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Precautions for Use (Particulars
common to all kinds of product types) |
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The types and the specifications in this catalog
are typical ones. Before use, please make sure of specifications
and precautions in use with the contents of specifications for supply
or ask our sales offices for the specifications. |
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Particulars common to all kinds
of product types |
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Soldering |
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Soldering shall be performed within the specified
temperature, time and number of times for each component. If the
components are heated to high temperature for a long time, the colors
and characteristics may change, and disconnection, etc. may occur. |
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After soldering, keep the component from stress
until it is cooled down. |
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After soldering, be sure not to give any mechanical
stress on the terminal section by warping of the printed board,
etc. |
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When repairing chip resistors by a soldering
iron, pay attention to the following points.
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Work under the prescribed temperature
of the iron-tip by the individual product type. |
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Preheat component and P.W.B. as much as
possible. |
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Work so that the tip of the soldering
iron does not touch direct the body of a component or terminal
electrodes. |
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If you put the component up with tweezers,
be sure not to add damage to the protection coats or electrodes. |
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After the repair of film resistors, washing
of flux should be done after they get well cooled. The remnants
of ionic substances may degrade resistances to humidity/corrosion.
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Instructions
in case of mounting with lead - free solder |
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There is a possibility of solder temperature
rising higher than usual in the soldering process than eutectic
solder depending on a solder composition. Please use it after checking
beforehand that there is no problem under actual conditions. |
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In case that the parts are inserted to the double-sided
P.W.B. with through hole, check in advance with the actual P.W.B.
before inserting because lift-off phenomenon may cause degradation
of the strength of soldering connection when using lead free solder. |
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Please use them after checking the influence
of flux remnants contained in the solder to components. Confirm
the influence in advance of the flux contained in the lead-free
solder by the examination of reliability. |
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Insertion
and mounting |
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The coating is covered to ensure the performance
of components. Do not give any damage or excessive impacts on the
products with pliers or pincette, or improper adjustment of an automatic
mounter. They may cause characteristic changes, disconnection, crack,
etc. |
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Do not use the components dropped at the time
of mounting or ones removed from the printed boards. |
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Make sure to avoid heat radiation generated
by other heated components. |
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In case boards are sealed by molding or coated
after mounting components, consult with us beforehand. |
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Take care not to have electrostatics applied
to the components when assembling. |
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Check and adjust in advance "height positioning
in vertical direction", "pressure of chucking" and
"abrasion of positioning nails" when you use them and
adjust the position in parallel direction after adsorbing chip components
by an automatic mounter. Insufficient adjustment of the automatic
mounter may cause large stress to the components, break cracks,
bad mounting position, etc. |
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If the nozzle of the automatic mounter is too
low, it causes the force which makes the parts hit to P.W.B., the
hit marks on the protection coat of the parts surface to bring about
change in resistance and deterioration
of the performance, and the break and cracks of the components.
Mount the components by slowing down the nozzle speed or by correcting
the warp of P.W.B. right before mounting. |
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Resistance values of resistors/sensors in film
types change by excessive voltage of static electricity. Take care
that static electricity (ESD), which occur in the assembly process
(automatic mounters/inspection monitors/human bodies, etc.), or
at transportation of the components, are not applied to the components. |
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Ionic impurities such as perspiration and salt
should not be put onto the outer coat or terminals of the parts.
It may cause degradation of resistances to humidity/corrosion. |
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Resistance to pulse |
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In case of the circuits where excessive overload (single
pulse, repeated pulse) like pulse or surge etc. are applied to,
there are fears of the degradation of performance (disconnection,
resistance change, etc.), decline of reliability if voltage/current/power
over than ratings are applied. Confirm sufficiently with the actual
circuit considering the dispersion of constant of other components.
Consult with us in advance if you need the data of anti-pulse characteristics. |
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Storage |
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Store the components at the less dusty places avoiding high
temperature/humidity, condensation, direct sunray, heat, sea breeze,
corrosive gas(SO2, H2S, chlorine, acid, alkali, NH3 etc.), oil mist
from lubricating oil. Use desiccant as occasion demands. |
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Please inquire of us about the storage term of components. |
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Storage
of products with Pb-free terminations. |
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Pay much more attention to storage condition
(temperature, humidity) for products with Pb-free terminations than
those with Sn/Pb terminations.
If they are stored in bad condition, terminations and solderability
may be deteriorated in shorter time than it happens to products
with Sn/Pb terminations.
The storage condition and period vary depending on product type.
Please contact us for further details. |
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Washing |
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Consider not to remain ionic substances contained
in solder flux, after washing of soldering. Ionic impurities may
deteriorate resistances to humidity and corrosion of the components
especially for film resistors. Especially when non-washing-soldering,
water washing or water-soluble detergent is used, it is essential
to confirm reliability of the components before use. Particularly
in lead-free soldering, much of ionic substances may be contained.
