The Metal Core Printed Circuit is used specifically in applications where it demands efficient heat dissipation, such as the following applications: LED lighting, Motors, High Power Circuits, etc. Regardless of the design for which the metal core printed circuit board is intended, it is important that it is designed and particularly thought out so that all its characteristics are considered, and that its cost-benefit ratio is evaluated.
What is the Metal Core Printed Circuit Board?
The metal core printed circuit is composed of a copper laminate where the circuit tracks will be printed, which contains as electrical insulator a very thin composite of ceramic and fiberglass and as a heat sink a thicker layer of aluminum. This material cannot be composed of metallic holes, that is, it must be built in a single face – single face – limiting the characteristics of the circuit
The great advantage of the printed metalcore circuit is that it is produced according to the design of each client; they are fully personalized, following the characteristics and specifications that are defined by the consumer. Generally, the quality of the products depends on the type of raw material and suppliers used. Therefore, it is important to look for a specialized company when purchasing the metalcore printed circuit, which in the manufacturing stage obeys the rules of the IPC 6012 safety standard.
These factors are important, because a metalcore printed circuit that is not well installed or does not work correctly can damage equipment, cause accidents and even paralyze the entire manufacturing process, causing several losses.
For customers looking for the acquisition of the highest quality metalcore printed circuit , they should look for a renowned manufacturer in the market such as Micropress, a reference company in the printed circuit segment.
Metal Core Printed Circuit is on Micropress
Micropress specializes in the manufacture of prototypes of printed circuit boards and works with advanced technologies, quality and agility. With several years of experience, it is recognized for quality and efficiency. Its service covers the entire national territory, in addition to being totally personalized, always looking for new solutions to meet the customer’s needs, offering technical support and committed to the stipulated deadlines.
Pay Attention to the Evolution of Printed Circuit Boards
In the first place, the basic reason why printed circuit boards came to be used was to reduce the cost of manual solder wiring. The earliest printed circuit boards were made of paper impregnated with phenolic resin. This paper phenolic substrate is a flame-retardant grade of a copper-clad laminate that is widely used at present, and is classified by an index of FR-1 or FR-2.
Since phenolic resin and epoxy resin are thermosetting resins, they have the property of being able to achieve favorable rigidity as a base material for printed circuit boards. However, paper is prone to cracking and tearing when subjected to a large load.
A little Historical Background of PCB Board Manufacturing
In 1974, General Motors’ truck division, GMC Truck, designed a printed circuit board with a ballast resistor for the ignition system mounted on a paper phenolic substrate. The substrate worked fine under normal mechanical and thermal loads.
However, the vehicle assembler did not anticipate the load that would be applied when connecting the wire harness connector to the board. As a result, the printed circuit board was damaged during the manufacturing stage, causing a warranty problem before entering the market competition.
General Motors is not the only one facing the structural limitations of paper phenolic substrates. Around 1980, Ford Motor had a similar problem with the ignition module. The module was made of 5 x 8 inch (12.7 x 20.32 cm) zinc die-cast and contained a paper phenolic board with timing, logic and drive circuits to ignite the spark plug.
This module, which worked well in the development stage, was distorted due to temperature changes in the paper phenol substrate when it actually entered the mass production stage, causing cracks in the wiring. This caused a serious failure of the ignition system, causing the vehicle to get stuck on the road.
Ford’s management believed that it would be costly to switch the module’s paper phenolic substrate to a FR-4 substrate with a fiberglass cloth impregnated with epoxy resin. The countermeasure taken there is to put an appropriate amount of sand in the module and then perform potting (resin filling). As a result, the heat mass increased and the cushioning effect was obtained, so the failure rate within the warranty period could be suppressed to 5% or less. The failure rate of 5% or less was the highest among the parts used in Ford vehicles.
Why FR4 Board is the Top Choice of Mmetal Core PCB Manufacturers?
Today, FR-4 boards are widely used in consumer devices, PCs, communication devices, automobiles, and mobile devices. The price difference between paper phenolic substrates and FR-4 substrates is no longer as large as it was in the 1980s.
It should be noted that the FR-4 board is becoming more multi-layered. The number of layers has increased from single layer and 2 layers to 8 layers and 12 layers, and now 26 layers have appeared. The demand for these FR-4 multilayer boards was boosted by PC motherboards. However, due to the integration of chipsets and the adoption of serial buses such as PCI Express, some recent PC motherboard boards have only 6 to 8 layers.
The miniaturization of the circuit line width of printed circuit boards has progressed to the point where 4 mils (about 0.1 mm: 1 mil is about 25 μm) have become common. It is also possible to make the line width and spacing of the circuit 2 mils (0.05 mm) each by performing special processing. In addition, the state-of-the-art manufacturing plant has achieved a circuit line width of 1.25 mil (about 0.03 mm).
Demand for multilayer boards for PCs may have declined, but demand for multilayer boards for consumer devices, servers, and mobile phone base stations remains high. In a multilayer board, the technology for processing via holes connecting the layers of a printed circuit board is more important than the miniaturization of the circuit line width.
