Performance

Performance Characteristics
of Multilayer Glass
Dielectric Capacitors
A B S T R A C T :
Glass dielectric capacitors exhibit several key
performance parameters critical to high
performance circuitry. This technical paper is a
summary of specialized tests performed on AVX
glass capacitors to demonstrate their in-circuit
characteristics.
Ron Demcko
AVX Corporation
Raleigh, NC
PERFORMANCE CHARACTERISTICS
OF MULTILAYER GLASS
DIELECTRIC CAPACITORS
by Ron Demcko
AVX Corporation
Raleigh, NC
Introduction
Glass Dielectric Capacitor Construction
AVX Glass dielectric capacitors offer the end user the
highest performance and reliability features available in
the capacitor industry.
The construction of Glass capacitors is straightforward.
There are only three elements: glass dielectric and case,
aluminum electrodes, wire terminals. (Radial capacitors
have a molded case.) The capacitors are made in a
multilayer fashion (as shown below).
Simplicity of construction, combined with the excellent
dielectric characteristics of glass, make AVX Glass
Capacitors outstanding performers.
AXIAL
Simplicity of construction, combined with the excellent
dielectric characteristics of glass, make AVX Glass
Capacitors outstanding performers.
RADIAL
AVX performs a 100% inspection on each capacitor
checking: capacitance value and tolerance, rated voltage,
and hermetic seal (axials). The combination of tight quality
control, simplicity of design, and a superior material
system means that AVX Glass capacitors are close to being
the “perfect circuit symbol.”
Here is an overview of AVX Glass capacitor features:
High Stability
– Low Retraceable Temperature
Coefficient (TC)
No Hysteresis
Zero Aging Rate
Zero Piezoelectric Noise
Extremely Low
– Stable Q Factor at High Frequencies
Losses
Low Dielectric Absorption
Large RF Current Capability
Nuclear Radiation Hardness (Axials)
High Operating Temperature Range (Up to 200°C)
High Shock/Vibration Capability
Excellent High Vacuum Performance
Glass Capacitor Applications
Glass capacitors have traditionally seen widespread
usage in military applications with a large number of new
designs occurring in the aerospace and high performance
commercial sectors. Glass capacitors have applications
across the entire spectrum of electronic circuits and their
past success on a variety of manned and unmanned space
missions continues to fuel interest of the defense and
aerospace industries.
The following is a list of general applications where
Glass capacitors are currently utilized:
Ramp Integrators
Radiation Hardened Circuitry
Voltage Snubbers
Burn in Oven Circuitry +200°C
Transistor Biasing
High Temperature Circuitry
Low Temperature Circuitry
Galvanometers
(-150°C)
Radar Systems
Bridge Reference Capacitors
Modulators
Temperature Sensing Circuitry
Gyro Systems
Jet Engine Monitors
R.F. Amplifiers Output Filters
Low Noise Receiver Front Ends Dosimeters
Space Defense/Satellites
Variable Frequency Oscillators
Geophysical Sensors
Voltage Controlled Oscillators
Amplifier Coupling
Porcelain Capacitor Replacements
Impedance Transformation
Medical Monitoring Circuitry
Networks
Missile Systems and Avionic
PLL Circuitry
Circuitry
Sample and Hold Capacitor
Application assistance on any specific circuitry is
available from the Raleigh, NC applications hotline: (919)
878-6224.
Glass Capacitor Electrical
Characteristics
Capacitance Stability
Glass capacitors exhibit excellent stability characteristics
as a result of their unique material system.
The temperature coefficient for Glass capacitors (stated
in linear approximation form) is 140±25ppm/°C. However,
the actual temperature coefficient is shown below (see
Figure 1). Furthermore, the temperature coefficient of all
Glass capacitors will retrace to within ±5ppm/°C of the TC
curve without exhibiting hysteresis. The capacitance change
vs. temperature of Glass capacitors is shown in Figure 2.
Loss Characteristics
AVX Glass capacitors exhibit low loss over a wide
operating temperature and frequency range. The following
graphs describe loss characteristics as a function of
temperature, capacitance value/form factor, and frequency.
Dissipation Factor vs. Temperature
Radial
Figure 1
Figure 3
Figure 2
Long Term Stability
Numerous five year “drift tests” were conducted on
standard CY Glass capacitors which indicate Glass
capacitors have zero aging rate. The components under test
were read for capacitance immediately after production.
They were then stored under normal room conditions and
reread for capacitance value five years later. The maximum
positive drift was 0.07% of initial capacitance value and the
maximum negative drift was 0.09%.
