Worth Repeating About Soldering SMT Devices

Yep, solder paste and a temperature controlled toaster oven! I've made quite a few circuit boards with SMT parts this way.

Have you seen my new soldering iron? (Courtesy, Seattle Robotics Society)

Thanks for the post!

I always appreciate better ways of fishing! Tech tips like this make the ride on CR4 a real pleasure.

Better ways of fishing, hmmmm. Try dynamite and a long handle net.

We were setting off hydrogen-oxygen 2:1 mole ratio gas in balloons out at the farm this weekend. What a blast. It is posted on YouTube, something about red balloons popping.

Thanks for the information. I had figured that SMT devices pretty much shut out the DIY hobbyist.

Still, DIP packages are much easier to breadboard.

True, but not everything comes in a DIP, sometimes you must SMT.

You just have to have very steady hands when placing 0804 resistors!

I'm good except for the steady hands and sharp eyesight.

We are talking microscope, and screw-arm manipulators? I don't think I could even nudge one of the 0804 resistors with tweezers and get the position 100% aligned, although, I used to be a good hand at picking up tiny forensic evidence with tweezers while working under a 'scope.

I could not even read license plate at 21:00 last evening (end of dusk, beginning of night) under our street lights, only about 35-40 yards distance.

Needed binoculars, and did not bother for them.

I solder SMD by hand. Not often, but there is plenty of help on the net and the solder paste is wonderful.

There is a soldering 3rd hand aka helping hand available in the market which works well for holding the things steadily.

I haven't used solder paste in years as it tends to leave little (microscopic) solder balls around in weird places on circuit boards shorting out things you don't want shorted. It's not bad with some of the larger coarse pitch parts, but when leads are .020" or less, the tiniest of solder blobs can be an issue.

I find that a fine tip iron and plenty of flux I can usually place and solder some pretty small parts. I use a felt tip flux pen. My hands aren't that steady, but I've got a technique where I use a finger or two on the bench to steady the whole hand. Works pretty well for me.

The other must have is a good stereoscopic microscope. 20x to 40x is usually good enough. A wide field of view helps as well, especially to place and solder IC's.

You need to be very careful with the flux, buy best quality and only using a tiny, tiny amount, less is always better.

Plus scrubbing of any rest left, away, with alcohol and a toothbrush. You may need to do that 2 or 3 times....

The look at it carefully with a high powered eyepiece, say 50x. Using a metal pointer, remove anything untoward, but thats hardly ever needed....

Never had a problem.....

Good point. Conductive crud can get caught in the flux as it dries and hardens on the circuit board. Clean it well. I've seen some weird things happen that went away once the board was cleaned.

Make sure that your alcohol is fairly pure. Isopropanol works well, but make sure it's at least 91% or stronger. I buy that at drugstores. 70% medicinal grade won't work. If you're a purist or need larger quantities, chemical suppliers can supply industrial grade at 95% or better.

What about using denatured ethanol? I have plenty of that around.

I do a lot of surface mount work and there are a couple of secrets that have never been mentioned before.
Apart from a temperature-controlled soldering iron and 0.5mm solder (or thinner), the secret to soldering surface mount chips is to hold the chip up-side down and very quickly solder all the legs but leave almost solder behind. You need a fine tip on the iron.
Then solder all the lands with very little solder and even remove any excess with wick.
Now use tweezers to place the chip over the lands and run the iron across the legs and the pressure of the iron and the solder already present will do the trick.
This is the fastest and cheapest way and the least stressful. You don't have to buy anything expensive.
I find SM soldering twice as fast as poking leads through holes and the board is smaller and appears to be less complex.