Bonded printed circuit board, printed circuit board, and method for manufacturing bonded printed circuit board

Abstract

Provided is a bonded printed circuit board capable of suppressing transmission loss with a simple structure. A bonded printed circuit board (1) according to an embodiment includes: printed circuit boards (10, 20) bonded to each other; and a shield portion 30 having a conductive layer provided across the printed circuit boards 10, 20. A printed circuit board 10 includes: a first insulating layer; a signal line 11; a second insulating layer that is laminated on the first insulating layer so as to embed at least a portion of the signal line (11); and a ground layer (14) provided so as to cover the signal line (11) when the printed circuit board (10) is viewed in the thickness direction. The printed circuit board 20 comprises a third insulating layer; and a signal line 21 electrically connected to the signal line 11. The conductive layer of the shield portion 30 includes: a first conductive portion provided so as to cover the signal line 21 when the printed circuit board 20 is viewed in the thickness direction; and a second conductive part formed integrally with the first conductive part and joined to the ground layer 14.

Description

Technical Field

[0001] The present invention relates to a bonded printed circuit board, a printed circuit board, and a method for manufacturing a bonded printed circuit board, and more particularly to a bonded printed circuit board, a printed circuit board, and a method for manufacturing a bonded printed circuit board capable of improving transmission characteristics with a simple structure. Background Art

[0002] In information and communication devices such as smartphones, printed circuit boards are used as antenna substrates for receiving radio waves, cable substrates provided with signal lines for transmitting signals, and main substrates equipped with semiconductor chips.

[0003] In order to achieve both miniaturization of the substrate size and high transmission characteristics even in high-frequency band signals used in 5G, etc., the material of the antenna substrate is usually different from that of the cable substrate or the main substrate. For example, in the antenna substrate, a material with a high dielectric constant (polyimide, etc.) is used for miniaturization, and in the cable substrate or the main substrate, a material with a low dielectric constant (liquid crystal polymer, etc.) is used to reduce transmission loss.

[0004] Therefore, it is necessary to join the antenna substrate and the cable substrate or the main substrate via a conductive material. Patent Document 1 describes a joined printed circuit board in which two printed circuit boards made of different materials are joined via a conductive material. Prior art literature Patent Literature

[0005] Patent Document 1: Japanese Patent No. 4685614 Technical issues

[0006] A joint printed circuit board for transmitting high-frequency band signals has a microstrip line structure or a stripline structure. In these structures, a signal line and a ground layer are provided with an insulating layer sandwiched therebetween. In a joint printed circuit board, when the ground layer of one printed circuit board is not electrically connected to the ground layer of another printed circuit board, the return current induced in the ground layer by the signal flowing through the signal line is cut off at the joint portion, generating noise and reducing the transmission characteristics. In the joint printed circuit board of Patent Document 1, the ground layers of the two substrates are not electrically connected, and the transmission characteristics are reduced due to the cutoff of the return current.

[0007] The present invention is completed based on the above technical knowledge, and its purpose is to provide a bonded printed circuit board and a manufacturing method thereof that can improve the transmission characteristics with a simple structure. However, it is not limited to this purpose, and the purpose corresponding to each effect brought about by the structure of each embodiment described later can also be taken as the purpose of the present invention. Summary of the invention

[0008] The first aspect of the present invention provides a bonded printed circuit board characterized by comprising: a first printed circuit board; a second printed circuit board, the second printed circuit board being bonded to the first printed circuit board; and a shielding portion, the shielding portion having a conductive layer arranged across the first printed circuit board and the second printed circuit board. The first printed circuit board includes: a first insulating layer, the first insulating layer having a first main surface and a second main surface on the opposite side of the first main surface; a first signal line, the first signal line being arranged on the first main surface; a second insulating layer, the second insulating layer having a third main surface opposite to the first main surface and a fourth main surface on the opposite side of the third main surface, the second insulating layer being stacked on the first insulating layer in a manner of burying at least a portion of the first signal line; and a grounding layer, the grounding layer being arranged on the fourth main surface in a manner of covering the first signal line when the first printed circuit board is observed in the thickness direction. The second printed circuit board includes: a third insulating layer, the third insulating layer having a fifth main surface bonded to the first printed circuit board and a sixth main surface on the opposite side of the fifth main surface; and a second signal line, the second signal line being electrically connected to the first signal line. The conductive layer of the shielding part includes: a first conductive part, which is configured to cover the second signal line when the second printed circuit board is observed in the thickness direction; and a second conductive part, which is formed as a whole with the first conductive part and is connected to the ground layer.

[0009] In addition, in the joined printed circuit board, the second printed circuit board can be an antenna substrate provided with an antenna, which is connected to the second signal line and receives wireless signals; the first printed circuit board can be a cable substrate in which the first signal line is connected to other substrates, or can be a main substrate on which a semiconductor chip is mounted, and the semiconductor chip processes the wireless signal received by the antenna.

[0010] In addition, in the joined printed circuit board, the first insulating layer of the first printed circuit board may include a first insulating substrate, which is composed of a liquid crystal polymer, a fluorine material, a polyimide material or a cycloolefin polymer; the second insulating layer of the first printed circuit board may include a second insulating substrate, which is composed of a liquid crystal polymer, a fluorine material, a polyimide material or a cycloolefin polymer; the third insulating layer of the second printed circuit board may include a third insulating substrate, which is composed of a polyimide material, a liquid crystal polymer, a fluorine material, epoxy glass, a cycloolefin polymer, ceramic or polyphenylene ether.

[0011] In addition, in the joined printed circuit board, the conductive layer of the shield portion may have a metal foil, a conductive paste layer, a solder layer, an isotropic conductive adhesive layer, or a conductive film layer.

[0012] In the joined printed circuit boards, the conductive layer of the shield portion may be a metal foil, and the shield portion may further include an anisotropic conductive adhesive layer for bonding the metal foil to the first printed circuit board and the second printed circuit board.

[0013] In addition, in the joined printed circuit boards, the conductive layer of the shield portion may be a conductive paste layer, and the shield portion may further include an isotropic conductive adhesive layer for bonding the conductive paste layer to the first printed circuit board and the second printed circuit board.

[0014] In addition, in the joined printed circuit boards, the conductive layer of the shielding portion may be a conductive paste layer or a solder layer, and the shielding portion may further have an anisotropic conductive adhesive layer for bonding the conductive paste layer or the solder layer to the first printed circuit board and the second printed circuit board.

[0015] In addition, in the joined printed circuit board, the conductive layer of the shield portion may be an isotropic conductive adhesive layer.

[0016] In addition, in the bonded printed circuit board, the conductive layer of the shielding portion may be a metal foil, and the shielding portion may further include: a first insulating adhesive layer, the first insulating adhesive layer being provided on the second printed circuit board, the first insulating adhesive layer bonding the first conductive portion of the conductive layer to the second printed circuit board; and a second insulating adhesive layer, the second insulating adhesive layer being provided on the first printed circuit board, the second insulating adhesive layer bonding the second conductive portion of the conductive layer to the first printed circuit board. The second conductive portion may be electrically connected to the ground layer via a conductive material.

[0017] In addition, in the joined printed circuit board, the second insulating layer of the first printed circuit board can be stacked on the first insulating layer in a manner that the first main surface and the end of the first signal line are partially exposed, the second signal line of the second printed circuit board can be arranged on the fifth main surface, the first conductive portion of the shielding portion can be joined to the sixth main surface, the fifth main surface can be joined to the partially exposed portion of the first main surface of the first printed circuit board through a second conductive material, and the end of the first signal line and the second signal line can be electrically connected through the second conductive material.

[0018] In addition, in the joined printed circuit board, the first printed circuit board may further include an interlayer connecting portion, which passes through the second insulating layer and electrically connects the first signal line to a soldering pad provided on the fourth main surface, the fifth main surface of the second printed circuit board may be joined to the fourth main surface of the first printed circuit board, and the first signal line and the second signal line may be electrically connected through the interlayer connecting portion and the soldering pad.

[0019] In addition, in the joined printed circuit board, the second signal line of the second printed circuit board can be arranged on the fifth main surface, the first conductive part of the shielding part can be joined to the sixth main surface, and the pad of the interlayer connection part and the second signal line can be electrically connected by a second conductive material.

[0020] In addition, in the bonded printed circuit board, the second printed circuit board may further include a third signal line provided in the third insulating layer and different from the second signal line, and the pad of the interlayer connection portion may be electrically connected to the third signal line via a third conductive material.

[0021] In addition, in the bonded printed circuit board, the second signal line of the second printed circuit board may be provided on the sixth main surface, and the second printed circuit board may further include: an insulating protective layer, the insulating protective layer covering the second signal line; and a third conductive material, the third conductive material filling a through hole penetrating the third insulating layer and electrically connecting the pad of the first printed circuit board and the second signal line. The first conductive portion of the shielding portion may be bonded to the insulating protective layer.

[0022] In addition, in the bonded printed circuit board, the second printed circuit board may further include a second ground layer provided on the fifth main surface, and the ground layer and the second ground layer may be electrically connected via a second conductive material.

[0023] In the bonded printed wiring board, a third insulating adhesive layer, a second insulating protective layer, and a fourth insulating adhesive layer may be stacked in this order between the fourth main surface and the fifth main surface.

[0024] In addition, in the joined printed circuit boards, the first printed circuit board and / or the second printed circuit board may be a flexible printed circuit board.

[0025] In addition, in the bonded printed circuit board, the first printed circuit board may have 2-5 circuit layers.

[0026] In addition, in the bonded printed circuit board, the second printed circuit board may have 1 to 5 circuit layers.

