Jeff, Running a burn-in test (infant mortality) is meant to find and remove the parts that would have failed in the field at first stress. The nature of the test will degrade your parts to some degree. This stress (usually heated while part is in operation ... ok biased) is determined by you, which brings up something else. Burn-in tests are statistical process. The levels and duration of stress, as well as target application (be it solder joints, actual components, entire subsystems ... you get the picture) all have to be determined before hand. The best thing for you to do is: 1) Check with your reliability dept. (I'm assuming that you have one since you've access to an actual burn-in oven) to see what standards apply to your design. Someone left suggestions on acquiring MIL standards (they also left a brief list of sites to search). MIL standards are great if you want to build overkill into your product (which is not a bad thing), however, there are specific standards governing each industry that do not require MIL spec quality, and hence, cost you less. 2) Look at the specifications yourself. Even if you do have a rel dept., and they say they've got everything covered, you'll want to review yourself to double-check their assessment. Try these sites as well (keep in mind you'll have to pay for any standard you need): www.itu.org www.eia.org www.ansi.org I tool around these sites from time to time to see what's changed for specifications. There are more, which I hope others will point out in subsequent mailings. These are three that I have hot linked. 3) Keep on asking questions (like you did on this group). Standards are changing all the time and they often get convoluted. Everyone will have an opinion about burn-in specs. The trick is digging deep enough to figure out what's right and why. 4) This is statistics in action. Everything about it is. Keep that in mind when your reviewing a spec that has in it something like "a temperature is to applied to the device of 85deg C for no less than 24hrs, while biased at -5V." This would be a minimum only. Those folks wrote that with a specific tub curve in mind for a typical case. Your design may be a little more robust with respect to initial failures but not so robust as to negate the need to extend the time and or temp range. You'll need to do some experimenting to define the first leg of the tub curve. Anyway, I rambled enough. I hope this helps (or at least starts a debate). J -- Author: INET: [EMAIL PROTECTED]
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