JP2013247306A - Manufacturing method of wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a wiring board on which an electronic component can be mounted normally without forming a protrusion consisting of copper plating above a through hole, and other insulation layer and a conductor layer can be laminated normally.SOLUTION: The manufacturing method of a wiring board comprises: a step of preparing a double-sided copper-clad plate 3 where a copper foil 2 is clad to both surfaces of an insulating plate 1; a step of boring a through hole 4 in the double-sided copper-clad plate 3 so as to penetrate the copper foil 2 on both surfaces and the insulating plate 1 therebetween with a first diameter D1; a step of forming a plating resist layer 5 that has an opening 6 of second diameter D2 smaller than the first diameter D1 above the through hole 4 with the periphery of the opening 6 projecting above the through hole 4, on the copper foil 2 having double sides; and a step of depositing a through hole conductor 7 consisting of copper plating on the inner wall of the through hole 4, so that both ends of the through hole conductor 7 do not protrude into the opening 6 of the resist layer 5.

Description

  The present invention relates to a method for manufacturing a wiring board including a step of forming a through-hole conductor by copper plating in a through-hole provided in a double-sided copper-clad plate.

  As a wiring board for mounting electronic components such as semiconductor elements, a double-sided copper-clad board with copper foil attached to both sides of an insulating board is used as a starting material, and through-holes are drilled or laser-processed on this double-sided copper-clad board. After forming a through hole conductor, a through hole conductor is formed in the through hole by depositing a copper plating layer comprising electroless plating and electrolytic plating thereon on the inner wall of the through hole and the copper foil surface, and then on the insulating plate. The copper foil and the copper plating layer on it are etched into a predetermined pattern to have wiring conductors consisting of copper foil and the copper plating layer on both sides of the insulating plate, and the wiring conductors on both sides are connected by through-hole conductors There is known a wiring board formed as described above.

  However, in such a wiring board, the strength of the electric field applied between the outer peripheral portion and the central portion of the double-sided copper-clad plate is different when the copper plating layer is deposited on the inner wall of the through hole and the copper foil surface by electrolytic plating. For this reason, the thickness of the copper plating layer on the copper foil is likely to vary greatly. Such a variation in the thickness of the copper plating layer partially causes excessive or insufficient etching when the wiring conductor is formed by etching the copper foil and the copper plating layer on the copper foil into a predetermined pattern. As a result, the wiring conductor cannot be accurately formed in a predetermined pattern, and it is easy to cause a disconnection or a short circuit in the wiring conductor, and it is difficult to form a wiring conductor with a fine pattern. Was.

  Therefore, after forming a through hole in the double-sided copper-clad plate and depositing an electroless copper plating layer on the inner wall of the through-hole and the copper foil surface, the opening corresponding to the opening of the through-hole is formed on both sides of the double-sided copper-clad plate A method of forming a through-hole conductor by forming a plating resist layer that has a portion and covering the copper foil surface and depositing electrolytic copper plating in the through-hole in that state has been proposed.

  According to this method, although the electroless copper plating is deposited on the surface of the copper foil, the electrolytic copper plating is not deposited. Therefore, only the copper foil having a uniform thickness and the electrolytic copper plating thereon are patterned. The wiring conductor having a fine pattern can be accurately formed by etching. However, in this method, when a through-hole conductor made of electrolytic copper plating is deposited on the inner wall of the through hole, there is no plating resist layer on the through hole, so that the electrolytic copper plating is the inner wall of the opening of the plating resist layer. Along the outer surface of the through hole, it is deposited, and as a result, a projection made of electrolytic copper plating is likely to be formed on the through hole.

  As described above, when protrusions made of copper plating are formed on the through holes in the wiring board, when electronic parts such as semiconductor elements are mounted on the wiring board, normal mounting of the electronic parts consists of copper plating. There is an increased risk of being blocked by the protrusions. In addition, when another insulating layer and a conductor layer are laminated on this wiring board to multilayer the wiring board, the normal lamination of another insulating layer and the conductor layer is hindered by protrusions made of copper plating. There is a high risk that

Japanese Patent Laid-Open No. 11-135940

  In the present invention, when a through-hole conductor made of a copper plating layer is formed in a through-hole drilled in a double-sided copper-clad plate, a projection made of copper plating is not formed on the through-hole, and an electronic component is mounted. It is possible to mount electronic components normally when the circuit board is stacked, and even when another insulating layer and a conductor layer are stacked thereon to make a wiring board multilayer, An object of the present invention is to provide a method of manufacturing a wiring board capable of normally laminating an insulating layer and a conductor layer.