[0027] The second aspect of the present invention provides a joint printed circuit board characterized by comprising: a first printed circuit board; a second printed circuit board, the second printed circuit board being joined to the first printed circuit board; and a shielding part, the shielding part having a conductive layer arranged across the first printed circuit board and the second printed circuit board. The first printed circuit board includes: a first insulating layer, the first insulating layer having a first main surface and a second main surface on the opposite side of the first main surface; a first signal line, the first signal line being arranged on the first main surface; and a grounding line, the grounding line being arranged on the first main surface in a manner of sandwiching the first signal line. The second printed circuit board includes: a second insulating layer, the second insulating layer having a third main surface joined to the first main surface and a fourth main surface on the opposite side of the third main surface; and a second signal line, the second signal line being arranged on the third main surface and electrically connected to the first signal line through a conductive material. The conductive layer of the shielding part includes: a first conductive part, the first conductive part being arranged on the fourth main surface in a manner of covering the second signal line when the second printed circuit board is observed in the thickness direction; and a second conductive part, the second conductive part being formed integrally with the first conductive part and joined to the grounding line.

[0028] The printed circuit board provided by the present invention is characterized in that it comprises: a first insulating layer, the first insulating layer having a first main surface and a second main surface on the opposite side of the first main surface; a first signal line, the first signal line is arranged on the first main surface; a second insulating layer, the second insulating layer having a third main surface opposite to the first main surface and a fourth main surface on the opposite side of the third main surface, the second insulating layer comprising a laminated portion laminated on the first insulating layer and an extension portion extending from the laminated portion in a length direction; a second signal line, the second signal line is arranged on the fourth main surface at the laminated portion and the extension portion of the second insulating layer; a grounding layer, the grounding layer A ground layer is arranged on the fourth main surface at the stacked portion of the second insulating layer in a manner spaced from the second signal line; an interlayer connecting portion, which passes through the second insulating layer and electrically connects the first signal line with the second signal line; an insulating protective layer, which is arranged in a manner covering the second signal line; and a shielding portion, which has a conductive layer, the conductive layer includes a first conductive portion and a second conductive portion, the first conductive portion is arranged to cover the second signal line when the second insulating layer is observed in the thickness direction, and the second conductive portion is formed as a whole with the first conductive portion and is joined to the ground layer.

[0029] The method for manufacturing a bonded printed circuit board provided by the present invention is characterized by comprising the following steps: A first printed circuit board is prepared, wherein the first printed circuit board includes: a first insulating layer, the first insulating layer having a first main surface and a second main surface on a side opposite to the first main surface; a first signal line, the first signal line is provided on the first main surface; a second insulating layer, the second insulating layer having a third main surface opposite to the first main surface and a fourth main surface on a side opposite to the third main surface, the second insulating layer being stacked on the first insulating layer in a manner of burying the first main surface and at least a portion of the first signal line; and a ground layer, the ground layer being provided on the fourth main surface in a manner of covering the first signal line when the second insulating layer is observed in a thickness direction; preparing a second printed circuit board, wherein the second printed circuit board comprises: a third insulating layer, the third insulating layer having a fifth main surface and a sixth main surface opposite to the fifth main surface; and a second signal line, the second signal line being provided on the third insulating layer; Joining the first printed circuit board and the second printed circuit board through a conductive material; joining the fifth main surface of the second printed circuit board to the first printed circuit board to electrically connect the first signal line and the second signal line; A shielding portion having a conductive layer is provided, wherein the conductive layer includes a first conductive portion and a second conductive portion formed integrally with the first conductive portion, the first conductive portion is joined to the second printed circuit board in a manner that covers the second signal line when the second printed circuit board is observed in a thickness direction, and the second conductive portion is joined to the ground layer.

[0030] In the method for manufacturing the bonded printed circuit boards, the step of bonding the first printed circuit board and the second printed circuit board and the step of providing the shielding portion may be performed simultaneously.

[0031] According to the joined printed circuit board provided by the present invention, by providing a shield portion having a conductive layer provided across the first printed circuit board and the second printed circuit board, it is possible to improve transmission characteristics with a simple structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 (a) is a plan view of the bonded printed circuit boards provided in the first embodiment before bonding. Figure 1 (b) is a longitudinal cross-sectional view along the signal line of the bonded printed circuit board provided in the first embodiment. Figure 2 This is a longitudinal cross-sectional view along the ground line of the bonded printed circuit board provided in the first embodiment. Figure 3A The figures are cross-sectional views illustrating the steps of the method for manufacturing the bonded printed wiring boards according to the first embodiment. Figure 3B It is the successor Figure 3A Next, cross-sectional views of the steps of the method for manufacturing the bonded printed wiring boards provided in the first embodiment will be described. Figure 3C It is the successor Figure 3B Next, cross-sectional views of the steps of the method for manufacturing the bonded printed wiring boards provided in the first embodiment will be described. Figure 3D It is the successor Figure 3C Next, cross-sectional views of the steps of the method for manufacturing the bonded printed wiring boards provided in the first embodiment will be described. Figure 4 (a) is a longitudinal cross-sectional view along a signal line of a bonded printed circuit board provided in Modification 1 of the first embodiment. Figure 4 (b) is a longitudinal cross-sectional view along the signal line of the bonded printed circuit board provided in Modification 2 of the first embodiment. Figure 5 (a) is a longitudinal cross-sectional view along a signal line of a bonded printed circuit board provided in Modification 3 of the first embodiment. Figure 5 (b) is a longitudinal cross-sectional view along the signal line of the bonded printed circuit board provided in Modification 4 of the first embodiment. Figure 6 This is a longitudinal cross-sectional view along a signal line of a bonded printed circuit board provided in Modification 5 of the first embodiment. Figure 7 This is a longitudinal cross-sectional view along the signal line of the bonded printed circuit board provided in the second embodiment. Figure 8 This is a longitudinal cross-sectional view along a signal line of a bonded printed circuit board provided in a modification of the second embodiment. Fig. 9 This is a longitudinal cross-sectional view along the signal line of the bonded printed circuit board provided in the third embodiment. Fig.10 This is a longitudinal cross-sectional view along the signal line of a bonded printed circuit board provided in a fourth embodiment. Fig.11 (a) is a plan view of a bonded printed circuit board before bonding provided in the fifth embodiment. Fig.11 (b) is a longitudinal cross-sectional view along the ground line of the bonded printed circuit board provided in the fifth embodiment. Fig.12 1 is a longitudinal cross-sectional view along a signal line of a printed circuit board provided in a sixth embodiment. Main component symbols Joining printed circuit board 1, 1A Printed circuit board 10, 10A, 20 Signal lines 11, 11A, 21, 21A Ground wire 12, 12A Ground layer 13, 14, 24 Insulating substrate 15, 16, 16A, 25 Insulating adhesive layer 17, 17A Insulation protection layer 18, 19, 28, 29 Antenna 22 Shielding parts 30, 30A, 30B, 30C, 30D Metal foil 31, 31a, 31b Conductive paste layer 32 Isotropic conductive adhesive layers 33, 33a, 33b Anisotropic conductive adhesive layer 34 Insulating adhesive layers 35a, 35b Conductive material 36 Insulation protection layer 39 Anisotropic conductive adhesive 41 Ground vias 51, 52 Signal vias 53, 54 Pad 55 Conductive paste 61, 62 Insulating adhesive layers 71, 72 Insulation protection layer 73 Double-sided metal laminate 100 Metal foil 110, 120, 210, 210a, 310 Insulating substrate 130, 220, 320 Single-sided metal laminate 200, 300 DETAILED DESCRIPTION

[0033] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the same reference numerals are used for elements having the same functions.

[0034] In addition, the scale ratio of each element is set to a size that can be recognized on the drawings, so it can be changed appropriately. In addition, the drawings are schematic, and the characteristic parts provided by each embodiment are shown as the center, and the relationship between thickness and plane size, the ratio of thickness of each layer, etc. are different from reality.

[0035] In the following description, "joining" includes both the case of using an adhesive and the case of direct contact unless otherwise specified. When using an adhesive, there is no limitation on conductivity or insulation, and anisotropy or isotropy.

[0036] (First Embodiment) Reference Figure 1 and Figure 2 , the bonded printed circuit board 1 provided in the first embodiment will be described. Figure 1(a) is a plan view of the bonded printed circuit board 1 provided in the present embodiment before bonding. Figure 1 (b) is a longitudinal cross-sectional view along the signal lines 11 and 21 of the joined printed circuit board 1 provided in the present embodiment. Figure 2 1 is a longitudinal cross-sectional view of the joint printed circuit board 1 provided in the present embodiment along the ground line 12. Figure 1 In (a), the ground layer 14, the insulating protection layer 19 and the shielding portion 30 are omitted.

[0037] like Figure 1 and Figure 2 As shown, the joined printed circuit board 1 provided in this embodiment includes a printed circuit board 10 , a printed circuit board 20 and a shielding portion 30 .

[0038] In the present embodiment, the printed circuit board 20 is an antenna substrate provided with an antenna 22 for receiving a wireless signal. In addition, the printed circuit board 10 is, for example, a cable substrate for transmitting a wireless signal received by the antenna 22. The cable substrate is connected to other substrates, for example, to a main substrate on which a semiconductor chip for processing the wireless signal is mounted. In addition, by mounting a semiconductor chip on the printed circuit board 10, the printed circuit board 10 itself can be used as a main substrate.

[0039] The printed circuit board 10 includes a signal line 11, a ground line (protective ground) 12, ground layers 13, 14, insulating substrates 15, 16, an insulating adhesive layer 17, and insulating protective layers 18, 19. The insulating substrate 15 is an example of a first insulating layer. In addition, the insulating substrate 16 and the insulating adhesive layer 17 constitute an example of a second insulating layer.

[0040] The insulating substrate 15 (first insulating layer) has an upper surface (first main surface) and a lower surface (second main surface) on the opposite side of the upper surface. The signal line 11 is provided on the upper surface of the insulating substrate 15. In addition, a pair of grounding lines 12 (protective grounding) are provided on the upper surface of the insulating substrate 15 in a manner of sandwiching the signal line 11. The grounding layer 13 is provided on the lower surface of the insulating substrate 15. The grounding layer 13 is provided so as to cover the signal line 11 when the insulating substrate 15 is viewed in the thickness direction.

