Plastic Encapsulated Microcircuits Research Articles

Does ultrasonic cleaning damage components? : B. P. Richards, P. Burton and P. K. Footner. Electron. Prod. 15 (March 1990)

Microcircuit package qualification testing is used to establish the reliability of integrated circuit processes and devices as they relate to part packaging. This paper presents the results of package qualification tests conducted on plastic encapsulated microcircuits (PEMs) and plastic discrete devices (diodes, transistors) used in avionics applications. Highly accelerated stress test (HAST) and temperature cycle (TC) test results, including part failure mechanisms and associated failure rates, are provided. A variety of plastic package styles and integrated circuit functions have been tested. Examples of package styles tested include small outline (SO), plastic leaded chip carrier (PLCC), thin small outline package (TSOP), plastic quad flat package (PQFP) and plastic dual-in-line (PDIP).Manufacturers' devices have been evaluated and various plastic compounds have been compared to determine which provide optimum reliability. The testing showed that package qualification performance of PEMs is affected by type of compound, passivation (including die coat) and die size. HAST failures are caused by moisture penetration of the package while temperature cycle failures result from coefficient of thermal expansion (CTE) mismatch effects.

The Performance of Plastic-Encapsulated CMOS Microcircuits in a Humid Environment

The major portion of this investigation is devoted to accelerated testing of plastic CMOS microcircuits under conditions of high humidity. The test results revealed a high failure rate in sharp contrast to the results of a similar investigation performed on plastic TFL IC's. The program also investigates the effects of coating devices with a common PC card conformal coating and the effects of operation at various bias levels. A comparison is made between the results of short term pressure cooker testing and long term moisture bias fife testing. The results of testing over 1300 devices, representing the product of five (5) manufacturers are discussed. Findings of the Investigation reveal a higher failure rate for plastic CMOS than plastic TTL. Conformal coating proved to be an insignificant moisture deterrent. The results of 15PSIG, 127°, 48-h testing were observed to correlate with 85°C, 85-percent relative humidity (RH), 1000-h results. Also observed was the improved performance of CMOS B series devices in moisture compared to the A series. Removal of moisture from the ambient significantly improved the failure rate indicating that moisture was the prime failure cause.

The microcircuit pacemaker. Space age spin-off to achieve reliability and long life : T. P. Adams AND M. D. Fasano Jr.Proc. Reliability and Maintainability Symp., Washington D. C., p. 360, 28–30 January, 1975

Plastic-encapsulated microcircuits (PEMs) are proposed for use in military systems to reduce cost and eliminate long-lead items such as packages and lids. Encapsulant materials must be evaluated for compatibility with devices and fine-wire bonds, and electrical stability on deposited elements and integrated-circuit devices. Reliability evaluations in screen tests and various temperature/humidity/bias environments are also essential prior to use in advanced packaging.Encapsulant reliability evaluation requires a test vehicle (MCM-C and MCM-L) to identify these key performance characteristics to assure environmental and mechanical protection because no complete multichip test vehicle, however, is available for use. An encapsulant test vehicle in previous work was modified by substituting a Sandia ATC04 chip and a silver-comb-pattern array with varying feature sizes, using only a single nichrome-resistor network, and adding a deposited comb pattern. The unpassivated resistor and a silver-comb pattern offer both a go/no-go and quantitative test for screening encapsulants and the Sandia chip facilitates stress measurements on the die as well as thermal dissipation evaluation with resistance heaters on the chip.An industry-standard encapsulant, Hysol® FP 4450, was modified to improve thermal conductivity. Exact filler selection and loading were optimized, balancing dispensability, wear, and flow characteristics. Control materials (Hysol® FP 4450) and improved, thermally conductive versions were exposed to short-term screen tests, long-term humidity, and elevated temperature storage testing. Thermal conductivity of Hysol® FP 4450 was improved by approximately 200% and both materials were comparable in temperature/humidity/bias and highly accelerated stress testing as well as thermal cycling and elevated temperature storage.