Guide of LED PCB Assembly

We can say that LED PCB assembly has changed the world of lighting. LED lighting provides numerous significant advantages over other lighting system. LED lighting has grown increasingly widespread in our daily lives in recent years. As the demand for LED lighting increases dramatically, LED circuit board assembly technology needs to be updated faster and faster. In this article, we will introduce the general knowledge about LED PCB assembly, so that you can have a better understanding of our LED PCB assembly service.

What is an LED PCB?

Before you know what an LED PCB is, you may need to know what an LED refers to. LED, short for lighting-emitting diode, is a semiconductor diode. A chip contained in the lighting emitting diode will generate light when the LED is soldered to a Printed Circuit Board (PCB) and electrically connected.

And so what is an LED PCB? Actually, an LED PCB is a kind of printed circuit board with a number of electrical components soldered to it. It can be used to produce a wide variety of specific LED lighting fixtures. We often use aluminum as the substrate material for LED PCBs due to its good thermal conductivity. A completed circuit is formed when we first print the circuit on the aluminum plate and then solder the LED components onto the circuit board. When electrically connected, the chip, bonded by a heat sink and a ceramic base will generate light. With different types of chips or switches, you can completely control these light emitting diodes.

What is LED PCB Assembly?

PCB Assembly is known as the process in which all the electrical components are installed on a PCB. And LED PCB Assembly is referred to as the assembly used for the LED lighting. Several LEDs and some other components are required in the LED PCB Assembly. The multiple layers of LED PCBs can stick together using a special glue. Between these layers, there are various insulators, preventing the LEDs from overheating and even melting.

To dissipate heat more quickly, LED PCB Assembly is commonly composed of aluminum to resist heat. It’s strong and long-lasting. It can endure a great deal of abuse and function properly for a long period. MOKOLIGHT can make various shapes of assemblies according to the user’s requirements. Among them, LED PCB strips, circular and rectangular boards are all common.

Why We Should Choose LED PCB Assemblies?

LED PCBs are becoming increasingly popular in many applications as electronic products become smaller and smaller. There are numerous benefits of LED PCB assemblies as follows:

Low Heat Emission

This is one of the most important reasons why we use LED PCBs. Because of the intrinsic property of electricity, traditional circuits always have trouble in heat dissipation. LED PCBs, however, provide a relatively good solution to this problem. Although it still generates heat, it is negligible compared to other forms of lighting. The entire circuit can operate at a lower temperature by using radiators, and even minimal heat can be eliminated.

Compact and Lightweight

Compared to other types of lights, LEDs are much smaller and take up very little space. Sometimes, regular light bulbs cannot be placed in a small space, whereas LEDs can easily do this. Due to their tiny size, LEDs can be easily installed on complex PCBAs. In addition, LED PCB assemblies are small and lightweight, allowing for greater design flexibility. By using multiple LEDs, we can achieve any kind of design according to different requirements.


LED lights last nearly twenty-five times longer in comparison to incandescent and fluorescent lights. Another important reason is the construction. Early conventional circuits were prone to snap or wear. With LED PCBs, however, you don’t have to worry about this because the circuits are printed on the board, not connected by wires. And LEDs are made up of many solid components, making the technology more durable.

As a result, a variety of advantages are available. This means a great deal of maintenance costs can be saved since LEDs do not require frequent replacement. In addition, the LED PCB assembly can effectively dissipate heat, also increasing its reliability.

More Efficient

LEDs are more efficient than other lighting technologies because they generate very little heat. The majority of the energy is converted to light, and only a small amount is wasted as heat. LEDs not only use less energy, but also provide the same level of light for you. In a word, if you adopt LED technology, you will save your energy bills a lot.

The low power consumption is another significant advantage of LED PCBs. In general, using LEDs requires much less power than other lighting technologies. According to the U.S. Department of Energy, LEDs consume about 75% less energy than incandescent bulbs. By 2027, 348 terawatt-hours of electricity, or about $30 billion in electricity costs, will be saved due to the widespread use of LEDs.

Available in a Variety of Colors and Designs

Another major reason for the popularity of LED PCBs is that you can easily tune the color by integrating LED components of different colors into the same PCB. As the market demand for LED PCBs becomes more and more diversified, it is inevitable that widespread customization is required to suit this purpose. With various colors and designs, the technology can be used for a wide range of purposes.

Prevent the Circuits from Dust and Moisture

LED PCBs are far more resistant and durable than traditional circuits and lighting sources. This makes them an excellent choice for general-purpose and heavy-duty applications, especially for outdoor applications requiring frequent exposure to dust and moisture. The resistance of components will be greatly improved through the design of sealing systems and safety features.

