JPS62156898A - Manufacture of through-hole printed wiring board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method of manufacturing a through-hole printed wiring board.

[Technical background of the invention and its problems] In recent years, with the progress of higher density and higher quality of electronic and electrical equipment, through-hole printed wiring boards, in which circuit patterns on both sides are electrically connected by through-holes, have been developed. Demand is increasing.

Generally, such through-hole printed wiring boards are manufactured by the etched wheel method (subtractive method) described below.

In this method, electroless copper plating and electrolytic copper plating are sequentially applied to the surface of a copper-clad laminate that has been drilled, including the inner walls of the holes, and then coated with etching resist. After patterning, the through holes and solder pads are coated. Unnecessary parts except the parts and circuit patterns are dissolved and removed by etching.
The etching resist is roughly removed, and solder resist is coated thereon except for the through-holes and solder pads.

However, in this method, when forming through holes, solder pads, and circuit patterns, a thick copper layer consisting of copper foil, electroless copper plating, and electrolytic copper plating layer is etched. The drawbacks are that it tends to cause hairs, is time consuming, and wastes a large amount of copper material.

In order to overcome these drawbacks of the subtractive method, additive methods have recently come into use.゛The additive method is a method in which circuit patterns and through-holes are formed by electroless copper plating after drilling holes in a substrate made of a special material.The copper layer is formed only in the necessary areas, so resources are saved. Although this method saves money, since the through holes, solder pads, and circuit patterns are formed by electroless copper plating, there are problems in that it is time consuming and the reliability of the through holes is poor.

Furthermore, these methods have the problem of poor workability, as they must be cleaned by polishing or the like in order to improve the adhesion of through holes, solder pads, and circuit patterns when applying solder resist. Ta.

[Purpose of the Invention] The present invention has been made to solve these problems, and uses equipment and materials for manufacturing printed wiring boards by the normal subtractive method, and only the through-holes and solder pads. The purpose of the present invention is to provide a method for manufacturing a printed wiring board with high through-hole reliability by electrolytic copper plating with good workability.

[Summary of the Invention] That is, the present invention comprises: (a) a step of applying electroless copper plating to the surface including the inner wall of the hole of a double-sided copper-clad laminate that has been subjected to perforation; and (b) this double-sided copper-clad laminate. (c) coating both sides of the double-sided copper clad laminate with an etching resist having a solder resist function and removing this etching resist leaving the circuit pattern area; (d) step of sequentially applying electrolytic copper plating and solder plating; (e) step of removing the plating resist and etching the copper foil to form a circuit pattern; By performing the process of covering the solder resist except for the holes and solder pads, electricity is applied only to the through-holes and solder pads using equipment and materials for manufacturing printed wiring boards using the normal subtractive method. This is a copper-plated printed wiring board with high through-hole reliability that is easy to work with.

An example of the etching resist that functions as a solder resist used in the present invention is DPR-105 manufactured by Asahi Kaken Co., Ltd. This solder resist is applied onto the double-sided copper-clad laminate by screen printing.

Further, as an etching resist to be coated thereon except for through-hole portions, for example, T-3615 manufactured by DuPont, USA, which is an alkali-soluble dry film, can be used. This dry film can be easily peeled off and removed by treatment with an alkaline aqueous solution after electrolytic copper plating and solder plating are completed on through-hole portions and the like.

Roughly speaking, in the present invention, after forming a conductive circuit pattern by etching unnecessary parts, a solder mask is formed on the entire surface of the board excluding through-holes and solder pads by using a method such as the above-mentioned DPR-105. A suitable solder resist is used.

In the present invention, a solder resist film is formed roughly on the etching resist that functions as a solder resist and is coated on the conductive circuit pattern.

[Embodiments of the invention] Embodiments of the present invention will be described below with reference to the drawings.

In each of the following figures, (a) is a perspective view, and (b) is a sectional view.