Long term stability investigations were also performed
under load life test conditions. The results of one such test
are as follows:
Table I
Long Term Load Life Data
Style
No. Hours
on Test
No. of
Pieces
CY10
CY15
39,558
47,597
10
10
Value and
Tolerance
(pF)
120±10%
430±10%
Max. Cap.
Change %
Max.
DF %
Min.
IR
Min.
Q
.58
.63
.058
.042
1013
1013
1691
2534
All Glass capacitors exhibit zero piezoelectric noise and
have zero voltage coefficient regardless of age or style.
Quality Factor vs. Capacitance
Axial
Figure 4
Quality Factor vs. Capacitance
Radial
Figure 5
Capacitance vs. Frequency
Axial
Figure 6
Capacitance vs. Frequency
Radial
Figure 9
Quality Factor and Dissipation Factor vs. Frequency
Radial
Figure 7
Quality Factor and Dissipation Factor vs. Frequency
Axial
Figure 10
Resonant Frequency vs. Capacitance
Radial
Figure 8
Resonant Frequency vs. Capacitance
Axial
Figure 11
Dielectric Absorption
Glass dielectric capacitors have been tested for Dielectric
Absorption (DA) characteristics per Military Specification
MIL-C-19978 and have shown a consistently low Dielectric
Absorption from lot to lot (0.012% is typical). In addition to
DA figures which are comparable to polystyrene, glass
capacitors exhibit zero aging rate, zero piezoelectric noise,
and a ±5ppm TC retraceability regardless of component
age. Furthermore, glass capacitors exhibit zero voltage
coefficient and low thermal and charge noise figures.
Glass capacitors continue to experience widespread
usage in sample and hold current integrators, and in high
gain amplifiers as a result of these performance features.
AVX Glass Capacitors –
RF Current Applications
AVX Glass dielectric capacitors can handle large Radio
Frequency (RF) currents over a wide frequency range.
(See following graphs.)
Glass dielectric capacitors have a high Q factor and a low
dissipation factor that changes little with frequency and
temperature excursions. This coupled with a low,
retraceable, extended range temperature coefficient
ensures repeatable, reliable performance – regardless of
the capacitor’s environment.
The large RF currents that glass dielectric capacitors
can handle make them ideal for use in modulators, filters,
and linear amplifiers.
Figure 14
Nuclear Radiation Hardness
AVX axial Glass capacitors are made of inorganic
materials and are highly resistant to nuclear radiation,
voltage breakdown, and high operating temperatures.
When exposed to a neutron radiation field of 1015 fast
N/CM2 SEC, AVX Glass capacitors were shown to have a
transient capacitance increase of between 0.7 to 2.5 percent,
while exhibiting a permanent capacitance increase of less
than 0.5 percent. AVX Glass capacitors can operate in
neutron flux environments 10 to 100 times more intense
than other capacitor technologies and experience only
minor damage. Furthermore Glass capacitors will not
become a toxic hazard when exposed to radiation.
A summary of various capacitor technologies’ performance
under a neutron radiation field is shown below.
Figure 12
Figure 15
Capacitors ability to operate in neutron
field intensity (Flux/cm-2)
Figure 13
When exposed to gamma irradiation, Glass capacitors
exhibit an extremely small transient and permanent
capacitance change and a consistently low dissipation factor
with frequency.
The capacitors under test were uniformly exposed to a
total dose of 9.6 x 107 rads (H2O) and measured for
capacitance value and dissipation factor across a frequency
range of 100Hz to 100kHz before irradiation, immediately
after irradiation, 2 hours after irradiation, and 96 hours
after irradiation. Results of such testing are as follows:
ET Features •“Burned in” versions
•Short term (≤1 hour) exposure
con’t.
available – 50 hours, 1500 vdc, to 250°C no performance
25°C
degradation
•Voltage coefficient = 0
•High Voltage Pulse
•Working temperature range - withstanding capability
75°C to +200°C
•Low Noise – excellent choice
with GaAs circuitry
Typical
•Semiconductor Burn-in Ovens
Applications •Oil Well Logging and
Down Hole Instrumentation
•Geophysical Pressure Probes
•Remote Antenna
Low Noise Amplifiers (LNAs)
• Radio Frequency (RFD)
Output Circuitry
Standard
•Working Temperature Range. . .-75°C to +200°C, Short Term
Operating
(≤1 hours) exposure to 250°C with no degradation in
Characterisperformance
tics of AVX
•Voltage Rating. . . 50 vdc
ET Capacitors
•Capacitance Range. . .0.5pF to 2400pF
•Insulation Resistance. . .at 25°C>100,000 megohms
at 200°C>1 x 108 ohms
•Dissipation Factor. . .at 25°C<.1% at 1kHz
at 200°C<1% at 1kHz
•Life. . .(200°C, 1000 hour life at rated voltage)
•Post Life Test. . .Delta C at 25°C<2%
DF at 25°C<2.5%
IR> x 108 ohms (Axials)
IR> x 107 ohms (Radials)
Figure 16
Figure 17
Elevated Temperature (+200°C)
Performance
Temperature extremes are the enemy of reliable and
long term circuit performance. Elevated Temperature
(ET) series of Glass capacitors are designed to meet
these requirements.
