Wiring board, electronic device, and electronic module

Abstract

The purpose of the present invention is to reduce the reflection loss of a high-frequency signal at a connection part between a signal wiring and a signal through conductor while reducing the size of a wiring substrate. The differential wiring has a pair of signal wirings arranged between adjacent insulating layers in the stacking direction or on the first surface of the insulating substrate. The differential through conductor has a pair of signal through conductors arranged through the at least one insulating layer. The outer diameter of a portion of the signal through conductor, which is a portion connected to the first end portion and / or the second end portion of the signal wiring, is smaller than the outer diameter of a portion continuous to the portion connected to the portion.

Description

Technical Field

[0001] This invention relates to a wiring board, an electronic device, and an electronic module. Background Technology

[0002] In wiring substrates used to mount high-speed semiconductor devices, optoelectronic semiconductor devices, and other electronic components, differential wiring and differential through conductors are used to efficiently propagate high-speed, high-frequency signals. A differential wiring has a pair of signal wirings arranged between insulating layers of an insulating substrate or on a first surface of the insulating substrate. A differential through conductor has a pair of signal through conductors arranged and penetrating at least one insulating layer of the insulating substrate, and the signal through conductors are electrically connected to the signal wirings.

[0003] The ends of the signal wiring and the signal through conductor are connected in an L-shape. The abrupt change in direction between these two ends creates a discontinuity in the transmission line, resulting in high-frequency signal reflection. Consequently, at the connection point between the signal wiring and the signal through conductor, the reflection loss of the high-frequency signal increases, impairing its transmission and reducing the performance of electronic components.

[0004] Therefore, a wiring substrate (see Patent Document 1) has been developed that can reduce the reflection loss of high-frequency signals in the connection between signal wiring and signal through conductors. In the wiring substrate described in Patent Document 1, a pair of signal wirings (referred to as line conductors in Patent Document 1) are connected to a pair of signal through conductors via a pair of connecting line portions. The spacing between the pair of connecting line portions gradually increases as they approach the signal through conductors.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2008-311682 Summary of the Invention

[0008] The wiring substrate of the present invention comprises: an insulating substrate formed by stacking a plurality of insulating layers, having a first surface and a second surface opposite to the first surface; differential wiring having a pair of signal wirings arranged between adjacent insulating layers in the stacking direction or on the first surface; a differential through conductor having a pair of signal through conductors arranged to penetrate at least one of the insulating layers, the signal through conductors being electrically connected to the signal wirings; a ground wiring layer located between adjacent insulating layers in the stacking direction, having an opening for the differential through conductors to pass through; and a ground through conductor penetrating at least one of the insulating layers, electrically connecting opposing ground wiring layers in the stacking direction to each other, wherein the outer diameter of a portion of the signal through conductor, i.e., the portion connected to the first end and / or the second end of the signal wirings, is smaller than the outer diameter of the portion continuous with the connected portion.

[0009] The electronic device of the present invention has a wiring substrate of the present invention and electronic components mounted on a first side of the wiring substrate.

[0010] The electronic module of the present invention includes the electronic device of the present invention and a module substrate on which the electronic device is mounted. Attached Figure Description

[0011] Figure 1 This is a schematic cross-sectional view of the wiring substrate according to the first embodiment of the present invention.

[0012] Figure 2 It is along Figure 1 A schematic enlarged sectional view of line II-II in the diagram.

[0013] Figure 3 It is along Figure 1 A schematic enlarged cross-sectional view of line III-III in the diagram.

[0014] Figure 4 This is a schematic cross-sectional view of a wiring substrate according to another embodiment of the first embodiment of the present invention.

[0015] Figure 5 This is a schematic cross-sectional view of a wiring substrate according to another embodiment of the first embodiment of the present invention.

[0016] Figure 6 This is a schematic cross-sectional view of the electronic module according to the first embodiment of the present invention.

[0017] Figure 7 This is a schematic cross-sectional view of the wiring substrate according to the second embodiment of the present invention.

[0018] Figure 8 This is a schematic cross-sectional view of the wiring substrate according to the third embodiment of the present invention.

[0019] Figure 9 This is a schematic cross-sectional view of the wiring substrate according to the fourth embodiment of the present invention.

[0020] Figure 10 This is a schematic cross-sectional view of the wiring substrate according to the fifth embodiment of the present invention.

[0021] Figure 11 This is a diagram illustrating the simulation model of the embodiments and comparative examples.

[0022] Figure 12 This is a graph showing the relationship between the signal frequency and the signal reflection loss in the case of the embodiments and comparative examples, representing the simulation results of signal transmission.

[0023] Figure 13 It is a graph showing the simulation results of signal transmission under the embodiments and comparative examples, i.e., the relationship between time and characteristic impedance. Detailed Implementation

[0024] In the wiring substrate described in Patent Document 1, although the reflection loss of high-frequency signals at the connection between the signal wiring and the signal through conductor can be reduced, the spacing between a pair of connection lines gradually increases as they approach the signal through conductor. As a result, the wiring substrate tends to expand in the direction of the spacing between the pair of connection lines, in other words, in the direction of the arrangement of a pair of signal wirings. Therefore, it is desirable to both miniaturize the wiring substrate and reduce the reflection loss of high-frequency signals at the connection between the signal wiring and the signal through conductor, thereby improving the transmission performance of high-frequency signals.

