JP2020174145A - Wiring board and method for measuring wiring board - Google Patents

Abstract

To enhance the quality of a wiring board.SOLUTION: A wiring board 1 includes a laminate 10 containing two or more conductor layers 21 to 24, and insulating layers 31 to 33 interposed between the respective conductor layers, solder resist layers 41 and 42 covering a first surface 10F and a second surface 10S of the laminate 10 respectively, and a resin film 15 that partially covers an exposed surface of the laminate 10 which is not covered by the solder resist layers 41 and 42. The laminate 10 further has a through-hole 10a penetrating the laminate 10 in the thickness direction thereof, and the solder resist layers 41 and 42 have openings 41a and 42a for exposing the through-hole 10a. The resin film 15 covers edge portions of the solder resist layers 41 and 42 around the openings 41a and 42a on the first and second surfaces 10F and 10S respectively, and covers the inner wall surface 10a1 of the through-hole 10a.SELECTED DRAWING: Figure 1

Description

The present invention relates to a wiring board and a method for manufacturing a wiring board.

Patent Document 1 discloses a wiring board in which a rigid substrate is used. The wiring board has an opening penetrating the wiring board in a predetermined area including a region facing the semiconductor chip mounted on the wiring board.

Japanese Unexamined Patent Publication No. 2014-230010

In the wiring board disclosed in Patent Document 1, the material of the wiring board is released or dropped from the wall surface of the opening as fragments, which may affect the quality of the device in which the wiring board is used.

The wiring board of the present invention has a first surface and a second surface which is an opposite surface of the first surface, and has an insulating layer interposed between two or more conductor layers and each of the two or more conductor layers. A resin that partially covers the laminated body containing the above, the solder resist layer covering each of the first surface and the second surface of the laminated body, and the exposed surface of the laminated body not covered by the solder resist layer. It has a membrane. The laminated body further has through holes penetrating the laminated body in the thickness direction, the solder resist layer has an opening for exposing the through holes, and the resin film has the first and second through holes. Each of the surfaces covers the edge of the solder resist layer around the opening and the inner wall surface of the through hole.

The method for manufacturing a wiring board of the present invention includes preparing a laminate including two or more conductor layers and an insulating layer interposed between the two or more conductor layers, and the first surface and the first surface of the laminate. To form a solder resist layer that covers each of the two surfaces, to form a through hole that penetrates the laminate in the thickness direction in the laminate, and to supply a predetermined resin at least around the through hole. The present invention includes covering the edge of the solder resist layer around the through hole on each of the first and second surfaces and the inner wall surface of the through hole with a resin film.

According to the wiring board of the embodiment of the present invention, it is considered that dust generation from the inner wall of the through hole can be suppressed in the wiring board having the through hole, and the quality of the device in which the wiring board is used can be improved. .. According to the method for manufacturing a wiring board according to the embodiment of the present invention, it is possible to manufacture a wiring board with less dust generated from the inner wall of the through hole.

The cross-sectional view which shows an example of the wiring board of one Embodiment of this invention. The plan view which shows the wiring board of the example of FIG. Enlarged view of Part III of FIG. The cross-sectional view which shows the modification of the wiring board of FIG. FIG. 5 is a cross-sectional view showing another modified example of the wiring board of FIG. The cross-sectional view which shows an example of the laminated body prepared in the manufacturing method of the wiring board of one Embodiment of this invention. FIG. 5 is a cross-sectional view showing an example of a state after formation of a solder resist layer in the method for manufacturing a wiring board according to an embodiment of the present invention. FIG. 5 is a cross-sectional view showing an example of a state after formation of a through hole in the method for manufacturing a wiring board according to an embodiment of the present invention. FIG. 5 is a cross-sectional view showing an example of a state after formation of a resin film in the method for manufacturing a wiring board according to an embodiment of the present invention. FIG. 5 is a cross-sectional view showing an example of a wiring board according to another embodiment of the present invention.

