This tutorial has been written from a poor man’s perspective, eg. tight a**e. In saying that, I believe that good quality PCBs can only be made with a U.V. lightbox. Don’t stop reading… I assure you I am a tight a**e, not the type of guy to spend money on anything. It took me years of fiddling about with vero board, etch resistant pens and iron on transfers before I even contemplated spending money on a U.V. lightbox. Although, from the first time I used it, the results were far superior to any other method I’d tried, and believe me, I’d tried them all!
To complete this tutorial you will require a U.V. lightbox. If you close this blog in annoyance thinking that one day you’ll work out how to make quality PCBs without a U.V. lightbox, I wish you luck but employ you to revisit when you realise you can’t.
“Ok, so if I need a U.V. lightbox, where can I get one?”
First things first, here is a shopping list of everything you’re going to need and where you can get it from:
- Schematic drawing software (I highly recommend the freeware EAGLE program by Cadsoft http://www.cadsoft.de/freeware.htm )
- Transparencies (These are getting quite hard to obtain. In Melbourne, Australia my local Officeworks only had laser printer transparencies. Laser printers can be found at local libraries or friends and families workplaces)
- U.V. Lightbox (I got mine from Kalex - http://www.kalex.net.au/ The model shown in this tutorial is the PORTUVEE4 available from Kalex. In the November 2007 issue of Silicon Chip magazine http://www.siliconchip.com.au/ an article details the construction of a U.V. Lightbox. The author recommends to buy all the required parts from Kalex)
- PCB pre-coated Kinsten positive acting boards (I got mine from Kalex - http://www.kalex.net.au/ they have several different sizes. The model shown in this tutorial is the 100P150 available from Kalex)
- Developing solution (I got mine from Kalex - http://www.kalex.net.au/ . The solution shown in this tutorial was ordered under the code DP from Kalex)
- Ammonium Persulphate (This is available from Jaycar Electronics http://www.jaycar.com.au/index.asp under the code NC-4254)
- A kettle
- A small plastic container (A container bigger than the size of the PCB you intend to manufacture. The container should not be used for anything except PCB work; do not use a container you eat from or have other chemicals in!)
- Paper towel
- Running water
- Steel wool / Scourer (I am unfamiliar with grades of steel wool, in saying that, a light steel wool or scourer is all that is required; nothing too abrasive)
- Surgical gloves
- Old clothes (If you splash the ammonium persulphate solution onto your clothing it may slightly damage it, especially if it is not washed after use)
- Hack saw (This is only used to cut the PCBs to there correct sizes)
- Scissors
- A clock or stopwatch
- Measuring jug (The measuring jug is only used for measuring water quantities. Any kitchen measuring jug will be sufficient)
- Small scales (The scales should not be used for anything except PCB work; do not use scales you eat from or have had other chemicals in!)
- A sealable bottle (The bottle is only used to store the ammonium persulphate solution whilst being transported to an appropriate place for disposal. An old soft drink bottle will be sufficient)
Create your schematic image; I highly recommend you download and use the freeware EAGLE program by Cadsoft. Once you have completed your design and every track is exactly where you need it to be, then you’re ready to go!
A monochrome (black and white) version of your schematic image needs to be obtained. This is how I generate one using Cadsoft’s EAGLE and Microsoft’s Paint:
- Have the ‘board’ file open in Cadsoft’s EAGLE program
- Under ‘Display’, deselect all layers except ‘bottom’,’pads’ and ‘vias’. Every thing at this point displayed on the screen will become a copper track on your PCB
- Select ‘File’, ‘Export’, ‘Image’
- Choose the destination for your file and then name it appropriately
- Select from the window ‘monochrome’ then increase the resolution to 600 dpi. (The higher the resolution the smoother the tracks on your PCB will be)
- Select ‘OK’
- The bitmap image will currently have all the colours inversed. Open the file in Microsoft’s Paint, select ‘Edit’, ‘Select All’
- Then select ‘Image’, ‘Invert Colours’. Save this image; this is the image needed to manufacture your PCB
- Select ‘File’, ‘Page Setup’. Ensure the image scaling is set to ‘Adjust to 100% normal size’. DO NOT STRECTH THE IMAGE IN ANYWAY! Select ‘OK’.
- Place a transparency into your printer.
- In Microsoft’s Paint, select ‘File’, ‘Print’, then select the button ‘Print’.
The following PowerPoint presentation details how to manufacture the PCB:
If you place the printed transperancy with the printed side against the board, less light will bend around the edges of the ink.
When making PCBs the ammonium persulphate can damage your clothing. Below is a shirt I was wearing when I was making PCBs, it was splashed slightly with the ammonium persulphate solution. I did not wash it and as you can see it did slowly and eventually erode my shirt and leave red spots across it.
The ammonium persulphate solution should not be washed down the sink. Below is an e-mail I received in 2006 from 'Sustainability Victoria' regarding the disposal of ammonium persulphate .
Subject: Disposal of Ammonium Persulphate
Dear Ben,
Thankyou for your inquiry.
The Detox Your Home service is a free, mobile service for householders to dispose of household chemicals. You can dispose of ammonium persulphates through this service. The list of sites you would have been given when you rang is our 2006 timetable, also available on our website:
http://www.sustainability.vic.gov.au/www/html/2047-detox-your-home.asp Unfortunately we do not have a map available.
We are currently in the process of preparing the 2007 timetable, it should be available on our website by mid October. If you are able to store the chemicals and wait for a collection in your area, the City's of Whitehorse, Knox and Manningham will be hosting a collection in 2007.
The service rotates around the State on weekends, with approximately 35 collections a year. Due to the nature of the materials collected, each event is staffed by qualified chemists. There are no permanent disposal stations available for free disposal of toxic chemicals. You will need to visit one of the collection events, I would suggest the collection in Camberwell on October 28 from 8am-4pm at the Council Depot, 648 Riversdale Road Melways 60B1.
Alternatively if you are willing to pay for the disposal of the Ammonium Persulphate, there are a number of chemical treatment and disposal companies who could dispose of them for you.
