I have to make some dirt cheap boards. I can
lay them out single-sided. But, need to be able
to mill/route the outlines to relatively complex
shapes (e.g., donuts, concave curves, etc.)

One approach is to laser cut the boards -- if the
material chosen isn't too "robust" -- instead of
having the boardhouse deal with this.

The boards don't have to be particularly sturdy as
they will be supported completely by their undersides.

What sort of material might be suitable for this?

[I'm only looking for small quantities -- hundreds.
I'll let someone else refine the process for bigger
quantities (with commensurate investments]

Don Y <blockedofcourse@foo.invalid> wrote:
> I have to make some dirt cheap boards. I can
> lay them out single-sided. But, need to be able
> to mill/route the outlines to relatively complex
> shapes (e.g., donuts, concave curves, etc.)
>
> One approach is to laser cut the boards -- if the
> material chosen isn't too "robust" -- instead of
> having the boardhouse deal with this.
>
> The boards don't have to be particularly sturdy as
> they will be supported completely by their undersides.
>
> What sort of material might be suitable for this?
>
> [I'm only looking for small quantities -- hundreds.
> I'll let someone else refine the process for bigger
> quantities (with commensurate investments]
>
>

We’ve used Dirty PCBs for stuff like that in the long-ago time.

https://dirtypcbs.com

Dunno if they’ve gone too far upmarket since.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC /
Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics

mandag den 14. august 2023 kl. 16.35.38 UTC+2 skrev Don Y:
> I have to make some dirt cheap boards. I can
> lay them out single-sided. But, need to be able
> to mill/route the outlines to relatively complex
> shapes (e.g., donuts, concave curves, etc.)
>
> One approach is to laser cut the boards -- if the
> material chosen isn't too "robust" -- instead of
> having the boardhouse deal with this.
>
> The boards don't have to be particularly sturdy as
> they will be supported completely by their undersides.
>
> What sort of material might be suitable for this?
>
> [I'm only looking for small quantities -- hundreds.
> I'll let someone else refine the process for bigger
> quantities (with commensurate investments]

upload some gerbers to jlcpcb, I suspect shipping will be more that a 100 boards

On 2023-08-14, Don Y <blockedofcourse@foo.invalid> wrote:
> I have to make some dirt cheap boards. I can
> lay them out single-sided. But, need to be able
> to mill/route the outlines to relatively complex
> shapes (e.g., donuts, concave curves, etc.)
>
> One approach is to laser cut the boards -- if the
> material chosen isn't too "robust" -- instead of
> having the boardhouse deal with this.
>
> The boards don't have to be particularly sturdy as
> they will be supported completely by their undersides.
>
> What sort of material might be suitable for this?
>
> [I'm only looking for small quantities -- hundreds.
> I'll let someone else refine the process for bigger
> quantities (with commensurate investments]

Any though hole parts?

--
Jasen.
🇺🇦 Слава Україні

On 14/08/2023 15:35, Don Y wrote:
> I have to make some dirt cheap boards.  I can
> lay them out single-sided.  But, need to be able
> to mill/route the outlines to relatively complex
> shapes (e.g., donuts, concave curves, etc.)
>
> One approach is to laser cut the boards -- if the
> material chosen isn't too "robust" -- instead of
> having the boardhouse deal with this.
>
> The boards don't have to be particularly sturdy as
> they will be supported completely by their undersides.
>
> What sort of material might be suitable for this?
>
> [I'm only looking for small quantities -- hundreds.
> I'll let someone else refine the process for bigger
> quantities (with commensurate investments]

I used some thin single-sided FR4 once, IIRC 0.4mm but it may have been
less. It was thin enough to cut with scissors, which we did.

--
Cheers
Clive

On 8/15/2023 5:21 AM, Clive Arthur wrote:

>> What sort of material might be suitable for this?
>>
>> [I'm only looking for small quantities -- hundreds.
>> I'll let someone else refine the process for bigger
>> quantities (with commensurate investments]
>
> I used some thin single-sided FR4 once, IIRC 0.4mm but it may have been less.
> It was thin enough to cut with scissors, which we did.

