Circuit Thermal Protection Circuit Protection Multilayer Varistors Certificated Products by industry Organizations Packaging Specifications Packaging Specifications for Automotive Products Catalog (EMC Components/ESD Components) Safety Precautions Safety Precautions for Automotive

Circuit Thermal Protection Circuit Protection Multilayer Varistors Certificated Products by industry Organizations Packaging Specifications Packaging Specifications for Automotive Products Catalog (EMC Components/ESD Components) Safety Precautions Safety Precautions for Automotive
Multilayer Varistors for Automotive
Multilayer Varistors, Chip Type for Automotive
Series: EZJP
Handling Precautions
Safety Precautions
Multilayer Varistors for Automotive (hereafter referred to as “Varistors”) should be used for general purpose applications
as countermeasures against ESD and noise found in vehicle electronics (Engine ECU and various body ECU,
accessory equipment, etc.) equipment. When subjected to severe electrical, environmental, and/or mechanical stress
beyond the specifications, as noted in the Ratings and Specified Conditions section, the Varistors’ performance may be
degraded, or become failure mode, such as short circuit mode and open-circuit mode.
If you use under the condition of short-circuit, heat generation of Varistors will occur by running large current due to
application of voltage. There are possibilities of smoke emission, substrate burn-out, and, in the worst case, fire.
For products which require high safety levels, please carefully consider how a single malfunction can affect your
product. In order to ensure the safety in the case of a single malfunction, please design products with fail-safe, such
as setting up protecting circuits, etc.
● For the following applications and conditions, please contact us for additional specifications, which is not found
in this document.
· When your application may have difficulty complying with the safety or handling precautions specified below.
· High-quality and high-reliability required devices that have possibility of causing hazardous conditions, such
as death or injury (regardless of directly or indirectly), due to failure or malfunction of the product.
1 Aircraft and Aerospace Equipment (artificial satellite, rocket, etc.)
2 Submarine Equipment (submarine repeating equipment, etc.)
3 Transportation Equipment (airplanes, trains, ship, traffic signal controllers, etc.)
4 Power Generation Control Equipment (atomic power, hydroelectric power, thermal power plant control system, etc.)
5 Medical Equipment (life-support equipment, pacemakers, dialysis controllers, etc.)
6 Information Processing Equipment (large scale computer systems, etc.)
7 Electric Heating Appliances, Combustion devices (gas fan heaters, oil fan heaters, etc.)
8 Rotary Motion Equipment
9 Security Systems
J And any similar types of equipment
Strict Observance
1. Confirmation of Rated Performance
The Varistors shall be operated within the specified rating/performance.
Applications exceeding the specifications may cause deteriorated performance and/or breakdown, resulting in
degradation and/or smoking or ignition of products. The following are strictly observed.
(1) The Varistors shall not be operated beyond the specified operating temperature range.
(2) The Varistors shall not be operated in excess of the specified maximum allowable voltage.
(3) The Varistors shall not be operated in the circuits to which surge current and ESD that exceeds the specified
maximum peak current and maximum ESD.
(4) Never use for AC power supply circuits.
2. The Varistors shall not be mounted near flammables.
Operating Conditions and Circuit Design
1. Circuit Design
1.1 Operating Temperature and Storage Temperature
When operating a components-mounted circuit,
please be sure to observe the “Operating
Te m p e r a t u r e R a n g e ” , w r i t t e n i n d e l i v e r y
specifications. Storage temperature of PCB after
mounting Varistors, which is not operated, should be
within the specified “Storage Temperature Range” in
the delivery specifications. Please remember not to
use the product under the condition that exceeds
the specified maximum temperature.
1.2 Operating Voltage
The Varistors shall not be operated in excess of
the “Maximum allowable voltage”. If the Varistors
are operated beyond the specified Maximum
allowable voltage, it may cause short and/or
damage due to thermal run away.
The circuit that continuously applies high
frequency and/or steep pulse voltage please
examines the reliability of the Varistor even if it is
used within a “Maximum allowable voltage”. Also,
it would be safer to check also the safety and
reliability of your circuit.
Design and specifications are each subject to change without notice. Ask factory for the current technical specifications before purchase and/or use.
Should a safety concern arise regarding this product, please be sure to contact us immediately.
