The Hacker's Encyclopedia 1998

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Note: Uploaded to CompuServe by Steve Mason. I didn't remove the copyright notice, it was missing on the copy I got, from the Deja-News www server. ___________________________________________ PCB FAQ - DRAFT - FIRST RELEASE Contents: * 1: About the Author * 2: Copyright * 3: Preface * 4: ABOUT THIS FAQ * 4.1: Who put this FAQ together? * 4.2: How can I contribute to this list? * 4.3: What newsgroups will this FAQ be posted to? * 4.4: May I post this FAQ to my local BBS? * 5: DISCLAIMER * 6: Designing a Board * 6.1: Drawing directly onto the PCB material * 6.2: Using Transfer Films * 6.3: Using PhotoSensitive PCB material * 7: Making a PCB Layout for Photographic PCB production * 7.1: Using Pen and paper * 7.2: Using a computer * 7.2.1: Printing the layout * 7.2.2: Plotting the layout * 7.2.2.1: Photoplot * 8: Transferring the Layout onto the PCB * 8.1: Making the Film required to transfer onto the PCB * 8.1.1: Using a COPIER and transparencies * 8.1.2: Using Pelifilm from SENO * 8.1.3: Using Litex Photofilm * 8.2: The actual transferring * 8.2.1: How to make photosensitive PCb material yourself * 8.2.2: Buy ready made material * 8.3: Exposing the material and developing * 9: Etching the PCB * 10: Plating with Solder Lacquer, gold, silver, or tin * 10.1: Applying solder lacquer * 10.2: Applying Tin,silver or gold * 10.3: Silkscreening the PCB * 11: Doublesided PCB's * 11.1: Trough hole connections * 12: Do-It-Yourself section * 12.1: The exposure unit * 12.2: A Heated etching system * 13: Appendix A: Contact Adresses * 14: Appendix B: Products described in this FAQ _________________________________________________________________ 1: ABOUT THE AUTHOR PCB FAQ - DRAFT - FIRST RELEASE Author: Vincent Himpe E-Mail: Vincent.Himpe@ping.be Expires: 30 Jun 95 Archive-name: PCB-FAQ Date: 21 Jun 1995 This article is a collection of information sources on how to make your own Printed Circuit Boards My Signature: -------------------------------------------------------------- Vincent Himpe ///// Internet : O *) vincent.himpe@ping.be / vi_himpe@mietec.be \__/ Fido : 2:291/1912.8 -------------------------------------------------------------- _________________________________________________________________ 2: COPYRIGHT I disclaim everything. The contents of this article might be totally inaccurate, inappropriate, misguided, or otherwise perverse - except for my name (hopefully I got that right). * Copyright (c) 1995 by Vincent Himpe, all rights reserved. * This FAQ may be posted to any USENET newsgroup, on-line service, or BBS as long as it is posted in its entirety and includes this copyright statement. * This FAQ may not be distributed for financial gain. * This FAQ may not be included in commercial collections or compilations without express permission from the author. _________________________________________________________________ 3: PREFACE Now and then questions pop up on how to make your own Printed Circuit Boards. Since it is not always easy to get started with this something this FAQ tries to help you out. This FAQ contains a lot of my and other peoples experiences in making printed circuit boards. As usual the 'hull' of this FAQ was taken from the 8051-FAQ by Russ Hersh. Hope its useful to you guys and girls out there. Keep those replies coming Regards, Vincent _________________________________________________________________ 4: ABOUT THIS FAQ _________________________________________________________________ 4.1: Who put this FAQ together? I put this FAQ together in response to my own frustration in searching for information. Although I am not an expert on this matter, I think my and other people's, experiences can solve common problems. _________________________________________________________________ 4.2: How can I contribute to this list? If you have any suggestions or additions please inform me. You can contact me: By e-mail : Internet : Vincent.himpe@ping.be (preferred) vi_himpe@mietec.be Fido : 2:291/1912.8 By Snail-Mail : Vincent Himpe A.De Taeyelaan 12 8792 Desselgem Belgium I hope that those of you who know of interesting items for this FAQ will share with everyone by contributing to this list. A good amount of stuff is turning up thanks to everyone's help. If you are a manufacturer and have an anonymous ftp site or BBS available that has information available please let me know by EMail so that I can add it to this FAQ. Also, please feel free to update me on new products involved in PCB production. _________________________________________________________________ 4.3: What newsgroups will this FAQ be posted to? This FAQ will be posted to Sci.Electronics These newsgroups often contain discussions, announcements, or information about making PCB's. Check them out from time to time. The schedule for posting will be once a month. I can't promise that it will be on time, but I hope to post it by the end of each month. _________________________________________________________________ 4.4: May I post this FAQ to my local BBS? I am putting no restrictions on the use of this FAQ except - It must be distributed in its entirety with the COPYRIGHT NOTICE and DISCLAIMER and NO FINANCIAL GAIN MAY BE REALIZED FROM IT. After all, I have spent, and continue to spend, a lot of time on this. The only thing that I intend to gain from it is more information about making PCB's. For this reason I have appended a copyright statement to the end of this FAQ. I feel pretty silly doing this, but I just want to protect myself. The copyright does not limit the use of this list for noncommercial purposes. I hereby give my permission to one and all to pass this list around and post it wherever you want - as long as it is not for financial gain. Thank you. _________________________________________________________________ 5: DISCLAIMER I VINCENT HIMPE, THE AUTHOR OF THIS FAQ, CANNOT AND WILL NOT BE HELD RESPONSIBLE FOR ANY DAMAGE, INJURY OR WHATEVER TO ANYONE OR ANYTHING RESULTING FROM THE USE OF WHAT IS DESCRIBED IN THIS FAQ. SOME OF THE THINGS EXPLAINED IN THIS FAQ HOLD A POTENTIAL DANGER OF ELECTROCUTION OR POISONING OR INJURY WHEN BUILDING OR USING THEM. WHEN BUILDING ANY OF THE THINGS DESCRIBED IN THIS FAQ YOU, THE READER OF THIS FAQ, AND ONLY YOU ARE THE SOLE PERSON RESPONSIBLE FOR WHAT MIGHT HAPPEN. WHEN YOU BUILD ANYTHING FROM THIS FAQ AND SELL IT, RENT IT OR GIVE IT TO THIRD PARTY PERSONS, OR EVEN ONLY LET THEM USE IT THEN YOU WILL SHOW ANYONE THIS NOTICE BEFORE YOU SELL IT, RENT IT, GIVE IT AWAY OR LET ANYONE USE IT. AGAIN: I CANNOT AND WILL NOT BE HELD RESPONSIBLE FOR ANY DAMAGE OR INJURY RESULTING FROM THE BUILDING OR USE OF ANYTHING DESCRIBED IN THIS FAQ. FURTHERMORE, I CANNOT BE HELD RESPONSIBLE FOR FINANCIAL LOSS OR DAMAGE OF ANY KIND TO ANYONE OR ANYTHING RESULTING FROM THE TECHNIQUES OR INFORMATION CONTAINED IN THIS FAQ. IN READING ANY TEXT BELOW THIS LINE YOU ACCEPT THESE TERMS. THIS ALSO APPLIES IF YOU STARTED READING BELOW THIS DISCLAIMER OR EVEN IF YOU HAVEN'T READ THIS DISCLAIMER AT ALL. WHEN USING THE CHEMICALS DESCRIBED IN THIS FAQ YOU MUST TAKE ALL NECESSARY PRECAUTIONS TO PROTECT YOURSELF OR ANYONE ELSE NEARBY FROM INJURY OR DAMAGE RESULTING FROM THE USE OF THESE PRODUCTS. IN DISPOSING OF USED