Soldering Technique and SMD Reflow Oven

[okalex]

Hey guys,

So you've covered the tools of a typical workbench and etching PCBs. I think the next logical step is to cover soldering technique. As simple as it seems, a lot of people (even professional EEs in my experience) don't know how solder properly.

The main thing I'd like to see, however, is a description of the construction and use of a SMD reflow oven made from a toaster oven. It's something I've been curious about for a while, but never had the time to try it out and would love to see some in-depth coverage of the process and the results. I'm not sure if you can do SMD reflow on PCBs without a solder mask, but if so, this combined with the ability to etch our own PCBs can make for a pretty powerful home prototyping station.

I also want to let you know that I enjoy the show. It's nice to see a podcast that delves into the details.

Cheers,
Alex

[blazes816]

I believe they did soldering in the Digg The Digg Button episode.

[d4rk_fr33dan]

I believe they did soldering in the Digg The Digg Button episode.
Yeah but that was covered by Limor Fried and Kevin Rose and well they didn't do such a hot job. I'd rather have Dave's perspective on it. Also what Okalex is talking about is on a completly different level.

[timada]

When picking up a soldering iron, make sure you are picking it up by the PLASTIC end. The easiest way to accomplish this seemingly simple feat is to place the iron in a proper stand where the hot end of the iron is safely covered. This will also protect your tabletop from burns (guilty), keep mysterious holes from appearing in your carpet (guilty), and maintain the pristine condition of your other tools (oops). All of these problems disappeared for me after I purchased a $10 soldering iron holder.
__________________________________________________ ____________
Ada sears parts (http://www.appliancepartspros.com/Sears-Parts.aspx )

[mikec]

Please don't solder in the house. Even if you don't use a lead solder some fluxes have nasty ingredients. If you have a workshop, invest in good to great ventilation. Keep pregnant spouses and friends and children out of that area. Wash your hands after and don't eat, drink or smoke while soldering. Keep no food in that area.


One thing I noticed was that one needs to keep the tip clean to be able to solder well. A damp solder sponge, heck buy a kitchen sponge and cut it into smaller pieces, keeps the tip clean.

Second, use an iron with the proper wattage for the job you are doing. Yes, a higher power iron gets hot faster but it can also destroy a board or components.

And yes, KNOW what end of the iron to grab.

[md2389]

Please don't solder in the house. Even if you don't use a lead solder some fluxes have nasty ingredients. If you have a workshop, invest in good to great ventilation. Keep pregnant spouses and friends and children out of that area. Wash your hands after and don't eat, drink or smoke while soldering. Keep no food in that area.


One thing I noticed was that one needs to keep the tip clean to be able to solder well. A damp solder sponge, heck buy a kitchen sponge and cut it into smaller pieces, keeps the tip clean.

Second, use an iron with the proper wattage for the job you are doing. Yes, a higher power iron gets hot faster but it can also destroy a board or components.

And yes, KNOW what end of the iron to grab.

And don't try to use it like a pencil like I did one time (wasn't paying attention....I did from that point on! :D) btw, those $15 Radio Shack combo kits do come in handy for those just starting out. (You know, the one that comes with the 15/30W solder iron that has interchangeable tips and includes the stand you mentioned.)


btw Dave, if you do read this, I want you to know that this show is the reason why I got back into soldering again. :)

Another thing you might want to bring up is the use of an extension cord. Those little cheap-ass 18 gauge k-mart two-prong extension cords aren't going to cut it. Sure, they'll power the iron, but it will take forever to heat it up. Get yourself a proper extension cord from your local hardware store. (I'm talking either 16 or 12 gauge here. Preferably the latter.)

[mikec]

One thing I just remembered SAFETY GLASSES. If I didn't wear glasses I probably would be either blind in one eye or have serious eye damage due to a fluke solder explosion that happened to me when I was working on something indoors. Not sure why or how but one second I was repairing an audio mixer then next second my right lens and eyebrow had solder on it. I didn't shake the iron, no moisture around. I was in a climate controlled environment and the parts had been inside for at least a day.

