Page 1
Page 2
Automotive Relay User’s Guide
,
Please use the check sheet. 1
Category Section Contents
1. Confirmation
under the
actual use
condition
2. Safety
precautions
3. Selection of
relay type
1. Confirmation
under the
actual use
1. Specification
range
2. Installation,
maintenance
3. Connection When connecting terminals, please follow the internal connection diagrams in the catalog to ensure that
4. Fail-safe If there is a possibility that adhesion, contact failure, or breaking of wire could endanger assets or human
1. Selection In order to use the relays properly, the characteristics of the selected relay should be well known, and the
The rated switching power and life mentioned in the specification and catalog are given only as guides. A
relay may encounter a variety of ambient conditions during actual use result ing in unexpected failure.
Therefore, it is necessary for proper use of the relay to test and review with actual load and actual
application under actual operating conditions.
Use that exceeds the specification ranges such as the coil rating, contact rating and switching life should
be absolutely avoided. Doing so may lead to abnormal heating, smoke, and fire.
Never touch live parts when power is applied to the relay. Doing so may cause electrical shock. When
installing, maintaining, or troubleshooting a relay (including connecting parts such as terminals and
sockets), be sure that the power is turned off.
connections are done correctly. Be warned that an incorrect connection may lead to unexpected
operation error, abnormal heating, and fire.
life, please make sure that a fail-safe system is equipped in the vehicle.
conditions of use of the relay should be investigated to determine whether they are matched to the
environmental conditions, and at the same time, the coil specification, contact specification, and the
ambient conditions for the relay that is actually used must be fully understood in advance.
In the table below, please refer to a summary of the consideration points regarding selection of relay.
Items Consideration points regarding selection
- Select relay with consideration for power source ripple.
- Give sufficient consideration to ambient temperature
and for the coil temperature rise, and hot start.
- When used in conjunction with semiconductors, careful
with the voltage drop.
- When starting up, careful with the voltage drop.
- Note that the relay life is balanced with the life of the
device the relay is used in.
- Is the contact material matched to the type of load? It is
necessary to take care particularly with low level usage.
- The rated life may become reduced when used at high
temperatures. Life should be verified in the actual use
atmosphere.
- It is necessary to be tested and reviewed under actual
use conditions with actual load and actual application.
- Note that ambient temperature and applied voltage
cause the change of operate time and bounce time.
- Note that operate time and release time do not include
bounce time.
- Give consideration that switching life changes
depending on switching frequency.
- Give consideration to performance under vibration and
shock in the use location.
- Confirm the allowable ambient temperature of the relay.
- Selection can be made for connection method with
plug-in type, printed circuit board type, soldering, and
screw fastening type.
- Selection of protection construction can be made for
PCB mounting method such as soldering and cleaning.
- For use in an adverse atmosphere, sealed construction
type should be selected.
- Are there any special conditions?
Coil
Contact
Operate time
Mechanical
characteristics
Other items
a) Rating
b) Pull-in voltage
(current)
c) Drop-out voltage
(current)
d) Maximum continuous
impressed voltage
(current)
e) Coil resistance
f ) Temperature rise
a) Contact arrangement
b) Contact rating
c) Contact material
d) Life
e) Contact resistance
a) Operate time
b) Release time
c) Bounce time
d) Switching frequency
a) Vibration resistance
b) Shock resistance
c) Ambient use
temperature
d) Life
a) Breakdown voltage
b) Mounting,
Connection
c) Size
d) Protection
construction
Panasonic Electric Works
Obihiro Co., Ltd.
Oct. 1
2008: 1stEdition
Page 3
4. Load,
Electrical life
2
1. General Contact performance is significantly influenced by voltage and current values applied to the contacts (in
particular, the voltage and current waveforms at the time of application and release), the type of load,
frequency of switching, ambient atmosphere, contact switching speed, and of bounce, which lead the
various other damages such as unsuitable operation contact transfer, welding, abnormal wear, increase
in contact resistance. Therefore, please confirm that in actual use conditions such as actual circuit and
actual load or contact our company.
2. Inductive
load
In the case of switching on and off with inductive loads such as coil, magnet crutch, and solenoid, the arc
at switching can cause a severe damage on contacts and greatly shortening of life. In addition, in the
case of switching at a high frequency, a blue-green corrosion may be developed. So, please contact our
company to use it.
If the current in the inductive load is relatively small, the arc discharge decomposes organic matter
contained in the air and causes black deposits (oxides, carbides) to develop on the contacts. This may
result in contact failure. So, please contact our company to use it.
3. Lamp load
Large inrush current enhancing contact welding will be impressed. Its current value is greatly affected by
wiring resistance, switching frequency and ambient temperature. The load current characteristics in
actual circuit and actual use condition must be examined and sufficient margin of safety must be
provided in selection of a relay.
It is dangerous to use a lamp load whose nominal current is small even a large nominal current has been
tested beforehand.
Please contact us when switching at nominal current with a small lamp load (40W or less), because
continuous ON failure may occur due to locking caused by contact-transfer phenomenon when switching
arc is locally concentrated.
4.Electric-
discharge
lamp load
5. LED lamp
load
6. Other lamp
load
7. Motor load
Its load current tends to cause contact welding easily because its inrush current is larger than that of the
regular lamp load. The load current characteristics in actual circuit and actual use condition must be
examined and sufficient margin of safety must be provided in selection of a relay.
It is necessary to check the contact reliability because the load current of the LED load is very small.
Please contact us before use.
Please contact us before use of new structured lamp except for halogen, Electric-discharge lamp, and
LED.
When using of NC contact side of 1C contact for the motor brake, mechanical life might be affected by
the brake current. Therefore, verify in actual use conditions with actual circuit.
Note that larger inductivity of motor may cause contact damage and transfer even the motor load current
is same.
8. Capacitor
load
Note that its load current tends to cause contact welding and contact transfer easily because its inrush
current is generally large which has a small break current and a short time period to reac h an inrush
peak value.
Also, inrush current value is influenced by wiring resistance. Therefore, the inrush current in actual circuit
must be examined and sufficient margin of safety must be provided in selection of a relay.
9. Resistance
load
10. Small
electric
This load causes relatively-less contact damage since its inrush current is not large. Select a relay based
on the rating control capacity, or contact us.
