JP2020174147A - 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, and a solder resist layer 40 covering a first surface 10F and a second surface 10S of the laminate 10. The laminate 10 further has a through-hole 10a penetrating the laminate 10 in the thickness direction thereof, and the solder resist layer 40 passes through the through-hole 10a from one of the first surface 10F and the second surface 10S of the laminate 10 to the other surface, is continuous, and covers an 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. It has a laminated body containing the above, and a solder resist layer covering the first surface and the second surface of the laminated body. Then, the laminated body further has a through hole penetrating the laminated body in the thickness direction, and the solder resist layer has the through hole from one to the other of the first surface and the second surface of the laminated body. It is continuous through the inside of the inside and covers 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 penetrating the laminate in the thickness direction. A through hole is formed in the laminated body, and a solder resist layer covering the first surface and the second surface of the laminated body is passed through the inside of the through hole from one of the first surface and the second surface to the other. It includes covering the inner wall surface of the through hole with a resin film by forming the through hole so as to be continuous.

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. FIG. 3 is a partial cross-sectional view showing a modified example of the wiring board of FIG. FIG. 5 is a cross-sectional view showing another modified example of the wiring board of FIG. The plan view which shows the wiring board of FIG. 4A. 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 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 solder resist layer in the method for manufacturing a wiring board according to an 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, and a solder resist layer 40. 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 40 covers the first surface 10F on the first surface 10F side of the laminated body 10, and covers the second surface 10S on the second surface 10S side of the laminated body 10. The solder resist layer 40 is continuous from one of the first surface 10F and the second surface 10S of the laminated body 10 through the inside of the through hole 10a. The solder resist layer 40 covers the inner wall surface 10a1 of the through hole 10a inside 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 solder resist layer 40 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 solder resist layer 40. 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 inner wall surface 10a1 of the through hole 10a is covered with the solder resist layer 40 covering the first surface 10F and the second surface 10S of the laminated body 10. That is, the inner wall surface 10a1 is covered with a covering body integrally with the first surface 10F and the second surface 10S of the laminated body 10 and with the solder resist layer 40 covering the first surface 10F and the second surface 10S. ing. The solder resist layer 40 has openings 41 and 42 that expose the connection pads 22a and 24a, respectively, as will be described later. The solder resist layer 40 can function as a separating means between the connection pads in order to prevent mounting defects such as solder shorts on the first surface 10F and the second surface 10S. The solder resist layer 40 can also function as an antioxidant means for the second and fourth conductor layers 22 and 24 and a mechanical protection means for the laminate 10.

In the present embodiment, the solder resist layer 40 is formed, and the covering body continuous from the first surface 10F to the second surface 10S penetrates not only the first surface 10F and the second surface 10S of the laminated body 10. The inner wall surface 10a1 of the hole 10a is also covered. Therefore, it is considered that both suppression of solder shorts and the like and suppression of malfunctions of electronic devices due to dust can be realized with a simple structure. Therefore, it is considered that this embodiment can contribute to improving the quality of the wiring board and / or the electronic device using the wiring board.

Further, since the inner wall surface 10a1 of the through hole 10a is covered with the solder resist layer 40 capable of having the functions as the above-mentioned means, the inner wall surface 10a1 composed of the first to third insulating layers 31 to 33 is in good contact with the inner wall surface 10a1. The covering body to be used can be provided on the inner wall surface 10a1.

In the wiring board 1 of the example of FIG. 1, the core substrate of the wiring board 1 is formed by the first insulating layer 31 and the first conductor layer 21 and the third conductor layer 23 laminated on both sides thereof. 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 caused by the solder resist layer 40. Can be avoided. 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 40 has an opening 41 for exposing the connection pad 22a and an opening 42 for exposing the connection pad 24a. The solder resist layer 40 can be formed by using any material having an insulating property. The material of the solder resist layer 40 may be composed of, for example, an epoxy resin, a polyimide resin, or the like as a main raw material. The plurality of openings 41 and 42 can be formed so as to be lined up at a fine pitch, and the material of the solder resist layer 40 can be sufficiently adhered to the inner wall surface 10a1 of the through hole 10a.

In the wiring board 1 of FIG. 1, the surface of the portion of the solder resist layer 40 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 solder resist layer 40 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. 1, 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 solder resist layer 40 having a curved surface on the inner wall surface 10a1 as in the example of FIG. 1 is preferable because it is easy to cover such fiber debris without exposing it.

