Wiring circuit boards, bonded wiring circuit boards, and wiring circuit board assembly sheets

Abstract

The present invention provides a wiring circuit board, a bonded wiring circuit board, and a wiring circuit board assembly sheet that can be made thinner. [Solution] The wiring circuit board 100 is joined to the wiring circuit board 200 and includes a laminated portion 110 and a joint portion 120. In the laminated portion 110, a metal layer 112, an intermediate insulating layer 111, and a metal layer 113 are laminated. The joint portion 120 is connected to one of the metal layers 112 and 113. The joint portion 120 is joinable to the wiring circuit board 200. The thickness of the joint portion 120 is less than the thickness of the laminated portion 110. The thickness of the joint portion 120 is greater than the thickness of the metal layer connected to the joint portion 120.

Description

Technical Field

[0001] The present invention relates to a wiring circuit board, a joined wiring circuit board, and a sheet of an assembly of wiring circuit boards.

Background Art

[0002] A wiring circuit board is used to transmit an electrical signal between a plurality of electronic components. Such wiring circuit boards are formed on a sheet of an assembly of wiring circuit boards in a plurality of arranged states. Here, in order to increase the number of wiring circuit boards that can be formed on one sheet of an assembly of wiring circuit boards, a plurality of components obtained by dividing each wiring circuit board may be formed on the sheet of an assembly of wiring circuit boards.

[0003] For example, in the original web described in Patent Document 1, a plurality of first flexible circuit sheets and a plurality of second flexible circuit sheets are formed. Each first flexible circuit sheet and each second flexible circuit sheet are cut out from the original web. One first flexible circuit sheet and one second flexible circuit sheet are partially overlapped, and the overlapped portion is joined to complete a flexible circuit sheet joined body.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the flexible circuit sheet joined body described in Patent Document 1, a step occurs at the joined portion between the first flexible circuit sheet and the second flexible circuit sheet. In this case, since the thickness of the flexible circuit sheet joined body becomes partially large, it is difficult to make the flexible circuit sheet joined body thinner.

[0006] The object of the present invention is to provide a wiring circuit board, a bonded wiring circuit board, and a wiring circuit board assembly sheet that can be made thinner. [Means for solving the problem]

[0007] A wiring circuit board according to a first aspect of the present invention is a wiring circuit board that is joined to another circuit board, comprising: a first laminated portion in which a first metal layer, a first insulating layer, and a second metal layer are laminated; and a first joint portion connected to one of the metal layers, the first metal layer and the second metal layer, and joinable to the other circuit board, wherein the thickness of the first joint portion is greater than the thickness of the metal layer connected to the first joint portion and less than the thickness of the first laminated portion.

[0008] A bonded wiring circuit board according to a second aspect of the present invention comprises a first wiring circuit board which is the above-described wiring circuit board, and a second wiring circuit board bonded to the first bond of the first wiring circuit board, wherein the second wiring circuit board includes a second laminated portion in which a third metal layer, a second insulating layer, and a fourth metal layer are laminated, and a second bond connected to one of the metal layers, the third metal layer and the fourth metal layer, and bonded to the first bond of the first wiring circuit board, wherein the thickness of the second bond is greater than the thickness of the metal layer connected to the second bond and less than the thickness of the second laminated portion.

[0009] A wiring circuit board assembly sheet according to a third aspect of the present invention comprises a first wiring circuit board which is the above-described wiring circuit board, a second wiring circuit board which can be bonded to the first joint of the first wiring circuit board, and a support which supports the first wiring circuit board and the second wiring circuit board, wherein the second wiring circuit board includes a second laminated portion in which a third metal layer, a second insulating layer and a fourth metal layer are laminated, and a second joint portion which is connected to one of the metal layers, the third metal layer and the fourth metal layer, and can be bonded to the first joint of the first wiring circuit board, wherein the thickness of the second joint portion is greater than the thickness of the metal layer connected to the second joint portion and less than the thickness of the second laminated portion. [Effects of the Invention]

[0010] According to the present invention, the wiring circuit board can be made thinner. [Brief explanation of the drawing]

[0011] [Figure 1] This is a plan view of an aggregate sheet according to the first embodiment of the present invention. [Figure 2] This is an enlarged view of the region in the assembled sheet of Figure 1 that includes a set of wiring circuit boards. [Figure 3] This is a plan view of a bonded wiring circuit board. [Figure 4] Figure 2 is a cross-sectional view of the aggregate sheet along line AA. [Figure 5] Figure 3 is a cross-sectional view of the BB line of the bonded wiring circuit board. [Figure 6] This is a diagram illustrating an example of a manufacturing method for a wiring circuit board. [Figure 7] This is a diagram illustrating an example of a manufacturing method for a wiring circuit board. [Figure 8] This is a diagram illustrating an example of a manufacturing method for a wiring circuit board. [Figure 9] This is a diagram illustrating an example of a manufacturing method for a wiring circuit board. [Figure 10] This is a diagram illustrating an example of a manufacturing method for a wiring circuit board. [Figure 11] This is a diagram illustrating an example of a manufacturing method for a wiring circuit board. [Figure 12] This is a diagram illustrating an example of a manufacturing method for a wiring circuit board. [Figure 13] This is a plan view of a bonded wiring circuit board according to a second embodiment. [Figure 14] Figure 13 is a cross-sectional view of the bonded wiring circuit board along the CC line. [Figure 15] This is a plan view showing another example of a composite sheet. [Figure 16] This is a cross-sectional view showing another example of a bonded wiring circuit board.

