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May 2009

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Subject:
From:
Werner Engelmaier /* <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
Date:
Mon, 4 May 2009 11:03:22 -0400
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 Hi Rob, 
No 'baking ' benefit is likely from baking above Tg; however, I am really concerned about solderability as well as damage to the PCB resin, sitting this long above Tg with its large CTE.

Werner


 


 

-----Original Message-----
From: Rob Strecker <[log in to unmask]>
To: [log in to unmask]
Sent: Mon, 4 May 2009 10:54 am
Subject: Re: [TN] PCB baking










I have read the same thing. 105 - 125C around 4 hours.  Our PCB supplier has had 
issues with the pressing time in there process and we are seeing more 
delamination on our boards again.  They have recommended we bake our existing 
stock, 5 boards stacked in the oven, at 180C for 2 hours (including ramp).  My 
main concern is the solderability of the ENIG finish after this baking profile.  
They have shown me some pictures after bake and the gold is darkening.  They are 
asking us if this is acceptable because the boards passed a solder dip test.  We 
are going to bake some boards ourselves, paste and reflow to see the impact.  
Any thoughts on the 180C bake temp?  It seem as though they want the bake 
temperature above the Tg temp (170) not sure why?

Rob Strecker 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier /*
Sent: Monday, May 04, 2009 7:57 AM
To: [log in to unmask]
Subject: Re: [TN] PCB baking

 Hi Ioan,
No there is not, and there really cannot be.
The temperatures used are in the range of 105 to 125-I tend towards 10
5 C, but 
the duration depends on a whole lot of factors. Among them: moisture content 
[bake time ranging from 0 to 24 hours plus], construction [thickness, P/G layer 
location, PCB resin, resin content, PTH/via pitch/diameter], reflow 
process/temperature, etc.
My recommendation is to determine it yourself on some coupons supplied with the 
PCBs.

Werner


 


 

-----Original Message-----
From: Ioan Tempea <[log in to unmask]>
To: [log in to unmask]
Sent: Mon, 4 May 2009 9:25 am
Subject: [TN] PCB baking










Dear Technos,

 

I know this has been oftenly discussed here, but I would like to lively up the 
traffic a little bit...

 

Is there any IPC standard reglementing the bake out time for PCBs, in terms of 
temperature/dwell time?

 

Thanks,

 

Ioan Tempea, ing.

Ingénieur Principal Fabrication / Sr. Manufacturing Engineer 

 

 

30 ans déjà! - Already 30 years!

950 rue Bergar, Laval, Québec, H7L 5A1

t : 450-967-7100 ext : 244

Mtl : 514-990-5762

f : 450-967-7444

[log in to unmask] <mailto:[log in to unmask]> 

www.digico.cc <http://www.digico.cc/> 

P N'imprimer que si nécessaire - Print only if you must

 


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