In the example of FIG. 1, the maximum thickness T1 of the solder resist layer 40 on the inner wall surface 10a1 is 10 μm or more and 80 μm or less. Further, examples of the thickness T2 of the solder resist layer 40 on the first surface 10F and the second surface 10S of the laminated body 10 are 10 μm or more and 50 μm or less. The ratio of the thickness T1 to the thickness T2 (T1 / T2) is, for example, 1.0 or more and 3.0 or less. If the ratio of the thickness T1 to the thickness T2 is within this range, thermal expansion in the thickness direction of the solder resist layer 40 between the first surface 10F and the second surface 10S and the inner wall surface 10a1. It is considered that the solder resist layer 40 is unlikely to be distorted or peeled due to the difference in the amount (heat shrinkage amount).

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. As described above, the solder resist layer 40 covers the inner wall surface 10a1 over the entire circumference of the through hole 10a in a plan view. Unlike the example of FIG. 2, the inner wall surface 10a1 does not necessarily have to be covered with the solder resist layer 40 over the entire circumference of the through hole 10a. Even if the inner wall surface 10a1 of the through hole 10a is partially exposed, the detachment of dust from at least the portion covered with the solder resist layer 40 can be prevented.

In the example of FIG. 2, the plurality of connection pads 22a are arranged along the two sides of the pair of facing holes 10a facing each other, and are exposed in the opening 41 of the solder resist layer 40. .. 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. To. 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.

The cross-sectional shape of the solder resist layer 40 in the through hole 10a is not limited to the shape having a curved surface as illustrated in FIG. FIG. 3 shows a modified example of the wiring board 1 of FIG. 1, and a portion corresponding to part III of FIG. 1 in the modified example is shown.

In the modified example of FIG. 3, the solder resist layer 40 has a substantially flat surface at a portion covering the inner wall surface 10a1 of the through hole 10a. Since the surface of the solder resist layer 40 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 solder resist layer 40 may have such a flat surface in the through hole 10a, and if even the inner wall surface 10a1 of the through hole 10a is not unintentionally exposed, the solder resist layer 40 is recessed toward the inner wall surface 10a1. It may have a curved surface. Since the structures and shapes of the components other than the solder resist layer 40 in FIG. 3 are the same as those in the example of FIG. 1, the description of these components is omitted.

4A and 4B show a cross-sectional view and a plan view of the wiring board 1a, which is still another example of the wiring board 1 of FIG. 1, respectively. FIG. 4A is a cross-sectional view taken along the line IVA-IVA shown in FIG. 4B. As shown in FIGS. 4A and 4B, the solder resist layer 40 of the wiring board 1a has an opening 40a around the through hole 10a on each of the first surface 10F and the second surface 10S of the laminated body 10. There is. The first surface 10F or the second surface 10S of the laminated body 10 is exposed in the opening 40a.

In the wiring board 1a, as shown in FIG. 4B, a plurality of openings 40a are formed so as to surround the through hole 10a in a plan view. Further, each of the plurality of openings 40a has a slit-shaped planar shape, and a series of openings 40a are arranged in a perforated line along each side of the through hole 10a in a plan view. By providing a discontinuous portion of the solder resist layer 40 such as an opening 40a around the through hole 10a, the solder between the first surface 10F and the second surface 10S and the inner wall surface 10a1 described above. It may be possible to absorb strain due to a difference in the amount of thermal expansion (amount of thermal contraction) of the resist layer 40. Therefore, peeling of the solder resist layer 40 may be prevented.

In the example of FIG. 4B, each of the plurality of openings 40a is formed so as to correspond to the connection pad 22a. That is, the arrangement pitch of the plurality of openings 40a and the arrangement pitch of the connection pad 22a are substantially equal to each other. Each of the plurality of openings 40a and each of the connection pads 22 face each other. Further, two connection pads 22a facing each other across the through hole 10a and two openings 40a facing each other across the through hole 10a are arranged in a row. When a discontinuity such as the opening 40a is formed in this way, it is estimated that the stress that may occur due to the difference in the coefficient of thermal expansion between the component E and the solder resist layer 40 after mounting the component E is relaxed by the discontinuity. Will be done. Therefore, it is considered that cracks and the like are unlikely to occur in the solder resist layer 40.

