A resin encapsulated metal film chip resistor

Abstract

The present invention relates to the technical field of resistors, and in particular to a resin-encapsulated metal film chip resistor, comprising an insulating rod and an end cap; a metal film is plated on the insulating rod; the film comprises a thin film section and a thick film section; the thickness of the thin film section is less than that of the thick film section; a first groove is cut on the thin film section; the first groove is first cut on the thin film section of the film so that the resistor obtains a first partial resistance value, wherein the first partial resistance value is less than the final resistance value of the resistor, and the first partial resistance value reaches more than 95% of the final resistance value of the resistor; a rough adjustment of the final resistance value of the resistor is achieved; after measuring the resistance value of the resistor, a second groove is cut on the thick film section to obtain the second partial resistance value; a fine adjustment of the final resistance value of the resistor is achieved; the final resistance value of the resistor is made more accurate, and only one resistance test is required throughout the whole process, thereby improving production efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of resistors, and in particular to a resin-encapsulated metal film chip resistor. Background Art

[0002] Resistors are generally called resistors in daily life. They are current limiting components. When the resistor is connected to the circuit, it can limit the current passing through the branch it is connected to. There are many types of resistors, and the more commonly used ones are metal film resistors. Metal film resistors are a type of film resistor. In the prior art, such as the Chinese patent with publication number CN105590709A, named a resin-encapsulated metal film chip resistor, the public technical solution records that high-temperature vacuum coating technology is used to tightly attach nickel-chromium or similar alloys to the surface of the porcelain rod to form a film, and multiple grooves for adjusting the resistance value are opened on the surface of the film to achieve the final required precision resistance value.

[0003] In order to ensure that the resistance error of metal film resistors is as low as possible, it is necessary to open cutting lines of different shapes on the resistors. Since the resistance value of each resistor before processing is different, even if the resistance value of the resistor is pre-detected before cutting the resistor and the shape of the cutting line is adjusted according to the detected resistance value, the resistance value will be inaccurate due to the uneven thickness of the metal film along the circumferential direction, affecting the final resistance value of the resistor. Cutting different cutting lines for different resistors is a relatively costly operation. For this reason, in the actual production of resistors, fixed-shaped cutting lines are often used to cut the film to reduce costs. However, due to the inconsistent thickness of the metal film sputtered on the surface of the porcelain rod by vacuum, the resistance error of the resistor is large when the film is cut using a fixed-shaped cutting line. Summary of the invention

[0004] The present invention provides a resin-encapsulated metal film chip resistor to solve the above problems.

[0005] A resin-encapsulated metal film chip resistor of the present invention adopts the following technical scheme: a resin-encapsulated metal film chip resistor, comprising an insulating rod and an end cap; a metal film is plated on the side wall of the insulating rod; the film comprises a thin film section and a thick film section; the thickness of the thin film section is less than that of the thick film section; a first groove is cut on the thin film section; the first groove is spiral; the first groove is used to obtain a first partial resistance value; a second groove is cut on the thick film section; the second groove is spiral; the second groove is used to obtain a second partial resistance value; the sum of the first partial resistance value and the second partial resistance value is the final resistance value of the resistor; firstly, the first groove is cut on the thin film section of the film so that the resistor obtains the first partial resistance value, wherein the first partial resistance value is less than the final resistance value of the resistor, and the first partial resistance value reaches more than 95% of the final resistance value of the resistor; the final resistance value of the resistor is roughly adjusted; after the resistance value of the resistor is measured, the second groove is cut on the thick film section to obtain the second partial resistance value; the final resistance value of the resistor is finely adjusted;

[0006] Two end caps are provided and fixed at two ends of the insulating rod; the end caps are made of conductive metal; and the outer sides of the end caps and the membrane are wrapped with a resin packaging shell.

[0007] Furthermore, the thin film section is arranged on one side of the thick film section.

[0008] Furthermore, the thick film section is provided with two sections, which are distributed on both sides of the thin film section; the first groove and the second groove are provided near the center of the insulating rod, and a preset distance is reserved between the second groove and the end of the insulating rod, so as to avoid welding materials from filling into the second groove when the end cap is installed and when the end cap is welded on the film, thereby affecting the final resistance value of the resistor.

[0009] Furthermore, the lengths of the two thick film sections in the axial direction of the insulating rod are equal, so that the heating position of the film is more centered, thereby improving the stability of the resistor during use.