[0041] like Figure 2 As shown, the ground line 12 and the ground layer 13 are electrically connected through a plurality of ground vias 51. The plurality of ground vias 51 may also be arranged at intervals of less than 1 / 4 of the wavelength (electrical length) determined by the frequency of the signal transmitted by the signal line 11 and the dielectric constant of the insulating substrate 15. In this embodiment, it is assumed that the frequency of the signal is 6 GHz, a liquid crystal polymer (LCP) is used as the insulating substrate 15, and the interval between the ground vias 51 is set to 1.5 mm. Thus, the transmission characteristics of the signal propagated through the signal line 11 can be improved.

[0042] The insulating substrate 16 and the insulating adhesive layer 17 (second insulating layer) have a lower surface (third main surface) and an upper surface (fourth main surface) opposite to the lower surface. In the present embodiment, the lower surface of the second insulating layer is the lower surface of the insulating adhesive layer 17. In addition, the upper surface of the second insulating layer is the upper surface of the insulating substrate 16.

[0043] The lower surface of the insulating adhesive layer 17 faces the upper surface of the insulating substrate 15. In addition, the insulating adhesive layer 17 is laminated on the insulating substrate 15 in a manner that buries at least a portion of the signal line 11 and the ground line 12. In the present embodiment, the insulating adhesive layer 17 is laminated on the insulating substrate 15 in a manner that the upper surface of the insulating substrate 15 and the ends of the signal line 11 and the ground line 12 are partially exposed.

[0044] Furthermore, when the insulating substrate 15 and the insulating substrate 16 can be bonded without an adhesive, the insulating adhesive layer 17 may not be provided. In this case, the lower surface of the second insulating layer is the lower surface of the insulating substrate 16. In this case, the insulating substrate 16 may be laminated on the insulating substrate 15 in a manner that at least a portion of the signal line 11 and the ground line 12 are buried.

[0045] In the present embodiment, the material of the insulating substrate 15, 16 is a liquid crystal polymer (LCP) with a relatively low dielectric constant. Not limited thereto, the material of the insulating substrate 15, 16 may also be polyetheretherketone (PEEK), or polyethylene naphthalate (PEN), etc. Alternatively, the material of the insulating substrate 15, 16 may also be a fluorine-based material such as tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer (PFA), polytetrafluoroethylene (PTFE), a material for embedding epoxy glass with a fluorine-based material, a polyimide-based material such as modified polyimide (MPI), polyimide (PI), or a cycloolefin polymer (COP) with a low dielectric constant and a low dielectric loss tangent. The material with a low dielectric constant and a low dielectric loss tangent includes the LCP used in the present embodiment. By using a material with a low dielectric constant and a low dielectric loss tangent as the material of the insulating substrate 15, 16, the transmission characteristics in the printed circuit board 10 can be improved.

[0046] In addition, the materials of the insulating base material 15 and the insulating base material 16 may be the same or different from each other.

[0047] The ground layer 14 is provided on the upper surface of the insulating substrate 16. The ground layer 14 is provided to cover the signal line 11 when the printed circuit board 10 is viewed in the thickness direction. Figure 2 As shown, the ground line 12 and the ground layer 14 are electrically connected through a plurality of ground vias 52. The intervals between the plurality of ground vias 52 are set to be the same as the intervals between the plurality of ground vias 51.

[0048] The insulating protective layer 18 is provided to cover the ground layer 13. The insulating protective layer 19 is provided to cover the ground layer 14 except for a portion bonded with an anisotropic conductive adhesive layer 34 described later. Insulating protective layers 18 and 19 may also be provided with openings for connection.

[0049] In this embodiment, the insulating protective layers 18 and 19 are polyimide films. Alternatively, a photosensitive photoresist may be used for the insulating protective layers 18 and 19. The same is true for the insulating protective layer 29 described later.

[0050] The printed circuit board 20 includes a signal line 21, an antenna 22, an insulating base material 25, and an insulating protection layer 29. The insulating base material 25 is an example of a third insulating layer.

[0051] The insulating substrate 25 (the third insulating layer) has a lower surface (the fifth principal surface) and an upper surface (the sixth principal surface) on the opposite side of the lower surface. In the present embodiment, the material of the insulating substrate 25 is a polyimide (PI) having a higher dielectric constant than LCP. By using a material with a high dielectric constant and a low dielectric loss tangent as the material of the insulating substrate 25, a smaller antenna can be provided when the printed circuit board 20 is used as an antenna substrate. In addition, the material of the insulating substrate 25 can also be a polyimide material other than a fluorine-based material, PI, epoxy glass or COP such as LCP, FR4, etc. Alternatively, the material of the insulating substrate 25 can also be a material with a high dielectric constant and a low dielectric loss tangent such as ceramics or polyphenylene ether.

[0052] The printed circuit board 20 is bonded to the printed circuit board 10 via an anisotropic conductive adhesive 41. In the present embodiment, the lower surface of the insulating substrate 25 of the printed circuit board 20 is bonded to a partially exposed portion of the upper surface of the insulating substrate 15 of the printed circuit board 10 via the anisotropic conductive adhesive 41. In addition, in the present embodiment, the anisotropic conductive adhesive 41 is an anisotropic conductive film (ACF). The anisotropic conductive adhesive 41 is an example of the second conductive material.

[0053] In addition, the anisotropic conductive adhesive 41 may be an anisotropic conductive paste (ACP). In addition, an isotropic conductive adhesive such as an isotropic conductive film or an isotropic conductive paste or a solder such as a paste solder may be used instead of the anisotropic conductive adhesive 41. When an isotropic conductive adhesive or a solder is used, an insulating material such as a non-conductive film (NCF), a non-conductive paste (NCP), or an insulating adhesive may be used to achieve insulation between the isotropic conductive adhesive or the solder.

[0054] The signal line 21 is electrically connected to the signal line 11. In the present embodiment, the signal line 21 is provided on the lower surface of the insulating substrate 25. In the present embodiment, the end of the signal line 11 and the end of the signal line 21 are opposite to each other and are electrically connected through the anisotropic conductive adhesive 41. In addition, when an isotropic conductive adhesive, an isotropic conductive paste, or a solder such as a paste solder is used instead of the anisotropic conductive adhesive 41, the signal line 11 and the signal line 21 are not opposite to each other, and the positions may be staggered when viewed from above. Alternatively, the signal line 11 and the signal line 21 may be directly in contact with each other, and the printed circuit boards 10 and 20 may be joined using an insulating material.

[0055] The antenna 22 receives or transmits wireless signals, for example. In this embodiment, the antenna 22 is provided on the lower surface of the insulating substrate 25, is formed integrally with the signal line 21, and is electrically connected to the signal line 21. In this embodiment, since PI with a thickness of 25 μm is used as the insulating substrate 25, Figure 1 The width W of the antenna 22 shown in (a) is, for example, 16 mm, and the length L is, for example, 13 mm.

[0056] The insulating protection layer 29 is provided to cover a portion of the signal line 21 and the antenna 22 .

[0057] like Figure 1 (b) and Figure 2 As shown, the shielding part 30 is provided across the printed circuit board 10 and the printed circuit board 20. The shielding part 30 has a metal foil 31 provided across the printed circuit board 10 and the printed circuit board 20, an anisotropic conductive adhesive layer 34, and an insulating protective layer 39. The metal foil 31 is an example of a conductive layer.

[0058] In the present embodiment, the metal foil 31 is provided across the entire upper surface of the insulating substrate 25 and a portion of the ground layer 14. More specifically, the metal foil 31 includes: a metal foil 31a (first conductive portion) bonded to the upper surface of the insulating substrate 25; and a metal foil 31b (second conductive portion) extending from the end of the printed circuit board 20 and bonded to the ground layer 14. In addition, in the present embodiment, the metal foil 31 is a 3 μm copper foil.

[0059] The metal foil 31a is provided so as to cover the signal line 21 and the antenna 22 when the printed circuit board 20 is viewed in the thickness direction. Thus, the metal foil 31a functions as a ground for the signal line 21 and the antenna 22. Figure 1 In the figure, the metal foil 31a is arranged on the entire upper surface of the insulating substrate 25, and is arranged to cover the signal line 21 and the antenna 22 when the printed circuit board 20 is observed in the thickness direction, but the metal foil 31a is arranged to at least cover the signal line 21 when the printed circuit board 20 is observed in the thickness direction.

[0060] The metal foil 31b is formed integrally with the metal foil 31a, and the metal foil 31b is bonded to the ground layer 14 via the anisotropic conductive adhesive layer 34. Thus, the metal foil 31 and the ground layer 14 are electrically connected.

[0061] The anisotropic conductive adhesive layer 34 is provided between the metal foil 31 and the printed circuit boards 10 and 20 to bond the metal foil 31 to the printed circuit boards 10 and 20. In addition, the anisotropic conductive adhesive layer 34 may be divided into two or more parts. For example, the anisotropic conductive adhesive layer 34 may be divided into: a first anisotropic conductive adhesive bonding the metal foil 31a to the upper surface of the insulating substrate 25; and a second anisotropic conductive adhesive bonding the metal foil 31b to the ground layer 14.

[0062] The insulating protective layer 39 is provided on the metal foil 31 to cover the metal foil 31. Alternatively, the insulating protective layer 39 may not be provided.

[0063] In the joint printed circuit board 1 described above, the shielding part 30 is arranged across the printed circuit board 10 and the printed circuit board 20. The metal foil 31 of the shielding part 30 has a metal foil 31a and a metal foil 31b. The metal foil 31a acts as a ground for the signal line 21. The metal foil 31b is formed as a whole with the metal foil 31a, and the metal foil 31b is electrically connected to the ground layer 14 of the printed circuit board 10. Due to such a structure, the return current is not cut off at the joint part. For example, when the antenna 22 receives a wireless signal and the current flows from the signal line 21 to the signal line 11, the return current induced by the current flowing through the signal line 11 in the ground layer 14 flows to the metal foil 31a via the metal foil 31b, and is therefore not cut off at the joint part. As a result, the transmission characteristics of the signal propagated through the signal lines 11 and 21 can be improved with a simple structure.

