DE1255560B - In a composite, plane-parallel, electrical substrate usable ceramic made of at least two joined masses with different electrical properties - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. α .:

C04b

German class: 80 b -8/135

Number: 1 255 560

File number: G 36082 VI b / 80 b

Filing date: October 4, 1962

Open date: November 30, 1967

The invention relates to an in a composite, plane-parallel electrical substrate usable ceramic made of at least two joined together Grounds with different electrical properties, one of which is a non-ohmic ground with a certain content is calcium titanate, magnesium zirconate and barium zirconate and the other is made up reduced titanates with a certain content of barium titanate.

A ceramic of the aforementioned composition, in which one mass has a high dielectric constant has, while the other mass has a low dielectric constant, is already known and represents a composite i? C unit.

With this known ceramic, however, it has been possible to date without undesired influencing of the electrical Properties of the ceramic do not achieve sufficient compatibility of the two masses. About that in addition, the constituents of the high dielectric constant mass could only be within within a narrow range, otherwise the electrical properties will be adversely affected occurred.

It has now been found, unexpectedly, that in a ceramic of the type mentioned chemical compatibility of the two materials and the compatibility of the two materials during the Firing process can be improved if you consider the mass consisting of reduced titanates Oxides of rare earths added.

The invention therefore relates to a ceramic of the type mentioned at the outset, which is according to the invention characterized in that rare earth oxides are added to the mass of reduced titanates, to make the masses compatible with regard to their chemical properties and their burning behavior do.

It is already one of titanates, zirconates and reduced titanates and possibly oxides Dielectric ceramics composed of rare earths are known, but which have a uniform composition has, so that the problem of chemical compatibility as well as compatibility in firing does not occur in this known ceramic.

The invention will now be explained in more detail with reference to drawings; in these shows

1 shows a view of an electrical component, which contains the ceramic according to the invention and is provided with a protective coating,

F i g. 2 shows a view of the component according to FIG. 1 before applying the protective layer,

In a composite, plane-parallel,
electrical substrate usable ceramic
of at least two masses joined together
with different electrical properties

Applicant:

Globe-Union, Inc., Milwaukee, Wis. (V. St. A.)

Representative:

Dipl.-Ing. M. Licht and Dr. R. Schmidt,

Patent Attorneys, Munich 2, Theresienstr. 33

Named as inventor:
Alfred Safay Khouri, Milwaukee, Wis .;
ao Howard Urban Taylor,

Thiensville, Wis. (V. St. A.)

Claimed priority:
V. St. v. America October 5, 1961
(143198),

dated July 26, 1962 (214 446) - -

F i g. 3 shows a side view of the component according to FIG. 2,

F i g. 4 shows a view of the component according to FIG. 1 from below;

F i g. Fig. 5 is a circuit diagram of the in Figs. 1 to 4 inclusive shown component.

The resistance-capacitance coupling network shown therein will now be explained with reference to the drawings; it contains a ceramic base plate or support 10, which consists of a single, assembled piece with end parts 12, 14 and a middle part 16 (all shaded by lines) and parts 18 and 20 between them in the same plane; 12, 14 and 16 are formed from a reduced titanate ceramic semiconductor material having a high dielectric constant; 18 and 20 consist of two non-ohmic ceramic parts with a low dielectric constant. Ceramic bodies with adjacent parts in one plane, which nevertheless have different electrical properties, are described and claimed in U.S. Patent 2,794,940. Certain ceramic mixtures with a low Ä ",

709 690/477

described in that patent can be used in the manufacture of the composite baseplate 10 as well as other ceramic mixtures, as will be described in more detail below. However, the ceramic composition used in parts 12, 14 and 16 with reduced titanates and compatible with parts 18 and 20 with low K is different from the ceramic compositions with high K disclosed in the referenced patent, especially because of the addition of a predetermined amount of rare earth oxides. The ceramic composition of shaded portions 12, 14 and 16 is a reduced titanate essentially of the type described and claimed in U.S. Patent 2,841,508. An example of compositions for the high K semiconductor parts which have given satisfactory results are as follows:

Table I.

material 1 2 3 4th 5 6th BaTiO ₃ , «> /,
CaTiO ₃ ,%
SrTiO _{3, ^0/0}
MgZrO ₃ ,%
BaZrO ₃ ,%
CaZrO ₃ , ° / ₀
PbTiO ₃ , ° / ₀
Oxides of rare earths, ° / ₀ ... 84.5
15th
0.5 89
1.0
10
0.5 68
7th
15th
10
0.5 60
15th
25th
0.5 66
10
12th
2.0
0.5 70.5 to 71.0
7.3
9
0.7
11.5 to 12
0.5

Parts 12, 14 and 16 made from these compositions have the necessary electrical properties to perform the function of the high K semiconductor dice and are nonetheless compatible with the low K parts. As can be seen, the particular composition may be varied significantly while maintaining acceptable electrical properties; however, it should be noted that each of the samples contains barium titanate (BaTiO ₃ ) and rare earth oxides. The other materials calcium titanate (CaTiO ₃ ), strontium titanate (SrTiO ₃ ), magnesium zirconate (MgZrO ₃ ), barium zirconate (BaZrO ₃ ), calcium zirconate (CaZrO ₃ ) and lead titanate (PbTiO ₃ ) are added as desired. In practice it has been found that satisfactory results can be obtained from ceramic mixtures containing the following materials within the indicated ranges:

