Authored By:
Ed Briggs
Indium Corporation
Clinton, NY, USA
Summary
Solder preforms are composed of solder alloys and are designed and manufactured into various shapes and configurations. The solder preform concept is quite simple; however, the applications are very diverse. Solder preforms are used in numerous ways, e.g., from simple PCB rework to high-reliability applications, and from package level to board level assembly. They are used in low-volume applications, as in military electronics as well as in high throughput, high-volume applications, such as smartphones. Preforms are also used in robotics and automated processes and to optimize labor-intensive steps in manufacturing processes such as hand soldering. Solder preforms and solder-cored wire offer an opportunity to increase consistency and decrease cycle times in many manufacturing environments.
This paper will discuss attributes associated within the solder families that the preforms are composed of, offer simple rule of thumb considerations when considering solder preforms, and take a look at various applications, including the automation of hand soldering to improve consistency and reduce cycle times.
Conclusions
Preforms can be utilized in a wide variety of applications from low-volume high-reliability to high-volume lowreliability and from package level to board level. They can be processed in many environments from rapid heating, such as laser or induction, to conventional convection ovens. The number of alloys available in the form of a preform are the most extensive available, including true low temperature (<170 Celsius) reflow. The ability to flux-coat alloys that cannot be flux-cored in wire form also makes them the most versatile of the forms of solder available. In addition, preforms offer the most accurate volume to the precise area needed and with the greatest consistency achievable in a soldering process, which can eliminate testing or inspection steps. Add in automation and reduced cycle times and preforms become a very attractive alternative to hand soldering applications.
Initially Published in the SMTA Proceedings
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