U.S. patent number 3,778,744 [Application Number 05/336,518] was granted by the patent office on 1973-12-11 for film resistors.
Invention is credited to Henry W. Brandi.
United States Patent |
3,778,744 |
Brandi |
December 11, 1973 |
FILM RESISTORS
Abstract
A metal film resistor adapted to be combined with like resistors
to form a resistor network. The film is deposited on a dielectric
as a nickel-chrome alloy being fused thereto as by means of a glass
medium. Leads are connected to the back or front sides of the
resistor by means of silverized terminals which are fused to the
dielectric on two sides and the intervening edge of its dielectric
thereby affording such option and allowing the film to be deposited
over the entire surface of its front side when the leads are
connected on the back side. The resistance path is formed in the
film between slots cut through both the deposited film and the
dielectric whereby the resistance of the film may be adjusted
extremely accurately to the desired ohmage.
Inventors: |
Brandi; Henry W. (Morristown,
NJ) |
Family
ID: |
23316459 |
Appl.
No.: |
05/336,518 |
Filed: |
February 28, 1973 |
Current U.S.
Class: |
338/260; 338/275;
338/309; 338/329; 338/262; 338/273; 338/292; 338/314 |
Current CPC
Class: |
H01C
1/14 (20130101) |
Current International
Class: |
H01C
1/14 (20060101); H01c 001/14 () |
Field of
Search: |
;338/260,262,273,275,276,292,293,309,313,314,329,328,322 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Goldberg; E. A.
Claims
What is claimed is:
1. A film resistor comprising a flat base of a dielectric material,
a metal material forming terminations discretely fused to said
base, wire leads bonded to said metal material, a metallic film
deposited on one side of said base, slots formed in said dielectric
material and film to form a resistive path in said film, and a
packing material encapsulating said resistor.
2. A film resistor as defined in claim 1 wherein silverized metal
material is continuously formed on two sides and the intervening
edge of the dielectric material and the leads are soldered to the
terminations on the other side of said base.
3. A film resistor as defined in claim 1 wherein said dielectric
material is a glass ceramic and said resistive path is formed
between straight lined slots ground in said film.
4. A film resistor as defined in claim 2 wherein said dielectric
material is a glass ceramic and said resistive path is formed
between straight lined slots ground in said film.
5. A film resistor as defined in claim 4 wherein said metallic film
is fabricated of a nickel-chrome alloy.
6. A film resistor as defined in claim 5 wherein said straight
lined slots are ground in the film and ceramic alternately from one
edge and an opposing edge of the resistor, each slot extending less
than the entire distance between said edges.
7. A resistive network comprising two or more film resistors as
defined in claim 6 which have been encapsulated in a common packing
material.
Description
The present invention relates to electric resistor components and,
in particular, to such components employing metallic films as the
resistor substance.
Hitherto, film resistors have typically utilized cylindrically
shaped ceramic bodies on which metallic film is deposited. The film
is connected to end caps by fused end terminals, the leads being
welded to the caps, See U. S. Pat. No. 3,643,200.
The parameters of the known metal film resistors are adversely
affected in operation as a consequence of the means employed to
connect the leads to the resistors film. According to the present
invention the dielectric substrate is formed of a flat body having
slots which determine the filmed resistive pathway, formed therein
either prior or subsequent to the deposit of the film. The leads
are then bonded to silver terminations which have been thermally
fused to the substrate on one edge and two sides thereof so that
the bonding can be effected on the reverse side thereof prior to
film deposit over the entire surface of the substrate without
affecting said parameters. The component is then encapsulated in a
clear epoxy.
One object of the invention is to provide an improved metallic film
resistor having a long term stability in operation under extreme
atmosphere and temperature conditions.
Another object of the invention is to provide a metal film resistor
having low temperature coefficiency.
Other objects and advantages of the invention may be appreciated on
reading the following detailed description of one embodiment
thereof which is taken in conjunction with the accompanying
drawings, in which:
FIG. 1 is an elevational view of the film resistor with a portion
thereof broken away;
FIG. 2 is a section taken on the line 2--2 of FIG. 1;
FIG. 3 is a perspective view showing a plurality of resistors in
side by side relation to form a resistive network; and
FIG. 4 is a perspective view showing a plurality of resistors in
end to end relation to form a resistive network.
Referring to the drawings, the dielectric base or substrate 10 for
the film resistor is fabricated of a glass-ceramic. Silverized
terminations 12 are thermally fused to the two lower corners of the
base on its front face, the lower edge and the back side thereof as
shown in FIG. 2. Leads 14 and 16 are soldered to the terminations
on the back side of the substrate.
There is deposited on one side of the base a nickel-chrome resistor
film 18. The ohmic resistance of the film is adjusted highly
accurately to the desired value by grinding straight slots into the
film and dielectric alternating from the top and bottom edges of
the component as shown in FIG. 1. For standard size resistors, it
may be preferred to precut the slots in the substrate prior to
depositing the resistive film thereon. The resulting product is a
highly stable, low noise resistor having a low temperature
coefficiency. The particular expedient used to bond the leads of
the silver terminals allows not only the elimination of end caps,
but minimizes contact resistance. The resistor is finally
encapsulated in a high temperature epoxy material 20 as protection
against moisture or other contamination.
The particular construction of the film resistor lends itself to
either side by side combination, as shown in FIG. 3, or end to end
combination, as shown in FIG. 4, of individual components to form a
network of resistors which are adapted for easy insertion into a
socket provided by an external circuit. The combination is then
encapsulated in an epoxy covering.
Various modifications of the invention may be effected by persons
skilled in the art without departing from the scope and principle
of the invention as defined in the appended claims.
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