We have a long time concerns in one of our product modules. These are
the misalignment of LED components (SMD type) and no solder on its
termination. The root cause of the problems have already pinpointed
through our investigations. Potential cause is the termination design
of the component is not suitable for the mounting orientation. The
LED is being mounted in sideway direction and with said orientation,
the design of the termination is only at the right, left and front
sides. However, the bottom part of the LED has no termination which
will serves as the conductor during metallic fusion between the
solder pad and the component. The problem is, during the melting
period of solder paste the component is also moving causing
misalignment and often times no solder. We have conducted the
evaluation using solder paste containing 2% silver (Sn62Pb36Ag2) but
the problem still exists. We eliminated the misalignment by
putting a non-conductive epoxy but no solder is still present in our
line. Our customer won't allow us to modify the existing component
even it is already pinpointed as the main cause. That's why we
injected an inert gas (N2) in our process. Though our defects have
been reduced by15% but we need to eliminate this variable.

Does anyone have suggestions for our evaluation?

Jon M. Pinca
Supervising Process Engineer
Electronic Assemblies, Inc.
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