Building Multilayer Metal Core PCBs Design, Structure, Materials, and Manufacturing Guide

What Is a Multilayer Metal Core PCB?

Multilayer Metal Core PCBs (MCPCBs) are advanced printed circuit boards that incorporate a metal core layer—such as aluminum, copper, or iron alloy—within a multilayer PCB structure.

Compared with traditional FR4 multilayer PCBs, multilayer MCPCBs offer:

• Significantly enhanced thermal conductivity

• Superior heat dissipation

• Improved mechanical rigidity

• Higher power density capability

Because of these advantages, multilayer metal core PCBs are widely used in:

• Communication electronics

• Power converters and inverters

• LED lighting systems

• Medical devices

• Industrial and automotive electronics

At KKPCB, we specialize in designing and manufacturing high-reliability multilayer MCPCBs for demanding thermal applications.

Key Design Considerations for Multilayer MCPCBs

Designing a multilayer metal core PCB requires special attention beyond standard FR4 designs.

1. Thermal Management Is the Core Objective

The primary purpose of a metal core is efficient heat dissipation. Key design points include:

• Minimizing dielectric thickness (typically 0.003–0.006 inches)

• Ensuring uniform heat spreading across the metal core

• Reducing thermal resistance between components and the core

Metal core PCBs conduct heat 8–9 times faster than FR4.

2. Strict Control of Board Thickness

The total thickness of multilayer MCPCBs must be carefully controlled to ensure:

• Mechanical strength

• Flatness

• Reliable lamination

• Compatibility with enclosures and mounting hardware

Typical metal core thickness:

• 1.0 mm / 1.5 mm / 3.2 mm

• Overall substrate thickness range: 1–4 mm

Structure of a Multilayer Metal Core PCB

A typical multilayer MCPCB structure consists of:

1. Top Copper Layers

   • Signal, power, or mixed routing

   • Copper thickness: 1–4 oz

2. Dielectric Insulation Layer

   • Electrically isolates copper from metal core

   • Ultra-thin for fast heat transfer

3. Metal Core Layer

   • Aluminum, copper, or iron-based alloy

   • Primary heat-spreading layer

4. Bottom Copper / Backplate (Optional)

   • Mechanical support or grounding plane

   • Often left uncoated to reduce EMI

Important Design Rule
The metal core should typically be connected to ground to prevent it from acting as a large antenna and introducing EMI issues.

Advantages of Multilayer Metal Core PCBs

Compared with standard multilayer FR4 PCBs, multilayer MCPCBs offer:

 Superior Heat Dissipation

• Entire metal base acts as a heat spreader

• Reduced reliance on thermal vias

 Higher Power Density

• Supports high-current and high-power components

• Ideal for switching power circuits and LEDs

 Improved Reliability

• Lower junction temperature

• Extended component lifespan

 Simplified Manufacturing Features

• Minimal drilling required

• Only large mounting holes needed

 Higher Mechanical Strength

• Reduced warpage

• Better flatness control

Metal Substrate Options for Multilayer MCPCBs

Aluminum Core Multilayer PCBs

• Most commonly used substrate

• Excellent cost-to-performance ratio

• Lightweight and recyclable

• Suitable for most LED and power applications

Thermal performance: ~130 W/mK
Typical applications: LED lighting, power supplies, motor drives

Copper Core Multilayer PCBs

• Best thermal conductivity among all options

• Higher cost and weight

• Suitable for extreme thermal requirements

Thermal performance: ~400 W/mK
Typical applications: RF power amplifiers, aerospace, high-power modules

Iron-Based Multilayer PCBs

• High mechanical strength

• Lower thermal conductivity than aluminum

• Suitable for extreme temperature environments

Typical applications:

• High-temperature industrial systems

• Multi-LED heat dissipation platforms

Iron-based PCBs are more robust and resistant to bending but are heavier and more costly than aluminum solutions.

Copper Invar Copper (CIC) Multilayer PCBs

CIC (Copper–Invar–Copper) is a specialized metal core material widely used in aerospace and high-reliability electronics.

CIC Key Advantages:

• Very low coefficient of thermal expansion (CTE)

• Excellent dimensional stability

• Good thermal conductivity

• Ideal for large ground planes and power layers

Manufacturing Considerations:

• Special etching processes required

• Ferric chloride (FeCl₃) preferred over CuCl₂ due to different etch rates between copper and invar

• More complex and higher cost than standard MCPCBs

Manufacturing Process of Multilayer Metal Core PCBs

At KKPCB, multilayer MCPCB manufacturing typically includes:

1. Metal Core Preparation

   • Cutting, punching, surface treatment

2. Dielectric Lamination

   • High-temperature and pressure bonding

   • Removal of residual fillers

3. Electroplating of Inner Metal Layers

4. Multilayer Lamination

   • Specialized stacking sequence

5. Circuit Patterning

   • Imaging, etching, plating

6. Final Assembly & Inspection

   • SMT, high-temperature soldering, or sintering

Because of the complexity, multilayer MCPCBs require tight process control and experienced manufacturing partners.

Applications of Multilayer Metal Core PCBs

Multilayer MCPCBs are ideal for applications requiring high thermal reliability, including:

• High-power LED arrays

• Power converters and inverters

• Medical imaging equipment

• Communication base stations

• Automotive electronics

• Aerospace and defense systems

Why Choose Multilayer MCPCBs from KKPCB?

Multilayer metal core PCBs provide unmatched advantages in:

• Thermal management

• Power handling

• Mechanical stability

• Long-term reliability

Material selection guide:

• Aluminum core → Best overall value

• Copper core → Maximum heat dissipation

• Iron-based / CIC → Extreme environments & dimensional stability

At KKPCB, we support customers from DFM design review to mass production, ensuring your multilayer MCPCB meets thermal, electrical, and mechanical requirements.

 Contact KKPCB today for professional multilayer metal core PCB solutions.