Aluminum PCBs can be referred to as printed circuit boards containing a conductive material. The development of Aluminum PCBs can be traced back to the 1970s. After their development, there was an increase in their demand dramatically. They were first applied in Amplification Hybrid Circuits. Presently, they are utilized on a larger scale. It is very important that we have some knowledge about Aluminum PCB, and the role they play in our community.
All designs of unbending and flexible printed circuit boards are different. They are usually customized to help meet the purpose of the board. The same holds true for the base material of the printed circuit board. One well-known base material is fiberglass. However, aluminum PCBs are very useful in different applications. The aluminum PCB has excellent thermal conductivity and electrical insulation, is metal-based, and delivers great performance.
How are Aluminum PCB Made?
Aluminum PCBs are made up of metal-based seals, which are covered by circuit layers. Also, they are composed of alloy plates, which combine silumin, aluminum, and magnesium. Aluminum PCBs offer great machining performance, high electrical insulation, and great thermal potential. Also, they are different in many important ways when compared to other printed circuit boards.
Thermal Insulation Layers
These layers are very important modules of a printed circuit board. It is composed of a ceramic polymer, which is known to possess viscoelastic properties, great thermal resistance, and also defends the printed board against any thermal and mechanical stresses.
The base is made up of aluminum alloy substrate. Utilizing aluminum ensures that this printed circuit board is a great option for the through-hole technology.
The circuit layer is made up of copper foil. Most times, PCB manufacturers utilize copper foils that extend between 1 – 10 ounces. Heat is absorbed by the dielectric insulation layer. This happens as current passes via the circuits. Then, it is transferred to the aluminum layer to get the heat dispersed.
Printed circuit boards having improved thermal resistance will extend the lifespan of your completed product. Manufacturers with high skill will offer you part reliability, superior protection, and heat mitigation.
Why do we make use of Aluminum in Circuit Boards?
This use of aluminum in circuit boards is necessary because aluminum does a great job in transferring heat from important components. Therefore, it reduces the harm that could have come to the circuit board.
Another reason why aluminum is used is because it has higher durability. With aluminum, you get the durability and strength for your product, which is lacking in fiberglass or ceramic bases.
The Printed Circuit Board Evolution
Printed circuit boards are similar to the electrical systems, which was introduced back in the 1850s. Back then, rods or metal strips connected huge electric components that were installed on bases made of wood. With time, wires that were connected to screw terminals took the place of metal chassis and metal strips, which were used instead of wooden bases.
Although these technological advances were significant, the systems seemed too large to meet the increasing need for more compact and smaller designs, which were demanded by products using the circuit boards.
With this demand, United States’ Charles Ducas became inspired and decided to create a stencil having conductive links, which could directly print the electrical paths on surfaces that are insulated. In 1925, he submitted a patent regarding the whole process, which led to the two phrases “printed circuit” and “printed wiring”.
In 1943, the method was developed and patented to etch circuits onto copper foil layers that were joined to non-conductive base materials which were glass reinforced. This technique, which was created by United Kingdom’s Paul Eisler gained wide popularity back in 1950, which was made possible with the creation of transistors for use commercially. Until then, vacuum tubes, as well as other components were large enough that just wiring and traditional mounting methods were needed.
However, with transistors, everything changed. Components reduced in size greatly. Manufacturers also wanted to reduce the electronic packages’ overall size by switching to printed circuit boards.
When through-hole technology was introduced, as well as its usefulness in multi-layer printed circuit boards back in the 1960s, this led to an increase in the density of the component as well as electrical paths that are tightly-spaced. This resulted in a new beginning for PCB design.
The Structure of an Aluminum PCB
Aluminum printed circuit boards have similar characteristics to the FR4 printed circuit boards. The Aluminum PCB’s basic structure is four layers. It is made up of a metal copper foil, a base membrane made of aluminum, a base layer made of aluminum, and a dielectric layer.
Copper Foil Layer
Copper layer used is thicker compared to the usual CCLs. Having a thicker copper layer means there is a higher carrying capacity for the current.
This layer is thermally conductive, and its thickness falls between 50 micrometer and 200 micrometer. Its thermal resistance is also low and it is great for its application.
The aluminum base layer is composed of aluminum substrate pcb. This base has a high thermal conductivity. It has a selective membrane. It also plays defensively keeping the exterior of the aluminum safe from scraping and etching. This is of two types. It is either below 120 degrees or about 250 degrees.
Types of Aluminum PCB
So far, power and LED converter companies are known to be the largest aluminum PCB users. However, automotive and radio frequency companies also utilize this type of PCB. Also more common is the single-layer construction. This is because of its simple nature. However, other configurations are offered.
Through-Hole Aluminum PCBs
For structures that are highly complex, a single aluminum layer can form the major core of thermal structure with many sides. For through-hole printed circuit boards, the aluminum is first drilled. Also dielectric is used in back-filling the hole before the process of lamination takes place.
Next, the sub assemblies or thermal materials are laminated to the aluminum sides with the materials for thermal bonding. After the lamination, the assembly is then thru-drilled to look like a multilayer printed circuit board. Then, plated-through holes are passed through the aluminum clearances to offer electrical insulation.
Flexible Aluminum PCBs
The flexible dielectric is a new development in the IMS – Insulated Metal Substrate materials. These materials have polyimide resin and ceramic fillers and offer greater flexibility, thermal conductivity, and electrical insulation.
