New Development of Copper Foil Technology for PCB In The World (2)

In addition to ensuring the general performance of ordinary copper cylinders, VLP, LP copper foil also has the following characteristics.

① The initial precipitation of VLP and LP copper foil is a crystalline layer that maintains a certain distance. This crystalline structure can prevent the sliding between metal grains, and there is a greater force to resist deformation caused by external conditions. Therefore, the tensile strength and elongation (normal state and thermal state) of copper foil are better than those of general electrolytic copper foil.

② LP copper foil is smoother and finer on the roughened surface than ordinary copper foil. On the interface between the copper foil and the substrate, there will be no residual copper powder (copper powder transfer phenomenon) after etching, which improves the surface resistance and interlayer resistance characteristics of the PCB, and improves the reliability of the dielectric properties.

③It has high thermal stability and will not cause copper recrystallization on thin substrates due to multiple laminations.

④The time for etching the graphic circuit is less than that of the general electrolytic copper foil. Reduced side erosion. White spots are reduced after etching. Suitable for the production of fine lines.

⑤ LP copper foil has high hardness, which improves the drillability of multilayer boards. Also suitable for laser drilling.

⑤ The surface of LP copper foil is relatively flat after the multilayer board is pressed and formed, which is suitable for the production of fine line circuits.

⑦ The thickness of LP copper foil is uniform, the signal transmission delay is small after the PCB is made, and the characteristic impedance is well controlled, and there will be no noise between lines, layers and layers.

Low profile copper foil is very different from general electrolytic copper foil in terms of microstructure, such as grain size, distribution, crystal orientation and distribution. The low-profile copper foil manufacturing technology is based on the electrolyte formulation, additives, and electroplating conditions in the original traditional general electrolytic copper foil production, and has made great improvements and technological advancements.

3. Ultra-Thin Copper Foil

Multilayer boards with micro-buried and blind vias for portable electronic products represented by mobile phones and notebook computers, as well as organic resin packaging substrates such as BGA and CSP, the copper foil used is thin foil type, ultra-thin foil type advance. At the same time, the CO2 laser etching process also requires ultra-thin copper foil as the substrate material, so that the copper foil layer can be directly processed with micro-holes.

In Japan, the United States and other countries in recent years, thin copper foil with a thickness of 12 μm has been generalized in the application. 9μm, 5μm, 3μm electrolytic copper cycle has been industrialized production. At present, the technical difficulties or key points in the production of ultra-thin copper foil are mainly manifested in two aspects: one is that the 9μm thick ultra-thin copper foil is directly produced from the carrier (support), and maintains a high product qualification rate. The second is to develop a new type of ultra-thin copper foil carrier. In terms of the types of carriers used, there are currently copper, aluminum, and thin films. The aluminum carrier is used in a large amount, but the etching process of strong alkali is required to remove the aluminum carrier, so it is faced with the problem of waste liquid treatment. When the copper carrier is removed, the peeling method is used, but its peelability and the treatment of peeling off the copper layer also have problems. Some copper foil manufacturers in Japan have developed a film-type carrier, which has the advantages of light weight, easy access, and good peelability after plate forming and pressing.