If you go on EBay and search for solder paste - the pro stuff costs an arm and a leg for small amounts, so I was wondering if it is possible to make entry grade solder paste at home. After looking at several forums, I found a forum conversation in which someone used shavings from a filed block of solder mixed with solder flux to create paste, and reported it as success. I decided to recreate this, and in the process discovered that it is much easier than i thought. And the bonus is that working with the pre-tinned pcbs is so much easier, soldering times are now significantly reduced.
WARNING: THIS PROJECT INVOLVES FILING SOLDER - WHICH IS AT LEAST 40% LEAD. WORK IN WELL VENTILATED AREA AND WEAR A FACE MASK AND GLOVES. ALSO MAKE SURE LEAD DOES NOT END UP IN FOOD.
Also read this: http://en.wikipedia.org/wiki/Lead_poisoning
What you will need:
1) Solid Solder - 50-50 or 60-40. You can use solder that has flux in it - as long at it is NOT acid based flux which will corrode your components
2) A medium to fine file - the finer the file - more work but better quality paste
3) Solder Flux - also called "solder paste" but do not confuse this with real solder paste. Make sure it is not acid based for intended for soldering! Radio shack sell some of this stuff.
4) a toaster oven, fire, or oven.
This instructable has 12 steps.
Step 1: Prepare Solder Bits for Melting
2) Put in aluminium foil. fold the foil a few layers thick so no solder will leak out and mess up your nice toaster oven or stove or leak on something important like your foot
3) Form a makeshift "pan" or "boat"
Step 2: Bake, Cook, Grill or Toast
I used the toaster at the highest heat (broil setting) for 40 minutes.
You can also place the boat on a metal plate over a counter top stove. WARNING: Do not put the makeshift boat/pan directly on a fire, as it will eat through the aluminium, and you will have a nice solder puddle to clean up. You do not want to get in trouble with the local home management team.
Once the solder melts, take it out/off and let it cool down into a bar of solder, the shape does not really matter.
Step 3: Cooling and Prepping
Note: MAKE SURE YOU GET RID OF ALL THE ALUMINIUM FOIL AS IT WILL END UP IN THE PASTE IN THE NEXT STEP!
Step 4: File/Grind the Solder Bar
MAKE SURE TO WEAR PROTECTIVE GEAR. OK SO I AM NOT WEARING GLOVES. DOES'NT MEAN YOU DON'T NEED TO!
Step 5: Mix the Powder Into the Flux
Step 6: A First Test
I was in a rush to show off, so unforunately I didnt strip off all the photoresist (the blue residue on some of the pads and leads. This is where the solder will not catch on properly. Lesson learned. Next time let the board sit in the resist remover (baking soda) instead of trying to quickly scrape it off.
Step 7: Add THIN Later of Paste
TIP: One nice thing I discovered is that if you want to get really good results in etching, exposing, and tinning - you can clean off the board with Comet kitchen cleaner and it works better/safer/quicker/far-better than acetone.
Step 8: Heat the Board - Part 1
Step 9: Heat the Board - Part 2
Step 10: Almost Finished
Step 11: Final Reflowed Board
Step 12: Final Result
Hope you enjoyed this instructable!