CHEMICALS YOU MUST FOLLOW LOCAL REGULATIONS. PLEASE TAKE CARE OF MOTHER EARTH ALSO. THANK YOU (filipg: yes, that was meant to be all uppercase). _________________________________________________________________ 6: DESIGNING A BOARD Before you can start making a Printed circuit board you need a layout. If you already have on (from a magazine or so) you can skip this section. There are numerous ways to make a layout. I will not discuss routing here because this is an intuitive matter. It takes some experience to be able create clean layouts. My advice is: just do it. What will be discussed here are the techniques and materials involved in the drawing process. Not the drawing methods. _________________________________________________________________ 6.1: Drawing directly onto the PCB material When the PCB layout is very easy and you only need 1 or 2 pieces you can draw immediately onto the material. You must however use an etch-resistant ink. There are a number of companies that make this kind of drawing pens. In europe there exists a company called Decon-Dalo. This company makes a special pen with a pumping mechanism. The ink in this pen is specially designed for etching PCB's. Its resistance against the etchant is very high. In the USA the best is to go to your local Radio-Shack. They have it in their catalogue. Anyhow the best to acquire a drawing pen of this type is to go to your local electronics shop and buy one there. Furthermore you need some Clean PCB material. There are a number of different materials available (see further on). Make sure the Copper is clean before you start drawing on it. To clean it you can use regular Scotch-Brite from 3M. Don't use steel wool. It will make the copper oxidize and generally it leaves some grease on the copper. To make it really perfect you can wipe it off with a cloth wetted with IPA. (IsoPropyl Alcohol) Now you can draw the tracks on the Copper surface. When finished make sure it gets the neccesary time to dry thoroughly. When drawing prevent, as much as possible, from touching the copper with your bare hands. The grease on our skin will oxidize the copper and might make the exposed areas more resistant against etching. There are a number of companies that sell so called Dry-Transfers. These are sheets of plastic that have all sorts of cymbols on them. You can transfer them by simply rubbing on the paper. Put the sheet with symbols on the Copper. Rub with a pencil on the symbol you want to transfer. It will stick to the copper. Sheets exist with alls sizes of Pads, Tracks, symbols. You can find adresses at the end of this FAQ. Now it's ready to etch. _________________________________________________________________ 6.2: Using Transfer Films There exists also something called Transfer film. This is a sheet of specially coated plastic film. If you have a layout then you can copy or LASER-print it onto this material. Other printing methods will not work! Now you have to put the film, with the printed side, onto the bare copper. Put a regular household iron on the film. The temperature setting should be around 200F. What happens is that the printout will be transferred onto the PCB. Yust let it cool down and then remove the plastic film. If you're successfull you should have a neat PCB ready to etch. The film can only be used once since the process depends on the special coating of the film. There are a number of these films around. You can find more information at the end of this FAQ. _________________________________________________________________ 6.3: Using PhotoSensitive PCB material First we need a layout on a transparent material. With transparent I mean: a material that let's light pass trough it. Paper is also transparent in this case. This is explained in the next section. _________________________________________________________________ 7: MAKING A PCB LAYOUT FOR PHOTOGRAPHIC PCB PRODUCTION _________________________________________________________________ 7.1: Using Pen and paper We can be very brief here. Only two advices : Use a good, clean pen with BLACK ink. Make sure that the ink is as black as possible. There are some differences between the ink types. Use good quality drafting paper for Ink-drawings. Best is to go to a shop that is specialised in drawing materials. Usually they will be able to assist you in the selection of the ink and paper. You can also make your drawings on tracing paper. This is a semi-transparant type of paper. This is good solution if you make your PCB by photographic means. There also exist transfer symbols that make life easier. Check out you electronics store. _________________________________________________________________ 7.2: Using a computer A number of solutions exist here. There are numerous programs around to make PCB's. Amongst these are some really well known like OrCad, Protel, Ultiboard, Tango, Layo, Eagle, Pads, etc. Discussing these programs would take us too far. You can contact these companies for further information. (adresses can be found further on in this FAQ) If you are a hobbyist then you can often get limited version of these programs for free. These Demo programs are often fully functional but limited in size and number of layers. However they are usefull for hobbyist like designs. There are a number of excellent programs around that can be obtained for free from various FTP sites. One of these is EasyTRAX for DOS. This is a real working, commercial program that is available as freeware. The company that makes it Protel Pty from Australia, has released it as freeware. It is a fully functional, non-restricted PCB editor. It is the same as their 'big' system called Autotrax. The only difference is that in Easytrax the Auto router has been taken out. That means that you cannot make the computer route the connections for you. It can be found on the Simtel FTP site. (filipg: Added list of hotlinks to mirrors for EasyTrax. Please e-mail errors to me at filipg@paranoia.com. Thanks.) The file you want is called easytrax.zip and is 490KB. Please be nice and pick the site closest to you! * USA Site: oak.oakland.edu directory /SimTel/msdos/cad file easytrax.zip OR Site: archive.orst.edu directory /pub/mirrors/simtel/msdos/cad/ file easytrax.zip OR Site: wuarchive.wustl.edu directory /systems/ibmpc/simtel/msdos/cad file easytrax.zip * Australia Site: archie.au directory /micros/pc/SimTel/msdos/cad file easytrax.zip * France Site: ftp.ibp.fr directory /pub/pc/SimTel/msdos/cad file easytrax.zip * Germany Site: ftp.uni-paderborn.de directory /SimTel/msdos/cad file easytrax.zip * Hong Kong Site: ftp.cs.cuhk.hk directory /simtel/msdos/cad file easytrax.zip * Netherlands Site: ftp.nic.surfnet.nl directory /mirror-archive/software/simtel-msdos/cad file easytrax.zip * South Africa Site: ftp.sun.ac.za directory /pub/simtel/msdos/cad file easytrax.zip * Sweden Site: ftp.sunet.se directory /pub/pc/mirror/SimTel/msdos/cad file easytrax.zip * Switzerland Site: ftp.switch.ch directory /mirror/simtel/msdos/cad file easytrax.zip * Thailand Site: ftp.nectec.or.th directory /pub/mirrors/SimTel/msdos/cad file easytrax.zip * United Kingdom Site: micros.hensa.ac.uk directory /mirrors/simtel/msdos/cad file easytrax.zip OR Site: src.doc.ic.ac.uk directory /pub/packages/simtel-msdos/cad file easytrax.zip