Author: Paul Wood Company: OK International Date Published: 9/12/1999
Abstract: In Ball Grid Array (BGA), and, more recently, Chip Scale Packaging (CSP) rework environments, the correct deposition of solder paste has always been difficult. There are different ways to apply solder paste, depending on your product and throughput requirements: 1. Manual printing of solder paste using a mini stencil for printing one dedicated pad pattern. 2. Stencil printing using a vision system to assist stencil alignment. 3. Stencil printing using a machine to align the stencil over the pads more accurately. 4. Solder deposition using positive depensement valves to give accurate paste measurements dot by dot. This paper describes the care of solder paste, the different methods for solder paste depositon in rework, and the advantages of solder paste deposition. Key words: CSP, BGA, solder paste.