A wiring board according to an embodiment of the present invention will be described with reference to the drawings. 1 and 2 show a cross-sectional view and a plan view of the wiring board 1 which is an example of the wiring board of one embodiment, respectively. FIG. 1 is a cross-sectional view taken along the line II shown in FIG. As shown in FIGS. 1 and 2, the wiring board 1 includes a laminate 10 of an insulating layer and a conductor layer, a solder resist layer (first resin film) 41, and a solder resist layer (second resin film) 42. And have. The laminate 10 has a first surface 10F, which is one of two surfaces orthogonal to the thickness direction of the wiring board 1, and a second surface 10S, which is the opposite surface of the first surface 10F. The laminate 10 has two or more conductor layers (first to fourth conductor layers 21, 22, 23, 24 in the example of FIG. 1) and an insulating layer interposed between the two or more conductor layers (FIG. In the example of 1, the first to third insulating layers 31, 32, 33) are included. The laminated body 10 further has a through hole 10a that penetrates the laminated body 10 in the thickness direction. The solder resist layer 41 covers the first surface 10F of the laminate 10, and the solder resist layer 42 covers the second surface 10S of the laminate 10. The solder resist layer 41 has an opening 41a that exposes the through hole 10a, and the solder resist layer 42 has an opening 42a that exposes the through hole 10a. The wiring board 1 further has a resin film 15 (third resin film). The resin film 15 partially covers the exposed surface of the laminate 10 that is not covered by the solder resist layers 41 and 42. The resin film 15 is formed so as to extend from one of the first surface 10F and the second surface 10S of the laminated body 10 to the other via the inside of the through hole 10a, and covers the inner wall surface 10a1 of the through hole 10a. .. As shown in FIG. 2, in the present embodiment, the inner wall surface 10a1 of the through hole 10a is covered with the resin film 15 over the entire circumference in a plan view.

The through hole 10a may be formed by machining such as laser machining or drilling, as will be described later. On the inner wall surface of the through hole 10a, which may be a surface cut by such processing, cutting chips due to processing may remain without being removed. The remaining cutting debris may be released from the inner wall surface of the through hole to become dust when a circuit board such as the wiring board 1 is used. Then, such dust may float in the through hole 10a or adhere to the surface of the wiring board 1 and / or the component E mounted on the wiring board 1.

However, in the present embodiment, the inner wall surface 10a1 of the through hole 10a is covered with the resin film 15. Therefore, even if cutting chips of a conductive or insulating material forming each conductor layer and each insulating layer of the laminated body 10 remain on the inner wall surface 10a1 of the through hole 10a, such cutting chips and the like remain through the holes. It cannot be released within 10a. Therefore, it is considered that dust composed of cutting chips and the like is prevented from affecting the function of the component E that can be mounted on the wiring board 1.

Further, in the present embodiment, the resin film 15 covers the edge of the solder resist layer 41 around the opening 41a on the first surface 10F of the laminated body 10, and surrounds the opening 42a on the second surface 10S of the laminated body 10. Covers the edge of the solder resist layer 42. Therefore, even if the formation positions of the openings 41a and 42a of the solder resist layers 41 and 42 and / or the formation positions of the resin film 15 are slightly displaced, the first surface 10F and the second surface 10S of the laminate 10 are formed. Either or both of them are difficult to be exposed unintentionally.

In the wiring board 1 of the example of FIG. 1, the core substrate of the wiring board 1 is formed by the first conductor layer 21 and the third conductor layer 23 laminated on both sides of the first insulating layer 31 and the first insulating layer 31, respectively. Has been done. A build-up layer having the second insulating layer 32 and the second conductor layer 22 and a build-up layer having the third insulating layer 33 and the fourth conductor layer 24 are formed with the core substrate interposed therebetween. The first insulating layer 31 is formed with a through-hole conductor 31a that connects the first conductor layer 21 and the third conductor layer 23. The number of conductor layers and insulating layers included in the laminated body 10 is not limited to the example of FIG. 1. For example, the laminated body 10 includes only the first insulating layer 31 and the first and third conductor layers 21 and 23. It may be included, or may include a build-up layer composed of two or more sets of conductor layers and insulating layers.

In the description of the wiring board 1, the side far from the first insulating layer 31 in the thickness direction of the wiring board 1 is also referred to as "upper" or "upper", or simply "upper", and is close to the first insulating layer 31. The side is also referred to as "lower" or "lower", or simply "lower". Further, in each conductor layer and each insulating layer, the surface facing the side opposite to the first insulating layer 31 is also referred to as "upper surface", and the surface facing the first insulating layer 31 side is also referred to as "lower surface". Further, the thickness direction of the wiring board 1 is also simply referred to as "Z direction".