Excellent. I am assuming the ease of cutting won't affect the
price of having it done by the board fabricator; they see it
as another step in the process (and, possibly difficult depending
on the actual geometries of the outlines I choose).

OTOH, "thinner" means other techniques may be more appropriate
to cut it (though scissors would probably be too labor intensive
and inaccurate).

Thanks!

On 8/14/2023 10:50 PM, Jasen Betts wrote:
>> [I'm only looking for small quantities -- hundreds.
>> I'll let someone else refine the process for bigger
>> quantities (with commensurate investments]
>
> Any through hole parts?

No. *Possibly* a couple of registration holes.

On 8/14/2023 7:45 AM, Phil Hobbs wrote:
>> The boards don't have to be particularly sturdy as
>> they will be supported completely by their undersides.
>>
>> What sort of material might be suitable for this?
>>
>> [I'm only looking for small quantities -- hundreds.
>> I'll let someone else refine the process for bigger
>> quantities (with commensurate investments]
>
> We’ve used Dirty PCBs for stuff like that in the long-ago time.
>
> https://dirtypcbs.com
>
> Dunno if they’ve gone too far upmarket since.

"Stuff like that" meaning "dirt cheap", "flimsy"? Or, "unusual outlines"?

On Tuesday, 15 August 2023 at 15:08:58 UTC+1, Don Y wrote:
> On 8/14/2023 10:50 PM, Jasen Betts wrote:
> >> [I'm only looking for small quantities -- hundreds.
> >> I'll let someone else refine the process for bigger
> >> quantities (with commensurate investments]
> >
> > Any through hole parts?
>
> No. *Possibly* a couple of registration holes.

Having complex external shapes in FR4 never seems to be a problem for
manufacturers, but some don't like large internal cutouts. Others are OK
with these. In one design I linked the internal cutout to the outside with a
2mm wide channel so that everything could be cut without lifting the router bit.

Some manufacturers will fit as many repetitions as possible onto one panel
for a fixed price. I recently had a small double-sided design with a complex routed
outline manufactured with about 190 repetitions on a single 130x210mm panel
for about GBP100 in total.
Here are the details for a larger single-sided panel.
https://www.pcbpanel.co.uk/panel-f-single-sided-conventional.html
You can probably do a lot better in China, especially if you use resin
bonded paper.
John

On 8/14/2023 8:12 AM, Lasse Langwadt Christensen wrote:
> mandag den 14. august 2023 kl. 16.35.38 UTC+2 skrev Don Y:
>> I have to make some dirt cheap boards. I can
>> lay them out single-sided. But, need to be able
>> to mill/route the outlines to relatively complex
>> shapes (e.g., donuts, concave curves, etc.)
>>
>> One approach is to laser cut the boards -- if the
>> material chosen isn't too "robust" -- instead of
>> having the boardhouse deal with this.
>>
>> The boards don't have to be particularly sturdy as
>> they will be supported completely by their undersides.
>>
>> What sort of material might be suitable for this?
>>
>> [I'm only looking for small quantities -- hundreds.
>> I'll let someone else refine the process for bigger
>> quantities (with commensurate investments]
>
> upload some gerbers to jlcpcb, I suspect shipping will be more that a 100 boards

Yes, that's the only sure way to get hard numbers.

I would have prefered if folks would clearly state their
capabilities instead of trying to swat at them by
submitting different outlines and waiting to see
where the pain creeps in.

[I've had this problem when dealing with custom devices from
Japanese vendors; they want you to tell them what you *want*
whereas most designers look at what things "cost" and adjust
their "wants", accordingly.]

Rectangular boards being the cheapest.

