myUSBCtrlr Files

This the the PCB layout for the Bluetooth option

You can use this and leave out the Bluetooth if desired, it will still work.

URL for Thermal Paper
http://www.aliexpress.com/item/Hot-50pcs-PCB-circuit-board-thermal-transfer-paper-transfer-paper-A4-size-hot-sale-in/1036906319.html

URL for Etch Solution
http://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20151008122040&SearchText=pcb+etchant

URL for PCB board
http://www.aliexpress.com/item/10pcs-lot-FR4-PCB-Single-Side-Copper-Clad-DIY-PCB-Kit-Laminate-Circuit-Board-70x100x1-5mm/32255361688.html


I used drill of 0.8mm for most holes, 1mm for the transistors

2mm for the USB mount connector metal holes (not the 4pin connectors which are 0.8mm) 
- I used larger pads here and thus give more rigidity.

TO MAKE THE PCB BOARD

1. Clean/wash/rinse the PCB solder side of any dust, grease, finger prints etc.
It needs to be clean and shiny

2. Using a LASER printer, print the usbCtrlrSolderSide_BT_004.BMP file 
   onto white paper

3. Using a LASER printer, photocopy the printed layout from step1 onto the 
   shiny side of the thermal paper

4. Get an clothes Iron and set temperature as high as possible. Turn off any
water spray. We just need the heat

5. Place the PCB copper side up on a suitable sized board (I used a kitchen
cutting board)

6. Position the thermal paper (ink side down) onto the PCB. Hold in place
and run iron over. Make sure the paper does not move. Eventually after about
a minute it will start to stick to the PCB, at which point you can keep 
ironing the rest of the paper.

7. Keep ironing for at least 5-7 minutes till the paper is well adhered to
the PCB. You will need to apply a little force downwards (not too much).
Move the iron around so it doesnt overheat the paper in any one place.

8. Wait 10 minutes for the PCB to cool. Switch off the iron

9. Gently peel back the thermal paper. Most will come off. Some might be stuck.
Any stuck portions can be moisted with water. Don't rub too hard or the ink might 
come off.

10. Once you have the paper off, inspect the layout and repait any imperfections
using a PCB pen.

11. Boil about 1 litre of water. Put the etch powder into a square glass dish
big enough to hold the PCB. Then slowly pour the water into the dish. Be careful 
of splashes and don't get any on your hands. Use rubber gloves and eye protection.

12. Gently stir the solution with a wooden spoon till all the powder is dissolved

13. Gently place the PCB solder side up into the dish and then gently agitate the
solution with the wooden spoon over the next 5 minutes or so

14. You will see the solder start to disappear and the solution starts to turn green

15. Once the solder has been etched and it appears to be completed, take out the 
PCB (do not get any solution onto your bare hands) and rinse the PCB under cold
flowing water for a few minutes. Inspect the board and if necessary, it can go back
into the solution if some more etching is required.

16. If happy, then rinse the board again and dry off with a paper towel.

17. To get the ink off the board, you can use some cleaning agent like alcholol, 
I used petrol on an old rag and it came off quickly. Then rinse the board again
with soapy water, rinse with clean water and dry off.

18. Now onto drilling the board. Drill all the holes using 0.8mm.
Then use a 1mm drill to enlargen the holes for the transistors and headers.
Then use a larger 2mm drill for the metal ground tabs that hold each of the
USB connectors in place.
 
19. Fit all the top links in place first. Then the resistors, diodes, capacitors.
Then the transistors. Then the diodes. Then the headers. Then the Nano. Then the
relays, and finally the USB connectors.