Best Mode for Carrying Out the Invention

[0012] 1. First Embodiment (1) Configuration of Wiring Circuit Board Hereinafter, a wiring circuit board, a bonded wiring circuit board, and a wiring circuit board assembly sheet (hereinafter abbreviated as an assembly sheet) according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a plan view of an assembly sheet according to the first embodiment of the present invention. As shown in FIG. 1, in the assembly sheet 500, two directions orthogonal to each other are defined as the X direction and the Y direction as indicated by the arrows X and Y. In this example, the X direction and the Y direction are directions parallel to the horizontal plane.

[0013] The assembly sheet 500 includes a support 510, a plurality of wiring circuit boards 100, and a plurality of wiring circuit boards 200. The support 510 is a rectangular sheet member. A pair of sides of the support 510 extend in the X direction, and the other pair of sides extend in the Y direction. The support 510 is formed of, for example, stainless steel. The support 510 may be formed of other metal materials such as aluminum (Al).

[0014] The support 510 supports a plurality of wiring circuit boards 100 and a plurality of wiring circuit boards 200. In the example of FIG. 1, in the support 510, a row in which a plurality of wiring circuit boards 100 are arranged side by side in the X direction and a row in which a plurality of wiring circuit boards 200 are arranged side by side in the X direction are alternately provided in the Y direction. In FIG. 1, in order to easily distinguish between the wiring circuit board 100 and the wiring circuit board 200, the wiring circuit board 100 is illustrated by a solid line, and the wiring circuit board 200 is illustrated by a dashed line.

[0015] Figure 2 is an enlarged view of the region in the assembly sheet 500 of Figure 1 that includes a pair of wiring circuit boards 100 and 200. As shown in Figure 2, in this example, in plan view, each wiring circuit board 100 and each wiring circuit board 200 have a substantially semicircular shape. In the direction in which the pair of wiring circuit boards 100 and 200 are arranged (in this example, the Y direction), the maximum distance between a portion of wiring circuit board 100 and a portion of wiring circuit board 200 is L1.

[0016] After the assembly sheet 500 is manufactured, each wiring circuit board 100 and each wiring circuit board 200 are separated from the support 510. A joined wiring circuit board is manufactured by joining the end of one wiring circuit board 100 separated from the support 510 to the end of another wiring circuit board 100. Figure 3 is a plan view of the joined wiring circuit board. As shown in Figure 3, in this example, the joined wiring circuit board 400 has an annular shape. The outer diameter of the joined wiring circuit board 400 is L2.

[0017] In this example, when the assembled sheet 500 is viewed in the X direction, the wiring circuit boards 100 formed in one row and the wiring circuit boards 200 formed in an adjacent row in the Y direction partially overlap (see Figure 2 and Figure 4 described later). In this case, the maximum distance L1 between the portion of wiring circuit board 100 and the portion of wiring circuit board 200 becomes smaller than the outer diameter L2 of the bonded wiring circuit board 400. This makes it possible to form a larger number of sets of wiring circuit boards 100, 200 on a single assembled sheet 500. As a result, a larger number of bonded wiring circuit boards 400 can be obtained from a single assembled sheet 500.

[0018] Figure 4 is a cross-sectional view of the assembly sheet 500 of Figure 2, along line AA. Specifically, Figure 4 shows longitudinal cross-sectional views of one wiring circuit board 100 and one wiring circuit board 200 near one end in the X direction. The structure near the other end of wiring circuit boards 100 and 200 in the X direction is the same as the structure in Figure 4. Therefore, the illustration of the other end of wiring circuit boards 100 and 200 in the X direction is omitted.

[0019] As shown in Figure 4, the wiring circuit board 100 includes a laminated portion 110, a joint portion 120, a base insulating layer 130, and a cover insulating layer 140. The laminated portion 110 includes an intermediate insulating layer 111 and metal layers 112 and 113. The metal layer 112 has a predetermined pattern and is formed on one side of the intermediate insulating layer 111. The metal layer 113 has a predetermined pattern and is formed on the other side of the intermediate insulating layer 111. That is, in the laminated portion 110, the metal layer 112, the intermediate insulating layer 111, and the metal layer 113 are laminated together. In this example, the metal layer 112 and the metal layer 113 are electrically connected by a connecting conductor 114.

[0020] The intermediate insulating layer 111 is formed of, for example, polyimide. The intermediate insulating layer 111 may also be formed of other resin materials such as epoxy. The metal layers 112, 113 and the connecting conductor 114 are formed of, for example, copper. The metal layers 112, 113 and the connecting conductor 114 may also be formed of other metals such as gold (Au) or aluminum. Alternatively, the metal layers 112, 113 and the connecting conductor 114 may be formed of an alloy such as a copper alloy or an aluminum alloy.

[0021] The joint 120 includes a base layer 121 and plating layers 122 and 123. The base layer 121 is formed integrally with the metal layer 112 of the wiring circuit board 100 so as to protrude from the metal layer 112. The plating layer 122 is formed on the base layer 121. The plating layer 123 is formed on the plating layer 122. The joint 120 is used to join the wiring circuit board 200.

