Reliability comparison of Infrared and Vapour Phase soldering

In our experiment the reliability (life-time) of solder joints formed with Infrared (IR) and Vapour Phase (VP) soldering was investigated. A testboard was designed; and fifty pieces of 0603 (1.5 × 0.75 mm) size chip resistors were soldered onto it. For the soldering, profiles with the same Qη factor (1 200 s·K) were set for both the IR and VP method. After soldering, samples were aged by TS and HAST (Thermal Shock and Highly Accelerated Stress Test) to determine the expected lifetime. The mechanical strength of the solder joints was characterized by shear-strength measurements, which were carried out on as-reflowed and on aged samples too. The shear strength was measured according to industrial standards; the shearing speed was 100 μm/s. Based on the measured shear strength values and the expected lifetime calculations, the reliability of the solder joints formed with Vapour Phase soldering proved to be better than those formed with Infrared soldering.