CN103864413B - Dielectric ceramic powder composition and temperature compensation type laminated ceramic capacitor made of same - Google Patents

Abstract

The invention relates to a dielectric ceramic powder composition and a temperature compensation type laminated ceramic capacitor made of the dielectric ceramic powder composition, wherein the sintering temperature is below 1000 ℃, and the dielectric ceramic powder composition can be matched with an internal electrode of 90% Ag/10% Pd to make the laminated ceramic capacitor. The dielectric ceramic powder composition comprises 100 parts by weight of MgO in a mole, ZnO in a mole b, CaO in a mole c, BaO in a mole d and TiO in a mole m₂The first component and 1.5-16 weight portions of BaO and SiO₂ZnO, MnO and B₂O₃A glass frit of a second composition; wherein m = B/A = TiO₂The mole number/(MgO + ZnO + CaO + BaO), a + b + c + d =1, a is more than or equal to 0.05 and less than or equal to 0.40, b is more than or equal to 0.40 and less than or equal to 0.85, c is more than or equal to 0.04 and less than or equal to 0.11, d is more than or equal to 0.00 and less than or equal to 0.30, and m is more than or equal to 0.6 and less than or equal to 2.0.

Description

Composition of Dielectric Porcelain Powder and Temperature Compensation Multilayer Ceramic Capacitor Made of It

technical field

The invention relates to the field of ceramic capacitors, in particular to a dielectric ceramic powder composition and a temperature-compensating laminated ceramic capacitor made thereof.

Background technique

Generally, ceramic capacitors can be divided into three categories according to the dielectric constant of the ceramic powder: high dielectric constant type (Hi-K), medium dielectric constant type (Mid-K) and temperature compensation type (TC). The dielectric constant of the high dielectric constant type reaches 4000-15000, and the dielectric constant changes greatly with the change of temperature. The dielectric constant of the medium-permittivity type is about 1400-3000, and the change of the dielectric constant with temperature is small but often nonlinear. The dielectric constant of the temperature compensation type is about 8 to 100, and the dielectric constant changes with temperature the least and often changes linearly.

The internal electrode and the ceramic dielectric layer of the multilayer ceramic capacitor must be co-fired together. Therefore, the porcelain powder composition of the common commercialized multilayer ceramic capacitor can be divided into two types according to the firing temperature: high-temperature firing type and low-temperature firing type. The firing temperature of the high-temperature firing type is about 1250 ° C to 1300 ° C. Because of the high firing temperature, the internal electrodes generally need to use palladium (Pd) metals with high melting points and expensive prices. Low-temperature sintering type Since the sintering temperature is below 1150°C, the inner electrode can be made of cheap silver-palladium alloy metal (Ag/Pd) with high silver content to reduce costs and be more economical.

Although the dielectric constant of the ceramic powder of the general temperature compensation capacitor is between 8 and 100, when the current technology manufactures low-capacitance NP0 multilayer ceramic capacitors below 100pF, if the dielectric constant of the ceramic powder is high, it will be due to The number of laminated layers is small, and the production process is not easy to control. The capacitance value of ceramic capacitors often deviates from the specification value and the yield rate is low; There are many palladium internal electrodes, which increases the cost of internal electrode materials. Therefore, the current manufacturing of multilayer ceramic capacitors below 100pF often uses ceramic powder with a dielectric constant of 15-45 to obtain the most suitable economical production.

Generally, the composition of low-temperature firing type dielectric ceramic powder is usually the main component of high-temperature firing and then adding various sintering aids (Sintering aid), such as glass (glass), glass frit (frit) or flux (flux), etc. In order to reduce the firing temperature, general glass or glass frit contains low melting point components such as Pb, Cd or Bi, and Pb and Cd are harmful substances to the environment and ecology.

Regarding the composition of low-temperature firing temperature-compensated ceramic capacitors, U.S. Patent No. 4,506,026 discloses a composition consisting of the main component MgO-CaO-TiO ₂ -Al ₂ O ₃ -SiO ₂ -Nb ₂ O ₅ and the secondary component PbO-Bi ₂ O ₃ -CdO-ZnO-SiO ₂ -B ₂ O ₃ glass and No. 5,599,757 discloses a glass composed of main component BaO-TiO ₂ -ZrO ₂ -SiO ₂ and auxiliary component PbO-TiO ₂ -ZrO ₂ -Al ₂ The composition composed of O ₃ -LiF-SiO ₂ -B ₂ O ₃ glass meets the NP0 specification requirements of EIA, but the firing temperature must be above 1100°C and the composition of the porcelain powder contains Pb or Cd, which is harmful to the environment substance. Therefore, the firing temperature is below 1000°C, and the main component is MgO-ZnO-CaO-BaO-TiO ₂ , and the auxiliary component of BaO-SiO ₂ -ZnO-MnO-B ₂ O ₃ frit is added without Pb, Cd, Bi The powder composition of MLCCs has not yet appeared.

