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Forum Index : Microcontroller and PC projects : PIC Moisture Sensitivity

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Poppy

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Joined: 25/07/2019
Location: Germany
Posts: 486
Posted: 10:54am 23 Oct 2019
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Hi Folks,


I just ordered and received some IC´s from microchipdirect.com, all of them were just static sensitively packed except the CMM-CPU´s (PIC32MX) they were specially packed for moisture sensitivity, with a declaration concerning further handling and storing (J-STD-033 ->Picture).

Do these guidelines, especially including baking before mounting and mounting within 168 hours after opening the bag, only depend on applying reflow-soldering or will the chips be harmed generally by simply storing or manually soldering outside this time frame?

... meaning, if I just open the bag and keep them stored until I solder them with my iron or hot air ... when ever, right now or a year later?!?!?

I cannot imagine what difference in handling this should make to already mounted IC´s on PCB´s just lying around on my desk and being still working, or is this just necessary for "highliest-professional NASA-purposes"?

   



Edited 2019-10-23 20:55 by Poppy
Andre ... such a GURU?
 
cosmic frog
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Joined: 09/02/2012
Location: United Kingdom
Posts: 302
Posted: 11:19am 23 Oct 2019
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If you are just going to solder with a normal soldering iron don't worry.
But if you are using a reflow station and the chip has taken on moisture it has the risk of "popcorning".

Dave.
 
ryanm
Senior Member

Joined: 25/09/2015
Location: Australia
Posts: 203
Posted: 11:23am 23 Oct 2019
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Moisture sensitivity is all about reflow ovens as far as I know. If the bulk substrate of the package (whatever kind of part it is) is porous it can absorb atmospheric moisture into it. If you then quickly heat the whole part it can "popcorn." Same as throwing river rocks into a campfire.

Never seen it happen in person, I've always just resealed the bags with a bit of duct tape out of precaution. I use MSL above 3 parts so you should be fine. Thermal stress on the bulk of the part will be way less hand soldering anyway.
 
SimpleSafeName

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Joined: 28/07/2019
Location: United States
Posts: 351
Posted: 11:58am 23 Oct 2019
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Just put them in a toaster oven (aka your reflow oven) on low for a few days prior to soldering. I have to dry my 3D filament for the same reason.
 
Poppy

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Joined: 25/07/2019
Location: Germany
Posts: 486
Posted: 01:05pm 23 Oct 2019
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"Popcorning" as what I already read about it myself and I guess this issue depends on completely heating the IC.

So if I thankfully understand you all correctly this does not matter for just heating up the pins during soldering with a normal iron or a heat gun, so doing no reflow at all myself!?!?

And what about the time frame for soldering?
Edited 2019-10-23 23:05 by Poppy
Andre ... such a GURU?
 
cosmic frog
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Joined: 09/02/2012
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Posts: 302
Posted: 07:20pm 23 Oct 2019
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Take as long as you want if just soldering the pins.
 
Poppy

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Joined: 25/07/2019
Location: Germany
Posts: 486
Posted: 07:21pm 23 Oct 2019
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Thanks!
Andre ... such a GURU?
 
CaptainBoing

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Joined: 07/09/2016
Location: United Kingdom
Posts: 2171
Posted: 11:21pm 23 Oct 2019
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my kid works in this industry with GE and they have hell an' all problem with SMD caps popping in re-flow and changing over time
 
Poppy

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Joined: 25/07/2019
Location: Germany
Posts: 486
Posted: 10:50am 24 Oct 2019
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  ryanm said  If you then quickly heat the whole part it can "popcorn."


  CaptainBoing said  my kid works in this industry with GE and they have hell an' all problem with SMD caps popping in re-flow and changing over time


... and on worst case scenarios they start a party:

https://www.youtube.com/watch?v=YfdLh0MHqKw

Andre ... such a GURU?
 
CaptainBoing

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Joined: 07/09/2016
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Posted: 08:02pm 24 Oct 2019
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dammit. you do know it's not possible to "un-see" things.. i am never going to get that out of my head now  
 
Poppy

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Joined: 25/07/2019
Location: Germany
Posts: 486
Posted: 08:32pm 24 Oct 2019
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I know, I know ... I am suffering with You  

This so damned ... great to watch      
Damned Popcorn  
Andre ... such a GURU?
 
Paul_L
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Joined: 03/03/2016
Location: United States
Posts: 769
Posted: 12:01pm 27 Oct 2019
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My generation had Spike Jones.

Then came the frug, disco, and Tiny Tim.

Now we have pop corn.

What else is new?
 
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