Browse Prior Art Database

PLASTIC ENCAPSULATED GaAs MESFET

IP.com Disclosure Number: IPCOM000005510D
Original Publication Date: 1983-Mar-01
Included in the Prior Art Database: 2001-Oct-10
Document File: 1 page(s) / 49K

Publishing Venue

Motorola

Related People

Charles Wetzel: AUTHOR [+2]

Abstract

This disclosure concerns a gallium arsenide depletion-mode low-noise MESFET which is passivated with a DuPont polyimide and encapuslated in a plastic package.

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Volume 3 March 1983

PLASTIC ENCAPSULATED GaAs MESFET

By Charles Wetzel and James Frary

This disclosure concerns a gallium arsenide depletion-mode low-noise MESFET which is passivated with a DuPont polyimide and encapuslated in a plastic package.

   Gallium arsenide devices are very surface-sensitive, however, unlike Si devices, no suitable native oxides of GaAs exist which can act as surface passivants. Therefore, almost all commercially available GaAs FETs are put in relatively expensive hermetically sealed packages. An inexpensive, volume pro- duced part is required by economics to be plastic encapsulated. The process of encapsulation requires that the device be both electrically and mechanically passivated.

   The only commercially available GaAs FET in a plastic package is passivated with silicon nitride. Our process employs DuPont PI2545 polyimide as the passivation layer, epoxy die attach to a Macro-X leadframe, and encapsulation with Hysol 130 resin. Our studies have shown that neither the polyimide nor the plastic packaging degrades the device r.f. performance, while silicon nitride does. This process also offers the advantages of lower cost and easier fabrication.

   A finished device wafer is spin coated with the PI2545 polyimide and partially cured. The layer is then patterned to open bonding areas using a positive photoresist process and curing is completed. The die is then attached with epoxy to a Macro-X leadframe, wire bonded, and finally encapsulated in Hy...