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Moisture sensitive ICs in repairs/refurb

Views: 1535

#69176

Moisture sensitive ICs in repairs/refurb | 6 June, 2013

We keep all moisture sensitive parts in a humidity control enviroment at our main plant, but our return/refurb products building does not have humidity control.

My question: Do moisture sensitive ICs that get hand placed by our refurb/return team need to be in a humidity controlled environment? Since they aren't going into a reflow oven.

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#69178

Moisture sensitive ICs in repairs/refurb | 6 June, 2013

Interesting question, we have only seen issues with PCBs and humidity when they are going through reflow. Are you having issues?

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#69179

Moisture sensitive ICs in repairs/refurb | 6 June, 2013

No issues it was just brought up during an internal audit.

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#69180

Moisture sensitive ICs in repairs/refurb | 6 June, 2013

I think that you will be fine. You don't want to crack the part during it's stay on a high temperature in the reflow oven(thermal shock...thermal stress...). Once you mount the part on the board it will collect moisture again, but it is already processed.

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#69197

Moisture sensitive ICs in repairs/refurb | 7 June, 2013

In thirty years of Electronic service I have never had problems with moisture in boards when hand soldered. I have worked on boards in boxes for defense through industrial control, joy rides etc. Sometimes they some back buried in half an inch of dust 3mm of grease etc. they are basically washed down so there is no dirt grease etc left, looking like new. Then the repair is done. Some of the IC black materials can absorb moisture from the air so before any reflow operation ie the whole board not just a single IC, the board is baked at 80 - 90 C ie below the boiling point of water, so that if there is any moisture ingress it does not turn to steam and blow up the package. In your instance of working on returns in larger volumes take an excess board soak it in water for say 15 minutes , tap it dry then put it in an oven at 120C and if it blows an IC, you will then know it is something to be concerned about.

regards sarason

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#69625

Moisture sensitive ICs in repairs/refurb | 28 June, 2013

If the soldering process isn't heating the whole package up to soldering temp then NO you don't need to keep them DRY (using a soldering iron to fit a QFP for example)....but if the soldering process is done on a rework station or in a manner where the device body is heated close to soldering temp (like BGA / QFN perhaps)then YES you do need to keep the devices dry before they are fitted.

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