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Be Safe Wherever You Go
01
Extreme cold to searing heat, incessant exposure to strong vibrations and shocks, and many other adverse factors―electronic
components in cars are subject to extremely harsh conditions and therefore need to provide much higher reliability than general use
products. Making full use of its rich store of advanced core technologies such as materials technology, layering technology, and
sintering technology, TDK is offering a wide range of highly reliable multilayer ceramic chip capacitors for automotive use. These
are grouped into various product series, such as high temperature resistance types suitable for use near the engine (X8R), C0G
characteristics types, mid voltage types with high capacitance, Mega Cap types with excellent thermal stress resistance etc. All of
these products are designed to make a significant contribution to safe and pleasant driving.
Core Technologies Create High Reliability
High Reliability Automotive Use
Multilayer Ceramic Chip Capacitors
Dielectric Relative dielectricconstant
Various plastic films 2〜3
Mica 6〜8
Aluminum oxide 8〜10
Ceramics(low relative dielectric constant type) 10〜100
Ceramics (high relative dielectric constant type) 1000〜20000
Air 1
Higher relative dielectric constant = larger capacitanceSmaller electrode gap distance = larger capacitance
Larger electrode surface area = larger capacitance
Electrode
Electrode
Dielectric
Electrode surface area S
Electrode gap distance d
Capacitance C= Sε0εr d
1 1V 10V 100V 1000V 10000V10 100 1 10 100 10 100 1 10 100 1pF nF
1µF mF F
Multilayer Ceramic Chip Capacitors
Aluminum Electrolytic Capacitors
Tantalum Electrolytic Capacitors
Film CapacitorsFilm Capacitors
Tantalum Electrolytic Capacitors
Aluminum Electrolytic Capacitors
Multilayer Ceramic Chip Capacitors
□Various dielectrics and their relative dielectric constant
□Basic capacitor construction and capacitance
□Capacitance ranges of various capacitor types □Rated voltage range of various capacitors
ε0:Dielectric constant in vacuum
(8.854×10-12F/m)
εr :Relative dielectric constant in a material
High Reliability Automotive Use Multilayer Ceramic Chip Capacitors
02
A capacitor has the function of condensing and storing
an electrical charge, which is why it used to be called a
condenser. The measure of how much charge it stores is called
capacitance, from which the current name is derived. The
magnitude of the capacitance is determined by the surface area
(S) of the opposing electrode plates, the narrowness (d) of the
gap between the electrodes, and the relative dielectric constant
(εr) of the dielectric (insulator) between the electrodes.
Multilayer ceramic chip capacitors used frequently in modern
electronic devices have multiple layers of electrodes and
dielectric sandwiched within the capacitor housing to enlarge
the electrode area. This type of capacitor was developed for
practical use in the middle of the 20th century, but the concept
of a simple condenser with layered electrodes and dielectric
existed already in the middle of the 19th century. Because thinly
sliced mica was used as dielectric, the condenser was called
a mica condenser. While the relative dielectric constant of air
is about 1, mica has a rating of between 6 and 8, which means
that high capacitance can be achieved with this material.
The relative dielectric constant of the various types of plastic
film used for film capacitors is 2 to 3, while that of aluminum
oxide film used as dielectric in aluminum electrolytic capacitors
is on the order of 8 to 10. The relative dielectric constant of
ceramic dielectric is about 10 to 100 at the lower end, and
as much as 1000 to 20000 at the higher end. Consequently,
multilayer ceramic chip capacitors can provide very high
capacitance even in products with small dimensions, which is
the major reason for their great popularity.
The capacitance is only one of the many characteristics of
a capacitor. Other aspects that are of importance include
temperature characteristics, rated voltage, frequency response
and many more. Depending on the application, different types
of capacitors are required, and each type has its advantages
and disadvantages. For example, aluminum electrolytic
capacitors provide very high capacitance values, but their high
frequency response characteristics are not very good and they
also have a relatively short service life.
