Soldering

[Freebird]

There have been many times here where somebody has had questions about the proper way to re-solder the class controller on the first gen or other soldering jobs. I ran across this pretty good page on how to properly re-solder connections on circuit boards. Hopefully it will help some of our members who have not done much soldering.

 

http://www.streettech.com/modules.php?op=modload&name=Reviews&file=index&req=showcontent&id=68

[BOO]

Good article.

Good advice is practice, practice, practice.

In my opinion the best advice in the article,

 

The Soldering Iron You don't need one of those expensive professional soldering workstations you see advertised in electronics parts catalogs, but you should have a decent iron, ideally with a variable temperature feature. I've used the Xtronic 16-30 Watt iron for years and am more than happy with it. I paid under US$30 for it. A hot iron is a happy iron. You want to get in and out of there (to the solder/component/soldering pad) as quickly as possible so as to weld the component to the pad without baking the component's little brains. Discrete components are designed to take the heat, but you don't want to push your luck (and a scorched PCB is *so* not cool-looking). So you want an iron that can be as hot as it needs to be to melt the solder, but no hotter. You'll probably also want some tips of different sizes, especially really small tips if you're going to be doing a lot of work on tightly "populated" circuit boards.

 

I'm sure some electronic guys will jump in and tell you to use low wattage gun on those circuit boards. 100 watts is not low wattage....15 watts or less.

Jerry

[autopilot]

In days gone by, a string of gals at work stations with big 200 Watt "American Beauty" soldering irons took care of the soldering tasks on electronic assembly lines, because they have better "touch" than most men.

 

The power of the iron (beyond nominal) is less important than skill and time on the solder joint. Also, if possible, use a clip or pair of hemastats or heat sink of some kind between the soldering and the components. I also strongly recommend the inexperienced get asssistance if the work is on something critical. Otherwise, waste as much time as necessary to learn and practice the procedure, until proficient.

 

The test?.........wrap small gauge wire around a teminal post on a scrap electronics board, solder it without having a loose or a cold joint and without burning or melting anything. The joint should be secure, but only have enough solder so that you can see well defined coils of the wire beneath the solder and should be shiny in appearance. (you should still be able to define strands in stranded wire..if not, there's too much solder) Apply heat only until good flow is achieved, then pull away and leave it...if it's a cold joint (dull &/or grainy), don't try to fix it till after it's all cool again-you don't want to risk overheating a component. Also, do use something to hold the pieces in position while soldering, if possible. Even small movement while the solder is cooling/solidifying can cause a cold joint & poor continuity. (and let it cool on its own..don't blow on it)

 

ONLY rosin-core, silver solder for electronics. I disagree with the commentary on flux. I would not recommend any but the experienced fool around with flux (solder paste) around electronics. The acid will destroy things you didn't even know you touched. A little heat spatter can go a long way! You can accomplish similar results with a shaped pencil eraser. Just be clean about it. Use a small electronics vac to clean up, or a little canned air to blow it off prior to solder.

[Guest tx2sturgis]

In my former life, I worked as an electronics tech, and there is one thing I did not see mentioned in these articles and advice comments.

 

The advice is all good, as far as it goes, but leaving this one thing out can lead to multiple failed joints, and lots of cold soldered joints. This one simple thing that you MUST do to guarantee success...MAKE SURE EVERYTHING YOU'RE SOLDERING TO IS SHINY!

 

Silver, tin, lead and copper, all of it, oxidizes over a period of time, as little as a few hours, depending on the environment. If you buy an electronics kit thats been sitting on a shelf for a while, or pickup a copper wire thats been exposed for a while, and then solder it, your trapping in some oxidation, which acts as an insulator to heat and electricity. Bad news when it comes to electronics soldering.

 

ALWAYS do this: Scrape the leads, the wire, or the solder pad on the circuit boards, so that everything is nice and shiny. Use a small pocket knife, and scrape the component leads and the copper wires and the circuit board traces, till its shiny, shiny, shiny. Melted solder will absolutely LOVE shiny metal. I have even showed disbelieving 'techs' how to solder to high quality STEEL ( i'm not talking hardened steel)...as long as its super clean and shiny, roughed up, and you get it hot enough, you can solder to it. And I'm not talking about using a torch, just a small iron. The experts say it cant be done, but I can do it. And it stays soldered.

 

When inserting component leads into the holes on a PCB, take your little pocket knife and scrape lengthwise ( the blade should be at about a 90 degree angle to the lead) along the lead, till its shiny. Rotate the wire lead, resistor, capacitor, transistor, whatever it is, in your hand, and keep lightly scraping in one direction with the knife edge at a 90 degree angle to the lead. Get it nice and shiny. Do the same with anything thats copper, like wire or grounding/bonding straps, before you solder to it. Also scrape the little solder pads around the holes on every circuit board, everytime, and with the component lead all clean and shiny, and the solder pad all clean and shiny, it is SO much easier to get a good solder joint.

 

Did I mention, scrape it till its shiny?

 

 

 

 

[Yammer Dan]

This Thread needs to be kept. At least until I get to my Class sometime this winter!!

[Marcarl]

I know it's been said but I said it again, everything needs to be clean, clean, clean. Time spent in cleaning and keeping things clean is soon earned back when everything goes together as planned.

Also, the iron needs to be fully hot and big enough,, not too big but big enough to put out the heat needed. Not good to try to solder something with an iron that cools to quick and so doesn't have enough 'guts' to finished the job.

When talking about irons, tip maintenance is also very important. The tip needs to be in total contact with the job at hand. If the tip is corroded (eaten away) (which happens) then there won't be enough contact for proper, speedy heat transfer and more parts than what is needed will be heated, causing more problems.