Question 1

Open Mode and the“1210 Rule” (1): What is TDK "Open Mode" capacitor?

Accepted Answer

A. In response to the market demand for a reduced risk MLCC with respect to board flexure cracks, TDK introduced a unique inner electrode design that compensates for the typical crack path induced by PCB bending. This "Y" crack has been well documented as a signature crack for board flexure [1] and has been a leading cause of MLCC failures in the market for years.

Excessive board bending during PCB manufacturing or final assembly is common, and the brittle nature of ceramic components is especially prone to damage after soldered to the PCB. TDK has responded to this problem with the Open Mode MLCC for applications where flex cracking is a high concern (see illustration in Figure 1).

Figure 1

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Question 2

Open Mode and the“1210 Rule” (2): How can an Open Mode capacitor reduce a short risk by board flexure?

Accepted Answer

A. Bending a PCB board after solder will transfer stress to the populated components. If the stress exceeds the breaking strength of the ceramic capacitor a crack will occur. Furthermore, if the stress is large enough a displacement in the component may occur which could result in a shorted part as an electrode contacts a counter electrode (see Figure 1).

Figure 1

The active area utilized in MLCC is reduced due to the shortened electrode layers which prevent the counter electrode from being in proximity of the potential crack. In the event of a crack the propagation will not cross a counter electrode, thus minimizing the likelihood of a short. Of course this reduction in active area compromises the capacitance available.

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Question 3

Open Mode and the“1210 Rule” (3): How can I tell Open Mode design from the TDK part numbers?

Accepted Answer

A. TDK uses a letter in the part number to indicate Open Mode.
Please see catalog part number description on Search by Part No. of TDK MLCC website for the designators used in your application.

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Question 4

Open Mode and the“1210 Rule” (4): Why is Open Mode of MLCCs (Multilayer Ceramic Capacitors) not offered in case sizes smaller than 0805 (C2012)?

Accepted Answer

A. Physics begin to work in the user's favor as the size of the ceramic component is reduced. Just as it is more difficult to break a small brick as opposed to a large brick, smaller MLCCs offer strength robustness that no longer warrants the Open Mode design. As an example, typical board flexure strength as a function of case size is shown below (Figure 1 & Figure 2). Smaller geometries increase the strength of the MLCC well beyond the 2mm EIA-198 industry specification. Open Mode designs in these geometries are considered overkill.

Figure 1, Flex Strength vs Case Size

Figure 2, Flex Strength vs Thickness

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Question 5

Open Mode and the“1210 Rule” (5): What is the "1210 Rule" of MLCCs (Multilayer Ceramic Capacitors)?

Accepted Answer

A. Many design engineers utilize a basic rule of thumb that prohibits the use of any 1210 or larger case sized MLCC for fear of increased risk of failed components due to board flexure. The 1210 Rule addresses the significance of larger components but it fails to address the significance of thicker components.

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Question 6

Open Mode and the“1210 Rule” (6): How can I justify using a large size despite the "1210 Rule" of MLCCs (Multilayer Ceramic Capacitors)?

Accepted Answer

A. The strength of brittle materials is often measured by Modulus of Rupture. The MOR of a ceramic body is function of its geometry - proportional to its width and thickness, but inversely proportional to its length. Thus longer MLCCs with the same thickness will result in lower bending strength, however this loss of strength can be offset by utilizing a thicker component.

1210 and larger components are offered in a variety of thicknesses, many greater than 2mm. Components of this size are often more robust to board flexure stresses than 1206 or 0805 sized components, and well exceed the 2mm bending requirement.

Not using these higher value components severely limits the designer engineer’s capacitor options - especially in the case of higher capacitance values for Tantalum replacement application.

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Question 7

Open Mode and the“1210 Rule” (7): Where should TDK Open Mode capacitors be used?

Accepted Answer

A. Examples of high risk circuit applications would include:

All direct battery line applications.
Any circuit > 20A
Regions of historic board flexure or high risk/problem areas.

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Question 8

Open Mode and the“1210 Rule” (8): How can I find the latest cap ranges available in Open Mode?

Accepted Answer

A. Please check the latest capacity range of the MLCC product series from the product site.

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Question 9

No Tin Whisker Risk in TDK MLCCs (1): What material is used for the internal electrodes and terminal electrodes?