If the switching current is small (2A or less), contact reliability decreases since the contact surface is not
cleaned by switching arc. So, please contact us for use.
current
load
11. Load
polarity
12. Voltage
drop of
power
supply
Electrical life may be affected by load polarity (+/-) connecting to relay contacts. So, please verify them in
actual use polarity.
Under a circuit which inrush current is applied to such as lamps and capacitors, the moment the contact
is closed, voltage drop to the coil, return of relay, or chattering may occur. Note that it may remarkably
reduce the electrical life.
Load
Page 4
4. Load,
Electrical
life
3
13. Load
voltage
If the load voltage is high, the arc energy which generated at contact switching increases, which may
decrease the electrical life. Therefore, it is necessary to give consideration to the voltage which could
occur in actual use condition.
14. Coil voltage If coil applied voltage gets higher, the relay operate time gets faster. However, contact bounce gets also
larger so that the electrical life may decrease.
15. Coil
short-pulse
input
When the short-pulse signal is input to the relay coil, the relay movable part may operate a nd touch
lightly to the contact. Therefore, please avoid short pulse input (100ms or less) since it may cause
contact welding due to less contact pressure. Please test adequately, for example when a relay is
operated by external manual switch (such as key switch.)
16. High-
frequency
When the switching frequency is high, the electrical life may decrease. Please confirm if there is a
high-frequent switching caused by abnormal mode in actual use condition.
of switching
17. Low-
frequency
Note that if the contact has not been switched for a long time period, organic film tends to be generated
on the contact surface, which may cause contact instability.
of switching
18. Ambient
Verify in the actual use condition since electrical life may be affected by use at high temperatures.
temperature
19. Connection
of coil surge
absorption
circuit
If resistor, diode, zener diode are connected parallel to decrease the surge voltage when the relay coil
being turned off, the relay release time will get longer and may decrease the electrical life or cause
light-welding.
Load
20. Sneak or
remaining
current
Please test a relay in actual vehicle condition since there is a risk of deterioration at relay function or
switching performance such as slower release time which is caused by sneak current due to diode,
zener diode, capacitor mounted on a vehicle or by remaining current soon after a motor is turned off.
21. Wire length If long wires (a few ten meters) are to be used in a relay contact circuit, inrush current may become a
problem due to the stray capacitance existing between wires. In such case, add a resistor in series with
the contacts.
Page 5
4. Load,
electrical life
4
22. Contact
protective
circuit
Use of contact protective devices or protection circuits can suppress the counter emf to a low level.
However, note that incorrect use will result in an adverse effect. Typical contact protection circuits are
given in the table below.
Also, note that release time will slow down due to sneak in the circuit and may cause the electrical life to
shorten and slight-welding.
Diode circuit
Circuit
The diode connected in parallel causes the energy stored in the coil
to flow to the coil in the form of current and dissipates it as joule
Features/Others
Devices Selection
heat at the resistance component of the inductive load. This circuit
delays the release time. (2 to 5 times the release time listed in the
catalog)
Use a diode with a reverse breakdown voltage at least 10 times the
circuit voltage and a forward current at least as large as the load
current or larger.
In electronic circuits where the circuit voltages are not so high, a
diode can be used with a reverse breakdown voltage of about 2 to 3
times the power supply voltage.
Diode and zener diode circuit
Circuit
Features/Others It is effective in the diode circuit when the release time is too long.
Devices Selection
In the actual circuit, it is necessary to mount the protective device (diode etc.) in the immediate vicinity of
the load. If it is mounted too far away , the ef fectiveness of the protective device may diminish. As a guide,
the distance should be within 50cm.
Avoid using the protection circuits shown in the figures below.
Although it is usually more difficult to switch with DC inductive loads compared to resistive loads, use of
the proper protection circuit will raise the characteristics to that for resistive loads.
Use a zener diode with a zener voltage about the same as the power
supply voltage
Although it is extremely effective in arc
suppression as the contacts open, the
contacts are susceptible to welding since
energy is stored in C when the contacts open
and discharge current flows from C when the
contacts close.
Although it is extremely effective in arc
suppression as the contacts open, the
contacts are susceptible to welding since
charging current flows to C when the
contacts close.
Page 6
4. Load,
electrical
life
5. Coil
impressed
voltage
5
23. Connection
of load
24. Short
between
interelectrodes
1. Hot start
voltage
2. Ambient
temperature
characteristic
3. Applied
voltage
Connect the load to one side of the power supply as shown in Fig. (a). Connect the contacts to the other
side. This prevents high voltages from developing between contacts. If contacts are connected to both
side of the power supply as shown in Fig. (b), there is a risk of shorting of the power supply when
relatively close contacts short.
Fig. (a) Good example (b) Bad example
Regarding the following circuit constructions with 2-coil relays (twin relays) or single-pole relays, an arc
between contacts may be generated when breaking of load current depending on the type of load
current, voltage, and load. Please note that or contact us.
＜2 coil relay (twin relay) or two of single-pole relays＞
＜Single-pole relay＞
When using of multipole relays such as 2-coil relays (twin relays), verify insulation and breakdown
voltage between contacts in each pole in order to avoid an accident caused by short.
After continuous applying of current to coil and contacts, if the current is turned OFF then immediately
turned ON again, coil resistance and the pick-up voltage will increase due to the temperature rise in the
coil.
Temperature rise value of coil is greatly affected by circuit board, connected harness, connected
connector, heat dissipation of system/modules, and heat source around relay. Please verif y whether it is
operating properly or inoperative under actual vehicle and actual use con ditions.
Coil resistance and the pick-up voltage will increase when the relay is used in a higher temperature
atmosphere. The resistance/temperature coefficient of copper wire is about 0.4% for 1°C, and the coil
resistance increases with this ratio. On the other hand, coil resistance and the drop-out voltage will
decrease at lower temperature. Coil resistance change decreases with the same ratio at higher
temperature, about 0.4% for 1°C.
Therefore, please confirm the relay operation in every operating tem perature range, with attention to
such temperature characteristic.
The ambient usage temperature should be set as around the relay inside the box because a heat
generated by a relay itself or other instruments causes increase of temperature inside the box.
Note that a coil impression with a voltage greater than or equal to the maximum continuous impressed
voltage may cause temperature rise which could cause coil burning or layer short. Furthermore, do not
exceed the usable ambient temperature range listed in the catalog. Please contact us regarding PWM
control.
