Method and system for adaptive sampling testing of assemblies

Details Method and system for adaptive sampling testing of assemblies Method and system for adaptive sampling testing of assemblies

2002-06-21

2004-04-06

Niebling, John (Department: 2812)

Semiconductor device manufacturing: process

With measuring or testing

Reexamination Certificate

active

06716652

ABSTRACT:

TECHNICAL FIELD OF THE INVENTION
The present invention relates in general to functional testing of circuit boards, subsystems, and the like and more particularly to a method and system for adaptive sampling testing of assemblies.
BACKGROUND OF THE INVENTION
In manufacturing, it is desirable to reduce production test cycle time while decreasing overall production test capital investment and operating cost. Conventional techniques to perform such savings included performing test program audits and reviews to identify tests that could be eliminated without impacting quality. Acceptance sampling techniques have also been employed in conventional production plants. A common application of acceptance sampling can be found in the material receiving departments of many companies. Received material is divided into lots or groups of units and a sample is drawn from each lot. The sample is tested or inspected and a determination is made as to whether to accept or reject the entire lot based on the tested/inspected sample. The result is that the manufacturing processes that consume the received material are protected from unacceptable levels of quality without relying on 100 percent testing by the receiving department.
However, these conventional techniques can not handle a high demand scenario or shipment deadline. For example, to complete a year end production plan, conventional functional testing had insufficient capacity to handle the product demand bursts. These bursts occur as a result of late arriving material from suppliers and contractors for key modules of a product. The bottleneck at the functional test could not leave enough time during the last few weeks of the year to test, pack, and ship the product. Thus, conventional functional testing techniques are inefficient during product burst demands.
SUMMARY OF THE INVENTION
From the foregoing, it may be appreciated by those skilled in the art that a need has arisen for a testing capability that can handle just in time requirements of product burst demands. In accordance with the present invention, a method and system for adaptive sampling testing of assemblies is provided that substantially eliminates or greatly reduces disadvantages and problems associated with conventional assembly testing techniques.
According to an embodiment of the present invention, there is provided a method for adaptive sampling testing of assemblies that includes selecting an individual acceptable quality level for each of a plurality of test steps of an assembly test. Each of the plurality of test steps is executed on a predetermined number of assemblies. A failure rate for each of the plurality of test steps is determined according to their respective individual acceptable quality levels. A sampling frequency is set for each of the plurality of test steps in response to their respective failure rates. Subsequent assemblies are tested using the assembly test where the assembly test for each subsequent assembly includes only those of the plurality of test steps according to their respective sampling frequency.
The present invention provides various technical advantages over conventional assembly testing techniques. For example, one technical advantage is to run those test steps on an assembly where a previous failure was detected. Another technical advantage is to run those test steps that have previously been successfully passed on only a certain number of subsequent assemblies. Yet another technical advantage is to adjust how frequent a particular test step is executed on subsequent assemblies in response to a pass or failure rate of the particular test. Other technical advantages may be readily ascertainable by those skilled in the art from the following figures, description, and claims.


REFERENCES:
patent: 6167545 (2000-12-01), Statovici et al.
patent: 6265232 (2001-07-01), Simmons
patent: 6483334 (2002-11-01), Hsieh

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