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elektroless

Elektroless, also known as electroless, refers to a class of metallurgical coating processes in which metal deposition occurs on a substrate without an external electrical power source. The coating forms by autocatalytic redox reactions in an aqueous bath, where a reducing agent converts metal ions to metal directly on catalytic sites on the substrate.

Common electroless coatings include nickel-phosphorus, nickel-boron, copper, gold, and silver. Nickel-phosphorus is widely used for corrosion

Substrates are prepared and activated to create catalytic sites, then immersed in a bath containing metal ions

Applications include metallizing printed circuit boards, corrosion protection of steel, metallization of polymers and ceramics, and

Advantages include uniform coatings on difficult geometries and low energy use; drawbacks include slower deposition rates,

Electroless deposition was developed in the mid-20th century, with nickel-phosphorus systems becoming commercially important in the

resistance
and
wear,
with
phosphorus
content
influencing
hardness
and
heat
resistance.
Copper
electroless
coating
is
used
to
metallize
nonconductive
substrates
and
as
a
seed
layer
for
electroplating.
and
a
reducing
agent
(for
example,
hypophosphite
for
Ni-P).
The
metal
deposits
autocatalytically
on
active
areas,
yielding
uniform,
conformal
coatings
even
on
complex
geometries.
Bath
pH,
temperature,
and
stabilizers
determine
rate
and
film
quality.
coatings
for
MEMS
and
sensors
that
require
conformal
metal
layers.
strict
bath
control,
potential
toxicity,
and
the
need
for
pretreatment
and
bath
regeneration.
1950s
and
1960s.