Ａ
Load
+
Load
+
B
B side OFF
Load
OFF
Load
+
+
Short current
Arcing
Arcing
Page 7
5. Coil
impressed
voltage
6. Coil
impressed
circuit
4.Twin-relay
coil
simultaneous
operation
5. Continuous
current
1. Relay drive
by means of
a transistor
6
For relays which have multiple coils such as twin relay for forward-reverse operation of motor, if the coils
are continuously turned on at the same time, the coil temperature may exceed the tolerance in a short
time due to heat generation of each coil. Please contact us before use.
Coil heating due to continuous current applying to coil for extensive time periods will cause deterior ation
in insulation performance for coil.
For such circuit types, please consider the fail-safe circuit design in case of contact failure or breaking of
coil.
1. Connection method
Collector connection method is the most recommendable when the relay is driven by means of a
transistor.
To avoid troubles in use, the rated voltage should always be impressed on the relay in the ON time and
zero voltage be done in the OFF time.
(Good) Collector connection
This is the most common
connection, which operation is
usually stable with.
2. Countermeasures for surge voltage of relay control transistor
If the coil current is suddenly interrupted, a sudden high voltage pulse is developed in the coil. If this
voltage exceeds the breakdown voltage of the transistor, the transistor will be degraded, and this will
lead to damage. It is absolutely necessary to connect a diode in the circuit as a means of preventing
damage from the counter emf. In case of DC relay, connection of Diode is effective. As suitable ratings
for this diode, the average rectified current should be equivalent to the coil current, and the reverse
blocking voltage should be about 3 times the value of the power source voltage. Connection of a diode is
an excellent way to prevent voltage surges, but there will be a considerable time delay when the relay is
open. If you need to reduce this time delay you can connect between the transistor's Collector and
Emitter with a Zener diode that will make the Zener voltage somewhat higher than the supply voltage.
Take care of Area of Safe Operation (ASO).
(Care) Emitter connection
When the circumstances make
the use of this connection
unavoidable, the voltage may not
be completely impressed on the
relay and the transistor would not
conduct completely.
Diode
(Care) Parallel connection
As the power consumption of
the entire circuit increases,
the relay voltage should be
considered.
Page 8
6. Coil
impressed
circuit
7
1. Relay drive
by means of
a transistor
3. Snap action (Characteristic of relay with voltage rise and fall)
It is necessary for the relay coil not to impress voltage slowly but to impress the rated voltage in a short
time and also to drop the voltage to zero in a short time.
Non-pulse signal
Pulse signal (square wave)
(No good) Without snap action (Good) Snap action
4. Schmitt circuit (Snap action circuit) (Wave shaping circuit)
When the input signal does not produce a snap action, ordinarily a Schmitt trigger circuit is used to
produce safe snap action.
1. The common emitter resistor R
must have a sufficiently small value compared with the resistance of
E
the relay coil.
2. Due to the relay coil current, the difference in the voltage between at point P when T
at point P when T
is conducting creates hysteresis in the detection capability of Schmitt circuit, and care
1
is conducting and
2
must be taken in setting the values.
3. When there is chattering in the input signal because of waveform oscillation, an CR time constant
circuit should be inserted in the stage before the Schmitt trigger circuit. (However, the response speed
drops.)
5. Avoid Darlington circuit connections. (High amplification)
Care must be taken in this circuit due to increase of V
. It does not cause a failure immediately, but it
CESAT
may lead to troubles by using for a long period or by operating with many units.
（No good） Darlington connection
Due to excessive consumption of
power, heat is generated.
(Good) Emitter connection
Tr2 conducts completely.
Tr1 is sufficient for signal use.
A strong Tr1 is necessary.
Page 9
6. Coil
impressed
circuit
8
1. Relay drive
by means of
a transistor
6. Residual Coil Voltage
In switching applications where a semiconductor (transistor, UJT, etc.) is connected to the coil, a residual
voltage is retained at the relay coil which may cause incomplete restoration and faulty operation. Using
of DC coils may cause incomplete restoration or reduction in contact pressure and vibration resistance,
because its drop-out voltage is lower than that of AC coil (10% or more of the rated voltage) also
because there is a tendency to increase the life by lowering the drop-out voltage.
When the signal from the transistor's collector is taken and used to drive another circuit as shown in the
figure as follows, a minute dark current flows to the relay even if the transistor is off. This may also cause
the problems described above.
Connection to the next stage through collector
2. Relay drive
by means of
SCR
1. Ordinary drive method
For SCR drive, it is necessary to take particular care with regard to gate sensitivity and erroneous
operation due to noise.
IGT : There is no problem even with more than 3 times
the rated current.
R
: 1K ohms must be connected.
GK
RC : This is for prevention of switching error due to a
sudden rise in the power source or to noise.
2. Cautions regarding ON/OFF control circuits
(when used for temperature control circuits or similar one)
Care must be taken because the electrical life suffers extreme shortening when the relay contacts close
simultaneously with an AC single phase power source.
1. When the relay is turned ON and OFF using a SCR, the SCR serves as a half wave power source as it
is, and there are ample cases where the SCR is easily restored.
2. In this manner the relay operation and restoration timing are easily synchronized with the power
source frequency, and the timing of the load switching also is easily synchronized.
3. In case of the load for temperature control whose load is a high current load such as a heater, some
relays switch only peak values and some other rela ys switch only zero phase v alues as a phenom enon
of this type of control. (Depending upon the sensitivity and response speed of the relay)
4. Accordingly, it causes either an extremely long life or an extremely short life resulting in wide variation.
So, it is necessary to take care with the initial device quality check.
Page 10
9
７. Contact
reliability
8. Contact
resistance
9. Operate
noise
10.Mechanical
noise
11. Electrical
noise
1. Load switch When switching with a very small load after switching with a large load, “contact failure by small load
switching” may occur due to particles generated during switching of the contact with large load. Please
note that or contact us.
2. Installation
condition
1. Transient
state
2. Contact
voltage,
current
1. Coil applied
voltage
2. Operate
noise at
installation
1. Abnormal
noise
1. Serge
voltage
Note that if it is connected or installed with a high heat-capacity such as bas bar, connector, harness,
and PCB, heat removal phenomenon at low temperature will make relay terminals and contacts cool and
condensate a small amount of organic gas inside the relay, which may cause a contact failure. So,
please contact us before use.
