JPH04209596A - Materials for circuit boards - Google Patents

Abstract

PURPOSE:To improve the adhesion between the macromolecular film of a base material and a copper layer so as to provide high reliability by providing a nickel chromium alloy layer, a copper nickel alloy layer, and a copper layer in order on the macromolecular film. CONSTITUTION:A chromium layer excellent in the adhesion with a macromolecular film or a nickel chromium alloy layer (the first buffer layer), which contains chromium by 50wt. portion or more, are provided on a macromolecular film. Thereon, a nickel layer excellent in the adhesion with the first butter layer or a copper nickel alloy layer (the second buffer layer), which contains nickel by 50wt. portion or more, are provided. A copper layer is provided on the second buffer layer, and the macromolecular film of the substrate and the copper layer are bonded firmly to each other.

Description

[Detailed description of the invention]

[00017

[Industrial Field of Application] The present invention relates to a circuit board material used for electronic circuit boards such as computers and word processors. [0002] Conventionally, as materials for circuit boards, materials in which a copper layer is provided on a polymer film such as glass epoxy, polyimide, or polyester have been used. [0003]

[Problems to be Solved by the Invention] However, since the above-mentioned material in which a copper layer is provided on a polymer film has low adhesion between the polymer film and the copper layer, it is difficult to perform etching treatment and tin plating for circuit formation. There was a problem in that pretreatment, machining such as drilling, and soldering caused both parts to peel off due to heat treatment and the like. For this reason, various surface treatment methods for the polymer film used as the material have been studied, but no sufficient improvement has been achieved. was proposed, but when using chromium, the chromium layer and the copper layer tend to separate, and when nickel is used, the nickel layer and the polymer film tend to separate. Ta. [0004]

[Means for Solving the Problems] The present invention was made as a result of intensive research in view of the above situation, and its purpose is to improve the adhesion of the copper layer that serves as a conductor to the base material.
The purpose of the present invention is to provide a material for circuit boards based on a polymer film. That is, the circuit board material of the present invention includes, on a polymer film, a chromium layer or a nickel-chromium alloy layer containing 50 parts by weight or more of chromium, and a nickel layer or a copper-nickel alloy layer containing 50 parts by weight or more of nickel. and a copper layer are sequentially provided. The circuit board material of the present invention includes a chromium layer having good adhesion to the polymer film or a nickel-chromium alloy layer containing 50 parts by weight or more of chromium (hereinafter referred to as the first buffer layer) on the polymer film. A nickel layer having excellent adhesion to the copper layer and the first buffer layer or a copper-nickel alloy layer containing 50 parts by weight or more of nickel (hereinafter referred to as the second buffer layer) is provided on the second buffer layer, and A copper layer is provided on the
The polymer film as the base material and the copper layer for forming the circuit are tightly adhered to each other. [00051 In the circuit board material of the present invention, films such as glass-epoxy, polyimide, polyester, and ethylene/fluoroethylene copolymer can be applied to the polymer film serving as the base material, but polyimide films are particularly suitable. It has excellent adhesion to the first buffer layer. Prior to providing a first buffer layer on the above polymer film,
It is desirable to activate the polymer film by plasma treatment in an atmosphere of nitrogen gas, oxygen gas, argon gas, etc., because this improves the adhesion between the polymer film and the first buffer layer. If the thickness of each of the first buffer layer and the second buffer layer provided on the polymer film that is the base material of the circuit board material of the present invention exceeds 1000A, when the material is wound up, Cracks will occur in the buffer layer and the second buffer layer, so if any layer is less than 1000m thick, and more specifically, if the thickness of each exceeds 300mn, the material obtained will curl due to the difference in thermal expansion with the polymer film. Therefore, it is preferable to set it to 3008 or less. Also the first
The thickness of each of the buffer layer and the second buffer layer is 5
If the thickness is less than A, it becomes difficult to provide the first buffer layer and the second buffer layer with uniform thickness. For this reason, the thickness of each of the first buffer layer and the second buffer layer is
The most preferred range is 300A to 5 people. In addition, as a method for forming the first buffer layer and the second buffer layer on the polymer film that is the base material, chemical vapor deposition method, sputter deposition method, etc. are used, but especially sputter deposition method has excellent adhesion. It is preferable that things can be formed. Further, it is preferable to provide the first buffer layer and the second buffer layer continuously in-line by sputter deposition to improve adhesion. Further, the copper layer is deposited on the second buffer layer by sputter deposition or the like. 1
It is best to pre-coat to a thickness of ~1 μm and then form it to the required thickness using methods such as electroplating.
This is preferable because the adhesion between the copper layer and the second buffer layer is improved. Further, it is preferable that the preliminary coating of the copper layer is performed continuously in-line after the first buffer layer and the second buffer layer, since mutual adhesion is improved. [0006]

