Reference Specification
Metal Terminal Monolithic Ceramic Capacitor
( KRM55 Series [Rat. Vol.: DC25V to DC100V] )
Product specifications in this catalog are as of May 2017, and are subject to change or
obsolescence without notice.
Please consult the approval sheet before ordering.Please read rating and Cautions first.
Reference only
Caution
■Storage
and Operation Conditions
1. The performance of chip monolithic ceramic capacitors may be affected by the storage conditions.
1-1. Store the capacitors in the following conditions:Room Temperature of +5°C to +40°C and a Relative Humidity
of 20% to 70%.
(1) Sunlight, dust, rapid temperature changes, corrosive gas atmosphere, or high temperature and humidity
conditions during storage may affect solderability and packaging performance. Therefore, please maintain
the storage temperature and humidity. Use the product within six months, as prolonged storage may cause
oxidation of the electrodes.
(2) Please confirm solderability before using after six months. Store the capacitors without opening the original bag.
Even if the storage period is short, do not exceed the specified atmospheric conditions.
1-2. Corrosive gas can react with the termination(external) electrodes or lead wires of capacitors, and result
in poor solderability. Do not store the capacitors in an atmosphere consisting of corrosive gas
(e.g., hydrogen sulfide, sulfur dioxide, chlorine, ammonia gas, etc.).
1-3. Due to moisture condensation caused by rapid humidity changes, or the photochemical change caused
by direct sunlight on the terminal electrodes and/or the resin/epoxy coatings, the solderability and electrical
performance may deteriorate. Do not store capacitors under direct sunlight or in high humidity conditions.
■Rating
1. Temperature Dependent Characteristics
1. The electrical characteristics of a capacitor can change with temperature.
1-1. For capacitors having larger temperature dependency, the capacitance may change with temperature changes.
The following actions are recommended in order to ensure suitable capacitance values.
(1) Select a suitable capacitance for the operating temperature range.
(2) The capacitance may change within the rated temperature. When you use a high dielectric constant type
capacitor in a circuit that needs a tight (narrow) capacitance tolerance (e.g., a time-constant circuit),
please carefully consider the temperature characteristics, and carefully confirm the various characteristics
in actual use conditions and the actual system.
2. Measurement of Capacitance
1. Measure capacitance with the voltage and frequency specified in the product specifications.
1-1. The output voltage of the measuring equipment may decrease occasionally when capacitance is high.
Please confirm whether a prescribed measured voltage is impressed to the capacitor.
1-2. The capacitance values of high dielectric constant type capacitors change depending on the AC voltage applied.
Please consider the AC voltage characteristics when selecting a capacitor to be used in an AC circuit.
3. Applied Voltage
1. Do not apply a voltage to the capacitor that exceeds the rated voltage as called out in the specifications.
1-1. Applied voltage between the terminals of a capacitor shall be less than or equal to the rated voltage.
(1) When AC voltage is superimposed on DC voltage, the zero-to-peak voltage shall not exceed the rated DC voltage.
When AC voltage or pulse voltage is applied, the peak-to-peak voltage shall not exceed the rated DC voltage.
(2) Abnormal voltages (surge voltage, static electricity, pulse voltage, etc.) shall not exceed the rated DC voltage.
Typical Voltage Applied to the DC Capacitor
DC Voltage
DC Voltage+AC
AC Voltage
Pulse Voltage
E
E
E
0
E
0
0
0
(E: Maximum possible applied voltage.)
1-2. Influence of over voltage
Over voltage that is applied to the capacitor may result in an electrical short circuit caused by the breakdown
of the internal dielectric layers. The time duration until breakdown depends on the applied voltage
and the ambient temperature.
2. Use a safety standard certified capacitor in a power supply input circuit (AC filter), as it is also necessary
to consider the withstand voltage and impulse withstand voltage defined for each device.
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Reference only
Caution
4. Type of Applied Voltage and Self-heating Temperature
1. Confirm the operating conditions to make sure that no large current is flowing into the capacitor due to the continuous
application of an AC voltage or pulse voltage. When a DC rated voltage product is used in an AC voltage circuit or a
pulse voltage circuit, the AC current or pulse current will flow into the capacitor; therefore check the self-heating condition.
