Thermal protection type piezoresistor component

Abstract

The utility model discloses a thermal protection type piezoresistor component, which comprises a chip-type voltage-sensitive chip, a pin support and an insulating plastic package layer, the pin support comprises an upper pin support, a middle pin support and a lower pin support, and the lower surface of the chip-type voltage-sensitive chip is connected with one end of the lower pin support; one end of the suspended upper and middle pin support is connected with the upper surface of the sheet-type pressure-sensitive chip through the fusible metal, the sheet-type pressure-sensitive chip, the main bodies of the pin supports and the fusible metal are packaged in the insulating plastic packaging layer, and the other ends of the two pin supports extend out of the insulating plastic packaging layer. Compared with the existing varistor component, the varistor disclosed by the utility model has the advantages that a temperature protector and a ceramic chip are eliminated, the product can be made to be smaller, and the cost is lower. Moreover, the chip-type pressure-sensitive chip, the pin support, the jump piece and the fusible metal are all packaged in the insulating plastic packaging layer through plastic packaging, and the whole process can be operated through a machine, thereby improving the production efficiency, and achieving the batch production.

Description

Technical Field

[0001] This utility model relates to a thermally protected varistor component, belonging to the field of electronic component technology. Background Technology

[0002] Varistors (MOVs) experience performance degradation during use or after prolonged use, such as a decrease in varistor voltage and an increase in leakage current. This leads to a significant increase in the current passing through the varistor, causing the product temperature to rise and eventually resulting in product explosion. In severe cases, this can cause electric arcing and open flames. To avoid these situations, over-temperature protection varistors (TMOVs) have been developed.

[0003] There are currently two main types of thermally protected varistors (TMOVs) on the market:

[0004] (1) Varistor + Temperature Fuse: The pre-welded varistor and temperature fuse are bonded together and then encapsulated with epoxy resin. The advantage of this type of product is its simple structure; the disadvantages are its large size, slow response speed, and high cost.

[0005] (2) Varistor + Ceramic Body + Fuseable Metal: First, the ceramic sheet (or ceramic device base) is bonded and fixed onto the chip varistor. Then, leads are soldered to both sides of the chip. Next, one end of the fuseable metal is soldered to the third lead fixed on the ceramic sheet, and the other end of the fuseable metal is soldered to the chip varistor on the same side (some ceramic devices have a cover, which is then added). Finally, it is encapsulated with environmentally friendly resin material. The disadvantages of this type of product are its large size, the fact that the soldering temperature affects the fuseable metal, the fact that the epoxy resin curing temperature affects the fuseable metal, the fact that most of the work is done manually, and the poor consistency of product quality.

[0006] The thermal fuses or thermal circuit breakers mentioned above are single components consisting of leads connected to both ends of a fusible metal. The fusible metal is generally tin or a tin alloy.

[0007] Both of these types of products require manual insertion by customers, which is inefficient. To improve customer efficiency, a shell and potting process is used, which results in a larger size and higher cost.

[0008] There is an urgent market demand for a miniaturized, low-cost, mass-producible, and machine-insertable varistor for over-temperature protection. Summary of the Invention

[0009] The purpose of this invention is to provide a thermally protected varistor. This thermally protected varistor has advantages such as miniaturization, low cost, and mass production capability.

[0010] The technical solution of this utility model is as follows: A thermally protected varistor component includes a chip varistor, a lead frame, and an insulating plastic encapsulation layer. The lead frame includes an upper middle lead frame and a lower lead frame. The lower surface of the chip varistor is connected to one end of the lower lead frame. One end of the suspended upper middle lead frame is connected to the upper surface of the chip varistor via a fusible metal. The chip varistor, the main body of the lead frame, and the fusible metal are encapsulated inside the insulating plastic encapsulation layer. The other ends of the two lead frames extend outside the insulating plastic encapsulation layer.

[0011] In the aforementioned thermally protected varistor component, the lead bracket further includes an upper lead bracket. One end of the suspended upper lead bracket is connected to the upper surface of the chip varistor via a jumper. The main body of the upper lead bracket and the jumper are encapsulated inside an insulating plastic encapsulation layer, and the other end of the upper lead bracket extends outside the insulating plastic encapsulation layer.

[0012] In the aforementioned thermally protected varistor component, the chip varistor is a circular, square, or other polygonal chip varistor.

