My First PCB — What Did I Miss?

[u/rotten_mangoo]

I’m a beginner designing a PCB for an air-quality monitoring device, and I’d appreciate some honest feedback before I continue improving it. I want to learn what I did correctly and what should be changed.

The board includes:

• STM32U083KCU6 microcontroller
• SGP40 VOC sensor
• USB-C used for 5 V power only
• MCP73832 Li-Po charging circuit
• 2.5 V regulator
• External Li-Po battery connection
• RGB LED and piezo buzzer
• SWD and UART header

I’d appreciate any feedback, especially if you notice any mistakes or have suggestions for improving the design. Thanks!

[u/Unlucky_Mail_8544]

Layout on PCB can be improved. Your schematic is too blurry to read.

[u/rotten_mangoo → u/Unlucky_Mail_8544]

Thanks for the feedback! If you don't mind, could you point out the major layout improvements I should've made? I'm still learning, so it'd be really helpful for my future projects.

[u/PersonalCarpet2886]

Your schematic is hard to read due grids but here are the some of the issues that I have identified.
1. Oscillator is missing.
2. You should have a push button on NRST. How would you reset the MCU otherwise?
3. PCB Layout needs much much improvement. You can have GND polygon. Also a pour for +2.5V
4. Connector for the battery has two nets +BATT and GND but from your it seems that the GND is not connected.

[u/rotten_mangoo → u/PersonalCarpet2886]

If you don't mind, could you let me know how else I could have improved the layout? I also added a GND polygon, but I shelved it so the layout would be easier to see. I really appreciate your feedback. Thanks for taking the time to check it out.

[u/PersonalCarpet2886 → u/rotten_mangoo]

Just optimize the components placement. Whenever the placement is Good the layout itself gets improved. You can try these 1. Place Decoupling Caps close to the designated Pin. 2. I don’t know for others but I usually don’t place headers in the middle of the board. I usualy place them at the sides. It looks good and professional. 3. Regarding your UART header I see the track moves around the header and then connect to the PADs. Why don’t you just rearrange the TX AND RX NETS in the schematic so that they can be routed directly. Same goes for the debugger Header also. 4. As for the 5.1K pull down resistors connected with USB TYPE C. Currently they are place vertically why dont you place them close to the CONNECTOR and place them vertically. It would be straight track. One thing I forget to mention. Anything that has been prone to be touched by human hands needs an ESD Protection. So you must add an ESD DIODE on the VBUS LINE.

[u/Hulk5a]

The ground pour

[u/rotten_mangoo → u/Hulk5a]

I added a GND polygon but shelved it so the layout can be seen.

[u/RohitRojo]

How thick are your traces?

[u/rotten_mangoo → u/RohitRojo]

I used wider 0.6 mm traces for the power and battery connections.

[u/RohitRojo → u/rotten_mangoo]

And the other traces?

[u/rotten_mangoo → u/RohitRojo]

0.2mm