May 1990
·
17 Reads
·
3 Citations
Recent growth in surface mount technology (SMT) assembly has put additional performance demands on fabricators of metal mask stencils used for printing solder paste. Delivery time of a quality stencil is very important. There are occasions when an SMT assembly facility has a line down for lack of a stencil or has an unexpected rush printed circuit board (PCB) assembly job. They need a stencil immediately. Additionally, as people convert present through-hole boards over to SMT boards, there is an intermediate requirement for stencils to produce mixed technology boards having both through-hole as well as SMT components on the same board. Another challenge is technological growth in the packaging sector, which, with the development of fine pitch technology (FPT), is constantly pushing toward higher pad densities. Packages with 20 and 25 mil pitch are becoming more commonplace. Metal mask stencils and printing processes must keep up by offering improvements in printing performance. The response to performance demands and the manufacturing process are discussed.