Direct to PCB InkJet Resist Printing

This page details the use of Epson^{^} InkJet printers with pigment based inks to feed and directly print resist patterns to copper clad printed circuit board stock, ready for etching. Once you can feed the PCB through the printer for etch resist, you can then feed it back through the printer for solder mask (yes! Several people report that it works quite well!) and for a component "silk-screen".

Toner transfer is probably easier to set up for and may be as fast, but direct ink is more precise, allows solder mask and component printing in the appropriate color, and most importantly, finer traces and spaces! And if you admit that a laminator is required for TT, given the prices for old C84^{^} or R220^ / R280^ printers and the Inks, direct to PCB InkJet printing is cheaper. Photoresist systems do allow finer boards, but equipement and materials costs, as well as time are substantial.

The secret (discovered by Volkan) is that certain pigment based inks, such as MISPRO Inks^ (#MISPRO42-SET-MK) or FullSpectrumEngineering.com Resist Inks^, can be cured with heat to form a very strong resist. The Epson InkJet printer use pizeo electric actuators in the print head (rather than the thermal method used by other brands) which allows for a wider range of ink types to be squirted out. The "Durabright" inks include a pigment rather than dye. The solid base in pigment inks apparently provides a resistant cover that will actually stand up to the echant after it is melted onto the board. For more, see: http://inkcityusa.com/epson_durabrite_inks.htm

Even without an inkjet ink that will stand up to echant, you can print with an inkjet and then dust the wet ink with toner in a hybrid of inkjet and toner transfer.

This guide was written by Stefan Trethan and edited with comments added from Volkan Sahin (Volkan not Volan, Voltan, Votan, etc...) who first developed and shared this method on the Homebrew PCB Yahoo Group^{^}. A new group InkJet PCB Construction^ has been formed for more specific discussion.

These pictures show a typical modified printer, a PCB blank being printed, and the sort of results some people are getting. That is a TSSOP chip!

Printer Modifications:

CD/DVD printing trays. (make small PCB's with NO modification!) Artisan 50, Stylus RX580, RX595, RX680, R260, R280, R285, R290, R380 don't really need to be modified, just cut out the CD/DVD spindel in the tray so the PCB can lie flat. This allows PCB's up to about 3x5". For larger PCB's the printers can still be modified:

• C84 by Stefen Trethan
• C87 by epineh^
• C88 by wnnelson
• CX4200 by Volkan Sahin. Volkan has also produced a custom flatbed inkjet direct PCB resist printer of his own design, using the heads from an Epson Inkjet.
• R220 or R2xx series by Bora Dikman
• Artisan 50 by Richard Liberatoscioli
• T20 by ScottA

Process

• PCB Preparation
• Printer Settings
• Printing
• Curing
• Etching

PCB Preparation

Sand the PCB with 600 or 1000 grit paper so that the surface appears scratched everywhere. You may also use a abrasive plastic pad sold for cleaning copper pipes before soldering.

Then wipe with acetone, twice, the first pass should take away the copper dust. The PCB must be grease free now and stay that way.

Pre-Etching?

Bora Dikmen says: "...before printing, you should bath the PCB about 1-2 minutes in acid (H-Cl + H2-O2) to become purple-brown in color. This creates a soft surface and ink will be printed very smoothly as if it is printed onto a paper. Otherwise, ink is populated on some areas, waved in color and not evenly distributed on the PCB."

Pre-Heating?

John Mardock says "... tried the MIS yellow (MP-4-Y) we have been using with the heated board with good results. I made a series of 5 boards using this yellow from 75C to 105C all with about the same success. The boards are heated in the oven for several minutes to stabilize the temp and then removed and positioned in the printer. I am sure there is heat loss during the process. The great news is this board heating does handle the puddling effect that has been such a pain. The dry time for the ink is just about instantaneous on the heated boards as you might imagine. Seemed the higher the heat the better the coating of the ink. ... The other interesting aspect was one of better resist with less ink being deposited on the board."