So far for the software. Let's see what more is needed. In the end what count's is that you get your design on paper or drafting film.A number of options exist here. _________________________________________________________________ 7.2.1: Printing the layout The best results are obtained with an Ink-Jet printer. The drawings created by these printers are better than those created by a laser printer. This may sound weird but it isn't. Let me explain. Since a Laser printer uses a 'toner' (the black powder used to print) you will get difficulties with big planes. The main problem encountered with big planes is that the center of the plane is lighter than the borders. It is very well possible that the resulting print-out might not be usable. Since an ink-jet printer is using liquid ink this is not the case. The printout will be equally black on all places. If you don't have either an ink-jet or laser then a 24 needle printer can be used too. Use a fresh printer lint(ribbon) when creating you art-work. This will insure a good result too. A 9 pin printer will not give good results. One important thing when making printouts is the quality of the paper. In Ink-jet printers you should use glossy paper. The ink stays on top of the paper and does not penetrate into it. This prevents the ink from smearing out. Of course, the drying process will take some more time. For the other printers this is of no real importance. You can use tracing paper in all of these printers.This will save you the step of making a transparent layout further on. In a Laser printer you can even use so called 'overhead transparencies'. These are the kind of films they use to put on projectors when giving presentations for public. In an inkjet printer you can use these too but you have to make sure that you have the right type. You must use transparencies designed for inkjet printers. One good source of these is Hewlett-Packard. _________________________________________________________________ 7.2.2: Plotting the layout Another option (for the more fortunate) is using a real plotter. Since these machines are using liquid ink the results are bound to be good. Furthermore the line-drawing features are much better then a printer. you can use different pens for each linewidth. The main drawback is that plots are costly. Not only the plotter itself is expensive but the cost involved in making a plot is substantial too. The pens and the special paper cost quite some money. On a plotter you can also use tracing paper or transparencies. When using these you might have to buy special pens. Check this out with the supplier of your plotting equipment. _________________________________________________________________ 7.2.2.1: Photoplot This is a technique used in industrial PCB production. A regular flat-bed plotter is fitted with an Uv light source. The pen is replaced by a fiber optic cable. The mechanism to make the pen move up and down is replaced by an electronic shutter. Typically this is an LCD shutter. For the computer this looks like a regulare plotter. Although very often these plotters ues a special languages like GERBER or GDS II. The plot is done in a darkroom on a photograpical film. When the plot is completed they develop it just like a regular photo. This is the only method to make ultra thin lines. A french company is producing an add-on kit to convert a regular plotter into a photoplotter. _________________________________________________________________ 8: TRANSFERRING THE LAYOUT ONTO THE PCB _________________________________________________________________ 8.1: Making the Film required to transfer onto the PCB Okay. By now you should have your layout ready. You have to create a layout on a transparent material now. When you have drawn, printed or plotted your layout on tracing-paper then you have no problem.On the other hand when you have it on plain paper you will have to make a transparent layout first. _________________________________________________________________ 8.1.1: Using a COPIER and transparencies When the design is not critical you can use a plain-paper copier. Make sure the copier is not enlarging your design. Most copiers have some optical error that somehow enlarges a little bit. This can give trouble with something as small as a 28 pin chip. You can make your copy on tracing paper or on transparencies. Make sure that you have transparencies designed for copiers. They will have to stand the heat used inside the copier to make the toner stick to the carrier (toner = the black powder). Another way make your transparent is using a photographic method. There are some solutions here. _________________________________________________________________ 8.1.2: Using Pelifilm from SENO A company called SENO commercializes a special film for this purpose. You can start off with you drawing on paper and you will end up with a film ready to transfer onto the PCB. You must process this material in dim light however. It is quite sensible to ambient light although a darkroom is not necessary. You need : A Ligh bulb of approx 60 watts. For bigger PCB's VF lamps are better.(VF = Facuum fluorescent also called TL Lamps ) 2 pieces of PlexiGlass plate. Your drawing on paper A sheet of the SENO film. procedure: Put you drawing on the glass plate.Beneath the glass plate you put the light source.Put the film on your drawing. put the next glass plate on the film. Note: you can use something else for the top plate too. It is just used to push the film onto the drawing. ============================= Top plate. -------------- Film ------------ Drawing on paper ============================= Glass Plate BulB The actual time needed to transfer the drawing onto the film is depending upon the type of lamp and the light intensity used. You might have to experiment a bit here. Normally with a 60 watt lamp 5 to 10 seconds is normal. Again: experiment with litlle pieces of the film first. For larger drawings you should use a frosted glass plate.That way the light is beeing diffused.This will give you better results.Even better is a sheet of white plexiglass. This is a white sheet of plastic that is transparent for light. _________________________________________________________________ 8.1.3: Using Litex Photofilm A more professional way is using real photofilm. This kind of film is produced,amongst others, by AGFA. The type is LITEX no 0911p.It is the kind of film used by newspaper publishers to make their leadplates for printing newspapers. For this film a darkroom is necessary. It must be processed in RED light because it is extremely sensible to other light.You can check your local photoshop.They should be capable of giving you advice on what you need and how to do it. The cost of getting started is reasonable. You will need to purchase a box of films (sold per 100 pieces) and some chemical products. It requires some experience too before you get working results. But the result is excellent and the cost per film is very low. (below half a dollar for standard letter size paper.) And the result is excellent.Black is really black on this kind of film. Basically what you need is: * Litex Film. * Litex developer (2 different liquids) * Regular Fixer for B/W film. * 3 trays (plastic) * 2 plastic tweezers (to grab the film) * 3 