PCBs and Their Applications in the LED Lighting Industry
Printed circuit boards, or PCBs, are everywhere in our technology-based society. Everything from computers to medical equipment to cars contains these PCBs in one form or another. However, not all PCBs are the same— many of them use different designs or materials to suit a unique purpose. The base material is especially important for the circuit board, which helps determine how effectively the circuit board transfers heat.
Some applications require specific properties in their circuit boards. This is especially true for temperature-sensitive applications, one of which is LED lighting. The LED lighting industry is expanding rapidly in response to increased interest in the more efficient and cost-effective lighting method, but much of the functionality of LED lights depends on the temperature of its system. For many companies, the solution to this problem is in aluminum-based PCBs.
To help you understand why the LED lighting industry uses PCBs, we’ve outlined the nature of PCB base layers, the attractive qualities of aluminum PCBs and why they work well in the LED lighting industry.
Engineers design printed circuit boards to work best within their particular application. The designs can specify the nature of the circuit, the PCB coating material, the size of the PCB and a variety of other qualities. One of the most basic qualities to change, however, is the core of the circuit board.
PCB bases come in a variety of materials, including:
- FR-4: Most common of these materials is FR-4, a base composed of glass and epoxy. While fire-retardant, FR-4 tends to be relatively inefficient at transferring heat.
- Epoxies: Another, albeit less common substrate for PCBs is a material known as an epoxy. While less durable than other options, epoxy-based PCBs are much cheaper to manufacture.
- Metal-core: Metal-core PCBs are very effective for a variety of applications, specifically those involving heat transfers. These bases consist of metal, usually aluminum, laminated with copper. These metals give the circuit board improved electrical insulation and thermal conductivity.
When thermal qualities are not as important, FR-4 or epoxy bases are more common, as these tend to be relatively less expensive. However, when thermal qualities are important for the proper function of the end product, metal-core printed circuit boards are likely the solution.
About Aluminum PCBs
Most common among metal-core printed circuit boards is the aluminum PCB. This type of printed circuit board is built on top of an aluminum alloy base, instead of a fiberglass base. The alloy usually consists of a combination of magnesium, aluminum and silumin, altering the properties of the metal to best suit the needs of the application.
All aluminum PCBs consist of the following layers:
- The Base Layer: The base layer of the PCB is the aluminum alloy sheet upon which the rest of the PCB builds. This alloy is typically designed to provide maximum electrical insulation and thermal conductivity.
- The Thermal Insulation Layer: This layer is extremely important in the design of the PCB. Consisting of a ceramic polymer, this layer protects the PCB from mechanical or thermal damage by offering thermal resistance and viscoelastic properties. This works by absorbing the heat created as the current moves through the circuits and transferring it to the aluminum layer — there it disperses.
- The Circuit Layer: This layer contributes most to the end function of the board, containing the copper foil circuits needed for the PCB to function.
These layers occur in any number of variations, with one or several thermal and circuit layers depending on the particular application. The layers listed also lend a number of different benefits to aluminum PCBs, which can be of use to several key industries.
Aluminum PCB Types
There are numerous ways the layers above can be altered to create new PCB designs. Each of these variations results in slightly different qualities of the PCB, making it more suitable for some industries and applications over others.
Some types of Aluminum PCBs include:
- Flexible Aluminum: This relatively new material uses ceramic fillers and polyimide resin to provide excellent insulation and flexibility, all while retaining the aluminum’s impressive thermal conductivity. These PCBs can be formed to connect directly where they are needed. This eliminates the need for cables, connectors and fixtures, which can add to the end cost of the product. Once they are bent, however, they are meant to stay there — these PCBs are not designed to flex constantly.
- Hybrid Aluminum: Just as it sounds, a non-thermal material fused to an aluminum base metal creates hybrid aluminum. Usually, the material is a circuit board made with conventional FR-4. By fusing these layers together, the circuit board can dissipate heat more effectively, as well as increase rigidity. These hybrids also tend to be less expensive than entirely aluminum products. The downside, however, is the loss of flexibility.