Contact resistance consists of dynamic and static contact resistance. “Contact resistance” on the
catalogue and the specifications refers to static contact resistance. Dynamic contact resistance usually
shows a large value due to just after the contact operation. Please contact us if a stable contact
resistance is necessary soon after a relay is turned on.
Note that if the contact-applied voltage is small (at 6V or less) and contact-applied current is small (at 1A
or less), contact resistance may become a larger value due to a small amount of film on a contact
surface.
Mechanical relays produce an operational noise at operate and release time. Note that if the coil-applie d
voltage is higher at operate time, the noise becomes larger.
It is necessary to test relays in actual installation condition because operate noise may become larger in
the installation condition than with a relay by itself due to resonance and sympathetic vibrations of
installation PCB and system module.
Note that if a large current is applied to the contact, electromagnetic repulsion makes contact vibrate and
produces an abnormal noise. Please contact us if quietness is required.
Note that if an external vibration and shock are applied to a relay while the relay turns off, a movable part
of the relay may vibrate and produce a noise. So, please test in the actual use condition if quietness is
required.
When the relay turns off, serge voltage is generated from the coil. This serge voltage can be reduced if a
resistor is connected in parallel to the coil. Likewise, it can be reduced more if a diode instead of resistor
is connected in parallel.
However, please contact us or note that if a resistor or a diode is connected in parallel electrical life may
be affected due to slowing down of release time.
Page 11
10
12. Usage
ambient
condition
1.Temperature,
humidity,
air pressure
During usage, storage, or transportation, avoid locations subject to direct sunlight and maintain normal
temperature, humidity, and pressure conditions.
The allowable specifications for environments suitable for usage, storage, and trans portation are given
below.
1. Temperature: The allowable temperature range differs with each relay, so refer to the relay's
individual specifications. In addition, in the case of transporting and storing relays in a tube package, the
temperature may differ from the allowable range of the relay. So, please contact us for individual
specifications.
2. Humidity: 5 to 85 % R.H.
3. Pressure: 86 to 106 kPa
Furthermore, the humidity range varies with the temperature. So, use relays within the range indicated in
the graph below.
(The allowable temperature range differs for each relay.)
-Be sure the usage ambient temperature does not exceed the value listed in the catalog.
-When switching with a load which easily generates arc in high-humidity environment, the NO
generated by the arc and the water absorbed from outside the relay combine to produce nitric acid.
This corrodes the internal metal parts and adversely affects operation. Avoid using them at an ambient
humidity of 85%RH or higher (at 20°C). If it is unavoidable to use them in such environment, please
consult us.
-Plastic sealed type relay s are es pecially not suited for use in environments which require airtight relays.
Although there is no problem if they are used at sea level, avoid using them in atmospheric pressures
beyond 96±10kPa. Also avoid using them in an atmosphere containing flammable or explosive gases.
2. Dust It is recommendable to use relays in a normal temperature and humidity with less dust, sulfur gases
(SO
, H2S), and organic gases.
2
Sealed types (plastic sealed type) should be considered for applications in an adverse environment.
3. Silicon Silicon-based substances (silicon rubber, silicon oil, silicon-based coating material, silicon caulking
compound, etc.) emit volatile silicon gas. Note that when silicon is used near relay, switching the
contacts in the presence of its gas causes silicon to adhere to the contacts and may result in contact
failure.
Therefore, please use a substitute that is not silicon-based. Plastic also has air permeability so please
avoid using them in a silicone atmosphere.
4. Magnetism If relays are proximately installed each other or installed near highly-magnetized parts such as motor
and speaker, the relay may change its operational characteristics or cause malfunction. So, please
verify in actual installation and operational condition.
5. Vibration Vibration of the area where relay is installed may be enhanced more than expected depe nding on
installation condition of PCB. So, please verify in actual use condition. NO contact is the recommended
contact for the use at the vibration-frequent area because the vibration resistance performance of NC
contact is generally inferior to that of NO contact.
6. Shock It is ideal for mounting of relay that the movement of the contacts and movable parts is perpendicular to
the direction of vibration or shock. Especially note that the vibration and shock resistance of NC contacts
while the coil is not excited is greatly affected by the mounting direction of the relay.
7. Dew
condensation
Condensation forms when vapors when there is a sudden change in temperature under hig h
temperature, high humidity conditions. Note that condensation may cause deterioration of the insulation,
breaking of coil, and rusting.
Note that if a relay is connected or installed with a high heat-capacity such as bas bar, connector,
harness, and PCB, heat removal phenomenon will accelerate cooling of the relay inside and promote
condensation. So, please verify in actual installation condition.
x
Page 12
12. Usage
f
ambient
condition
11
8. Water
resistance
Select the sealed-type for exposure to water. In the case of water exposure in severe conditions or
immersion, please verify water resistance of the relay or contact us. Even for sealed-type relays, its
terminals are not waterproof, so please avoid a failure such as terminal corrosion.
9. Freezing
10. Low
temperature,
low humidity
13.Installation 1. Connector
installation
14. PC board
design
1. PC board
design
consideration
Note that moisture adhered on relay in a due condensation or a high humidity condition freezes when
the temperature is lower than 0°C. This may cause problems such as sticking of movable parts or
operational time lags, or poor contact conduction. Therefore, please test them in actual use
environment.
Note that if a relay is connected or installed with a high heat-capacity such as bas bar, connector,
harness, and PCB, heat removal phenomenon will accelerate cooling of the relay inside and promote
freezing. So, please verify in actual installation condition.
The plastic becomes brittle if the relay is exposed to a low temperature, low humidity environment for
long periods of time.
Please consider the vibration at installation area to avoid loosely-contact.
Also, note that even a microscopic vibration may cause contact failure at the contact area of relay
terminal and connector.
Decrease of fitting performance of connector may cause abnormal heat at connector contact area
depending on use temperature and applying heat. Sufficient margin of safety must be provided in
selection of a connector.
Please select the proper material of connector and surface treatment to avoid corrosion at the contact
area of relay terminal and connector and increase of resistance at connecting area which ma y be
caused depending on ambient environment.