plastic bottles (black plastic!) * A pair of plastic gloves. * A light source. * A darkroom Let's start at the bottom. * A Darkroom. That's easy. Any room that can be put in complete darkness will do. Replace the normal light bulb with a red light bulb. I use the kind used for outdoor christmas-tree lights. The lamp should be no ore than 20 watts. I use a 15 watt lamp. * A light source. This can be the same source you will use to expose your PCB's. Typical a set of Ultraviolet lamps will do.You can also use regular fluorescent lamps. But since you will need ultraviolet lamps for exposing the PCB ... . See further on in this Faq for more information. * Tweezers, bottles and trays. You can buy this in a photoshop. The trays are used to contain the chemicals for developing the film material. The bottles are used to hold the chemical products when not used.The tweezers are used to grab the film and take it out of the liquids. * Plastic gloves. These can be regular household gloves.Theire purpose is to protect you from the chemicals involved. Although most of the chemicals are only rather harmless please do wear them. The effects of these chemical products are not always known. * Fixer for black and White film. You will have to go to a photoshop to obtain this. An example of the prouct is AGEFIX FIXER from AGFA. You can buy this product in bottles of 1/2 Liter.Pricing is somewhere around 5 dollars for a bottle.This is a concentrated product.You will have to dilute it before use. The best dilution is 1 to 4 so: 1 part of Fixer for 4 parts of Water.This will give you the right solution for the Litex Film. * Developer for Litex Film. Again here you will have to go to a photoshop.This is a special developer for this litex film.It comes either as a powder or as a liquid solution.It is sold as two different products. In either case you will have a part A and a part B. You will have to follow instructions on the package to make the final product.For the liquid product for instance : 5 parts of product A 5 parts of product B 20 parts of water This will give you a clear solution if it's okay. It may take up to 1 minute before it comes completely clear. You can hold this solution for about 1 to 3 months depending on the usage.Eventually after 3 months it will go bad. Even if you don't use it.That is the reason why it is delivered as two different products. When separated they can be preserved for a long time. (Mine are currently over 2 years old). Store them in a airtight bottles in a dark place.Best is to buy special photobottles. These are black plastic bottles that you can squeeze. They look like a harmonica.Also make sure that the product is kept cool.Around 20 degrees Celcius Maximum. This product is inexpensive too.The products you need to make about 5 liters of developer will cost something like 12 Dollar. * The LITEX Film. This too will have to be bought in a photoshop.They might have to order this for you.Don't expect them to carry this as a standard product. The same goes for the developer and Fixer. The type is LITEX 0911p from AGFA. You can buy these in ready cut sheets. There are 3 or 4 different sizes which are sold in boxes of 100 films. A box of oversized Letter-paper films will cost something like 60 Dolar. That's about half a dollar per sheet. You must store these films in a dry,clean,fresh and preferrably dark place.Temperature must not rize above 25 degrees CELCIUS. When you respect this you can hold these films a very long time. Up to 5 years is perfectly possible. Okay. Now how is it done ?. 1. Make sure you have made the solutions of the products you need.Also get everything else necessary. Gloves, the artwork , light unit , a pair of scissors (to cut film to size) , the box of films ,the trays, the tweezers etc ,maybe a set of safety goggles to protect your eyes from the chemicals. 2. Switch to DARKROOM mode. When in the red light take some time so your eyes can get used to their new environment. After a minute or so you will be amazed of what you are capable of seeing. Fill one tray with about 1 liter of mixed developer. Another with about 1 liter of Fixer. The third tray gets filled with fresh water. 3. The Film Open up the box of films and take out one. Cut it to the right size and store the rest back into the box. CLOSE THE BOX AGAIN!. This will prevent from exposing all of the films by accident.You will see that the films are packaged in a black plastic bag inside of the box. You will also remark thet the inside of the box has been made completely black. This is done to protect the films as much as possible from ambient light. When cutting sheets of films you must cut 2 pieces. The film is of the reversing kind. You will first make a negative before making a positive again. 4. Exposing the film Put your drawing with the inked side up onto the glass plate of the exposure unit.Put the film on top of the drawing. If you look at a sheet of film you will remark that it has a darker and a lighter side. Put it with the lighter side on the inked side of the drawing.The lighter side of the film is actually the sensible layer. Close the lid of the exposure unit and switch on and off. The exposure is only a flash of light. The actual time needed for the exposure is half a second. It is sufficient that the UV lamps just flashed once or twice. 5. Developing the film. Put the exposed film into the tray with the developer. Put it in with the light side UP.Be carefull not to scratch the light side of the film.It is rather fragile when wet. Depending on the age of the developer and the exposure time the film will have to stay in there for 0.5 to 2 minutes. You will see that the exposed parts will turn black. The film is ready when it is equally black.Also look at the white areas. When they start to go brown the film has been in the developer too long or you have exposed it too long. The above part may take some experience. Don't get worried when the first 10 trials fail.Once you get it right you will have very rare failures. When it's okay take it out of the developer, using tweezers, or if you are wearing gloves you can do it by hand. Put the film immediately into the FIXER without rinsing!. It will have to remain in the fixer for about 2 minutes. You will see that the white area's will become transparent. There is no risk of ''over-fixing'' the film.Of course if you leave it in there for over 30 minutes it will go bad. But you can safely leave it in the fixer for up to 5 minutes When it's fixed put the film into the water and leave it in there for some time (2 to 3 minutes). Then you can take it out and rinse it under running water. Be carefull not to scratch it. It is very fragile when it comes out of the processing.Once it's dried up it's very tough and can stand strong abuse. 6. Making a positive image again. This is the same as step 5 but instead of starting from the paper drawing ,start from the film you just made. What i generally do is take the film out of the tray with water , wipe it of a little and start from this wet film. What will happen is that a small layer of water will be between the the two films. This will give some optical effect and insure a good sharp result. The best way to wipe of the the film is to pull it between 2 fingers. Be carefull not to cut yourself though.The edge of the film is rather sharp.There exist also speciall rollers to do this.Check with your photoshop. 