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Making Homemade Single Side Printed Circuit Boards (PCBs)

It is possible to make reliable homemade printed circuit boards at home and the process of can be very rewarding. With the steps listed below you can get repeatable results every time. The techniques I am presenting have been tested and refined over numerous projects.

Instead of waiting weeks for custom boards to arrive from overseas manufacturers you can make your own board from start to finish in about an hour or so.

mcu in hand

mcu

Get the Required Gear

Supplies Required:

Copper Clad Printed Circuit Board – PCB material
Phaser FX Toner Transfer Paper
Phaser FX Green TRF material
AVERY laser printable mailing label paper
Ferric Chloride
Plastic Etching Tray
Eye Protection
Plastic Nitrile Gloves
Small PCB Drill Bits
Fine-tip Sharpie marker
Temperature controlled soldering iron

Equipment Required:

Computer
Diptrace or similar PCB CAD package
Laser Printer or Plain Paper Laser Copier
Laminator
Drill Press

Nice to Have:
Microscope

Let’s Make a Homemade Circuit Board

Step 1. Designing a single sided circuit board

I enjoy using the CAD program Diptrace to design my circuit boards because of its intuitive and easy to use GUI. Diptrace is made Novarm, Ltd.. and is available in both a commercial version and a freeware version. The freeware version is fully functional with a 250 pin limit. If you use the Diptrace pannelize command you can output multiple boards on the same sheet of paper and they don’t count towards the pin count limit.

PCB design

I find Diptrace is an easy to use Printed Circuit Board CAD design package. Diptrace has a schematic design module and a PCB design module. The two designs are tied together with a NETLIST that allows you to know the names of the pins and traces. The auto-router built into the PCB program can help you quickly route the traces in a circuit based upon the schematic design.

Schematic design

For making simple single sided PCB designs I recommend putting the through hole components, connectors, and any jumper wires on the top side of the board. Then you can put the copper traces and surface mount components on the bottom side.

When using the auto-router set it to use 1 layer and start the auto-routing with the bottom layer active so the traces are made on the bottom layer.

As a design step for simple and reliable homemade PCBs I find it is easiest if I make the pads for through hole parts and VIAs 87 mil diameter and the center hole approx. 47 mil in size. This gives lots of copper to solder to and makes drilling easy. The last thing you want in the drilling process is to rip up tiny copper pads!

Don’t forget to put a power indicator LED on the board so you know the board is on. Also make sure that you have a current limiting resistor on any LEDs. Also don’t pull more than 25 millamps on any individual microcontroller pin.

A handy current limiting LED resistor calculator is:

http://home.cogeco.ca/~rpaisley4/LEDcalc.html

When using buttons in a design don’t forget to add pull-down resistors or you may get strange results.

It is a good idea to add removable polarized connectors to any power cords that are attached to the PCB. This will help reduce problems and protect the board from reversed power connections.

It is also a good idea to use a DIP socket for DIP based microcontrollers vs. directly soldering down the DIP chip. This is handy during development and prototyping stages.

Step 2. Printing off the design

Using a laser printer and toner transfer paper can allow you to get the circuit design out of the computer and onto the copper clad printed circuit board material.

To conserve materials I mark an arrow on the printing side of a piece of letter sized 8.5″ x 11″ paper showing the feed direction. Then I print off the design on the paper for positioning and alignment.

Next I cut out a small square of toner transfer paper that is 1 cm larger on all sides than the design. Make sure to place the toner transfer paper glossy side up.

Print off the design the with the following settings:

Print Resolution – 1200 DPI
Toner density – normal or Extra Dark Printing if available

In the Diptrace Print Window set the following settings:

Print the bottom layer non-mirrored at 100% scale.
Enable the printing of Pads, VIAs, holes, traces, connections, board, and assembly layers.
Disable the printing of Silk layers and tables.
Enable the Print in Black option so the board outline will be printed in Black.

Diptrace Print Window

I attach the small piece of toner transfer paper to the letter sized sheet of regular paper page using a strip of AVERY paper mailing labels.

An important note is that if you use plasticized tape to hold down the toner transfer paper it will melt in the laser printer and jam the machine so use something like AVERY laser printable mailing label paper for success.

printing on toner transfer paper

printing off the design

When I made my first toner transfer printed circuit boards I started with glossy photo paper and magazine paper for the toner transfer along with a clothing iron.

I’m really happy I switched to using specialized papers like the Pulsar FX Toner Transfer paper because it provides the best results I have seen to date. The Pulsar FX paper offers consistent results and works very well with a laminator and the toner transfer paper releases easily from the PCB when immersed in water. If you use glossy photo paper or magazine paper you will need to soak it for a long time and scrub it off with a tooth brush.

