CA1218125A - Electrical film resistor - Google Patents
Electrical film resistorInfo
- Publication number
- CA1218125A CA1218125A CA000473640A CA473640A CA1218125A CA 1218125 A CA1218125 A CA 1218125A CA 000473640 A CA000473640 A CA 000473640A CA 473640 A CA473640 A CA 473640A CA 1218125 A CA1218125 A CA 1218125A
- Authority
- CA
- Canada
- Prior art keywords
- electrode
- substrate
- electrodes
- film
- terminals
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/351—Working by laser beam, e.g. welding, cutting or boring for trimming or tuning of electrical components
Abstract
ABSTRACT OF THE DISCLOSURE
An electrical film resistor. The film resistor includes a substrate, resistive film, and first and second terminals. The first terminal includes a first electrode.
The second terminal includes second and third electrodes.
The second electrode is close to the first electrode, and the third electrode is spaced apart from the first electrode. Moreover, the second and third electrodes are electrically interconnected. A kerf may be cut in the resistive material to increase the resistance between the two terminals and eventually substantially electrically isolate the second electrode from the first terminal.
Thereafter, kerfs may be cut in the resistive material between first and third electrodes to further increase the resistance between the two terminals.
An electrical film resistor. The film resistor includes a substrate, resistive film, and first and second terminals. The first terminal includes a first electrode.
The second terminal includes second and third electrodes.
The second electrode is close to the first electrode, and the third electrode is spaced apart from the first electrode. Moreover, the second and third electrodes are electrically interconnected. A kerf may be cut in the resistive material to increase the resistance between the two terminals and eventually substantially electrically isolate the second electrode from the first terminal.
Thereafter, kerfs may be cut in the resistive material between first and third electrodes to further increase the resistance between the two terminals.
Description
8~5 BACKGROUND OF TEE INVENTION
The present invention relaxes to an electrical resistor and more particularly to an electrical film resistor that may be trimmed to exhibit a predetermined resistance.
In order to help reduce the size of electronic products to more easily provide connections for components, electronic elements are often formed on a board, or substrate, rather than being made as discrete components and applied to the board. Resistors are often formed in such a manner by first making an electrically non-conductive substrate. A layer of an electrically resistive material and at least two electrically conductive terminals are applied to the substrate.
Electrical current may flow between the terminals through the electrically resistive film. The level of resistance between the terminals is determined by the physical geometry of the film between the terminals.
The geometry of the film between the two terminals is often changed by "trimming," or removing, selected portions of the film from the substrate. laser may be used, for example r to make a "kern," or cut, in the film and necessarily change the pattern of current flow through the film on the substrate.
Many applications, such as in hearing aids, require the manufacturer of the resistor to gradually vary the resistance between the terminals after the film has been applied to the substrate. Many presently available methods for trimming such film resistors, however, are not ideally suited for trimming aver wide resistance ranges.
As a result, the size of the substrate and film is larger than may otherwise be necessary.
In addition, many currently available film resistors exhibit resistance "drift." Thus, after the film resistor has been trimmed, the electrical resistance .
Lo 25 that it exhibits may, for example, vary over time or vary as a result of being exposed to different ambient temperatures. Such instability in the resistance may impair the performance of the electrical device incur-prorating the film resistor. Alternatively, the design of the electrical device may have to be larger and more complex than otherwise necessary in order to compensate for the drift that the film resistor exhibits.
SUM Y OF THE INVENTION
In a principal aspect, the present invention is a film resistor having first and second terminals and an electrically non-conductive substrate. In addition, the S resistor includes an electrically resistive film applied to the substrate in contact with the terminals.
The film provides a substantially predetermined resistance for each square unit of area on the substrate.
Also, it may be removed from the substrate in a prude-termined pattern (such as kerns made by a laser).
The first terminal includes a first electrode. The second terminal includes second and third electrodes. The second electrode is displaced a first predetermined distance from the first electrode.
The third electrode is displaced a second predetermined distance from the first electrode, and this second predetermined distance is larger than the first predetermined distance. Nonetheless, the second and third electrodes are electrically interconnected.
As a result, the resistance between the terminals may be increased by selectively removing the film between the first and second electrodes until the second electrode is substantially electrically isolated from the first electrode. Thereafter, if needed, the resistance between the terminals may be further increased by selectively removing the resistive film between the first and third electrodes.
In another principal aspect, the present inventions a process for making a film resistor having first and second terminals which are applied to an electrically non-conductive substrate. The first terminal includes a first electrode. The second terminal includes second and third electrodes which are electrically interconnected.
An electrically resistive film is applied to the substrate, in contact with the three electrodes. The film may then be removed from the substrate between the first and second electrodes so that the resistance between the first and second terminals may be gradually increased.
If the resistor is required to exhibit additional resistance, the removal of the film continues until the second electrode is substantially electrically isolated from the first electrode. Thereafter, the film is removed from between the first and third electrodes. In this manner, the resistance between the first and second terminals may increase still further.
Thus, an object of the present invention is an improved electrical film resistor. Another object is a smaller film resistor that may be gradually trimmed to exhibit a greater range of resistance values. Still another object is a film resistor with improved drift stability that more precisely maintains a particular resistance value after trimming.
et another object of the present invention is an improved process for making a film resistor. Still another object is a process for making a smaller film resistor that may be gradually trimmed to exhibit a greater variety of resistance values. An additional object is a process for making a film resistor that exhibits greater drift stability. These and other objects, features, and advantages of the present invention are discussed or apparent in the following detailed description BRIEF DESCRIPTION OF THE DRAWING
Preferred embodiments of the present invention are described herein with reference to the drawing wherein:
FIGURE 1 is a schematic representation of a top plan S view of an electrical film resistor commonly used prior to applicant's present invention;
FIGURE 2 is a schematic representation of a top plan view of a preferred embodiment of the electrical film resistor, which is distinguished from the electrical film I resistor shown in FIGURE l;
FIGURE 3 is a schematic representation of a top plan view of a second preferred embodiment of the present invention, showing electrodes extending further into the substrate than the embodiment shown in FIGURE 2; and FIGURE 4 is a schematic representation of a top plan view of a third preferred embodiment of the present invention, showing a substrate having a more irregular shape than the embodiment shown in FIGURE 2.
s , ., .
I s - -DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
Referring to FIGURES, a preferred embodiment of the present invention is shown as an improved electrical film resistor 10. The film resistor 10 may be used in any application where a thick or thin film resistor is required. The film resistor 10 of the present invention, however, may be used to great advantage where the resistor must be capable of exhibiting a wide variety of resistive values, be physically small, and offer superior drift characteristics. Thus, for example, the film resistor 10 may be used to great advantage in constructing a hearing aid (not shown).