[0064] <Method for manufacturing a bonded printed circuit board> Next, refer to FIG. 3A to FIG. 3D The method for manufacturing the joined printed wiring board 1 provided in the first embodiment will be described. FIG. 3A to FIG. 3D The diagram is a cross-sectional view showing the steps of the method for manufacturing the bonded printed wiring board 1 according to the present embodiment.

[0065] like Figure 3A As shown in (1), a double-sided metal-clad laminate 100 including a metal foil 110, a metal foil 120, and an insulating substrate 130 is prepared. The metal foil 110 is provided on the upper surface of the insulating substrate 130, and the metal foil 120 is provided on the lower surface of the insulating substrate 130.

[0066] The metal foils 110 and 120 are, for example, copper foils with a thickness of 12 μm. The material of the metal foils 110 and 120 is not limited to copper, but may be silver, aluminum, or other metals. The same is true for the metal foils 210 and 310 described later.

[0067] The insulating substrate 130 is, for example, LCP with a thickness of 100 μm. In addition, the insulating substrate 130 may also be made of PEEK, PEN, fluorine-based materials, polyimide-based materials, or COP.

[0068] Then, if Figure 3A As shown in (2), the metal foils 110 and 120 are patterned using a known photolithography method. Thus, the metal foil 110 is patterned to form the signal line 11 and the ground line 12. In addition, the metal foil 120 is patterned to form the ground layer 13. At this time, an opening (not shown) for a conformal mask is formed in the ground layer 13. In addition, the opening can also be formed in another process.

[0069] Then, if Figure 3A As shown in (3), a single-sided metal-clad laminate 200 having a metal foil 210 and an insulating base material 220 is prepared. The metal foil 210 is provided on the upper surface of the insulating base material 220.

[0070] The insulating substrate 220 is, for example, LCP with a thickness of 50 μm. In addition, the insulating substrate 220 may also be made of PEEK, PEN, fluorine-based materials, polyimide-based materials, or COP.

[0071] Then, if Figure 3A As shown in (4), the metal foil 210 is patterned using a known photolithography method to form the grounding layer 14 and the metal foil 210a. At this time, an opening for a conformal mask is formed in the grounding layer 14 (not shown). In addition, the opening can also be formed in other processes. By forming the metal foil 210a, the shape of the end of the insulating substrate 220 is stabilized, so that the process of removing a portion of the insulating substrate 220 becomes easy. It should be noted that the metal foil 210a may not be formed. In addition, an insulating adhesive layer 17 is provided on the lower surface of the insulating substrate 220. As shown in FIG. Figure 3A As shown in (4), the insulating adhesive layer 17 is not provided in the end region of the insulating substrate 220. Therefore, in the subsequent step, it is easy to remove a portion of the insulating substrate 220. In this embodiment, the thickness of the insulating adhesive layer 17 is 50 μm. In addition, the material of the insulating adhesive layer 17 can be a material with a low dielectric constant and a low dielectric loss tangent.

[0072] Then, if Figure 3B (1) As shown in Figure 3A (2) is stacked on the substrate Figure 3A More specifically, the substrate is aligned so that Figure 3A (2) The signal line 11 of the substrate and Figure 3A(4) The insulating adhesive layer 17 of the substrate is opposite. At this time, the upper surface of the insulating substrate 130 and the ends of the signal line 11 and the ground line 12 are partially exposed after lamination. Thereafter, they are heated and pressurized by hot pressing to become one. In the hot pressing process, stamping is performed at a temperature higher than the softening point of the insulating adhesive layer 17 (for example, 170°C). In addition, in the case where thermal curing is insufficient, a heating process utilizing curing in an oven may be added.

[0073] Next, along Figure 3B The dotted line CL shown in (2) cuts the insulating substrate 220, thereby removing a portion of the insulating substrate 220 and the metal foil 210a. In this embodiment, a portion of the insulating substrate 220 is torn off and removed using a jig. Alternatively, the insulating substrate 220 may be cut and removed using a CO2 laser or the like. In addition, instead of cutting the insulating substrate 220, an insulating substrate 220 shorter than the insulating substrate 130 may be used in advance.

[0074] Next, laser pulses are irradiated to the openings provided in the ground layers 13 and 14, thereby forming the ground via holes 51 and 52 (see FIG. 1 ) in the insulating substrates 130 and 220. Figure 2 ) through-hole. More specifically, the metal foil around the opening (a part of the grounding layer 13, 14) is used as a conformal mask and irradiated with laser pulses, thereby removing the insulating substrate 130, 220 and the insulating adhesive layer 17 of the opening portion. In this embodiment, a carbon dioxide laser is used as the laser, but a UV-YAG laser or the like may also be used. In addition, the diameter of the through-hole is, for example, 150 μm. The grounding wire 12 is exposed on the bottom surface of the through-hole. Desmear treatment may also be performed after the through-hole is formed.

[0075] Next, ground vias 51 and 52 are formed by forming a metal plating layer in the via hole. In the present embodiment, copper plating is performed to form a copper plating layer. In addition, in the present embodiment, after a dry film is laminated on the grounding layers 13 and 14, the dry film is exposed and developed, and an opening is formed in the portion where the via hole is formed, using a button plating method (pattern plating method) for performing the plating process. In addition, a full-board plating method in which a metal plating process is performed on the entire substrate may be used instead of the button plating method. Through these steps, the insulating substrates 130 and 220 become the above-mentioned insulating substrates 15 and 16. In addition, after the metal plating process, the grounding layers 13 and 14 may be patterned by a known photolithography method.

[0076] Then, if Figure 3BAs shown in (3), the insulating protective layer 18 is covered on the ground layer 13, and the insulating protective layer 19 is covered on the ground layer 14. In this embodiment, a polyimide film is laminated on the ground layers 13 and 14, but a photosensitive photoresist may also be used. In this case, at least a portion of the ground layer 14 is exposed later for electrical connection with the shielding part. In addition, the exposed ground layers 13 and 14 may be subjected to surface treatment such as gold plating. In this embodiment, although gold plating is applied, a water-soluble pre-flux may also be applied.

[0077] Through the above process, we can obtain Figure 3B (3) The printed circuit board 10 shown.

[0078] Then, if Figure 3C As shown in (1), a single-sided metal-clad laminate 300 including a metal foil 310 and an insulating base 320 is prepared. The metal foil 310 is provided on the lower surface of the insulating base 320.

[0079] In this embodiment, the insulating substrate 320 is, for example, polyimide with a thickness of 25 μm. Alternatively, the insulating substrate 320 may be made of a fluorine-based material, a polyimide-based material other than polyimide, LCP, epoxy glass, COP, ceramic, or polyphenylene ether.

[0080] Then, if Figure 3C As shown in (2), the metal foil 310 is patterned using a known photolithography method to form the signal line 21 and the antenna 22. In this embodiment, since interlayer connection portions such as vias are not formed on the insulating substrate 320, the insulating substrate 25 is formed at this stage.

[0081] Then, if Figure 3C As shown in (3), the signal line 21 and the antenna 22 are covered with an insulating protective layer 29. At this time, at least the end of the signal line 21 is exposed for electrical connection with the signal line 11 later. In this embodiment, a polyimide film is laminated on the signal line 21 and the antenna 22, but a photosensitive photoresist may also be used. In addition, the exposed end of the signal line 21 may be subjected to surface treatment such as gold plating. In this embodiment, although gold plating is performed, a water-soluble pre-flux may also be applied.

[0082] Through the above process, we can obtain Figure 3C (3) The printed circuit board 20 shown.

[0083] Then, if Figure 3D As shown in (1), the printed wiring board 10 and the printed wiring board 20 are bonded together by anisotropic conductive adhesive 41. In this embodiment, ACF is used as anisotropic conductive adhesive 41, and the printed wiring board 10 and the printed wiring board 20 are bonded together by the following steps.

[0084] First, in order to position the ACF, temporary bonding is performed at a temperature below the curing temperature of the ACF. For example, in the case of using an ACF made of an epoxy resin material that cures at 170°C, the heating temperature is set to 100°C, and the ACF is temporarily bonded to the upper surface of the insulating substrate 15 partially exposed at the end of the printed circuit board 10 and the signal line 11. Alternatively, the location to temporarily bond the ACF may be the lower surface of the insulating substrate 25 of the printed circuit board 20 and the signal line 21.

[0085] Next, the printed circuit board 10 and the printed circuit board 20 are aligned. In the present embodiment, the alignment is performed based on the outer shapes of the printed circuit boards 10 and 20. Alternatively, the printed circuit boards 10 and 20 may be provided with through materials or through holes, and the alignment is performed based on the through materials or through holes.

[0086] Next, a main bonding step was performed at a temperature of 170° C. and a pressure of 4 MPa.

[0087] Through the above steps, the printed wiring board 10 and the printed wiring board 20 are bonded together.

[0088] In the present embodiment, the lower surface of the insulating base material 25 is bonded to the partially exposed portion of the upper surface of the insulating base material 15 . Thus, the signal line 11 and the signal line 21 are electrically connected.

[0089] Then, if Figure 3D As shown in (2), a shielding portion 30 is provided across the printed circuit board 10 and the printed circuit board 20. More specifically, the metal foil 31a is bonded to the upper surface of the insulating substrate 25 in such a manner as to cover the signal line 21 when the printed circuit board 20 is viewed in the thickness direction. In addition, the metal foil 31b is bonded to the ground layer 14. In this process, for example, the anisotropic conductive adhesive layer 34, the metal foil 31 and the insulating protective layer 39 are formed into a whole, and the whole is bonded. Alternatively, after the anisotropic conductive adhesive layer 34 is applied or arranged, a shielding material having the metal foil 31 and the insulating protective layer 39 is bonded. Thus, the metal foil 31a functions as a ground for the signal line 21 and the antenna 22. The metal foil 31 is electrically connected to the ground layer 14 through the anisotropic conductive adhesive layer 34.