[0022] In this example, the base layer 121 is formed from the same material as the metal layer 112. Furthermore, in the direction in which the metal layer 112, the intermediate insulating layer 111, and the metal layer 113 are stacked, the base layer 121 has approximately the same thickness as the metal layer 112. Therefore, the thickness of the joint 120 is greater than the thickness of the metal layer 112. In this example, the plating layer 122 is formed from the same material as the metal layer 113 of the wiring circuit board 100. The plating layer 123 may be formed from a material having higher conductivity and corrosion resistance than the plating layer 122. For example, the plating layer 123 may be formed from gold (Au).

[0023] The base insulating layer 130 is formed on the support 510 so as to cover the metal layer 112 of the laminated portion 110 and the base layer 121 of the joint portion 120. The cover insulating layer 140 is formed on the base insulating layer 130 so as to cover the laminated portion 110. The joint portion 120 is exposed and not covered by the cover insulating layer 140. The base insulating layer 130 and the cover insulating layer 140 may be formed from the same material as the intermediate insulating layer 111.

[0024] The wiring circuit board 200 includes a laminated portion 210, a joint portion 220, a base insulating layer 230, and a cover insulating layer 240. The laminated portion 210 includes an intermediate insulating layer 211 and metal layers 212 and 213. In this example, metal layer 212 and metal layer 213 are electrically connected by a connecting conductor 214. The joint portion 220 is used for joining with the wiring circuit board 100 and includes a base layer 221 and plating layers 222 and 223. Except that the patterns of metal layers 212 and 213 differ from the patterns of metal layers 112 and 113, the wiring circuit board 200 has the same configuration as the wiring circuit board 100. Therefore, a detailed description of the wiring circuit board 200 is omitted.

[0025] Each of the joints 120 and 220 is formed such that the difference between the sum of the thicknesses of joint 120 and joint 220 and the thickness of the laminated portion 110 is less than or equal to a predetermined value (e.g., ±30 μm). Furthermore, each of the joints 120 and 220 is formed such that the difference between the sum of the thicknesses of joint 120 and joint 220 and the thickness of the laminated portion 210 is less than or equal to a predetermined value (e.g., ±30 μm). In addition, the thicknesses of the base insulating layer 130, cover insulating layer 140, base insulating layer 230, and cover insulating layer 240 are approximately equal.

[0026] Figure 5 is a cross-sectional view of the joined wiring circuit board 400 shown in Figure 3, along line BB. Specifically, Figure 5 shows a cross-sectional view of the joint between the wiring circuit board 100 and the wiring circuit board 200. As shown in Figure 5, the wiring circuit boards 100 and 200 are arranged so that the plating layer 123 of the joint 120 and the plating layer 223 of the joint 220 are in contact. In this state, ultrasonic waves are irradiated onto the plating layers 123 and 223. In this case, the plating layer 123 and the plating layer 223 are integrally bonded, thereby joining the wiring circuit board 100 and the wiring circuit board 200. This completes the joined wiring circuit board 400.

[0027] As described above, the difference between the sum of the thicknesses of the joint 120 and the joint 220 and the thickness of the laminated portion 110 or the laminated portion 210 is less than or equal to a predetermined value. Furthermore, the thickness of the base insulating layer 130 and the thickness of the cover insulating layer 240 are approximately equal, and the thickness of the cover insulating layer 140 and the thickness of the base insulating layer 230 are approximately equal. Therefore, as shown by the dashed line in Figure 5, there is almost no step difference at the joint between the wiring circuit board 100 and the wiring circuit board 200.

[0028] (2) Method for manufacturing a wiring circuit board The assembled sheet 500 is manufactured, for example, by a roll-to-roll method. The manufacturing method of the wiring circuit boards 100 and 200 will be described below with reference to cross-sections of the wiring circuit boards 100 and 200 formed on the assembled sheet 500. Figures 6 to 12 are diagrams illustrating an example of the manufacturing method of the wiring circuit boards 100 and 200. Figures 6 to 12 correspond to the cross-sectional view of line AA of the assembled sheet 500 in Figure 2.

[0029] First, as shown in Figure 6, a base insulating layer 130 is formed in the area on the support 510 where the wiring circuit board 100 is to be placed. Also, a base insulating layer 230 is formed in the area on the support 510 where the wiring circuit board 200 is to be placed. The base insulating layers 130 and 230 may be formed by coating the entire upper surface of the support 510 with a photosensitive resin precursor and exposing a predetermined area of ​​the photosensitive resin precursor using ultraviolet light.

[0030] Next, as shown in Figure 7, a metal layer 112 and a base layer 121 are formed on the base insulating layer 130. A metal layer 212 and a base layer 221 are also formed on the base insulating layer 230. Specifically, a seed layer is formed by sputtering to cover the upper surfaces of the base insulating layers 130 and 230, and then a mask having a predetermined pattern of openings is formed on the seed layer. Examples of seed layer materials include chromium, copper, nickel, titanium, or alloys thereof. The mask is formed, for example, by exposing and developing a photosensitive dry film resist.

[0031] Subsequently, a conductive layer having a predetermined pattern is formed on the seed layer through the pattern openings of the mask, for example, by plating. In this example, the conductive layer is formed by a semi-additive method, but the embodiments are not limited thereto. The conductive layer may also be formed by an additive method or a subtractive method.

