Manufacturing method of printed circuit boards

Abstract

A pad wiring section with a width close to the design value is formed. [Solution] A method for manufacturing a printed wiring board, comprising: preparing a core substrate having copper foil on both surfaces; forming through holes in the core substrate; forming a through-hole plating layer on the surface of the copper foil and inside the through holes; filling the through holes with resin; forming a resist layer on the surface of the copper foil and on the surface of the filled resin; forming an opening on the through holes in the resist layer; and forming a partial cover plating layer in the opening, further comprising: forming a plating film on the partial cover plating layer; removing the resist layer; performing etching using the plating film as a mask to remove the through-hole plating layer and copper foil other than the mask; and removing the plating film used as a mask.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a printed wiring board in which a conductor circuit of a core substrate is formed using an etching mask.

Background Art

[0002] Conventionally, when forming a partial cover plating layer on a through-hole conductor using an etching mask, a technique for solving the problem that the partial cover plating layer cannot be formed to the same dimensions as the design dimensions due to etching shift is known, for example, from Patent Document 1. FIGS. 2(a) to 2(c) are diagrams for explaining an embodiment of a conventional method for manufacturing a printed wiring board disclosed in Patent Document 1.

[0003] In the example shown in FIGS. 2(a) to 2(c), 51 is a core substrate, 52 is a copper foil formed on both surfaces of the core substrate 51, 53 is a through-hole formed in the core substrate 51, 54 is a through-hole plating layer formed inside the through-hole 53 and on the surface of the copper foil 52, 54 is a resin filled inside the through-hole 53, and 55 is a partial cover plating layer formed on the through-hole plating layer 54.

[0004] In the above-described conventional method for manufacturing a printed wiring board, first, as shown in FIG. 2(a), a first resist layer 61 is formed on both surfaces of the core substrate 51, an opening 61a is formed on the through-hole 53 of the first resist layer 61, and a partial cover plating layer 55 is formed in the formed opening 61a. Next, as shown in FIG. 2(b), after removing the first resist layer 61, a patterned second resist layer 62 is formed on the partial cover plating layer 55 and on the through-hole plating layer 54. Thereafter, by etching using the second resist layer 62 as a mask, a printed wiring board having pads 71 and wiring patterns 72 is formed as shown in FIG. 2(c).

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2008-282842 [Overview of the project] [Problems that the invention aims to solve]

[0006] In the conventional printed circuit board manufacturing method shown in Figures 2(a) to (c), a second resist layer 62 is formed on the partial cover plating layer 55 so as to cover its upper surface, as shown in Figure 2(b). In this process, it was almost impossible to align the position of the partial cover plating layer 55 with the position of the second resist layer 62. Therefore, in the conventional printed circuit board manufacturing method described above, the width of the partial cover plating layer 55 after removing the conductor exposed from the second resist layer 62 sometimes deviated significantly from the design value. [Means for solving the problem]

[0007] The present invention relates to a method for manufacturing a printed circuit board, comprising: preparing a core substrate having copper foil on both surfaces; forming through holes in the core substrate; forming a through-hole plating layer on the surface of the copper foil and inside the through holes; filling the through holes with resin; forming a resist layer on the surface of the copper foil and on the surface of the filled resin; forming an opening on the through holes in the resist layer; and forming a partial cover plating layer in the opening, wherein the method further comprises: forming a plating film on the partial cover plating layer; removing the resist layer; performing etching using the plating film as a mask to remove the through-hole plating layer and copper foil other than the mask; and removing the plating film used as a mask. [Brief explanation of the drawing]

[0008] [Figure 1A] This figure illustrates one embodiment of the method for manufacturing a printed circuit board according to the present invention. [Figure 1B] This figure illustrates one embodiment of the method for manufacturing a printed circuit board according to the present invention. [Figure 1C] This figure illustrates one embodiment of the method for manufacturing a printed circuit board according to the present invention. [Figure 1D] This figure illustrates one embodiment of the method for manufacturing a printed circuit board according to the present invention. [Figure 1E] This figure illustrates one embodiment of the method for manufacturing a printed circuit board according to the present invention. [Figure 1F] This figure illustrates one embodiment of the method for manufacturing a printed circuit board according to the present invention. [Figure 1G] This figure illustrates one embodiment of the method for manufacturing a printed circuit board according to the present invention. [Figure 1H] This figure illustrates one embodiment of the method for manufacturing a printed circuit board according to the present invention. [Figure 1I] This figure illustrates one embodiment of the method for manufacturing a printed circuit board according to the present invention. [Figure 1J] This figure illustrates one embodiment of the method for manufacturing a printed circuit board according to the present invention. [Figure 1K] This figure illustrates one embodiment of the method for manufacturing a printed circuit board according to the present invention. [Figure 2] (a) to (c) are diagrams illustrating one embodiment of a conventional method for manufacturing printed circuit boards. [Modes for carrying out the invention]

[0009] Hereinafter, one embodiment of the method for manufacturing a printed circuit board according to the present invention will be described with reference to the drawings. In the example shown in Figures 1A to 1K, the dimensions in the width and height directions of each component are described using dimensions different from the actual dimensions in order to better understand the features of the present invention.

