[log in to unmask] wrote:
> 
> Questions from a telecomms designer:
> 
> What is the max continuous operating temperature for a COMPONENT on a vertically
> orientated PCB (without  thermal management) without causing "damage" to the
> substrate?
> 
> Has anyone derived a time/temp situation in reflow that would result in
> significant degregation of the PCB such that personnel might be affected by
> toxic fumes?
> 
> Thanks,   George Wheadon
> 
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The MAX. Component temperature is dependent upon the component 
specification and should be available from the supplier specs.

A typical FR4 PCB is capable of continuously operating at 60-70 deg. C in 
a product. All applications should be designed to stay well below Tg 
temperature of the board material in use.

The PCB can withstand the reflow temperature, 200 - 240 deg. C for a 
short duration which is the reflow cycle of 1.5-2.5 minute. If fumes are 
comming off the FR4 PCB, the temperature is too hot and the epoxy will be 
breaking down and will cause reliability issues in the field.  
-- 
Pratap Singh
Tel./Fax: 512-255-6820
e-mail: [log in to unmask]


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