- Multilayer Aluminum: In high performance power-supply applications, multilayer aluminum PCBs are generally the best. These PCBs consist of layers of thermally conductive dielectrics. While this multilayer approach can handle high performance, they tend to be less efficient when it comes to transferring heat However, overall these PCBs tend to be effective for basic heat dissipation in more complex designs.
- Through-Hole Aluminum: For more complex constructions, the aluminum base of a PCB can be pre-drilled and back-filled with dielectric before being laminated with thermal materials. These are highly complex, and tend to be labor-intensive projects meant for particularly complicated or specific projects.
Of these aluminum PCB types, flexible and hybrid varieties tend to see the most use in industries like the LED lighting industry.
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The LED Lighting Industry
Light Emitting Diode, or LED, lighting is an increasingly popular lighting solution, favored for its improved longevity and reduced environmental impact. Some of the benefits of LED lighting over conventional methods include:
- Lower Power Consumption: Quality LED lights can be six to seven times more efficient than traditional incandescent lights. On average, switching your home from incandescent lighting to LED lights can cut your energy use by more than 80 percent
- Longer Lifespan: LED light bulbs can have a life of over 25,000 hours, or three years of 24/7 use! This is 25 times longer than any traditional light bulb. This saves you the time, money and effort involved in purchasing and installing new bulbs!
- More Efficient: Traditional incandescent light bulbs release 90 percent or more of their energy as heat. LED lights cut this by up to twenty percent! This means more of your energy is going into lighting your home, and less into unnecessarily heating it.
- Very Compact: Because of their small size, LED lights feature in applications of various sizes and varieties. This means manufactures can insert LEDs into anything from computers and smartphones to cars and traffic lights.
- Mercury Free: LED lights contain no mercury, unlike more traditional options. As a result, LEDs have a smaller environmental impact than traditional bulbs and can be more easily disposed of, without special disposal procedures.
These benefits are incredible, and have lent to the popularity of LED lighting today. As of 2012, Americans installed over 49 million LEDs, saving $675 million in annual energy costs and significantly cutting carbon emissions. You can find LEDs in automobile lighting, traffic lights, TVs and electronics and a variety of other applications.
However, one of the major problems with LED lighting is its thermal limitations. The temperature at which these LED lights operate influences the color of the lighting, its efficiency and the overall lifespan of the light. This is especially problematic as 70 to 80 percent of the electrical power applied to LED lights is converted into heat, and every 10°C increase in temperature decreases the lifespan of the LED by as much as 50 percent! As brighter, higher density LED arrays hit the market, more efficient thermal management solutions are needed to keep these arrays functioning as long and as strong as possible.
Aluminum PCBs and the LED Lighting Industry
For many companies within the LED industry, aluminum PCBs are the new standard. This is because of the numerous benefits and features aluminum PCBs contain. Some of these benefits include the following:
- Less Expensive: You can find aluminum in mines across the world, making it easy to access and refine, especially compared to other metals. This abundance means aluminum is much less expensive than other rarer metals. As a result, manufacturing with aluminum is also less expensive, especially when it comes to aluminum PCBs.
Aluminum-based circuit boards are also inexpensive when compared to other methods of heat transfer, such as heat sinks. While heat sinks may be slightly more effective at transferring heat than aluminum bases, they are much more expensive to add on to the PCB.
- Environmentally Friendly: Most of us know that aluminum soda cans are recyclable, and aluminum boards are no different. Aluminum PCBs are recyclable and non-toxic, which means disposing of them is relatively easy and environmentally sound.
- Improved Durability: Compared to ceramic and fiberglass, aluminum is much sturdier. This strong, durable material is much more resistant to breakage, and can better handle the stresses of the manufacturing process. This also means that the end PCB is much more resistant to damage from everyday handling, especially in impact-prone environments.
- Lightweight: Despite how durable it is, aluminum is very lightweight. This means a PCB can have improved resilience without additional weight, an important factor in manufacturing. Not only does this result in a lighter end product, but it makes shipping and handling of the circuit boards and end products much cheaper and easier to handle in large quantities.