[0010] <Regarding one embodiment of the method for manufacturing a printed circuit board according to the present invention> Figures 1A to 1K are diagrams illustrating one embodiment of the method for manufacturing a printed circuit board according to the present invention. Hereinafter, one embodiment of the method for manufacturing a printed circuit board according to the present invention will be described with reference to Figures 1A to 1K.

[0011] First, as shown in Figure 1A, a core substrate 2 having copper foil 1 on both surfaces is prepared. A commercially available copper-clad laminate can be used as the core substrate 2. Next, as shown in Figure 1B, through-holes 3 are formed in the core substrate 2. Conventional methods known as drilling or laser processing can be used to form the through-holes 3. Next, as shown in Figure 1C, a through-hole plating layer 4 is formed on the surface of the copper foil 1 and inside the through-holes 3. Next, as shown in Figure 1D, resin 5 is filled into the through-holes 3. Next, as shown in Figure 1E, a resist layer 6 is formed on the surface of the copper foil 1 and on the surface of the filled resin 5. Next, as shown in Figure 1F, an opening 6a is formed on the through-holes 3 in the resist layer 6. Next, as shown in Figure 1G, a partial cover plating layer 7 is formed in the opening 6a. Each of the above steps in Figures 1A to 1G is the same as the conventional method for manufacturing printed circuit boards disclosed in, for example, Patent Document 1.

[0012] The key feature of the printed circuit board manufacturing method of the present invention lies in the steps shown in Figures 1H to 1K after the above steps. Specifically, after forming the partial cover plating layer 7 in Figure 1G, first, as shown in Figure 1H, a plating film 8 is formed on the partial cover plating layer 7. Next, as shown in Figure 1I, the resist layer 6 is removed. Then, as shown in Figure 1J, etching is performed using the plating film 8 as a mask to remove the through-hole plating layer 4 and copper foil 1 other than the partial cover plating layer 7 covered by the plating film 8 acting as a mask. Finally, as shown in Figure 1K, the pad wiring portion 11 can be formed by removing the plating film 8.

[0013] Here, since the plating film 8 needs to function as a resist layer, it is preferable to use Sn or Sn / Pb. Furthermore, since each step shown in Figures 1A to 1K can be carried out using any of the conventionally known methods, a detailed explanation is omitted here.

[0014] In the above-described process, the description focused on forming the pad wiring portion 11 on the through-hole 3. However, wiring patterns other than the pad wiring portion 11 can also be formed using the above process. Specifically, in the process of FIG. 1F, another opening is formed at the position where the wiring pattern is formed together with the formation of the opening 6a. In the process of FIG. 1G, a plating layer is also provided in the other opening. Then, by performing the processes of FIGS. 1H to 1K, a wiring pattern can be formed at the position of the other opening in the same manner as the pad wiring portion 11.

[0015] According to the method for manufacturing a printed wiring board of the present invention described above, as shown in FIG. 1H, the resist for partial cover plating and the resist for etching mask are the same. That is, the partial cover plating layer 7 and the plating film 8 can be formed in the same opening 6a, and the position of the partial cover plating layer 7 and the position of the plating film 8 as the etching mask coincide, so that the pad wiring portion 11 having a width close to the design value can be formed.

Explanation of Reference Numerals

[0016] 1 Copper foil 2 Core substrate 3 Through-hole 4 Through-hole plating layer 5 Resin 6 Resist layer 6a Opening 7 Partial cover plating layer 8 Plating film 11 Pad wiring portion

Claims

1. A method for manufacturing a printed circuit board, comprising: preparing a core substrate having copper foil on both surfaces; forming through holes in the core substrate; forming a through-hole plating layer on the surface of the copper foil and inside the through holes; filling the through holes with resin; forming a resist layer on the surface of the copper foil and on the surface of the filled resin; forming an opening on the through holes in the resist layer; and forming a partial cover plating layer in the opening, Forming a plating film on the aforementioned partial cover plating layer, Removing the aforementioned resist layer, Etching is performed using the aforementioned plating film as a mask to remove the through-hole plating layer and copper foil other than the mask, Removing the aforementioned plating film used as a mask, Includes.

2. The method for manufacturing a printed wiring board according to claim 1, wherein the plating film is formed of Sn or Sn / Pb.

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