Hello everyone,

I'm developing an ESP32-based monitoring and control board that is moving from prototype quantities into a small production run.

The prototype boards have been working well, but during assembly and testing I'm seeing a few boards that occasionally fail to boot or show unstable behavior until they are power-cycled. The issue is not consistent, which makes troubleshooting difficult.

Current design includes:

• ESP32-WROOM module
• Multiple I2C sensors
• RS-485 communication
• External power input
• Custom 4-layer PCB

A few questions for those with experience taking ESP32 designs into production:

1. What are the most common PCB-related issues that only appear during production rather than prototyping?
2. Have you encountered grounding or power integrity problems that caused intermittent ESP32 startup failures?
3. Are there specific test points or diagnostics you recommend adding before the next revision?
4. How much margin do you typically leave around power supply and RF sections?

PCB Manufacturing Question:

The next revision will likely be manufactured through PCBWay, and I'm also reviewing panelization options.

• Are there panelization practices that help reduce handling or assembly issues?
• Have you seen breakaway tabs or V-scoring create reliability problems near sensitive circuitry?
• How much board-edge clearance do you typically leave around antennas and connectors?

Connector and Wiring Harness Question:

The final product will connect to external sensors and power sources through wiring harnesses.

• What connector families have proven most reliable for ESP32-based products?
• Do you prefer separate connectors for power and signals, or combined harnesses?
• Have connector-related failures become a significant issue in field deployments?
• Any recommendations regarding strain relief or harness routing?

I'd appreciate hearing from anyone who has taken ESP32 products from prototype boards into small-scale production.

 

Intermittent startup issues that only appear during production often end up being related to power sequencing, marginal solder joints, or component tolerance variations rather than firmware.

For the ESP32 specifically, I'd pay close attention to the EN and boot-strapping pins, power supply ramp-up behavior, and decoupling around the module. Small differences between prototype and production assemblies can sometimes expose issues that weren't visible on a handful of boards. Check out this discussion: https://electronics.stackexchange.c...-boot-strapping-pins-problem-gpio15-and-gpio5

For the next revision, adding test points for key power rails, EN, TX/RX, and important control signals can make troubleshooting much easier.

Regarding connectors, I've generally had better long-term results using separate connectors for power and signals, especially in environments where sensors may be connected or disconnected during maintenance. Proper strain relief is also worth the extra effort, as connector and harness issues tend to become more common in field deployments than PCB failures themselves. Check these PCB connector design rules: https://www.pcbway.com/blog/Engineering_Technical/PCB_Connector_Design_Rules.html

Out of curiosity, are the boards that fail to boot always the same units, or does the problem appear randomly across different boards in the production batch?

 

Hello everyone,

I'm developing an ESP32-based monitoring and control board that is moving from prototype quantities into a small production run.

The prototype boards have been working well, but during assembly and testing I'm seeing a few boards that occasionally fail to boot or show unstable behavior until they are power-cycled. The issue is not consistent, which makes troubleshooting difficult.

Current design includes:

• ESP32-WROOM module
• Multiple I2C sensors
• RS-485 communication
• External power input
• Custom 4-layer PCB

A few questions for those with experience taking ESP32 designs into production:

1. What are the most common PCB-related issues that only appear during production rather than prototyping?
2. Have you encountered grounding or power integrity problems that caused intermittent ESP32 startup failures?
3. Are there specific test points or diagnostics you recommend adding before the next revision?
4. How much margin do you typically leave around power supply and RF sections?

PCB Manufacturing Question:

The next revision will likely be manufactured through PCBWay, and I'm also reviewing panelization options.

• Are there panelization practices that help reduce handling or assembly issues?
• Have you seen breakaway tabs or V-scoring create reliability problems near sensitive circuitry?
• How much board-edge clearance do you typically leave around antennas and connectors?

Connector and Wiring Harness Question:

The final product will connect to external sensors and power sources through wiring harnesses.

• What connector families have proven most reliable for ESP32-based products?
• Do you prefer separate connectors for power and signals, or combined harnesses?
• Have connector-related failures become a significant issue in field deployments?
• Any recommendations regarding strain relief or harness routing?

I'd appreciate hearing from anyone who has taken ESP32 products from prototype boards into small-scale production.

This kind of issue is pretty common when you move to production.

It really sounds like a power problem. The ESP32 is sensitive when it boots, so if your 3.3V dips or isn’t clean, you can get random failures. Adding a bit more capacitance and making sure your layout (ground + decoupling) is solid usually fixes it. Also worth checking the EN and boot pins.

I’d add a few test points (3.3V and UART at least) to make debugging easier.

For panelization, just don’t put important parts too close to edges or break tabs.

For connectors, use locking ones and add strain relief loose or stressed connectors cause a lot of real-world issues.

Nothing unusual here most of the time it comes down to small power or layout tweaks.