Table II

material

BaTiO ₃

CaTiO ₃

SrTiO ₃

MgZrO ₃

BaZrO ₃

CaZrO ₃

PbTiO ₃

Rare earth oxides

60 to 90 0 to 25 0 to 25 Obis I 0 to 18 0 to 13 obis 5

0.2 to 1.2

35

40

45

55

Regarding the oxides of rare earths, so preferably 0.5 ° / ₀ are used; however, satisfactory results can be obtained using amounts within the indicated range. It must be ensured that the particular ingredients of the mixture and their amounts are selected so as to ensure certain required electrical characteristics, capacitance, power factor and resistance and their required values.

Examples of low K ceramic mixes for parts 18 and 20 that are compatible with the above compositions are as follows:

Table III

material 1 2 3 4th 5 BaTiO ₃ , »/ ο
CaTiO _{3 ^0/0}
SrTiO ₃ , e / o
MgZrO ₃ ,%
BaZrO ₃ , ° / _{0
CaZrO.sub.3, ^0/0} 3
77
2
18th 44
36
2
18th 56
21.5
16.5
0.5
5.5 65
18th
1
14th
2 71
7.3
9
0.7
12th

Parts 18 and 20 made from the above compositions are compatible with the high K materials in Table I and, after being fired as described below, have the necessary electrical properties to perform their function as low K pieces to meet. As can be seen in Table III, the particular composition of the low K ceramic mixtures can be varied significantly while maintaining acceptable electrical properties; Satisfactory results have been obtained using blends in which the materials are within the following ranges:

Table IV ° / o material O to 71
7 to 77
0.5 to 2
5 to 40
O to 17 BaTiO O to 10 CaTiO ³ MgZrO ₃ ... BaZrO ₃ ... SrTiO ₃

It should be noted that while BaTiO _{3 is} preferred, it can be omitted if desired

and yet a satisfactory result can be achieved. Again, note that the special ingredients and their quantities are selected so that certain required electrical properties, Capacity, power factor and resistance and their required values can be guaranteed.

Certain compositions of high and low K ceramics can be combined as desired to form a planar plate having the preferred combination as in Example 6 of Table I and Example 3 of Table III. The flat plate can be molded in the manner described in U.S. Patent 2,794,940; it is ripe fired in air at a temperature of around 1350 ° C. After this firing, the shaded parts 12 to 16 of the plate do not yet have the properties of a semiconductor. The plate is then reburned at a temperature of 1175 ° C. in an atmosphere containing hydrogen or carbon monoxide, or in other reducing atmospheres, in order to reduce parts 12, 14 and 16 and thus develop the continuous semiconductor properties. The intermediate low K portions 18 and 20 have a dielectric constant of about 1300.

In some applications it is desirable to keep the K of the low K parts as small as possible; for this purpose it has been found that a K down to 100 to 120 can be achieved by a body which is compatible with the parts made from reduced titanates. An example of a ceramic mixture for such a body is:

material

BaTiO ₃

CaTiO ₃

SrTiO ₃

MgZrO ₃

BaZrO ₃

Oxide mixtures of rare earths

10.0 48.0

2.0 40.0

This low K ceramic blend is similar to that of Table III in that it also includes barium titanate, calcium titanate, magnesium zirconate, and barium zirconate.

After the reduction firing, the front surface of the plate 10 is then provided with silver-printed electrodes in a manner known per se in capacitor technology. Electrodes 22, 24 and 26 are attached to the reduced titanate parts 12, 14 and 16 and are electrically connected by conductors 28 and 30 attached to the low K parts 18 and 20. These electrodes and conductors can be applied to the surface as a continuous silver print pattern as shown in the illustration. Electrodes 32, 34 and 36 are also attached to the reduced titanate parts 12, 14 and 16 as shown. They lie in one plane with the electrodes 22, 24 and 26 and form with them (due to the edge effect) capacitances which are denoted by C ₁ , C ₂ and C ₃ in FIG. 5 are designated.

Electrodes 32, 34 and 36 are electrically connected to tabs 38, 40 and 42 which are printed in low K silver on parts 18 and 20 as shown. The flags can be applied with the electrodes 32, 34 and 36 as parts of the same silver print pattern. Another, separate terminal lug 44 is attached to part 20 with low K , and a special resistance strip R ₂ (shown in dotted lines) made of carbon resistance layer is screen-printed in a manner known per se on part 20 with low K and connects the conductor 30 with the terminal lug 44. The parts with low K are thus

ίο used to lay the foundation for the conductors and terminal lugs and to form the base for the resistance strip and so well soldered connections enable.