Accepted Answer

A. TDK produces MLCCs with base metal (Ni) inner electrodes and corresponding Cu outer (or terminal) electrodes. This termination is electroplated to protect the component from solder heat leaching and enhance solderability. A Ni barrier plating layer provides solder heat protection and a Pb free Sn overplate (matte finish) provides optimal solderability.

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Question 10

No Tin Whisker Risk in TDK MLCCs (2): What bath compositions are used for electroplating process?

Accepted Answer

A. The bath composition is typical Watts Nickel and typical Methyl Sulfonic Acid Tin (slightly acidic, pH = 4). Our plating chemistry is Pb free and provides 100% Ni deposit at 1.25 +/- 0.25um (～2um grain size) and 100% Sn deposit at 4.0 =/- 1.0um (～5um grain size).

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Question 11

No Tin Whisker Risk in TDK MLCCs (3): How does TDK ensure the tin finish will not promote whisker growth?

Accepted Answer

A. Methyl Sulfonic tin is characterized as a matte finish in the plating industry and contains no organic brighteners. Bright finishes contain organic additives that may encourage tin whisker growth. Furthermore, after electroplating a heat treatment/annealing process (150C / 60min) is employed to relieve any residual plating stress on the component. Small grain size and annealed stress relief is a key point for whisker prevention during component manufacturing.

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Question 12

No Tin Whisker Risk in TDK MLCCs (4): How does TDK test for Sn whisker?

Accepted Answer

A. There currently is no industry standard for MLCC Sn Whisker testing. Sn whisker testing is not a part of standard internal qualification test plans. TDK has tested per the IC standard as described in JESD22A121.

TDK MLCCs are RoHS compliant (Pb free). Sn overcoating is matte finish.

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Question 13

Data on the electrical characteristics of products with Y5V characteristics is needed when looking for a replacement with Y5V characteristics that TDK no longer manufactures. What needs to be done?

Accepted Answer

A. Products with X5R or X7R characteristics are recommended replacements for products with Y5V characteristics. X5R and X7R electrical characteristics are far superior to those of Y5V so we believe that, as long as the shape, rated voltage, and capacitance are the same, there is no need to make direct comparisons of electrical characteristics. Therefore, no data on products with Y5V characteristics has been released. Below are examples of comparisons of Y5V and X7R temperature characteristics and DC bias characteristics.

Comparison of temperature characteristics

C1608Y5V1H104Z

C1608X7R1H104K

Comparison of DC bias characteristics

C1608Y5V1H104Z

C1608X7R1H104K

Materials with Y5V characteristics have a higher relative dielectric constant than materials with X5R and X7R characteristics, and can be used to manufacture products with greater capacitance. However, because their capacitance is greatly affected by changes in temperature and voltage, their operating temperatures and applications limited them to general indoor appliances, etc. On the other hand, materials with X5R and X7R characteristics show less effect on capacitance from changes in temperature and voltage as well as excellent characteristics so they can be used for a wide range of applications from communication devices to automotive use.
In order to meet market demands for high capacitance, the capacitance of products with X5R and X7R characteristics has been enhanced through improvements in material technology and various elemental technologies. Furthermore, they sufficiently comply with capacitance ranges that only Y5V characteristics could comply with in the past.

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Question 14

How can a meter supply a different measured voltage than what is set when measuring high capacitance MLCCs (Multilayer Ceramic Capacitors)?

Accepted Answer

A. Capacitors interrupt direct current and let alternating current pass. For electronic devices that run on DC voltage, elements of an alternating-current become noise that makes operation unstable. As a countermeasure, capacitors are connected so as to allow the AC elements to pass through to the ground. The electronic device operates properly because only the necessary DC components are supplied.

Unnecessary signals (noise) are removed and necessary signals remain.

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Question 15

Measurement tips for high capacitance MLCCs (Multilayer Ceramic Capacitors) (1): Why does the measured capacitance sometimes read low?

Accepted Answer

A. When measuring capacitors, it is important to understand the difference between the true value, effective value, and indicated value. The true value is the value of the capacitor if it was an ideal component with no inductive and resistive elements. The effective value is the sum of the components real and reactive vectors, and is frequency dependent. The indicated value is the value displayed by the measurement equipment, and subject to measurement inaccuracies.