FIGURE 1 demonstrates a previously known film resistor 12. The film resistor 12 includes an electrical-lye non-conductive substrate 14, resistive film 16 applied thereto, and first and second terminals 18, 20.
The substrate 14 substantially defines a rectangle having first, second, third, and fourth edges, respect-lively marked 22, 24, 26, and 28. In the example shown in 20 FIGURE 1, the first and third edges 22, 26 are each approximately 1.2 inch long and the second and fourth edges are each approximately .95 inch long.
The resistive film 16 is applied at a substantially uniform thickness over the substrate 14. The electrical resistance between two large areas, or electrodes, on the film resistor 10 is then a function of the geometry of the resistive film 16 between the two electrodes.
More precisely, the resistance is substantially a function only of the length and width of the area of the resistive film 16 between the two areas. Thus, for example, assume that the resistive film 16 between two electrodes (not shown) is an area, or square, measuring .1 inch long by .1 inch wide. The resistance would be the ; same if the area between the two electrodes measured 1.0 inch long by 1.0 inch wide. Notably, however, the .:, ~Z~8~S
resistance between the two electrodes would be tripled if the area between the two electrodes measured .3 inch long by .1 inch wide.
Thus, as those skilled in the art will recognize, the resistance between two electrodes is determined by the number of "square units of resistive film" or "squares,"
between the two electrodes. The size of the squares has no substantial, direct influence on the resistance between the electrodes.
In algebraic terms, the resistance between the two electrodes for a simple case may be expressed by the following formula:
P L P
R = B B x N
t W t where R = Resistance between the two electrodes, expressed in ohms;
PUB = Bulk resistivity of the resistive film, expressed in ohm centimeters;
t = thickness of the resistive film on the substrate, expressed in centimeters;
L = length of the area between the two electrodes, expressed in centimeters;
W = width of the area between the two electrodes, expressed in centimeters; and N = number of squires" of resistive film between the two electrodes (dimension-less.
s Thus, the electrical resistance between two electrodes may be increased by increasing the number of squares (of resistive material) between the two electrodes.
The first and second terminals 18, 20 of the film resistor 12 are separated by approximately 1 inch (FIGURE
1). Before any of the resistive film 16 is selectively removed from the substrate 14, current may flow through the resistive material, directly between the first and second terminals 18, 20.
The number of squares, and thus the electrical resistance, between the first and second terminals 18, 20 may be gradually increased by selectively removing the resistive film 16 from the substrate 14 in a predetermined pattern and "forcing" the current to take a more indirect route from one terminal to the other.
Thus, for example, a computer controlled yttrium aluminum garnet (YAW) or carbon dioxide (COY) laser (not shown), specifically designed for trimming resistor elements, may be used to make kerns in the resistive film 16. Other known techniques, however, such as abrasive trimming, may also be employed to make the kerns.
The trimming does not substantially affect the substrate, but does remove a narrow strip of the resistive film 16. As shown in FIGURE 1, a first kern 30 may be made, dividing the resistive film 16 into left and right sections 32, 34.
Before the first kern 30 is made, the current can flow, in a substantially straight line, between the first and second terminals 18, 20. The first kern 30, however, causes the current from the first terminal 18 to flow through the left section 32 before traveling to the second terminal 20.
As the first kern 30 is drawn from the first edge 22 toward the third edge 26, the resistance between the first and second terminals 18, 20 gradually increases. As shown in FIGURE 1, the first kern 30 increases the resistance of ~2~8~25 g the film resistor 12 by over two squares (which have been illustratively marked with dotted lines in FIGURE 1 and designated 36 and 38.
As previously indicated, the resistance between the first and second terminals 18, 20 may be monitored and the cutting of the first kern 30 curtailed when an appropriate resistance level has been obtained. If the resistance exhibited by the film resistor 12 is still too low after the first kern 30 has been made, however, a second kern 40 may be made parallel to the first kern 30. The second kern 40 may begin at the third edge 26 of the film resistor 12 and be cut toward the first edge 22 J thus increasing the number of squares of resistive film 16 that the current must flow through when traveling between the first and second terminals 18, 20.
If, after completing the second kern 40, additional resistance is still required between the first and second terminals 18, 20, additional kerns 42 may be made in a manner similar to that previously described for the first 20 and second kerns on, 40. The "zig-zag" pattern of kerns shown in Figure 1 was previously known in the art and is often referred to as a "serpentine cut."
The ratio between the highest resistance that a film resistor will exhibit (after kerns have been cut), divided 25 by the lowest resistance that the film resistor 12 can exhibit (before any kerns are cut), is often referred to as a "trimming ratio." The trimming ratio is thus a measure of how variable a film resistor may be. the trimming ratio, multiplied by the resistance per square of 30 the particular resistive film used, provides the range of resistance values which may be achieved by the film resistor.
; The size of the substrate, together with applicants observation that no square of resistive material should be 35 less than .01 inch by .01 inch, suggests that the "serpentine cut" shown in FIGURE 1 provides a trimming ratio of less than 75:1.
, US
If the substrate 14 were to be lengthened, the first and second terminals 18, 20 could be moved further apart, and additional kerns could be cut between the first and second terminals 18, 20. Moving the first and second terminals 18, 20 further apart, however, also increases the resistance between the first and second terminals 18, 20 before any kerns are cut. Thus, the trimming ratio (which equals the ratio of the greatest possible resistance divided by the lowest possible resistance) will increase only a relatively small amount if the film resistor 12 is made longer and the first and second terminals 18, 20 are moved further apart.
Applicant has discovered, however, that the trimming ratio of a film resistor may be increased 15 significantly by using the film resistor 10 shown in FIGURE 2. The film resistor 10 is formed on an electrically non-conductive board, or substrate 44. The film resistor 10 also includes an electrically resistive film 46, together with first and second terminals 48, 50, 20 which are applied to the substrate 44.
The substrate 44 of the preferred embodiment is made of Alumina (Aye). Other substances, however, such as Barlow (Boo), or glass, may be used to construct the substrate 12. The substrate 44 defines a rectangle having 25 first, second, third, and fourth edges, 52, 54, 56, 58.
