Capability for Metal Core Printed Circuit Boards

  • The heat dissipation performance of copper plate is superior to that of aluminium plate and iron plate in essence, the heat dissipation performance of copper substrate is one of the three criteria to measure the quality of plate (thermal resistance and pressure resistance are the other two).
  • The thermal conductivity of copper substrates can be measured by testing instruments after lamination.
  • The high thermal conductivity is usually ceramics, aluminium and so on. However, considering the cost, most of them are copper substrates on the market at present.
  • The corresponding thermal conductivity of copper substrates is a concerned parameter.
  • The higher the thermal conductivity is, the higher the thermal conductivity is. One of the symbols of better representativeness. Copper substrate is a unique metal-based copper clad plate, which has good thermal conductivity, electrical insulation and mechanical processing performance.
No. Item Value
1 Special Material Aluminum, Copper, Steel substrate , etc.
2 Max Heat Conduction 400 W/M.K
3 Max Layer Count 4
4 Min Line width/space 3mil
5 Max Withstand Voltage 4KV
6 Dimensions Tolerance (1) According to the request.(2) Tolerance +/-0.05mm ( without any instruction)
7 Min Hole D. 0.4mm
8 Type of Surface Finish Immersion Au/Ni

Clad laminates

  • Organic resin copper clad laminates
  • Metal-based copper clad laminates
  • Ceramic-based copper clad laminates


Thickness of copper clad laminate

  • Thick plate (the thickness range is 0.8-3.2 mm (containing copper)
  • Thin plate (the thickness range is less than 0.78 mm (excluding copper)

Reinforcement materials of copper clad laminates

  • Glass cloth based copper clad laminates
  • Paper based copper clad laminates
  • Composite based copper clad laminates (CME-1, CME-2)

Flame retardant grade.

  • Flame retardant plate
  • Non-flame retardant plate are classified

Tg

  • High Tg (Tg < 170 C), high dielectric properties, high CTI (CTI < 600V), environment-friendly copper clad laminates (halogen-free, antimony-free) and ultraviolet shielding copper clad laminates.

Copper Substrate/Aluminum Substrate

  • The surface of the power device is mounted on the circuit layer. The heat generated by the operation of the device is quickly transmitted to the metal base through the insulation layer, and then transferred by the metal base to achieve the heat dissipation of the device.
  • Compared with the traditional FR-4, the metal substrate can reduce the thermal resistance to the minimum, which makes the metal substrate has excellent thermal conductivity.
  • Compared with the thick-film ceramic circuit, its mechanical properties are excellent.

Metal substrates have the following unique advantages

  • Meet the requirements of RoHs.
  • It is more suitable for SMT process.
  • Thermal diffusion is treated effectively to reduce the operating temperature of the module, prolong the service life, and improve the power density and reliability.
  • Reduce the assembly of radiator and other hardware (including thermal interface materials)
  • Reduce product volume
  • Reduce hardware and assembly costs
  • Optimize the combination of power circuit and control circuit
  • Substitute the fragile ceramic with metal substrates for better mechanical durability

Metal Substrate Composition

Circuit Layer

Circuit layer (usually electrolytic copper foil) is etched to form a printed circuit for assembly and connection of devices. Compared with the traditional FR-4, with the same thickness and line width, the metal substrate can carry higher current.

Insulation layer

  • Insulation layer is the core technology of metal substrate, which mainly plays the function of bonding, insulation and heat conduction.
  • Metal substrate insulation layer is the largest thermal barrier in power module structure. The better the thermal conductivity of insulating layer is, the more conducive to the diffusion of heat generated during the operation of the device, the more conducive to reducing the operating temperature of the device, so as to achieve the purpose of increasing the power load of the module, reducing the volume, prolonging the life and increasing the power output.

Metal base

  • The choice of metal for insulating metal substrates depends on the comprehensive consideration of thermal expansion coefficient, thermal conductivity, strength, hardness, weight, surface state and cost of metal substrates.
  • Generally speaking, considering the cost and technical performance, metal sheet is an ideal choice.
  • Copper plate
  • Aluminum plate
  • Stainless steel plate
  • Iron plate
  • Silicon steel plate
  • Metal can be used if there are higher requirements for heat conductivity, mechanical properties, electrical properties and other special properties.

Four major differences between copper clad laminates and metal substrates

1. Heat dissipation

The heat dissipation of metal substrate is higher than that of copper clad plate. The heat dissipation of metal substrate and its insulation layer density, thermal conductivity, the thinner the insulation layer, the higher the thermal conductivity.

2. Mechanical function

Compared with copper clad laminate, metal substrate is better than copper clad laminate. Metal substrate has high mechanical strength and resistance, so it can be printed on the metal substrate.

3. Electromagnetic Shielding Function

Metal substrate can be used as shielding plate to shield electromagnetic wave, it is better than copper clad plate.

4. Coefficient of thermal expansion

The copper cladding is not easy to affect the quality of metal holes and wires. The thermal expansion coefficient of metal substrate is less than that of copper clad plate, which is helpful to ensure the quality and reliability of printed circuit board.

Why do you need metal copper substrate PCB?

  • With the increase of assembly density and integration of PCB components
  • The speed of signal transmission is accelerated, and the corresponding power consumption is also increased
  • In the era led by the 4G/5G network, RF signal needs excellent grounding function, and a request for heat dissipation will also be greatly improved. The function of ordinary rigid plate will not be able to satisfy its request.
  • Are you still worrying about the high power and heat dissipation of the equipment when planning the circuit?
  • Signal grounding is not good and easy to be disturbed and take a lot of trouble?
  • Why not consider choosing a very “grounding gas” metal copper substrate, and the question will be solved.
  • Copper substrate is a kind of copper-clad copper substrate, which is very similar to the whole structure of aluminum substrate. It has outstanding thermal conductivity, electrical insulation and mechanical processing functions, including metal layer, bonding layer (insulation layer), conductive wiring layer, three elements are indispensable. The metal layer (block) plays the primary role of heat dissipation, shielding, covering or grounding. Because of the difference between the functions of copper and aluminium and the corresponding PCB Machinable technology, copper substrates have more functional advantages than aluminium substrates.

Functional differences between copper and aluminium substrates

Superiority of thermal conductivity function

Under equal conditions:

Aluminum base: about 200 W/M.K.

Copper base: about 400 W/M.K.

From the thermal conductivity, we can intuitively see the advantages of heat dissipation of copper substrates over that of aluminium substrates.


PCB Machinable Functional Advantage

  • Because the copper base can etch precise graphics by etching circuit, the copper base can be processed into a convex platform, so that it can protrude to the line layer or the patch layer and the veneer surface is even, and the BOM components can be directly attached to the convex platform to achieve excellent grounding and heat dissipation.
  • Because of the factors of PCB processing technology, it is impossible to finish metallization directly on the aluminium base surface (e.g. single-sided aluminium base plate), while the copper base can be processed into metallization holes, which makes the corresponding single or multi-layer backplane have excellent optional grounding function, and the copper itself has weldable function, which makes the planned structure possible. Welding is optional for final installation, which is much better than heat sink.
  • Because of the difference of elastic modulus between copper and aluminium (the elastic modulus of copper is about 121000 MPa and that of aluminium is 72000 MPa), the warpage and expansion of copper substrates are smaller than that of aluminium substrates, and the functions of copper substrates are more stable.

Copper Substrate

  • Its thermal conductivity is many times better than that of aluminium and iron substrates.
  • It is suitable for high frequency circuits
  • High and low temperature areas
  • Precise communication equipment in heat dissipation and building decoration industries.
  • Generally, there are gold-deposited copper substrate, silver-plated copper substrate, tin-sprayed copper substrate, antioxidant copper substrate and so on.
  • The circuit layer of copper substrates requires great current-carrying capacity, so thick copper foil with a thickness of 35 to 280 microns should be used.
  • Thermal insulation layer is the core technology of copper substrates. The core thermal conductive parts are aluminium trioxide and silicon powder and epoxy resin filled polymer, with low thermal resistance (0.15), excellent viscoelastic properties. It has the ability to resist thermal aging and can withstand mechanical and thermal stresses.
  • Copper base metal is the supporting part of copper base plate, which requires high thermal conductivity.
  • It is suitable for conventional mechanical processing such as drilling, punching and cutting, etc.

Aluminum Substrate

  • The board made of aluminium base material is called aluminium base plate. Because of its strong heat dissipation ability, this kind of board is commonly used in LED lighting products. There are both positive and negative sides, the white side is welded LED pins, the other side presents the color of aluminum, usually coated with thermal conductive slurry after contact with the thermal conductive part.
  • Aluminum substrate is a kind of metal-based copper clad laminate with good heat dissipation function. Generally, single panel consists of three layers, namely circuit layer (copper foil), insulation layer and metal base.
  • Used for high-end use is also designed for double layers, the structure is circuit layer, insulation layer, aluminum base, insulation layer, circuit layer.
  • Very few applications are multi-layer boards, which can be made by bonding ordinary multi-layer boards with insulating layer and aluminium base.

Rules for design of copper base plate

  • Because of the thicker copper base, the minimum drilling tool diameter must be 0.4 mm. Line width spacing is determined by the thickness of copper foil on copper base plate.
  • The thicker the thickness of copper foil, the wider the thinnest line width required and the wider the minimum spacing required.
  • Please contact us If you are interested in more design rules. Mail us: info@hifipcb.com