Copper is one of CCL's most important raw materials, which often determines the quality and the use of CCL.
By copper foil of different methods can be divided into rolling copper and electrolytic copper foil two categories. Are rolled copper foil (Rolled Copper Foil) and electrolytic copper foil (Electrode Posited copper).
(1) rolled copper foil (Rolled Copper Foil) is rolling copper is repeatedly made of the original foil (also called hair foil), according to the requirements of rough processing. As the rolling copper processing constraints, the width of the laminate is difficult to meet the rigid requirements, it rolled copper foil used in very small rigid copper clad board. As the folding and rolling copper electrolytic copper foil is larger than elasticity, it applies to flexible copper clad board. Its purity copper (99.9%) than electrolytic copper foil (99.8 9 / 5), electrolytic copper foil in hair than smooth surface, which are conducive to rapid transfer of electrical signals. Therefore, in recent years of foreign high-speed signal transmission in high frequency, small wire on the PCB substrate, using rolled copper foil. It is in the audio device to use PCB substrate, but also improve the sound quality. It is also used to reduce the thin wire, high number of multi-layer circuit board of the thermal expansion coefficient (TCE) and the system "metal sandwich board" on. Rolled copper foil of Japan in recent years has also introduced new varieties, such as: high toughness rolled copper foil, a kind of low-temperature crystallization of the rolled copper foil. Because of its high flexural bending resistance for flexible board. The other is anaerobic rolling copper foil, is characterized by the oxygen content of 0.001%, its tensile strength, can be used for TAB requested the lead of the printed circuit board with high intensity, and sound equipment on the PCB.
(2) electrolytic copper foil (Electrode Posited copper) is made of copper dissolved by the solution first, then a dedicated copper sulfate electrolyte electrolysis equipment will be under the influence in DC, made of the original foil electrodeposition, and then asked the original foil surface treatment, heat treatment and oxidation treatment layer and a series of surface treatment. Electrolytic copper foil is different from the rolling, electrolytic copper foil surface on both sides of different crystal forms, close to the cathode side of roller relatively smooth, as smooth; other side of the concave and convex shape of the crystal showing the organizational structure, a bit rough, as rough surface. Electrolytic copper foil and rolled copper foil surface treatment is also quite different. As the electrolytic copper foil is a columnar crystal structure, toughness, strength and other properties to be inferior to rolled copper foil, the electrolytic copper foil are used for the production of rigid copper clad laminate, and then made rigid PCB.
On the electrolytic copper foil (including coarsening treated) are mainly the thickness of standard quality, appearance, tensile strength, peel strength, high temperature oxidation resistance, the quality of copper resistivity technical performance requirements. In addition to these seven key performance requirements, some countries, local manufacturers, there are other aspects of performance requirements, such as elongation, folding resistance, hardness, elastic modulus, high extension, surface roughness, etch resistance, weldability , UV ink adhesion, such as copper hue.
With high-density PCB thinning, multi-layered, thin (<0.8mm) and high frequency of the continuous development of a number of high-performance electrolytic copper foil manufacturing technologies have emerged, according to test this the proportion of copper in the market share will reach 40%. These high-performance type of electrolytic copper foil as follows.
① excellent tensile strength and elongation of copper under normal high tensile strength and high elongation rate of levy, can improve the electrolytic copper foil is processed and enhanced rigidity to avoid wrinkles to improve the pass rate of production. Extension of high temperature (THE) copper foil and copper foil under high temperature high tensile strength, can improve the thermal stability of the PCB, to avoid distortion and warping.
② low-profile high-density multilayer copper wiring technology, the traditional type of electrolytic copper foil is not suited to manufacturing high-precision graphics of PCB circuits. Therefore, the new generation of copper - low profile (LOW Proffle, LP), and ultra-low profile (VLP) electrolytic copper foil one after another. Compared with the general electrolytic copper foil, LP copper foil is very fine crystalline (<2/zm), for the equiaxed grains, non-columnar crystals, is the crystal into layers, and the flat ridge, surface roughness is low. VLP copper foil surface roughness degree lower, according to measurements, the average degree of coarsening O. 55 Hong m (usually copper foil of 1.40 Hong m). In addition, better dimensional stability, high hardness and so on.
③ ultra-thin copper foil with mobile phones, notebook computers, represented by portable electronic products containing micro-buried, blind and through larvae L the multilayer BGA, CSP and other organic resin used in packaging substrate to the thin copper foil type, super- thin foil-type forward. COz laser processing also pits also need to use very thin copper foil substrate, so that you can layer on the copper wire directly to micro-hole processing. In Japan, the United States and other countries 9 Hong m, 5pm, 3/-tm of electrolytic copper foil are able to industrial production. Currently, ultra-thin copper foil production technology of difficult or critical point is whether the carrier directly from the qualified products and higher production and development of new carrier.