7. (last step) Clean up. Put all liquids back in their respective bottles. and wrap up. When it's okay you should have a razor sharp image of your drawing by now. Note: The products are sensible to light too.Therefore you have to store them in black bottles.Put the liquids only into the trays when you are already in your darkroom. I have been making films with this method for the last 5 years now and so far only very few have failed.(i'm making 3 to 5 film's a week!). I can make a ready-to-run film from paper in less then 5 minutes. It is a very good way to make your PCB layout , but as i said : it takes some experience and some patience to get started. I screwed up a number of times before i got the results i wanted. I have tested the possibilities of the Film.It is possible to make tracks of 5 mils and less!. (Starting from a Plotted artwork on a raster plotter from Versatec.) If you have layouts with tracks smaller than 15 mils then you can follow these guidelines : Print or plot the MIRRORED view. This is the view you would get if you would look trough the PCB. In the first step this will happen : =============================== Film ------------------------------- sensible side --- -- ---- -- ink =============================== Paper ( BULB ) There will be no gap between the ink or toner and the sensible side of the film. (otherways the film material itself would be in between) This will prevent any parallax faults to occur. After development of this first film do the same again. =============================== Film ------------------------------- sensible side -- --- ----- -------- -- Coating =============================== Film Now develop again. --- -- ---- -- Coating =============================== Film If you now make the PC board from this film you will have no problems with the small tracks: =============================== PCB ------------------------------- Photo Lacquer --- -- ---- -- Coating =============================== Film After devlopment : =============================== PCB --- -- ---- -- Lacquer This is exactly what you wanted. Without parallax faults. _________________________________________________________________ 8.2: The actual transferring Okay. Up till now we have been busy transferring our drawing onto a transparent or semi-transparent material. So now we are ready to transfer our image onto the Copper layer of the PCB. For starters we need photosensitive PCB material. There are 2 possibilities here : Either you buy ready made material or you make it yourself. The best is to buy ready made material.This is a PC board of which the copper layer is covered with photosensitive lacquer.The lacquer is covered with a black paper or plastic which can easily be removed. _________________________________________________________________ 8.2.1: How to make photosensitive PCb material yourself This is a rather messy job and takes lot's of time.You will not save any money by making the sensible PCB's yourself.On the contrary. You can buy spray cans with this type of lacquer.You must clean the Copper layer of the PCB and wipe it off with IPA. When it is dried up you can spray the photo lacquer onto the copper area.Make sure it gets even spread onto the whole copper area. Now you must leave it to dry , in a dark place for 24 hours.If you are lucky it will work. _________________________________________________________________ 8.2.2: Buy ready made material There are two different types available. Positive and negative. 95 percent of the material beeing sold is positive material.Which is okay for what we need. The negative material is used in industrial PCB production.The only advantage is that it easier to make Multilayer PCB's with.But since this is virtually impossible to do at home : forget about it. You can recognize the material by looking at the lacquer. Peel of a small corner of the cover sheet and look at the photosensitive layer If it has a lighblue metal shiny look then it is negative material. All other colors are positive material.( this is to my knowledge ). Furthermore we need a developer for this material.Generally the shop that sells the PCB material will sell also this material. There are a number of different products on the market but basically they all contain SodiumHydroxid. SodiumHydroxid is the substance used to de-clog your drain.If the drain of the kitchen sink is clogged then you can buy bottles of brown liquid to throw in there and de-clog the drain. Well the product in those bottles is most of the time SodiumHydroxid. I have tested it and it actually works to develop PCB's with! Of course you have to dilute it . It is far to concentrated to use directly. Of course the best is to buy the product in an electronics shop. You can buy ready made doses of product to make 1 liter of product. When handling the product please wear gloves and safety goggles. It will probably not cause any burns but it is not very healthy to put you bare hands into the product or solution. Should you come in contact with it rinse with water. If you get it into your eyes then rinse with plenty of water and call a physician. _________________________________________________________________ 8.3: Exposing the material and developing Right. So by now we have our Film, the PCB and developer. What else do we need: 2 plastic trays. A pair of rubber gloves and an exposure unit. This has to be an Ultraviolet light source designed to expose PCB material. The wavelength is rather important. Further on in this FAQ is described how you can make your own. If you don't want to spend money you can use direct sunlight too! Using direct sunlight. Put the film on the sensitive side of the PCB (of course you first have to remove the cover paper). Cover it with a piece of Plexiglass or other clear plastic. Don't use glass here because it stops too much of the ultraviolet component in the sunlight. Exposure time: somewhere around 10 to 15 minutes. Using the exposure unit: The exposure time (with the described exposure unit or with a ready made unit) is approx 2 to 3 minutes. Some experimenting might be necessary here although it is not very critical. Put the drawing onto the exposure unit. Put the PCB with the sensible area onto the drawing, close the lid and start the exposure. Two important notes here: First Protect yourself! Ultraviolet light is dangerous. Never look into the light source when it is switched on. Always close the lid of the exposure unit when the lamps are turned on. Second Do this in dimmed light. Not in clear daylight.Although the PCB material is only sensible to UV light there is a risk of destroying it with direct sunlight or strong daylight. Sunlight contain UV also and strong daylight will gradually reduce the sharpness of the image. You can process PCB's in normal ambient light if you use the PCB material directly. Once the cover paper has been taken away from the photosensitive layer you must use it. Don't leave it on your table for 2 minutes. It will go bad if you do. I generally do it in ambient light. I put my transparent on the exposure unit . Take the paper away from the PCB . Put the PCB on the drawing and close the lid. After the