The capacitor type with the best overall balance of rated
voltage, frequency response, service life etc. is the multilayer
ceramic chip capacitor. Because it can be manufactured as a
chip component, it offers excellent performance at reasonable
cost, and the progress of thin layer and multi layer technology
has brought its capacitance within the realm of electrolytic
capacitors.
Multilayer Ceramic Capacitors Provide a Great Balance of Characteristics
□Temperature characteristics □DC bias characteristics
Temperature(℃) ( )
( )
( )
□Ambient temperatures in a car
150 °C rated X8R compliant multilayer ceramic chip capacitors can be used in electronic devices installed in high-temperature environments such as in the vicinity of the engine and near the engine surface.
Passenger compartment (85℃)
Engine surface(150℃)
Engine compartment(125℃~150℃)
Trunk interior(85℃)
High Reliability Automotive Use Multilayer Ceramic Chip Capacitors
03
Multilayer ceramic chip capacitors can be largely divided into two
categories, namely low relative dielectric constant types using
CaZrO3 (calcium zirconate) or similar as dielectric (Class I), and high
relative dielectric constant types using barium titanate (BaTiO3) or
similar as dielectric (Class II). To obtain high capacitance, the high
relative dielectric constant type is best, but this type has an important
drawback, namely the fact that capacitance changes depending on
the temperature. By contrast, the low relative dielectric constant type
shows little capacitance variation depending on temperature. It is
therefore used extensively in applications such as filter circuits and
oscillators, where stable characteristics are important. These products
are therefore also referred to as temperature compensating capacitors.
The fact that electronic devices for use in automobiles are subject
to extreme environment conditions is a major difference to general
electronic devices. As automobiles get more and more electronic, the
number of ECU (Electronic Control Unit) devices in a single car can
be between 10 and 100, resulting in a large number of wire harnesses
criss-crossing the vehicle. Because the weight of these harnesses
can reach several dozen kilograms, there is a tendency to position the
ECUs in the engine room, thereby reducing the length of the harnesses
and the related weight. However, the temperature in the engine room
reaches about 125 °C, and as much as 150 °C on the engine surface.
Electronic components for automotive use therefore must be able
to withstand very high temperatures and be able to maintain stable
operation over a wide temperature range. X7R and X8R type multilayer
ceramic chip capacitors (high relative dielectric constant) fulfill these
requirements.
X7R specifications prescribe a temperature range of -55 to +125
°C with a capacitance tolerance of maximum ±15%. For X8R, the
temperature range is -55 to +150 °C and the tolerance also ±15%
(EIA standard). With high relative dielectric constant type capacitors
described above, meeting these requirements is difficult, but to realize
X8R specifications is an important challenge with a view to the further
progress of car electronics. By improving material composition and
manufacturing conditions, TDK was able to optimize the particle
structure of the dielectric ceramics and achieve a more uniform
particle size. Following in the footsteps of 125 °C rated X7R compliant
products, the company succeeded in bringing 150 °C X8R compliant
multilayer ceramic chip capacitors to the market. The availability of
X8R products meets the advanced needs of the market and means
that temperature-related limitations to ECU placement are eliminated.
Performance and reliability of the engine control unit, sensor modules,
HID, ABS and other automotive devices will benefit from this
development.
X8R Characteristics Can Withstand Even Engine Surface Temperatures of 150 °C
□Development of new dielectric realizes smaller dimensions and higher capacitance for C0G type/ mid voltage capacitors
Composition structure of conventional material Composition structure of new dielectric material
Average particle size:0.25µm Shell
(low dielectric range)Core(high dielectric range)
Grain boundary
Further size reduction and higher capacitance
Enlarged shell and reduced ferroelectricity of core result in low distortion and reduced capacitance drop in strong magnetic fields.
Service life improvement by a factor of 50 at identical dielectric layer spacing allows thinner layers and higher capacitance.
