Solder Reflow Oven – Hardware Mode

OK so it’s been a while since my previous post. I didn’t start directly with the solder reflow oven board creation from my previous post (Sorry if I kept some people waiting). I have some other projects in the pipe line and I wanted to source all the components for the following projects with the ongoing projects in one go. Next up will be an power supply unit with variable current limiting functionality with an automatic battery charger (Engaging and disengaging the charger depending on battery voltage level). But this will only happen once the solder reflow oven is completed.

So back to the reflow oven. I revised the board designs in Eagle CAD since there were some things that were incorrect on the previous designs. The new designs of the boards looks like this:

Display Brd

Display mounting board – mounts all other boards as well

Button Brd

Button Interface Board

Relay Brd

Relay Board – For switching the elements and the extractor fan on and off.

Shield Brd

Solder Reflow Oven Shield – Board that mounts onto the Arduino Uno board and distributes the signals and get the temperature measurement from the thermocouple.

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So after I’ve finalized the designs I made sure that everything fitted correctly and then I re-sized component packages if it didn’t fit correctly.

So after all the planning and testing it was time to fabricate the boards. I transferred the circuit diagram to the plain copper board using the toner transfer method of creating PCBs. The results were good except for some things that didn’t align well but none the less the boards came out well.

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Drilling holes

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Finalized PCB boards looking good (“,). Note that I’m using normal relays and not solid state relays. Salvaged most of the components that your see here from old units.

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Lots of wires (“,) – putting everything together to make sure that it is working and that there are no broken connections or bridges that I’ve missed perhaps. The Shield board didn’t come out very good. This is because I didn’t remove all the paper residue from the copper before edging the board. I then ran out of glossy paper and had to go and get some more and redo the board. The second transfer looked really good and it aligned well.

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Top and bottom of the same board in different pictures.

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Me edging away on our kitchen top with a protective piece of off-cut wood below.

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The problems started when I started drilling and fitting the components.  The components didn’t fit correctly. Initially I thought that the alignment was not correct and so I struggled onward. I then tried to mount my ribbon cable connectors and I had to seriously start bending the pins to try and fit it. This was now at 12 O’ clock at night. I then tried to fit it by soldering it onto the surface of the board but I didn’t get it right and tried to remove the connector from the board. I then ripped my ribbon cable connector’s pads from the board by accident and effectively destroyed any hope of recovering the board :(.

That was it, I decided that I would call it a night (This was now last night – 2013.11.13) and I went to bed. This morning I tested the board to see if it would fit into my Arduino Uno board. No luck, so I’ve printed the transfer of the board on plain paper and tested the size, the mounting holes and header connectors spacing of my original Arduino Uno on my printed out transfer of the board. Everything fitted nicely, so why didn’t my board come out correctly?

I took the transfer of the board on the plain paper to work since my work has a laser printer which I use to print the circuit board transfer onto glossy paper.  When I had a chance I printed the boards on plain paper again and tested the size of it against my reference transfer of the board which I’ve tested this morning. The sizing was off by a few millimeters meaning nothing would fit correctly :(.

I then went through my printer settings and found that the some of the settings caused the sizing to be off. So I’ve corrected it and tested the newly printed transfer against my reference transfer and everything aligned. So I will create another board this evening and populate it and then hopefully next week I can show you an assembled piece of equipment (“,). Drop me a comment if you have any questions, hope you’ve enjoyed this post

 

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One comment on “Solder Reflow Oven – Hardware Mode
  1. stephen says:

    i have to scale up by 4.1% exporting from gEDA pcb program.
    found out in much the same way:-)

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