Aluminum-based copper-clad PCB has aluminum as a base material along with other materials, including a dielectric layer, and thermal and insulating material.
Some other terms also refer to aluminum copper PCB, such as a metal-clad PCB, aluminum base, an insulated metal substrate, aluminum clad, etc.
The Reason for Using an Aluminum PCB
Aluminum PCB started in the 1970s and has developed a lot so far. It is ideal for applications with heat dissipation because it helps manage temperature as it transfers the heat far from important PCB components. It has a longer lifespan than fiberglass because of its high durability.
Components of Aluminum PCB
Aluminum PCB has an insulated metal structure (IMS) having different layers with different functions and materials. Let’s study them one by one.
It is also known as circuit copper which consists of copper foil with 1 to 10 ounces of thickness or weight. The manufacturing of this layer involves the etching of copper which is essential for a board. The copper layer helps in PCB assembly and the device connection to enhance their function. As it’s an IMS, so the base layer has a high current. The width and thickness of this layer are similar to anFR4.
Also known as a dielectric layer, the insulation prevents heat. The thickness of this layer ranges from 50µm to 200µm. Other than insulation, the layer helps in bonding. Moreover, it dissipates heat that occurs when there is a flow of current.
Metal Base Layer
The metal base or a substrate helps differentiate anIMS from another kind of printed circuit board.Besides, the insulating layer has an aluminum base. While looking for a metal plate, you must consider its cost, strength,thermal conductivity, thermal coefficient, mass, as well as a strong point.In other words, the aluminum plate has all these qualities. You can also increase its effectiveness in terms of mechanical properties and conductivity by adding iron, copper, or silicon steel.
The membrane layer has an aluminum alloy base to protect it from unwanted scraping or etching. The thickness of the layer is often 1mm, whereas its temperature is either 250 degrees or it’s less than 120 degrees, depending on the intensity of the heat.
Classification of Aluminum Clad PCB
Though the main purpose of all aluminum PCBs is heat dissipation, different types come up with different structures and designs. Let’s discuss all types of aluminum-clad circuit boards.
Flexible Aluminum Printed Circuit Board
The flexible PCB is an integration of polyamide resin and ceramic during the pcb fabrication. Both materials provide heat insulation, thermal efficiency, and flexibility like you can fold them as you want. A flexible aluminum PCB is cheaper than others, as you don’t need to buy connectors. However, you can’t change the final product in this case.
Through-Hole Aluminum Printed Circuit Board
A through-hole aluminum circuit board involves the backfilling and pre-drilling of one aluminum layer. After that, the laminate material is applied, leading to the construction of a core with several layers. Later on, both sides of the board are laminated with thermal bonding. Then, in the end, it comes drilling.
Multilayer Aluminum PCB
Such a PCB has many thermally conductive layers. Its design consists of circuitry layers present in the dielectric with blind vias or thermal vias.
It is ideal for complex circuits, like power supply products. But, it is expensive and does not suit a PCB having a single-layer layout.
Aluminum PCB with A High Thermal Conductivity
Such a PCB has epoxy resin as insulation. So, the material should have a high thermal conductivity in this case.
Aluminum PCBwith A High Frequency
Such a type of PCB has insulation of polyamide or the layer has fiberglass inserted between the epoxy resins. Both materials make a PCB flexible and easy to assemble.
Pros of Aluminum PCB
- Aluminum PCB is good for some applications, but it does have some weaknesses. However, it is better than a traditional circuit board in many ways. Let’s look at its benefits in terms of performance and thermal conductivity.
- Many PCB materials are poor conductors when it comes to high thermal temperatures. Such a high temperature can damage the electrical components. The aluminum substrate covers the damage in such situations.
- There is a common issue of thermal expansion and contraction in SMT assembly. But, aluminum PCB can resolve these issues, enhancing a circuit board and making it long-lasting.
- A PCB with aninsulating substrate is not that stable, but the aluminum substrate makes it stable. Like, the heat can’t change a circuit board’s dimensions much if it has an aluminum substrate. In other words, a board’s dimensions can change up to 2 to 3%, if it gets heated up to 30° C to 140 – 150° C.
- The aluminum PCB is a better alternative to a PCB with a ceramic substrate as it is brittle. Besides, aluminum increases the heat resistance and physical properties of a circuit board and reduces the fabrication cost and workload.
Other Benefits of Aluminum Copper Clad PCB
- Aluminum PCB is lightweight though it’s highly durable. It gives strength to a PCB without increasing its weight.
- Unlikefiberglass and ceramic, thealuminum core makes a circuit board durable by enhancing its strength.
- It prevents accidental damage that often occurs during manufacturing.
- Aluminum PCB is friendly toits surrounding environment. It is recyclable and free from toxins. The assembly of an aluminum PCB involves less energy, and it is healthy for the planet.
- Aluminum mining and refining cost are less than other metals. So, the end products having aluminum PCBs become less costly.
Cons of Aluminum-Based Copper Clad PCB
- In certain cases, aluminum PCB becomes expensive.
- It is hard to have a double-sided aluminum PCB, as most manufacturers can only make a single-sided aluminum PCB.
- It is vulnerable to halide ions, especially chloride, and gets affected faster than other circuit boards.
Some Common Applications of Aluminum PCB
There are many applications of aluminum PCB, especially they are ideal for technological equipment and devices, such as:
- Regulators and converters such as DV/AC are used as power supply equipment.
- Power amplifiers, as well as the input and output amplifiers, including audio equipment.
- Communication devices or electronic equipment. High-frequency amplifiers.
- Automation equipment used in offices, such as a motor driver.
- Power re-fillers, solidrelays, rectifierbridges, and converters of power modules.
- Power supply devices used in computers, such as motherboards, disk drives, and many others.
- Electronic control components, including transistor base, relays, etc.
- LED has two-mode displays, and energy-saving LEDs
- Parts of industrial vehicles, such as the automatic safety system, ignition, lighting converter, and voltage regulator.
Aluminum PCB Manufacturing Issues
1- Copper Etching Issues
A circuit layer should have a thick copper foil. The thickness of up to 3ozcauses a challenge, as you have to compensate in terms of etching width. But, if you fail in this case, the width would affect the etching. So, you have to manage the etching parameters.
2-Poor Solder Mask Printing
Sometimes in an aluminum-clad PCB, the thickness of the copper foil affects thesolder mask printing. When the trace copper is thick, it makes the etched image different in the baseboard and trace surface, making the printing process hard. You can resolve this issue with a good solder mask oil or filling in the resin is also an option,but it should be prior to the solder mask.
While making an IMS, the manufacturer uses mechanical drilling. Moreover, it involves molding as well as V-Scoring, like on internal vias. But, such drilling reduces the electrical strength of the board. You can avoid it if you use a special cutter for milling andelectric milling, especially forlow-volume production.It is also essential to eliminate the burr production that you can do by adjusting the drilling parameters.
4-Aluminum PCB Storage Issue
Sometimes you have to store the aluminum PCB before using it, but it can change its color making it black or yellow. So, you must place the PCB in a moist-free room to avoid any suchdamage. It would be better to use an aluminum PCB within 48 hours of unboxing it.
What Is An Aluminum-Based Copper Clad PCB?
As the name shows, aluminum-based copper-clad PCB has aluminum as a base material. Whereas it has other materials, such as the dielectric layer, and thermal and insulating material.
Is Aluminum PCB Expensive?
Though aluminum plate is cheap, the manufacturing and assembly process of the PCB makes it expensive.
What Are The Benefits Of An Aluminum PCB?
Aluminum-clad PCB helps manage temperature as it transfers the heat far from other PCB components. It has a longer lifespan than fiberglass and resin.
What Are the Manufacturing Issues Of Aluminum PCBs?
Some common manufacturing problems with aluminum PCBs are copper etching, poor solder mask printing, and poor electrical strength due tomechanical drilling.
In general, aluminum PCBs are cheap and provide better heat dissipation than other materials. It uses surface mount technology and has a less production volume than other circuit boards. It consists of different layers and it has a wide application.
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