When measuring high capacitance value components, the voltage level set at the meter, the indicated value, may not necessarily be equal to the voltage level delivered across the DUT, the effective value.

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Question 16

Measurement tips for high capacitance MLCCs (Multilayer Ceramic Capacitors) (2): What voltage and frequency should I apply to the capacitor?

Accepted Answer

A. MLCC capacitors > 10μF are considered high capacitance. Improvements in manufacturing technology have allowed ceramic capacitor manufacturers to build higher capacitance parts approaching tantalum and electrolytic values. These “high value” MLCC’s are specified under the same conditions as tantalum capacitors. The measurement voltage should be 0.5 Vrms and measurement frequency should be 120Hz. The following table summarizes the measurement conditions.

Capacitance	AC Voltage	Frequency
C ≤ 1000pF	1.0 ± 0.2 Vrms	1MHz ± 10%
1000pF < C ≤10μF	1.0 ± 0.2 Vrms	1kHz ± 10%
C > 10μF	0.5 ± 0.2 Vrms	120 Hz ± 10%

Table 1: Measurement Conditions per TDK general specification.

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Question 17

Measurement tips for high capacitance MLCCs (Multilayer Ceramic Capacitors) (3): How can I confirm that my measuring voltage is correct?

Accepted Answer

A. The easiest method to verify voltage is by measuring the AC voltage (Vrms) across the capacitor while the capacitor is being measured by the instrument (Fig.1).

If the measured voltage is below the lower limit requirement of 0.8 Vrms while the capacitor measurement is being made, low capacitance may be observed. Some capacitance meters such as the HP4284A have Voltage and Current Level Monitors. (Fig.2). When these functions are “ON”, the voltage level across the DUT, or the current through the DUT will be displayed directly on the instrument display, eliminating the need for connecting the voltmeter. It is important to understand that the voltage delivered to the DUT can be very different from the set oscillator voltage level.

Fig. 1: Verification of VAC

Fig. 2: Voltage and Current level monitors on the HP4284A

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Question 18

Measurement tips for high capacitance MLCCs (Multilayer Ceramic Capacitors) (4): How can a meter supply a different measured voltage than what is set?

Accepted Answer

A. The impedance of a capacitor can affect the capacitance measurement read from certain cap meters. The impedance (Z) formula for a capacitor is as follows:

Z（Ω）=R+j（-1/ωC）where ω=2πf （formula 1）

Consequently, the frequency (f) and capacitance (C) will effect the impedance value for the device under test (capacitor). As capacitance and frequency increase, the impedance of the capacitor decreases. The cap meter’s impedance should switch to a lower range to compensate for the lower impedance of the capacitor. Some cap meters have several impedance settings to adequately compensate for different capacitor impedances. However, not all cap meters are able to switch to appropriate lower impedance values. As a result, inaccurate capacitance readings can occur. In other words, a cap meter’s fixed high impedance can cause lower capacitance measurements by not allowing the full voltage setting to reach the capacitor.

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Question 19

Measurement tips for high capacitance MLCCs (Multilayer Ceramic Capacitors) (5): What is the recommended meter for measuring?

Accepted Answer

A. For accurate high cap measurements, the recommended meters are the HP4284A, HP4278A, or equivalent.

The HP4284A with the high power option (option 001) increases the rms source current level from 10 mArms to 100 mArms. With a higher current range, the meter has more power to maintain the rms voltage level applied to the capacitor. The HP4284A also has Voltage and Current Level Monitors which show the actual voltage and current levels seen at the capacitor. One drawback from using the HP4284A is extended measurement time. The HP4284A uses a feedback configuration with the level monitor to maintain the full rms levels.

Measurement time for the HP4284A can be calculated from the following formula:

[(meas_timeshort) + (～ 115msec.)] x n (Formula 2)

where n = 2 to 6.

If measurement speed is a greater concern than accuracy, the HP4278A is recommended. This meter does not have the ALC function or the Voltage and Current Level Monitors but AC Voltage can still be verified by using a voltmeter. The HP4278A is an earlier version of the HP4284A and is sometimes referred to as a “production “ meter due to the faster measurement speed.

The important point is that the meter must be able to supply the correct voltage to the capacitor. This can be accomplished either by switching to a low output impedance range in order to compensate for the low impedance of high capacitance ceramic capacitors, or by having a feature which automatically maintains the test level at the device under test.

