Metal Core (Aluminum and Copper) Printed Circuit Boards

Definition of a Metal Core Printed Circuit Board

A metal core printed circuit board (MCPCB) also known as thermal PCB, incorporates a metal material as its base as opposed to the traditional FR4, for the heat spreader fragment of the board. Heat builds up due to some electronic components during the operation of the board. The purpose of the metal is to divert this heat away from critical board components and towards less crucial areas such as the metal heatsink backing or metallic core. Hence, these PCBs are apt for thermal management.

In a multilayer MCPCB, the layers will be evenly distributed on each side of the metal core. For instance, in a 12-layer board, the metal core will be at the center with 6 layers on the top and 6 layers at the bottom.

MCPCBs are also referred to as insulated metallic substrate (IMS), insulated metal PCBs (IMPCB), thermal clad PCBs, and metal-clad PCBs. In this article, we will be using the acronym MCPCB to avoid ambiguity.

The MCPCBs are made up of thermal insulating layers, metal plates, and metal copper foil.

The basic structure of MCPCB comprises of the following:

• Solder mask
• Circuit layer
• Copper layer – 1oz. to 6oz. (most commonly used 1oz. to 2oz.)
• Dielectric layer
• Metal core layer
• Heat sink

Types of Metal Bases used in MCPCBs

Aluminum substrate – The aluminum printed circuit boards offer good heat dissipation and heat transferring ability. Since they are light in weight, the aluminum core PCBs find their purpose in LED lighting, audio frequency apparatus, and communication electronic equipment.

Here, the thickness of the core ranges between 40 mils and 120 mils, with 40 mils and 60 mils being the most commonly used.

• 8mm to 2mm aluminum thickness
• 5W/(mK) and 2.0W/(mK) thermal conductivity
• Greater than 9lb/in peeling strength
• Solder resistance: SF: 288℃, >180 sec.
• >3000V breakdown voltage
• 03 dielectric loss angle
• UL 94V-0 flammability
• 18" x 24" panel size

Copper base (copper core or heavy copper) – The copper core boards feature better performance than aluminum. But customers generally choose aluminum since copper is relatively expensive. Also, copper cores are heavier and involve a tough machining process.

Why Metal Core PCBs?

Accumulation of too much heat in printed circuit boards lead to malfunctions in the devices. Electronic devices that generate a considerable amount of heat cannot always be cooled using conventional fans. Conductive cooling through metal core boards is an ideal option. In conductive cooling, the heat is transferred from one hot part to a cooler part by direct contact. This works well since heat constantly seeks to move to any object or medium that is cooler.

Benefits of a Heavy Copper Printed Circuit Board

These boards possess the ability to integrate a dielectric polymer layer with high thermal conductivity for lower thermal resistance.

• The higher the conductivity of the material, the faster the heat transfer.
• The metal boards can be etched to control heat flow away from components
• Boards with aluminum tend to be lighter in weight than ceramics.
• Metal substrates are long-lasting and are more conductive than epoxy products.
• Metals are non-toxic and are recyclable.
• Implemented in high vibration applications. The components don't fall off since the core reduces the vibration.

Common Usage of a Metal Core Printed Circuit Board

MCPCBs are most widely found in LED technologies. Some of the popular applications are:

• LED
• Backlight unit
• General lighting
• Automotive
• Moto drives
• Solid-state relays
• Power converters
• Electric/Hybrid motor control
• Solar panels
• Motion control
• Photovoltaic
• Heat spreaders
• Heat sinks

Further design guidelines/recommendations for Metal Core (Aluminum and Copper) Printed Circuit Boards are available upon request; contact PCB Universe at Sales@PCBUniverse.com or your Account Representative to inquire more!