Not affected by the external environment

LED PCBs can work well in almost any environment, regardless of hot or cold. They can be used for a wide range of applications, even at extreme ambient temperatures.

Industry Applications of LED PCB Assemblies

LED PCBs can be incorporated into numerous industries and applications because of their distinct qualities and characteristics. So let’s look at some popular use cases in this chapter.


Because of their durability, long life and heat dissipation capability, LED indicators and displays are often used in the telecommunications industry. Most LED PCB assemblies are mounted with aluminum, which can effectively transfer and dissipate heat. Therefore, with the help of LED circuit boards, the equipment will not malfunction intermediately because of overheating and can stand the test of time.

Automotive Industry

More and more automobile manufacturers are manufacturing indicators, brake lights and headlights with aluminum LED PCBs due to their durability and competitive pricing. This may be a last resort to improve the quality and effectiveness of their automobile parts.

Medical Industry

LED PCBs are widely used in medical equipment in hospitals because they typically provide more light than traditional circuit boards. High-powered LED lights are often used as lighting tools for medical examinations and surgeries. And aluminum PCBs are commonly used in these fixtures to effectively dissipate heat and ensure the proper functioning of medical equipment.

Computer Manufacturing Industry

In computer applications, using LED displays and indicators is more and more common. Recently, many computer companies have become interested in LED PCB Assembly. Computer parts such as power units and CPU boards are sensitive to heat. Aluminum PCB LEDs are a suitable solution due to their ability to transfer and dissipate heat.

Additional Application Cases

The applications of LED PCBs go far beyond what we’ve mentioned above. And you may be interested in other applications of it. Other examples include:

Street and tunnel lighting

Flashlights, lanterns, work lamps and solar lighting

  • Signal lighting
  • Military lighting
  • Aviation lighting
  • Marine lighting
  • Factory lighting

LED PCB Assembly Technology

In general, there are three ways of LED PCB Assembly. But in practice, we often use two main methods to mount electronic components to printed circuit boards. They are as follows:

Through-Hole Assembly

Dated back in the 1940s, through-hole PCB assembly technology was widely used in electronic manufacturing. The process of through-hole assembly involves drilling holes in the PCBs, threading leads through the holes, and then using solder to hold the pieces in place. To ensure accuracy and effectiveness, the process also includes numerous inspections.

Now, with the development of technology, through-hole assembly technology isn’t outdated. Instead, some device manufacturers still prefer it because it has some benefits that other technologies cannot compare with, such as:

This technique makes it easier to prototype because its components can be easily interchanged;
This method provides a stronger weld and is able to withstand harsh environmental conditions, resulting in higher durability.

Surface-Mount Assembly

Surface mount technology, originated in the 1960s, is the current mainstream technology in the electronics assembly industry. In the 1980s, it gradually replaced the through-hole assembly technology. Most manufacturing companies use this technique because it has the following advantages:

  • Small-size devices can be assembled through this technology;
  • Make automated assembly possible;
  • Both sides of the board are used;
  • Cost-effective and has good thermal property;
  • Faster assembly than through-hole assembly technology.

Process of LED PCB Assembly

LED PCB assembly process is similar to other PCB assembly methods, including a series of steps as follows:

Designing the PCB

The design is always the first step in the manufacture of any PCB. The designer creates a PCB blueprint, and the circuit board should be designed according to the requirements of the PCB layout. There are some common PCB design programs, such as Extended Gerber, Altium Designer, CAD and Pads. Upon receiving the PCB design, the PCB fabricator will conduct a Design for Manufacture (DFM) check to ensure that the PCB design fulfills the required tolerances for manufacture.

Printing the PCB Design

After all checks are completed, PCB printing can begin. We often use a plotter printer to print PCB plans and make photo films of the PCB. After the films are printed, holes are punched through them, called registration holes, which are used to align the films.

Printing the Copper for the Interior Layers

At this point, you’re actually starting to make PCBs. The copper path was drawn while the films were being made, and then the graphics on the film should be printed on the copper foil. At this stage, the cleanliness of the PCB structure is particularly important. Remember not to have any dust particles deposited on the laminate. Otherwise, it may cause short circuits or circuits remaining open.

Etch the Inner Layers to Remove Copper

Next, we need to remove the extra copper from the inner layers of the printed circuit board. All unprotected copper can be removed during the chemical etching process, leaving a necessary amount of copper on the board. The copper removal time and the amount of copper etching solvent used will vary for different types of PCB boards.