In this embodiment, as shown in the figure, a through hole 3 of a predetermined diameter is first formed by drilling or punching in an ordinary copper-clad laminate 2 on which copper foil 1.1 with a thickness of 35 μm is laminated on both sides. Then, an electroless copper plating layer 4 is uniformly formed on the inner wall of the through hole 3 and the copper layer 1 (FIG. 2). After pretreatment using conventional methods,
On the electroless steel plating layer 4, an etching resist layer 5 having a solder resist function is formed using, for example, DPR-105.
is formed, and a circuit pattern C is formed by etching (FIG. 3).

Thereafter, a plating resist dry film (T-3615) 6 is pasted on the etching resist layer 5, and only the through-holes and solder pads are exposed by patterning (FIG. 4).

Next, copper plating and solder plating are sequentially performed by electroplating, and an electrolytic copper plating layer 7 and a solder plating layer 8 are sequentially formed on the through hole portion and the solder pad portion (FIG. 5).

After the electroplating, the plating resist dry film 6 is peeled off by being immersed in an alkaline aqueous solution, and the copper foil and electroless steel plating layer in the non-circuit pattern area are dissolved and removed by alkali etching.

Thereafter, a solder resist layer 9 is formed using DPR-105 on the entire surface except for the through-hole portions and solder pad portions where the copper plating layer 7 and the solder plating layer 8 are formed, thereby completing the through-hole printed wiring board (No. Figure 6).

In the manufacturing method of this embodiment, the conductor circuit pattern is formed by etching only the copper foil 1 and the electroless copper plating layer 4 in the non-circuit pattern area in the circuit pattern area.
Uniform etching can be performed in a short time.

In addition, since the other parts are covered with plating resist dry film T-3615 and electroplated with copper and solder only on the through holes and solder pads, the advantage is that the amount of plating can be controlled. be.

Roughly speaking, DPR-105 is finally applied on the DPR-105 printed layer 5 on the conductor circuit pattern to form a solder mask, so the surface polishing and other treatments that are normally required are carried out before this application. Can be omitted.

[Effects of the Invention] As explained above, according to the method of the present invention, the circuit pattern is formed by etching the copper foil of the copper-clad laminate, and the through holes etc. are formed by electrolytic copper plating. , a printed wiring board with high through-hole reliability can be manufactured with good workability using ordinary materials and manufacturing equipment.

Further, the design information of the circuit pattern part and the information of the through-hole part etc. can be managed separately, and furthermore, there is an advantage that pre-processing when finally forming the solder mask can be omitted.

[Brief explanation of drawings]

1 to 6 are sectional views of essential parts of a hanging board for explaining the procedure of an embodiment of the present invention. 1... Copper foil 2... Copper clad laminate 3... Through hole 4... Electroless Copper plating layer 5...
... Etching resist layer 6 ... Plating resist dry film 7 ... Electrolytic copper plating layer 8 ... Solder plating layer 9 ...・・・・・・Solder resist layer applicant
Toshiba Corporation Representative Patent Attorney Satoshi Suyama - (a) Figure 1 (a') Figure 2 (b) Figure 3 Figure 4

Claims (2)

[Claims] (1) (a) A step of applying electroless copper plating to the surface, including the inner wall of the hole, of a double-sided copper-clad laminate that has been subjected to perforation, and (b) A process of applying a solder resist function to both sides of this double-sided copper-clad laminate. (c) covering the double-sided copper-clad laminate with a plating resist except for the through-holes and solder pads; , (d) a step of sequentially applying electrolytic copper plating and solder plating; (e) a step of removing the plating resist and etching the copper foil to form a circuit pattern; and (f) a through-hole portion and a solder pad portion. A method for manufacturing a through-hole printed wiring board, comprising the steps of: excluding the above steps and covering the solder resist with the solder resist. (2) The method for manufacturing a through-hole printed wiring board according to claim 1, wherein the plating resist is a dry film.