JPS6032344B2 - Grain boundary insulated semiconductor porcelain capacitor material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a grain boundary insulated semiconductor ceramic capacitor material,
In particular, its tan6, insulation resistance, temperature characteristics, and DC bias voltage characteristics are improved.

In recent years, in polycrystalline sintered bodies, capacitive elements have been manufactured using protective layers formed on the surface of semiconducting crystals by selectively insulating the grain boundaries of semiconducting crystals. It is generally known that capacitors can be obtained with significantly higher dielectric constants than ceramic capacitors. This is called a boundary layer capacitor, and its main components are barium titanate and strontium titanate. Barium titanate-based boundary layer capacitors are those whose main components are barium titanate and barium titanate solid fused solids obtained by solidifying strontium titanate, barium stannate, etc., and this type of capacitor has a dielectric constant of 50,000 to 50,000. A very large capacitor of 80,000 was obtained, providing a small capacitive element. However, this type of barium titanate-based boundary layer capacitor has a large n6 of 3 to 5% and a capacitance temperature characteristic of -25%.
In the temperature range of ~185°C, the capacitance at 20°C shows a change of about ±30%, and the bias voltage dependence is that when the DC bias voltage is 25V, the capacitance when the bias voltage is 0 is about 25%. % decrease, which limited its practical usefulness as a capacitor.

Also, strontium titanate boundary layer capacitors are ta
When n6 is 1 to 3%, the capacitance change rate in the temperature range -25 to 18,500 °C is about 15%, and the change rate due to DC bias voltage is about -8% at 25V, and the barium titanate-based boundary layer It is superior to capacitors or general porcelain capacitors, but its dielectric constant is approximately 300.
00 is not sufficient for making a 4-type capacitor, and is inferior in terms of capacitance and insulation compared to a film capacitor. Also recently, SrTi03 has Nb05, Ta2Q,
Semiconductorization accelerators such as W03, Y2Q, Dy203 and Zn0 are added and sintered in a reducing atmosphere to form Bi203.
Alternatively, a strontium titanate boundary layer capacitor obtained by diffusing a mixture of Bi203, Pb○ and B203 has been invented, but this type of capacitor has a large dielectric constant of 35,000 to 50,000, and the n6 is 1%.
Below, the insulation resistance is 2×1 and more than 0Q−, and the temperature characteristics are also extremely excellent at about ±15% in the temperature range of −25 to 185° C. However, this type of capacitor has a very high firing temperature of 1,400 to 1,500 degrees centigrade, and its characteristics vary greatly depending on the firing temperature, making it difficult to control mirror formation during manufacturing. The present invention is based on [(1-x) S of 1x/2Bi2
030 Ti02] (where x is Bi2 for Sr0
A composition obtained by adding Zn○ to a composition represented by a molar fraction of 0.03 molar fraction) was sintered, and then Bi203 was diffused into the grain boundaries of the semiconductor porcelain obtained by forced reduction. A strontium titanate grain boundary insulated semiconductor ceramic capacitor characterized by insulating a strontium titanate grain boundary layer capacitor, which has a large dielectric constant and a ta
A grain boundary insulated semiconductor ceramic capacitor that can be obtained by easily bonding a capacitor with small n6, high insulation resistance, and excellent temperature characteristics and DC bias voltage characteristics at a temperature of 1250 to 135000 without requiring difficult temperature control. It provides materials.

Hereinafter, the present invention will be explained in detail based on examples.

The present invention is [(1-x) S no 10
] (where x is the molar fraction of Bi203 relative to Sr0) When y mol% of Zn○ is added to the composition, SrC03, Ti02, After weighing Bi203 and Zn○ in accurate proportions, wet mixing is performed, and then 11
4000 for 2 hours to cause decomposition and solid phase reaction of the raw material powder, and the resulting reaction product powder was pulverized in a ball mill to obtain an adjusted raw material powder.

