Current sensing resistor and manufacturing method thereof

Abstract

The invention provides a current sensing resistor and a manufacturing method thereof. The current sensing resistor comprises a resistive layer, two first electrodes and a second electrode, wherein the resistive layer is provided with a first surface and a second surface; the first surface and the second surface are respectively located on two opposite sides of the resistive layer. The first electrodes are located on the first surface of the resistive layer and located at the two opposite ends of the first surface respectively. The second electrode is located on the second surface of the resistance layer, the area, overlapped with the resistance layer, of the second electrode stretches across the two first electrodes, and the second electrode is overlapped with at least one part of each first electrode. Therefore, one first electrode can be electrically connected to the other first electrode through the second electrode, and the heat dissipation efficiency is further improved.

Description

Technical Field

[0001] The present disclosure relates to a current sensing resistor, and more particularly to a current sensing resistor with heat dissipation function and a manufacturing method thereof. Background Art

[0002] The existing current sensing resistor is a pair of electrodes arranged at both ends of the substrate carrier, and the resistance layer is formed under the pair of electrodes and distributed between the pair of electrodes. Generally speaking, when the current flows through the current sensing resistor, the heat generated is dissipated from the substrate carrier (for example, ceramic) by air convection or thermal radiation, or the heat is conducted to the circuit board through the electrodes at both ends, thereby achieving overall heat dissipation of the current sensing resistor. Since the heat energy is mainly generated by the resistance layer, the heat energy is easily concentrated on the substrate carrier between the above-mentioned electrodes. However, the indirect heat dissipation efficiency through air convection or thermal radiation of the substrate carrier is not good, so it is difficult to improve the situation where the temperature of the current sensing resistor is too high.

[0003] On the other hand, based on the law of resistance, if the material remains unchanged and the electrode spacing is fixed, if you want to reduce the resistance of the resistor layer, you must increase its thickness to increase the cross-sectional area through which the current passes. However, the size of the current sensing resistor is limited by the specifications of the electronic component product, so it is impossible to arbitrarily reduce the resistance by increasing the thickness of the resistor layer. Summary of the invention

[0004] Therefore, the present disclosure provides a current sensing resistor and a manufacturing method thereof to improve the heat dissipation efficiency of the current sensing resistor.

[0005] The present disclosure provides a current sensing resistor, which includes a resistor layer, two first electrodes and a second electrode. The resistor layer has a first surface and a second surface, and the first surface and the second surface are respectively located on opposite sides of the resistor layer. The two first electrodes are located on the first surface of the resistor layer and are respectively located at opposite ends of the first surface. The second electrode is located on the second surface of the resistor layer, and the area where the second electrode overlaps with the resistor layer spans between the two first electrodes. The second electrode overlaps at least a portion of each first electrode.

[0006] In at least one embodiment of the present disclosure, the resistivity of the second electrode is smaller than the resistivity of the resistance layer.

[0007] In at least one embodiment of the present disclosure, the current sensing resistor further includes two protective layers. The protective layers are respectively located on the first surface and the second surface of the resistor layer, and the first electrode and the second electrode are located between the two protective layers. The protective layer located on the first surface covers the first electrode and exposes the area of ​​the first electrode respectively, and the protective layer located on the second surface covers the second electrode.

[0008] In at least one embodiment of the present disclosure, the current sensing resistor further includes two solder materials. The solder materials are respectively located on the first electrode and are electrically connected to the first electrode. The solder materials cover the area of ​​the first electrode exposed by the protective layer.

[0009] In at least one embodiment of the present disclosure, each solder material includes a solder layer and an electrode layer. The electrode layer is located between the solder layer and one of the first electrodes, wherein the solder layer and the electrode layer have an interface, and the protective layer located on the first surface has a top surface. The interface protrudes from the top surface, and the distance between the interface and the top surface is greater than 5 μm.

[0010] In at least one embodiment of the present disclosure, each solder material has an interface between one of the first electrodes, and the protection layer on the first surface has a top surface. The interface protrudes from the top surface, and the distance between the interface and the top surface is greater than 5 μm.

[0011] In at least one embodiment of the present disclosure, the current sensing resistor further includes a resistance repairing region located on the first electrode and extending to the resistance layer.

[0012] The present disclosure also provides a method for manufacturing a current sensing resistor, comprising providing a resistor layer, wherein the resistor layer has a first surface and a second surface; forming two first electrodes on the first surface of the resistor layer, wherein the first electrodes are respectively located at opposite ends of the first surface; and forming a second electrode on the second surface of the resistor layer, wherein the region where the second electrode overlaps with the resistor layer spans between the two first electrodes. The second electrode overlaps at least a portion of each of the first electrodes.

