In order to meet customer requirements, the circuit board via hole must be plugged. After a lot of practice, the traditional aluminum plug hole process has been changed, and the circuit board surface solder mask and plug are completed with white mesh which is with stable production and reliable quality.
Via holes play the role of interconnecting and conducting lines. The development of the electronics industry also promotes the development of PCBs, and also puts forward higher requirements for printed board manufacturing technology and surface mount technology. Via hole plugging technology came into being, and the following requirements should be met at the same time:
There is only copper in the via hole, and the solder mask can be plugged or not.
There must be tin and lead in the via hole, with a certain thickness requirement (4 microns), and no solder resist ink should enter the hole, causing tin beads to be hidden in the hole.
The via holes must have solder resist ink plug holes, be opaque, and must not have tin circles, tin beads, and leveling requirements.
With the development of electronic products in the direction of “light, thin, short and small”, PCBs are also developing towards high density and high difficulty. Therefore, a large number of SMT and BGA PCBs have appeared, and customers require plug holes when mounting components, which mainly include five functions:
To prevent the tin from passing through the component surface from the via hole to cause a short circuit when the PCB is over-wave soldered; especially when we put the via hole on the BGA pad, we must first make a plug hole, and then gold-plated to facilitate BGA soldering.
Avoid flux residues in vias.
After the surface mount and component assembly of the electronics factory is completed, the PCB must be vacuumed on the testing machine to form a negative pressure before it is completed.
Prevent the surface solder paste from flowing into the hole to cause virtual soldering and affect the mounting.
Prevent solder balls from popping out during wave soldering, causing short circuits.
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