BY OLAF KURTZ, JÜRGEN BARTHELMES,
ROBERT RÜTHER AND
JOKO SETYADI-LIE ATOTECH
Silver coatings of highest
refectivity for LED applications.
Bright Future
for Plating
LED Lights
18
SEPTEMBER 2015 — pfonline.com
ELECTRONICS E L E C T R O N I C S
Most industrial nations have gradually removed incan-
descent light bulbs from the market due to their inad-
equate performance and high consumption of electricity.
In 2008, the European Union began the process, and
in 2012, the last incandescent bulb was sold and the rest
removed from the shelves the following day—marking the
end of a technology era that had caused a revolution when
it was introduced about 130 years ago.
The U.S. Congress passed a law in 2007 to begin phasing
out the old familiar tungsten-filament 40- and 60-watt
incandescent light bulbs by the beginning of 2014.
Light emitting diode (LED) technology provides an efficient
alternative to standard bulb technologies. The efficiency
of each lamp type can be expressed as "luminous efficacy,"
defined as the ratio of the luminous flux emitted from the lamp
per electrical power required by the lamp.
Efficacy is specified in lumen [lm] per watt [W
-1
] and is typi-
cally 15 lm/W for conventional light bulbs, increasing to 30 lm/W
for halogen, while as high as 150 lm/W for an LED. This high
efficiency, combined with extended longevity, explains why LED
technology has high market attraction with excellent growth and
application potential.
A low free-cyanide silver process, containing innovative bright-
ener additives, enables the highest luminous reflectance and perfor-
mance of the LED.
Highly Reflective Coatings
Nowadays, LEDs are widely used in the electronics and automotive
industries, together with household and road lighting applications.
Silver plating of the LED substrate can be carried out via conven-
tional rack or reel-to-reel plating procedures. The current density
range used can vary considerably, typically 20 to 150 A/dm
2
, depen-
dent on whether the surface is fully or partially (spot) plated.