When utilized with aluminum materials that are flexible like 5754, the printed circuit board can get rid of expensive items like connectors, fixtures, and cables. Although they are flexible materials, they can be bent and stay in place for life. The flexible aluminum pcbs shouldn’t be used for applications requiring the frequent flexing of the materials.
Hybrid Aluminum PCBs
The best type of application for the hybrid aluminum PCB is in RF applications. Why this is so is because, they provide higher thermal performance, most especially when it is used in a standard FR4 product.
Hybrid aluminum printed circuit boards usually entail the separate processing of non-thermal materials. Then, it is applied to a thermal material having a base made of aluminum. Binding here offers rigidity and strength to the aluminum PCB. It also plays a role in the dissipation of heat. Another advantage here is that you can bond a thermal material with one that is non-thermal.
Why this is so is because it’s thermal conductance is great. Also, concerning production, it costs less. When manufacturing hybrid aluminum printed circuit boards, there’s no need for any assembly or heat sink.
High Conductivity Aluminum Printed Circuit Board
You can make use of high conductivity aluminum printed circuit boards in manufacturing equipment requiring high input of power. The aluminum’s characteristics ensure it fits perfectly to these applications’ usage. This aluminum type can either be in double or single layers. This depends on your usage.
Aluminum Nitride Ceramic Printed Circuit Board
This aluminum substrate pcb material is widely used because it has the ability to have high thermal conductivity. When this is combined with a high dielectric strength coupled with low expansion, then you will produce a PCB that stands out.
This PCB can be applied while producing high-power ICs, sensors, aluminum pcb for LEDs, as well as other components. Several benefits come with using the aluminum nitride ceramic printed circuit board. These include its high temperature of operation, strong dielectric, low coefficient of expansion, and smaller size of package as a result of integration.
The application you are making use of, as well as your desired design, will determine if you should print your circuit using silver or copper.
Once again, you may have a double or single-layer aluminum nitride board.
Difficulties Encountered when Manufacturing Aluminum PCBs
All aluminum pcbs have a similar manufacturing process. In this chapter, we will be discussing the main processes in manufacturing, the issues, as well as their solutions.
Aluminum PCB’s copper foil is a bit thicker. So if this copper foil is more than 3-oz, then the etching needs width settlement. The fact is if it doesn’t work according to the design’s demand, then after etching the trace width stays out of tolerance. One good reason why the compensation of the trace width is done accurately. You have to control the etching factors while manufacturing is on.
Mechanical manufacturing involves some processes, which includes mechanical drilling, molding, v-scoring, and more. This usually decreases electrical strength. This is why the electric and professional milling cutters are utilized for producing low-volume of products. So also, the parameters of drilling have to be adjusted. This prevents the generation of burr. It will also help during mechanical manufacturing.
Printing of the Solder Mask
As a result of the thick copper foil, the aluminum PCB’s solder mask printing usually comes with a difficulty. Why is this so? If the thickness of the trace copper becomes too much, then the etched image will possess a great difference between the trace surface and the base board. This is what makes the printing of the solder mask quite difficult.
This is why the two-time printing of the solder mask is usually used. The oil of the solder mask should have decent quality. Also, in some other cases, the filling of the resin is handled first before the solder mask.
Benefits of Aluminum PCBs
Aluminum printed circuit boards usually come with some benefits compared to the use of other materials as the base.
It is less expensive
The fact is aluminum is easily mined and refined and this is why it is native to many climates. This is why, mining and refining it, is also less expensive compared to other metals. Regarding extension, the costs involved in manufacturing, which are related to aluminum PCB products, are less expensive as well. Compared to heat sinks, aluminum PCBs are less expensive as well.
Better transfer of heat
One reason why electronics could have serious damage is high temperatures. With Aluminum, you can be sure that heat is conducted and transferred away from areas that are dangerous. This, in turn, reduces the possible damage that can be brought to your printed circuit board.
Aluminum can be recycled. All producers, down to the purchasers can make use of Aluminum PCBs because it ensures that the planet stays healthy.
Due to the durability of aluminum, it is extremely lightweight. Also, it adds strength and resilience to the printed circuit board without putting more weight on the PCB.
Although power converters and lighting projects are known as the greatest users of printed circuit boards that are metal based, countless different users exist. Every supplier of the Aluminum core PCB should assist customers in assessing their requirements for thermal control and insulation. Aluminum core printed circuit boards are used classically with White or Black solder masks.
Compared to other base materials like ceramic and fiberglass, aluminum is more durable and tougher. It reduces any possible accidental breakage, which could occur all through the process of manufacturing, as well as during everyday use and handling.
Application of Aluminum PCB
Aluminum PCBs are great for situations where the dissipation requirements of thermal heat are extremely high.
Aluminum PCB is very functional at directing away thermal energy from the components of printed circuit boards. Therefore, it offers better management of temperature for any PCB design. As regards getting rid of thermal energy from components of circuit boards, designs that are aluminum backed could be ten times much more effective compared to designs backed with fiberglass. This higher rate of thermal dissipation ensures the implementation of higher density and higher power designs.
Aluminum PCBs are used frequently for High power dissipation
Aluminum PCBs have gained wide recognition in automotive lighting, LED applications, general lighting, and traffic lights. Using aluminum designs permits the LED density in the structure of the printed circuit board to increase. It also allows aluminum pcb for LEDs that are mounted to operate at currents that are higher, while remaining within specific tolerances of temperature.