Presensitised PCB
2005-12-08 by PPC
After lurking and learning quite a lot from many of you here, allow me to narrate my personal experience on how I make my very first PCB. 1) After making my layout in Eagle and printing it out in my HP laser printer, I made a positive film in my film contact frame. 2) Using a 2 Kw UV plate exposure machine with vacuum, I exposed my "Presensitised Positive (+) Acting FR4 Single Side Printed Circuit Board". 3) Test Exposure & Development Method: Using the method of step & repeat (in increments of 5 seconds and 6 steps - for exposure time of 5, 10, 15, 20, 25, & 30 seconds), a small strip of the PS PCB was exposed in the UV plate exposure machine. The PCB was then developed in about 40 seconds. 4) Test Etching Method: Etched the PCB in about 15 minutes. The etching time depends on the concentration of the Ferric Chloride. I used a small tray for etching and manually agitate it by rocking the tray. 5) Test Result: It was determined that the 5 seconds exposure was the best. Longer exposure time will render the PCB photo-resist to soften and make the needed wire to stripped out when being develop and etch. 6) My Actual FIRST PCB Exposure, Developing and Etching: Used 5 seconds for UV Plate making exposure for the PCB. Developed in about 40 seconds. Etch in about 20 minutes or less depending on the strength of the Ferric Chloride solution. 7) I uploaded a scanned photo of the PS PCB named "BOB-4.jpg" in the photo section under folder Presensitised PCB. My comments & observations: 1) Considering that I have an offset printing shop, I used my existing facilities like camera, contact frame, and UV plate exposure (with vacuum) machine to do my first PCB. 2) With the vacuum and high 2 KW UV lamp and my experience in PS Plate (that is a presensitised aluminum offset printing plate), I was able to produce a very good PCB in my first try. 3) The photo (I hope it is there) will show that the border frame and small text came out very clear. The border is 0.5 point and the text is 6 pt. I hope the above will be of help to someone and I welcome any comments, suggestions and questions. By the way, the PCB is for a simple breakout board with only a DB25 and screw terminals. I'll need help along the way when I try to design my BOB with buffering, opto, relays, etc. Thanks again to all of you. [Non-text portions of this message have been removed]