Do I have to solder this in a special way?

Private19872

http://www.parallax.com/product/32313

I recently purchased this and when I got it, I noticed the solder points were smaller than I had expected. Do I have to solder this very carefully or is there something different I need to use? Thanks for your help.

Publison

What kind of soldering iron do you have? A 40 watt Radio Shack iron would be fine.

The smaller tip the better.

RDL2004

Those are surface mount parts (but pretty big ones), so you do need to be careful to not bridge any of the pads and cause a short, but you can do it with a normal soldering iron. I usually drag solder and mop up any excess with some solder wick, but there are other ways to do it. Go to youtube and search for "surface mount soldering" and you'll find lots of tutorial videos.

LoopyByteloose

When working with small pads and small components, I generally do what is called 'tinning'.

In other words, I first apply a coating of solder to all the pads that I am going to use without any component placement. This is just a thin coat of solder, but that makes attaching the component a simpler job. Bare metal that hasn't been tinned sometimes rejects solder due to oxide, dirt, or oil. By first tinning the pads, you avoid struggling with rework that might otherwise be required.

kwinn

A fine tipped soldering iron, solder, tweezers, a magnifying glass (at least for my eyes), and good lighting are all you need. As Loopy posted cleaning and tinning the pads first makes the job much easier.

Publison

Flux makes it easy!

LoopyByteloose

Yes indeed, the flux is important.

For those that don't know, it takes the heat from the soldering iron and cleans the bare copper (or other metal), so that the actual solder will stick. If the copper is discolored from age, it might be best to start with an abrasive pad (the plastic ones I use to clean pots and pans) to get to bright copper before expecting the flux to do its job.

Not all flux is for electronic projects -- some are too strong and create later problems (like Acid core solder).

Others might be okay for electronics, but don't clean up very easy (like Rosin core solder)

It may be best to use a solder that doesn't provide a flux in its core and to get either a paste or liquid flux that will clean up more easily.

Paste flux usually requires a solvent to clean up as it tends not to mix with water.
Liquid flux usually cleans up with soap and water.

Tinning can be done to everything that you think might give you trouble -- pads on the board, components, and wires; but don't use excessive solder as that creates a mess and additional problems. (You may need a bit of practice with tinning to get it right.)

None of these things are 'special solder skills'. They are the skills and knowledge that apply to soldering just about anything.

Heater.

Tinning pads is not always a good idea.

I tried that when soldering surface mount LEDs. The problem was that having tinned the pads on the PCB it was no longer possible to sit the LED tight flush down onto the board due to the layer of solder in the way. That meant the LEDS ended up skew. Better was just to position the LED on the naked pads and tack down one end, position nicely whist the solder is molten. Then solder the other end of the LED.

I love the way people who know what they are doing solder fine pitch SMD chips. Flux the PCB pads. Position the chip and tack down one or two corner pins. Seemingly flood the pins with what seems like far too much solder, "drag soldering", that shorts everything out. Never mind messing with fine tipped irons use something that seems far too big for the job.

Then, drag the solder away from the pins with the iron and perhaps remove the excess with solder wick. Voil

LoopyByteloose

Well SMDs have certainly changed everything about soldering (Do you remember when we used wave soldering machines?). A lot of people are using paste solder, solder masks, and a toaster oven.

But there are some things that do work with a soldering iron and SMDs.

LEDs and other two-point components (resistors, capacitors, and such) can be very difficult to get right. They may actually be harder than multi-lead chips.

So Heater has a good point. It may be best to stick everything down with gooey flux or to only tin one pad and then set the item where you exactly desire.

For chips with multi-lead packages, I tack one corner and then a diagonally opposite corner before doing the rest. That assures that the alignment is reasonably good.

Another way to go with tinning pads is to electroplate tin or lead to the pads. This can be done, but it rather involved technically. You need a solution with the tin or lead in it, and some apparatus to plate with a brush that wetted with the solution. (Too involved for my projects.)

Heater.

Wave soldering is still going strong. There are still billions of through hole devices coming out of China. Crack open a cheap power adapter sometime (Don't actually use them, they all seem a bit dodgy to me, like the one that fried itself on my DLINK router recently)

Always amazed me. "What? You mean my board goes in that dangerous looking tsunami of molten solder and actually comes out all neatly soldered up without getting fried? No way!"

Works a treat though. After somebody has tuned up the process.

kwinn

Heater. wrote: »

Wave soldering is still going strong. There are still billions of through hole devices coming out of China. Crack open a cheap power adapter sometime (Don't actually use them, they all seem a bit dodgy to me, like the one that fried itself on my DLINK router recently)

Always amazed me. "What? You mean my board goes in that dangerous looking tsunami of molten solder and actually comes out all neatly soldered up without getting fried? No way!"

Works a treat though. After somebody has tuned up the process.

Yep, works well when tuned, but boy can it ever produce cold solder joint problems down the road if not tuned and operated properly.