TW202347363A - Current sensing resistor and method for manufacturing the same - Google Patents

Abstract

This invention relates to a current sensing resistor and a method for manufacturing the same. The current sensing resistor includes a substrate, a resistive layer, two front electrodes, two back electrodes, and two conductive layers. The substrate with negative temperature coefficient (NTC) has a front surface, two lateral surfaces, and a back surface. The resistive layer is disposed on the front surface. The front electrodes are spaced apart from each other and disposed on the resistive layer, such that the resistive layer is located between the substrate and the front electrodes. The back electrodes are spaced apart from each other and disposed on the back surface. One of the conductive layers partially covers one of the front electrodes and covers one of the back electrodes and covers one of the lateral surfaces, such that the one of the front electrodes is electrically connected to the one of the back electrodes.

Description

Current sensing resistor and method of making same

The present invention relates to a current sensing resistor and a manufacturing method thereof, and in particular to a current sensing resistor and a manufacturing method using a negative temperature coefficient (NTC) material as a substrate.

Traditional resistors use an insulating ceramic substrate or soft material as a carrier substrate, and then a selected special temperature coefficient of resistor (TCR) material is deposited on the upper surface of the carrier substrate, and then two ends of the TCR material are applied The terminal electrode process forms a basic current sensing resistor element. In order to accurately sense the current and compensate the current value, a temperature sensing element will be connected in parallel in the circuit design to compensate for the current measurement values at different temperatures.

However, in the application of the above-mentioned traditional current sensing elements, the parallel temperature sensing element will be affected by the thermal conductivity of the current sensing resistor element and is related to the material of the printed circuit board (PCB). The temperature sensing element will There is a temperature difference between the body temperature of the current sensing resistor element and it makes it difficult to accurately determine whether it is caused by the current change or the temperature change when a current change is measured.

The object of the present invention is to propose a current sensing resistor including a substrate, a resistance layer, two front electrodes, two back electrodes and two conductive layers. The substrate has negative temperature coefficient (NTC) characteristics and has a front surface, two side surfaces and a back surface. The resistive layer is disposed on the front side of the substrate. The two front electrodes are spaced apart on the resistive layer, so that the resistive layer is located between the substrate and the two front electrodes. Two backside electrodes are spaced apart on the backside of the substrate. One of the two conductive layers partially covers one of the two front electrodes and covers one of the two back electrodes and one of the two side surfaces of the substrate, so that the one of the two front electrodes is electrically connected to the one of the two back electrodes.

In some embodiments, the current sensing resistor further includes a first protective layer disposed on the resistive layer and partially covering the two front electrodes.

In some embodiments, the above-mentioned current sensing resistor further includes a second protective layer covering the first protective layer and partially covering the two front electrodes.

In some embodiments, the above-mentioned two conductive layers partially cover the second protective layer.

In some embodiments, the above-mentioned current sensing resistor further includes an intermediate electrode disposed on the back surface of the substrate. The above-mentioned intermediate electrode is located between two back electrodes and is disposed on the back surface of the substrate spaced apart from the two back electrodes.

The object of the present invention is to propose a method for manufacturing a current sensing resistor, which includes: providing a substrate having a front face, two side faces and a back face, and being made of a negative temperature coefficient material; forming a resistance layer on the front face of the substrate; Form two front electrodes on the resistive layer so that the resistive layer is located between the substrate and the two front electrodes, wherein the two front electrodes are spaced apart; form two back electrodes on the back side of the substrate, wherein the two back electrodes are spaced apart; form two A conductive layer, wherein one of the two conductive layers partially covers one of the two front electrodes and covers one of the two back electrodes and one of the two side surfaces of the substrate, so that the one of the two front electrodes is electrically connected to the two back electrodes The one who deserves it.

In some embodiments, the above manufacturing method further includes: forming a first protective layer on the resistive layer, wherein the first protective layer partially covers the two front electrodes.

In some embodiments, the above manufacturing method further includes: forming a second protective layer to cover the first protective layer and partially cover the two front electrodes.