  The method of manufacturing a wiring board according to the present invention includes a step of preparing a double-sided copper-clad plate in which copper foils are attached to both sides of an insulating plate, and the double-sided copper-clad plate having the double-sided copper foil and an insulating plate therebetween. Drilling a through-hole penetrating at a first diameter, and having an opening having a second diameter smaller than the first diameter on the through-hole, and a periphery of the opening protruding on the through-hole. Forming a plating resist layer on the copper foils on both sides, and a through-hole conductor made of copper plating on the inner wall of the through-hole. Both ends of the through-hole conductor protrude into the opening of the plating resist layer. And the step of depositing so as not to occur.

  According to the method for manufacturing a wiring board of the present invention, the plating resist layer having an opening having a diameter smaller than the diameter of the through hole on both sides of the double-sided copper-clad plate on which the through hole is formed. Since the periphery of each of the through holes is formed so as to protrude on the through hole, and the through hole conductor made of copper plating is deposited on the inner wall of the through hole so that both ends thereof do not protrude into the opening of the plating resist layer, No protrusion made of copper plating is formed on the through hole. Therefore, it is possible to normally mount the electronic component when mounting the electronic component. In addition, even when another insulating layer and a conductor layer are further laminated thereon to form a multilayer wiring board, the other insulating layer and the conductor layer can be normally laminated. It is to provide a method for manufacturing a substrate.

FIG. 1A to FIG. 1C are schematic cross-sectional views of main parts for each process for explaining an example of an embodiment of a method for manufacturing a wiring board according to the present invention. 2D to 2F are schematic cross-sectional views of main parts for each process for explaining an example of the embodiment of the method for manufacturing a wiring board according to the present invention. FIGS. 3A to 3C are schematic cross-sectional views of relevant parts for each step for explaining another example of the embodiment of the method for manufacturing a wiring board of the present invention. 4D to 4F are schematic cross-sectional views of main parts for each process for explaining another example of the embodiment of the method for manufacturing a wiring board according to the present invention.

  Next, an example of an embodiment of the method for manufacturing a wiring board according to the present invention will be described with reference to FIGS. 1 (a) to 1 (c) and FIGS. 2 (d) to 2 (e).

  First, as shown in FIG. 1A, a double-sided copper-clad plate 3 having a copper foil 2 attached to both sides of an insulating plate 1 is prepared.

  The insulating plate 1 is made of, for example, a plate-like body obtained by impregnating a glass cloth with a thermosetting resin such as an epoxy resin or a bismaleimide triazine resin, and has a thickness of about 40 to 800 μm, for example.

  The copper foil 2 is made of, for example, an electrolytic copper foil having a thickness of about 5 to 18 μm, and is laminated on both surfaces of the insulating plate 1 by being laminated on both surfaces of the insulating plate 1 before curing and thermally curing the insulating plate 1. .

  Next, as shown in FIG.1 (b), the through-hole 4 which penetrates the copper foil 2 of both surfaces and the insulating plate 1 between them is drilled in the double-sided copper-clad board 3. FIG. The diameter D1 of the through hole 4 is, for example, about 70 to 150 μm. The through hole 4 is drilled by employing a drilling technique such as drilling, laser processing, or blasting.

  Next, an electroless copper plating layer (not shown) is deposited on the inner wall of the through hole 4 and the surface of the copper foil 2. The thickness of the electroless copper plating layer is, for example, about 0.1 to 1 μm. Such an electroless copper plating layer attaches a palladium catalyst for electroless plating to the inner wall of the through-hole 4 and the surface of the copper foil 2, and the well-known electroless copper-plated plate 3 to which the palladium catalyst is attached. It is formed by dipping in a copper plating solution.