[0032] Of the conductor layer on the base insulating layer 130, the portion covered by the cover insulating layer 140 formed in a later process becomes the metal layer 112, and the portion exposed from the cover insulating layer 140 becomes the base layer 121. Therefore, the base layer 121 is formed integrally with the metal layer 112 when the metal layer 112 is formed. Also, of the conductor layer on the base insulating layer 230, the portion covered by the cover insulating layer 240 formed in a later process becomes the metal layer 212, and the portion exposed from the cover insulating layer 240 becomes the base layer 221. Therefore, the base layer 221 is formed integrally with the metal layer 212 when the metal layer 212 is formed.

[0033] Next, as shown in Figure 8, an intermediate insulating layer 111 is formed on the metal layer 112. An intermediate insulating layer 211 is also formed on the metal layer 212. The method for forming the intermediate insulating layers 111 and 211 is the same as the method for forming the base insulating layers 130 and 230 in Figure 6.

[0034] Subsequently, as shown in Figure 9, a connecting conductor 114 is formed on the metal layer 112, a metal layer 113 is formed on the intermediate insulating layer 111 so as to be electrically connected to the connecting conductor 114, and a plating layer 122 is formed on the base layer 121. Also, a connecting conductor 214 is formed on the metal layer 212, a metal layer 213 is formed on the intermediate insulating layer 211 so as to be electrically connected to the connecting conductor 214, and a plating layer 222 is formed on the base layer 221. The method for forming the metal layers 113, 213, connecting conductors 114, 214, and plating layers 122, 222 is the same as the method for forming the metal layers 112, 212 and base layers 121, 221 in Figure 7.

[0035] In this way, the laminated portion 110 is formed by laminating the metal layer 112, the intermediate insulating layer 111, and the metal layer 113. Similarly, the laminated portion 210 is formed by laminating the metal layer 212, the intermediate insulating layer 211, and the metal layer 213. According to the above manufacturing method, the plating layer 122 is formed from the same material as the metal layer 113 when the metal layer 113 is formed. Likewise, the plating layer 222 is formed from the same material as the metal layer 213 when the metal layer 213 is formed.

[0036] Next, as shown in Figure 10, a cover insulating layer 140 is formed on the base insulating layer 130 so as to cover the laminated portion 110 and expose the plating layer 122. A cover insulating layer 240 is also formed on the base insulating layer 230 so as to cover the laminated portion 210 and expose the plating layer 222. The method for forming the cover insulating layers 140 and 240 is the same as the method for forming the base insulating layers 130 and 230 in Figure 6.

[0037] Next, as shown in Figure 11, a plating layer 123 is formed on the plating layer 122 exposed from the cover insulating layer 140. A plating layer 223 is also formed on the plating layer 222 exposed from the cover insulating layer 240. The plating layers 123 and 223 are formed, for example, by gold plating. The base layer 121 and the plating layers 122 and 123 form a joint 120, and the base layer 221 and the plating layers 222 and 223 form a joint 220. This completes the wiring circuit boards 100 and 200. As a result, the assembled sheet 500 is completed.

[0038] Finally, as shown in Figure 12, the support 510 is removed. The support 510 may be removed by etching using an etching solution such as ferric chloride solution. This separates the manufactured wiring circuit boards 100 and 200.

[0039] (3) Effects In the assembled sheet 500 according to this embodiment, a wiring circuit board 100 and a wiring circuit board 200 that can be joined together are supported by a support 510. The wiring circuit boards 100 and 200 are separated from the support 510. The separated wiring circuit boards 100 and 200 are joined together to form a joined wiring circuit board 400.

[0040] The wiring circuit board 100 includes a laminated portion 110 and a joint portion 120. In the laminated portion 110, a metal layer 112, an intermediate insulating layer 111, and a metal layer 113 are laminated. The joint portion 120 is connected to the metal layer 112 and can be joined to the joint portion 220 of the wiring circuit board 200. The thickness of the joint portion 120 is greater than the thickness of the metal layer 112 and less than the thickness of the laminated portion 110.

[0041] The wiring circuit board 200 includes a laminated portion 210 and a joint portion 220. In the laminated portion 210, a metal layer 212, an intermediate insulating layer 211, and a metal layer 213 are laminated. The joint portion 220 is connected to the metal layer 212 and can be joined to the joint portion 120 of the wiring circuit board 100. The thickness of the joint portion 220 is greater than the thickness of the metal layer 212 and less than the thickness of the laminated portion 210.

[0042] According to the above configuration, it is prevented that an excessively large step will occur at the joint between the wiring circuit board 100 and the wiring circuit board 200. In this example, the joint portion 120 is formed such that the difference between the sum of the thickness of the joint portion 120 and the thickness of the joint portion 220 of the wiring circuit board 200 to be joined, and the thickness of the laminated portion 110, is less than or equal to a predetermined value. The joint portion 220 is formed such that the difference between the sum of the thickness of the joint portion 220 and the thickness of the joint portion 120 of the wiring circuit board 100 to be joined, and the thickness of the laminated portion 210, is less than or equal to a predetermined value. In this case, almost no step occurs at the joint between the wiring circuit board 100 and the wiring circuit board 200. This makes it possible to more reliably make the joined wiring circuit board 400 thinner.

