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Hack Chat Transcript Part 2

A event log for Flexible PCBs Hack Chat with OSH Park

PCBs, with more Flexibility

lutetiumLutetium 05/23/2019 at 20:040 Comments

oshpark12:22 PM
@Aaron_Kraus The substrate itself is spot-on 4.0 mils, which I've measured with a micrometer across multiple panel runs. The copper would likely be the largest variable, but should be with our stack-up specs https://docs.oshpark.com/services/flex/.

David Troetschel12:22 PM
Gotcha, I'll throw something together. I'm curious to see how hard it would be to weld a stack of surface contact flex PCBs. Our ultrasonic welder is pretty old but has a decent sized jaw. Based off of the spec sheet I doubt we would be able to join more than 2-3 double sided but that could allow for water resistance.

David Shuman joined  the room.12:23 PM

Aaron_Kraus12:24 PM
@oshpark @Dan Sheadel thx I missed that somehow :)

Vias work just as normal?

Maave12:24 PM
oh yeah, seconding the via question

Drew Fustini12:24 PM
@Bil Herd you might be interested in the RF filters that Darrell Harmon did on our Flex service https://twitter.com/HarmonInst/status/1102991659384528896

Dan Sheadel12:24 PM
@Aaron_Kraus Yep. The entire submission and design process is identical to normal rigid boards.

Drew Fustini12:25 PM

Nicolas Tremblay12:25 PM
@David Troetschel , wondering where you're going with this sounds cool.

Aaron_Kraus12:25 PM
O_o very nice

I guess you just answered all my questions for now

oshpark12:26 PM
@Aaron_Kraus Additionally, since the polyimide substrate is so uniform the interior plating tends to be very regular and smooth. Also, they're very short due to the thinness of the material, so a _little_ less resistance :)

Bil Herd12:26 PM
@Drew Fustini That kind of stuff makes me grin maniacally.

Michael Welling12:26 PM
is the a script available for generating spirals for inductors in kicad?

oshpark12:26 PM
As with any flexible design, ideally keep vias away from the portions of the board which you expect to be doing the maximum flexing.

Michael Welling12:26 PM
is *there

Frank Buss12:27 PM
you could create it in Inkscape, then use one of the KiCAD SVG importers

David Troetschel12:28 PM
@Michael Welling (good question)

oshpark12:28 PM
@Michael Welling I wrote one in Python for use on the butterfly and would like to try to adapt it to an Action script plugin soon.

Michael Welling12:28 PM
wondering if the process is documented some place?

Daren Schwenke12:28 PM
@oshpark I would love to see that code. Got it up somewhere?

Aaron_Kraus12:29 PM
@oshpark hmm on a *more or less* sphere the flexing should be uniform on the full pcb :p

so i should spread the vias uniformly as well?

oshpark12:29 PM
@Daren Schwenke Not yet! But after this Hack Chat I'll have motivation to do that sooner than later. :)

Kris Winer12:29 PM
Any plans for 4-layer flex service?

morgan12:30 PM
(could use right now)

Daren Schwenke12:30 PM
Oooo great question...

Bil Herd12:30 PM
General cost for 2 layer flex sq inch?

Dan Sheadel12:30 PM
@Aaron_Kraus Generally, you only need to care about vias around _sharp_ bends. If it's a gradual, gentle bend, there's not as much concern. There's a lot of really good whitepapers to cover various aspects of mechanical design.

Drew Fustini12:31 PM
I don't think so right now. We are looking to increase volume on the 2 layer flex to increase the speed that we fill the panel.

oshpark12:31 PM
@Bil Herd Right now it's $10/square-inch of design, and for that you get the usual 3 copies shipped for free anywhere.

Dan Sheadel12:31 PM
@Kris Winer No plans yet, but it's possible. Just as likely is the possibility we do 4 layer rigid flex, with 2 layers of flex sandwiched in 2 layers of rigid.

