TANAKA TECHNOLOGIES

3% Increased Brightness
Key to Raising the Boundaries of High-Brightness LEDs

Manufacturers work around the clock on R&D to improve brightness. The effect is brilliant!

December 2011

LEDs are under the spotlight, but what is this emphasis on brightness?

With power shortages recently becoming a concern, automobile, electronics and machine manufacturers are implementing power-saving initiatives by introducing summertime schedules, working on weekends in summer, installing private electric generators and changing their own and affiliate companies’ light bulbs to LEDs. Low voltage LEDs have now suddenly become the focus of great attention.
The important thing currently for LEDs is to improve brightness, which manufacturers are working on day and night. This page explains what effect improving brightness will achieve.

Reasons for R&D focusing on improving brightness

The basic structure of an LED package is shown in the diagram. Located in the center of the package is the LED chip, which is die-bonded to the substrate. An electrode is formed on the surface of the LED chip and is then connected to the substrate with bonding wire. The LED emits light when electricity is passed through the bonding wire.

A term frequently used these days is High-Brightness LED. Brightness relates to the strength of light emitted when electricity passes to the LED chip, so this brightness is an important characteristic of the LED. Manufacturers are working hard on research and development to achieve even small increases to this brightness.

Bonding wire connects LEDs with the future

Silver Bonding Wire

Silver Bonding Wire

In 2011, the TANAKA Kikinzoku Group company TANAKA Denshi Kogyo discovered and brought to market a material that improved LED brightness. The material was silver alloy bonding wire. This wire has excellent reflective properties near the important 450nm wavelengths, especially for packages using blue LED chips. Mounting the LED chip on the package using this wire is a more efficient way of drawing out the light from the package, achieving 3% better brightness when compared to gold wire (in-house comparison).

Silver wire has a wide range of potential applications in addition to use with LEDs, and it can be used as a substitute for gold wire. Since the price of silver is lower than gold as well, this has the potential to contribute greatly to cost reductions. The TANAKA Kikinzoku Group is constantly developing similar high performance materials using precious metals and other materials.