I guess live and learn.


PS If you have solder novices around please educate them on the hazards. We had a female production intern, who knew nothing about soldering, who tried to put her hand under the soldering iron to catch a bead of molten solder. The tech wasn't aware what she was doing, he was fixated on the repair.

[lordbyron]

Please don't solder in the house.

Dude next your gonna say you have to wear a respirator also.

[lordbyron]

And yes, KNOW what end of the iron to grab.

If you don't know this you have no business even trying you build something.

[lordbyron]

Another thing you might want to bring up is the use of an extension cord. Those little cheap-ass 18 gauge k-mart two-prong extension cords aren't going to cut it. Sure, they'll power the iron, but it will take forever to heat it up. Get yourself a proper extension cord from your local hardware store. (I'm talking either 16 or 12 gauge here. Preferably the latter.)

What awg wire do you think is on the iron?

also using ohms law:

watts
------- = Amps
voltage

so

30 watt iron
------------ = .25 amps
120 volt


18 awg wire recommended current capacity is 5 amp

explain why you need a cord that is rated for 20 amps to plug in a soldering iron.

now if you are going to solder 400 feet from an outlet I can understand the high awg wire because if you factor in the resistance in the wire itself.

[md2389]

I don't know what iron you have, but mine has 16 guage wire. Furthermore, the bit with the extension cords is from personal experience.

[lordbyron]

I don't know what iron you have, but mine has 16 guage wire. Furthermore, the bit with the extension cords is from personal experience.

Here is my favorite iron. I have about a half dozen irons. This rig has 18 awg wire.

http://i245.photobucket.com/albums/gg42/brianranieri/IM001606.jpg

[mikec]

If you don't know this you have no business even trying you build something.


Meant as a sarcastic joke.

BTW, nice Weller.

[lordbyron]

BTW, nice Weller.

Thanks, that is my favorite rig. turn it on and almost instantly you are ready to solder. No waiting 10 minutes for it to warm up.

[md2389]

Thanks, that is my favorite rig. turn it on and almost instantly you are ready to solder. No waiting 10 minutes for it to warm up.

How much did you pay for it?

[lordbyron]

How much did you pay for it?

I think it was around $100. But it was one of those things I bought when I was out on a job and needed an iron and did not have one with me so i bought one...who knew I would like it so much.

[mikec]

One site shows it for $126.65 with a list of $149.00.


I could never get the company to spend the $$ for a station like yours for the shop, they said most of my work was field work, so I "needed" a portable iron.

[md2389]

I think it was around $100. But it was one of those things I bought when I was out on a job and needed an iron and did not have one with me so i bought one...who knew I would like it so much.

Heh, thats not bad for something like that. I used one very similar at the local community college a few years ago. Same brand, but this one had a knob where you could manually set the temperature of the iron. It also came with a vacuum pump solder sucker. (which was quite loud if memory serves)

[lordbyron]

One site shows it for $126.65 with a list of $149.00.


I could never get the company to spend the $$ for a station like yours for the shop, they said most of my work was field work, so I "needed" a portable iron.

That is all I do is field work. And when you are one of the owners there is no one to tell me I can't spend it. :) When most of our jobs are $3000-$5000 on the lowend, what is $100 and that gets passed on to the customer anyway. We were at an auction today and just bought another scissor lift, a ford F150 and a Miller Bobcat 250 welder. So a soldering iron is nothing.

[lordbyron]

Heh, thats not bad for something like that. I used one very similar at the local community college a few years ago. Same brand, but this one had a knob where you could manually set the temperature of the iron. It also came with a vacuum pump solder sucker. (which was quite loud if memory serves)

Yea I would like to get a variable temp unit but just haven't got around to it, actually this one works great. I do not really care for solder suckers I prefer to use braid.