JPS6021858A - Ceramic composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a porcelain composition, particularly a porcelain composition that can be sintered at a low temperature of 1000°C or less, has a high product of dielectric constant and specific resistance (and has high mechanical strength). .

Conventionally, barium titanate (B
It is well known that porcelain compositions containing aTiO, ) as a main component have been widely put into practical use. However, those whose main component is barium titanate (BaTjOs) have a sintering temperature of usually 1300 to 1400°C. Therefore, if this material is used in a 414-type capacitor, a material that can withstand this sintering temperature must be used for the internal electrodes, such as a high-temperature metal material such as platinum or palladium, which increases manufacturing costs. There are drawbacks. In order to manufacture multilayer capacitors at low cost, a porcelain composition that can be sintered at as low a temperature as possible, particularly below 1000° C., is required so that inexpensive metals mainly composed of silver, nickel, etc. can be used for internal electrodes.

By the way, when producing a practical multilayer capacitor using a ceramic composition, many items must be evaluated as the electrical properties of the ceramic composition.1 Generally, the dielectric constant should be as high as possible, and the dielectric loss should be as high as possible. It is required that the resistivity be as small as possible, that the specific resistance be as large as possible, and that the change in dielectric constant with temperature be small.

However, for practical purposes, multilayer capacitors require values such as capacitance, temperature change rate of capacitance, dielectric loss, etc., rather than dielectric constant. In multilayer capacitors,
Capacity is proportional to the dielectric constant of the porcelain composition, but it is inversely proportional to its thickness, and proportional to the electrode area and the number of laminated layers, so it is not necessarily necessary that the dielectric constant of the porcelain composition be large in order to obtain a constant capacitance. It is not a factor. Furthermore, the temperature change rate of capacitance (temperature change rate of permittivity) has various allowable ranges depending on the application, and the temperature change rate of permittivity of the ceramic composition is not an absolute factor when manufacturing multilayer capacitors. .

On the other hand, there is a regulation that the induced loss must be below a certain value depending on the application, and the maximum is 5.0% or below at room temperature.

Furthermore, regarding specific resistance, for example, as stated in I (IAJ standard [Japan Electronics Industry Association's Multilayer Ceramic Capacitor (Chip Type) RC-3698B)], the insulation resistance of the multilayer capacitor should be 10,000 MΩ or more or the capacity. It is specified that the resistance product is 500 μF - MΩ or more, whichever is smaller. In other words, if the product of the permittivity and resistivity of the porcelain composition exceeds a certain absolute value lj, a capacitor of any capacitance, especially a large capacitance, cannot meet practical standards; , and has no practical meaning. This point will be explained in detail as follows. A multilayer capacitor has a structure in which single-layer capacitors are stacked, generally consisting of n layers of the same thickness and forming n+1 internal electrodes. In this case, if the capacitance per single layer is Co and the insulation resistance is Tori, then the capacitance C of the multilayer capacitor will be CoQ)n times, and the insulation resistance R will be 1/n of Horse.

Here, the dielectric constant of the porcelain composition is 6. The dielectric constant of Makabe is εo,
If the specific resistance of the ceramic composition is ρ, and the thickness of the ceramic of the single-layer capacitor is 41, and the area of the overlapping electrodes is S, then C6 of the single-layer capacitor is (ε.C8)/d, and R6 is (ρd)/
It becomes 8. Therefore, the capacitance of a multilayer capacitor consisting of n layers (
The product CXR of C) and insulation resistance (R1 is [(ρd)/(”8
)) X ((ng, g8)/d) == goερ
becomes. That is, the capacitance-resistance product (CXR) of a multilayer capacitor of any capacity is normalized to a constant value (ε0ερ) obtained by multiplying the product of ε and ρ of the ceramic composition by 60.

Capacitance/resistance product CXR is 500μF@MΩ, or 500
More than F・Ω means ε. = 8.855 mochi Q-”
From F/cm, CXR = g, ip = 8.85
5X10-''(F/(m)Xε×ρ≧500F·Ω, therefore, there is a requirement that ερ≧5.65

For example, when ε=10000, ρ≧5.65X10”Ω・
α.