In some embodiments, the resistive layer is formed by printing or coating.

In some embodiments, the above manufacturing method further includes: forming a middle electrode on the back side of the substrate, wherein the middle electrode is located between two back side electrodes and is spaced apart from the two back side electrodes.

In order to make the above-mentioned features and advantages of the present invention more obvious and easy to understand, embodiments are given below and described in detail with reference to the accompanying drawings.

Embodiments of the present invention are discussed in detail below. It is to be appreciated, however, that the embodiments provide many applicable concepts that can be embodied in a wide variety of specific contexts. The embodiments discussed and disclosed are for illustration only and are not intended to limit the scope of the invention. The terms "first", "second", ..., etc. used in this article do not specifically refer to the order or order, but are only used to distinguish components or operations described with the same technical terms.

FIG. 1 is a schematic cross-sectional view of a current sensing resistor 1 according to an embodiment of the present invention. The current sensing resistor 1 includes a substrate 10, a resistance layer 20, front electrodes 30a, 30b, back electrodes 40a, 40b, and conductive layers 50a, 50b.

In the embodiment of the present invention, the substrate 10 is made of a negative temperature coefficient (NTC) material. The negative temperature coefficient material of the present invention is a material whose resistance value decreases as the temperature increases. In other words, the substrate 10 Has a negative temperature coefficient. The substrate 10 is in the shape of a rectangular plate and has a back surface bs, side surfaces lsa and lsb respectively extending upward from opposite sides of the back surface bs, and a front surface fs connecting the top edges of the side surfaces lsa and lsb. As shown in FIG. 1 , the side surface lsa is the left side, and the side lsb is the right side.

The resistance layer 20 has a predetermined resistance value and is disposed on the front surface fs of the substrate 10 . In the embodiment of the present invention, the resistive layer 20 is a resistive film, which is formed on the front side fs of the substrate 10 by printing or coating (such as physical vapor deposition (PVD)).

The front electrodes 30a and 30b are conductive. The front electrodes 30a and 30b are not connected to each other. The front electrodes 30a and 30b are respectively in a rectangular shape and are spaced apart on the resistive layer 20 so that the resistive layer 20 is located between the substrate 10 and the front surface. between electrodes 30a and 30b. The resistance layer 20 is electrically connected to the front electrodes 30a and 30b. The side of each front electrode far away from the other front electrode coincides with the side of the substrate. In the embodiment of the present invention, the front electrodes 30a and 30b are formed on the resistive layer 20 by printing.

The back electrodes 40a and 40b are conductive and are not connected to each other. The back electrodes 40a and 40b are respectively in a rectangular shape and are spaced apart on the back bs of the substrate 10 . The substrate 10 is electrically connected to the back electrodes 40a and 40b. The side of each back electrode that is relatively far away from the other back electrode coincides with the side of the substrate. In the embodiment of the present invention, the back electrodes 40a and 40b are formed on the back bs of the substrate 10 by printing, so that the front electrode 30a and the back electrode 40a are symmetrical to each other, and the front electrode 30b and the back electrode 40b are symmetrical to each other.

The conductive layer 50a partially covers the front electrode 30a and covers the back electrode 40a and the left side lsa of the substrate 10, so that the front electrode 30a is electrically connected to the back electrode 40a. In the embodiment of the present invention, the conductive layer 50a that electrically connects the front electrode 30a to the back electrode 40a serves as the input terminal.

The conductive layer 50b partially covers the front electrode 30b and covers the back electrode 40b and the right side lsb of the substrate 10, so that the front electrode 30b is electrically connected to the back electrode 40b. In the embodiment of the present invention, the conductive layer 50b that electrically connects the front electrode 30b to the back electrode 40b serves as the output terminal. The conductive layer 50a and the conductive layer 50b are symmetrical to each other.

