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Subject:	Re: Safe processing window
From:	Richard van Beveren <[log in to unmask]>
Reply To:	TechNet E-Mail Forum.
Date:	Thu, 21 Feb 2002 09:58:42 +1100
Content-Type:	text/plain
Parts/Attachments:	text/plain (47 lines)

Dan,

Depends on the solder - the window you suggest may be very roughly OK for
conventional solder but if you are using lead free, then your reflow temp
will certainly need to be much higher (check the specs of the solder).
Also, in my experience, a 2 C/sec ramp up is a little conservative - if you
have a good "soak" or level period before rising to relfow you can even
things out and so ramp up a bit faster (never had troubles with 2.5 C/sec).
2 C/sec ramp down is definitely slow and there are probably advantages in
dropping off much faster, particularly from the reflow peak to well under
liquidous (maybe as fast as 4 C/sec?).

Just some thoughts.

Richard van Beveren
NEWTRONICS PTY LTD

> -----Original Message-----
> From: Dan R. Johnson [SMTP:[log in to unmask]]
> Sent: Thursday, 21 February 2002 08:15
> To:   [log in to unmask]
> Subject:      [TN] Safe processing window
>
> A couple of questions for what has become my best engineering resource.
>
> Management has asked me to provide a re-flow profile for our product, a
> surface mount component built on FR-4 with lead free solder. I am
> reluctant, I would prefer to generate a "safe processing window" type
> document. As manufacturing professionals what do you prefer?
>
> The window would spec ; max 2  C /sec ramp up, max 60 sec dwell above 180
> C, max 220 C peak, and a 2 C/sec max ramp down. Could you live with this?
>
> Many thanks for your help,
> Dan

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