JPS6033255A - 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, and particularly to 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 magnetic compositions containing aTiO3 as a main component have been widely put into practical use. However, those whose main component is barium titanate (BaTi03) have a sintering temperature of usually 1300 to 1400°C. Therefore, when using this material in a multilayer capacitor, a material 2 that can withstand this sintering temperature must be used as the internal electrode, such as an expensive noble metal such as platinum or palladium, which has the disadvantage of high manufacturing costs. be. In order to manufacture multilayer capacitors at low cost, it is necessary to have a porcelain composition that can be sintered at as low a temperature as possible, especially at 1000° C. or lower, so that inexpensive metals mainly composed of silver, nickel, etc. can be used for the internal electrodes.

By the way, when producing a practical multilayer capacitor using a porcelain composition, many items regarding the electrical properties of the porcelain composition must be evaluated.

Generally, it is required that the dielectric constant be as large as possible, the dielectric loss as small as possible, the resistivity as large as possible, and the temperature change in the dielectric constant as small as possible.

However, for practical purposes, multilayer capacitors require values such as capacitance, rate of change of capacitance with temperature, and dielectric loss, rather than permittivity. In a multilayer capacitor, the capacitance 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 in order to obtain a constant capacitance, the dielectric constant of the porcelain composition must be adjusted. Size is not necessarily an absolute factor. Furthermore, the temperature change rate of capacitance (temperature change rate of dielectric constant) has various allowable ranges depending on the application, and the temperature change rate of dielectric constant of the ceramic composition is also an absolute factor when manufacturing multilayer capacitors. Not.

On the other hand, there is a regulation that the dielectric loss must be below a certain value depending on the application, and is at most 50 inches or less at room temperature. Furthermore, regarding specific resistance, as stated in the EIAJ standard [Japan Electronics Industries Association's Multilayer Ceramic Capacitors (Chip Type) RC-3698B], the insulation resistance of a multilayer capacitor must be ioooooMQ or more or the capacitance-resistance product. It is specified as 500μF・MΩ or more, whichever is smaller. In other words, unless the product of the dielectric constant and resistivity of the ceramic composition exceeds a certain absolute value, it is impossible to make a capacitor of any capacitance, especially a capacitor with a large capacitance, meet practical standards, and its uses are extremely limited. It 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 of the single layer is C6 and the insulation resistance is Ro, then the capacitance C of the multilayer capacitor is n times C0, and the insulation resistance is 1 of R6.
/ becomes n. Here, the permittivity of the magnetic composition is ε, and the permittivity of vacuum is 6°.

If the specific resistance of the ceramic composition is ρ, the thickness of the ceramic of the single-layer capacitor is 62, and the area of the overlapping electrodes is 8, then 00 of the single-layer capacitor is (ε.εS)/dJ) Re is (ρd)
/S. Therefore, the product of capacitance (C) and insulation resistance (CXR) of a multilayer capacitor consisting of n layers is [(ρd)/(n
s) )' X ((n layer.εs)/ci)−ε0ερ
becomes.

In other words, the capacitance of a multilayer capacitor of any capacity is
The resistance product (CXR) is normalized to a constant value (ε.ερ) obtained by multiplying the product of ε and ρ of the ceramic composition by 6°. If the capacitance/resistance product CXR is 500 μF-MΩ, that is, 500 F·Ω or more, ε. = 8B55 Xl0-14p/c
myosi, CX R= g. ερ= 8.855X 1O
-14(F/cI+L)×ε×ρ≧500F−Ω, therefore, there is a requirement that ερ≧5.65×10111Ω·a.

For example, ε=1ooo.

Then ρ = 5.65 x 10”Ω・ε = 300
For 0, ρ≧1, 88 x 10"Ω·a, ε; for 500, ρ=1.13 x 10"Ω·a is required. Any large capacitance multilayer capacitor made of a ceramic composition having ρ greater than these values depending on the dielectric constant will have a capacitance-resistance product of 500 μF-MΩ. If ε is 3000
ρ is one order of magnitude lower than the required value, 1.88X 10"%'-f
If i is ε. = 50μF-MΩ and 500μF-MΩ
is not satisfied, and in order to satisfy the standard value of insulation resistance of 1100OOΩ, that is, 1010Ω or more, the capacitance C must be 0.
．． Must be limited to 0.005 μF or less. The capacitance-resistance product (CXR) of this multilayer capacitor is always 5.
It shows 0μF・MΩ, so when the value is 1100OOΩ, C is 0.005μF, and if C is larger than this, R is smaller than 1000OOΩ, which is 0.005μF.
This is because this is the highest capacity that satisfies the standard. Therefore, if the specific resistance of the ceramic composition is low, the practicality of the material is 2%, and the advantages of small size and large capacity, which are the characteristics of multilayer capacitors, cannot be utilized, 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.

In addition, in the case of multilayer chip capacitors, when the chip capacitor is mounted on a board, due to the difference in thermal expansion coefficient between the board and the ceramic composition that makes up the chip capacitor,
Mechanical strain is applied to the chip capacitor, which may cause cracks or damage to the chip capacitor. 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 mechanical strength of the porcelain forming the capacitor is low, making it susceptible to cracks and damage, resulting in low reliability.

Therefore, it is of practical importance to increase the mechanical strength of porcelain as much as possible.

