Wiring board and mounting structure

Abstract

A wiring board according to this disclosure includes a layered structure in which a plurality of insulating layers and a plurality of conductive layers are alternately layered. The plurality of conductive layers include a first signal wiring. The first signal wiring includes: first and second electrodes; a projecting section; a linear conductor having first and second ends; a third electrode; and first, second, and third via hole conductors. The first and third electrodes are connected to each other by a first wiring pattern including the first via hole conductor. The projecting section and the first end of the linear conductor are connected to each other by the second via hole conductor. The second end of the linear conductor and the second electrode are connected to each other by the third via hole conductor.

Description

Wiring board and mounting structure

[0001] The present invention relates to a wiring board and a mounting structure using the same.

[0002] In wiring boards on which electronic components such as semiconductor devices are mounted, it is necessary to inspect whether signals are transmitted as designed. Such inspections are performed using measurement pads formed on the edges of the wiring board, as described in, for example, Patent Document 1.

[0003] Patent No. 5361023

[0004] The wiring board according to the present disclosure has a laminated structure in which multiple insulating layers and multiple conductor layers are alternately stacked. The multiple insulating layers include at least a first insulating layer located at the bottom, a second insulating layer located one layer above the first insulating layer, and a third insulating layer located at the top and having a mounting area. The multiple conductor layers include a first signal wiring. The first signal wiring includes a first electrode and a second electrode located on the bottom surface of the first insulating layer, a protruding portion located on the bottom surface of the first insulating layer so as to contact the first electrode, a linear conductor located between the first and second insulating layers and having first and second ends, a third electrode located on the top surface of the third insulating layer, and first, second, and third via-hole conductors located so as to penetrate the top and bottom surfaces of the first insulating layer. The first electrode and the third electrode are connected by a first wiring pattern including the first via-hole conductor. The protruding portion and a first end of the linear conductor are connected by a second via-hole conductor. The second end of the linear conductor and the second electrode are connected by a third via-hole conductor.

[0005] A mounting structure according to the present disclosure includes the above-described wiring board and an electronic component located in a mounting area of ​​the wiring board.

[0006] Fig. 2 is an explanatory diagram for explaining a main part of a wiring board according to an embodiment of the present disclosure. Fig. 3 is a plan view showing an example when viewed from the arrow A shown in Fig. 1. Fig. 4 is a plan view showing another example when viewed from the arrow A shown in Fig. 1. Fig. 5 is an explanatory diagram for explaining the shortest distance between a first electrode and a grounding conductor, the shortest distance between a protruding portion and a grounding conductor, and the shortest distance between protruding portions of a pair of electrodes.

[0007] In conventional wiring boards, measurement pads are formed at the edge of the wiring board, and the pattern of the measurement wiring path is significantly different from the actual product pattern. Furthermore, while it is desirable to measure the electrical characteristics of signal pads surrounded by ground conductors, conventional testing results in portions of the signal pads that are not surrounded by the ground conductor layer. When portions of the signal pads are not surrounded by the ground conductor, the electrical characteristics deteriorate. Therefore, there is a need for a wiring board in which the pattern of the measurement wiring path closely resembles the actual product pattern, enabling accurate measurement of electrical characteristics.

[0008] The wiring board according to the present disclosure has a configuration as described in the section on means for solving the problems, so that the pattern of the measurement wiring path is close to the actual product pattern, allowing accurate measurement of electrical characteristics. Furthermore, the mounting structure according to the present disclosure has electronic components mounted on a wiring board whose electrical characteristics have been accurately measured. Therefore, the mounting structure according to the present disclosure has excellent electrical reliability and can reduce defects such as malfunctions of electronic components.

[0009] A wiring board according to an embodiment of the present disclosure will be described with reference to Figures 1 to 4. Figure 1 is an explanatory diagram for explaining a main part of a wiring board 10 according to an embodiment of the present disclosure. Specifically, Figure 1 shows the vicinity of an area connected to a measuring device to perform an inspection (electrical characteristic measurement) to determine whether a signal is transmitted as designed.

