Space and avionics applications need a high level of reliability as they face extreme conditions in space. In order to develop components qualified for this application, engineers need to design high reliability into these products. This interview looks at how they achieve high reliability for these products, and also on how a product is qualifies for space applications.
Wolfgang Kuebler, senior marketing manager – high reliability products, Infineon speaks with Abhishek Mutha from EFY.
Q. How is high reliability achieved for products incorporated for space use? What kind of tests and processes are carried out?
To achieve solid reliability, we take silicon wafers from stable production and pack these devices into hermetically sealed ceramic packages. This whole process has to be deeply evaluated and qualified. After the component is manufactured there is the so-called screening which consists of different tests including temperature cycling, burn-in and hermeticity checks. During this screening, the electrical parameters of the component are tested several times to make sure they stay the same. For space applications, a working lifetime of 15 years is expected and there is absolutely no mortality allowed.
Q. What are the kinds of design challenges you face while manufacturing HiRel components?
Manufacturing has to follow very strict rules. To be a space supplier, you need to be certified by a space agency. In Europe, it’s the European Space Agency (ESA) who does certification. They check our production facilities, do paper and factory audit and check if every process is documented. There is a lot of visual inspection in between. Normally, it is much easier to manufacture a component but for space, every step in manufacturing is visually inspected and verified.
Q. What are the kinds of customer challenges that you come across? Are the customer requirements very dynamic in nature?
No, they are not so dynamic. Once a module is designed, a customer would want to stay with it as long as possible. So the major challenge is to produce the component in the required space quality for the next 20 to 30 years even if it is just a few pieces per year.
Q. Could you talk about the kind of rules and regulations for a HiRel product to be qualified for space and avionic applications?
The ESA (European Space Agency) have a qualified part list. Our target is to enter this list because that way the customers trust and pick us. To get a component on this part list, you have to do a so-called evaluation of the components. Even during the build up of the component, the space agency has the right to do a pre-inspection before closing the package of the component. After the component is sealed, evaluation is started. During evaluation, various test are performed like a 3000-hour burn-in or lifetime test. Shock, vibration, temperature and step-stress tests are some other tests performed.
Q. Could you elaborate on how these tests are done?
Temperature step stress test is one where you bring the component to work and increase the temperature in steps of 20 degrees every week until it basically breaks thereby checking the limit of the component. In a power step stress test, power is increased in equal steps. So with all these limits, the specifications are built. So if the component has a limit of 10 watts, the specification would say ‘you are allowed to use this product up to two Watts’. What I mean to say is there is always a very big degradation. Then the components are sent for qualification where you test all the limits that have been set. For instance, if the specification states two watts then the product is tested once more at two watts. Any major variations during this test are noted down. After qualification come all kinds of paper work. Finally, after the entire test, the product is approved and certified. Every two years, a re-certification needs to be done.
Q. That seems like a really long process. So what’s the average time it takes for a component for space uses to be available from scratch?
Let’s say when you have a technology and using that you create a product, it could take roughly one to one and a half year. The evaluation and qualification takes about three-fourth of a year or even one year, and including all the paper work it comes to about one and a half years. If you start a project from scratch, or develop a new technology, it could be several years; probably three to five years.