By the way, P b (Mgl/2W1/2)03 pb
'rto3 porcelain compositions have already been developed by N.N.Krajnik and A.A.I.Agranovskaya (N, N, K.
rainikand A, 1. Agranovska
ya(Fi:ziko Tverdog.

Te1a, To, 2. NOI, pp70-72
．． Janvara (1960))) was proposed, 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 unclear. Also (8rxPbl-x'
rtos) a(PbMgo, a%, aos)6 (where x = O ~ 0.10, a is 0.35 ~ 0.5
．． b is 0.5 to 0.65, and a + b =
1] is disclosed in Japanese Patent Application Laid-Open No. 52-21662 as a monolithic capacitor and a method for manufacturing the same,
A dielectric powder composition is also disclosed in JP-A-52-21699. Here again, the characteristics of the composition are that the dielectric constant is about 2000 to 8000 and the dielectric loss is 0.5%.
There is a description of ~5.0cm, but there is no description of specific resistance or capacitance-resistance product, so the practicality was unclear. Furthermore, Pb(Mgl/2W□/2)03 and P b T
i O3-based composition, P b (Mgl
/2W□/2) Os is 20.0 to 70.0 mol%, Pb
JP-A-55-144 discloses a high dielectric constant ceramic composition characterized in that a TiO3 content in the range of 30.0 to 80.0 mole is added with an amount of MgO of 30% or less of the calculated value.
It is disclosed as Publication No. 609. However, even in this patent, there is a description of the temperature characteristics of the dielectric constant in the tl, which states that the dielectric constant is about 2300 to 7100 and the dielectric loss is 0.3% to 2.1%, but there is a description of the specific resistance or the capacitance-resistance product. However, the practicality of this composition is not clear. Next, we have already shown that Pb (Mg 1/2 Wl/2)O can be sintered at temperatures between 910 and 950 °C.
s and PbTiOs system, this is (Pb (
Mg172Wl/2)03), (pb'rio
, )t −8, then X is 0.65< x≦
Compositions in the range of 1.00 are proposed. This composition has a high product of dielectric constant and resistivity of 5.65XIO"Ω・1 or more, and has excellent electrical properties with low dielectric loss. However, composition 17 has Since both 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 1 ooo'c, and the product of dielectric constant and specific resistance is 5.65.
X 10! IlΩ・OR (i.e. capacitance-resistance product i15
The purpose is to provide a porcelain composition that has a high value of 00μF・Mg) or more, has excellent electrical properties with low dielectric loss, and also has high mechanical strength. (Mg 1/2WL/2
)03] and lead titanate (PbTi0. ) as P b (Mgl/2W□/2)Ox ) x
(p bTto, ) When expressed as 1-x,
Manganese lead tungstate Pb (M
n2/aW1/a) Ox from 0.05 to the main component
It is characterized by containing 2 mo1%.

The present invention will be explained in detail below using examples.

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

Magnesium oxide (Mgo), tungsten oxide (WO
3)? Titanium oxide (Ti02) and manganese carbonate (MnCOa) are used, and each is weighed so that the mixing ratio shown in the table is achieved. 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 16 m. ! Four disks each having a diameter of 11° and a thickness of approximately 2M and a cylinder having a diameter of 16m and a thickness of approximately 10 mm 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 a digital LCR meter was used to measure the frequency of 1).
Capacitance and dielectric loss were measured at G(z, voltage I Vr *m+ s, temperature 20°C, and dielectric constant was calculated. Next, a voltage of 50 V was applied for 1 minute using a super insulation resistance tester to measure the insulation resistance at temperature 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 Q, 5 m was
, 10 rectangular plates with a width of 2 mm and a length of approximately 13 m were cut out.

The distance between the supports is set to 9 m, and the breaking load Pm (Kp) is calculated using the three-point method.
) is measured, t is the thickness of the sample, and W is the width of the sample. The electrical properties are the average values of 4 disk samples, and the bending strength is the average value of 10 rectangular plate samples.
Calculated from the average value of the points. The main component of the porcelain obtained in this way (Pb(Mg1/2W1/z)On) x(Pb
TiOs:h-z compounding ratio
(expressed as 0ερ) is shown in the table.

As shown in the table, it is clear that manganese lead tungstate (Pb(Mn2/aW)
By adding 't/a)Or), it is an excellent high-permittivity porcelain that increases both the bending strength and the capacitance-resistance product, and also maintains a low dielectric loss value, and is highly reliable and highly practical. It can be seen that a composition is obtained.

The porcelain 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, and also to save energy and furnace materials. Excellent effects also occur.

If the main component compounding ratio X is less than 0.5, the capacitance-resistance product will be smaller than the standard value and the dielectric loss will also exceed 5.0, which is not practical. It is also a subcomponent.

If the amount of Pb(Mn2/3W1/3)On added is less than 0.05 moJ*, the effect of improving the bending strength is small, and if it exceeds 2 mo1%, the bending strength becomes too small to be practical.

Claims (1)

[Claims] Magnesium lead tungstate (pb (Mgl/2W
1/2) O3) and lead titanate (PbTiO,) (Pb(Mgl/2W1/2)03)
, (PbTiOs) 1-x, where X is within the range of 0.50≦X≦1.00, manganese lead tungstate (Pb(Mn
2/3W1/3)03) from 0.05 to the main component
A porcelain composition characterized in that it contains an additive content of 2ml/1%.