8 Ways to Overcome LED PCB Defects
●Circuit Scratch：Reduced wire spacing
●Pad Outline:the trick is to insist on program control.
●Degrading Functions:Solder mask oil removed or concerned components demolition.
●Solder Mask Oil Peeling：Secondary exposure
●Solder Mask Oil Color Inconformity:Choose Rigorous manufacturing technologies and years’ fabrication experience’supplier.
●Bad Board corner:Add base plate for protection as a protection measure.
●Warpage:Reducing warpage to a level not sufficient to concentrate on achieving a flatness of 0.5%
●Bad board Outline: To have a suitable process assistance margins.
LED PCB Component assembly Technology
There are three methods of placing/ mounting components on LED PCB. They are the Through-hole mounting , the surface mount , and chip-on-board (COB).
●Through-hole mounting:Two types of components are used in the through-hole mounting technique. They are radial (placing the leads on both sides) and axial (placing the leads on one side).
●The surface mount:Also named Flat installation technology ,The components used have a assemble called SMD under or around the leads.
●Chip-on-board (COB): Soldered small, leadless components or components with very short leads to the printed circuit board.
Design techs in LED PCB Assembly
●Pitch: The pitch range in harmony with current SMT is from 0.45mm to 1.6mm while LED pitch is from 1.0mm to 4.0mm. The figure 1 indicates comparison between SMT pitch and LED pitch.
●LED Installing Holes:LED installing holes are non-penetrating holes with advised diameters tolerance at ±0.05mm depth (H) should be ≤the value of board thickness (T) minus 0.5mm. Depth tolerance should ＞ ±0.2mm while the conventional drilling angle (θ) is 130°.
●Laser Drilling Blind Vias:These techniques are suggested to be designed as stagger vias when stack boards ＞ 2 layers. because it reduce the procedure complexity and manufacturing cost.
Your Premier LED PCB Manufacturer
Today, LED lightings are around us everywhere in our daily life, more and more lightings are replaced by LED( light emitting diode) solutions, since LED lighting has lower power consumption, longer lifespan and more energy efficiency compare to the traditional lighting bulbs. In PCB industry, when we say LED PCB( LED pcb board, LED circuit board, LED pcb board, LED printed circuit board ) it refers to the PCBs( printed circuit boards) that used for LED lighting applications.
LED PCB: LED Ceiling Light
Venture has been participated inall kinds of LED lighting projects,by supplying LED PCB( LED circuit board ) with using CEM3, FR4 , aluminum and copper alloy as the LED PCB base material.
There is no doubt that, compare to CEM 3 and FR 4 material, aluminum and copper alloy have better performance on heat transfer, however, since copper alloy price is much higher than aluminum, so we can say, in LED lighting industry, aluminum is absolutelythe most economic option considering thermal conductivity, rigidness, and cost.
|Layers||1 – 6||1 – 6|
|Max Board Size||24” x 40”||609.6 x 1016mm|
|Min Board Thickness – 1-2 (layers)||16mil||0.4mm|
|Min Board Thickness – 4 (layers)||20mil||0.5mm|
|Min Board Thickness – 6 (layers)||24mil||0.6mm|
|Board Thickness Range||16 – 157mil||0.4 – 4mm|
|Max Copper Thickness||5oz||175um|
|Min Trace Width / Space||4mil / 4mil||0.1 / 0.1mm|
|Min Hole Size||20mil||0.5mm|
|PTH Diameter Tolerance||±2mil||±0.05mm|
|NPTH Diameter Tolerance||±1mil||±0.025mm|
|Hole Position Deviation||±4mil||±0.1mm|
|Thermal Shock||5 x 10Sec @288||5 x 10Sec @288|
|Warp & Twist||<= 0.75%||<= 0.75%|
Venture can produce LED PCB prototype base on our stock material so you don’t have to wait long lead time on materials. We have a full range of top level LED PCB raw materials( LED pcb board material) in stock to meet your high-end LED PCB application, such as Totking, Bergquist, Laird, Kinwong, Doosan, ITEQ, Shengyi, Polytronics, Iteq, Arlon, Ventec, we can also suggest local popular aluminum raw material manufacturer that fit your projects, and most important-reduce your cost . Pls check below our LED PCB raw materials list, for more details pls feel free to contact our sales.
