36-Layer Industrial Control PCB — Project Case Study

Project Background

This project was commissioned by an industrial automation company in Argentina requiring a high-layer-count PCB for a PLC (Programmable Logic Controller) application. PLC controllers demand exceptional signal integrity across multiple power and signal planes, precise impedance control, and reliable thermal management under continuous operating conditions.

At 36 layers, this board sits at the upper end of standard multilayer PCB complexity — requiring sequential lamination cycles, precise layer registration and controlled impedance routing across the full stack-up.

Engineering Challenges

Thermal Management
With 2oz copper weight across 36 layers, managing heat distribution through the board stack was the primary engineering challenge. Copper planes were strategically arranged to act as thermal spreaders, distributing heat away from high-power components in the PLC control circuitry. Our CAM engineers reviewed the stack-up specifically for thermal via placement and copper balance before production started.

Layer Registration
Producing a 36-layer board with consistent layer-to-layer registration across the full 220mm x 150mm format requires precise press control and multiple sequential lamination cycles. Any misregistration at this layer count compounds through the stack and affects via reliability. Our manufacturing team applied tight press cycle parameters to maintain registration tolerance throughout.

Controlled Impedance
PLC controller boards carry both high-speed digital signals and power distribution across the same stack-up. Achieving the specified impedance values across signal layers while managing the 2oz copper power planes required careful dielectric thickness selection within the Isola laminate stack-up.

Materials & Specifications

Isola Laminate
Isola high-performance laminates were selected for this project due to their dimensional stability, consistent dielectric properties and thermal reliability under industrial operating conditions. Isola materials maintain tight Dk tolerances across the frequency range relevant to PLC control signals, making them well-suited for complex multilayer stack-ups.

ENIG Surface Finish
Electroless Nickel Immersion Gold was specified for its flat, solderable surface — essential for fine-pitch component placement on a dense PLC controller board. ENIG also provides excellent shelf life and oxidation resistance for boards deployed in industrial environments.

2oz Copper
The 2oz copper weight was specified to handle the current-carrying requirements of the PLC power distribution layers while contributing to overall board thermal performance.

Quality Assurance

Every board in this production run underwent:

• Automated Optical Inspection (AOI) — full surface inspection of all copper features, pad geometry and solder mask alignment against the original Gerber data
• Impedance Testing — controlled impedance verification on specified signal layers using TDR (Time Domain Reflectometry) to confirm trace impedance values matched the design specification
• IPC Class 2 Standard — production and inspection carried out to IPC-6012 Class 2 requirements for industrial electronics
• All boards were shipped to Argentina and passed incoming inspection without rework.

Why the Customer Chose Kejie PCB

For a 36-layer industrial board destined for PLC applications in the field, the customer needed a manufacturer with proven multilayer capability, direct engineering communication and reliable quality control — not an automated quoting platform.

Kejie PCB’s engineering team reviewed the Gerber files and stack-up before production, identified thermal via optimisation opportunities, and maintained direct communication with the customer’s design team throughout the project. The boards were shipped to Argentina on schedule and passed the customer’s incoming inspection without rework.

Need a High-Layer-Count PCB?

Whether your project calls for 12, 24 or 36+ layers, Kejie PCB’s engineering team reviews every design file manually before production starts. Upload your Gerber files and our engineers will respond with a detailed quote within 24 hours.