Printer Settings

When printing a purely black test pattern I found the transparency setting does not use any ink from the black cart at all. The other settings use ink in varying amounts, the most ink is used for matte paper and the least for glossy or durabright setting. You need Photo or Best Photo resolution. The "fast" setting, which prints in both directions of travel, produces better results for me. No edge smoothing needed.

• Screen shots of Stefen's driver settings for the C84: 1, 2
• Screen shots of Volkan's driver settings for the CX4200: 1, 2
• Screen shots from FullSpectrumEngineering.com for the R280 1 This is Step 6^ of their excellent tutorial at: http://www.fullspectrumengineering.com/tutorial.html

Printing

This video from Full Spectrum Engineering (http://www.fullspectrumengineering.com) shows an unmodifed Epson R280 printing a PCB which is being held in the CD/DVD tray via the Stainless Steel PCB Holder which aligns a 3.5" x 2.5" PCB blank perfectly. The only modification necessary is to cut out the spindle mount in the CD/DVD tray accessory, which can be puchased seperatly from the printer. This holder is now available in the USA from us!

This video shows how to use a modified C87 to print and etch a PCB.

READY LOADED

To print you must insert the carrier manually into the printer. Turn the printer on, and wait until it has completed it's dance. Now feed the edge of the carrier into the printer so that it just protrudes a few mm from the traction/pressure rollers. Make sure it is straight so it will not run against an edge when the printer feeds. Now print the artwork on your carrier to find the right position (stick some tape or adhesive backed plastic foil on it or you may end up with permanent marking of the carrier). You can use low resolution for this print since you only need to know where it will end up. If you use the fastest draft setting watch out, the printer virtually shoots it through.

Now place the PCB over this position and stick it down with tape along the edges (take care not to cover any holes, the printer may look for those for alignment) or using double sided tape underneath. You may delay the acetone cleaning of the PCB until this point if you prefer. Again feed the carrier and print the artwork.

Hybrid Ink/Toner

If you choose to try the hybrid ink/toner method, dust the wet ink with laser toner or embossing powder at this point.

Curing

START ALMOST CURED

This is a key step. The PCB and ink must be heated to a specific temperature to cure it and keep it from coming off in the etchant. To do this, a stove or heat gun will not allow the required temperature control. Something more precise must be used: Basically an old electric hot plate with a aluminum plate on top and a temperature meter attached.

For MISPRO Inks: It turns out that around 446F / 230C is the sweet spot. keep that for several minutes (at least 3 i'd say for now but more research needed). This incidentally is exactly the point where the copper will start to go from just minimal yellowish oxidation to a purple one (This is probably what Volkan is using to judge the temperature). It is well away from damaging the PCB.If you are much below or above this temperature the ink will not resist so well. Round about 225C the ink starts to change somehow and can no longer be cleaned off, even with acetone.

For FullSpectrumEngineering.com Resist Inks^:  212-230'F, 100-110'C for 5 minutes.

For Hybrid Ink/Toner: Use the temperature at which the toner or embossing powder melts. It will be very easy to see, as the powder will suddenly become shiny.

Etching

I suspected Ferric chloride is less aggressive to the [MSPRO] ink than CuCl, so i set up a test. I cut a test PCB in half after curing to get identical samples, and put one in CuCl and one in ferric chloride. If anything the ferric chloride showed more aggressive under-etching. In the samples below, the lines above 3 mills are fine; below 3 they are unreliable.

scc_11067 says: "[using Durabright inks] ... I switched to ferric chloride and get really good results. I am currently using durabrite yellow with really good etch's Could use durabrite magenta, but the ink bunches up on the board if not dried instantly.  The persulfates just lift the ink off the board."

See also:

• spamilie321 at yahoo.com refers to " http://esupport.epson-europe.com/ProductHome.aspx?lng=en-GB&data=zbff+oTjl0FGNLU1Fzdl8M3LB2K5gNT5 hallo it is possible to modify epson D68?" +
• spamcassiano at atc-br.com.br refers to

  http://www.polaco.pro.br/pcb-epson I have made the same with an Epson Stylus Color C43UX, but after the print finished, I've powded Laserjet toner on the PCB. So I wiped the excess from the board and heated it. The toner melted and fixed on the board. The corrosion is perfect, and the results where impressive.

