Basic knowledge of PCB circuit board copper foil

First, the introduction of copper foil

Copper foil: A thin, continuous metal foil deposited on the base layer of a circuit board as an electrical conductor of a PCB. It is easy to adhere to the insulating layer, accepts a printed protective layer, and forms a circuit pattern after etching.

The copper foil is made of copper and a certain proportion of other metals. The copper foil generally has two kinds of 90 foil and 88 foil, that is, the copper content is 90% and 88%, and the size is 16*16 cm. Copper foil is the most versatile decorative material. Such as: hotels, temple Buddha statues, gold signs, tile mosaics, handicrafts, etc.

Second, product characteristics

Copper foil has a low surface oxygen property and can be attached to a variety of different substrates, such as metals, insulating materials, etc., and has a wide temperature range. Mainly used in electromagnetic shielding and anti-static, the conductive copper foil is placed on the substrate surface, combined with the metal substrate, has excellent conductivity, and provides electromagnetic shielding effect.

Third, the global supply of copper foil

Industrial copper foil can be divided into two types: rolled copper foil and electrode posited copper foil. Among them, rolled copper foil has good ductility and is used for early flexible board process. Electrode posited copper foil has the advantage of lower manufacturing costs than rolled copper foil. Since the rolled copper foil is an important raw material of the flexible board, the improvement of the characteristics and the price change of the rolled copper foil have a certain influence on the flexible board industry.

Since there are fewer manufacturers of rolled copper foil and technically in the hands of some manufacturers, the customer has low mastery of price and supply, so it is a feasible solution to replace rolled copper foil with electrolytic copper foil without affecting product performance. However, in the next few years, because the physical properties of the structure of the copper foil will affect the etching factor, in the thin-lined or thin-formed products, the importance of the high-frequency products to the copper foil will be increased again due to telecommunications considerations.

There are two major obstacles to the production of rolled copper foil, resource barriers and technical barriers. The obstacle of resources means that the production of rolled copper foil needs to be supported by copper raw materials, and it is very important to occupy resources. On the other hand, technical barriers have discouraged more new entrants, in addition to calendering techniques, the techniques of surface treatment or oxidation treatment are also. Most of the world's largest manufacturers have many technology patents and key technologies, increase barriers to entry. If the new entrants process the production after purchase and are subject to the cost of the big factory, it is not easy to successfully join the market, so the global rolled copper foil is still a strong and exclusive market.

Fourth, the development of copper foil

Copper foil is an important material for the manufacture of copper clad laminates (CCL) and printed circuit boards (PCB). In the rapid development of today's electronic information industry, electrolytic copper foil is called: "neural network" of electronic product signal and power transmission and communication. Since 2002, the production value of printed circuit boards in China has entered the third place in the world. As the substrate material for PCBs, copper clad laminates (CCL) have become the world's third largest producer. This has also led to the rapid development of China's electrolytic copper foil industry in recent years.

From the perspective of the production department of the electrolytic copper foil industry and the development of the market, it can be divided into three major development periods: the United States created the first world copper foil enterprise and the period of the electrolytic copper foil industry; Japanese copper foil the period in which enterprises monopolize the world market in an all-round way; the period in which the world multi-polarization competes for the market.

PCB CCL Material

1. Resin

The resins used for copper-clad laminates include phenolic, epoxy, polyester, and polyimide resins, with phenolic and epoxy resins being the most widely used.

Phenolic resin is a type of resin formed by the polycondensation of phenols and aldehydes in acidic or alkaline media. Among them, the resin obtained from the polycondensation of phenol and formaldehyde in an alkaline medium is the main raw material for paper-based copper-clad laminates.

Epoxy resin is the primary raw material for glass cloth-based copper-clad laminates. It exhibits excellent adhesion properties as well as electrical and physical performance.

2. Impregnated Paper

Common types of impregnated paper include cotton linter paper, wood pulp paper, and bleached wood pulp paper. Cotton linter paper, made from short cotton fibers, features good resin impregnation and results in laminates with excellent punching and electrical performance. Wood pulp paper, primarily made from wood fibers, is generally more cost-effective than cotton linter paper and offers higher mechanical strength. Using bleached wood pulp paper can improve the appearance of the laminates.

3. Alkali-Free Glass Cloth

Alkali-free glass cloth is the reinforcing material for glass cloth-based copper-clad laminates. For specific high-frequency applications, quartz glass cloth can be used.

4. Copper Foil