Some Causes of Problems with Existing SMT Solder Creams and Possible Improvements

Many of the common defects observed when using solder creams can be related to the materials, formulation and blending of the product. Despite the fact that they have been used for the last 15–20 years some of the most serious of these problems remain. A correlation between material parameters and defects is presented. The three most serious defects are identified as Voids, Solder Balls and Residue and Cleanability and the mechanism and occurrence of these are discussed extensively. Suggestions are presented as to material and process improvements to reduce or eliminate the problem areas. Finally the suggested improvements are tabulated to indicate the effects on all the defects originally identified.