Browse Prior Art Database

Package Sealing by Means of a Pressure Tight Vessel

IP.com Disclosure Number: IPCOM000100824D
Original Publication Date: 1990-Jun-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 63K

Publishing Venue

IBM

Related People

Coffin, JT: AUTHOR [+2]

Abstract

A process is disclosed which will enhance any encapsulation involving a seal that transforms from a liquid state to a solid state through a temperature excursion. Defects and leak paths produced by the pressure differential between the encapsulated cavity and the ambient are eliminated using a pressure tight vessel during the thermal excursion.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 62% of the total text.

Package Sealing by Means of a Pressure Tight Vessel

       A process is disclosed which will enhance any
encapsulation involving a seal that transforms from a liquid state to
a solid state through a temperature excursion.  Defects and leak
paths produced by the pressure differential between the encapsulated
cavity and the ambient are eliminated using a pressure tight vessel
during the thermal excursion.

      The standard procedure for encapsulation is shown in Fig. 1,
which involves cap 1 being placed onto a substrate 2 at room
temperature.  This is followed by a thermal excursion to either cure
or reflow of the seal 3.  If this is done in a convection oven or
belt furnace, the ambient pressure is atmospheric.  The pressure
inside the encapsulated cavity 4, formed by the cap 1, seal 3 and the
substrate 2, increases with temperature, i.e., obeying the ideal gas
law.  The internal pressure within the encapsulated cavity 4 builds
up until it exceeds the restraining force of the surface tension of
the seal 3 material.  The pressure may be released by forming a leak
path 5 through the liquid seal 3. A leak path 5 or internal edge
defect 6 is left, as shown in Fig. 2, when the sealing material 3
does not flow back to its original configuration upon curing or
solidifying.

      By performing the sealing temperature excursion in a
pressure-tight vessel or oven 7, the pressure differential across the
liquid seal 3, as shown in Fig. 3, is eliminated or greatly r...