Metal Core Heavy copper PCB

Metal Core Heavy copper PCB

To operate efficiently and ensure reliability, heat must be removed from heat generating power components.

As a result of faster speeds, reduced format, and more devices being populated on Printed Circuit Board, more heat is being generated that must be removed for efficient operation.

The move to sustainable-energy increased the demand for energy management electronics which also create much heat because of the high electrical currents as used on these applications (Power inverters for solar and wind-energy, powertrain electronics for HEV)

Thermal management through various applications aids in directing heat away from heat generating system components. The following are a review of various thermal management approaches, applications and capabilities.

Metal Core Heavy copper PCB

PCB Thermal Management Types

Applications requiring PCB Thermal management

It is important to utilize the best application for your thermal management application. Considerations of cost and how much thermal heat removal required are important. Typical applications for Thermal Management may include:

  • Power Applications: Power amplifiers, DC power supplies, Power control systems, RF/MW applications
  • Automotive: Motor Control Modules, Electric brake system, Power-train in EV
  • High Speed Computing
  • Lighting systems: Automotive, Industrial, Consumer

Thermal Conduction in PCBs

Thermal resistance at each level of an electronic system will impact conduction and Heat generated must be transferred to Environment.

Metal Core Heavy copper PCB

Thermal Conduction in PCB

Air Gap Thermal Resistance

The air gap under components generally represents the greatest thermal resistance

  • Air has a thermal conductivity approximately 0.025 W/ mK
  •  Under filling the component can dramatically reduce thermal resistance
Air Gap Thermal Resistance

PCB Thermal Conductivities

PCB’s are composed of resin, glass and a random distribution of copper that is parallel to the PCB surface.  An approximate value for parallel and perpendicular conductivity is:

K II = 27.5 W/mK

K= 0.41 W/mK

PCB Thermal Conductivities

Approximations are based on FR4 based laminate and will vary based on actual board construction and specific distribution of copper but they are a good starting point.

Thermal conductivities of common PCB materials

Thermal conductivities of common PCB materials

PCB materials Thermal conductivities

PCB Thermal Resistance: Parallel

PCB Thermal Resistance

This  example does not take into account the thermal resistance from the IC and perpendicular resistance in the PCB.

PCB Thermal Resistance: Perpendicular

PCB Thermal Resistance

Relatively large thermal resistance in the Z axis since copper layers are separated by high resistance laminate

PCB Thermal Resistance

PCB Thermal Management – Heavy Copper

Thick Cu Outer layers in Printed Circuit Boards

External conductors we can employ Copper-plate & Etch technology

PCB Thermal Management

Heavy copper PCB

210um (6Oz) final copper thickness on external layers

210um (6Oz) final copper thickness on external layers

Heavy Copper Inner-layers in printed Circuit Board

6 Layer Heavy copper PCB

  • Two cores with two 10oz/10oz copper layers based on print and etch process
  • To avoid reliability-issues with extreme heavy copper on outer-layers it is recommend to move heavy copper to inner layers
Heavy Copper Inner-layers in printed Circuit Board

4 Layer Heavy copper PCB

One core with two 410um (12 Oz) copper layers based on print and etch process

4 Layer Heavy copper PCB

PCB Thermal Management – Insulated Metal Substrate (IMS)

PCB Thermal Management – Insulated Metal Substrate (IMS)

Metal Clad PCB Manufacturing Process

Insulated Metal Substrate (IMS) PCB Capabilities

Al IMS (5052)Cu IMS
MaterialVentec BergquistVentec Bergquist
Layer Count in MP1L1L
Max Panel size18” x 24”16” x 21”
Min dielectric layer thickness75um75um
Max Copper thickness3oz3oz
V-cutYesYes
RoutingYesYes
Solder maskGreen, White, BlackGreen, White, Black

Insulated Metal Substrate PCB Case studies:

IMS PCB Example 1

Metal Type:  5052 Al

Dielectric thickness: 100um

Copper Thickness: 3 OZ

Al thickness: 1.9mm

Surface finish:  LF-HASL

IMS PCB Example 1

IMS PCB Example 2

Metal Type:  5052 Al

Dielectric thickness: 75um

Copper thickness: 2 OZ

Al thickness: 1.9mm

Surface finish:  LF-HASL

IMS PCB Example 2

IMS PCB Example 3

Metal Type:  5052 Al

Dielectric thickness: 75um

Copper Thickness: 3 OZ

Al thickness: 1.0 mm

Surface finish:  LF-HASL

IMS PCB Example 3

IMS PCB Example 4

Metal Type:  5052 Al

Dielectric thickness: 100um

Copper Thickness: 3 OZ

Al thickness: 1.0 mm

Surface finish:  LF-HASL

IMS PCB Example 4

Cerra Systems Printed Circuit Board Fabrication capabilities support high-frequency PCB, High-temperature Boards, Thick PCB, ultra-thin PCB, heavy copper PCB, Metal Core PCB, HDI boards with Blind Vias, Buried Vias, Micro Vias, Embedded passives, bonded heat sink, Impedance Control, Depth control drilling, Back drilling, Edge Plated PCB, Bump Pads, cavity with ledge, Via on pad and stacked micro-Via technology.

CerraSystems – http://cerrasystems.com

HDI PCB ,  Rigid Flex PCBRF PCB 

Electronics Manufacturing Partners:

Argus Systems (AESPL) –  www.sysargus.com

PCBPCBACable AssemblyBox BuildTesting

EMSxchange – www.EMSxhange.com

PCBACable AssemblyBox Build ,  TestingLogistics