[0025] According to the present invention, it is possible to both miniaturize the wiring substrate and reduce the reflection loss of high-frequency signals in the connection between the signal wiring and the signal transmission conductor, thereby improving the transmission performance of high-frequency signals.

[0026] Hereinafter, the wiring board, electronic device, and electronic module of the embodiments will be described in detail using the accompanying drawings. However, for ease of explanation, the figures referred to below only show simplified components necessary for illustrating the embodiments. Therefore, the wiring board, electronic device, and electronic module of the embodiments may include any components not shown in the figures. The dimensions of the components in the figures do not faithfully represent the actual dimensions of the components or the dimensional proportions of each component. For convenience, an orthogonal coordinate system XYZ is used to define the orientation of the wiring board, electronic device, and electronic module. The positive side of the X direction is the right side, the negative side of the X direction is the left side, the positive side of the Y direction is the front side, the negative side of the Y direction is the rear side, the positive side of the Z direction is the top side, and the negative side of the Z direction is the bottom side.

[0027] [First Implementation Method]

[0028] Reference Figures 1 to 5The wiring substrate 1 of the first embodiment of the present invention will be described. Figure 1 This is a schematic cross-sectional view of the wiring substrate 1 according to the first embodiment of the present invention. Figure 2 It is along Figure 1 A schematic enlarged sectional view of line II-II in the diagram. Figure 3 It is along Figure 1 A schematic enlarged cross-sectional view of line III-III in the diagram. Figure 4 and Figure 5 This is a schematic cross-sectional view of a wiring substrate 1 according to another embodiment of the first embodiment of the present invention.

[0029] like Figure 1 As shown in the example, the wiring substrate 1 of the first embodiment of the present invention may have a rectangular plate-shaped insulating substrate 2. The insulating substrate 2 may be constructed by stacking a plurality of insulating layers 21 having the same dielectric constant. The stacking direction of the plurality of insulating layers 21 may be the Z direction. The insulating substrate 2 may have a first surface 2a and a second surface 2b located on the opposite side of the first surface 2a.

[0030] The wiring substrate 1 may have a plurality of electrode pads 3 serving as a plurality of electrodes located on a first surface 2a of the insulating substrate 2. The plurality of electrode pads 3 may be formed on the first surface 2a of the insulating substrate 2. Additionally, the wiring substrate 1 may have a plurality of external electrodes 4 located on a second surface 2b of the insulating substrate 2. The plurality of external electrodes 4 may be formed on the second surface 2b of the insulating substrate 2.

[0031] like Figures 1 to 3 As shown in the example, the wiring substrate 1 may have differential wiring 5 for transmitting signals (high-frequency signals), and the differential wiring 5 may be located between adjacent insulating layers 21 in the stacking direction, i.e., the Z direction. The differential wiring 5 may have a pair of strip-shaped signal wirings 51, which are arranged in parallel between adjacent insulating layers 21 in the Z direction. The pair of signal wirings 51 may be located on the first surface 2a of the insulating substrate 2. In this specification, the description of "parallel" means that it is horizontally parallel and does not require strict parallelism.

[0032] like Figure 1 and Figure 2As shown in the example, the wiring substrate 1 may have a first differential through conductor 6 located between the first surface 2a of the insulating substrate 2 and the differential wiring 5. The first differential through conductor 6 may have a pair of cylindrical first signal through conductors 61 arranged and penetrating at least one insulating layer 21. The first signal through conductors 61 may be electrically connected to the signal wiring 51. One end of the first signal through conductor 61 may be connected to the electrode pad 3. The other end of the first signal through conductor 61 may be connected to one end (first end) of the signal wiring 51. When the pair of signal wirings 51 are located on the first surface 2a of the insulating substrate 2, the wiring substrate 1 may omit the first differential through conductor 6.

[0033] like Figure 1 and Figure 3 As shown in the example, the wiring substrate 1 may have a second differential through conductor 7 located between the differential wiring 5 and the second surface 2b of the insulating substrate 2. The second differential through conductor 7 may have a pair of cylindrical second signal through conductors 71 arranged and penetrating at least one insulating layer 21. The second signal through conductors 71 may be electrically connected to the signal wiring 51. One end of the second signal through conductor 71 may be connected to the other end (second end) of the signal wiring 51. The other end of the second signal through conductor 71 may be connected to the external electrode 4.

[0034] That is, such as Figure 1 As shown in the example, electrode pad 3 and external electrode 4 are electrically connected via a pair of first signal through conductors 61, a pair of signal wirings 51, and a pair of second signal through conductors 71. Signals (high-frequency signals) can be transmitted between electrode pad 3 and external electrode 4 via the pair of first signal through conductors 61, a pair of signal wirings 51, and a pair of second signal through conductors 71. The first differential through conductor 6 and the second differential through conductor 7 correspond to the differential through conductors described in the claims of this application. The first signal through conductor 61 and the second signal through conductor 71 correspond to the signal through conductors described in the claims of this application.