Further, the HP4284 has a feature known as Automatic Level Control (ALC). By activating this function, the set voltage level can be held constant at the DUT. When measuring high capacitance ceramic capacitors with this instrument, make sure that the ALC feature is “ON” (Fig.1-2). Failing to turn this function on can result in capacitance readings that are mistakenly read low.

Fig. 1: Setting ALC On

Fig. 2: ALC on indicator.

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Question 20

Measurement tips for high capacitance MLCCs (Multilayer Ceramic Capacitors) (6): What should I do if the capacitance measurement results are outside of the specifications on the low side?

Accepted Answer

A.

Confirm that the cap meter's voltage and frequency settings are correct (See Table 1 unless otherwise specified by the manufacturer).
Test the capacitor with a voltmeter in conjunction with the cap meter in order to determine if the actual voltage at the component meets the 1.0 ± 0.2 Vrms requirement.
If the instrument has the ALC or equivalent function, make sure that it is on.
Refer to the cap meter's manual to determine what impedance settings are possible and if the meter is capable of automatically switching the settings to compensate for the impedance of the capacitor.

Capacitance	AC Voltage	Frequency
C ≤ 1000pF	1.0 ± 0.2 Vrms	1MHz ± 10%
1000pF < C ≤ 10μF	1.0 ± 0.2 Vrms	1kHz ± 10%
C > 10μF	0.5 ± 0.2 Vrms	120 Hz ± 10%

Table 1: Measurement Conditions per TDK general specification.

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Question 21

Measurement tips for high capacitance MLCCs (Multilayer Ceramic Capacitors) (7): How much can the drop of measured voltage really affect the capacitance measurement?

Accepted Answer

A. As capacitance and frequency increase, the impedance of the capacitor decreases. To further illustrate this point, the following example mathematically shows how the impedance of the capacitor affects the actual voltage seen across the capacitor.

The capacitor (C3216Y5V1A106Z) is tested using both the HP 4263B cap meter and the HP4278A cap meter. Substituting a frequency of 1kHz and capacitance of 10 µF into Formula 1 yields a capacitor impedance of approximately 16 Ω.

When 1.0 Vrms is applied from the test equipment to the capacitor, the voltage is divided between the meter impedance and the capacitor impedance. The impedance of the HP4263B remains at 100 Ω(Fig.1) but the impedance of the HP4278A changes to 1.5 Ω for the calculated capacitor impedance (Fig.2). The result is that for the HP4263B the majority of the applied voltage is dropped across the cap meter impedance, while the HP4278A enables the capacitor to receive most of the voltage. The outcome is that the HP4263B will show an indicated value that is lower than the true value

Setting the OSC voltage of a test meter to 1.0Vrms does not guarantee that the full-applied voltage is delivered across the capacitor. It is not surprising to find that the voltage across the capacitor is around 10% of the set value. The following graph shows how a lower VAC effects the measured capacitance (Fig.3).

Fig. 5: HP4263B Impedance.

Fig. 6: HP4278A Impedance.

Fig. 7:Capacitance vs. AC Voltage

The following pictures illustrate the difference between ALC on and off. With the ALC function off, the actual voltage across the capacitor is approximately 10% of the 1.0Vrms set voltage. With the ALC on, the voltage across the capacitor is almost 100% of the set voltage. The HP4284A has voltage and current level monitors, but the actual voltage also can be verified using a voltmeter.

Automatic level COntrol (ALC) Function of HP4284A Capacitance Meter

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Question 22

How to measure capacitors/Test a Capacitors  (1): How do I correctly measure capacitance and dissipation factor?

Accepted Answer

A. The key to measure the capacitance and dissipation factor correctly is the meter settings (see Table 1).

Class Type	Capacitance	Frequency	Voltage
Class I	1ꯠpF and under	1MHz ± 10%	0.5 ～ 5 Vrms
Class I	Over 1ꯠpF	1kHz ± 10%	0.5 ～ 5 Vrms
Class II	10uF and under	1kHz ± 10%	1.0 ± 0.2 Vrms
Class II	Over 10uF	120Hz ± 20%	0.5 ± 0.2 Vrms

Table 1: Frequency and voltage settings for different capacitance range and class types.

