Solder paste tests for the 'AART' process

The electronics manufacturing arena continuously seeks faster and cheaper methods of assembly of electronic components on the Printed Circuit Board (PCB). This scenario has led to the development of the Alternative Assembly and Reflow Technology (AART) process. AART integrates the assembly of through hole and surface mount components. The mass reflow of the through hole and surface mount components results in considerable cost benefits due to the elimination of wave soldering process. The AART process requires the deposition of a large volume of solder paste at the through hole sites. The solder volume requirements at the through hole sites are satisfied by depositing solder paste into the Plated Through Holes (PTHs) and on the solder mask around the holes. Due to the significance of solder paste in the AART process, it is necessary to evaluate the solder pastes before their use. This research proposed two solder paste tests that will be required to assess solder pastes for the AART process. The modified slump test is aimed at studying the slump behavior of solder paste deposits at through hole sites. The second test, the pullback test, is designed to study the flow of solder paste into the PTHs upon reflow. Eight solder pastes were studied for their applicability to the AART process. Through this study, it was inferred that the slump and the pullback behavior of solder pastes are dependent on each other. Solder pastes tended to perform well during pullback if they have not undergone slumping during the pre-reflow stage.