Description

The early red LEDs were bright enough only for use as indicators, as the light output was not enough to illuminate an area. Readouts in calculators

were so small that plastic lenses were built over each digit to make them legible. Later, other colors became widely available and appeared in

appliances and equipment.

Early LEDs were packaged in metal cases similar to those of transistors, with a glass window or lens to let the light out. Modern indicator LEDs are

packed in transparent molded plastic cases, tubular or rectangular in shape, and often tinted to match the device color. Infrared devices may be dyed,

to block visible light. More complex packages have been adapted for efficient heat dissipation in?high-power LEDs. Surface-mounted LEDs further

reduce the package size. LEDs intended for use with?fiber optics?cables may be provided with an optical connector.

LEDs are produced in a variety of shapes and sizes. The color of the plastic lens is often the same as the actual color of light emitted, but not always.

For instance, purple plastic is often used for infrared LEDs, and most blue devices have colorless housings.

Modern high-power LEDs such as those used for lighting and backlighting are generally found  (SMT) packages (not shown).

LEDs are made in different packages for different applications. A single or a few LED junctions may be packed in one miniature device for use as an

indicator or pilot lamp. An LED array may include controlling circuits within the same package, which may range from a simple resistor, blinking or

color changing control, or an addressable controller for RGB devices. Higher-powered white-emitting devices will be mounted on heat sinks and will

be used for illumination. Alphanumeric displays in dot matrix or bar formats are widely available. Special packages permit connection of LEDs to

optical fibers for high-speed data communication links.

High-power LEDs (HP-LEDs) or high-output LEDs (HO-LEDs) can be driven at currents from hundreds of mA to more than an ampere, compared

with the tens of mA for other LEDs. Some can emit over a thousand lumens.LED power densities up to 300 W/cm2 have been achieved. Since

overheating is destructive, the HP-LEDs must be mounted on a heat sink to allow for heat dissipation. If the heat from an HP-LED is not removed, the

device fails in seconds. One HP-LED can often replace an incandescent bulb in a flashlight, or be set in an array to form a powerful LED lamp.

Flashing LED are used as attention seeking indicators without requiring external electronics.

Flashing LED  resemble standard LED but they contain an integrated and a circuit that causes the LED to flash with a typical period of one second.

In diffused lens LED, this circuit is visible as a small black dot.

Most flashing LED emit light of one color, but more sophisticated devices can flash between multiple colors and even fade through a color sequence

using (RGB) color mixing.

The aluminum base are usually the most common LED PCB. They show effective results and offer high performance.

The conductive link between the Heat Sink and the IC is basically the thermally conductive dielectric layer of the aluminum base. This concept is

unlike FR4.

The aluminum and the copper have enhanced and improved the characteristics of the thermal expansion to a great extent. Even the dimensional

stability of an MPCB is much more than the conventional insulating material, FR4.

The great thing about the aluminum base is the versatility it offers.

Since there are different types of aluminum available serving different purposes, thus it is possible to have more specialized LED Printed Circuit

boards.

Andwin Circuits as a industry leading of PCB manufacturer since 2003.

Specializing in multilayer PCB, Rigid flex PCB, HDI PCB, controlled impedance PCB and Radio Frequency circuit, from quick turn prototype to mass products.