LED base plates, or LED PCB bases, are a type of bottom component for LED packaging. In an LED lamp, the LED chips are directly attached to the base plate, and then a lens is placed above the chips. An LED base plate provides the LED chip and wires with circuit connection, mechanical support, airtightness protection, and thermal dissipation.
Most of the LED PCB bases are aluminum-substrate, but as LED lighting requires more and more brightness and longer shelf life, ceramic PCB base plates for LED merge. Which type of LED PCB plate is better? In this article, we will introduce different LED base PCBs and make a comparison of them from the below parts.
Part 1: Types of LED PCB Bases
LED chips are sensitive to temperatures. When LEDs illuminate, a great amount of heat is generated. The larger the current, the brighter the LED light. If the thermal is not dissipated immediately, the temperature rises. In turn, the elevating temperatures reduce the LED power and brightness. So the LED lamps have to solve the thermal dissipation problem, and choosing the PCB base plates is vital.
LED PCB base plates have two main types: LED aluminum base plates and ceramic LED base plates. Ceramic LED base plates have two types - alumina LED PCB base and aluminum nitride PCB base.
Part 2: Aluminum LED PCB Base Plate
- Appropriate for: LEDs with not-so-high power requirement
- Pros: aluminum has good thermal dissipation
- Cons: overall insufficient thermal dissipation; high expense
Aluminum has good thermal dissipation of 237W/mK but no electrical insulation at all. To make aluminum into an LED base plate, an insulation layer is added. However, the insulation layer has poor thermal dissipation. As a result, the aluminum LED PCB base plate has overall thermal dissipation only a little better than plastic.
When it works, the thermal transfers from the LED chips quickly to the aluminum layer and then to the insulation layer. However, due to the poor thermal dissipation, the thermal accumulates in the insulation layer. Though the thermal is not accumulated in the LED chips, when the LED lamp has higher power or works for a longer period, the chips are affected by thermal eventually.
Meanwhile, due to the insulation layer, the metal base plate can’t be welded at high temperatures, and there are insufficient possibilities for LED package optimization.
Besides, the aluminum LED base plate requires a fan to dissipate thermal, which takes up quite some space. And the aluminum price has been high in recent years.
It is known that the trend of LED lamps is to get a smaller size, a higher power, a longer shelf life, and if possible, a lower cost. The aluminum LED PCB plate is not following this trend.
Part 3: Alumina LED PCB Base Plate
- Appropriate for: normal LED lamps
- Pros: higher thermal dissipation than aluminum base plate; lower cost
- Cons: higher thermal expansion coefficient than Si; inappropriate for high-power circuits; fragile
Alumina is currently the most used ceramic LED base plate material. The ceramic material alumina has thermal conductivity from 15W/mK to 50W/mK and good electrical insulation. When alumina is made into an LED PCB base, it has a thermal conductivity 10 times of the aluminum LED base plate. For traditional LED lamps for cars, the alumina base plate has enough thermal dissipation.
Besides, alumina is a cheap ceramic material. And there is no need to add an insulation layer and a fan.
However, the alumina LED PCB base plate has a higher thermal expansion coefficient than semiconductors. At 20°C to 300°C, the thermal expansion coefficient of 96% alumina is 6~7.5×10ˆ-6°C. For 99% alumina, it is 8~10×10ˆ-6°C. As for Si, the most used semiconductor, its thermal expansion coefficient is 3.5~4×10ˆ-6°C for Si. For this reason, the alumina LED PCB base plate is not appropriate for LED packaging used for high-frequency, high-power, and large-scale integrated circuits.
LED lamps for cars, ships, photography, and so on are developing to higher powers for brighter light now and in the future. Traditional LED lamps are gradually replaced by high-power LEDs. Alumina LED base plates will also lose their majority in ceramic LED PCB base plates.
