By Mike Giamportone
Here is a fast and relatively easy way to accomplish one of the more difficult parts of any electronic project construction. If you are looking for a technique to give your project a unique professional look... read on.
This article will explain exactly how you can make your own PCB's and/or enclosure labels at a relatively low cost.
All that is required is a L2000 Laser/Copier Iron-on Resist Sheet and follow the procedure explained here and your on your way...
Do all your project enclosures look the same? Would you like each one of your project enclosures to look unique, and express you creativity? Maybe you're tired of those amateurish-looking label tapes that eventually peel off. More than likely, you have seen a design that would dress up a project nicely, but lacked an acceptable way to apply it.
Do you find creating very populated printed circuit boards intimidating? How about ones with traces running between IC pads? Are you finding that rubbing a pattern down to make a PCB, time consuming, costly, or frustrating? Well, here may be the answer to your prayers, L2000 Laser/Copier Iron-On Resist Sheets. This new product will give you the quickest and easiest way to make a printed circuit board or label an enclosure. Using the latest in iron-on resist sheets, you too can craft electronic projects like a professional. All that is required is a L2000 sheet, household iron, and use of a laser printer or plain paper copier.
There are just a few simple steps to make PCBs or great looking enclosures using L2000 sheets. Copy the desired pattern onto the special plastic sheet with either a laser printer or copy machine. Tape the copied pattern to your board or enclosure, and iron in place.
Remove the sheet to find your pattern transferred to the metal surface. For a PC board, it would be ready for etching, that quick! By making several patterns at a time, you can select one whenever needed from your files. This will save even more time and effort especially when building multiple circuits or enclosures.
The process starts when the laser printer or copier applies a copy of the selected artwork to the sheet, and heat fuses it in place. This is done with toner, the machine's dry powder ink. When the L2000 sheet is reheated by ironing, it releases the toner that now bonds to the metal surface. In the case of a PCB, the ink becomes resist.
Resist is any acid-proof material used to protect parts of the board, when submersed in the copper-eating etchant. Once soaked in the etchant, all exposed copper is removed from the board. This leaves only the copper under the resist. After rinsing, the resist is then removed to uncover the copper traces and pads, comprising our printed circuit.
Making your own iron-on resist patterns begins by washing your hands to remove body oils that will interfere with any resist and etchants. Handle the laser sheets and the board or enclosure to be labeled, by the edges only. If your sheet seems dirty or mishandled, clean it with a little rubbing alcohol and dry with a clean paper towel before use.
When using a computer to generate the printed circuits or other artwork, you should print the artwork flipped, or as a mirror image. This will give you the proper pattern when ironed onto the new surface. Most printed circuit making programs, like PC Boards, do this by printing the foil (lower) layer as it appears from the component (upper) side. This will be the mirror image needed when printed. If your PCB program does not print the reverse image of the foil pattern, build your foil pattern on the component, or upper layer.
If you are using a computer graphics program to dress up an enclosure, (Like First Publisher, Print-magic, Deluxe Paint, Printmaster, and many others), you can flip or invert the artwork to get the mirror image desired. Not all graphic or PCB programs will print the reverse view. In these cases, treat your art as you would ready-made work.
In the cases when your artwork is not the mirror image or ready-made artwork, follow these steps: Make a paper copy of the pattern to check darkness and quality before using the L2000. Take your design or even if it is a hand drawing, and copy it to a laser sheet. Then put this copy in the top of a copy machine, ink-side up.
Put a clean sheet of paper on top of the L2000 sheet to prevent a dirty copy machine lid from adding to your final artwork. Copy this flipped image onto another sheet of L2000. Making a second copy this way, gives you the mirror image needed. This is what has to be done with a foil-side PC pattern normally supplied in plans or construction articles.
Clean the intermediate sheet used to make the mirror image with acetone (nail polish remover) or similar solvent, dry, then wipe with rubbing alcohol. When working with flammable liquids, wear rubber gloves, protective glasses, and do so only in a well ventilated area away from flames or sparks. If the laser sheet becomes slightly cloudy after cleaning, it can be reused and has no effect on its performance.
When using a copy machine, be sure it is a plain paper type using dry toner. This type of copier is commonly used by libraries, most offices, print and copy shops. If the machine can copy to a transparency or overhead projector sheet, it will work just fine for making L2000 Laser/Iron-On Resist patterns.
Load the L2000 sheets where single paper sheets are fed. This is usually on top of the paper feed tray and where single sheets of paper are placed to make two-sided copies. In the few cases where there is no place for single sheets, place the L2000 on top of the stack of paper in the feed tray. If using a laser printer, turn the paper feed knob to allow the laser sheets to pass straight through, rather than route it back toward you.
