High Reliability Pb-Free Printed Circuit Board Assembly


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The solderability and reliability of SnAgCu and SnAgCuSbBiNi lead-free solders were assessed against SnPbAg solder on a range of PCB finishes. A novel solderability test has been developed to assess the solder system’s ability to realign when a deliberately inaccurate solder stencil printing process was applied. This has shown to be an excellent way to compare PCB finishes and solders, as well as define process parameters. Electroless Nickel Immersion Gold (ENIG) finish proved to give the best solderability and the optimum process parameters were also found. SnPbAg solder has shown superior thermal cycling performance compared to SnAgCu.



Edited by:

Daizhong Su, Qingbin Zhang and Shifan Zhu




S.D.T. Weller et al., "High Reliability Pb-Free Printed Circuit Board Assembly", Key Engineering Materials, Vol. 450, pp. 9-12, 2011

Online since:

November 2010




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[50] [55] [60] [65] [70] [75] [80] [85] [90] [95] 100 50 60 70 80 90 100 110 Tine Above Liquidus (seconds) % Pad Wet from 40% Solder Misprint ENIG ImAg ImSn % Pad Wetting from 40% Solder Paste Mis-print on ImAg & ImSn Finishes.

DOI: https://doi.org/10.1515/9783110971286.2.1514

[10] [20] [30] [40] [50] [60] [70] [80] [90] 100.

[1] Pass 2 Pass 4 Pass 6 Pass Surface Finish Pre-Ageing Condition % Pad Wet SnPbAg+ImAg SAC305+ImAg SnPbAg+ImSn SAC305+ImSn Thermal Cycles-to-Failure Unreliability SAC-ENIG: SHAPE=3. 75; Scale=2237 @N68 SnPbAg-ENIG: SHAPE=2. 00; SCALE=6274 @N12.

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