 is connected to the first integrated circuit chip 40 and the heat sink 80. The heat sink 80 is separated from the connector 20.

[0197] Thus, the first integrated circuit chip 40 is cooled by the heat sink 80. Malfunction or thermal breakdown of the first integrated circuit chip 40 can be prevented. Furthermore, the flow of electromagnetic noise from the connector 20 into the heat sink 80 is prevented. Electromagnetic noise can be prevented from passing through the heat sink 80 and the heat transfer material 83 and into the first integrated circuit chip 40 and any other electronic component besides the first integrated circuit chip 40 that is electrically connected to the first grounding structure 11 (for example, an active electronic component such as integrated circuit chip 40b (see Fig.4) or a light-emitting diode). Malfunction or electrical breakdown of an electronic component electrically connected to the first grounding structure 11 (first integrated circuit chip 40 and an electronic component other than the first integrated circuit chip 40) can be prevented.

[0198] The printed circuit board 1j in the present embodiment further comprises the heat sink 80, a first heat transfer element (heat transfer material 83), and a second heat transfer element (heat transfer material 84). The heat sink 80 is located opposite the first main surface 10a and is arranged such that it is separated from the first main surface 10a. The heat sink 80 is in contact with the connector 20. The first heat transfer element is connected to the first integrated circuit chip 40 and the heat sink 80. The height of the first heat transfer element is 1 mm or more. The second heat transfer element is electrically conductive and is connected to the second grounding structure 15 and the heat sink 80.

[0199] Thus, the heat sink 80 can cool the connector 20. The parasitic capacitance in the first heat transfer element (heat transfer material 83) is reduced, and electromagnetic noise coupled to the first integrated circuit chip 40 is reduced. The second heat transfer element (heat transfer material 84) allows electromagnetic noise from the connector 20 (housing 21) to escape through the second grounding structure 15 into the heat sink 80 to the reference potential 59. Malfunction or electrical breakdown of an electronic component electrically connected to the first grounding structure 11 (first integrated circuit chip 40 and any other electronic component) can be prevented.

[0200] The first through eighth embodiments and modifications thereof disclosed herein should in every respect be regarded as illustrations and not as limitations. At least two of the first through eighth embodiments and modifications thereof disclosed herein may be combined, provided no contradiction arises. The scope of the present disclosure is not shown in the preceding description but in the claims, and it is intended that all modifications which are of the same meaning and equivalence to the claims are included here. LIST OF REFERENCE MARKS

[0201] 1, 1a, 1b, 1c, 1d, 1e, 1f, 1g, 1h, 1i, 1j Printed circuit board, 2, 2j Electronic device, 9 Printed circuit board, 10 Insulating substrate, 10a First main area, 10b Second main area, 10c, 11a, 11b, 11c Outer edge section, 11 First grounding structure, 12 Recess, 13a, 13b First signal line structure, 13d Second signal line structure, 15 Second grounding structure, 16a First grounding structure section, 16b Second grounding structure section, 20 Connector, 21 Housing, 22 Receiving section, 23a, 23b, 23c, 23d, 24a, 24b, 24c, 24d Connection, 25a, 25b First Connector signal wiring, 25c Connector ground wiring, 25d Second connector signal wiring, 30 Electrical cable, 31 Connector body, 32 Sheath, 33a, 33b, 33c, 33d Terminal, 35a, 35b First cable signal wiring, 35c Cable ground wiring, 35d Second cable signal wiring, 40 First integrated circuit chip, 40b Integrated circuit chip, 42a, 42b First signal terminal, 42c First ground terminal45 Second integrated circuit chip, 46a Second signal terminal, 46c Second ground terminal, 50, 51, 52, 53 Capacitor, 50a, 52a Straight line, 54 Resistor, 55 Conductive wire, 56 Mounting element, 57 Conductive rod, 59 Reference potential, 60 Package, 61, 64, 64a, 64b, 65 Noise path, 71 Third ground structure, 71a, 71b, 71c Outer edge section, 73 First conductive via, 75 Fourth ground structure, 77 Second conductive via, 80 Heat sink, 81 Heat dissipation plate, 82 Heat dissipation fins, 83, 84 Heat transfer material.

