Make PCBs with a Plotter

[balu]

Breadboards are great for prototypes and testing. In many cases I need more than this, but not a real PCB. My requirements are not so high. I need just single sided PCBs with a maximum dimension of approx. 3x4 Inch (80x100mm), because I use a free version of Eagle PCB Designer. I tested a lot of methodologies for homemade PCBs, but I’m looking for a simpler way – and make a find.

Plotting the PCB layout direct on a PCB

Two months ago I bought an old HP7440A plotter. My first step was to make an interface cable between my laptop and the plotter. The plotter has a DB-25 female connector for the RS-232 serial interface. I use a simple USB to RS-232 adapter with no flow control.
The Eagle PCB Designer provides the functionality to export layouts in hpgl and the plotter based on hpgl;-) But … I used a terminal program to send a hpgl-test-file to the plotter an I had a lot of problems:

1. The “no flow control” and plotting speed issue
 - I have to reduce the RS-232 speed down to 300 Baud, because the plotter has very small loss data buffer and will loss data
 - Sending hpgl command lines in max. 200 lines cluster to prevent loss of commands
 - I must reduce the plotter speed to 15 cm/s (approx.. 6 Inch/s) with the hpgl command VS15;
2. The plotter drawing pen issue
 - Selecting the right pen for PCBs – I use a Staedtler Permanent Lumocolor S (0.4mm, 0.016”) or F (0.6mm, 0,025”) – I use sodium persulfate for etching PCBs
 - Adapter for using the pen – I created with DesignSpark Mechanical a 3d model of the pen adapter and use my 3d printer to make the adapter

To reduce the effort of splitting hpgl files into 200-command-line-files and adapting the plotter speed I made a quick and dirty application with C#. The application load the hpgl-file, replace the SPn-Commands (SP: select pen) with VS15-Commands, remove all space characters and draw the layout in a graphic window with the sequence of hpgl commands. After connecting the plotter via RS-232/USB it is possible to plot the layout on a prepared PCB.

[tggzzz]

Potentially interesting.

Are there any closeups of etched PCBs, and are there any (informal) design rules about what is and isn't possible?

[Refrigerator]

I wonder if you could turn this into a micro CNC.

[SeanB]

Will not work as a CNC, as it really has no torque at all. It can just provide enough to move a pen on paper, not much more. Trying to get it to move against a milling cutter will be an exercise in futility and broken tips and boards.

[Kalvin]

I have always wanted to ask this: How about attaching a UV laser diode (with safe power level, of course) to the pen holder and "plotting" the pattern directly on the surface of the UV sensitive PCB? After that a quick development and etching.

[Richard Crowley]

I have always wanted to ask this: How about attaching a UV laser diode (with safe power level, of course) to the pen holder and "plotting" the pattern directly on the surface of the UV sensitive PCB? After that a quick development and etching.

http://youtu.be/4SNkzoOvoD8  (and several others)

[Kalvin]

I have always wanted to ask this: How about attaching a UV laser diode (with safe power level, of course) to the pen holder and "plotting" the pattern directly on the surface of the UV sensitive PCB? After that a quick development and etching.

http://youtu.be/4SNkzoOvoD8  (and several others)

Richard, thank you very much for the link. Few clicks away I found the answer to my question:

https://www.youtube.com/watch?feature=player_detailpage&v=rLQajSRnELc#t=308

Plotter and UV laser should work.

[tggzzz]

Plotter and UV laser should work.

Potentially extremely dangerous.

UV damages eyes; that's why sunglasses have UV specifications!

More importantly, much less than 100mW will instantly and permanently blind you - and it doesn't matter whether that is direct exposure or a reflection off of a metal (e.g. copper) or glass.

Now I really don't care if you blind yourself; that's merely evolution in action. But if you blinded an innocent third party passing by I would be extremely unhapppy. If you blinded me then I would commit suicide, since I am extremely deaf. But before that I would do everything in my power to ensure that you didn't pass your genes onto another generation. Seriously. Don't doubt it.

