Well, back from a short break away (kid free woohoo!) and onto some widget builds. I thought I’d document how I do my widget construction. I actually find building SMD devices much easier than the PTH variety.
I have all my components in some neat snap together containers, this allows me to have everything at hand for the build.
[Click on images for larger size)
1) Solder paste is applied to the boards sparingly, ready for component placement
2) Components placed on each board, I usually do a board at a time. You will see x3 boards without any RF modules, these will be added at a later time depending on what band is required.
My SMD toaster oven setup.
The toaster oven is unmodified straight out of the box connected to the PID temperature controller.
PID Ramp controller with Solid State Relay output driver from E-Bay, that allows me to store up to 64 different temperature/time steps, each step can have their own PID parameters. The ramp controller allows me to set and store my solder temperature profiles and when enabled will cycle through the temperature profile.
The PID controller is installed in an external SCSI case I salvaged from an old external tape drive.
The thermocouple is a K-type with the shroud removed to give a fast response to temperature changes, I also have it wired to a spare PCB to give me a good indication of the PCB surface temperature in the oven
Rear of PID controller case, I’ve wired a power point directly a 10A solid state relay and fuse. The SSR is driven by the PID output, so power is only applied when heat is required. This allows me to use any unmodified toaster oven. 
Batch ready for baking, carefully placed onto tray so no components are moved in the process.
All I do now is start the Temperature controller and let it do the rest (after closing the door) Since the Toaster oven is unmodified in any way I just turn it’s temperature knob to the max temperature and the same goes for it’s timer. The bottom power light turns on when temperature controller is heating.
My hi-tech fuse and bootloader programmer ready for programming. The headers give me good connections and allows for easy changeover.
Fuse and bootloader being programmed
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PDF 
July 12th, 2009 at 11:39 am
Cool stuff.
Are you using RoHS solder? Can you give details on the particular PID circuit/software you are using? What type of oven are you using, and what is its maximum temperature? What’s the maximum length board you could put in it? I have some MCPCB’s about 11″ long I’d like to populate – do you think I could fit one in and get even enough temperature over the length? Have you ever measured the temperature variation at different locations in the oven? When the controller turns off the oven, how fast does the internal temperature fall ?
And where did you get those cool parts boxes?
July 12th, 2009 at 10:54 pm
Thanks,
The PID is all done in the controller and programmed from the front panel, not the easiest thing to program, but once in I haven’t needed to change it. These are stock standard industrial PID controllers, in this case it’s a ramp controller, capable of 64 steps in which the PV, alarm parameters and the PID tuning parameters can be set for each step, as well the time required to go from one temp to another i.e a temperature ramp. I got it from ebay for about $US90 with the thermocouple, they have different output types, so you need to get one that drives a solid state relay, all you have to do is hook up a SSR directly to the output. I’ll get a circuit and photos online shortly, but is very simple.
The oven is one I got for the local discount store, I went for the cheapest that and it can do 250 deg C, the brand is Minstral I think, it has 250deg on the dial as max temp but I’ve driven it past that.
I haven’t measured the variations across the oven, which I’m sure will be there, I’m using the aluminium tray as I’m hoping it will act as a bit of a heat sink and stabilise the variations. When the controller turns the oven off, it does take a while to drop temp un assisted and door closed, a fan would be good addition and could be hooked up to the alarm outputs, but I currently open the door slightly and this seems to work ok.
The cool part boxes are http://www.dealextreme.com/details.dx/sku.4580 (pretty addictive site lol)
July 18th, 2009 at 5:49 pm
Nice done Stephen,
I try to implement your settings into a FPGA hardware board. I need on the TX side this hardware because the full application of the laser detection to capture in-flight insects. For extra flashes, your solution as receiver must be very good. Because I need a very high speed, only a subset of your function have to be used. But i will test this and i will give also the results when finish.
Your work is realy good and have perfect documentation. I try to use the most parameters on the same way. Here in Belgium we need to work on 866Mhz but thats only a small adjust of the parameter setting. I prepare now 2 RFM12B modules on my breadbord and the DE1 Terrasic hardware FPGA unit. Later the receiver can be the AVR module.
Frans
July 20th, 2009 at 9:11 am
Hi Frans,
Thanks for that, If you need help/settings let me know. I look forward to your results.
Stephen…