Please refer to FIG. 1 again. The current sensing resistor 1 further includes a first protective layer 60 disposed on the resistive layer 20 and partially covering the front electrodes 30a and 30b. Specifically, the first protective layer 60 is formed on the area between the two front electrodes 30a and 30b above the resistive layer 20, so that the first protective layer 60 is located between the two front electrodes 30a and 30b. In the embodiment of the present invention, the first protective layer 60 is made of insulating material and covers the resistive layer 20 to isolate the resistive layer 20 from the outside world.

Please refer to FIG. 1 again. The current sensing resistor 1 further includes a second protective layer 70. The second protective layer 70 is made of an insulating material. The second protective layer 70 covers the first protective layer 60 and partially covers the two front electrodes 30a. , 30b, to isolate the resistance layer 20 and the first protective layer 60 from the outside world. As shown in FIG. 1 , the conductive layers 50a and 50b partially cover the second protective layer 70 .

Please refer to FIG. 1 again. The current sensing resistor 1 further includes a middle electrode 40c. The middle electrode 40c is conductive. The middle electrode 40c is in a long rectangular shape and is disposed on the back side bs of the substrate 10. The substrate 10 is electrically connected to the intermediate electrode 40c. Specifically, the middle electrode 40c is located between the back electrodes 40a and 40b, and the middle electrode 40c and the back electrodes 40a and 40b are spaced apart from each other on the back bs of the substrate 10.

Please refer to FIG. 1 again, the current sensing resistor 1 further includes a conductive layer 50c, and the conductive layer 50c covers the middle electrode 40c. In the embodiment of the present invention, the conductive layer 50c is an intermediate node.

Please refer to FIG. 1 again. The current sensing resistor 1 further includes a third protective layer 80 . The third protective layer 80 is disposed on the back side bs of the substrate 10 . Specifically, the third protective layer 80 is located on the area between the conductive layers 50a, 50b and 50c below the back surface bs of the substrate 10, so that the third protective layer 80 is located between the conductive layers 50a, 50b and 50c. In the embodiment of the present invention, the third protective layer 80 is made of insulating material and covers the substrate 10 to isolate the substrate 10 from the outside world.

FIG. 2 is a schematic diagram of the welding surface of the bottom of the current sensing resistor 1 according to an embodiment of the present invention. Specifically, the composition of the current sensing resistor 1 shown in Figure 1 constitutes a chip resistor, and the conductive layers 50a, 50b, 50c located at the bottom thereof are solderable electrode junctions and the conductive layers 50a, 50b, 50c Separated by the third protective layer 80 , the power supply current sensing resistor 1 is welded to the circuit board, thereby achieving electrical connection between the input terminal IN, the intermediate node MID and the output terminal OUT of the current sensing resistor 1 and the circuit board.

FIG. 3 is a schematic equivalent circuit diagram of the current sensing resistor 1 according to an embodiment of the present invention. The current sensing resistor 1 uses a substrate 10 made of a negative temperature coefficient material as a chip resistance carrying substrate to form a double parallel resistance element connected in parallel with the resistance formed by the resistance layer 20 . Specifically, the resistor composed of the resistive layer 20 is represented by the resistor R1 in FIG. 3 , and the resistor R1 is electrically connected between the input terminal IN and the output terminal OUT; in addition, the substrate 10 is composed of a negative temperature coefficient material. The negative temperature coefficient resistor is represented by the negative temperature coefficient resistor R2 in Figure 3. The negative temperature coefficient resistor R2 includes a negative temperature coefficient resistor between the conductive layer 50a and the conductive layer 50c, which is electrically connected to the input terminal IN and the intermediate node MID. The negative temperature coefficient resistor R2 also includes a negative temperature coefficient resistor between the conductive layer 50c and the conductive layer 50b, which is electrically connected between the intermediate node MID and the output terminal OUT.

In the embodiment of the present invention, the resistance value of the negative temperature coefficient resistor R2 composed of the substrate 10 made of negative temperature coefficient material is much greater (for example, thousands of times or more) than the resistance value of the resistor R1 composed of the resistive layer 20 . Tens of thousands times), therefore the temperature resistance impedance of the substrate 10 can be measured using the input terminal IN, the output terminal OUT and the middle node MID that are electrically connected to the back electrodes 40a, 40b and the middle electrode 40c.

