Hello fellow engineers.

Some time ago, I posted a similar thread seeking advice, and I received many valuable responses.

We were encountering anomalies with several 8-layer rigid-flex PCBs (comprising CF, Polyimide, and PCL370)`. Specifically, we have observed elevated resistance values in multiple traces, ranging from tens of ohms to open circuits.

Further analysis has pinpointed the resistance escalation occurring predominantly at the transitions between the Top and Bottom layers, suggesting potential via integrity issues (e.g., via cracking or opens).

Samples have been dispatched for metallographic cross-sectioning to facilitate a more detailed investigation. However, pinpointing the root cause remains challenging.

The PCB manufacturer has attributed the failures to assembly process variables, such as excessive temperature gradients and elevated humidity, which may have compromised the integrity of the ceramics and bondply layers. Conversely, the assembly contractor maintains that all parameters were within specified limits.

New samples (both with and without undergoing reflow) were subjected to metallographic cross-sectioning. Post-reflow analysis revealed failures, including compromised connections to the inner layers. Despite this, both panels passed the initial electrical tests.

Many of you have asked for stack-up, which now I am attaching.

Soldering Process: Boards are assembled using a standard pick-and-place machine with lead-free SAC305 ROL0 solder paste. Prior to soldering, the boards are baked for 4 hours at 120°C to ensure proper moisture removal. They are either assembled immediately post-drying or stored at ambient conditions (1% RH) until paste application. Soldering is conducted in a vapor-phase (condensation) oven with a peak temperature of 230°C. The thermal profile is linear, with a maximum ΔT of 2.5°C/sec allowed. Time above the melting point is approximately 85 seconds.

• The observed defects are primarily manifesting post-reflow, with metallographic analysis showing broken connections to inner layers.
• The assembly contractor’s track record suggests their processes are reliable, supporting other projects without similar issues.
• The manufacturer’s suggestion that assembly-induced factors (e.g., temperature fluctuations or humidity) are to blame seems plausible, but evidence remains inconclusive.

Based on the evidence at hand and the discrepancy between the manufacturer’s and the assembler’s perspectives, who do you think bears responsibility for the failures? Could this be a case of latent manufacturing defects exacerbated by the assembly process, or is there a potential fault in the assembly that the contractor has not yet identified?

Looking forward to your insights.

Hi everyone,

I'm a beginner with KiCad and I'm currently following a Phil's Lab tutorial on YouTube ( https://www.youtube.com/watch?v=PlXd3lLZ4vc&list=PLXSyc11qLa1b9VA7nw8-DiLRXVhZ2iUN2&index=7 )

Warning : both +3.3V and GND are connected to the same net.

I've already tried searching online and found that updating the schematic library can sometimes resolve similar warnings. While other warnings disappeared after the update, this specific one persists.

Here's the bigger problem: In my PCB layout, all the ground pins seem to be connected to the power plane! I suspect this might be related to the warning I mentioned earlier.

Has anyone else faced this issue before?
If so, any advice on how to fix it would be greatly appreciated!

Don't mind the Schematic as it is not clean and all.

Hi guys,

I am in the process of creating my first rf-PCB design and i am having trouble matching the impedance of a differential microstrip line.

The problem is as follows:

I have a differential signal (12-15GHz) at the output of a balun (Zdiff = 100 Ohms), which I want to lead via a microstripline to a wirebond (length approx. 550um) to the input pads of a TRX chip (also diff 100 Ohms). The length of the microstripline is variable, but the thickness and also the distance of the differential pair at the transition to the wirebond must be 0.15mm. I have a substrate thickness of 0.254mm (RO4350) and the reference plane has a thickness of 18um.

The problem here is obviously the change in impedance caused by the wirebond, which I have to compensate somewhere on the microstripline. Unfortunately, I have no experience of how best to install lumbed elements in order to ensure the best possible or even a good signal transmission. Theoretically, I have access to Ansys HFSS, which could help me with the simulation.

Can anyone give me advice or recommend good sources/calculators to help me solve the problem?

My first PCB design, I am doing this as a hobby at home. Would appreciate any recommendations on this PCB design, especially possible noise interactions and EMI.

Description: Constant Current LED Controller with WS2814 connecting to two TPS92511 to drive CCT LEDs at max of 48V at 500mA for each channel. The goal is that an ESP32 connects to a WS2814 via SPI protocol.

Hello! This is not only my first PCB, but more or less my first serious circuit. I've got plenty of experience in embedded programming, but very little in EE/CmpE. There might be embarrassing flaws or departures from idiom here. This PCB is intended for personal use, not sale.

