New Development of Copper Foil Technology for PCB In The World (1)

(1) A brief introduction to the development of world copper foil production.

In 1937, the copper smelting plant of Anaconda Company in the United States began to establish a copper foil production industry. At that time copper foil was only used for waterproofing of wooden roofs. In the early 1950s, due to the emergence of the printed circuit board industry, the copper foil industry became an important cutting-edge precision industry associated with the electronic information industry.

In 1955, Yates Corporation of the United States separated from Anaconda Corporation and established it as the world’s first company specializing in the production of electrolytic copper foil for PCB. In 1957, the American Gould company also invested in this industry, which equally divided the exclusive market of Yates’ copper foil for PCB in the world. Since Japan’s Mitsui Metal Company (Mitsui) began to introduce the American copper foil manufacturing technology in 1968, Japan’s Frukawa Electric Company (Frukawa) and Nippon Mining Company (Nippon Mining) cooperated with Yates Company and Gould Company respectively to make the Japanese copper foil industry There has been a great development.

In 1972, the patent (U.S.Pat 3674656) of the electrolytic copper foil production of the Yates company in the United States was published, marking the world’s electrolytic copper foil manufacturing and surface treatment technology has entered a new stage.

According to statistics, in 1999, the production of electrolytic copper foil for PCB in the world reached about 180,000 tons. Among them, Japan is 50,000 tons, Taiwan is 43,000 tons, mainland China is 19,000 tons, and South Korea is about 10,000 tons. It is predicted that in 2001 the world’s production of electrolytic copper foil will increase to 253,000 t. The fastest growing among them is Japan (predicted 73,000 t in 2001) and Taiwan (predicted 65,000 1).

Japan, the world leader in copper foil production and technology, has developed rapidly in copper foil production and technology in recent years due to the development of printed circuit boards and copper clad laminates. And in recent years, it has also established Japanese-invested overseas manufacturers in North America, mainland China, Taiwan, Southeast Asia, Europe and other countries and regions. Japan’s main electrolytic copper foil manufacturers are Mitsui Metal Mining Co., Ltd., Nippon Energy Corporation (formerly Nippon Mining Co., Ltd.), Furukawa Electric Co., Ltd., Foton Metal Foil Powder Industry Co., Ltd., Nippon Electrolytic Co., Ltd., etc. The characteristics of Japan’s electrolytic copper foil production are: in recent years, it has developed towards more high-tech and cutting-edge products.

The production of electrolytic copper foil in Taiwan currently ranks second in the world. The main large-scale manufacturers are Changchun Petrochemical Company, Taiwan Copper Foil Company, Nanya Plastic Company and so on.

(2) High Performance Electrolytic Copper Foil

In recent years, in the world copper foil industry, some high-performance electrolytic copper foil manufacturing technologies have been continuously innovated and developed. An overseas copper foil market research expert recently believed that: due to the high-density thinning (LIS = 0.10 mm/0.10 mm or more), multi-layer (more than 6 layers), thinning (0.8 mm) and high The frequent use of high-performance copper foils will be widely used in PCBs, and the market share of such copper foils will reach more than 40% in the near future. The main types and characteristics of these high-performance copper foils are as follows.

1. Excellent Tensile Strength And Elongation Copper Foil
Excellent tensile strength and elongation electrolytic copper foil, including both under normal conditions and high temperature. High tensile strength and high elongation under normal conditions can improve the processability of electrolytic copper foil, enhance rigidity and avoid wrinkling to improve the production qualification rate. High temperature elongation (HTE) copper foil and high tensile strength copper foil at high temperature can improve the thermal stability of PCB and avoid deformation and warpage. At the same time, the problem of high temperature fracture of copper foil (usually copper sinks are used in the inner layer of multi-layer boards to make through-hole inner rings, which are prone to crack ring phenomenon during dip soldering) can be improved by using HTE copper foil.

2. Low Profile Copper Foil

The technological progress of high-density wiring of multi-layer boards makes it impossible to continue to use conventional electrolytic copper foils, which is no longer suitable for the needs of manufacturing high-precision PCB graphics circuits. In this case, a new generation of copper foils—low profile (LP) or very low profile (VLP) electrolytic copper foils have emerged one after another. Low-profile copper foil was successfully developed in the early 1990s (1992-1994) in the United States (Gould’s Arizona plant) and Japan (Mitsui Metals, Furukawa Electric, and Futian Metal Industries) at almost the same time.

Generally, the original foil is made by electroplating method, and the current density used is very high, so the microcrystals of the original foil are very rough and appear as coarse columnar crystals. The “edge line” of the slice cross-section has large fluctuations. The crystal of LP copper foil is very fine (below 2μm), is equiaxed grains, does not contain columnar crystals, is lamellar crystals, and has flat ridges. Low surface roughness. VLP copper foil is actually measured, and the average roughness (R.) is 0.55μm (generally copper foil is 1.40μm). The maximum roughness (R m?x) is 5.04μm (general copper foil is 12.50μm).