[0010] Furthermore, the equipment for processing the thin film segment and the thick film segment includes an insulating sleeve; the insulating sleeve is annular, and the insulating sleeve is made of the same material as the insulating rod; the inner diameter of the insulating sleeve is the same as the diameter of the insulating rod; the processing steps of the thin film segment and the thick film segment include:

[0011] The first step is to put a ring-shaped insulating sleeve on the insulating rod, and move the insulating sleeve to the pre-film-coated section on the insulating rod to cover the pre-film-coated section on the insulating rod;

[0012] The second step is to coat the pre-coated thick film section on the insulating rod by vacuum coating to form a thick film section;

[0013] In the third step, the insulating sleeve is removed, and vacuum coating is performed again on the insulating rod where the thin film segment is pre-coated to form a thin film segment.

[0014] Further, the processing steps of the thin film section and the thick film section include:

[0015] In the first step, vacuum coating is used to form a film with the same thickness as the thick film segment;

[0016] The second step is to apply photoresist on the pre-coated thin film section on the insulating rod, perform exposure and development, and etch away the film on the pre-coated thin film section on the insulating rod;

[0017] The third step is to remove the photoresist;

[0018] In the fourth step, vacuum coating is again used to coat the pre-coated thin film segment on the insulating rod to form a thin film segment.

[0019] Furthermore, a terminal electrode is fixedly connected to the end cap, and one end of the terminal electrode extends to the outside of the resin packaging shell.

[0020] Furthermore, the insulating rod is a porcelain rod.

[0021] Furthermore, the resin packaging shell is made of epoxy resin.

[0022] Furthermore, the end cap is made of iron.

[0023] The beneficial effects of the present invention are:

[0024] 1. First, cut a first groove on the thin film section of the membrane to make the resistor obtain the first part of the resistance, wherein the first part of the resistance is less than the final resistance of the resistor, and the first part of the resistance reaches more than 95% of the final resistance of the resistor; realize the coarse adjustment of the final resistance of the resistor; after measuring the resistance of the resistor, cut a second groove on the thick film section to obtain the second part of the resistance; realize the fine adjustment of the final resistance of the resistor, so that the final resistance of the resistor is more accurate, and only one resistance test is required throughout the process, thereby improving production efficiency.

[0025] 2. When installing the end cap and when the end cap is welded to the membrane, avoid the welding material from filling into the second groove, thereby affecting the final resistance value of the resistor. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0027] Figure 1 A three-dimensional diagram of an embodiment of a resin-encapsulated metal film chip resistor of the present invention;

[0028] Figure 2 A schematic diagram of another angle of an embodiment of a resin-encapsulated metal film chip resistor of the present invention;

[0029] Figure 3 A schematic diagram of an end cap and a film of an embodiment of a resin-encapsulated metal film chip resistor of the present invention;

[0030] Figure 4 A top view of an end cap and a film of an embodiment of a resin-encapsulated metal film chip resistor of the present invention;

[0031] Figure 5 for Figure 4 Sectional view at AA in the middle;

[0032] Figure 6 A front view of an end cap and a film of an embodiment of a resin-encapsulated metal film chip resistor of the present invention;

[0033] Figure 7 This is a schematic diagram of the end caps and membrane of another embodiment of a resin-encapsulated metal film chip resistor of the present invention.

[0034] In the figure: 100, insulating rod; 200, membrane; 210, thin film segment; 211, first groove; 220, thick film segment; 221, second groove; 300, end cap; 400, resin packaging shell; 500, terminal electrode. DETAILED DESCRIPTION

[0035] Embodiments of the present invention will be described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention.

[0036] The features of the terms "first" and "second" in the specification and claims of the present invention may include one or more of the features explicitly or implicitly. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0037] In the description of the present invention, it is to be understood that the terms “center”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0038] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] An embodiment of a resin-encapsulated metal film chip resistor of the present invention is as follows Figures 1 to 7 As shown, a resin-encapsulated metal film chip resistor includes an insulating rod 100 and an end cap 300; the insulating rod 100 is a porcelain rod.