Aluminum Material Type
|105||T-Lam 6061+ 1KA10||Laird|
|Aluminium||140||T-Lam 5052 + 1KA04|
|Aluminium||105||T-Lam – Alco 6061+1KA04|
|105||TLam SS 1KA06||Laird|
Through our 2 hours rapid response services from our 24/7 sales and tech support team, and excellent after-sales service, we will be your best LED (bulb)PCB(circuit board)manufacturers in China. At Venture we can answer any LED PCB questions that you may have, pls feel free to contact us anytime.
Your Leading LED PCB Supplier in China
Venture is trusted by thousands of electronic engineers on their LED lighting projects, from consumer led bulb PCB design to precisely medical LED light PCB design, from commercial flood LED PCB to industrial high power LED PCB, from automotive LED PCB to military LED PCB, we can help you from the beginning of design stage;Venture is the perfect place for your LED PCB requirement, below are the LED PCB applications we have been participated in:
- Commercial Lighting
- Pendant Lights
- Down lights
- Display Lights
- Desk Lights
- Wall Lights
- Ground Lights
- Cabinet Lights
- Spot Lamps
- Medical Lights
- Street Lights
- Vehicle/automobile Lights
Venture has 10 years experiences with LED PCB projectsby providing aluminum, copper base PCBs that are with leading LED PCB manufacturing process.
LED PCB: The Ultimate Guide
Are you looking for a suitable LED PCB for your lighting systems?
Or do you want to save cost on your next modern LED lighting systems project?
If yes, then you should read this guide.
It covers everything you need to know about LED PCB, from a basic definition, advantages, features, manufacturing process, choosing material, assembly process, and many more.
Keep reading to learn more…
Chapter 1: What is LED PCB?
LED is an initial for light emitting diodes which emits light rays when an electric current passes through.
LED usually has negative (cathode) and positive (anode) and will produce light in the visible region.
The LEDs stick to the PCBs by the process of soldering and have electrical connections for illumination.
In the recent past, there has been a great evolution in the field of printed circuit boards thus simplifying various systems.
The innovations have spread through to the field of lighting where we have printed circuit boards responsible for LED lighting.
The light emitting diode connects to the main circuit board and includes a chip which produces light in an electric circuit.
LED on a PCB
The light emitting diode PCB chip is in connection to the board using a ceramic base and a thermal heat sink.
It emits a lot of heat when it is in use and manufacturers use other means of reducing the heat.
Metalcore PCBs are often the best option for the LED PCB lighting systems as it dissipates heat faster.
The main material or metal in the metal core printed circuit board for light emitting diodes is usually aluminum.
The aluminum LED PCB, has a thin layer of thermally conductive dielectric material to assist in heat dissipation.
The material works better, more efficiently and faster in comparison to the traditional rigid printed circuit boards.
You can use the LEDs in making different patterns and signals in applications such as advertisement boards.
The technology is also involving every day and you can use it in a task and environmental lighting too.
You can easily find it in a number of varieties such as ultraviolet light, visible light, and infrared light.
Chapter 2: Advantages and Disadvantages of LED PCB
Whenever you are using the LED PCB, you will enjoy certain benefits and it might also fail on other occasions.
Some of the advantages of using the LED printed circuit board includes:
- The Light emitting diodes are common due to their high intensity and high-quality purposes. Many manufacturers in the modern world prefer using the LED PCBs as they assure their customers of quality performance.
- It has a flexible design capability enabling customers to have custom designs for their appliances. You will also find different designs of the LED printed circuit boards in the market that you can choose from.
- The Led printed circuit boards are cost effective thus will save you a lot of money.
- It is also very easy to use and you don’t have to go through training before using the appliance.
- It is energy efficient and you will save a lot of energy whenever you are using any of the appliances.
- The LED printed circuit boards to have very low electrical noises even though it produces bright and effective light.
- The diagnosis and repair of the LED printed circuit boards is simple. You can easily do it without contacting a technician for help. It is also replaceable in case you have serious damages to the device.
- Manufacturers can make it in different compact sizes which would not be possible without the PCBs. It is a convenient platform for arranging the electrical components in an efficient and compact manner. This allows for the development of different LED circuits of various sizes.
- The LED PCB components are immune to movements as they stick to the board through solders. It allows manufacturers to use it in moving appliances such as the headlights of a vehicle. You will not worry about the displacement of components and electrical short circuits as the vehicle moves.
