Also realize these balances can usually be leased if you only need to
perform a bake study for a particular PWB.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman
Sent: Wednesday, October 14, 2009 12:14 PM
To: [log in to unmask]
Subject: Re: [TN] Weighing PCBs

Hi Leif - one company that produces capable balances is Mettler. Realize

that many printed wiring boards are too big to fit on the available 
capable balances and you will need to be using a excised sample. The 
balance required for measuring moisture loss/gain needs to have 4 places

of accuracy to make the measure correctly. Good Luck.

Dave Hillman
Rockwell Collins
[log in to unmask]



Leif Erik Laerum <[log in to unmask]> 
Sent by: TechNet <[log in to unmask]>
10/14/2009 11:44 AM
Please respond to
TechNet E-Mail Forum <[log in to unmask]>; Please respond to
Leif Erik Laerum <[log in to unmask]>


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Subject
[TN] Weighing PCBs






Technetters,

We would like to have the capability to weigh PCBs in order to evaluate 
moisture content. IPC-TM-650 2.6.28 (proposal inside IPC 1601 (draft) ) 
suggests I need a scale with accuracy down to 0.0001g. I have a hard 
time finding something and I was wondering if anyone has "real world" 
experience weighing PCBs and what type of scale they use.

I have a 12 layer 8" x 10" board that weighs around 4 oz. If we assume 
for sake of argument that this board has reached it's maximum moisture 
absorption level. After baking this bone dry, what percentage (ballpark)

weight reduction should we see?

Any advice is appreciated.

Thank you.

-- 
Leif Erik Laerum

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