Layer Alignment and Optical Inspection

It is time for layer alignment and optical inspection after cleaning each layer of PCB. We need to align the outer and inner layers through the holes from earlier. To align and punch the holes accurately, the layers are put in a machine called an optical punch.

Layering and Gluing

At this stage, individual PCB layers are placed together, waiting for lamination. The two steps-the lay-up step and the laminating step are included in the PCB lamination process. After the PCB layers are pressed together, we need to unpack them. The actual PCB will be pulled out by the technician after removing the top press plate and pins from earlier.


First, we can use an X-ray machine to drill the registration holes. In this way, the PCB stack can be fixed before more specific holes are drilled. When the drilling is complete, additional copper lines left at the edges will be filed off.

PCB Plating

After drilling, the panel is ready for plating. All the layers of the PCB are fused together through the plating process. The PCB is then soaked in some chemicals, adding a micron-thick layer of copper to the panel.

Outer Layer Imaging

Similar to the previous step, we also need to apply a layer of photoresist to the outer layers and image it. The outer layers are coated with tin to protect the copper.

Outer Layer Etching

This stage requires the removal of any unwanted copper using the same copper solvent as before. The areas that need to be removed for the outer layer etching is the opposite of that for the inner layer etching.

Outer Layer AOI

Like the inner layer, an automatic optical inspection (AOI) for the outer layer is also required. This allows you to check whether the PCB is functioning properly, avoiding electrical connection errors.

Apply Solder Mask

Before applying the solder mask, we must thoroughly clean the panel. The UV light shines on the circuit board, and some of the solder resistance is removed according to the indications. To cure the solder resist, the circuit board is then placed into an oven.


In the silkscreen process, some vital information needs to be printed on the surface of the circuit board with an inkjet printer. They then go through the final testing and inspection phases.

Electrical Testing

To ensure the functionality of the PCB, different areas of the PCB are subjected to a series of electrical tests, including circuit continuity and isolation tests.

Analysis and Scoring

At analysis stage, the shape and dimension of each circuit board separated from the construction board need to be identified. The data is usually retained in the Gerber files. After the boards are scored, they can cleanly separate from the construction board to proceed to the next step.

Final Test

LED PCB assembly needs to go through a final test before packaging and shipping. The inspection involves the following aspects:
The size of the boards must conform to the design specifications;
The hole sizes of all layers should be the same;
No dust remains on the board;
No burrs or sharp edges on the finished boards;
Boards that fail electrical tests must be repaired and retested.

Packaging and Shipment

This is the final stage of PCB manufacturing. First, the areas around the printed circuit boards should be sealed to prevent dust from entering. Then place the sealed boards in a container to avoid damage during shipment.

Challenges and Solutions Encountered in LED PCB Assembly

Heat Management in LED PCB Assembly

One of the main factors to consider when assembling LED PCBs is thermal management. When multiple high-intensity LEDs are densely packed on a single board, they generate high levels of heat in a short period of time. Some efficient methods of heat dissipation are required in order to enhance the durability of the circuits. The problem can be first solved through smart design and precision prototyping. In addition, you can use heat sinks or metal-core PCBs to improve heat dissipation.

Solder LED Components in LED PCB Assembly

Soldering the components is one thing to take due care of when performing PCB assembly. The LED components must be soldered to the correct base for LED lamps to work efficiently. A ceramic plate base is generally used to minimize heat.

When assembling LED PCBs, you need to pay attention to the following points:
Solder bridges: A short circuit might occur if you make an unintentional connection while soldering;
Component warping can also lead to soldering;
In order to create a good joint, the solder head should be kept clean and tidy;
To quickly assemble a PCB, solder the smaller components first and then the larger parts.


LED PCB designs are increasingly complex, so you may need a company with expertise and high-end equipment to assemble them. MOKOLIGHT has many years of LED PCB assembly experience and is ISO9001-certified and FDA-registered. We can provide you with LED lights for a wide range of uses from consumer, LED bulbs to precision medical, MOKOLIGHT is the perfect place to meet your LED PCB assembly requirements. We offer quick response service and excellent after-sales service to help you make better use of this technology. Please contact us immediately for quote information on LED PCB assembly.

Adelyn Ward

Master of Science; professional electronic engineer with over 7 years of experience in electronic design and engineering projects; proven expertise of LED manufacturing processes, capable of communicating intricate ideas to a broad range of audiences. Reach Me Now>>

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