Just a reminder that you have to print off the design on a laser printer because it is the laser printer toner that provides the etching resist mask that will stop the traces from etching away. You cannot use an inkjet printer for this task. It is a good idea to use a laser printer that has a consistent black toner density and doesn’t leave behind any splotching or roller marks on the paper.

If you don’t have a laser printer you can take your design and print it off on plain paper with an inkjet printer and then use a laser photo copier to transfer the design onto the toner transfer paper.

Step 3. Cut the PCB material to size

Using a band saw cut the printed circuit board material to the size of your design. After you cut out the board, sand the board edges to remove the roughness of the fiberglass. You may want to use very fine 320 grit sandpaper to prepare the board lightly so the toner transfers properly. After sanding you need to clean the new copper clad printed circuit board material and keep the oil from your fingers off the copper surface by holding the board by its edges.

Step 4. Laminating Part 1

You will need to buy PCB material that is the right thickness for your laminator. Thin PCB material works well for most homemade PCB projects.

Let the laminator heat up fully.Then using another cut strip of adhesive paper from an Avery mailing label stick the toner transfer paper with the glossy printed side against the freshly cleaned copper side of the PCB material.

Set the laminator to its thickest mode.

laminating the toner transfer

Feed the PCB into the laminator a few times to guarantee that the toner is transferred from the paper onto the PCB material. I find between 5 to 7 passes through the laminator works well depending on the PCB board thickness and the laminator heat output.

Let the PCB board cool for a few minutes after laminating.

When the board is cold to the touch soak it in a container of luke-warm water for 3 minutes. This will soften the toner transfer paper. Once the PCB board and the toner transfer paper have been soaked the paper should slide right off the board without any force*. Pulsar FX toner transfer paper will release and leave behind no residue on the printed circuit board.

*Once again I will mention if you try and use any other paper besides toner transfer paper such as glossy magazine paper or glossy photo paper you will have to scrub off the paper backing with a tooth brush after soaking for a few minutes.

Dry the board with a clean piece of paper towel.

Hopefully the traces are a nice dark color and look solid.

Step 5. Check your design against the actual PCB design

Gently set any surface mount components on the toner transferred PCB board to check for the proper pin 1 alignment of the ICs and for proper scale and positioning. This is the last point in time where it is easy to update the PCB board design!

Fixing Design Issues After the First Toner Transfer
At this stage if you notice any problems with your PCB design you can remove the toner off the board using acetone. Acetone is an aggressive solvent so make sure to wear thick nitrile plastic gloves because acetone goes through latex gloves very quickly. Safety glasses are a good idea too.

In a well ventilated area transfer a small amount of acetone onto a folded piece of paper towel. Gently wipe the toner transfer off the printed circuit board by slowing rubbing the surface with the acetone coated paper towel. If the board is a large design you may need to fold the paper towel over again and use more acetone to remove the rest of the design.

Once the board is clean and dry you can revise the CAD design and repeat the printing and laminating steps.

Step 6. Laminating Part 2

If most of the design looks perfect but there are any small breaks in the traces use a fine tip sharpie marker to fix them. This works well with Ferric Chloride etchant. If you use Ammonia Persulfate etchant, sharpie markers won’t be able to fix problems in the toner transfer. The ammonia persulfate etchant will chew right through it. In this case cut thin pieces of electrical tape just large enough to fix the broken trace and apply it after you complete the next green TRF laminating step.

The Pulsar FX Green TRF material thickens the density of the toner transfer and can fill in areas that have a light toner transfer coating. Pay attention to the orientation of the greenTRF film becasue the matte side of the toner transfer film must go against the printed circuit board. Cut out a piece of green TRF film slightly larger than the PCB material. Leave a 1 cm longer section folded over the side of the board that will be the leading edge when you run the greenTRF film through the laminator.

Feed the PCB and greenTRF material into the laminator.

laminating green trf

Once the laminator has a hold on the PCB provide a slight tension on the green TRF foil to keep it flat and wrinkle free. You can feed the green TRF film and PCB through the laminator a few times to ensure proper adhesion.

Let the PCB cool for about 2 minutes.

Peel off the green TRF foil. In areas where there is toner on the PCB the green TRF coating will stick. This will give the traces an almost plasticized appearance.

Step 7. Etching the Copper

Put on plastic nitrile gloves and eye protection.

Pour a small amount of Ferric Chloride into a shallow plastic sealable container. Do not use a metal container to store the etchant as it will be dissolved over time by the etchant chemicals! Don’t forget to label the container with the etchant’s chemical name and write POISON on it. Keep the chemicals away from young children.

copper etching

Place the toner transferred PCB into the etchant. Soak a disposable sponge in the ferric chloride and slowly rub the entire PCB material. Every so often dip the sponge in the etchant to suck up more fluid. Rub the circuit board in a constant pattern for around two to three minutes until all of the unmasked copper has been etched away. A smaller circuit board will etch faster than a larger circuit board so you need to spread out your rubbing action on a larger design.

sponge etching

etching half done

Once the unmasked copper has been etched away wash the board under water to stop the process. Safety tip: Don’t rinse the PCB board in a sink that is used for food preparation!