This produces flatter, better looking patterns. Experiment with darkness whenever possible. The darker the pattern, the more resist that gets applied to prevent undercutting while etching.
Applying the artwork made with L2000 starts by preparing the board or enclosure you will be putting the design onto. Cut the blank PC board to size, or drill the enclosure/lid as needed. Thoroughly clean the metal surface with a plastic scouring pad, scouring powder, and plenty of water.
This is very important since the fine scratches will help the toner adhere. Scrubbing should be done in a circular motion and until entire surface is polished evenly. Aluminum enclosures and lids will require a little more effort since the metal is harder. Rinse well, dry with a clean paper towel, and handle by the edges from now on.
Trim the plastic pattern to the same size as the metal surface. With two pieces of tape, secure the design with the toner side toward the surface to be marked.
The plastic must lay flat. Drag your fingernail lightly over the plastic. If it feels rough where the pattern is, you taped the sheet on upside-down.
To insulate the board/pattern assembly from the cool table top, place it plastic side up, on an old magazine.
Cover it, with a sheet of paper towel. This assures maximum heat transfer from the iron to the metal surface.
This is essential to properly re-melt the toner.
Preheat a household iron for several minutes at 290 degrees F. or on cotton/linens. Once fully warm, place it squarely on the assembly while under paper towel.
Allow the iron to heat the assembly for 20 seconds.
Then move the iron around the entire surface with medium pressure for about 30 seconds. Remove the iron, turn off and let cool. Never leave the hot iron unattended.
Allow the assembly to cool COMPLETELY before removing the plastic. Peel the plastic from one corner slowly. You will find any minor toner deficiencies in the original artwork vanished when the toner re-melts. If any of the ink did not transfer, or the pattern is not completely black, just draw in with a resist pen. Sanford brand "Sharpie" permanent markers are the same as resist markers. "Sharpies" are available at most department or office-supply stores and come in several tip sizes. They cost about half as much as other resist pens.
Scrape any unwanted resist off with a razor or knife.
If you made a circuit board, it is now ready for etching.
This type of resist is very tough. But after etching, it can be removed in the normal manner using scouring powder and water, or solvent.
Enclosures require additional heating to bake the toner staunchly in place. Put the metal lid/enclosure in a 350 degree preheated oven for 5 minutes. The artwork will be just about impossible to get off after this.
To further protect the metal and artwork, spray a very light coat of quick-drying clear enamel on the metal while it is still warm. This not only protects and weatherproofs the art, but gives a bright luster to the entire piece. Additional coats may be applied after the previous one dries. Heavy coats may re-melt the toner and ruin the artwork.
ADDITIONAL TIPS Some hobbyists prefer to add one step before ironing resist artwork, by etching their printed circuit boards for one to three minutes before applying the pattern. This makes the copper more sensitive and adhesion easier.
This is usually not needed and only necessary if you find the resist not adhering well to your boards.
By warming and agitating the etchant, you can speed the etching process. This prevents undercutting of the resist. Even though this type of resist is tougher than dry transfer (rub downs) and other resists, it is a good idea to keep etching time to a minimum.
Print all dot-matrix PC patterns in the 2 times mode.
Then reduce the circuit pattern in a copy machine by 71% and then again another 71% to get the proper size pattern before copying to a sheet of L2000. The result will be a cleaner, better looking pattern.
Any sheet, paper or synthetic, that passes through a copy machine or laser printer has to withstand the high temperatures used to fuse the toner to it. L2000 Iron-On Resist Sheets are designed specifically for this and are not just "coated" as other sheets may be. The new material does not get old and deteriorate in performance like coated plastics. If past experiences with iron-on resist have been disappointing, try the latest. The 872" x 11" L2000 Sheets carry a 30 day warranty and come with complete instructions.
Give your enclosures a new look. Save time and money by ironing resist artwork to your circuit boards.
Inexpensive, yet simple enough for the beginner electronic enthusiast to use, L2000 Iron-On Laser/Copier Resist Sheets are the latest innovation for labeling enclosures and making printed circuit boards.
L2000 Laser/Copier Iron-on Resist Sheets are sold by Thumb Electronics, P.O. Box 344, Marysville, MI 48040. Costs for L2000 are $1.20 each plus $1.50 shipping and handling up to 4 sheets. Quantities of 5 sheets more are 80ยข each plus $1.75 shipping and handling. For technical assistance inquires, or any remark requiring a reply, please send a Self Addressed Stamped Envelope.
*PCBoards is an easy-to-run, menu-driven computer program to generate single or double sided printed circuit artwork for under $100. PCBoards, 2110 14th Ave.
South, Birmingham, AL 35205 1-205-933-1122.
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adapted from: Electronics Handbook 1992