JPH0343344B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a method of forming chemical plating on an insulator, and more specifically, a method of forming an adhesive layer on an insulator and chemically roughening the surface. After that, it relates to a method of forming chemical plating.

(Prior Art) The technology of depositing a metal layer on the surface of an insulating material such as plastic or glass has many applications such as electrical appliance parts, automobile parts, ornaments, and electronic parts. The method of depositing a metal layer on the surface of such an insulator is carried out by chemical plating, and is well known as an additive method. In both the fully additive method, in which metal is deposited on the surface of a nonconductor by chemical plating alone, and the semi-additive method, in which chemical plating and electroplating are combined, the adhesion of the metal layer by chemical plating is insufficient, and the metal layer often separates from the substrate. Encounter peeling problems.

In order to improve this weak adhesion, there is a method of applying an adhesive, for example, as seen in Japanese Patent Publication No. 16495/1983, a mixture of acrylonitrile rubber, phenol resin and epoxy resin in specified amounts is used. A method of forming a stratum and making the surface uneven with a chromium sulfuric acid solution, as shown in Japanese Patent Publication No. 57-18358, uses thermosetting resin nitrile rubber, phenol-modified epoxy resin, P-nitrophenyl acetic acid, rose bengal, copper chloro There is a method of applying an adhesive thermosetting resin composition in which one or more types of filin sodium and one or more types of zinc oxide and zinc hydroxide are mixed in predetermined amounts and roughening the surface. For all of these adhesives, measures are taken to roughen the surface by chemical or mechanical means. Specific methods for this roughening are also described in the above-mentioned publications, but chemical roughening using chromic acid or the like encounters inconvenient events as shown in FIG.

That is, FIG. 2 is a model diagram of a micrograph of a process cross section immediately after the surface of the adhesive has been roughened by chromium sulfuric acid as chemical roughening. The advantage of chemical roughening such as chromium sulfate over mechanical roughening such as sandblasting is that this surface condition exhibits an extremely complex pattern, as can be understood from the model diagram shown in Figure 2. It is. The chemical plating layer deposited on this surface is therefore not easily peeled off.

(Problems to be Solved by the Invention) However, the only drawback is that gases generated during chemical plating, such as hydrogen gas, are occluded inside the dendritic uneven surface. The hydrogen gas 2 trapped deep within the uneven adhesive 1 eventually pushes up the chemically plated layer (not shown) and appears as a blistering phenomenon. Such a phenomenon causes wire breakage and poor adhesion. Note that 3 is an insulating substrate.

Therefore, this invention is a process of applying an adhesive onto an insulating plate to apply chemical plating, and in particular, even if the surface layer of this adhesive is chemically roughened, the chemical plating layer does not blister. The object of the present invention is to obtain a method that exhibits high adhesion.

(Means for Solving the Problem) This invention chemically roughens the surface of the adhesive and then roughens the surface layer prior to the chemical plating process to the extent that air bubbles generated during the chemical plating process are not incorporated into the adhesive. It is used for grinding.

(Function) The characteristic effect of this invention is that although it is a chemically roughened adhesive, it has a rough surface that does not absorb air bubbles during the chemical plating process, so it is particularly effective in improving the adhesion of chemical plating. It is something that works.

(Embodiment) A preferred embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing the manufacturing process of a printed circuit board with a metal core based on the method of the present invention. The surface is covered with an insulator 11, and this insulator 11 and
An adhesive layer 12 is formed to provide adhesion to the conductor circuit 13 formed thereon. The adhesive 12 may be the composition shown in the above-mentioned publication, but in this example, phenol-based Sumilite resin was used. Next, as shown in b, the adhesive layer 12 was roughened with chromium sulfuric acid. Next, as shown in c, the roughened surface layer of the adhesive layer 12 was ground. The amount of this grinding varies depending on the roughening time in step b, the adhesive used, or the solvent used during grinding, so it is difficult to describe it quantitatively, but the roughened adhesive layer 12 It is about half of the surface layer. In other words, appropriate grinding is performed to prevent bubbles such as hydrogen gas generated during chemical plating in the next step from being occluded deep into the roughened adhesive layer 12. Please note that if this grinding is performed excessively, the adhesion of the chemically plated layer 13 shown in step d will be significantly reduced.

For grinding, a method using brushing was tried. Nylon, hair, and wire brushes were used as brushing materials, but nylon brushes were better in terms of hardness. The incidence of blisters was lower when brushing was done in multiple directions, that is, in a random manner, than in a single direction. This is because the roughening by chromium sulfuric acid in step b does not show any directionality. That is, with unidirectional brushing, it is possible that uneven portions smaller than the thickness of the brush may not be ground at all. Therefore, it is preferable to rub randomly from multiple directions. More specifically, it is wise to perform brushing while appropriately applying rotation and reciprocating motion.

The surface of the adhesive layer 12 has been scraped by mechanical grinding means such as brushing, and the adhesive layer 12 has an uneven state that does not contain bubbles such as hydrogen gas generated in the next process, as shown by d below. A chemical plating layer 13 is then deposited on the surface.

Thereafter, in the semi-additive method, an electroplated layer is formed on this chemically plated layer 13, and patterning is further performed in the printed circuit board.
A detailed explanation of each of these steps will be omitted.

(Effect of the invention) According to the method of this invention, by chemically roughening the surface of the adhesive layer and further grinding the surface layer by mechanical means, gases generated during chemical plating are not occluded, but the process is complicated. Since it is possible to create a surface layer of the adhesive with irregularities, it is possible to apply a chemical plating layer with high adhesion that does not cause blisters on top of the surface layer, which is a great advantage.

[Brief explanation of drawings]

1A to 1D are process cross-sectional model diagrams showing a preferred embodiment of the present invention. FIG. 2 is a model diagram of a microscopic photograph of a cross-sectional view of the process immediately after the surface of the adhesive has been chemically roughened. 10... Metal plate, 11... Insulator, 12... Adhesive layer, 13... Chemical plating layer.

Claims (1)

[Claims] 1. In a method of depositing an adhesive layer on the surface of an insulator and chemically roughening the surface of this layer to form a chemically plated layer, the adhesive layer is coated before forming the chemically plated layer. The method includes the step of grinding the chemically roughened surface layer of the adhesive layer by brushing, and the amount of grinding is such that the amount of grinding is such that the surface condition is such that the gas generated during the formation of the chemical plating layer is not occluded particularly in the recesses on the surface of the adhesive layer. A method of forming chemical plating on a characteristic insulator.