Aluminium is the first choice for making the PCBs used in LED lights

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The relatively low cost of aluminium compared to copper and steel, its light weight, excellent durability and its heat transferring capabilities are some of the reasons why this metal is increasingly being used in the manufacture of metal core PCBs for LED lights.

By Priyanka Kumari

In recent times, metal core PCBs (MCPCBs) have gained popularity in the LED industry. The PCBs used in LED lighting require specific properties as the latter are temperature-sensitive. MCPCBs are today being used in high current LEDs and spotlights.

In the case of MCPCBs, the core or the base material is a metal instead of the traditional FR4/CEM1-3. In an FR4 board, heat remains stagnant if not transferred by a topical heat-sink. Another material for making PCBs, though less commonly used, is an epoxy. A PCB made of epoxy is considered less durable. However, in cases where thermal quality is not very important, FR4 or epoxy bases are more common as these are less expensive.

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Commonly used metals for PCBs are aluminium, copper and steel alloys. Apart from being cheaper than copper, aluminium is known for its good heat transferring and dissipation abilities. However, copper is considered to be a better performer. Both normal steel and stainless steel are more rigid and have less thermal conductivity than aluminium and copper. The choice of the core depends on the desired output and application. In general, aluminium is laminated with copper.

Aluminium PCBs
In recent times, among MCPCBs, the aluminium variants are gaining popularity. They are built on top of an aluminium alloy base (comprising magnesium, aluminium and silumin) instead of a fibre glass base. This alloy is designed to provide maximum electrical insulation and thermal conductivity. Generally, a thin layer of thermally conductive but electrically insulating dielectric is laminated between a metal base and a copper foil, which is etched into the desired circuit pattern. The metal base draws heat away from this circuit through the thin dielectric.

Aluminium PCBs and the LED lighting industry
Several qualities, including better heat dissipation, have led to aluminium PCBs becoming the new standard for many companies in the LED industry. Some of its key features and benefits include the following.

  • Better heat transfer: Heat transfer refers to the movement of thermal energy from one place to another. As is well known in the electronics field, constant high temperatures can lead to the PCB getting damaged, which affects its functionality, making heat transfer one of the most important aspects of PCB manufacture. Aluminium is known for its heat transferring capabilities. It can transfer heat away from critical parts to reduce thermal damage to the PCB. In comparison to fibre glass, aluminium designs can be up to 10 times more efficient.
  • High durability: Aluminium is sturdier in comparison to ceramic and fibre glass. Resistant to breakage, it can better handle the stress involved in the process of manufacturing. It also does not get easily damaged during day to day handling, especially in impact-prone environments.
  • Light in weight: In addition to its durable characteristics, aluminium is known to be light in weight. This results in improved resilience, an important factor in manufacturing. The lighter the PCB and in turn the end product in which it is used, the easier it is to handle and ship.
  • Less expensive: Aluminium is found across the globe and is easier to refine than other metals, making it less expensive. In comparison with other methods of heat transfer such as heat-sinks, a PCB made of aluminium is inexpensive. Though heat-sinks may be more effective in transferring heat, they are costlier to add on to the PCB.
  • Environment-friendly: Being recyclable and having no toxic properties, aluminium PCBs can be easily disposed.
  • Increased LED density: A fibre glass design transfers heat relatively slowly, causing the heat to build up. This factor limits the number of LEDs on the board. But in the case of aluminium, more LEDs can be put on the board and can function efficiently without exceeding the specified temperature tolerance. Due to the high thermal conductivity of aluminium, the heat transfers quickly.
  • Longer operating time: It is known that when used for long durations, LEDs tend to get heated, impacting the quality and colour of the light as well as the overall life span of the product. With better heat transferring capabilities, aluminium PCBs help LEDs to operate at a lower temperature and hence increase their life span.

Applications of LED lighting
Due to their design flexibility, energy efficiency and low cost, aluminium PCBs are increasingly used in various lighting applications and across several industries. Some common use cases include automotive headlights, airport runway landing lights, lighting used in military field applications, street lighting, highway tunnel lighting, photovoltaic or solar lighting, flashlights and lanterns, traffic and signal lighting, lighting in hospital operating rooms and high growth plant lighting, among others. Some prominent applications of aluminium PCBs are mentioned below.

  • Telecommunications: In the telecommunications sector, aluminium PCBs are used in various filtering appliances and high-frequency amplifiers.
  • Automotive: In the automotive sector, aluminium PCB LEDs can be found in car indicators, headlights and brake lights, apart from electronic regulators and power controllers.
    Computers: In this category, aluminium PCBs are used in LED displays, indicators, power devices and CPU boards.
  • Medical: Lighting tools for surgery and medical examinations use high-powered LED lights. Medical scanning technology also uses aluminium PCBs.

