US3068438A - Multiple resistance characteristic semi-conductor elements - Google Patents

Description

Dec. 11, 1962 J. E. RQLLINS 3,068,438

MULTIPLE RESISTANCE CHARACTERISTIC SEMI-CONDUCTOR ELEMENTS Filed Feb. 17, 1960 INVENTOR JAMES E R L ATTORN EY United States Patent 3,068,438 MULTIPLE RESISTANCE CHARACTERISTIC SEMI-CONDUCTOR ELEMENTS James E. Rollins, Newark, N.J., assignor to Specialties Development Corporation, Belleville, N.J., a corporation of New Jersey Filed Feb. 17, 1960, Ser. No. 9,270 1 Claim. (Cl. 338-22) The present invention relates to semi-conductor elements, and more particularly, to such elements having two or more resistance values at a given temperature.

Heretofore, it has been proposed to make semiconductor elements such as thermistors and varistors by embedding a pair of parallel spaced apart electrically conductive terminal wires in a body formed of a resistance material to provide a known resistance across the wires at given temperatures. In certain types of networks, a number of such elements may be required which add to the cost of the components and the assembly thereof in the network. Also, since the resistance of each element at a given temperature is fixed, the elements can only be used where the particular resistance is called for.

Accordingly, an object of the present invention is to provide such elements which have more than one resistance value at a given temperature.

Another object is to provide such elements which carry out the function of two or more previously individually used elements.

Another object is to provide such elements which have both thermistor and varistor characteristics.

A further object is to provide such elements in a simple, practical and economical manner.

Other and further objects of the invention will be obvious upon an understanding of the illustrative embodiment about to be described, or will be indicated in the appended claim, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice.

In the drawing:

FIG. 1 is an enlarged sectional view of a semiconductor element illustrating one embodiment of the invention.

FIG. 2 is an end elevational view looking at the element shown in FIG. 1 from the left.

FIG. 3 is a view similar to FIG. 2 of an element illustrating another embodiment of the invention.

FIG. 4 is a view similar to FIGS. 2 and 3 of an element illustrating still another embodiment of the invention.

Referring to FIGS. 1 and 2 of the drawing in detail, there is shown a semi-conductor element which generally comprises a bead-like body and terminal wires 11, 12 and 13 embedded in the body and extending outwardly therefrom.

The body may be formed of any suitable resistance materials such as metallic oxides which have thermistor and/or varistor characteristics. Examples of such materials are disclosed in United States patent application Serial No. 6,422, filed February 3, 1960, and assigned to the assignee of this application. The following examples are disclosed in the above application:

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Example III Percent by weight Manganese dioxide 80 Cupric oxide 20 Example 1V Manganese dioxide Cupric oxide 30 Percent by weight Manganese dioxide 70 to 96 Cupric oxide 30 to 4 The wires may be formed of platinum; an alloy sold by The International Nickel Company, Inc. under the trademark Inconel and consisting essentially of between about 6% and about 17% by weight of iron, between about 11% and about 18% by weight of chromium and the balance nickel at a minmum of 70% by weight; or an alloy sold by Driver Harris Co. under the trademark Nichrome and consisting essentially of between about and about by weight of nickel and between about 20% and about 15% by weight of chromium.

In order to provided the element with diiterent resistance characteristics across diiferent pairs of wires as contemplated by the present invention the wires 11, 12, and 13 may be spaced apart different distances with respect to each other. For example, the distance A between the wires 11 and 12, the distance B between the wires 12 and 13, and distance C between the wires 11 and 13 could be of an increasing magnitude in the order named. The difference in distance could vary considerably in order to attain pronounced difierent resistance, characteristics so that, for example, the element could be used where one, two or three units of resistance are required, that is, R, 2R or 3R.

