Still can't solder for beans! :-(

[Nick1911]

Despite my best attempts, I still can not manage to solder a simple component to a PCB. 

I touch one end of the pencil to one side of the component poking though, and hold my solder against the other side, and everything just gets really freaking hot.  Like component-making-bad-smells hot.  My solder won't melt even if I hold it there for a solid 15 seconds.

Sometime when I touch the solder to the end of the pencil I get the same effect.  Other times the solder melts and forms a ball on the end of the remaining solder.

Ideas?  Am I just hopeless?

TIA.

[mfree]

What kind of iron do you have?

I have always had excellent luck even with the cheap irons, as long as they are tinned (solder already on the tip). I bridge the component lead and the pad on teh PCB with the iron, wait a second, then introduce solder at about 90 degrees away from the lead.

Also, how long are you waiting before soldering with your iron? It really sounds like your iron isn't hot enough.

[grislyatoms]

My solder won't melt even if I hold it there for a solid 15 seconds.

Yikes! That's way too long. Solder should melt instantly against the iron. Your iron isn't getting hot enough. Also, before you go to actually solder your component, when the iron is hot, coat the tip of your iron with solder. It should be a very bright, shiny metallic color on the end of your iron. Also, keep a damp sponge near you to wipe off excess solder. If the tip of your iron looks dull, add more solder to it, turn up the heat, or get a different iron.

What are you soldering, and how thick is the solder? Make sure you are using electronics-type solder. (As I recall it's a mixture of silver, tin? and a little flux) You cannot use the lead-type for electronics.

When I solder, I poke one of the legs through, touch the iron to the leg and then touch the solder to the iron and leg. It should flow right into the hole, and leave a little sloping meniscus of solder around the leg. When it cools, the solder should be bright and shiny, not dull or with any holes.

[Headless Thompson Gunner]

Get a good iron.  Make sure the tip is nice and clean.  The tip should be bright and shiny, not dark and corroded and nasty looking.  Solder won't melt against corrosion, only against bare metal.  Use a file to clean away any corrosion and expose bare, bright metal, then tin the tip.

Heat transfers best through melted solder.  Touching a clean, dry iron to a component lead or PCB pad won't heat it up all that much (relatively speaking - it'll heat up enough to damage parts, but not enough to melt solder).  Add a little bit of melted solder between the iron and the component/PCB and their temperature will rise rapidly.

I generally hold the tip of the iron against both the component lead and the PCB for a second, then touch the solder to the point where all three (iron, lead, pcb) intersect.  The iron melts the solder, which then begins to transfer heat to the lead and PCB pad.  Once the lead and PCB heat up to the melting point of the solder, the solder will flow all around and create a good solder joint.

[Bogie]

www.partsexpress.com can recommend something.

They also sell some good solder.

Pick up the cold end.
 

[Thor]

My solder won't melt even if I hold it there for a solid 15 seconds.

What are you soldering, and how thick is the solder? Make sure you are using electronics-type solder. (As I recall it's a mixture of silver, tin? and a little flux) You cannot use the lead-type for electronics.

Umm, the best solder to use for soldering electronics is eutectic solder, meaning 63% lead and 37% tin. I use that exclusively for electronics. A nice liquid solder flux is good to have. (Make sure it's the non-corrosive kind).

Nick, in my experience, if this is an older iron, sometimes corrosion builds up between the part of the tip that goes inside the heating element. If you have a removable tip, take it out and clean it up real well, then re-install it. If it still doesn't seem to heat up very well, get a new iron. I really like the Weller irons. Tinning the tip is an important step, too. Sandpaper or file it down, heat it up, dip in some flux and coat liberally with solder. Wipe any excess off with a damp sponge. For the record, I shy away from rosin core or flux core solder.

Grisly, I think that you're thinking of water pipes. Lead has been banned for soldering copper water pipes. Apparently, the lead can leech into the water eventually. Of course, not too many copper water pipes going in nowadays. I recently priced a 10 ft section of 1/2" copper pipe, it was over $50 !!! It's going to take me a while to get used to the new, inflated metal prices. (Thanks a LOT, China!!)   

[mfree]

"Pick up the cold end."

Er, quite sage advice.

Also, make sure whatever you set the hot end on will handle it It's rather hard to get molten polypropylene to let go of your soldering tip, and it also quite effective welds together what 5-6 components were touching that part of the film case when you let the iron roll into it...

[Manedwolf]

IMO, the Weller temp-controlled stations are the best you can do. Make sure it's hot enough before you start. A "cold solder" joint from insufficient heating, even if it looks alright, can have a layer of flux blocking contact...and if you hold it there for 15 seconds, you're likely frying a component!