[0010] 1, a wiring board 10 according to one embodiment has a laminated structure in which a plurality of insulating layers 1 and a plurality of conductor layers 2 are alternately laminated. As shown in Fig. 1, the insulating layer 1 includes, for example, a core insulating layer 11 and a build-up insulating layer laminated on at least one main surface of the core insulating layer 11. The wiring board 10 according to one embodiment is connected to a motherboard 20 via solder 6, for example, as shown in Fig. 1.

[0011] The insulating layer 1 is formed of a resin such as an epoxy resin, a bismaleimide-triazine resin, a polyimide resin, a polyphenylene ether resin, or a liquid crystal polymer. These resins may be used alone or in combination of two or more. The insulating layer 1 may have insulating particles dispersed therein. The insulating particles are not limited, and examples thereof include inorganic insulating fillers such as silica, alumina, barium sulfate, talc, clay, glass, calcium carbonate, and titanium oxide. The core insulating layer 11 and the build-up insulating layer may be formed of the same resin or different resins. Furthermore, each layer constituting the build-up insulating layer may be formed of the same resin or different resins.

[0012] The insulating layer 1 may contain a reinforcing material. Examples of the reinforcing material include insulating fabric materials such as glass fiber, glass nonwoven fabric, aramid nonwoven fabric, aramid fiber, and polyester fiber. Two or more types of reinforcing materials may be used in combination. Furthermore, the insulating layer 1 may contain dispersed therein an inorganic insulating filler such as silica, barium sulfate, talc, clay, glass, calcium carbonate, or titanium oxide.

[0013] When the insulating layer 1 is a core insulating layer 11, the core insulating layer 11 has a thickness of, for example, 200 μm or more and 1400 μm or less. The core insulating layer 11 has through-hole conductors for electrically connecting the conductor layers 2 located on the upper and lower surfaces of the core insulating layer 11. The through-hole conductors are located in through-holes that penetrate the upper and lower surfaces of the core insulating layer 11. The through-hole conductors are formed of a conductor made of metal plating, such as copper plating. The through-hole conductors are connected to the conductor layers 2 on both surfaces of the core insulating layer 11. The through-hole conductors may be formed only on the inner wall surfaces of the through-holes, or may fill the through-holes.

[0014] When the insulating layer 1 is a build-up insulating layer, the build-up insulating layer has a thickness of, for example, 5 μm or more and 100 μm or less. The layers constituting the build-up insulating layer may be formed of the same resin, or may be formed of different resins. The build-up insulating layer has via-hole conductors for electrically connecting the conductor layers 2 located above and below the build-up insulating layer via the build-up insulating layer. The via-hole conductors are obtained by depositing, for example, copper plating in via holes that penetrate the top and bottom surfaces of the build-up insulating layer. The via-hole conductors may be positioned so as to fill the via holes as shown in FIG. 1 , or the via-hole conductors may be attached to the inner surfaces of the via holes, with resin filling the areas where there are no via-hole conductors.

[0015] The conductor layer 2 is located on the main surface of the insulating layer 1, i.e., the main surface of the core insulating layer 11 and the main surface of the build-up insulating layer. The conductor layer 2 is made of copper, such as copper foil or copper plating. The thickness of the conductor layer 2 is not particularly limited and is, for example, 3 μm or more and 30 μm or less.

[0016] Solder resist 5 is located on a portion of the top and bottom surfaces of wiring board 10. Solder resist 5 is formed of, for example, acrylic-modified epoxy resin. Solder resist 5 has a function of protecting conductor layer 2 from adhesion of solder 6 when mounting electronic components, for example. Solder resist 5 has openings. The conductor layer 2 exposed through these openings functions as an electrode.