[0040] The side wall of the insulating rod 100 is coated with a metal film 200 made of nickel-chromium or other alloys by high-temperature vacuum coating technology; the film 200 includes a thin film section 210 and a thick film section 220; the thickness of the thin film section 210 is less than that of the thick film section 220; a first groove 211 is cut on the thin film section 210; the first groove 211 is spiral; the first groove 211 is used to obtain the first part of the resistance; a second groove 221 is cut on the thick film section 220; the second groove 221 is spiral; the second groove 221 is used to obtain the second part of the resistance; the sum of the first part of the resistance and the second part of the resistance is the final resistance of the resistor. Two end caps 300 are provided, fixed at both ends of the insulating rod 100; the end caps 300 are conductive metal; the material of the end caps 300 is preferably iron. The end caps 300 and the film 200 are wrapped with a resin packaging shell 400, and the resin packaging shell 400 is made of epoxy resin, which has the characteristics of high temperature resistance, moisture resistance, and good insulation. The end cap 300 is fixedly connected with the terminal electrode 500, and one end of the terminal electrode 500 extends to the outside of the resin package shell 400. SMT automated assembly can be realized, with high assembly efficiency, saving human resources, reducing assembly costs, and being conducive to improving corporate benefits.

[0041] According to the determination formula of resistance, when the length is constant, the larger the cross section, the smaller the resistance. When the thin film segment 210 of the membrane 200 cuts the first groove 211, the resistance value changes greatly, and the rough adjustment of the resistance of the resistor is achieved. When the thick film segment 220 of the membrane 200 cuts the second groove 221, the resistance value changes less, and the fine adjustment of the resistance of the resistor is achieved. Therefore, we first cut the first groove 211 in the thin film segment 210 of the membrane 200, and roughly obtain the first part of the resistance of the resistor in a coarse adjustment manner. The first part of the resistance is close to the final resistance of the resistor. According to the resistance value detected after cutting, the second groove 221 is then cut in the thick film segment 220 of the membrane 200, and the cutting of the second groove 221 is controlled in a fine adjustment manner to obtain the second part of the resistance of the resistor. Since the resistance value of the thick film segment 220 changes less when the second groove 221 is cut in the thick film segment 220 of the film 200 , it is easier to reduce the deviation between the final resistance value of the resistor and the standard resistance value set during the resistor production.

[0042] For example, a first groove 211 is first cut on the thin film segment 210 of the membrane 200 so that the resistor obtains a first partial resistance value, wherein the first partial resistance value is less than the final resistance value of the resistor and the first partial resistance value reaches more than 95% of the final resistance value of the resistor; a coarse adjustment of the final resistance value of the resistor is achieved; after measuring the resistance value of the resistor, a second groove 221 is cut on the thick film segment 220 to obtain a second partial resistance value; a fine adjustment of the final resistance value of the resistor is achieved.

[0043] There are two embodiments for distributing the thin film segments 210 and the thick film segments 220 .

[0044] In the first embodiment of the distribution of the thin film segment 210 and the thick film segment 220, the thin film segment 210 is arranged on one side of the thick film segment 220. The equipment for processing the thin film segment 210 and the thick film segment 220 includes an insulating sleeve; the insulating sleeve is annular, and the insulating sleeve is made of the same material as the insulating rod 100; the inner diameter of the insulating sleeve is the same as the diameter of the insulating rod 100; the processing steps of the thin film segment 210 and the thick film segment 220 are: first, the insulating sleeve is put on the insulating rod 100 with an annular insulating sleeve, and the insulating sleeve is moved to the pre-coated thin film segment 210 on the insulating rod 100 to cover the pre-coated thin film segment 210 on the insulating rod 100; then, the pre-coated thick film segment 220 on the insulating rod 100 is coated by vacuum coating to form the thick film segment 220. Afterwards, the insulating sleeve is removed, and the pre-coated thin film segment 210 on the insulating rod 100 is coated by vacuum coating again to form the thin film segment 210.

[0045] In the second embodiment of the distribution of the thin film segment 210 and the thick film segment 220, the thick film segment 220 is provided with two segments, which are distributed on both sides of the thin film segment 210; the first groove 211 and the second groove 221 are arranged near the center of the insulating rod 100, and a preset distance is reserved between the second groove 221 and the end of the insulating rod 100. When the end cap is installed and the end cap 300 is welded on the membrane 200, it is prevented that the welding material fills into the second groove 221, thereby affecting the final resistance value of the resistor. The two thick film segments 220 have the same length in the axial direction of the insulating rod 100. The heating position of the membrane 200 is more centered, which improves the stability of the resistor during use. Among them, the processing steps of the thin film segment 210 and the thick film segment 220 are: firstly, vacuum coating is used to form a membrane 200 with the same thickness as the thick film segment 220. Then, a photoresist is applied to the pre-coated thin film section 210 on the insulating rod 100, and exposure and development are performed, and the film 200 at the pre-coated thin film section 210 on the insulating rod 100 is etched away. After that, the photoresist is removed, and vacuum coating is performed again to coat the pre-coated thin film section 210 on the insulating rod 100 to form a thin film section 210.

