Hi CH,
You do not want 'aggressive' ramp down rates—these cause pad cratering among other things.

 Werner


 

 

-----Original Message-----
From: C H Huang <[log in to unmask]>
To: [log in to unmask]
Sent: Wed, Mar 17, 2010 1:14 pm
Subject: Re: [TN] Reflow Oven Comparison and Qualification


Hi Leland, 
Depends on the size and thickness of your boards, you may need to consider center board support. 
May also want to consider different cooling options if you need more aggressive ramp down rate. 
 
CH 
 
On 3/17/2010 7:34 AM, Leland Woodall wrote: 
> Technetters, 
> 
> We're preparing to purchase eight to ten forced convection reflow ovens 
> to replace equipment we currently have.  We also have plans to attend 
> APEX to check out the varieties available and their features. 
> 
> Being a Quality guy, I'm concerned about items that include: 
> 
> Ability to hold temp within 1 to 2 degrees C 
> Flux management systems 
> Nitrogen control, with expected levels of 50 to 100 O2 PPM (max 500 PPM) 
> Oxygen analyzer type, sampling rate, etc. 
> Seals, exhaust system 
> 8 to 10 zones 
> Board drop sensors 
> Auto width adjust 
> Ability to maintain parallelism from end to end with constant use 
> Ease of maintenance 
> Power consumption, cost of ownership 
> 
> I know that I'm missing some important items.  Will those that have a 
> few minutes please add to my list and elaborate upon what I should 
> investigate?  I'd especially like to hear about personal experiences 
> with critical control designs (what's good, and what should be avoided 
> with all costs). 
> 
> Many thanks, as always! 
> 
> Leland 
> 
> 
> 
> 
> 
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