Frank Buss12:32 PM
@Michael Welling this should work: https://github.com/mtl/svg2mod

and spiral in Inkscape:

Kris Winer12:32 PM
Goal would be weight reduction for flight controllers and animal trackers...

Nicolas Tremblay12:32 PM
? @Dan Sheadel , what would be the point?

David Troetschel12:32 PM
@Kris Winer Yeah!

morgan12:32 PM
I'm iiiiin! https://hackaday.io/project/165714-sprite-wand

Bil Herd12:32 PM
Do you use the same fab house for flex as you do for rigid ? (Memory is it was GoldPhoenix)

NikiSchlifke12:33 PM
Are there any free or affordable tools that can help with "3D" or foldable designs?

Drew Fustini12:33 PM
All services are manufactured in the USA including the Flex

Bil Herd12:33 PM
Altium... oh wait, you said affordable.

Dan Sheadel12:33 PM
@Bil Herd We don't actually use GoldPhoenix, but yeah, the fab that makes our flex also makes some of our rigid boards.

David Troetschel12:34 PM
@Nicolas Tremblay lets just say I have a pretty bored cat....

Michael Welling12:34 PM
thanks @Frank Buss

Bil Herd12:34 PM
Lol.. I will avoid saying that then. :)

Maave12:34 PM
@NikiSchlifke like Pepakura Designer?

Aaron_Kraus12:34 PM
how is the production process works? Premade Kapton sheets with a layer of copper on top? and than laminate another kapton layer as soldermask?

Drew Fustini12:35 PM
Gold Phoenix was used by BatchPCB which OSH Park took over several years ago from SparkFun. All OSH Park orders are always fab'd in the U.S.

Dan Sheadel12:35 PM
@Nicolas Tremblay Rigid flex is super cool, in that you can have the benefits of both. Solid, fixed assembly points, and built in bendy wiring. You can basically fab a whole network of PCBs at once.

Frank Buss12:35 PM
@NikiSchlifke I really like FreeCAD, didn't try it in combination with KiCAD so far, but looks like it is possible:

http://kicad-pcb.org/external-tools/stepup/

Bil Herd12:35 PM
Advanced?

Bil Herd12:35 PM
That would explain the parity errors on the memory, thanks.

NikiSchlifke12:36 PM
@Maave yes!

Well could you incorporate that into a pcb design workflow?

Kris Winer12:36 PM
What kind of weight reduction could be achieved with rigid flex vs regular 4-layer rigid pcbs? 20%? 50%?

Nicolas Tremblay12:36 PM
@Dan Sheadel Now I get it. My mind is getting more blown minute by minute

Maave12:38 PM
I have no clue about using Pepakura with PCBs, I've only seen it used for craft projects

Dan Sheadel12:38 PM
@Kris Winer We'll get back on that one. We should be able to get Laen to weigh some QC boards to get a proper weight ratio.

Drew Fustini12:38 PM
@Aaron_Kraus it uses premade sheets of the polymide substrate with copper already applied. the soldermask is applied later with LPI process.

NikiSchlifke12:39 PM
@Maave I guess you could make the outline with it and use dxf/svg import to kicad

Dan Sheadel12:41 PM
Pepakura looks really perfect for doing flex designs. You'd certainly need to export and import it to generate gerbers for our process though.

Joe Miller joined  the room.12:43 PM

Aaron_Kraus12:43 PM
@Dan Sheadel Pepakura dragon with LED eyes and ... touch sensors to change eye colours?

Nicolas Tremblay12:44 PM
and copper scales

NikiSchlifke12:44 PM
Yeah Pepakura it is then :)

Maave12:44 PM
and nichrome artificial muscles

Aaron_Kraus12:45 PM
@Maave jup just what i thought about

flappy winged dragon XD

Dan Sheadel12:45 PM
:) Friendly reminder that there's always room in the Hackaday flex contest for a friendly flexy dragon.

Daren Schwenke12:45 PM
naw, coils and magnets..