In response to the trend of environmental protection, it is necessary to develop a composition of dielectric ceramic powder that does not contain Pb and Cd.

Contents of the invention

The present invention selects an appropriate main component system, adds sintering aids that do not contain Pb and Cd to reduce the sintering temperature to below 1000°C, so that 90% Ag/10% Pd, which is cheaper than 70% Ag/30% Pd, can be used. Internal electrodes to reduce costs to manufacture more economical MLCCs.

The purpose of the present invention is to develop a kind of dielectric porcelain powder composition that can be fired into laminated ceramic capacitors at a sintering temperature of 1000 ° C, and does not contain components such as lead, cadmium, bismuth, and the dielectric constant of its electrical properties can reach 25~40, Q value above 1000, temperature coefficient conforms to E.I.A. NP0 specification, that is, within 0±30ppm/℃, the composition of the dielectric ceramic powder is suitable for the manufacture of temperature-compensated multilayer ceramic capacitors.

In order to achieve the above-mentioned purpose, the present invention proposes the composition of the dielectric ceramic powder of the laminated ceramic capacitor of ultra-low temperature firing and low dielectric constant, which is composed of 100 parts by weight of molar ratios of 0.05≤MgO≤0.40, 0.40≤ZnO≤0.85 , 0.04≤CaO≤0.11, 0.00≤BaO≤0.30, 0.6≤TiO ₂ ≤2.0, and 1.5-16 parts by weight of glass frit of the second component composed of BaO, SiO ₂ , ZnO, MnO and B ₂ O ₃ (frit), wherein the composition of glass frit (frit) is 10% ≤ BaO ≤ 60%, 5% ≤ SiO ₂ ≤ 30%, 5% ≤ ZnO ≤ 30%, 0% ≤ MnO ≤ 10%, 15% ≤B ₂ O ₃ ≤60%.

According to the above composition range, MgTiO ₃ , ZnTiO ₃ , CaTiO ₃ , BaTi ₄ O ₉ , Ba ₂ Ti ₉ O ₂₀ etc. are the main components and frit is added to lower the sintering temperature below 1000°C and increase the density of the sintered body. sex. Controlling the content ratio of different MgTiO ₃ , ZnTiO ₃ , CaTiO ₃ , BaTi ₄ O ₉ , Ba ₂ Ti ₉ O ₂₀ can adjust the dielectric constant and capacitance temperature coefficient; adding glass frit can increase the sintering density and insulation resistance .

For further disclosure of the technical content of this case, please refer to the following examples:

Detailed ways

The technical solutions in the embodiments of the present invention are clearly and completely described below. Apparently, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Starting from BaCO ₃ (barium carbonate), ZnO (zinc oxide), Mg(OH) ₂ (magnesium hydroxide) or MgCO ₃ (magnesium carbonate), CaCO ₃ (calcium carbonate), TiO ₂ (titanium oxide), Weigh according to the composition ratio shown in Table 1, wet mix in a ball mill for 16 hours, pour out and dry, and then calcinate in a kiln at a high temperature above 1050°C for 2 hours, and the calcined material is coarsely crushed and finely ground to below 1.0 μm As the first ingredient in the present invention.

The second component of glass frit (frit) uses zinc oxide (ZnO), barium carbonate (BaCO ₃ ), manganese carbonate (MnCO ₃ ), boric acid (H ₃ BO ₃ ), silicon oxide (SiO ₂ ) as starting materials , and according to the sum of 10% ≤ BaO ≤ 60%, 5% ≤ SiO ₂ ≤ 30%, 5% ≤ ZnO ≤ 30%, 0% ≤ MnO ≤ 10%, 15% ≤ _{B 2} O ₃ ≤ 60% 100% According to the proportion of weighing, mixing and drying, it is quenched in molten water at 1100°C and then coarsely crushed and finely ground to less than 1.5μm.

According to the weight ratio in Table 2, the first component and the second component were weighed, wet-mixed in a ball mill for 16 hours, and dried to obtain the final formula powder. Add 20% solution containing 10% polyvinyl alcohol (PVA) to this formula powder, granulate it, and press it into a disc shape with a diameter of 10mm and a thickness of 0.5mm at a pressure of 1.5Ton/ _cm2 The green sheet is sintered at a temperature of about 1000°C for 2 hours. After the electrodes are fired on both sides of the sintered body, its electrical properties and sintered density are measured according to the following test conditions: frequency 1MHz, test voltage 1Vrms, capacitance value and calculation of dielectric constant ε and measurement of DF value (ie dissipation factor tanδ) ; With a DC voltage of 500V, charging for 1 minute, and a temperature of 25°C, measure the resistance value; take the capacitance value at 25°C as the benchmark, measure the capacitance temperature variation coefficient from -55°C to 125°C; measure the weight and volume of the sintered body to calculate The density of the sintered body, and the microstructure of the sintered body is observed by an optical microscope (OM), and these data are used to comprehensively analyze whether the composition meets the requirements.