[0090] Through the above steps, the joined printed wiring board 1 provided in this embodiment is obtained.

[0091] As described above, according to the manufacturing method of the joined printed circuit board 1 provided in the first embodiment, the shielding portion 30 is provided after the printed circuit boards 10 and 20 are joined, and the metal foil 31 (conductive layer) of the shielding portion 30 functions as the ground (ground layer) of the signal line 21 and the antenna 22. Thus, a single-sided metal-clad laminate can be used as a starting material for the printed circuit board 20, and the joined printed circuit board 1 can be manufactured simply and inexpensively. In addition, a material having good characteristics, such as a low dielectric constant and transparent material, can be used.

[0092] In addition, in the above-mentioned manufacturing method, the process of bonding the printed circuit board 10 and the printed circuit board 20 and the process of providing the shielding part 30 can also be performed simultaneously. More specifically, after the anisotropic conductive adhesive 41, the printed circuit boards 10, 20 and the shielding part 30 are aligned, bonding is performed using a flat press. Under the conditions of this embodiment, for example, the pressing is performed at 170° C. for 60 seconds. Thus, the process can be shortened, and the bonded printed circuit board 1 can be manufactured more cheaply.

[0093] Furthermore, in the joined printed circuit board 1 provided in the first embodiment, the metal foil 31 (conductive layer) of the shield 30 is electrically connected to the ground layer 14. Thus, the return current induced in the ground layer of one printed circuit board by the signal flowing through the signal line is not cut off at the joined portion and flows to the ground layer of the other printed circuit board. Thus, the transmission characteristics can be improved.

[0094] In addition, the first conductive layer and the second conductive layer are formed integrally in the conductive layer of the shield portion 30. This can reduce the number of locations where electrical characteristics change on the path through which a ground return current flows, and can further improve the transmission characteristics.

[0095] Furthermore, a material with a low dielectric constant and a low dielectric loss tangent can be applied to the printed circuit board 10, and a material with a high dielectric constant and a low dielectric loss tangent can be applied to the printed circuit board 20. In this way, different materials can be applied to the printed circuit boards 10 and 20, and a cable substrate with high transmission characteristics and a space-saving antenna substrate can coexist.

[0096] In addition, the printed circuit board 10 may be a flexible printed circuit board or a rigid printed circuit board. The same is true for the printed circuit board 20. In addition, by making one of the printed circuit boards 10 and 20 a flexible printed circuit board and the other a rigid printed circuit board, a rigid-flexible structure can be provided at a low cost.

[0097] In addition, in the above description, the printed circuit board 10 has two circuit layers (including signal lines, ground lines and / or ground layers). Not limited to this, the printed circuit board 10 may also have any number of circuit layers. In addition, the printed circuit board 10 may also have 1-5 circuit layers.

[0098] Similarly, in the above description, the printed circuit board 20 has two circuit layers. Without being limited thereto, the printed circuit board 20 may also have any number of circuit layers. In addition, the printed circuit board 20 may also have 1 to 5 circuit layers. In the case of using a printed circuit board 20 having any number of circuit layers, since the ground layer is formed by the shielding portion 30, the number of circuit layers can be reduced by one. More specifically, in the manufacture of the printed circuit board 20, fewer circuit layers than the circuit layers usually used can be used. Therefore, the bonded printed circuit board 1 can be manufactured more cheaply.

[0099] In addition, in the above description, the printed circuit board 10 is a cable substrate or a main substrate connected to the antenna substrate. Not limited to this, the printed circuit board 10 can also be a cable substrate that connects main substrates to each other. In this case, a shielding portion that acts as a grounding for a signal line provided on the cable substrate can also be provided. For example, the shielding portion has a conductive layer that covers the signal line of the cable substrate when the cable substrate is observed in the thickness direction. The conductive layer can also be electrically connected to the ground layer of the main substrate. As a result, for example, compared with the case of using coplanar wiring, the width of the signal line can be further increased, and a cable substrate with high transmission characteristics in high-frequency band signals can be provided. Moreover, since the etching process can be omitted, the cable substrate can be manufactured inexpensively.

[0100] In addition, in the above description, the printed circuit board 20 is an antenna substrate. Not limited to this, the printed circuit board 20 can also be a cable substrate or a main substrate. In addition, both the printed circuit boards 10 and 20 can be cable substrates. In this way, a long cable can be made. Furthermore, the orientation of the length direction of each printed circuit board can also be different. For example, the printed circuit boards 10 and 20 are joined in the joining area, and the orientations of the length directions of each other intersect to form a right angle or other angles. In this way, cables of various shapes using multiple printed circuit boards can be made.

[0101] In the above description, the case where the extending directions of the signal lines 11 and 21 of the printed circuit boards 10 and 20 are parallel is described. However, the present invention is not limited thereto, and the signal lines 11 and 21 may be bent near the joining area of ​​the printed circuit boards 10 and 20 at the insulating substrate 15 to form a right angle, other angles, or an arc shape.

[0102] In addition, the structure of this embodiment can also be applied to the joint portion of a cable substrate having a power line and a main substrate having an IC. In this case, for example, the cable substrate can be regarded as a printed circuit board 10, the main substrate can be regarded as a printed circuit board 20, and a shielding portion 30 can be provided as in this embodiment. The power line of the cable substrate can replace the signal line 11 or be provided together with the signal line 11. The cable substrate having a power line has a problem of damaging the power integrity due to the voltage drop caused by the IC. Therefore, as described above, the number of conductor layers is increased by providing a shielding portion 30. This can cheaply and easily reduce the impedance of the cable (PDN: Power Delivery Network), guide the power line to directly under the IC, and improve the power integrity.

[0103] In addition, the conductive layer of the shielding part 30 is not limited to the metal foil 31. For example, the conductive layer may be a metal foil, a conductive paste layer, a solder layer (e.g., a paste solder layer), an isotropic conductive adhesive layer, or a conductive film layer. Here, the conductive film refers to, for example, a thin film that forms a mesh of fine wiring on a transparent resin and acts as a pseudo-transparent material. In addition, an isotropic conductive adhesive layer may be used instead of the anisotropic conductive adhesive layer 34 of the shielding part 30. Alternatively, the conductive layer of the shielding part 30 may be bonded to the grounding layer 14 by a conductive paste or solder, and bonded to the upper surface of the insulating substrate 25 and the insulating protective layer 19 by a conductive adhesive or an insulating adhesive.

[0104] Modifications 1 to 4 of the first embodiment are described below as examples in which the structure of the shield portion is different from that of the first embodiment. In the description of each modification, the difference from the first embodiment is mainly described, and the description of the same parts as the first embodiment is omitted.

[0105] (Variation 1 of the First Embodiment) Reference Figure 4 (a) A joined printed circuit board according to Modification 1 of the first embodiment will be described. Figure 4 (a) is a longitudinal cross-sectional view along the signal lines 11 and 21 of the joined printed circuit boards provided in this modification.

[0106] The shield portion 30A of this modification example has a conductive paste layer 32 instead of the metal foil 31 in the shield portion 30 of the first embodiment, and has an isotropic conductive adhesive layer 33 instead of the anisotropic conductive adhesive layer 34. Figure 4 As shown in (a) of FIG. 1 , the shield portion 30A of the present modification example includes a conductive paste layer 32, an isotropic conductive adhesive layer 33, and an insulating protective layer 39. The conductive paste layer 32 is an example of a conductive layer.

[0107] Furthermore, the “isotropic conductive adhesive” refers to a conductive adhesive (adhesive having conductivity) in which anisotropic conductive adhesive is removed.

[0108] As described above, according to the shield portion 30A of the present modification, for example, a shield portion having characteristics different from those of the shield portion 30 of the first embodiment can be configured.

[0109] (Variation 2 of the first embodiment) Reference Figure 4 (b) A joined printed circuit board provided in Modification 2 of the first embodiment will be described. Figure 4 (b) is a longitudinal cross-sectional view along the signal lines 11 and 21 of the joined printed circuit boards provided in this modification.

[0110] The shield portion 30B of this modification has a conductive paste layer 32 instead of the metal foil 31 in the shield portion 30 of the first embodiment. That is, the shield portion 30B has a conductive paste layer 32, an anisotropic conductive adhesive layer 34, and an insulating protective layer 39. In addition, a solder layer may be provided instead of the conductive paste layer 32. The conductive paste layer 32 or the solder layer is an example of a conductive layer.

[0111] The shield 30 of the first embodiment and the shield 30A of the first modification example are finished products formed integrally using, for example, a conductive layer, a conductive adhesive layer, and an insulating protective layer. In contrast, the shield 30B of this modification example is manufactured by, for example, providing an anisotropic conductive adhesive layer 34 and then applying a conductive paste layer 32 or a solder layer.

[0112] More specifically, first, the anisotropic conductive adhesive layer 34 is disposed and crimped. Then, conductive paste or solder is provided on the anisotropic conductive adhesive layer 34 by inkjet or screen printing. Then, the insulating protective layer 39 is disposed and crimped. The shielding portion 30B is provided through the above steps.

[0113] Furthermore, when the insulating protective layer 39 is provided, the crimping after the anisotropic conductive adhesive layer 34 is arranged can be omitted, and in the crimping after the insulating protective layer 39 is arranged, the anisotropic conductive adhesive layer 34 and the insulating protective layer 39 can be crimped simultaneously.

[0114] In this way, according to the shield portion 30A of the present modification, the shield portion can be provided by a different manufacturing method.

[0115] (Variation 3 of the first embodiment) Reference Figure 5 (a) A joined printed circuit board provided in Modification 3 of the first embodiment will be described. Figure 5(a) is a longitudinal cross-sectional view along the signal lines 11 and 21 of the joined printed circuit boards provided in this modification.

