1, the phenomenon described
Customer products for the double-sided patch, the product coil inductance material in the secondary reflow. (Coil inductor as shown in Figure 1) after the second reflow soldering phenomenon. Improve the former rate of 15%.
2, the reasons for the analysis
Coil inductance only two pins, and the pin for the circular contact with the pad is small, limited adhesion after welding, the secondary return when the coil down, affected by the impact of gravity phenomenon.
3, to improve countermeasures
The implementation of solder paste red double-process technology, after printing solder paste, in the coil inductor component location non-pad area point red plastic (shown in Figure 2), then the placement and reflow soldering.
4, the effect of verification
Through this process, the coil off is 100% improved. The reason is that the curing temperature of the red paste is lower than the melting temperature of the solder paste. Before the solder paste melts, the element has been fixed by red gum. Thus resolving the coil drop exception.