The above-mentioned sample formula can be further made into a multilayer ceramic capacitor, and its method is as follows: to 100 parts by weight of the formula powder, add 10 parts of polymethyl methacrylate, 30 parts of methyl ethyl ketone/ethanol solvent, butyl benzyl phthalate The organic binder composed of 4 parts of acid ester, etc., is placed in a ball mill and mixed evenly for 16 hours to make a porcelain slurry for casting molding, and then put the porcelain slurry into the coating machine to make the porcelain slurry evenly coated on the substrate The thickness of the dielectric layer coated each time is about 20 μm to 30 μm. After drying at 80 ° C, the internal electrode layer with the internal electrode material composition of 90% Ag/10% Pd is printed, and this is repeated several times to achieve the required After the thickness and the number of layers, the formed body is cut into green chips with a size of 4.0L×2.0Wmm. The green chips are degreased at a temperature lower than 500°C for 80 hours, and then sintered at a temperature of 960°C to 1000°C for 3 hours. , the size of the sintered chip is about 3.2L×1.6Wmm, and after the external electrode is fired, according to the following test conditions: frequency 1MHz, test voltage 1Vrms, measure D.F value and capacitance value and calculate its dielectric constant ε value; DC voltage 50V, after charging for 1 minute, measure the insulation resistance value; increase the DC voltage at a rate of 100V per second, and measure its breakdown voltage; take the capacitance value at 25 °C as the reference, measure the capacitance temperature from -55 °C to 125 °C coefficient of variation to fully evaluate the electrical characteristics of MLCCs. The results of this example are shown in Table 3.

In the present invention, the dielectric constant is 25-40, the capacitance temperature coefficient conforms to the NP0 specification (that is, -55°C to 125°C, 0±30ppm), the D.F value (that is, the dissipation factor tanδ) is below 0.001, and the insulation resistance is above 1×1011Ω , The sintered density is above 4.25g/cm3 as the goal. Sample 1, Sample 7, Sample 8, Sample 12, Sample 14, Sample 16, Sample 17, Sample 19, Sample 21, Sample 22, and Sample 26 are excluded from the samples in Table 2. Except that the object of the present invention cannot be met, all the other samples can meet the object, so the reasons for the scope of the claim are as follows:

As shown in sample 1, when frit=1 weight part, the D.F value is too high and the sintered density is lower than the target value. As shown in sample 7, when frit=20 weight part, sintering produces sticking phenomenon so that The electrical property cannot be measured, which means that there is too much glass frit, and when frit=2～16 parts by weight, the target value can be met. Therefore, the optimum adding amount of frit is 1.5%≤frit≤16.0%.

Samples 8 to 26 are mainly to adjust the ratio of MgO, ZnO, CaO, BaO and TiO ₂ in the first component to find the best range. In this range, the samples can meet the target electrical characteristics and sintered density and microscope structures.

As shown by sample 8 and sample 12, when MgO=0m/o, the D.F value is too high, which does not meet the requirements of NPO characteristics. Or when MgO=50m/o, poor sintering results in poor sintered density, poor IR and poor D.F. When MgO=5m/o～40m/o, all properties meet the target value, so the optimum range of MgO 5m/o≤MgO≤40m/o.

As shown by sample 14 and sample 16, when ZnO=32.5m/o, the D.F value deviates from the target value, when ZnO=87.5m/o, the D.F value also deviates from the target value, when ZnO=42.5m/o～ At 82.5m/o, all properties meet the target value, so the optimum range of ZnO is 40m/o≤ZnO≤85m/o.

As shown by sample 17 and sample 19, when CaO=3.7m/o, the temperature coefficient deviates from the target value, when CaO=11.2m/o, the temperature coefficient also deviates from the target value, when CaO=5.2m/o～ At 9.5m/o, all properties meet the target value, so the optimum range of CaO is 4m/o≤CaO≤11m/o.

As shown in sample 21, when BaO=40m/o, there is a phenomenon that the D.F value is too high to meet the requirements of NPO characteristics. When BaO=0m/o～30m/o, all properties meet the target value, so BaO The optimum range is 0m/o≤BaO≤30m/o.

As shown by samples 22 and 26, when m=TiO ₂ moles/(MgO+ZnO+CaO+BaO) moles=0.59, the DF value is too high and exceeds the target value; when m=2.50, there is a temperature The phenomenon that the coefficient deviates far from the target value, when m=0.67～2.00, all properties meet the target value, so the optimum range of m is 0.60≤m≤2.00.

