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Alpha Particle Barrier for Flip Chip Bonded Semiconductor Devices

IP.com Disclosure Number: IPCOM000048965D
Original Publication Date: 1982-Apr-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Mondou, ER: AUTHOR [+2]

Abstract

The compound used to form the alpha particle barrier can be varied to tailor-stiffness, and is cleanable to facilitate a rework of the module.

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This is the abbreviated version, containing approximately 90% of the total text.

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Alpha Particle Barrier for Flip Chip Bonded Semiconductor Devices

The compound used to form the alpha particle barrier can be varied to tailor- stiffness, and is cleanable to facilitate a rework of the module.

In the packaging of silicon chips wherein the chips are mounted on a ceramic substrate, it is important to insure a good bond between the ceramic and the chip. Also, as the circuitry on the chip becomes smaller and more closely packed, it is necessary to insure maximum shielding of the chip from alpha particle radiation. These alpha particles can cause false signals and computational errors upon striking the chip. This is particularly pertinent in charge-coupled devices for memory products. Sources of alpha particle radiation are the ceramic material of the substrate supporting the chip and the solder material forming the terminal bond. In forming the barrier it is necessary to insure that any bonding material be essentially free of alpha particle emitters as well as being a good shield against alpha particles emitted by the substrate and the solder.

This composition which can be used to form a barrier consists of (1) zero to 50 weight percent of a microcrystalline wax, (2) zero to 50 weight percent of ultra-pure sulphur-free mineral oil, and (3) one per cent of a dye.

The compound is placed under the bonded chips while the substrate and material are both warmed above the melting point of the wax. The placement of the barrier is aided by capillary action in...