JPH0248155B2 - INSATSUHAISENBANNOSEIZOHOHO - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for manufacturing a printed wiring board using an additive method. (Prior art) Conventionally, when manufacturing a printed wiring board by forming a circuit by electroless plating using an additive method such as the CC-4 method, an adhesive layer containing a plating catalyst is applied on the surface of an insulating substrate in advance. has been established. In this case, if the insulating substrate has holes for through holes, after the holes are formed and before electroless plating, a plating catalyst is applied to the holes. ing. (Problem to be Solved by the Invention) By the way, in order to improve the adhesion between the adhesive layer and the plating circuit formed by electroless plating, after the plating catalyst is attached to the holes, the adhesive is The layer is roughened. 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 will be washed away. Therefore, even if an electroless plating treatment is performed later, it takes time for the plating to precipitate at the holes, and the deposited plating film is thin and has a low peel strength. Therefore, when soldering the hole with solder dip or connecting electronic components, etc., the dipping film provided on the inner circumferential surface of the hole is partially thin, and the gas inside the insulating substrate can leak onto the hole wall. The solder film is peeled off and the hole is filled with solder, and the solder is pushed out from inside the hole and covers only the surface of the entrance (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. (Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides a method for applying a predetermined method by electroless plating to an insulating substrate having holes for through holes and coated with a plating catalyst-containing adhesive. A method for manufacturing a printed wiring board on which a circuit can be formed includes a step of immersing an insulating substrate in a thermosetting resin and applying a thermosetting resin containing a plating catalyst to the hole wall surface, and removing an emulsion on the surface after this step. removed 5
A process of heating the thermosetting resin attached to the hole wall with hot air at a wind speed of m/sec or less, a process of attaching a plating catalyst after heating, and a process of forming an adhesive layer with a roughening liquid after forming a plating resist layer. Provided is a method for manufacturing a printed wiring board, which includes a step of roughening the printed wiring board. (Function) That is, in the present invention, a thermosetting resin layer containing a plating catalyst is previously provided on the wall surface of a through hole provided in an insulating substrate, and this resin is used to semi-cure or harden the layer. Since hot air is used at a speed that does not remove the thermosetting resin, the thermosetting resin can be kept evenly adhered to the hole walls. Therefore, even if the insulating substrate is subsequently immersed in a roughening solution, the catalyst plated on the pore walls is sufficiently dispersed and will not be removed. Plating precipitates in a short period of time, forming a plating layer. Moreover, since the thermosetting resin layer can prevent the gas in the insulating substrate from being released through the hole walls, it is possible to prevent defects such as blowholes when performing solder plating, etc., and prevent plating on the hole wall surfaces. The precipitation rate can be accelerated. (Examples) Hereinafter, the present invention will be described based on Examples. First, as shown in FIG. 1, an insulating substrate 1 made of a paper-phenol resin base material or a paper-epoxy resin base material is prepared.
An adhesive containing a plating catalyst such as palladium is applied to the adhesive layer 2 to form an adhesive layer 2. Next, as shown in FIG. 2, holes 3 for predetermined through holes are formed by punching the insulating substrate 1 on which the adhesive layer 2 is formed. After forming the holes 3, the surface of the insulating substrate 1 is leveled and washed with high-pressure water to remove substrate debris caused by punching.
The insulating substrate 1 after washing with water is immersed in an emulsion of thermosetting resin containing a plating catalyst, and as shown in FIG. will be established. As the thermosetting resin, epoxy resin, urethane resin, polyester resin, etc. are used, but when the insulating substrate 1 is made of phenol resin or epoxy resin, epoxy resin is preferred because of its good adhesion to the substrate. Furthermore, as the curing agent, an amine type curing agent is preferable since a stable emulsion can be obtained. The solid content concentration in the emulsion is particularly preferably in the range of 0.3 to 5 wt%. i.e. 0.3wt%
If the concentration is less than 5% by weight, the effect as a curing agent will be reduced and the resin will be difficult to cure, and if the concentration is more than 5wt%, the resin may be coated so as to close the pores, making removal work necessary, which is undesirable for work. The plating catalyst is preferably a palladium-based catalyst used in combination with a palladium compound or a tin compound, and is preferably added in an amount of 0.005 to 0.5 parts by weight per 100 parts by weight of the resin.If it is less than 0.005 parts by weight, the catalytic effect is low; 0.5
If the amount exceeds parts by weight, the price and manufacturing costs will increase. After the insulating substrate 1 is immersed in the emulsion, the emulsion on the surface is removed using a squeezing roller or a buff. After removing the surface emulsion,
Air that is forcibly heated by an electric fan, etc. is
The thermosetting resin adhering to the hole wall is heated and dried by hot air of less than sec to a hardened state. After the thermosetting resin layer 4 is cured, a plating resist ink is applied to the surface of the adhesive layer 2 in a predetermined pattern and dried to form a plating resist layer 5 as shown in FIG.
After forming 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, and then the adhesive layer 2 is formed as shown in FIG.
coarsen. After roughening the adhesive layer 2, the insulating substrate 1 is immersed in an electroless plating solution to deposit plating in a predetermined pattern to form a circuit 6 as shown in FIG.
form. After forming the circuit 6, the insulating substrate 1 is processed in a conventional manner to produce a printed wiring board. Next, the plating adhesion inside the through-hole, the through-hole reliability, and the blowhole occurrence rate were measured for the present invention and the conventional example, and the results shown in the table were obtained.

