During the PCBA processing process, one end of the electronic component will be lifted up, which is what everyone calls the tombstone phenomenon. So what exactly is the cause? Is there any solution?

PCBA processing

Unreasonable pad design. Too long or too short pad extension will cause tombstone phenomenon. During the pad design process, the overhang size should be reasonable to avoid the pad outer edge wetting angle formed by the overhang length being greater than 45°. Printing problems, poor solder paste printing, uneven component placement, etc. will all lead to tombstones. Therefore, the stencil must be cleaned to ensure that the solder paste printing is full and even, and the placement of the patches must be accurate. Temperature curve setting, the slower the heating rate near the solder paste melting point, the better it is to eliminate the tombstone phenomenon. The pad is contaminated, has solder mask ink, foreign matter adheres to it, and the pad is oxidized. Incoming materials must be inspected for this condition on the PCB pad, and the quality of incoming materials must be strictly controlled.

The above are the reasons for the tombstone phenomenon in PCBA processing. Different solutions for different situations will improve the qualification rate of our products and reduce the time and cost of defective repairs.