September, 2017
www.us-tech.com
Developing an Ultra- Low-Voiding Solder Alloy
Continued from previous page
Optimizing Solder Alloy Based on these test results, the
company began a research project to determine the optimal soldering alloy for the lowest voiding perform- ance. TGA and X-ray analysis were used. Parameters such as reflow pro- file, yield strength, pasty range, elon- gation, and usability in other processes were also taken into con- sideration.
Interflux’s development strate-
gy involved starting with the stan- dard lead-free soldering alloys and fine-tuning them with Sn, Bi, Ag, Zn, Cu, etc. This resulted in numerous candidate alloys and TGA analysis was used as an initial selection tool.
Amerway Offers Cobar Balver Zinn PCB Solder Materials
Altoona, PA — Amerway is now offer- ing Cobar Balver Zinn solder prod- ucts, including the popular lead-free SN100C alloy. The company also pro- vides a premium line of solder pastes, fluxes, bar, wire, and custom alloys.
Through TGA analysis, the evapora- tion of the flux paste chemistry in combination with a certain alloy and reflow profile was monitored. A smoother evaporation curve corre- lates with lower void formation. From this research, eight prototype soldering alloys were chosen for fur- ther investigation. The eight prototype soldering
alloys were subjected to the same test setup as the initial reference samples. This included soldering QFNs with each solder paste on dif-
Page 47
ferent PCB finishes and analyzing voiding performance with X-ray in- spection. The initial test results showed significant reduction of void levels when compared with the stan- dard SAC305, lowSAC0307 and even Sn42Bi57Ag1. One prototype stood out. “Test
Alloy G” resulted in the lowest void- ing values in combination with the narrowest spreading of the results. The alloy was selected for further mechanical reliability testing. To- gether with its low voiding proper- ties it also showed good shock and vi- bration resistance in combination with better thermal cycling proper- ties than SAC305. Besides reflow, the alloy also
proved suitable for wave and selec- tive soldering. Alloy G was chosen to be commercialized under the name LMPA™-Q. A serious decrease in void for-
mation was obtained with the adjust- ed soldering alloys when compared to the market standards SAC305 and LowSAC0307. According to the re- search, the ultra-low-voiding solder- ing alloy LMPA-Q performs better in thermal cycling and vibration resist- ance when compared with most available soldering alloys. Contact: Interflux N.V., Eddas-
traat 51, 9042 Gent, Belgium % +32-9251-4959 fax: +32-9251-9636 E-mail:
info@interflux.com Web:
www.interflux.com r
SN100C alloy. Cobar Balver Zinn SN100C is a
nickel-stabilized tin-copper eutectic that contains a small amount of ger- manium to reduce oxidation. SN100C generates bright and
shiny solder joints, comparable with lead-containing solders. In 2005, NASA tests indicated that SN100C is the most reliable soft solder for wave soldering. The alloy is especially pre- ferred for the higher process temper- atures of selective soldering. Amerway manufactures a large
selection of lead-free alloys including pure tin, tin-copper, tin-antimony, tin-silver, SAC alloys, fluxes, and more. Amerway was recently award- ed ISO 9001 quality certification, and now offers high-quality and high-purity COBAR Balver Zinn products.
Contact: Amerway, Inc., 3701
Beale Avenue, Altoona, PA 16601 % 814-944-0200 Web:
www.amerway.com
See at SMTAI, Booth 1134
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