hello guys !!, You may have or not the experience with printing your own custom PCB . There are so many methods to follow in order to make a PCB. The usual way to print a circuit is to apply the pattern(circuit) on a copper clad board and etch the unwanted copper.But if we can make the copper board our own, there are many possible creative things that can be performed. So in this instructable I'm gonna show you a method that could be used to make a custom PCB on anysuitable surface. Any surface want make this possible .In order to solder things on the surface that hold the copper layer sould sustain to higher temperatures around 270 degrees of celsius. Materials such as plastic wont make it .For this demonstration I choose glass.Because it sustain the required temperature and also it is awesome to make a transparent PCB. So without further ado lets start ....
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Step 1: About the Technique
There are many techniques to make PCB .These techniques varies from the method that used to transfer the pattern(circuit design ).You can simply draw the circuit on the copper with a permanent maker. But that gives an untidy output.Or you can use the toner transfer method. In this instructable I'll show you how to use UV curable mask to transfer the circuit on to the copper board .UV curable mask give a super fine output even with smaller track width. This is the method that used even in mass production of PCB.
UV curable etch resist is a thin layer which get hard when get exposed to UV light . This resist laid over the copper board and expose it to a UV light source through a opaque film that consist an image of the circuit .By the way the the circuit pattern get cured on the resist film.By applying a developer it is possible to remove the uncured film and obtain the circuit ready to get etched. Don't be confused with the word developer ,it is just a low basic solution like baking soda that have the ability to remove uncured UV resist.
There are two types of UV resist films which are positive and negative.When the developer added, exposed parts of the photo resist remains undissolved ,while other parts get dissolved .positive is vise versa .In this Instructable I use a negative one.
Step 2: Materials
Step 3: Prepearing the Circuite Design
As mentioned in the above step we need the design of circuit which is transfer to a transparent sheet.This can be done by printing the design on to OHP paper.But first of all we have to design the circuit.There are so many platforms to design a circuit. Personally I use a online circuit design software called "EASY eda". It is easy to learn ,free of charge and easy to find components.just go through some tutorial and you may familiar with it.
First make a schematic diagram of your circuit .Then model the PCB layout .After that using auto route tool,rout the paths of your circuit .This may sound bit complex for beginner .But with some tutorials you'll be fine.
In the design there are so many unwanted texts and component diagrams. For our purpose we need only the tracks and pads . Therefor after you satisfy with your design isolate the paths and pads layer in the layer pallet and export the monochrome image as a PNG.
We use the negative type of photo resist ,which means we need to expose the resist to light were we need to remain copper.There for it is compulsory to use the "white on black " option in the exporting dialog.It means that it keep tracks and pads white on a black background.White means OHP paper remains transparent after printing.
Step 4: Printing the Design
up to now we have the designed and exported image. The purpose of the OHP print is to make a mask which blocks UV light exporsure of the resist in unwanted regions.In order to do that the black parts of the OHP print should block light perfectly.If not light would leak through them.One layer of print do not block light perfectly. Therefor 3 print were aligned and place on each other and glued to keep steady.
Step 5: Gluing the Copper Foil to the GLASS
As I mentioned above I'm gonna make a copper which lies on a glass.To make this my plan is to gluing a copper foil on a glass.In the final stages we have to remove unwanted copper by dissolving with ferric chloride .Choosing a thick copper foil make that process more time expensive.A thickness around 0.05mm is perfect.
To prepare the glass ,first we have to clean the glass and the copper foil with rubbing alcohol .If not the copper want stick to the glass well. After cleaning put some decent amount of glue onto the glass and spread all over the glass. Then place the copper foil and press firmly.Make sure that there are no any air bubbles in between glass and copper foil.Remove excessive glue by squeezing the copper foil. Leave it to be cured well.
Step 6: Applying Photo Resist
first of all cut off required sized piece .The photo resist come with covered in both sides with two transparent covers. The photo resist material is sticky.When the cover removed it can be stick to the copper board easily. As I told the resist film consist two covers.In order to stick the photo resist we have to remove cover.to do that we can stick two pieces of scotch tape on top and the bottom of the resist film.By tearing those tape pieces it is possible to remove a cover .Then carefully place the uncovered side on the copper .Gently press the photo resist in order to stick them both well. Make sure you don't make any air bubbles between photo resist film and copper.
Step 7: Make the Setup to Expose to Light
After applying photo resist now we have to make the setup.Take the OHP print out that we made previously .place it over the copper board. Make sure to place the correct side of the print.If not the whole print may mirrored.After that place a sheet of glass to ensure that OHP print keep tight to the copper board.I have added two clips to keep the setup steady.Now its time to expose to light.
Step 8: Expose to Light
Now we have to expose the setup to light.You have the freedom to use a artificial UV source .bright sun light is a good source of UV light .Around 5 min of expose to the sunlight will do the job . Make sure to keep the whole setup steady though out the exposing process .That's were clips do a great job .
After 5-7min take the setup out of bright sun light and disassemble every thing .You should able to see slightly the print have cured on the resist.It is shown in the image.
Step 9: Develop the Resist
The resist film have another layer of cover on top of it.In order to develop it. we have to remove that also.Again with a help of a scotch tape remove the cover.
Take some backing soda and make a solution out of it. Any basic solution will dot he job. If you unable to find backing soda ,rinse powder also do the job perfectly .Anyway after making the developer (backing soda/ rinse powder solution) dip the board and keep a moment.Then take it out and wash gently.you must able to see the unexposed parts are getting washed away.Repeat the process until all the unexposed parts washed away.
Finally you will end up with a copper board with tracks of cured resist.Now it's time to etch...
Step 10: Etching
Take some amount of ferric cloride powder and dissolve in about 150ml of water the solution must be dark .If not add more ferric cloride.After making the solution dip the copper board in the solution. Shake the board often to etch efficiently.After around 10-15 min all unwanted copper may removed remaining the paths.
Step 11: Final Product
With some acetone or warm water it is possible to remove the resist over the copper paths .
So what now,,. making a PCB on a Glass may not give any electrical advantages.these type of circuits can use for many projects associated with transparency is needed.such as a led set on this kind of circuit might be awesome.
This technique opens path to many creative things .Even on a curved surface we are able to create a PCB. Replacing glass with kapton tape it is able to make flexible circuits.
I'll stop this here.I think you learned some thing new ......
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