Apr. 04, 2019
Solder shortage in PCBA process
In the process of SMT PCBA processing, the causes of insufficient solder defects are as follows:
1. Phenomenon. Solder joints are dry, incomplete and have holes. Solder in plug holes and lead holes is not full. Solder has not climbed to the solder pad of SMT components.
(1)PCB preheating and welding temperature is too high, so that the solder viscosity is too low.
(2)The hole of the plug hole through the big, solder out of the hole.
(3) Poor quality metallization hole or flux into the hole.
(4) PCB climbing Angle is small, not conducive to flux exhaust.
(1) In SMT PCBA processing ,preheating temperature is 90 ~ 130 ℃, SMT components is large cap, tin wave temperature (205 + / - 5), welding time is 3 ~ 5 s.
(2)The hole diameter of the plug hole is 0.15 ~ 0.4mm larger than the straight diameter of the pin, the lower limit of the thin lead, the upper limit of the thick lead.
(3)The size of the pad should match the diameter of the pin.
(4) Set the PCB is 4°~ 6 ° incline Angle.