[0116] In the present modification, the shield portion 30C has an isotropic conductive adhesive layer 33 and an insulating protective layer 39. The isotropic conductive adhesive layer 33 is an example of a conductive layer.

[0117] The isotropic conductive adhesive layer 33 includes: an isotropic conductive adhesive layer 33a (first conductive portion) bonded to the upper surface of the insulating substrate 25; and an isotropic conductive adhesive layer 33b (second conductive portion) extending from the end of the printed circuit board 20 and bonded to the ground layer 14.

[0118] The isotropic conductive adhesive layer 33a is provided so as to cover the signal line 21 and the antenna 22 when the printed circuit board 20 is viewed in the thickness direction. Thus, the metal foil 31a functions as a ground for the signal line 21 and the antenna 22.

[0119] The isotropic conductive adhesive layer 33b is formed integrally with the isotropic conductive adhesive layer 33a, and is bonded to the ground layer 14. Thus, the isotropic conductive adhesive layer 33 and the ground layer 14 are electrically connected.

[0120] In this modification, isotropic conductive adhesive layer 33 as a conductive layer is directly bonded to printed wiring board 10 and printed wiring board 20. This makes it possible to more simply form the structure of the shielding portion.

[0121] (Variation 4 of the first embodiment) Reference Figure 5 (b) describes a joined printed circuit board provided in Modification 4 of the first embodiment. Figure 5 (b) is a longitudinal cross-sectional view along the signal lines 11 and 21 of the joined printed circuit boards provided in this modification.

[0122] In the present modification, the shield portion 30D includes a metal foil 31, an insulating adhesive layer 35a, and an insulating adhesive layer 35b. The metal foil 31 is an example of a conductive layer.

[0123] The metal foil 31 is provided across the upper surface of the insulating substrate 25 and the ground layer 14. More specifically, the metal foil 31 includes: a metal foil 31a (first conductive portion) bonded to the upper surface of the insulating substrate 25 via an insulating adhesive layer 35a; and a metal foil 31b (second conductive portion) bonded to the insulating protective layer 19 via an insulating adhesive layer 35b. The insulating adhesive layers 35a and 35b are, for example, NCF, NCP, or an insulating adhesive.

[0124] In addition, a portion of the metal foil 31b is electrically connected to the ground layer 14 at a position A in the figure through a conductive material 36. The conductive material 36 is, for example, solder, conductive paste, or conductive adhesive.

[0125] Furthermore, a portion of the metal foil 31b may be in direct contact with the ground layer 14 at the position A in the figure without passing through the conductive material 36. In this case, the metal foil 31b may be pressed from above using an insulating adhesive or the like.

[0126] In addition, an insulating protective layer may be provided on the metal foil 31 .

[0127] As described above, according to the shield portion 30D of the present modification, the shield portion can be configured using metal foil as a starting material.

[0128] (Variation 5 of the First Embodiment) Reference Figure 6 Modification 5 of the first embodiment will be described. One of the differences between this modification and the first embodiment is the number of layers of printed wiring board 10 . Figure 6 1 is a longitudinal cross-sectional view of the bonded printed circuit board provided in this modification along the signal lines 11 and 21. Hereinafter, this embodiment will be described mainly with respect to the parts different from the first embodiment, and the description of the parts identical to the first embodiment will be omitted.

[0129] The printed circuit board 10 of the present embodiment includes a signal line 11A, an insulating base material 16A, an insulating adhesive layer 17A, and a signal via 53 in addition to the printed circuit board 10 of the first embodiment.

[0130] The signal line 11A is a signal line provided in a layer different from the signal line 11, and is provided on the lower surface of the insulating substrate 15. In addition, the signal line 11A is electrically connected to the signal line 11 through the signal via 53. The signal via 53 is provided to penetrate the insulating substrate 15. In addition, a pair of ground lines may be provided on the lower surface of the insulating substrate 15 in a manner of sandwiching the signal line 11A. In addition, the ground line and the ground layer 13 and / or the ground line 12 may also be electrically connected through the ground via.

[0131] The insulating adhesive layer 17A is provided on the lower surface of the insulating base material 15 so as to bury the signal line 11A. The insulating base material 16A is provided on the lower surface of the insulating adhesive layer 17A. In addition, the insulating adhesive layer 17A may not be provided. In this case, the insulating base material 16A may also be provided so as to bury the signal line 11A.

[0132] The ground layer 13 is provided on the lower surface of the insulating base material 16A. The insulating protection layer 18 is provided so as to cover the ground layer 13.

[0133] As described above, according to the joint printed circuit board provided in Variation 5 of the first embodiment, a multilayer substrate including four circuit layers can be used as the printed circuit board 10. Thus, for example, in a joint printed circuit board in which a multilayer substrate and an antenna substrate are integrated, transmission characteristics can be improved with a simple structure.

[0134] (Second Embodiment) Reference Figure 7 The second embodiment will be described. One of the differences between the present embodiment and the first embodiment is, for example, the shape of the end portion of the printed wiring board 10 . Figure 7 It is a longitudinal cross-sectional view along the signal lines 11 and 21 of the bonded printed circuit boards provided in this embodiment.

[0135] In this embodiment, unlike the first embodiment, the insulating base material 16 and the insulating adhesive layer 17 (second insulating layer) are stacked on the insulating base material 15 in such a manner as to completely bury the signal line 11 and the ground line 12. In other words, the insulating adhesive layer 17 is stacked on the insulating base material 15 in such a manner that the upper surface of the insulating base material 15 and the signal line 11 and the ground line 12 are not exposed.

[0136] Therefore, in order to electrically connect the signal line 11 with the signal line 21, the printed circuit board 10 further includes a signal via 54. The signal via 54 penetrates the insulating substrate 16 and the insulating adhesive layer 17, and electrically connects the signal line 11 with a pad 55 provided on the upper surface of the insulating substrate 16. The signal via 54 is an example of an interlayer connection portion.

[0137] In addition, the lower surface (fifth main surface) of the insulating base material 25 is bonded to the upper surface (fourth main surface) of the insulating base material 16 via an anisotropic conductive adhesive 41 .

[0138] Furthermore, the pad 55 and the end of the signal line 21 are electrically connected via the anisotropic conductive adhesive 41 .

[0139] According to the bonded printed circuit board provided in the second embodiment, in a structure in which the signal line 11 is not exposed at the end portion, the transmission characteristics can be improved with a simple structure.

[0140] Furthermore, the thickness of the insulating base material 25 in this embodiment may be thinner than that of the insulating base material 25 in the first embodiment. Thus, the thickness of the entire bonded printed wiring board 1 can be suppressed.

[0141] (Variation of the Second Embodiment) Reference Figure 8 A modification of the second embodiment will be described. The difference between this modification and the second embodiment is the number of layers of printed wiring board 10 . Figure 8 This is a longitudinal cross-sectional view along signal lines 11 and 21 of the joined printed circuit boards provided in this modification.

[0142] The printed circuit board 10 of the present embodiment includes a signal line 11A, an insulating adhesive layer 17A, an insulating base material 16A, and a signal via 53 in addition to the printed circuit board 10 of the first embodiment.

[0143] In addition, since the signal line 11A, the insulating adhesive layer 17A, the insulating base material 16A, and the signal via 53 are the same as those in the fifth modification of the first embodiment, the description thereof will be omitted.

[0144] According to the bonded printed circuit board provided in the modification of the second embodiment, a multilayer substrate including four circuit layers can be used as the printed circuit board 10. Thus, for example, in a multilayer substrate where the signal line 11 is not exposed at the end, the transmission characteristics can be improved with a simple structure.

[0145] Next, a third embodiment and a fourth embodiment in which an interlayer connection portion is provided on the printed wiring board 20 will be described.

[0146] (Third Embodiment) Reference Fig. 9 The bonded printed circuit boards provided in the third embodiment will be described. Fig. 9 It is a longitudinal cross-sectional view of the bonded printed circuit board provided in this embodiment along the signal lines 11 and 21. Hereinafter, this embodiment will be described mainly with respect to the parts different from the second embodiment, and the description of the parts identical to the second embodiment will be omitted.

[0147] The printed circuit board 20 of the present embodiment includes a signal line 21, a ground layer 24, an insulating base material 25, an insulating protection layer 28, and a conductive paste 61. The conductive paste 61 is an example of a third conductive material.

[0148] The signal line 21 is provided on the upper surface (sixth main surface) of the insulating base material 25. The signal line 21 is covered by the insulating protective layer 28. The signal line 21 is electrically connected to the pad 55 via the conductive paste 61. In addition, a part of the signal line 21 may be an antenna.

[0149] The ground layer 24 is provided on the lower surface (fifth main surface) of the insulating base material 25. The ground layer 24 is provided to cover the signal line 21 when the printed circuit board 20 is viewed in the thickness direction. The ground layer 14 and the ground layer 24 are electrically connected by an anisotropic conductive adhesive 41.

[0150] In this embodiment, insulating adhesive layer 71, insulating protective layer 73, and insulating adhesive layer 72 are sequentially stacked between the upper surface of insulating base material 16 and the lower surface of insulating base material 25. This can improve the insulation properties of ground layer 14 and ground layer 24.

[0151] like Fig. 9As shown, openings for filling the anisotropic conductive adhesive 41 and the conductive paste 61 are respectively provided on the insulating adhesive layer 71 , the insulating protection layer 73 and the insulating adhesive layer 72 .

[0152] The insulating protection layer 28 is provided to cover the signal line 21. The material of the insulating protection layer 28 is the same as that of the insulating protection layer 29.

[0153] The conductive paste 61 fills the through-holes provided in the insulating base material 25 , the insulating adhesive layer 71 , the insulating protection layer 73 , and the insulating adhesive layer 72 , thereby electrically connecting the signal line 21 and the pad 55 .

