Metal Finishing Guide Book

2011-2012 Surface Finishing Guidebook

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ZCT Reference As plated Betatec Pressure cooker 4 h Pressure cooker 8 h As plated Pressure cooker 4 h Pressure cooker 8 h 0.34 sec 0.36 sec 0.81 sec 0.33 sec 0.35 sec 0.80 sec Table 3: Results Demonstrating no Loss to Solderability After Post-Dip Treatment Steam-aging: The "pressure cooker test" is used to promote corrosion, diffusion, and deposit cracking. This test was conducted for a duration of 8 hours, after which contact resistance measurements were carried out. The pressure cooker test parameters included: ➢high temperature ➢high humidity ➢high pressure 105 °C 100% RH 1.192 atm Results inferred no increase in contact resistance after 8 hours of exposure. Figure 7 depicts little change in contact resistance values for Betatec 1 and 2 test samples, before and after the pressure cooker test, using the very low tracking force of 5cN. SOLDERABILITY STUDY This study was carried out to confirm that Betatec post-dip would not effect sol- derability properties. The gold thickness was reduced to 0.1 µm for these sol- derability tests. The lead-free alloy SAC (SnAgCu) was used as solder with the following con- ditions: Solder Temperature Density Immersion time Sensitivity Submergence Velocity SnAgCu 245°C 7.5 mg/mm3 10 s 2.5 3 mm 21 mm/s All tests were conducted in accordance with the IEC-68-2-69 standard using a Litton Kester 950 E3.5 flux. Both zero crossing time (ZCT) and wetting force (Fmax) were used to assess solderability, highlighted in Table 3. 152 Fmax 1.91 mN 1.49 mN 0.71 mN 2.07 mN 1.54 mN 0.56 mN

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