JPS60204883A - Partial plating method - Google Patents

Abstract

PURPOSE:To form a plating layer having excellent linearity in the edge part of plating by sticking tentatively a masking material contg. a plasticizer which is liquid at an ordinary temp. to a metallic bar and plating the same in the stage of subjecting said bar to partial plating to a desired shape. CONSTITUTION:A masking material formed with a desired pattern to allow permeation of a plating liquid is adhered to a metallic bar and the bar is subjected to a plating treatment in the plating liquid to form a plating film having a desired shape thereon. A material formed by mixing a plasticizer which is liquid at an ordinary temp. at >=5wt% ratio with a material consisting of a plastic tape or sheet of polyester, PVC, etc. and a pressure-sensitive adhesive material consisting essentially of rubber or synthetic resin is used as the masking material to be used in this case. The adhesion to the metallic bar is easy. The part of said material where the pattern to allow permeation of the plating liquid is formed is beautiful and deformation-free. The partial plating having the exact and beautiful edges is formed without intrusion of the plating liquid to the bottom surface of the masking material.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a partial plating method in which a masking material is temporarily attached to a metal strip and plating is performed.

Methods for manufacturing electronic components such as IC lead frames and transistor lead frames include plating metal strips with precious metals such as gold and cutting them into desired shapes, or cutting metal strips into desired shapes in advance and plating them with precious metals. 〇Recently, as an alternative method to these methods, a method is used in which the key points of the mating strip are masked in advance with a masking material in which a plating liquid permeable pattern is formed, and the plating is applied to the pattern. A method has been proposed in which the material is then cut and processed.

However, the materials used as these masking materials are plastic films coated with adhesives such as pressure-sensitive adhesives mainly made of rubber X-ray resin, thermosetting adhesives, and thermoplastic adhesives. For example, when using a pressure-sensitive type to form a plating liquid permeable pattern using a cutting blade due to the rubber elasticity of the line adhesive, the cut portion deforms and the edges of the pattern do not come out beautifully. Although the edges of the pattern appear beautiful with the heat-sensitive type, a heating process is required, and the adhesive layer deforms during processing due to heating, resulting in the plating on the edges not coming out in a straight line. -Furthermore, due to the lack of microscopic smoothness of these adhesive layers, fine voids are formed at the interface with the metal strip.
There are problems such as the infiltration of plating solution into this area, making it difficult to obtain plating with beautiful edges, and these problems are becoming more serious as electronic components are required to be smaller and have higher performance. The current situation is that it is increasing.

Therefore, an object of the present invention is to use a masking material that allows the edge portions of the plating solution permeation pattern to be formed beautifully, and that does not cause the edge portions of the plating to become non-linear due to deformation or the like even when the masking material is used for plating processing. The purpose of the present invention is to provide a partial plating method.

The object of the present invention is to continuously treat a composite body made of a metal strip with a masking material formed with a desired plating solution permeation pattern with a plating solution by using a plastic tape (as the masking material). This can be achieved by using a plasticizer which is composed of an adhesive layer (or sheet) and an adhesive layer, and which contains at least a plasticizer that is liquid at room temperature.

According to the partial plating method of the present invention, since a masking material consisting of an adhesive layer containing a liquid plasticizer at room temperature is used,
The adhesive layer is appropriately plasticized, so even if a plating liquid permeation pattern is formed using a cutting blade, the cut portion will not be deformed, and the pattern will be beautifully formed, and it will not be difficult to make it into a metal strip. When adhering, it can be applied with light pressure such as finger pressure, and the interface between the masking material (adhesive layer) and the metal strip is adhered without any gaps by the appropriately plasticized adhesive layer, so it can be attached to the interface of the plating solution. It is characterized by the fact that there is no infiltration of particles, and therefore plating with beautiful edges can be obtained.

To specifically explain the partial plating method of the present invention, for example, a masking material having an adhesive layer containing a liquid plasticizer at room temperature and a metal strip are synchronously transferred, and the masking material is coated with the metal strip before being bonded together. After bonding, insert a cutting blade and make a cut for forming a plating liquid permeation pattern consisting of a slit of a predetermined width or a hole of a predetermined shape, and remove the unnecessary portion after bonding, or apply the plating solution to the masking material in the same manner as above after bonding. A composite consisting of the metal strip and masking material is made by making cuts for forming a transparent pattern and removing unnecessary parts, and this is continuously immersed in a plating solution, washed and dried, and then masked. Complete by stripping and removing the material.