The voltage settings are very critical for high capacitance capacitors. For some cap meters, the applied voltage to the test component is insufficient and thus the capacitance reads low.

The frequency settings are also important. Since capacitance changes with frequency, industry standards specify the test frequency at 1MHz, 1kHz, or 120Hz (see Table 1).

The recognition of the aging phenomenon for EIA class II capacitors is also important. For class II materials, capacitance decreases with Time1. Therefore, an industry convention has been accepted that states the capacitance shall be within tolerance at 1000 hours since the time of the last heat (TOLH)2.

TDK MLCC Application Note, “What is the Capacitance of this Capacitor?”, S. Maloy. (1999)
IEC-384-9 (1988), Appendix A

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Question 23

How to measure capacitors/Test a Capacitors  (2): Why is it necessary to measure capacitance at different test frequency/voltages depending on the capacitance range?

Accepted Answer

A. The frequency settings for the meter are mainly depended on the parasitic of the component. In order to achieve more accurate reading of the component, measuring frequencies are directed away from the Self-Resonance Frequency (SRF) of the component. Industry users set the standards at different frequency points depending on the capacitance value (see Table 1). The capacitance over 10uF was considered in the range of Tantalum capacitors. Therefore, as the ceramic capacitance range began to increase into the Tantalum capacitor range, the industry adopted the frequency standard for Tantalum measurements into ceramic capacitors.

The applied voltage is also depended on the capacitance of the capacitor. Generally, the 10uF and under have applied voltage of 1.0 ± 0.2 Vrms. But over 10uF, the applied voltage is 0.5 ± 0.1 Vrms. High capacitance capacitors have very low impedance, therefore to supply enough current to make the measurement, the power supply needs more current than that supplied at 1.0 ± 0.2 Vrms. Therefore, by lowering the applied voltage, the power supply will be able to supply enough current to measure the high capacitance capacitor accurately.

Class Type	Capacitance	Frequency	Voltage
Class I	1ꯠpF and under	1MHz ± 10%	0.5 ～ 5 Vrms
Class I	Over 1ꯠpF	1kHz ± 10%	0.5 ～ 5 Vrms
Class II	10uF and under	1kHz ± 10%	1.0 ± 0.2 Vrms
Class II	Over 10uF	120Hz ± 20%	0.5 ± 0.2 Vrms

Table 1: Frequency and voltage settings for different capacitance range and class types.

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Question 24

How to measure capacitors/Test a Capacitors  (3): What is the difference between Cp and Cs of capacitance?

Accepted Answer

A. An impedance analyzer can measure the capacitance in parallel known as Cp or in series known as Cs. The circuit model will be depending on the value of capacitance of the capacitor (see Figure 1).

When C is small and impedance is high, parallel impedance between C and Rp will become significantly higher than Rs. Thus the meter setting for measuring capacitance should be Cp. When C is large and impedance is small, parallel impedance for C and Rp is not as significant. Therefore, Cs should be used for the meter setting to measure capacitance. A good rule of thumb to select the impedance setting is to use Cp for capacitor impedance values greater than 10kΩ and Cs for less than 10Ω.

Figure1: Impedance equivalment circuit

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Question 25

How to measure capacitors/Test a Capacitors  (4): What functions should I look for when choosing a meter for measuring capacitance of MLCCs (Multilayer Ceramic Capacitors)?

Accepted Answer

A. The most important function of the meter is applied voltage and measurement frequency. Make sure the voltage and frequency ranges are sufficient for the settings listed in Table 1. Be aware that the meter’s impedance can become a significant issue with high-capacitance MLCCs. It may be necessary to choose a meter with a switchable internally impedance, if high-capacitance MLCCs are measured.

Some meters offer a level monitor function. This function can monitor the output level of OSC level or dc bias.

Measurement accuracy, speed, and capacitance range of the meter are also important. The measurement accuracy should be within 0.07% accuracy for capacitance measurement. Make sure the meter have the adequate time to measure the capacitor especially for some high speed measurement machines. Make sure the capacitor to be measured is within the capacitance range of the meter.