The first surface 10F and the second surface 10S of the laminated body 10 are the other conductor layers constituting the laminated body 10 among the surfaces substantially orthogonal to the Z direction in each of the conductor layer and the insulating layer constituting the laminated body 10. And a part that is not in contact with other insulating layers. Therefore, in the example of FIG. 1, in the region where the conductor pattern of the second conductor layer 22 is formed, the upper surface of the second conductor layer 22 is the first surface 10F, and the conductor pattern of the second conductor layer 22 is formed. In the absence region, the upper surface of the second insulating layer 32 is the first surface 10F. Similarly, in the region where the conductor pattern of the fourth conductor layer 24 is formed, the upper surface of the fourth conductor layer 24 is the second surface 10S, and in the region where the conductor pattern of the fourth conductor layer 24 is not formed, the third surface is the third. The upper surface of the insulating layer 33 is the second surface 10S.

Each conductor layer (first to fourth conductor layers 21 to 24) may have, for example, a metal foil, an electroless plating film, and an electrolytic plating film. Each conductor layer can be formed, for example, with any metal such as copper, nickel, silver, palladium, alone or in combination.

Each insulating layer (first to third insulating layers 31 to 33) is formed by using an arbitrary insulating material. Examples of the insulating material include epoxy resin, bismaleimide triazine resin (BT resin), and phenol resin. Each insulating layer formed using these resins may contain a reinforcing material such as glass fiber or aramid fiber and / or an inorganic filler such as silica.

The second insulating layer 32 includes a via conductor 51 that penetrates the second insulating layer 32 and connects the first conductor layer 21 and the second conductor layer 22. The third insulating layer 33 includes a via conductor 52 that penetrates the third insulating layer 33 and connects the third conductor layer 23 and the fourth conductor layer 24. The via conductors 51 and 52 are so-called filled vias formed by filling through holes penetrating the second and third insulating layers 32 and 33 with a conductor. The via conductors 51 and 52 are integrally formed with the respective upper conductor layers. Therefore, the via conductors 51 and 52 are formed of, for example, an electroless plating film and an electrolytic plating film made of copper, nickel, or the like. The through-hole conductor 31a is also formed of an electroless plating film and an electrolytic plating film made of copper, nickel, or the like.

The second conductor layer 22, which is the outermost conductor layer on the first surface 10F side of the laminated body 10, has a connection pad 22a for the component E mounted on the wiring board 1. The component E can be mounted on the wiring board 1 so as to straddle the through hole 10a as in the example of FIG. In that case, the component E may be an electronic component including a light receiving element such as an image pickup element or an optical system element including a light emitting element that receives or emits light passing through the through hole 10a. Further, the component E may be an electronic component having a wireless communication function for receiving or transmitting radio waves passing through the through hole 10a, or may be an optical component such as a lens.

When such a component E is mounted on the wiring board 1, the through hole 10a can function as an optical path or a waveguide. If dust is suspended in the through hole 10a capable of having such a function, the function of the component E may be affected by the dust, but in the present embodiment, such a situation is avoided by the resin film 15. Can be done. It is considered that the wiring board 1 can contribute to improving the quality of the electronic device used.

The fourth conductor layer 24, which is the outermost conductor layer on the second surface 10S side of the laminated body 10, includes a connection pad 22a for the component E mounted on the wiring board 1 so as to straddle the through hole 10a. May be good. The connection pad 22a may be provided on either one of the second and fourth conductor layers 22 and 24, or the connection pad 22a may be provided on both conductor layers.

In the example of FIG. 1, the fourth conductor layer 24 includes a plurality of connection pads 24a. Each of the connection pads 22a included in the second conductor layer 22 described above has a plurality of connection pads via the via conductor 51, the first conductor layer 21, the through-hole conductor 31a, the third conductor layer 23, and the via conductor 52. It may be electrically connected to one or more of 24a. Although not shown, a surface protective film made of Au, Ni / Au, Ni / Pd / Au, solder, heat-resistant preflux, or the like may be formed on the surfaces of the connection pads 22a and 24a.

The solder resist layer 41 has an opening for exposing the connection pad 22a in addition to the opening 41a. The solder resist layer 42 has an opening for exposing the connection pad 24a in addition to the opening 42a. The solder resist layers 41 and 42 can be formed by using any material having an insulating property. The materials of the solder resist layers 41 and 42 may be composed of, for example, an epoxy resin or a polyimide resin as a main raw material.

The resin film 15 can also be formed using any resin material. The material of the resin film 15 may be composed of an epoxy resin, a silicone resin, an acrylic resin, or the like as a main raw material.