The firsthand third edges 52, 56 are each approximately 1.35 inch long, and the second and fourth edges 54, 58 are each approximately .95 inch long. (Notably, all figures shown, including FIGURE 1, are drawn for illustrative 30 purposes and not drawn to scale.) The film resistor 10 of the present invention may be used as either a thick or thin film resistor. In the preferred embodiment used by applicant, however, the resistive film 46 is of the "thick" variety. Thus, the 35 resistive film 46 is comprised of a material, such as I
ruthenium oxide, which offers a predetermined electrical resistance for each square unit of the resistive film 46 on the substrate 44. A layer of the resistive film 46, at least 10 micrometer thick, is applied to the substrate 44, dried, and then fired in air at a temperature between 750 centigrade to 1000 centigrade. The resistive film 46 on the substrate 44 then offers a resistance of approximately 500 ohms per square.
The first terminal 48 includes a first electrode 60 along with associated hardware that interconnects the first electrode 60 with other components within an electrical device (not shown). The first terminal 48 is attached to the substrate 44 and is in electrical contact with the resistive film 46.
The second terminal 50, however, includes second and third electrodes 62, 64, and a conductor 66 for electric ally interconnecting the second and third electrodes 62, 64. The second terminal 50 also, of course, includes the associated hardware that interconnects the second and 20 third electrodes 62, 64 with other components within an electrical device (not shown).
The first and second electrodes 60, 62 are positioned on the substrate 44 approximately .02 inch from each other, with a first area I of resistor film I
25 between them. The third electrode 64, however r is approximately .85 inch from the first electrode 60, with a second area 70 between the first and third electrodes 60 J
64.
initially, before any kerns are made, substantially 30 all resistance between the first and second terminals I
50 is provided by the resistive film 46 in the first area 68 between the first and second electrodes 60, 62.
As before, the resistance between the first and second terminals 48, 50 is monitored and, if additional 35 resistance is desired, kerns may be cut into the resistive ., US
film 46. Once a desired level of resistance between the first and second terminals 48, 50 is obtained, the cutting of the kerns is discontinued.
A first kern 72, having first and second segments, 74, 76 may be cut into the first area 68 of the resistive film 46. The first segment 74 of the first kern 72 is cut substantially midway between the first and second electrodes 60, I The first segment 74 of the first kern 72 it discontinued when the kern 72 reaches a turning point 78 approximately .01 inch past the first and second electrodes 60, 62. The second segment 76 of the first kern 72 starts at the turning point 78 and continues toward the second edge 54.
As before, the resistance between the first and second terminals 48, 50 gradually increases as the first kern 72 is made. When the second segment 76 of the first kern 72 approaches the second edge 54, the second electrode 62 is substantially electrically isolated from the first terminal 48. However, most of current from the first terminal 48 flows instead into the third electrode 64.
As shown in FIGURE 2, the second segment 76 ox the first kern 72 is discontinued before it comes closer than .01 inch to the second edge 54. The first kern 72 has then 25 substantially divided the substrate into upper and lower regions on, 82. If the film resistor 10 is required to exhibit still more resistance, additional kerns may be cut into the upper region 80, as shown in FIGURE 2.
A second kern 84 may thus be cut into the upper 30 region 80 of resistive film 46 on the substrate 44. The second kern I begins at the turning point OR and extends toward the third edge 56.
The second kern 84 stops at least .01 inch from the third edge 56. If the second kern 84 did reach the third US edge 56, the First terminal 48 would be electrically I*
,..~,, isolated from the second terminal 50, effectively eliminating the usefulness of the film resistor 10.
Applicant has observed that the second kern 84 should be cut no closer than .01 inch from the third edge 56. Otherwise, the resistance exhibited by the film resistor 10 may vary, or drift, both initially, during processing, and later, over time.
When the laser (not shown) makes any kern, micro cracks (not shown) may occur in the resistive film 46 about the kern. Thus, if the second kern 84 extends substantially closer than .01 inch to the third edge 56, the micro cracks may extend between the kern 84 and third edge 56. Such micro cracks may significantly alter the resistance of the film resistor 10 in a substantially unpredictable manner.
If required, a third kern 86 may be cut parallel to the second kern 84. The third kern 86 is approximately .01 inch from the second kern 84. The third kern 86 begins at the third edge 56 of the substrate 44 and extends toward the first edge 52. The third kern 86 stops at least .01 inch from the second segment 76 of the first kern 72.
Applicant has observed that the third kern 86 should be made no closer than .01 inch to the first or second kerns 72, 84. Otherwise, micro cracks in the resistive film 42 between the first and third kerns 72, 86 or between the second and third kerns 84, 86 may cause a substantially unpredictable drift in the resistance exhibited by the film resistor 10.
Additional kerns 87 may be cut into the upper region 80 of the resistive film 46, in a manner similar to that previously described for the second and third kerns 84, 86. Using the film resistor 10 shown in FIGURE 2, applicant has obtained a trimming ratio of over 170:1.
Thus, the film resistor 10 of applicant's invention Jo .
~LZ18~2~
exhibits a significantly higher trimming ratio and offers a higher range of possible values.
Moreover, since no kern is cut closer than approximately ~01 inch from the edges 52-58 of -the substrate 44 or from other kerns, micro cracks have a reduced impact on the resistance exhibited by the film resistor 10. Thus, the film resistor 10 offers improved stability against "shift" in the resistance value that it exhibits.
Since the first and second electrodes 60, 62 of the film resistor 10 are relatively close, the minimum resistance exhibited between the first and second terminals 48, 50 (before any kerns are cut) is rather low.
However, kerns may be cut in the resistive film I so that the second electrode 62 is gradually isolated from the first electrode 60 and the resistance between the first and second terminals 48, 50 gradually increases.
After the second electrode 62 is substantially electrically isolated, most current from the first 20 electrode 60 flows into the third electrode 64~ Since the second and third electrodes 52, 64 are electrically interconnected, however, the gradual isolation of the second electrode 62 is not apparent to other electrical components which utilize or monitor the electrical 25 properties of the film resistor 10.
The third electrode 64 is displaced farther away from the first electrode 60 than is the second electrode 62. Thus, the resistance between the first and second terminals 48, 50 may be further increased by cutting kerns 30 between the first and third electrodes 60, 64.
Notably, different configurations of the substrate 44, resistive film 46, and terminals 48, 50 may be incur prorated in different embodiments of the present invention.
Thus, in the preferred embodiment shown in FIGURE 3, a 35 film resistor 88 is shown having a substrate 90, resistive 8~2~
film 92, and first and second terminals 94, 96. As before, the substrate 90 defines a rectangle having first, second, third, and fourth edges 98, 100, 102, 104. Again, the first and third edges 98, 102 are approximately 1.35 inches long and the second and fourth edges 100, 104 are approximately .95 inch long.