Class Type	Capacitance	Frequency	Voltage
Class I	1ꯠpF and under	1MHz ± 10%	0.5 ～ 5 Vrms
Class I	Over 1ꯠpF	1kHz ± 10%	0.5 ～ 5 Vrms
Class II	10uF and under	1kHz ± 10%	1.0 ± 0.2 Vrms
Class II	Over 10uF	120Hz ± 20%	0.5 ± 0.2 Vrms

Table 1: Frequency and voltage settings for different capacitance range and class types.

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Question 26

How to measure capacitors/Test a Capacitors  (5): What is “stray capacitance” of a meter?

Accepted Answer

A. Stray capacitance is a type of measurement error defined as capacitance between the connections of a fixture and/or tip of the tweezers. When the fixture is open, there is some stray capacitance added to the measurement of the capacitor. However, if open compensation is properly performed, the stray capacitance generated by the fixture can be accurately compensated.

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Question 27

How to measure capacitors/Test a Capacitors  (6): What is compensation of measurement errors&#44 and why is it necessary?

Accepted Answer

A. Compensation is a technique used to compensate for error added during measurement, such as the residual parasitic from the fixture, tweezers, etc.
When measuring the capacitor, a fixture or tweezers is needed to make electrical contact. However, the fixture has some parasitic impedance and admittance, which can add unwanted impedance or admittance to the measurement value. Therefore, compensation of the parasitic is necessary.
Compensation usually consists of three steps. These steps are open, short, and load compensation. When performing the open compensation, the parasitic admittance is compensated. When performing the short, the parasitic impedance is compensated. Load compensation sets the reference point for a 50Ω load measurement.
Obviously compensation is paramount for low capacitance (<1000pF) measurements, where any additional measurement error could significantly effect the displayed value.

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Question 28

How to measure capacitors/Test a Capacitors  (7): How can I accurately measure the quality factor (Q)?

Accepted Answer

A. The quality factor is a measure of the extent to which a capacitor acts like a theoretically pure capacitor6. It is the inverse of the dissipation factor (DF). Q is typically reported for capacitance values ≦ 330pF, DF > 330pF.

An accurate Q value can be obtained from Q-meter that utilizes precise inductance coils that correspond to a specific capacitance range. Often multiple coils are necessary to adequately measure across the 0.5 ～ 330pF range. For capacitors > 330pF, the quality factor can be calculated by take the inverse of the dissipation factor (see Formula 1).

*1 "Glossary of Capacitor Terms", Ray Ostlie （1989）

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Question 29

How to measure capacitors/Test a Capacitors  (8): How can I measure a capacitor’s insulation resistance?

Accepted Answer

A. Insulation Resistance (IR) is the extent to which the dielectric material in a capacitor resists leakage current. It is the resistance of the dielectric material itself*1. IR is measured by leakage current. Knowing the leakage current and applied voltage, the insulation resistance can be calculated based on the ohm’s law. There are two basic ways to measure the leakage current. First, apply an ammeter in series with the capacitor and voltage source (see Figure 1).

Second, apply a voltmeter in parallel with a resistor, and then connect in series to the capacitor and voltage source (See Figure 2).

The first method is usually applied to capacitors less than 1uF. Low capacitance capacitors have low leakage current; thus, a low current ammeter can measure the current accurately. If the leakage current is high, the ammeter will not able to measure accurately due to the noise and unstability of the charged capacitor. Therefore, the second method should be used for higher capacitance capacitors*2.

Figure 1: Series ammeter with capacitor.

Figure 2: parallel voltmeter with a resistor and series to a capacitor.

*1 “Glossary of Capacitor Terms”, Ray Ostlie （1989）
*2 Keithley Switching Handbook, 3rd Edition, 1995, Page 4-12

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Question 30

How to measure capacitors/Test a Capacitors  (9): How do I calculate the insulation resistance and CR product?

Accepted Answer

A. There are two limits for insulation resistance depending on the component’s rated voltage (see Table 1).

Rated Voltage	IR Limit Formula
25V～50V	10ꯠMΩ or 500MΩ uF; Whichever smaller.
6.3V～16V	10ꯠMΩ or 100MΩ uF; Whichever smaller.

Table 1

Example:
Rated Voltage : 16V
Nominal Capacitance : 100ꯠpF (or 0.1 uF)

IR Limit = min[10ꯠMΩ or 100MΩ uF/0.1uF]

= min[10ꯠMΩ or 1ꯠMΩ]

Therefore, IR Limit = 1ꯠMΩ

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