How To Design a FLEX PCB | Stackup & Rules | Example in Altium

[@pintarenator]

Hi Robert, I have the same version of altium 21.8.1 (updated yesterday), but I have a different stackup structure when i chose Rigid/Flex (and check the "Is flex" box). When i insert layers I have Bikini Coverlay instead Overlay. Stiffener option is nowhere to be found. Is this possible? Tnx, Tomaz

[@RobertFeranec]

I forgot, some time ago I enabled some Flex options in the System -> General -> Advanced preferences. Search there for flex, I have PCB.RigidFlex2.0 and PCB.RigidFlex.SubstackPlanning enabled there (Value is checked). Maybe that will help?

[@devangvyas9996]

@@RobertFeranec This fixed it. Thanks!

[@Alfie63071]

@@RobertFeranec Thank you Robert.

[@waleedsajidbaloch9523]

@@RobertFeranec i did not find any :( also when i arrange stackup in such a way that i have coverlay at the top and stiffner at bottom it gives me same color coding in 3D view

[@BraianBannert]

Hi Robert. It's really nice to see all the videos you share with the community. I tried what you mentioned in System -> General -> Advanced. The problem is, even I have them both checked and restarted the Altium application, it doesn't show any change and it's not possible to add Stiffener of Adhesive layers in the stackup. I'm using Altium 23.4.1 version. Thank you in advance

[@oregondude825]

Thanks Robert, informative as usual! I haven't done many flex boards so these comments are passed along from the fabricators I talked to. I would add that if you are looking for information on "best practices" talk to your fabricator - they are usually very happy to give input and provide up front support. They recommended placing an "anti-tear" feature in the radiused corners to help prevent tearing when the specific portions of the board are flexed. A piece of free copper is what was suggested, paralleling the radius of the corner. This helps prevent the traces in a corner from getting torn in the event the flex material starts to tear. It helps to redirect/prevent the tear from proceeding into the center of the radius. Another thing that was recommended was "ears" on the vias. Since the plating technique is different for flex boards (button plating) with flexing the vias can separate from the board. So copper pieces extending in 2 directions from the vias - opposite the trace entry side - was recommended to help adhesion for vias. The last thing I'll add is that they also strongly recommended tear drops on every pad/hole/pin. Especially adding teardrops on the traces where they meet the pins that plug into the connector. Not using teardrops allows for square corners which then become natural cracking/tearing points. By using a teardrop you effectively spread out the energies that would cause tearing. (this is one of the reasons you also use curves for corners on your traces) (I tried to attach images of each but this won't let me - I hope you follow the train of thought)

[@TheEmbeddedHobbyist]

It’s important to know where your pcb is going to bend as tracks on the inside travel a shorter distance than those on the outside of the radius. We used to use flexi pcbs to replace wiring looms, with normal tracks, screened tracks, and best of all twisted pair screens to cut the production costs. Solid copper layers on the top and bottom layers were cross hatched where they bent to reduce stress. As the pcb’s were made from Kapton which is hydroscopic it’s very important to bake the pcb to drive out moisture before soldering as it could blow the layers. Kapton was banned in a lot of new designs due to issues with moisture absorption and cable looms blowing apart in the event of a failure in one conductor.

[@markbutowski4487]

What did you use to replace the Kapton once it was banned?

[@TheEmbeddedHobbyist]

@@markbutowski4487 back to PTFE based coatings, but these can have issues. If the insulation is pulled as its cut it can slide back along the wire and expose the conductor. then I left the company.

[@Stabby666]

I had some flexible PCBs made by PCBWay for a wearable project, and the cross-hatched ground works well I found. Another thing I found was that you need to be careful with your reflow curve settings if you are using an oven, as there is no mass and so the PCB heats up much faster than standard FR4 PCBs. I had to make a special profile for these so that the flux did not boil off and create bunt components and bad solder joints.

[@bobby9568]

Never seen someone explain it this well!

[@xrtechinv]

Awesome. Literally the best tutorial I've ever seen on Flex pcb design.

