The stability of multi-layer PCB material standard is the primary factor affecting the positioning accuracy of the inner layer. It is also necessary to consider the influence of the thermal expansion coefficient of substrate and copper foil on the inner layer of Multilayer PCB. From the analysis of the physical properties of the substrate used, the laminates contain polymers, and its primary structure will change at a certain temperature, which is commonly known as the glass transition temperature Tg. Glass transition temperature is the unique function of large subordinate polymers, second only to the coefficient of thermal expansion. It is the most important characteristic of laminates.
The natural expansion rate of electroplated through holes is lower than that of the surrounding laminates. In the processing of circuit board, the thermal expansion of laminate is faster than that of hole body, which means that the through hole body is stretched along the deformation direction of laminate. Under this stress condition, the tensile stress occurs in the through-hole body. When the temperature increases, the tensile stress will continue to increase. When the stress exceeds the cracking strength of the through-hole coating, the coating will crack. At the same time, the high thermal expansion rate of the laminate significantly increases the stress on the inner conductor and pad, resulting in the cracking of the conductor and pad, forming a short circuit in the inner layer of Multilayer PCB.
In the process of circuit board processing, the selection of raw materials is also very important. We should conduct in-depth analysis on the functions of raw materials to ensure that the raw materials meet certain skill requirements and bring assistance to later processing. In the future, the skills will continue to develop, and its production method will become more advanced over time to ensure that the standard and accuracy of the circuit board meet the requirements.
Xinfeng Mingxin Electronic Technology Co., Ltd