Surface treatment method for copper and copper

Abstract

A copper surface treatment method is provided to ensure adhesive strength between a copper surface and an insulating layer without forming a recess and a protrusion over 1[mu]m due to copper surface treatment and to improve insulation reliability between wirings. A copper is also provided. The surface treatment method is provided with a step of discretely forming a metal nobler than copper on the copper surface, and a step of successively oxidizing the copper surface by an alkaline solution including an oxidizing agent. The copper whose surface is treated by such method is also provided.

Description

technical field [0001] The present invention relates to a copper surface treatment method and copper surface-treated by the surface treatment method. Background technique [0002] In recent years, the development of the information society has been astonishing. Computers and mobile phones in consumer equipment are developing towards miniaturization, light weight, high performance, and high functionality. As industrial equipment, wireless base stations, optical communication devices, servers, Network-related equipment such as routers, etc., regardless of large or small, also seek to improve their functions. In addition, with the increase in the amount of information transmitted, the signal to be processed tends to increase in frequency every year. High-speed processing and high-speed The development of transmission technologies is actively underway. Regarding the mounting relationship, at the same time, we are actively promoting the high-speed and high-functionalization of L...

AI Technical Summary

Problems solved by technology

However, in the formation of fine wiring, the unevenness of the copper surface that is in close contact with the resist becomes needle-like, and similar to the above, due to the residue of the resist, there is a problem of short-circuiting between the wirings, and it is impossible to obtain a good bond between the copper surface and the insulating resin. Or the problem of the adhesion between the copper surface and the solder resist, the problem of non-precipitation of gold plating or uneven gold plating

[0018] In addition, in the formation of fine wiring by the semi-additive method, unevenness can be formed on the copper seed layer formed by sputtering. However, similar to the above, since the resist cannot be completely removed from the copper surface, there may be unevenness in the seed layer. Difficulty in forming wiring on the surface, short circuit between wiring, inability to obtain adhesion between copper surface and insulating resin or copper surface and solder resist, non-deposited gold plating or uneven gold plating

[0019] In addition, the height variation of unevenness becomes large. If Rz1.0μm, there will be a transmission loss similar to the first conventional technology. big problem

In addition, because the needle-like crystals of copper oxide are easily damaged, it is impossible to perform horizontal line processing, and there is a problem of poor operability when processing thin plates

In addition, in the plating process of through-hole connection, since the needle-shaped crystals of copper oxide are dissolved, pink circles (pink circles) are formed around the through-holes, and insulation reliability is reduced in parts where the insulation distance between wirings is short. Or easy to peel between the copper surface and the insulating resin

In addition, since a high-temperature alkaline solution is used, the surface of the insulating resin is easily invaded, and the insulation reliability is easily reduced due to ion contamination or insulation deterioration

In addition, when washing with water after oxidation treatment, due to the complicated needle-shaped crystal irregularities of copper oxide, water washing between the needle-shaped crystals cannot be sufficiently performed, and there is a problem that the insulation reliability is likely to be lowered due to residual ions between the crystals.

[0020] The third conventional technique is to provide fine needle-like crystals of metallic copper on the copper surface to improve the bonding strength between the copper surface and the resist or between the copper surface and the insulating resin, because there is no The needle-shaped crystals of metallic copper are dissolved, so no pink circles are generated. However, similar to the second prior art, in the formation of fine wiring, short circuits between wirings may occur due to the residue of the resist. The problem is that the adhesion between the copper surface and the insulating resin or the copper surface and the solder resist cannot be obtained, the problem of non-precipitation of gold plating or uneven gold plating occurs, and the problem of reduced bonding reliability at high temperature and high humidity, Problems of increased transmission loss, problems of poor operability when handling thin plates, problems of reduced insulation reliability due to ion contamination or insulation deterioration of insulating materials, problems of reduced insulation reliability due to water washability after oxidation treatment

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