- It also has heat sinks and metal cores such as aluminum that will assist in the dissipation of heat.
- It is also very compact and manufacturers can place it easily into different components such as cars among others.
- It is free of mercury unlike the other traditional options of lighting and is environmentally friendly.
Apart from the advantages, light emitting diodes printed circuit boards also has some demerits which include:
- Even though there has been an improvement in the performance, single devices are unable of producing enough output. The output from single devices is still inefficient to a point where you can’t use it for mainstream lighting applications. It will, therefore, consume a lot of physical space to make an efficient LED PCB.
- Grouping of LEDs into different arrays also present challenges of optical, illumination and manufacturing viewpoints.
- Optimizing the quality of the light from an LED PCB is very difficult as it is expensive and time-consuming.
- The LED arrays will age at different rates as some may have longer lives in comparison to others. It can result in the junking of the unit by the consumer.
- The assembly of different LED PCBs is also labor intensive and difficult and sometimes increases the cost.
- The LED application also produce a lot of heat prompting the use of metal core printed circuit boards. The metal core printed circuit boards are relatively expensive in comparison to the normal PCBs.
Square LED PCB
Chapter 3: Main LED PCB Applications
LED PCBs are available in different applications due to energy efficiency, design flexibility, and low cost.
The LED printed circuit board plays a very important role in prolonging life and saving energy in such applications.
There are certain types of LED PCBs that reflects LED light and supports the maximum intensity of light.
The main applications of the LED printed circuit boards to include:
Automotive LED PCB
You are most likely to find this type of LED PCB in the power regulators, automotive industry and electronic regulators.
The PCB for the automotive industry should have long life service, high durability, at a very competitive rate. The LED printed circuit board is best fit for automotive as it can perform well in the rigors world of automotive.
Audi with LED Lights
The LED printed circuit board is in the display, engine circuits, and other electronic equipment such as the stereo system.
In many cases, the metal core LED printed circuit boards to perform better in the high-temperature application such as the headlights.
The main applications of the LED PCB in the automotive industry include:
- Power relays
- ECU/ECL control modules
- Digital displays
- Transmission sensors
- Interior and exterior LED lighting systems
Telecom LED PCB
The LED PCB that you will use in the telecom industry usually has low weight, highly durable and resistant to noise.
The LED printed circuit boards are available for filter circuits and other equipment of high frequency.
Telecommunication equipment use LED displays and indicators and in the process produces a lot of heat.
Simple telecommunication system – Photo courtesy: Optical Society of America
To address the heat problem, aluminum LED PCB is more applicable and extremely useful in this industry.
The aluminum LED PCB is also desirable due to its low weight and durability making the devices lighter and long-lasting.
Medical LED PCB
Look at various medical equipment such as scanners and you will find the LED printed circuit board.
Medical equipment needs to be efficient and highly durable and the LED PCBs provide the best results.
The LED printed circuit boards are available in equipment that you will use for diagnosis, treatment, and research.
In various operating rooms, most of the lighting systems have the light emitting diode printed circuit boards.
The intensity of illumination from these appliances makes them the best choice for such operations.
It is also the main component in the lighting devices you will find in different rooms of the hospital.
Computer LED PCB
The computers usually emit a lot of heat during its operations and require a good PCB to eliminate the heat.
The best heat-sensitive circuit boards for the computers are the light emitting diode printed circuit boards.
You will find the LED PCBs in scanners, smartphones, tablets, desktops and laptops for display functions.
Computer motherboard LED
Parts of the computer such as the floppy drives, power devices, and CPU boards will use the aluminum LED PCB.
Other examples of applications where you can find the LED PCB include airport runway landing lights and street lights.
It is also available in the applications for the lighting equipment in the military field, and highway tunnel lighting.
Solar/Photovoltaic lighting, lanterns and flashlights, signal and traffic lighting also have the LED printed circuit boards.
Apart from these applications, you can also find the LED PCB in the field of agriculture and crop science.
Agricultural researchers use the LED PCBs to assist in lighting for high growth of the plants.
The light intensity from the devices is suitable enough for the growth of the plants.
Chapter 4: Key Components of LED PCB
The success of the LED printed circuit board will depend on various components of the LED PCB.
