unable to solder a wire to a mini toggle switch

[poiureza]

I'm unable to solder a stupid wire to a mini toggle switch.
I've ruined 4 in a row

If I touch the lug with the iron any longer than half a second, some insulation melts inside and the switch goes kaput (the "off" position gets as low as 150K ohms instead of infinite resistance)

But it needs half a second to melt the solder with my 30W iron at full throttle.

Tried these
http://www.befr.ebay.be/itm/Lot-of-...ltDomain_0&hash=item4abfd7ae1c#ht_5464wt_1014
and these
http://www.befr.ebay.be/itm/5-x-Min...434?pt=LH_DefaultDomain_0&hash=item416afe2f7a


I'm clueless

 

[Relayer110]

Hello poiureza,
I'm not sure what technique you're using to wire those types of switches, but the correct procedure involves preparation first.
Its essential your soldering iron is always kept clean. You should have a sponge soaked in water, but not dripping. Use it to clean off excess solder every time prior to soldering.
One thing I need to mention is that you should NEVER file the tip of the iron. Most beginners are guilty of this and in effect the iron tip has been destroyed and solder will reluctantly stick to it. If this applies to you, then go out and buy a new tip before proceeding with the next lot of instructions.
Next is the preparation of your wires. Its essential that you strip, twist and then tin the wire with solder prior to fixing to anything. Allow it to cool. Then snip off the tinned wire to approximately the length of the switch lugs.
When tinning wires, make sure you strip off enough of the insulation prior to, a bit more than the length of the lug/s and place your iron at the center point (the middle between the end of the insulation and the end of the tip of the exposed wire), and place some solder between the iron and the wire. When you see it melting and the solder spreading through the wire, move the iron slowly and gently along the wire as you're feeding it with solder until you get a uniform coating. Try not using too much solder, otherwise you end up with a blob. Any excess solder can be removed by placing the wire so the tip points to the floor and with the iron cleaned of solder then proceed to run the iron from the insulation downwards and you should see it become uniform. Once done, cut the length you need as I said above.
Next you really need to place the switch into a mini vice or the edge of your desk, weighted with something that won't allow it to move.
Place your clean iron on one of the lugs and then place the tip of the solder in between the iron and the lug. Doing this technique forms a solder bridge and makes it a quicker and cleaner solder joint. The least amount of heat hitting the lug the better, though this takes practice. But if done correctly every time, it won't take long to become proficient to a point you'll rarely destroy anything with heat.
Make sure you don't put too much solder on the lug. If you do, then remove the excess with your iron as you do with the wire.
Do one lug at a time and allow each one to cool down sufficiently.
Also, when doing switches as shown in you links, make sure you start with the center lugs first. Once they are done you can do the top, then you can flip the switch over and do the bottom. Its not critical you solder to the same face of the lugs.
Once you've done the lugs, you're ready to fix the wires onto the switch.
Get you wire ready and get your iron to heat the lug up, then place the wire onto the lug at the same time moving your iron away. Try to minimize the amount of time your iron contacts the lug.
By doing the above you should be able to attach the wire/s to your switch/s neatly and without melting the plastic around the lug/s.
One last tip:
When ever you're done with your soldering iron, make sure you coat it with a generous amount of solder on the tip, carefully place the iron in its stand and turn off the unit. Let it cool with the blob of solder on it.
This will protect the tip when not in use, thus it will extend the life of it.

I hope the above helps.
Regards,
Relayer

 

[tjk3052]

Try filling each lug on the switch with solder first. Then you can strip a small amount of insulation from the wire ends, reheat the lug to melt the solder, stick the wire in, and let it cool. You're more prone to a cold joint doing it this way, but it's not too difficult to get the timing right and avoid that. The other way to avoid turning things to goo is to use higher quality components. Better switches use higher temp potting epoxy, and better wire can have insulation that doesn't melt as easy. Teflon insulation is damn near impossible to melt.

 

[poiureza]

Thank you guys.

Relayer : I do all you described word for word. I even add paper sanding the lugs, all to no avail.
I apply that same technique for pot lugs and I never had a problem so far.
The switches seem incredibly more fragile than pots.

I'll try tjk's method and see how it goes.
And if everything fails I'll resign to get better switches

 

[Lunchie]

Are you heating and reheating them? I have never had a problem frying a switch unless I had to reheat them to fix a boo-boo. I went through a whole bunch of 3pdt switches when I was learning how to build pedals because I kept pulling the lugs out of the switches trying to fix mistakes. I finally found a system that worked for me but it involved some trial and error. Rather expensive trial and error at $3 a pop.

