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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 factorselectronic

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


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Dielectric Relative dielectric

constant

Various plastic films 23

Mica 68

Aluminum oxide 810

Ceramics(low relative dielectric constant type) 10100

Ceramics(high relative dielectric constant type)

100020000

Air 1

Higher relative dielectric constant = larger capacitance

Smaller electrode gap distance = larger capacitance

Larger electrode surface area = larger capacitance

Electrode

Electrode

Dielectric

Electrode surface area S

Electrode gap distance d

CapacitanceC= S

0rd

1 1V 10V 100V 1000V 10000V10 100 1 10 100 10 100 1 10 100 1pF nF

1F mF F


Aluminum Electrolytic Capacitors

Tantalum Electrolytic Capacitors

Film Capacitors

Film Capacitors

Tantalum Electrolytic Capacitors

Aluminum Electrolytic Capacitors


Various dielectrics andtheir relative dielectric constantBasic capacitor construction and capacitance

Capacitance ranges of various capacitor types Rated voltage range of various capacitors

0Dielectric constant in vacuum

8.85410-12

F/m

rRelative dielectric constant in a material

High Reliability Automotive Use Multilayer Ceramic Chip Capacitors

02

A capacitor has the function of conde nsing and stor ing

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

(r) 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


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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 suchas in the vicinity of the engine and near the

engine surface.

Passenger compartment

85

Engine surface150

Engine compartment

125150

Trunk interior85


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 (BaTiO 3) 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


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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

0.25m 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.


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


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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


05

A multilayer ceramic chip capaci tor incorporates multip le

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


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Construction principle of a Mega Cap (dual stacked type)

Reduction of stress caused by thermal expansion ofaluminum board

Thermal stress test comparison

High-temperature

solder

Metal cap

Tin (Sn) plating

Stress load is concentrated on

electrode section

Use of metal cap reduces

stress load on capacitor

Nickel (Ni) plating

Copper (Cu) base

Stress

Higher

Lower

Initial period After 1,000 cycles After 3,000 cycles

Board bending simulation (2 mm)

C3225

Solder

Joint between

terminal electrode and

solder

Metal cap

Solder crack

develops

after 1,000

cycles

Metal caprelieves

stress

General use type

CKG32K

Mega Cap


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 m 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

m. 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


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Sn

Ni

Cu

TDK capacitors for automotive use

High relative dielectric constant and low relative

dielectric constant (temperature compensating)

products

Rated voltage 100 to 630 V

X7R, X7T, X7S characteristics products etc.

150 guaranteed X8R

characteristics product

Metal cap provides protection from

thermal 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 in

external electrode.

ESR control type Product using ternary

compound AgPdCu

terminal compliant

with conductive

adhesive 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


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

multi layer 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 l ineup of electronic components for automotive use, to

contribute to safe, reliable, and enjoyable driving.

TDK Multilayer Ceramic Chip Capacitors for Automotive Use

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