Apparatus for verifying hermeticity of small electronic assemblies

Claim 2

Apparatus for detection of leaks in sealed devices comprising, a test chamber for a sealed device; means for isolating said test chamber from the ambient atmosphere; at least one gas source providing a supply of carrier gas at predetermined pressures; means for providing a flow of said carrier gas from said supply through said test chamber and around said sealed device; detector means for detecting impurities contributed to said carrier gas by said sealed device; means for routing said carrier gas from said test chamber to said means for detecting impurities; and a sub-ambient pressure reference container enclosing at least said means for routing said carrier gas to said detector means.

Claim 3

The invention according to claim 1 and further comprising, a plurality of buffer chambers for isolating said test chamber from the ambient atmosphere; each of said buffer chambers positioned whereby each succeeding one of said buffer chambers surrounds each preceding one of said buffer chambers to provide fluid flow and pressure isolation of said test chamber and said buffer chambers each from the ambient atmosphere and from each other; and said test chamber and each of said buffer chambers having inlet and outlet means for passing gas through said chambers.

Claim 4

The invention according to claim 2 and further comprising, means for providing said carrier gas to said test chamber and said buffer chambers at selected relative pressures; said pressures selected to provide pressure barriers to leaks into said test chamber.

Claim 5

The invention according to claim 1 wherein said gas source further comprises, control valve means for providing a sweep gas at a preselected pressure to pUrge residual atmosphere from said test chamber prior to testing said sealed device; control valve means for continuously purging said buffer chambers with buffer gases at preselected relative pressures during test of said sealed device; said buffer gases having relative pressures to cause a leak between said test chamber and said buffer chambers to effect a flow of gas from said test chamber; control valve means for providing said carrier gas at a preselected pressure to said test chamber during test of said sealed device; and said carrier gas being further routed to said detector where the impurity level of said carrier gas is measured by said detector wherein said impurity level indicates the presence or absence of a leak in said sealed device.

Claim 6

The invention according to claim 4 wherein the respective pressures of said buffer gases flowing through said buffer chambers relative to each other, to said test chamber and to the ambient atmosphere of said test cell are selected to minimize leaks through said buffer chambers between the ambient atmosphere and said test chamber.

Claim 7

The invention according to claim 4 wherein the gas flowing through at least one of said buffer chambers is monitored to provide a self check of the isolation of said test cell from ambient atmosphere and to verify detector indications.

Claim 8

Apparatus for detecting leaks in sealed devices comprising, a test cell containing an inner test chamber adapted to receive sealed device and to isolate it from ambient atmosphere; at least one gas source providing a supply of gas at predetermined pressures; detector means for analyzing the purity of said gas; control valve and other fluid flow and pressure regulating elements connecting said test cell, said detector and said gas sources to provide that a carrier gas at preselected pressure flows around said test specimen through said test cell and to said detector, said detector analyzing the purity level of said gas passing through said test cell and detecting the impurity exuding from a leak in said sealed device; and said control valve and other fluid flow and pressure regulating elements include a vacuum providing device and a sub-ambient pressure reference container that encloses at least said control valve elements routing said carrier gas to said detector.

Claim 9

Apparatus for detecting leaks in sealed devices comprising, a test cell containing an inner test chamber adapted to receive sealed device and to isolate it from ambient atmosphere; at least one gas source providing a supply of gas at predetermined pressures; detector means for analyzing the purity of said gas; control valve and other fluid flow and pressure regulating elements connecting said test cell, said detector and said gas sources to provide that a carrier gas at preselected pressure flows around said test specimen through said test cell and to said detector, said detector analyzing the purity level of said gas passing through said test cell and detecting the impurity exuding from a leak in said sealed device; and said control valve and other fluid flow and pressure regulating elements include a vacuum providing device and a sub-ambient pressure reference container that encloses at least said control valve elements routing said carrier gas to said detector.

Claim 10

Apparatus for detecting leaks in hermetically sealed devices comprising, a test cell with an inner test chamber adapted to provide a receptacle for a hermetically sealed device and to isolate it from ambient atmosphere; at least one buffer chamber wherein the innermost of said buffer chambers isolates said test chamber from test cell ambient atmosphere; each of said buffer chambers positioned whereby each succeeding one of said buffer chambers surrounds each preceding one of said buffer chambers to provide fluid flow and pressure isolation of said test chamber and said buffer chambers each from the test cell ambient atmosphere and from each other; at least one gas source providing a supply of an inert non-radioactive gas at predetermined pressures; said test chamber and each of said buffer chambers having inlet and outlet means for passing gas through said chambers; gas chromatograph detector means insensitive to said inert non-radioactive gas but sensitive to said impurities in said gas for analyzing the purity of said gas; control valve and other fluid flow and pressure regulating elements connecting said test cell and said gas sources so that said gas flows around said test specimen through said test cell and connecting said test cell and said detector so that said detector analyzes the purity level of said gas passing through said test cell and detects only the impurity exuding from a leak in said hermetically sealed device; and said control valve and other fluid flow and pressure regulating elements include moisture and cryogenic traps, a vacuum providing device, and a sub-ambient pressure reference coNtainer enclosing at least the valves routing said inert non-radioactive gas to said detector.

Claim 11

Apparatus for detecting leaks in hermetically sealed devices comprising, a test cell with an inner test chamber adapted to provide a receptacle for a hermetically sealed device and to isolate it from ambient atmosphere; at least one buffer chamber wherein the innermost of said buffer chambers isolates said test chamber from test cell ambient atmosphere; each of said buffer chambers positioned whereby each succeeding one of said buffer chambers surrounds each preceding one of said buffer chambers to provide fluid flow and pressure isolation of said test chamber and said buffer chambers each from the test cell ambient atmosphere and from each other; at least one gas source providing a supply of an inert non-radioactive gas at predetermined pressures; said test chamber and each of said buffer chambers having inlet and outlet means for passing gas through said chambers; gas chromatograph detector means insensitive to said inert non-radioactive gas but sensitive to said impurities in said gas for analyzing the purity of said gas; control valve and other fluid flow and pressure regulating elements connecting said test cell and said gas sources so that said gas flows around said test specimen through said test cell and connecting said test cell and said detector so that said detector analyzes the purity level of said gas passing through said test cell and detects only the impurity exuding from a leak in said hermetically sealed device; and said control valve and other fluid flow and pressure regulating elements include moisture and cryogenic traps, a vacuum providing device, and a sub-ambient pressure reference coNtainer enclosing at least the valves routing said inert non-radioactive gas to said detector.

Claim 12

The invention of claim 8 in which said gas source further provides, means for providing a sweep gas to purge residual atmosphere from said test chamber prior at test of said hermetically sealed device; means for providing buffer gases at preselected pressures to form pressure barriers and to purge said buffer chambers continuously during test of said hermetically sealed device; means for providing a carrier gas at reduced pressure to said test chamber during test of said hermetically sealed device with said carrier gas routed through said test chamber to flow around said sealed device; and said carrier gas being further routed to a detector where the impurity level of said carrier gas is measured by said detector wherein said impurity level indicates the presence or absence of a leak in said hermetically sealed device.

Claim 13

The invention according to claim 8 wherein said apparatus for detecting leaks further comprises, means for providing calibration of said apparatus so that results are correlatable with other leak testers wherein leaks are rated in units such as cc/sec - std atm.