JPH01313996A - Manufacture of printed wiring board - Google Patents

Abstract

PURPOSE:To improve the reliability of electric conduction of a through hole by a method wherein an electroplated copper layer is formed on a land and the inner wall surface of a through hole, by utilizing selective etching property of copper and nickel. CONSTITUTION:A chemical nickel plated layer 7 as a substratum is formed on the whole part containing the inner wall of a through hole 4 and a land 6. By using said substratum 7, a dense electroplated copper layer 9 is formed so as to cover the inner wall surface of the through hole 4 and a land 6. As a result, the formed copper layer 9 possesses density, and maintains almost uniform quality. The formed electroplated copper layer 9 is further coated with a nickel plated layer 7'. In this state, the layer 9 is etched and eliminated together with the chemical nickel layer 7 covering a circuit part, so that the electroplated copper layer 9 is not damaged. Thereby the reliability of electric conduction of through hole is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a method for manufacturing a printed wiring board, and more particularly to an improvement in a method for manufacturing a printed wiring board by a part-rediative method.

(Prior Art) The following part-reactive method is known as a means for relatively easily manufacturing a double-sided printed wiring board. That is, a double-sided copper-clad plate is first prepared, and through-holes are formed by punching or drilling at predetermined positions on the copper-clad plate, and then the through-holes are subjected to a pre-plating treatment. Next, a desired circuit pattern is masked on the copper surface of the copper clad plate with an etching resist, and the exposed copper is removed by selective etching, and then the etching resist is removed to obtain a predetermined circuit pattern. After that, a plating resist layer is coated on surfaces other than the land and the inner wall surface of the through-hole hole of the formed circuit pattern, and a conductive layer is formed on the inner wall surface of the through-hole hole by selectively applying chemical copper plating. The company manufactures double-sided printed wiring boards.

(Problems to be Solved by the Invention) However, the following disadvantages are often observed in double-sided printed wiring boards manufactured by the above-mentioned part-additive method. That is, the so-called through-hole conductive layer of the double-sided printed wiring board manufactured by the above method is not always formed uniformly, and the reliability of through-hole conduction cannot be said to be sufficient. In other words, the chemical copper plating solution used to form the through-hole conductive layer deteriorates over time or changes its composition, which tends to cause variations in the formed plating layer, which reduces the reliability of through-hole conduction. It is understood that there is.

[Structure of the Invention] (Means for Solving the Problems) The present invention involves forming an electrolytic copper plating layer on the inner wall surfaces of lands and through-holes by utilizing the selective etching properties of copper and nickel in the above-mentioned part additive method. The main point is In other words, a chemical nickel plating layer is first formed on the entire surface including the inner wall surface of the through-hole hole and the land, then electrolytic copper plating is selectively applied to the inner wall surface of the through-hole hole and the land, and then the layer is further covered with a nickel plating layer. , chemical nickel plating layer on the circuit pattern,
The nickel plating layer covering the inner wall surface of the through-hole and the land is selectively etched away to provide a through-hole conductive layer with high precision and high density.

(Function) According to the present invention, a chemical nickel plating layer is formed as a base on the entire surface including the inner wall surface of the through hole and the land, and this base layer is used to coat the inner wall surface of the through hole and the land with electroplating. Coat with a copper layer. Therefore, the copper layer formed as a coating always maintains substantially -like properties due to the denseness (high density). Furthermore, the formed electrolytic copper plating layer is covered with a nickel plating layer, which is removed by etching together with the chemical nickel plating layer covering the circuit pattern. In other words, in the etching removal of the exposed chemical nickel plating layer covering the circuit pattern, etc., the nickel plating layer covering the through-hole inner wall surface and land is first selectively removed. Since it is etched, the electrolytic copper plating layer is not damaged.

(Example) The present invention will now be described in detail with reference to the accompanying drawings.

