Hi Alejandro,
if you have 400°C at the tip that´s to much. The risk of damaging parts and
boards is quite high and if my memory is right the Pb starts to evaporate in
this temperature range with all the hazards for the operators.
Consider what you have for temperatures in your wave and your reflow.

I know it´s hard to maintain the temperature during the handsoldering with
certain equipment that´s not capable of delivering enough energy in time to
the tip to encounter the loss that you have due to heating the joint and
it´s surrounding and it´s widely seen that operators work with higher temps
to get the job done.

A better way is to use different tips (soldering irons) for different
joints, using one small tip for everything just doesn´t work. We have at
least three different sets at the reworkplace with additional hot air device
for preheating  the units so that there´s no need to go to high in
temperature.
There are other systems available with faster energy transport to the tip
and easy change of tips ( in seconds ) for different tasks.

Keep things under control and you also might measure your temp. at the tip
and how it behaves during soldering to see what you need. 
Preheating is often the answer to many problems.

Good luck

Wolfgang


-----Ursprüngliche Nachricht-----
Von: Becerra Alejandro [mailto:[log in to unmask]]
Gesendet am: Donnerstag, 22. Februar 2001 00:11
An: [log in to unmask]
Betreff: [TN] Temperatures for Rework operation

Hello to All,

I am interested in the optimum temperature for the soldering iron used in
rework operations.
At this moment we use 750F (Aprox. 400C) in the soldering irons for the
touch up operation (Rework operation in line for wave soldering).
Is it correct this temperature or do we use a lower temperature?

Thanks in advance



Alejandro Becerra
Quality Assurance
Phone (915) 841-8439, Fax (915) 841-8401
[log in to unmask]

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