On 8/15/2023 7:27 AM, John Walliker wrote:
> Having complex external shapes in FR4 never seems to be a problem for

It's not a question of whether or not they can *do* it but, rather,
what the cost penalty is. I'm looking for *really* cheap.

> manufacturers, but some don't like large internal cutouts. Others are OK
> with these. In one design I linked the internal cutout to the outside with a
> 2mm wide channel so that everything could be cut without lifting the router bit.

(I'm trying to identify similar shapes that I can convey easily)

Imagine routing a board with the outline of the digit '8'.
Or, '2' (note the tight internal angle on the bottom right)
to keep eliminate the need to lift the tool to route an
internal void.

> Some manufacturers will fit as many repetitions as possible onto one panel
> for a fixed price.

Yes. Panelizing a nice regular shape is easier than something
more obscure. How tightly could you pack '2's onto a panel?
(That;s actually an interesting problem. I'll see what my
panelizing software comes up with for a solution... I wonder
how many options it explores?)

What's the minimum distance between to ensure you don't chip a
board edge? etc.

> I recently had a small double-sided design with a complex routed
> outline manufactured with about 190 repetitions on a single 130x210mm panel
> for about GBP100 in total.

Those would be tiny boards. I'm looking at an enclosing polygon
of maybe 100mm x 70mm (but, a fair bit of that being "space")

> Here are the details for a larger single-sided panel.
> https://www.pcbpanel.co.uk/panel-f-single-sided-conventional.html
> You can probably do a lot better in China, especially if you use resin
> bonded paper.

It might be better to populate and then cut. But, that limits
the houses that can do that. OTOH, it might afford better panelizing
options for the different boards (on a single panel).

On 2023-08-15 10:11, Don Y wrote:> On 8/14/2023 7:45 AM, Phil Hobbs wrote:
>>> The boards don't have to be particularly sturdy as
>>> they will be supported completely by their undersides.
>>>
>>> What sort of material might be suitable for this?
>>>
>>> [I'm only looking for small quantities -- hundreds.
>>> I'll let someone else refine the process for bigger
>>> quantities (with commensurate investments]
>>
>> We’ve used Dirty PCBs for stuff like that in the long-ago time.
>>
>> https://dirtypcbs.com
>>
>> Dunno if they’ve gone too far upmarket since.
>
> "Stuff like that" meaning "dirt cheap", "flimsy"? Or, "unusual
outlines"?
>
>
Dirt cheap, solder mask and silk screen optional, PTH also optional. We
built some breakout boards for prototyping.

(Small rectangular pads on a grid of 0.5 x 0.65 mm are super useful too.)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

On 2023-08-15, Don Y <blockedofcourse@foo.invalid> wrote:
> On 8/14/2023 10:50 PM, Jasen Betts wrote:
>>> [I'm only looking for small quantities -- hundreds.
>>> I'll let someone else refine the process for bigger
>>> quantities (with commensurate investments]
>>
>> Any through hole parts?
>
> No. *Possibly* a couple of registration holes.

perhaps thin phenolic paper or polyimide, it can be cut using blade in a
press, laser or water jet etc... or scissors for prototypes.

--
Jasen.
🇺🇦 Слава Україні

On 8/15/2023 11:54 PM, Jasen Betts wrote:
> On 2023-08-15, Don Y <blockedofcourse@foo.invalid> wrote:
>> On 8/14/2023 10:50 PM, Jasen Betts wrote:
>>>> [I'm only looking for small quantities -- hundreds.
>>>> I'll let someone else refine the process for bigger
>>>> quantities (with commensurate investments]
>>>
>>> Any through hole parts?
>>
>> No. *Possibly* a couple of registration holes.
>
> perhaps thin phenolic paper or polyimide, it can be cut using blade in a
> press, laser or water jet etc... or scissors for prototypes.

Thanks! I will see if I can find a house that has it available.

Perhaps (in production) a die can be created to just stamp out the
blanks prior to stuffing...