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June 25, 2022, 05:48:27 17:48


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Author Topic: Best method of making PCB .. Toner tarnsfer or Photoresist or what .. help?  (Read 35108 times)
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vern
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« Reply #100 on: June 04, 2022, 01:47:51 13:47 »

you cannot really etch copper with a fiber laser, the absorbtion rate for copper at this this wavelength (around 1000nm) is about 8%, 92% of the incoming energy is reflected.
I have a 15W fiber laser, it works well with aluminum, steel, plastics etc, but with copper it doesn't work at all. It works well with the pcb-epoxy though, once you make it through the copper everything under it is burned immediately.
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kripton2035
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« Reply #101 on: June 04, 2022, 03:59:29 15:59 »

so all the movies on youtube showing a 20w fiber laser burning copper on a pcb are fake ?
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h0nk
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« Reply #102 on: June 04, 2022, 07:19:54 19:19 »

so all the movies on youtube showing a 20w fiber laser burning copper on a pcb are fake ?

Yes.
It needs a lot more power.


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Xwing
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« Reply #103 on: June 05, 2022, 07:54:14 07:54 »

so all the movies on youtube showing a 20w fiber laser burning copper on a pcb are fake ?

It depends, if the 20 W are the real optical power it is possible, if they are the laser input power it is not possible to engrave the copper for a pcb.
A real 20W out fiber laser requires over 80W input, costs no less than 4000-5000E.
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wild
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« Reply #104 on: June 05, 2022, 09:24:38 09:24 »

https://youtu.be/RudStbSApdE
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Wizpic
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« Reply #105 on: June 05, 2022, 09:33:17 21:33 »

I used to use chemicals tried all methods but messy so now Iíve got my own CNC machine which I use to make simple one off projects, the hardest part is the viaís on double sided boards, Iíve even got the correct tool with copper rivets which werenít cheap and it caught me out once trying to trace a fault which was caused by one of them so still ended up putting a blob of solder over them to make sure connections are good. This method is still time consuming  and soldering SMD parts between .4mm tracks without tracking can be tricky but good to prove your design if you wanted more then one off.
 But now I just use JLPCB fast service and good quality, just waiting for my last order which consist of 3 projects 10 boards for each one and only cost me 35gbp including postage. When Iím working on a project thereís no rush or deadline to meet.

So for me now days get them sourced out not worth the hassle or mess with chemicals
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vern
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« Reply #106 on: June 06, 2022, 06:11:35 18:11 »

Quote
It depends, if the 20 W are the real optical power it is possible, if they are the laser input power it is not possible to engrave the copper for a pcb.
A real 20W out fiber laser requires over 80W input, costs no less than 4000-5000E.

as I mentioned in my post I have a 15W fiber laser, and that is of course optical output power. Laser specs are always output power, never input.
And my 15W laser does almost nothing on copper.
I can imagine a fiber laser with a lower wavelength would be good, but I don't think you can get one of those for $5000
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kripton2035
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« Reply #107 on: June 07, 2022, 07:26:36 07:26 »

on a fiber laser, it seems that the lens size must be paires with the laser power
a 20W laser needs a 100mmx100mm working area (= lens foical) for enough power
a 30W laser can go with a 200mm lens
if you have a 15W laser and a 300mm lens it could be normal that nothing happens on copper ?

ps: as I dont have (yet) a fiber laser, these are only thought I have after surfing on the subject for some times ...
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vern
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« Reply #108 on: June 09, 2022, 11:46:46 11:46 »

no, the lens diameter has nothing to do with the laser power, it only defines the scan area.
The laser beam is only several mm, it doesn't matter how big the lens is.
My laser has a 75mm diameter lens, focal lenght is about 180mm.

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LithiumOverdosE
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« Reply #109 on: June 09, 2022, 08:17:48 20:17 »


Yup. I've played a bit on 6K resolution SLA printer and the results seem promising.
Considering that cost of hi-res SLA printers are dropping significantly I suppose that one could even gut two printers to make a "sandwich" and expose double sided PCB at once.

The only downside is that at this point one has to convert PCB layout to .stl files in order to use original SLA printer hardware.
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CocaCola
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« Reply #110 on: June 10, 2022, 09:06:48 09:06 »

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The only downside is that at this point one has to convert PCB layout to .stl files in order to use original SLA printer hardware.

