The thermomechanical stress sensitivity of ball grid array (BGA) solder connections is significantly reduced, when the solder connections solidify in column-like contours after the reflow processa result achieved by using the solder material in tapered openings of a thick sheet-like elastic polymer adhered...http://www.google.com.au/patents/US20030153160?utm_source=gb-gplus-sharePatent US20030153160 - Ball grid array package for enhanced stress tolerance
