Kinsten - Presensitized PCB
I had a trip to Taiwan on May 31 and i'm coming back soon. During my trip i came across several electronic shops and man they sell electronics for a very cheap price. A white or blue Led is about 6 tai bi which equals $0.04. and the price just keeps going down for red yellow and green. So i got a few. While in the shop, I also so this Kinsten Presensitized Board. This was a different type of PCB board that was easier and more accurate to create PCBs. I got it for about $2. So I started my research. There are 5 steps:
Step 1- Create PCB design
Step 2 - Print it on a plastic/ trsparent paper
Step 3 - Expose it to UV light/Floresent light
Step 4 - Remove the photo sensitive coating to expose your design
Step 5 - Etch
This is very easy and more relaible than having to iron on the toner to the copper board. Cause sometimes your not accurate and you peel of the paper and some toner is still on the paper. So the next few days follow me as I start this tutorial on Presensitized PCBs. This will be a LED testcircut I designed a few days back. :)
PCB software is everywhere. But the one i like the best is express PCB. It free and easy to use. You can download it here.
You can easily learn how to use it by just looking at it. I already designed the LED test circut. Although I might make some changes. If you see a problem tell me and I'll fix it.
There is a voltage regulator to lower the harsh 9V to a nice 5V. the 330 ohm resistor protects the LED when the Varrible resistor it all the way to 0. You can adjust the 10k varrible resistor to your desired brightness and then measure the resistance at the ohm intersection. then you can also measure the amps and voltage passing through the LED at the V/MA section.
I want to upload this PCB file but the site won't alow me. I don't know any other place to upload this so you guys can have it.
I've updated the circut abit by placing in a switch to turn it on and off.
After you have designed your PCB change the colors of the screen. Backround to white. copper traces to black. Then when you ready to print. view only the bottom copper layer and uncheck the silkscreen and top copper layer. this can all be done in the the View > Options. And to change the color it's View > Options > Color.
It should look like this ready to print:
Then you wanna run out to Staples or any office supply store and get transparent Paper:
The paper should look alittle like this when unpackaged. I would take a picture ofone alonebut then you couldn't see it!
Then just stick it in your printer and print as usuall. When it comes out it looks like this:
The plack markings prevent the light from going to the board. So then the photo resist around the black lines disappear and the when you etch it the photo resist remaining protects the copper layers from etch.
I took the PCB out and cut it to the specifications.
When cutting, I used a hacksaw. This one was bought at home depot for $3. A little back breaking work but it works. Bansaws would work better though.
Also make sure to cut it under red light or in a dark room.
I turned my downstairs bathroom into a darkroom just with a red light bulb boght at home depot for $3. then went to go expose it under a floresent light. all you have to do is lay your plastic PCB design on top of the board and then place a piece of glass over it so it doesn't move. I didn't have glass so I used clear plastic. The board has to be about 4-6 cm. away from the light. very close.
To quater is there to keep theplastic straight instead of lop sided. although the label on the bag says expose it for 10-12 minutes. i did for 30 just to make sure.
Then get out some sodium hydroxide or developer solution. since my dad is a chemist i got some sodium hydorxide instantly. if your usuing pure sodium hydroxide. make sure you dilute it very well. if it is not diluted very well it will eat through everything.i used 50% sodium hydroxide. about 1 part sodium hydroxide to 20 parts water. Once you dip it in it eats away the nonexposed an leaves your exposed traces.
Looks good huh. After that, just leave it in the sun or under the floresent light for a while so the photo resist gets even harder. this is to ready it up for etching.