[0035] like Figure 1As shown in the example, the wiring substrate 1 can have a plurality of ground wiring layers 8, which are located between a plurality of adjacent insulating layers 21 in the stacking direction, i.e., the Z direction. A pair of ground wiring layers 8 can face each other in the Z direction while sandwiching the differential wiring 5. By having a pair of ground wiring layers 8 facing each other in the Z direction while sandwiching the differential wiring 5, the differential wiring 5 and the pair of ground wiring layers 8 form a strip-shaped line. Furthermore, the plurality of ground wiring layers 8 can have circular openings 81 for the passage of a first differential through conductor 6 or a second differential through conductor 7. The inner peripheral surface of the openings 81 of the plurality of ground wiring layers 8 can be separated from the first differential through conductor 6 or the second differential through conductor 7. By having the openings 81 in the plurality of ground wiring layers 8, the differential wiring 5 can be electrically insulated from the plurality of ground wiring layers 8 by the plurality of insulating layers 21.

[0036] like Figures 1 to 3 As shown in the example, the wiring substrate 1 may have a plurality of cylindrical grounding conductors 9 penetrating at least one insulating layer 21. The plurality of grounding conductors 9 can electrically connect the grounding wiring layers 8 facing each other in the stacking direction, i.e., the Z direction. Any one of the grounding conductors 9 may be located surrounding a first differential conductor 6. Any one of the grounding conductors 9 may be located surrounding a second differential conductor 7.

[0037] The characteristic impedance of the differential wiring 5 is set by specifying the width of the signal wiring 51 and the thickness of the insulating layer 21. The characteristic impedance of the first differential conductor 6 is set by specifying the outer diameter of the first signal conductor 61, the thickness of the insulating layer 21, and the size (inner diameter) of the opening 81 of the ground wiring layer 8. The characteristic impedance of the second differential conductor 7 is set by specifying the outer diameter of the second signal conductor 71, the thickness of the insulating layer 21, and the size (inner diameter) of the opening 81 of the ground wiring layer 8.

[0038] like Figure 1 and Figure 3 As shown in the example, the outer diameter of a portion of the second signal through conductor 71, namely the portion 71a connected to the second end of the signal wiring 51, can be smaller than the outer diameter of the portion 71b continuous with the connected portion 71a. The connected portion 71a of the second signal through conductor 71 can be located concentrically with the continuous portion 71b. The length of the connected portion 71a in the second signal through conductor 71 can, for example, be set to 0.1 mm or less. The outer diameter of the connected portion 71a of the second signal through conductor 71 is, for example, 50 μm or more and 75 μm or less. The outer diameter of the continuous portion 71b of the second signal through conductor 71 is, for example, set to 75 μm.

[0039] The outer diameter of the first signal through conductor 61 can be smaller than the outer diameter of the continuous portion 71b of the second signal through conductor 71. For example, the outer diameter of the first signal through conductor 61 is set to 50 μm. Here, the first signal through conductor 61 is a part of the signal through conductor, corresponding to the portion connected to the first surface 2a side of the insulating substrate 2. The continuous portion 71b of the second signal through conductor 71 is a part of the signal through conductor, corresponding to the portion connected to the second surface 2b side of the insulating substrate 2.

[0040] Instead of having the outer diameter of the connecting portion 71a of the second signal through conductor 71 smaller than the outer diameter of the continuous portion 71b, the following situation may also occur.

[0041] like Figure 4 As shown in the example, the outer diameter of a portion of the first signal through conductor 61, namely the portion 61a connected to the first end of the signal wiring 51, can be smaller than the outer diameter of the portion 61b continuous with the connected portion 61a. The connected portion 61a of the first signal through conductor 61 can be located concentrically with the continuous portion 61b. The length of the connected portion 61a of the first signal through conductor 61 is, for example, set to 0.1 mm or less. The outer diameter of the connected portion 61a of the first signal through conductor 61 is, for example, set to 25 μm or more and 50 μm or less. The outer diameter of the continuous portion 61b of the first signal through conductor 61 is, for example, set to 50 μm.

[0042] In this case, the outer diameter of the continuous portion 61b of the first signal through conductor 61 can be smaller than the outer diameter of the second signal through conductor 71. Here, the continuous portion 61b of the first signal through conductor 61 is part of the signal through conductor and corresponds to the portion connected to the first surface 2a side of the insulating substrate 2. The second signal through conductor 71 is part of the signal through conductor and corresponds to the portion connected to the second surface 2b side of the insulating substrate 2.

[0043] like Figure 5 As illustrated in the example, the outer diameter of the connecting portion 61a of the first signal conductor 61 can be smaller than the outer diameter of the continuous portion 61b, and the outer diameter of the connecting portion 71a of the second signal conductor 71 can be smaller than the outer diameter of the continuous portion 71b. The connecting portion 61a of the first signal conductor 61 can be located concentrically with the continuous portion 61b. The connecting portion 71a of the second signal conductor 71 can be located concentrically with the continuous portion 71b.

[0044] The length of the connecting portion 61a of the first signal through conductor 61 is, for example, set to 0.1 mm or less. The outer diameter of the connecting portion 61a of the first signal through conductor 61 is, for example, set to 25 μm or more and 50 μm or less. The outer diameter of the continuous portion 61b of the first signal through conductor 61 is, for example, set to 50 μm. The length of the connecting portion 71a of the second signal through conductor 71 is, for example, set to 0.1 mm or less. The outer diameter of the connecting portion 71a of the second signal through conductor 71 is, for example, set to 50 μm or more and 75 μm or less. The outer diameter of the continuous portion 71b of the second signal through conductor 71 is, for example, set to 75 μm.

