Homebrew PCBs

To follow up on the "Electrical Discharge Machining plus painted board plus CNC x-y table" discussion,  I would like to suggest a similar idea.  What do you think of spraying a PCB with automotive spray paint and using a water jet to remove the paint.   After removing the paint, the board is etched.  Electric pressure washers produce 1800 psi.  Hypodermic needles are available in .004".  Do you think there would be enough pressure out of a .004" opening to remove the coating on the board?

Jeff

It seems like Dykem metal marking fluid (aka Machinist's Bluing or layout fluid) would be a better coating as it is meant to be scratched off without coming off in big flakes.

For those who don't know what it is, it is a laquer based blue or black paint in a spray or brush-on form. Painted on metal, then lines to cut and machine may be scratched in very accurately without scratching the metal itself.

This is beginning to sound a lot like the Scratch 'n Etch idea that John Kleinbauer came up with when the list was young.

Here's the thread:
http://tech.groups.yahoo.com/group/Homebrew_PCBs/message/259

An early test by Brian Schmalz using Eagle PCB:
<http://tech.groups.yahoo.com/group/Homebrew_PCBs/files/Scratch_And_Etch/>

I did a few tests running an old HP plotter manually, I found it is very important to let the Dykem metal marking fluid dry completely to get a clean scratch line.

There are carbide scribers, and diamond-tipped scribers. This could be done with a very light-duty CNC machine or old flatbed paper/pen plotter. I dumped some lead shot into a pen with a carbide tip mounted in it to get enough pressure, it doesn't take much as the metal marking fluid is designed specifically so you don't have to press very hard.

Steve Greenfield AE7HD


--- In Homebrew_PCBs@yahoogroups.com, "Jeff" <jeff.heiss@...> wrote:

>
> To follow up on the "Electrical Discharge Machining plus painted board plus CNC x-y table" discussion,  I would like to suggest a similar idea.  What do you think of spraying a PCB with automotive spray paint and using a water jet to remove the paint.   After removing the paint, the board is etched.  Electric pressure washers produce 1800 psi.  Hypodermic needles are available in .004".  Do you think there would be enough pressure out of a .004" opening to remove the coating on the board?
> 
> Jeff
>

Given that waterjets are used to cut steel, I expect something like this is feasible ... but I have doubts that it is going to give very good results. Of course, you may prove me wrong!

--- In Homebrew_PCBs@yahoogroups.com, "Jeff" <jeff.heiss@...> wrote:

>
> To follow up on the "Electrical Discharge Machining plus painted board plus CNC x-y table" discussion,  I would like to suggest a similar idea.  What do you think of spraying a PCB with automotive spray paint and using a water jet to remove the paint.   After removing the paint, the board is etched.  Electric pressure washers produce 1800 psi.  Hypodermic needles are available in .004".  Do you think there would be enough pressure out of a .004" opening to remove the coating on the board?
> 
> Jeff
>

Andrew, indeed it might be something I might like to try.  Just curious why
do you think it would not give suitable results?

 

  _____  

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
On Behalf Of Andrew
Sent: Wednesday, January 12, 2011 6:56 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: [Homebrew_PCBs] Re: water jet and spray painted board

 

  

Given that waterjets are used to cut steel, I expect something like this is
feasible ... but I have doubts that it is going to give very good results.
Of course, you may prove me wrong!

--- In Homebrew_PCBs@yahoogroups.com
<mailto:Homebrew_PCBs%40yahoogroups.com> , "Jeff" <jeff.heiss@...> wrote:
>
> To follow up on the "Electrical Discharge Machining plus painted board
plus CNC x-y table" discussion, I would like to suggest a similar idea. What
do you think of spraying a PCB with automotive spray paint and using a water
jet to remove the paint. After removing the paint, the board is etched.
Electric pressure washers produce 1800 psi. Hypodermic needles are available
in .004". Do you think there would be enough pressure out of a .004" opening
to remove the coating on the board?
> 
> Jeff
>





[Non-text portions of this message have been removed]

There are three issues that I would guess would cause problems -- and this is only guessing, so take this for what it is worth:

1) Regulating the pressure and speed so that you erode paint/dye but not copper/board. Particularly on areas where you are eroding a block of paint/dye, I would wonder if the speed of erosion is different when there is paint/dye on each side, vs. only on one side of the line. Further, I would expect that it would require a different pressure or timing to start or stop a feature than to continue a line. How easy is it to control the pressure with some level of exactness?

2) Overspray/interference -- since you would not be cutting through the board, the water will be bouncing up off the board, right into the path of the water jet. My guess is that this "overspray" will degrade the resolution of the waterjet, making #1 even more difficult.

3) Electronics and mechanical systems in a wet environment would likely increase the difficulties of the design by an order of magnitude.

No doubt, with sufficient effort and expense, all of these problems could be overcome ... at which point you will have to "paint" the board and wait for it to dry. Then you will have wait a good bit of time for the waterjet process to actually produce the design on the board -- this is not going to be a fast process, and the time required will increase as the complexity of the board increases. And after all of that, you still have to etch the board.

Meanwhile, I can produce boards ready to etch in about 5 minutes using toner transfer, with 8/8 dimensions. If I needed finer dimensions, I would make the very small investment required to go with a UV-exposure process.


--- In Homebrew_PCBs@yahoogroups.com, "Jeff Heiss" <jeff.heiss@...> wrote:

>
> Andrew, indeed it might be something I might like to try.  Just curious why
> do you think it would not give suitable results?
> 
>  
> 
>   _____  
> 
> From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
> On Behalf Of Andrew
> Sent: Wednesday, January 12, 2011 6:56 PM
> To: Homebrew_PCBs@yahoogroups.com
> Subject: [Homebrew_PCBs] Re: water jet and spray painted board
> 
>  
> 
>   
> 
> Given that waterjets are used to cut steel, I expect something like this is
> feasible ... but I have doubts that it is going to give very good results.
> Of course, you may prove me wrong!
> 
> --- In Homebrew_PCBs@yahoogroups.com
> <mailto:Homebrew_PCBs%40yahoogroups.com> , "Jeff" <jeff.heiss@> wrote:
> >
> > To follow up on the "Electrical Discharge Machining plus painted board
> plus CNC x-y table" discussion, I would like to suggest a similar idea. What
> do you think of spraying a PCB with automotive spray paint and using a water
> jet to remove the paint. After removing the paint, the board is etched.
> Electric pressure washers produce 1800 psi. Hypodermic needles are available
> in .004". Do you think there would be enough pressure out of a .004" opening
> to remove the coating on the board?
> > 
> > Jeff
> >
> 
> 
> 
> 
> 
> [Non-text portions of this message have been removed]
>