I have a friend who wants to solder up an SMT altimeter kit for rocketry. It uses many 0805 SMT components.
How difficult a task is it to hand solder such a board for someone with modest thru-hole soldering skills? Hard? Laughably hard? Doable if one skips coffee for the day? The site calls a 3/5 difficulty.
Any advice is appreciated.
Here’s a pic.
And here’s the kit website: http://eggtimerrocketry.com/home/eggfinder-gps-tracking-system/
Not super fun but very doable. Shaky hands won’t help a bit though.
Old guys and purists will scoff, but the best technique I’ve found is to apply good no-clean liquid flux (we have excellent stuff at DMS). Get a little solder on the end of your iron. Pin the part with tweezers and hit one end with the iron long enough for the solder to flow nicely. Repeat with the other end of the part (no need to hold in place).
I can confirm it is totally doable with a couple hours of practice.
This will be vastly easiest with a microscope, which we have in the Electronics Lab. With some practice you can absolutely solder that with regular solder and a good tip on a soldering iron.
If you don’t have good hand/eye coordination or steady hands I’d use solder paste on the pads, then tape down the part with heat tape, and then gently heat the solder paste with a heat gun. You have to be careful because you don’t want to burn the part or have the part fly off the board from the air coming from the air gun (thus, the tape).
If you don’t have heat tape you can hold down the part with a pair of tweezers, just remember that hot things are hot and metal tweezers conduct heat.
It looks like you have qfn (quad flat nolead IC) (needs a hot air tool) and a number of 0402 chip resistors on the left hand. then there is quartz oscillator. I would think it can be done with an boom microscope, and understanding of heating limits of plastic parts and the correct sequence of soldered parts.
Mid level if the board is bare
If the board only need 0805 it is easy.
These might be the two best videos on youtube on how to hand solder surface mount parts. The first one is absolutely top notch. The second one is just as good but extremely short. To be clear, almost everything else I found wasn’t just not good but was actively bad. As weird as it feels to say it, I actually think my advice might be to watch these two videos and none others.
I would cover the pads in bead flux, place the resistors with a switched vacuum tweezer, then Easy Bake it in a toaster oven.
It’s cool, you can watch as the solder’s surface tension aligns the resistors to true North as it liquifies.
I’ll third the recommendation to use solder paste and hot air instead of hand soldering this. Hand soldering takes more practice and skill, and is more demanding of dexterity and eyesight. It used to be the only practical option years ago when hot air stations cost $500 and up and finding small quantities of solder paste was hard, but we have all the right tools at the space and it isn’t necessary anymore.
You better be dang quick then… or you’ll find the part on your iron tip instead of on the board. I still hold it down for that 2nd joint, but just barely putting any pressure on.
