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Do yo have to bake unused bare boards or just Vacuum Pack?

Views: 1517

aj

#43515

Do yo have to bake unused bare boards or just Vacuum Pack? | 23 August, 2006

rgd's

aj...

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#43561

Do yo have to bake unused bare boards or just Vacuum Pack? | 24 August, 2006

It depends. What is: * Storage environment and period * Board laminate, epoxy, and copper thickness of PTH * Down stream process * Etc

FR4 0.062" thick boards absorb between 0.08 to 0.1%Wt of moisture within a 24 hour period, and 0.2 to 0.23%Wt in 2880 hours (120 days). These measurements were carried out under environmental conditions of 20*C (max. variation 1*C) and 50%RH (max. variation 3%), using specimen sizes of 40mm x40mm, and FR4 with a 43% resin content. (Some PCB materials absorb up to about 6 times as much under similar conditions). [F Frimpong]

As an alternative to baking, consider having your board fabricator package the boards in sealed vapor barrier bags (bulk quantities) immediately after final cleaning & post-lam bake. Keep the boards stored in the sealed bags until just prior to assembly.

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aj

#43566

Do yo have to bake unused bare boards or just Vacuum Pack? | 25 August, 2006

Thanks for reply,

I am mainly concerned when we run a batch of say 200 out of a kit of 400. due to part shortages we might have to revisit the remainder a few weeks later. Its these boards that concern me.

we use enig boards.

aj...

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#43571

Do yo have to bake unused bare boards or just Vacuum Pack? | 25 August, 2006

Our sympathies about the ENIG boards. B:)

So, you cut the end off the barrier bag, take 200 boards, heat seal the end of the bag and restock it, build the 200 boards and ship them, right?

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#43604

Do yo have to bake unused bare boards or just Vacuum Pack? | 27 August, 2006

AJ, We use all ENIG boards. After opening, any remaining boards are kept in low humidity keeping cabinet. I have never experienced a problem using this method I think the longest I have kept them this way is eighteen months. We also store any open trays this way. Mr Fish - why the dislike of ENIG?

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#43607

Do yo have to bake unused bare boards or just Vacuum Pack? | 28 August, 2006

Mr Jarvis One experience with black pad makes you promise never to use ENIG again. It's nice that you have a supplier that has avoided that problem.

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#43632

Do yo have to bake unused bare boards or just Vacuum Pack? | 28 August, 2006

Dave, I have never even seen black pad - even in my subby days. As my wife says whenever I find a good parking spot: "Lucky Darby and his beautiful wife!" This is particularly so if we go to Watto�s - www.sydneypubguide.net/pubs/Watsons_Bay_Hotel_(Doyles).aspx

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#43640

Do yo have to bake unused bare boards or just Vacuum Pack? | 29 August, 2006

So, you find parking at Watto�s!! => "... we've coerced Josh into driving us out to Watson's bay, braving the horrendous parking situation, to visit Doyle's."

Good for you, but you could be parking on a sinkhole: http://www.uwsp.edu/geo/faculty/ozsvath/images/winter_park_sinkhole.htm

It's very easy to ship black pad boards and not even know that you're doing it, until you have a catastrophic field failure. Black pad can often not even show, because many times it appears only at the center of a pad or just catches one edge. It can show on only one board of a lot. Very tricky.

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#43652

Do yo have to bake unused bare boards or just Vacuum Pack? | 29 August, 2006

Dave, The parking is difficult but don't believe the reviewer about the getting a table business. I just walk in and my waiter; Luigi the Unbelievable, goes to my regular table and says, "You! Jackman, Gibson anda McPherson - piss off! Mr Jarvis and his bewdiful wife wish to eat da fish". Who would have thought that such celebrity could be gained via chip attachment. The beer garden and view are fantastic but the food is overated. The only sinkhole that occurs at Watto's is in the wallet.

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#43653

Do yo have to bake unused bare boards or just Vacuum Pack? | 29 August, 2006

Once a rock star, always a rock star, eh bubba? Ozz don't forget stuff like that.

After a half liter of golden merriment, I don't care about how odd the food tastes, I just want to remain agile enough to dodge the sinkholes on the way home.

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