The moisture uptake time constant for a pwb is going to be different than a card so... There's another factor for a ponder.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Joe Russeau
Sent: Monday, April 23, 2018 8:49 AM
To: [log in to unmask]
Subject: Re: [TN] HIC Card validity?
Good Morning Steve,
Are all cards from the same supplier? Were all three cards sitting in the same area of the room, like next to each other, or were they spread around?
Think of a room like a big environmental chamber. If the cards were in varying locations then it could be possible for there to be variation in humidity. We have mapped chambers before (much smaller rooms) and you can get a huge variation in the humidity from one area to another based on air
flow. So it may be possible if the cards weren't all in the same area. If
the cards were in the same location, then the results you're seeing could be
suspect. The question is which one is correct? I don't know an answer.
You might contact the supplier(s) and ask for any testing that was done showing that those lots represented in the photograph were good.
Best Regards,
Joe Russeau
-----Original Message-----
From: Steve Gregory
Sent: Monday, April 23, 2018 11:25 AM
To: [log in to unmask]
Subject: [TN] HIC Card validity?
Morning all,
I have a question regarding HIC cards. We have one style here in our stock room that we have new in a can. Last Thursday when it was 77% relative humidity, you could take one of the HIC cards out of the can (it was the lower right hand card in the photo) and literally watch the 5% & 10% dots turn pink within 20-minutes. So according to the card, if a sealed MBB that contained MSL3 parts was opened, and 20-minutes later both dots turned pink I would have to bake the parts, correct? The problem with that is that the bag was only opened for 20-minutes, not 168-hours. I'm just asking the question the same way a stockroom clerk would ask it. What are they supposed to do when they see a pink card?
http://stevezeva.homestead.com/HIC_Cards.jpg
BTW, all three cards have been sitting out all weekend and came in with bare PCB's and other parts that we received in. I know the humidity has been at least 77% over the weekend, and it's 57% this morning. All the dots on all the cards should be pink, correct? How much faith do you put in the HIC cards when you see this kind of variability?
Steve
--
Steve Gregory
Kimco Design and Manufacturing
Process Engineer
(208) 322-0500 Ext. -3133
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