For example, there are blind vias having through holes on only one side of the printed circuit board, embedded vias connecting the layers inside the substrate, and the like. Recently, microfabrication of these via holes has become possible. For example, if you use the latest laser drill, you can make a hole with a diameter of about 2.5 mil (about 0.06 mm) on a printed circuit board. In addition, supplier printed circuit board manufacturing equipment such as Sierra Proto Express can drill holes with a diameter of 4 mils (about 0.1 mm) while machining.
In addition to the printed circuit board manufacturing technology, the base material itself is also evolving. Teflon and polyamide are the most suitable base resin for circuits with high operating frequencies. These resins have a low dielectric constant and have low loss when transmitting high frequency signals. However, some manufacturers, such as Sanmina SCI, use FR-4 on the top layer of the printed circuit board.
The thickness of this FR-4 can be 4 mils (about 0.1 mm) or 2 mils (about 0.05 mm). This means that the ground plane can be installed 4 mils from the signal line. Assuming that the dielectric constant of FR-4 is 4, the signal line can clear the characteristic impedance of 50Ω if the line width is up to twice the distance between the signal line and the ground plane. For example, when FR-4 with a thickness of 4 mils is used for the uppermost layer, the signal line has a characteristic impedance of 50 Ω if the line width is 8 mils (about 0.2 mm) or less.
Example of metal core printed circuit board It is possible to partially remove the dielectric material or create a flange-like shape. (Exhibitor: The Bergquist Company)
Currently, many printed circuit board manufacturers are focusing on developing products that incorporate ICs and passive components. The component-embedded board can effectively utilize the space on the upper surface and the lower surface of the printed circuit board, which is useful for miniaturizing the device.
Metal Core PCB Fabrication and its Thickness
Another notable technology is the metal core printed circuit board, which is manufactured based on metal. The biggest feature is high heat dissipation characteristics. It has 9 times more heat dissipation characteristics than a general FR-4 board. This metalcore printed circuit board has come into the limelight with the advent of LED lighting.
In addition to being able to dissipate heat efficiently, it also has high rigidity. Copper, aluminum, iron, etc. are used as the base metal (metal core). The thickness of the metal core is generally 30 to 125 mils (0.75 to 3.125 mm). Another advantage is that it is easy to process to the special specifications and shapes required by customers ( Fig. 4 ).
Advanced technology is required to manufacture metal core printed circuit boards. However, it has the potential to easily solve the problem of heat dissipation not only in LED lighting but also in automobiles and solar power generation systems. In fact, there are cases where the power amplifier is cooled without a fan by utilizing a metal core printed circuit board for mobile phone base stations.
When a copper core board is used, the copper core and through holes can be electrically connected, so it can be used as a three-layer board such as a ground or a through hole for heat conduction. The through hole can also be used as a heat transport path, and the heat of high heat generating parts can be instantly diffused to the core with the thermal conductivity of copper. Furthermore, by providing a slit in the copper core, it can be used as a power supply and ground for two systems. (Fig 5: It is necessary to pay attention to the arrangement of parts in consideration of the deterioration of heat diffusion performance due to slits.)
Metal Core Board
By carving out the board so that the metal core is exposed, and directly mounting heat-dissipating parts such as heat sinks there or directly transporting heat to the housing, the heat of parts operating at high temperatures can be efficiently released to the outside.
It is not enough to stick a metal substrate to metal. The difference in performance depends greatly on the insulating resin used.
There are [ thermal conductivity], [withstand voltage], and [insulation layer thickness] as important factors, and it is necessary to select the optimum insulation resin depending on the application.
For example, the thermal conductivity of FR-4 Gala Epo resin, which is most used in printed circuit boards, is said to be 0.36 W / mK, but even the low-cost popular type we use has achieved 1.8 W / mK. , It has about 4 times the thermal conductivity. By using an insulating resin with excellent thermal conductivity, rapid heat transfer is possible without storing heat.
Multi-layer & Metal Base Board
This is a multi-layer compatible metal base board that has evolved from the conventional “single-sided metal base board” and enables circuit configurations with two or more layers.
Conventional single-sided wiring has become difficult due to higher density wiring, smaller boards, and RGB support. We have realized a multi-layer metal base without losing the basic performance of the single-sided base type.
Applications / application examples
- As a printed circuit board for LED heat dissipation measures such as traffic lights and outdoor bulletin boards
- Draw out performance exceeding the rated current of high-brightness LEDs and power devices
- Reliability measures for electronic components due to heat
- EMI measures using metal shielding
- Replacement from ceramic substrates with an emphasis on cost and impact resistance
- Electronic control in a high temperature environment when used in combination with a cooling unit
- Heat dissipation measures for power devices that generate a large amount of heat, such as IGBTs and power MOSFETs, and measures for reliability of electronic components due to heat
- Reduction of assembly cost and space saving by built-in bus bar (copper core substrate)
- Low capacitance, large current electromagnetic field control by microstrip structure (copper core substrate)
A printed circuit board with enhanced heat dissipation and heat resistance. A metal base board with a circuit formed on the metal plate, and a metal plate sandwiched inside the board. There are two types of metal core boards, and the metal material can be selected from aluminum and copper.