 

[AndyLowry]

Gotta get a heat sink in there some way.

 

[poiureza]

First time heating here Lunchie, no fixing

A heatsink is an idea I've also thought of. The lugs are so small, there's maybe 1-1.5mm between the hole in the lug and the body of the switch. Tough

 

[poiureza]

Try filling each lug on the switch with solder first. Then you can strip a small amount of insulation from the wire ends, reheat the lug to melt the solder, stick the wire in, and let it cool. You're more prone to a cold joint doing it this way, but it's not too difficult to get the timing right and avoid that. The other way to avoid turning things to goo is to use higher quality components. Better switches use higher temp potting epoxy, and better wire can have insulation that doesn't melt as easy. Teflon insulation is damn near impossible to melt.

Could you give me a commercial link to those high temp epoxy switches ? or the Teflon ones ?

 

[poiureza]

Had a tech friend passing by for BBQ last night.
He wouldn't believe me I fried the switches.

While checking with my DMM he kept saying the switches were ok and my DMM needed fresh batteries lol .. until I pulled out my second DMM giving identical results.

Then I shove him my iron and he right down fried yet another switch while trying
After this outstanding performance we kept it to the beers ...
And I think I'll get better switches ...

 

[Suede]

Maybe your soldering iron is too powerful for these mini switches?
Mine is 30W too and haven't had a problem wiring cheap budget switches like these : http://www.banzaimusic.com/Low-Cost-DPDT-on-off-on.html.
You could try them, price-wise they are on the same range, plus they will arrive faster from Germany.

 

[poiureza]

Made in Taiwan ... I wonder if those come from the same factory as Tayda.
They sure look the same. Price is OK but I'd have to buy other parts for making that 10€ shipping worth it.

Just wondering : did anyone meter check their switches after soldering ?
I mean 150Kohms in the "off" position is still a large resistance value and one might not notice anything depending on its use.

 

[limbe]

I don´t understand why people today torture themselves with the old kind of soldering iron that isn´t temperature controlled.When I was a kid that was the only kind available.My dad taught me how to solder with those at an early age so I remember them clearly.As soon as I could I bought a Weller soldering station and have never looked back.When I put a no.7 tip with the right size in the iron,I know the tip will be at 700 F.You still have to know how to solder but it is much,much easier.

 

[poiureza]

I have a Weller WLC200 station but it's power controlled, not temperature controlled.
So you're right, I might need a better iron

 

[poiureza]

OK found it

I ripped a switch apart to take a look at the internals.
There's no insulation anywhere, there's simply a (non-conductive) rocker that pushes down 2 small blades (one for each pole) either side so the related terminals are in contact. Nothing to go wrong there.

Then I noticed something else.
On the outside, the lugs are sealed to the body with some kind of red sealant.
That red sealant is all over the place and all the lugs are connected by that sealant.
And while the sealant is perfectly non-conducting on its own ....

... I'm using a new "soldering water" (that's what they call it here).
It's some corrosive flux that you apply on both parts prior to soldering and prior to tinning. It works great to remove any residual dirt, grease or whatever that could prevent perfect grip between solder and part.

When I put the iron on the lug, I suppose that some of that flux partially melts with the red sealant instead of evaporating.

This solder flux contains zinc chloride ... zinc conducts ...


I made a test without the flux and the switch was perfect after soldering.
OMG where's that face palm emoticon

Live and learn

 

[trev333]

don't feel too bad.. I've melted more than a few of those little blue toggle switches...

solder these days has a flux core and those small terminals are solder friendly.... I don't bother cleaning them... I put a tiny hook on a tinned wire to hold them there with tension..... then a quick dab on the terminal with a wet iron does the trick....

after you've melted the first few it gets easier,,...... at least they're cheap to buy by the dozen...

 

[poiureza]

Yep, applying additional cleaning flux is a habbit I've taken since I soldered my first parts some 30 years ago. I think we didn't have core flux in the solder wire then.

 

[limbe]

If my memory doesn´t fail me,I´ve always used solder wire with flux channels.The only difference was that it had three channels instead of the five that Ersin Multicore has today.
That´s of course no guarantee that it was available where you lived.

 

[Armo]

Have done the same with a 3pdt switch myself. All is not lost however as you can reposition the poles by reheating and pulling then with a pin or long nose pliers. Try not too put pressure on them when heating with iron as the poles tend to sink or move. Experiment on one of your mucked up ones. A light touch is called for.