The reliability of reflow soldering by hot air reflow

The reliability of a solder joint produced on an FR-4 substrate by hot air reflow soldering in SMT (surface mount technology) was investigated. The hot air reflow method is shown to make the temperature of the mounted components and substrate equal to the ambient temperature and does not greatly damage components. The capacitance drift did not change after 700 cycles on MIL-STD-202F(107G), at -65 degrees C to 125 degrees C. The shear strength on the solder joint was not reduced after 700 cycles on MIL-STD-202F(107G), at -65 degrees C to 125 degrees C. The Engelmaier model showed better results against 700 cycles of thermal shock than the average life of the solder. The large heat capacitance eliminates fluctuation of the furnace temperature and makes the surface temperature of the substrate even to ensure overall connection reliability. A stable setting temperature profile can be attained even when a different substrate is used, making this method suitable for diversified small-quantity production.<
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