[Kalvin]

Plotter and UV laser should work.

Potentially extremely dangerous.

UV damages eyes; that's why sunglasses have UV specifications!

More importantly, much less than 100mW will instantly and permanently blind you - and it doesn't matter whether that is direct exposure or a reflection off of a metal (e.g. copper) or glass.

Now I really don't care if you blind yourself; that's merely evolution in action. But if you blinded an innocent third party passing by I would be extremely unhapppy. If you blinded me then I would commit suicide, since I am extremely deaf. But before that I would do everything in my power to ensure that you didn't pass your genes onto another generation. Seriously. Don't doubt it.

Safety first, I agree. I am always very worried too, when I see the videos on youtube where people are playing or experimenting with the lasers, and the system doesn't have the protective housing around it which would prevent accident from happening.

[dave_j_fan]

lovely servo based plotter :http://youtu.be/kcXlak7RNV0

[Cloud]

And I tough I am the only one who tried to do that  Can I get the file for the pen holder?

[balu]

I have made some examples. Just simple active BPFs, but made with SMDs and a layout with 0.4 mm (0.016 Inch) PCB tracks width. The result will fulfill my requirements. Because soldering of SMD parts with the size of 1206 and the pin spacing like SO8 is small enough for me. It is no problem to place a wire between the two resistor SMD pads.

I have attached the 3d model of the pen adapter as files in DesignSpark-Mechanical and STL file format.

I have no idea about the advantage of using a UV laser diode to create a PCB. After plotting the layout with the UV laser diode the PCB must be developed – this is one more step in the process to create a simple PCB. Possible advantage can be a more detailed and smaller structure – but I need just a simple prototype for my smallest parts with the size of 1206, SO8 etc. and this is no problem with this configuration.

[tggzzz]

Is it possible to post close-up photos of the naked PCB after etching, i.e. no components?  The current photos have the PCB obscured by components and we can't see the cuality of the tracks.

That would help us establish how well the etch resist works.

Thanks.

[pickle9000]

lovely servo based plotter :http://youtu.be/kcXlak7RNV0

That looks really well done.

[ivan747]

I am genuinely impressed by the guy who made the UV plotter. Yes, it is dangerous, but there are these things called protective covers. He managed to make 5 mil traces without a sweat! That's fab quality. Now we only need a CNC drill and a via insertion robot 

[ajb]

I have always wanted to ask this: How about attaching a UV laser diode (with safe power level, of course) to the pen holder and "plotting" the pattern directly on the surface of the UV sensitive PCB? After that a quick development and etching.

I was thinking the other day you could build a fully automated little PCB fabrication line this way.  Setup a gantry that holds the PCB vertically, and passes the PCB between a pair of horizontal carriages with opposing laser diodes.  The gantry then moves over and dips the PCB into a developer tank, then a rinse, then an etching tank, then a rinse, and voila, a double sided PCB ready for drilling.  The mechanics should be pretty simple since the required speeds and forces are low, and only three axes are required if both laser diodes are driven by the same motor, and the movable gantry can be wiggled to provide agitation during developing and etching.  With vertical tanks, you could do pretty good sized PCBs in a machine with the overall size about that of a 3d printer.

[tggzzz]

I am genuinely impressed by the guy who made the UV plotter. Yes, it is dangerous, but there are these things called protective covers.

Clearly the safety interlocks were completely ineffective!

The trouble with these thing is that it is always unclear whether the operator realised the danger of these devices. 40 years ago in an industrial lab they used to scare new employees by showing films (not a video!) of how high power lasers "interact" with primate faces.

Then there were signs everywhere saying things like "do not look at laser with remaining eye". I doubt there is much safety awareness/training supplied with something bought from a backsteeet shop

[JuKu]

I wonder how a conductive ink pen on a plain fiberglass board might work?

