Emergence of the forced air convection reflow provides a controllable heating rate. Implementation of the optimized profile requires the support of a heating‐efficient reflow technology with a controllable heating rate. The optimized profile favors that the temperature ramps up slowly until reaching about 180☌. However, a slow cooling rate reduces solder or pad detachment. A rapid cooling rate helps to reduce grain size as well as intermetallic growth, charring, leaching and dewetting. Use of a low peak temperature lessens charring, delamination, intermetallics, leaching, dewetting, and voiding. A minimized soaking zone reduces voiding, poor wetting, solder balling, and opens.
In general, a slow ramp‐up rate is desired in order to minimize hot slump, bridging, tombstoning, skewing, wicking, opens, solder beading, solder balling, and components cracking. A reflow profile is proposed which is engineered to optimize soldering performance based on defect mechanism analysis.
