CERAMIC HIGH RELIABILITY CAPACITORS
CERAMIC HIGH RELIABILITY PRODUCTS
Ceramic Chips, Radial Molded
KEMET Electronics Corporation has been known for
many years as the leader in the ceramic high relia-
bility products. KEMET produces high reliability
monolithic ceramic capacitors under tightly-con-
trolled manufacturing procedures. These capacitors
achieve “State of the Art” performance by virtue of
careful materials selection, conservative design
rules, motivational training of employees, and
scrupulous inspection of all processes as well as the
finished product. KEMET not only manufactures its
own high reliability ceramic capacitor (GR900),
KEMET also manufactures MIL-PRF-123 product
which is built to the highest military standard in the
industry today.
BASIC REQUIREMENTS FOR KEMET’S
HIGH RELIABILITY
PRODUCTS ARE AS FOLLOWS:
1. Selected Raw Materials:
All raw materials are
selected for characteristics known to produce the
finest quality capacitors exhibiting the best electrical
parameters and physical integrity. Materials trace-
ability is maintained throughout the manufacturing
process.
2. Batch Homogeneity:
Production is under batch
control. Each batch is homogeneous with respect to
materials, design and processing conditions.
3. Clean Room Processing:
All processes sensitive
to particulate contamination take place in a clean
room environment.
4. Special Designs:
Special design considerations
such as dielectric thickness are strictly enforced.
Only COG (BP) and X7R (BX) temperature charac-
teristics are made.
5. Destructive Physical Analysis (DPA, or
Cross-Sectioning):
All batches are sampled using
EIA-469 as a minimum requirement. The samples
remain on file and DPA Reports are shipped with the
capacitors.
6. Ultrasonic Scanning:
Optional 100% screening
may be performed using ultrasonic waves to detect
voids or delaminations. Screened lots must pass a
final sample DPA.
7. Batch Performance Monitoring:
All production
batches are tested to generate electrical characteris-
tics. Batches which show anomalous characteristics
are rejected.
8. Special Customer Requirements:
Many special
requirements such as serialization, DPA samples,
X-Ray plates, and special packaging can be accom-
modated.
9. Document Applicable:
The high reliability prod-
uct is implemented through various internal docu-
ments under revision control. The Manufacturing
Instructions provide detailed descriptions of all oper-
ations and delineate requirements for process con-
trol and product performance at various points in the
process flow. Inspector Operating Documents
describe test procedures and sampling plans for
inspection of raw materials, in-process material and
finished product. Raw material specifications
describe physical and chemical characteristics as
well as the packaging and labeling needed to pre-
serve characteristics and identity. Customer specifi-
cations are internal documents applicable only to
products manufactured and inspected to require-
ments of individual customers; in effect, these docu-
ments translate customer drawings into modifica-
tions of the specified portions of KEMET standard
procedures.
The Quality System in total is controlled by the
KEMET Quality Manual and by various Quality
Operating Documents. All documents, and revisions
thereto, bear specified approval signatures.
DETAILED SPECIFICATION:
Temperature Characteristics
Electrical stability with respect to temperature and
voltage is related inversely to the packaging effi-
ciency (capacitance X voltage in a given case size).
COG (BP) is made from ceramic materials which are
not ferroelectric, yielding superior stability but low
packaging efficiency. X7R (BX) is made from materi-
als which are ferroelectric, such as barium titanate,
yielding a stable and high packaging efficiency.
Aging
If the temperature of a barium titanate dielectric is
lowered after an excursion above its curie point, the
ceramic crystalline structure gradually reverts to the
tetragonal form typical of the low temperature condi-
tions. The reversion requires a considerable length
of time, and its effect in practical capacitors has
become known as “Aging”. The rate of aging is
affected by both the temperature and the applied
voltage experienced by the capacitor. The COG (BP)
formulation is non-ferroelectric and does not exhibit
aging. The X7R (BX) formulation exhibits its own
1
© KEMET Electronics Corporation • P.O. Box 5928 • Greenville, SC 29606 (864) 963-6300 • www.kemet.com
CERAMIC HIGH RELIABILITY CAPACITORS
characteristic aging rate which describes a decrease
in capacitance versus time. The capacitance of the
X7R dielectric decreases approximately 1.0% dur-
ing each decade of hours following a return to tem-
peratures below the curie point. In other words,
capacitance will decrease 1.0% between 1 and 10
hours, another 1.0% between 10 and 100 hours,
another 1.0% between 100 and 1000 hours, etc.
KEMET takes into consideration the aging rate by
designing capacitors to fall within the specified
capacitance tolerance at 1000 hours. Inasmuch as
the aging rate is exponential, very little change in
capacitance will take place after 1000 hours.
Voltage Effects
Ferroelectric materials are also affected by applied
voltage, both alternating and direct. Low values of
voltage produce a slight increase in capacitance and
dissipation factor. Higher voltages cause a decrease
in capacitance. Typically, capacitors with X7R char-
acteristic decrease in capacitance by approximately
10% when rated DC voltage is applied.
A small portion of the decrease in capacitance by
the application of a high DC voltage persists after the
voltage is removed and then disappears gradually.
Customer Testing
Because of temperature and voltage effects, caution
must be used in establishing a testing sequence for
ceramic capacitors. Insulation resistance measure-
ments and tests of dielectric withstanding voltage
both require application of high DC voltage and
cause temporary changes in capacitance. These
tests, therefore, should not be conducted until
capacitance testing is completed. Alternatively, the
capacitors can be “de-aged” at high temperature as
described above. A stabilization time at room ambi-
ent of 24 hours should be used after de-aging.
See F-3101 Catalog for more details.
PERFORMANCE CHARACTERISTICS
General Information
Working Voltage:
COG (BP)
- 50,100 & 200 volts
X7R (BX)
- 50,100 & 200 volts
Temperature Characteristics:
COG (BP):
0± 30 ppm/C from -55°C to +125°C.
(Limits widen below 20 pF.)
X7R (BX):
±15%; from -55°C to +125°C.
Capacitance Tolerance:
COG (BP):
C - ±0.25pF; D - ±0.5pF; F - ±1%;
G-± 2%; J- ±5%; K- ±10%; M- ±20%.
X7R (BX):
J - ±5%; K - ±10%; M - ±20%.
Electrical
Capacitance:
Within specified tolerance when
measured with 1 volt RMS @ 1 kHz (1000pF or less
@ 1 MHz for COG (BP)).
Dissipation Factor:
25°C @ 1 kHz (1000 pF or less at 1 MHz for
COG (BP)).
COG (BP):
0.15% maximum
X7R (BX):
2.5% maximum
Insulation Resistance:
After 2 minutes electrification:
at 25°C and rated voltage:
COG (BP):
l00K megohms or (1000 megohm
X µF), whichever is less.
X7R (BX):
l00K megohms or (1000 megohm
X µF), whichever is less.
at 125°C and rated voltage:
COG (BP):
10K megohms or (100 megohm
X µF), whichever is less.
X7R (BX):
10K megohms or (100 megohm
X µF), whichever is less.
Dielectric Withstanding Voltage:
250% of
rated voltage for 5 seconds with current limited to
50 MA at 25°C.
Aging Rate:
% Delta Cap/Decade Hour, Typical
COG (BP):
0%
X7R (BX):
1.0%
2
© KEMET Electronics Corporation • P.O. Box 5928 • Greenville, SC 29606 (864) 963-6300 • www.kemet.com
RF/Wirelessly
京公网安备 11010802033920号
EEWORLD
