Bias pressure cooker device

Figure 1. Bias pressure cooker-device reliability test, cresol-epoxy-novolac-based molding compounds.

These molding compounds were also used to encapsulate electronic devices for reliability testing. In Figures 4, 5, and 6, stable bromine CEN outperformed "state-of-the-art" resins in the bias pressure cooker device test (BPC), high temperature storage device test (HTS), and the highly accelerated stress test (HAST). 

Figure 4 shows the performance of encapsulated devices under the standard bias pressure cooker device test. The conditions of this test are as follows 100% relative humidity, 15 psig, 250°F, and electrical bias. In this test, the encapsulant based on stable bromine CEN took more than 1000 hours to achieve 50% cumulative failure while the encapsulant based on the standard high purity resins took about 700 hours. 

Figure 4. Bias Pressure Cooker - Device Reliability Test LM324 Quad Op Amp, 121°C, 100% RH, and Bias...

The electronics industry desires improved flame suppressant additives for microelectronic encapsulants due to bromine induced failure. Epoxy derivatives of novolacs containing meta-bromo phenol have exhibited exceptional hydrolytic and thermal stability in contrast to standard CEN resins with conventional TBBA epoxy resins. When formulated into a microelectronic encapsulant, this stable bromine epoxy novolac contributes to significant enhancements in device reliability over standard resins. The stable bromine CEN encapsulant took about 30% more time to reach 50% failure than the bias pressure cooker device test. In the high temperature storage device test, the stable bromine CEN encapsulant took about 400% more time to reach 50% failure than the standard compound. Finally, the replacement of the standard resins with stable bromine CEN does not adversely affect the desirable reactivity, mechanical, flame retardance or thermal properties of standard molding compounds. 

Steady temperature-humidity-bias life (85°C/85% RH) the test specimens are stored for 1000 h or more at 85 2°C and a relative humidity of 85 5% with, depending on the device, a voltage applied either constantly or intermittently. Unbiased autoclave in the steam cooker test, the packaged devices are stored at 121°C under a saturated steam pressure of 0.103 MPa in a sealed autoclave. Depending to the intended application, the test conditions vary from 24 to 48 or 96 h of storage. The electrical measurements are performed at ambient temperature after the devices have been stored at room temperature for 48 h. Biased autoclave the test procedures are similar to the unbiased, except that a bias is applied through hermetic electrical connections. 

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