Multi-layer PCB in communication, medical, industrial control, security, automobile, electric power, aviation, military, computer peripheral and other fields as the “core force”, product functions are more and more, more and more dense lines, so relatively, the production difficulty is also more and more.
At present, the PCB manufacturers that can batch produce multilayer circuit boards in China often come from foreign enterprises, and only a few domestic enterprises have the strength of batch. Multi-layer circuit board production not only needs higher technology and equipment investment, more need experienced production and technical personnel, at the same time, obtain multi-layer board customer certification, strict and tedious procedures, therefore, multi-layer circuit board entry threshold is higher, the realization of industrial production cycle is longer. Specifically, the processing difficulties encountered in the production of multilayer circuit board are mainly the following four aspects. Multilayer circuit board in the production and processing four difficulties.
1. Difficulty in making the inner line
There are various special requirements of high speed, thick copper, high frequency and high Tg value for multilayer board lines. The requirements of inner wiring and graphic size control are getting higher and higher. For example, the ARM development board has a lot of impedance signal lines in the inner layer, so it is difficult to ensure the integrity of impedance in the inner line production.
There are many signal lines in the inner layer, and the width and spacing of the lines are about 4mil or less. The thin production of multi-core plate is easy to wrinkle, and these factors will increase the production cost of the inner layer.
2. Difficulty in conversation between inner layers
With more and more layers of multilayer plate, the requirements of the inner layer are higher and higher. The film will expand and shrink under the influence of ambient temperature and humidity in the workshop, and the core plate will have the same expansion and shrink when produced, which makes the inner alignment accuracy more difficult to control.
3. Difficulties in the pressing process
The superposition of multi-sheet core plate and PP (semi-solidified sheet) is prone to problems such as layering, slide and drum residue when pressing. Because of the large number of layers, the expansion and shrinkage control and size coefficient compensation cannot keep consistent. The thin insulation between layers will easily lead to the failure of reliability test between layers.
4. Difficulties in drilling production
The multi-layer plate adopts high Tg or other special plate, and the roughness of drilling is different with different materials, which increases the difficulty of removing the glue slag in the hole. High density multi-layer PCB has high hole density, low production efficiency, easy to break the knife, different network through the hole, the hole edge is too close will lead to CAF effect.
Therefore, in order to ensure the high reliability of the final product, it is necessary for the manufacturer to carry out corresponding control in the production process.
Post time: Sep-09-2022
