Difficulties multilayer wiring board PCB proofing

　　Multilayer PCB in terms of design or manufacture, the more complicated than the single and double ply, we believe it will encounter some problems, and that in a multi-layer circuit boards PCB proofing the difficulties which we have to avoid it?
　　1, the interlayer alignment difficulties
　　because of the many layers of a multilayer circuit board, PCB users increasingly high alignment layer is required. Typically, alignment tolerance between the control layer 75 microns. Considering the large size of the multilayer circuit board unit, large graphics changeover workshop environment temperature and humidity, different inconsistencies caused dislocation core plate overlaps the interlayer targeting the like, such that the multilayer circuit board, more difficult to control.
　　2, the internal circuit fabrication difficulty
　　multilayer circuit board using a special material having a high TG, high speed, high frequency, thick copper thin dielectric layer and the like, and internal circuit pattern dimension control making high demands made. For example, the integrity of the impedance of the signal transmission increases the difficulty of manufacture of the internal circuit. Line width and spacing is small, open and short circuits increases, increasing the short-circuit, pass rate; a thin multi-layer signal, the inner leak detection probability increases AOI; core plate is thin, easy to wrinkle, defective exposure, tends to curl when etching machine; high-rise multi-plate system board, the larger unit size, and high product obsolescence costs.
　　3, the compression difficulty in manufacturing
　　a number of the core plate and prepreg are superposed, prone to slide in the stamping, delamination, voids and bubbles remaining resins and other defects. In the design of the laminated structure, should be considered in heat resistance, pressure resistance material, gel content and thickness of the dielectric, material compression scheme to develop reasonable multilayer circuit board. Due to large number of layers, the size of the expansion and shrinkage coefficient of the compensation control can not maintain consistency between the thin interlayer insulating layer easily lead to failure of the reliability test.
　　4, making drilling difficult
　　high TG, high-speed, high-frequency, type of special thick copper sheet, an increase of the roughness of the borehole, drilling burrs and desmear the difficulty. Large number of layers, thickness, and the cumulative total copper thickness, drill cutting knife easily; intensive BGA multiple, narrow-bore wall due to failures pitch CAF; thickness due to problems easily lead helical drill. More details on PCB circuit board all in the Czech Republic with the official website https://www.jiepei.com/G602, welcome to learn together!