Learning to solder electronics old-school style and PCB cleaning

Building electronics is awesome!  A big part of the building process involves soldering.  Most of the work that we do now uses surface mount components, we try to use surface mount parts everywhere we can, but the some components are still through hole parts.

Yesterday I watched this awesome, retro video series by Pace on proper soldering techniques.  If you’re starting out in electronics it’s definitely worth a watch.

These days when I have to hand solder I use the water soluble, lead-free variety from American Iron and Metal (AIM).  I usually use the 0.020″ diameter version but I also have a spool of the 0.032″ version for (slightly) larger work.

Some folks prefer and recommend no-clean solder, but I don’t like it because I find it very hard to clean the residues off of the circuit boards and even though you don’t technically “have to” clean the residues off of your circuit boards, who wants tacky red-brown goo all over their latest creation???  I went through a lot of laboratory grade isopropyl alcohol (IPA) back when we were mainly using no-clean solders.  I’d clean it with the IPA, douse it with deionized water, then shoot it with compressed air.  I’d have to go through the cycle several times and the boards usually ended up looking chalky or still be sticky after cleaning.

Yes, you must clean off the water soluble flux left behind from the AIM solder mentioned above, but the great thing is that it’s water soluble: it just comes off with water.  To aid in the process we have an ultrasonic cleaner that we use to clean our boards before we quality test them.  The heater built into the cleaner aids in dissolving the residues.  It’s not perfect though.  We still end up using an old toothbrush at the end to make sure everything got cleaned.  Some folks warn about cleaning electronics with ultrasonics, so read about it before you try it and decide for yourself.  Our technique involves leaving the boards in the ultrasonic bath with just the heater turned on (no ultrasonics) for about an hour.  Then, we’ll rub them with the toothbrush and run through an ultrasonic cycle.  I should also mention that we use type II deionized water in the cleaner.

The smell of the AIM solder is a little funkier than other solders, but I think water soluble is definitely the way to go.  And my iron of choice is the Weller WES51.