Laser cutter for stainless steel stencils

[olkipukki]

The market is flooding with different sort of laser cutters and I wonder if somebody here own one to make in-house stencils.

What is price and operation cost starts from for a reasonable cutter and how easy to operate/maintain it?
Is it worth hassle rather than outsource to PCB house?

Thanks

[IconicPCB]

conventional CO2 laser will not touch stainless steel unless...

There is a surface treatment for stainlesss steel whihc will allow the CO2 laser to mark / cut stainless steel. The treatment is a spray pack of some black concoction. Itis sprayed on and when cutting completed it is removed.

Costs an arm and a leg.

A more apropriate laser source capable of cutting stainless steel is a fibre laser source..
A laser cut stencil cut locally in Brisbane willset you back at least a few hundred dollars. Owning and operating one.s own laser cutter might be economicaly viable under these costs. Asian sources will cut a stencil for a quarter of the price, With freight it works out at half the local cost. OK if planing in advance of a project, Otherwise local next day delivery may be essential.

[rx8pilot]

I have never seen a 'low cost' laser that can cut stainless sheet. It takes a lot of power, excellent optics, and a specific wavelength to accomplish that.

[olkipukki]

In Europe, a bit more than a week of waiting and you can get a spencil for $50, for extra 25/30% - just few days door-to-door

Any hint on a starting price for a decent cutter?

[IconicPCB]

30Wattfiber laser will cut stencil happily.
A 30 watt reasonable chinese fiber laser source a few thousand dollars.
On top of that optics and movement.

[IconicPCB]

See Raycus fiber laser.

[rx8pilot]

I have a 45W CO2 Epilog laser that won't touch metal. I can use Cermark to mark the metal but that is it.

[Fred27]

A hobby CO2 laser can cut mylar solder paste stencils. As rx8pilot states, it won't make any impact on metals.

[MagicSmoker]

The market is flooding with different sort of laser cutters and I wonder if somebody here own one to make in-house stencils.

Near infrared is supposed to be best for cutting stainless steel, so that means Nd:YAG and fiber lasers, which tend to be really expensive.

BUT... kapton (polyimide) and mylar (polyester) both make very good stencils that can be used 100+ times and which can be cut with a cheap 30-60W sealed-tube CO2 laser. Epilog is one popular manufacturer of lasers that are good for this application, but there are others.

That said, it probably isn't economical to cut your own stencils unless you are designing dozens of boards per year OR you are willing to pay a huge premium to get a stencil immediately, but since a stencil isn't worth much without a board, you would also need to have rapid board prototyping capability as well... All in all, it's probably best to get stencils made by, e.g., http://ohararp.com/stencils/ (no affiliation, just a satisfied customer of their kapton stencils).

[olkipukki]

What is mean "really expensive" - are we talking 6 digits (and plus) or...
as mentioned by @blueskull a cheapest starts from $15K, so $25-$30K will take us closer to a decent?

Actually, I never tried kapton and mylar stencils (basically, any non-stainless steel). Would be okay for 0402 parts and similar?
Not sure if I need this since $40-$50 will get me one from EU supplier (more or less as Chinese cost if include all taxes, risks, duties and shipping).

How difficult to use and maintain a cutter? Are there a lot of changes and overhead (setup type, gerber-to-what-ever-cutter-accepted-format converting) to fit into an existing workflow?
As today, I generate a fabrication output and send these to a PCB manufacturier(-ies).

[MagicSmoker]

...Actually, I never tried kapton and mylar stencils (basically, any non-stainless steel). Would be okay for 0402 parts and similar?

I've used kapton stencils for the initial prototypes of boards that had 0.65mm pitch QFP packages on them and the paste printed fine. I suspect going down to 0.5mm pitch would be risky, though. 0402 passives should be fine, too, but I never use anything smaller than 0603 so can't speak from experience.

[DerekG]

The market is flooding with different sort of laser cutters and I wonder if somebody here own one to make in-house stencils.

I'm not sure how many you need to make but PCBWAY will supply you panelised stainless steel stencils for about US$40ea.

[jpanhalt]

Why does it have to be laser?  Why does it have to be stainless steel (which alloy?)

I am always reluctant to make a suggestion when someone with a problem tries to define the solution -- assuming of course that there must be good reasons behind that.   Why not etch or reverse electroplate the metal template?   Have you considered copper or even (maybe better) nickel instead of SS?  After all, if etching gives you the resolution you need for the PCB, why won't it give sufficient resolution for the template?

John

[DerekG]

Why does it have to be laser?

It doesn't have to be laser cut, but the stencil shops are set up for this as it quick & accurate.

Why does it have to be stainless steel (which alloy?)

Stainless steel is generally used these days as it is very hard & lasts a long time. I actually prefer brass screens as they are easier to handle .......... but brass is not so common these days. Brass will still manage a few hundred thousand operations (if they are looked after) before they need replacing.

[IconicPCB]

I sometimes mill a stencil in double sided FR4 material ( 0.2mm thick ) as used in multilayer core production.
Would not use it on 0603 or finer pitch designs.

