How do i solder LEDs to a circuit board/pcb?

[jtobrien]

more specifically, in a keyboard lighting mod, how do i get the LEDs connected? like i know to get the old ones out you heat up the solder holding them on and then pull them offf, but for puting new ones on, how do i do so? do i need flux? do i have to clean the circuit board/pcb first?

Thanks in advance!!

 

[awdark]

Hrmm...
My normal brutal method is pry and heat.
But.. the "correct" method is to use some desoldering tools to remove the solder (such as a desoldering braid) then heat the area a little to melt any residual solder and pull the component out.

To solder the led to the circuit board, poke the led through the holes (make sure you get the polarity correct!) Add some flux, melt some solder on it and hope it forms nicely around the legs then trim.

If the legs of the LED does not poke through the circuit board, heat it some while you continue to try to push the legs through. (I stuck the point of my iron into the hole but that might not be a good idea as it can damage the via but im destructive...)

 

[theshadow27]

for puting new ones on, how do i do so? do i need flux? do i have to clean the circuit board/pcb first?

you need a soldering iron and possibly flux core solder. you almost never apply flux separately then the solder, rather it comes inside the solder wire. if you have non-electrical (acid flux) solder, go to radioshack and get electrical solder.

first tin your iron. this means heat it up and melt some solder over the tip. if it doesn’t stick, lightly roughen it with some sandpaper or scotch bright (dont burn yourself!), then try again.

with a little practice, you can heat up both of the pcb pads (that the old LED is soldered to) until the solder is melted (going back and forth between the two rather quickly) then pull out the old LED. place the new LED in the holes that the old one came out of (you wont be able to push it through because the solder is cold) and hold it there with one hand, then flip the board over and heat up the solder pads, again going back and forth between the two. as soon as the solder melts, you will be able to push the LED through the holes (you need not push hard). then you can make sure that it is seated correctly, if it is not: re-melt the pads and push it straight. like i said this takes a little practice, so if you can find an old circuit board and do it a couple times. if you do it right, you do not need to remove the old solder and apply new solder, nor do you need to apply flux. however, if there is not enough solder on the pads, you can (ELECTRONICS SOLDER ONLY!) add a little solder by heating up one pad, then with the iron still on it touch the solder to the pad, and repeat for the other one.

My normal brutal method is pry and heat.
But.. the "correct" method is to use some desoldering tools to remove the solder (such as a desoldering braid) then heat the area a little to melt any residual solder and pull the component out.

if you heat the part up properly, you shouldn’t need to pry. and actually, soldering braid will damage the board more then it will help, so unless you have a major bridge or short, try to stay away from it. heat up/pull out/put in is much better.

best of luck

 

[awdark]

o really? I usually end up with a very hot part and stuck part

 

[Magic H8 Ball]

you need a soldering iron and possibly flux core solder. you almost never apply flux separately then the solder,

Incorrect. Go into any plant that populates PCBs and you will find small bottles of liquid flux and solder that does not have a flux core. For flux to do its job, you really need it on the part as you are heating it, and before the solder touches it.

if you have non-electrical (acid flux) solder, go to radioshack and get electrical solder.

Some electrical grade flux is "acid" flux. It does require washing of the PCB within an hour or so of soldering. It tends to make prettier looking (shinier) solder joints but seems to be getting phased out due to environmental & cost reasons. For the hobbiest, I would recommend a no-clean flux. Though be warned, removing excess no-clean flux (if you are trying to pretty up your board) is a royal PIA. If you want some good quality flux and/or solder, check out anything made by Kester: http://www.kester.com/

first tin your iron. this means heat it up and melt some solder over the tip. if it doesn’t stick, lightly roughen it with some sandpaper or scotch bright (dont burn yourself!), then try again.

Tip cleaners like this: http://www.apogeekits.com/images/Tip Cleaner VTSTC.jpg Are a GODSEND. Forget the stupid sponge that might have come with your iron.

with a little practice, you can heat up both of the pcb pads (that the old LED is soldered to) until the solder is melted (going back and forth between the two rather quickly) then pull out the old LED. place the new LED in the holes that the old one came out of (you wont be able to push it through because the solder is cold) and hold it there with one hand, then flip the board over and heat up the solder pads, again going back and forth between the two. as soon as the solder melts, you will be able to push the LED through the holes (you need not push hard). then you can make sure that it is seated correctly, if it is not: re-melt the pads and push it straight. like i said this takes a little practice, so if you can find an old circuit board and do it a couple times. if you do it right, you do not need to remove the old solder and apply new solder, nor do you need to apply flux. however, if there is not enough solder on the pads, you can (ELECTRONICS SOLDER ONLY!) add a little solder by heating up one pad, then with the iron still on it touch the solder to the pad, and repeat for the other one.

This is a recipie for DEAD PARTS especially with a low wattage non-regulated iron. Either get some desoldering braid, a desoldering iron, or a solder sucker. You will heat soak the board and you can fry sensitive parts in the area you are working on using your method.

if you heat the part up properly, you shouldn’t need to pry. and actually, soldering braid will damage the board more then it will help,

You must not know how to use desoldering braid properly then. I will admit that desoldering braid isn't the easiest to deal with but its better than heat-soaking the whole PCB!