[0043] The joint 120 includes a base layer 121 integrally formed with the metal layer 112, and plating layers 122 and 123 formed on the base layer 121. In this case, the thickness of the joint 120 can be easily made greater than the thickness of one of the metal layers. Furthermore, the base layer 121 can be formed simultaneously with the metal layer 112. Therefore, the manufacturing efficiency of the wiring circuit board 100 can be improved. Moreover, the plating layer 122 may be formed from the same material as the metal layer 113. In this case, the plating layer 122 can be formed simultaneously with the metal layer 113. Therefore, the manufacturing efficiency of the wiring circuit board 100 can be further improved. The same applies to the wiring circuit board 200.

[0044] 2. Second Embodiment (1) Configuration of a bonded wiring circuit board The differences between the wiring circuit boards 100, 200, bonded wiring circuit board 400, and assembly sheet 500 according to the second embodiment of the present invention and those according to the first embodiment will be explained. Figure 13 is a plan view of the bonded wiring circuit board 400 according to the second embodiment. As shown in Figure 13, in this embodiment, the bonded wiring circuit board 400 includes a pair of connecting boards 300 in addition to the wiring circuit boards 100 and 200.

[0045] Each connecting board 300 has ends 301 and 302. End 301 of one connecting board 300 is joined to one end of the wiring circuit board 100, and end 302 is joined to one end of the wiring circuit board 200. End 301 of the other connecting board 300 is joined to the other end of the wiring circuit board 100, and end 302 is joined to the other end of the wiring circuit board 200. In other words, the wiring circuit board 100 and the wiring circuit board 200 are joined via the connecting board 300. This constitutes the joined wiring circuit board 400.

[0046] Figure 14 is a cross-sectional view of the jointed wiring circuit board 400 shown in Figure 13 along the CC line. That is, Figure 14 shows a cross-sectional view of the joint portion between the wiring circuit boards 100, 200 and the connecting board 300. As shown in Figure 14, the connecting board 300 includes a resin layer 310 and a conductor layer 320. The conductor layer 320 is formed on the resin layer 310. The resin layer 310 may be formed from the same material as the intermediate insulating layer 111 of the wiring circuit board 100. The conductor layer 320 may be formed from the same material as the base layer 121 of the wiring circuit board 100.

[0047] In this embodiment, the joint portion 120 of the wiring circuit board 100 does not need to include the plating layers 122 and 123. Therefore, the thickness of the joint portion 120 may be approximately the same as the thickness of the metal layer (metal layer 112 in this example) connected to the base layer 121. Similarly, the joint portion 220 of the wiring circuit board 200 does not need to include the plating layers 222 and 223. Therefore, the thickness of the joint portion 220 may be approximately the same as the thickness of the metal layer (metal layer 212 in this example) connected to the base layer 221.

[0048] The wiring circuit boards 100 and 200 are arranged so that the joint portion 120 and the joint portion 220 face each other. The connecting board 300 is arranged so that the conductor layer 320 at end 301 contacts the base layer 121 of the joint portion 120, and the conductor layer 320 at end 302 contacts the base layer 221 of the joint portion 220. In this state, ultrasonic waves are irradiated onto the base layers 121, 221 and the conductor layer 320. In this case, the wiring circuit board 100 and the connecting board 300 are joined by the integral bonding of the base layer 121 and the conductor layer 320. Also, the wiring circuit board 200 and the connecting board 300 are joined by the integral bonding of the base layer 221 and the conductor layer 320. This completes the joined wiring circuit board 400.

[0049] The connecting substrate 300 is formed such that the difference between the sum of the thickness of the end portion 301 and the thickness of the joint portion 120 and the thickness of the laminated portion 110 is less than or equal to a predetermined value. Furthermore, the connecting substrate 300 is formed such that the difference between the sum of the thickness of the end portion 302 and the thickness of the joint portion 220 and the thickness of the laminated portion 210 is less than or equal to a predetermined value. The thickness of the connecting substrate 300 may be adjusted by appropriately determining the thickness of the conductive layer 320 formed on the resin layer 310.

[0050] (2) Effects In the assembled sheet 500 according to this embodiment, the wiring circuit board 100 and the wiring circuit board 200 are supported by a support 510. The wiring circuit boards 100 and 200 are separated from the support 510. The separated wiring circuit boards 100 and 200 are joined together via a connecting board 300 to form a joined wiring circuit board 400.

[0051] The thickness of the joint portion 120 of the wiring circuit board 100 that can be joined to the end portion 301 of the connecting board 300 is smaller than the thickness of the laminated portion 110. Similarly, the thickness of the joint portion 220 of the wiring circuit board 200 that can be joined to the end portion 302 of the connecting board 300 is smaller than the thickness of the laminated portion 210. Therefore, it is prevented that an excessively large step difference occurs at the joint portion between the wiring circuit boards 100, 200 and the connecting board 300.

[0052] In this example, as described above, the difference between the sum of the thickness of the end portion 301 of the connecting substrate 300 and the thickness of the joint portion 120 and the thickness of the laminated portion 110 or the thickness of the laminated portion 210 is less than or equal to a predetermined value. Also, the difference between the sum of the thickness of the end portion 302 of the connecting substrate 300 and the thickness of the joint portion 220 and the thickness of the laminated portion 110 or the thickness of the laminated portion 210 is less than or equal to a predetermined value.