[DerekG]

I sometimes mill a stencil in double sided FR4 material ( 0.2mm thick ) as used in multilayer core production.

Yes, good thinking. We do most of our stencils in 0.2mm to ensure enough solder paste gets laid down on the board for reliability in automotive/vibration environments.

[mikeselectricstuff]

One possible route to low-cost metal stencils is photochemical etching - some commercial stencils are done this way.
You still have quite a lot of process optimisation to get it right though.

[awallin]

check this... plastic fantastic stencil with chinesium 40W co2 cutter

[richardlawson1489]

Here is a reference for you, which may help you to find the Laser cutter. http://hackaday.com/2015/04/03/cutting-smt-stencils-with-a-laser/

[D3f1ant]

So does anybody know what the cheapest laser machine is that will cut stainless stencils?

[Smallsmt]

I don't know if it's cheap but GCC has good quality machines.

Please look at
http://www.gccworld.com/goods.php?act=view&no=22

[Spikee]

Stainless steel stencils are soo cheap from china that seems crazy to invest in such machine.

~15-20 usd for ~30*30 frame-less stencil 0.1mm thickness (0402, BGA... all ok) , DHL/FEDEX/SF EXPRESS/EMS/Cheap china AIR  shipped within 36-72 hours.
With about 20USD shipping cost for DHL to most places. Can probably even do combine shipping if your pcb also come from china.

[D3f1ant]

It's not so much about the cost, its the time it takes to get a replacement when there is design flaws. 2 or 3 days is a very long time to have machine sitting idle.

[OSHStencils]

Thanks Blueskull, we do ship within 1 business day anywhere in the world and we utilize the best stencil cutting machine and metal on the market currently.

Our pricing is linear, and you only pay for what you need.  If you look on Twitter @OSHStencils you'll see lots of customer posted stencils, or our website in the gallery you will also see our product offerings.

[jmelson]

Yes, I make brass stencils form .003" brass shim stock, using the same technology for making PC boards.  I use Riston dry film resist, making a set of mirror-image artwork.  I glue the artwork in alignment, then slip the sensitized brass in between and expose and etch just like a PC board.
Works quite well.

Jon

[janekm]

BTW just the laser isn't enough to get good stainless steel stencils, there are post-processing steps too to remove the burr from the laser (otherwise the solderpaste won't release well). Usually electropolishing is used. You won't have much luck using an unpolished stencil for 0402 or QFNs (or smaller).
LPKF are probably the best-known brand for the CNC laser setups for cutting the stainless steel stencils, and the better Chinese factories use their machines (there are also some good Japanese ones).

So much like for making PCBs, it's a messy and expensive enough process that it's best left to a factory that do it day in day out and can reduce the costs to a minimum. You can just order the stencil at the same time as the PCB...

[DigitalDeath]

I use a LPKF mill to mill 5 mil brass. They have 10 mil and 4 mill diameter end mill bits so you can make any size. Here's an example with several different footprints.
You can get used LPKF mills pretty cheap on ebay and on top of that it allows you to make pcb prototypes.
I would assume you can use pretty much any cheap chinese router engraver with these bits and make a similar one.

[mikeselectricstuff]

I use a LPKF mill to mill 5 mil brass. They have 10 mil and 4 mill diameter end mill bits so you can make any size. Here's an example with several different footprints.
You can get used LPKF mills pretty cheap on ebay and on top of that it allows you to make pcb prototypes.
I would assume you can use pretty much any cheap chinese router engraver with these bits and make a similar one.

How do you keep the material flat while milling?

[DigitalDeath]

LPKF mills have a "ring" around the mill that rests on the PCB while they mill. The depth of the cut is adjusted by how much the end mill protrudes from this ring. This head and ring are held down by a solenoid while the head is down.

[IconicPCB]

What spindle speed and lineal feed rate do you cut at?

[rx8pilot]

LPKF mills have a "ring" around the mill that rests on the PCB while they mill. The depth of the cut is adjusted by how much the end mill protrudes from this ring. This head and ring are held down by a solenoid while the head is down.

That is the only practical way to do the job with any hope of accuracy.

[janekm]

LPKF mills have a "ring" around the mill that rests on the PCB while they mill. The depth of the cut is adjusted by how much the end mill protrudes from this ring. This head and ring are held down by a solenoid while the head is down.

That is the only practical way to do the job with any hope of accuracy.

Auto-levelling using a contact probe is also pretty effective, and arguably has some advantages: (and can be done on a much cheaper machine...)

[DigitalDeath]

@IconicPCB
For the 10 mil (0.25mm) end mil I'm using 52000 rpm and 5 mm/s speed.
For the 4 mil (0.1mm) I'm using 60000 and 4 mm/s speed.
BTW the end mills are shaped for PCB milling so they have pretty short flutes and transition into 1/8 inch shank pretty quickly as shown in the picture below.

@janekm
That software seems pretty cool. The only disadvantage that seems to me it would have is that you would need to secure the brass sheet to the base with double-sided tape or some other means such as vacuum. In the case of the LPKF that's not really an issue but then again you would need to get a used LPKF mill. I wonder if there is some gadget out there that does this same ring thing with a regular milling spindle. I bet it could be designed and made into a practical thing.