It is preferable to form the pattern in the middle of the masking process because it will less likely cause deformation etc. to the pattern forming part. Temporarily attach a release film or similar product to the adhesive layer surface and wind it into a four-ring shape 1
It is a good idea to leave it as is.

The masking material used in carrying out the present invention is a plastic tape (such as polyester or polyvinyl chloride).
or sheet) and an adhesive layer consisting of a pressure-sensitive adhesive material mainly composed of rubber and/or synthetic resin, and at least the adhesive layer contains a plasticizer that is liquid at room temperature. However, the plastic tape (or sheet) may also contain the plasticizer.

The plastic tape (or female sheet) is also a masking material containing the above plasticizer. Since the elasticity of the tape (or sheet) has decreased, a plating liquid permeation pattern is formed on the masking material using a cutting blade. Even if the cutting edge portion is not deformed due to elastic deformation of the tape (or sheet), a more beautiful pattern can be obtained.

The plasticizer is added to the adhesive layer by adding a plasticizer that is liquid at room temperature, such as dioctyl 7 tallate, dibutyl 7 tallate, or a polyester plasticizer, to the pressure-sensitive adhesive material at a weight of 75% by weight or less, preferably 5 to 50% by weight. It is desirable that the content be in the range of 50% by weight.

Further, the plasticizer can be added to the tape (or sheet) by being blended in advance or by being transferred from the adhesive layer.

When a plasticizer is contained in both the tape (or sheet) and the adhesive layer, it is desirable that the plasticizer content be 5% by weight or more, preferably 8 to 50% by weight.

The fact that the edge portion of the plating obtained by the partial plating method of the present invention has excellent linearity is illustrated in the following example. Due to the plasticizer, it has a light releasability from the metal strip and can be peeled off without causing any deformation or the like to the metal strip.

Examples are shown below. The text middle part means the weight part.

Example 1 A blend consisting of 85 parts of butyl acrylate, -5 parts of acrylonitrile, and 3 parts of acrylic acid was copolymerized by a conventional method to produce a copolymer having a weighted average molecular weight of 800,000, and a polyisocyanate compound was added to this. An acrylic pressure-sensitive adhesive material was obtained by blending 5 parts of the following.

Next, add 6 parts of polyester plasticizer to 100 parts of the substance.
A masking material was obtained by adding 9 parts of the iJ plasticizer and applying it to a thickness of 10 μm on a polyester film (thickness: 25 μm) containing 11 parts of the iJ plasticizer.

Example 2 80 parts of dioctyl 7 tallate was added to 100 parts of the pressure sensitive adhesive material of Example 1 to prepare a flexible polyvinyl chloride film (80 parts thick) containing 30 parts of dioctyl 7 tallate.
A masking material was obtained by applying the masking material to a thickness of 1OP island (0 μS).

Comparative Example 1 In Example 1, a masking material was obtained without adding the polyester plasticizer.

Comparative Example 2 In Example 1, a masking material was obtained by coating a polyvinyl chloride film containing a small amount of plasticizer without adding a polyester plasticizer.

Next, the masking materials of Examples 1 and 2 and Comparative Examples 1 and 2,
While feeding out the copper sheet at the same speed, make two cuts in the length direction of the masking material with a gap of 1 m in width using a cutting blade, and apply the masking material to the copper sheet using a rubber roller with a hardness of 80 degrees to 10 to 9/Cd. After that, the strips of IH width masking material formed by cuts in the masking material were peeled off and removed to form a composite, which was immersed in a gold plating solution at a speed of 3 m/m and then washed with water. After drying L1, the masking material was peeled off to obtain an IC lead frame material in which plating with a width of IM'I1 was formed in the length direction.
The table shows the characteristics evaluation results of Examples 1 and 2 and Comparative Examples 1 and 2, which were plated using the above method.

Table 1 patent applicant Nitto Electric Industry Co., Ltd. Gold Wire Representative Sanbe Hijikata

Claims (1)

[Scope of Claims] l) When continuously treating a composite formed by pasting a masking material formed with a desired plating solution permeation pattern on a metal strip with a plating solution, a plastic tape ( In addition, it is composed of a sheet) and an adhesive layer, and at least this layer contains a plasticizer that is liquid at room temperature.
A partial plating method characterized by: 2) The partial plating method according to claim 1, wherein the amount of the plasticizer added to the adhesive layer is at least 5% by weight.