1. Cautions regarding Pattern Layout for Relays
Since relays affect electronic circuits by generating noise, the following points should be noted.
• Keep relays awa y from semi conductor devices.
• Design the pattern traces with the shortest length.
• Place the surge absorber (diode, etc.) near the relay coil.
• Avoid routing pattern traces susceptible to n oise (suc h as for audio signals) underneath the
relay coil section.
• Avoid through-holes in places which cannot be seen from the top (e.g. at the base of the
relay). Solder flowing up through such a hole may cause damage such as a sealing failure.
• Even for the same circuit, it is necessary to consider the pattern design in order to min imize
the influence of the on/off operations of the relay coil and lamp on other electronic circuits, as
shown in the figure below.
-Relay currents and electronic circuit
currents flow together through A and B.
-Relay coil currents consist only of A1 and B1.
-Electronic circuit currents consist only of A2
and B2. A simple design can change safety o
the operation.
Page 13
14. PC board
design
12
2. Hole and
Land
diameter
The Hole and Land diameter are made with the hole slightly larger tha n th e lead wire so that the
component may be inserted easily. Also, when soldering, the solder will build up in an eyelet condition,
increasing the mounting strength. The standard dimensions for the Hole diameter and Land are shown
in the table below.
Standard dimensions for the Hole and Land diameter
Unit: mm/ inch
Standard Hole
0.8/ .031
1.0/ .039
1.2/ .047
1.6/ .063
Remarks
Tolerance Land diameter
2.0 to 3.0/ .079 to .118
±0.1/ ±.039
3.5 to 4.5/ .138 to .177
• The Hole diameter is made 0.2 to 0.5mm/ .008 to .020inch larger than the lead diameter.
However, if the jet method (wave type, jet type) of soldering is used, solder may pass through
to the component side. Therefore, it is more suitable to make the Hole diameter equal to the
lead diameter +0.2mm.
• The Land diameter should be 2 to 3 times the Hole diameter.
• Do not put more than 1 lead in one hole.
3. Expansion
and
shrinkage
of
copper-clad
laminates
Because copper-clad laminates have a longitudinal a nd lateral direction, the manner of punching
fabrication and layout must be observed with care. Expansion and shrinkage in the longitudinal direction
due to heat is 1/15 to 1/2 of that in the lateral, and accordingly, after the punching fabrication, the
distortion in the longitudinal direction will be 1/15 to 1/2 of that in the lateral direction. The mechanical
strength in the longitudinal direction is 10 to 15% greater than that in the lateral direction. Because of
this difference between the longitudinal and lateral directions, when produc ts having long configurations
are to be fabricated, the lengthwise direction of the configuration should be made in the longitudinal
direction, and PC boards having a connector section should be made with the connector along the
longitudinal side.(The figure below)
Example: As shown in the drawing below, the 150mm (5.906 inch) direction is taken in the longit udinal
direction.
Also, as shown in the drawing below, when the pattern has a connector section, the direction is taken as
shown by the arrow in the longitudinal direction.
Page 14
15. PCB
mounting
13
1. Through-hole type
In keeping with making devices compact, it is becoming more common to solder the relay to a PC board along with the
semiconductors instead of using the previous plug-in type in which relays were plugged into sockets.
With this style, loss of function may occur because of seepage into the relay of flux, which is applied to the PC board. Therefore,
the following precautions are provided for soldering a relay onto a PC board. Please refer to them during installation in order to
avoid problems.
The type of protective structure will determine suitability for automatic soldering or automatic cleaning. Therefore, please review
the parts on construction and characteristics.
1. Mounting of Relay
• Avoid bending the terminals to make
the relay self-clinching. Relay
performance cannot be guaranteed if
the terminals are bent.
• Correctly make the PC board according
to the given PC board pattern
illustration.
• Tube packaging for automatic mounting
is available depending on the type of
relay. (Be sure that the relays don't
rattle.) Interference may occur internally
if the gripping force of the tab of the
surface mounting machine is too great.
This could impair relay performance.
Bad example
• Adjust the position of the PC board so
2. Flux Application
that flux does not overflow onto the top
of it. This must be observed especially
for dust-cover type relays.
• Use rosin-based non-corrosive flux.
• If the PC board is pressed down into a
flux-soaked sponge as shown on the
right, the flux can easily penetrate a
dust-cover type relay. Never use this
method. Note that if the PC board is
pressed down hard enough, flux may
even penetrate a flux-resistant type
relay.
• Be sure to preheat before using
3. Preheating
automatic soldering. For dust-cover
type relays and flux-resistant type
relays, preheating acts to prevent the
penetration of flux into the relay when
soldering. Solderability also improves.
• Preheat according to the following
conditions.
Bad example
• Note that long exposure to high
temperatures (e.g. due to a
malfunctioning unit) may affect relay
characteristics.
Temperature
Time
120°C/ 248°F or less
(PCB solder surface)
Within approx. 2
minute
Page 15
14
4. Soldering
5. Cooling
• Flow solder is the optimum method for
• Adjust the level of solder so that it does
• Unless otherwise specified, solder
Soldering Time
• Immediate air cooling is recommend to prevent deterioration of the relay and
• Although environmentally the sealed type relay (plastic sealed type, etc.) can be
Automatic Soldering Hand Soldering
• Please take caution with multi-layer
soldering.
not overflow onto the top of the PC
board.
under the following conditions
depending on the type of relay.
Solder
Temperature
surrounding parts due of soldering heat.
cleaned, avoid immersing the relay into cold liquid (such as cleaning solvent and
coating material) immediately after soldering. Doing so may deteriorate the sealing
performance.
Approx.260°C±5°C/
500°F±41°F
Within approx. 6
seconds
boards. Relay performance may
degrade due to the high thermal
capacity of these boards
• Keep the tip of the soldering iron
clean.
Soldering Iron 30W to 60W
Iron Tip
Temperature
Soldering Time
Approx. 350°C
Within approx. 3
seconds
6. Cleaning
7. Coating
• Do not clean dust-cover type relays and flux-resistant type relays by immersion.
Even if only the bottom surface of the PC board is cleaned (e.g. with a brush),
careless cleaning may cause cleaning solvent to penetrate the relay.