• http://stores.ebay.com/PCB-Laminates-Copper-Clad ABCFAB PCB Laminates and Copper Clad. Highly recommended for all your blank PCB needs, including thin materials that can be fed without modifying head height. +
• http://groups.yahoo.com/group/Homebrew_PCBs/message/15769 Bill Mcgough suggests using powder coat from standard powder coat painting to soak up the wet ink and then bake it to adhere it to the copper where the ink has been printed. The extra powder coat just wipes off.

Questions:

• Well, I just got a canon ip4600, I suppose it uses pigment ink, it comes with a cd tray for direct cd label print, I would like to try in direct printing my pcbs, so first thing before I drill a hole in the middle of the tray is to drill a hole in a blank pcb and cut it to cd size, print and post the results.
  but my question is what software to use later on as cd label software leaves a circle in the middle that is not to be printed. I use eagle free software. can you shade some light on this point please?
  Hatamata James Newton of Massmind replies: Use any OTHER software to print.+

  +

• Has anyone tried to use other pigment based inkjet printers?
  The Epson UltraChrome is also a pigment based system and is compatible with CD/DVD media. Perhaps this would allow printing of PCBs without heavy modification.+
• I' m looking for water resistant ink (Like MisPro) for HP 695c.
  Do you know something?+
• cbarton270(at)alltel.net asks:

  I'm trying to set this up using a cannon bjc-240.
  I think I can just dremel the sheet feeder into a wider opening.
  It only cost a dollar at a yard sale.
  I was wondering if your could heat the boards before printing to make the ink stick better.Also, what other inks could be used.
  My wife refilled a cartridge with india ink .It worked for a while but I think it dryed up in a couple days.

• spampato.donald.pato at gmail.com asks:

  Have you tried using the ink as soldermask? I did, but unfortunately the results were not that good, as the ink did not managed to stop the solder.
  How did you do it? Different ink?

  James Newton replies: I haven't personally done it, but I believe the key is heat curing the ink prior to soldering.+

  +

• spamankada at hotmail.com asks:

  volkan bey ben soner
  ankaradan
  sizinki gibi bi yazýcýyý tekrar bozup yapmak istiyorum
  malzemelerini hazýraltoyýrum
  a4 yazýcýnýn yazcýný kafasýnýn gidip gelme alanýný büyütmek istiyorum. tüm donanýmlarýný hazýrlasam þerit de dahil. bi problem çýkarmý ?

• spamBilblog at gmail.com asks: " OK, Just what I was looking for("Direct to PCB InkJet Resist Printing"). But what ink do you use for the soldermask? Thanks, Bill" James Newton replies: The same one, the same process, just don't etch it and you can mix the color a bit differently. Use more yellow for example.+

  +

• Show !!!!!!!! James Newton replies: Show what? :)+

  +

Comments:

• I really need to contact Mr Volkan.
  We need to drive an F158010 Epson head.
  is for commercial proposes.
  Please contact me mollet2@cantv.net.
  
  Best regards
  
  Antonio+
• can you put a video shot+
• Really nice indeed. But, ink does not dry. I have modified D78 printer. Results were satisfying.
  
  Alper A.
  James Newton replies: The key points are using the MISPRO inks and baking the board until the inks harden.+

  +

• good+
• Paul G, Have been using this method for a while now, v good results, if you pre etch for a few seconds in ferric chloride, then print using Durabrite yellow using fast and matt paper settings ( I usually change the PCB printing colors in paint). Then burn the ink on for a few seconds with a blow torch, this turns the ink black/brown in color (much cleaner than baking), then etch in ferric chloride, the ink hardens really well, after printing with the yellow ink there should be a fairly thick layer of ink on the surface of the board........If not you heads might be blocked.+
• Wow. You can be sure that I am making one. Thanks a bunch.+
• Be sure that the parking rubber (that the print head sits on when the printer is off) is in place and in good shape. If the print head drys out, the ink is totally impossible to remove. You might want to fire the printer up and do a test page every week or so.

LCD Front Panel Set: $8.99! - 2x16 LCD HD44780 controller - 4 push buttons - 3 LEDs - 2x12 header

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