Simple, reliable, inexpensive method for gross-leak testing has been devised, based upon the conventional fine-leak technique. The sensitivity ranges from the detection of very large leaks down to leaks of 10 to the minus seven cc helium per sec

Altshuler, T. L.

English

NASA Technical Reports Server

December 1968	 Brief 68-10562 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Reliable Method for Testing Gross Leaks in Semiconductor

Component Packages 
Stopper 
Various semiconductor components such as in-
tegrated circuit modules or cans are adversely affected 
by the presence of a few parts per million of water. 
The components must therefore be hermetically sealed 
to prevent the entrance of water vapor. Leak tests, 
used to determine seal effectiveness, are generally 
divided into two categories: gross-leak tests (for leak 
rates greater than 10 stdcc/sec) and line-leak tests 
(for leak rates less than 10 std cc/sec). Helium leak 
tests (involving a mass spectrometer), which have been
commonly used for leak detection, are limited to leak 
rates of less than 10 std cc/sec. The conventional 
helium leak tests cannot, therefore, be reliably used for 
detecting gross leaks in integrated circuit cans. Bubble 
tests, which are often used for detecting gross leaks, 
are also unreliable. 
A simple, reliable, inexpensive method for gross-
leak testing has been devised, based upon the conven-
tional fine-leak technique. The sensitivity ranges from 
the detection of very large leaks down to leaks of 
(coritin ued oerIeai) 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19680000518 2020-03-12T06:33:51+00:00Z
10 cc helium per sec. The tester includes a sample 
chamber mounted at the mouth of and connected by a 
small orifice to the test chamber, a helium mass spec-
trometer and a high-vacuum pump shown in the dia-
gram. The test chamber is continuously evacuated, 
eliminating the necessity of vacuum cycling for each 
test, greatly simplifying the testing procedure. 
In summary, the test consists of the following steps: 
I. The devices, housed in open bottles, are pres-
surized with helium at 60 psig for at least 2 hours. 
2. Immediately after pressurization, the bottles con-
taining the devices are closed. 
3. A particular device to be tested is removed from its 
bottle and placed into the sample chamber, which 
is then immediately closed with the rubber stopper. 
A high-vacuum pump continuously evacuates the 
test chamber through the helium mass spectrometer. 
The orifice at the bottom of the sample chamber 
limits gas flow so that the gas pressure within the 
test chamber remains at approximately 0.01 micron, 
even though the pressure within the sample cham- 
ber is atmospheric. Helium gas will diffuse out of 
the device into the sample chamber. The resulting 
helium and air mixture will flow through the orifice 
into the mass spectrometer, where the helium leak 
rate is measured. 
4. After gross leak testing is completed, the device is 
removed from the sample chamber, which is then 
purged with nitrogen gas in readiness for the next 
gross-leak test.
Fine-leak testing of the device should be done after 
gross-leak testing. This may be accomplished by merely 
inserting the device into the test chamber (without 
using a sample chamber). The mouth of the test cham-
ber is then sealed with a cap and the helium leak test 
is conducted in the conventional manner. It is not 
necessary to repressurize the device with helium. Also, 
only those devices that do not show gross leaks should 
be subjected to the fine-leak test. Because of the test-
ing range of the gross-leak test, this test might be the 
only one required for many applications. 
Notes: 
Details may be obtained from: 
Clearinghouse for Federal Scientific 
and Technical Information 
Springfield, Virginia 22151 
Price $3.00 
Reference: B68-10562 
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to NASA, Code 
GP, Washington, D.C. 20546.
Source: T. L. Altshuler 
(ERC- 10150) 
Category 01
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Brief 68-10562	 Category 01


Reliable method for testing gross leaks in semiconductor component packages

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