00
Apr. 2016
Multilayer Varistors for Automotive
1.3 Self-heating
2.3 Utilization of Solder Resist
The surface temperature of the Varistors shall
be under the specified Maximum Operating
Temperature in the Specifications including the
temperature rise caused by self-heating. Check
the temperature rise of the Varistor in your circuit.
1.4 Environmental Restrictions
The Varistors shall not be operated and/or stored
under the following conditions.
(1) Environmental conditions
(a) Under direct exposure to water or salt water
(b) Under conditions where water can condense
and/or dew can form
(c) Under conditions containing corrosive gases
such as hydrogen sulfide, sulfurous acid,
chlorine and ammonia
(2) Mechanical conditions
The place where vibration or impact that
exceeds specified conditions written in
delivery specification is loaded.
(1) Solder resist shall be utilized to equalize the
amounts of solder on both sides.
(2) Solder resist shall be used to divide the pattern
for the following cases;
· Components are arranged closely.
· The Varistor is mounted near a component
with lead wires.
· The Varistor is placed near a chassis.
See the table below.
Prohibited Applications and Recommended Applications
Item
There is a possibility of performance deterioration
by heat shock (temperature cycles), which causes
cracks, from alumina substrate.
Please confirm that the substrate you use does
not deteriorate the Varistors’ quality.
2.2 Design of Land Pattern
(1) Recommended land dimensions are shown below.
The lead wire of a
Arrangement near
chassis
Chassis
Solder
(ground solder)
Solder resist
Solder resist
Electrode pattern
Retro-fitting of
component with
lead wires
Use the proper amount of solder in order to
prevent cracking. Using too much solder places
excessive stress on the Varistors.
Lateral
arrangement
Recommended Land Dimensions
Improved applications
by pattern division
Mixed mounting Component With lead wires
with a component
with lead wires
2. Design of Printed Circuit Board
2.1 Selection of Printed Circuit Boards
Prohibited
applications
A lead wire of
Retrofitted
Soldering component
iron
Portion to be
Excessively soldered
Land
Solder resist
Solder resist
SMD
Land
c
2.4 Component Layout
b
a
Solder resist
Unit (mm)
Size
Code
0(0402)
Component dimensions
L
W
T
1.0
0.5
0.5
a
b
c
To prevent the crack of Varistors, place it on the
position that could not easily be affected by the
bending stress of substrate while going through
procedures after mounting or handling.
(1) To minimize mechanical stress caused by the
warp or bending of a PC board, please follow
the recommended Varistors’ layout below.
0.4 to 0.5 0.4 to 0.5 0.4 to 0.5
(2) The land size shall be designed to have equal
space, on both right and left side. If the amount
of solder on the right land is different from that
of the left land, the component may be cracked
by stress since the side with a larger amount of
solder solidifies later during cooling.
Prohibited layout
Recommended layout
Layout the Varistors sideways
against the stressing direction.
Recommended Amount of Solder
(a) Excessive amount (b) Proper amount
(c) Insufficient amount
Design and specifications are each subject to change without notice. Ask factory for the current technical specifications before purchase and/or use.
Should a safety concern arise regarding this product, please be sure to contact us immediately.
00
Apr. 2016
Multilayer Varistors for Automotive
(2) The following layout is for your reference since
mechanical stress near the dividing/breaking
position of a PC board varies depending on
the mounting position of the Varistors.
E
D
Perforation
C
A
(4) The heat-curing methods for adhesive are
ultraviolet radiation, far-infrared radiation, and so
on. In order to prevent the terminal electrodes of
the Varistors from oxidizing, the curing shall be
under the following conditions:
160 °C max., for 2 minutes max.
(5) Insufficient curing may cause the Varistors to fall
off after or during soldering. In addition, insulation
resistance between terminal electrodes may
deteriorate due to moisture absorption. In
order to prevent these problems, please
observe proper curing conditions.
B
Slit
Magnitude of stress A>B=C>D>E
(3) The magnitude of mechanical stress applied
to the Varistors when dividing the circuit board
in descending order is as follows: push back
< slit < V-groove < perforation. Also take into
account the layout of the Varistors and the
dividing/breaking method.
2.5 Mounting Density and Spaces
Intervals between components should not be too
narrow to prevent the influence from solder bridges
and solder balls. The space between components
should be carefully determined.
