1、 Foreword

According to GJB 597a-96 general specification for semiconductor integrated circuits, cjb 548a-96 test methods and procedures for microelectronic devices, gjb33a-96 general specification for semiconductor discrete devices, cjb 128-96 test methods for semiconductor discrete devices and other national military standards, new products of military electronic devices must be subject to "identification and inspection". Only new products that pass the "identification and inspection" can be produced in small or batch. Moreover, in the future, batches of products produced in batches or small batches must also be subject to "quality consistency inspection". Only products that pass the "quality consistency inspection" can be supplied to users, delivered for use, and used in military complete machines or systems such as missiles and satellites.

However, in the "identification inspection" and "quality consistency inspection" specified in the above standards, there are requirements for "high temperature 1000h power on steady-state life test" (also known as "steady-state working life test"). So why must military electronic devices undergo a 1000h long steady-state life test? How to guarantee and improve product quality through experiments? And how to select the best number of steady-state life tests under different or the same temperature conditions. This paper intends to make an analysis and brief introduction.

2、 Electronic devices must undergo high temperature steady-state life test

1. The necessary test items for the quality assessment of electronic devices at home and abroad according to the investigation, all the domestic and foreign electronic device standards have put forward various technical requirements for ensuring the quality, and through various tests to ensure and improve the quality, and these Provisions are obtained through practice, tests and lessons, which are based and in line with the objective law. Practice has shown that the quality of electronic devices can be guaranteed and improved by following the requirements of the standard. Otherwise, the device will fail, delaying the fighter and defeating the whole system. Table 1 lists the life tests and relevant requirements of electronic devices at home and abroad for our comparison and analysis.

It can be seen from table 1 that the working life test and requirements of Chinese military standard electronic devices are the same as those of the US military standard, while China's stricter "seven special" regulations stipulate two 1000h, namely, 1000h of power aging and 1000h of high-temperature storage, which is stricter than the national military standard.

Compared with the European Space Agency, its "identification test" is 2000h, but its failure criterion is relaxed, which is 45 (1) and 30

(1) And 22 (1) third gear. The "delivery inspection" is 1000h, and the criteria are 15 (1), 8 (1) and 5 (1), which is also relaxed. However, by comparing and analyzing the standards of various countries in Table 1, the working life test of electronic devices shall be conducted for at least 1000h without any change.

Harris company of the United States first put forward the scheme of small batch sampling life test in 1993, as shown in Table 2.

It can be seen from table 2 that the sampling number is related to the batch size. If the batch size is large, more samples will be taken, and if the batch size is small, less samples will be taken. The IC manufacturers all over the world carry out a large number of steady-state life tests. For example, Harris conducted the steady-state lifetime of various CMOS devices at 1000h and +125 ℃ in 1990 A total of 18 groups, 22179 PCs, 126 PCs failed: in 1993, 10 groups, 26922 PCs, 24 pcs failed, were tested for 1000h, +125 ℃ high-speed CMOS, epitaxial CMOS, 80 ℃ 86rh and 80 ℃ 85rh microcomputers. The purpose is to ensure the inherent reliability of the device, so as to improve and ensure the application reliability of the military machine.

2. Through the test, problems can be found, and the quality of electronic devices can be improved in time. The work practice shows that electronic devices can find problems and take improvement measures in time in the high temperature 1000h steady-state life test, so as to achieve the purpose of improving product quality.

Some companies in the United States also have failed devices and failed batches during the "quality consistency inspection" of electronic devices, i.e. 1000h, +125 ℃ high temperature steady-state life test. There are also many domestic batches that fail to pass. This means 125 ° C 1000h life test is very important. Here are a few examples to illustrate this problem.

Example 1: a domestic factory conducted 1000h rated power (rated current) life test on photodiodes: it passed at 500h; Passed at 750H; One failed at 1000h, i.e. 22 (1) failed. After careful analysis and improvement of various measures, the factory conducted a 1000h life test on the new batch, reaching 22 (0).

Example 2: a factory in China conducted a life assessment test for transient voltage suppression Diodes: +125 ℃ high temperature reverse bias requirement 22 (0)+ High temperature storage at 150 ℃ requires 36 (0). The test results show that high temperature reverse deflection: 500h pass, 750H fail, 1 branch, 1000h

Another one failed, 22 (2) failed. High temperature storage: 500h pass, 750H pass, and 36 (1) fail after 1000h failure. This is a test of a batch of civilian products, which shows that the reliability of civilian products is low. This also shows the necessity of high temperature life test.