Claims

[1] Printed circuit board (1, 1a, 1b, 1c, 1d, 1e, 1f, 1g, 1h, 1i, 1j), comprising: a circuit board (9) comprising an insulating substrate (10) including a first main surface (10a), a first grounding structure (11), a second grounding structure (15) and a first signal line structure (13a, 13b); a first integrated circuit chip (40) mounted on the circuit board (9); a connector (20) mounted on the circuit board (9) and connectable to an electrical cable (30); and a first capacitor (50) mounted on the circuit board (9), wherein in a plan view of the first main surface (10a), the first grounding structure (11) has a wider surface than the second grounding structure (15), the second grounding structure (15) is separated from the first grounding structure (11) and is directly opposite the first grounding structure (11) in the plan view of the first main surface (10a), the first signal line structure (13a, 13b) is insulated from the first grounding structure (11) and the second grounding structure (15), the connector (20) includes a housing (21), a connector ground wiring (25c) provided inside the housing (21), and a first connector signal wiring (25a, 25b) provided inside the housing (21), the first integrated circuit chip (40) includes a first ground terminal (42c) and a first signal terminal (42a, 42b), the first grounding terminal (42c) is electrically connected to the first grounding structure (11) and is opposite the second grounding structure (15) in the plan view of the first main surface (10a), the first signal terminal (42a, 42b) is electrically connected to the first connector signal wiring (25a, 25b) by the first signal line structure (13a, 13b), the second grounding structure (15) is electrically connected to the housing (21) or the connector grounding wiring (25c) and the first capacitor (50) is connected to the first grounding structure (11) and the second grounding structure (15) and is arranged on a straight line (50a) defining a shortest distance between the first grounding terminal (42c) and the second grounding structure (15) in the plan view of the first main surface (10a). [2] The printed circuit board (1, 1a, 1b, 1c, 1d, 1e, 1f, 1g, 1h, 1i, 1j) according to claim 1, wherein the shortest distance between the first ground terminal (42c) and the second ground structure (15) is one-tenth or less of an electrical length inside the printed circuit board (9) of electromagnetic noise from the connector (20). [3] Printed circuit board (1, 1a, 1b, 1c, 1d, 1e, 1f, 1g, 1h, 1i, 1j) according to claim 1 or 2, wherein the first capacitor (50) is the only capacitor connected to the first grounding structure (11) and the second grounding structure (15). [4] Printed circuit board (1b) according to one of claims 1 to 3, wherein the second grounding structure (15) includes a first grounding structure section (16a) and a second grounding structure section (16b), the second grounding structure section (16b) protrudes from the first grounding structure section (16a) to the first grounding structure (11), the first grounding structure (11) has a recess (12) which accommodates the second grounding structure section (16b), in the plan view of the first main surface (10a), the first grounding terminal (42c) is opposite the second grounding structure section (16b) and the first capacitor (50) is connected to the first grounding structure (11) and the second grounding structure portion (16b) and is arranged on a straight line (50a) defining a shortest distance between the first grounding terminal (42c) and the second grounding structure portion (16b) in the plan view of the first main surface (10a). [5] Printed circuit board (1c) according to one of claims 1 or 2, further comprising: a second integrated circuit chip (45) placed on the circuit board (9); and a second capacitor (52) mounted on the circuit board (9), the circuit board (9) further including a second signal line structure (13d), the connector (20) further includes a second connector signal wiring (25d) provided inside the housing (21), the second integrated circuit chip (45) includes a second ground terminal (46) and a second signal terminal (46a), the second signal terminal (46a) is electrically connected to the second connector signal wiring (25d) by the second signal line structure (13d), the second grounding terminal (46) is electrically connected to the first grounding structure (11) and is opposite the second grounding structure (15) in the plan view of the first main surface (10a) and the second capacitor (52) is connected to the first grounding structure (11) and the second grounding structure (15) and is arranged on a straight line (52a) defining a shortest distance between the second grounding terminal (46) and the second grounding structure (15) in the plan view of the first main surface (10a). [6] Printed circuit board (1c) according to claim 5, wherein in the plan view of the first main surface (10a), the first grounding structure (11) includes a first outer edge portion (11a) and a second outer edge portion (11c) connected to the first outer edge portion (11a) and extending in a direction different from the first outer edge portion (11a), the second grounding structure (15) includes a first grounding structure portion (16a) extending along the second outer edge portion (11c) and a second grounding structure portion (16b) extending along the first outer edge portion (11a) and connected to the first grounding structure portion (16a), the first capacitor (50) is connected to the first grounding structure (11) and the first grounding structure portion (16a) and is arranged on a straight line (50a) defining a shortest distance between the first grounding terminal (42c) and the first grounding structure portion (16a) in the plan view of the first main surface (10a), and the second capacitor (52) is connected to the first grounding structure (11) and the second grounding structure portion (16b) and is arranged on a straight line (52a) defining a shortest distance between the second grounding terminal (46c) and the second grounding structure portion (16b) in the plan view of the first main surface (10a). [7] Printed circuit board (1d, 1e) according to one of claims 1 to 3, further comprising a second integrated circuit chip (45), wherein the insulating substrate (10) includes a second main surface (10b) opposite the first main surface (10a), the printed circuit board (9) further comprises a third grounding structure (71), a fourth grounding structure (75), a second signal line structure (13d), at least one first conductive via (73) and a second conductive via (77), the fourth grounding structure (75) is separated from the third grounding structure (71) and is directly opposite the third grounding structure (71) in the plan view of the first main surface (10a), the second signal line structure (13d) is insulated from the third grounding structure (71) and the fourth grounding structure (75), the at least one first conductive via (73) is connected to the first grounding structure (11) and the third grounding structure (71) and extends along a direction in which the first main surface (10a) and the second main surface (10b) separate from each other, the second conductive via (77) is connected to the second grounding structure (15) and the fourth grounding structure (75) and extends in the direction in which the first main surface (10a) and the second main surface (10b) separate from each other, the connector (20) further includes a second connector signal wiring (25d) provided inside the housing (21), the second integrated circuit chip (45) includes a second ground terminal (46c) and a second signal terminal (46a), the second grounding terminal (46c) is electrically connected to the third grounding structure (71) and is opposite the fourth grounding structure (75) in the plan view of the first main surface (10a) and the second signal terminal (46a) is electrically connected to the second connector signal wiring (25d) through the second signal line structure (13d). [8] Printed circuit board (1d, 1e) according to claim 7, wherein the at least one first conductive via (73) consists of a plurality of first conductive vias (73). [9] Printed circuit board (1e) according to claim 7 or 8, further comprising a second capacitor (52) mounted on the printed circuit board (9), wherein the second capacitor (52) is connected to the third grounding structure (71) and the fourth grounding structure (75) and is arranged on a straight line (52a) defining a shortest distance between the second grounding terminal (46c) and the fourth grounding structure (75) in the plan view of the first main surface (10a). [10] The printed circuit board (1e) according to claim 9, wherein in the plan view of the first main surface (10a), the second capacitor (52) is arranged at a same position as the first capacitor (50). [11] Printed circuit board (1f) according to one of claims 1 to 3, wherein in the plan view of the first main surface (10a), the first grounding structure (11) includes a first outer edge portion (11b) and a second outer edge portion (11c) connected to the first outer edge portion (11b) and extending in a direction different from the first outer edge portion (11b), the second grounding structure (15) includes a first grounding structure portion (16a) extending along the second outer edge portion (11c) and a second grounding structure portion (16b) extending along the first outer edge portion (11b) and connected to the first grounding structure portion (16a), the first capacitor (50) is connected to the first grounding structure (11) and the first grounding structure portion (16a) and is arranged on a straight line (50a) defining a shortest distance between the first grounding terminal (42c) and the first grounding structure portion (16a) in the plan view of the first main surface (10a), and a gap between the first grounding structure portion (16a) and the first grounding structure (11) is smaller than a gap between the second grounding structure portion (16b) and the first grounding structure (11). [12] Printed circuit board (1g) according to one of claims 1 to 3, wherein the second grounding structure (15) includes a first grounding structure section (16a) and a second grounding structure section (16b), the second grounding structure section (16b) protrudes from the first grounding structure section (16a) to the first grounding structure (11), a gap between the second grounding structure portion (16b) and the first grounding structure (11) in a direction of projection of the second grounding structure portion (16b) from the first grounding structure portion (16a) is smaller than a gap between the first grounding structure portion (16a) and the first grounding structure (11) in the direction of projection, in the plan view of the first main surface (10a), the first grounding terminal (42c) is opposite the second grounding structure section (16b) and the first capacitor (50) is connected to the first grounding structure (11) and the second grounding structure portion (16b) and is arranged on a straight line (50a) defining a shortest distance between the first ground terminal (42c) and the second grounding structure portion (16b) and extending along the direction of the projection. [13] Printed circuit board (1h, 1i) according to one of claims 1 to 3, further comprising a second capacitor (53) mounted on the printed circuit board (9), wherein the housing (21) is a conductive housing (21), the second grounding structure (15) includes a first grounding structure section (16a) and a second grounding structure section (16b) which is separated from the first grounding structure section (16a), the second grounding structure section (16b) is electrically connected to the conductive housing (21), the first capacitor (50) is connected to the first grounding structure (11) and the first grounding structure portion (16a) and is arranged on a straight line (50a) defining a shortest distance between the first grounding terminal (42c) and the first grounding structure portion (16a) in the plan view of the first main surface (10a), and the second capacitor (53) is connected to the first grounding structure section (16a) and the second grounding structure section (16b). [14] Printed circuit board (1i) according to claim 13, further comprising a resistor (54) mounted on the printed circuit board (9), wherein the resistor (54) is connected to the first grounding structure section (16a) and the second grounding structure section (16b) and the second capacitor (53) and the resistor (54) are arranged in parallel between the first grounding structure section (16a) and the second grounding structure section (16b). [15] Printed circuit board (1j) according to one of claims 1 to 14, further comprising: a heat sink (80) opposite the first main surface (10a) and arranged to be separated from the first main surface (10a); and a heat transfer element (83) connected to the first integrated circuit chip (40) and the heat sink (80), wherein the heat sink (80) is separated from the connector (20). [16] Printed circuit board (1j) according to one of claims 1 to 14, further comprising: a heat sink (80) opposite the first main surface (10a) and arranged to be separated from the first main surface (10a); a first heat transfer element (83) connected to the first integrated circuit chip (40) and the heat sink (80); and a second heat transfer element (84) connected to the second grounding structure (15) and the heat sink (80), wherein the heat sink (80) is in contact with the connector (20), the first heat transfer element (83) has a height of 1 mm or more and the second heat transfer element (84) has electrical conductivity. [17] Printed circuit board (1, 1a, 1b, 1c, 1d, 1e, 1f, 1g, 1h, 1i, 1j) according to one of claims 1 to 16, wherein in the plan view of the first main surface (10a) the circuit board (9) has a rectangular shape, a size of each of sides of the circuit board (9) in the plan view of the first main surface (10a) is 5 cm or more and 15 cm or less and the first capacitor (50) has a capacitance of 0.5 µF or more and 5.0 µF or less.

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