The recent advances in solder bond technology which have occured in the metallurgical, chemical and mechanical fields for both macroconnections and microconnections have caused a rapid acceleration in the use of solder in microelectronics packaging. Relatively soluble metallurgical coatings can be eroded by solder. This process can be controlled by the appropriate heat treatment, by the judicious choice of solder alloy or by the use of an underlying film (such as nickel) which has a slow dissolution rate in the solder. Intermetallic phase formation between active solder components such as tin and soluble metallizations such as gold and palladium can result in a loss of strength at elevated temperatures. At temperatures below 100°C, extrapolations predict adequate strenght for reasonable lifetimes. Oxidation is the chief chemical problem in soldering; the solution of this problem is approached by acid treatment before soldering and by flux and/or the use of reducing atmospheres during soldering. Corrosion problems after soldering are controlled by encapsulation with materials such as RTV silicone rubber. Mechanical problems dominate the design of joints to surface-mounted components as well as the terminals connecting film integrated circuits to printed-circuit boards. New terminals feature strain relief, insertion limiters, shank stiffeners and optimized solder distributions. Surface mounting is benefiting from novel methods of solder placement and the use of surface tension forces to support the components away from the substrate. The solder post thus created is comparatively insensitive to thermal expansion mismatch and other shear strains and enables the film circuitry to be places under the surface-mounted component. In this technique it is crucial to maintain a high surface tension during soldering to prevent collapse of the posts.