Part 4: Aluminum Nitride LED PCB Base Plate
- Appropriate for: large-scale integrated circuits; small-size/high-power LED
- Pros: matched thermal expansion coefficient with semiconductors; higher thermal expansion than alumina; high strength; good optical transmission; excellent electrical performance
- Cons: an oxide layer can affect its thermal expansion; higher cost than alumina LED PCB base plate
Finally, we get to tell about the aluminum nitride (AlN) LED PCB base plate. AlN is a promising electronic ceramic packaging material and AlN PCB is considered to be the most ideal LED PCB base.
The thermal conductivity of the AlN LED PCB base is 7 times higher than the alumina LED PCB base and 100 times higher than the aluminum base plate. For high-power LEDs for cars, ships, photography, spotlights, and so on, AlN is the most excellent PCB base plate option.
Besides, aluminum nitride has a greater hardness than alumina. And unlike normal ceramic, an AlN PCB base plate has good strength.
In addition, aluminum nitride LED base plates have a similar thermal expansion coefficient (4.6×10ˆ-6°C) with Si ((3.5~4×10ˆ-6°C). As the LED chips are made of Si, the close thermal expansion of the base plate and chips reduce the risk of circuit desoldering and keeps the good performance of the LED lamp.
Apart from the LED base plate, the excellent characteristics of the AlN PCB make it have many other high-end applications.
On the contrary, the drawbacks are few.
Aluminum nitride is more expensive than alumina and so is when they are made into LED base plates.
Aluminum nitride PCB base plates should not have an oxide layer on their circuit layer because even a very thin oxide layer can affect the plate's thermal conductivity.
Thankfully, PCBONLINE has strict quality control over the AlN PCB materials and manufacturing, and the AlN PCB LED base plates it manufactures have good consistency.
Part 5: Comparison of Different LED Base Plates
We have analyzed different LED base plates and listed their pros and cons. Here let's sort them by different aspects.
- Thermal conductivity: aluminum nitride LED base plate > alumina LED base plate > aluminum LED base plate
- Semiconductor thermal expansion suitability: aluminum nitride LED base plate > alumina LED base plate > aluminum LED base plate
- Welding performance: aluminum nitride LED base plate > alumina LED base plate > aluminum LED base plate
- Strength: aluminum LED base plate > aluminum nitride LED base plate > alumina LED base plate
- Cost: aluminum LED base plate > aluminum nitride LED base plate > alumina LED base plate
We can say that the aluminum nitride LED PCB base plate is the best, the alumina base plate second, and the aluminum base plate the third name. But in applications, all of them are widely used LED base plates.
Best Tailored LED Base Plates Manufactured at PCBONLINE
PCBONLINE is a leading high-end PCB manufacturer and assembler since 1999. It has an aluminum PCB factory achieving industry 4.0 manufacturing and a ceramic PCB factory specializing in alumina and aluminum nitride PCB and products.
Here are some metrics of the AlN LED base plates manufactured by PCBONLINE:
- PCBONLINE adopts the DPC technology to manufacture aluminum nitride PCB LED base plates (3D capability).
- The thermal conductivity is 180 W/mK ~ 260 W/mK, which meets the high-power LED thermal dissipation demand easily.
- Besides, the ceramic materials have excellent anti-ultraviolet properties and anti-aging properties, which further extend the life cycle of LED products.
- PCBONLINE's aluminum nitride PCB LED base plates have no oxide layer and have a long shelf life in aggressive environments.
PCBONLINE is dedicated to providing the best custom LED base plates to engineers/companies/business makers. You are welcome to get an instant quote now. Remember to register online and get $100 coupons for online purchases first!
Showcase of LED PCB Base Plates
Model: 3532 LED base plate
Material: aluminum nitride
Surface finish: nickel palladium gold
Lens type: square cup
Dam height: T1=0.4mm T2=0.15mm (tolerance ±0.05mm)
Finished product thickness: 1.2mm (tolerance ±0.15mm)
Note: the T2 part is slotted to prevent glue overflow during packaging.
Conclusion
This article aims not to rank the LED base plates but to make an analysis of different LED base plates. We can say the aluminum nitride PCB base plate is the most promising LED base plate. However, different devices or LED lamps require different base plates for LED packaging. If you have some concerns, welcome to leave your comments or contact us by email at info@pcbonline.com.
