We have found that the temperature of 230 deg C doesnot damage the board,
except for slight discoloration.
In very few cases we reflow boards(FR 4)  with a peak of 250 deg C, no
damage to the boards.

We have not faced any warpage problem.

Two thermal cycles are found ok. Sometimes we have gone for three cycles
and no problems.

regards

Sunil Gupta
Tata Telecom Ltd.





"Tempea, Ioan" <[log in to unmask]> on 21/05/99 23:28:48

Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond
      to "Tempea, Ioan" <[log in to unmask]>

To:   [log in to unmask]
cc:    (bcc: Sunil Gupta/TTL)
Subject:  [TN] PCB specs




Hi PCB fabs,

this one's for you.

I'm caught into a lot of fussing about whether my reflowing profiles warp
the boards or not.

What I'd like to know is if the PCB manufacturers recommend optimal reflow
profiles for their boards or, at least, two things:

1. maximum temperatures the boards can withstand without warping or getting
damaged in any way
2. maximum number of thermal cycles the board can take, including double
reflow, waving and some rework

I don't mind if I hear from PCB users either.

Have a good week-end after answering,         Ioan

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