For example, the input terminal IN and the output terminal OUT of the current sensing resistor 1 can be used to measure the tiny current flowing through the substrate 10, and the known negative temperature coefficient characteristics can be used to convert the temperature of the substrate 10, and The current flowing through the substrate 10 is controlled according to the calculated temperature.

For example, when you want to confirm the position of the heat source, you can use the input terminal IN and the middle node MID of the current sensing resistor 1 to measure the input current flowing into the substrate 10, and use the middle node MID and the middle node MID of the current sensing resistor 1. The output terminal OUT is used to measure the output current flowing out of the substrate 10, thereby using the known negative temperature coefficient characteristics to calculate the temperature of the substrate 10 near the input end and the output end by converting the input current and the output current, thereby knowing the proximity of the heat source. Input or output.

FIG. 4 is a flow chart of a manufacturing method of the current sensing resistor 1 according to an embodiment of the present invention, including steps S1 to S5. Please refer to Figure 1 and Figure 4 together. In step S1, a substrate 10 is provided. In step S2 , the resistive layer 20 is formed on the front surface fs of the substrate 10 by printing or coating. In step S3, front electrodes 30a and 30b are formed on the resistive layer 20 so that the resistive layer 20 is located between the substrate 10 and the front electrodes 30a and 30b, wherein the front electrodes 30a and 30b are spaced apart. In step S4, backside electrodes 40a and 40b are formed on the backside bs of the substrate 10, where the backside electrodes 40a and 40b are spaced apart. In step S5, conductive layers 50a and 50b are formed, wherein conductive layer 50a partially covers the front electrode 30a and covers the back electrode 40a and the side surface lsa of the substrate 10, so that the front electrode 30a is electrically connected to the back electrode 40a, and the conductive layer 50b partially covers The ground covers the front electrode 30b and the back electrode 40b and the side surface lsb of the substrate 10, so that the front electrode 30b is electrically connected to the back electrode 40b.

In the embodiment of the present invention, after forming the front electrodes 30a and 30b, the manufacturing method of the current sensing resistor 1 further includes: forming a first protective layer 60 on the resistive layer 20, and the first protective layer 60 is located on the front electrode 30a. , 30b, wherein the first protective layer 60 partially covers the front electrodes 30a, 30b.

In an embodiment of the present invention, after the first protective layer 60 is formed, the manufacturing method of the current sensing resistor 1 further includes: forming a second protective layer 70 to cover the first protective layer 60 and partially cover the front electrode 30a, 30b.

In an embodiment of the present invention, the manufacturing method of the current sensing resistor 1 further includes: forming an intermediate electrode 40c on the backside bs of the substrate 10, wherein the middle electrode 40c is located between the backside electrodes 40a, 40b, wherein the backside electrodes 40a, 40b. 40b is spaced apart from the middle electrode 40c.

In an embodiment of the present invention, after forming the middle electrode 40c, the manufacturing method of the current sensing resistor 1 further includes: forming a conductive layer 50c, wherein the conductive layer 50c covers the middle electrode 40c.

In the embodiment of the present invention, after forming the conductive layer 50c, the manufacturing method of the current sensing resistor 1 further includes: forming a third protective layer 80 on the back side bs of the substrate 10, wherein the third protective layer 80 is located on the conductive layer Between 50a, 50b and 50c.

Based on the above, the present invention proposes a current sensing resistor that uses a substrate made of negative temperature coefficient material as a chip resistance carrying substrate to form a double parallel resistance element connected in parallel with the resistance formed by the resistance layer.

The features of several embodiments are summarized above, so that those skilled in the art can better understand the aspects of the present invention. Those skilled in the art should understand that they can easily use the present invention as a basis to design or modify other processes and structures to achieve the same goals and/or achieve the same advantages as the embodiments introduced here. . Those skilled in the art should also understand that these equivalent structures do not deviate from the spirit and scope of the present invention, and they can make various changes, substitutions and changes without departing from the spirit and scope of the present invention.

