What is Aluminum PCB?

An aluminum PCB has a similar layout to any other PCB. It has a layer or layers of copper, solder mask and silkscreen layered over it. Instead of having a fiberglass or plastic substrate, though, an aluminum circuit board has a metal substrate. This base mainly contains a combination of aluminum. The metal core can consist entirely of metal or have a combination of fiberglass and aluminum. Aluminum PCBs typically are single sided, but can be double sided as well. Mulilayer Aluminum PCBs are highly difficult to manufacture.

Aluminum boards get the most use in LED and power converting electronics. The intense light produced by LEDs creates high levels of heat, which aluminum directs away from components. An aluminum PCB extends the lifespan of an LED device and provides more stability. You can find aluminum substrates in street lights, stop lights and household lighting. They allow power converters to change currents and regulate electronics. Creators in many other industries also find use in aluminum circuit boards, but they don't implement them as often.

Why is Aluminium Used in Circuit Boards?

Aluminum can actually transfer heat away from vital components, thus minimizing the harmful effect it could have on the print circuit board. Higher durability: Aluminum provides strength and durability to a product that ceramic or fiberglass bases cannot.

Advantages and Disadvantages of Aluminum PCB

Aluminum boards are one of the most thermally conductive PCB options. They keep as much heat away from vital components as possible to ensure minimal circuit damage. Thanks to their high heat tolerance, they can handle higher density circuits and larger power levels. Substrates created from aluminum alloys have a high level of physical durability that lowers the risk of breakage. Compared to other metals, aluminum has a lower environmental impact in addition to a reasonable cost.

On the other hand, aluminum PCBs tend to have more niche uses than standard boards. While they cost less than adding conductors to a copper board, they have a higher price than standard PCBs without those components. Investing in an aluminum core may not pay off if your application doesn’t involve high temperatures. If you plan on creating a flex circuit,  flexible PCBs can only flex into its initial position. It will bend to fit into smaller electronics, but it won’t withstand the stress of vibration.

Performance of Aluminum PCB

1. Thermal Dissipation

Common PCB substrates, such as PCB material FR4, CEM3 are poor conductors of thermal. If the heat of electronic equipments cannot be distributed in time, it will result in high temperature failure of electronic components. Aluminum substrates can solve this thermal dissipation problem.

2. Thermal Expansion

Aluminum substrate PCB can effectively solve the thermal dissipation problem, so that the thermal expansion and contraction problem of components on printed circuit boards with different substances can be alleviated, which improves the durability and reliability of whole machine and electronic equipments. In particular, aluminum substrate can solve the SMT (surface mount technology) thermal expansion and contraction problems.

3. Dimensional Stability

Aluminum substrate printed circuit board has apparently higher stability than the insulating material of the printed circuit board. When heated from 30 ° C to 140 ~ 150 ° C, the dimensional change of aluminum substrate is only 2.5 ~ 3.0%.

4. Other Performance

Aluminum substrate printed circuit board has shielding effect, and can alternative brittle ceramic substrate. Aluminum substrate also helps to improve the heat resistance and physical properties and reduce production costs and labor.

Structure of Aluminum PCB

Aluminum PCBs are aluminum based CCLs (CCL is a type of base material of PCBs). AluminumPCBs are actually quite similar to FR4 PCBs. The basic structure of Aluminum PCBs is four layered. It consists of a layer of copper foil, a dielectric layer, an aluminum base layer and aluminum base membrane.

• Copper Foil Layer: the copper layer used is relatively thicker than normal CCLs ( 1oz-10oz). A thicker layer of copper means a larger current carrying capacity.

• Dielectric Layer: the Dielectric layer is a thermally conductive layer and is around 50μm to 200μm thick. It had a low thermal resistance and it suitable for its application.

• Aluminum Base: The third layer isthe aluminum base which is made up of aluminum substrate. It has a high thermal conductivity.

• Aluminum Base Membrane Layer: Aluminum base membrane is selective. It has a protective role by keeping the aluminum surface safe from scraping and unwanted etching. It is of two types i.e. Lower than 120 degree or around 250 degrees (anti high temperature).

Classification of Aluminum PCB

Aluminum PCBs are essentially divided into three categories.

1. Universal Aluminum PCB: the dielectric layer used here is made up of epoxy glass fiber pre-preg.

2. High Thermal-Conductive Aluminum PCB: the dielectric layer is made up of epoxy resin. The resin used must have high thermal conductivity.

3. High-frequency Aluminum PCB: the dielectric layer is composed of polyolefin or polyimide resin glass fiber pre-preg.

Manufacturing Difficulties of Aluminum PCB

The manufacturing process for nearly all aluminum PCBs is essentially the same. Here we will discuss the major manufacturing processes, the difficulties and their solutions.

1. Copper Etching: the copper foil used in Aluminum PCBs is comparatively thicker. If the copper foil is over 3oz however, the etching requires width compensation. If it is not according to the demand of the design, the trace width will be out of tolerance after etching. Therefore the trace width compensation should be designed accurately. The etching factors need to be controlled during manufacturing process.

2. Solder Mask Printing: due to the thick copper foil there is a difficulty in solder mask printing of aluminum PCB. This is because if the trace copper is too thick then the image etched will have a large difference between trace surface and base board and solder mask printing will be difficult. Therefore, the two-time soldermask printing is used. The solder mask oil used should be of good quality and in some cases the resin filling is done first and then solder mask.

3. Mechanical Manufacturing: the mechanical manufacturing process involves mechanical drilling, molding and v-scoring etc. which Is left on internal via. This tends to reduce electrical strength. Therefore, the electric milling and professional milling cutter should be utilized for low-volume manufacturing of products. The drilling parameters should be adjusted to prevent burr from generating. This will help your mechanical manufacturing.

Applications of Aluminum PCB

Aluminum base has good thermal dissipation function. Because the LED will generate a lot of heat, the printed circuit board for the LED lamp is generally aluminum substrate. 

1. Audio equipments: input and output amplifiers, balanced amplifiers, audio amplifiers, preamplifiers, power amplifiers and so on.

2. Power supply equipments: stabilizer, conditioner, DC-AC adapter and so on.

3. Communication electronic equipments: high-frequency amplifiers, filter electrical circuit.

4. Office automatic equipments: motor driver and so on.

5. Computer: power supply device, floppy disk drive, motherboard and so on.

6. Power modules: inverters, solid relays, rectifier bridges and so on.

7. Electronic control: relays, transistor base, a variety of components in the circuit.

8. Switches, microwave: radiator, semiconductor devices, thermal insulation and motor controller.

9. Industrial vehicles: ignition, voltage regulator, automatic safety control system, lighting conversion system.

10. LED Display (two modes: LED display; display with LED light source)

11. Lighting: With the promotion of energy-saving lamps, a variety of energy-saving LED lights are welcomed by the market, so the aluminum substrates for LED lights have large-scale applications.

ALLPCB: A Reliable Aluminum PCB Manufacturer

ALLPCB, one of the largest PCB manufacturers in China. ALLPCB offers one-stop services for electronic manufacturing, including PCB fabrication, components sourcing, SMT, and assembly.

ALLPCB has been manufacturing aluminum PCBs for decades. Our full feature aluminum circuit boards making capabilities and Free DFM Check allows you to get high-quality aluminum PCBs done within budget. Our printed Aluminum PCBs are widely used for LED lighting, power equipment and automotive systems. With the new user promotion, you can get Aluminum PCB prototype for only 1$. Get quote today to start!