Surface Mount Soldering for Dummies (and Fraidy-Cats)
Surface-mount soldering is something that I once felt was beyond my ability as a mere mortal. I could hand solder very basic connectors if they were large enough, but fine-pitch surface mount? Forget it. However, this summer, I wanted to build a couple of projects involving AVR microcontrollers that were not available in DIP through-hole packages, so my options were to either build my design around a full dev board like an Arduino or Teensy++ or else bite the bullet and learn to solder surface-mount parts. I chose the latter, and I'm glad that I did. I have created this page to document what I have discovered does and doesn't work for me, in the hopes that someone else might find it useful. I'm sure that many of my current practices are by far not what would be considered "best practices", but I try my best to avoid stupid things that run the risk of destroying parts (as I did several times as I was learning through trial and error). I will try to document here not only how I have come to do things, but also to describe my mistakes, so that others may avoid them, as well as (to the best of my ability) to describe the Right Way(tm) of doing things (such as hot-air rework, solder paste, reflow ovens, etc.). I take somewhat of a middle-of-the-road approach. My methods are certainly not the best, but they work quite well for me. So far, I do all of my soldering by hand with an iron (so no reflow oven, though hopefully soon I will try learning how to use a hot-air rework station), so that will be mainly what I describe here. I feel that discussing hand soldering will be the most useful to the widest number of people anyway, as that is who I am directing this page at anyway--people who can do basic soldering but would like to take the next step and learn to solder surface mount parts, but may be too intimidated to even try (as I was).
Ok, first of all, you'll need the right equipment to get started. I'm going to assume for this (and most of this page), that you are new to soldering, and are looking for entry-level equipment and techniques.
An absolute must. I highly suggest a variable-temp iron with replaceable tips. I use a 1/32" conical tip for just about everything, though different tips make different jobs much easier. Unfortunately, this is one area I can't really help you. I seriously haven't changed tips since putting on the 1/32" conical tip.
Here is the iron I use ($20)
This is probably a good tip for SMD flat-pack (QFP, etc.) parts ($6, haven't used it myself...)
Here is a nicer iron ($40)
Here is a REALLY nice iron ($100) I'll probably be buying this iron soon. It looks amazing.
Another absolute must. There are many kinds of solder out there. I prefer silver-bearing, rosin-core. Avoid solder with liquid-soluble flux core unless you know what you're getting in to (basically, if you need this guide, stay away from water-soluble flux). I hear good things about water-soluble flux, but it requires special care to be taken to wash it all off or it corrodes your boards with prolonged exposure. Rosin flux and rosin-core solder are perfectly suitable for beginners.
Another thing you'll want is liquid flux. You can get it in a syringe with a plunger or a bottle with a brush in the cap. I went the bottle/brush route. It's messier, but cheaper.
Rosin flux ($9)
For cleaning up flux, you can get dedicated flux cleaner, or you can just use isopropyl alcohol. Alcohol tends to leave a tacky residue, but that can be washed off with normal dish soap. This is the route I take.
For desoldering surface mount parts, I have found ChipQuik to be the easiest method (though I have yet to try using a hot-air rework station, which should be easier and cheaper...). See the desoldering section below for how to use it.
Most of these are optional, but highly recommended.
Digital Multi-meter (varies) The most important feature you want to look for is continuity testing. The symbol for continuity testing is typically "o)))" (kind of like a sideways Wi-Fi symbol This is used for checking for shorted pins. Also, look for sharp leads (you can also buy special insulated probe leads if your meter has removeable leads)
Fine-tipped tweezers ($3) Look for a pair with a fine enough tip that they come with rubber tip guards to keep you from stabbing yourself. Then you know you have a good pair ;) I prefer bent-tip over straight tip, but that's up to you
Soldering iron stand ($5)
Brass tip cleaner ($5)
Desoldering pump ($5) Somewhat useful in conjunction with desoldering braid for through-hole parts
Desoldering braid ($4) Extremely useful for fixing shorts in fine-pitch SMD parts
Ok, so this is probably the main reason you're here... sorry, I'll get around to filling out this section with pics and stuff as soon as I get the chance.
Q&D guide: The simplest and most effective method I've found is called "flood-and-suck", basically flood all of the pins with solder, making sure to get good solder joints on every pad but not caring about shorts. Then, use desoldering braid to deal with the shorts. USE LOTS OF FLUX.
I have a feeling that this doesn't really need to be covered, but I'll cover it briefly anyway... eventually...
Q&D guide: ChipQuik. Apply the flux, apply the ChipQuik solder liberally to all of the pins (you're looking for a single large blob of solder to cover all of the pins on each side of the chip). Go back and heat up all of the solder one last time, then pull the chip off with tweezers. Clean the excess solder off of the pins with desoldering braid, then wash with isopropyl alcohol and soap water.
Q&D guide: Desoldering pump to remove as much solder as possible, then finish the job with desoldering braid. Don't spend too much time with the pump, the more you heat the solder, the less it will want to flow. The braid does most of the work, the pump is just so you don't end up using a ton of braid because of the large amounts of solder found on through-hole pins.