1.
RESOLUTION OF A
SOLDERABILITY ISSUE
How a component finish on a critical component
was modified to enable improved solderability and
long term reliability

2.
The Client
The client is a major supplier of electronic
parts for the military sector.

3.
The challenge
Certain critical components were detaching
from the solder on a printed circuit board

4.
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

5.
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.

6.
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.