Also, in utilizing certain manufacturing techniques, it is diflicult to reproduce two wire elements having exactly the same resistance value. Thus, by spacing one pair of wires (12, 13) the distance calculated to reproduce desired resistance values and spacing one other pair of wires (11, 13) a slightly greater distance and spacing a third pair of wires (11, 12) a slightly lesser distance, at least one of the pairs of wire should provide the resistance sought to be reproduced.

The foregoing efiects also may be accomplished by varying the diameters of the wires 11, 12 and 13 or by using wires having different resistivities due to the oxide formed when sintering the body on the wires. Thus, by using difierent combinations of resistivities, dilferent resistances can be provided across different pairs of wires.

In FIG. 3, Wires 14, 15 and 16 are shown spaced apart .the same distance D with respect to each other and as being of equal diameter to provide three equivalent resistances across the wires 14-15, 14-16 and 1516, respectively. Here again, the resistance values could be varied by using wires of difierent diameters or different materials in a symmetrical arrangement.

Also, in a symmetrical arrangement of wires of like diameters and materials, a resistance unit could be established within the element having one half the resistance across any pair of wires. This may be accomplished by connecting any two of the wires at one end, for example, the wires 14 and 16, so that the Wires 14 and 16 provide a common terminal and the resistances between the Wires 3 and 14 and 15 and 16 are connected in parallel. Thus, from the formula where r and r; are equal and can be expressed as r,

Other combinations of individual and parallel resistance values could be provided by asymmetrically arranged wires or wires of dissimilar materials.

In connection With the invention disclosed in the aforementioned patent application, it has been found that, with certain combinations of metallic oxides providing the resistance material of the body such as manganese dioxide and cupric oxide, the material between a pair of platinum or Inconel wires has the characteristics of a thermistor whereas the same material between a pair of Nichrome wires has the characteristics of a varistor. Thus, with an arrangement such as shown in FIG. 4, platinum or Inconel wires 17 and 18 provide a thermistor unit and Nichrome wires 19 and 20 provide a varistor unit in a single element.

While the terminal wires could extend outwardly from both ends of the body of the element to enable the ultimate user to utilize any of the possible combinations that can be made, it may be preferred in some instances to have one pair extend outwardly only at one end and have another pair extend outwardly only at the opposite end so that adjacent pairs indicate that they are to be used in conjunction with each other. For example, in the arrangement shown in FIGS. 1 and 2, one wire (11) could extend outwardly at both ends and the other two wires (12, 13) could each extend outwardly only at an opposite end. Similarly, in the arrangement shown in FIG. 4, the wires 17 and 18 could extend from one end and the wires 19 and 20 could extend from the opposite end.

From the foregoing description, it will be seen that the present invention provides semi-conductor elements having a plurality of values and/or characteristics in a simple, practical and economical manner.

As various changes may be made in the form, construction and arrangement of the parts herein, without departing from the spirit and scope of the invention and without sacrificing any of its advantages, it is to be understood that all matter herein is to be interpreted as illustrative and not in any limiting sense.

I claim:

A semi-conductor element comprising a body formed of a resistance material consisting essentially of between about and about 96% by weight of manganese dioxide and between about 30% and about 4% by weight of cupric oxide, and a first and second pair of spaced parallel, conductive terminal wires embedded in said body and extending outwardly therefrom, said first pair of Wires being formed of an alloy consisting essentially of between about and about by weight of nickel and between about 20% and about 15% by weight of chromium and both wires of said second pair of wires being formed of a material selected from the group consisting of platinum and an alloy consisting essentially of between about 6% and about 17% by weight of iron, between about 11% and about 18% by weight of chromium and the balance nickel at a minimum of 70% by weight, said first pair of wires cooperating with said body to provide an element having varistor characteristics and said second pair of wires cooperating with said body to provide an element having thermistor characteristics.

References Cited in the file of this patent UNITED STATES PATENTS 1,549,394 Tyler Aug. 11, 1925 2,352,056 Wilson June 20, 1944 2,899,665 Cowles Aug. 11, 1959

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