Further, in the examples of FIGS. 4A and 4B, the opening 40a is formed between the through hole 10a and the connection pad 22a. When the component E is mounted on the wiring board 1a, a protective resin (not shown) such as an underfill material may be filled around the connection pad 22a. In that case, the protective resin may flow into the through hole 10a when the protective resin is filled. However, as in the examples of FIGS. 4A and 4B, when a discontinuity portion such as the opening 40a is formed on the mounting surface of the component E (first surface 10F in FIG. 4A), a certain amount of protective resin is formed. It is considered that it may flow into the discontinuity and stay there. Therefore, it is considered that the inflow of the protective resin into the through hole 10a is likely to be prevented.

The planar shape of the discontinuous portion such as the opening 40a and the arrangement of the plurality of discontinuous portions are not limited to the example of FIG. 4B. For example, one continuous groove may be formed as a discontinuous portion, and the through hole 10a may be surrounded by the groove. The discontinuity can have any planar shape. Further, the discontinuous portion does not necessarily have to surround the through hole 10a over the entire circumference thereof. Further, the discontinuous portion such as the opening 40a may not be provided on both the first surface 10F and the second surface 10S of the laminated body 10, as in the example of FIG. 4A. It may be provided on only one of the first surface 10F and the second surface 10S, for example, only on the surface on which the component E is mounted. Since the structures and shapes of the components other than the discontinuous portion of the solder resist layer 40 in FIGS. 4A and 4B are the same as those in the example of FIG. 1, the description of these components is omitted.

Next, the method for manufacturing the wiring board of one embodiment will be described with reference to FIGS. 5A to 5C, 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, 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.

As shown in FIG. 5C, the method for manufacturing the wiring board of the present embodiment further forms a solder resist layer 40 covering the first surface 10F and the second surface 10S of the laminate 10, and the through hole 10a. The inner wall surface 10a1 of the above is covered with a resin film integrated with the solder resist layer 40. As shown in FIG. 5C, the solder resist layer 40 is formed so as to pass through the inside of the through hole 10a and be continuous from one of the first surface 10F and the second surface 10S of the laminated body 10. By forming the solder resist layer 40 in this way, the inner wall surface 10a1 of the through hole 10a is covered with the resin film which is a part of the solder resist layer 40.

In the formation of the solder resist layer 40, for example, by supplying a photosensitive resin to the laminate 10, as shown in FIG. 5C, together with the inner wall surface 10a1 of the through hole 10a, the first surface 10F of the laminate 10 and A solder resist layer 40 is formed so as to cover the entire surface of the second surface 10S. As described above, an epoxy resin or the like is exemplified as the resin forming the solder resist layer 40. The material of the solder resist layer 40, such as an epoxy resin, is supplied by any method such as, for example, 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.

In the present embodiment, forming the solder resist layer 40 is an opening that exposes the connection pads 22a and 24a to the solder gist layer 40 formed on the entire surfaces of the first surface 10F and the second surface 10S of the laminate 10. May include forming. For example, the solder resist layer 40 before the main curing is exposed and developed using an exposure mask having an appropriate aperture pattern to form openings for exposing the connection pads 22a and 24a. When the above-mentioned discontinuity is provided, it can be formed together with the formation of an opening that exposes the connection pads 22a, 24a. After that, the solder resist layer 40 is finally cured to the final state by heating, for example. By going through the above steps, the wiring board 1 shown in FIG. 1 is completed.

After forming the opening in the solder resist layer 40, a surface protective film (not shown) may be formed on the connection pads 22a and 24a, if necessary. 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.

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. Further, the solder resist layer 40 does not necessarily have to be formed so as to cover the entire surface of the laminated body 10 once in the forming process. For example, the solder resist layer 40 that covers only the desired portion may be formed from the beginning in the formation of the solder resist layer 40 by spray coating using a mask or the like. 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 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 insulating layer 33 Third insulating layer 40 Solder resist layer 40a Aperture (discontinuous part)
E parts

Claims (5)

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 the first surface and the second surface of the laminate, 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 is continuous from one of the first surface and the second surface of the laminate through the inside of the through hole and covers the inner wall surface of the through hole in the inside. The wiring board according to claim 1, wherein the solder resist layer is a partially discontinuous portion around the through hole on the first surface and / or both of the first surface and the second surface of the laminate. have. The surface of the wiring board according to claim 1, which covers the inner wall surface of the through hole in the solder resist layer, 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,
By forming a through hole in the laminated body that penetrates the laminated body in the thickness direction,
The through hole is formed by forming a solder resist layer covering the first surface and the second surface of the laminate so as to pass through the inside of the through hole and to be continuous from one of the first surface and the second surface to the other. Covering the inner wall surface with a resin film
A method of manufacturing a wiring board, including.

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