I did the SOICs with a stencil made pushing the IC through aluminum foil. It worked well. Other IC's and the Si570 were done by putting "dots" on by hand. I did other SMT (caps, resistors, etc.) with stick solder.
I used an IR thermometer from Harbor Freight to monitor temperature but that isn't needed. What you want to do to emulate the reflow "curve" that is done by realizing why it is the way it is. The solder paste has little "balls" or "speckles" of tin/lead solder (or lead free if you are in a zone where you are forced to do so..but the temperatures are much higher and you have to be more careful!). Those are suspended in flux and solvent. If the solvent dries out you can carefully reconstitute the paste for home use.
You heat the board until the flux flows. Unplug the griddle for 30 seconds at this point and reposition the IC's if necessary.. flux should completely flow. Plug it back in. Solder will eventually melt. Most parts, if positioned close to where they should be should "snap" into position on the board be the action of surface tension of the liquid solder. If not.. a little nudging can be quickly done at this point. This is why I like this technique for SMT.. if done correctly all the IC's will be precisely centered on the pads. If you would like this centering but don't want to mess with solder paste, you can solder on parts with stick solder, clean it up.. apply a small amount of flux on the pins and reflow with the griddle the same way. Parts should pop into place. Do this initially on old boards and you will get the hang of it. I did not ruin any boards while learning but I could have.
Notice how the IC's are nice and straight and the Si570, is well, perfect. The capacitors and other 2 and three terminal devices are done with stick solder and two soldering irons. If you do that the capacitors will surface tension reflow just like the IC's did on the hotplate. If you don't stencil, I personally believe it's faster to place them that way.
The top side of the board I built all with stick solder. Not much to say here but flux well, and clean up really well. Please always clean your boards. Flux can corrode in some cases and it always can hide cold solder joints. I often will clean.. rework a half-dozen connections and clean again. Your boards can and should look like they came off a professional wave solder machine. Once you start building this neatly your first time success rate in testing will be nearly 100%.
Top side:
The board has been partially tested. The Si570 circuit and microcontroller is working. My only complaint and fear with these boards is the awkward mounting method and complex toroidal transformers. I think I have them correct.. hopefully in the next couple of weeks I can verify and get this on the air.
Someday, I hope the Softrocks will go to Coilcraft and/or Mini-Circuit type RF transformers and chip coils. For that matter once you get used to building SMT... it is really quite a bit easier and faster to build and the final product comes out better. I am not criticizing Tony Parks (who is a saint) for designing and kitting these this way as most hams fear SMT. Hopefully I can help convince them otherwise. The day of the through hole part has passed and like it or not, they will dwindle in availability until they mostly go away. But, actually once you learn how to build SMT, you will like it better...
I was originally going to build my SDR-Cube with this rig external. I will eventually try it as I'm going to configure it for both internal and external. But.. since I decided that building SMT is better and really the 6.3 series Softrocks are more compatible with the Cube design (and a little backpack rig would be fun to have).. I've built a sr63ng, which is the "MOBO" version done by George Boudreau. George Heron agreed to sell me an RXAMP board and a TXPA board even though I passed on the base SR6.3 kit.. so I will have a "cube" built as intended before I start to hack it for other uses.
The sr63ng will be the next post...
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