[0013] In at least one embodiment of the present disclosure, after forming the first electrode, a protective layer is disposed on the resistor layer. The protective layer is located on the first surface of the resistor layer and covers the first electrode. The protective layer exposes the area of ​​the first electrode.

[0014] In at least one embodiment of the present disclosure, after forming the first electrodes, welding materials are formed on the first electrodes respectively, and the welding materials cover the areas of the first electrodes exposed by the protective layer.

[0015] In at least one embodiment of the present disclosure, after forming the second electrode, a protective layer is disposed on the resistor layer, wherein the protective layer is located on the second surface of the resistor layer and covers the second electrode.

[0016] Based on the above, the present disclosure sets a second electrode with a lower resistivity on one side of the resistance layer, so that the current tends to flow from one of the first electrodes through the second electrode to the other first electrode. In this way, the heat generated by the resistance layer can be dispersed to the first electrodes at both ends, and the heat is conducted to the outside through the first electrodes. In addition, the second electrode located on one side of the resistance layer also provides a heat dissipation path, which helps to improve the overall heat dissipation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The embodiments of the present disclosure can be understood from the following detailed description and the accompanying drawings. It should be noted that various features are not drawn to the standard scale in industry practice. In fact, the size of various features may be arbitrarily increased or decreased for clarity of discussion.

[0018] Figure 1 FIG. 4 is a cross-sectional view of a current sensing resistor according to an embodiment of the present disclosure.

[0019] Figure 2 FIG. 1 is a partial three-dimensional diagram illustrating a current sensing resistor according to an embodiment of the present disclosure.

[0020] FIG. 3A to FIG. 3D The figure is a cross-sectional view illustrating a method for manufacturing a current sensing resistor according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0021] The present disclosure will be described in detail with the following embodiments. It should be noted that the following description of the embodiments of the present disclosure is only for illustration and is not intended to exhaustively disclose all implementations or to limit the specific implementations of the present disclosure. For example, the description of "a first feature formed on a second feature" includes multiple implementations, including the first feature being in direct contact with the second feature, and also including additional features being formed between the first feature and the second feature so that the two are not in direct contact. In addition, the same element symbols used in the drawings and the specification will represent the same or similar elements as much as possible.

[0022] In the following text, in order to clearly present the technical features of the present disclosure, the dimensions (such as length, width, thickness and depth) of the elements (such as layers, films, substrates and regions, etc.) in the drawings will be enlarged in a non-proportional manner. Therefore, the description and explanation of the embodiments below are not limited to the dimensions and shapes presented by the elements in the drawings, but should cover the dimensions, shapes and deviations of the two caused by actual processes and / or tolerances. For example, the flat surface shown in the drawings may have rough and / or nonlinear features, and the acute angles shown in the drawings may be rounded. Therefore, the elements presented in the drawings of the present disclosure are mainly for illustration, and are not intended to accurately depict the actual shape of the elements, nor are they used to limit the claims of the present disclosure.

[0023] Please refer to Figure 1 The present embodiment discloses a current sensing resistor 10, which includes a resistor layer 100, a first electrode 120a, a first electrode 120b, and a second electrode 140. The resistor layer 100 has a first surface 100f and a second surface 100s, and the first surface 100f and the second surface 100s are respectively located on opposite sides of the resistor layer 100. The first electrode 120a and the first electrode 120b are located on the first surface 100f of the resistor layer 100, and are respectively located at opposite ends of the first surface 100f. In some embodiments, the resistor layer 100 may include, for example, copper manganese tin (CuMnSn), copper manganese nickel (CuMnNi), other appropriate alloy materials, or any combination of the above materials.

[0024] There is a distance D1 between the first electrode 120a and the first electrode 120b. In the present embodiment, the range of the distance D1 is between 1 / 4 of the length d and 4 / 5 of the length d, with respect to the length d, width w and thickness t of the chip resistor. The length d, width w and thickness t of the chip resistor are respectively equivalent to the length L, width (not shown) and thickness T of the resistor layer 100. Figure 1 As shown. On the other hand, the second electrode 140 is located on the second surface 100s of the resistor layer 100, and the area where the second electrode 140 overlaps with the resistor layer 100 will span between the first electrode 120a and the first electrode 120b. In addition, the second electrode 140 overlaps with at least a portion of the first electrode 120a and the first electrode 120b respectively. Although in the present embodiment, the second electrode 140 covers a portion of the first electrode 120a and the first electrode 120b respectively, the present disclosure is not limited to this. In other embodiments, the second electrode 140 may also completely cover the first electrode 120a and the first electrode 120b.

