For no other reason than I'm a sucker for punishment, I have decided to share my uber-lame but nonetheless effective reflow soldering setup. I have used this hardware to reflow solder a few boards (in particular a Bus Pirate 4 "DorkBot edition," and a GoodFET) as well as some small components on breakout boards and all attempts have been successful, barring a few solder bridges and components that somehow misaligned before the solder paste reflowed.
Looking around element14 and other sites, I see that many of you take your reflow stations very seriously. That's awesome! Some day I'll have a serious set of hardware that can handle heat profiles and such. For now, though, I'm staying scrappy.
Without further ado, here's what I use:
- a 1,000 watt Proctor Silex "Durable Fifth Burner" that I bought at Amazon.com for around $16 (free Prime shipping FTW)
- a 6" x 6" x 1/4" MIC6 aluminum plate that I got from McMaster Carr for around $25 including shipping
- a Harbor Freight Router Speed Control that I bought locally for around $20
I always use this setup in my laundry room on top of my dryer, right under an exhaust fan. Those solder paste fumes...yuck. Don't want 'em. Nasty, nasty stuff.
The burner has a coil which doesn't work very well with PCBs. The MIC6 aluminum plate somewhat remedies this by not only offering a smooth, flat surface for maximum PCB contact, but it also distributes the inconsistent heat that emanates from the burner coil. It's not perfect, but it works well enough for dirty reflow work.
The problem with this rig is temperature control. Folks that use cheap burners know that there is no actual temperature control; it's either 100% on or 100% off. The higher the "temperature" is set, the more time the burner stays 100% on; the lower the "temperature," the more time the burner is 100% off. You want consistent heat when doing reflow soldering, not long periods of "on" alternating with long periods of "off."
To remedy this, some people hack relays into their burners to turn them on/off quickly according to heat profiles. Others have external wall jack boxes that turn whatever's plugged into them on/off based on heat profiles. These are all severely cool setups. However, I am not that sophisticated (yet) and that's a lot of work.
So here's where the router speed control kicks in. The router speed control delivers consistent, adjustable power to whatever is plugged into it. Even though it's made for routers (which I assume are either 100% on or 100% off, hence the need for a speed control), there's nothing saying you have to plug a router into it.
What I do is I turn up the burner "temperature" to 100% so it's all the way on, then I plug that into the turned-off router speed control. Through experimentation and a laser thermometer, I have determined that a good setting for the router speed control is about 2/3 of the way into the "M" (medium) speed range. At that setting, it takes roughly 3 or so minutes to heat everything up when starting with a completely cool burner and aluminum plate. No matter where I dial in the "speed," the power that is delivered to the burner is consistent. The higher the "speed," the hotter the burner. The burner buzzes a bit (I suspect the burner doesn't like having its wattage limited by a router speed control) but so far no catastrophes have occurred.
With this all set up and dialed in, I place my PCB on the aluminum plate and switch the router speed control to "var," then the burner starts to slowly heat up. It's important that this process begin with a cool aluminum plate because everything needs to heat up gradually. Never throw a freshly solder-pasted PCB on an already hot burner!
Long story longer, after about 3 minutes the solder paste reflows and I remove the PCB from the aluminum plate. I was told long ago to cool PCBs on wood, not metal, so I have a cutting board that serves as a cooling surface.
And...that's it. Put a fork in it, because it's done.
Overall, I'm pretty happy with this setup. It cost just over $60 and I haven't had any issues yet. My house hasn't burned down, nothing has exploded, etc. And best of all, I have not had to hack any hardware to do this. Everything is off-the-shelf and in its original condition, save for a few scuffs. I don't know why I like that but I do.
Also, so far I have had no obvious damage to components. Everything I have soldered has worked just fine after solder bridges were fixed (if any), so I assume I'm doing at least most of this semi-correctly. Of course, if anyone out there wants to duplicate this setup, your "speed" setting may be very different from mine so experiment and measure frequently with a laser thermometer or other heat measurement apparatus, otherwise you'll risk frying your components.
Thanks for reading! If you have ideas for doing this easier/better/cheaper, please let me know. I'm always on the lookout for scrappier ways to get sophisticated things done.
(My Bus Pirate 4 "DorkBot Edition," reflow soldered on the setup above. Works like a charm. I apologize for the blurry photo. Maybe I'll swap it with a better one some day. Purple PCB is from OSHPark, obviously.)