Seems like that would be a great export addition to consumer layout software, or even better would be if someone wrote a stand-alone gerber to .stl converter for just this purpose, that is if this technique takes off and I can certainly see the potential for this to take off...  I could even see spin-off PCB exposing machines made for the purpose, if all you need is the LCD screen, UV lights, and a plate of glass in a box with minimal software to run the LCD and UV lights vs the extra motion hardware/software in the printer it would significantly cut cost of a purpose made machine...  Even 8K LCDs are affordable nowadays...
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mars01
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« Reply #111 on: June 10, 2022, 03:52:34 15:52 »

In my case I need to make PCB's that sometime might be as big as an A4 sheet so the current 6K or 8K SLA printers with such a size are still way too expensive.
But the use of a SLA printer made me think if it will not be an idea to buy a high resolution 13" or 14" display, take the light source away and replace it with UV LED strips.

Unfortunately I see two issues:
- one is that the glass of the screen might be made specifically to block UV radiation which is harmful. Might be.... although the white LED's are not supposed to emit UV, so who knows if the glass is truly blocking the UV light
- second is that when displaying the white on the LCD there are actually sub-pixels involved (R,G,B) and that might create some issues. On the other hand the photosensitive film do polymerize in vicinity of the exposed area, not much but it does, so for high density displays it might just work. 
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CocaCola
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« Reply #112 on: June 10, 2022, 11:14:42 23:14 »

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- second is that when displaying the white on the LCD there are actually sub-pixels involved (R,G,B) and that might create some issues. On the other hand the photosensitive film do polymerize in vicinity of the exposed area, not much but it does, so for high density displays it might just work. 

That is why most of these printers have now moved to monochrome LCDs...

The biggest issue as you get bigger displays is the pixel size, even at 8K a 13" screen likely isn't going to be a small enough pixel size to get high enough resolution...

Quote
- one is that the glass of the screen might be made specifically to block UV radiation which is harmful. Might be.... although the white LED's are not supposed to emit UV, so who knows if the glass is truly blocking the UV light

To try this I would remove the actual LCD, use regular plate glass, thinner the better and a proper UV backlight.
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kreutz
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« Reply #113 on: June 10, 2022, 11:24:35 23:24 »

No all of the models use a glass over the LCD screen that is why, so far, resin vat leakage most often requires LCD display replacement. The printers are made to transmit as much UV light  as possible to the resin vat, so no UV light blocking material is used in the light path. The plastic cover and a safety switch are supposed to protect the user's eyes but, most importantly, the user's common sense should be required for safety (not to bypass the cover switch for example)
« Last Edit: June 11, 2022, 06:07:43 06:07 by kreutz » Logged
CocaCola
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« Reply #114 on: June 11, 2022, 09:02:54 09:02 »

The plastic cover and a safety switch are supposed to protect the user's eyes but, most importantly, the user's common sense should be required for safety (not to bypass the cover switch for example)

The 405nm reflector-based UV used in most consumer DLP printers, is arguably no more harmful than sunlight unless you are some dolt that is staring straight into it for extended periods of time.  I'm not advocating disabling the cover switch and running without, as the cover also provides dust protection, but running a consumer DLP resin printer less cover is not all that dangerous...  The commercial SLA printers running 355nm lasers are of course much more dangerous as it's highly focused more damaging wavelength, assuming it was directed at your eyes...

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LithiumOverdosE
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« Reply #115 on: June 11, 2022, 12:14:02 12:14 »

It seems that one can buy relatively cheap 8.9 inch 4K mono screen with HDMI input.
In that case no gerber to stl conversion would be required.
https://www.aliexpress.com/item/1005003493405410.html

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CocaCola
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« Reply #116 on: June 13, 2022, 11:55:33 23:55 »

It seems that one can buy relatively cheap 8.9 inch 4K mono screen with HDMI input.
In that case no gerber to stl conversion would be required.
https://www.aliexpress.com/item/1005003493405410.html

I wonder how much of a nightmare scaling would be over HMDI to that display across devices...
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kreutz
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« Reply #117 on: June 14, 2022, 01:09:18 13:09 »

Check the specs of the mono display, you want very high contrast ratio. Check also that the Hdmi to MIPI adapter has been programmed for that particular display. The initialization of the MIPI displays is not a standard and the chosen controller has to be programmed to initialize them.
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mars01
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« Reply #118 on: June 14, 2022, 09:23:23 21:23 »

I wonder how much of a nightmare scaling would be over HMDI to that display across devices...

Nothing that cannot be calibrated with a few iterations. Sprint Layout can, for example, scale on X and Y axis a Gerber so it can adjust the print result therefore making it useful for compensation of such LCD presenting scaling errors.
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Parmin
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« Reply #119 on: June 16, 2022, 02:58:42 02:58 »

I can definitely testify that fiber laser can make PCB easily.
On my 20W machine I have etched out copper many times and all is good.

The lens focal length definitely have effect on the power transmitted.
With 50mm focal length, I can even cut the boards (very stinky fumes) to odd shapes if required.
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