[0046] In combination with the above embodiments, the use principle and working process of the present invention are as follows: first, a first groove 211 is cut on the thin film segment 210 of the membrane 200 so that the resistor obtains a first partial resistance value, wherein the first partial resistance value is less than the final resistance value of the resistor, and the first partial resistance value reaches more than 95% of the final resistance value of the resistor; a coarse adjustment of the final resistance value of the resistor is achieved; after measuring the resistance value of the resistor, a second groove 221 is cut on the thick film segment 220 to obtain the second partial resistance value; a fine adjustment of the final resistance value of the resistor is achieved, so that the final resistance value of the resistor is more accurate, and only one resistance test is required throughout the process, thereby improving production efficiency.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A resin encapsulated metal film chip resistor, characterized in that: It includes an insulating rod and an end cap; a metal film is plated on the side wall of the insulating rod; the film includes a thin film section and a thick film section; the thickness of the thin film section is less than that of the thick film section; a first groove is cut on the thin film section; the first groove is spiral; the first groove is used to obtain a first part of the resistance value; a second groove is cut on the thick film section; the second groove is spiral; the second groove is used to obtain a second part of the resistance value; the sum of the first part of the resistance value and the second part of the resistance value is the final resistance value of the resistor; firstly, the first groove is cut on the thin film section of the film so that the resistor obtains the first part of the resistance value, wherein the first part of the resistance value is less than the final resistance value of the resistor, and the first part of the resistance value reaches more than 95% of the final resistance value of the resistor; the final resistance value of the resistor is roughly adjusted; after the resistance value of the resistor is measured, the second groove is cut on the thick film section to obtain the second part of the resistance value; the final resistance value of the resistor is finely adjusted; There are two end caps fixed at both ends of the insulating rod; the end caps are conductive metal; the end caps and the outer side of the film are wrapped with a resin packaging shell; the equipment for processing the thin film section and the thick film section includes an insulating sleeve; the insulating sleeve is annular, and the insulating sleeve is made of the same material as the insulating rod; the inner diameter of the insulating sleeve is the same as the diameter of the insulating rod; the processing steps of the thin film section and the thick film section include: The first step is to put a ring-shaped insulating sleeve on the insulating rod, and move the insulating sleeve to the pre-film-coated section on the insulating rod to cover the pre-film-coated section on the insulating rod; The second step is to coat the pre-coated thick film section on the insulating rod by vacuum coating to form a thick film section; In the third step, the insulating sleeve is removed, and vacuum coating is performed again on the insulating rod where the thin film segment is pre-coated to form a thin film segment.

2. The resin encapsulated metal film chip resistor according to claim 1, characterized in that: The thin film section is arranged on one side of the thick film section.

3. The resin encapsulated metal film chip resistor according to claim 1, characterized in that: The thick film section is provided with two sections, which are distributed on both sides of the thin film section; the first groove and the second groove are arranged close to the center of the insulating rod, and a preset distance is reserved between the second groove and the end of the insulating rod.

4. The resin encapsulated metal film chip resistor according to claim 3, characterized in that: The lengths of the two thick film sections in the axial direction of the insulating rod are equal.

5. The resin encapsulated metal film chip resistor according to claim 4, characterized in that: Another processing step for thin film and thick film sections includes: In the first step, vacuum coating is used to form a film with the same thickness as the thick film segment; The second step is to apply photoresist on the pre-coated thin film section on the insulating rod, perform exposure and development, and etch away the film on the pre-coated thin film section on the insulating rod; The third step is to remove the photoresist; In the fourth step, vacuum coating is again used to coat the pre-coated thin film segment on the insulating rod to form a thin film segment.

6. A resin encapsulated metal film chip resistor according to any one of claims 1 to 5, characterized in that: The end cap is fixedly connected with a terminal electrode, and one end of the terminal electrode extends to the outside of the resin packaging shell.

7. The resin encapsulated metal film chip resistor according to claim 6, characterized in that: The insulating rod is a porcelain rod.

8. The resin encapsulated metal film chip resistor according to claim 6, characterized in that: The resin packaging shell is made of epoxy resin.

9. The resin encapsulated metal film chip resistor according to claim 6, characterized in that: The end cap is made of iron.

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