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What Is A Surface-Mounted Diode?

Posted by Richard Clarke on 23rd Jul 2012

Time For Questions

When you’re shopping for LED bulbs, you’ll encounter two types of LED (Light-Emitting Diode). One is a regular LED, and the other is a more advanced type that’s called an SMD or “Surface-Mounted Diode”. 

So What Is A Surface-Mounted Diode? 

Before tackling this question, it’s good to know that a “Diode” is a semiconductor device with two terminals, typically allowing the flow of electrical current in one direction only. A Surface-Mounted Diode is a type that emits light and that’s mounted and soldered flat against a circuit board. In this respect, it’s quite unlike standard LEDs which rely on wire leads to hold them in place.

What Makes SMDs Better Than Regular LEDs? 

SMDs offer a number of advantages over their "through-hole" counterparts, including their reduced size, improved beam angle and lower cost.

With normal LEDs, you’ll find that they’re accompanied by a lot of extra accoutrements, including the aforementioned wire leads, as well as additional optical light diffusers. With an SMD, most of this extraneous material is surplus to requirements, leaving only the part of the LED that emits light remaining.

The obvious advantage here is that SMDs can be made much smaller; usually between a quarter and a tenth of the size and weight of an equivalent through-hole component.

Two Sizes To Choose From

SMDs used for lighting typically come in two sizes. There’s the 3.5mm by 2.8mm (3528) and the 5mm by 5mm (5050), but some of the smallest are less than a millimetre in size. In the context of lighting, this means the size of LED bulbs can be smaller, whilst their power and luminescence can be increased.

Improved Light Diffusion

The absence of a light diffuser also allows for an improved beam angle. Normal LEDs are limited to a fairly narrow beam angle, because the epoxy casing acts as a focusing lens. In contrast, the light from an SMD is very diffuse, which makes them suitable for applications that require a wide beam angle, such as ambient lighting and in rooms with low ceilings.

In comparison with the traditional, yet very labour-intensive manufacturing process required by through-hole LEDs, SMDs can be assembled very quickly and inexpensively, with some machines capable of placing hundreds of thousands of components per hour. This allows for an end product that is more affordable, whilst still retaining the build-quality and reliability that people have come to expect from their traditional LED counterparts.

Widely Used

SMDs are used in a wide range of LED Lighting products, including GU10 LED bulbsLED floodlights and LED strip lights, and they’ll provide you with brilliant, cost-effective and long-lasting illumination in exactly the way traditional LEDs did...only better!

Indeed, requiring 90% less energy and a life-expectancy that’s 20 times longer than incandescent lights, you can expect to recoup your initial investment on SMD-equipped LED bulbs within a very short time.

So, if you’d like more information about SMDs, please call 0116 321 4120 or e-mail us at cs@wled.co.uk.

You can also see our full range of LED lighting products on our online store.

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