PCB the easy way: picture series

[OliverD]

For those who have never done it (probably not many anyway), for those who want to try a better and cheaper etchant, and for those who click on any thread with pictures (like I do)

All you need is a laser print or copy of you PCB layout on plain paper. Mirror the print, so the toner has contact with your board. Put some text on you PCB layout to remember which side is up. You need two prints to increase the contrast. One layer of toner often is too transparent.



The next step is making your layout transparent. People are selling expensive chemicals for this, but I tend to prefer veggie oil. I recommend buying (or building) a light box with UV tubes. I got much better and more repeatable results and will never go back. Properly align the two prints, put the PCB on them and light for about five minutes.



Don't expose your eyes to ultraviolet light. I've done it once. Believe me.

After lighting, remove the veggie oil from your PCB (you cannot process it otherwise) and clean you lightbox from the mess you made.

[OliverD]

To develop the board, you need a solution of 10g NaOH in 1 l water. Don't use hot water.



I use a precision weighing machine to prepare the mixture.



NaOH is a hazardous chemical! Wear suitable gloves and eye protection. Avoid contact with skin and seek medical advice when you failed to.

This is how the board looks after developing:

[roibm]

Nice way to do it.
I was using the toner transfer method and had some problems with it. It's really hard to find the ideal paper for toner transfer but once you find it it's really easy(assuming one has a laser printer).
After the toner is fixed, all you need is smoking HCl

[OliverD]

Rinse the board in water. Have a careful look if everything went right. It is the last time to correct little errors. I use a steel needle to remove from, and an etch resistant pen to add to the etch resistant on the board. Write down a series number if you like or sign your boards

I use a special etchant which is water clear, very fast and also cheap! This is what you need:



Hydrochloride acid, fuming, 37%



Hydrogene peroxide solution, 35%

ATTENTION when using these chemicals! Wear protective clothes, eye/face protection and gloves. Both chemicals can cause severe burns. Store them only in suitable bottles and keep them in a cold and dark place. Allow for ventilation. Hydrochloride acid, even when kept in a closed bottle, will corrode metals in the room... Keep away from your valuable tools! When feeling unwell, immediately seek medical advice and show the labels from the bottles. Don't flush these chemicals in the toilet!

[OliverD]

The receipe:

For 1l etchant, mix (in this order!) 770ml hot water, 200ml hydrochloride acid, 30ml hydrogene peroxide.

Here you can see the copper dissolving:

[OliverD]

Never etch a PCB without proper ventilation, especially when using these chemicals! Don't do this in your living room or the kitchen. If you don't have a workshop, better go outside.

Here's the PCB after stripping the etch resistant with acetone and drilling:



It's a double sided design, but no vias. It belongs to this project.

[jackinnj]

35% Hydrogen Peroxide is a very powerful oxidizer and not readily purchased by the average DIYr. You can use pharmacy H2O2 by increasing the volume to attain the same molality -- here's my recipe using readily available chemicals:

400ml water
250 ml 31.5% hydrochloric acid (Muriatic Acid)
350 ml 3.0% hydrogen peroxide (Pharmacy Brand)

Wear goggles, don't wear your favorite jeans or shirt! Add acid to water, the reaction is exothermic so be prepared for a rapid rise in temperature. Then add the H2O2, stir.

200 ml of the above solution etched a 4 by 4 inch board in 8 minutes.

You can discard the solution in plenty of running water.

You can also use the hydrogen peroxide from a hair salon -- this is a 7% solution (hmmm, sounds like Sherlock Holmes) In this case adjust the percentages accordingly. H2O2 is available to 91% concentration, but you have to be NASA or the U.S. military to obtain it.

[Rudy]

Originally posted by OliverD
To develop the board, you need a solution of 10g NaOH in 1 l water. Don't use hot water.

actually, you can do this with "caligene", the name is dutch, i dont know how you call it in english ( somebody ??) , but it is basicly a cleaningprodukt, it cost about 1 euro for 1 liter, and you need about 10cl/liter.

and now the good thing, you can just flush it away trough your sink, thats wat's it made for

[OliverD]

Probably "Caligene" mainly consists of NaOH. We have a cleaning product in Germany called "Rohrfrei" which consists of NaOH and aluminium scraps.

NaOH is really cheap to get, the package is the most expensive part of it. However, buying these might be a problem for the typical DIYer as mentioned above. I ordered the chemicals through my gliding club.

[ashok]

Hi OliverD,
That write up with pics was very nice.
But I couldn't understand what you did with the vegetable oil and your reference to " making the print transparent ".

The next step is making your layout transparent. People are selling expensive chemicals for this, but I tend to prefer veggie oil. I recommend buying (or building) a light box with UV tubes. I got much better and more repeatable results and will never go back. Properly align the two prints, put the PCB on them and light for about five minutes.

Looks like you missed out that because everyone ( except me ?) knows what is to be done.

I have the prints , the clean board and the veggi oil. What next?
I know the step after that , remove excess veggi oil ( with soap ?). So does one apply the oil to the board ?
The next one would be etching.
Sorry for being dumb.
Thanks,
Ashok.