- Better Heat Transfer: In electronics, consistently high temperatures can cause serious damage, negatively affecting functionality. This makes heat transference one of the most important parts of a finished PCB.
Heat transference is a term referring to how well thermal energy moves from one place to another. How effectively a material does this depends on the materials conduction, convection and radiation. Conduction refers to how easily a material will transfer thermal energy from one area to another, while convection is the transfer of thermal energy from a material to a fluid and radiation refers to the amount of thermal energy a material gives off.
Aluminum has some of the best qualities for heat transfer, because it conducts thermal energy fairly easily, transferring it away from critical parts and minimizing thermal damage to the PCB. Comparatively, fiberglass is much less conductive. This difference results in PCBs that are much more efficient at thermal energy transfer — in fact, aluminum-backed designs can be more efficient than fiberglass-backed designs by up to 10 times!
Because of these qualities, specifically the incredible ability to dissipate heat, aluminum PCBs have become the new PCBs of choice within the LED lighting industry. This growing popularity within the LED industry is due to a few incredible capabilities and improvements upon LED PCB designs made possible with aluminum PCBs. These include:
- Increased LED Density: Each PCB design allows for a greater number of LEDs to mount onto it. Each of these LEDs produces heat, heating up the PCB more quickly. This can be a serious problem for the longevity of the LED lights, because each LED must stay within a strict range of temperatures in order to function properly.
Traditional fiberglass-based designs have a cap on the density of lights per board, purely because the board can get too hot. This is because fiberglass transfers heat relatively slowly, causing the heat to build up. With aluminum boards however, more LEDs can function simultaneously without exceeding the specified temperature tolerance. This is because in an aluminum-core PCB, heat transfers quickly and efficiently, due to the high thermal conductivity of the material.
- Longer Operating Time: As with most electronics, the longer you use them, the hotter they get. This can negatively impact the functionality of the system and alter its operation, especially in more complex systems. In the case of LEDs, the quality and color of the lights change depending on how hot they get, and operating at a hotter temperature reduces the overall lifespan of the LED.
With aluminum LED PCBs, the improved heat transferring qualities of the material results in the LEDs operating at a lower temperature for a longer amount of time. This means aluminum PCB LEDs can operate for much longer before they finally fail.
The Applications of Aluminum LED PCBs
The above benefits make LEDs with aluminum-based printed circuit boards very desirable for a number of applications and industries. Some of the more prominent applications of Aluminum PCB LEDs include:
- Telecommunications: Telecommunications equipment often uses LED indicators and displays, and because of the surrounding machinery, the improved heat transfer ability of aluminum-based LED PCBs is extremely useful in this application. Improved durability and decreased weight also make these aluminum PCB LEDs quite desirable within telecommunications applications. Not only that, but aluminum PCBs are commonly used in other components of telecommunications equipment as well, including filtering appliances and high-frequency amplifiers.
- Automotive: You can also find aluminum PCB LEDs in cars on indicators, in headlights and brake lights, and other applications. The durability, longevity and relatively low price makes these aluminum PCBs ideal within the automotive industry. Their applications don’t end at LEDs either – aluminum PCBs are commonly used within electronic regulators and power controllers.
- Computer: LED displays and indicators are becoming increasingly common within computer applications, and the heat sensitivity of computer machinery makes aluminum PCB LEDs the ideal solution. In addition to LED applications, computer parts like power devices, floppy drives and CPU boards are commonly use aluminum PCBs because of their ability to handle and transfer heat.
- Medical: Lighting tools used in surgeries and medical examinations commonly use high-powered LED lights, and these LED lights often use aluminum PCBs. This is primarily due to the durability and heat transfer capabilities of aluminum PCB LEDs — this ensures medical equipment is functioning properly regardless of the number of patients cycling through a medical office. In addition to lighting tools, medical scanning technology often uses aluminum PCBs as well.