Eliminating Wave Soldering With Low Melting Point Solder Paste
Authors: Mitch Holtzer and Tuck Weng Mok Company: Alpha, an Alent plc Company Date Published: 10/13/2013
Abstract: Wave soldering has been a process of record for countless consumer electronic, automotive, medical, IT infrastructure and desktop computing assembly applications for decades. Miniaturization of components and the need for more functionality have been major drivers for the expansion of surface mount technology in nearly all electronic assemblies. As the number of through hole components used declines, selective soldering has had a tremendous level of growth, further expediting the decline in assemblies built using the wave soldering process. With the advent of lead free soldering in the past decade, SMT reflow temperatures have increased from a typical peak temperature of 210º to 220º C with tin/lead solder, to a typical peak temperature of 240ºC+- 5ºC. With the common use of low melting connectors, audio and video jacks, and other temperature sensitive through hole components, some assemblies still require a wave soldering step. Wave soldering has been eliminated in a large number of applications where both lead free materials and heat sensitive components are used. The enabling technology requires a low melting point solder paste and effective adaptation of pin in paste technology. This paper will give case histories of the successful replacement of wave soldering with low temperature PIP processing. The costs of wave soldering materials, energy, substrate savings and others will be discussed based on actual case histories. Second side SMT reflow using a solder alloy with a eutectic melting point of 138ºC has gained significant technical success. This paper will discuss the cost and technological drivers behind this emerging trend.