| FCT Assembly & Fine Line Stencil July 2005 News | Serving
the EMS provider since 1995 |
Article: |
RELIABILITY UPDATE FOR SN100C This report is the second of a five part series highlighting the results of recent reliability testing comparing the Nihon Superior SN100C nickel stabilized tin/copper alloy to tin/lead and SAC alloys. The full report is available by contacting Jim Wertin at jwertin@fctassembly.com. One of the primary concerns in the industry today is whether converting to a lead free process from tin/lead will have an impact on the reliability of the assembly. Much testing has been performed in the last 10 years on lead free joints in anticipation of the potential switch by the industry but there are still concerns about the applicability of the results. Most of the testing has been to procedures developed over time for tin/lead alloys and the issue is whether there will be the same correlation between test results and actual product life cycle of lead free products in the field. As reliability is a complex issue, and not just thermal cycling, a number of tests were performed to attempt to simulate the environment in use. The testing included vibration, thermal shock, HALT testing, salt fog, temperature/humidity, thermal cycling at multiple ranges, hand solder repair with mixed alloys and thermal cycling. HALT testing results will be discussed in this report. The HALT testing was performed by Raytheon Company and is a combined environmental test, which included both thermal cycling and vibration. The thermal cycle was -55°C to 125°C at 20°C per minute ramp with dwells at the upper and lower temperatures of 15 minutes. The boards were exposed to vibration at the upper and lower dwells of 10 Grms increasing 5 G’s after every 50 cycles to a maximum of 55 Grms (see profile below).
Test results indicated the PDIP’s were one of the more reliable components on board in this test. The SN63, SN100C and SAC joints in the manufactured boards had similar failures as indicated in the chart below. The repaired assemblies displayed a large difference with the SAC assemblies having 8 failures and the 63/37 and SN100C having 2 and 3 respectively. The results were tabulated (see Table 1).
SN100C has been patented by Nihon Superior and is offered worldwide through licensed manufacturers including FCT Solder for North America. We offer SN100C for wave solder and lead tinning, reflow solder paste applications, and SN100CL for lead free hot air solder leveling (HASL) of P.C. Boards. We will be including in future newsletters, many of the advantages our current customers have discovered in switching to SN100C as their lead free alloy of choice and we welcome your comments and questions. We look forward to working with you to make your transition to lead free as successful as possible. SN100C has been patented by Nihon Superior and is offered worldwide through licensed manufacturers including FCT Solder for North America. We offer SN100C for wave solder and lead tinning, reflow solder paste applications, and SN100CL for lead free hot air solder leveling (HASL) of P.C. Boards. We will be including in future newsletters, many of the advantages our current customers have discovered in switching to SN100C as their lead free alloy of choice and we welcome your comments and questions. We look forward to working with you to make your transition to lead free as successful as possible. Table 1 MANUFACTURED BOARDS FAILED COMPONENTS BY ALLOY
REPAIRED BOARDS FAILED COMPONENTS BY ALLOY
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