Circular LED PCB
These are the key factors that work in conjunction with one another to complete a process. These components perform or modifies and manage the voltage and current that will flow through them.
Most of the components are standardized off the shelf that you can easily identify and purchase.
Other components are usually more proprietary to the project and you cannot find them easily.
A typical LED basically has a chip which is a semiconductor that will produce light in an electrical circuit.
The design will specify the circuit nature, the coating material of the PCB, size and other important factors.
LED on PCB – Source: MY LIGHTING GUIDE
Apart from the chip, there are various components of the LED printed circuit board such as:
Note that not all the LED PCBs are the same as they may vary according to the type of application and base material.
The base material is the most significant part of the LED PCB as it will determine the efficacy of the board.
The efficacy of the board is seen in the mode and speed by which it will transfer heat from the device.
There are certain applications that require specific components to be available on the light emitting diode printed circuit board.
This fact is true in the applications that are very sensitive to high temperature such as the LED lights.
Engineers will, therefore, design different types of PCB cores using different materials depending on the application.
PCB Base Material
Among the best and most important qualities of the PCB, you need to look at is the PCB core. The base of the LED printed circuit board is available in a variety of materials such as:
FR-4 Material for PCB
FR-4 is the most common base material that you can find in the LED PCB composing of epoxy and glass.
It is fire retardant but it is not the best material that you can choose for dissipation of heat.
There are different designations of the FR4 which include FR4 standard, FR4 non-halogen, FR4 mid-Tg, and FR4 high Tg.
Apart from that, there is also the FR4 printed circuit board with the thermal via array.
It is a type of FR4 with thin double sides and plated through holes or thermal via holes.
The thermal vias will ensure that there is a thermal path to improve the conduction of heat through the thermal substrate.
Epoxies Material for PCB
Epoxies are other albeit and not so common substrates for the light emitting diode printed circuit boards.
They are less durable in comparison to other substrates but they are cheaper to manufacture.
It is, however, a very bad conductor of heat and not a good option for the dissipation of heat.
Metal Core for LED PCB
Metal-cores are the most effective materials for the light emitting diodes especially the one that produces excess heat.
They are very good conductors of heat and can assist in the dissipation of heat from the device. It usually consists of different types of metal such as aluminum, copper or stainless steel.
Metal core LED PCB
The metal provides the circuit board with proper electric insulation and heat conductivity properties.
The most common type of metalcore that many manufacturers prefer to use is aluminum.
This type of LED printed circuit board depends on the aluminum as its main base core instead of a fiberglass base.
The alloy can consist of different combinations of aluminum, magnesium, and silumin altering the properties of the metal.
The combination will vary according to the application you desire.
When thermal conductivity is not a real factor to consider, then epoxies and FR4 are the most suitable base materials.
This is because they are relatively cheap in comparison to the metal core LED printed circuit boards.
Use the metal core printed circuit board if the application will involve the production of a lot of heat.
Most of the applications or the light emitting diode printed circuit boards are on the outside environment.
It is likely to have damages due to temperature changes, moisture (rain humidity and condensation), corrosion, salt spray, and gases.
The key feature in the exterior application is the output of the device and the overall depiction of the device.
It is, therefore, important to have a cover or coating material that will protect the internal parts of the device.
The coating material will protect the LED printed circuit board from damages from moisture, excess heat and other environmental factors.
The LED PCB will, therefore, have a longer life span due to the active protection from the coating material.
The coating material of the light emitting diode PCB should not affect the efficacy, reliability, and performance of the device.
The most common type of coating manufacturers use is the conformal coating.
They are thin lacquers that can conform to the PCB contours without adding volume or weight on the device.
You can easily apply it to the LED PCB through dipping or spraying until it is 25 to 75 micrometers thick.
The coating should be very clear and remain clear throughout the life span of the LED PCB in that particular environment.
The best form of conformal coating relies on acrylic chemistry offering both color and clarity stability.
It is the best form of coating for the LED printed circuit board because of the following reasons:
- It is easy to apply to the LED printed circuit board
- It does not increase the volume and weight of the product further
- It allows for versatility in its use
- They have a unique effect on the color temperature shift
The other type of coating material available is the encapsulation resin available in different types.
It is available in certain types such as polyurethane, epoxy and silicone options. Epoxy resins are the toughest among them all but are not as flexible posing difficulty during thermal cycling.