The first component batching ratio of table 1 sample 10

raw material weight after burning weight moles The molar ratio of Mg(OH) ₂ 1.17kg MgO 0.81kg 20 a=0.10 ZnO 10.17kg ZnO 10.17kg 125 b=0.625 CaCO ₃ 1.50kg CaO 0.84kg 15 c=0.075 BaCO ₃ 7.89kg BaO 6.13kg 40 d=0.20 TiO ₂ 17.74kg TiO ₂ 17.74kg 222 m=1.11

The composition list and test characteristic result of table 2 embodiment

Table 3 Electrical Characteristics of Multilayer Ceramic Capacitors Made of Sample 2 and Sample 15

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the scope of the present invention. Protection scope, within the spirit and principles of the present invention, any modification, equivalent replacement, improvement, etc., shall be included in the protection scope of the present invention.

Claims (6)

1. A low-permittivity dielectric ceramic powder composition of ultra-low temperature firing, characterized in that, said dielectric ceramic powder composition comprises 100 parts by weight mainly consisting of a mole of MgO, b mole of ZnO, c mole of CaO, d mole A glass frit with a first component composed of moles of BaO and m moles of TiO ₂ and a second component of 1.5 to 16 parts by weight of a second component mainly composed of BaO, SiO ₂ , ZnO, MnO and B ₂ O ₃ ; wherein, m=TiO ₂ moles Number/(MgO+ZnO+CaO+BaO) moles, in the above formula, ZnO is the first component of ZnO, and a+b+c+d=1, and 0.05≤a≤0.40, 0.40≤b≤0.85 , 0.04≤c≤0.11, 0.00≤d≤0.30, 0.6≤m≤2.0; the content of each component of the glass frit of the second component is 10%≤BaO≤60%, 5%≤SiO ₂ ≤30% , 5%≤ZnO≤30%, 0%≤MnO≤10%, 15%≤B ₂ O ₃ ≤60%. 2. The low-permittivity dielectric ceramic powder composition of ultra-low temperature firing as claimed in claim 1, wherein each composition in the first component is based on BaCO ₃ , ZnO, Mg(OH) ₂ Or MgCO ₃ , CaCO ₃ as the starting material, wet mixed in the ball mill for 16 hours, poured out and dried, then calcined in the kiln at a high temperature above 1050°C for 2 hours, and the calcined material was coarsely crushed and finely ground to below 1.2μm. 3. the low-k dielectric ceramic powder composition of ultra-low temperature firing as claimed in claim 1, is characterized in that, each component in the glass frit of described second component is weighed in proportion, mixed, oven dry Afterwards, it is quenched in molten water at 1100°C and then coarsely crushed and finely ground to below 1.5 μm. 4. A temperature-compensated laminated ceramic capacitor made of a low-permittivity dielectric porcelain powder composition fired at an ultra-low temperature, characterized in that, the low-permittivity dielectric porcelain powder composition is composed of 100 parts by weight A glass frit mainly composed of a mole of MgO, b mole of ZnO, c mole of CaO, d mole of BaO and m mole of TiO ₂ and a glass frit of 1.5 to 16 parts by weight of a second component, the low dielectric constant dielectric The ceramic powder composition is added with an organic binder, uniformly mixed in a ball mill to make a porcelain slurry for casting molding, and then the porcelain slurry is evenly coated on the substrate and dried, and then the internal electrode material is printed, and so repeated several times To achieve the desired ceramic structure, the laminated ceramic capacitor formed by sintering; wherein, m=TiO ₂ moles/(MgO+ZnO+CaO+BaO) moles, in the above formula, ZnO is the first component of ZnO , and a+b+c+d=1, and 0.05≤a≤0.40, 0.40≤b≤0.85, 0.04≤c≤0.11, 0.00≤d≤0.30, 0.6≤m≤2.0; the glass of the second component The composition of the frit is 10%≤BaO≤60%, 5%≤SiO ₂ ≤30%, 5%≤ZnO≤30%, 0%≤MnO≤10%, 15%≤B ₂ O ₃ ≤60%. 5. The temperature-compensated multilayer ceramic capacitor made of the low-permittivity dielectric porcelain powder composition of the ultra-low temperature firing as claimed in claim 4, wherein the organic binder is made of polymethylmethacrylate It is composed of ester, butanone/ethanol solvent, and butyl benzyl phthalate. 6. The temperature-compensated multilayer ceramic capacitor made of the low-permittivity dielectric porcelain powder composition fired at ultra-low temperature as claimed in claim 4, wherein the composition of the internal electrode material is 90% Ag /10% Pd as the internal electrode material.