[janekm]

@janekm
That software seems pretty cool. The only disadvantage that seems to me it would have is that you would need to secure the brass sheet to the base with double-sided tape or some other means such as vacuum. In the case of the LPKF that's not really an issue but then again you would need to get a used LPKF mill. I wonder if there is some gadget out there that does this same ring thing with a regular milling spindle. I bet it could be designed and made into a practical thing.

Yes that's right, normally one would use double-sided tape but it's a bit of a pain to peel off if one was doing this every day. It's fine as an emergency method (which is what I think PCB milling is good for anyway  ).

[IconicPCB]

Digital,

I am familiar with LPKF tools. Excelent tools albeit pricey.

Tools from precise bits are much less expensive and equal to the LPKF.
I run the 10 thou ( 0.010" ) cutter for PCB work at 30KRPM and 1900mm/min on 1ounce copper ( 35 micron ). Another very interesting product Precise Bits have is cutting compound for copper.
I guess Your LPKF has the 60KRPM spindle. Very nice ...but try to find the mechanically sweet spot of he spindle where run-out of the spindle will not provide excessive resonance and "smear" of the tool tip path.

I run an Alfred Jaeger 100KRPM spindle but rarely push it above 50KRPM. Typically only when drilling 0.3mm holes .

[DigitalDeath]

Thanks for the tip on precisebits.com it's part of Think & Tinker from which I purchased a plating line. I had not realized they had end mills. I'll keep them in mind for future purchases.

[CopperCone]

what kind of laser would you need to cut the brass stencil?

[rx8pilot]

100mW cuts metal?

[mikeselectricstuff]

100mW cuts metal?

Avarage power of very short pulses - peak power is many kilowatts

[CopperCone]

How about carbon fiber?

[rx8pilot]

How about carbon fiber?

Interesting thought.....
In CF you have various forms, each with different cutting approaches available.

I have only seen raw CF and pre-preg cut with mechanical cutters. For cured CF, waterjet and mechanical works well.
I have never seen anyone cutting with laser. My guess is that the huge temp tolerance differential between the CF and the epoxy binders would make it difficult to do well.

[mrpackethead]

 I just bought a 300x400mm framed laser cut and electropolished stencil ex JLCPCB for $22.    They make them really nicely and the job is just fine.   They ship with my pcbs, and if you use LCSC.com for parts ( recommended ) they will ship them at the same time.    Not something to even contemplate making.

[CopperCone]

Is there any kind of metal that is a step up from plastic but still possible to cut with a cheap laser?

[rx8pilot]

Is there any kind of metal that is a step up from plastic but still possible to cut with a cheap laser?

I think physics rules the world on this......it takes money to cut metal with coherent light. I have never seen a 'cheap' laser create the wavelength and power necessary to cut metal.

[mikeselectricstuff]

If you really want to make your own metal stencils, photochemical etch is probably the only option.

[IconicPCB]

Copper Cone,

Under ordinary conditions a cheap CO2 laser will not touch stainless steel shim.

There is a spray on treatment for stainless steel which will allow a CW  co2 laser to mark the surface. I suppose repetitive ablation will eventually cut through, probably 20th pass.
I can not recall the name of the product but have seen it in use, a friend was making tattoo machines out of stainlees steel and used to decorate the machine frames by laser engraving the polished surfaces.

[1276-2449-1-ND]

Chinese fiber lasers that can cut thin stainless sheets are around $5K now.

I've been making stencils from mylar sheets on a CO2 laser cutter -- the trick is to ablate (etch), not cut away the mylar to get crisp edges with no bumps or burning.

When the laser was down and I needed some quick stencils I got a cheap craft vinyl cutter and it also made surprisingly useful stencils (the trick here is to overcut the corners so nothing dangles or leaves a little nub).

[mrpackethead]

got a link.

[mrpackethead]

I've been making stencils from mylar sheets on a CO2 laser cutter -- the trick is to ablate (etch), not cut away the mylar to get crisp edges with no bumps or burning.

I'm not familar with that technique?  How does it work? Is it like a raster scan or something?

[mikeselectricstuff]

I've been making stencils from mylar sheets on a CO2 laser cutter -- the trick is to ablate (etch), not cut away the mylar to get crisp edges with no bumps or burning.

I'm not familar with that technique?  How does it work? Is it like a raster scan or something?

Yes - you laser the whole area of the aperture rather than cutting round the edges.

[beanflying]

Chinese fiber lasers that can cut thin stainless sheets are around $5K now.

I've been making stencils from mylar sheets on a CO2 laser cutter -- the trick is to ablate (etch), not cut away the mylar to get crisp edges with no bumps or burning.

When the laser was down and I needed some quick stencils I got a cheap craft vinyl cutter and it also made surprisingly useful stencils (the trick here is to overcut the corners so nothing dangles or leaves a little nub).

Haven't got around to trying Mylar on my 40W yet but etching works well on light card and paper. I will run some tests on cut vs etch when I get some thin plastic loaded up.

Still amazed how often people ask can xyz small laser cut 'metal' even Google knows the answer to that one.