cold solder joints.

[zevon8]

Dont worry if the solder touches the tip of the iron, it often helps create a better heat transfer to the joint, since the tiny pool of solder will flow onto the joint, allowing more surface contact with the iron and the joint. What you need to do is get the tip to touch both the component lead and the pad at the same time, apply solder, let it flow, then remove the iron. On a typical small lead this all takes about 1 second or 2.

This is part of the previous link samcheetah gave, with pictures:

http://www.epemag.wimborne.co.uk/solderpix.htm

It's a very good tutorial, worth a read.

 

[lavenatti]

You should be able to dab a small amount of flux on each bad solder joint and reheat to fix them. I don't think you'll have to remove the old solder, I never do.

I usually push the solder in between the tip of the iron and the component to get a puddle of solder that really transfers the heat quickly.

 

[duffman]

Ok, so after soldering well for a small time period, It has come to the point that the iron tip is black. It is just nasty. Oxidized a bit, and i accidentally let it slip on the carpet and it burned it so there is some residue on it. Wiping it on a sponge doesnt work anymore, and we all now know that sanding i will ruin the tip. How to I clean the soldering iron tip then?

 

[samcheetah]

u should always have a soldering iron stand and be careful with your soldering iron and do not drop it. and try not to work near a carpet. but im afraid that what happened to u happens all the time.

im a bit clumsy with my iron too. infact i have alot of burn marks on my hands these days because im doing alot of soldering. u just have to be careful and dont solder anything if u are tense or u want to do something else.

the bit of my iron turns black when i accedentily touch it with plastic. what i do is that i turn the iron off, let it cool down and then i clean it with a scotch brite pad. ive always been succesful with this method. try and see if it works for u too.

as u say that the tip is oxidized a bit so i would say that this will keep on going and u will see that there will be a point when u wont be able to make good solder joints. so u should start thinking about replacing your iron tip

i hope that helps

 

[evandude]

and don't be too afraid to get solder on your iron tip. you always want to have SOME on there, it transfers the heat a lot better to the joint. even having a VERY slight droplet on there isn't too bad, as long as you don't have so much it's dripping off. When you get right down to it, the whole reason they say not to have a lot of solder on your iron is so that the solder that's going intot he joint is the fresh stuff you're feeding into the joint, which has flux in it which helps clean the joint and make better contact, rather than the solder that's on your iron tip, which has had all the flux evaporated away and so will form poor solder joints. so as long as MOST of the solder going into each solder joint is coming from the spool, not from your iron tip, then you will be fine. Use enough solder on the tip to make the heat transfer fast enough so you don't burn pads off the board, etc. With a reasonably good iron, you should not have to leave the iron on the pad for very long at all. At work here we use the nice weller soldering stations, and you can usually get perfectly good solder joints in under 2 seconds. Given a radio shack iron, it will take slightly longer, but I would say that if it's taking more than like 5 seconds to make a solder joint (at least when you're doing small component leads, such as resistors, etc... larger leads like voltage regulators, etc. will of course take longer) then you would want to change your method.

Oh, and usually when you have black crud on your iron tip, rather than cleaning it off by scouring it with sandpaper or scotch-brite, you can typically scrape it off with a knife. usually it is a very brittle substance, so it crumbles and cracks away pretty easily when you scrape it off.

 

[Sawblade]

Is there any way to plate a soldering iron tip that was never plated before? I have an antique 225w soldering iron (used to have a cloth insulated cord) with a copper tip, but I'm having to polish the tip with some fine sandpaper to remove the dead spots at least once a week.

 

[McGuinn]

So, how do you fix a cold joint?

By reflowing the joint, ensuring proper heating of the legs and pad.
Flux assists this by wetting the components.

 

[Electric Rain]

So, how do you fix a cold joint?

Well, I hear from some people that you can just re-melt the solder. Then it should harden again with a nice, shiny look. But from other I hear the best way is to completly remove the old solder and re-solder the joint.

Rain

 

[Nigel Goodwin]

Well, I hear from some people that you can just re-melt the solder. Then it should harden again with a nice, shiny look. But from other I hear the best way is to completly remove the old solder and re-solder the joint.

It's something I do on a daily basis - there are basically two ways - first you can just heat the joint and apply extra fresh solder, or you can remove all the old solder and resolder it from scratch.

Just reheating the joint won't be very effective, there's no flux to help the solder 'take'.