First PCB Design Review Request - Sensors Breakout Board - Page 1
Forum section: electronics / general

author: realbarisbasturk
author_rank: Newbie
timestamp: August 07, 2025, 09:51:03 am
content: Hi,I'm trying to design my first PCB and would like to request a review for the first version. My goal is to create a modular environment sensors PCB. It will connect to another (main) PCB which is part of an ongoing larger project of mine. In prototyping stage, I'll use an Arduino Portenta H7 with a breakout board to test it. The schematic and the pcb layout screenshots are attached below.I'm still learning the basics so any feedback will be greatly appreciated.Best,Baris.Disclaimer: I'm a CS graduate and although I've taken introductory courses for circuit and signals in university, it's been a while since I tinkered with electronics. I'm using KiCad and have used Gemini to assist me for pretty much everything up until now.Update:I'm currently adding a TVS diode for ESD protection and a Ferrite Bead. I've shared my last revision addressing part of the feedbacks in reply #7.

author: thm_w
author_rank: Super Contributor
timestamp: August 07, 2025, 09:06:43 pm
content: Looks OK to me. You could add mounting holes, test points, LEDs, if wanted.This could easily be done on a 2 layer board, but 4 layer works too.

author: realbarisbasturk
author_rank: Newbie
timestamp: August 07, 2025, 09:19:47 pm
content: Thanks for the review, I wanted to confirm if there are any major flaws in the initial design first before moving on. I'll probably go with 2 layers as you suggested since 4 layer pcb is probably not necessary here. Mounting holes might provide additional stability so that is also a valid point, thanks.

author: Jerrery
author_rank: Newbie
timestamp: August 13, 2025, 04:15:42 pm
content: Cool to see KiCad design - I ever been using it too. Suggest adding a TVS diode (e.g. SMAJ5.0A) at power input for ESD protection. Also the 3D shows tight connector spacing - might cause soldering issues, maybe adjust slightly~

author: realbarisbasturk
author_rank: Newbie
timestamp: August 13, 2025, 04:20:49 pm
content: Thanks for the review @Jerrery. I plan to update the design with the feedbacks I've received when I find the time.

author: mariush
author_rank: Super Contributor
timestamp: August 13, 2025, 05:03:44 pm
content: It would be easier to rotate the chips ....rotate U1 counter-clockwise 90 degrees, and take the trace going to CS_BME, put a via between the chip and C1 (now on the left side), on the back side come down with the trace and use another via to bring the trace back on top and route it to the right to the pin header.Same deal on the right, rotate clockwise 90 degrees this time, and do the same with that trace.Consider leaving an empty pin (as key) to the left of MISO and duplicating the CS_INT and CS_BMI and CS_BME to the right of miso, mosi , clock ... that would allow someone to use a 2 x 5 ribbon cable to connect the board to some other boardmiso mosi clock GND 3.3vINT BMi BME NC/GND NC/3.3vThe empty pin will allow you to insert a 2x5 plug without issues... if you leave a pin there you would not have the versatility, you'd have to desolder the single row header and swap with another double row header.

author: realbarisbasturk
author_rank: Newbie
timestamp: August 13, 2025, 05:07:21 pm
content: Thanks a lot for the detailed review @mariush, I'll try to digest and experiment with your suggestions when I find the time and post the revised version.

author: realbarisbasturk
author_rank: Newbie
timestamp: August 13, 2025, 08:32:27 pm
content: I'm still working on it and not all feedbacks are addressed yet but here is the draft version to get early feedback:

author: PGPG
author_rank: Frequent Contributor
timestamp: August 15, 2025, 06:05:31 pm
content: For connector pads 1,2,3,4 you don't need your tracks + vias as they are automatically connected to right zones.I think there is a way to force pad 1 getting thermal relief connection at 45°, but don't remember how to do it.Clearances at zones around vias seems for me too big.When I add zone I set 3 of parameters (don't remember names, don't have KiCad here) to 0.25 and one to 0.2.

author: realbarisbasturk
author_rank: Newbie
timestamp: August 17, 2025, 01:16:15 pm
content: Hi @PGPG, thanks for the review.> For connector pads 1,2,3,4 you don't need your tracks + vias as they are automatically connected to right zones.I thought adding multiple vias would help, I know they are not really necessary. If you suggest it actually hinders more than helps, I'll remove it.> I think there is a way to force pad 1 getting thermal relief connection at 45°, but don't remember how to do it.I will look into thermal reliefs, haven't considered it before you mentioned it. It seems like a good candidate for improvement.> Clearances at zones around vias seems for me too big.I used the default (whatever KiCad provides) but will look into it too before I finalize the PCB.

