The Effects of Surface Finish on Solder Paste Performance - The SequelAuthor: Tony Lentz
Company: FCT Assembly
Date Published: 9/22/2019 Conference: SMTA International
This work explores some of the surface finish - solder paste combinations in more detail with an expanded set of SMT parameters. Three surface finishes were studied including electroless nickel immersion gold (ENIG), organic solderability preservative (OSP), and immersion silver (ISilver). Two lead-free solder pastes were used including a no clean SAC305 solder paste and a water soluble SAC305 solder paste. Three different reflow conditions were tested including a ramp-to-spike (RTS) profile, a ramp-soak-spike (RSS) profile, and reflowing two times through a RTS profile to simulate double-sided surface mount work. Print speeds were varied at 25, 50, and 100 mm/second and printed solder paste volumes measured. Reflow performance was measured including wetting, solder balling, and graping. Quad flat no lead (QFN) components were placed and voiding was measured.
All of the test results were summarized. Discussion of the strengths and weaknesses of each combination of surface finish and solder paste were given with respect to the various SMT parameters. Recommendations were made for optimal combinations of surface finish and solder paste.
surface finish, solder paste, print speed, reflow profile, wetting, solder balling, graping, voiding
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