Life-span investigation of ICT (in-circuit test) pins

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Scherer Balázs Attila
Department of Measurement and Information Systems

The last phase of the automatic-transmission control unit (TCU) production in the factory of the Robert Bosch Ltd. in Hatvan is the pre-ageing test called BurnIn. To execute the examination, the TCU is laid in a test environment called nest, where it receives such heat and current stress that is expectable during its lifetime. The electrical contacts, that are required for the tests, are ensured by spring loaded ICT pins (or called as needles) placed in the nest. Above the heat and current stress the regular change of the TCUs strains the pins mechanically too, therefore those resistance rise presumably significantly, that influences the result of the BurnIn test. To avoid the wrong test results, the pins with poor condition must be changed during the maintenance-work.

The reason of the maintenance-diffculties is the lack of the necessary control measurements to determine the pin's condition and the shortage of change directives. As the end of the needle's lifetime is only indicated by the row of failed BurnIn test results, it causes high costs in the production. The goal of my work was the creation of the information-base that can help to reduce this cost.

In my BSc thesis I present the BurnIn method used by the Robert Bosch Ltd. in Hatvan and Ingun ICT pins that are the weak points of the test environment. I describe the three different stress types, respectively the measurement results of the brand-new and used pins. Big amount of samples were available to analyse the effect of the heat and current stress, but I had to investigate the pin's reliability change during the mechanical abrasion with an own-designed equipment. In my thesis are the engineering processes of the mechanics and electronics, furthermore the device driver software in detail presented.


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