JPS6140088A - Method of producing printed circuit 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] (Industrial application field) The present invention relates to a method of manufacturing a printed wiring board.

(Prior Art) Conventionally, when manufacturing a printed wiring board by forming a circuit by electroless plating such as the CC-4 method, an adhesive layer containing a plating catalyst is placed on the surface of an insulating substrate in advance. In this case, in the case where through holes are formed in the insulating substrate, after the through holes are formed and before electroless plating, a process is performed in which a plating catalyst is attached to the through balls.

By the way, in order to improve the adhesion between the adhesive layer and the plated circuit formed by electroless plating, the adhesive layer is usually roughened after a plating catalyst is attached to the through holes. The adhesive layer is roughened by dipping the insulating substrate in a roughening solution such as a borofluoric acid solution or an anhydrous chromic acid/sulfuric acid solution. Most of the catalyst is washed away. Therefore, even if electroless plating is performed later, it takes n) for plating to precipitate in the through holes.
However, the deposited plating film is thin and has low peel strength. Therefore, when solder plating is applied to lands using solder dipping, etc., or when electronic components are connected, gas in the insulating substrate peels off the plating film of the through holes and is released, filling the through holes and causing the solder to melt. It is pushed out from inside the through hole and only covers the entrance surface! (hereinafter referred to as a blowhole). In such a state, there are disadvantages in that connection failures of electronic components are likely to occur and adhesive strength is also likely to decrease.

(Objective) The purpose of the present invention is to improve the above-mentioned drawbacks, and provide a highly reliable method for manufacturing printed wiring boards that facilitates plating deposition in through-holes, shortens manufacturing time, and prevents blowholes. That is.

(Means for Solving the Problems) In order to achieve the above two objects, the present invention provides through-holes in a cape edge substrate whose surface is provided with an adhesive layer containing a plating catalyst, and forms predetermined holes by electroless plating. Provided is a method for manufacturing a printed wiring board forming a circuit, characterized in that after providing a through hole, a resin layer containing a plating catalyst is provided on the inner peripheral surface of the through hole. So, there it is.

(Function) According to the present invention, after providing the through hole,
Since the inner circumferential surface of this through hole is stepped with a resin layer containing a plating catalyst made of palladium chloride, tin chloride, etc., even if roughening treatment is performed afterwards, the inner circumferential surface of the through hole A sufficiently thick plating is deposited in a short time.

In addition, even when solder plating is performed, the resin layer is in close contact with the inner circumferential surface of the through hole, which prevents the gas in the insulating substrate from being released from the inner circumferential surface of the through hole. , the occurrence of blowholes can be prevented.

(Example) Embodiments of the present invention will be described below based on the drawings.

First, as shown in FIG. 1, an adhesive containing a plating catalyst such as palladium is applied to an insulating substrate 1 made of a paper-phenol resin base material or a paper-epoxy resin base material to form an adhesive layer 2. Next, as shown in FIG. 2, the insulating substrate 1 with the adhesive layer 2 formed thereon is bunched to form a predetermined through hole 3. After forming the through-holes 3, the surface of the insulating substrate 1 is leveled and washed with high-pressure water to remove plugging debris caused by punching.

Next, the insulating substrate 1 after washing with water is immersed in an emulsion of a thermosetting resin such as an epoxy resin containing a plating catalyst of palladium chloride and tin chloride, and as shown in FIG. A thermosetting resin 111'4 having a thickness of about 2 to 10 μm is provided on the inner circumferential surface of 3.

In addition to epoxy resin, thermosetting resins include urea □
□ Tan resin □ Polynisder resin is used, and especially in the case of a phenol resin-based or epoxy resin-based insulating substrate, epoxy resin is preferable because it has good adhesion to the substrate. Furthermore, as the curing agent, amine-based curing agents are preferable because they provide a stable solution.

After the insulating substrate 1 is immersed in the emulsion, it is taken out and one part of the emulsion on the surface is removed by a squeezing roller. After removing the emulsion, plating relimet ink is applied in a predetermined pattern and dried to form a plating resist layer 5 as shown in FIG. 4, and at the same time, the resin 14 is cured.

After providing the plating resist layer 5, the insulating substrate 1 is immersed in a roughening solution consisting of a borofluoric acid solution or an anhydrous chromic acid/sulfuric acid solution to roughen the adhesive layer 2, as shown in FIG. . . After roughening the adhesive layer 2, the insulating substrate 1 is immersed in an acupuncture electrolytic copper plating solution to deposit plating in a predetermined pattern to form a circuit 6, as shown in FIG. After forming the circuit 6, the insulating substrate 1 is processed and manufactured using a conventional method.

