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L. Musiejovsky, H. Schrottmayer, J. Nicolics:
"Solid-Solder Technology for Laser Soldering - An Alternative to Solder Pastes";
Vortrag: 5th Int. Conf. on Brazing, High Temperature Brazing and Diffusion Bonding (LÖT 98), Aachen, BRD; 05.06.1998; in: "DVS Proc. of 5th Int. Conf. on Brazing, High Temperature Brazing and Diffusion Bonding", (1998), S. 278 - 282.

Decreasing size of solder joints are related to increasing quality requirements. High effort has been devoted to the development of quality assurance methods. However, state-of-the-art methods are still unsatisfactorily in the fine-pitch range.
In this paper laser soldering using solder paste and solid solder as well as significant features of both technologies are compared. The infrared radiation (IR) emitted by the solder joint is used for closed-loop controlling of the applied heat levels and for simultaneous quality control. For better understanding and interpretation of the IR signals soldering processes were analyzed with more-stage models allowing to consider the changes of solder geometry during melting and wetting. Deviations between measured and calculated IR signals are discussed for both cases, solder paste and solid solder. It is demonstrated that wetting can be recognized very clearly on IR signals using solid solder technology.