As shown in FIG. 2, the through hole 10a included in the wiring board 1 of FIG. 1 has a rectangular planar shape as a whole, and is formed in a substantially central portion of the wiring board 1. In FIG. 2, the innermost solid line of the quadrangular squares drawn in the central portion of the wiring board 1 indicates the inner side surface 15a of the resin film 15. The broken line drawn next to the inner side surface 15a of the resin film 15 indicates the inner wall surface 10a1 of the through hole 10a. Further, the broken line drawn adjacent to the outside of the inner wall surface 10a1 indicates the inner edge of the opening 41a of the solder resist layer 41.

As shown in FIG. 2, the inner edge of the opening 41a of the solder resist layer 41 is located further outside the through hole 10a in a plan view than the inner wall surface 10a1 of the through hole 10a. Although not shown in FIG. 2, the inner edge of the opening 42a of the solder resist layer 42 is also located outside the through hole 10a in a plan view from the inner wall surface 10a1 of the through hole 10a.

As shown in FIG. 2, the resin film 15 is formed over the entire circumference of the through hole 10a and has a frame-like planar shape. The resin film 15 covers the inner wall surface 10a1 of the through hole 10a and the inner edge of the opening 41a of the solder resist layer 41 over the entire circumference of the through hole 10a. Therefore, the outer surface 15b of the resin film 15 is located outside the opening 41a (and the opening 42a (not shown)) in a plan view.

In the example of FIG. 2, the plurality of connection pads 22a are arranged along the two sides on the outside of each of the two opposing sides of the through hole 10a. The component E (see FIG. 1) mounted on the wiring board 1 is mounted on the wiring board 1 so as to straddle the through hole 10a, and a predetermined terminal (not shown) of the component E is connected to the connection pad 22a. obtain. The connection pads 22a are not limited to the example of FIG. 2, and an arbitrary number of connection pads 22a are provided at an arbitrary position according to the component E. The connection pads 22a may be arranged, for example, on the outside of each of the four sides of the substantially rectangular through hole 10a along each of the four sides.

FIG. 3 shows an enlarged view of part III of FIG. As shown in FIG. 3, in the region near the through hole 10a in the laminated body 10, the conductor patterns of the second and fourth conductor layers 22 and 24 (see FIG. 1) are not formed. Therefore, the first surface 10F and the second surface 10S of the laminated body 10 are composed of the upper surfaces of the second and third insulating layers 32 and 33, respectively. In the wiring board 1, the inner edge of the opening 41a of the solder resist layer 41 is located outside the through hole 10a with respect to the inner wall surface 10a1 of the through hole 10a. Therefore, the first surface 10F of the laminated body 10 has a region in the vicinity of the through hole 10a that is not covered by the solder resist layer 41. Similarly, the inner edge of the opening 42a of the solder resist layer 42 is located outside the through hole 10a with respect to the inner wall surface 10a1 of the through hole 10a. Therefore, the second surface 10S of the laminated body 10 has a region not covered by the solder resist layer 42 in the vicinity of the through hole 10a.

Then, the resin film 15 comes into contact with the region between the inner edge of the opening 41a of the solder resist layer 41 and the inner wall surface 10a1 of the through hole 10a on the first surface 10F of the laminated body 10 and exposed in the opening 41a. There is. Similarly, the resin film 15 is in contact with the region between the inner edge of the opening 42a of the solder resist layer 42 and the inner wall surface 10a1 of the through hole 10a on the second surface 10S of the laminated body 10 and exposed in the opening 42a. ing.

As will be described later, the resin film 15 can be formed, for example, after the solder resist layers 41 and 42 have been cured. In that case, the resin film 15 may not be able to adhere to the solder resist layers 41 and 42 with sufficient strength. On the other hand, in the second and third insulating layers 32 and 33 constituting the first and second surfaces 10F and 10S in the region around the through hole 10a, the second conductor layer 22 or the fourth conductor layer 24 is strong. Each upper surface may have an appropriate rough surface so that it can be adhered to the surface. Therefore, it is considered that the first surface 10F and the second surface 10S of the laminate 10 can adhere to the resin film 15 more firmly than the solder resist layers 41 and 42. Therefore, in the wiring board 1 on which the resin film 15 is formed as in the example of FIG. 3, it is presumed that the resin film 15 and the laminate 10 are unlikely to be peeled off.