The first terminal 94 includes a first electrode 106, and the second terminal 96 includes second and third electrodes 108, 110, which are electrically inter-connected via a conductor 112. Also, as before, the third electrode 110 is displaced further from the first electrode 106 than is the second electrode 108.
All electrodes 108-110 of the film resistor 88, however, are approximately 1 inch long. Thus, a first kern 114 may be cut into the resistive film 92 which includes first, second, third, and fourth segments 116, 118, 120, 122 separated, respectively, by first, second, and third turning points 124, 126, 128.
The first segment 116 of the first kern 114 extends from the first edge 98 of the substrate 90 toward the third edge 102. The first segment 116 stops at the first turning point 124, which is located approximately .11 inch from the first edge 98. The second segment 118 of the first kern 114 extends from the first turning point 124 toward the second edge 100, until it reaches the second turning print 126~ The third segment 120 extends from the second turning point 126 toward the first edge 98, and stops approximately .01 inch from the first edge 98.
The third turning point 128 it roughly .01 inch from the first edge 98, and the fourth segment 122 of the first kern 114 extend therefrom toward the second edge 100~
The fourth segment 122 abuts the third electrode 110, such that the second electrode 108 is substantially entirely electrically isolated from the first electrode 106.
35 Current may still flow between the first and third electrodes 106, 110, however. The first kern 114, as before, divides the film resistor 88 into upper and lower regions 130, 132, and additional kerns 134 may be cut into the resistive film 92 as required. See FIGURE 3 .
Yet another configuration of the present invention is shown in FIGURE 4 . A film resistor 136 is shown having a substrate 138, resistive film 140, and first and second terminals 142, 144.
Unlike the substrate 44 shown in FIGURE 2, however, the substrate 138 is irregularly shaped. Nonetheless, the basic principles for making and using the film resistor 136 represented in FIGURE 4 are the same as for the film resistor 10 represented in FIGURE 2.
The first terminal 142 includes a first electrode 146 The second terminal 144 includes second and third electrodes 148, 150 which are electrically inter-connected.
The first and second electrodes 146, 148 are close to each other, and a first kern 152 may be cut between them to gradually increase the resistance (increase the number of squares of the resistive film 140) between them.
In the film resistor 136 of FIGURE 4, however, unlike the film resistor 10 of FIGURE 2, the first kern 152 is continued until it substantially entirely electrically isolates the second electrode 148 from the first electrode 146. The first kern 152 has then divided the film resistor 136 into upper and lower regions 154, 156, and, as before, additional kerns 158 may be cut into upper region 154 to increase the resistance between the first and third electrodes 146, 150 and thus between the first and second terminals 142, 144.
Preferred embodiments of the present invention have been described herein. It is to be understood, however, that changes and modifications can be made without departing from the true Scope and spirit of the present invention. Thus, or example, the present invention may still be used even though the order ox the steps or the `` ~21~Z~
materials used to make the film resistor lo are different than previously described. The true scope and spirit of the present invention are defined by the following claims, to be interpreted in light of the foregoing specification.
The present invention relaxes to an electrical resistor and more particularly to an electrical film resistor that may be trimmed to exhibit a predetermined resistance.
In order to help reduce the size of electronic products to more easily provide connections for components, electronic elements are often formed on a board, or substrate, rather than being made as discrete components and applied to the board. Resistors are often formed in such a manner by first making an electrically non-conductive substrate. A layer of an electrically resistive material and at least two electrically conductive terminals are applied to the substrate.
Electrical current may flow between the terminals through the electrically resistive film. The level of resistance between the terminals is determined by the physical geometry of the film between the terminals.
The geometry of the film between the two terminals is often changed by "trimming," or removing, selected portions of the film from the substrate. laser may be used, for example r to make a "kern," or cut, in the film and necessarily change the pattern of current flow through the film on the substrate.
Many applications, such as in hearing aids, require the manufacturer of the resistor to gradually vary the resistance between the terminals after the film has been applied to the substrate. Many presently available methods for trimming such film resistors, however, are not ideally suited for trimming aver wide resistance ranges.
As a result, the size of the substrate and film is larger than may otherwise be necessary.
In addition, many currently available film resistors exhibit resistance "drift." Thus, after the film resistor has been trimmed, the electrical resistance .
Lo 25 that it exhibits may, for example, vary over time or vary as a result of being exposed to different ambient temperatures. Such instability in the resistance may impair the performance of the electrical device incur-prorating the film resistor. Alternatively, the design of the electrical device may have to be larger and more complex than otherwise necessary in order to compensate for the drift that the film resistor exhibits.
SUM Y OF THE INVENTION
In a principal aspect, the present invention is a film resistor having first and second terminals and an electrically non-conductive substrate. In addition, the S resistor includes an electrically resistive film applied to the substrate in contact with the terminals.
The film provides a substantially predetermined resistance for each square unit of area on the substrate.
Also, it may be removed from the substrate in a prude-termined pattern (such as kerns made by a laser).
The first terminal includes a first electrode. The second terminal includes second and third electrodes. The second electrode is displaced a first predetermined distance from the first electrode.
The third electrode is displaced a second predetermined distance from the first electrode, and this second predetermined distance is larger than the first predetermined distance. Nonetheless, the second and third electrodes are electrically interconnected.
As a result, the resistance between the terminals may be increased by selectively removing the film between the first and second electrodes until the second electrode is substantially electrically isolated from the first electrode. Thereafter, if needed, the resistance between the terminals may be further increased by selectively removing the resistive film between the first and third electrodes.
In another principal aspect, the present inventions a process for making a film resistor having first and second terminals which are applied to an electrically non-conductive substrate. The first terminal includes a first electrode. The second terminal includes second and third electrodes which are electrically interconnected.
An electrically resistive film is applied to the substrate, in contact with the three electrodes. The film may then be removed from the substrate between the first and second electrodes so that the resistance between the first and second terminals may be gradually increased.
If the resistor is required to exhibit additional resistance, the removal of the film continues until the second electrode is substantially electrically isolated from the first electrode. Thereafter, the film is removed from between the first and third electrodes. In this manner, the resistance between the first and second terminals may increase still further.