Drew Fustini12:46 PM
There is still time to submit to the contest and there is good chance that all entries will get free 2 square inches on our flex service:

https://hackaday.io/contest/163267-flexible-pcb-concept-contest

Aaron_Kraus12:47 PM
@Dan Sheadel damn ... if I only had any spare time, apart from my other 500 side projects U_u

I'll see what I'm able to whipout in a short turn :)

Whats the deadline again?

oshpark12:47 PM
Since flex is laser-cut, the outlines can be more detailed than are normally achievable with a rotary milling bit used on rigid services.

Maave12:47 PM
deadline is wednesday!

ZigmundRat joined  the room.12:48 PM

Drew Fustini12:48 PM
the contest ends May 29th (next Wednesday)

Drew Fustini12:48 PM
You just need to submit a project idea. Not a finished project

Joe Miller12:48 PM
@NikiSchlifke Fusion360 has sheet metal mode, whereas you can create and work on any surface folded or unfolded. Also integrates with Eagle PCB, also free for non-comercial use.

Drew Fustini12:48 PM
this project used paper to prototype the design:

https://hackaday.io/project/165256-fitm-flex-in-the-middle-for-power-analysis

Orlando Hoilett12:48 PM
Will submit! @drew

Aaron_Kraus12:48 PM
@oshpark Seriously? you lasercut that after everything is done? How awesome is that?

Maave12:48 PM
I can't wait until HaD has a 1 Cubic Inch contest for flex PCB

Drew Fustini12:48 PM
gerat!

@Aaron_Kraus - remember, all the contest needs is an idea with some kind of documentation. Scribble a design down on a napkin even

Orlando Hoilett12:49 PM
Will submit @Drew Fustini

Maave12:49 PM
@Joe Miller nice thanks, I'm using Fusion 360 so I'll check that out

Daren Schwenke12:49 PM
1 'cubic' inch, aka, 20 bends of flex and components over an inch. :)

NikiSchlifke12:50 PM
@Joe Miller Wow, I haven't realized that, fusion360 really has everything I should have guessed.

oshpark12:50 PM
Flex is a LOT of fun! The contest is a great way to jump in and get your feet wet, and see first hand some of the wild and cool things that can be done with it.

Drew Fustini12:50 PM
Here is an interesting entry:

Möbius Flex https://hackaday.io/project/164528-mbius-flex


https://cdn.hackaday.io/images/145481554823951668.jpg

HACKADAY

morgan12:52 PM
neat! I was also thinkign of adding a modius

Michael Welling12:53 PM
hmmmm .. any good wearable examples?

Dan Sheadel12:53 PM
Sheet metal tools are really nice, since you can actually specify bend radii. It's really handy when you have to get the lengths done properly. Actually sticking to the bend you design is a different matter entirely.

Bil Herd12:53 PM
So flex is really only 2D then....

Nicolas Tremblay12:53 PM
2D in 3D space

Michael Welling12:54 PM
2.5D

Aaron_Kraus12:54 PM
i get that right?

2 inches sqare, would be a square just shy of 36mm edge length?

Bil Herd12:54 PM
Ah, a projection.

Drew Fustini12:54 PM
@Michael Welling here is a wearable idea https://hackaday.io/project/164262-flexible-diy-nike-fuelband


https://cdn.hackaday.io/images/9524541551948750100.png

HACKADAY

Drew Fustini12:55 PM
thanks Dan

Drew Fustini12:55 PM
and the ultimate wearable:

Cyborg Eyeball Project https://hackaday.io/project/164544-cyborg-eyeball-project

Michael Welling12:55 PM
cool, bobricius is quite industrious

Drew Fustini12:55 PM
though not sure if that is a good idea :)

oshpark12:55 PM
@Aaron_Kraus Correct.

Michael Welling12:55 PM
yikes!

Drew Fustini12:56 PM
interesting wearable concept to detect sign language

https://hackaday.io/project/165673-flex-type-and-sign

oshpark12:56 PM
The 2 square inches of design space can be used as a 1" x 2", or an ~36 mm square, etc.

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