Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – With rotor
Reexamination Certificate
2003-05-14
2004-11-09
Thai, Luan (Department: 2829)
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
With rotor
C324S076610
Reexamination Certificate
active
06815943
ABSTRACT:
TECHNICAL FIELD
This invention relates to an electric parts testing system and an electric parts testing method.
BACKGROUND ART
In the semiconductor testing process, a semiconductor testing system examines semiconductor devices or the like (hereinafter called DUT (device under test) as well) under test according to various predetermined conditions. Such a semiconductor testing system contains a number of electric parts such as a DUT board, performance board and motherboard for testing DUTs, etc. To ensure accurate measurement of DUTs, etc. by a semiconductor testing system, it is essential that those boards and other electric parts inside the semiconductor testing system operate accurately.
Some conventional semiconductor testing systems additionally contain self-diagnostic devices for testing their own electric parts contained in the systems.
Such self-diagnostic devices supply predetermined quantities of electric power at predetermined timings to individual electric parts inside the semiconductor testing system, or to selective portions of certain electric parts inside the semiconductor system, under predetermined test conditions. Thereafter, the self-diagnostic device observes outputs from those electric parts, or from the selective portions of the electric parts, and determines whether or not those outputs meet predetermined result conditions. If any of the outputs does not meet its result condition, then the self-diagnostic device notifies the user that the corresponding electric part did not satisfy the result condition. In other words, the self-diagnostic device notifies the user that the electric part was judged to be defective.
A number of test conditions are usually related to different test items to distinguish the conditions from each other. Therefore, in most cases, the self-diagnostic device notifies the user of a defective electric part by means of a test item instead of describing its test condition. Then the user can know the test condition used upon judgment of a defect or fault from the test item.
In general, a plurality of test conditions are related to each electric part. Therefore, when a certain electric part is defective, its defectiveness may be pointed out in more than one test item. Similarly, a single test item relates to the defectiveness of a plurality of parts. Therefore, even with a judgment of defectiveness for a test item and a test condition, it is difficult for the user to know which electric part is actually defective.
Such a self-diagnostic device was heretofore contained in a semiconductor testing system. Then, data on the causes of the defectiveness, test items and test conditions connected to the past judgment of defectiveness were stored. The self-diagnostic device showed the user the actual testing results of a particular electric part selected from the data as having been most often judged to be defective according to a selected test item.
However, the electric part most often judged to be defective by a single test item was typically a low quality electric part or a part more commonly used in a semiconductor testing system as compared with other electric parts. In other words, among various kinds of electric parts that otherwise have the same rate of defectiveness, the electric parts used most in the semiconductor testing system were more likely to become defective than the less commonly used electric parts. In addition, electric parts inferior in quality were also more likely to become defective than the other electric parts.
Heretofore, therefore, the self-diagnostic device always showed the user the most commonly used electric part in the semiconductor testing system or a poor quality electric part as being most likely the cause of defectiveness.
As stated above, in general, each electric part is related to a plurality of test items or test conditions, and each test item or test condition is related to a plurality of different electric parts.
In some cases, the electric part that is the actual cause of defectiveness can be a less commonly used electric part in the semiconductor testing system. In other cases, electric parts having been regarded previously as poor quality parts may have been improved in quality and seldom become defective.
If the self-diagnostic device makes judgments on a cause of defectiveness for a single test item in those cases, it will erroneously show the user an electric part that it is not the true cause of defectiveness.
Further, a long period of time was required for the self-diagnostic device to accumulate and be able to use data of actual results of the past causes of defectiveness and actual results of electric parts that have been causes of defectiveness. Therefore, it took a long time after initial use of the semiconductor testing system until data on actual results became available for actual use.
Moreover, once an electric part in its normal condition was misjudged to be the cause of defectiveness, it took a long time to detect the truly defective electric part.
It is therefore an object of the invention to provide, from the initial use, an electric parts testing system and an electric parts testing method capable of bringing to user's attention an electric part with higher probability of being the cause of defectiveness than the conventional one
It is another object of the invention to provide an electric parts testing system and an electric parts testing method capable of detecting the truly defective electric part more quickly than the conventional technique after defectiveness is found by a test of electric parts.
SUMMARY OF THE INVENTION
An electric parts testing system comprises a testing unit to test electric parts for individual condition identifiers assigned for identification of a plurality of test conditions different from each other;
a first memory unit which previously stores estimated causes in relation at least to each said condition identifier, said estimated causes being obtained by estimation as causes of defectiveness of the electric parts;
a second memory unit to store at least one or more of the condition identifiers regarded as fault-connected identifiers when any of the electric parts are judged to be defective; and
an arithmetical unit to calculate a parameter when there are a plurality of said fault-connected identifiers, said parameter being related to the fault-connected identifiers at least for each said estimated cause related to the fault-connected identifiers.
Said parameter is preferred to the number of fault-connected identifiers related to said estimated causes.
Said parameter is preferred to the sum of expected values indicating how often each said estimated cause is estimated to be the cause of defectiveness, or the sum of probabilities of the past causes of defectiveness, said sum being obtained for each said fault-connected identifier.
The electric parts testing system is preferred to further comprise a display unit to display at least one or more of the estimated causes having the largest or smallest parameter value.
The electric parts testing system is preferred to further comprise a display unit to display a matrix of said estimated causes and said fault-connected identifiers to show which of the estimated causes is related to which of the fault-connected identifiers.
Each estimated cause is preferred to be related to expected data obtained by estimation of the nature of the electric part or the test condition, or data on actual results estimated on the basis of the actual past causes of defectiveness, said data on actual results being automatically renewed upon every calculation by the arithmetical unit.
An electric parts testing system includes a server system and a client system capable of exchanging data by mutual communication, comprising:
a testing unit contained in the client system, said testing unit testing electric parts for individual condition identifiers assigned for identification of a plurality of test conditions different from each other;
a first memory unit contained in the server system, said first memory unit previously storing est
Advantest Corporation
Birch & Stewart Kolasch & Birch, LLP
Nguyen Trung Q.
Thai Luan
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