PCBs for the LED Industry
Printed circuit boards, or PCBs, are everywhere in our technology-based society. Everything from computers to medical equipment to cars contains PCBs in one form or another. However, PCBs are not all the same— each product is custom with different designs or materials and specifications to suit a unique purpose. For circuit boards in the LED industry, the base material is especially important, 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 aluminum-based PCBs.
To help you understand why the LED lighting industry uses PCBs, we’ve outlined the nature of base layers, the benefits of aluminum circuit boards and why they work well in the LED lighting industry.
What Is an LED PCB?
LED stands for light-emitting diode. An LED printed circuit board is used to mount the diode(s) and power the LED for the application.
Generally, LED devices use a surface-mounted design (SMD) that includes a single LED component. To generate more light, an LED circuit board connects multiple lights.
Because these lights and their operation generate a large amount of heat, they need to have a way to remove this heat, such as a heat sink or structural material that draws away heat. Hence, the LED PCB material may be aluminum, which excels at transferring heat away from the board.
Due to the many advantages of LED lighting and its multiple applications in modern life, LED PCB manufacturing and products have increased to meet the rising demand.
The Benefits of LED Lighting
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%.
- Longer life span: 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% or more of their energy as heat. LED lights cut this by up to 20%! 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 manufacturers 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.
The Challenges of LED Lighting
LED lighting has several challenges that proper design must overcome. These challenges include:
- Temperature: First, the temperature of the light’s operation contributes to other problems. Up to 20% of the electricity that the LED receives turns into heat. This extra heat impacts the life span and the color of the light.
- Color of the lighting: The LED light’s color relates to the operating temperature. For maintaining a specific color, the temperature also requires careful control. Again, thermal limitations present a major challenge in the design and use of LED lights.
- Life span of the light: High temperatures can severely shorten the life span of the LED. When the temperature of LEDs increases, the life span drops. Therefore, controlling temperatures for brighter, more intense LED arrays will become even more critical in the future to ensure the longevity of the lights.
Factors to Consider When Designing an LED PCB Board
When designing an LED printed circuit board, you must think about the materials used, how to manage heat, trace routing and the finish. With an appropriate design, a PCB manufacturer can create a board that will work as it should for operating the LED.
Materials used for the printed circuit board should work together to remove and dissipate extra heat, insulate conductors, and allow electrical connections between LED components.
The base layer for many LED circuit boards uses aluminum. Over the aluminum base is the dielectric layer, topped by the copper circuit layer and the solder mask. This type of structure also goes by the term insulated metal substrate (IMS). The aluminum base works well to release extra heat and assist in thermal management.
Thermal management is one of the most crucial aspects of LED design. Poorly regulated temperatures can shorten the life of the device and affect the color purity of the light. Therefore, designs of LED circuit boards typically include aluminum cores and heat sinks to get as much heat away from the components as possible. The component arrangement and LED placement also impact the distribution and removal of heat to the air and should be part of the design considerations.
Proper trace routing design prevents open and short circuits, crosstalk between circuits and manufacturing problems. Trace routing ensures that all network connections are properly attached without interference from other network connections.
Using the proper width of the traces prevents overheating. Space for traces and mounting hole considerations in the design also ensure that problems will not happen during manufacturing.
The board’s finish protects the circuit layer and ensures that assembly has a site for soldering components onto. There are several types of printed circuit board finishes available, each with its own advantages and disadvantages. Finding the right finish may involve discussing the expectations of the board and the budget for the project.
LED printed circuit board cores typically include either standard epoxy glass or metal cores. Heat transfer, as always, is crucial to maintaining the life of LED circuit boards. However, epoxy glass cores can be more cost-effective.
The most common metal core used for LED printed circuit boards is aluminum. This metal quickly transfers heat away from the board to the outside. In doing so, it augments the function of the board’s heat sink in preventing excessive heat from damaging the components of the circuit board.
These types of PCBs require surface mounted components because mounting anything through the board could lead to short circuits if the solder contacts the metal interior of the circuit board. However, since LED components are surface mounted, metal cores suffice for their use.
Standard Glass Epoxy
One of the biggest differences between metal and glass cores is their method of heat transfer. For instance, metal cores do not use metal vias to conduct heat. Instead, the aluminum does the work. For standard glass epoxy, metal vias carry heat away, though not as efficiently as metal core PCBs. Unless cost-effectiveness is the most important component of designing an LED PCB, metal cores will perform better than standard glass epoxy cores.