Market dynamics: Growth drivers and challenges
According to the latest market research report by Industry ARC, the global PCB market is estimated to hit US$ 70 billion by 2024. The Asia-Pacific is the leading market and is estimated to grow at a rate of 36.87 per cent to reach US$ 6.4 billion by 2024. This market is mainly driven by the growing need for smart devices in consumer electronics. Standard multi-layer PCBs have the largest share of the market and are expected to continue their dominance in the global market, reaching about US$ 1.27 billion by the end of 2024. Owing to the need for smaller and lighter boards for use in electrical devices, military/ healthcare equipment and other industry verticals, the demand for these boards is increasing rapidly

As per a study conducted by the Electronic Industries Association of India (ELCINA) the demand for PCBs in India is growing at a CAGR of 20.56 per cent over the period 2015-2020, and will reach over US$ 6 billion by 2020.The major growth drivers include consumer electronics, industrial electronics, strategic electronics, computer hardware, mobile phones, automotive, telecom and the LED lighting industries.

The study mentions that around 60 per cent of Indian manufacturers are SMEs and belong to the unorganised sector. The country is dependent on imports to meet approximately 65 per cent of its requirements. Some of the key challenges that the Indian industry faces include profitability (which hinders investments in new manufacturing technology), an inefficient supply chain for raw materials, high capital expenditure and lack of access to low cost finance, taxation issues and logistics inefficiencies. These factors lead to longer turnaround times and increased costs.

A few of the latest products available in the market

Product: MCPCB for general LED lighting applications Manufacturer: Cambridge Nanotherm
The company uses a patented electrochemical process to create a 20μ-thick dielectric layer of alumina atomically bonded to an aluminium board. This MCPCB has a thermal efficiency of 120W/mK, offering electronic designers an increase of over 56 per cent compared to the thermal conductivity of an aluminium plate. It can be applied to chip scale packaged (CSP) modules, Chip-on-Board LED (COB LED) modules, high density LED modules, automotive lighting modules, horticultural lighting and power semiconductors.
Key features:

  • Robust stability at an operating temperature of 130°C
  • Lead-free solder compatible
  • RoHS and UL recognised
  • Layer of electrically isolating alumina (Al2O3) formed on aluminium base
  • Ultra-thin layer of adhesive to attach a copper foil circuit trace

Contact details: www.camnano.com

Product: 1X3 Lux-M Linear; Manufacturer: Sinkpad
Built on SinkPAD TM-II direct thermal path PCB technology, this PCB delivers a high thermal performance. It is offered in a 3, 4 or 5 LUXEON M LED footprint, and is designed for easy systems integration and faster time to market. Industry standard optics can be used.

Key features:

  • Shape: Linear
  • PCB finish thickness: 0.065mm
  • Surface finish: Lead-free HASL
  • Thermal conductivity: 210.0 W/mk
  • LED configuration: 1×3 series
  • Glass transition temperature: 170°C
  • UL approved and RoHS compliant

Contact details: www.sinkpad.com

Product: 20.5mm round-3XP aluminium; Manufacturer: Sinkpad
The base metal of this PCB is made of aluminium. It is compatible with several LEDs including XHP35, XP-G, N219A and 3535. The configuration of this multi-LED PCB needs to be parallel.

Key features:

  • PCB size: 0.807mm
  • Shape: Round
  • PCB finish thickness: 0.065mm
  • Surface finish: Lead-free HASL
  • Glass transition temperature: 170°C
  • UL approved and RoHS compliant

Contact details: www.sinkpad.com

Product: AI PCB; Manufacturer: XNJ PCB
This is a unique, metal based and copper-clad laminate PCB with good thermal conductivity, electrical insulation and machining properties. This PCB uses the Fuchs Wright aluminium substrate and is used in the LED industry.

Key features:

  • Surface finishing: Lead-free Hot Air Solder Leveling (HASL), golden finger, immersion gold/tin/silver plated hard gold, etc
  • Maximum size: 1200mm x 646mm
  • PCB thickness: 0.5mm – 6.0mm
  • Shapes: Die punching, stamping, route, V-cut
  • Hole tolerance: -0.05mm~0.05mm
  • Laser drilling hole size: 0.075mm
  • Minimum line width and line spacing: 0.075mm

Contact details: www.xnjpcb.com

Product: STAR PCB for 1-LED CREE XHP35; Manufacturer: LED Mounting Bases Company
An exclusive designing and manufacturing contract between Cree and LED Mounting Bases has resulted in the MCPCB being manufactured with UL certified aluminium substrates. It has a high thermal conductivity of 2W/mK.

Key features:

  • Number of LEDs: One
  • Shape: Star
  • PCB thickness: 1.6mm
  • Material: Aluminium, as per UL guidelines

Contact details: www.led-mounting-bases.com

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