[@hugopristauz3620]

Stunning tutorial! I'm going to design my first flex PCB, and this tutorial was the perfect intro. Thanks for your great work (slow and super clear explanations) 🙂

[@user-ee1ou2oe5h]

Hi Robert, will you please make a video on double layer complete flex without stiffener pcb in altium 22

[@thejunouyang]

Best vid for flex pcb hands down.

[@waynechen6797]

Best Altium Rigid-Flex lecture

[@RobertFeranec]

Thank you Wayne

[@DavisDanh]

thanks Sir, all information is very helpful

[@MaxWattage]

Thank you for this video, it is a most valuable resource. The only thing that jumped out at me as unusual about the flex-PCB design (in comparison to a normal PCB) was the sharp internal corners on the cutout regions. If Flex PCBs are milled like a normal PCB then they would need a 2mm radius on all internal corners. So, are your flex-PCBs going to be laser-cut or die-punched instead, due to their thinness? In general for flex-PCBs, at the connectors, a trace entering a pad forms a weak spot in which the copper might get fatigued over time. It is recommended to taper down the pads towards the end in which they are connected to the traces. Pads on flex-PCBs (e.g. vias) should have extra mechanical support to prevent detachment. This can come from copper anchors, an overlapping coverlay, and using teardrop shape pads. Apparently, if the flex PCB is multilayer, then the top and bottom traces should be staggered rather than vertically aligned.

[@RobertFeranec]

Thank you Nicholas. PS: About the corners ... we will see. The PCBs are on the way. I am also curious to see if they made any other adjustments.

[@jorgeistmo93]

Thank you so much Robert. This information is very useful for my first design of Flex PCB.

[@ziradlabs]

Robert I just downloaded AD22 and noticed that the Flex options is not enabled by default. Overall I am rating AD21/22 a big fail for Rigid / Flex. AD18 was super easy and intuitive. It is too bad Altium does not have this big item resolved.

[@myetis1990]

great job Robert:) as usual. So what is next : Flexible LCD on flexible board , make your own DIY galaxy Zfold :)) btw I would love to see a video about inspecting EMC EMI aspect of a board with Daniel Beeker from NXP. I think It would be serious teaching material for us.

[@psgarcha92]

3 months ago I needed to do this. Now you post this. Robert you are an absolute machine! love your content

[@vidur.vachan]

Hi Robert! Thank you so much for such a detailed and complete video on Flex PCB! you got a subscriber for life!! Kudos to you!!!

[@navkri1]

Hi Robert Feranec, Thanks alot for this very informative video !

[@666aron]

Thank you for this valuable video. I never used flex PCBs, mainly because for some reason it did not occur to me, but at some projects (quadro copter and portable ECG logger) my life would have been easier without all those bad cabling jobs. Looks like I have to brush up on some Flex PCB design too :).

[@linqiang5734]

Many thanks Robert, all information is very helpful, appreciated.

[@wickedprotos1937]

Perfectly timed for my needs!!!! I need to do some flex pcbs in the near future!

[@tahsindegirmenci5667]

Thank you for this video Robert.

[@CasualInventor]

Fantastic introduction to this topic. Thank you.

[@Pro_Amine]

Thank you about these information ❤️👍

[@artrock8175]

Great topic! I was hoping you'd cover this! Thank you for taking time to share your knowledge!

[@raymonda.koosha5824]

This was excellent! Thanks Robert

[@ziradlabs]

I see the Beta version enable for the Board view / Rigid-Flex. It is a little confusing from Altium on the Branch and how the Rigid-Flex is being displayed. I would really like to see all the stackups being used in one window. How many times have Altium changed Layer Stack manager GUI?

[@RobertFeranec]

Yes, they keep changing it - that is why it took me almost 3 years to make this video :D. I think, I started this project when ad 19 was released and at that time I found out it can't show in FLEX what I need, so I waited until they improved it ... and I guess they will keep updating it.

[@punchofart4743]

since you are not sure about 0.2mm thickness or 0.18mm thickness, can you please tell the thickness of FPC which came after manufacturing? Actually I am designing FPC and I need to know some stack up for it

[@jagadishk4513]

Hi, Can you do a tutorial on membrane switch design.

[@RobertFeranec]

If I have a project for it, I will.

