JP2016098169A - Dielectric porcelain composition and electronic element using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a dielectric porcelain composition that satisfies characteristics of X5R, X7R and X8R specified in temperature characteristics symbols explicitly shown in the EIA standard; and an electronic element using the same.SOLUTION: A dielectric porcelain composition contains a main component being (1-x)BaTiO3-x(Na1-yKy)NbO3 (0.005≤x≤0.5, 0.3≤y≤1.0), which is a solid solution of BaTiO3 as a first main component and (Na1-yKy)NbO3 as a second main component; a first accessory component including an oxide or carbonate of an element selected from Mn, V, Cr, Fe, Ni, Co, Cu and Zn; and a second accessory component being SiO2 or a glass-forming substance containing the same.SELECTED DRAWING: None

Description

  The present invention relates to a dielectric ceramic composition and an electronic device using the same, and more specifically, a dielectric ceramic composition that satisfies the characteristics of X5R, X7R, and X8R specified in the EIA standard and the same. The present invention relates to an electronic element.

Conventionally, a composition system of a dielectric material of a high-capacity BME multilayer ceramic capacitor such as X5R, X7R, or X8R is BaTiO ₃ or (Ba _1−x Ca _x ) (Ti _1−y Ca _y ) O ₃ which is a main component material. The base material essentially contains subcomponents of approximately four or more types of additives. Among the subcomponents of the additive, those that occupy the largest proportion are Mg, which is a fixed-valence acceptor, and rare-earth elements, and other valence-variable acceptors (variable elements). -Valence acceptor) is added in a smaller amount than these, and sintering aids are included to improve sinterability. In such a conventional composition system, a rare earth element and a valence fixed acceptor Mg or the like react with BaTiO ₃ to form a core-shell structure, which is to realize normal multilayer ceramic capacitor characteristics. It is necessary for

In order to increase the Curie temperature using a BaTiO ₃ base material, there is a method of adding CaZrO ₃ or adding an excessive amount of rare earth elements to alleviate the degree of decrease in the dielectric constant above the Curie temperature. Are known.

JP 2009-173473 A Yoon et al. J. et al. Mater. Res. 22 [9] 2539 (2007)

  The present invention is a dielectric ceramic composition that satisfies the X5R, X7R, and X8R characteristics specified in the EIA standard, and uses nickel as an internal electrode in a reducing atmosphere in which the nickel is not oxidized below 1300 ° C. The object is to provide a dielectric ceramic composition that can be fired and an electronic device using the same.

In the present invention, BaTiO ₃ and (Na, K) NbO ₃ are mixed at an appropriate ratio, or a solid solution is formed, and a small amount of SiO ₂ and MnO ₂ is added to produce a sintered body, A relatively high dielectric constant of 1500 or more can be maintained at room temperature, and X8R temperature characteristics can be satisfied.

  According to the present invention, it is possible to realize the characteristic that the Curie temperature rises and the dielectric constant of the high temperature part becomes flat without using lead (Pb) harmful to the environment as the base material powder, and the X8R temperature characteristic. In addition, excellent high temperature withstand voltage characteristics can be satisfied.

  Hereinafter, the present invention will be described in more detail.

  The present invention relates to a novel dielectric ceramic composition that satisfies the X8R characteristic in which the temperature characteristic and reliability are guaranteed up to 150 ° C.

In the case of BaTiO ₃ , which is the main material of high-capacity Ni-MLCC, the Curie temperature (TC) is around 125 ° C., and above this temperature, the phenomenon that the dielectric constant rapidly decreases occurs. In order to make the temperature characteristic within ± 15% of X8R standard, a composition corresponding to this is required.

For example, an excessive amount of rare earth element is added to the BaTiO ₃ base material to reduce the decrease in the dielectric constant above the Curie temperature, or when an appropriate amount of CaZrO ₃ is added, the Curie temperature rises to increase the TCC (Temperature Coefficient (of Capacitance) can be improved (for example, JP 2002-255639 A, JP 2005-263508 A, etc.).

However, when an excessive amount of rare earth is added, there is a problem that a secondary phase called Pyrochlore is generated and the reliability is lowered (Yon et al., J. Mater. Res., 22 [9] 2539 (2007)). If an excessive amount of rare earth is added to a BaTiO ₃ base material having a Curie temperature of 125 ° C. or CaZrO ₃ is added, the X8R characteristic is satisfied, but there is a limit in obtaining an excellent TCC characteristic in the high temperature part. It was.