Size of PCB
The size of the LED printed circuit board will vary depending on the type of application you intend it for.
It means that there are different sizes available for the LED PCBs that you can choose.
They range from very small LED PCBs to bigger one depending on the application.
You are at liberty of communicating to the manufacturer to make an LED PCB of different sizes depending on the application.
The bigger the device the bigger the LED PCB and the smaller it is, the smaller the device.
The factors that will determine the size of the LED PCB is the thickness of the panel and panel size.
Normally, the most common or standard panel sizes range from the smallest available to:
- Up to 10″ X 16″ (on a 12″ X 18″ panel; this panel size is commonly used)
- Up to 16″ X 22″ (on a 18″ X 24″ panel; this panel size is commonly used)
- Up to 19″ X 27″ (on a 21″ X 29″ panel; this panel size is not as common)
It is the part of the LED printed circuit board that contributes the most to the end function of the PCB.
It contains the copper circuits that are important for the functioning of the PCB.
It is the layer on top of the dielectric in an LED printed circuit board.
You can laminate the copper on the board of the printed circuit board using adhesives or heat.
The thickness of the copper varies depending on the type of application and amount of current flowing through.
Most of the LED PCBs have one ounce of copper while the others that allow more power have more.
They may have two or three ounces of copper depending on the amount of current flowing through.
You can determine the resistance of the circuit layer by looking at its length, width, and thickness.
The dielectric is a thin, thermally conductive layer that bonds to the aluminum substrate to assist in the dissipation of heat.
The key to the superior performance of the thermal class is in the dielectric of the LED printed circuit board.
In the process of designing an LED printed circuit board, remember to place the dielectric to assist in heat dissipation.
It is an insulator layer that is not electrically conductive separating aluminum from the electrical layout.
Chapter 5: Types of LED PCB
Since there are numerous applications for the light emitting diode PCB, there are different types of the PCBs.
The different types of LED PCBs have their own manufacturing specifications, usage, and type of material. Some of the most common types of LED printed circuit boards are in the following paragraphs.
Flexible LED PCB
The flexible LED printed circuit board consists of materials that can flex, twist and move in different directions including plastic.
They are available in different layer formats which include the single, double and multilayer formats.
Flexible LED PCB
The fact that you will have to print the circuit on the flexible material makes it relatively expensive.
The flexible light emitting diode printed circuit boards have numerous advantages over the rigid LED printed circuit board.
The fact that it is flexible and is able to move towards different directions makes it superior to rigid LED PCB.
It means that you are able to fold it and also bend it around different corners and edges.
The flexibility is a great asset that leads to savings on the volume, weight, and cost of creating a particular design.
You can also use it in different areas that are usually environmentally hazardous and might be harmful to other types.
This is because they have materials that are waterproof, corrosion proof, shockproof and resistance to oils of high temperature.
Rigid LED PCB
Just as the name suggests, the rigid LED printed circuit board is stiff and cannot bend in different directions.
Manufacturers use solid materials as the substrates thus preventing the board from twisting in different directions.
The most common type of rigid LED printed circuit board is the one you will find in a computer.
The rigid LED printed circuit boards to make the highest number of PCBs that manufacturers make.
You will find them in many places where one needs to use an LED PCB that should stay in shape forever.
You will find them available in different forms which include single, double or multilayer LED printed circuit boards.
Hybrid LED PCB
The hybrid LED PCB includes a material that is non-thermal together with a base metal such as aluminum.
In many cases, the hybrid LED printed circuit board consists of the conventional FR4 binding with the aluminum substrate.
The joining of the two parts makes it easy for the device to dissipate heat in a more efficient manner.
Hybrid LED PCB – Source: DIYForums
Apart from an increase in the rate of heat dissipation, the device has better rigidity making it very strong.
The hybrids are also less expensive in comparison to a rigid aluminum light emitting diode printed circuit board.
It also has its disadvantages which includes the lack of flexibility thus making a bend is difficult.
Multi-layer LED PCB
Multi-layer PCBs consists of more than two double layers light emitting diode printed circuit board.
The multiple layers stick together using a special type of glue and between different types of insulators.
The insulators will make sure that none of the layers of the LED printed circuit board melt due to excess heat.
Multi layer PCB
They are available in different sizes where you can find a small one with as low as four layers. You can also get a bigger one with 12 layers or more in different LED applications.