3. Add polypinyl alcohol to this adjusted raw material powder. % by weight was added to form granules, and the mixture was pressure-molded into a disk shape at a pressure of 1200 k9/ground, and the mixture was heated to 1250 to 1350 oo in air.
It was baked for 4 hours. Furthermore, the porcelain was placed in hydrogen at 130 ml.
Approximately 14 ribs in diameter after 2 hours of reduction with Pi○? A disk-shaped semiconductor porcelain having a thickness of 0.6 mm was obtained. Next, Bi203 was applied to the porcelain surface.
The powder was applied 5 to 20 times 9 times and heat treated in air at 1300°C for 2 hours to diffuse Bi203 into the grain boundaries and insulate the grain boundaries. A silver paste was applied thereto, dried, and fired at 800q○ for 3 minutes to form a silver electrode. Table 1 shows the results of measuring the electrical characteristics of each sample of the cosodensor thus prepared. In addition, when measuring the sample, the capacity and tan6
is measured using a capacitance bridge at a frequency of 1kHz and an input signal voltage of IVnns, and the insulation resistance is measured using an insulation resistance meter after applying 50V DC for 1 minute.
The temperature characteristics showed the rate of change in capacity at each temperature based on 2000. Also, the specific power transfer rate (r) is 14.4 x capacity (pF) x
The thickness (arc) was calculated using the formula: diameter x diameter (arc).

Table 1 Note that in Table 1, sample numbers 1, 7, 8, and 15 are outside the scope of the present invention.

Sample number 9 is the same sample as 3. Sample number 2, 3, 4
, 5, 6, 9, 10, 12, 13, and 14, the relative dielectric constant is as large as 35,000 to 62,200, and t
An8 is 1.0% or less, insulation resistance is as large as 50×1 piQ-skin or more, and temperature characteristics are extremely excellent, with the soil being within 16%.

Also, in terms of DC bias voltage characteristics, -8 at 25V
Good values were obtained, such as within % and within -20% at 50V.
Further, when comparing the characteristics of each sample number, it is found that the insulation resistance is high, and the dielectric constant and tan6 are hardly affected by the freezing temperature, which is extremely favorable in terms of manufacturing. The porcelain dielectric composition of the present invention has crystal grains of 70
It was a polycrystalline body with clear grain boundaries and uniform particle diameters.

This is considered to be because the addition of Bi203 greatly contributed to the growth of crystal grains and the formation of grain boundaries, and the addition of Zn○ contributed to making the crystal grains uniform and lowering the firing temperature. By the way, Buddha 203, Dy203, Y203, Nb24, Ta205
In a ceramic composition in which Zn0 was added at the same time as Zn0, the crystal grain size was irregular, with a coexistence of giant crystals of about 100 Buddhas and small crystals of several Buddhas m to loAm, and depending on the firing conditions. It was difficult to make the crystal grains uniform. In addition, from the above results, the grain boundary insulated semiconductor ceramic capacitor material of the present invention has a composition range of 0.00 in the x, y composition range.
7Sxmi0.011 and 2.27≦ySII. To explain the reason why it is limited to 35, the range where x is smaller than 0.007, the range where x is larger than 0.011, and y
is smaller than 2.27, sample numbers 8 and 1 in Table 1
Samples 5, 1, and 1 have a small dielectric constant and do not satisfy the object of the present invention. Further, in a range where y is greater than 11.35, as shown in sample number 7, the specific electrical constant is large and tan6 is small, but the insulation resistance is small, making it unsuitable as a boundary layer capacitor. In the examples, B;203 was used as the diffusion material, but similar characteristics can be obtained by using a mixture of C, Pb, and Bi.

As explained above, the grain-boundary insulated semiconductor ceramic capacitor material according to the present invention can be used not only for conventional ceramic capacitors, but also for boundary layer capacitors by significantly improving tan6, insulation resistance, temperature characteristics, and bias voltage characteristics. In addition to having excellent properties, the sintering conditions can be easily controlled, and extremely new and useful electronic components can be provided.

Claims (1)

[Claims] 1 x is in the range of 0.7 to 1.1 mol% (however, x is S
molar fraction of Bi_2O_3 with respect to rO) [(1
-x) SrO+x/2Bi_2O_3+TiO_2] with 2.27 to 11.35 mol% of ZnO
Grain boundary insulated semiconductor ceramic capacitor material made by adding additives.