Thus, an object of the present invention is an improved electrical film resistor. Another object is a smaller film resistor that may be gradually trimmed to exhibit a greater range of resistance values. Still another object is a film resistor with improved drift stability that more precisely maintains a particular resistance value after trimming.
et another object of the present invention is an improved process for making a film resistor. Still another object is a process for making a smaller film resistor that may be gradually trimmed to exhibit a greater variety of resistance values. An additional object is a process for making a film resistor that exhibits greater drift stability. These and other objects, features, and advantages of the present invention are discussed or apparent in the following detailed description BRIEF DESCRIPTION OF THE DRAWING
Preferred embodiments of the present invention are described herein with reference to the drawing wherein:
FIGURE 1 is a schematic representation of a top plan S view of an electrical film resistor commonly used prior to applicant's present invention;
FIGURE 2 is a schematic representation of a top plan view of a preferred embodiment of the electrical film resistor, which is distinguished from the electrical film I resistor shown in FIGURE l;
FIGURE 3 is a schematic representation of a top plan view of a second preferred embodiment of the present invention, showing electrodes extending further into the substrate than the embodiment shown in FIGURE 2; and FIGURE 4 is a schematic representation of a top plan view of a third preferred embodiment of the present invention, showing a substrate having a more irregular shape than the embodiment shown in FIGURE 2.
s , ., .
I s - -DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
Referring to FIGURES, a preferred embodiment of the present invention is shown as an improved electrical film resistor 10. The film resistor 10 may be used in any application where a thick or thin film resistor is required. The film resistor 10 of the present invention, however, may be used to great advantage where the resistor must be capable of exhibiting a wide variety of resistive values, be physically small, and offer superior drift characteristics. Thus, for example, the film resistor 10 may be used to great advantage in constructing a hearing aid (not shown).
FIGURE 1 demonstrates a previously known film resistor 12. The film resistor 12 includes an electrical-lye non-conductive substrate 14, resistive film 16 applied thereto, and first and second terminals 18, 20.
The substrate 14 substantially defines a rectangle having first, second, third, and fourth edges, respect-lively marked 22, 24, 26, and 28. In the example shown in 20 FIGURE 1, the first and third edges 22, 26 are each approximately 1.2 inch long and the second and fourth edges are each approximately .95 inch long.
The resistive film 16 is applied at a substantially uniform thickness over the substrate 14. The electrical resistance between two large areas, or electrodes, on the film resistor 10 is then a function of the geometry of the resistive film 16 between the two electrodes.
More precisely, the resistance is substantially a function only of the length and width of the area of the resistive film 16 between the two areas. Thus, for example, assume that the resistive film 16 between two electrodes (not shown) is an area, or square, measuring .1 inch long by .1 inch wide. The resistance would be the ; same if the area between the two electrodes measured 1.0 inch long by 1.0 inch wide. Notably, however, the .:, ~Z~8~S
resistance between the two electrodes would be tripled if the area between the two electrodes measured .3 inch long by .1 inch wide.
Thus, as those skilled in the art will recognize, the resistance between two electrodes is determined by the number of "square units of resistive film" or "squares,"
between the two electrodes. The size of the squares has no substantial, direct influence on the resistance between the electrodes.
In algebraic terms, the resistance between the two electrodes for a simple case may be expressed by the following formula:
P L P
R = B B x N
t W t where R = Resistance between the two electrodes, expressed in ohms;
PUB = Bulk resistivity of the resistive film, expressed in ohm centimeters;
t = thickness of the resistive film on the substrate, expressed in centimeters;
L = length of the area between the two electrodes, expressed in centimeters;
W = width of the area between the two electrodes, expressed in centimeters; and N = number of squires" of resistive film between the two electrodes (dimension-less.
s Thus, the electrical resistance between two electrodes may be increased by increasing the number of squares (of resistive material) between the two electrodes.
The first and second terminals 18, 20 of the film resistor 12 are separated by approximately 1 inch (FIGURE
1). Before any of the resistive film 16 is selectively removed from the substrate 14, current may flow through the resistive material, directly between the first and second terminals 18, 20.
The number of squares, and thus the electrical resistance, between the first and second terminals 18, 20 may be gradually increased by selectively removing the resistive film 16 from the substrate 14 in a predetermined pattern and "forcing" the current to take a more indirect route from one terminal to the other.
Thus, for example, a computer controlled yttrium aluminum garnet (YAW) or carbon dioxide (COY) laser (not shown), specifically designed for trimming resistor elements, may be used to make kerns in the resistive film 16. Other known techniques, however, such as abrasive trimming, may also be employed to make the kerns.
The trimming does not substantially affect the substrate, but does remove a narrow strip of the resistive film 16. As shown in FIGURE 1, a first kern 30 may be made, dividing the resistive film 16 into left and right sections 32, 34.
Before the first kern 30 is made, the current can flow, in a substantially straight line, between the first and second terminals 18, 20. The first kern 30, however, causes the current from the first terminal 18 to flow through the left section 32 before traveling to the second terminal 20.
As the first kern 30 is drawn from the first edge 22 toward the third edge 26, the resistance between the first and second terminals 18, 20 gradually increases. As shown in FIGURE 1, the first kern 30 increases the resistance of ~2~8~25 g the film resistor 12 by over two squares (which have been illustratively marked with dotted lines in FIGURE 1 and designated 36 and 38.
As previously indicated, the resistance between the first and second terminals 18, 20 may be monitored and the cutting of the first kern 30 curtailed when an appropriate resistance level has been obtained. If the resistance exhibited by the film resistor 12 is still too low after the first kern 30 has been made, however, a second kern 40 may be made parallel to the first kern 30. The second kern 40 may begin at the third edge 26 of the film resistor 12 and be cut toward the first edge 22 J thus increasing the number of squares of resistive film 16 that the current must flow through when traveling between the first and second terminals 18, 20.
If, after completing the second kern 40, additional resistance is still required between the first and second terminals 18, 20, additional kerns 42 may be made in a manner similar to that previously described for the first 20 and second kerns on, 40. The "zig-zag" pattern of kerns shown in Figure 1 was previously known in the art and is often referred to as a "serpentine cut."
The ratio between the highest resistance that a film resistor will exhibit (after kerns have been cut), divided 25 by the lowest resistance that the film resistor 12 can exhibit (before any kerns are cut), is often referred to as a "trimming ratio." The trimming ratio is thus a measure of how variable a film resistor may be. the trimming ratio, multiplied by the resistance per square of 30 the particular resistive film used, provides the range of resistance values which may be achieved by the film resistor.
; The size of the substrate, together with applicants observation that no square of resistive material should be 35 less than .01 inch by .01 inch, suggests that the "serpentine cut" shown in FIGURE 1 provides a trimming ratio of less than 75:1.