Dry the etched PCB with paper towel. When you are satisfied with the etched PCB seal the container that holds the etchant to reduce the risk of spilling the chemicals.

Now you need to remove the toner transfer mask. In a well ventilated area wipe the board slowly with acetone to remove toner transfer resist mask and expose the copper traces.

six processors on one board

acetone wiping the PCB

Step 8. Drilling the PCB

Take your time when using a drill press and put on eye protection!!!

I find a 1.12 mm drill bit works well with my drill press. In my experience I find that if your drill press has any wobble in the chuck using the largest drill bit that will get the job done means the drill bits will last longer and are less likely to break off in the PCB.

Using a small drill bit drill out the pad and VIAs on PCB takes patience.

Using a small drill bit drill out the pad and VIAs on PCB takes patience.

Make sure to hold down the PCB as you drill so it doesn’t spin or lift off the deck of your drill press.

Step 9. Soldering the Components

Solder all of your surface mount components first then add the through hole parts. Try and keep your time soldering surface mount components to the minimum so you don’t over heat them. Solder DIP parts, resistors, capacitors, next. When soldering the through hole components I often find it easier to put down the high pin count ICs and then work my way down to the smaller parts.

When soldering through hole components and especially DIP parts I find a bent conical tip works well. Also, I find it is best to put any jumper wires in last so they don’t get in the way of any other parts and you can make the wires as short as possible.

I solder most through hole components with a soldering iron temperature setting around 375°F. For the last few years I have used a temperature controlled Ayoue solder station I bought off eBay and I have been very satisfied with it.

As you are soldering the circuit board constantly clean your soldering iron tip on a wet sponge to remove dirt and residue that builds up. If your tip is dirty you will get inconsistent results when soldering.

If you have a microscope you will find it helps to inspecting the solder joints for quality assurance. I purchased a trinocular boom microscope off eBay and it has really helped with soldering tiny surface mount parts. The microscope I purchased has 6 inches of working height and I can use my soldering iron while looking through the stereo eyepieces. This allows you to easily solder pin to pin on a 64 pin TQFP.

Use solder wick or a solder sucker to gently remove bridging between pins. Be careful when using solder wick that you don’t pull up any traces.

If you are using lead free solder solid-core SAC 305 solder be sure to add liquid flux when soldering.

positioning the smd part

Step 10. Inspecting the Assembled PCB board

Use either a microscope or magnifying glass to inspect all of the traces for any problems. A digital camera set to macro mode can also be used to inspect the board. After assembly it is a good idea to check the traces using your multimeter in Ohms mode to look for short circuits from solder bridges on the PCB.

resistor inspection

Step 11. Programming the Microcontroller

If you are using dip based microcontrollers, program them in your development board then install them into the PCB board. If you are using a surface mount MCU, you will need to use In-Circuit Serial Programming (ICSP) to program them. For embedded projects I enjoy using MikroElektronica products for MCU development. Their EasyPIC dev boards and MikroC compilers are excellent.
ICSP Programming

7 comments
  1. Re: As a design step for simple and reliable homemade PCBs I find it is easiest if I make the pads for through hole parts and VIAs 87 mil diameter and the center hole approx. 47 mil in size.

    How? please.

  2. Hi Eric.

    You can change the pad size in your final Diptrace PCB Layout by right clicking on the part in the PCB Layout module and selecting the “Pad Properties” option.

    * * *

    You could also change the default pad size for each of your custom parts using the Diptrace Pattern Editor.

    After you open the Diptrace .lib file in the Pattern Editor, and select the part. Select the pad you want to change. You can group select multiple pads at the same time. Right click on the pad and selecting “Properties”.

    The “Pad” properties window will open. Click on the “Type / Dimensions” tab. You can set the shape of the pad, change the pad’s width and height, and edit the hole shape and diameter.

    Regards,
    Andrew

  3. Hi Marius.

    My current printer is a low cost Samsung ML-2510 printer. Most laser printers will work fine with the toner transfer process. The important thing is to make sure to print the document on a printer with even toner distribution and a fairly new printer drum.

    You can test this by printing a page with a solid black image. If the printed black toner looks consistent across the page then the printer should be fine for making toner transfer prints.

    Something to keep in mind is that as a laser printer ages the printer drum can develop ‘grooves’ that will cause light lines to show up across you page as it is printed. You will come across this issue if you use a high-traffic office laser printer that has had the toner cartridge refilled multiple times.

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