author: PGPG
author_rank: Frequent Contributor
timestamp: August 18, 2025, 11:51:22 am
content: Quote from: realbarisbasturk on August 17, 2025, 01:16:15 pmI just wanted to tell that they are not necessary.If you have several zones with the same net than adding some (many) vias to connect them together is rationale, but if each your zone is different net than it have no sense.Your viases near these connector pads give really nothing. You can think of THT connector pad as of a via but much stronger than other vias because of big hole diameter and being filled with tin.Quote from: realbarisbasturk on August 17, 2025, 01:16:15 pmDefault KiCad settings are very conservative hare. I may be using such parameters in 80s.Whenever I add zone I change parameters to:Clearance, Thermal relief gap and Theremal spoke with to 0.25mm and Minimum width to 0.2mm.These are not very demanding parameters - I would used them also 20 years ago.

author: PGPG
author_rank: Frequent Contributor
timestamp: August 18, 2025, 12:09:36 pm
content: One more think - how many layers your PCB have.It looks that there are at least two zones (3V3 and GND) and they are not at top so probably 4 layers.I use 2 layer PCBs until I don't have to use more layers.Here is the example of my 2 layer PCB:https://forum.kicad.info/t/approaching-pcb-track-routing-for-a-newbie/36302/8I used top layer for supply and signal and whole bottom as GND.I used there three 0Rs to jump with VCC over signal tracks without breaking GND continuity.Top free space is also GND - all vias you see are GND.

author: JOSDHO
author_rank: Contributor
timestamp: September 03, 2025, 07:33:10 am
content: Nice job for a first PCB — the layout looks clean and organized. For a sensor breakout board like this, you might want to add a few extra test pads on the I²C lines and power rails so you can easily hook up a scope probe during debugging. It’s also handy to leave a couple of unpopulated resistor pads or jumpers in series with the signal lines, so you can insert pull-ups or current-limiting resistors later without having to cut traces.If this board will be in an enclosure, think about adding mounting holes early — it saves a lot of headache later. Otherwise, your current 4-layer stackup is fine, but you could even simplify to 2-layer if cost is a concern since signal integrity here isn’t very demanding.Looks like a solid starting point, good luck with the rest of your project!

author: realbarisbasturk
author_rank: Newbie
timestamp: September 03, 2025, 08:56:47 am
content: Hi JOSDHO, thanks for the feedback! I aim to create the final revision this weekend and share it here. I've done a bit of revision and shared it in reply #7 but not all feedbacks are addressed yet. I'll update the first entry as well.Update:I couldn't finalize it this weekend although I've worked on it. I'm planning to add a TVS diode and a Ferrite Bead. I will update the first post when it's ready for review.

author: realbarisbasturk
author_rank: Newbie
timestamp: September 08, 2025, 06:34:22 pm
content: Hi!I'm trying to add a TVS diode for ESD protection and a Ferrite Bead. Before I move on to PCB editor, I'd like to verify my schematic. Do TVS diode and Ferrite Bead connections seem ok? I'm planning to create an empty area/island around J1 Connector's power and ground pins then add these components in that island. I also would like to know if these are valuable/necessary additions to the sensor breakout board.

author: thm_w
author_rank: Super Contributor
timestamp: September 08, 2025, 08:32:12 pm
content: The diode is upside down.Ferrite looks ok but I would put something larger than 100nF, maybe 1uF or 10uF, should be available in the same footprint.

author: realbarisbasturk
author_rank: Newbie
timestamp: September 08, 2025, 08:44:32 pm
content: Quote from: thm_w on September 08, 2025, 08:32:12 pmThe diode is actually bidirectional but I couldn't find a suitable symbol. I'll correct the direction to avoid confusion though, thanks.About the 1uF vs 10uF, you mean the capacitors around the ferrite bead right? If that's what you mean then yes I'll adjust the values.

author: SYOM
author_rank: Newbie
timestamp: September 09, 2025, 08:04:16 am
content: Great job on the PCB design! It’s great that you’re taking the modular approach and using an Arduino Portenta H7 for prototyping.A few things to consider:Power and Ground Planes: Make sure you’ve added solid power and ground planes to minimize noise and voltage drops, especially since you're connecting it to other sensors and components. In KiCad, you can use zones to define these.Decoupling Capacitors: I noticed you might not have added decoupling capacitors for each power pin of the ICs. Adding 0.1 µF and 10 µF capacitors close to the power pins will help with filtering noise and voltage spikes.TVS Diodes: I see you’re adding a TVS diode for ESD protection, which is excellent! Make sure the TVS diode’s clamping voltage is well within the voltage rating of your components to avoid any damage. The placement should also be close to the input pins to be effective.The addition of a ferrite bead is also great for filtering high-frequency noise, but keep in mind it will add some resistance, so ensure it's in an area where it won’t impact power delivery significantly.Looking forward to seeing the final version once you’ve implemented the feedback!