[0025] The materials of the first electrode 120a, the first electrode 120b and the second electrode 140 may be the same and may include copper. In particular, the resistivity of the second electrode 140 is less than the resistivity of the resistance layer 100. For example, the resistance layer 100 may include a resistivity in the range of 20×10 -8 Ω·m to 55×10 -8 Ω·m (such as copper-nickel, copper-manganese, manganese-copper-tin and copper-related alloys), and the second electrode 140 may include a resistivity of about 1.7×10 -8 When a voltage is applied to the current sensing resistor 10 and a potential difference is generated between the first electrode 120a and the first electrode 120b, the first electrode 120a and the first electrode 120b, the resistor layer 100 and the second electrode 140 are electrically connected to each other, thereby forming a Figure 1 The current path I is shown.

[0026] Since the resistivity of the second electrode 140 is less than the resistivity of the resistor layer 100, the current sensing resistor 10 tends to electrically connect its input end and output end through the second electrode 140 to form a current path I. In detail, the current will be collected from one of the first electrodes (for example, the first electrode 120a), and will reach one end of the second electrode 140 (i.e., the end overlapping with the first electrode 120a) through the first surface 100f and the second surface 100s of the resistor layer 100. Then, the current will travel from one end of the second electrode 140 toward the other end of the second electrode 140. After reaching the other end of the second electrode 140, the current tends to enter the first electrode 120b through the second surface 100s and the first surface 100f of the resistor layer 100.

[0027] Based on the above current tendency, although the first electrode 120a and the first electrode 120b at both ends can be electrically connected through the resistor layer 100, since the resistivity of the second electrode 140 is lower than that of the resistor layer 100, the current ratio of the first electrodes at both ends (i.e., the first electrode 120a and the first electrode 120b) electrically connected through the second electrode 140 is higher than the current ratio of the first electrodes at both ends electrically connected through the resistor layer 100. Further, the resistor layer 100 and the second electrode 140 located between the two first electrodes will electrically connect the first electrode 120a to the first electrode 120b in parallel, and most of the total current will choose to pass through the second electrode 140. Therefore, the resistance value of the current sensing resistor 10 is not only provided by the resistor layer 100, so it is not limited by the size of the resistor layer 100. In detail, when it is necessary to reduce the resistance value of the current sensing resistor 10, the second electrode 140 provides a lower resistance value, and it is no longer necessary to increase the thickness of the resistor layer 100 to increase the cross-sectional area through which the current passes.

[0028] It is worth mentioning that since the first electrode 120a and the first electrode 120b are electrically connected to the resistor layer 100 through the two ends of the first surface 100f and the two ends of the second surface 100s, the heat generated by the resistor layer 100 is concentrated at its two ends, and the heat can be thermally conducted to the outside through the first electrode 120a and the first electrode 120b.

[0029] The current sensing resistor 10 further includes a protection layer 160a and a protection layer 160b, which are respectively located on the first surface 100f and the second surface 100s of the resistor layer 100. Figure 1As shown, the protective layer 160a is located on the first surface 100f, and the protective layer 160b is located on the second surface 100s. The first electrode 120a, the first electrode 120b and the second electrode 140 are located between the protective layer 160a and the protective layer 160b. It is particularly mentioned that the protective layer 160a located on the first surface 100f covers the first electrode 120a and the first electrode 120b, and exposes the regions 120r of the first electrode 120a and the first electrode 120b respectively.

[0030] On the other hand, the protective layer 160b located on the second surface 100s covers the second electrode 140. Although in the present embodiment, the protective layer 160b completely covers the surface (not shown) of the second electrode 140, the present disclosure is not limited thereto. In other embodiments, the protective layer 160b may also expose a portion of the surface of the second electrode 140. The protective layer 160a and the protective layer 160b may include organic polymer materials such as polyimide (PI) and epoxy resin.

[0031] In addition, the current sensing resistor 10 further includes two welding materials 180. The two welding materials 180 are respectively located on the first electrode 120a and the first electrode 120b, and are electrically connected to the first electrode 120a and the first electrode 120b. The welding material 180 covers the area 120r of the first electrode 120a (and the first electrode 120b) exposed by the protective layer 160a.

