Device plastic encapsulants

Higher thermal stability so that the higher Junction temperatures of today s and tomorrow s devices will not be limited by the thermal degradation of the plastic encapsulant. 

M. Isagawa, Y. Iwasaki, and T. Sutoh, Deformation of A1 Metalization in Plastic Encapsulated Semiconductor Devices Caused by Thermal Shock, 18th Annual Proceedings, Reliability Physics, 1980, pp. 171-177. 

Enhancement of Gold—Aluminum Wirebond Reliability in Plastic Encapsulated Very Large Scale Integration (VLSI) Devices Through C—Br Bond Stabilization... 

Over 95% of all the microcircuits made are packaged in plastic, usually a transfer moulded epoxy resin. Changes in packaging technology will occur away from the familiar PDIP (plastic dual-in-line package) to smaller SOT or chip carrier formats but plastics will continue to be the dominant packaging material for cost reasons. At the same time there is a need to improve the reliability of plastic encapsulated devices (PEDs) as they find further use in professional and certain military applications. 

U.K. Patent Application GB 2087 1S9A. Plastic Encapsulated Electronic Devices. 

The number of dots that can be dispensed per unit of time also depends on viscosity. The use of low-viscosity adhesives increases the number of dots that can be dispensed. However, there is a tradeoff between the speed at which the adhesive can be dispensed and the speed of device placement. Most automated component-placement equipment operate faster than adhesive-dispensing equipment. A comparison of the effect of viscosity on dispensing and placement times is shown in Table 4.19 for an 86-lead plastic-encapsulated leadless chip carrier (PLCC). ... 

The decision to rework electronic devices or assemblies depends on the cost of reworking versus the value of the part. Consumer electronics, due to their low cost, are considered throwaways and seldom reworked. For some, such as plastic-encapsulated microcircuits (PEMs) that are produced in high volumes, rework is impractical because of the difficulty in removing the plastic encapsulant without destroying the components. However, for high-value assemblies, such as densely populated PWBs and MCMs, where the final value may be as high as 10,000 or more, the ability to rework is essential. In such cases, rework may be necessary to meet schedules when small numbers of assemblies are produced. 

Devices can be classified by package style, which can either be hermetically sealed (ceramic or metal cans) or nonhermetic (epoxy, sdicones, phenoHcs or plastic encapsulated). Materials employed in most microcircuits will change very slowly if stored in a dry environment at a constant low temperature. 

The success of plastic technology in achieving higher rdliability and mass production has led to wider applications in consumer products such as dectronic calculators, radios, televisions, and video recorders and in industrial products such as personal computers, office automation equipment, and computo Today, more tlum 80% of all semiconductor devices are encapsulated by epoxy molding compounds. 

Since absorption and permeation of water through polymer materials are inevitable, the most serious problem in plastic encapsulated devices is aluminum metallization corrosion in moist atmospheres, which leads to functional failures of the devices... 

Harrison, J. C., Long term reliability of plastic encapsulated devices through control of the encapsulation material. Proceedings of Symposium on Plastic Encapsulated Semiconductor Components, Malvern, 1976. 

Roberts, B. C., Plastic encapsulation of semiconductor devices. Proceedings of the International Conference Plastics in Telecommunications III, IEEE, London, 1981. 

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