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:
Purpose - The goal of this work is to evaluate the feasibility of soldering tin-silver-copper balled BGAs using tin-lead-based solder and to investigate the influence of different production parameters on the microstructure of the solder joint. Design/methodology/approach - The soldering of the BGAs was done with various temperature profiles and two conveyor speeds under a nitrogen atmosphere in a full convection oven. One specimen from each temperature/time combination was cross-sectioned. The cross sections were analysed with optical microscopy, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDS) at 30?kV and focused ion beam microscopy (FIB). Findings - The cross sections show a metallurgical bond between the solder and the tin-silver-copper balls of the BGA, even at a peak reflow temperature of 210°C. However, the balls alloy only partially with the solder, as the liquidus of tin-silver-copper balls is 217°C. As soon as the peak temperature exceeds the liquidus of the ball, the solder is totally dissolved in the material of the ball. A reflow profile with a peak temperature of about 230°C on the BGA gives a homogenous reaction of the solder with the ball with a minimum formation of voids. Research limitations/implications - The dependence of varying reflow parameters on reliability requires detailed study. Especially the effect of a partially melted ball on the degradation of the solder joint needs to be investigated. Originality/value - From the findings, it can be said that soldering lead-free balls with tin-lead solder is possible. This is useful during the transitional period that the industry is in at the moment. More and more component manufacturers are changing their components to lead-free, often without notice to the customer. If a production line is still running a tin-lead process it is essential to know how to process these components with tin-lead solder.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1108/09540910510597465
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