[0045] In this case, the outer diameter of the continuous portion 61b of the first signal through conductor 61 can be smaller than the outer diameter of the continuous portion 71b of the second signal through conductor 71. Here, the continuous portion 61b of the first signal through conductor 61 is part of the signal through conductor, corresponding to the first portion connected to the first surface 2a side of the insulating substrate 2. The continuous portion 71b of the second signal through conductor 71 is part of the signal through conductor, corresponding to the second portion connected to the second surface 2b side of the insulating substrate 2.

[0046] In the wiring substrate 1, the insulating substrate 2 is formed, for example, by a ceramic green sheet lamination method. In this case, the insulating substrate 2 is made of ceramic materials such as alumina sintered body, aluminum nitride sintered body, silicon carbide sintered body, silicon nitride sintered body, mullite sintered body, or glass ceramic. Alternatively, the insulating substrate 2 may be made of organic insulating materials such as polyimide, epoxy resin, fluororesin, polynorbornene, or benzocyclobutene.

[0047] When the insulating substrate 2 is, for example, made of an alumina sintered body, the wiring substrate 1 is manufactured as follows. First, a slurry is prepared by adding and mixing appropriate organic binders or solvents to raw material powders such as alumina, silicon oxide, calcium oxide, or magnesium oxide. The slurry is then formed into a sheet using a scraper method or a rolling mill method to produce a ceramic green sheet for the insulating layer 21. Then, through-holes for the first signal through conductor 61, the second signal through conductor 71, and the ground through conductor 9 are formed on the ceramic green sheet by die-cutting or laser processing. Metal paste, formed by adding and mixing metal powder and appropriate organic binders or solvents, is then filled into these through-holes. In addition, metal paste is printed and applied to the surface of the ceramic green sheet in a pattern corresponding to the electrode pads 3, the external electrode 4, the signal wiring 51, and the ground wiring layer 8. Furthermore, the wiring substrate 1 can be manufactured by firing the metal paste together with the ceramic green sheet.

[0048] When the insulating substrate 2 is made of, for example, epoxy resin, the wiring substrate 1 is manufactured as follows: An insulating layer 21 with through holes is formed using a photosensitive resin; a mask with a predetermined pattern shape is formed on the insulating layer 21; and a metal thin film of a predetermined shape is formed in the through holes and on the surface of the insulating layer 21 by sputtering, vacuum evaporation, or plating. Alternatively, it can be formed by forming a metal thin film on the entire upper surface of the insulating layer 21 without forming a mask, and then forming a mask of a predetermined shape, removing unwanted portions by etching. Alternatively, for example, an electrode pad 3, an external electrode 4, a signal wiring 51, and a ground wiring layer 8 can be formed by processing a copper foil into a predetermined shape and transferring it onto the insulating layer 21. Furthermore, a first signal through conductor 61, a second signal through conductor 71, and a ground through conductor 9 can be formed by filling the through holes with a metal paste formed from metal powder and a binder.

[0049] Reference Figure 6 The electronic device 100 of the first embodiment of the present invention and the electronic module 300 of the first embodiment of the present invention will be described. Figure 6 This is a schematic cross-sectional view of the electronic module 300 according to the first embodiment of the present invention.

[0050] like Figure 6 As shown in the example, the electronic device 100 of the first embodiment of the present invention may have a wiring substrate 1 and an electronic component 200 mounted on the first surface 2a side of an insulating substrate 2 on the wiring substrate 1. The electronic component 200 may be, for example, a semiconductor component such as an integrated circuit (IC) or a large-scale integrated circuit (LSI). The electronic component 200 may also be, for example, an optoelectronic semiconductor component such as a semiconductor laser (LD) or a photodiode (PD). A plurality of electrodes of the electronic device 100 may be electrically connected to corresponding electrode pads 3 via conductive bumps made of solder such as a tin-lead (Sn-Pb) alloy or gold (Au).

[0051] like Figure 6 As shown in the example, the electronic module 300 of the first embodiment of the present invention may include an electronic device 100 and a module substrate 400 on which the electronic device 100 is mounted. A plurality of external electrodes 4 of the wiring substrate 1 may be electrically connected to corresponding electrodes 410 of the module substrate 400 via solder or the like. The electrical connection between the plurality of external electrodes 4 of the wiring substrate 1 and the corresponding electrodes 410 of the module substrate 400 enables signal input / output and power supply to the electronic component 200.

[0052] like Figure 1 and Figure 3As shown in the example, the outer diameter of the connecting portion 71a of the second signal through conductor 71 is smaller than the outer diameter of the continuous portion 71b. Therefore, the electrostatic capacitance between the connecting portion 71a of the second signal through conductor 71 and the ground through conductor 9 can be reduced. Consequently, without expanding the wiring substrate 1 in the Y direction (the direction in which the pair of signal wirings 51 are arranged), reflection loss of high-frequency signals at the connection between the signal wirings 51 and the second signal through conductor 71 can be reduced.

[0053] like Figure 4 As shown in the example, the outer diameter of the connecting portion 61a of the first signal through conductor 61 is smaller than the outer diameter of the continuous portion 61b. Therefore, the electrostatic capacitance between the connecting portion 61a of the first signal through conductor 61 and the grounding through conductor 9 can be reduced. Consequently, without expanding the wiring substrate 1 in the Y direction (the direction in which the pair of signal wirings 51 are arranged), reflection loss of high-frequency signals at the connection between the signal wirings 51 and the first signal through conductor 61 can be reduced.