After years of research, this wide range capability was
achieved by matching and optimizing thermal expansion
rates of the materials in Glass capacitor manufacture.
AVX ET series capacitors also provide the same highly
reliable characteristics as other AVX Glass capacitors such
as nuclear radiation stability, outstanding capacitance
retraceability, and rugged, yet simple, construction that
eliminates mechanical problems.
ET Features •Available in both Axial and
Radial Configurations
•Radiation Hardened (Axials)
•Missile and Aerospace
Transducers
•Super Cooled High
Speed Logic
•Cold Low Noise Radar
Circuitry
•Aerospace Solar Array-Systems
•Cryogenic Sensors
Figure 18
•Values from 0.5pF to 2400pF
•Rugged design and
construction
Figure 19
ET, ETR Series: Elevated Temperature (ETR High
Reliability) series. Capable of operation over -75°C to
+200°C with short overexposure to +250°C (≤1 hour).
Available in 2 case sizes; .5pF to 1200pF; 50 VDC rated
across operating temperature range; hermetically sealed;
ETR series burned-in at 1500 VDC, 50 hours, 25°C.
Glass Radial: CY, CYR, ET & ETR Series
CY Series: Qualified to MIL-C-11272; available in 3 case
sizes, 1pF to 2400pF; 300 VDC rated.
CYR Series: Qualified to MIL-PRF-23269; Failure Rate
Level M; available in 3 case sizes; 1pF to 2400pF.
ET, ETR Series: Elevated Temperature (ETR High
Reliability) series capable of operation over -75°C to
+200°C. Available in 3 case sizes; 1pF to 2400pF; 50 VDC
rated across operating temperature range. ETR series
burned-in at 1500 VDC, 50 hours, 25°C.
Figure 20
Product Options/Series
Glass Axial: CY, CYR, CYFR, ET & ETR Series
CY Series: Qualified to MIL-C-11272. Available in 2 case
sizes; .5pF to 1200pF; 500 VDC, 300 VDC rated,
hermetically sealed.
CYR Series: Qualified to MIL-PRF-23269. Failure Rate
Levels M and S: available in 2 case sizes; .5pF to 1200pF;
500 VDC, 300 VDC rated; 100 VDC (S level only);
hermetically sealed.
CYFR Series: Meets or exceeds all requirements of AVX
specifications J-950, J-951 (modeled after Minuteman high
reliability specification); available in 2 case sizes; .5pF to
1200pF; 500 VDC, 300 VDC rated. Insulation resistance
greater than 500,000 megohms at 25°C, greater than 10,000
megohms at 125°C; hermetically sealed.
Figure 22
Figure 21
Table II: Capacitance Range/Case Sizes
Axial: CY, CYR, CYFR, ET & ETR Series
Case
Size
Capacitance
Range
L
W
T
10
.5pF to 300pF
15
220pF to 1200pF
.344 ± .047
(8.74 ± 1.19)
.469 ± .047
(11.91 ± 1.19)
.172 ± .031
(4.37 ± .79)
.266 ± .031
(6.76 ± .79)
.078 ± .031
(4.37 ± .79)
.109 ± .047
(2.77 ± 1.19)
Dimensions: Inches (Millimeters)
Lead Diameter
+.004 (+0.1)
-.001 (-0.03)
.020
(.51)
.020
(.51)
Weight
(Grams)
.25 - .50
.75 - 1.25
Table IV: Capacitance Range/Case Sizes
Radial: CY, CYR, ET & ETR Series
Case
Size
Capacitance
Range
06/51
1pF to 560pF
07/52
620pF to 1000pF
08/53
1100pF to 2400pF
Dimensions: Inches (Millimeters)
L
±.005
(±.13)
.300
(7.62)
.300
(7.62)
.500
(12.70)
W
±.010
(±.25)
.200
(5.08)
.300
(7.62)
.300
(7.62)
T
±.005
(±.13)
.115
(2.92)
.115
(2.92)
.115
(2.92)
Lead Diameter
±.002
(±.051)
.020
(.51)
.020
(.51)
.020
(.51)
S
±.020
(±.51)
.200
(5.08)
.200
(5.08)
.400
(10.16)
Weight
(Grams)
.3 - .4
.4 - .5
.7 - .8
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