[0017] In the wiring board 10 according to one embodiment, the insulating layer 1 includes at least a first insulating layer 1a located at the bottom, a second insulating layer 1b located one layer above the first insulating layer 1a, and a third insulating layer 1c located at the top and having a mounting area. Specifically, as shown in FIG. 1 , of the build-up insulating layers stacked on the underside of the core insulating layer 11, the outermost build-up insulating layer corresponds to the first insulating layer 1a. The build-up insulating layer located one layer inside the first insulating layer 1a (toward the core insulating layer 11) corresponds to the second insulating layer 1b. Furthermore, of the build-up insulating layers stacked on the top surface of the core insulating layer 11, the outermost build-up insulating layer corresponds to the third insulating layer 1c.

[0018] In the wiring board 10 according to one embodiment, the conductor layer 2 includes a first signal wiring 21 for electrical measurement. The first signal wiring 21 includes a first electrode 31, a second electrode 32, a third electrode 33, a protruding portion 3a, a linear conductor 3b, a first via-hole conductor 41, a second via-hole conductor 42, and a third via-hole conductor 43. In other words, the first signal wiring 21 is a continuous wiring path from the second electrode 32 to the third electrode 33 shown in FIG. 1 .

[0019] The first electrode 31 and the second electrode 32 are located on the lower surface of the first insulating layer 1a and are exposed through openings in the solder resist 5. The first electrode 31 and the second electrode 32 are connected via a linear conductor 3b as shown in FIG.

[0020] The linear conductor 3b is located between the first insulating layer 1a and the second insulating layer 1b. The linear conductor 3b and the first electrode 31 are connected via a protruding portion 3a located in contact with the first electrode 31 and a second via-hole conductor 42. The second via-hole conductor 42 is connected near a first end 3b1 of the linear conductor 3b. The linear conductor 3b and the second electrode 32 are connected via a third via-hole conductor 43. The third via-hole conductor 43 is connected near a second end 3b2 of the linear conductor 3b. The first electrode 31 and the third electrode 33 located on the upper surface of the third insulating layer 1c are connected by a first wiring pattern P1 including the first via-hole conductor 41. In other words, the first wiring pattern P1 refers to a series of wiring paths from the first via-hole conductor 41 shown in FIG. 1 to the via-hole conductor connected to the third electrode 33.

[0021] As shown in Fig. 2, the conductor layer 2 may further include a grounding conductor 23. Fig. 2 is a plan view showing an example as viewed from the arrow A shown in Fig. 1. Fig. 2(A) shows the bottommost conductor layer 2, and Fig. 2(B) shows the layer one layer inward from the bottommost conductor layer 2 (the core insulating layer 11 side), showing the vicinity of the first electrode 31 and the second electrode 32.

[0022] The ground conductors 23 are located, for example, on the underside of the first insulating layer 1a and between the first insulating layer 1a and the second insulating layer 1b. As shown in Figures 2(A) and 2(B), the ground conductors 23 are located so as to surround both sides of the linear conductor 3b and the first electrode 31 in a plan view. "The ground conductors 23 located on both sides of the linear conductor 3b" refers to, for example, the ground conductors 23 located on the left and right sides along the longitudinal direction of the linear conductor 3b in Figure 2(B). In this way, when the ground conductors 23 are located so as to surround both sides of the linear conductor 3b and the first electrode 31, electrical characteristics can be measured more accurately.

[0023] The first electrode 31 may be a single electrode as shown in Fig. 2, or may be a pair of electrodes having two electrodes positioned adjacent to each other, with the protruding portion 3a in contact with each of the two electrodes as shown in Fig. 3. Fig. 3 is a plan view showing another example as seen from the arrow A shown in Fig. 1. Fig. 3(A) shows the bottommost conductor layer 2, and Fig. 3(B) shows the layer one layer inward from the bottommost conductor layer 2 (the core insulating layer 11 side), showing the vicinity of the first electrode 31 and the second electrode 32.