[0054] Therefore, the wiring substrate 1 according to the first embodiment of the present invention can both achieve miniaturization of the wiring substrate 1 and reduce the reflection loss of high-frequency signals at the connection between the signal wiring 51 and the second signal through conductor 71 or the first signal through conductor 61, thereby improving the transmission performance of high-frequency signals.

[0055] In particular, such as Figure 5 As shown in the example, when the outer diameter of the connecting portion 61a of the first signal conductor 61 is smaller than the outer diameter of the continuous portion 61b, and the outer diameter of the connecting portion 71a of the second signal conductor 71 is smaller than the outer diameter of the continuous portion 71b, the transmission performance of high-frequency signals can be further improved.

[0056] When the outer diameter of the first portion of the signal conductor connected to the first surface 2a side of the insulating substrate 2 is smaller than the outer diameter of the second portion connected to the second surface 2b side of the insulating substrate 2, electronic components 200 can be mounted at a high density on the first surface 2a side of the insulating substrate 2.

[0057] [Second Implementation]

[0058] Reference Figure 7 The wiring substrate 1A of the second embodiment of the present invention will be described. Figure 7 This is a schematic cross-sectional view of the wiring substrate 1A according to the second embodiment of the present invention.

[0059] like Figure 7As shown in the example, except for some structural features, the wiring substrate 1A of the second embodiment of the present invention has the same structure as the wiring substrate 1 of the first embodiment of the present invention. The structures of the wiring substrate 1A that differ from those of the wiring substrate 1 of the first embodiment will be described. For ease of explanation, components having the same function as those described in the first embodiment will be labeled with the same reference numerals.

[0060] The connecting portion 71a of the second signal through conductor 71 can be eccentric relative to the axis of the continuous portion 71b. The eccentricity of the connecting portion 71a of the second signal through conductor 71 can be towards the negative side of the X direction, in other words, towards the center of the insulating substrate 2. The eccentricity of the connecting portion 71a of the second signal through conductor 71 can also be towards the positive side of the X direction or the Y direction. The eccentricity of the connecting portion 71a of the second signal through conductor 71 can be less than or equal to half the outer diameter of the continuous portion 71b of the second signal through conductor 71.

[0061] In the wiring substrate 1A of the second embodiment of the present invention, instead of making the outer diameter of the connecting portion 71a of the second signal through conductor 71 smaller than the outer diameter of the continuous portion 71b, the outer diameter of the connecting portion 61a of the first signal through conductor 61 can be made smaller than the outer diameter of the continuous portion 61b (see reference). Figure 4 The outer diameter of the connecting portion 61a of the first signal conductor 61 can be smaller than the outer diameter of the continuous portion 61b, and the outer diameter of the connecting portion 71a of the second signal conductor 71 can be smaller than the outer diameter of the continuous portion 71b (see reference). Figure 5 In these cases, the connection portion 61a of the first signal through conductor 61 may be eccentric relative to the axis of the continuous portion 61b.

[0062] like Figure 7 As illustrated in the example, when the connection portion 71a of the second signal through conductor 71 is eccentric relative to the axis of the continuous portion 71b, the electrostatic capacitance between the connection portion 71a of the second signal through conductor 71 and the ground through conductor 9 can be further reduced. Alternatively, when the connection portion 61a of the first signal through conductor 61 is eccentric relative to the axis of the continuous portion 61b, the electrostatic capacitance between the connection portion 61a of the first signal through conductor 61 and the ground through conductor 9 can be further reduced. Therefore, the reflection loss of high-frequency signals at the connection between the signal wiring 51 and the second signal through conductor 71 or the first signal through conductor 61 can be sufficiently reduced, further improving the transmission performance of high-frequency signals.

[0063] [Third Implementation Method]

[0064] Reference Figure 8 The wiring substrate 1B of the third embodiment of the present invention will be described. Figure 8 This is a schematic cross-sectional view of the wiring substrate 1B according to the third embodiment of the present invention.

[0065] like Figure 8 As shown in the example, except for some structural features, the wiring substrate 1B of the third embodiment of the present invention has the same structure as the wiring substrate 1 of the first embodiment of the present invention. The structures of the wiring substrate 1B that differ from those of the wiring substrate 1 of the first embodiment will be described. For ease of explanation, components having the same function as those described in the first embodiment will be labeled with the same reference numerals.

[0066] The connecting portion 71a of the second signal conductor 71 can be enlarged in diameter toward the continuous portion 71b in at least two stages. The length of the connecting portion 71a of the second signal conductor 71 is, for example, set to 0.1 mm or less. The maximum outer diameter of the connecting portion 71a of the second signal conductor 71 is, for example, set to 50 μm or more and 75 μm or less. The outer diameter of the continuous portion 71b of the second signal conductor 71 is, for example, set to 75 μm.

[0067] In the wiring substrate 1B of the third embodiment of the present invention, instead of making the outer diameter of the connecting portion 71a of the second signal through conductor 71 smaller than the outer diameter of the continuous portion 71b, the outer diameter of the connecting portion 61a of the first signal through conductor 61 can be made smaller than the outer diameter of the continuous portion 61b (see reference). Figure 4 The outer diameter of the connecting portion 61a of the first signal conductor 61 can be smaller than the outer diameter of the continuous portion 61b, and the outer diameter of the connecting portion 71a of the second signal conductor 71 can be smaller than the outer diameter of the continuous portion 71b (see reference). Figure 5 In these cases, the diameter of the connecting portion 61a of the first signal through conductor 61 can be increased by at least two sizes toward the continuous portion 61b. The length of the connecting portion 61a of the first signal through conductor 61 is, for example, set to 0.1 mm or less. The maximum outer diameter of the connecting portion 61a of the first signal through conductor 61 is, for example, 25 μm or more and 50 μm or less. The outer diameter of the continuous portion 61b of the first signal through conductor 61 is, for example, set to 50 μm.

