NEW MASS SOLDERING PROCESS: CONDENSATION SOLDERING.

Mass soldering operations play an important part in the high reliability and low cost oof many complex electronic equipment systems. A commonly used soldering technique is wave or dip soldering in which a bath of molten solder simultaneously provides both the solder and the heat necessary to form an interconnection. However, frequently the product design does not permit the use of molten solder. An example is soldering wire wrap terminals to a printed wiring board; the terminals must not be coated with solder if subsequent high reliability wire-wraps are to be made to the terminals. In such situations, reflow soldering must be used. In a reflow soldering process, the solder is provided as a paste or solid preform in one step and heat is added in a second step to form the interconnection. Reflow soldering with condensation heating was developed to eliminate the problem with other processes by providing precise temperature control uilizing a fluid whose physical characteristics are ideal for the process. Although condensation heating has a number of applications, including the soldering and fusing of both rigid and flexible circuit boards, the main emphasis in this paper is on mass soldering.