I 3 3 1 1 1 1 ! n 1 1 1 1 1 1 I 1 I REDUCTION OF SOLVENT USE THROUGH

Conventional soldering typically requires fluxing to promote wetting. Halogenated solvents must then be used to remove the flux residues. While such practice has been routinely accepted throughout the DOE weapons complex, new environmental laws and agreements will eventually phaseout the use of these solvents. Solvent substitution or alternative technologies must be developed to meet these restrictions. SNL, Albuquerque is characterizing and developing alternative fluxless soldering technologies that will reduce solvent use and be compatible with prototypic packaging materials. The program is focusing on controlled atmosphere (vacuum, inedreducing gas, reactive plasma, and activated acid vapor) soldering, metallization a n d i n h i b i t o r t e c h n o l o g y , a n d thermomechanical surface activation (laser, infrared, solid state diffusion, and ultrasonic) soldering. Since there is no universal method that can be applied to every electronic application, the study is defining technological options and limitations. Fluxless soldering would reduce the number of cleaning steps and the subsequent volume of mixed solvent waste. This paper will present an overview of the effects of atmosphere, materials, and processing conditions on attaining a fluxless operation. Examples of applying these technologies to electronic packaging will be given. *This work is supported by the U.S. Department of Energy under Contract DE-AC04-76DP00789.