The distance D1 between the inner edges of the openings 41a and 42a of the solder resist layers 41 and 42 and the inner wall surface 10a1 of the through hole 10a is, for example, 50 μm or more and 150 μm or less. When the distance D1 has a length in such a range, the resin film 15 is difficult to peel off from the laminated body 10, and the connection pad 22a can be arranged at a position relatively close to the through hole 10a. Further, the length D2 of the portion where the solder resist layers 41 and 42 and the resin film 15 overlap each other in the direction substantially orthogonal to the inner wall surface 10a1 of the through hole 10a is, for example, 50 μm or more and 100 μm or less. When the distance D2 has a length in such a range, unintentional exposure of the first surface 10F and / or the second surface 10S of the laminated body 10 is prevented, and relatively from the through hole 10a. The connection pad 22a may be arranged at a close position.

Further, the thickness T1 of the portion of the resin film 15 that overlaps with the solder resist layers 41 and 42 is, for example, 5 μm or more and 30 μm or less. When the thickness T1 has a thickness in such a range, cracks and the like are unlikely to occur in the resin film 15 on the solder resist layers 41 and 42. In addition, a component E (see FIG. 1), such as a semiconductor integrated circuit device having a package with a relatively low standoff height, may be mounted on the wiring board 1 so as to straddle the resin film 15.

As shown in FIG. 3, the surface of the portion of the resin film 15 that covers the inner wall surface 10a1 of the through hole 10a is curved so as to be convex toward the inside of the through hole 10a. That is, the thickness of the resin film 15 on the inner wall surface 10a1 of the through hole 10a is thick in the central portion in the Z direction and thin in the vicinity of the first surface 10F and the second surface 10S. In the example of FIG. 3, the first insulating layer 31 forming the central portion of the wiring board 1 in the Z direction is the core layer of the wiring board 1. Therefore, the first insulating layer 31 may include a reinforcing material such as glass fiber or aramid fiber in order to obtain appropriate rigidity. When the first insulating layer 31 contains such a fibrous material, the fiber debris cut by the formation of the through hole 10a may protrude relatively long from the central portion of the inner wall surface 10a1 in the Z direction. .. The resin film 15 having a curved surface as in the example of FIG. 3 is preferable because it is easy to cover such fiber debris without exposing it.

The shapes of the inner edges of the resin film 15 and the openings 41a and 42a of the solder resist layers 41 and 42, respectively, are not limited to the shapes exemplified in FIG. 4A and 4B show a modification of the wiring board 1 of FIG. 1, respectively, and a portion corresponding to part III of FIG. 1 in each modification is shown.

In the modified example of FIG. 4A, the resin film 15 has a substantially flat surface at a portion covering the inner wall surface 10a1 of the through hole 10a. Since the surface of the resin film 15 is not curved toward the inside of the through hole 10a, the opening size of the through hole 10a may be smaller than that in the example of FIG. The resin film 15 may have such a flat surface in the through hole 10a, and the surface curved so as to be recessed toward the inner wall surface 10a1 unless the inner wall surface 10a1 of the through hole 10a is exposed. May have. Since the structures and shapes of the components other than the resin film 15 in FIG. 4A are the same as those in the example of FIG. 3, the description of these components will be omitted.

In the example of FIG. 4B, the inner wall surfaces of the openings 41a and 42a of the solder resist layers 41 and 42 are inclined so as to approach the through hole 10a toward the center of the wiring board 1 in the Z direction. In other words, the inner wall surfaces of the openings 41a and 42a of the solder resist layers 41 and 42 are inclined so as to be farther from the through hole 10a toward the outer surface side of the wiring board 1 in the Z direction. Then, the resin film 15 covers the upper surfaces of the solder resist layers 41 and 42 and the exposed surfaces of the first and second surfaces 10F and 10S together with the inclined inner wall surfaces of the openings 41a and 42a. Since the inner wall surfaces of the openings 41a and 42a are inclined, the change in the thickness of the resin film 15 on the first and second surfaces 10F and 10S of the example of FIG. 4B is smaller than that of the example of FIG. .. In the resin film 15, it is considered that local fragile portions and stress concentration are unlikely to occur. Since the structures and shapes of the components other than the resin film 15 in FIG. 4B are the same as those in the example of FIG. 3, the description of these components will be omitted.

Next, the method for manufacturing the wiring board of one embodiment will be described with reference to FIGS. 5A to 5D, using the wiring board 1 shown in FIG. 1 as an example.

As shown in FIG. 5A, the method for manufacturing the wiring board of the present embodiment includes two or more conductor layers (first to fourth conductor layers 21, 22, 23, 24 in FIG. 5A) and two or more conductor layers. It includes preparing a laminate 10 including an insulating layer (in FIG. 5A, the first to third insulating layers 31, 32, 33) interposed between the conductor layers. The laminate 10 forms, for example, the first conductor layer 21, the second insulating layer 32, and the second conductor layer 22 in this order on one surface of the first insulating layer 31, and on the other surface of the first insulating layer 31. It is prepared by forming the third conductor layer 23, the third insulating layer 33, and the fourth conductor layer 24 in this order.