• Plastic sealed type relays can be cleaned by immersion. Use an alcohol-based
cleaning solvent. Use of other cleaning solvents (e.g. Trichlene, chloroethene,
thinner, benzyl alcohol, gasoline) may damage the relay case.
• Cleaning with the boiling method is recommended. Avoid ultrasonic cleani ng on
relays. Use of ultrasonic cleaning may cause breaks in the coil or slight sticking of
the contacts due to the ultrasonic energy.
• Do not cut the terminals. When terminals are cut, breaking of coil wire and slight
sticking of the contacts may occur due to vibration of the cutter.
• If the PC board is to be coated to prevent the insulation of the PC board from
deteriorating due to corrosive gases and high temperatures, note the following.
• Do not coat dust-cover t ype relays and flux-resistant type relays, since the coating
material may penetrate the relay and cause contact failure. Or, mount the relay
after coating.
• Depending on the type, some coating materials may have an adverse affect on
relays. Furthermore, some solvents (e.g. xylene, toluene, MEK, I.P.A.) may
damage the case or chemically dissolve the epoxy and break the seal. Select
coating materials carefully.
• If the relay and all components (e.g. ICs) are to be coated, be sure to carefully
check the flexibility of the coating material. The solder may peel off from thermal
stress.
Coating
material type
Epoxy-base Good
Urethane-base Care
Silicon-base No Good
Suitability
for Relays
Features
Good electrical insulation.
Although slightly difficult to apply, does not affect
relay contacts.
Good electrical insulation, easy to apply.
Solvent may damage case. Check before use.
Silicon gas becomes the cause of contact failure.
Do not use the silicon-base type.
Page 16
15
15. PCB
mounting
1. What is a Surface Mount Relay?
1. From IMT to SMT
2. SMD type
To meet the market demand for downsizing to smaller, lighter, and thinner products, PC boards also need to proceed from
insertion mounting to surface mounting technology.
To meet this need, we offer a line of surface mount relays. The following describes some cautions required for surface
mount relay installation to prevent malfunction and incorrect operation.
*Please contact us for or reflow soldering of through-hole terminal type.
Conventional insertion mount technology (IMT) with some 30 years of history is now being replaced with surface mount
technology (SMT).
Solid-state components such as resistors, ICs, and diodes can withstand high heat stresses from reflow soldering because
they use no mechanical parts. In contrast, the conventional electro-mechanical relays consisting of solenoid coils, springs,
and armatures are very sensitive to thermal stress from reflow soldering.
We applied the experience gained from our advanced relay technolo gies to produce high-performance electromagnetic
relays compatible with surface mount technologies such as IRS and VPS.
Insertion Mount Technology & Surface Mount Technology
Insertion
Mounting
Technology
(IMT)
Components' terminals are inserted into terminal
holes of PC board and are soldered to copper pads
on the other side of the board. (flow-soldering)
Mounting
Technology
2. Features and Effects
Allows high density mounting
Components can be installed on both sides of a board
Ceramic PC boards can be used
Compatible with automatic placement by robots
Drilling for lead holes is not required
Compact system designs are possible due to high density mounting
High heat resistance
Anti-gas measures
The surface mount relay is realized with the following advanced technologies:
• Heat-resistance encapsulation technique
• Gas analysis
• Reliability assessment
• Precision molding technique for heat-resistant materials
Surface
(SMT)
Components are placed on copper pads pre-coated
with paste solder and the board assembly is heated to
solder the components on the pads. (reflow soldering)
Features Effects
Chip resistor
System downsizing
Overall cost reduction
High reliability
Page 17
16
3. Examples of SMT Applications
IRS is the most popular reflow soldering technology now available for surface mounting. It
uses a sheath heater or infrared lamp as its heat source. PC board assemblies are
continuously soldered as they are transferred through a tunnel furnace comprised of a
preheating, heating, and cooling-stages.
1. Infrared Reflow Soldering
(IRS)
With VPS technology, PCB assemblies are carried through a special inactive solvent,
such as Fluorinert FC-70, that has been heated to a vapor state. As the saturated vapor
condenses on the PC board surface, the resulting evaporation heat provides the energy
for reflow soldering.
2. Vapor Phase Soldering (VPS)
3. Belt conveyer reflow oven
4. Double Wave Soldering (DWS)
5. Other Technologies
2. Cautions for installation
1. Paste Soldering
As PCB assemblies are transferred on a thin, heat-resistant belt conveyer, they are
soldered by the heat from hotplates placed beneath the conveyer belt.
After components are glued to the PC board surface, the board assembly is transferred
through a molten solder fountain (with the component side facing down). Then, the
components are soldered to the board.
Other reflow soldering technologies include those of utilizing lasers, hot air, and pulse
heaters.
• Mounting pads on PC boards
must be designed to absorb
placement errors while taking
account of solderability and
insulation. Refer to the
suggested mounting pad layout
in the application data for the
required relay product.
• Paste sold er may be applied on
the board with screen printing or
dispenser techniques. For either
method, the paste solder must
be coated to appropriate
thickness and shapes to
achieve good solder wetting and
adequate insulation.
2. Relay mounting
• For small, lightweight components such as chip components, a
self-alignment effect can be expected if small placement errors exist.
However, this effect is not as expected for electro-mechanical components
such as relays, and they require precise positioning on their soldering pads.
• If SMT relays are subjected to excessive mechanical stress from the
placement machine's pickup head and damaged inside, their performanc e
cannot be guaranteed.
• Our SMT relays are supplied in tube packaging compatible with automatic
placement processes. We also offer tape packaging at customer request..
Page 18
17
3. Reflow
Reflow soldering under inadequate soldering conditions may result in unreliable
relay performance or even physical damage to the relay (even if the relay is of
surface mount type with high heat resistance).
1.IRS profile
Note: When a soldering technique other than ab ove is to be used (hot air, hotplate,
laser, or pulse heater technique), carefully investigate the suitability of the
technique.
The soldering temperature profile indicates the pad temperature. In some
cases, the ambient temperature may be greatly increased. Examine it under
the specific mounting condition.
2.Manual soldering
Soldering iron tip temperature: 350°C (662°F)
Soldering iron wattage: 30 to 60 W
Soldering time: Less than 3 sec.
3.Others
For other solder methods except for the above (such as hot air heating, hot plate
heating, laser heating, pulse heating, etc.), please check for mounting and soldering
condition before use.
