SYMPOSIA PAPER Published: 01 January 1957

Industrial Survey of Paste Solder Alloys


The purpose of this paper is to correlate the scattered data on paste solders for future standardization.

The two basic objectives in using paste solders are (1) to simplify hand soldering through automatic application of paste solder and, (2) to bring about an automatic heating-and-soldering cycle. In the development of paste alloys, many chemical and physical obstacles had to be overcome to reach these objectives. Examples of good and bad applications are illustrated. Also, several interesting applications in various fields are described in detail.

Six typical processes of heating are described and merits of equipment evaluated. Loose fitting joints are to be avoided, and parts designed for a close fitting “microfilm” joint seem desirable. Paste solders and automation methods seem to go hand in hand, but application techniques have been slow to develop. Five fundamental methods of paste solder application are brought out in some detail.

It is suggested that standards for paste solder alloys should be established in line with their ability to withstand corrosion using pure rosin as a standard. Four divisions could be made in accordance with present applications. Also, a numbering system based on the approximate melting point (close to the liquidus) has been suggested as more understandable by industry. A combination of the two would be a key to identify each paste solder alloy.

Author Information

Williams, Harold
Fusion Engineering, Cleveland, Ohio
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Developed by Committee: B02
Pages: 49–57
DOI: 10.1520/STP44108S
ISBN-EB: 978-0-8031-5938-9
ISBN-13: 978-0-8031-6092-7