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March 2014 • The PCB Magazine 43 IST Testing Preconditioning & Test Conditions • Six coupons for each material type will be cycled through 6X @ 260°C assy. • Test the coupons for failure, any failure to be recorded • Capacitance readings will be taken before preconditioning, after preconditioning and at the end of cycling • Any change in capacitance > -6.5% will be considered a failure • Test temperatures cycling will be room temperature to 1500°C in 3 minutes +/- 5 seconds and cooling in approximately 2 minutes • Test cycles will be 1,000. Cycles or a change of 10% in resistance, whichever comes first • Testing done at PWB Interconnect Solutions Test Results Capacitance Analysis Six sections for each of the seven materials tested showed various degree of % change in capacitance value. Material 'A' & 'B' showed ex- cellent results with a maximum of -4.13% and -3.46% change in capacitance. Results for mate- rial 'C' and 'D' had a maximum of -5.40% and -5.05% change, which is still considered accept- able below the maximum allowable percentage change of -6.5%. Material 'RA' showed signs that material degradation had started but percentage change was still below the maximum allowable range. However, material 'E' and 'RB' were at -7.02% and -8.59%. In both of these cases mate- rial damage was observed. See Table 2 for typi- cal capacitance results for 0.8 mm (0.032") test coupon. It was observed that if test coupons have re- tained moisture then we will see an improve- table 3. table 2. BEHAVIOR OF MATERIALS IN THE MANUFACTURING ENVIRONMENT continues