As another method, TCC in the high temperature part can be improved by using a powder having a high Curie temperature. It is known that when Ca is dissolved in ABO ₃ of ABO _{3 with} a Perovskite structure, the Curie temperature is raised. When a powder of BaTiO ₃ (BCT) in which Ca is dissolved in this way is used, the temperature is high. TCC characteristics of some parts could be improved, and the possibility as an X8R material has been presented (Yon et al., J. Mater. Res., 25 [11] 2135 (2010)).

When BaTiO ₃ is synthesized by calcination in the air using a solid phase method, elements known to date that can increase the Curie temperature include Pb in addition to Ca. However, in the case of Pb, it is classified as a harmful substance, and when it is fired in a reducing atmosphere like a Ni-multilayer ceramic capacitor, there is a problem that it tends to volatilize. It was difficult.

In the present invention, BaTiO ₃ and (Na, K) NbO ₃ are mixed at an appropriate ratio, or a solid solution is formed, and a small amount of SiO ₂ and MnO ₂ is added to produce a sintered body. Is a ceramic composition that is excellent in insulation resistance and can realize X8R temperature characteristics. That is, the X8R characteristic can be realized without adding CaZrO ₃ or an excessive amount of rare earth elements, and a better TCC characteristic of the high temperature part can be realized as compared with the case of using a conventional BaTiO ₃ base material. Can do.

According to one aspect of the present invention, (1-x) BaTiO ₃ -x (1) is a solid solution of BaTiO _{3 as} the first main component and (Na _1-y K _y ) NbO ₃ as the second main component. Na _1-y K _y ) NbO ₃ (0.005 ≦ x ≦ 0.5, 0.3 ≦ y ≦ 1.0) as a main component, Mn, V, Cr, Fe, Ni, Co, Cu and Zn a first subcomponent including an element selected from the group consisting of a dielectric ceramic composition containing formation material glass containing SiO ₂ or as the second subcomponent is provided.

  In the above, the ranges of x and y are based on the experimental results of Tables 1 and 2 derived from the above composition and examples of the present invention.

The dielectric ceramic composition comprises a base material by mixing and dissolving BaTiO _{3 as} the first main component and (Na, K) NbO _{3 as} the second main component. It includes a valence variable acceptor element oxide or carbonate as a subcomponent and SiO ₂ as a _second subcomponent. The synthesized base material is in a powder form, and the particle size is preferably 1.0 μm or less.

  In one embodiment, the first subcomponent may be an oxide or carbonate of an element selected from the group consisting of Mn, V, Cr, Fe, Ni, Co, Cu and Zn.

In one embodiment, the first subcomponent may be MnO ₂ or MnCO ₃ .

  In one embodiment, the content of the first subcomponent may be 0.1 to 5.0 at%.

In one embodiment, the content of SiO _{2 in} the _second subcomponent may be 0.1 to 5.0 at%.

  The content range of each component described above is based on the experimental results shown in Tables 1 and 2 below.

  According to another aspect of the present invention, an electronic device including a dielectric formed using the above dielectric ceramic composition is provided.

  In one embodiment, the electronic device may be one or more selected from the group consisting of a multilayer ceramic capacitor, a piezoelectric device, a chip inductor, a chip varistor, a chip resistor, and a PTCR (Positive Temperature Coefficient Resistor).

  In particular, the dielectric ceramic composition of the present invention can be used for laminated dielectric products and internal electrode layers, for example, products in which Ni internal electrode layers and dielectric layers are alternately laminated. In the case of a very thin dielectric layer, since the number of crystal grains present in one layer is small and the reliability may be adversely affected, the thickness of the dielectric layer is 0.1 μm after firing. It is preferable to use in the above range.

The mixed solid solution powder of the main component (1-x) BaTiO ₃ -x (Na _1-y K _y ) NbO ₃ , which is a base material powder, was produced using a solid phase method as described below. As starting materials, BaCO ₃ , TiO ₂ , Na ₂ O, K ₂ O, and Nb ₂ O ₅ were used.

First, BaCO ₃ and TiO ₂ were mixed by a ball mill and calcined in the range of 900 to 1000 ° C. to prepare BaTiO ₃ powder having an average particle size of 300 nm. By a similar method, Na ₂ O, K ₂ O, and Nb ₂ O ₅ are mixed by a ball mill and calcined in the range of 800 to 900 ° C., and the average particle size is 300 nm (Na _0.5 K _0.5 ) NbO ₃ powder was prepared.

They were dispersed and mixed in ethanol according to the composition ratio shown in Table 1 below. The powder thus mixed was calcined in the range of 950 to 1050 ° C. in the air to produce a base material powder having an average particle size of about 300 nm. After adding the powder of MnO ₂ and SiO ₂ which are subcomponent additives to the base material powder of such a main component at the composition ratio shown in Table 1, the raw material powder containing the main component and the subcomponent is added. Using zirconia balls as a mixing / dispersing medium, ethanol / toluene, a dispersant, and a binder were mixed, followed by ball milling for 20 hours. The produced slurry produced a 10 μm thick molded sheet using a doctor blade method coater.