In addition, the palladium concentration contained in the thermosetting resin is preferably 0.005 to 0.5 parts by weight per 100 parts by weight of the solid content in the resin, and if it is less than 0.005 parts by weight, the precipitation effect of □ plating will be reduced. If the amount is too low, and if it exceeds 0.5 part by weight, it becomes expensive and is not suitable for practical use.

Furthermore, stannous chloride has the function of removing chlorine from palladium chloride to form palladium which is a plating catalyst, but it is preferably added in an amount of 5 to 40 times the weight of palladium chloride. If it is less than 5 times, the number of palladium generators is small (and if it is more than 40 times, the insulation resistance of the resin layer becomes too low, which is not preferable).

Furthermore, the resin emulsion has a resin concentration of 0.3 to 5.
% by weight is preferred; if it is less than 0.3% by weight, the formed resin layer will be too thin and the effect of preventing blowholes will be low;
If the amount is more than 5% by weight, the through holes are likely to be clogged and removal work is required, making the work difficult and tedious.

Next, the plating adhesion within the through hole, blowhole occurrence rate, and through hole reliability were measured for the present invention and the conventional example, and the results shown in the table were obtained. The adhesion of plating inside the through-hole is determined by the time it takes for the plating to deposit on the entire inner wall of the through-hole, the blowhole occurrence rate is determined by setting the soldering conditions at 245°C for 5 seconds, and the reliability of the through-hole is determined by MIL-1070 (- 65°C, 30 minutes to 125°C.

The number of cycles is defined as the number of cycles at which the resistance value increases by 10% in a thermal shock test with a 30-minute cycle.

The table manufacturing conditions were as follows in Example 1): a) Insulating substrate: Paper-epoxy resin laminate coated with a plating catalyst-containing adhesive (HA-04, manufactured by Hitachi Chemical Co., Ltd.) (A manufactured by Hitachi Chemical Co., Ltd.) CL-E-144), b〉■Mulsion: 2-I-poxy resin emulsion (80 parts by weight of curing agent EB-1 was added to 100 parts by weight of solid content of Epolsion EA-1 manufactured by Kanebo NSC, and this 180 parts by weight C) Plating resist treatment: Metsugi resist ink (Hitachi Chemical) =1) was screen printed on HGM-028 manufactured by Kogyo Co., Ltd. and heated for 30 minutes at a temperature of 160°C, d) Roughening solution: a solution consisting of borofluoric acid and chromic anhydride, e) Plating treatment: Electroless plating process forms a 30μ thick copper layer using electroless plating. In addition, in Example 2), 10% of tinnous chloride was added to 1 part of palladium chloride as 1 mulsion in Example 1).
In Example 3), the concentration of palladium chloride was set at 30 parts by weight per 100 parts of resin content in Example 1>, and in Example 4), the concentration of palladium chloride in Example 1) was set at 30 parts by weight. The palladium concentration was set to 3 parts by weight per 100 parts by weight of the resin content, and in Example 5), the substrate in Example 1) was replaced with an insulating substrate containing no plating catalyst (LE-44 manufactured by Hitachi Chemical Co., Ltd.).
In the conventional example, the emulsion filling step in Example 1 was omitted and only palladium was deposited instead.

As is clear from the table, according to the present invention, the plating adhesion inside the through hole is reduced by about 67% or more compared to the conventional example.
The plating deposition rate is faster and the blowhole occurrence rate is 40%
% or less, and the reliability of the through-holes is 1.
This is an improvement of more than 5 times, and all three characteristics are significantly improved.

As described above, according to the present invention, in the through hole,
Since a resin layer containing a mating catalyst is provided and the plating is deposited on this resin base, the plating can be deposited quickly on the solid surface inside the through hole, reducing manufacturing time. A method for manufacturing a seaweed printed wiring board is obtained.

[Brief explanation of the drawing]

Figures 1 to 6 show the manufacturing process of an embodiment of the present invention. Figure 1 is a cross-section of an insulating substrate provided with eight adhesive layers, and Figure 2 is a cross-section of an insulating substrate with through holes formed. Figure 3 is a cross-sectional view of an insulating substrate with a resin layer provided thereon, Figure 4 is a cross-sectional view of an insulating substrate with a plating resist layer provided, and Figure 5 is a cross-sectional view of an insulating substrate with a roughened adhesive layer. , FIG. 6 shows a cross-sectional view of an insulating substrate on which a circuit is formed. DESCRIPTION OF SYMBOLS 1... Insulating substrate, 2... Adhesive layer, 3... Through hole, 4... Resin layer, 5... Plating resist layer, 6... Circuit.

Claims (1)

[Claims] (1) In a method for manufacturing a printed wiring board in which through holes are formed in an insulating substrate whose surface is provided with an adhesive layer containing a plating catalyst, and a predetermined circuit is formed by electroless plating, after the through holes are formed, the A method for manufacturing a printed wiring board, comprising providing a resin layer containing a plating catalyst on the inner peripheral surface of a through hole.