Use RMA soldering or flux, or wash them well enough. Thorough washing
shall be done in case that ionic substances like perspiration ,
salt, etc. are attached. Ionic substances may not be removed totally
in case of insufficient care of washing fluid. Consult with us in
advance when you use detergents other than alcohol or wash by acid/alkali. |
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A resonance phenomenon may destruct the components
by an ultrasonic cleaning. Also confirm sufficiently on the actual
board as the surface electrodes may be damaged by a strong water
pressure cleaning. |
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Sulfuration |
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The resistance values of the components that
use silver electrodes, may increase when the conductors are changed
into insulators by a sulfuration phenomenon. One of the causes is
the sulfur contained as impurities in sulfide gas (H2S, SO3,etc.)
or in sulfide compound that are attached to the components by being
included in oil mist. Take measures to sulfuration in case of using
under those environments. |
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How to
use for improving reliability |
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The smaller the impressed power against rated
power is, the smaller the power stress becomes, which leads to the
decline of the trouble rate of resistors. The trouble rate can be
smaller, if machines are so designed that the ambient temperature
of the resistors may be close to the normal temperature.
In case of using for the purpose requiring high reliability, consider
thoroughly fail-safe designing. Keep the system security by preparing
protecting or diffuse circuits, etc. not to become unsafe in the
single trouble of this component. |
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General |
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For basic particulars for cautions, refer to EIAJ "RCR-1001
Safety application guide for electronic parts", the technical
report is issued by Electronic Information Technical Industry Association. |
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Particulars common to chip components |
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Warping
of printed boards, which is caused by heat, gives stress directly
to components when boards are cooled down. Be careful of the following
particulars: |
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The arrangement of electrodes of chip components
should go along with the fiber direction (vertical direction) of
printed boards. |
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The component made of ceramic as its base may
cause cracks on the solder at the connecting section(solder fillet)
due to the difference in heat expansion coefficient from the mounting
P.W.B. if heat stress like heat shock etc. are continuously given.
The occurrence of crack is affected depending on size of the pad
for mounting, solder amount, heat radiation volume of mounting P.W.B.,
etc., so pay special attention when designing especially for the
big types(5.0 2.5mm or larger). |
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The components or electrodes may be destructed
by much stress when the components are placed near the dividing
groove of the P.W.B. Please refer to the following figure and mount
them to the positions and directions of small stress. |
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In case of placing the components near the surrounding
of P.W.B. or connectors, be sure not to give any stress to the components
at assembling equipment or at insertion/extraction of connectors. |
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When using a back-up pin to mount the components,
those on the opposite side of P.W.B. may be damaged unless they
are placed properly. In case of poulticing adhere by using a dispenser,
take care not to touch the printed board when setting up the bottom
dead center of the dispenser. |
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The difference in sizes of right and left pads
causes the difference in amounts of right and left solder, then
stress moves to one side at the time of cooling solder to make the
chip stand up or get stress. In order to prevent such abnormalities,
the sizes of the pads must be corrected to be equal on both sides
by using solder resist, etc. |
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When the components are placed near bigger parts
compared with itself, stress is pulled to the bigger components
side at the time of solder stiffening, so take the positioning and
directions into consideration. |
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Particulars common to leaded components |
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To avoid
mechanical force to components, pay attention to following the particulars: |
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Be careful not to create resonance by vibration. |
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The bodies of the leaded components should be free from
twisting or bending. |
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The bodies of the large components should be firmly fixed. |
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When the lead wires need to be bent, try to make larger
radius of curve in order to avoid excessive force at the foot of
the terminals. Excessive force, if applied, may damage the components
by desorption of the caps fitted on the ceramic cores. |
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When cutting or clinching the lead wires on the mounter,
be careful not to apply excessive forces to them. |
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Rated Power |
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The maximum value of power which can be continuously loaded
to a resistor at a rated ambient temperature. Please confirm beforehand
that there is such a case in a network resistor that rated power
per package as well as per element is specified. |
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Rated Voltage |
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The maximum value of D.C. voltage or A.C. voltageicommercial
frequency effective valuejcapable of being applied continuously
to a resistor at the rated ambient temperature.
Rated voltage shall be calculated from the following formula. |
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However, it shall not exceed the maximum working voltage. |
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Critical
Resistance Value |
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The maximum nominal resistance value at which the rated
power can be loaded without exceeding the maximum working voltage.
The rated voltage is equal to the maximum working voltage in the
critical resistance value. |
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Maximum
Working Voltage |
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The maximum value of D.C. voltage or A.C. voltage (commercial
frequency effective value) capable of being applied continuously
to a resistor or a resistor element. However, the maximum value
of the applicable voltage is the rated voltage at the critical resistance
value or lower. |
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Maximum Overload Voltage |
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The maximum value of voltage capable of being
applied to a resistor for five seconds in the overload test(. JIS
C 5201-1 4.13). Typically the applied voltage in the short time
overload test shall be 2.5 times larger than the rated voltage.
However, it shall not exceed the maximum overload voltage. |
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Dielectric
Withstanding Voltage |
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A.C. voltage (commercial frequency effective value) that
can be applied to a designated spot between the electrode and the
outer coating for a minute in the dielectric withstanding voltage
test. (JIS C 5201-1 4.7) |
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Rated Ambient
Temperature |
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The maximum ambient temperature at which a resistor is capable
of being used continuously with the prescribed rated load (power).
The rated ambient temperature refers to the temperature around the
resistor inside the equipment, not to the air-temperature outside
the equipment. |
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Derating
Curve |
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The curve that expresses the relation between the ambient
temperature and the maximum value of continuously loadable power
at its temperature, which is generally expressed in percentage. |
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Temperature
Coefficient of Resistance(T.C.R.) |
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The rate of change in resistance value per 1
in the prescribed temperature within the range of resistor operating
temperature shall be expressed in the following formula: |
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Application Notes
Brush up your circuit
Basic Knowledge