Please confirm the surface temperature of the capacitor so that the temperature remains within the upper limits of the
operating temperature, including the rise in temperature due to self-heating. When the capacitor is used with a
high-frequency voltage or pulse voltage, heat may be generated by dielectric loss.
<Applicable to Rated Voltage of less than DC100V>
1-1. The load should be contained to the level such that when measuring at atmospheric temperature of 25℃, the product's
self-heating remains below 20℃ and the surface temperature of the capacitor in the actual circuit remains within the
maximum operating temperature.
<Applicable to Temperature Characteristic X7R, X7T beyond Rated Voltage of DC200V>
1-2. The load should be contained so that the self-heating of the capacitor body remains below 20°C, when measuring at
an ambient temperature of 25°C. In addition, use a K thermocouple of φ0.1mm with less heat capacity when
measuring, and measure in a condition where there is no effect from the radiant heat of other components or air flow
caused by convection. Excessive generation of heat may cause deterioration of the characteristics and reliability of the
capacitor. (Absolutely do not perform measurements while the cooling fan is operating, as an accurate measurement
may not be performed.)
5. DC Voltage and AC Voltage Characteristics
1. The capacitance value of a high dielectric constant type capacitor changes depending on the DC voltage applied.
Please consider the DC voltage characteristics when a capacitor is selected for use in a DC circuit.
1-1. The capacitance of ceramic capacitors may change sharply depending on the applied voltage (see figure).
Please confirm the following in order to secure the capacitance.
(1) Determine whether the capacitance change caused by the applied voltage is within the allowed range.
(2) In the DC voltage characteristics, the rate of capacitance change becomes larger as voltage increases, even if the
applied voltage is below the rated voltage. When a high dielectric constant type capacitor is used in a circuit that
requires a tight (narrow) capacitance tolerance (e.g., a time constant circuit), please carefully consider the voltage
characteristics, and confirm the various characteristics in actual operating conditions in an actual system.
2. The capacitance values of high dielectric constant type capacitors changes depending on the AC voltage applied.
Please consider the AC voltage characteristics when selecting a capacitor to be used in an AC circuit.
6. Capacitance Aging
1. The high dielectric constant type capacitors have the characteristic in which the capacitance value decreases with the
passage of time. When you use high dielectric constant type capacitors in a circuit that needs a tight (narrow) capacitance
tolerance (e.g., a time-constant circuit), please carefully consider the characteristics of these capacitors, such as their
aging, voltage, and temperature characteristics. In addition, check capacitors using your actual appliances at the intended
environment and operating conditions.
7. Vibration and Shock
1. Please confirm the kind of vibration and/or shock, its condition, and any generation of resonance.
Please mount the capacitor so as not to generate resonance, and do not allow any impact on the terminals.
2. Mechanical shock due to being dropped may cause damage or a crack in the dielectric material of the capacitor.
Do not use a dropped capacitor because the quality and reliability may be deteriorated.
Crack
Floor
3. When printed circuit boards are piled up or handled, the corner of another printed circuit board should not be allowed
to hit the capacitor, in order to avoid a crack or other damage to the capacitor.
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Reference only
Caution
■Soldering
and Mounting
1. Mounting Position
1. Confirm the best mounting position and direction that minimizes the stress imposed on the capacitor during flexing
or bending the printed circuit board.
1-1. Choose a mounting position that minimizes the stress imposed on the chip during flexing or bending of the board.
[Component Direction]
Locate chip horizontal to the direction in which stress acts.
[Chip Mounting Close to Board Separation Point]
It is effective to implement the following measures, to reduce stress in separating the board. It is best to implement all
of the following three measures; however, implement as many measures as possible to reduce stress.
Contents of Measures
Stress Level
(1) Turn the mounting direction of the component parallel
A>D
(1)
to the board separation surface.
(2) Add slits in the board separation part.
A>B
D
A
(3) Keep the mounting position of the component away
Slit
A>C
(3)
from the board separation surface.
[Mounting Capacitors Near Screw Holes]
When a capacitor is mounted near a screw hole, it may be affected by the board deflection that occurs during the
tightening of the screw. Mount the capacitor in a position as far away from the screw holes as possible.
Perforation
B
C
Screw Hole
Recommended
2.
1.
2.
3.
4.
5.
6.
7.
Information before Mounting
Do not re-use capacitors that were removed from the equipment.
