Choosing a wave soldering machine suitable for welding SMC/SMD, usually a double wave soldering machine or an electromagnetic pump wave soldering machine. The device must be validated.
The tools that must be available at the production site of the prototype pcb are: 300 ° C thermometer (validated) for measuring the actual temperature of the tin wave; density meter (validated) for measuring the density of the flux; nozzle cleaning tool; solder pot residue cleaning tool.
Prototype pcb production environmental requirements of wave soldering are as flows : 1 The working room should be well ventilated, clean and tidy; 2 the fluxing device should be covered with a lid to prevent evaporation; 3 the recycled flux should be stored separately, periodically return to the chemical library or concentrate on processing.
Leaded products generally use Sn/37Pb rod eutectic solder with a melting point of 183 °C. During usage, the contents of Sn and Pb were kept within +1%, respectively.
Lead-free high-reliability products generally use Sn-3Ag-0.5Cu or Sn-3.5Ag-0.75Cu, and have a melting point of about 216-220 °C. The consumer product may be Sn-0.7Cu or Sn-0.7Cu-Ni, which has a melting point of 227 °C. Adding a tiny amount of Ni can increase the fluidity and elongation; or use a low-silver Sn(0.5~1.0)Ag(0.5~0.7)cu alloy with a melting temperature of 217~227°C.
According to the usage condition of the equipment, the alloy proportion and main impurities of the solder are regularly detected (three months to six months). When the solder is not met requirement, the solder is replaced or measures are taken. For example, when the Sn content is less than the standard, some pure Sn may be added.
The above is provided by FASTPCBA!