• It is recommended that the soldered pad be immediately cooled to prevent thermal
damage to the relay and its associated components.
• While surface mount relays are solvent washable, do not immerse the relay in cold
cleaning solvent immediately after soldering.
• While seale d-typ e (plastic-sealed) relays are solvent washable, do not immerse
4. Cooling / Cleaning
the relay in cold cleaning solvent immediately after soldering.
• Use alcohol or an equivalent solvent for cleaning.
• Boiled cle aning is approved for surface mount relays. Ultrasonic cleaning may
cause coil damage or light contact sticking.
Page 19
18
16. Soldering
1. Solder Please use the flux-resistant type or sealed type in the case of automatic soldering.
2. Cleaning
3. Terminal clinch Avoid bending terminals for the relay of print circuit board since it may cause malfunction.
Please use the sealed type for cleaning. Also, use the alcohol type for cleaning li quid and avoid
ultrasonic cleaning.
When cleaning a printed circuit board after soldering, we recommend using alcohol-type cleaning
liquid. Please avoid ultrasonic cleaning. The ultrasonic energy may cause breaking of coil and
sticking of contacts.
17. Storage,
transportation
18. Product
handling
1.Transportation Relay’s functional damage may occur if strong vibration, shock or heavy weight is applied to a relay
during transportation of a device in which a relay is installed. Therefore, please pack them in a way,
using shock-absorbing material, so that the allowable range for vibration and shock is not exceeded.
2. Storage If the relay is stored for extended periods of time (including transportation period) at high
temperatures or high humidity levels or in atmospheres with organic gas or sulfide gas, sulfide film or
oxide film may be formed on surface of the contacts, which may cause contact instability, contact
failure and functional failure. Please check the atmosphere in which the units are to be stored and
transported.
1. Tube packing
Some types of relays are supplied with tube packaging. If you remove some relays from the tube, be
sure to slide a stop plug into one end of a tube to hold the remaining relays firmly and avoid rattling of
relay inside the tube. Note that rattling may cause a damage on appearance and/or performance.
Do not use the relays if they were dropped or fallen down in a tube packing condition because there
is a risk of characteristic failure.
Fall of tube
Page 20
19
19. Reliability
[1] What is Reliability?
1. Reliability in a Narrow Sense of the Term
In the industrial world, reliability is an index of how long a particular product serves without failure during use period.
2. Reliability in a Board Sense of the Term
Every product has a finite service lifetime. This means that no product can continue normal service infinitely. When a product has brok en
down, the user may throw it away or repair it. The reliability of repairable products is recognized as "reliability in a broad sense of the
term." For repairable products, their serviceability or maintainability is another problem. In addition, reli ability of product design is
becoming a serious concern for the manufacturing industry. In short, reliability has three senses: i.e. reliability of the product itself,
serviceability of the product, and reliability of product design.
3. Intrinsic Reliability and Reliability of Use
Reliability is "built" into products. This is referred to as intrinsic reliability which consists mainly of reliability in the narrow sense. Product
reliability at the user's site is called "reliability of use," which consists mainly of reliability in the broad sense. In the relay industry, reliability
of use has a significance in aspects of servicing.
[2] Reliability Measures
The following list contains some of the most popular reliability measures:
Reliability measure Sample representation
Degree of reliability R(T) 99.9%
MTBF 100 hours
MTTF 100 hours
Failure rate lambda 20 fit, 1%/hour
Safe life B10 50 hours
Page 21
20
1. Degree of Reliability
Degree of reliability represents percentage ratio of reliability. For example, if none of 10 light bulbs has failed for 100 hours, the degree of
reliability defined in, 100 hours of time is 10/10 = 100%. If only three bulbs remained alive, the degree of reliabilit y is 3/10 = 30%. The JIS
Z8115 standard defines the degree of reliability as follows: The probabilit y at which a system, equipment, or part provides the specified
functions over the intended duration under the specified conditions.
2. MTBF
MTBF is an acronym of Mean Time Between Failures. It indicates the mean time period in which a system, equipment, or part operates
normally between two incidences of repair. MTBF only applies to repairabl e prod ucts.
MTBF tells how long a product can be used without the need for repair.
Sometimes MTBF is used to represent the service lifetime before failure.
3. MTTF
MTTF is an acronym of Mean Time To Failure. It indicates the mean time period until a product becomes faulty MTTF normally applies to
unrepairable products such as parts and materials.
The relay is one of such objective of MTTF.
4. Failure Rate
Failure rate includes mean failure rate and momentary failure rate. Mean failure rate is defi ned as follows:
Mean failure rate = Total failure count/total operating hours
In general, failure rate refers to momentary failure rate. This represents the probability at which a system, equipment, or part, which has
continued normal operation to a certain point of time, becomes faulty in the subsequent specified time period.
Failure rate is often represented in the unit of percent/hours. For parts with low failure rates, "failure unit (Fit) = 10
-９
/hour" is often used
instead of failure rate. Percent/count is normally used for relays.
5. Safe Life
Safe life is an inverse of degree of reliability. It is given as value B which makes the following equation true:
1 - R(B) = t%
In general, "B[1 - R(B)] = 10%" is more often used. In some cases this represents a more practical value of reliability than MTTF.
Page 22
21
[3] Failure
1. What is Failure?
Failure is defined as a state of system, equipment, or component in which part of all of its functions are impaired or lost.
2. Bathtub Curve
Product's failure rate throughout its lifetime is depicted as a bathtub curve, as shown below. Failure rate is high at the beginning and end of
its service lifetime.
(I) Initial failure period
The high failure rate in the initial failure period is derived from latent desi gn errors, process errors, and many other causes.. This
process is called debugging, performing aging or screening in order to find out initial failures.
(II) Accidental failure period
The initial failure period is followed by a long period with low, stable failur e rate. In this period, called accidental failure period,
failures occurs at random along the time axis. While zero accidental failure rate is desirable, this is actuall y not practical in the real
world.
(III) Wear-out failure period
In the final stage of the product's service lifetime comes the wear-out failure period, in which the life of the product expir es due to
wear of fatigue. Preventive maintenance is effective for this type of failure. The timing of a relay's wear-out failure can be predicted
with a certain accuracy from the past record of uses. The use of a relay is intended only in the accidental failure period, and this
period virtually represents the service lifetime of the relay.