Confirm capacitance characteristics under actual applied voltage.
Confirm the mechanical stress under actual process and equipment use.
Confirm the rated capacitance, rated voltage and other electrical characteristics before assembly.
Prior to use, confirm the solderability of capacitors that were in long-term storage.
Prior to measuring capacitance, carry out a heat treatment for capacitors that were in long-term storage.
The use of Sn-Zn based solder will deteriorate the reliability of the MLCC.
Please contact our sales representative or product engineers on the use of Sn-Zn based solder in advance.
8. We have also produced a DVD which shows a summary of our opinions, regarding the precautions for mounting.
Please contact our sales representative to request the DVD.
3. Maintenance of the Mounting (pick and place) Machine
1. Make sure that the following excessive forces are not applied to the capacitors.
1-1. In mounting the capacitors on the printed circuit board, any bending force against them shall be kept to a minimum
to prevent them from any bending damage or cracking. Please take into account the following precautions and
recommendations for use in your process.
(1) Adjust the lowest position of the pickup nozzle so as not to bend the printed circuit board.
(2) Adjust the nozzle pressure within a static load of 1N to 3N during mounting.
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Reference only
Caution
2. Dirt particles and dust accumulated between the suction nozzle and the cylinder inner wall prevent the nozzle from moving
moving smoothly. This imposes greater force upon the chip during mounting, causing cracked chips. Also, the locating
claw, when worn out, imposes uneven forces on the chip when positioning, causing cracked chips.
The suction nozzle and the locating claw must be maintained, checked, and replaced periodically.
4-1. Reflow Soldering
1. When sudden heat is applied to the components, the
mechanical strength of the components will decrease
because a sudden temperature change causes deformation
inside the components. In order to prevent mechanical damage
to the components, preheating is required for both the
components and the PCB. Preheating conditions are shown
in table 1. It is required to keep the temperature differential
between the solder and the components surface (ΔT) as small
as possible.
2. Solderability of tin plating termination chips might be
deteriorated when a low temperature soldering profile where
the peak solder temperature is below the melting point of tin
is used. Please confirm the solderability of tin plated
termination chips before use.
3. When components are immersed in solvent after mounting,
be sure to maintain the temperature difference (ΔT) between
the component and the solvent within the range shown in table 1.
Table 1
[Standard Conditions for Reflow Soldering]
Temperature (℃)
Peak Temperature
220℃(200℃)
190℃(170℃)
170℃(150℃)
150℃(130℃)
ΔＴ
Reflow
Soldering
Gradual
Cooling
Preheating
Time
60 to 120 seconds
30 to 60 seconds
Temperature
Incase of Lead Free Solder
( ): In case of Pb-Sn Solder
Temperature (℃)
Peak Temperature
Vapor Reflow
Soldering
ΔＴ
Gradual
Cooling
Part Number
K□□21 / K□□31
K□□55
Temperature Differential
ΔT≦190°C
ΔT≦130°C
190℃(170℃)
170℃(150℃)
150℃(130℃)
Preheating
Recommended Conditions
Pb-Sn Solder
Reflow
Peak Temperature 230 to 250°C
Atmosphere
Air
Vapor Reflow
230 to 240°C
Saturated vapor
of inactive solvent
Lead Free
Solder
240 to 260°C
Air or N2
Time
60 to 120 seconds 20 seconds max.
[Allowable Reflow Soldering Temperature and Time]
Soldering Temperature
(℃)
Pb-Sn Solder: Sn-37Pb
Lead Free Solder: Sn-3.0Ag-0.5Cu
280
270
260
250
240
230
90
120
Soldering Time (sec.)
In the case of repeated soldering, the accumulated
soldering time must be within the range shown above.
220
0
30
60
4. Optimum Solder Amount for Reflow Soldering
4-1. If solder paste is excessive, solder between a chip and a
metal terminal melts. This causes the chip to move and
come off.
4-2. If solder paste is too little, it causes a lack of adhesive
strength on the metal terminal and the capacitor comes off.
4-3. Please make sure that solder is smoothly applied higher
than 0.3mm and lower than the level of the bottom of the
chip.
Inverting the PCB
Make sure not to impose any abnormal mechanical shocks to the PCB.
4-2. Flow Soldering
1. Do not apply flow soldering.
0.3mm min.
In section
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