PCBA processing is also known as chip processing, more upper layer is called SMT processing, SMT processing, including SMD, DIP plug-in, post-solder test and other processes, the title of the pads are not on the tin is mainly in the SMD processing link, a paste full of various components of the board is evolved from a PCB light board, pcb light board has a lot of pads (placement of various components), through-hole (plug-in), the pads are not tin currently occurring The situation is less, but in SMT inside is also a class of quality problems.
A quality process problems, is bound to be multiple causes, in the actual production process, need to be based on relevant experience to verify, one by one to solve, find the source of the problem and to solve.
I. Improper storage of PCB
In general, spray tin a week will appear oxidation, OSP surface treatment can be stored for 3 months, sunken gold plate can be stored for a long time (at present such PCB manufacturing processes are mostly)
II. Improper operation
Wrong welding method, not enough heating power, not enough temperature, not enough reflow time and other problems.
III. The PCB design problems
Solder pad and copper skin connection method will lead to inadequate pad heating.
IV. The flux problem
Flux activity is not enough, PCB pads and electronic components soldering bit does not remove the oxidation material, solder joints bit flux is not enough, resulting in poor wetting, flux in the tin powder is not fully stirred, failure to fully integrated in the flux (solder paste back to temperature time is short)
V. PCB board itself problem.
PCB board in the factory before the pad surface oxidation is not treated
VI. Reflow oven problems
Preheating time is too short, the temperature is low, the tin has not melted, or preheating time is too long, the temperature is too high, resulting in flux activity failure.
From the above reasons, PCBA processing is a kind of work can not be sloppy, each step needs to be rigorous, otherwise there is a large number of quality problems in the later welding test, then it will cause a very large number of human, financial and material losses, so PCBA processing before the first test and the first piece of SMD is necessary.
Post time: May-12-2022