High Voltage Ceramics Capacitors, Shocking!!! So you want to ramp up the voltage in your design. Have you considered what type of ceramic capacitor to use? Have you taken steps to prevent surface arcing? KEMET is a leader in high voltage ceramic capacitors providing solutions for commercial, automotive, military, and industrial applications. This webinar will review key considerations when designing in a high voltage ceramic capacitor along with ways to miniaturize your circuit without the fear of arcing.

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High Voltage Ceramic Capacitors
June, 2019

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Agenda
• What is High Voltage
• MLCC Design
• Creepage vs Clearance
• Arcing and KEMET’s ArcShieldTM
• KEMET HV Portfolio

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What is High Voltage?
High Voltage Product Portfolio
10,000V1,000V100V10V1V1V
DC: >250Vdc
AC: ≥250Vac
Ceramics

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MLCCs
C = Design Capacitance
K = Dielectric Constant
A = Overlap Area
d = Ceramic Thickness
n = Number of Electrodes
C = e0KA(n-1)
d
Detailed Cross Section
Inner Electrode
End Termination
Barrier Layer
Termination Finish
Dielectric Material

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What is MLCC Surface Arcing?
Electrical breakdown between the two MLCC terminations or
between one of the terminations and the internal electrodes of
the capacitor within the ceramic body.
Influences
• Humidity
• Surface Contamination
• Creepage Distance

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Creepage vs Clearance
Clearance
Creepage
Creepage – Spacing between conductive elements through an insulating surface
Clearance – Spacing between conductive elements through air

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Creepage vs Clearance
Clearance = Creepage

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The Phenomenon of Surface Arcing
Opposing
Terminations
Alternating layers create opposing
electrodes

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The Phenomenon of Surface Arcing
First Counter
Electrode
Ionization of Air
Electric Field
High field concentration

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The Phenomenon of Surface Arcing
Electric Arc
Inception voltage < Rate Voltage

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Surface Arcing Between MLCC Termination
and the Internal Electrode Structure

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Surface Arcing Failure Modes
Carbon Traces
Voltage Breakdown Failures
Terminal-to-Terminal Arcing Terminal-to-Active Arcing

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Solutions for MLCC Surface Arcing
• Reduce electric field strength
• Reduce ionization of air at MLCC
surface
• Maximizes available capacitance
in a MLCC package size
Surface Coatings Serial Electrode Designs ArcShield Designs
• MLCC Coating
– Added by MLCC supplier
– Additional process step
– Critical that there is no damage to
or air gap under the coating
• PCB Coating
– Added after PCB assembly
– Additional process step
– Added cost
– Cannot rework
• Reduce electric field strength
– Available capacitance in a MLCC package
size is lowered
– Allows for higher voltage capability
– Reduces the probability of MLCC failure due
to flex crack

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The Benefits of Coating Technology
Ionization of Air
Creepage Distance

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Issues With Coating Technologies
Damaged CoatingElectric Arc

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Serial Electrode Design
Reduction of Electric Field
1uF 1000V
0.22uF 5000V
Single MLCC
Five Series MLCCs
Single Monolithic Structure
(Serial Design)
0.22uF 5000V
Electric Field Distributed Across Individual MLCCs
Electric Field Distributed Across Each Serial Design
1000V
1000V 1000V 1000V 1000V 1000V
1000V 1000V 1000V 1000V 1000V
1
𝐶𝑒𝑓𝑓
= ෍
1
𝐶 𝑁

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Serial Electrode Design
Also known as “Serial Electrode” or “Floating Electrode” designs
Capacitive
Area
Capacitive
Area
Separation Between
Series Elements

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“Serial” to “Shield” Design Comparison
“Serial” Design
• With capacitors (N) in series, the
acting voltage on each capacitor is
reduced by the reciprocal of the
number of capacitors (1/N).
• Effective Capacitance is reduced:
“Shield” Design
• Larger electrode area overlap A so
higher capacitance while retaining
high voltage breakdown.
• Thickness d between opposing
electrodes increased:
V/2 V/2
C =
ϵoKNA
d
1
𝐶𝑒𝑓𝑓
= ෍
1
𝐶 𝑁

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KEMET ArcShield Technology
Shield
Electrodes
Shield
Electrodes

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Explanation of Shield Design
Reduction of Electric Field
Terminal-to-Terminal Arcing
Standard Design
Opposite Field extends close to terminal of
opposed polarity so low energy barrier
Terminal-to-Terminal Arcing
ArcShield Design
Opposite Field is longer distance from terminal of
opposed polarity increasing size of energy barrier
+-
E
+-
E

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Explanation of Shield Design
Designed for Higher Voltage
Consider a Standard Design
• In a standard overlap X7R MLCC there are 3 ways of
failing high voltage:
1. Arcing between terminal and 1st electrode of
opposite polarity
2. Arcing between terminals
3. Internal breakdown
Shield designs solve these voltage breakdown
issues by:
a. Adding a shield to prevent 1.
b. The shield also creates a barrier to 2.
c. Thicker actives for higher breakdown 3.
1.
2.
3.
+- a.
b.
c.

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ArcShield Key Features and Benefits
Shield Electrode Technology
Built Inside the MLCC
Patented Electrode Design
• Suppresses an arc-over event while increasing available capacitance
Permanent protection!
• Competitive versions often use a non-permanent surface coating
BME X7R Dielectric
500, 630 and 1,000Vdc
0603 - 2225 Case Sizes
1.0nF – 560nF
Flexible Termination Available
“The World’s Smallest
High Voltage MLCC’s”

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High Voltage Product Portfolio
20,000V10,000V5,000V3,000V2,000V1,000V630V500V
SMD Comm & Auto
SMD Mil Screened
KPS SM Series
KPS
Radial Leaded
Goldmax
HS Series
VRR/VCR Series
Pulse discharge Discharge voltage
SMD Comm
Arc-Shield
KC-LINK

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HIGH VOLTAGE
C900 Safety Disc
Safety SMD
ER Safety Disc
Class and Voltage Ratings:
• X1 400 VAC / Y2 250 VAC
• X1 440 VAC / Y2 300 VAC
• X1 760 VAC / Y1 500 VAC
• X1 400 VAC / Y1 250 VAC
• X1 400 VAC / Y1 400 VAC
Class and Voltage Ratings
• X1 250 VAC / Y2 250 VAC
• X2 250 VAC
• Up to 5 kV Pulse Capable
• Industrial Grade
Case Sizes:
• 1808-2225
Lead Styles:
• Straight
• Outside
• Vertical
Class and Voltage Ratings:
• X1 440 VAC / Y2 250 VAC
• X1 440 VAC / Y2 300 VAC
• X1 760 VAC / Y1 500 VAC
Lead Styles:
• Straight
• Outside
• Vertical
AC, AS, AH ERO, ERK, ERP
KJ Safety Disc
Class and Voltage Ratings:
• X1 440 VAC / Y1 400 VAC
• X1 400 VAC / Y1 250 VAC
Lead Styles:
• Straight
• Outside
• Vertical
KJN, KJY
COMING
SOON

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Creepage vs Clearance
Clearance
Creepage

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Creepage vs Clearance
Clearance
Creepage
Clearance
Creepage

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More Information
Component Edge
https://search.kemet.com/component-edge/#/

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More Information
Component Edge
https://search.kemet.com

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Thank you!
Mark Laps
Technical Product Manager - Ceramics
KEMET Electronics
marklaps@kemet.com