exposure i take out the PCB and put it directly into the developer.Works all the time. Developing: After exposing the PCB you must develop it. Therefore you have to put it into the developer.The actual developing process takes some 30 seconds. You have to move the PCB in the liquid. After some seconds you will be able to see the image on the PCB. After sim half a minute you should have areas with blank copper and areas that are covered with the photoresist.The photoresist will turn brwon to black so you can see it very clearly. Now you can take out he PCB and rinse with water. That's it. Now you have a PCB that is ready to be etched. _________________________________________________________________ 9: ETCHING THE PCB We can be brief about the procedure here. Just put it into the etchant and wait until all bare copper has been removed. Then take it out and rinse with water. However there are lots of chemicals you can use to etch a PCB. In general when using these chemicals please wear safety goggles and gloves Best is also to wear an acid-resitant apron. Most of these products are capable of eating holes in your clothes or producing stains that are very hard to remove. There are 2 basic products used to etch PCB's with. * Ferrous Tri Chloride Fe3Cl Brown solution. You can buy this under the form of a ready made liquid or as powder or as a granulate. This is probably the most used etchant by hobbists, although it is used in industry also. Advantages Cheap, easy to obtain Drawbacks Make stains which are very hard to remove. Is a dirty product. Not so fast, therefore, it is not useable for fine lines. * Persulfate from Natrium (sodium) or Ammonium. Na2S2O8 of (NH4)2S2O8 The second product is used in professional PCB production. It is sold as a white powder or granulate. Ammonium Persulfate works slightly faster than Natrium Persulfate. Advantage Clean, transparent solution. Turns dark blue when used-up Drawbacks Not as cheap as Fe3Cl, needs heating to 35 degrees Celcius! There are people who mix Fe3Cl with other chemical products to improve the etch rate. But in general, this results in the release of toxic gases. There are also some other products that can be used. Since the risk involved with these other products is bigger i will not cover them here. The products described above are, although still dangerous, safer than others. I use Sodium or Ammonium persulfate. Mostly Sodium Persulfate. Ammonium persulfate is used to etch large quantities of PCB's at the same time. The problem with the product is that it tends to re-crystallize if you let it cool down. Once you make a solution you must use it. If it cools down it goes bad. Sodium Persulfate solution can be stored ready made for a long time. That's about it. After etching the PCB remember to rinse it thoroughly with water. Now you have a PCB ready to drill holes in and put components on. Some photolayers can be left on. You can easily solder the PCB. The photolayer will be removed locally by the heat of the soldering iron. However you can still process it further. For further processing, it is necessary that you do not drill the holes yet. Drilling the holes should be the last you do before putting components on the PCB. _________________________________________________________________ 10: PLATING WITH SOLDER LACQUER, GOLD, SILVER, OR TIN You can cover your PCB with a real solder lacquer of flux. This will prevent the copper from oxidating (patina) and turning green. It has the advantage that it easier to solder than the photolacquer. If you want to give your PCB's a professional look you can cover them with tin. If you need pcb's for hostile environments you can cover them with silver or gold. Before applying all these products we must strip off the remaining photo- layer. The best is to use acetone to do this. This is available in any do-it-yourself shop. Submerse the PCB in the Acetone and leave it in there for some 15 seconds. This should dissolve all of the photolayer. You can use the acetone many times. When you take it out wipe it dry with a fresh cloth or piece of kitchen paper. Important for these actions is that you did not drill the holes yet! _________________________________________________________________ 10.1: Applying solder lacquer You can buy this lacquer in spray-cans in good electronics shops. Just spray a thin film of this product onto the pcb. Now it has to dry out completely. This can take some time (1 to 2 hours). _________________________________________________________________ 10.2: Applying Tin,silver or gold In good electronics shops you can buy products to do this. They are called Chemical Plating Agents. Basically these are liquids where the metal is dissolved in. They all contain some sort of acid. So handle them with care. Wear rubber gloves and safety goggles when using them. The plating process is very fast but it requires some precautions. The copper must be very clean. Furthermore you must prevent, as much as possible, that strange products get into the liquid. The liquid is very sensible to other chemicals and even to water. It will go bad. The best procedure is as follows: 1. Strip the photolacquer with acetone. 2. Wipe dry with fresh cloth or kitchen paper. 3. Submerse the PCB in IPA. This is to remove all grease. 4. Again wipe dry with fresh cloth or kitchen paper. 5. Rinse in fresh water. This will make sure the 'wettability' of the PCB. is okay. You can rub the copper with some cloth while under water. If you put water on a pcb that comes out of the IPA you will see that it will not stick to the copper. It will run off immediately. The PCB will look 'greasy'. For the plating process this is not good. 6. Now wipe dry again with clean cloth or kitchen paper. 7. Put the PCB in the plating solution and leave it in there for a couple of minutes (1 or 2 should be sufficient) 8. Take it out an rinse with water. 9. Wipe it dry immediately! This is necessary since it will oxidize very rapidly if you don't do this. 10. Now you still can apply a solder lacquer if you'd like. 11. That's it. By now you should have a printed circuit board ready to drill. _________________________________________________________________ 10.3: Silkscreening the PCB If you look at commercial PCB's like found in a TV set or Radio then you will remark that a component layout is printed on the PCB. You can do this at home too. The process used in the PCb industry is rather difficult to reproduce at home. They use silkscreens and Paint. But you can use the iron-on type of films. The procedure has been described in the section about making PCB's by hand. _________________________________________________________________ 11: DOUBLESIDED PCB'S When basically the same processes are involved as in single sided PCB production there is a little more care to be taken. Since you cannot look trough the PCB when positioning the films the positioning of the film's can give problems. A good way to circumvent this problem is as follows. Make two strips of PCB about half an inch wide and 5 inches long. The size does not matter actually, it's the thickness that counts. Now Put the 2 films on top of each other and position them correctly. Cut them to the same size now using a paper-knife. You need to leave a border of at least 1 inch around