[0053] In this configuration, as shown by the dotted line in Figure 14, there is almost no step at the joint between the wiring circuit board 100 and the connecting board 300. Similarly, as shown by the dashed line in Figure 14, there is almost no step at the joint between the wiring circuit board 200 and the connecting board 300. As a result, even when a joined wiring circuit board 400 is constructed by joining the wiring circuit board 100 and the wiring circuit board 200 via the connecting board 300, the joined wiring circuit board 400 can be made thinner.

[0054] 3. Other Embodiments (1) In the above embodiment, rows of multiple wiring circuit boards 100 arranged in the X direction and rows of multiple wiring circuit boards 200 arranged in the X direction are alternately provided on the assembly sheet 500 in the Y direction, but the embodiment is not limited to this. As long as it is possible to provide a larger number of wiring circuit boards 100, 200, the multiple wiring circuit boards 100, 200 may be provided on the assembly sheet 500 in other arrangements.

[0055] For example, the assembly sheet 500 may be arranged such that multiple rows of wiring circuit boards 100 and 200 are arranged alternately in the X direction, and these rows are arranged alternately in the Y direction. The assembly sheet 500 may be arranged such that wiring circuit boards 100 and 200 are arranged alternately in the X and Y directions. The left half of the assembly sheet 500 may be equipped with wiring circuit boards 100, and the right half of the assembly sheet 500 may be equipped with wiring circuit boards 200. The upper half of the assembly sheet 500 may be equipped with wiring circuit boards 100, and the lower half of the assembly sheet 500 may be equipped with wiring circuit boards 200.

[0056] Figure 15 is a plan view showing another example of the assembly sheet 500. As shown in Figure 15, some of the multiple wiring circuit boards 100, 200 may be provided on the assembly sheet 500 such that their ends face in the opposite direction from the other wiring circuit boards. Alternatively, the wiring circuit boards 100 and 200 may be provided on separate assembly sheets 500. That is, multiple wiring circuit boards 100 may be provided on one assembly sheet 500, and multiple wiring circuit boards 200 may be provided on another assembly sheet 500.

[0057] (2) In the above embodiment, the bonded wiring circuit board 400 has an annular shape, but the embodiment is not limited thereto. The bonded wiring circuit board 400 may have other shapes, such as an elliptical annular shape.

[0058] (3) In the above embodiment, the bonded wiring circuit board 400 is formed by joining two wiring circuit boards 100 and 200, but the embodiment is not limited thereto. The bonded wiring circuit board 400 may be formed by joining three or more wiring circuit boards. Even when three or more wiring circuit boards are joined, the portions of the two wiring circuit boards to be joined may have the configuration shown in Figure 5 or Figure 14.

[0059] (4) In the above embodiment, the joint 120 is connected to the metal layer 112 and the joint 220 is connected to the metal layer 212, but the embodiment is not limited thereto. Figure 16 is a cross-sectional view showing another example of a jointed wiring circuit board 400. As shown in Figure 16, in the wiring circuit board 100, the joint 120 may be connected to the metal layer 113. In this case, the base layer 121 is formed integrally with the metal layer 113. Therefore, the base layer 121 has approximately the same thickness as the metal layer 113. In the wiring circuit board 200, the joint 220 may be connected to the metal layer 213. In this case, the base layer 221 is formed integrally with the metal layer 213. Therefore, the base layer 221 has approximately the same thickness as the metal layer 213.

[0060] Alternatively, the bonded wiring circuit board 400 may be constructed by joining a wiring circuit board 100, whose joint portion 120 is connected to a metal layer 112, and a wiring circuit board 200, whose joint portion 220 is connected to a metal layer 213. Similarly, the bonded wiring circuit board 400 may be constructed by joining a wiring circuit board 100, whose joint portion 120 is connected to a metal layer 113, and a wiring circuit board 200, whose joint portion 220 is connected to a metal layer 212.

[0061] (5) In the first embodiment, the joint 120 includes both the plating layer 122 and the plating layer 123, and the joint 220 includes both the plating layer 222 and the plating layer 223, but the embodiment is not limited thereto. The joint 120 does not have to include either the plating layer 122 or the plating layer 123, and the joint 220 does not have to include either the plating layer 222 or the plating layer 223. If the joint 120 does not include the plating layer 122, the plating layer 123 is formed on the underlayer 121. If the joint 220 does not include the plating layer 222, the plating layer 223 is formed on the underlayer 221.

[0062] If the joint 120 does not include the plating layer 123, a temporary protective layer may be formed on the plating layer 122 during the distribution stage of the wiring circuit board 100 to prevent corrosion of the plating layer 122. Similarly, if the joint 220 does not include the plating layer 223, a temporary protective layer may be formed on the plating layer 222 during the distribution stage of the wiring circuit board 200 to prevent corrosion of the plating layer 222. At the time of manufacturing the jointed wiring circuit board 400, the manufacturer can manufacture the jointed wiring circuit board 400 by removing the temporary protective layer from each of the plating layers 122 and 222 and joining the joint 120 of the wiring circuit board 100 and the joint 220 of the wiring circuit board 200.