[Examples] The present invention will be explained in detail below using examples. Example 1 A polyimide film with a thickness of 50 μm was activated by plasma treatment in an argon atmosphere, and then 50 A of chromium, 50 A of nickel, and copper were sequentially sputter-deposited onto the film to a thickness of 1 μm to form a composite material. Next, copper was electroplated to a thickness of 35 μm on the copper layer of this composite material to obtain a material for a circuit board. Incidentally, sputter deposition of chromium, nickel, and copper was performed continuously in-line, and argon gas was used as a carrier gas for sputter deposition. Example 2 A circuit board material was manufactured in the same manner as in Example 1, except that chromium, nickel, and copper were sputter-deposited separately in a batch manner. Example 3 In Example 1, the chromium layer and nickel layer provided on the polyimide film were formed using a nickel-chromium alloy containing 50 parts by weight or more of chromium and a copper-nickel alloy containing 50 parts by weight or more of nickel, respectively. Others are
A circuit board material was manufactured by the same method as in Example 1. Comparative Example 1 A circuit board material was manufactured in the same manner as in Example 1, except that the chromium layer and/or nickel layer was not provided. [0007] For each circuit board material produced in this way, a peeling test of the copper layer by tension, formation of a conductor pattern on the copper layer by photolithography, and peeling of the formed conductor pattern using adhesive tape were performed. Tests were conducted to determine the adhesion of the copper layer. The results are shown in Table 1. In addition, in the peeling test of the copper layer by tension, the above material was
A test piece was cut out to a width of m. One end of the test piece was removed leaving the polyimide film, and the other end was removed leaving the copper layer. The polyimide film and copper layer at both ends were chucked. The test was carried out by biting the material and pulling it, and measuring the load at break. In addition, to form a conductive pattern on a copper layer by photolithography, the copper layer is covered with an alkali-developed type resist film, and then a conductive pattern is formed with a width of 50 μm and a pitch of 1100 μm.
After developing the L conductor pattern with a mixed alkaline solution of caustic soda and caustic potash, the exposed copper layer was removed by etching with an aqueous ferric chloride solution, the resist film was then removed with acetone, and finally the resist film was etched with hydrochloric acid and tetrahydrochloride. Electroless plating of tin was performed on the conductive pattern by immersing it in an aqueous solution of stannous chloride acidified with fluoroboric acid. Further, the peel test using an adhesive tape for the conductor pattern was performed by pasting an adhesive tape having an adhesive force equivalent to 500 g/cm on the conductor pattern and peeling off the tape. [0008]

[Table 1] As is clear from Table 1, the products of the present invention (Nos. 1 to 3) are:
The adhesion of the copper layer was good in all tests. In particular, the one in which the buffer metal layer is continuously sputter-deposited in-line (No. 3) is different from the batch-type one (No.
2) showed higher values in the tensile test. Furthermore, there was no difference in the type of buffer metal between pure metal and alloy. On the other hand, the comparative products (Nos. 4 to 6) all had poor adhesion, and peeling was observed in the conductor pattern after formation when the conductor pattern was formed by photolithography, and this conductor pattern was not formed using adhesive tape. Everything peeled off in the peel test. In addition, the peeling site No. 5 or No. 6 is as follows:
They were between the nickel layer and the polyimide layer or between the chromium layer and the copper layer, respectively. [0009]

[Effects] As described above, the material for circuit boards of the present invention has good adhesion between the base polymer film and the copper layer, and can be used in electronic circuit boards to achieve high reliability, which is remarkable in industry. It has a great effect.

Claims (1)

[Claims] Claim 1: A chromium layer or a nickel-chromium alloy layer containing 50 parts by weight or more of chromium, a nickel layer or a copper-nickel alloy layer containing 50 parts by weight or more of nickel, and a copper layer are sequentially provided on a polymer film. A material for circuit boards that is characterized by: