2 technical articles added by Christopher Associates Inc.
Investigation and Development of Tin-Lead and Lead-Free Solder Pastes to Reduce the Head-In-Pillow Component Soldering Defect.
Mar 06, 2014 | Jasbir Bath, Roberto Garcia - Christopher Associates Inc. Noriyoshi Uchida, Hajime Takahashi, Gordon Clark, Manabu Itoh - Koki Solder
Over the last few years, there has been an increase in the rate of Head-in-Pillow component soldering defects which interrupts the merger of the BGA/CSP component solder spheres with the molten solder paste during reflow. The issue has occurred across a broad segment of industries including consumer, telecom and military. There are many reasons for this issue such as warpage issues of the component or board, ball co-planarity issues for BGA/CSP components and non-wetting of the component based on contamination or excessive oxidation of the component coating. The issue has been found to occur not only on lead-free soldered assemblies where the increased soldering temperatures may give rise to increase component/board warpage but also on tin-lead soldered assemblies....
An investigation into low temperature tin-bismuth and tin-bismuth-silver lead-free alloy solder pastes for electronics manufacturing applications
Jan 24, 2013 | Jasbir Bath, Manabu Itoh, Gordon Clark, Hajime Takahashi, Kyosuke Yokota, Kentaro Asai, Atsushi Irisawa, Kimiaki Mori, David Rund, Roberto Garcia
The electronics industry has mainly adopted the higher melting point Sn3Ag0.5Cu solder alloys for lead-free reflow soldering applications. For applications where temperature sensitive components and boards are used this has created a need to develop low melting point lead-free alloy solder pastes. Tin-bismuth and tin-bismuth-silver containing alloys were used to address the temperature issue with development done on Sn58Bi, Sn57.6Bi0.4Ag, Sn57Bi1Ag lead-free solder alloy pastes. Investigations included paste printing studies, reflow and wetting analysis on different substrates and board surface finishes and head-in-pillow paste performance in addition to paste-in-hole reflow tests. Voiding was also investigated on tin-bismuth and tin-bismuth-silver versus Sn3Ag0.5Cu soldered QFN/MLF/BTC components. Mechanical bond strength testing was also done comparing Sn58Bi, Sn37Pb and Sn3Ag0.5Cu soldered components. The results of the work are reported....