Precautions for Assembly
1. Storage
(1) The Varistors shall be stored between 5 to
40 °C and 20 to 70 % RH, not under severe
conditions of high temperature and humidity.
(2) If stored in a place where humidity, dust, or
corrosive gasses (hydrogen sulfide, sulfurous
acid, hydrogen chloride and ammonia, etc.) are
contained, the solderability of terminals electrodes
will be deteriorated.
In addition, storage in a place where the heat
or direct sunlight exposure occurs will causes
mounting problems due to deformation of tapes
and reels and components and taping/reels
sticking together.
(3) Do not store components longer than 6 months.
Check the solderability of products that have
been stored for more than 6 months before use.
3. Chip Mounting Consideration
(1) When mounting the Varistors components on a
PC board, the Varistor bodies shall be free from
excessive impact loads such as mechanical
impact or stress due to the positioning, pushing
force and displacement of vacuum nozzles
during mounting.
(2) Maintenance and inspection of the Chip Mounter
must be performed regularly.
(3) If the bottom dead center of the vacuum nozzle
is too low, the Varistor will crack from excessive
force during mounting.
Pease refer to the following precautions and
recommendations.
(a) Set and adjust the bottom dead center of
the vacuum nozzles to the upper surface of
the PC board after correcting the warp of
the PC board.
(b) Set the pushing force of the vacuum nozzle
during mounting to 1 to 3 N in static load.
(c) For double surface mounting, apply a
supporting pin on the rear surface of the
PC board to suppress the bending of the
PC board in order to minimize the impact of
the vacuum nozzles. Typical examples are
shown in the table below.
(d) Adjust the vacuum nozzles so that their
bottom dead center during mounting is not
too low.
Item
Single surface
mounting
Prohibited mounting Recommended mounting
Crack
The supporting pin does not necessarily
have to be positioned beneath the
Varistor.
Supporting
pin
2. Adhesives for Mounting
(1) The amount and viscosity of an adhesive for
mounting shall be such that the adhesive will
not flow off on the land during its curing.
(2) If the amount of adhesive is insufficient for
mounting, the Varistors may fall off after or
during soldering.
(3) L o w - v i s c o s i t y o f t h e a d h e s i v e c a u s e s
displacement of Varistors.
Double surface
mounting
Separation of solder
Crack
Supporting
Design and specifications are each subject to change without notice. Ask factory for the current technical specifications before purchase and/or use.
Should a safety concern arise regarding this product, please be sure to contact us immediately.
00
Apr. 2016
Multilayer Varistors for Automotive
△T
Gradual cooling
(at ordinary mperature)
0
Time
60 to 120 sec 3 to 5 sec
For products specified in individual specifications,
avoid flow soldering.
5.2 Reflow Soldering
The reflow soldering temperature conditions are
composed of temperature curves of Preheating,
Temp. rise, Heating, Peak and Gradual cooling.
Large temperature difference inside the Varistors
caused by rapid heat application to the Varistors
may lead to excessive thermal stresses, contributing
to the thermal cracks. The Preheating temperature
requires controlling with great care so that
tombstone phenomenon may be prevented.
Soldering flux may seriously affect the performance
of the Varistors. Please confirm enough whether the
soldering flux have an influence on performance of the
Varistors or not, before using.
5. Soldering
5.1 Flow Soldering
Item
1 Preheating
2 Temp. rise
3 Heating
4 Peak
5 Gradual cooling
Temperature
140 to 180 °C
Preheating temp
to Peak temp.
220 °C min.
260 °C max.
Peak temp.
to 140 °C
Period or Speed
60 to 120 sec
2 to 5 °C /sec
60 sec max.
10 sec max.
1 to 4 °C /sec
Recommended profile of Reflow soldering (EX)
4 Peak
260
Temperature (˚C)
When conducting flow soldering, stress from abrupt
temperature change is applied to the Varistors, so the
temperature, especially temperature of solder should
be controlled very carefully. Varistors should not be
subjected to abrupt temperature change because it
causes occurrence of thermal cracks as a result of
excessive thermal stress inside of the Varistors from
flow soldering. You should be careful to temperature
difference. Therefore it is essential that soldering
process follow these recommended conditions.
(1) Application of Soldering flux :
The soldering flux shall be applied to the
mounted Varistors thinly and uniformly by foaming
method.
(2) Preheating :
Conduct sufficient pre-heating, and make sure
that the temperature difference between solder
and Varistors’ surface is 150 °C or less.
