Simply put, the Turnkey Printed Circuit Board Assembly process is a combination of SMT processing and DIP processing. According to different production technology requirements, it can be divided into single-sided SMT placement process, single-sided DIP cartridge process, single-sided mixing process , single-sided placement and cartridge mixing process, double-sided SMT placement process and double-sided mixing process.
In the pcba processing, when the surface tension of the solder is damaged, the surface mount components are poorly soldered. The main manifestation of poor wetting is that during the soldering process, the substrate solder joint and the solder do not react with each other after infiltration, resulting in less soldering or solder leakage.
The main causes of poor wetness of Turnkey Printed Circuit Board Assembly are:
1. The surface of the weld zone is contaminated, the surface of the weld zone is stained with flux, or the surface of the patch component forms a metal compound. Will cause poor wetting. For example, sulfides on the surface of silver, oxides on the surface of tin, etc., may cause poor wetting.
2. When the residual metal in the solder exceeds 0.005%, the degree of flux activity is lowered, and poor wetting occurs.
3. When wave soldering, there is a gas on the surface of the substrate, and it is easy to cause poor wetting.
The solutions to poor wetting are:
1. Strictly implement the corresponding welding process.
2. The PCB board and component surfaces should be cleaned.
3. Select the appropriate solder and set a reasonable soldering temperature and time.