[0063] In the second embodiment as well, a temporary protective layer may be formed on the base layer 121 to prevent corrosion of the base layer 121 during the distribution stage of the wiring circuit board 100. Similarly, a temporary protective layer may be formed on the base layer 221 to prevent corrosion of the base layer 221 during the distribution stage of the wiring circuit board 200. At the time of manufacturing the bonded wiring circuit board 400, the manufacturer can manufacture the bonded wiring circuit board 400 by removing the temporary protective layer from each of the base layers 121 and 221 and bonding the joint portion 120 of the wiring circuit board 100 and the joint portion 220 of the wiring circuit board 200 to the connecting board 300.

[0064] (6) In the second embodiment, the joint 120 does not include the plating layers 122, 123, and the joint 220 does not include the plating layers 222, 223, but the embodiment is not limited thereto. Similar to the first embodiment, the joint 120 may include one or both of the plating layers 122, 123. The joint 220 may include one or both of the plating layers 222, 223.

[0065] (7) In the first embodiment, the joint 120 of the wiring circuit board 100 and the joint 220 of the wiring circuit board 200 are joined by ultrasonic bonding, but the embodiment is not limited to this. The joint 120 and the joint 220 may be joined by solder or a connecting material such as ACF (anisotropic conductive film). In this configuration, the thickness of the joint portion between the wiring circuit board 100 and the wiring circuit board 200 will be increased by the thickness of the connecting material. Even in this case, each of the joint portions 120 and 220 is formed so that there is almost no step difference at the joint portion between the wiring circuit board 100 and the wiring circuit board 200.

[0066] Similarly, in the second embodiment, the joint 120 of the wiring circuit board 100 and the joint 220 of the wiring circuit board 200 and the connecting board 300 are ultrasonically bonded, but the embodiment is not limited to this. The joints 120 and 220 and the connecting board 300 may be bonded by a connecting material. In this configuration, the thickness of the joint portion between the wiring circuit boards 100, 200 and the connecting board 300 increases by the thickness of the connecting material. Even in this case, the connecting board 300 is formed so that there is almost no step difference at the joint portion with the wiring circuit boards 100, 200.

[0067] 4. Correspondence between each component of the claim and each part of the embodiment The following describes examples of the correspondence between each component of the claims and each element of the embodiments, but the present invention is not limited to the following examples. Various other elements having the configuration or function described in the claims can also be used as each component of the claims.

[0068] In the above embodiment, the wiring circuit board 100 is an example of a wiring circuit board or a first wiring circuit board, the wiring circuit board 200 is an example of another circuit board or a second wiring circuit board, and the metal layer 112 is an example of a first metal layer. The intermediate insulating layer 111 is an example of a first insulating layer, the metal layer 113 is an example of a second metal layer, the laminated portion 110 is an example of a first laminated portion, and the joint portion 120 is an example of a first joint portion.

[0069] The bonded wiring circuit board 400 is an example of a bonded wiring circuit board, the metal layer 212 is an example of a third metal layer, the intermediate insulating layer 211 is an example of a second insulating layer, and the metal layer 213 is an example of a fourth metal layer. The laminated portion 210 is an example of a second laminated portion, the joint portion 220 is an example of a second joint portion, the support 510 is an example of a support, and the assembled sheet 500 is an example of a wiring circuit board assembled sheet.

[0070] 5. Summary of the Embodiments (Paragraph 1) The wiring circuit board relating to Paragraph 1 is, A wiring circuit board that is joined to other circuit boards, A first laminated portion comprising a first metal layer, a first insulating layer, and a second metal layer, It comprises a first joint that is connected to one of the metal layers, the first metal layer and the second metal layer, and is bondable to the other circuit board, The thickness of the first joint is greater than the thickness of the metal layer connected to the first joint, and less than the thickness of the first laminated portion.

[0071] This wiring circuit board is joined to another circuit board. If the other circuit board has a similar configuration to the wiring circuit board, the first joint of the wiring circuit board and the joint of the other circuit board will be joined. Here, the thickness of the first joint is greater than the thickness of one of the metal layers connected to the first joint, but less than the thickness of the first laminated portion, so that an excessively large step does not occur at the joint between the wiring circuit board and the other circuit board. As a result, even when the wiring circuit board and the other circuit board are joined, the joined wiring circuit board can be made thinner.

[0072] (Article 2) In the wiring circuit board described in Article 1, The first joint may be formed such that the difference between the sum of the thickness of the first joint and the thickness of the other circuit board portion to be joined, and the thickness of the first laminated portion, is less than or equal to a predetermined value.

[0073] In this case, there is virtually no step difference at the joint between the wiring circuit board and other circuit boards. This makes it possible to more reliably make the joined wiring circuit boards thinner.

[0074] (Article 3) The joint wiring circuit board relating to Article 3 is A first wiring circuit board which is a wiring circuit board as described in paragraph 1, The first wiring circuit board comprises a second wiring circuit board joined to the first joint of the first wiring circuit board, A second laminated portion in which a third metal layer, a second insulating layer, and a fourth metal layer are laminated, It includes a second joint connected to one of the third metal layer and the fourth metal layer, and joined to the first joint of the first wiring circuit board, The thickness of the second joint is greater than the thickness of the metal layer connected to the second joint, and less than the thickness of the second laminated portion.

