Resolution of solder voids in pin-in-hole product
ing improvements were implemented. A fil- ferent hypotheses through experiments and and Gary Gao.
tration system was installed in the recircu- determine the ultimate cause of the solder
lation path of the permanganate desmear- voids. The solder voids which formed references
ing bath to remove residue and lower the were as a result of the residue that was left 1. Acceptability of Electronic Assemblies,
chance of debris attaching onto hole walls. in the PTHs during the sweller/desmear IPC-A-610D, IPC Bannockburn, IL.
To further drive down the dppm rate, addi- operation. This residue was plated into 2005. pp. 5-10, 7-50 to 7-52.
tional actions were taken to minimize the copper nodules. When these copper nod- 2. Kang-Wook Lee, “Mechanism of E&E
chance of copper nodule formation and ules went through the wave solder process, PCB Void Formation (version 1)”
micro copper void formation. The water the thermal energy in the wave volatilized 3. Safdar Ishtiaq, and Ahmed Faisal,
rinse pressure in the deburr line was in- the residual sweller solvent ‘popcorning’ “The implementation of via-in-pad
creased in order to enhance the efficiency the nodule, releasing the gas to form solder interconnects to increase PBC circuit
with which drill debris is flushed away voids in the PTHs. Filtration was imple- density: filled via-in-pad processes are a
from PTHs therefore preventing it from mented to remove the residue by-product way to achieve an intermediate density
contaminating the desmear bath. Periodic from the process. It was then demonstrated increase for a minimal additional cost.”
cleaning of the permanganate desmear that this did nearly eliminate the solder Printed Circuit Design & Manufac-
bath was implemented to avoid excessive void defect. ture, Oct 2007.
residue accumulation. 4. Clyde F. Coombs, Jr., “Printed circuits
acknowledgements handbook”, McGraw-Hill, New York,
summary We the authors wish to thank our families 1995, p28-30.
Once the problem was identified, a cross- who were very understanding while we 5. R. J. Klein Wassink, Soldering in Elec-
company team was established to identify were working on this problem. We further tronics. Electrochemical Publications
the root cause of the solder void phenom- wish to thank our co-workers who were Limited, Scotland, 1984. pp. 271-272,
ena. The team was able to examine the much help; the CMs who worked with us, 310-311.
evidence through failure analysis, test dif- the IBM Fishkill Materials Analysis team
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