The maximum number of layers we know about is 50 and it was for a major application.
The multilayer LED printed circuit boards to exist for use in complicated electrical applications.
Single-layer LED PCB
A single layer light emitting diode PCB has only one side with the circuit or basically one layer of the substrate.
On one side of the base material is a very thin metal layer preferably copper as it is a good conductor.
After applying the copper base, the next step is the application of a protective solder mask.
Single layer PCB
After that, you can follow apply a silk screen that marks out every element available on the board.
They are very simple LED printed circuit boards that are easy to design and subsequently manufacture.
You can, therefore, purchase them at very low prices and in very high volumes.
The advantages of using this type of LED PCB layer makes it an important component in many applications.
Chapter 6: LED PCB vs. Standard PCB – What Makes LED PCB Unique
LED printed circuit boards are one of the cheapest modes of lighting that many people embrace and is increasingly becoming popular.
It is the main reason why the metal core printed circuit board is also in high demand.
The LED PCB lighting system can be five times cheaper in comparison to the standard PCB systems.
LED Lighting system
The LED printed circuit board is more efficient in terms of consumption of space.
It covers very little space and the output or efficacy is also very high.
It performs better in comparison to the standard PCB and also conserves space and energy.
Due to the efficacy of the LED PCBs, many devices prefer replacing the standard PCB with the LED printed circuit boards.
There is, however, an aspect of the LED printed circuit board that one has to take care of first.
The fact that it emits a lot of heat makes the standard PCB a desirable device in comparison to LED PCB.
The heat problem that many people associate with the LED printed circuit boards has a solution.
To maintain the LED lighting system for a longer period without damage, manufacturers incorporate the metal core printed circuit board.
The metal core will assist in the dissipation of excess heat from the system making more efficient than standard PCBs.
The LED printed circuit board has a metal plate on the lower side which is of various thickness.
The standard PCB does not have the metal plate at the bottom and has surface finishing and solder masks.
In the LED printed circuit boards you will find the solder mask and surface finishing on one side.
The LED printed circuit is unique because it has the components on the surface rather than using the through holes.
This because it usually has a metal plate at the bottom to assist in the dissipation of heat.
The presence of the through holes on the LED printed circuit board would lead to a shot thus the unique features.
There are certain types of LED PCBs that have vias especially if it has more than one FR4 substrate layers.
This type of LED PCB dissipates heat through the vias making it quite similar to the standard PCBs.
The work that vias perform in the LED PCB is the responsibility of the components of the metal core printed circuit board.
Apart from that, the LED PCB is unique since the holes that you will drill on the boards are for mounting.
It is different from the standard PCB which has via holes for dissipation of heat. The mounting holes on the LED PCBs are also larger than via holes on the standard PCBs.
The multilayer LED printed circuit boards are costly to design and manufacture due to the cost of material.
The incorporation of aluminum between every layer of the multilayer PCB makes it costly in comparison to standard PCB.
Even though it has to pass through certain restrictions of design, the process is almost similar to standard PCBs.
The color of the solder mask also poses a unique feature to the LED printed circuit board. The standard PCB has an array of dark colors such as black, red, green, and blue.
The LED printed circuit board has only one color which is white on one the upper side of the board.
The thickness of the standard PCB varies widely, due to the various combination of different materials and layer counts.
The thickness of the LED printed circuit has certain limits to the available thickness of the backing plate.
The thickness of the dielectric sheet will also determine how thick the LED printed circuit board will be.
The process of machining both standards and LED printed circuit board is similar in most cases.
It means that both boards undergo routing, drilling, countersink, v-scoring, and counterbore. The major difference making the LED PCB unique is the fact that it relies on a diamond coated saw blade for v-scoring.
Chapter 7: LED PCB Circuit Design – How to Make LED PCBs
The process of designing an LED printed circuit board starts with having a designing software to assist in designing.
Apart from that, you will also require an LED printed circuit board designer to help you or guide you in the process.
There are many PCB design software that you can use in making a proper design for the LED printed circuit board.
PCB Design Software
Some of the design software that you can use in making the designs include:
- PCBWeb Designer
- Osmond PCB
- Altium designer
Designing a PCB will begin with the design engineer ready to explore his wits, tools, schematic captures, and layout software packages.