[0032] like Figure 1 As shown, each welding material 180 also includes a welding layer 180s and an electrode layer 180e, and the electrode layer 180e is located between the welding layer 180s and the first electrode 120a (or the first electrode 120b). There is an interface 180i between the welding layer 180s and the electrode layer 180e, and the protective layer 160a located on the first surface 100f has a top surface 160s. In the present embodiment, the interface 180i protrudes from the top surface 160s, and the distance D2 between the interface 180i and the top surface 160s is greater than 5μm, but the present disclosure is not limited to this. In other embodiments, the distance D2 between the interface 180i and the top surface 160s may also be less than 5μm. The material of the welding layer 180s in the welding material 180 may include, for example, nickel or tin, and the material of the electrode layer 180e may include copper.

[0033] Please refer to Figure 2, the current sensing resistor 10 further includes a resistance trimming region 250. In this embodiment, the resistance trimming region 250 is located on the first electrode 120a and extends to the resistor layer 100, but the disclosure is not limited thereto. In other embodiments, the number of the resistance trimming region 250 is not limited to one, but may be more than one, and they may be distributed on the first electrode 120a or the first electrode 120b.

[0034] Depend on FIG. 3A to FIG. 3D A series of steps in the present disclosure are used to illustrate the manufacturing method of the current sensing resistor in at least one embodiment of the present disclosure. Please also refer to Figure 3A and Figure 3B First, a resistor layer 100 is provided, and the resistor layer 100 has a first surface 100f and a second surface 100s. Next, a second electrode 140 is formed on the second surface 100s of the resistor layer 100. On the other hand, two first electrodes (i.e., a first electrode 120a and a first electrode 120b) are formed on the first surface 100f of the resistor layer 100. The first electrode 120a and the first electrode 120b are respectively located at opposite ends of the first surface 100f, and the region where the second electrode 140 overlaps with the resistor layer 100 spans between the first electrode 120a and the first electrode 120b. In addition, the second electrode 140 partially overlaps with the first electrode 120a and the first electrode 120b, respectively.

[0035] In this embodiment, the first electrode 120a, the first electrode 120b and the second electrode 140 can be formed by, for example, electroplating. For example, a patterned anti-plating protective layer can be provided on the resistor layer 100 by printing, lamination and photolithography, and the anti-plating protective layer can be a photoresist, a removable film or ink. Then, a metal material, such as copper, is deposited on the resistor layer 100 by electroplating. Finally, the patterned anti-plating protective layer is removed by a stripping solvent or water washing to form the first electrode 120a, the first electrode 120b and the second electrode 140 on the resistor layer 100.

[0036] It is particularly noted that in this embodiment, the second electrode 140 is formed first, and then the first electrode 120a and the first electrode 120b are formed. However, the present disclosure is not limited to the above manufacturing sequence. In other words, in other embodiments, the first electrode 120a and the first electrode 120b may be formed first, and then the second electrode 140 is formed.

[0037] Please refer to Figure 3BAfter forming the second electrode 140, a protective layer 160b may be disposed on the resistor layer 100 by laminating, printing or coating. The protective layer 160b is located on the second surface 100s of the resistor layer 100 and covers the second electrode 140. In this embodiment, the protective layer 160b is disposed before forming the first electrode 120a and the first electrode 120b. However, the present disclosure is not limited thereto. In other embodiments, the protective layer 160b may be disposed after forming the first electrode 120a and the first electrode 120b.

[0038] like Figure 3B As shown, the first electrode 120a (or the first electrode 120b) and a portion of the resistor layer 100 may be removed by laser trimming or mechanical processing to form a resistance trimming region 250 for adjusting the resistance to obtain a desired target resistance.

[0039] Next, please refer to Figure 3C After forming the first electrode 120a and the first electrode 120b, a protective layer 160a may be provided on the resistor layer 100 by lamination, printing or coating. The protective layer 160a is located on the first surface 100f of the resistor layer 100 and covers the first electrode 120a and the first electrode 120b. The protective layer 160a exposes the region 120r of the first electrode 120a and the first electrode 120b.

[0040] Please refer to Figure 3D After forming the first electrode 120a and the first electrode 120b (and providing the protective layer 160a), welding materials 180 can be formed on the first electrode 120a and the first electrode 120b respectively by electroplating. These welding materials 180 cover the area 120r of the first electrode 120a (and the first electrode 120b) exposed by the protective layer 160a. In detail, an electrode layer 180e containing copper can be first deposited on the first electrode 120a by electroplating. Then, a welding layer 180s containing nickel or tin is deposited on the electrode layer 180e to provide the function of welding adhesion between the current sensing resistor 10 and the external circuit board. At this point, the current sensing resistor 10 of at least one embodiment of the present disclosure has been basically completed.