[0024] When the first electrode 31 is a pair of electrodes, it becomes possible to efficiently transmit a high frequency signal using a differential signal line.

[0025] The position of the protruding portion 3a in contact with the first electrode 31 is not limited. For example, as shown in Fig. 4, the protruding portion 3a may be in contact with the first electrode 31 so that a first distance L1, which is the shortest distance between the grounding conductor 23 and the first electrode 31, is shorter than a second distance L2, which is the shortest distance between the grounding conductor 23 and the protruding portion 3a. If the protruding portion 3a is in contact with the first electrode 31 so that the first distance L1 is shorter than the second distance L2, the electrical characteristics can be measured more accurately.

[0026] Furthermore, the first electrode 31 and the protruding portion 3a are in contact with each other, and can be viewed as a single electrode (pad). The first electrode 31 is connected to the first via-hole conductor 41, and the protruding portion 3a is connected to the second via-hole conductor 42. Therefore, two via-hole conductors are connected to what appears to be a single electrode (pad), which can improve the adhesion of the first electrode 31 and the protruding portion 3a to the first insulating layer 1a.

[0027] The shape of the protruding portion 3a is not limited. As shown in FIGS. 3 and 4, the shape of the protruding portion 3a may be circular. A circular shape enables more accurate measurement when measuring using the de-embedding technique described below. When the first electrode 31 and the protruding portion 3a are viewed as a single electrode (pad), the electrode may have a teardrop shape. The teardrop shape makes it easier to form the electrode and reduces peeling of the protruding portion 3a. For the same reason, the shape of the protruding portion 3a may be rectangular.

[0028] Making the protruding portion 3a as small as possible in manufacturing enables accurate measurement. Therefore, the protruding portion 3a only needs to have the minimum size necessary to connect the second via-hole conductor 42 (connected to the protruding portion 3a), and the maximum width may be, for example, about 100 μm. In other words, in plan view, the protruding portion 3a has a portion with a width greater than the maximum width of the second via-hole conductor 42.

[0029] 3, when the first electrode 31 is a paired electrode, the protruding portion 3 a may be in contact with the first electrode 31 so that the first distance L1 is shorter than the third distance L3, which is the shortest distance between the protruding portions 3 a of the paired electrode. When the protruding portion 3 a is in contact with the first electrode 31 so that the first distance L1 is shorter than the third distance L3, the electrical characteristics can be measured more accurately.

[0030] The first signal wiring 21 is a circuit used to measure electrical characteristics, and therefore is not connected to the electronic component or the motherboard 20. After the electronic component is mounted, signals are transmitted and received between the electronic component and the motherboard 20 via the second wiring pattern P2.

[0031] The second wiring pattern P2 connects the fourth electrode 34 located on the lower surface of the first insulating layer 1a and the fifth electrode 35 located on the upper surface of the third insulating layer 1c. In other words, the second wiring pattern P2 is a series of wiring paths from the via-hole conductors connected to the fourth electrode 34 to the via-hole conductors connected to the fifth electrode 35. The second wiring pattern P2 is the same wiring path pattern as the first wiring pattern P1 connecting the first electrode 31 and the third electrode 33. In other words, the first wiring pattern P1 and the second wiring pattern P2 have the same configuration with respect to wiring length, wiring width, size, number and arrangement of the via-hole conductors, etc.

[0032] The first wiring pattern P1, which is a pattern for electrical measurement, has the same wiring path pattern as the second wiring pattern P2, which is an actual product pattern, and thus electrical characteristics can be measured more accurately than with conventional wiring boards. The method for measuring the electrical characteristics is not limited, and for example, measurements may be made using a de-embedding technique, which allows for more accurate measurement of electrical characteristics.

