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Desoldering Temperature

Posted: Fri Jan 25, 2013 9:12 am
by enochsmoken
I just bought a used Hakko 472D desoldering station. Never used one before. What is a proper temperature setting for desoldering? And I’ll take any other advice you got.


Re: Desoldering Temperature

Posted: Fri Jan 25, 2013 3:55 pm
by Janitor Tzap

Good question, never really thought about the temperature.
But more as to how long the component is exposed to the heat of the Soldering Iron.

Here's the Wikipedia page on Solder.

Signed: Janitor Tzap

Re: Desoldering Temperature

Posted: Mon Jan 28, 2013 8:19 am
by dacflyer
for solider alone it is about 725F
but depending on the thickness and area of the traces ( ground plane ) they can eat up a lot of heat before the solider flows. and more so if it is a mulit-layer board with thru holes.
some PC boards i have worked on, almost required a soldiering gun ( weller ) before the solider gives way.
you just have to start at about 700F and work your way up, til the solider starts to melt..
practice practice :)

Re: Desoldering Temperature

Posted: Mon Jan 28, 2013 11:01 am
by gerty
Another consideration...the newer lead free solder takes a higher temperature.
I usually give my students an old circuit board and have them desolder some of the components to get the feel of how to set the temperature.

Re: Desoldering Temperature

Posted: Mon Jan 28, 2013 1:35 pm
by enochsmoken
So this is kind of a trial and error thing.

Re: Desoldering Temperature

Posted: Mon Jan 28, 2013 3:04 pm
by haklesup
In your case Trail and error is what it will come down to most likly. While Lead free needs higher temp, a longer dwell time is also appropriate. The optimal temp not only depends on the type of solder but also on the workpiece. For example heavy ground plane connections will require more heat than a thin trace and different circuit boards have different tolerance to heat.

Are you trying to save the part or the PCB. Its not always possible to save both. In many situations, technicians are trained to save the board and trash the part. That means clipping the leads off and then desoldering the leads individually before cleaning and retinning the pads.

I suppose you are working with thru hole assemblies. Also look at how the leads were clipped. If they were trimmed after soldering (hand assembly) they should slide right out of the holes. Machine assembled boards often have a cut that holds the lead in the hole until soldering. In that case, desoldering may still tear up the hole as you try to pull the deformed lead through the blazing hot hole.

My final advice is don't be afraid to use plenty of flux when desoldering, it can always be cleaned off and generally makes the solder reflow more cleanly.

Re: Desoldering Temperature

Posted: Sat Feb 16, 2013 5:04 pm
Generally soldering and un soldering operations require about the same temperature and in theory that depends on the type of solder being used.

Every shop I have worked in with a variable temperature soldering station invariably always had the temperature control crank all the way up, no matter what temperature that was. Not a good practice as excessive heat/temperature will cause damage to both parts and the PCBs. I greatly prefer the stations that have the temperature control in the tip. I have installed 700 degree tips in the stations I have used and have NEVER had to go to a higher temperature tip. Now, some exotic solders may need it, but in over 40 years of electronic shop experience with a 50/50 mixture of soldering and un soldering, I have never had even one instance where that was necessary. 700 deg F should be enough for 99.99999999% of any work you will ever encounter unless they employ a higher temperature solder than is currently in common use. If you find that a 700 deg F iron does not do the job, you most likely need a higher power (Wattage) iron, not a higher temperature iron. Actually, 600 deg F is probably enough for 99 % of that work. There are hundreds of solder alloys and almost every one of them melts below 600 deg F.

Another frequent reason for difficulty soldering or un soldering is the heat transfer from the iron to the work. Any corrosion on the iron will have a very adverse effect on this heat transfer. A clean and freshly tinned iron tip and clean parts with a bit of flux is the best way to ensure that the heat is transferred properly. When you tin the iron, be sure to leave a slight bit of extra solder ("half a drop") on it to help this heat transfer.