Are there reliability risks associated with SAC305 or Tin-Copper wave soldering?
When SAC305 solder is used in wave soldering the temperature is normally set at 255-260°C and for Tin-Copper based solders the temperature normally is higher 260-270°C. When soldering with Sn63Pb37 solder, the pot temperature is typically close to 260°C (500°F). If the contact times with molten solder in a SAC305 process is kept the same there is no detrimental effect. However, many assemblers are finding that they need reduce conveyor speeds and increase contact times to achieve adequate hole-fill with lead-free solders. This can be further aggravated with thicker boards above 0.093″ where contact times may need to be even longer to avoid poor hole-fill. This is a direct result of the differences in the alloys’ physical properties; SAC305 and other lead-free alloys simply do not flow as quickly as Sn63Pb37. This means that adequate hole-fill may only be achieved by decreasing the conveyor speed and thereby increasing the contact time at the wave. Extra contact time does not come witho
