Film Capacitors
With over 50 years of experience manufacturing plastic film capacitors, KEMET also designs and builds
custom equipment for film capacitor production, continuously innovating and improving the production
capability, quality, and efficiency. Because films are exceptionally thin – less than 1µm in some cases
– extreme precision and process control is required to manufacture quality capacitors for demanding
applications.
In the most common type of film capacitor, the electrodes are vacuum deposited, or metallized onto a
roll of precision plastic film. The metallization is not deposited near one edge. Two films, one with the
unmetallized edge on the left and one on the right, are laid on top of each other and wound into a roll.
In many cases, the roll is flattened. Next, several metal layers are sprayed on the ends. These become
the electrodes onto which wires are welded before encapsulation.
Another variation has the two films in a stack of layers much like a multilayer ceramic capacitor. These
can either have leads attached and be encapsulated for through-hole capacitors, or left unencapsulated
for surface mount capacitors. KEMET offers several variations on this basic construction using all the
commonly available plastic films to meet a broad range of application requirements. KEMET commonly
customizes film capacitors for specific applications when a standard part is not available.
electrode
free margin
dielectric
Min. film
thickness
(µm)
Dielectric
constant at
1 kHz, +23°C Nomal/(Extended)
Operating
Temperature (°C)
Dissipation
factor at
1 kHz, +23°C
Insulation time
constant(s) at
+23°C
Dielectric
absorption
%
Dielectric
Material
Temperature coefficient
(ppm/°C)
Abbreviation
-55 to +100
( +125)
Polyester
PET
PEN
0.9
3.3
+400 ( 200)
+200 ( 150)
0.5%
0.4%
25,000
25,000
50,000
100,000
15,000
0.5
1.2
-55 to +125
( +150)
Polyethylene
Naphthalate
1.4
1.2
3.0
0 (-50) -55 to +100
550 ( 50) +100 to +150
0 (+50) +150 to +200
-55 to +125
( +175)
Polyphenylene
Sulfide
3.0
0.05
0.01
N/A
0.06%
0.03%
PPS
PP
-200
-55 to +105
( +125)
Polypropylene
2.4
8.0
2.2
(-100, +50) almost liner
Paper
Impregnated
5.5
+1200 ( 200)
-40 to +115
0.8%
P
Properties of common dielectrics used in film capacitors
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KEMET [ KEMET CORPORATION ]