, US
If the substrate 14 were to be lengthened, the first and second terminals 18, 20 could be moved further apart, and additional kerns could be cut between the first and second terminals 18, 20. Moving the first and second terminals 18, 20 further apart, however, also increases the resistance between the first and second terminals 18, 20 before any kerns are cut. Thus, the trimming ratio (which equals the ratio of the greatest possible resistance divided by the lowest possible resistance) will increase only a relatively small amount if the film resistor 12 is made longer and the first and second terminals 18, 20 are moved further apart.
Applicant has discovered, however, that the trimming ratio of a film resistor may be increased 15 significantly by using the film resistor 10 shown in FIGURE 2. The film resistor 10 is formed on an electrically non-conductive board, or substrate 44. The film resistor 10 also includes an electrically resistive film 46, together with first and second terminals 48, 50, 20 which are applied to the substrate 44.
The substrate 44 of the preferred embodiment is made of Alumina (Aye). Other substances, however, such as Barlow (Boo), or glass, may be used to construct the substrate 12. The substrate 44 defines a rectangle having 25 first, second, third, and fourth edges, 52, 54, 56, 58.
The firsthand third edges 52, 56 are each approximately 1.35 inch long, and the second and fourth edges 54, 58 are each approximately .95 inch long. (Notably, all figures shown, including FIGURE 1, are drawn for illustrative 30 purposes and not drawn to scale.) The film resistor 10 of the present invention may be used as either a thick or thin film resistor. In the preferred embodiment used by applicant, however, the resistive film 46 is of the "thick" variety. Thus, the 35 resistive film 46 is comprised of a material, such as I
ruthenium oxide, which offers a predetermined electrical resistance for each square unit of the resistive film 46 on the substrate 44. A layer of the resistive film 46, at least 10 micrometer thick, is applied to the substrate 44, dried, and then fired in air at a temperature between 750 centigrade to 1000 centigrade. The resistive film 46 on the substrate 44 then offers a resistance of approximately 500 ohms per square.
The first terminal 48 includes a first electrode 60 along with associated hardware that interconnects the first electrode 60 with other components within an electrical device (not shown). The first terminal 48 is attached to the substrate 44 and is in electrical contact with the resistive film 46.
The second terminal 50, however, includes second and third electrodes 62, 64, and a conductor 66 for electric ally interconnecting the second and third electrodes 62, 64. The second terminal 50 also, of course, includes the associated hardware that interconnects the second and 20 third electrodes 62, 64 with other components within an electrical device (not shown).
The first and second electrodes 60, 62 are positioned on the substrate 44 approximately .02 inch from each other, with a first area I of resistor film I
25 between them. The third electrode 64, however r is approximately .85 inch from the first electrode 60, with a second area 70 between the first and third electrodes 60 J
64.
initially, before any kerns are made, substantially 30 all resistance between the first and second terminals I
50 is provided by the resistive film 46 in the first area 68 between the first and second electrodes 60, 62.
As before, the resistance between the first and second terminals 48, 50 is monitored and, if additional 35 resistance is desired, kerns may be cut into the resistive ., US
film 46. Once a desired level of resistance between the first and second terminals 48, 50 is obtained, the cutting of the kerns is discontinued.
A first kern 72, having first and second segments, 74, 76 may be cut into the first area 68 of the resistive film 46. The first segment 74 of the first kern 72 is cut substantially midway between the first and second electrodes 60, I The first segment 74 of the first kern 72 it discontinued when the kern 72 reaches a turning point 78 approximately .01 inch past the first and second electrodes 60, 62. The second segment 76 of the first kern 72 starts at the turning point 78 and continues toward the second edge 54.
As before, the resistance between the first and second terminals 48, 50 gradually increases as the first kern 72 is made. When the second segment 76 of the first kern 72 approaches the second edge 54, the second electrode 62 is substantially electrically isolated from the first terminal 48. However, most of current from the first terminal 48 flows instead into the third electrode 64.
As shown in FIGURE 2, the second segment 76 ox the first kern 72 is discontinued before it comes closer than .01 inch to the second edge 54. The first kern 72 has then 25 substantially divided the substrate into upper and lower regions on, 82. If the film resistor 10 is required to exhibit still more resistance, additional kerns may be cut into the upper region 80, as shown in FIGURE 2.
A second kern 84 may thus be cut into the upper 30 region 80 of resistive film 46 on the substrate 44. The second kern I begins at the turning point OR and extends toward the third edge 56.
The second kern 84 stops at least .01 inch from the third edge 56. If the second kern 84 did reach the third US edge 56, the First terminal 48 would be electrically I*
,..~,, isolated from the second terminal 50, effectively eliminating the usefulness of the film resistor 10.
Applicant has observed that the second kern 84 should be cut no closer than .01 inch from the third edge 56. Otherwise, the resistance exhibited by the film resistor 10 may vary, or drift, both initially, during processing, and later, over time.
When the laser (not shown) makes any kern, micro cracks (not shown) may occur in the resistive film 46 about the kern. Thus, if the second kern 84 extends substantially closer than .01 inch to the third edge 56, the micro cracks may extend between the kern 84 and third edge 56. Such micro cracks may significantly alter the resistance of the film resistor 10 in a substantially unpredictable manner.
If required, a third kern 86 may be cut parallel to the second kern 84. The third kern 86 is approximately .01 inch from the second kern 84. The third kern 86 begins at the third edge 56 of the substrate 44 and extends toward the first edge 52. The third kern 86 stops at least .01 inch from the second segment 76 of the first kern 72.
Applicant has observed that the third kern 86 should be made no closer than .01 inch to the first or second kerns 72, 84. Otherwise, micro cracks in the resistive film 42 between the first and third kerns 72, 86 or between the second and third kerns 84, 86 may cause a substantially unpredictable drift in the resistance exhibited by the film resistor 10.
Additional kerns 87 may be cut into the upper region 80 of the resistive film 46, in a manner similar to that previously described for the second and third kerns 84, 86. Using the film resistor 10 shown in FIGURE 2, applicant has obtained a trimming ratio of over 170:1.
Thus, the film resistor 10 of applicant's invention Jo .
~LZ18~2~
exhibits a significantly higher trimming ratio and offers a higher range of possible values.
Moreover, since no kern is cut closer than approximately ~01 inch from the edges 52-58 of -the substrate 44 or from other kerns, micro cracks have a reduced impact on the resistance exhibited by the film resistor 10. Thus, the film resistor 10 offers improved stability against "shift" in the resistance value that it exhibits.