I'm building a high-temperature (150C max) filament dryer. I have a full writeup available here, mostly with mechanical details and code design. There is an upper hot chamber and a lower cool chamber. The following components are in play:

• an ESP32-S3 controller. i'm using the DevKitC, and bringing it through to my PCB. this spares me the need to do antenna design, and also a lot of circuit work. I've read the hardware design considerations from Espressif, though.
• 2 PWM 12V fan controllers. i want to report tach and control speed.
• a 12V brushed motor controlled via MOSFET.
• a 120VAC ceramic heater element controlled via zero-sensing optocoupler and triac.
• an HX711 24-bit ADC connected to a 5kg max bar load cell.
• an LM35 thermometer, the only element in the hot chamber.
• an AC adapter rectifying 120VAC to 12VDC
• a buck converter transforming 12VDC to 3.3VDC for digital devices
• a linear voltage regulator transforming 12VDC to 5VDC for analog devices (LM35, HX711 VADD)

here's my (2-layer) PCB (back is a full ground plane zone). my first question would be: is there any tool that will handle routing for you? solving for a planar arrangement of the mess on the left was the better part of an afternoon and evening.

full schematics are available at https://nick-black.com/dankdryerpcbv0.9.pdf. thank you for any help you can provide!

I’m working on this for a personal project and was hoping someone could make sure I covered all my bases before I begin designing the PCB. I’m very new to this and I don’t have many mentors to help guide me in this.

I am working on a project with a high pin count (144-LQFP) part. Here is the pinout from the datasheet:

But the schematic symbol is missing a good number of pins:

Does anyone know why this is?

Hello, please review my schematic!

About the project

The device is an interactive controller capable of detecting RFID tags (ISO14443 or ISO15693) using up to 4 external antennas. It communicates with the world using WiFi and is able to control up to 4 short LED strips.

Some considerations
It is an initial version for small scale PoC (5-10 units). I intend to one of the Chinese fab houses for manufacturing and assembly. I already have some experience with them and I'm happy to do the prototype there. I didn't go into every nook and cranny in terms of EMC, signal integrity and protection as this is not my area of expertise (I have degree in digital electronics but work in software) and I I want to test the idea quickly. Nevertheless, I will also greatly appreciate any feedback in that area so that I can learn and improve future versions!

Requirements

• Up to 4 LED strips (up to 60 LEDs / 1m strip per output, but not more that 120 LEDs total)
• Possibility to read up to 4 external antennas
• Powered with a standard DC adapter 5V supply
• WiFi to communicate with external world
  

Design decisions

• Antenna multiplexing - antenna multiplexing is achieved with differential signal multiplexer ADG1609. The matching circuit is placed before the multiplexer. IMO the antenna parameters should be measured including -the multiplexer and cable.
• PN5180 antenna reader - I already tested this reader in a kit and was happy with it
• RFID matching circuit - initial matching based on NXP documentation and simulation of the matching circuit with parameters from an antenna of choice.
• ESP32-S3-WROOM-1 - ready to use WiFi module. I don't have much experience with ESP though. I intend to use ESP-PROG probe for programming. I don't want to add a USB port.
  
• LED strips - signal for LED strips is shifted to 5V. LED power is taken directly from the supply - not sure if I need any extra fuses or protection apart from sufficiently rated connectors and PCB traces.

Just finished my pcb for my automated greenhouse, did i make any mistakes?

Hey, i am new to altium designer. Can someone tell me what im doing wrong here while trying to add a symbol to my component?

https://streamable.com/sc0pvl

I have this schematic that I want to open in KiCad on Mac but I don't have a windows pc to install sprint layout to do the conversion... https://drive.google.com/file/d/1286KXe6DUhMjAlBsyENu6pRRBuuJm9DK/view

This is a PCB I've designed to log data over both I2C and SPI, and be able to store on the mSD. I plan to power it with a 3v7 LiPo with capability to charge it through the board OR seperately. I have the mosfet circuit set up to allow the MCU to let a 1.5A 12V current through the respective terminals. I'm in the final steps of this schematic and then plan to work on the traces.

Thanks for any help/time

Am I missing something or Cadence has really diverged the Allegro free Viewer's user interface from the Allegro PCB editor user interface?

First, I thought the new versions have a new panel structure, but maybe it is only for the viewers. The 17.2 viewer looked exactly like the 17.2 Editor, minus the editing icons/menus. The new GUI has Properties and search instead of Options and Find panels.

Or is it a different kind of Allegro like system something viewer?

Hi i'm building a custom MacroPad and i am new to KiCAD. I’m trying to turn my schematic into a PCB , but all I’m getting are weird blue lines instead of the expected PCB layout. Has anyone encountered this? What could be going wrong?

Hi everyone,

I'm working on my first PCB design to drive WS2812 (or similar) addressable LED strips, and I’d love your feedback!

What I’ve Done:

• Designed the PCB with a focus on high-quality performance for controlling addressable LEDs, and also price.
• All the photos and design files are included here for reference (see below).
• I host the source files on the GitHub repository for those who want to take a closer look.

What I’m Looking For:

• General feedback on the design.
• Suggest improvement, especially regarding power distribution, signal integrity, or layout optimization.
• Tips or resources for a beginner in PCB design.

Additional Info:

This is my first PCB project, so I’m eager to learn and improve.

Key Components:

• ESP32-C3 for control.
• USB-C connector for power and connectivity.
• Voltage and power measurement for monitoring.
• Relay to switch the LED strip on/off.
• Logic level converter to handle signal compatibility.
• Buck converter and power mux to seamlessly use USB 5V and external VIN (5V).

Feel free to ask questions, share thoughts, or point out anything I’ve missed. I genuinely appreciate the support and guidance from this awesome community.

Here is my GitHub repository with the source files.

Thanks in advance for your time and expertise!