PCB Resist Laminator
I believe I've mentioned that Ross developed his own means of applying photoresist film onto his large supply of PCB. This is one of the machines he created:
This device consists of a pair of heated rollers that apply the film onto the clean PCB. The PCB is fed from the top. The film comes up over the guides at the top to prevent creasing. Motors drive the rollers at a controlled speed through the device.
The device requires a separate 12V supply for the control functions and 240VAC for the motors and heaters.
It may be hard to see the decimal point -- the device is capable of handling substrates up to 2.5mm (not 25mm!).
This information is positioned on the side of the controller for the unit.
The instructions are very clear. I'm pretty sure I could figure it out! I know that Ross did many trials to determine the correct amount of compression required -- and this is just one part of the long process of building this tool.
Here is a view that shows the collection of guides and rollers. You can see the orange coloured heated rollers in the centre, and the small gap between them.
And a better view of the compression adjustment at one end. There's a LOT of work here!
A view from the other side with the cover removed. One of the motors can be seen here. For a number of reasons (including the spacing of the rollers) the two motors are mounted one at each end.
The angle views show some of the details more clearly. Power is passed through some of the guides made from tube for this purpose, eliminating the need for external wiring. These guides don't get hot, so the insulation is in no danger of melting.
Also note the flexible coupling between the motor and the driven roller to eliminate stresses caused by any small misalignment.
The cover removed for these photos has further instructions on the preparation of the PCB.
Some of the instructions are repeated briefly under the guides and rollers to remind you of some of the important steps.
On the front side of the controller are the main power switches and the pause switch to allow accurate initial placement of the substrate.
The back side of the controller has the mains connection and the programming port for the microcontroller. Sadly, I don't have the source for the firmware.
The top of the controller has the various annunciators and the temperature control.
After removing this cover, there's not a lot mounted to it, but it does provide access to the PCB -- and if you're careful you could operate the device with the cover off.
A couple of views of the PCB show how it all hangs together. Note that the other motor is mounted at this end with the shaft passing through the board.
I'm going to try to locate the schematic for this device, but I've not found it yet.
I do recall some things that Ross told me about the UV sensitive film. The film itself is supplied with a plastic coating on each side. When he received his first batch of film he was concerned that the packaging was not particularly light-tight. However he found it is not appreciably sensitive to UV until the film is removed -- probably the coating is opaque to UV. Once removed the film is very thin and very easily creased or affected by dust. I was also unable to find his supply of unused film :-(
It's not mentioned in the instructions, but the entire process had to be done under red light to avoid exposing the film. The small amount of green light from the LED is insignificant.