[0033] The de-embedding technique first measures the electrical characteristics of the first signal wiring 21 (from the second electrode 32 to the third electrode 33) to obtain a measured value M1. Next, the electrical characteristics of the portion from the protruding portion 3 a to the second electrode 32 are measured to obtain a measured value M2. Then, the measured value M2 is subtracted from the measured value M1 to obtain the electrical characteristic value between the first electrode 31 and the third electrode 33. In the wiring board 10 disclosed herein, the first wiring pattern P1 connecting the first electrode 31 and the third electrode 33 has the same wiring path pattern as the second wiring pattern P2 connecting the fourth electrode 34 connected to the motherboard 20 and the fifth electrode 35 connected to the electronic component. This allows the electrical characteristic value between the first electrode 31 and the third electrode 33 to be used as an electrical characteristic value closer to the electrical characteristic value between the third electrode 33 and the fifth electrode 35. Therefore, a wiring board 10 capable of measuring accurate electrical characteristics can be provided.

[0034] Next, a mounting structure according to the present disclosure will be described. The mounting structure according to one embodiment includes the wiring board 10 according to the above embodiment and an electronic component located in a mounting area of ​​the wiring board 10.

[0035] Examples of the electronic component include semiconductor elements such as an ASIC (Application Specific Integrated Circuit), a semiconductor integrated circuit element, and an optoelectronic element. The electronic component is connected to the fifth electrode 35 by the solder 6. That is, as described above, the electronic component is not electrically connected to the first wiring pattern P1, but is electrically connected to the second wiring pattern P2.

[0036] In the mounting structure according to one embodiment, electronic components are mounted on the wiring substrate 10 whose electrical characteristics have been accurately measured. Therefore, the mounting structure according to one embodiment has excellent electrical reliability and can reduce defects such as malfunctions of electronic components.

[0037] Although the embodiments of the present disclosure have been described above, the invention according to the present disclosure is not limited to the above-described embodiments, and various modifications and improvements are possible within the scope of the present disclosure as shown in (1) and (7) below.

[0038] (1) A wiring board according to the present disclosure has a laminated structure in which multiple insulating layers and multiple conductor layers are alternately stacked. The multiple insulating layers include at least a first insulating layer located at the bottom, a second insulating layer located one layer above the first insulating layer, and a third insulating layer located at the top and having a mounting area. The multiple conductor layers include a first signal wiring. The first signal wiring includes a first electrode and a second electrode located on the bottom surface of the first insulating layer, a protruding portion located on the bottom surface of the first insulating layer so as to contact the first electrode, a linear conductor located between the first insulating layer and the second insulating layer and having first and second ends, a third electrode located on the top surface of the third insulating layer, and first, second, and third via-hole conductors located so as to penetrate the top and bottom surfaces of the first insulating layer. The first electrode and the third electrode are connected by a first wiring pattern including the first via-hole conductor. The protruding portion and a first end of the linear conductor are connected by a second via-hole conductor. The second end of the linear conductor and the second electrode are connected by a third via-hole conductor.

[0039] Regarding the embodiments of the present disclosure, the following embodiments (2) to (6) and (8) are further disclosed.

[0040] (2) In the wiring board described in (1) above, the conductor layer further includes a fourth electrode located on the lower surface of the first insulating layer and a fifth electrode located on the upper surface of the third insulating layer. The fourth electrode and the fifth electrode are connected by a second wiring pattern having the same wiring path pattern as the first wiring pattern. (3) In the wiring board described in (1) or (2) above, the first electrode is a pair of electrodes having two electrodes located adjacent to each other, and the protruding portion contacts each of the two electrodes. (4) In the wiring board described in any of (1) to (3) above, the conductor layer further includes a ground conductor on the lower surface of the first insulating layer and between the first insulating layer and the second insulating layer. The ground conductor is located on both sides of the linear conductor and surrounding the first electrode in a plan view. (5) In the wiring board described in (4) above, the first distance, which is the shortest distance between the first electrode and the ground conductor, is shorter than the second distance, which is the shortest distance between the protruding portion and the ground conductor. (6) In the wiring board described in (4) or (5) above, the first electrode is a pair electrode having two electrodes positioned adjacent to each other, a protruding portion contacts each of the two electrodes, and the first distance, which is the shortest distance between the first electrode and the grounding conductor, is shorter than the third distance, which is the shortest distance between the protruding portions of the pair electrodes.

