Due to the rapid development of electronic technology, the continuous development of printed circuit technology has been promoted. PCB boards have developed through single-sided-double-sided and multi-layered boards, and the proportion of multi-layer boards has been increasing year by year. The performance of the multi-layer board is developing to the extremes of high precision dense fine large and tiny. An important process in the manufacture of multilayer boards is lamination. The control of lamination quality becomes more and more important in the manufacture of multilayer boards. Therefore, to ensure the quality of multi-layer board lamination, it is necessary to have a better understanding of the multi-layer board lamination process. Therefore, based on many years of lamination practice, how to improve the quality of multi-layer board lamination is summarized as follows in process technology.
A. The inner core board is designed to meet the requirements of lamination.
Due to the gradual development of laminating machine technology, the heat press has changed from the previous non-vacuum heat press to the current vacuum heat press. The heat press process is in a closed system, invisible and intangible. Therefore, it is necessary to design the inner layer board reasonably before lamination. Here are some reference requirements:
1. The thickness of the core board should be selected according to the total thickness of the multilayer board. The thickness of the core board is consistent, the deviation is small, and the latitude and longitude directions of the blanking are the same, especially for the multilayer boards with more than 6 layers. The latitude and longitude directions of each inner core board must be the same. The warp direction overlaps the warp direction, and the weft direction overlaps the weft direction to prevent unnecessary board bending.
2. There must be a certain distance between the outer dimensions of the core board and the effective unit, that is, the distance between the effective unit and the edge of the board should be as large as possible without wasting materials. Generally, the distance between the four-layer board is greater than 10mm. The six-layer board requires a spacing greater than 15mm, and the higher the number of layers, the greater the spacing.
3. The design of the positioning hole is to reduce the deviation between the layers of the multilayer board, so it is necessary to pay attention to the design of the positioning hole of the multilayer board. The 4-layer board only needs to design more than 3 positioning holes for drilling. For multi-layer boards with more than 6 layers, in addition to designing positioning holes for drilling, it is also necessary to design more than 5 layer-to-layer overlapping positioning rivet holes and more than 5 tool plate positioning holes for rivets. However, the designed positioning holes, rivet holes, and tool holes are generally higher in the number of layers, and the number of designed holes should be correspondingly larger, and the position should be as close to the side as possible. The main purpose is to reduce the layer-to-layer alignment deviation and leave a larger space for production. The target shape is designed to meet the requirements of the shooting machine to automatically identify the target shape as much as possible, and the general design is a complete circle or concentric circle.
4. The inner core board requires no opening, short, open circuit, no oxidation, clean board surface, and no residual film.
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