High Reliability Automotive Use Multilayer Ceramic Chip Capacitors
04
The smaller the distance between the electrodes of a capacitor,
the higher its capacitance. Consequently, using a dielectric
with high relative dielectric constant and making the dielectric
layers of a multilayer ceramic chip capacitor thinner also would
result in higher capacitance, but under real world conditions
effective capacitance may decrease and service life may be
shortened. Through measures such as reviewing the material
composition, making dielectric particles smaller, and optimizing
the particle core (high dielectric range) - shell (low dielectric
range) structure, TDK is implementing advanced materials and
particle design approach which allows about 30 percent thinner
layers as compared to conventional products. The new dielectric
has enabled a new product series with C0G characteristics and
rated voltage of 50 V. The thinner layers result in a capacitance
improvement by a factor of about 3 over conventional types.
This also means that at the same capacitance rating, the new
capacitors can be made significantly smaller.
Mid voltage type capacitors used for example in the power
supply smoothing circuitry of automotive equipment also require
high reliability dielectric layers and a dielectric with excellent
DC bias characteristics, in order to allow for high capacitance.
By enlarging the dielectric particle shell and controlling the
ferroelectric behavior of the core, TDK has realized low distortion
and reduced the capacitance drop in strong magnetic fields.
Use of the new dielectric also has enabled a significantly longer
service life for X7S and X7T capacitors with mid voltage rating
(100 V to 630 V). While maintaining the voltage resistance rating,
thinner layers and consequently higher capacitance have become
possible.
The X7S specifications prescribe a temperature range of -55 to
125 °C and a capacitance tolerance of ±22%, while X7T covers
the same temperature range at a tolerance requirement of +22%,
-33%. This is lower than X7R which has a capacitance tolerance
range of ±15%. But the TDK X7S and X7T products using the
new dielectric exhibit the same excellent performance as X7R
products in an actual operation environment with voltage applied.
New Dielectrics Increase Capacitance of C0G Type and Mid Voltage Type Products
□Internal construction of CEU series multilayer ceramic chip capacitors
Tin (Sn) plating
External electrode
Nickel (Ni) plating
Copper (Cu) base
Conductive plastic layer
Crack
Conductive plastic electrode layer absorbs external stress and protects the ceramic element.
Serial structure of internal electrodes prevents insulation breakdown in case of cracks.
Internal electrode serial structure
High Reliability Automotive Use Multilayer Ceramic Chip Capacitors
05
A multilayer ceramic chip capacitor incorporates multiple
dielectric and internal electrode layers in a sandwiched
configuration. Because this is an equivalent circuit to a parallel
connection of multiple capacitors, insulation breakdown in
even just one capacitor will result in short-circuiting. But if two
multilayer ceramic chip capacitors are connected in series,
insulation breakdown in one capacitor will not cause a short-
circuit of the entire arrangement. The CEU series is based on
this principle. It features an internal electrode structure that is
the equivalent of a serial connection of two capacitors.
An important feature of the CEU series is dual fail-safe design.
The external electrodes use a conductive plastic layer to absorb
and soften bending stress of the PCB, thereby preventing
the occurrence of cracks. In addition, the internal electrode
structure employs a serial connection of two capacitors. If
a crack should develop in one capacitor element and cause
breakdown short-circuiting, insulation breakdown is avoided by
the second capacitor.
This dual fail-safe design of the CEU series is optimal for the
power supply lines of automotive equipment, where safety is a
foremost concern. The design also helps to save space on the
circuit board because two capacitors are located in the space
of one.
