RESOLUTION OF A SOLDERABILITY ISSUEHow a component finish on a critical component was modified to enable improved solderability and long term reliability

The Client

The client is a major supplier of electronic parts for the military sector.

The challenge

Certain critical components were detaching from the solder on a printed circuit board

The problem

Without the critical component, the circuit board would fail. Without the PCB, the entire module for this component of a military vehicle would be rendered ineffective

The Solution

ITRI Innovation performed a series of analyses to characterise the solderable finish of the coating. As the substrate of the component terminations were a brass alloy, the solderability issues were found to be due to zinc migration. The introduction of an extra interlay in the coating was suggested to restrict the migration of zinc in order to ensure that the solderability would not be affected.

The Outcome

With the introduction of the interlay in the termination finish, the solderability issues were eliminated overnight A series of quality checks were carried out to ensure that

the new finish was being consistently applied. The soldering performance of this new finish was then

assessed using the wetting balance method. Finally, the solder joints produced were evaluated by cross-

sectioning and microscopy to ensure they were of an acceptable standard.

The improved solderable finish, and solder joints, are now being used on live hardware with zero field returns to date.