Analysis of the causes of tin beads in SMT reflow soldering
Oct 14, 2021
1. Reasons for the production of tin beads (part one):
1. Reasons for the production of tin beads (part one):
Phenomenon: Tin balls are generally one or a few large solder balls, which usually appear next to chip resistors or capacitors, or around the pins of fine-pitch chips.
Analysis: excessive printing of solder paste; poor solderability of the component soldering body; too slow heating up, etc., too slow heating up causes capillary action, sucking the non-reflowed solder paste back to the bottom of the tape component, and then during reflow, the solder paste melts. At this time, due to the different surface tension and differential shear force, the liquid tin is squeezed out and gathered next to the component.
Solution: Properly increase the heating slope, and try in sections until the problem is solved.
2. Reasons for the production of tin beads (two):
The printed solder paste itself is too large, no matter how the furnace temperature is changed, there is no significant effect, and there is pressure on the placement...too many reasons.