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humidity in PC packages

jgodfrey

#10909

humidity in PC packages | 21 June, 1999

I am finding that some of our IC's are coming from the supplier with the humidity gauge in the bag reading 10-20%. Has anybody done any tests to determine what humidty level in a package will cause problems during reflow?

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JohnW

#10910

Re: humidity in PC packages | 21 June, 1999

| | I am finding that some of our IC's are coming from the supplier with the humidity gauge in the bag reading 10-20%. Has anybody done any tests to determine what humidty level in a package will cause problems during reflow? | | Sound's to me like your supplier has a problem, you shouldn't be getting anything on them I would think. If your reading 10-20% then they have a heck of a lot of moisture in them..what class of moisture sensative device are they ?? and are they being packed with silica to absorbe the moisture. My first guess is that there is gonna be a problem with them if you don't back them first,but there are better expert's on this in the forum...I'm just an amature. Saying that after the day I've had what the hell...shoot the supplier, bill him for the additional baking and get him to check his process cos they are out of control. at 20% humididty in the bag..your not sure how much is actually inthe component..it maybe a low as 1 or 2% but it maybe the full 20 so there is the dreaded posibility of Popcorning, and even if they don't how long have they been exposed to the moiture ? what effect has it had on the wire bond's in the package.... I really hate monday's you know!!

JohnW

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John Thorup

#10911

Re: humidity in PC packages | 21 June, 1999

| | I am finding that some of our IC's are coming from the supplier with the humidity gauge in the bag reading 10-20%. Has anybody done any tests to determine what humidty level in a package will cause problems during reflow? | Usually a proper manufacturer's vacuum package will hold a very low moisture level. This level will increase over the 12 month shelf life life of the pack and is somewhat dependent on the storage RH. EIA standard JESD22-A112 allows up to 20% RH within the storage environment. We use level 3 and 4 devices and the operators are instructed to accept a slight 20% indication and reject a slight 30%+ indication. We have not had a known popcorn event in many years. Remember that the cards are accurate only at 23 C (+-5) or 73 F. There is a new IPC J-STD (033, as I recall) published in April and concerning the storage and handling of moisture sensitive ICs. It should allow you to audit your and your vendor's procedures. John Thorup John Thorup

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