When ε = 3000, ρ≧1.88 XIO Otori 2Ω・Tan,
When ε=500, ρ≧1.13×10”Ω・儂 is required. Depending on the dielectric constant, any large-capacity multilayer capacitor can have a capacitance of ρ greater than or equal to these values. The resistance product satisfies 500 μF and MΩ.If ε is 3000 and ρ is 1.88 XI, which is one order of magnitude lower than the required value.
If O”Ω, then ε0ερ=50μF@MΩ and 500
μF-MΩ is not satisfied, and the standard value of insulation resistance is 110
In order to satisfy 0OOΩ, that is, 10100 or more, the capacitance C must be limited to 0.005 μF or less. It is the capacitance-resistance product (CxR
) always indicates 50 μF and MΩ, so ■ is 100
When it is 0OOΩ, C is 0.005 μF, and if C is thicker than this, the value becomes smaller than 10000 MΩ,
This is because 0.005 μF is the highest capacitance that satisfies the standard.

Therefore, if the specific resistance of the porcelain composition is low, the usability of the material will be reduced.
In particular, it is not possible to take advantage of the small size and large capacity, which is a feature of the laminated copper capacitor, and it is completely meaningless. Therefore, it is extremely important in practice that the product of the dielectric constant and specific resistance of the ceramic composition has a certain value or more.

Also,! *In the case of Jf4 type chip capacitors, after the chip capacitor is mounted on a board, mechanical strain is applied to the chip capacitor due to the difference in thermal expansion coefficient between the board and the ceramic composition that makes up the chip capacitor. The capacitor may crack or be damaged. Furthermore, in the case of a dip capacitor coated with epoxy resin or the like, cracks may occur in the dip capacitor due to the stress of the coat resin. In either case, the lower the mechanical strength of the porcelain forming the capacitor, the more likely it is to crack and break, resulting in lower reliability. Therefore, it is of practical importance to increase the mechanical strength of porcelain as much as possible.

By the way, Pb (Mg bar W%) 0. -PbTiO, based porcelain compositions have already been reported by N, N, Krainik and AI, Agranovskaya.
andA +I, Agranovskaya (F
iziko Tverdogo T, ela.

Vo, 2. Jcil, pp'yo ~72. Jan
Vara (1960)), but among the characteristics to be evaluated when manufacturing a multilayer capacitor, only the dielectric constant and its temperature characteristics were described, and its practicality was not clear. Also (5rxPb1-xTiOa)a(
PbMgo, sWo, sOs) b [Tatashi, x = 0
-0.10, a 0.35 to 0.5, b 0.
5 to 0.65, and a + b = 1), it is disclosed in Japanese Patent Application Laid-open No. 1982-21662 as a monolithic capacitor and its manufacturing method, and as @Electric powder composition It is disclosed in Japanese Patent No.-21699. Here again, the characteristics of the composition are that the dielectric constant is approximately 2000 to 8000, and the galvanic loss is 0. ! There is a description of 11 to 5.0 inches, but there is no mention of specific resistance or capacitance-resistance product, and the practicality is clear. Sarani Pb
(Mg, W,)0. PbTiOs Main composition: Pb (Mg34w%) 0. F20.
0 to 70.0 mo/L, %, PbTi0. Ka3
0.0~80. A high dielectric constant porcelain composition characterized in that it contains an amount of MgO added to a calculated value of 30 or less is disclosed in Japanese Patent Application Laid-open No. 55-1446.
It is disclosed as Publication No. 09.

However, even in this patent, the dielectric constant is about 2300.
In addition to the description that the dielectric loss is 0.3 to 2.1 inches for ~7100, there is also a description of the temperature characteristics of the dielectric constant, but there is no description of specific resistance or capacitance-resistance product, and the practicality of this composition is clear. Not. Next, the inventors have already identified 910
It can be sintered at temperatures between ℃ and 950℃, and Pb (Mg MW3
A) It consists of two components of 03 and PbTios system, which is (
Pb(Mg34W%)Os)xl:PbTi0s), -
We are proposing a composition in which X is in the range of 0.65 (x≦1.00). This composition has a product of dielectric constant and specific resistance of 5.65 x 1015 Ω or more. It has a high value of , and has excellent electrical properties with low dielectric loss.

