I'm learning to do flexible circuit and the first thing that I try is a flasher bracelet, so this is a log of the first approach that I did.
Step 1: One
The circuit is the a 555 timer flasher based,
Materials you'll need
smd leds X 2
smd resistor x 2
smd 555 timer(I used a dip type)
A laser printer
A some other stuff...
Since I used the fotosensible pcb method I print the circuit in negative mode using some projection transparencies. Two or more are requiered to get a darker color that avoid unwanted exposure of some areas in the board.
The software used was eagle.
The copper sheet is placed in the transparency sheet, the transparencies sheet for the copper should be ticker than the one used for the printed circuit.
Step 2: Two
So the negative of the circuit should be placed on the sheet of copper.The copper sheet was joined with a light sensitive sheet that allows to transfer the circuit from the negative sheet to the copper sheet. one joined the must be passed trough a heat source eg iron, hair dryer or a laminator. the should be exposed to an UV light source for a couple of minutes. then it could be taken to a developer solution like baking soda mixed with water.
Step 3: Three
After etching the sheet solder mask is applied, this avoid the via and pads damage. But guest what? ....the mask didnt stick to the sheet, I have to fix that too
Step 4: Final
For the final step is recommended to use solder paste to solder the parts, more experiments will be performance.Thanks