Masters Abstracts (1998)

MURTHY, SHAILESH
(May 1998), Advanced Manufacturing Engineer, Nortel Networks, Billerica, MA

Email: smurthy@nortelnetworks.com

Stencil Printing and Solder Paste Issues for Alternate Assembly and Reflow Technology

The AART process eliminates the necessity for hand/wave soldering, and consequently results in substantial savings through the elimination of capital equipment. In addition, the AART process can provide for the automation of the mixed technology PCB assembly process and can therefore reduce cycle times while concurrently improving the quality of the solder joint. This research effort focused on solder paste and its use in the AART process. Stencil printing was the method of solder paste deposition that was considered. The hole fill that could be obtained was studied and characterized. A series of designed experiments were conducted to systematically evaluate the effect of the various stencil printing parameters on hole fill. As a result of this research, hole fill can be accurately predicted and reliably controlled for boards with a thickness ranging up to 0.125". A fundamental understanding of the solder paste's behavior during the stencil printing and pre-reflow stages was obtained through extensive solder paste tests and rheological studies. Two new solder paste tests were developed to help evaluate solder pastes exclusively for the AART process.