[Table] The adhesion of plating inside the hole for through holes is the time until plating is deposited on the entire inner wall of the hole, and the through hole reliability is MIL-107D (-65℃, 30 minutes to 125℃,
The number of cycles at which the resistance value increases by 10% (thermal shock test with a 30-minute cycle) and the blowhole occurrence rate are determined by soldering conditions of 240°C and 5 seconds. The manufacturing conditions of Example 1) were as follows: a) Insulating substrate: An epoxy resin laminate plate was coated with a plating catalyst-containing adhesive (HA-04 manufactured by Hitachi Chemical Co., Ltd.) and cured. b) Thermosetting resin layer forming step: Epoxy resin emulsion (Epolsion manufactured by Kanebo NSC)
Hardening agent EB- for 100 parts by weight of solid content of EA-1
1) to which 80 parts by weight of 1) was added, palladium liquid
After immersing PEC-8 (a plating catalyst manufactured by Hitachi Chemical Co., Ltd.) in a 1% solution containing palladium at a concentration of 0.03 parts by weight per 100 parts by weight of resin, the emulsion on the surface of the adhesive was removed using a bub. is removed, and further heated with hot air heated to about 100°C at a wind speed of 3 m/sec. c) Plating resist process: Screen printing the plating resist ink (HGM-02BK-1 manufactured by Hitachi Chemical Co., Ltd.) and curing it by heating at a temperature of 160°C for 30 minutes. d) Roughening step: The surface of the adhesive is roughened with a borofluoric acid roughening solution, washed and dried. e) Electroless plating process: A 30μ thick copper layer is formed by a normal electroless copper plating process. In Example 2), 10 parts by weight of nitrile butadiene rubber (Higher 1522 manufactured by Nippon Zeon Co., Ltd.) was added to 100 parts by weight of the thermosetting resin in Example 1), and in Example 3), In Example 1), the roughening liquid was a sodium fluoride/chromium sulfate system, and in Example 4), hot air heated to about 100°C at a wind speed of 4.5 m/sec was used after removing the emulsion in step b) in Example 1). Example 5) was heated with hot air at a wind speed of 5 m/sec heated to about 100°C after the emulsion was removed in step b) in Example 1), and Example 6) was heated with Example 1). In step b), after removing the emulsion, heating was performed using hot air heated to about 100° C. at a wind speed of 5.5 m/sec, and the conventional example was obtained by omitting step b) in Example 1). As is clear from the table, according to the present invention, compared to the conventional example, the plating adhesion on the hole wall surface for through-holes is about 1/2 or less, the plating deposition rate is faster, and the through-holes are more reliable. The sex is about 1.4 times more,
The blowhole occurrence rate will be less than 1/5. Further, according to the present invention, it is clear that when the hot air velocity exceeds 5 m/sec, the adhesion of the hot air sharply increases, so it is preferably 5 m/sec or less. (Effects of the Invention) As described above, according to the present invention, by uniformly disposing the thermosetting resin on the hole wall surface of a through hole, plating precipitation on the hole wall surface is accelerated, and manufacturing time can be shortened. A highly reliable printed wiring board manufacturing method with a low blowhole occurrence rate can be obtained.

[Brief explanation of drawings]

1 to 6 show the manufacturing process of an embodiment of the present invention, in which FIG. 1 is a cross-sectional view of an insulating substrate provided with an adhesive layer, FIG. 2 is a cross-sectional view of an insulating substrate with holes formed, and FIG. The figure is a cross-sectional view of an insulating substrate with a thermosetting resin layer provided on the hole wall, 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 provided with a circuit. DESCRIPTION OF SYMBOLS 1... Insulating substrate, 2... Adhesive layer, 3... Hole, 4... Thermosetting resin layer, 5... Plating resist layer, 6... Circuit.

Claims (1)

[Claims] 1. In a method for manufacturing a printed wiring board in which a predetermined circuit and through holes are formed by an electroless plating method on an insulating substrate having holes for through holes and coated with a plating catalyst-containing adhesive, an insulating substrate is plated. A process of dipping into an emulsion of a thermosetting resin containing a catalyst and plating the thermosetting resin containing a catalyst onto the hole wall surface, and after this process, removing the emulsion on the surface and drying the hole with hot air at a wind speed of 5 m/sec or less. A step of heating the thermosetting resin attached to the wall surface, a step of adhering a plating catalyst to the thermosetting resin after the step, and a step of immersing the insulating substrate in a roughening solution after forming the plating resist layer. A method for manufacturing a printed wiring board, comprising the step of roughening an adhesive layer.