Example 3: a factory in Beijing, China, carried out the assessment and acceptance of the national military standard production line. According to the provisions of the standard, the CMOS devices produced by the production line must undergo a +125 ℃, 1000h steady-state life test. The first test passed after 500h and failed after 1000h. Analysis, research and improvement shall be carried out in the plant, and then another batch shall be produced according to the "seven specialties". The second test passed after 500h and failed after 1000h. Experts inside and outside the factory were called to discuss, analyze and study. After the improvement was made again, another batch was produced according to the "seven specialties". The test passed after 500h and 1000h. According to the acceptance regulations of the "seven special" production line, two more batches of new products were produced. These three batches of new products were all subject to the life test. Three consecutive batches of products passed the life test after 500h and 1000h. After 8-9 months of research, the chief engineer believed that it was reasonable and necessary to carry out +125 ℃ and 1000h aging assessment for electronic devices in accordance with the American military standard and the Chinese military standard at the final acceptance meeting, because of the 500h assessment test, Our factory has passed many times, but the problems existing in the device technology have not been exposed. Only through 1000h high-temperature aging can we fully expose some internal quality problems of the device. Although our breakthrough has delayed the progress, the internal quality of CMOS devices has been improved, and we can rest assured of providing users with products.

Through the comparison and analysis of the tests of new electronic devices by the above three factories, it is proved that the steady-state life test of electronic devices must be carried out at +125 ℃ and 1000h. If the assessment test is conducted under the condition of +125 ℃ and 500h according to some standards, the deep-seated problems of electronic devices cannot be found. Therefore, in order to guarantee and improve the quality of new products, the high temperature 1000h steady-state life test must be carried out for aerospace electronic devices.

3. Reliability test

Electronic device products that have passed "identification inspection" and "quality consistency inspection" shall also undergo "reliability test" to obtain the failure rate a of this batch of devices, that is, the reliability level is level 6 reliability（ λ= 10-6), or level 7（ λ= 10-7) or grade 8（ λ= 10-8）。 "Reliability test" has stricter requirements, more devices, longer time and more costs. Foreign countries also attach great importance to the reliability test of electronic devices. The United States, Japan and other countries invest a lot of money and spend a lot of time on this work, and put forward various test items to ensure the quality of devices. Many semiconductor devices in China also attach great importance to the reliability evaluation test of electronic devices, so as to improve the quality of domestic electronic devices.

① There is an advanced tab process in the United States, which has many advantages. It can improve the quality of devices, improve the production capacity and reduce the production cost Make the package short, small, light and thin, and increase the package density. However, for formal use, 19 reliability tests, or "tab reliability test items", must be carried out on the products produced by this process, as shown in Table 3. Among them, 5 items are assessment tests under 1000h high or low temperature conditions.

④ From 1984 to 1986, many famous "seven special" semiconductor device factories in China conducted reliability evaluation tests for single batch of "seven special" components, most of which were level 6, and a few were level 7 (such as "seven special" CMOS circuits). These tests have greatly promoted the improvement of the quality of domestic electronic devices.

4. In order to ensure the quality of electronic devices, how many times of high temperature 1000h steady-state life tests should be carried out at different or the same temperature? We can select the best test times by comparing the test data of several units at home and abroad.

① The special two-piece integrated circuit for TV (this is a civil product) has passed three 100h examination tests, namely: +85 ℃, 1000h, power on and rated power aging+ 150 ℃, 1000h, high temperature storage+ 40 ℃, 85%~95%rh, 1000h high temperature storage. The integrated circuits of civilian TV sets must pass the 1000h test for three times. Should the integrated circuits used in military products and satellite missiles pass the 1000h test for three times?

② The "seven special" devices that are strictly produced in China should also undergo two 1000h examination tests, as shown in Table 1 and described in the text. Based on the above analysis, the author believes that in the future, the high-temperature steady-state life test of military electronic devices in China should be conducted at least twice for 1000h according to the "seven special" technical conditions, so as to ensure and improve the quality and high reliability of electronic devices.

3、 Concluding remarks

The high reliability and long service life of electronic devices are the key to ensure the successful flight of China's aerospace products and the basis for the quality of systems and subsystems. We must, in accordance with the requirements of the standard, carry out a high-temperature 1000h steady-state life test, ensure and improve the quality of electronic devices, lay a solid foundation, and make due contributions to promoting the further development of aerospace technology and the modernization of national defense. At the same time, it is suggested that leaders at all levels should pay attention to this work, vigorously support this work, increase investment, and improve and ensure the inherent reliability of electronic devices through "identification inspection", "quality consistency inspection" and "1000h life assessment test in reliability test".