the drawing! Also make sure thy don't shift! Now lift the top film and put the 2 pieces of PCB material between the two films. ------------------------------------------- Film === === PCB ------------------------------------------- Film Align the films and tape them to the PCB material. This way you get an arrangement where you can slip the PCB material between. The alignment will be ok. If you would not use the 2 strips of PCB material the risk exists that the images are shifting and the PCB becomes unusable. Now you can expose, develop, and etch as any normal board. _________________________________________________________________ 11.1: Trough hole connections The big question: How do you connect the 2 sides of the PCB together. There are a number of ways to do this. Use pieces of wire to put in the holes.A neat way is to use a special component for this. This is called a Track Pin. -+- <-- It looks like this | | It is sold as strips which you can easily break apart. The above techniques have the disadvantage that you cannot put a component in the hole anymore. When making the PCB layout you should try to make VIA's (connections from one side to another) at the component pins directly. That way if you solder the lead at both side then you have an instant VIA. If you use IC sockets with machined contacts then you can even apply this technique for IC pins. How it is done in industry: Note that this is a process that you cannot reproduce at home! They take a clean double sided copper board. The copper thickness is only 17 micron! as opposed to 35 micron used for singlesided PCB's and for the kind of material we use. First the holes are beeing drilled by a computer controlled drilling machine. The PCB now goes in a chemical plating agent. This is a special liquid which contains lots of copper in an ionic form. The copper precipitates on the PCB. Both on the copper and on the bare PCB material. This way a copper layer of about 2 to 3 micron is beeing grown onto the PCB material. The PCB is taken out and rinsed. The copper at the edges is removed. Now the PCB is going trough an electro plating process. What happens is that they use a liquid with dissolved copper. They attach the negative side of a power supply to the PC board. Another electrode with the positive wire connected is put in the solution too. Now copper will start growing on all the bare copper. The process is stopped when the overall thickness of the copper layer is around 35 micron. They will not measure this but will use a fixed time for the proces. Because the rate of precipitation is constant they can calculate the actual thickness. So the thickness of the trough hole plating is 35 - 17 = 18 micron. Now a NEGATIVE photolacquer is applied and exposed with the layout. After development the tracks are bare copper. What has to be removed is still covered wth lacquer. No I'm not mistaken here! Read on, it will come clear why. The problem with photolacquer is that it will not penetrate into the small holes to cover them from the etchant. So they use a different technique. The PCB is now plated with TIN or Chrome. Now the photolacquer is stripped off. You end up with a PCB where the tracks are marked with TIN or Chrome. The plating solution is able of penetrating into the holes and covering the inside wall of the whole with TIN or Chrome. To etch the PCB they use heated Ammonium Persulfate. Nice thing about this is that it only etches copper. It does not etch TIN or Chrome. So the coated locations are not beeing etched. When the PCB is etched they clean it up and have a trough plated and tinned PCB. The chrome is used if they make multi-layers. They stack the boards on top of each other and make the chrome fuse together. Since the melting point of chrome is higher than the one of TIN this will make shure that the board does not fall apart if you solder it. Of course they start with thinner material to make multilayers. The copper thickness is also much less. How you can do it at home: I have been looking for information about this question for years. Nobody seems to have a solution for this. So I started to experiment on my own together with my cousin who is in the running for a masters degree in chemistry. We hope to have results by August. I'm sorry i can't answer this question right now. _________________________________________________________________ 12: DO-IT-YOURSELF SECTION _________________________________________________________________ 12.1: The exposure unit You can buy these ready made in large electronics shops. Or you could one make yourself. To make one yourself : Note : I cannot and will not be held responsible for injury, damage or whatever, either to you, third party or whatever, resulting from the building or using this unit. Just to make this clear. If you decide to build and/or use this unit you are the only one responsible for whatever might happen. Make an enclosure (in wood) of which the top cover is attached by hinges. So you can open it. You can ask a carpenter to help you here. The top cover should be made so that you can put a piece of foam rubber in there. You should have to apply a light pressure to be able to close it. This is to insure that the PCB and/or film makes good contact with each other when they are between the foam rubber ad the glass plate. In the back of the exposure chamber you should drill some holes so that fresh air can get into the chamber. Normally VF lamps do not produce much heat. But for fire safety just do it. Cross view: +-------------------------------------------------------+ |==================== Foam rubber ======================| | ======== Glass plate (frosted glass) ================ |---------+ | | | ||| ||| Starter | | | Coils | | | Timer | | | | | | | | "================= U V light source ================" | | | "===================================================" | | | " " | | +-------------------------------------------------------+---------+ Make the enclosure so that you can fit 4 Ultraviolet lamps inside. top view: (top cover opened) ========================================================= | Top cover | ========================================================= ====== ====== ==================================================================| | | | | +---------------------------------------------------+ | = On | | | | | = Off | | | "================= Lamp 1 ======================" | | | | | "-----------------------------------------------" | | 3 4 5 | | | | | \ | / | | | "================= Lamp 2 ======================" | | | | | "-----------------------------------------------" | | \ | | | | | 2- O -6 | | | | | | | | "================= Lamp 3 ======================" | | / \ | | | "-----------------------------------------------" | | 1 7 | | | | | | | | "================= Lamp 4 ======================" | | Timer | | | "-----------------------------------------------" | | | | | | | | | +---------------------------------------------------+ | | | | | ==================================================================| Make the exposure chamber so that the lamps are spaced about 2 inches apart and 1 inch from the walls. The best is to go to an electronics shop and buy a PCB exposure kit there. Usually they can sell you a small kit containing 2 lamps