Process variables in the reflow soldering of surface mount

The variety of surface mount device (SMD) terminations, solder pad shape and surface properties, soldering processes, and properties of solder pastes currently leads to ill-understood and ad hoc methods of specifying component terminations, joint geometry, and soldering parameters and to the consequent risk of reduced process yields for SMD-to-printed-circuit-board connections. The authors attempt to relate the design and process variables to their effects on final joint quality and production process stability. It is pointed out that the migration of manufacturers from vapor-phase to infrared (IR) reflow soldering has gone some way to reduce the occurrences of many of the reflow soldering defects. However, despite the improvement provided with the IR reflow technique, any gains in reducing the number of occurrences per joint of these defects will to a large extent be counteracted by the significant increase in interconnections expected in the near future