Good iron:



I got one from a bankruptcy auction at a small industry sort of place.

[jeepmor]

If not already done, tin your component legs also.  Helps immensely.  If you have one of the solder stands, you can leave it in that with a shiny tinned hot soldering gun tip and then touch the component leg to the iron and then the solder to the interface between the two.  Solder will wick onto component.  If it's getting clumpy, your not getting good wetting, which means your solder is not sticking properly. 

As for the rest, it's covered adequately.

[grislyatoms]

One other little tidbit. Watch how much heat you apply to the pads and pass-throughs. You can get them hot enough to fall right off/out of the board!

[cfabe]

Nick, from what you're saying it sounds like something is very wrong. Wrong kind of solder, wrong temp on iron, dirty/rusty/not tinned tip, etc. Give us more info on what you're using and what you're trying to do, maybe even some pics would help.

What is the component you're trying to solder? If it's very massive and you're using a small hobby iron (10-20w) you might just need a more powerful iron. Most of the good quality soldering stations like others have shown are 50W irons and I've only come across a few instances where I really needed more power than that. But some of the radio shack irons are only 10 or 15watts, so that could cause a problem.

The rest of the suggestion are good advice.

[280plus]

Sounds like a crappy iron. Go to radio shack and get one of those pencil ones. and some rosin core solder. I never seem to have any problems with it. Smells good too. Almost like church...

The biggest secret to soldering is the WORK must melt the solder, not the iron.

[AJ Dual]

www.partsexpress.com can recommend something.

They also sell some good solder.

Pick up the cold end.
 

I didn't ask, but thanks for that link!

I'm just now getting back into a little tinkering, and the last time I was in my mad scientist phase, Radio Shack actually still sold the stuff like that, instead of becoming a cell phone and RC toy store, and I've been looking for online places with electonic components and tools.

 

[One of Many]

I taught an electronics lab at the local college last spring, and two of the students were not able to get a decent solder connection.  They were burning off the pads on the printed circuit board, and had large globs of solder on the few connections they made.

When they asked me why they could not get good solder joints, like the rest of the class, I asked them to show me the solder they were using.  It was LEAD FREE solder that they purchased at the local Radio Shack.  I gave them some 63/37 or 60/40 lead/tin flux core solder, and the joints from then on looked very good.

The electronic technicians at the employer I worked at, all cussed the lead free solder, saying they could not get decent joints with the stuff, and these guys soldered every day for years.

Flux cored solder is the easiest type of solder to work with, and less messy than having to use liquid or paste type flux with a separate dispenser.

Temperature control of the soldering iron is critical; it should get just hot enough to melt the solder you are using, and maintain the molten state while in contact with the work for three seconds.  DO NOT leave the solder iron in contact with the work longer than three seconds, or you risk destroying the electronic component, and the pad on the printed circuit board.

The size of the tip on the soldering iron should be adjusted to fit the work; the larger the tip, the more heat it stores (and may transfer to the work).  It is very bad to use a tip that is too small for the work; if the tip is too small, you will not be able to transfer enough heat in three seconds to complete a good joint - leaving the tip on for a longer time gets the work overheated, but not hot enough to melt the solder where it will flow and make a good joint.

When soldering, remove the solder from the joint before removing the tip of the soldering iron; do not allow the joint to move while it is cooling, or a cold joint may result.  If the finished joint has a frosty appearance, it is a cold joint, and needs to be re-flowed with flux and solder. Components should be inserted in such a way that they will not move during the soldering process.

[AJ Dual]

I taught an electronics lab at the local college last spring, and two of the students were not able to get a decent solder connection.  They were burning off the pads on the printed circuit board, and had large globs of solder on the few connections they made.

When they asked me why they could not get good solder joints, like the rest of the class, I asked them to show me the solder they were using.  It was LEAD FREE solder that they purchased at the local Radio Shack.  I gave them some 63/37 or 60/40 lead/tin flux core solder, and the joints from then on looked very good.

The electronic technicians at the employer I worked at, all cussed the lead free solder, saying they could not get decent joints with the stuff, and these guys soldered every day for years.

Drat.

At least I only bought the tiny $2.99 tube of .39 rosin-core at Rat Shack, something in my gut told me not to buy the full spool of the stuff... 

[Manedwolf]

The lead free stuff just doesn't work for me either.

Just set up a fan blowing away from your soldering area and tape a charcoal filter to it. As long as the smoke is going to it, it should be fine.

[280plus]

Radio Shack actually still sold the stuff like that,

They still do here, it's just buried in the back. At least the soldering irons and solder are but I know what you're talking about.

[Headless Thompson Gunner]

I've had passable luck with the lead free solder.  Bought some by mistake last time, but it still worked well enough for me.