Our Attitude – Always at your service

Dielectric

Characteristics of the plastic film dielectrics

Characteristics of Metallized Film Capacitors in Comparison with Other Dielectrics


PET PP PEN PPS NPO X7R Tantal
Dielectric constant
1 kHz/23°C
3.3 (positive as temperature rise) 2.2 (negative as temperature rise) 3.0 (positive as temperature rise) 3.0 (very constant versus temperature) 12...40 700...2000 26
Operating temperature (°C) -55...+105 (+125) -55...+105 -55...+125 -55...+140 -55...+125 -55...+125 -55...+125
Dielectric absorption (%) 0.2...0,25 0.05...0,10 1.0 0.05 0.6 2.5 n.a.
ΔC/C versus temperature (%) ± 5 ± 2.5 ± 5 ± 1.5 ± 0.3 ± 15 ± 10
ΔC/C versus voltage (%) negligible negligible negligible negligible negligible -20 negligible
ΔC aging rate (%/h decreasing) negligible negligible negligible negligible negligible 2 n.a.
Dissipation factor (%)
1 kHz
10 kHz
100 kHz
0.8
1.5
3.0
0.05
0.08
0.25
0.8
1.5
3.0
0.2
0.25
0.5
0.10
0.10
0.10
2.5
-
-
8
-
-
ESR low very low low very low low moderate high
Ris (MΩ x µF)
25 °C
85 °C
10000
1000
100000
10000
10000
1000
10000
1000
10000
1000
1000
500
100
10
Capacitance range from pF to µF 1000...680 27...400 10000...1.0 10000...2.2 1...0.1 100...2.2 100000...1000
Capacitance tolerance (+/- %) 5/10/20 1/2.5/5/10 5/10/20 2.5/5/10/20 5/10 10/20 10/20
Self-healing yes yes yes yes no no no
Typical failure mode at end of life open open open open short short short
Reliability high high high high high moderate low
Piezoelectric effect no no no no no yes yes
Resistance to thermal and mechanical shock low low low low moderate to high moderate to high low
Polarity no no no no no no yes

Polyester (Polyethylene-terephthalate)

Basic molecule

formelpet

Typical graphs


polyester1 Capacitance change versus temperature
(f = 1 kHz) ( general guide)

polyester3 Insulation resistance change versus temperature
(general guide)

Dissipation factor change versus frequency
(general guide)



Max. working temperature: +125°C
Film thickness: > 0.7 µm
Production process: extruded, biaxially stretched

Manufacturing Process of Polyester Film


Extrusion

faser4
Bi-axial streching

faser5

Crystallisation

tangled, felted
streched
faser3 crystallised (cross-linked, knotted)

Fields of Applications for Polyester Capacitors

  • Decoupling
  • Coupling
  • Blocking

Properties

  • Advantageous price/performance ratio
  • Advantageous capacitance/volume ratio
  • Substitution of low quality electrolytic and tantal capacitors

Polypropylene

Basic molecule



Typical graphs


Capacitance change versus temperature
(f = 1 kHz) (general guide)

Insulation resistange change versus temperature
(general guide)

Disipation factor change versus frequency
(general guide)



Max. working temperature: +105°C
Film thickness: > 4 µm
Production process: extruded, biaxially stretched

Manufacturing process of Polypropylene film


Extrusion

faser4
Bi-axial streching

faser5

Crystallisation

tangled, felted
streched
faser3 crystallised (cross-linked, knotted)

Fields of Applications for Polypropylene Capacitors

  • Sample and hold
  • Oscillator circuits
  • Resonating circuits
  • Deflection systems
  • Power supplies
  • Converters
  • Lighting
  • Audio applications

Properties

  • Lowest dissipation factor
  • Constantly negative TKc
  • Close tolerances up to 1%