  Next, as shown in FIG.1 (c), the plating resist layer 5 is formed on the copper foil 2 of both surfaces with which the electroless copper plating layer was adhere | attached. The plating resist layer 5 is made of a thermosetting resin such as an acrylic-modified epoxy resin and has an opening 6 on the through hole 4. The diameter D2 of the opening 6 is smaller than the diameter D1 of the through hole 4 by about 30 to 50 μm, so that the plating resist layer 5 around the opening 6 protrudes from the through hole 4 by about 15 to 25 μm like a ridge. The thickness of the plating resist layer 5 is, for example, about 25 to 50 μm. Such a plating resist layer 5 is formed by adhering a dry film made of a photosensitive resin such as an acrylic-modified epoxy resin on the copper foil 2 on which the through holes 4 are formed, and using a photolithography technique to open the plating resist layer 5. It is formed by exposing and developing so as to have a portion 6.

  Next, as shown in FIG. 2 (d), the inner wall of the through hole 4 to which the electroless copper plating layer is applied is applied, and the electroless copper plating and the electrolytic copper plating thereon are formed. A through-hole conductor 7 is formed. In such electrolytic copper plating, the double-sided copper-clad plate 3 on which the plating resist layer 5 is formed is immersed in a well-known electrolytic copper-plating solution, and the electroless copper-plated coating applied to the surface of the double-sided copper-clad plate 3 It is formed by supplying a charge for electrolytic plating through the layer. At this time, it is important that both ends of the through-hole conductor 7 are attached so as not to protrude into the opening 6 of the plating resist layer 5. Specifically, the through-hole conductor 7 is deposited so that the thickness at both ends is about 10 to 20 μm. Thereby, it is possible to prevent a protrusion made of copper plating from being formed on the through hole. In addition, since the periphery of the opening 6 of the plating resist layer 5 protrudes like a ridge over the through hole 4 at both ends of the through hole 4, the flow of the electrolytic copper plating solution is stagnant. Therefore, deposition of electrolytic copper plating is suppressed at both end portions of the through hole 4, and the thickness of both end portions of the through hole conductor 7 is gradually reduced toward the plating resist layer 5 side. Therefore, even if the through hole conductor 7 has a thickness of about 10 to 20 μm that does not protrude into the opening 6 of the plating resist layer 5, the through hole 4 has a thickness of about 15 to 25 μm at the center of the through hole 4. A conductor 7 can be deposited.

  Next, as shown in FIG. 2 (e), the plating resist layer 5 is peeled and removed from the double-sided copper-clad plate 3. A known alkaline resist stripping solution may be used for stripping the plating resist layer 5.

  Next, as shown in FIG. 2 (f), the copper foils 2 on both sides and the electroless copper plating layer thereon are etched into a predetermined pattern by a well-known subtractive method, whereby copper is formed on the upper and lower surfaces of the insulating plate 1. A wiring conductor 8 comprising a foil and an electroless copper plating layer thereon is formed. Thereby, the wiring board according to the present invention is completed. In this case, although the electroless copper plating is applied to the surface of the copper foil 2, since the electrolytic copper plating is not applied, only the copper foil 2 having a uniform thickness and the electrolytic copper plating thereon are predetermined. By etching the pattern, the wiring conductor 8 having a fine pattern can be accurately formed. Further, no protrusion made of copper plating is formed on the through hole 4. Therefore, it is possible to normally mount the electronic component when mounting the electronic component. Moreover, even when another insulating layer and a conductor layer are further laminated thereon to form a multilayer wiring board, it becomes possible to normally laminate those other insulating layers and conductor layers. .

  In addition, this invention is not limited to an example of the above-mentioned embodiment, and it cannot be overemphasized that a various change is possible if it is a range which does not deviate from the summary of this invention. For example, in the example of the above-described embodiment, after the through-hole conductor 7 is formed, the copper foils on both sides are etched into a predetermined pattern to form the wiring conductor 8. The wiring conductor 8 may be formed by etching the copper foil into a predetermined pattern. Such an example will be described below based on FIGS. 3A to 3C and FIGS. 4D to 4F. In addition, in this example, the same code | symbol is attached | subjected to the part similar to an example of embodiment mentioned above, and the detailed description is abbreviate | omitted.

  First, as shown in FIG. 3A, a double-sided copper-clad plate 3 is prepared. This double-sided copper-clad plate 3 is the same as that described in the example of the embodiment described above.

