PWB Never Soldered

non wetting pwb.png
xrf of thin pad.png
non wetting pwb 1.png

Understanding the characteristics of the multiple surface finishes currently in use for PWB's is critical for failure analysis for this type of defect. 

These images clearly show preferential wetting to the device pin and non wetting to the PWB surface. 

The failure was determined to be a HAL coating that consisted entirely of CuSn IMC's the result of too thin a deposit having been applied.