[0041] (7) A mounting structure according to the present disclosure includes the wiring board according to any one of (1) to (6) above, and an electronic component located in a mounting area of ​​the wiring board.

[0042] (8) In the mounting structure of (7) above, the electronic component is not electrically connected to the first wiring pattern but is electrically connected to the second wiring pattern.

[0043] REFERENCE SIGNS LIST 1 Insulating layer 11 Core insulating layer 1a First insulating layer 1b Second insulating layer 1c Third insulating layer 2 Conductor layer 21 First signal wiring 22 Second signal wiring 23 Grounding conductor 31 First electrode 32 Second electrode 33 Third electrode 34 Fourth electrode 35 Fifth electrode 3a Projecting portion 3b Linear conductor 3b1 First end 3b2 Second end 41 First via hole conductor 42 Second via hole conductor 43 Third via hole conductor 5 Solder resist 6 Solder 10 Wiring substrate 20 Motherboard P1 First wiring pattern P2 Second wiring pattern

Claims

1. A laminated structure in which a plurality of insulating layers and a plurality of conductor layers are alternately laminated, The plurality of insulating layers include at least a first insulating layer located at the bottom, a second insulating layer located one layer above the first insulating layer, and a third insulating layer located at the top and having a mounting area; The plurality of conductor layers include a first signal wiring, The first signal wiring is a first electrode and a second electrode located on a lower surface of the first insulating layer; a protruding portion located on a lower surface of the first insulating layer and in contact with the first electrode; a linear conductor located between the first insulating layer and the second insulating layer and having a first end and a second end; a third electrode located on an upper surface of the third insulating layer; a first via-hole conductor, a second via-hole conductor and a third via-hole conductor positioned to penetrate through upper and lower surfaces of the first insulating layer; the first electrode and the third electrode are connected by a first wiring pattern including the first via hole conductor; the protruding portion and the first end of the linear conductor are connected by the second via-hole conductor; the second end of the linear conductor and the second electrode are connected by the third via-hole conductor; Wiring board.

2. the conductor layer further includes a fourth electrode located on a lower surface of the first insulating layer and a fifth electrode located on an upper surface of the third insulating layer; The wiring board according to claim 1 , wherein the fourth electrode and the fifth electrode are connected by a second wiring pattern having the same wiring path pattern as the first wiring pattern.

3. The wiring board according to claim 1 , wherein the first electrode is a pair of electrodes having two electrodes positioned adjacent to each other, and the protruding portion is in contact with each of the two electrodes.

4. The conductor layer further includes a ground conductor on a lower surface of the first insulating layer and between the first insulating layer and the second insulating layer; The wiring board according to claim 1 , wherein the ground conductor is positioned on both sides of the linear conductor and surrounding the first electrode in a plan view.

5. 5. The wiring board according to claim 4, wherein a first distance, which is the shortest distance between the first electrode and the ground conductor, is shorter than a second distance, which is the shortest distance between the protruding portion and the ground conductor.

6. The first electrode is a pair of electrodes having two electrodes positioned adjacent to each other, and the protruding portion is in contact with each of the two electrodes; 5. The wiring board according to claim 4, wherein a first distance that is the shortest distance between the first electrode and the ground conductor is shorter than a third distance that is the shortest distance between the protruding portions of the pair of electrodes.

7. 7. A mounting structure comprising: the wiring board according to claim 1; and an electronic component located in the mounting region of the wiring board.

8. The mounting structure according to claim 7 , wherein the electronic component is not electrically connected to the first wiring pattern, and is electrically connected to the second wiring pattern.