  Next, as shown in FIG. 3B, the wiring conductors 8 made of copper foil are formed on the upper and lower surfaces of the insulating plate 1 by etching the copper foils 2 on both sides into a predetermined pattern by a known subtractive method. . In this case, the wiring conductor 8 having a fine pattern can be accurately formed by etching only the copper foil 2 having a uniform thickness into a predetermined pattern.

  Next, as shown in FIG.3 (c), the through-hole 4 which penetrates the wiring conductor 8 which consists of copper foil of both surfaces, and the insulating board 1 between them is drilled. The diameter D1 and the drilling method of the through hole 4 are the same as those described in the example of the embodiment described above.

  Next, an electroless copper plating layer (not shown) is deposited on the inner wall of the through hole 4, the surface of the wiring conductor 8, and the surface of the insulating plate 1. The thickness and the deposition method of the electroless copper plating layer are the same as those described in the example of the embodiment described above.

  Next, as shown in FIG. 4 (d), a plating resist layer 5 is formed on the wiring conductors 8 on both sides to which the electroless copper plating layer is applied. The plating resist layer 5 has an opening 6 on the through hole 4. The diameter D2 of the opening 6 is smaller than the diameter D1 of the through hole 4 by about 30 to 50 μm, so that the plating resist layer 5 around the opening 6 protrudes from the through hole 4 by about 15 to 25 μm like a ridge. The composition, thickness, and formation method of the plating resist 5 are the same as those described in the example of the embodiment described above.

  Next, as shown in FIG. 4E, the electrolytic copper plating is applied to the inner wall of the through hole 4 to which the electroless copper plating layer is applied, and the electroless copper plating and the electrolytic copper plating thereon are formed. A through-hole conductor 7 is formed. At this time, it is important that the both ends of the through-hole conductor 7 are deposited so as not to protrude into the opening 6 of the plating resist layer 5 as in the example of the embodiment described above. Specifically, the through-hole conductor 7 is deposited so that the thickness at both ends is about 10 to 20 μm. Thereby, it is possible to prevent a protrusion made of copper plating from being formed on the through hole. In addition, since the periphery of the opening 6 of the plating resist layer 5 protrudes like a ridge over the through hole 4 at both ends of the through hole 4, the flow of the electrolytic copper plating solution is stagnant. Therefore, deposition of electrolytic copper plating is suppressed at both end portions of the through hole 4, and the thickness of both end portions of the through hole conductor 7 is gradually reduced toward the plating resist layer 5 side. Therefore, even if the through hole conductor 7 has a thickness of about 10 to 20 μm that does not protrude into the opening 6 of the plating resist layer 5, the through hole 4 has a thickness of about 15 to 25 μm at the center of the through hole 4. A conductor 7 can be deposited.

  Next, as shown in FIG. 4F, the plating resist layer 5 is peeled and removed. The plating resist layer 5 is peeled in the same manner as described in the example of the embodiment described above.

  Finally, the electroless copper plating layer on the surface of the wiring conductor 8 and the insulating plate 1 is removed by etching to complete a wiring board according to another example of the embodiment of the present invention. In this case, the wiring conductor 8 having a fine pattern can be accurately formed by etching only the copper foil 2 having a uniform thickness into a predetermined pattern. Further, no protrusion made of copper plating is formed on the through hole 4. Therefore, it is possible to normally mount the electronic component when mounting the electronic component. Moreover, even when another insulating layer and a conductor layer are further laminated thereon to form a multilayer wiring board, it becomes possible to normally laminate those other insulating layers and conductor layers. .

DESCRIPTION OF SYMBOLS 1 Insulation board 2 Copper foil 3 Double-sided copper-clad board 4 Through-hole 5 Plating resist layer 6 Plating resist layer opening 7 Through-hole conductor 8 Wiring conductor

Claims (1)

  A step of preparing a double-sided copper-clad plate in which copper foil is attached to both sides of the insulating plate, and a through-hole penetrating the double-sided copper-clad plate and the insulating plate therebetween with a first diameter in the double-sided copper-clad plate A step of perforating, and a plating resist layer having an opening having a second diameter smaller than the first diameter on the through hole and having a periphery of the opening projecting on the through hole. And a step of depositing a through-hole conductor made of copper plating on the inner wall of the through-hole so that both ends of the through-hole conductor do not protrude into the opening of the plating resist layer. A method for manufacturing a wiring board, comprising:

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