Page 23
22
3. Weibull Analysis
Weibull analysis is often used for classifying a product's failure patterns and to determin e its lifetime.
Weibull distribution is expressed by the following equation:
where
Weibull distribution can be adopted to the actual failure rate distribution if the three variables ab ove are estimated.
The Weibull probability chart is a simpler alternative of complex calculation formulas. T he chart provides the following advantages:
(1) The Weibull distribution has the closest proximity to the actual failure rate distribution.
(2) The Weibull probability chart is easy to use.
(3) Different types of failures can be identified on the chart.
The following describes the correlation with the bathtub curve. The value of the parameter "m" represents the type of the failure.
(1) When m < 1 : Initial failures
(2) When m = 1 : Accidental failures
(3) When m > 1 : Wear-out failures
Page 24
Product name:
Relay name:
Date:
Category
Safety
Load/
Electrical life
Coil operation
voltage
Coil operation
circuit
Check
box
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
Check sheet (1/2)
Refer to the following
Check item
Does the vehicle system have a fail-safe in case of a relay failure? ｐ1/1-1、ｐ1/2-4
Has it been confirmed by testing under actual load, actual circuit, and
actual condition?
Have load type, load current characteristic, and current value been
checked?
Isn't the applied contact current too small? (Small current is likely to
decrease the contact reliability.)
Has connecting load polarity been checked? ｐ2/4-11
Is the load likely to cause instant voltage drop? ｐ2/4-12
Isn't the applied contact voltage too high? (High voltage decreases
electrical life.)
Isn't applied coil voltage too high? (High voltage affects electrical life.) ｐ3/4-14
Isn't short pulse applied to coil? ｐ3/4-15
Isn't the switching frequency too high even including at abnormality? ｐ3/4-16
Doesn't switching continue for a long time? ｐ3/4-17
Does it switch under high temperature? ｐ3/4-18
Have precautions been checked for using of coil surge absorption
circuit?
Have you checked there is no sneak current or voltage to the relay coil? ｐ3/4-20
Is there stray capacitance between lead wires? ｐ3/4-21
Have precautions been checked for using of contact protective circuit? ｐ4/4-22
Is there a risk of dead short in the power supply? ｐ5/4-23
Is there a risk of short circuit in the power supply at load rejection? ｐ5/4-23
Is there a risk of insulation and breakdown voltage between contacts in
each pole when high voltage is applied to a twin relay?
Has hot start been considered? ｐ5/5-1
Is the ambient temperature within the range of use? Also, is the ambient
temperature characteristics considered?
Is the applied voltage below the maximum continuous applied voltage? ｐ5/5-3
Is there a risk of using PWM control? (PWM control requires careful
attention.)
Doesn't coil of twin relay operate at the same time? ｐ6/5-4
Hasn't the current continuously applied to coil over a long period? ｐ6/5-5
In case of relay operation by electric circuit, is the circuit designed in
consideration of mal-function?
Doesn't the surge voltage of relay cause mal-function or destruction of
transistor circuit?
When relay is applied to an electric circuit, has voltage drop caused by
other electric components on the circuit been considered?
page and item on
Page / Category Section
ｐ2/4-1
ｐ2/4-2～4-9
ｐ2/4-10
ｐ3/4-13
ｐ3/4-19
ｐ5/4-24
ｐ5/5-2
ｐ5/5-3
ｐ6/6-1、ｐ8/6-2
ｐ6/6-1、ｐ8/6-2
ｐ6/6-1、ｐ8/6-2
Page 25
Category
Contact
reliability
Contact
resistance
Operating sound
Mechanical
noise
Use
environmental
condition
Mounting
PCB mounting
Soldering
Storage,
transportation
Product
handling
Check
box
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
Check sheet (2/2)
Refer to the following
Check item
Have precautions been checked in the case of switching with both high
and low loads by the same contact?
Doesn't heat dissipation occur under low temperature? ｐ9/7-2
Has transient state of contact resistance been considered? ｐ9/8-1
Are contact voltage and current 6V 1A or higher? ｐ9/8-2
Are there any problems regarding operating sound of relay? ｐ9/9-1、ｐ9/9-2
Are there any problems regarding abnormal weak noise of relay? ｐ9/10-1、ｐ9/10-2
Is temperature, humidity, atomosphere pressure within the range of use? ｐ10/12-1
Have precautions been checked in the case of switching under high
humidity?
Is the ambient environment free from particles, dusts, sulfidizing gas,
organic gas?
Is the ambient environment free from silicon? ｐ10/12-3
Is the ambient environment free from high-field magnetic instruments
such as speaker?
Are the ambient vibration and shock below the relay's vibration and
impact characteristics? Also, is there no resonance after the relay is
Isn't there a risk of freezing and dewing of relay? ｐ9/7-2、ｐ10/12-7、ｐ
Isn't there a risk of water or oil adhesion? ｐ11/12-8
Doesn't vibration or shock cause poor connection between a relay and a
connector?
Have precautions been checked for operating of flux applying and
automatic soldering?
Have precautions been checked for cleaning operation of print board? ｐ13/15-1、ｐ15/15-2
Isn't glass shot performed for flux cleaning? (Particle of the glass may
get inside the relay and cause operation failure.)
Does significant warping of print board occur, which applies a force on a
relay teminal and changes the relay characteristics?
Isn't the unused terminal cut? (Applied force on terminal can change the
characteristics.)
Any strong forces such as terminal clinch are not applied at attaching. ｐ18/16-3
Aren't load, shock, or vibration which is out of the allowable range
applied during transportation?
Are temperature and humidity within the allowable range? ｐ18/17-2
Is the ambient atomosphere free from organic gas and sulfidizing gas? ｐ18/17-2
Aren't dropped or fallen tube packages used? ｐ18/18-1
page and item on
Page / Category Section
ｐ9/7-1
ｐ10/12-1
ｐ10/12-2
ｐ10/12-4
ｐ10/12-5、ｐ10/12-6
11/12-9
ｐ11/13-1
ｐ13/15-1、ｐ15/15-2
ｐ13/15-1、ｐ15/15-2
ｐ13/15-1、ｐ15/15-2
ｐ13/15-1、ｐ15/15-2
ｐ18/17-1
Page 26
Loading...