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78 The PCB Magazine • April 2016 Table 9: Temperatures used for long-Term Test Based on 1,000-Hour Test Prediction and Input from Suppliers. Table 10: IST Results. performed worse than Laminates A, D, and E. Upon cross sectioning, defects were found in the plated-through hole. Laminate C was not tested. The HATS method differs from IST in that it uses high volumes of hot and cold air to rap- idly heat and cool the sample coupons between -55°C to +150°C. This rapid thermal transition makes HATS a more stressful test than IST. A change in resistance greater than 10% is con- sidered a failure. Samples were subjected to 500, 1000, 1500, and 2000 cycles. Each cycle took 19 minutes. Results are presented below. Laminate B again performed the worse with failures start- ing as early as 150 cycles. A retest of a modified formulation of Laminate B, Laminate B*, did pass 1000 cycles however, Laminate E followed by D provided the best plated through hole reli- ability. Long-Term Testing Using the 1000 hour test data and +25,000- hour test data from T3, T4, and T5, an Arrhe- nius plot of 50% EOL (hours) vs. 1/Temperature (K) was generated for each laminate in Figure 11. Data is still being collected for T1 and T2 long-term thermal reliability of pCb materials