I am in the middle of designing a driver for Oshpark in Eagle, and just thought about making it dual sided. With hot air soldering and solder paste, will soldering the second side generate enough heat for the components on the first side to pop off? I have no experience at all with hot air soldering, this will be my first attempt.
The bottom side solder may melt but surface tension holds the components on. Unless there is a particularly heavy component. A drop of superglue can hold such heavy components.
I do it all the time. If your serously concerned reflow the first side on the stove using standard solder, paste will melt at a lower temp for the second side.
Make sure you’re using thermal’s.
May I ask what this means? The little soldering terminology I know is in Swedish.
Left side is an example of thermals.
http://dangerousprototypes.com/docs/Eagle_Polygons#Thermals
I see… When I get there I’ll have to figure out how to add them in Eagle. At least I know what they are now. Thanks.
Edit: Just saw your link. Thanks again!
It’s the poly GND plane, that link above is EXTREMELY helpful. If you’re not using GND planes start, makes for a much better overall board, both in looks and performance (as well as making it easier to design, theres no reason to route out GND traces, finish everything else first and let a GND POLY connect all your GND’s).
The point of thermal’s is to provide thermal relief for soldering, without them the larger GND plane’s will dissipate soldering heat (as they should, thats one of the many benefit’s of large GND planes- heat dissipation from the components), leaving thermals turned on (the default setting in eack poly’s properties) for lower power components will allow them to not wick away all the soldering heat.
I always leave thermal’s on EXCEPT for the FET’s source since it is a high draw component (to do that you will need to make a second poly around just the grounded source leg. Check out my description in the BLF 17dd thread for a little more into (but start with the link to dangerous proto’s above).
I think I’ve been a bit to eager to start things… I haven’t been using polygons at all, been using wires for everything, not knowing what polygons are… Back to the tutorials I guess 
Poly’s arnt in the mattaus tutorials, that link posted is really the best info I was able to find on them.
I also was suspicious when I first used a hot air soldering how it will work and if it will cause problems on the underside. But it works without any problems…just try it. Maybe you have some old electronics in the garbage anyway, maybe a main board or something similar just try to unsolder and solder on again as a training. it is easier than I thought to make and solder a working smd pcb. My PcBs and soldering looks always a bit messy but it works.
Have you checked the oshpark projects thread?
Yes, I have been browsing through it and also gone through a couple of mattaus tutorials, but never really thought about what will happen when I do the second side. I was worried I had done a whole lot of work in vain, but thankfully it sounds like I haven’t. The little I have now read about thermals and polygons makes it clear I have a little more work to do though.
It’s amazing how much time I am willing to spend on all this. In the beginning I was convinced that I’d be satisfied with driver swaps. Now I’m writing my own code for drivers and trying to design a driver myself… and just found out that I know someone with a high end lathe, meaning even more time to spend learning new stuff… I’m actually not quite sure if I should thank this forum or damn it… I know what my girlfriend thinks though 