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Welcome Review Minutes and Action Items from last meeting Project History Determine next steps for committee Review New Action Items Agenda
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Welcome Welcome Introductions Please introduce yourselves Name Company and position What is your expectation of this group/meeting? Assign a scribe to take minutes
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Antitrust Statement There should never be a discussion of the following at IPC meetings: Price or any elements of price or pricing policies, including costs, discounts, etc. Sales or production quotas, territories, allocations, boycotts or market shares. Identified individual company statistics, inventories or merchandising methods. Particular competitors or customers. Commercial liabilities, warranties, guarantees or the particular terms and conditions of sales, including credit, shipping and transportation arrangements. Anything dealing with "arm-twisting," trade abuses or excluding or controlling competition.
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Principles of Standardization In May 1995 the IPC’s Technical Activities Executive Committee (TAEC) adopted Principles of Standardization as a guiding principle of IPC’s standardization efforts. Standards Should : Show relationship to Design for Manufacturability(DFM) and Design for the Environment (DFE) Minimize time to market Contain simple (simplified) language Just include spec information Focus on end product performance Include a feedback system on use and problems for future improvement Standards Should Not: Inhibit innovation Increase time-to-market Keep people out Increase cycle time Tell you how to make something Contain anything that cannot be defended with data
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Project History
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Goal Identify or create a test method that could differentiate and predict corrosion resistance of components and assemblies in the field Develop a next generation corrosion test using a modified mixed flowing gas test method for predicting field life of electronic assemblies and materials in G1-GX environments as defined by ISA 71.04-1985 Investigate other corrosion tests, including Flowers of Sulfur, as alternatives to mixed flowing gas tests
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History Alcatel-Lucent published results in 2007 and 2009 for MFG tests on PCBs and PCAs showing the reliable creation of creep corrosion Others had not been able to reliably produce creep corrosion in MFG Task group began investigating the Alcatel- Lucent modified MFG test as a possible creep corrosion test
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MFG Tests Three different MFG chambers Alcatel-Lucent CALCE Battelle Identical test conditions, coupons and materials Tightly specified MFG operating procedures Experienced PIs
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Validating Alcatel-Lucent results Conditions from APEX2007 paper: Unbiased (no applied voltage) Keep same parameters from first test H2SH2SSO 2 NO 2 Cl 2 ALU International 1700 ppb*200 ppb 20 ppb *Normally 100 or 200ppb for test
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Test Coupons Custom Alcatel-Lucent test coupons (same as 2009 experiments with includes PTH
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Materials for Validation Tests Controls: – Bare copper – SnPb HASL Test samples: – OSP – Immersion silver (immAg) – ENIG
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Preconditioning Precondition with solder assembly processes SMT print and reflow Wave solder RO and OR fluxes Masked areas to create interfaces
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Sample Analysis (after testing) 1.Visual inspection 2.Mass change measurement 3.Determination of chemical composition of corrosion products 4.Removal of corrosion products followed by additional surface inspection 5.Measurement of corrosion rate in angstroms
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Different Types of Corrosion Observed Fiber assisted corrosion [Immersion Silver–day 5 Discoloration [Bare Copper –day 5] Discoloration Creep [Immersion Silver–day 5] Creep White Patina [Bare Copper –day 10] White Patina Flaking [Immersion Silver–day 20] Flaking Green Patina [Bare Copper –day 5] Green Patina
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Results Board TypeDay 5Day 10Day 15Day 20 Cu Cu-OR Cu-RO SnPb SnPb-OR SnPb-RO OSP OSP-OR OSP-RO ImAg ImAg-OR ImAg-RO ENIG ENIG-OR ENIG-RO DiscolorationCreepWhite Flaking Green 3 out of 3 1 out of 3 2 out of 3 Creep Corrosion Results - CALCE
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Board TypeDay 5Day 10Day 15Day 20 Cu Cu-OR Cu-RO SnPb SnPb-OR SnPb-RO OSP OSP-OR OSP-RO ImAg ImAg-OR ImAg-RO ENIG ENIG-OR ENIG-RO Results DiscolorationCreepWhiteFlakingGreen Creep Corrosion Results - Battelle 3 out of 3 1 out of 3 2 out of 3
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Results Board TypeDay 5Day 10Day 15Day 20 Cu Cu-OR Cu-RO SnPb SnPb-OR SnPb-RO OSP OSP-OR OSP-RO ImAg ImAg-OR ImAg-RO ENIG ENIG-OR ENIG-RO DiscolorationCreepWhiteFlakingGreen 3 out of 3 1 out of 3 2 out of 3 Creep Corrosion Results – Alcatel-Lucent
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Large Differences Between Chambers Significant differences in results from different chambers Discrepancies consistent with the historical difficulty of reproducing MFG results consistently Investigated root cause of differences
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Control coupon testing Ag and Cu control coupons tested in each MFG chamber – Found large differences in corrosion Investigation showed Cl 2 to be primary source of difference Cl 2 cannot be monitored in situ Conclusion: Cl 2 levels cannot be controlled sufficiently for chamber to chamber uniformity
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Conclusions MFG is useful for its original purpose of monitoring connector plating finishes MFG is not recommended for testing other components, PCBs, or assemblies for corrosion resistance It does not reliably create the correct failure modes, especially with respect to creep Chlorine levels and other conditions vary too widely from chamber to chamber and cannot be monitored sufficiently for MFG to be considered a sufficiently robust test
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Alternate Test: Flowers of Sulfur Flowers of sulfur is another type of corrosion test that may be useful to differentiate corrosion performance of certain components
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Sulfur (s) Samples High temperature sublimes solid sulfur. Sulfur gas reacts with metal. Corrosion determination: AFM, XPS, visual cross section, microbalance Dependent on temperature Independent of humidity. Accelerated test 2 days = 1 year (@ 65°C) Sulfur (g) Flowers of Sulfur testing—based on ASTM B 809
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Flowers of Sulfur Test Apparatus Sulfur (s) Samples Polycarbonate box within a heating oven; attached fan for air circulation.
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Tests Conditions 0402 10K resistors mounted on PCBs – Normal and corrosion resistant 105C for 20days – Aggressive, based on IBM results No applied biased Preliminary Results No failures Next Steps Extend test period Locate “known bad” parts – Order high risk parts and test many types unmounted
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Next Steps
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Draft position paper on MFG Capture findings Recommend best practices Complete extended FOS test to determine if test can be used for resistors
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Action Item Review
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