Since the first and second electrodes 60, 62 of the film resistor 10 are relatively close, the minimum resistance exhibited between the first and second terminals 48, 50 (before any kerns are cut) is rather low.
However, kerns may be cut in the resistive film I so that the second electrode 62 is gradually isolated from the first electrode 60 and the resistance between the first and second terminals 48, 50 gradually increases.
After the second electrode 62 is substantially electrically isolated, most current from the first 20 electrode 60 flows into the third electrode 64~ Since the second and third electrodes 52, 64 are electrically interconnected, however, the gradual isolation of the second electrode 62 is not apparent to other electrical components which utilize or monitor the electrical 25 properties of the film resistor 10.
The third electrode 64 is displaced farther away from the first electrode 60 than is the second electrode 62. Thus, the resistance between the first and second terminals 48, 50 may be further increased by cutting kerns 30 between the first and third electrodes 60, 64.
Notably, different configurations of the substrate 44, resistive film 46, and terminals 48, 50 may be incur prorated in different embodiments of the present invention.
Thus, in the preferred embodiment shown in FIGURE 3, a 35 film resistor 88 is shown having a substrate 90, resistive 8~2~
film 92, and first and second terminals 94, 96. As before, the substrate 90 defines a rectangle having first, second, third, and fourth edges 98, 100, 102, 104. Again, the first and third edges 98, 102 are approximately 1.35 inches long and the second and fourth edges 100, 104 are approximately .95 inch long.
The first terminal 94 includes a first electrode 106, and the second terminal 96 includes second and third electrodes 108, 110, which are electrically inter-connected via a conductor 112. Also, as before, the third electrode 110 is displaced further from the first electrode 106 than is the second electrode 108.
All electrodes 108-110 of the film resistor 88, however, are approximately 1 inch long. Thus, a first kern 114 may be cut into the resistive film 92 which includes first, second, third, and fourth segments 116, 118, 120, 122 separated, respectively, by first, second, and third turning points 124, 126, 128.
The first segment 116 of the first kern 114 extends from the first edge 98 of the substrate 90 toward the third edge 102. The first segment 116 stops at the first turning point 124, which is located approximately .11 inch from the first edge 98. The second segment 118 of the first kern 114 extends from the first turning point 124 toward the second edge 100, until it reaches the second turning print 126~ The third segment 120 extends from the second turning point 126 toward the first edge 98, and stops approximately .01 inch from the first edge 98.
The third turning point 128 it roughly .01 inch from the first edge 98, and the fourth segment 122 of the first kern 114 extend therefrom toward the second edge 100~
The fourth segment 122 abuts the third electrode 110, such that the second electrode 108 is substantially entirely electrically isolated from the first electrode 106.
35 Current may still flow between the first and third electrodes 106, 110, however. The first kern 114, as before, divides the film resistor 88 into upper and lower regions 130, 132, and additional kerns 134 may be cut into the resistive film 92 as required. See FIGURE 3 .
Yet another configuration of the present invention is shown in FIGURE 4 . A film resistor 136 is shown having a substrate 138, resistive film 140, and first and second terminals 142, 144.
Unlike the substrate 44 shown in FIGURE 2, however, the substrate 138 is irregularly shaped. Nonetheless, the basic principles for making and using the film resistor 136 represented in FIGURE 4 are the same as for the film resistor 10 represented in FIGURE 2.
The first terminal 142 includes a first electrode 146 The second terminal 144 includes second and third electrodes 148, 150 which are electrically inter-connected.
The first and second electrodes 146, 148 are close to each other, and a first kern 152 may be cut between them to gradually increase the resistance (increase the number of squares of the resistive film 140) between them.
In the film resistor 136 of FIGURE 4, however, unlike the film resistor 10 of FIGURE 2, the first kern 152 is continued until it substantially entirely electrically isolates the second electrode 148 from the first electrode 146. The first kern 152 has then divided the film resistor 136 into upper and lower regions 154, 156, and, as before, additional kerns 158 may be cut into upper region 154 to increase the resistance between the first and third electrodes 146, 150 and thus between the first and second terminals 142, 144.
Preferred embodiments of the present invention have been described herein. It is to be understood, however, that changes and modifications can be made without departing from the true Scope and spirit of the present invention. Thus, or example, the present invention may still be used even though the order ox the steps or the `` ~21~Z~
materials used to make the film resistor lo are different than previously described. The true scope and spirit of the present invention are defined by the following claims, to be interpreted in light of the foregoing specification.
Claims (3)
1. A film resistor comprising, in combination:
an electrically non-conductive substrate;
an electrically resistive film applied to said substrate, said resistive film providing a substantially predetermined electrical resistance for each square unit of area and capable of being selectively removed, in a predetermined pattern, from said substrate;
a first terminal applied to said substrate in contact with said resistive film, said first terminal including a first electrode; and a second terminal applied to said substrate in contact with said resistive film, said second terminal including a second electrode applied to said substrate in contact with said resistive film, said second electrode displaced a first predetermined distance from said first electrode, whereby electrical resistance between said first and second electrodes may be increased by selectively removing, in a predetermined pattern, resistive film from said substrate, and a third electrode applied to said substrate in contact with said resistive material, said second and third electrodes being electrically interconnected, said third electrode displaced a second predetermined distance from said first electrode, and said second predetermined distance being greater than said first predetermined distance, whereby said resistive film may be selectively removed from said substrate between said first and second electrodes until said second electrode is substantially electrically isolated from said first electrode and whereby said resistance between said first and second terminals may thereafter by further increased by selectively removing, in a predetermined pattern, said resistive film from said substrate between said first and third electrodes.
an electrically non-conductive substrate;
an electrically resistive film applied to said substrate, said resistive film providing a substantially predetermined electrical resistance for each square unit of area and capable of being selectively removed, in a predetermined pattern, from said substrate;
a first terminal applied to said substrate in contact with said resistive film, said first terminal including a first electrode; and a second terminal applied to said substrate in contact with said resistive film, said second terminal including a second electrode applied to said substrate in contact with said resistive film, said second electrode displaced a first predetermined distance from said first electrode, whereby electrical resistance between said first and second electrodes may be increased by selectively removing, in a predetermined pattern, resistive film from said substrate, and a third electrode applied to said substrate in contact with said resistive material, said second and third electrodes being electrically interconnected, said third electrode displaced a second predetermined distance from said first electrode, and said second predetermined distance being greater than said first predetermined distance, whereby said resistive film may be selectively removed from said substrate between said first and second electrodes until said second electrode is substantially electrically isolated from said first electrode and whereby said resistance between said first and second terminals may thereafter by further increased by selectively removing, in a predetermined pattern, said resistive film from said substrate between said first and third electrodes.
