The
ceramic capacitor consists of a ceramic
dielectric with
metalized
sufaces. These
acts as
electrodes. To get a higher
capacitance
a multilayer buildup is often used.
Example of a multilayer capacitor
____ ____
|********************|
|-------------------*|
|********************|
|*-------------------|
|********************|
|-------------------*|
|********************|
|*-------------------|
|********************|
Legend:
- electrode
* ceramic dielectrum
This buildup is often used in
surface mount capacitors.
The ceramics are divided in to three
classes:
Class 1 has a low dielectric
constant but a high
temperature,
frequency and
voltage stabillity.
Class 1 capacitors are
available with values from
0.5pF to around 500pF. This type of ceramic is good for
high
frequency applications
Class 2 ceramics have a lower stability but a higher
dielectric constant. Available
values range between
100pF and 10uF. These capacitors are used in circiuts
were a high stabillity is not
important.
Class 3 ceramics consists of a
fused semiconducting
granulate. They have similar characteristics as the
class 2 ceramic, but lower
voltage tolerance. They
are however smaller and cheaper to produce. Values between
1000pF and 1uF is commonly available.