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| PCB Inkjet Tips |
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Tip 1: Board Alignment The Stainless Steel Cutout is made exactly to 3.55"x2.55" with stated tolerances of +/-.001". The PCB blanks are 3.5"x2.5" with approximately +/- 0.03" tolerances. Higher tolerances cost more money so it is not economical to make the blank boards to super high tolerances. However, the most important issue is repeatability. The Epson CD inkjet printer tray has optical sensors that align everytime you print. If you attach the pcb blank in the same place everytime, it will have repeatable results everytime meaning (0,0) will go to the same spot on the CD tray. The important things are to attach the CD holder securely and not cover any holes a normal CD wouldn't cover. Remember that the edges of the Stainless Steel Cutout needs to be as 90 degrees as possible to the direction of travel so we recommend using a machinist square as in step 2. In addition, for single sided boards, always align the upper left edge of the blank with the upper left edge of the Stainless Steel Cutout. This is much easier than trying to align to the center (which is almost impossible). Tip 2: Double Sided Boards In your CAD program (Eagle or other), create the drawing with a rectangular box starting at (0,0) and extending to (3.55",2.55"). We have conveniently supplied an Eagle template with a 3.55"x2.55" box on the Dimension Layer and the words "Hello" on the top layer. Top layer: 1) Turn on the Top Layer Only in Eagle Bottom layer: 1) Turn on the Bottom Layer Only Explaination: Consider a pcb image imported into Windows Paint. Call the top left corner (0,0) and the bottom right corner (3.55",2.55"). When you flip horizontal, (x,y) is mapped to (3.55"-x,y). When you print the bottom image, (x=0,y=0) is translated to (x=3.55",y=0"). However, our blank pcbs are only 3.5"x2.5" so we want (x=0,y=0) to translate to (x=3.5",y=0"). We accomplish this by shifting the left margin by -.05". Try printing this image. Print this image with left margin=1.2" and top margin=1.4" on a piece of paper attached to the pcb. Flip horizontal and flip the board over and align it as described above for the bottom layer. Print it again with left margin=1.15" and top margin=1.4" and you will see the text lines up exactly on top of each other when viewed from one side. You want the same effect with trace lines on a PCB. Now the board layout no longer depends on the tolerance of the blanks but instead relies on the dimensions of the Stainess Steel Stencil which does not vary from board to board. Just make sure the Stainless Steel Stencil edges are 90degrees to the direction of travel otherwise you will alignment problems. Tip 3: Test boards Alignment is a bit tricky and requires some experimentation due to variations in printers and attachment points of the Stainless Steelcut out to the CD tray. The best way to do this is to use a knife and cutout several pieces of paper by tracing the edges of the blank PCB. Then just tape the piece of paper over the PCB and print with regular black ink. Don't worry about the tape, the printer will print right over it. This way you don't need to worry about washing off the ink or cleaning the board. Flip the piece of paper over and print on the other side too. This is also a great way to perfect your doublesided board technique as you can easily see through a piece of paper. Tip 4: Initial Alignment Print a cross in your CAD program at (0,0) and use a ruler to figure out the margin settings to get it to (0,0) on your board. Tip 5: Etching The most common pcb etchant available is Ferric Chloride which can be bought at any Radio Shack. However, it is a huge mess so be aware it will stain everything it touches. Ammonium Persulfate is a good substitute but is sometimes hard to get and slow. We buy ours at Frys electronics. Another etchant that works well is 15-30% Hydrogen Peroxide (available in the US at Sally's Beauty Supply) + Muriatic acid (available at pool stores). Instructables has more info on the technique. Use Ammonium Persulfate if you are having problems. It is the most gentle etch and we have had good results with it. Tip 6: Solder Mask While we haven't tried it, we heard you can print 3 or more times and use the ink itself as a solder mask because it is non conductive. Just print the solder mask layer separately after you have etched the board. Tip 7: Silkscreen Mask You can use the ink as a silkscreen but the normal ink we send isn't high temperature stable so will change color. We also have high temperature yellow ink that will not change color so please e-mail us if you want some of the high temperature ink. Tip 8: Heating the board We suggest you avoid heating the copper to the point when it turns purple. The copper has oxidized at this point and will be harder to etch than the shiny gold copper. Tip 9: Epson Artisan 50 Some people have reported that the CD doesn't print in the middle. There is a fix courtesy of one of our customers: GIMP (http://gimp-win.sourceforge.net/stable.html) on Vista and the Gutenprint (http://webblog.ru/Dickobraz/53719/Gutenprint524.html) plugin for GIMP allows to print to the CD tray properly. The Gutenprint524 plugin has to be copied in the "C:\Program Files\GIMP-2.0\lib\gimp\2.0\plug-ins" directory. When I printed from GIMP I chose the R280 printer, set the page to A4 with left margin 1.22 and top margin 1.36. Another important setting is MediaSource, which is set to "Manual Feed". When MediaSource is set to "Print to CD" it doesn't print where the CD hole is supposed to be.
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