2. A process for making a film resistor having first and second terminals comprising, in combination, the steps of:
applying a first electrode to an electrically non-conductive substrate, said first electrode defining a first terminal;
applying a second electrode to said substrate at a first predetermined distance from said first electrode;
applying a third electrode to said substrate at a second predetermined distance from said first electrode, said second predetermined distance being greater than said first predetermined distance, said second and third electrodes being electrically interconnected and cooperatively forming said second terminal;
applying an electrically resistive film to said non-conductive substrate, said resistive film being in contact with said first, second, and third electrodes;
selectively removing, in a predetermined pattern, said resistive film from said substrate between said first and second electrodes, whereby electrical resistance between said first and second terminals is gradually increased, until said second electrode is substantially electrically isolated from said first electrode; and selectively removing, in a predetermined pattern, said resistive film from said substrate between said first and third electrodes, whereby electrical resistance between said first and second terminals is further gradually increased.
applying a first electrode to an electrically non-conductive substrate, said first electrode defining a first terminal;
applying a second electrode to said substrate at a first predetermined distance from said first electrode;
applying a third electrode to said substrate at a second predetermined distance from said first electrode, said second predetermined distance being greater than said first predetermined distance, said second and third electrodes being electrically interconnected and cooperatively forming said second terminal;
applying an electrically resistive film to said non-conductive substrate, said resistive film being in contact with said first, second, and third electrodes;
selectively removing, in a predetermined pattern, said resistive film from said substrate between said first and second electrodes, whereby electrical resistance between said first and second terminals is gradually increased, until said second electrode is substantially electrically isolated from said first electrode; and selectively removing, in a predetermined pattern, said resistive film from said substrate between said first and third electrodes, whereby electrical resistance between said first and second terminals is further gradually increased.
3. The process for making a film resistor as claimed in Claim 2 further comprising the step of monitoring electrical resistance between said first and second terminals and wherein said steps of selectively removing, in a predetermined pattern, said resistive film from said substrate are discontinued when said electrical resistance between said first and second terminals reaches a predetermined level.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US605,612 | 1984-04-30 | ||
| US06/605,612 US4551607A (en) | 1984-04-30 | 1984-04-30 | Electrical film resistor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1218125A true CA1218125A (en) | 1987-02-17 |
Family
ID=24424440
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000473640A Expired CA1218125A (en) | 1984-04-30 | 1985-02-06 | Electrical film resistor |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US4551607A (en) |
| JP (1) | JPS616802A (en) |
| CA (1) | CA1218125A (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6377101A (en) * | 1986-09-19 | 1988-04-07 | 三洋電機株式会社 | Trimming of resistor |
| US5015989A (en) * | 1989-07-28 | 1991-05-14 | Pacific Hybrid Microelectronics, Inc. | Film resistor with enhanced trimming characteristics |
| US6951995B2 (en) * | 2002-03-27 | 2005-10-04 | Gsi Lumonics Corp. | Method and system for high-speed, precise micromachining an array of devices |
| US7563695B2 (en) * | 2002-03-27 | 2009-07-21 | Gsi Group Corporation | Method and system for high-speed precise laser trimming and scan lens for use therein |
| CN100521835C (en) * | 2005-12-29 | 2009-07-29 | 梁敏玲 | Manufacturing method of resistance film heating device and the formed resistance film heating device |
| JP5508946B2 (en) | 2010-06-16 | 2014-06-04 | デクセリアルズ株式会社 | Optical body, window material, joinery, solar shading device, and building |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3889223A (en) * | 1971-12-02 | 1975-06-10 | Olivetti & Co Spa | Resistor trimming technique |
| JPS51150660A (en) * | 1975-06-20 | 1976-12-24 | Nissan Motor | Method of producing resisting elements |
| GB2064226B (en) * | 1979-11-23 | 1983-05-11 | Ferranti Ltd | Trimming of a circuit element layer |
-
1984
- 1984-04-30 US US06/605,612 patent/US4551607A/en not_active Expired - Fee Related
-
1985
- 1985-02-06 CA CA000473640A patent/CA1218125A/en not_active Expired
- 1985-04-30 JP JP60091324A patent/JPS616802A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| US4551607A (en) | 1985-11-05 |
| JPS616802A (en) | 1986-01-13 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4647899A (en) | Electrical film resistor | |
| US5548268A (en) | Fine-line thick film resistors and resistor networks and method of making same | |
| US4041440A (en) | Method of adjusting resistance of a thick-film thermistor | |
| US5363084A (en) | Film resistors having trimmable electrodes | |
| SE438057B (en) | SET TO REGULATE THE RESISTANCE OF A TERMISTOR | |
| US4301439A (en) | Film type resistor and method of producing same | |
| US5548269A (en) | Chip resistor and method of adjusting resistance of the same | |
| KR100328255B1 (en) | Chip device and method of making the same | |
| CA1218125A (en) | Electrical film resistor | |
| JPH08306503A (en) | Chip-like electronic part | |
| US20020130761A1 (en) | Chip resistor with upper electrode having nonuniform thickness and method of making the resistor | |
| KR100324098B1 (en) | NTC Thermistors and NTC Thermistor Chips | |
| US4853671A (en) | Electric laminar resistor and method of making same | |
| US6806167B2 (en) | Method of making chip-type electronic device provided with two-layered electrode | |
| US5148143A (en) | Precision thick film elements | |
| SE444875B (en) | WANT TO MANUFACTURE THERMISTORS | |
| KR970009770B1 (en) | Thermistor intended primarily for temperature measurement & procedure for manufacture of a thermistor | |
| JPH04209501A (en) | Substrate for semiconductor device | |
| KR100477831B1 (en) | Chip composite electronic component and method of manufacturing the same | |
| JP2006019323A (en) | Resistance composition, chip resistor and their manufacturing method | |
| JP2000030902A (en) | Chip type resistor and its manufacture | |
| JPH04214601A (en) | Rectangular chip resistor for function correction use and manufacture thereof | |
| JP3651179B2 (en) | Resistor manufacturing method | |
| JPH01270301A (en) | Small-sized thermosensitive resistor and manufacture thereof | |
| JP2003297670A (en) | Chip type composite part |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |