Fabricating Printed Circuit Boards
by Daniel Wee, 9V1ZV, 7 Dec 1994
Since the beginning of my electronics construction hobby,
I've just about built circuits in every possible way I could think of.
I still remember my early days when I actually had germanium
transistors screwed down on a block of wood. That was before I
acquired my first soldering iron. I then progressed to the well-
known "ugly" construction technique where component leads were
simply soldered together. Other methods I remember include,
breadboards, matrix boards which were quite popular at one time,
wire-wrapping, board-excavation and printed circuit boards. Of all
these, I have found the printed circuit board method to be one of
the most satisfying and aesthetically pleasing, so far. This does not
mean that it was an easy method, in fact, I had avoided circuits
requiring printed circuit boards until I had tried everything else,
and there was a good reason for this. There are also limits to what
you can produce yourself, for example, you will not have the
facility to fabricate through-plated boards or multi-layer boards.
For these, if you ever need them, its best to go to the PCB
manufacturer to have them made for you.
Like many, I had supposed, rightly, that the fabrication of
printed circuit boards was a tedious process, requiring a lot of
basic tools and equipment which I did not possess. As such, the
whole process of fabricating a printed circuit board had remained
pretty much a mystery to me until I entered the field of radio
electronics. I discovered then that the parasitic capacitance and
electrical properties of other construction methods were simply
unsatisfactory for circuits operating in the RF regions. Thus began
my quest for the printed circuit board. The purpose of this article
is to briefly outline the various methods and steps of producing a
usable printed circuit board.
The whole idea of making a printed circuit board is really
a chemical process of removing copper from the circuit board at
the right places, in order to leave behind tracks suitable for
carrying current as required by the circuit in question. Boards can
be bought which come with copper clading one or both surfaces,
used for making single or double sided PCBs respectively. A visual
survey of the board reveals an uninteresting copper surface with no
holes or tracks. The constructor must find some way of removing
the copper in order to obtain a circuit pattern which can be used.
One way to do this is by "excavating" the board with a sharp
cutting tool to remove the copper. This proves to be an extremely
tedious method and can only be used for the simplest circuit
patterns. It is sometimes useful for making quick and dirty
modifications to an existing pattern.
The standard way of creating a pattern, however, is by
means of a method known as "etching". Etching is a chemical
process whereby the unwanted copper is removed by a process of
reduction, a chemical reaction, which "corrodes" away the copper.
This is often achieved by immersing the copper clad board into a
solution of Ferric Chloride or Sodium Persulphate (I think). Upon
contact, a reaction occurs which reduces the copper on the PCB to
copper chloride which comes off the board. Ferric Chloride has
now become a controlled substance in some places because of its
toxic and environmentally unfriendly nature and this makes it
difficult to obtain from the usual sources. Sodium Persulphate is
the substitute for Ferric Chloride but has not arrived at the shops
here yet. Either of the etchtants can be obtained in liquid or in
crystallized form. Nowadays, they are rarely found in liquid form
because of the high rate of oxidation which renders the chemical
useless. More often than not, they come in the form of dehydrated
crystals which we mix with water to produce the etching solution.
This solution is then used to etch the boards.
If you have been asking yourself how the chemical can be
prevented from removing all of the copper, then you have asked an
appropriate question. There are a number of methods by which this
can be done. The whole principle lies is preventing the etching
solution from coming into contact with the copper you wish
preserved on the board. This can be by means of a water-proof
tape on the board, rub-on transfers, marker ink, etch-resist ink,
toner ink, plotter ink or photo-resist. In short, any method that can
protect the board from the chemical solution is usable. Some
methods are easier than others, of course, and the method to use
depends on a number of factors, such as complexity of the pattern
you want to produce, the density of the tracks, the boards available
Once you have, for example, drawn a pattern onto the
clean copper clad board with etch-resist ink, you may immerse the
board into a properly prepared etching solution for the etching
process. This can take from 5 to 30 minutes or more, depending on
the concentration of the etching solution. After that, the board is
removed from the solution, revealing a board where the unmarked
portions of the board has no copper on it, the board material
beneath being now visible, and the marked parts of the board still
having the ink in it. Once the ink is removed either by sanding of
by the use of solvents, the copper will become visible. The one last
remaining step is to drill the holes for component leads in the right
places and the board is ready for use.
That is generally what happens in the process of
fabricating a PCB. Time does not permit me to cover all the
methods that you can use so I will highlight some of the major
steps in the following text.
The Copper Clad Board
Boards suitable for etching can easily be obtained from
parts suppliers and come in a number of varieties. Typically, there
are two major types of board materials that are used for the base
board, fibre-glass (glass-epoxy) and phenolic paper. Fibre-glass
boards tend to be tougher, look better and probably has slightly
lower surface capacitance properties, as well as being the more
expensive of the two. Phenolic paper, on the other hand, is easier
to cut and drill though it tends to crack or fragment as it is more
brittle, and cheaper. Both types can be used for homebrew
construction projects as the mentioned RF properties are quite
insignificant until VHF frequencies and above.
You will find single-sided copper clad boards as well as
double sided ones and you choose the type of board appropriate for
the circuit board you wish to fabricate. Double sided boards are
normally used for RF related circuits because it offers a stable one-
point ground-plane which helps stability and prevents unwanted
oscillations or ground loops. However, producing double-sided
PCBs requires high precision tools and I will only briefly mention
some of the methods for producing simple ground-plane double
sided boards later. This should be sufficient for a start.
You will also come across boards which are "pre-
sensitized" or "photo-sensitized" which are used to produce photo-
resist patterns. These boards are typically much more expensive
than the plain boards because of the photo-resist film that has been
pre-deposited over the surface. Such boards often come in light-
proof wrapping with an additional layer of opaque plastic on the
board surface which will not be removed until ready for exposure.
I will detail this technique below.
Before you get started with the boards however, you will
need to cut the board down to the size you need. Normally boards
are sold in several sizes so you may pick either a large sized board
and cut it up as you need, or select a size that is closely matched
with your required size to minimize the cutting. The boards can be
difficult or easy to cut, depending on the material of the board and
its thickness. Average boards are about 2 mm thick and are quite
tough and difficult to cut. Some boards come in 1 mm thickness
and can be cut using a heavy-duty cutter. This type of board is
usually quite flexible and thus the bending will not damage it. The
thicker types on the other hand, will tolerate little bending before
fracturing or fragmenting. Cutting can be achieved using a hobby
saw with a fine-serrated blade. Thick saw blades are not suitable
for this. Sawing should be done slowly and gradually in order not
to damage the board. Saw perpendicularly to the board, which
should be clamped down to the work-bench firmly using a G-
clamp or a similar device. Alternatively, you can use a heavy-duty
Exacto knife to engrave the border lines of the appropriate size.
When using this method, it is not necessary to completely cut
through the board. Once about 3/4 of the thickness has been cut,
you can usually snap the board along the engraved lines. It is
important to engrave BOTH sides of the board, otherwise you will
not get a clean break. This method is very tedious, time consuming
and tends to destroy your blade, especially when cutting fibre-glass
boards. It can be used when a hobby saw is not available. Try not
to scratch or damage the copper surface when doing this. After the
board has been cut down to size, use a medium sized file to smooth
out the edges for a nice finish.
The Etching Process
The next most important component you require is the
etching solution. As of now, very few shops will sell Ferric
Chloride crystals to unlicensed buyers and Sodium Persulphate is
not publicly available. There is a good reason for this but it means
a lot of inconvenience for the home constructor. There are means
of obtaining the chemicals which will not be detailed here.
Ferric Chloride is most commonly available as
dehydrated crystals and sold in plastic containers. It is very
important to keep these crystals in a dehumidified environment as
it tends to combine with moisture in the atmosphere and turn into
a really messy and staining liquid. Be forewarned that this
substance stains permanently on clothes and even some plastics or
ceramics, is highly corrosive, carcinogenic and toxic. As such it
should be kept out of reach from children and water. For the same
reasons, it should not be discarded into the public drainage system
before diluting it with large amounts of water.
Sodium Persulphate is a white crystal and though it is
environmentally more friendly that Ferric Chloride is, similar
precautions should be taken and care exercised when dealing with
concentrated chemicals of any type. This substance is considerably
safer however. For one, it is endothermic when dissolved in water
and the resultant solution is a clear and non-staining solution. It is
also slower acting than Ferric Chloride and probably needs more
agitation and perhaps a little warming up. A good way to speed up
the reaction may be to dissolve the Sodium Persulphate crystals
in boiling water. Take all necessary precautions to avoid scalding.
The way to prepare the solution is to mix the crystals into
some water, usually 1 part crystals to 5 parts water. This is just a
guide and once you understand the process you can easily produce
higher concentrations to etch boards more quickly. You should also
be aware that the process of hydrating these crystals is a highly
exothermic one so do not be surprised if the water starts to boil. As
such, one should NEVER throw any substantial amount of crystals
into the water. Similarly, one should NEVER add water to crystals,
always crystals to water.
Normally, a plastic tray suitable for immersing the circuit
board is filled with about 2 cm of water. The crystals are then
added to the water BEFORE putting in the board, using a plastic
spatula or any other suitable instrument. The instrument MUST be
dry before applying to the crystals. Never leave the crystals
exposed to atmospheric air for long. As soon as you have taken out
enough crystals, wipe dry the rim of the crystal container and re-
seal it in its air-tight container and store in a dry place out of reach
of children. Do not get the crystals or solution on to your skin or
eyes, and if you do, rinse under cold running water to remove it.
See a doctor immediately in the event of ingestion. As you add the
crystals to the water, the water will change color, to dark brown if
using Ferric Chloride, and you should notice some heat being
produced. Do not be too worried by the heat as it is useful for the
etching process. Do not inhale any fumes produced during the
entire process, these are poisonous and though in very small
amounts, may cause asphyxiation (Chlorine). All this should be
done after you have readied the board for etching. All instruments
coming into contact with the solution should be non-metallic. Stir
the solution until all the crystals have dissolved to produce an
evenly colored solution. Now the solution is ready for use. Try to
use it while it is hot so this step should always be done after your
board is ready.
Put your resist-masked board into the solution slowly so
as not to cause a splash. Remember that the solution is very hot
sometimes. Once the board is completely immersed, regularly
agitate the tray and pay attention to the exposed copper. After
sometime, the exposed surface will appear dull, not necessarily
evenly. The after more agitation you will see patches of circuit
board becoming exposed. Do this until ALL the unwanted exposed
copper surface has been removed and the board material is visible
beneath it. This may not be easy initially as the etching solution
may obscure your view of the board. It is therefore good to have a
deeper tray which allows you to tilt the tray to expose the board.
Normally, surfaces with less exposed copper tend to etch faster
that surfaces with more copper, and once you are more
experienced, you may want to use a stronger concentration for
surfaces which require a lot of etching. The copper corrosion
normally starts from the edge of the board and works its way to the
center. Be sure to keep on agitating the board so that the resultant
copper chloride (a powdery precipitate black in color) will get
swept off the surface. This will speed up the etching process.
While it is important to make sure every part of the board
is sufficiently etched, DO NOT keep the board in the solution
longer than absolutely necessary. This is because extended
exposure will allow the etchtant to get under the resist and affect
the fringe of your tracks, resulting in ugly patterns. Experience will
soon tell you how long to leave it in for the concentration you use.
Normally everything should be done in 25 minutes but it may be
less, depending on the size of the board, exposed surface, and the
concentration of the solution. Proper timing is especially important
when very thin running tracks are involved.
If you are doing double sided boards, you should at some
point, turn the board over. In this case, unless you have special
holders, you should not over agitate the tray as the copper chloride
precipitate which sinks to the bottom of the tray is rather abrasive
and may scratch off some of the resist on the bottom side. Other
than that, the procedure remains the same.
Some of the shops sell special etching tanks which stand
vertically and has a little electric motor to automatically agitate the
tray. This is not suitable for small scale productions as the tank
normally requires large amounts of etching solution to fill up, and
cost quite a lot to buy. For me, the above method is more than
Drilling of Holes
The drilling of holes is typically the last stage of the PCB
fabrication process so this may seem a little anachronistic.
Nevertheless, this is the last common step of the various methods
of PCB fabrication so I thought it'd be good to cover it now.
Clearly, you will need to drill the holes yourself if you
intend to put components on the board. In some surface-mounted
designs, especially common with microwave and UHF circuits,
this may not be necessary. Unfortunately, you cannot use your
trusty Black & Decker power drill for this purpose because of the
excessive speed of the drill and the oversized drill bit. A hobby or
hand-drill is suitable and cheap ones, both battery powered and
mains powered, can easily be found in Singapore for under S$50.
You will need to get a few common small sized drill bits for PCB
use. The most useful by far is the 0.8 mm drill bit. The 1 mm and
2 mm drill bits also come in handy when drilling larger holes
on the PCB. Generally drilling PCBs do not require a lot of effort
because the PCB material is relatively soft and easy to drill. Be
sure to get spare bits because the bits tend to break easily and are
rather brittle due to their small cross-sectional area.
You should position the drill bit perpendicularly to the
PCB for drilling any holes, and always maintain a steady and firm
grip of the drill. If necessary, you may want to use a sharp
instrument to slightly indent the spot you want to drill, as a guide
as sometimes the drill bit tends to spin away from the point and
scar the rest of the copper surface. Usually though, properly made
boards should have these guides etched in. Do not apply undue
force as this might cause the bit to break or the board to crack.
Apply a steady force on the drill until you feel the penetration of
the PCB. It is also advisable to have a piece of unwanted even
wood surface beneath the board so that you won't destroy your
workbench or your drill bit. Soft-wood is best but other soft
material will also do, eg. old hard cover books.
Normally the drilling process produces a substantial
amount of debris which will obscure your drilling template. Thus
you will want to drill holes systematically so as not to miss any
holes inadvertently, and to drill a section at a time, clearing away
the debris as they accumulate. Do not have the fan blowing while
you are doing this or your XYL will be all over you for messing up
the place! Once you have drilled all the holes, inspect the board for
undrilled or partially-drilled holes. Also be on the lookout for
tracks that may have come off as a result of the drilling. This may
sometimes be the case when drilling large holes on a small pad.
Remove burrs from the holes and then your board is ready.
Masking the PCB
As was mentioned in the basic theory section, there must
be a way of controlling which parts get etched and which parts of
the board don't. I also briefly mentioned a number of methods.
Here I will highlight two of the methods most relevant to us
homebrewers. Direct penning onto the board using etch resist pens
Using Etch-Resist Pens
You can actually draw the desired tracks or patterns onto
the copper clad board with etch resist ink. Get a normal copper
clad board that has been cut down to size, washed and dried
completely. Do not soak the board in the water for too long or the
water may damage the board. Be certain to make sure that there is
not grease on the board or oxidized surface. If necessary clean the
board with some mild abrasive to obtain a shiny surface. Avoid
touching this surface with you fingers or dirtying it. This will
ensure a more even etching later on. There is no need to specially
buy etch-resist pens for this purpose though you could do so. For
simple purposes, permanent markers or Indian ink seems sufficient
for the job. There are advantages and disadvantages of using such
a method. On the plus side, this is a very convenient method for
producing one-off, not too intricate or complex patterns, and can
be done rather quickly. However, you cannot obtain high
resolutions tracks or any degree of evenness with this method. The
results tend to look amateurish. Just as a reminder, the tip of the
etch-resist pen tends to dry up quite quickly so the pen should be
re-capped tightly when not in use. Have a pice of paper near by to
get the ink flow even before tryin to mark the PCB with the pen.
Sometimes you can buy rub-on transfers for tracks or
pads which you can incorporate as part of your pattern to make it
look neater. On the whole, however, this method is reserved mostly
for experimentation or very simple circuits with broadly spaced
tracks. Alternatively, you can also use special tracking adhesives
to paste out your tracks. Either way, the end result is rather coarse
and difficult to reproduce.
Recently, there are available in the United States, special
transparencies which you can laser print or photostat your track
onto, and then iron-off the pattern from the transparency onto the
board. Below is an excerpt which says something of this method:-
From: gary%ke4zv.UUCP@mathcs.emory.edu (Gary Coffman)
There is a special transparency film called Tec 200
marketed for this purpose, but I've found that Avery
overhead transparency film works just as well, and is
available at most larger computer or office supply stores.
You just print your board layout to the transparency with
your CAD package laser driver, remember you want
a mirror image, and then iron it onto the copper. The
copper needs to be clean, just as it would be for any resist
application. You need a fairly hot clothes iron to fuse the
toner to the copper. I use a regular home iron set for
"cotton" and use an old Tee shirt between the iron and the
film. After it cools, you can peel the transparency film off
the circuit board and the toner will remain behind as the
resist pattern. There may be a few pinholes or gaps
where the toner didn't transfer well. You can patch them
up by hand with an ordinary resist pen.
Note you can also use Avery film in ordinary copiers to
generate a transfer from magazine artwork or hand
drawn paper layouts. Of course when laser printing the
film, you need to adjust your CAD driver so that the
laser printer gives a properly dimensioned copy, and
when using a copier, one with infinitely adjustable
"zoom" feature is handy for the same purpose. If the
artwork is "normal", you can first make a copy to a
transparency, flip it over, and use that as your master for
making the transfer transparency.
Works good, costs little.
Another method I have come across of directly masking
the PCB is through the use of flatbed plotters. Apparently, the ink
used in these plotters are etch-resistant and if you can design the
board using CAD software, you should be able to plot the mask
directly onto the board using the plotter. I have not tried this myself
but a friend of mine has and reports good success.
Photo Resist Masking
This is probably the best way I know for making nice
looking PCBs. Unfortunately, the technology behind it is rather
obscure for many people entering the hobby and remains a mystery
for others. Thus I will try to demystify the process here, with some
luck. Contrary to the belief of many, the photo-resist method does
NOT produce tracks on the PCB, it only produces a mask or
pattern of etch-resist material, after which the board still needs to
be etched like in all the other methods.
In this method, you need to get your pattern or mask onto
a piece of clear transparency. This is usually done by laser printing
direct on to the transparency, or photostating on to it. This means
that anything that can be photostated, eg. patterns from magazines
or from the ARRL handbook, or even texts and pictures, can be
etched. This adds a number of advantages. For one, it is much
easier to draw patterns on normal paper than on the copper surface.
There is no need to use special etch resist ink for this purpose. You
can also draw lines with higher density and definition as well as
accuracy than you can using the direct method. You can use PCB
layout software to print out computer generated patterns as well as
including printed texts as part of the pattern. The possibilities are
numerous. It should be noted that all the patterns must be black
and white, no grays, and that the transparency must be clear, clean
and colorless. Transparencies used for OHP presentations are
suitable for this purpose. As an additional hint, you should try to
get the transparency prepared such that the side with the toner is
also the side that will be in contact with the PCB during exposure.
This yields slightly better defined lines as there is then only one
clear edge. It does not matter that the print is not completely
opaque when you look at it against the light, usually normal
photostat contrast is sufficient. You may want to cut the
transparency to the size of the PCB for easier handling. Do not
scratch the transparency as the toner may come off. If you notice
missing tracks, you can still fix it by drawing on the missing tracks
using an opaque black marker pen. If you notice excess tracks,
slowly scrape off the toner/ink gently using a paper cutting blade.
One advantage is that once you have produced one mask, you can
use the same mask to produce a number of identical boards. When
producing the mask, you should try to get it so that the emulsion
side (the print side) is the side that contacts the PCB. This way
when you expose the board, there is a minimum of shadow and
fringe effect at the edges of the tracks and results in higher
The copper clad board must be specially prepared or
sensitized by spraying a film of photo-sensitive masking material
on to it. This spray is normally available in a canister and leaves a
coat of clear green color (usually) when applied to the board.
Spraying must be even and a sufficiently thick film must be
deposited and dried before commencing exposure. All this should
be done in low light/UV conditions as the spray is photo-sensitive.
Alternatively, and more conveniently, boards that have been
presensitized can be purchased quite easily from the shops. In any
case, the spray is very expensive and not easy to use. These pre-
sensitized boards come in light-proof wrapping which you may
remove. The boards have a second protective plastic film over the
surface so you need not worry about accidentally exposing the
boards. The rate of reaction is way slower than that of the camera
film so you need not be overly concerned of over exposure. Just be
sure that you are not doing this under intense fluorescent or sun-
light. The second protective layer is an opaque adhesive plastic
layer which is stuck to the board surface. This is usually white in
color. Do not peel off this layer until you are ready to expose the
board. If you do accidentally peel it off pre-maturely, store the
board in a dark place until you are ready. In any case, these boards
need to be stored in the dark and in a cool environment.
Once your transparency is ready and you have cut the
board to size (without removing the protective layer), prepare
yourself a clear piece of flat glass such as that found in picture
frame. Be sure that the glass surface is clear and clean, and that its
size exceeds the size of the PCB. This glass is used to hold the
transparency to the PCB during exposure. Put the PCB on a flat
surface and align the transparency over it, making sure that when
you look at the transparency, you see the exact image of the
track/pattern that you want, NOT the mirror image NOR the
negative. Be sure your UV source is NOT active. Once you are
ready and have double-checked every detail, slowly peel off the
protective layer from the pre-sensitized PCB and replace it on the
flat surface. Under the protective coating you should see a hard and
dry, green film over the copper. Place the transparency correctly
over the PCB and align it. Then, place the piece of glass over the
transparency to press it firmly to the PCB surface. Once again
check your alignment and then expose the board to the UV source.
The UV source can be a table top fluorescent lamp, or the
sun, or special UV lamps. In all cases the UV content is not the
same, thus exposure time varies. In my case, I use a table top lamp
with an 11-watt fluorescent tube and place it about 2 to 3 inches
above the board for 6 minutes to give me a properly exposed
board. Under the afternoon sun on a clear day, it takes about 8 to
15 minutes to get sufficient exposure. Under UV lamps, the period
may be as short as 30 to 90 seconds depending on the intensity of
your source. Experimentation is the key to knowing how long to
get the right exposure. Excessive exposure will damage the board
and under-exposure will be equally disastrous. Once you have
determined the correct exposure time, however, it is the same
every time when using the same type of board, so be prepared to
experiment a little with your first few boards. NEVER move or
adjust the board once you have started exposure. Once you get
good at it, you can even expose a number of boards
simultaneously. Some types of board will exhibit a slight color
change on the exposed parts once they are done but do not count of
this method to determine when to end because the change is barely
perceptible. Note that if you are using a UV lamp, be careful not
to look at the light direct as it may damage the eyes because the iris
of the eyes do not respond too well to UV and may result in retinal-
During the few minutes of exposure, get the developing
solution ready. This solution is normally sold in the same shops
where you purchased the PCB in the first place. They sometimes
come under the name of POSITIV 20 or something similar and
consists of an alkaline solution. Have this ready when you finish
exposing. If you observe the board carefully, you may notice that
the exposed portions are a little lighter green in color than the
masked portions. This allows you to actually see a faint trace of
your masking pattern on the exposed board. Rinse the exposed
board in the developer solution and if properly exposed, you will
see the exposed parts of the green photo-sensitive film dissolve
in the developer solution. Once the unwanted parts have been
completed dissolved and washed away, rinse the board under cold
running water to remove any remaining developer solution. You
should now see a very clearly defined, green, image of your
original pattern on the PCB now. Dry the board carefully, making
sure that you do not accidentally scratch off the resist/film. At this
point you can still make corrections to the pattern using etch-resist
pens or by scraping off resist/film from excess sections. Once
everything has been confirmed, put the board aside and prepare for
etching as outlined above.
Making your own PCB layout masks
There are a number of ways you can use to produce your
own photo-exposure masks and layouts. Typically you want to
draft out the layout on paper first before committing it to the final
mask. Be sure to take into consideration RF paths and good
grounding. There are a lot of considerations that need to be taken
into account of in the design of a good PCB layout. Once you have
drafted out the layout you can use hand-drawn masks, or combine
hand-drawing with the use of Decal-Dry or rub-on transfers. These
methods are suitable only for low density/complexity designs. The
easiest way however is by the use of CAD software. There are
some easy to use but fairly competent PCB CAD shareware
available and if you intend to produce PCB designs of your own,
you should be familiar with such software. Describing how they
work is outside the scope of this article but among the features of
such software, are their flexibility, multiple printer support,
multiple layer support, silk-screening support, automatic drill
guides on pads, auto-routing, easy editing, free/shareware, standard
component templates and the list goes on and on.
In summary, let me outline the steps and tools involved
in the direct PCB fabrication method. First, the tools and
a) Ferric Chloride or Sodium Persulphate crystals (or
b) A plastic tray big enough to immerse the board fully.
c) The single or double sided copper clad board.
d) Etch resist pen and/or transfers.
e) A small medium speed drill with 0.8 mm bits.
f) Hobby saw or Exacto knife to cut the PCB down to size.
g) File to give the board a good finish.
h) Mild abrasive for removing the resist from the PCB after
The steps involved are as follows:-
a) Prepare a draft of the desired layout.
b) Cut out the required size of the copper clad board.
c) File the edges of the cut down board for a smooth finish.
d) Transfer the layout to the copper clad board by drawing
it on with the etch resist pen or transfers.
e) Double check for errors.
f) Prepare the etching solution as by adding 1 part crystals
to 4 or 5 parts water. Refer to section on etching.
g) Immerse the masked board into the tray with the etching
h) Agitate the tray slightly for about 15 to 25 minutes,
paying attention to the extent of the etch.
i) Remove board from tray when completely etched.
j) Rinse board under cold running water from the tap.
k) Dilute used etching solution with lots of water before
l) Use the mild abrasive to remove the etch-resist from the
m) Use the drill to drill the appropriate holes for the
n) Remove burrs from the holes.
For the photo-resist method, the tools required are the
a) Ferric Chloride or Sodium Persulphate crystals (or
b) A plastic tray big enough to immerse the board fully.
c) Pre-sensitized copper-clad board.
d) Transparency suitable for photostating.
e) UV light source.
f) Developer solution.
g) A piece of clear glass to hold mask in place.
h) Marker pen or transfers.
i) A small medium speed drill with 0.8 mm bits.
j) Hobby saw or Exacto knife to cut the PCB down to size.
k) File to give the board a good finish.
l) Mild abrasive for removing the resist from the PCB after
The steps involved in the photo-resist method are as
a) Prepare the masking pattern on a piece of white paper.
b) Transfer pattern to the transparency by photostating.
c) Cut the pre-sensitized board down to size.
d) File the edges to remove unevenness.
e) Place transparency on the board to check alignment.
f) Peel of protective layer from board.
g) Align the transparency on the board.
h) Place glass over the transparency to hold it firmly in place.
i) Place the UV source over the board and glass.
j) Activate the source and expose board for a suitable period. Read above.
k) Rinse the exposed board with the developer solution to
dissolve unwanted resist.
l) Double check for errors.
m) Prepare the etching solution as by adding 1 part crystals
to 4 or 5 parts water. Refer to section on etching.
n) Immerse the masked board into the tray with the etching
o) Agitate the tray slightly for about 15 to 25 minutes, paying
attention to the extent of the etch.
p) Remove board from tray when completely etched.
q) Rinse board under cold running water from the tap.
r) Dilute used etching solution with lots of water before disposal.
s) Use the mild abrasive to remove the etch-resist from the board.
t) Use the drill to drill the appropriate holes for the components.
u) Remove burrs from the holes.
The real key to learning to make PCBs is to do it yourself.
In this article I have tried to provide a general idea of the process
of fabricating your own PCBs and have purposely included a
number of cautionary and warning notes so that the reader will be
aware of the hazards involved. On the other hand I have been
making my own PCBs for about 8 years now and have not suffered
any side-effects or harm. Hopefully, this article will open new
doors and possibilities for the homebrewer and that through
homebrewing, one very significant aspect of the original spirit of
Amateur Radio may be restored. If there should be further
inquiries, I will be more than glad to help out.
73, Daniel Wee
From: firstname.lastname@example.org ()
Subject: PC board manufacture: my technique
Date: Tue, 3 Nov 1992 18:41:34 GMT
I have followed the past thread on making pc boards and
have tried all of them except for plotting with ink on copper
directly. I don't have a suitable plotter. I have tried
transparency film and release paper with only mediocre results.
The best luck that I am having now uses ordinary copier
paper. I print on the paper at normal density. I am using a
"super black" toner cartridge from Black Lightning. I don't think
that this is necessary because I tried the output from another
printer with an ordinary cartridge and got equivalent results.
All of the following technique is with the super black toner.
I prepare the copper surface by sanding it with number 320
wet sanding sand paper. I do the sanding dry (don't know if this
matters). I sand in small circles so the scratches go in all
directions so the adhesion will not have a perfered axis.
I iron the paper onto the copper with the iron at 170 degrees C,
that is the highest temperature on my iron. The fuser
in my laser printers (LaserJet II and III) runs at 160 degrees C.
I iron for about 30 seconds on my counter top with a paper
towel between the board and counter top. This provides
insulation and a slight springiness to the board as I iron.
I iron enough to insure that every part of the paper is heavly
pressed onto the board.
Immediately after ironing I place a wet (dripping)
paper towel on the ironed on paper and press the iron onto
the wet towel. This drives steam into the paper. Without
this step the paper will shrink and pull the toner off the
copper. The steam causes the paper to swell up and relieve
the strain. The iron should be placed on the towel for
a split second or the paper will dry out. I then soak
the paper with dripping water and let it sit for about 5
The paper should be completely soaked and swelling
between traces. I then rub the paper with my fingers under
running water. The paper will begin to ball up and come off
in layers. I rub it until I get as much off as I can. At
this point the traces should be well attached to the copper and
not at risk at coming off.
You will find that all the toner has a paper fibers
imbeded into its surface. This is not a problem in most cases.
The problen arises when the fibers bridge the gap between
traces or pads. To solve this I scrub the board with a brass
brush. This brush is like a tooth brush with bristles made
of fine brass wire. The brush will break the fibers that
bridge gaps between toner areas. Do this while the board
is wet. Let the board dry and inspect all the toner
for fibers that would prevent proper etching. Pick any
remaining fibers away with an exacto knife.
While I etch the board, I periodically scrub the surface
with a real tooth brush to insure that the fibers are not blocking
etchant access to any portion of the exposed copper. Do not use
the brass brush in the etchant as it will be desolved itself.
I have made a number of small boards up to 2 by 4.5 inches
using this process and some with very fine traces and spacings.
I complete the etching of one side before I apply the toner
to the other side. I don't know it this process will scale up to
larger sizes well. It seems to me that the steam step is
particularly important. Before I did this traces would pull off at
the edges of the board as the board cooled.
>>>>>>>>>>>> Peter Reilley ..... email@example.com ..... KA1LAT <<<<<<<<<<<<<
Well, that about says it.
firstname.lastname@example.org (Ed Hare - KA1CV) writes:
>> If anyone knows of any other suppliers of inexpensive custom prototype
> printed-circuit boards or small-quantity printed-circuit board supplies,
> please send the information by postal mail to:
The best deal in DOUBLE SIDED that I know of is
#14-3650 19 St NE
Canada T2E 6V2
But they require that you have a GERBER file and drill tape, and you have
to buy two boards. I have not tried them so I cannot speak to the quality.
The price is something like $92 for two 5x6in boards. Same price for
single sided. I've seed their add in Nuts and Volts.
The best deal that I know of in SINGLE SIDED prototypes, and the most
exciting thing to come around in a long time is
1355 W. Palmetto Park Rd. Suite 158
Boca Raton, FL 33486
Get this, $25 for any 4x8in board or smaller. And they will do ONE
for that price. They will also put smaller boards onto that 4x8in area
if you meet certain criteria like total number of holes and cutting them
apart yourself. They do NOT require GERBER files nor drill tapes.
They take HPGL plot files, PCX bitmaps, laserjet PCL files, and
Postscript files. If all that is not enough, they also scan artwork you
send them from magazines or books, or that you drew by hand, and the
scanning is included in the price. They also have a alternate pricing scheme
which is beneficial for very small boards; $4 per square inch with a ten
dollar minimum. I've seen their classified in Nuts and Volts, Popular
Electronics and occasionally in 73 Amateur Radio Today.
Disclaimer: I have no affiliation with either of these two companies
other than my wife works at the latter company. I have used the
latter service and can speak for the quality.
Charlie Bustamante ... In balmy Boca Raton, Fl USA
internet email: email@example.com
From: firstname.lastname@example.org (Alan Bloom)
Subject: Re: Directly plotting etch-resist on PC boards?
Date: Wed, 13 Apr 1994 19:36:37 GMT
David DiCarlo (email@example.com) wrote:
: Well, I tried it this weekend by photocopying on to a sheet of
: transparency and ironing that onto the copper. ...
I'm surprised nobody mentioned the ready-made kit you can buy
specifically intended for this application. It uses a
specially-coated paper so that after you iron it onto the PC board
the paper soaks off in a pan of water, leaving the toner behind as
resist. You then etch the board in the normal way.
The pattern can be laid down on the paper using a photocopier
or laser printer.
The only tricky part is that the board must be completely clean and
scoured with fine steel wool. The steel wool seems to roughen the
copper so the toner sticks better. Another trick is to soak the
board with the paper side down. Otherwise, the paper can pull off
some toner as the paper floats up.
: My question is, what iron temperature was used and was the transparency
: peeled off hot or cold? I used 1 sheet of paper between the iron and the
Seems like the hotter the better. I haven't had any trouble with
toner smearing or widening of the traces.
I bought my kit (with 5 sheets of 8-1/2 x 11" paper) for $12.95 from:
Scottsdale, AZ 85257