Hi Lance

The maximum time above 200 degrees of 20 seconds makes this part
practically unsuitable for reflow soldering. The heavier parts on your
board will see even lower temperatures, and this will be insufficient
for proper reflow.

Daan Terstegge
Thales Communications
Unclassified mail
Personal Website: http://www.smtinfo.net

>>> [log in to unmask] 06/23/04 02:51pm >>>
Thanks Guy;

I'll pass this info along to the manufacturing engineer.  At present
we
welcome all suggestions.

Thanks again


                        P.  Lance Mayes
                        Mfg. Trainer




Guy Ramsey <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
06/23/04 05:48 AM
Please respond to "TechNet E-Mail Forum."; Please respond to Guy
Ramsey


        To:     [log in to unmask]
        cc:
        Subject:        Re: [TN] Reflow Profile(Temperature and Times)


You could develop a profile with a 20 second excursion from 200
through
205
and back and stay above 180 for a minute. It would be a ramp up and
down
at
about .5 degree per second.  205-180=30 30x2=60 205-200=5 and back
5x2=10
10x2=20. But, what happens to the parts on the board that are difficult
to
heat? That part may have to be hand soldered.

> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Lance Mayes
> Sent: Tuesday, June 22, 2004 5:15 PM
> To: [log in to unmask]
> Subject: [TN] Reflow Profile(Temperature and Times)
> Importance: High
>
> Technetters Hello again;
>
> We are having a problem with a Token crystal oscillator.
> During the month of April there was a fallout spike of plus
> 10% from testing in manufacturing.  The supplier was
> contacted and some defective components returned.  After
> their evaluation they indicated that the components were
> damaged due to over-heating.  They attached a copy of the
> desired temperature profile we should be using.
>
> We ran the mole through the oven and came up with the real
> profile (note, the thermocouple was attached to the body of
> the resonator).  They are having trouble actually
> interpreting the wording of the spec, especially when
> compared to the recommended profile for the solder paste.
>
> The component spec has a cautionary note as follows:
> "Heating conditions shall be within 20 seconds at +230 deg C
> min, but peak temperature shall be lower than +240 deg C.
> The profile figure shows a breakout above +200 deg C and
> states the maximum time above 200 should be 20 seconds.  The
> two statements together seem confusing and we are asking for
> some clarification.
>
> To add confusion to the issue the solder paste spec:
> Qualitek 670I No-Clean Paste (Sn63/Pb37) shows a recommended
> profile for reflow of Minimum Temp 205 deg C ranging from
> approx. 180 deg C with a minimum time of 60 seconds.  Again
> it appears using this paste we cannot meet the component
> reflow profile?
>
> We then looked at our current profile and found the following:
>
> We are above 200 deg C for about 45 seconds, the peak
> temperature is 218 deg C.
>
> Any help/comments would be appreciated.
>
>
>
>
>                         P.  Lance Mayes

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