The engineer should have the exact picture of the LED PCB design in mind before he begins to design.
It also includes the image of the end product they think they can achieve using the tools that are available.
The tools must be able to balance performance and power making it intuitive and easy to use.
The software should also contain all the requirements for the design beyond PCB editor and schematic editor.
The software should have a library, analysis, simulation, verification and documentation tools for the success of the LED PCB design.
You will begin by finding the schematic and drawing the schematic diagram on the computer software for designing LED PCBs.
After that, you have to transfer the schematic diagram into the drawing of the LED printed circuit board.
Doing the drawing is considered to be great artwork and requires you to take your time and make it good.
Look at the size of the board and the trace width of the board. There are certain limits to how thin or how big your traces and your board can be.
You should also keep in mind the size of the smallest drill available for use.
The trace width should be the size of the smallest trace width or thicker as thin traces are vulnerable to damage.
Consider the amount of current that will flow through the design and adjust the thickness of the board accordingly.
It means that the more the current flowing through the board the thicker the board should be.
LED PCB design
You should keep in touch with your manufacturer so that he can see every step of the designing process.
You can as well send him copies of the design drawings so that he can create a picture in his mind.
He can also advise you on the things that you need to do as you design the LED PCB.
When making the design, make sure that you place all the components of the LED PCB on the design.
The components should be at the right places and in the exact position you want them to be at.
The software will guide you through these steps and avoid making mistakes on the design to have a good product.
Placing the components at the right place as the schematic will help you in troubleshooting the circuit.
Pay extra attention to the large components and the connectors placing the connectors on the side for easy connections.
De-coupling capacitors should be close to the pins that you will connect to the capacitors.
All the components on the design should have the relevant labels with the part value and the name.
It will make it easier for the manufacturer to solder and also assist in troubleshooting.
The rule-of-thumb is to label all the connectors on the outside with the right names for description.
Some of the rules that you need to follow include:
- For a two-layer circuit board, route one layer vertically and the other horizontally.
- For an RF circuit board avoid angles at 90 degrees on the PCB traces to avoid the weird effect. The 45 degrees angle also looks professional and you should make it a habit.
You can follow the outlines available for drawing the design but most design software will have the necessary tools.
At this point, you should think about the final placement of the LED printed circuit board.
You can print the final drawing on a paper and test if it will fit the final placement point.
Remember that you need to get your board ready for manufacture as you make the design.
It means that you need to check on the board layout, for any errors and then convert to Gerber files.
This is the final process of designing and you can send it to the manufacturer for assembly.
Chapter 8: LED PCB Assembly Process
With the LED PCB design at hand, you are in a position to assemble and make the final board.
There are, however, a few steps that you need to look at before actually beginning the PCB assembly process.
These steps will help you know if the design will actually work after it is complete into a circuit board.
Fully assembled LED PCB
The process includes a DFM check with the exact design, design rules and specific requirements at hand.
It involves looking at all the specifications for the design, looking for any redundant, missing and problematic features.
An example of the PCB flaw is leaving very small spaces between the components of the PCB causing shots.
The DFM check will help in eliminating any problems before you waste money by making a dysfunctional LED PCB. The DFM/DFA checks should come as an assembly package from the manufacturers to assist in making proper PCBs.
The first step is solder paste stenciling which involves the application of solder paste to the board of the PCB.
You will place a stainless steel stencil on the printed circuit board allowing you to do the selective application.
It will assist in knowing the parts where the components will be sitting when the LED PCB is complete.
The solder paste that you will use consists of 96.5% tin, 3% of silver and 0.5% of copper.
Remember to apply the solder paste at the exact points of the board and also in the right amount.
The second step involves taking the board through the pick and place the robotic device to place the exact components.
The machine will not only place the components but also the SMDs accounting for most of the non-connector components.
You will then solder the SMDs on the board so that they can stick to the board well.
This process was once a manual project where manufacturers would pick and place the components by hand.
The machines replace human effort as they are more accurate, precise and faster than the humans with no fatigue issues.
The process involves picking up a PCB board using a vacuum grip and placing it on the picking and placing station.
The robot will orient the PCB and start applying SMTs to the surface of the printed circuit board.
It will be placing the components on the surface of the solder paste according to the locations on the program.
The third step is reflow soldering which involves sticking the components of the PCB on the board.
