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Liquid Masking Leak Test Method and Fixture

IP.com Disclosure Number: IPCOM000045230D
Original Publication Date: 1983-Feb-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 66K

Publishing Venue

IBM

Related People

Horvath, JL: AUTHOR [+2]

Abstract

A liquid masking fixture is provided which prevents detection of virtual leaks in leak testing of hermetically sealed electronic modules. The fixture allows the cooling fin 13 of the packaging module to be submerged in an inert liquid during the helium soak portion of the leak test. This procedure temporarily covers the cooling fin of the module and does not interfere with the penetration of helium into any real leaks between the cap 11 and the substrate 10 on which a number of LSI chips are mounted.

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Liquid Masking Leak Test Method and Fixture

A liquid masking fixture is provided which prevents detection of virtual leaks in leak testing of hermetically sealed electronic modules. The fixture allows the cooling fin 13 of the packaging module to be submerged in an inert liquid during the helium soak portion of the leak test. This procedure temporarily covers the cooling fin of the module and does not interfere with the penetration of helium into any real leaks between the cap 11 and the substrate 10 on which a number of LSI chips are mounted.

Hermetically sealed electronic modules are required to undergo leak testing by the use of a tracer gas, such as helium. The tracer gas is forced into the module under pressure, and the module is then placed in a helium detector to determine the size of any leak present. With some modules, external porosity on cooling fins can absorb helium which, during the detection part of the test, gives the appearance of a leak known as the virtual leak. The present method eliminates this problem.

The modules are mounted on pedestals 3 which are carried on a tray 1. The trays are designed to stack onto one another. The stack of trays is placed in a helium pressure chamber 5. Perfluorinated hydrocarbon, an inert liquid, is poured into each tray. The position of the liquid level relative to the seal joint is controlled by the use of an accurate overflow gate 2 and pedestals 3 on which the modules rest. The chamber is then pressurized with...