[@aatifshah8476]

@@RobertFeranec u r very humble person & knowledgeable i wish one day i ll have such knowledge 🤗

[@kirkrichardson3943]

Dave has a great video on this that is available. Always great to see another from Robert too. kzbin.info/www/bejne/fmm7c3Wcq9iDoJI&feature=emb_logo

[@jagadishk4513]

I have seen Dave's video but he dosen't go through the tools he used for routing tactile switches or decal. I used inkscape, freecad back and forth for decal. But there are no videos that show all these aspects indetail.

[@CarstenGroen]

Very well described (as usual!) by you!

[@user-er8mq7kq8m]

Very good tutorial on Flex PCB. I have a question concerning mechanical layers M4 and M5 for Stiffener. After you create the mechanical layer pair (as seen at time 39:11), did you enter the information about stiffener manually or there is an automated way of doing it? Altium Designer has everything to create this automatically using region in "Board Planning Mode" and stackup information, I want to know if it can do it and how to. Thank you,

[@amirfoo6565]

Wow I have been waiting for it long time 🙏🙏🙏🙏🙏

[@waynechen6797]

Nice Lecture.

[@hieunguyenngoc3726]

nice video. why I do not see Place tab while on board planning mode

[@officialbro1420]

Sir, can you give information on how smt pick and place machines are programmed...

[@denilsonnicolau3224]

Great Video Very informative

[@jumadhaheri]

Very interesting project

[@Heisenverse]

Off topic - Hi robert, my post in beginner section of fedevel forum is stuck at waiting for approval from moderator. While editing the post it somehow got locked in spam. Can you please look and approve it.

[@RobertFeranec]

Heisen, please send email to [e-mail] and ask Marcela to enable your account on forum

[@mecatx]

I cannot get sound or captions.

[@andrealongobardi2084]

Great video Robert, thank you! It is not clear to my why you have to specify all the different stack ups when you have to generate the stiffeners and coverlay layers for the entire board. Couldn’t just use only the full stack up?

[@RobertFeranec]

Thank you Andrea. PS: I just wanted to see the PCB as it will look when finished. It helps with checking everything.

[@ahbushnell1]

Good Job. Should you put a radius on the ground plane at the flex point?

[@mksee7674]

Awesome, good job !

[@jagdish1990]

hi Robert while Generating Flexi Rigid GERBER output there are additional file getting created along with solder mask (GTS/GBS) , these are GTS1 and GBS1. which is having flexi coverlay mask data but it is consistent . Some solder mask data present in GTS file and some present in GTS1 . GTS should have rigid section solder mask data and GTS1 should have FLexi region mask data but problem is this is getting mixed at split line , can you suggest something

[@petrmoravek4846]

Hello Robert, I have one question that does not directly tie to the rigid-flex technology but I have noticed that you had to tackle the same issue in the design you have shown so I figured I'd try asking. My question is - How did you route the tracks in the FPC cable that has the 180-degree curve in the middle? I understand how to setup the local polar grid but even after multiple attempts with a similar flex shape I was not able to force the copper tracks to follow the grid and form a nice curved connection. In the end I had to manually insert arcs with the proper width and spacing to the appropriate layer and assign the nets by hand. I am curious if you did it the same way or whether there is another, simpler way of doing this. Thanks a lot!

[@RobertFeranec]

Hi Petr, when routing corners, I used arc corner (SHIFT+Spacebar couple of times) and it was working oki.

[@sarazia9730]

Hi Robert, thanks so much for the video!! I also don't have the option for a stiffener even though PCB.RigidFlex2.0 and PCB.RigidFlex.SubstackPlanning are enabled (it says they're actually enabled by default). Do you know if they've changed something in the past year or what I should do from here. Thanks again for the great series.

[@titanlabs]

Informative, thanks :)

[@4mho1]

I'm working on my first flex design in Altium, and this was very helpful. Thank you. I noticed that the connector specifies 0.3mm thickness in the ZIF region without coverlay. In the material selection you indicated 0.2mm thick FPC plus 0.1mm stiffener. It looks like the coverlay+adhesive is included in the 0.2mm FPC build up. In this case does the total stackup thickness in the ZIF area come up 50um short of 0.3mm?

