Circuit Boards ??

[Bob Rath]

Someone asked me today whether or not it was possible to cut circuit boards on a laser. This is a hobbyist who wants one-off boards for prototype/experimental purposes. I don't know what the actual board is made of (PVC type matl??) or whether a 45w laser could make a dent in the very thin copper cladding that is on the board. Does anyone know anything about this type of application? If it is physically possible, I wonder whether the file format that I'm given can be lasered. (Hairlines etc??)
Thanx for any help you can give me.

[Kim Vellore]

it is not possible to cut them clean, they are made of FR-2 (Phenolic cotton paper), FR-3 (Cotton paper and epoxy) or FR-4 (Woven glass and epoxy). they all burn and chars like crazy. Copper cannot be cut either. I have been trying to engrave the copper side after painting so i can etch, the quality has been poor because of residues left after rastering.
Kim

[Bill Cunningham]

Yup! if you search using circuit boards as keywords, you will probably find a dozen others that have asked this very question.. It would be great if it would etch the copper off but nope!! You could always mask it, laser through the mask, and sandblast it off.. or just lacquer it, laser through the lacquer/paint, and etch it off with the usual ferric chloride..

[Rodne Gold]

You can use mild houshold abraisive cream like handy andy to remove the paint residues after laser engraving the resist to get to bare copper ..rub it on the laser ablated board with your fingertips or use a very soft toothbrush/brush - wash and etch.

[Kim Vellore]

You can use mild houshold abraisive cream like handy andy to remove the paint residues after laser engraving the resist to get to bare copper ..rub it on the laser ablated board with your fingertips or use a very soft toothbrush/brush - wash and etch.

Thanks Rodne,
I have been thinking only solvents for cleaning, I'll try different non solvents like soaps and light abrasives, I am sure that should work.

Kim

[Mark Winlund]

You also might try a very light sandblasting after lasering off the paint. The airbrush makers sell a pen type of sand blaster and the fine sand to go with it. It should remove all of the residual traces of paint and leave a good surface for etching.

Mark

[Richard Rumancik]

Or you could substitute baking soda for sand. It is often used for very gentle abrasion. It's a fine line between removing the residue and damaging the mask.

[Mark Ross]

Yes it is possible. IF you want to buy task specific machinery. Check out http://www.lpkf.com/

With a standard laser? Won't even put a dent in the copper.

[Rob Young]

Yes it is possible. IF you want to buy task specific machinery. Check out http://www.lpkf.com/

With a standard laser? Won't even put a dent in the copper.

+1 Cool equipment. I don't have one of their laser systems but I do have one of the older ProtoMat mechanical systems. Works great!

[Rob Young]

Someone asked me today whether or not it was possible to cut circuit boards on a laser. This is a hobbyist who wants one-off boards for prototype/experimental purposes. I don't know what the actual board is made of (PVC type matl??) or whether a 45w laser could make a dent in the very thin copper cladding that is on the board. Does anyone know anything about this type of application? If it is physically possible, I wonder whether the file format that I'm given can be lasered. (Hairlines etc??)
Thanx for any help you can give me.

If you could do it (which you probably can't, not enough power or proper wavelength to ablade copper), the usual format is "Gerber 274-x" for the layers and Excellon for the drill patterns. These are usually just know as the "Gerber files and drill tape". Gerber 274 and 274-x are vector based, ASCII readable files. The biggest difference between them, the -X includes the shape with which you are to draw the vectors. The older 274 version required a "wheel file" or "aperture file" to separately specify the shape. This file gave the shapes to be put into the aperture wheel of a photo plotter which would zip along over the board and expose the resist through the various openings on the wheel.

There are lots of places that will chemically etch, mechanically drill then plate 2 layer boards quite cheaply. Here are three:

barebonespcb.com
apcircuits.com
sierraprotoexpress.com

And they offer more advanced services too. Just the fact that they will plate through the holes for vias and leads makes these prototype boards much, much better value than stuff you do by hand. I use them as well as a LPKF ProtoMat which can do things quickly but I don't have the ability to plate the holes which adds complexity when assembling the prototypes.

[Dan Hintz]

Rob,

Search for through-hole plating kits... there are several that are essentially copper ferrules. Stick ferrules through the hole, place onto special anvil, press... instant plated-through hole.

[Rob Young]

Rob,

Search for through-hole plating kits... there are several that are essentially copper ferrules. Stick ferrules through the hole, place onto special anvil, press... instant plated-through hole.

Yes, I'm quite familiar with those methods.

The up shot is the chemical/electrolysis kits are too expensive (equipment, materials, shop space, etc) and the ROI just isn't there for me. And the mechanical staked type require too large a hole to be viable for the size board we usually make with the LPKF. Most of the boards need to be the size of a postage stamp or smaller and are quite crowded. Allowing >42mil for a via just isn't a good use of space. Plus the little buggers need to be soldered anyway to assure long term electrical connection.

For the dozen or so boards per year that must have vias through to the back side I simply solder a wire (30 ga through a 20mil hole) top and bottom. Or if we happen to have leaded parts I arrange the routing to take advantage of the pin.

Otherwise we just build in the cost and time of having a board made elsewhere. The LPKF is really only used for making up wild-hare test boards or what we refer to as "booger boards" which are little circuit boards used to retrofit or repair larger boards, usually they get shaped like the part or parts they must replace (another benefit of the LPKF, I can make odd shapes at no extra cost except material). Lets us make a repair or upgrade in a single day instead of a 3 day turn (layout=day, fabricate=day, ship=day == 3 days). Lots of fun.

[Dan Hintz]

My boards usually use 15-18mil vias (don't want to pay for the smaller size) and SMT components almost exclusively, 6-8mil trace/space. I've designed 4 layer boards using 2 double-layer stackups manually glued together, but I never want to do THAT again. For my work, there's usually little problem with waiting a week for standard turn time from emailing the files to receiving the boards.