[balu]

Here is an example of using a UV laser diode to create PCBs. Sorry - the page in German language, but shows a lot of pictures and a video.  I think the price and size is ok.


http://www.insaneware.de/175mW-405nm-UV-Lasermodul-im-Lamellenkuehlkoerper-V3

I will post ASAP some pictures of plotted and etched PCBs only to show the quality.

[Fraser]

Thanks for a great Topic. I have two HP plotters that I used for printing the output of my spectrum analyser. I have not used them for ages. Maybe this is a new application for them ? You have saved me a lot of time and experimentation. 

Aurora

[eneuro]

Potentially extremely dangerous.
UV damages eyes; that's why sunglasses have UV specifications!

There is no need use UV laser in the environment where humans are 
I see only one way to play with UV lasers in DIY constructions-everything in closed black box, as well as laser diode itself with covers isolating from environment, when main box is not closed to prevent any  unexpected switch on of UV laser diode in the event of its circuit failure, etc.
Additionaly visual camera close to laser diode holder to be able monitor whole ploting process without any glasses, on laptop screen 

I think, that such UV laser tool can be additional tool for small pick&place SMD machine, where we still need visual camera to look in top view where position elements on PCB, so just by changing tool from vaccum pump to UV diode (protected mechanicaly when not used from emiting any UV whatever electronics do), could be really nice thing.
Using pens and classic ploter might work, but we quickly find it has many limitations, so probably small custom CNC where we could change tool to drill a few holes in manual mode just by inserting G-Code CNC code is worth to spend some time to do something like this.

I was thinking a while ago about using UV to plot PCBs directly and now its time to DIY such UV laser tool for custom PCB  machine 

[tggzzz]

Potentially extremely dangerous.
UV damages eyes; that's why sunglasses have UV specifications!

There is no need use UV laser in the environment where humans are 
I see only one way to play with UV lasers in DIY constructions-everything in closed black box, as well as laser diode itself with covers isolating from environment, when main box is not closed to prevent any  unexpected switch on of UV laser diode in the event of its circuit failure, etc.
Additionaly visual camera close to laser diode holder to be able monitor whole ploting process without any glasses, on laptop screen 

I think, that such UV laser tool can be additional tool for small pick&place SMD machine, where we still need visual camera to look in top view where position elements on PCB, so just by changing tool from vaccum pump to UV diode (protected mechanicaly when not used from emiting any UV whatever electronics do), could be really nice thing.
Using pens and classic ploter might work, but we quickly find it has many limitations, so probably small custom CNC where we could change tool to drill a few holes in manual mode just by inserting G-Code CNC code is worth to spend some time to do something like this.

I was thinking a while ago about using UV to plot PCBs directly and now its time to DIY such UV laser tool for custom PCB  machine 

Laser assemblies can be made safe, but many example photos and videos show very unsafe practices. IMNSHO any photo/video must have a written "health warning" stating what is necessary in order to use them safely.

Inexperienced people can and will watch the videos, and poorly duplicate what they see. They probably won't even realise the various dangers - until it is too late for them or someone else.

[JuKu]

I think, that such UV laser tool can be additional tool for small pick&place SMD machine, where we still need visual camera to look in top view where position elements on PCB, so just by changing tool from vaccum pump to UV diode (protected mechanicaly when not used from emiting any UV whatever electronics do), could be really nice thing.

- Unless the  alignment happens to be perfect: Ever seen what happens to a laser tube if it gets its own reflected beam back in, in phase? 

[Chris Jones]

Here is another way of using a laser to directly write on the photoresist:

[eneuro]

Inexperienced people can and will watch the videos, and poorly duplicate what they see. .

Do you have in 230VAC mains wall socket such warning messages, too? 
Nobody puts any metal parts into this socket-because everybody knows it could kill you.
if you make something for your own use and make it difficult to switch on by accident, label with danger laser logo marks, than everybody knows that we have to be carefull and look into user manual if we are not familar with such device.
There are many things that are dangers in everyday life, but if someone is not stupid, has a very big chance to survive...

BTW: Many people do not duplicate ideas published on youtube , but make it much better than shown in those videos, while has good understanding of physics