For example, a double-sided copper-clad laminate having an insulating substrate to be the first insulating layer 31 and copper foil laminated on both sides thereof is prepared. A through hole for forming a through-hole conductor 31a is formed in the double-sided copper-clad laminate by laser processing, and a conductor film is formed on the inner wall of the through hole and the surface of the double-sided copper-clad laminate by electroless plating or sputtering. Is formed. Then, the first conductor layer 21 and the third conductor layer 23 having a desired conductor pattern are subjected to a subtractive method including electroplating using this conductor film as a seed layer and a feeding layer, and etching using an appropriate mask. In addition, a through-hole conductor 31a is formed. That is, the core substrate of the wiring board 1 is formed. The first and third conductor layers 21, 23, and the through-hole conductor 31a may be formed by a semi-additive method.

A sheet-like epoxy resin is laminated on the exposed surface of the first insulating layer 31 exposed between the conductor patterns of the first conductor layer 21 and the first conductor layer 21, and is thermocompression bonded to the second. The insulating layer 32 is formed. The first insulating layer 31 is exposed on the third conductor layer 23 and between the conductor patterns of the third conductor layer 23, preferably at the same time as the formation of the second insulating layer 32, in the same manner as the formation of the second insulating layer 32. A third insulating layer 33 is formed on the exposed surface of the above. In the formation of the second and third insulating layers 32 and 33, a metal foil such as a copper foil may be thermocompression bonded onto the second and third insulating layers 32 and 33. Holes for forming the via conductors 51 and 52 are formed in the second and third insulating layers 32 and 33 at predetermined positions by irradiation with laser light or the like.

Then, for example, by a semi-additive method, a second conductor layer 22 having a desired conductor pattern is formed on the second insulating layer 32, and a via conductor 51 is formed in the second insulating layer 32. Further, a fourth conductor layer having a desired conductor pattern on the third insulating layer 33 at the same time as the formation of the second conductor layer 22 is preferably performed by the same method as the method for forming the second conductor layer 22 and the via conductor 51. 24 is formed, and the via conductor 52 is formed in the third insulating layer 33. For example, by going through the above steps, a laminate 10 having a first surface 10F as a surface on the second conductor layer 22 side and a second surface 10S as a surface on the fourth conductor layer 24 side is prepared.

As shown in FIG. 5B, the method for manufacturing a wiring board of the present embodiment further comprises a solder resist layer 41 covering the first surface 10F of the laminate 10 and a solder resist covering the second surface 10S of the laminate 10. Includes forming layer 42. In the formation of the solder resist layers 41 and 42, for example, a resin layer containing a photosensitive epoxy resin, a polyimide resin, or the like is formed on the first surface 10F and the second surface 10S of the laminate 10. Examples of the method for forming the photosensitive resin layer include spray coating, curtain coating, deposition of liquid resin by printing, or lamination of sheet-like resin. By using the method of laminating sheet-like resins, it may be possible to form flatter solder resist layers 41 and 42. The formed resin layer is exposed and developed using an exposure mask having an appropriate opening pattern to form openings 41b and 42b that expose the connection pads 22a and 24a. After the openings 41b and 42b are formed, the solder resist layers 41 and 42 are finally cured to the final state by heating, for example.

As shown in FIG. 5B, forming the solder resist layers 41 and 42 means that the solder resist layers 41 and 42 are formed in a predetermined region corresponding to the through holes 10a (see FIG. 5C) formed in the laminated body 10 in the subsequent step. It may include forming the openings 41a, 42a of 42. When the wiring board 1 of FIG. 1 is manufactured, openings 41a and 42a are formed. Preferably, the openings 41a and 42a including the region A in which the through hole 10a to be formed in the subsequent step is to be formed are formed inside in a plan view. In other words, the openings 41a and 42a are preferably formed so that the entire through hole 10a fits inside the openings 41a and 42a in a plan view. The openings 41a and 42a can be formed at the same time as the openings 41b and 42b are formed in the same manner as the openings 41b and 42b that expose the connection pads 22a and 24a.