[0068] like Figure 8As illustrated, when the diameter of the connection portion 71a of the second signal through conductor 71 is increased by at least two stages towards the continuous portion 71b, the variation in specific impedance at the connection between the signal wiring 51 and the second signal through conductor 71 can be mitigated. Alternatively, when the diameter of the connection portion 61a of the first signal through conductor 61 is increased by at least two stages towards the continuous portion 61b, the variation in specific impedance at the connection between the signal wiring 51 and the first signal through conductor 61 can be mitigated. Therefore, reflection loss of high-frequency signals at the connection between the signal wiring 51 and the second signal through conductor 71 or the first signal through conductor 61 can be significantly reduced, further improving the transmission performance of high-frequency signals.

[0069] [Fourth Implementation Method]

[0070] Reference Figure 9 The wiring substrate 1C of the fourth embodiment of the present invention will be described. Figure 9 This is a schematic cross-sectional view of the wiring substrate 1C according to the fourth embodiment of the present invention.

[0071] like Figure 9 As shown in the example, except for some structural features, the wiring substrate 1C of the fourth embodiment of the present invention has the same structure as the wiring substrate 1B of the third embodiment of the present invention. The structures of the wiring substrate 1C that differ from those of the wiring substrate 1 of the first embodiment B will be described. For ease of explanation, components having the same function as those described in the third embodiment will be labeled with the same reference numerals.

[0072] The connecting portion 71a of the second signal through conductor 71 can be eccentric relative to the axis of the continuous portion 71b. The eccentricity of the connecting portion 71a of the second signal through conductor 71 can be towards the negative side of the X direction, in other words, towards the center of the insulating substrate 2. The eccentricity of the connecting portion 71a of the second signal through conductor 71 can also be towards the positive side of the X direction or the Y direction. The maximum eccentricity of the connecting portion 71a of the second signal through conductor 71 can be less than or equal to half the outer diameter of the continuous portion 71b of the second signal through conductor 71.

[0073] In the wiring substrate 1C of the fourth embodiment of the present invention, instead of making the outer diameter of the connecting portion 71a of the second signal through conductor 71 smaller than the outer diameter of the continuous portion 71b, the outer diameter of the connecting portion 61a of the first signal through conductor 61 can be made smaller than the outer diameter of the continuous portion 61b (see reference). Figure 4The outer diameter of the connecting portion 61a of the first signal conductor 61 can be smaller than the outer diameter of the continuous portion 61b, and the outer diameter of the connecting portion 71a of the second signal conductor 71 can be smaller than the outer diameter of the continuous portion 71b (see reference). Figure 5 ).

[0074] like Figure 9 As illustrated in the example, when the connection portion 71a of the second signal through conductor 71 is axially eccentric relative to the continuous portion 71b, the electrostatic capacitance between the connection portion 71a of the second signal through conductor 71 and the ground through conductor 9 can be further reduced. Alternatively, when the connection portion 61a of the first signal through conductor 61 is axially eccentric relative to the continuous portion 61b, the electrostatic capacitance between the connection portion 61a of the first signal through conductor 61 and the ground through conductor 9 can be further reduced. Therefore, the reflection loss of high-frequency signals at the connection between the signal wiring 51 and the second signal through conductor 71 or the first signal through conductor 61 can be reduced more sufficiently, and the transmission performance of high-frequency signals can be further improved.

[0075] [Fifth Implementation Method]

[0076] Reference Figure 10 The wiring substrate 1D of the fifth embodiment of the present invention will be described. Figure 10 This is a schematic cross-sectional view of the wiring substrate 1D according to the fifth embodiment of the present invention.

[0077] like Figure 10 As shown in the example, except for some structural features, the wiring substrate 1D of the fifth embodiment of the present invention has the same structure as the wiring substrate 1 of the first embodiment of the present invention. The structures of the wiring substrate 1D that differ from those of the wiring substrate 1 of the first embodiment will be described. For ease of explanation, components having the same function as those described in the first embodiment will be labeled with the same reference numerals.

[0078] The connecting portion 71a of the second signal through conductor 71 may taper towards the continuous portion 71b. The shape of the connecting portion 71a of the second signal through conductor 71 is tapered, but not strictly tapered. Even if there is a step caused by the stacking offset of the insulating layer 21 in the connecting portion 71a of the second signal through conductor 71, it is acceptable as long as the connecting portion 71a of the second signal through conductor 71 is visually identifiable as being tapered overall. The length of the connecting portion 71a of the second signal through conductor 71 is, for example, set to 0.1 mm or less. The maximum outer diameter of the connecting portion 71a of the second signal through conductor 71 is, for example, set to 50 μm or more and 75 μm or less. The outer diameter of the continuous portion 71b of the second signal through conductor 71 is, for example, set to 75 μm.

