Prospects of Solder Paste in the Ultra‐fine Pitch Era

Abstract

12 mil pitch processing is achievable with solder paste. It may also be the limit of solder paste printing technology, mainly due to the scooping problem associated with thin stencils. With decreasing pitch size, both smear and insufficiency rate increase. Tapering of stencil aperture helps thick stencil prints, but has an adverse effect on thin stencil printing. Apertures with orientation parallel to squeegee movement result in a higher print defect rate. Overall, the use of fine powders is the most effective means to meet most challenges. It helps in achieving high performance in printability, tack and non‐slump, with acceptable trade‐offs in rheology and tack time. Solder balling may be the primary drawback. The problem may be resolved by using inert reflow atmosphere or via flux chemistry improvements. A metal load of 90.5 to 91% seems to be the optimum for most properties.

Citation

Xiao, M., Lawless, K.J. and Lee, N.‐. (1993), "Prospects of Solder Paste in the Ultra‐fine Pitch Era", Soldering & Surface Mount Technology, Vol. 5 No. 3, pp. 4-13. https://doi.org/10.1108/eb037834