As shown in FIG. 5C, in the method for manufacturing a wiring board of the present embodiment, a through hole 10a that penetrates the laminated body 10 in the thickness direction of the laminated body 10 is further formed in a predetermined region of the laminated body 10. Includes. Examples of the method for forming the through hole 10a include drilling, router processing, and laser processing, but the method for forming the through hole 10a is not limited to these. When the through hole 10a is formed by laser processing, for example, laser light from a CO ₂ laser or the like is irradiated along the contour of the formation region of the through hole 10a in the laminated body 10. Then, the through hole 10a can be formed by pulling out the portion surrounded by the irradiation path of the laser light.

The through hole 10a is formed in the opening 41a and the opening 42a when the opening 41a and the opening 42a are formed in the formation of the solder resist layers 41 and 42 described above. By forming the through holes 10a inside the inner edges of the openings 41a and 42a, the regions exposed on the first surface 10F and the second surface 10S of the laminated body 10 without being covered by the solder resist layers 41 and 42. Is provided. If the openings 41a and 42a are not formed in the formation of the solder resist layers 41 and 42, the openings 41a and 42a can be formed by drilling or laser processing to form the through holes 10a. In that case, the wiring board 1a of another embodiment described later may be formed.

As shown in FIG. 5D, the method for manufacturing the wiring board of the present embodiment includes the inner wall surface 10a1 of the through hole 10a, the edge of the solder resist layer 41 around the through hole 10a, and the solder around the through hole 10a. It includes covering the edge of the resist layer 42 with the resin film 15. The resin film 15 covers the edges of the solder resist layers 41 and 42 along the openings 41a and 42a on the first surface 10F and the second surface 10S of the laminated body 10, respectively. The resin film 15 is formed by supplying a predetermined resin such as an epoxy resin, a silicone resin, or an acrylic resin to at least the periphery of the through hole 10a.

As shown in FIG. 5D, in forming the resin film 15, first, the solder resist layers 41 and 42 on the first and second surfaces 10F and 10S of the laminated body 10 and the inner wall surface 10a1 of the through hole 10a are formed. A predetermined resin may be supplied to the entire surface of the above. Then, a resin film 15 that covers the entire surfaces of the laminate 10 and the solder resist layers 41 and 42 may be formed. Predetermined resins, such as epoxy resins, can be supplied by any method such as inkjet, spin coating, spray coating, or roll coating. By such a method, a sufficient amount of resin can be supplied to the inner wall surface 10a1 of the through hole 10a.

After that, the resin supplied to the regions other than the inner wall surface 10a1 of the through hole 10a, the edge portion along the opening 41a of the solder resist layer 41, and the edge portion along the opening 42a of the solder resist layer 42 is removed. .. This removal is performed, for example, by exposure and development with a mask having a suitable aperture pattern.

In this way, the portion of the uncured resin film 15 formed on the entire surfaces of the laminate 10 and the solder resist layers 41 and 42 that covers a predetermined region other than the periphery of the through hole 10a is removed. As a result, the resin film 15 that covers only the desired portion is formed. Then, the resin film 15 is finally cured by heating as needed. By going through the above steps, the wiring board 1 shown in FIG. 1 is completed.

After the step shown in FIG. 5B, even if a surface protective film (not shown) is formed on the connection pads 22a and 24a exposed to the openings 41b and 42b of the solder resist layers 41 and 42, if necessary. Good. For example, electroless plating, solder leveler, spray coating, or the like can form a surface protective film made of Au, Ni / Au, Ni / Pd / Au, solder, heat-resistant preflux, or the like.

FIG. 6 shows a wiring board 1a which is an example of another embodiment. The wiring board 1a shown in FIG. 6 also has a laminate 10 of a conductor layer and an insulating layer, solder resist layers 41 and 42, and a resin film 15 in the same manner as the wiring board 1 of the embodiment illustrated in FIG. And is included. The laminated body 10 has a through hole 10a. The resin film 15 covers the inner wall surface 10a1 of the through hole 10a, and also covers the edges of the solder resist layers 41 and 42 around the through hole 10a on the first surface 10F and the second surface 10S of the laminate 10. There is.

On the other hand, in the wiring board 1a of FIG. 6, the inner edges of the openings 41a and 42a of the solder resist layers 41 and 42 are abbreviated as the inner wall surface 10a1 of the through hole 10a in the cross section along the Z direction as shown in FIG. Match. The inner wall surface of each of the openings 41a and 42a and the inner wall surface 10a1 of the through hole 10a are substantially flush with each other. That is, the solder resist layers 41 and 42 cover the first surface 10F and the second surface 10S of the laminated body 10 until they reach the inner wall surface 10a1 of the through hole 10a in a plan view. The first surface 10F and the second surface 10S of the laminate 10 do not have an exposed region in the openings 41a and 42a of the solder resist layers 41 and 42.