The figures are cross-sectional views showing the state of the printed wiring board in each step of the method of the present invention. First, a double-sided copper-clad board 3 was prepared by laminating copper foil 2 on both sides of an insulating substrate 1 (Fig. 1). . Next, the copper clad plate 3 is drilled, for example, at a predetermined position to form the required through hole 4 (Fig. 2), while masking with an etching resist 5 (Fig. 3), and selective etching is performed. and create the required circuit pattern (
(including land 6) was formed. After that, the masking resist 6 is removed (Fig. 4), and chemical nickel plating is applied to the entire surface including the inner wall surface of the through hole to form a nickel plating layer 7.
was formed (Fig. 5). In this way, a plating resist layer 8 is coated on the inner wall surface of the through-hole hole 4 of the insulating substrate 1 on which the chemical nickel plating layer 7 has been formed over the entire surface, and on other surfaces excluding the land 6 (FIG. 6). Electrolytic copper plating treatment was performed in this state. That is, electrolytic copper plating was performed on the insulating substrate 1, and an electrolytic copper plating layer 9 was selectively formed on the exposed inner wall surfaces of the through holes 4 and the surfaces of the lands 6. Next, electroplating or chemical nickel plating is performed with the plating resist layer 8 still attached to form a nickel plating layer 7 on the electrolytic copper plating layer 9 formed above (FIG. 7), and then the plating resist layer 8 is coated with the nickel plating layer 7. was removed (Figure 8). In this way, the outermost layer of the insulating substrate 1 is completely covered with the nickel plating layer 7,7' as shown in FIG.
．． 7' etching removal treatment was performed. That is, the nickel plating layer 7.7' forming the surface layer of the insulating substrate 1
2. After selectively etching and removing with Tsuchinda solution, a double-layered conductive layer consisting of a chemical nickel plating layer 7 and an electrolytic copper plating layer 9 was formed on the inner wall surface of the through-hole hole 4 and the land 6. A wiring board was obtained (Figure 9).

[Effects of the Invention] As can be seen from the above embodiments, according to the method of the present invention, the main circuit pattern formed on the main surface of the insulating substrate has a relatively -
Because it is made of copper foil with a uniform thickness, it can be formed with high precision.

Furthermore, since the conductive layer on the inner wall surface of the through-hole, including the land, is formed by electrolytic copper plating, it is dense and has no variation in the amount of coating (uniform thickness), and always functions as a highly reliable conductive layer. In other words, a nickel plating layer is pre-coated on the electrolytic copper plating layer formed on the inner wall surface of the through hole, and selective etching of the chemical nickel plating layer formed on other surfaces such as the main circuit pattern surface on the board is performed. Because of this, the copper foil pattern and the electrolytic copper plating layer are prevented from being damaged and the required thickness can be easily maintained. Moreover, since the electrolytic copper plating layer is formed only on the inner wall surface of the through-hole and the land surface, it is advantageous in terms of cost, and in combination with the high reliability of the printed wiring board, it can be said that this manufacturing method provides practical advantages. .

[Brief explanation of the drawing]

FIGS. 1 to 9 are cross-sectional views for explaining the method of manufacturing a printed wiring board according to the present invention, and showing aspects of the printed wiring board in each step. 1...Insulating board 2...Copper foil 3...Double-sided copper clad plate 4...Through hole Hole 5...Etching resist 6...
... Land 7 ... Chemical nickel plating layer 8 ...
・・・・・・Plating resist layer 9・・・・・・・・・Electrolytic copper plating layer

Claims (1)

[Claims] a step of providing through-hole holes at predetermined positions on a double-sided copper-clad plate; a step of masking the copper surface of the double-sided copper-clad plate with the through-hole holes with an etching resist and performing selective etching to form a desired circuit pattern; a step of removing the masking resist and applying chemical nickel plating to the entire surface including the inner wall surface of the through-hole hole to form a nickel plating layer; a step of covering the surface other than the inner wall surface of the through-hole hole and the land with a plating resist layer; After coating the plating resist layer, selectively forming an electrolytic copper plating layer on the exposed inner wall surfaces and land surfaces of the through holes; forming a nickel plating layer on the electrolytic copper plating layer; A method for manufacturing a printed wiring board, comprising the steps of removing a plating resist layer and etching away an exposed nickel plating layer.