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TUCoPS :: Hardware Hacks :: pcbfaq.txt

Printed Circuit Board FAQ

 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.
     * 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 
     * 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
   Author: Vincent Himpe
   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  *)                          /                            \__/
Fido :

                                 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
                              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  :  (preferred)
                  Fido      : 2:291/1912.8

    By Snail-Mail :   Vincent Himpe
                      A.De Taeyelaan 12
                      8792 Desselgem

   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
   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
   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
   (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
   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
   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
   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.
7.1: 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 Thanks.)
   The file you want is called and is 490KB. Please be nice
   and pick the site closest to you!
     * USA
       Site: directory /SimTel/msdos/cad file
       Site: directory /pub/mirrors/simtel/msdos/cad/
       Site: directory
       /systems/ibmpc/simtel/msdos/cad file
     * Australia
       Site: directory /micros/pc/SimTel/msdos/cad file
     * France
       Site: directory /pub/pc/SimTel/msdos/cad file
     * Germany
       Site: directory /SimTel/msdos/cad file
     * Hong Kong
       Site: directory /simtel/msdos/cad file
     * Netherlands
       Site: directory
       /mirror-archive/software/simtel-msdos/cad file
     * South Africa
       Site: directory /pub/simtel/msdos/cad file
     * Sweden
       Site: directory /pub/pc/mirror/SimTel/msdos/cad file
     * Switzerland
       Site: directory /mirror/simtel/msdos/cad file
     * Thailand
       Site: directory /pub/mirrors/SimTel/msdos/cad
     * United Kingdom
       Site: directory /mirrors/simtel/msdos/cad file
       Site: directory /pub/packages/simtel-msdos/cad
   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
   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.
   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
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


   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
    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
       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
   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
   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:
          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.
          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.
   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
   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
       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.
                Cheap, easy to obtain
                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.
                Clean, transparent solution. Turns dark blue when used-up
                Not as cheap as Fe3Cl, needs heating to 35 degrees
   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.
   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
   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
   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
   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
   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.

      "O "                               /|\                     "  -   "
      "  "                                |  2 inches            " < >  "
      "O "                               \|/                     "  -   "
                                      15 inch


                                                                    " /-----
  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
   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
   Photo Resist, developer, Lacquer, Nickel spray, Etchant
   Electrolube Limited
   Blakes Road
   RG10 8AW
   Tel: +44 1734 404031
   Fax: + 44 1734 403084
   Etchant, plating solution, etching equipment etc...
   Isel Automation
   6419 Eiterfeld 1
   Plating Pen
   5708 Schaaf Rd
   Cleveland, OH 44131
   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.
   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
                Kontakt Chemics, Seno
        Ready made PCB's
                Bungard, PRF, CKF, Seno, lots of brands exist.
                Bungard, Seno, or plain SodiumHydroxide from the
                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.
    This article translated by <>. The most recent
    version is available on the WWW server

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