However, since all of the above compositions have low mechanical strength, their applications have had to be limited to a narrow range.

In view of the above points, the present invention can be sintered in a low temperature range of 900 to 1000°C, and has a product of dielectric constant and specific resistance of 5.65.
×lQ'5Qec1rL (that is, the capacitance-resistance product is 500
The purpose of this project is to provide a porcelain composition that has a high value of p F -Mn) or higher, has excellent electrical properties with low dielectric loss, and also has high mechanical strength. (MgMW%) 0.] and lead titanate (PbTiO,).
(Mg%w%)o, )x(PbTiO,)I It is characterized by containing 0.01 to 1 atomic percentage of the main component.

Hereinafter, the present invention will be explained in detail with reference to Examples.

Lead oxide (PbO) with a purity of 99.9% or more as a starting material
.

Magnesium oxide (MgO), tungsten oxide (Wo
s) Titanium oxide (Tie, ) and manganese carbonate (M
nCO,), and weigh each to achieve the blending ratio shown in the table. Next, the weighed materials were wet-mixed in a ball mill, pre-baked at 750-800°C, and the powder was ground in a ball mill. After drying, an organic binder was added and the particles were sized and pressed. The diameter was 1611 m. , four disks each having a thickness of approximately 2 mm and a cylinder having a diameter of 16 mm and a thickness of approximately IQ++n were prepared. Next, it was sintered in air at a temperature of 900 to 1000°C for 1 hour. Silver electrodes were baked on the top and bottom surfaces of four sintered disks at 600"C, and the frequency IK was measured using a digital LCR meter.
The capacitance and dielectric loss were measured at Hz, [pressure I Vr, m, s, and temperature 20° C., and the dielectric constant was calculated. Next, a voltage of 50 V was applied for 1 minute using a super insulation resistance meter, the insulation resistance was measured at a temperature of 20° C., and the specific resistance was calculated.

In order to evaluate the mechanical properties by bending strength, a sintered cylinder with a thickness of 0.5 art, a width of 211 In, and a length of approximately 131 In was prepared.
Ten rectangular plates of 1III were cut out. The bending strength τ [ψtoku 2] was calculated using the distance between the fulcrums as 9 and according to the three formulas. Here, ① is the distance between the supporting points, t is the thickness of the sample, and W is the width of the sample. The electrical properties were determined from the average value of 4 disk samples, and the bending strength was determined from the average value of 10 rectangular plate samples.

The main component of the porcelain thus obtained (Pb (iV1g
3(W)4 ) Os ) x (Pb'I t Os
) 1-X blending ratio X and amount of subcomponents added, bending strength, dielectric constant, dielectric loss, and capacitance-resistance product (ε0ερ in the table)
) is shown in the table.

Note) Sample numbering marked with * is not included in the scope of the present invention.

As is clear from the results shown in the table, adding manganese (Mn) as a subcomponent increases both the bending strength and the capacitance-resistance product, while maintaining a low dielectric loss value, which is highly reliable. It can be seen that an excellent high dielectric constant ceramic composition can be obtained.

The ceramic composition of the present invention, which exhibits these excellent properties, has a low sintering temperature of 1000°C or less, which makes it possible to reduce the cost of the internal electrodes of multilayer capacitors, as well as save energy and furnace materials. It also produces excellent effects.

It should be noted that if the main component compounding ratio X is less than 0.5 ohms, the capacitance-resistance product will be smaller than the standard value and the induced tt loss will also exceed 5.0%, which is not practical. Furthermore, if the amount of manguin (Mn) added as a subcomponent is less than 0.01 atom 96, the effect of improving the bending strength will be small, and if it exceeds 1 atom H, the bending strength will become so small that it is not practical.

Claims (1)

[Claims] Magnesium Tungsden i! Lead (Pb(Mg%W3
．． 4) A binary composition consisting of Os) and titanium lead (PbTIOs) (Pb(Mg3(W3())
J3) X (Pb'i 103 )I When expressed as A porcelain composition characterized in that it contains 0.01 to 1 atomic percentage of .