Dual Fail-Safe Design Ensures High Reliability: CEU Series
□Construction principle of a Mega Cap (dual stacked type)
□Reduction of stress caused by thermal expansion of aluminum board
□Thermal stress test comparison
High-temperature
solder
Metal capTin (Sn) plating
Stress load is concentrated onelectrode section
Use of metal cap reducesstress load on capacitor
Nickel (Ni) plating
Copper (Cu) base
StressHigher
Lower
Initial period After 1,000 cycles After 3,000 cycles
《Board bending simulation (2 mm)》
C3225
Solder
Joint betweenterminal electrode and
solder
Metal cap
Solder crack develops after 1,000 cycles
Metal cap relieves stress
General use type
CKG32K
Mega Cap
High Reliability Automotive Use Multilayer Ceramic Chip Capacitors
06
The power supplies of automotive equipment frequently use
metal circuit boards made of aluminum or similar, in order
to enhance heat dissipation. However, due to the drastic
temperature changes in an automobile, the aluminum board
tends to shrink and expand, which causes large stresses on the
multilayer ceramic chip capacitors and can lead to cracks in
the solder joints and the capacitor element.
For example, a temperature change from -55 °C to +125 °C will
cause an expansion of 7 μm in the mounting surface of a size
1608 (1.6 x 0.8 mm) multilayer ceramic chip capacitor. For a
size 4532 (4.5 x 3.2 mm) product, the expansion amounts to 20
μm. In addition to the changes in temperature, vibrations and
mechanical shocks also exert a bending stress on the board,
thereby increasing the risk of cracks still further. A solution
to this problem is presented by a multilayer ceramic chip
capacitor type with metal caps on the external electrodes. TDK
markets such a product under the name "Mega Cap."
The Mega Cap has proven to be highly reliable, developing no
cracks even in a thermal stress test with 3000 cycles. The Mega
Cap is also available in a stacked type with two capacitors and
a metal cap. This allows a reduction in footprint requirements
for circuits where two capacitors of the same rating are used in
parallel.
When an AC current is applied to a conventional multilayer
ceramic chip capacitor soldered to a board, the ceramic
element will expand and contract due to the electrostrictive
effect, which can cause the board to vibrate and be heard as
a sound. This problem of sound emission which is also known
as "singing capacitors" is another area where use of Mega Cap
product can be highly effective.
Mega Cap Type Provides Outstanding Resistance to Thermal Stress and Board Flexing
Sn
Ni
Cu
□TDK capacitors for automotive use
High relative dielectric constant and low relativedielectric constant (temperature compensating)products
Rated voltage 100 to 630 VX7R, X7T, X7S characteristics products etc.
150 ℃ guaranteed X8Rcharacteristics product
Metal cap provides protection fromthermal and mechanical stress
Internal electrode serial connection+ plastic electrode ensures high reliability
Conductive plastic electrode
Base material:Copper (Cu)
Internal electrode:Nickel (Ni)AgPdCu
Developed for lead-free solder use.Conductive plastic layer inserted inexternal electrode.
ESR control type Product using ternarycompound AgPdCuterminal compliantwith conductiveadhesive mounting, etc.
Internal electrode serial structure
Conductive plastic layer
General use type Mid voltage type
High temperature type Mega cap type
CEU series Conductive plastic electrode type
CER series Conductive adhesive mounting compliant electrode type
High Reliability Automotive Use Multilayer Ceramic Chip Capacitors
07
2011.06.01
Modern cars are so reliant on electronics that they sometimes are
described as rolling electronic devices. The number of electronic
components used in them increases year by year. Looking at
multilayer ceramic chip capacitors alone, there are about a
thousand or more, in ECUs and other equipment. TDK is putting
its core technologies to optimum use in this regard. Materials
technology, process technology, evaluation and simulation
technology, production technology, device & module technology
combine to create multilayer ceramic chip capacitors that are tailor-
made for automotive applications. All products are completely free
of RoHS regulated substances such as lead, mercury, cadmium
etc. in order to reduce the burden on the environment. With a
view towards the more widespread acceptance of hybrid electric
vehicles (HEV) and electric vehicles (EV), TDK is further bolstering
its lineup of electronic components for automotive use, to
contribute to safe, reliable, and enjoyable driving.
TDK Multilayer Ceramic Chip Capacitors for Automotive Use