[0154] For example, the conductive paste 61 is formed by the method described in Japanese Patent No. 6177639. In addition, the conductive paste 61 may be formed by a paste formed into an alloy at a temperature close to the curing temperature of the anisotropic conductive adhesive 41 (e.g., 170° C.). Thus, the formation of the conductive paste 61 and the bonding using the anisotropic conductive adhesive 41 can be performed simultaneously. Thus, the bonded printed circuit board provided in this embodiment can be provided at a lower cost.

[0155] Furthermore, the formation of the conductive paste 61, the bonding using the anisotropic conductive adhesive 41, and the bonding of the shielding portion 30 can also be performed simultaneously. Thus, the bonded printed circuit board provided in this embodiment can be provided more cheaply. When the formation of the conductive paste 61, the bonding using the anisotropic conductive adhesive 41, and the bonding of the shielding portion 30 are performed simultaneously, for example, a flat press is used.

[0156] like Fig. 9 As shown, the metal foil 31a (first conductive portion) of the shield portion 30 is bonded to the insulating protective layer 28. The metal foil 31a is provided so as to sandwich the insulating protective layer 28 together with the signal line 21, and the metal foil 31a functions as a ground for the signal line 21.

[0157] Thus, the printed circuit board 20 of the present embodiment can form a stripline structure including the signal line 21, the ground layer 24 and the metal foil 31a. That is, a double-sided metal-clad laminate can be used as a starting material for the printed circuit board 20, and a stripline structure can be provided at a low cost compared to the case where a three-layer substrate is used as a starting material.

[0158] Furthermore, by using the signal line 21 as an antenna, a strip line antenna having high transmission characteristics can be provided with a simple structure.

[0159] In addition, the ground layer 24 may not be provided. Alternatively, as in a fourth embodiment described later, a signal line different from the signal line 21 or an antenna may be provided on the lower surface of the insulating base material 25 instead of the ground layer 24 .

[0160] In addition, although the printed wiring board 10 of this embodiment has the same structure as the printed wiring board of the second embodiment, a printed wiring board having the same structure as the printed wiring board of the first embodiment may be used as the printed wiring board 10 of this embodiment.

[0161] (Fourth Embodiment) Reference Fig.10 A description will be given of the bonded printed circuit boards provided in the fourth embodiment. Fig.10 This is a longitudinal cross-sectional view of the bonded printed circuit board provided in this embodiment along the signal lines 11 and 21. Hereinafter, this embodiment will be described mainly with respect to the parts different from the second and third embodiments, and description of the parts identical to the second and third embodiments will be omitted.

[0162] The printed wiring board 20 of the present embodiment includes a signal line 21 , a signal line 21A, and an insulating base material 25 .

[0163] The signal line 21 is provided on the lower surface (fifth main surface) of the insulating base material 25. The signal line 21 is electrically connected to the pad 55 via the anisotropic conductive adhesive 41.

[0164] Signal line 21A is provided on the lower surface of insulating substrate 25 with a gap between signal line 21. Signal line 21A is electrically connected to pad 55 via conductive paste 62. Signal line 21A may be provided on a different layer from signal line 21, such as on the upper surface of insulating substrate 25.

[0165] The conductive paste 62 fills the insulating adhesive layer 71, the insulating protection layer 73, and the insulating adhesive layer 72 to electrically connect the signal line 21 and the pad 55. The conductive paste 62 is an example of a third conductive material.

[0166] When the signal line 21 and the signal line 21A have different electrical characteristics (for example, current capacity), the conductive paste 62 and the anisotropic conductive adhesive 41 can be used separately. For example, when a large current does not flow through both the signal line 21 and the signal line 21A, the anisotropic conductive adhesive can be used instead. Fig. 9 The conductive paste 62 in the embodiment of the present invention.

[0167] In addition, the printed circuit board 20 of the present embodiment includes a plurality of signal lines 21 and 21A. Therefore, when the printed circuit board 20 is used as an antenna substrate, for example, an ultra-wideband (UWB) antenna can be manufactured.

[0168] In addition, in the present embodiment, the signal lines 21 and 21A are electrically connected to the same pad 55. However, the present invention is not limited to this, and the signal lines 21 and 21A may be electrically connected to different pads.

[0169] (Fifth Embodiment) Reference Fig.11 A joined printed wiring board 1A according to the fifth embodiment will be described. Fig.11 (a) is a plan view of the bonded printed wiring board 1A provided in the present embodiment before bonding. Fig.11 (b) is a longitudinal cross-sectional view along the ground line 12A of the joined printed circuit board 1A provided in the present embodiment. Figure 1 In (a), the ground layer 14, the insulating protection layer 19 and the shielding portion 30 are omitted.

[0170] This embodiment is a case where the printed wiring board 10 includes one circuit layer (coplanar structure). Hereinafter, this embodiment will be described mainly with respect to the parts different from the first embodiment, and description of the parts identical to the first embodiment will be omitted.

[0171] like Fig.11 As shown, the printed circuit board 10 provided in this embodiment includes a signal line 11 , a ground line 12 , an insulating substrate 15 and an insulating protection layer 19 .

[0172] The signal line 11 is provided on the upper surface of the insulating base material 15. In addition, a pair of ground lines 12A are provided on the upper surface of the insulating base material 15 so as to sandwich the signal line 11.

[0173] In order to cover the signal line 11 and the ground line 12A, an insulating protective layer 19 is provided. The insulating protective layer 19 is provided so that the ends of the signal line 11 and the ground line 12A are exposed on the upper surface of the insulating substrate 15. In addition, an opening 19a is provided in the insulating protective layer 19, and the ground line 12A is exposed inside the opening 19a.

[0174] In the metal foil 31 of the shield portion 30, the metal foil 31b is bonded to the ground line 12A exposed inside the opening 19a through the anisotropic conductive adhesive layer 34. Thus, the metal foil 31 and the ground line 12A are electrically connected.

[0175] As described above, according to the joined printed wiring board 1A provided in the fifth embodiment, even in the case of the printed wiring board 10 having a coplanar structure, the transmission characteristics can be improved with a simple structure by providing the shielding portion 30 .

[0176] (Sixth Embodiment) Reference Fig.12 A printed wiring board 10A provided in the sixth embodiment will be described. Fig.12 1 is a longitudinal cross-sectional view of a printed wiring board 10A provided in this embodiment along signal lines 11 and 21. In this embodiment, a portion of the insulating base material of the printed wiring board 10A is extended instead of joining two printed wiring boards as in the first to fifth embodiments.

[0177] The printed circuit board 10A includes signal lines 11 , 11A, 21 , ground layers 13 , 14 , insulating base materials 15 , 16 , 16A, insulating protection layers 18 , 19 , 29 , a signal via 54 , and a shielding portion 30 .

[0178] The signal lines 11, 11A, the ground layer 13, the insulating substrates 15, 16A and the insulating protective layers 18, 19 are connected to the Figure 8 The modified example of the second embodiment shown in FIG. 1 is the same as that of the second embodiment, so the description thereof will be omitted. Fig.12 In the embodiment, the insulating adhesive layers 17, 17A are omitted.

[0179] The insulating base material 16 is stacked on the insulating base material 15 and includes a stacked portion in which the signal line 11 is embedded and an extending portion extending from the stacked portion in the longitudinal direction (right direction).

[0180] The signal line 21 is provided on the upper surface of the insulating substrate 16 at the laminated portion and the extended portion of the insulating substrate 16. The signal line 21 is electrically connected to the signal line 11 through the signal via 54 provided in a manner penetrating the insulating substrate 16. The signal line 21 may be an antenna. In this case, the portion of the signal line 21 provided at the extended portion of the insulating substrate 16 may have a shape such as Figure 1 The antenna 22 shown in (a) is shaped like this.

[0181] The ground layer 14 is provided in a laminated portion of the insulating base material 16 so as to be spaced apart from the signal line 21 .

[0182] The insulating protection layer 29 is provided to cover the signal line 21 and a part of the ground layer 14. In addition, the insulating protection layer 29 may also be formed integrally with the insulating protection layer 19.

[0183] The shield portion 30 is provided across the laminated portion and the extended portion of the insulating base material 16 , and includes a metal foil 31 , an anisotropic conductive adhesive layer 34 , and an insulating protective layer 39 .

[0184] The metal foil 31 (conductive layer) is provided across the laminated portion and the extended portion of the insulating base material 16. More specifically, the metal foil 31 includes a metal foil 31a (first conductive portion) bonded to the insulating protective layer 29 and a metal foil 31b (second conductive portion) bonded to the ground layer 14.

[0185] The metal foil 31a is provided so as to cover the signal line 21 when the insulating base material 16 is viewed in the thickness direction. Thus, the metal foil 31a functions as a ground for the signal line 21.

[0186] The metal foil 31b is formed integrally with the metal foil 31a, and is bonded to the ground layer 14 via the anisotropic conductive adhesive layer 34. Thus, the metal foil 31 and the ground layer 14 are electrically connected.

[0187] As described above, according to the printed wiring board 10A provided in the sixth embodiment, by providing the shield portion 30 , it is possible to improve the transmission characteristics with a simple structure, not limited to the case where two printed wiring boards are joined.

[0188] Based on the above description, a person skilled in the art may think of additional effects and various modifications of the present invention, but the present invention is not limited to the above embodiments, and the constituent elements in different embodiments may be appropriately combined. For example, in the second to sixth embodiments, shielding parts 30A-30D may be used to replace shielding part 30. Various supplements, changes and partial deletions may be made within the scope of the conceptual ideas and purposes of the present invention derived from the contents specified in the claims and their equivalents.

