A STUDY OF THE STRENGTH AND SHAPE OF SURFACE-MOUNT TECHNOLOGY LEADLESS CHIP SOLDER JOINTS

A method that directly pulled the components off printed circuit board s was used as a means for testing the bond quality of surface mount te chnology leadless chip solder joints. Components D7243, CC1206, RC1206 , RC1210 and CC1812 were selected for the study. It was found that the ultimate tensile force that breaks a component off the printed circui t board has the potential to be used as a parameter for measuring the quality of the solder joint. The failure modes of the joints were reco rded and are discussed. The effect of solder thickness on the strength of a joint has also been investigated. The shape of joints soldered b y two methods, wave soldering and infra-red reflow, were compared. Joi nts at the two ends of a component produced by infra-red reflow were f ound to be more uniform than the ones produced by wave soldering. A re commendation is made here for the wave soldering approach in achieving uniform solder joints. The effects of solder shape on the joint stren gth were further investigated by finite element analysis. A convex joi nt was found to be marginally more robust than a concave joint.