Since the capacitances C ₁ , C ₂ and C ₃ arose on the semiconductor parts and their dielectrics are formed by extremely thin boundary layers, each has a high capacitance in relation to its physical size. The encapsulated unit, as seen in Fig. 1, has small dimensions of 20 10 X 3.6 mm. Assuming a typical operating voltage of 0.5 volts, these capacitors have values of 0.01 F to 2.0 F and the resistance R ₂ is in the region of about 10,000 ohms.

a5 A with R ₁ in F i g. 5 is created between the electrodes 26 and 36 and balanced by partially grinding off adjacent parts of these electrodes or by point soldering or soldering of the adjacent surfaces of these electrodes on the parts indicated by the cross-marked areas 46 and 48. The value of this resistor in this example is 300 ohms. However, resistances of 20 ohms to 20 megohms can also be achieved in this way. The required resistance is produced without the addition of body structure or without special accessories; therefore, the miniature character is preserved and the price is reduced. It is believed that the resistance is created when a portion of the non-ohmic interface under the portion of the electrode that is being abraded or soldered is excluded. At such a point, the electrodes behave like ohmic metal resistors on semiconductor material. The value of the resistance /? _a can be obtained using the formula

determining where ρ is the resistivity of the semiconductor material at a DC voltage below which the electrical resistance capacitor circuit element is to be used; L is the distance or the geometric center distance and A is the average area of the two above-described areas of the capacitor electrodes which represent the ohmic contacts.

The specific ohmic resistance can be brought to a value between 50 and 1000 ohm · cm and be mastered. By calculating the capacitor electrodes and their sections to be treated and the dimensions of the semiconductor material separating the respective electrode parts, the Values for the resistor and the capacitor can be predetermined.

From the foregoing it will be seen that when handling the unit and when installing the Wire connection 1 on the terminal lug 38, des

7 8

Wire connection 2 on conductor 28, of the wire BaTiO ₃ 0 to 71

Final 3 at the terminal lug 42, of the wire CaTiO ₃ 7 to 77

Final 4 at the terminal lug 44 and the wire MgZrO ₃ 0.5 to 2

connection 5 on the connection lug 40 in accordance with BaZrO ₃ 5 to 40

must be taken, not the boundary layer under 5 ". ,,.,,. , _. ,,,

destroy the electrodes. One way of doing this. 3 Ceramic according to Claim 2, characterized in

achieve is, first of all, an inactive print layer. ^Ζ ™ ίΤΐ? J? R ™ Tu % l? Tt ΪΤ

to pull over these electrodes. During start-f ^ ° to 25 "/ ₀ CaTiO 0 to 25% SrTiO _3, O to

Bringing the wire connections in the immersion bath, the J, ° / o MgZrO »O to 18 ° / _e BaZrO ₃ , O to 13 · /,

Lot on such a precautionary i. ^Ca ? ^r0 3 ^and °> ⁵ ° / o ^PbT > ° 3 contains undassi the

Coating does not hang, so it has no influence on ^mC ^ ^m Tn t, ^ λ l ° t '° ³

the boundary layer. Such a coating also protects and O b) s _10/0 contains CaZrO ₃

the electrodes before grinding during the treatment. \ ^Κβ ^? Λϊτ ^Ans P ^ruch \ ' thereby identified

in the following operations. If the unit f \ ^chn f ' ^that ^ e mass of reduced titanates

is finished, it is contains ^end by an isolate 15 ^fol S ^{shares m} percent by weight in a conventional manner:

encapsulated coating. BaTiO ₃ 70.5 to 71

CaTiO ₃ 7.3

SrTiO ₃ 9.0

Claims (2)

Claims: MgZrO3 0.7 20 BaZrO3 12.0 to 11.5 1. In a composite, plane-parallel oxide mixture of electrical substrate usable rare earth ceramic 0.5 at least two joined masses with verb ,, ". · -ii , +, _r , ja .. ·" different electrical properties, of which ^{and that the} Mchtohmsche mass the following proportions one of which contains a non-ohmic mass with a weight percent of approx. 5 ^m: correct content of calcium titanate, magnesium BaTiO ₃ 56 zirconate and barium zirconate and the other is CaTiO ₃ 21.5 one from reduced titanates with a certain SrTiO ₃ 16.5 th content of barium titanate, thereby MgZrO ₃ 0.5 characterized in that the mass of redu- 30 BaZrO ₃ 5.5 adorned titanate oxides of rare earths added _{r T} , ..,. , _Λ,, . , are to the masses in terms of their chemical 5 ceramics according to claim 1, characterized in The properties and their burning behavior are shown by the fact that the mass consists of reduced titanates träglich to make ^the S ^balance weight percentages as defined in claim 4 2. Ceramic according to claim 1, characterized in 35 ^and _u ^{that the nich} t ° h ^{msche mass fol} g ^ends drawn that the mass of reduced titanates contains weight percentages: the following composition in percent by weight BaTiO ₃ 10.0 has: CaTiO ₃ 48.0 BaTiO ₃ 60 to 90 MgZrO ₃ 2.0 Oxides of rare earths 0.2 to 1.2 * ° HaZrO ₃ ^4υ > ^υ while the non-ohmic mass together- Considered publications: is set from U.S. Patents No. 2,841,508. 2,794,940. 1 sheet of drawings