Soldering a micro switch...

[andyoxon]

What kind of soldering iron would I need to remove a broken microswitch (about 6mm) long from a car remote locking key - and insert a new one.  I have the replacement switches which I bought for about £0.30 each.  (New key = £85)

Andy

[Kim]

Cheapo one with a nice small tip in the ~15W range should do nicely.  I'd avoid anything over 20W for fiddly electronics unless it has thermostatic control.

You'll probably want a solder sucker or de-soldering braid to remove the solder so you don't have to try to prise the switch out with one hand while keeping the joints molten with the other hand and holding the board with your third hand.

[ScumOfTheRoad]

I'm not really up to speed on soldering at the moment, however my advice would be to go to Maplin and get an iron with as find a tip as possible. Worth getting something to get the old solder off the contacts - in the past I had a 'solder sucker' which is a rubber bulb with a nozzle - touch the iron to the old contacts, and slurp the solder off. You can also get braids which soak up the molten solder. You'll also need a bit of new solder - it is bought as a wire with flux already in it. Heat up the soldering iron, 'tin' the bit by melting some solder onto it before heating your component and PCB, melt on a bit of solder.

[andyoxon]

Cheers both.  Would this do?  

SOLDERING SET FOR THE ELECTRONICS HOBBYIST: Amazon.co.uk: Electronics & Photo

soldering iron too powerful?

Edit - I could get this 20W (~£5) one as well  Altai 20w Soldering Iron: Amazon.co.uk: Electronics & Photo

one without kit...  
   15W Miniature Soldering Iron Type C : Mains Soldering Irons : Maplin

[andygates]

You'd just need a good hand - don't keep the iron on too long or you cook the surrounding components. 

Put the workpiece in a clamp so you can get to the bits.  Let the iron heat up until it melts a test bir of solder almost instantly.  Touch it to the joint with one hand, and as the solder goes liquid (you'll see it shiver and change shape), use the sucker in the other hand to slurp it away; remove the iron immediately.

I still hallucinate solder boards from my summer working in a solder sweatshop. 

[Kim]

SOLDERING SET FOR THE ELECTRONICS HOBBYIST: Amazon.co.uk: Electronics & Photo

Possibly a bit on the hot side, but shouldn't be a problem for a switch (semiconductor stuff is more sensitive).  I'd say that was a bargain.

If you're not confident of your soldering ability, find a random item of junk electronics and have a go at de-soldering and re-soldering components first.

[MattH]

+1 to Kim's advice.
Also, make sure you have a small bit of solder melted onto the bit of the iron - just enough to wet it. This helps with the heat transfer, and gets the joint up to heat quickly without taking so long that it melts the rest of the board.
 

[tonycollinet]

If you can get at them easily - is it possible to cut the legs of the old switch before un-soldering. It is much easier to remove one pin at a time, than all of them together.

[redshift]

Find some good old-fashioned 60:40 tin+lead solder too, because the lead-free stuff is crap.  If medical, military and aerospace is exempt from RoHS-compliant solder, I don't need to wonder why... 

[Ham]

SOLDERING SET FOR THE ELECTRONICS HOBBYIST: Amazon.co.uk: Electronics & Photo

Possibly a bit on the hot side, but shouldn't be a problem for a switch (semiconductor stuff is more sensitive).  I'd say that was a bargain.

If you're not confident of your soldering ability, find a random item of junk electronics and have a go at de-soldering and re-soldering components first.

Really. Practice. Without wishing to cast nasturtiums, the fact that you are asking what iron to use suggests that the chances of making a cods of it are reasonably high. De-soldering is much harder to do quickly and safely than soldering.

The actual temperature of the iron for a non-temperature controlled iron is likely the same/similar however large or small the iron is, the main difference is the size of the tip and the heat stored in it that can flow into the circuit board and up the legs of the semiconductors, trashing them on the way. Consider, can you cut the leads of the switch on the _other_ side of the board, and solder the new switch to that? if so, you can sand the lead ends and solder to that much more successfully. Even if you can't do that, still consider if you can break or otherwise separate the existing switch so that you can de-solder one lead at a time. Otherwise, trying to desolder multiple connections at the same time makes life more difficult.


Good luck !