ISSN:
0954-0911
Source:
Emerald Fulltext Archive Database 1994-2005
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
A study was performed which investigated the wettability of 63Sn-37Pb and 96.5Sn-3.5Ag solders oncopper and gold -nickel plated Kovar ™ using a rosin -based, mildlyactivated (RMA) flux, a water soluble organic acid flux (WS ),and a lowresidue (LR) flux. The quantitative metric was the contact angle, c, measured by the meniscometer /wetting balance technique. The first part of thestudy (Part 1) examined wetting performance following continuous exposure to25°C prior to testing. Then, a preheating step was introduced into the experimentalprocedure after flux application, but preceding the actual wettability test in order to simulate afactory reflow process; these results are presented in Part II of this study. Contactangles for the 63Sn-37Pb solder (215°C) on copper were22±2° with the RMA flux, 12±5° for the WS flux, and31±6° for the LR flux. Increasing the 63Sn-37Pb solder temperature to245°C improved wettability with the RMA and LR fluxes, but no change was observedwith the WS fulx. Theii 96.5Sn-3.5Ag lead -free solder exhibited poorerwettability on copper compared with the 63Sn-37Pb alloy, with contact angles of41±2° (RMA), 63±15°(WS) and39±4°(LR). For the gold -nickel plated Kovar™substrates, the 63Sn-37Pb solder at 215° had contact angles of15±3°, 35±6° and 29±6° for the RMA, WS and LRfluxes, respectively. The values were reduced at the higher test temperature(245°). The 96.5Sn-3.5Ag solder also exhibited good wettingperformance on the gold -nickel plated Kovar™ specimens compared withcopper. Analysis of the interfacial tension parameters, ?SF-?SLand ?LF ,exemplified the importanceof ?LF as well as the condition of the surfaces (?SF ) on wettability performance. A so -called 'combinedanalysis' of the 63Sn-37Pb and 96.5Sn-3.5Ag wettability data oneither copper or gold - nickel plated Kovar™ substrates was used to predict thesolder temperature dependence of wettability for the three fluxes and two base materials.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1108/09540919610777708
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