1: Current sensing resistor 10:Substrate 20: Resistance layer 30a, 30b: Front electrode 40a, 40b: Back electrode 40c: middle electrode 50a, 50b, 50c: conductive layer 60: First protective layer 70: Second protective layer 80:Third protective layer bs: back fs: front IN: input terminal lsa,lsb: side MID: intermediate node OUT: output terminal R1: Resistor R2: negative temperature coefficient resistor S1-S5: Steps

The aspect of the present invention can be better understood from the following detailed description combined with the accompanying drawings. It should be noted that, in accordance with standard industry practice, features are not drawn to scale. In fact, the dimensions of each feature may be arbitrarily increased or decreased for clarity of discussion. [Fig. 1] is a schematic cross-sectional view of a current sensing resistor according to an embodiment of the present invention. [Fig. 2] is a schematic diagram of the soldering surface of the bottom of the current sensing resistor according to the embodiment of the present invention. [Fig. 3] is a schematic equivalent circuit diagram of a current sensing resistor according to an embodiment of the present invention. [Fig. 4] is a flow chart of a method of manufacturing a current sensing resistor according to an embodiment of the present invention.

1: Current sensing resistor

10:Substrate

20: Resistance layer

30a, 30b: Front electrode

40a, 40b: Back electrode

40c: middle electrode

50a, 50b, 50c: conductive layer

60: First protective layer

70: Second protective layer

80:Third protective layer

bs: back

fs: front

1sa,1sb: side

Claims (10)

A current sensing resistor including: A substrate has a negative temperature coefficient and has a front surface, two side surfaces and a back surface; a resistive layer disposed on the front side of the substrate; Two front electrodes are spaced apart on the resistive layer, so that the resistive layer is located between the substrate and the front electrodes; Two backside electrodes are spaced apart on the backside of the substrate; and Two conductive layers, wherein one of the conductive layers partially covers one of the front electrodes and covers one of the back electrodes and one of the side surfaces of the substrate, so that the front electrodes The other ones are electrically connected to the back electrodes. The current sensing resistor as described in claim 1 further includes: A first protective layer is disposed on the resistive layer and partially covers the front electrodes. The current sensing resistor as described in claim 2 further includes: A second protective layer covers the first protective layer and partially covers the front electrodes. The current sensing resistor of claim 3, wherein the conductive layers partially cover the second protective layer. The current sensing resistor as described in claim 1 further includes: An intermediate electrode is provided on the back surface of the substrate, wherein the intermediate electrode is located between the back electrodes and is spaced apart from the back electrodes on the back surface of the substrate. A method of manufacturing a current sensing resistor, including: Provide a substrate having a front face, two side faces and a back face, wherein the substrate is made of a negative temperature coefficient material; forming a resistive layer on the front side of the substrate; Forming two front-side electrodes on the resistive layer such that the resistance layer is located between the substrate and the front-side electrodes, wherein the front-side electrodes are spaced apart; Forming two backside electrodes on the backside of the substrate, wherein the backside electrodes are spaced apart; and Two conductive layers are formed, wherein one of the conductive layers partially covers one of the front electrodes and covers one of the back electrodes and one of the side surfaces of the substrate, so that the front electrodes The one is electrically connected to the one of the back electrodes. The manufacturing method as described in claim 6 further includes: A first protective layer is formed on the resistive layer, wherein the first protective layer partially covers the front electrodes. The manufacturing method as described in claim 7 further includes: A second protective layer is formed to cover the first protective layer and partially cover the front electrodes. The manufacturing method as claimed in claim 8, wherein the resistive layer is formed by printing or coating. The manufacturing method as described in claim 6 further includes: An intermediate electrode is formed on the back surface of the substrate, wherein the intermediate electrode is located between the back electrodes and is spaced apart from the back electrodes.

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