(3) Immersion into Soldering bath :
The Varistors shall be immersed into a soldering
bath of 240 to 260 °C for 3 to 5 seconds.
(4) Gradual Cooling :
After soldering, avoid rapid cooling (forced
cooling) and conduct gradual cooling, so that
thermal cracks do not occur.
(5) Flux Cleaning :
When the Varistors are immersed into a cleaning
solvent, be sure that the surface temperatures of
devices do not exceed 100 °C.
(6) P e r f o r m i n g f l o w s o l d e r i n g o n c e u n d e r
the conditions shown in the figure below
[Recommended profile of Flow soldering (Ex)] will
not cause any problems. However, pay attention
to the possible warp and bending of the PC
board.
Soldering
260
240
220
△T
4. Selection of Soldering Flux
Recommended profi le for Flow Soldering [Ex.]
Temperature(˚C)
(4) The closing dimensions of the positioning
chucks shall be controlled. Maintenance and
replacement of positioning chucks shall be
performed regularly to prevent chipping or
cracking of the Varistors caused by mechanical
impact during positioning due to wor n
positioning chucks.
(5) Maximum stroke of the nozzle shall be adjusted
so that the maximum bending of PC board
does not exceed 0.5 mm at 90 mm span. The
PC board shall be supported by an adequate
number of supporting pins.
2 Temp. rise
5 Gradual
cooling
180
140
1 Preheating
3 Heating
60 to 120 sec
60 sec max.
Time
△T : Allowable temperature difference △T < 150 °C
The rapid cooling (forced cooling) during Gradual
cooling part should be avoided, because this may
cause defects such as the thermal cracks, etc.
When the Varistors are immersed into a cleaning
solvent, make sure that the surface temperatures of
the devices do not exceed 100 °C.
Performing reflow soldering twice under the
conditions shown in the figure above “Recommended
profile of Reflow soldering (EX)” will not cause any
problems. However, pay attention to the possible
warp and bending of the PC board.
Design and specifications are each subject to change without notice. Ask factory for the current technical specifications before purchase and/or use.
Should a safety concern arise regarding this product, please be sure to contact us immediately.
00
Apr. 2016
Multilayer Varistors for Automotive
5.3 Hand Soldering
6. Post Soldering Cleaning
Hand soldering typically causes significant
temperature change, which may induce excessive
thermal stresses inside the Varistors, resulting in
the thermal cracks, etc.
In order to prevent any defects, the following
should be observed.
· Control the temperature of the soldering tips
with special care.
· Avoid the direct contact of soldering tips with
the Varistors and/or terminal electrodes.
· Do not reuse dismounted Varistors.
(1) Condition 1 (with preheating)
(a) Soldering :
Use thread solder (01 mm or below) which
contains flux with low chlorine, developed
for precision electronic equipment.
(b) Preheating :
Conduct sufficient pre-heating, and make
sure that the temperature dif ference
between solder and Varistors’ surface is
150 °C or less.
(c) Temperature of Iron tip: 350 °C max.
(The required amount of solder shall be
melted in advance on the soldering tip.)
(d) Gradual cooling :
After soldering, the Varistors shall be
cooled gradually at room temperature.
Recommended profile of Hand soldering [EX]
6.1 Cleaning solvent
Soldering flux residue may remain on the PC
board if cleaned with an inappropriate solvent.
This may deteriorate the performance of Varistors,
especially insulation resistance.
6.2 Cleaning conditions
Inappropriate cleaning conditions such as
insufficient cleaning or excessive cleaning may
impair the electrical characteristics and reliability
of the Varistors.
(1) Insufficient cleaning can lead to :
(a) The halogen substance found in the residue
of the soldering flux may cause the metal of
terminal electrodes to corrode.
(b) The halogen substance found in the residue
of the soldering flux on the surface of the
Varistors may change resistance values.
(c) Water-soluble soldering flux may have more
remarkable tendencies of (a) and (b) above
compared to those of rosin soldering flux.
(2) Excessive cleaning can lead to :
(a) When using ultrasonic cleaner, make sure
that the output is not too large, so that the
substrate will not resonate. The resonation
causes the cracks in Varistors and/or
solders, and deteriorates the strength of the
terminal electrodes.