the starter, the coil and the necessary sockets. This kit will also have an electrical wiring diagram. I Cannot give the actual sizes of the box because i don't know what size of lamps you will use. You will have to make your box depending on the size of lamps you use. However, the glass plate should be approx 4 inches away from the Lamps. Next to the exposure chamber you have some space where you can put the necessary coils and starters to ignite the lamps. If you put an aluminum top plate on there you can put in a timer circuit also. You can buy these mechanical timers in an electronics shop. Again make this large enough so you can fit the coils and all other parts in there. The top glass plate is made from frosted or clear glass. Make sure you have good quality glass here. It should be about = 1/5 inch thick. Best is to go to a do-it-youself store or glass shop and ask them to cut a piece of glass with the appropriate dimentions for you. Don't try this yourself. It is very dangerous. You will only end up hurting ourself. Ask them also to take away the sharp edges. Cover the bottom of the exposure chamber (on the inside of course) with aluminum foil. Do this only below the glass parts of the lamp. Not beneatch the sockets. This is for the electrical safety. Keep the edges of the aluminum foil about 1 inch away from the lamp sockets. The Aluminum foil is used as a reflector for the light that the lamps produce. This way you will create a light that is equally strong on all places of the glass plate. /------- Aluminum foil +--------------------+ | | "==========================" "--------------------------" | | "==========================" "--------------------------" | | "==========================" "--------------------------" | | "==========================" "--------------------------" | | | +--------------------+ | / / / / / Sockets -------------------- When wiring the whole system use good quality electrical power wire and respect all electrical cabling rules. Again: I cannot and will not be held responsible for ANY damage to ANYone or ANYthing resulting from the building and/or use of this unit. That's about it. When you put some time and work into it you will end up with a unit that will serve you for many years. _________________________________________________________________ 12.2: A Heated etching system You will need the help of somebody who knows to make aquariums. You could check a local pet shop. You will need glass plates. Do not try to cut these yourself - it's way too dangerous. Views: Top "=="======================================================="======" "O " /|\ " - " " " | 2 inches " < > " "O " \|/ " - " "=="======================================================="======" " <-----------------------------------------------------------------> 15 inch Front " /----- Pump--\ ---- " " " /|\ "=== =======" | "=================================================================" | " " " /" " | " " "//" " | " " "//" " | " " "//" " 1 | " " "//" " 0 | " " "//" " | " " Electrical heater with thermostat ---> "//" " i | " " for aquarium purposes "//" " n | " " "//" " c | " " "//" " h | " " "//" " e | " " "/ " " s | " " \==/ " | " " " | " " """"""""""""""""""""""""""""""""""""""""""""""""""""""" " | " \===================== Bubbler unit ==================== " \|/ =================================================================== The bubbler unit is a piece of porous stone. If you pump air through it then it will generate lots of small bubbles. You can get this in pet shops. There you can also find the aquarium pump and heater. The heater must be one with a built in thermostat. Make sure you can go up to 35 degrees CELCIUS. When selecting a heater make sure that the liquid can flow around it. Typical diameter is 1 to 1.5 inch diameter. The power should be 150 to 200 Watts. Typical dimensions of the glass tank are noted on the drawing Note that these are the INSIDE dimentions of the tank. In a pet shop or aquarium shop they will be able to tell you how to make this or they will even make it for you. I had mine made and payed around 10 dollar for it. Make sure you mount the tank on a stable Footage so it can not fall over. The pump, bubbler, some tubing, and the heater will cost something like US$50 together. Make sure you put the pump away from the tank. Keep it at a safe distance. Electricity and water are not best friends. Neither to each other or to you. The aquarium heater is designed for this purpose so it should be safe. It is a Pyrex tube with a heating element and thermostat sealed in. Make sure you immerse it deep enough into the liquid. There is a minimum level marked on it. You must respect this. Otherways overheating can occur. _________________________________________________________________ 13: APPENDIX A: CONTACT ADRESSES Electrolube Photo Resist, developer, Lacquer, Nickel spray, Etchant Electrolube Limited Blakes Road Wargrave Berkshire RG10 8AW U.K. Tel: +44 1734 404031 Fax: + 44 1734 403084 Isel Etchant, plating solution, etching equipment etc... Isel Automation 6419 Eiterfeld 1 Germany Sifco Plating Pen 5708 Schaaf Rd Cleveland, OH 44131 USA Tel: +1 216 524 0099 Fax +1 216 524 6331 That's all I have right now. If you have adresses for AGFA,KODAK,ISEL BUNGARD or whatever. Please mail me. _________________________________________________________________ 14: APPENDIX B: PRODUCTS DESCRIBED IN THIS FAQ Making artwork. * By hand Good quality drawing paper 80 grams per square meter minimum. Do not buy the thick paper. It won't work to make films. The thickness must be like normal paper but the granularity must be very fine. Drafting pens Staedler, Rotring in 0.3 0.5 and 0.7 sizes Transfer symbols Decon-Dalo, Mecanorma, Alfac offer sheets with transfer symbols for PCB production. Things like pads, lines IC sockets, etc. are available. Transfer Films Tec 200 PNP Blue By computer PCB Cad software or general CAD software. Using an inkjet printer Ink jet paper from Hewlett Packard. Ink jet transparencies from Hewlett Packard. Using a plotter Glossy plotter paper from Hewlett Packard or Sihl. Plotter transparencies from Hewlett Packard Drafting pens from Rotring or Staedler depending on the material used. * Making Film By means of Laser printer or photocopier Transparencies from 3M for photocopier or laser printer. Using PeliFILM from Seno PeliFilm from Seno Using photographic film method Agfa-Gevaert Litex 0911p film, Agfa-Gevaert Litex developer, Agfa gevaert Agefix fixer or any regular BW film fixer * Making PCB Photospray Kontakt Chemics, Seno Ready made PCB's Bungard, PRF, CKF, Seno, lots of brands exist. Developer Bungard, Seno, or plain SodiumHydroxide from the chemists. Etchant Fe3Cl = Ferrous Trichloride, Na2S2O8 = Sodium Persulfate, (NH4)2S2O8 = Ammonium Persulfate Solder Flux Kontakt Chemics ,Elektrolube, Seno ,PRF Plating solution Seno, Isel * General products Acetone: local do-it-yourself shop, IPA: (IsoPropylAlcohol) Local Drugstore or chemists, Plastic trays, Bottles, Gloves, Tweezers * Exposure unit, etching unit. Isel _________________________________________________________________ This article translated by <filipg@paranoia.com>. The most recent version is available on the WWW server "http://www.paranoia.com/~filipg/">http://www.paranoia.com/~filipg/