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Old 26-01-2018, 03:26 PM   #1
The Duke
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Default Solder keeps breaking off.

My first attempt at soldering has gone half ways ok but one wire consistently breaks off. I am soldering one of those very small LEDs of about 1 or 1 1/2mm n size. I have successfully soldered the very thin wire to the resistor which is soldered to the LED. The black wire was soldered to the negative pin of the LED and I tested it with the aid of a 9v. battery and it lit up ok. Twice, the black wire has broken off at the soldered joint so what am I doing wrong? The soldering is a bit messy lol. I don’t have flux but the solder is 60/40. In the picture where the LED is lit, I have simply twisted the wire onto the LED.


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Old 26-01-2018, 03:39 PM   #2
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The pictures aren't really clear enough to tell for sure, but it could be that the joint is being allowed to move slightly before the solder has solidified, causing a dry joint.
You could try wrapping the wire round the LED (just once) before desoldering it. Clean the old solder off before trying to resolder it.

I would advise practicing soldering pieces of wire together before tackling other components, such as LEDs, which are easily damaged by excess heat.
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Old 26-01-2018, 03:44 PM   #3
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As a Rog says.
Also increase temperature to around 380 degrees. Ensure irons tip is spotlessly clean - Use a damp sponge to wipe it on when hot.
If you're using Lead Free solder try obtaining some lead content solder 60/40 type with flux inside the solder.
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Old 26-01-2018, 03:46 PM   #4
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Get a helping hand, this will let you use both hands to do the soldering, once its soldered and tested shrink wrap the wire and joint.

one of these..
http://www.ebay.co.uk/itm/Helping-Th...IAAOSwHnFVu28r
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Old 26-01-2018, 04:01 PM   #5
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The joint could be contaminated with grease or some melted insulation. Everything needs to be spotlessly clean.
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Old 26-01-2018, 04:03 PM   #6
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The LED is tiny and despite holding the wire and LED in the grip of the helping hands croc clips, my shaking hands and the iron tip, moves the wire. I was thinking of bending the wire and LED pin into a hook, linking them and squeezing them tight before soldering them. I was also thinking of using the LEDs that just plug in but I wanted to be able to solder them myself and the plug in type is more expensive anyway. I haven’t used flux, just the 60/40 solder.
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Old 26-01-2018, 04:22 PM   #7
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Quote:
Originally Posted by The Duke View Post
<SNIP> I haven’t used flux, just the 60/40 solder.
Attachment 16662
60/40 solder is ideal as I said in post #3.
Also up the irons temperature to at least 380 degrees.
Twisting the bared wire end around the lead of the LED will help stabilise the joint prior to soldering.
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Old 26-01-2018, 04:28 PM   #8
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Looks like I’ll have to start again. I got one of those scrunchy wire scourer type things for cleaning the iron tip but I don’t think they’re much good. I’m changing to a sponge. How do I clean off the solder on the LED pin? I stripped the wires with a wire stripper. Never thought about melting it off, so there’s no melted insulation on the wires.It was much easier than I thought.
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Old 26-01-2018, 04:37 PM   #9
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it might be easier for you to tin the ends first, then bring the 2 pieces together and just touch it with the soldering iron tip, i would practice on scrap bits the different ways of soldering until you find a way that you feel comfortable with,
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Old 26-01-2018, 04:38 PM   #10
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Quote:
Originally Posted by The Duke View Post
<SNIP> I stripped the wires with a wire stripper. Never thought about melting it off, so there’s no melted insulation on the wires. It was much easier than I thought.
Don't use the iron to melt off the PVC insulation on wires. It will form a coating on the tip of the iron and render the tip near on useless. Use wire strippers or a craft knife though the latter is not preferred!
You can obtain solder braid which 'wicks' melted solder up. Or apply a little solder to the tip, hold tip onto the wire to melt the existing solder, remove iron and immediately wipe the wire with a cotton cloth.

Coat (Tin) both items to be soldered, then apply more solder to hot irons tip and place the two wires together, hold in place and touch irons tip onto joint until the two solders melt into one. Feed more solder onto joint if needed. Remove iron and hold joint still for around 5 second until solder solidifies.
Alternatively, as I said previously, Wrap the bared wire end around the LEDs wire then solder the joint.
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