Please follow these conditions for Ultrasonic
cleaning:
Ultrasonic wave output
: 20 W/L max.
Ultrasonic wave frequency
: 40 kHz max.
Ultrasonic wave cleaning time : 5 min. max.
△T
Gradual cooling
6.3 Contamination of Cleaning solvent
Cleaning with contaminated cleaning solvent may
cause the same results as that of insufficient cleaning
due to the high density of liberated halogen.
Preheating
60 to 120 sec
3 sec max.
△T : Allowable temperature difference △T<150 °C
(2) Condition 2 (without preheating)
Hand soldering can be performed without
preheating, by following the conditions below:
(a) Soldering iron tip shall never directly touch
the ceramic and terminal electrodes of the
Varistors.
(b) The lands are sufficiently preheated
with a soldering iron tip before sliding
the soldering iron tip to the terminal
electrodes of the Varistors for soldering.
Conditions of Hand soldering without preheating
Condition
Temperature of Iron tip
350 °C max.
Wattage
20 W max.
Shape of Iron tip
03 mm max.
Soldering time with a soldering iron
3 sec max.
7. Inspection Process
The pressure from measuring terminal pins might
bend the PCB when implementing circuit inspection
after mounting Varistors on PCB, and as a result,
cracking may occur.
(1) Mounted PC boards shall be supported by an
adequate number of supporting pins on the back
with bend settings of 90 mm span 0.5 mm max.
(2) Confirm that the measuring pins have the right
tip shape, are equal in height, have the right
pressure and are set in the correct positions.
The following figures are for your reference to
avoid bending the PC board.
Prohibited setting
Recommended setting
Check pin
Check pin
Bending of
PC board
Separated, Crack
Supporting pin
Design and specifications are each subject to change without notice. Ask factory for the current technical specifications before purchase and/or use.
Should a safety concern arise regarding this product, please be sure to contact us immediately.
00
Apr. 2016
Multilayer Varistors for Automotive
8. Protective Coating
10. Mechanical Impact
When the surface of a PC board on which the
Varistors have been mounted is coated with resin
to protect against moisture and dust, it shall be
confirmed that the protective coating does not affect
the performance of Varistors.
(1) Choose the material that does not emit the
decomposition and/or reaction gas. The Gas may
affect the composing members of the Varistors.
(2) Shrinkage and expansion of resin coating when
curing may apply stress to the Varistors and may
lead to occurrence of cracks.
9. Dividing/Breaking of PC Boards
(1) Please be careful not to stress the substrate with
bending/twisting when dividing, after mounting
components including Varistors. Abnormal and
excessive mechanical stress such as bending or
torsion shown below can cause cracking in the
Varistors.
Bending
(1) The Varistors shall be free from any excessive
mechanical impact. The Varistor body is made
of ceramics and may be damaged or cracked if
dropped. Never use a Varistor which has been
dropped; their quality may already be impaired,
and in that case, failure rate will increase.
(2) When handling PC boards with Varistors mounted
on them, do not allow the Varistors to collide with
another PC board.
When mounted PC boards are handled or stored
in a stacked state, the corner of a PC board
might strike Thermistors, and the impact of the
strike may cause damage or cracking and can
deteriorate the withstand voltage and insulation
resistance of the Varistor.
Mounted PCB
Crack
Crack
Torsion
Floor
(2) Dividing/Breaking of the PC boards shall be
done carefully at moderate speed by using a
jig or apparatus to prevent the Varistors on the
boards from mechanical damage.
(3) Examples of PCB dividing/breaking jigs:
The outline of PC board breaking jig is shown
below. When PC board are broken or divided,
loading points should be close to the jig to
minimize the extent of the bending.
Also, planes with no parts mounted on should
be used as plane of loading, in order to prevent
tensile stress induced by the bending, which
may cause cracks of the Varistors or other parts
mounted on the PC boards.
Other
The various precautions described above are typical.
For special mounting conditions, please contact us.
Outline of Jig
PC board
V-groove
PC board
splitting jig
Prohibited dividing
Recommended dividing
Loading direction
Loading
point
PC
board
Chip
component
V-groove
PC
board
Loading direction
V-groove
Chip component
Loading
point
Design and specifications are each subject to change without notice. Ask factory for the current technical specifications before purchase and/or use.
Should a safety concern arise regarding this product, please be sure to contact us immediately.
00
Apr. 2016
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