It means that you need to allow the solder paste to solidify making the components adhere to the board.
The process of allowing the components to stick or adhere to the board is the reflow process.
The process involves taking the board from the pick and place stand and placing it on a conveyer belt.
The conveyer belt will move through the reflow oven heating the board at 250 degrees Celsius.
The solder melts and moves through cooler heaters which solidify the solder in a proper manner.
This process will create a strong and permanent joint holding all the SMDs to the printed circuit board.
The fourth step involves doing inspections and controlling the quality of the LED printed circuit board.
Inspections are very important as the board might have very poor connections and shorts due to components in the wrong places.
There are many inspection methods that manufacturers use as you will learn shortly.
Manual checks are still common despite the fact that most of the processes are automatic.
Visual inspection of the boards by the designer especially in small batches is very important.
As the number of boards that require inspection increases, the method of doing manual checks becomes obsolete.
Inspections using the eye over a long period might lead to visual fatigue.
Once the eye is tired, there are many errors that can occur making it inaccurate. It, therefore, opens avenues for more accurate inspection processes.
The automatic optical inspection which is more accurate a method for the large batches of the LED PCBs.
An automatic optical inspection (AOI) machine uses cameras with high optical visualization to assist in the inspection.
The cameras are in different angles and will assist in checking errors in the connections.
The board is under illumination and the cameras are able to detect poor quality solder connections.
Normally, the poor connections and soldering will reflect light differently making it easy to detect.
The machine is able to process a huge batch of LED PCBs in a very short time.
X-ray inspection method which is not very common and uses X-rays to assist in the inspection.
Manufacturers use it to inspect complex and multilayer LED printed circuit boards.
The X-rays will allow you as the viewer to see any internal problems on the multiple layers and fix them.
In case of any problems, the LED PCB will have to go back through the process of designing.
The problem might also be small and the manufacturer can decide to fix it depending on their policies.
After that, you should inspect it again and see if it will perform in a particular manner it should perform.
The fifth step in the insertion of the components through the through hole among them being the LEDs.
These holes will assist in passing signals from different sides of the board. In this case, you will have to replace the soldering paste with other types of soldering such as:
- Manual soldering where different people will insert different components into the through holes at different stations. It is a lengthy and tiresome process depending on the number of components you need to insert. Many manufacturers avoid this process even though there are others who still consider using it.
- Wave soldering which is a more automatic version of manual soldering through a different process. After placing the components in the right hole, the board goes through an oven on a conveyer belt. It will wash a wave of solder on the bottom part of the LED printed circuit board.
After all these processes are complete, you can run the Board through the inspection unit to test the functionality.
Assembling LED PCB
The last step is the functional test passing the PCB through different paces simulating its functionality.
Simulated and power signals will run through the board as testers check on the electrical characteristics.
In case of any problems, you might have to go through the whole assembly process again till it functions properly.
Chapter 9: LED PCB Board Replacement
The LED PCB is the same as all the other features of machines that are susceptible to damage. In case any part or the whole board is not functioning well, you can replace it with a new LED PCB board. Since there are many applications of the LED PCBs, let’s look at LED ceiling light PCB board replacement.
The first step in replacing the board will involve disconnecting the whole unit from the power source.
This step will allow you to work without the risk of electrocution. Remember to have the necessary protective gear to protect you.
After disconnecting the power from the source, you can remove the LED Ceiling light from the ceiling.
Place it on a table or a workbench and remove the cover so as to expose the LED printed circuit board.
Inspect the board to find out the type and extent of damage on the board.
Depending on the fastener, use a screwdriver or a spanner to release the LED printed circuit board.
Unplug any other connection to the LED printed circuit board allowing it to be free. Remove it gently and place it on the workbench carefully.
At this point, you should be having the new LED printed circuit board on standby.
Take the new LED PCB and replace it at the exact point where the other one was making sure it fits well.
Fasten it in position and make sure that it sticks to the external component properly.
Replace the plugs to the exact point of connection and put the cover back in place.
Re-install the whole unit back to the ceiling making sure it stays in place. Power the system to see if the new LED PCB functions properly.
The information on the LED printed circuit boards will guide you through different LED PCB applications.
It will also assist you in making the right choice for the type of LED PCB that you may need. You are now in a position to call your designer to help you make custom LED printed circuit board.