The innovative road of LED lighting

By Paul Golata Mouser Electronics

Various packaging forms

Over the past decade, LEDs have exploded in popularity for general lighting applications. LEDs offer significant advantages over traditional lighting sources, including reliability, long life, low power consumption, small size, high efficiency (light produced per energy consumed), and design flexibility. LED manufacturers have been working to increase the availability of innovative designs for users and improve their products by incorporating a variety of packaging options. Three main areas worth investigating are: (a) discrete components, (b) integrated and conventional arrays, and (c) packaged solutions such as LED modules.

Discrete High Power Lighting LED

When we think of lighting class LEDs, we usually think of discrete high power (1W or higher) LEDs. A discrete LED is a semiconductor diode that is packaged in a suitable, independent thermo-mechanical package. Ideally, discrete LEDs are both bright and small. The footprint on these package types will decrease over time. Some common package footprints in recent years are 12 mm2 and 6.3 mm2. LEDs such as the Philips Lumileds LUXEON® Z family have a footprint of only 2.2 mm2, providing extremely high design density. LED manufacturers strive to provide the highest possible light output power in the smallest possible package size. Thermal resistance (°C/W) is often the limiting factor in discrete (single LED) designs. LED packages with low thermal resistance have better heat dissipation performance.

Figure 1: Example of a discrete high-power lighting LED - Philips Lumileds' LUXEON Z platform, with a footprint of only 1.3 mm x 1.7 mm = 2.2 mm2

Discrete mid-power LEDs: an emerging category

Over the past few years, the proliferation of linear and distributed lighting applications has led several LED manufacturers to target a new product category: mid-power LEDs. These packages are generally defined as LED packages that consume between 0.2W and 1.W (3 VDC x [75 mA to 250 mA]). These mid-power products typically use a similar footprint as higher brightness (> 1W) LEDs, but in a different package type. The lower cost and lower total light output power allows for more LEDs per linear meter, resulting in a softer, more diffuse lighting pattern that replicates the softer visual output that users are accustomed to.

Array

Once LED manufacturers developed their discrete LED product lines, they quickly realized that integrating multiple LED chips into a single thermo-mechanical package would provide many advantages. One reason for this was the increasing requirements for Correlated Color Temperature (CCT) consistency in general lighting applications. One of the advantages of LED arrays is that LED manufacturers can control the mix and match of LED chips in a very small physical footprint through a discrete package for electrical control and a discrete window and/or lens arrangement for optical control. This configuration is common in many package styles, with the most common form integrating four chips into a single package.

Integrated (chip-on-board) array

LED manufacturers continue to focus on their customers’ end applications and aim to meet their needs with another innovative concept: integrated arrays or chip-on-board (COB) arrays. This technology takes the advantages of arrays and further enhances them by mounting the LED chips directly onto a circuit board or substrate, resulting in a unique package that allows manufacturers to package the entire array with a phosphor window and ultimately achieve high-efficiency, high-lumen output light efficacy in a single integrated component. This packaged array is particularly attractive when high lumen output is required from a single light source.

Comprehensive Solution - Modules

Selling more LEDs is the goal pursued by LED manufacturers, but they realize that successful designs are difficult for many customers to achieve. To alleviate the design challenges, many LED manufacturers have been committed to improving the customer design chain to provide customers with comprehensive solutions. These solutions usually combine LED, light, electrical and mechanical characteristics into a product called a module, and Cree's LMH product series is a representative example.

Figure 2: Cree's LMH module, a comprehensive solution

in conclusion

Mouser Electronics is a company focused on providing design engineers and buyers with the latest LED lighting products and leading technologies, with excellent customer service and global support centers. The stock has the broadest and deepest best-selling LED components, optical components, electrical components and mechanical products to support LED lighting design. For more information on how to select and design LED products, please visit www.mouser.cn/applications/lighting.

1: An LED module is a light source device with one or more LEDs. In addition, it may also contain some other components, such as optical components, mechanical components and electronic components, but does not include the control part. For Zhaga standards, please visit http://www.zhagastandard.org/faq/

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