In the wiring board 1 illustrated in FIG. 1 referred to above, the thickness of the portion of the wiring board 1 covered by the resin film 15 changes stepwise from the inner wall surface 10a1 of the through hole 10a toward the outside of the through hole 10a. To do. On the other hand, in the example of FIG. 6, the portion of the wiring board 1a covered with the resin film 15 includes not only the laminate 10 but also the solder resist layers 41 and 42 at the end surface including the inner wall surface 10a1 of the through hole 10a. It has a thickness. Therefore, the thickness of the resin film 15 on the first and second surfaces 10F and 10S may be made thicker than the example of FIG. 1 if necessary. For example, by forming the resin film 15 to a desired thickness, for example, the height of the component E having the solder bump E1 at the time of mounting may be controlled within a desired range. When there is little concern about peeling between the resin film 15 and the solder resist layers 41 and 42, as illustrated in FIG. 6, the openings 41a and 42a having the inner wall surface 10a1 of the through hole 10a and the substantially flush inner wall surface are the solder. It may be formed on the resist layers 41 and 42.

The wiring board of the embodiment is not limited to the structure exemplified in each drawing and the structure, shape, and material exemplified in this specification. For example, the through hole 10a can be provided at an arbitrary position on the wiring board 1 in a plan view. Further, the laminated body 10 may be a so-called coreless substrate in which a conductor layer and an insulating layer are laminated in one direction without having a core substrate. Further, the via conductors 51 and 52 and the through-hole conductor 31a do not necessarily have to be formed.

The method for manufacturing the wiring board of the embodiment is not limited to the method described with reference to each drawing. For example, the second and fourth conductor layers 22 and 24 may be patterned by the subtractive method. Arbitrary steps may be added to the method for manufacturing the wiring board of the embodiment in addition to the above-mentioned steps, or a part of the above-mentioned steps may be omitted.

1, 1a Wiring board 10 Laminated body 10a Through hole 10a 1 Inner wall surface 15 Resin film 21 First conductor layer 22 Second conductor layer 23 Third conductor layer 24 Fourth conductor layer 22a Connection pad 31 First insulating layer (core layer)
32 Second Insulation Layer 33 Third Insulation Layer 41, 42 Solder Resist Layers 41a, 42a Aperture E Parts

Claims (8)

A laminate having a first surface and a second surface opposite to the first surface, and including two or more conductor layers and an insulating layer interposed between the two or more conductor layers.
A solder resist layer covering each of the first surface and the second surface of the laminate, and
A resin film that partially covers the exposed surface of the laminate that is not covered by the solder resist layer, and
It is a wiring board having
The laminate further has through holes that penetrate the laminate in the thickness direction.
The solder resist layer has an opening that exposes the through hole.
The resin film covers the edge of the solder resist layer around the opening and the inner wall surface of the through hole on each of the first and second surfaces. In the wiring board according to claim 1, the inner edge of the opening of the solder resist layer is located outside the through hole in a plan view from the inner wall surface of the through hole. The wiring board according to claim 2, wherein the resin film is in contact with each of the first surface and the second surface of the laminate exposed in the opening of the solder resist layer. The surface of the wiring board according to claim 1, which covers the inner wall surface of the through hole in the resin film, is curved so as to be convex toward the inside of the through hole. The wiring board according to claim 1, wherein at least one of the two or more conductor layers, the outermost conductor layer on the first surface side and the outermost surface layer on the second surface side, is said to be the above. It has a connection pad for an electronic component or an optical component mounted on the wiring board so as to straddle the through hole. To prepare a laminate including two or more conductor layers and an insulating layer interposed between the two or more conductor layers,
To form a solder resist layer covering each of the first surface and the second surface of the laminate,
By forming a through hole in the laminated body that penetrates the laminated body in the thickness direction,
By supplying a predetermined resin at least around the through hole, the edge of the solder resist layer around the through hole and the inner wall surface of the through hole on each of the first and second surfaces are covered with a resin film. Covering and
A method of manufacturing a wiring board, including. The method for manufacturing a wiring board according to claim 6, wherein forming the solder resist layer includes forming an opening in the solder resist layer including a region in which the through hole should be formed. There is. The method for manufacturing a wiring board according to claim 6, further comprising removing the resin film covering a predetermined area other than the periphery of the through hole.

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