[@RobertFeranec]

I have not created the follow up video yet, but I have received the PCBs and thickness looks oki (within the connector tolerance)

[@316728237]

HOW TO DO IMPEDANCE MATCHING IN FLEX PCB

[@aatifshah8476]

RF coil in mri machines used flex pcb ...

[@juanmism91]

Is it possible to create a flex stack for a single layer FPC? It seems to me Altium doesn't allow less than 2 layers....

[@NHL_B]

For some reasons when I click on features->Rigid/flex, nothing change and I don't know what to do. help?

[@guillep2k]

What about the little tabs for holding the different board together? What would be the equivalent of a v-score or mouse bites?

[@RobertFeranec]

In this my specific PCB I will just cut it out by scissors. Even if I would create a proper panel, it sill will be very flexible, so ... I would probably still use scissors. PS: The boards have arrived ... and they are woow! They look really good. I ordered the LEDs and I will try to make another video about them.

[@jeffreyyin]

When I click on Rigid/Flex, the insert layer options didn't change there is no adhesive or stiffener. I check system and everything is turned on. Does this happen to any one?

[@RobertFeranec]

Did not the pinned comment help?

[@punchofart4743]

is this stack up fine for FPCs that have components mounted on it too?

[@jyothishpkumar5542]

Hey robert. First thing.. thanks a lot man for your videos... I basically learned altium from your videos.. I am now designing flex PCBs but i cannot add adhesive or stiffner.. there are no option in the dropdown can you help me?

[@jyothishpkumar5542]

Hey Robert.. i went through the comment section and found your solution for the problem... After doing it and restarting altium it worked. It would be helpful for all people if you could make a comment and pin it on top.. so every new guy can see it.

[@christianaaroncunningham8200]

Hi Robert, This is a great video. But I'm very struggling with a problem. I can't see Board Mode of layer stack up even though I enabled Rigid-Flex option in Feature drop down menu. Also, I can't see Stiffener option. Could you please lead me? I tried altim21.6 and altium22. I installed offline version. Is it the cause?

[@Anonymous-ok9ul]

Hi Robert, Do you have any idea on how to create Metal-backed pcb boards of MCPCB, i have been banging my head but not able to find any proper resource or tutorial on it. I have learnt complete altium software from you so pleaaaaaaseeeeee help me with this one too, thank you

[@RobertFeranec]

Soon, an interview with Carl will be published. That may help you. His channel is kzbin.info

[@Anonymous-ok9ul]

@@RobertFeranec Thanks for the response! anxiously waiting for the video

[@kiddaviator]

Thanks for the tutorial! Will you be showing off the finished product when it's fab'd?

[@RobertFeranec]

It's possible

[@aatifshah8476]

@@RobertFeranec sir i am working on one project & in schematic section its showing me warning & blue line on component pins .(nets with no driving source ) plz help me how to solve it.

[@SuperHaptics]

@@RobertFeranec that would be most useful, especially about how stackup assumptions during ordering compare to the actual manufacturing, given that many people would go for the same manufacturer. Great videos thanks!

[@jainebri]

Altium you are using is free or you have to pay??

[@MUKHLALMAHTO]

happy diwali

[@_Khayyam_987_]

Hi. When i delete Top Stiffener at the same time Bottom Stiffener was deleted automatically. What must i do for deleting seperate Stiffener? Thanks from now..

[@RobertFeranec]

Altium has a checkbox to make Stackup symetrical. You may need to uncheck it.

[@_Khayyam_987_]

@@RobertFeranec thanks a lot

[@ahbushnell1]

you should share your file so we can look in detail at what you did.

[@RobertFeranec]

it is on github, just not the latest version github.com/FEDEVEL/youtube-flexcube-matrix-4x4

[@ahbushnell1]

@@RobertFeranec Thank you sir!

[@guillep2k]

I hope you didn't follow your "ordering example" to the letter, unless you know how to build cubes with only 5 faces. 😂

[@RobertFeranec]

You will see how it is built ;) I have got the PCBs ... I am curious how it will look. PS: I only need 4, they are placed above of each other.

[@LoveTheFactory]

Phantabulous. Recommended. Thank you Robert. Best, @LoveTheFactory