[0075] In this bonded wiring circuit board, the first wiring circuit board and the second wiring circuit board are joined together. This makes it possible to make the bonded wiring circuit board thinner. In addition, it is possible to more reliably prevent the occurrence of an excessively large step at the joint between the first wiring circuit board and the second wiring circuit board.

[0076] (Article 4) In the joint wiring circuit board described in Article 3, The first joint and the second joint may be formed such that the difference between the sum of the thicknesses of the first joint and the second joint and the thickness of the first laminated portion or the thickness of the second laminated portion is less than or equal to a predetermined value.

[0077] In this case, there is almost no step difference at the joint between the first wiring circuit board and the second wiring circuit board. This makes it possible to more reliably make the joined wiring circuit board thinner.

[0078] (Article 5) The wiring circuit board assembly sheet relating to Article 5 is A first wiring circuit board which is a wiring circuit board as described in paragraph 1, A second wiring circuit board that can be joined to the first joint of the first wiring circuit board, The system comprises a support that supports the first wiring circuit board and the second wiring circuit board, The second wiring circuit board described above is A second laminated portion in which a third metal layer, a second insulating layer, and a fourth metal layer are laminated, It includes a second joint that is connected to one of the third metal layer and the fourth metal layer and can be joined to the first joint of the first wiring circuit board, The thickness of the second joint is greater than the thickness of the metal layer connected to the second joint, and less than the thickness of the second laminated portion.

[0079] In this wiring circuit board assembly sheet, a first wiring circuit board and a second wiring circuit board, which can be joined to each other, are supported by a support. Since the first wiring circuit board is the aforementioned wiring circuit board, even when the first wiring circuit board and the second wiring circuit board are joined, the joined wiring circuit board can be made thinner. Furthermore, it is possible to more reliably prevent the occurrence of an excessively large step at the joint between the first wiring circuit board and the second wiring circuit board.

[0080] (Item 6) In the wiring circuit board assembly sheet described in Item 5, The first joint and the second joint may be formed such that the difference between the sum of the thicknesses of the first joint and the second joint and the thickness of the first laminated portion or the thickness of the second laminated portion is less than or equal to a predetermined value.

[0081] In this case, there is almost no step difference at the joint between the first wiring circuit board and the second wiring circuit board. This makes it possible to more reliably make the joined wiring circuit boards thinner. [Explanation of Symbols]

[0082] 100, 200…Wiring circuit board, 110, 210…Laminated section, 111, 211…Intermediate insulating layer, 112, 113, 212, 213…Metal layer, 114, 214…Connecting conductor, 120, 220…Joint section, 121, 221…Underlayment layer, 122, 123, 222, 223…Plating layer, 130, 230…Underlayment insulating layer, 140, 240…Cover insulating layer, 300…Connecting board, 301, 302…End section, 310…Resin layer, 320…Conductor layer, 400…Jointed wiring circuit board, 500…Assembly sheet, 510…Support

Claims

1. A wiring circuit board that is joined to other circuit boards, A first laminated portion comprising a first metal layer, a first insulating layer, and a second metal layer, It comprises a first joint that is connected to one of the metal layers, the first metal layer and the second metal layer, and is bondable to the other circuit board, A wiring circuit board in which the thickness of the first joint is greater than the thickness of the metal layer connected to the first joint and less than the thickness of the first laminated portion.

2. The wiring circuit board according to claim 1, wherein the first joint is formed such that the difference between the sum of the thickness of the first joint and the thickness of the other circuit board portion to be joined and the thickness of the first laminated portion is less than or equal to a predetermined value.

3. A first wiring circuit board which is a wiring circuit board according to claim 1, The first wiring circuit board comprises a second wiring circuit board joined to the first joint of the first wiring circuit board, The second wiring circuit board described above is A second laminated portion in which a third metal layer, a second insulating layer, and a fourth metal layer are laminated, It includes a second joint that is connected to one of the third metal layer and the fourth metal layer and is joined to the first joint of the first wiring circuit board, A bonded wiring circuit board in which the thickness of the second joint is greater than the thickness of the metal layer connected to the second joint and less than the thickness of the second laminated portion.

4. The jointed wiring circuit board according to claim 3, wherein the first joint and the second joint are formed such that the difference between the sum of the thickness of the first joint and the thickness of the second joint and the thickness of the first laminate or the thickness of the second laminate is less than or equal to a predetermined value.

5. A first wiring circuit board which is a wiring circuit board according to claim 1, A second wiring circuit board that can be joined to the first joint of the first wiring circuit board, The system comprises a support that supports the first wiring circuit board and the second wiring circuit board, The second wiring circuit board described above is A second laminated portion in which a third metal layer, a second insulating layer, and a fourth metal layer are laminated, It includes a second joint that is connected to one of the third metal layer and the fourth metal layer and can be joined to the first joint of the first wiring circuit board, A wiring circuit board assembly sheet wherein the thickness of the second joint is greater than the thickness of the metal layer connected to the second joint and less than the thickness of the second laminate.

6. The wiring circuit board assembly sheet according to claim 5, wherein the first joint and the second joint are formed such that the difference between the sum of the thickness of the first joint and the thickness of the second joint and the thickness of the first laminated portion or the thickness of the second laminated portion is less than or equal to a predetermined value.

Images