  The Ni internal electrode was printed on the manufactured molded sheet. As upper and lower covers, 25 layers of cover sheets were laminated, and 21 layers of printed active sheets were pressed and laminated to produce a bar. The crimp bar was cut into 3.2 mm × 1.6 mm chips using a cutting machine.

The 3216 size multilayer ceramic capacitor (MLCC) chip manufactured in this way is subjected to calcination and then 0.1% H ₂ /99.9% N ₂ (H ₂ O / H ₂ / N) in a reducing atmosphere. ₍₂ atmospheres) was fired at a temperature of 1200 to 1300 ° C. for 2 hours, and then re-oxidized at 1000 ° C. in an N ₂ atmosphere for 3 hours. The fired chip was subjected to a termination process and electrode firing with a Cu paste to complete an external electrode.

  The prototype multilayer ceramic capacitor specimens completed as shown in Table 1 were evaluated for capacity, DF, insulation resistance, TCC, resistance degradation behavior due to an increase in voltage step at a high temperature of 150 ° C., and the like. The room temperature capacitance and dielectric loss of the multilayer ceramic capacitor chip were measured using an LCR meter under the conditions of 1 kHz and AC 0.2 V / μm.

  The dielectric constant of the multilayer ceramic capacitor chip dielectric was calculated from the capacitance, the dielectric thickness of the multilayer ceramic capacitor chip, the area of the internal electrodes, and the number of layers.

  Room temperature insulation resistance (IR) was measured after 60 seconds with 10 samples taken and DC 10 V / μm applied. The change in capacitance according to temperature was measured in the temperature range of -55 ° C to 150 ° C.

  In the high temperature IR boost experiment, the resistance degradation behavior was measured while increasing the voltage step by 5 V / μm at 150 ° C. Here, the time of each step was 10 minutes, and the resistance value was measured at intervals of 5 seconds.

A high-temperature withstand voltage is derived from a high-temperature IR boosting experiment. This is a voltage step DC5V / μm for 10 minutes at 150 ° C. for a 3216-sized chip having 20 dielectric layers 7 μm thick after firing. When applied and measured while increasing the voltage step, it means a voltage with which IR can withstand 10 ⁵ Ω or more.

Table 2 shows characteristics of the prototype multilayer ceramic capacitor chip corresponding to the composition shown in Table 1.

In Examples 1 to 12 in Table 1, in the second main component (Na _1-y K _y ) NbO ₃ , y = 0.5, and the first subcomponent MnO ₂ and the second subcomponent SiO ₂ When the content of the base material powder (1-x) BaTiO ₃ -x (Na _1-y K _y ) NbO _{3 is} 0.5 at% and 0.5 at%, respectively, the content of the first main component BT 1- It shows the x and _{(Na 1-y} K y) characteristics of the prototype chip responsive to changes in the content x of NbO ₃ of the second principal component. When the content of x gradually increases from 0 (Example 1) to 0.6 (Example 12), the dielectric constant gradually decreases. When x is 0 (Example 1), The dielectric constant is 3156, which is very high, but there is a problem that TCC (150 ° C.) is −35.2%, which is outside the ± 8% X8R standard, and x is 0.6 (Example) 12) has a problem that the room temperature dielectric constant is less than 1500 and becomes too low.

  The specimens of Examples 2 to 11 satisfy the temperature characteristics of X8R of room temperature dielectric constant of 1500 or more, high temperature withstand voltage of 50 V / μm or more, and TCC (150 ° C.) ≦ ± 15%. Can be described as 0.005 ≦ x ≦ 0.5.

In Examples 13 to 19 in Table 1, in the second main component (Na _1-y K _y ) NbO ₃ , y = 0.5, the content x = 0.05, and the second subcomponent The characteristics of the prototype chip according to the change in the MnO ₂ content of the first subcomponent when the SiO ₂ content of the base material powder is 0.5 at% relative to the base material powder are shown.

When the Mn content is 0 (Example 13), the room temperature resistivity value is 8.480E7 (xEy = x × 10 ^y ), which is very low, and the Mn content is 0.1 (Example). 14) From the above, it can be confirmed that an insulation characteristic of 1E11 or more is realized.

  As the Mn content increases, the dielectric constant and the room temperature resistivity continue to decrease, and when the Mn content increases to 0.07 at% (Example 19), the dielectric constant decreases to 1365 and becomes less than 1500. There arises a problem that the room temperature specific resistance is less than 1E11.

