PCBA is transmitted through the guide rail during SMT patch processing, so it is necessary to leave a pair of cloth-forbidden components as the transmission side in the PCBA design. In the electronic processing factory, the two long sides of the PCB or the large board after the panel are usually used as the transmission side.
The width of the fixed plate of the SMT transmission track is 3.0mm, and the theoretical limit value of the transmission edge is 3.0mm, but it is recommended that you do not walk this limit and increase the difficulty of placement. To reserve more space as a margin, it is recommended to use 5.0mm as the "forbidden area" on the transmission side.
If this margin is not enough, after the PCBA is placed on the transfer rail, the interference part will affect the solder paste or the components that have been placed. The interference part of the board edge can only be post-welded or need another fixture to increase production. cost.
If the distance between the chip parts in the plate and the edge of the plate is far enough, and it will not be in the range of the crawler, there is no need to add a technological edge. If the part is in the range of the crawler, the technological edge must be added. According to the characteristics of the machine, the width of the process side usually needs 3-10mm, with 5mm being the most common.
The general process side is added on the longer side, and the board enters the SMT machine vertically, so the hardness of the board is relatively high, and it will not bounce due to the light pressure of the machine probe during placement, but the longer side process area is more and the disguise is improved. The average price of a single board. When the hardness of the board is sufficient, it can be added in the short direction, the process side area is small, the average cost of a single board is reduced, and the board enters the SMT machine horizontally.
MT is usually aligned with MARK points. If there are no MARK points in the board, 2-4 MARK points must be added diagonally on the side of the process. The size of the MARK points is generally 1.0mm. The copper is exposed to tin and there are some cases in the board. Next, the process side can be added or not added.
When PCBA substrates are produced, positioning is required for molding and testing. Add special positioning holes on the process side, the shape is relatively standard, and it is more convenient to do positioning. Therefore, 3-4 positioning holes with a diameter of 2.0-4.0mm will be added on the process side, with a diameter of 3mm being the most common.