[0079] In the wiring substrate 1D of the fifth embodiment of the present invention, instead of making the outer diameter of the connecting portion 71a of the second signal through conductor 71 smaller than the outer diameter of the continuous portion 71b, the outer diameter of the connecting portion 61a of the first signal through conductor 61 can be made smaller than the outer diameter of the continuous portion 61b (see reference). Figure 4 The outer diameter of the connecting portion 61a of the first signal conductor 61 can be smaller than the outer diameter of the continuous portion 61b, and the outer diameter of the connecting portion 71a of the second signal conductor 71 can be smaller than the outer diameter of the continuous portion 71b (see reference). Figure 5 In these cases, the connecting portion 61a of the first signal through conductor 61 may taper towards the continuous portion 61b. The length of the connecting portion 61a of the first signal through conductor 61 is, for example, set to 0.1 mm or less. The maximum outer diameter of the connecting portion 61a of the first signal through conductor 61 is, for example, set to 25 μm or more and 50 μm or less. The outer diameter of the continuous portion 61b of the first signal through conductor 61 is, for example, set to 50 μm.

[0080] like Figure 10 As illustrated in the example, when the connection portion 71a of the second signal conductor 71 tapers towards the continuous portion 71b, the variation in impedance at the connection between the signal wiring 51 and the second signal conductor 71 can be mitigated. Alternatively, when the connection portion 61a of the first signal conductor 61 tapers towards the continuous portion 61b, the variation in impedance at the connection between the signal wiring 51 and the first signal conductor 61 can be mitigated. Therefore, reflection loss of high-frequency signals at the connection between the signal wiring 51 and the second signal conductor 71 or the first signal conductor 61 can be significantly reduced, and the transmission performance of high-frequency signals can be further improved.

[0081] In one embodiment, (1) the wiring substrate comprises: an insulating substrate, formed by stacking a plurality of insulating layers, having a first surface and a second surface opposite to the first surface; differential wiring having a pair of signal wirings arranged between adjacent insulating layers in the stacking direction or on the first surface; a differential through conductor having a pair of signal through conductors arranged to penetrate at least one of the insulating layers, the signal through conductors being electrically connected to the signal wirings; a ground wiring layer located between adjacent insulating layers in the stacking direction and having an opening for the differential through conductors to pass through; and a ground through conductor penetrating at least one of the insulating layers, electrically connecting each of the ground wiring layers facing each other in the stacking direction, wherein the outer diameter of a portion of the signal through conductor, i.e., the portion connected to the first end and / or the second end of the signal wirings, is smaller than the outer diameter of the portion continuous with the connected portion.

[0082] (2) In the wiring substrate of (1), the differential wiring is located between adjacent insulating layers in the stacking direction. The outer diameter of a portion of the signal through conductor, i.e., the first portion connected to the first end of the signal wiring, may be smaller than the outer diameter of the portion continuous with the first portion. The outer diameter of a portion of the signal through conductor, i.e., the second portion connected to the second end of the signal wiring, may be smaller than the outer diameter of the portion continuous with the second portion.

[0083] (3) In the wiring substrate of (1) or (2), the differential wiring is located between adjacent insulating layers in the stacking direction, and the outer diameter of a portion of the signal through conductor, i.e. the portion connected to the first side, may be smaller than the outer diameter of a portion of the signal through conductor, i.e. the portion connected to the second side.

[0084] (4) In any one of the wiring substrates in (1) to (3), the connection portion of the signal through conductor may be eccentric relative to the axis of the continuous portion.

[0085] (5) In any one of the wiring substrates (1) to (4), the connection portion of the signal through conductor can be expanded in diameter toward the continuous portion in at least two stages.

[0086] (6) In any one of the wiring substrates (1) to (4), the connection portion of the signal through conductor may be tapered toward the continuous portion.

[0087] (7) An electronic device having a wiring substrate as described in any one of (1) to (6) and an electronic component mounted on a first side of the wiring substrate.

[0088] (8) An electronic module having the electronic device of (7) and a module substrate on which the electronic device is mounted.

[0089]

Example

[0090] Reference Figures 11 to 13 The embodiments of the present invention are described below. Figure 11 XIA is a diagram illustrating a simulation model of an embodiment. Figure 11 The XIB is a diagram illustrating the simulation model of the comparative example. Figure 12 XIIA is a graph showing the relationship between the signal frequency and the signal reflection loss in the case of the embodiment. Figure 12 XIIB is a graph representing the simulation results of signal transmission in the comparative case, i.e., the relationship between the signal frequency and the signal reflection loss. Figure 13 XIIIA is a graph showing the simulation results of signal transmission under the embodiment, i.e., the relationship between time and characteristic impedance. Figure 13 XIIB is a graph showing the simulation results of signal transmission in the comparative case, i.e., the relationship between time and characteristic impedance.

[0091] like Figure 11 As shown in the example of XIA, the simulation model of the embodiment is the wiring substrate 1 of the first embodiment (refer to...). Figure 1 The model is a part of the model. In the simulation model of the embodiment, the width of the signal wiring 51 is set to 51 μm, the outer diameter of the connecting portion 71a of the second signal through conductor 71 is set to 50 μm, and the outer diameter of the continuous portion 71b of the second signal through conductor 71 is set to 75 μm. Figure 11 In XIA, each component in the simulation model of the embodiment is given the same reference numerals as the corresponding components of the wiring substrate 1 in the first embodiment.

