Printing microwave PCBs how to?

I am trying to find a way to print at home these microwave PCB boards (Rogers etc)

I am very confident with the photochemical method, using transparencies, caustic soda and 3chloride FE (the red liquid), and I use an HP940C inkjet printer for printing transparencies, with very adecquate accuracy.
The ink thickness is really thick, so it is ok for this method.

I was thinking of converting the tray of this printer (or look at the manual if there is a back paper output), in order to directly feed the PCB into the printer and print the pattern directly onto the PCB.

Rogers boards do not have the photochemical coating so printing directly onto the coper seems ok at least for frequencies up to about 10GHz. Additionally, these rogers PCBs are really thin (like 3-5 common A4 papers stacked together)

Have you got any other ideas for printing these high frequency PCBs at home?

I have been looking at printing nano silver ink onto blank board to make the traces directly--no etching. Last time I looked, you needed to buy a very expensive printer to do it....was hoping for a cheaper way to go.

Etching boards is more standard processing, but how do you get rid of the nasty chemicals? If I have to etch a board, I send a quickturn board house the artwork file.

biff44 said:

I have been looking at printing nano silver ink onto blank board to make the traces directly--no etching. Last time I looked, you needed to buy a very expensive printer to do it....was hoping for a cheaper way to go.

Etching boards is more standard processing, but how do you get rid of the nasty chemicals? If I have to etch a board, I send a quickturn board house the artwork file.

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Well, I do not get rid of them. At least not quickly.
The mixtures can be reused many many times before they wear out. I have seen an intransparent bottle of caustic soda on a professional electronics lab and its still used.

The method you propose requires very expensive inks, and I do not know if there is any of these including the heads for ordinary printers. I think if one is to pay so much, he could send it for manufacture on a professional lab.

I am still sceptical about the printer method I reffered to earlier, it seems so much quicker and easy, and the only way for microwave PCBs at home...?

I recommend you to send your gerber files to low volume PCB manufacturers in Europe.They manufacture your PCBs precisely for Microwave frequencies, otherwise some errors become unavoidable.

You can of course buy photochemical spray paint and then use convenventional photo-etch methods. I have used it to make various boards although none of them were using Rogers substrates.

There are several makes, look for "Positiv 20" in google.

Brian.

neazoi said:

Well, I do not get rid of them. At least not quickly.
The mixtures can be reused many many times before they wear out. I have seen an intransparent bottle of caustic soda on a professional electronics lab and its still used.

The method you propose requires very expensive inks, and I do not know if there is any of these including the heads for ordinary printers. I think if one is to pay so much, he could send it for manufacture on a professional lab.

I am still sceptical about the printer method I reffered to earlier, it seems so much quicker and easy, and the only way for microwave PCBs at home...?

Click to expand...

I agree...in the past the printer heads are expensive. But I keep hoping someone comes up with a $40 injet head that just plugs into an HP or Epson injet printer.

BigBoss said:

I recommend you to send your gerber files to low volume PCB manufacturers in Europe.They manufacture your PCBs precisely for Microwave frequencies, otherwise some errors become unavoidable.

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Yes, but some small errors could be acceptable for amateur use up to the X-band. Unsuitable for most 24GHz work though.

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betwixt said:

You can of course buy photochemical spray paint and then use convenventional photo-etch methods. I have used it to make various boards although none of them were using Rogers substrates.

There are several makes, look for "Positiv 20" in google.

Brian.

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I have tried it in the past betwixt. I hate it. It badly stinks and the fumes are very hazarous. Not to mention the difficulty of making an even layer onto the whole PCB and the need to dry it for 1-2 days or (!!!) ovening it.

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biff44 said:

I agree...in the past the printer heads are expensive. But I keep hoping someone comes up with a $40 injet head that just plugs into an HP or Epson injet printer.

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This would be really great, but I do not mind to have just a solution to etch, it is cheap and reliable

I tried to modify another printer I had and I have managed to print on a pcb directly but when put into the etch liquid the ink was removed from the PCB. Later on I read somewhere that special pigment inks must be used and preheated. Not good. The transparency method is overal easier and cheaper...

By the way, I do not like positiv sprays, so I looked for a liquid type.
I have found this page https://www.megauk.com/pcb_chemicals.php which shows a brush style positiv applicator.
I would like your comments please, or any other sources for similar positiv aplicators (no spray).

I haven't tried that applicator but I do use Mega as a laminate, chemical and drill supplier and they are very reliable. Take note of their warnings about export outside of the UK though.

Brian.

betwixt said:

I haven't tried that applicator but I do use Mega as a laminate, chemical and drill supplier and they are very reliable. Take note of their warnings about export outside of the UK though.

Brian.

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Thanks for your reply,
I will probably make an order soon

A poor man's T-Tech:

https://www.youtube.com/watch?v=rDRN1_i0vJU

(p.s. remember PCB milling dust is toxic, you do NOT want to breath it!)