[0041] In summary, by setting a second electrode with a lower resistivity on one side of the resistor layer, the current tends to flow from one of the first electrodes through the second electrode to the other first electrode. In this way, the heat generated by the resistor layer can be dispersed to the first electrodes at both ends, and the heat is conducted to the outside through the first electrodes. In addition, the second electrode located on one side of the resistor layer also provides a heat dissipation path, which helps to improve the overall heat dissipation efficiency.

[0042] On the other hand, since the second electrode has provided a lower resistance value, it is not necessary to reduce the resistance value of the current sensing resistor by increasing the thickness of the resistance layer. Therefore, the present disclosure also helps to reduce the overall thickness of the current sensing resistor with a low resistance value.

[0043] Although the present invention has been disclosed as above by way of embodiments, it is not intended to limit the present invention. A person skilled in the art may make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the following claims.

[0044]

Explanation of symbols

[0045] 10: Current sensing resistor

[0046] 100: Resistance layer

[0047] 100f: first surface

[0048] 100s: Second surface

[0049] 120a, 120b: first electrode

[0050] 120r: ​​Region

[0051] 140: Second electrode

[0052] 160a, 160b: Protective layer

[0053] 160s: Top surface

[0054] 180: Welding materials

[0055] 180e: electrode layer

[0056] 180i: Interface

[0057] 180s: welding layer

[0058] 250: Repair area

[0059] D1,D2: Spacing

[0060] I: Current path

[0061] L: Length

[0062] T: thickness.

Claims

1. A current sensing resistor, characterized in that: Include: The resistor layer has a first surface and a second surface, wherein the first surface and the second surface are respectively located at two opposite sides of the resistor layer; Two first electrodes are located on the first surface of the resistance layer and are respectively located at two opposite ends of the first surface; as well as The second electrode is located on the second surface of the resistance layer, wherein the overlapping area of ​​the second electrode and the resistance layer spans between the first electrodes, and the second electrode overlaps at least a portion of each of the first electrodes.

2. The current sensing resistor according to claim 1, characterized in that: The resistivity of the second electrode is lower than the resistivity of the resistance layer.

3. The current sensing resistor according to claim 1, characterized in that: Also includes: Two protective layers are respectively located on the first surface and the second surface of the resistance layer, and the multiple first electrodes and the second electrodes are located between the multiple protective layers, wherein the protective layer located on the first surface covers the multiple first electrodes and exposes the areas of the multiple first electrodes respectively, and the protective layer located on the second surface covers the second electrode.

4. The current sensing resistor according to claim 3, characterized in that: Also includes: Two welding materials are respectively located on the plurality of first electrodes and electrically connected to the plurality of first electrodes, wherein the plurality of welding materials cover the region of the plurality of first electrodes exposed by the protective layer.

5. The current sensing resistor according to claim 4, characterized in that: Each of the plurality of welding materials comprises: Solder layer; and The electrode layer is located between the welding layer and one of the plurality of first electrodes, wherein the welding layer and the electrode layer have an interface, and the protective layer located on the first surface has a top surface, wherein the interface protrudes from the top surface, and the distance between the interface and the top surface is greater than 5 μm.

6. The current sensing resistor according to claim 1, characterized in that: Also includes: The resistance repairing area is located on the plurality of first electrodes and extends to the resistance layer.

7. A method for manufacturing a current sensing resistor, characterized in that: Include: Providing a resistance layer, wherein the resistance layer has a first surface and a second surface; forming two first electrodes on the first surface of the resistance layer, wherein the plurality of first electrodes are respectively located at two opposite ends of the first surface; as well as A second electrode is formed on the second surface of the resistor layer, wherein the region where the second electrode overlaps with the resistor layer spans between the first electrodes, and the second electrode overlaps with at least a portion of each of the first electrodes.

8. The method according to claim 7, characterized in that Also includes: After forming the plurality of first electrodes, a protection layer is disposed on the resistance layer, wherein the protection layer is located on the first surface of the resistance layer and covers the plurality of first electrodes, wherein the protection layer exposes regions of the plurality of first electrodes.

9. The method according to claim 8, characterized in that Also includes: After forming the plurality of first electrodes, welding materials are respectively formed on the plurality of first electrodes, and the plurality of welding materials cover the regions of the plurality of first electrodes exposed by the protective layer.

10. The method according to claim 7, characterized in that Also includes: After forming the second electrode, a protection layer is disposed on the resistance layer, wherein the protection layer is located on the second surface of the resistance layer and covers the second electrode.

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