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:
- Base layer: The base layer of the PCB is the aluminum alloy sheet. This alloy is typically designed to provide maximum electrical insulation and thermal conductivity.
- Thermal insulation layer: This layer is extremely important in the design of the PCB. Consisting of a ceramic polymer, this layer protects the circuit board 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.
- 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 Printed Circuit Board 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 printed circuit boards 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 epoxy resin. 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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Aluminum’s performance for use as a printed circuit board core has made it a standard of the LED lighting industry. Its inherent advantages make it a consistently acceptable option for the core of LED printed circuit boards.
Benefits of Aluminum PCBs for LEDs
Aluminum PCBs provide several advantages for their use with LEDs:
- Better value: Aluminum saves on production costs in two ways. Compared to other metals, aluminum is more cost-efficient. By choosing circuit boards that use this metal as its core, the design can avoid adding less cost-efficient heat sinks for thermal regulation.
- Recyclable: Aluminum is readily recyclable and non-toxic.
- Durable: Aluminum is stronger and lasts longer than glass, fiberglass or ceramic printed circuit boards, especially against impact and heat damage.
- Lightweight: Circuit boards made from aluminum don’t have extra weight from the core that they would from other materials. Shipping and handling become more cost-effective due to the lower weight of the aluminum core.
- Improved heat transfer: Aluminum PCB cores transfer heat better than standard cores or other materials, preventing heat damage to the LED components.
Aluminum LED PCB Design Advancements
Advancements in LED PCB design with aluminum cores have allowed for several new and improved capabilities. Aluminum transfers more heat from the printed circuit board and LEDs. Fiberglass PCBs have a limit on the density of LED lights they can accommodate due to heat build-up. Aluminum cores offer greater temperature control compared to standard cores or fiberglass bases.
Benefits of Design Advancements
The ability of aluminum to improve temperature control allows for the following benefits:
- Higher LED density: More lights mean higher operating temperatures that require better thermal regulation from aluminum cores.
- Longer operating time: Aluminum printed circuit board designs better remove excessive heat produced from long operating times.
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. Additionally, 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 in other applications. The durability, longevity and relatively low price make 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 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.
Our LED PCB Board Capabilities
When it comes to finding LED printed circuit board solutions, you need to understand the factors that influence the success of the circuit board operation. These factors will go into the design of the circuit board. Therefore, you need to know how the supplier’s capabilities can help to prevent the most common LED circuit board issues. At Millennium Circuits Limited (MCL), we can:
Thermal issues such as LED components that create excessive heat can lead to the failure of the circuit board. Therefore, you must have a solution that ensures proper design for function. Heat sinks and aluminum bases are among the LED PCB components that can remove excess heat and allow for the board to operate as intended.
Certify the LED PCB Manufacturing Process for RoHS Compliance
Many sectors require circuit boards to be Restriction of Hazardous Substances (RoHS) compliant. This regulation restricts the use of materials that include:
- Polybrominated diphenyl ether
- Polybrominated biphenyls
- Hexavalent chromium
At MCL, we ensure RoHS compliance with the circuit boards we provide for our customers.
Design PCBs for LED Components
When designing an LED circuit board, the same standards for other PCBs don’t necessarily apply. LED components have special requirements, such as extra means of dissipating heat. Therefore, you must ensure the design of the PCB will work for your LED application. For instance, have enough space between copper and other metals on the printed circuit board to prevent contact between the two. Space should be between pads, between pads and traces and between traces on the circuit board. If you have issues with the PCB design that may negatively affect manufacturing, we can alert you of the problem before production begins on your LED circuit boards.
Reduce Damage From Over Stress During Use
Consider the potential maximum electrical specifications and PCB use when designing the LED printed circuit board. Do not allow the LED requirements to reach or exceed their maximum values for surge current, reverse voltage, voltage, forward current and allowable temperature. Check your design against the operating parameters of the components.
Minimize Performance Drop Off Due to Manufacturing Defects
Some manufacturing defects can cause problems with performance. Examples of issues created during manufacturing may include:
- Short or open circuits
- Shifting components during assembly
- Performance degradation
At MCL, we use our design rule check (DRC) to ensure the manufacturability of the circuit board. If a problem with the design exists, we connect with the customer to correct it prior to production.
Choose Millennium Circuits Limited as Your Provider of PCB Technology
At MCL, our services help our customers acquire the PCB solutions they need, including for the LED uses. With our knowledge of circuit boards and LED technology, we can get the right circuit board solutions into our customers’ hands. Contact us for a free quote or questions about our capabilities.