[0092] like Figure 11 As shown in the XIB example, the only difference between the comparative example's simulation model and the embodiment's simulation model is that the outer diameter of the second signal conductor 71 is set to be constant. In the comparative example's simulation model, the outer diameter of the second signal conductor 71 is set to 75 μm. Figure 11 In the XIB, each component in the simulation model of the comparative example is given the same reference numerals as the corresponding components in the wiring board 1 of the first embodiment.

[0093] As an example, the simulation results of signal transmission, if we summarize the relationship between the signal frequency and the signal reflection loss, then... Figure 12As shown in XIIA. The simulation results of signal transmission in the comparative case, if we summarize the relationship between the signal frequency and the signal reflection loss, are as follows: Figure 12 As shown in XIIB. That is, as Figure 12 As shown in XIIA and XIIB, if the frequency of the signal exceeds 50 GHz, the signal reflection loss exceeds -15 dB in the comparative example, while in the embodiment, the signal reflection loss can be reduced to below -15 dB.

[0094] As an example, the simulation results of signal transmission, if we summarize the relationship between time and characteristic impedance, are as follows: Figure 13 As shown in XIIIA. The simulation results of signal transmission in the comparative case, if we summarize the relationship between time and characteristic impedance, are as follows: Figure 13 As shown in XIIIB. That is, as Figure 13 As shown in XIIIIA and XIIIB, it can be seen that if the impedance exceeds 160 psec, the characteristic impedance decreases significantly in the comparative example, while in the embodiment, the characteristic impedance decreases slowly.

[0095] The invention disclosed above has been described with reference to the accompanying drawings and embodiments. However, the invention disclosed herein is not limited to the embodiments described above. That is, various modifications can be made to the invention disclosed herein, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the invention disclosed herein. In other words, it should be noted that those skilled in the art can easily make various modifications or alterations to the invention. It should also be noted that the scope of the invention includes these modifications or alterations.

[0096] Explanation of reference numerals in the attached figures

[0097] 1. Wiring substrate (wiring substrate of the first embodiment)

[0098] 2 Insulating substrates

[0099] 21 insulation layers

[0100] 3-electrode pads (electrodes)

[0101] 4 External Electrodes

[0102] 5. Differential wiring

[0103] 51 signal wiring

[0104] 6. First differential through conductor (differential through conductor)

[0105] 61 First signal-through conductor (signal-through conductor)

[0106] 61a connection part

[0107] 61b continuous parts

[0108] 7. Second differential through conductor (differential through conductor)

[0109] 71 Second signal through conductor (signal through conductor)

[0110] 71a connection part

[0111] 71b continuous parts

[0112] 8 Grounding wiring layer

[0113] 81 opening

[0114] 9 Grounding Through Conductor

[0115] 100 electronic devices

[0116] 200 electronic components

[0117] 300 Electronic Module

[0118] 400 module baseboard

[0119] 410 electrode

[0120] 1A Wiring Substrate (Wiring Substrate of the Second Embodiment)

[0121] 1B Wiring Substrate (Wiring Substrate of the Third Embodiment)

[0122] 1C Wiring Board (Wiring Board of the Fourth Embodiment)

[0123] 1D wiring substrate (wiring substrate of the fifth embodiment)

Claims

1. A wiring substrate, wherein, have: An insulating substrate is formed by stacking multiple insulating layers and has a first surface and a second surface opposite to the first surface; Differential wiring has a pair of signal wirings arranged between adjacent insulating layers or on the first surface in the stacking direction; A differential through conductor having a pair of signal through conductors arranged to penetrate at least one of the insulating layers, the signal through conductors being electrically connected to the signal wiring; A grounding wiring layer is located between a plurality of adjacent insulating layers in the stacking direction and has an opening for the differential through conductor to pass through. as well as A grounding conductor, penetrating at least one of the insulating layers, electrically connects the grounding wiring layers facing each other in the stacking direction. The outer diameter of a portion of the signal conductor, i.e. the portion connected to the first end and / or the second end of the signal wiring, is smaller than the outer diameter of the portion continuous with the connected portion.

2. The wiring substrate according to claim 1, wherein, The differential wiring is located between adjacent insulating layers in the stacking direction. The outer diameter of a portion of the signal conductor, namely the first portion connected to the first end of the signal wiring, is smaller than the outer diameter of the portion continuous with the first portion. The outer diameter of a portion of the signal conductor, namely the second portion connected to the second end of the signal wiring, is smaller than the outer diameter of the portion continuous with the second portion.

3. The wiring substrate according to claim 1 or 2, wherein, The differential wiring is located between adjacent insulating layers in the stacking direction. The outer diameter of a portion of the signal-passing conductor, i.e. the part connected to the first side, is smaller than the outer diameter of a portion of the signal-passing conductor, i.e. the part connected to the second side.

4. The wiring substrate according to any one of claims 1 to 3, wherein, The connection portion of the signal-conducting conductor is eccentric relative to the axis of the continuous portion.

5. The wiring substrate according to any one of claims 1 to 4, wherein, The connecting portion of the signal-conducting conductor is expanded toward the continuous portion in at least two stages.

6. The wiring substrate according to any one of claims 1 to 4, wherein, The connecting portion of the signal-conducting conductor is tapered towards the continuous portion.

7. An electronic device, wherein, have: Wiring substrate according to any one of claims 1 to 6; and Electronic components mounted on the first side of the wiring substrate.

8. An electronic module, wherein, have: The electronic device according to claim 7; and A substrate for a module that carries the electronic device.

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