Claims

1. A method for bonding a printed circuit board, comprising: a first printed circuit board; a second printed circuit board, the second printed circuit board being bonded to the first printed circuit board; and a shield having a conductive layer disposed across the first printed circuit board and the second printed circuit board; Wherein, the first printed circuit board comprises: a first insulating layer, the first insulating layer having a first main surface and a second main surface opposite to the first main surface; a first signal line, the first signal line being arranged on the first main surface; a second insulating layer, the second insulating layer having a third main surface opposite to the first main surface and a fourth main surface on the opposite side of the third main surface, the second insulating layer being stacked on the first insulating layer in a manner of burying at least a portion of the first signal line; and a ground layer, the ground layer being provided on the fourth main surface in a manner of covering the first signal line when the first printed circuit board is viewed in a thickness direction; Wherein, the second printed circuit board comprises: a third insulating layer, the third insulating layer having a fifth main surface bonded to the first printed circuit board and a sixth main surface opposite to the fifth main surface; and a second signal line electrically connected to the first signal line; Wherein, the conductive layer of the shielding portion comprises: a first conductive portion, the first conductive portion being configured to cover the second signal line when the second printed circuit board is viewed in a thickness direction; and a second conductive portion, wherein the second conductive portion is formed as a whole with the first conductive portion and is joined to the ground layer.

2. The bonded printed circuit board according to claim 1, wherein The second printed circuit board is an antenna substrate provided with an antenna, and the antenna is connected to the second signal line and receives wireless signals; The first printed circuit board is a cable substrate to which the first signal line is connected to other substrates, or a main substrate on which a semiconductor chip is mounted, the semiconductor chip processing a wireless signal received by the antenna.

3. The bonded printed circuit board according to claim 2, wherein: The first insulating layer of the first printed circuit board includes a first insulating substrate, and the first insulating substrate is composed of a liquid crystal polymer, a fluorine-based material, a polyimide-based material or a cycloolefin polymer; The second insulating layer of the first printed circuit board comprises a second insulating substrate, and the second insulating substrate is composed of a liquid crystal polymer, a fluorine-based material, a polyimide-based material or a cycloolefin polymer; The third insulating layer of the second printed circuit board includes a third insulating substrate, and the third insulating substrate is made of polyimide materials, liquid crystal polymers, fluorine materials, epoxy glass, cycloolefin polymers, ceramics or polyphenylene ether.

4. The bonded printed circuit board according to claim 1, wherein The conductive layer of the shield portion has a metal foil, a conductive paste layer, a solder layer, an isotropic conductive adhesive layer, or a conductive film layer.

5. The bonded printed circuit board according to claim 4, wherein: The conductive layer of the shielding portion is a metal foil, The shielding part further has an anisotropic conductive adhesive layer for bonding the metal foil to the first printed circuit board and the second printed circuit board.

6. The bonded printed circuit board according to claim 4, wherein: The conductive layer of the shielding portion is a conductive paste layer, The shielding part also has an isotropic conductive adhesive layer for adhering the conductive paste layer to the first printed circuit board and the second printed circuit board.

7. The bonded printed circuit board according to claim 4, wherein: The conductive layer of the shielding portion is a conductive paste layer or a solder layer, The shielding portion further has an anisotropic conductive adhesive layer for adhering the conductive paste layer or the solder layer to the first printed circuit board and the second printed circuit board.

8. The bonded printed circuit board according to claim 4, wherein: The conductive layer of the shield is an isotropic conductive adhesive layer.

9. The bonded printed circuit board according to claim 4, wherein: The conductive layer of the shielding portion is a metal foil, The shielding portion further comprises: a first insulating adhesive layer, the first insulating adhesive layer being disposed on the second printed circuit board, the first insulating adhesive layer bonding the first conductive portion of the conductive layer to the second printed circuit board; and a second insulating adhesive layer, the second insulating adhesive layer being disposed on the first printed circuit board, the second insulating adhesive layer bonding the second conductive portion of the conductive layer to the first printed circuit board; The second conductive portion is electrically connected to the ground layer through a conductive material.

10. The joined printed circuit board according to any one of claims 1 to 9, wherein The second insulating layer of the first printed circuit board is stacked on the first insulating layer in such a manner that the first main surface and the end of the first signal line are partially exposed. The second signal line of the second printed circuit board is arranged on the fifth main surface, The first conductive portion of the shield portion is bonded to the sixth main surface, The fifth main surface is bonded to the partially exposed portion of the first main surface of the first printed circuit board through a second conductive material, An end portion of the first signal line and the second signal line are electrically connected through the second conductive material.

11. The joined printed circuit board according to any one of claims 1 to 9, wherein: The first printed circuit board further includes an interlayer connection portion, the interlayer connection portion penetrates the second insulating layer and electrically connects the first signal line to a pad provided on the fourth main surface. The fifth main surface of the second printed circuit board is bonded to the fourth main surface of the first printed circuit board, The first signal line and the second signal line are electrically connected through the interlayer connection portion and the pad.

12. The bonded printed circuit board according to claim 11, wherein The second signal line of the second printed circuit board is arranged on the fifth main surface, The first conductive portion of the shield portion is bonded to the sixth main surface, The pad of the interlayer connection portion and the second signal line are electrically connected through a second conductive material.

13. The bonded printed circuit board according to claim 12, wherein: The second printed circuit board further includes a third signal line disposed on the third insulating layer and different from the second signal line. The pad of the interlayer connection portion is electrically connected to the third signal line through a third conductive material.

14. The bonded printed circuit board according to claim 11, wherein The second signal line of the second printed circuit board is arranged on the sixth main surface, The second printed circuit board also includes: an insulating protective layer, wherein the insulating protective layer covers the second signal line; and a third conductive material, the third conductive material filling a through hole penetrating the third insulating layer and electrically connecting the pad of the first printed circuit board and the second signal line; The first conductive portion of the shielding portion is bonded to the insulating protection layer.

15. The bonded printed circuit board according to claim 14, wherein The second printed circuit board further includes a second ground layer disposed on the fifth main surface. The ground layer and the second ground layer are electrically connected through a second conductive material.

16. The bonded printed circuit board according to claim 11, wherein A third insulating adhesive layer, a second insulating protective layer, and a fourth insulating adhesive layer are stacked in this order between the fourth main surface and the fifth main surface.

17. The joined printed circuit board according to any one of claims 1 to 9, wherein: The first printed circuit board and / or the second printed circuit board is a flexible printed circuit board.

18. The joined printed circuit board according to any one of claims 1 to 9, wherein: The first printed circuit board has 2-5 circuit layers.

19. The joined printed circuit board according to any one of claims 1 to 9, wherein: The second printed circuit board has 1 to 5 circuit layers.

20. A bonded printed circuit board comprising: a first printed circuit board; a second printed circuit board, the second printed circuit board being bonded to the first printed circuit board; and a shield having a conductive layer disposed across the first printed circuit board and the second printed circuit board; Wherein, the first printed circuit board comprises: a first insulating layer, the first insulating layer having a first main surface and a second main surface opposite to the first main surface; a first signal line, the first signal line being arranged on the first main surface; and a ground line, the ground line being arranged on the first main surface in a manner of sandwiching the first signal line; Wherein, the second printed circuit board comprises: a second insulating layer having a third main surface bonded to the first main surface and a fourth main surface on the opposite side of the third main surface; and a second signal line, the second signal line being disposed on the third main surface and electrically connected to the first signal line through a conductive material; Wherein, the conductive layer of the shielding portion comprises: a first conductive portion, the first conductive portion being provided on the fourth main surface in a manner of covering the second signal line when the second printed circuit board is viewed in a thickness direction; and a second conductive portion, the second conductive portion being formed as a whole with the first conductive portion and being joined to the ground line.

21. A printed circuit board, comprising: a first insulating layer, the first insulating layer having a first main surface and a second main surface opposite to the first main surface; a first signal line, the first signal line being arranged on the first main surface; a second insulating layer, the second insulating layer having a third main surface opposite to the first main surface and a fourth main surface on the opposite side of the third main surface, the second insulating layer including a stacked portion stacked on the first insulating layer and an extending portion extending from the stacked portion in a length direction; a second signal line, the second signal line being provided on the fourth main surface at the stacked portion and the extended portion of the second insulating layer; a ground layer, the ground layer being provided on the fourth main surface at the stacked portion of the second insulating layer in a manner spaced apart from the second signal line; an interlayer connection portion, the interlayer connection portion penetrating the second insulating layer and electrically connecting the first signal line and the second signal line; an insulating protective layer, the insulating protective layer being arranged in a manner of covering the second signal line; and a shielding part, wherein the shielding part has a conductive layer, the conductive layer includes a first conductive part and a second conductive part, the first conductive part is configured to cover the second signal line when the second insulating layer is observed in the thickness direction, and the second conductive part is formed as a whole with the first conductive part and is joined to the ground layer.

22. A method for manufacturing a bonded printed circuit board, comprising the following steps: A first printed circuit board is prepared, wherein The first printed circuit board includes: a first insulating layer, the first insulating layer having a first main surface and a second main surface on the opposite side of the first main surface; a first signal line, the first signal line is provided on the first main surface; a second insulating layer, the second insulating layer having a third main surface opposite to the first main surface and a fourth main surface on the opposite side of the third main surface, the second insulating layer being stacked on the first insulating layer in a manner of burying the first main surface and at least a part of the first signal line; and a ground layer, the ground layer being provided on the fourth main surface in a manner of covering the first signal line when the second insulating layer is observed in the thickness direction; preparing a second printed circuit board, wherein the second printed circuit board comprises: a third insulating layer, the third insulating layer having a fifth main surface and a sixth main surface opposite to the fifth main surface; and a second signal line, the second signal line being provided on the third insulating layer; Joining the first printed circuit board and the second printed circuit board through a conductive material; joining the fifth main surface of the second printed circuit board to the first printed circuit board to electrically connect the first signal line and the second signal line; A shielding portion having a conductive layer is provided, wherein the conductive layer includes a first conductive portion and a second conductive portion formed integrally with the first conductive portion, the first conductive portion is joined to the second printed circuit board in a manner that covers the second signal line when the second printed circuit board is observed in a thickness direction, and the second conductive portion is joined to the ground layer.

23. The method for manufacturing a bonded printed circuit board according to claim 22, wherein: The step of bonding the first printed circuit board and the second printed circuit board and the step of providing the shielding portion are performed simultaneously.

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