  In the specimens of Examples 14 to 18, since the dielectric constant, high-temperature withstand voltage, and TCC characteristics satisfy the target characteristics of the present invention, the Mn content can be selected within the range of 0.1 to 5.0 at%. it can.

In Examples 20 to 25 of Table 1, in the second main component (Na _1-y K _y ) NbO ₃ , y = 0.5, x = 0.05, and the content of MnO ₂ as the first subcomponent Shows the characteristics of the prototype chip according to the change in the content of SiO ₂ as the second subcomponent when the ratio is 0.5 at% relative to the base material powder.

When the content of SiO ₂ is 0 (Example 20), the firing temperature is increased to about 1300 ° C., and when SiO ₂ is added (Examples 21 to 24), the sinterability is improved. There was an effect.

When the content of SiO ₂ is 7 at% (Example 25), the effect of improving the sinterability is almost lost, and the high-temperature withstand voltage characteristic becomes worse than less than 50 V / μm.

Therefore, from the results of Examples 20 to 25, considering the dielectric constant, high-temperature withstand voltage, TCC characteristics, and sinterability, the preferable SiO ₂ content can be selected in the range of 0.1 to 5.0 at%. it can.

In Examples 26 to 29 in Table 1, the content x of the second main component (Na _1-y K _y ) NbO ₃ is x = 0.05, the first subcomponent MnO ₂ and the second subcomponent SiO _2. Content of the base material powder is 0.5 at% and 0.5 at%, respectively, the K content y and the Na content 1 in the second main component (Na _1-y K _y ) NbO ₃ Indicates the characteristics of the prototype chip depending on -y.

In the second main component (Na _1-y K _y ) NbO ₃ , the Ti content decreases to 0.3 (Example 27) to 0.2 (Example 26) on the basis of y = 0.5. As the dielectric constant decreases, the high-temperature withstand voltage characteristics deteriorate, and when y = 0.2 (Example 26), the high-temperature withstand voltage characteristics become less than 50 V / μm. I understand. The dielectric constant and the high-temperature withstand voltage characteristics are somewhat lowered as the Ti content is increased from 0.7 (Example 28) to 1.0 (Example 29) on the basis of y = 0.5. The high temperature withstand voltage and TCC characteristics satisfy the target characteristics of the present invention.

  Therefore, from the results of Examples 26 to 29, in consideration of the dielectric constant, the high-temperature withstand voltage, and the normal temperature specific resistance value, the preferable range of the K content y may be selected as 0.3 ≦ y ≦ 1.0. it can.

  The present invention relates to a dielectric ceramic composition and an electronic device using the same, and more specifically, a dielectric ceramic composition that satisfies the X5R, X7R, and X8R characteristics specified in the EIA standard and uses the same. The present invention relates to an electronic device.

  According to the present invention, it is possible to realize the characteristics that the Curie temperature rises and the high temperature dielectric constant becomes flat without using lead (Pb) harmful to the environment as the base material powder. Good high temperature withstand voltage characteristics can be satisfied.

  Although specific portions of the present invention have been described in detail as above, such specific descriptions are merely preferred embodiments for those of ordinary skill in the art, and thus the present invention. Obviously, the range is not limited. Therefore, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

Claims (7)

(1-x) BaTiO ₃ -x (Na _1-y K _y ) NbO _3, which is a solid solution of BaTiO _{3 as} the first main component and (Na _1-y K _y ) NbO ₃ as the second main component. An element selected from the group consisting of Mn, V, Cr, Fe, Ni, Co, Cu, and Zn having (0.005 ≦ x ≦ 0.5, 0.3 ≦ y ≦ 1.0) as a main component. A dielectric ceramic composition comprising: a first subcomponent including SiO2; or a _second subcomponent that is SiO ₂ or a glass-forming substance including the same.   The dielectric ceramic composition according to claim 1, wherein the first subcomponent is an oxide or carbonate of an element selected from the group consisting of Mn, V, Cr, Fe, Ni, Co, Cu, and Zn. The dielectric ceramic composition according to claim 1, wherein the first subcomponent is MnO ₂ or MnCO ₃ .   The dielectric ceramic composition according to any one of claims 1 to 3, wherein a content of the first subcomponent is 0.1 to 5.0 at%. 5. The dielectric ceramic composition according to claim 1, wherein the content of SiO ₂ in the second subcomponent is 0.1 to 5.0 at%.   An electronic device comprising a dielectric formed using the dielectric ceramic composition according to any one of claims 1 to 5.   The electronic device according to claim 6, wherein the electronic device is one or more selected from the group consisting of a multilayer ceramic capacitor, a piezoelectric device, a chip inductor, a chip varistor, a chip resistor, and PTCR (Positive Temperature Coefficient Resistor).