[0013] In the aforementioned thermally protected varistor device, the jumper is a flat sheet of conductive metal material.

[0014] In the aforementioned thermally protected varistor device, the fusible metal is a cylindrical, square, or elongated strip structure made of tin or a tin alloy.

[0015] In the aforementioned thermally protected varistor device, the insulating encapsulation layer is an insulating material layer composed of one or more of epoxy resin, liquid crystal polymer, polycarbonate, ABS plastic material, polyethylene, and phenolic resin.

[0016] In the aforementioned thermally protected varistor component, the lead bracket is a flat lead bracket.

[0017] The beneficial effects of this invention are as follows: Compared with the prior art, the varistor component of this invention includes a chip-type varistor chip, a lead frame, a jumper, a fusible metal, and an insulating plastic encapsulation layer. Compared with existing varistor components, by connecting one end of the fusible metal to the suspended lead frame and the other end to the varistor chip, the thermal fuse and ceramic plate are eliminated, allowing for smaller product size and lower cost. Furthermore, the chip-type varistor chip, lead frame, jumper, and fusible metal are all encapsulated in an insulating plastic encapsulation layer, enabling the entire process to be machine-operated, improving production efficiency and achieving mass production. Attached Figure Description

[0018] Figure 1 This is a top view of the thermally protected two-pin varistor component according to Embodiment 1 of the present invention;

[0019] Figure 2 This is a top view of the thermally protected two-pin varistor component involved in Embodiment 2 of the present invention;

[0020] Figure 3 This is a top view of the thermally protected three-pin varistor component involved in Embodiment 3 of the present invention;

[0021] Figure 4 for Figure 3 Side sectional view.

[0022] Reference numerals: 10 - Chip-type varistor chip; 21 - Upper pin bracket; 22 - Upper-middle pin bracket; 23 - Lower pin bracket; 30 - Jumper; 40 - Fuseable metal; 50 - Insulating plastic encapsulation layer. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.

[0024] Embodiment 1 of this utility model: A thermally protected varistor component, comprising a chip varistor chip 10, a lead frame, a fusible metal 40, and an insulating plastic encapsulation layer 50. The lead frame includes an upper and middle lead frame 22 and a lower lead frame 23. A TMOV-10D471K two-pin varistor component manufactured using these components is shown below. Figure 1 As shown, the specific structure is as follows:

[0025] The 10D471K chip (chip varistor 10) is connected to the lower lead frame 23; one end of the fusible metal 40 is connected to the suspended upper lead frame 22, and the other end of the fusible metal 40 is connected to the upper surface of the chip varistor 10. The insulating plastic encapsulation layer 50 encapsulates the soldered chip varistor 10, the main body of the two lead frames, and the fusible metal 40 inside it. The other end of the two lead frames extends to the outside of the insulating plastic encapsulation layer 50, thus forming a thermally protected plastic-encapsulated TMOV-10D471K two-pin product.

[0026] Embodiment 2 of this utility model: A thermally protected varistor component, comprising a chip varistor chip 10, a lead frame, a fusible metal 40, and an insulating plastic encapsulation layer 50. The lead frame includes an upper lead frame 21, an upper-middle lead frame 22, and a lower lead frame 23. A TMOV-20D471K two-pin varistor component manufactured using these components is shown below. Figure 2 As shown, the specific structure is as follows:

[0027] Connect the 20D471K chip (chip varistor 10) and the lower lead frame 23; connect one end of the fusible metal 40 to the suspended upper lead frame 22, and the other end of the fusible metal 40 to the upper surface of the chip varistor 10. The insulating plastic encapsulation layer 50 encapsulates the soldered chip varistor 10, the main body of the three lead frames, and the fusible metal 40 inside it. The other ends of the three lead frames extend outside the insulating plastic encapsulation layer 50, but the part of the upper lead frame 21 exposed outside the fusible metal 40 needs to be cut off. Then, a plastic-encapsulated TMOV-20D471K two-pin product for over-temperature protection is formed.

[0028] Embodiment 3 of this utility model: A thermally protected varistor component, comprising a chip varistor chip 10, a lead frame, a jumper 30, a fusible metal 40, and an insulating plastic encapsulation layer 50. The lead frame is divided into an upper lead frame 21, an upper-middle lead frame 22, and a lower lead frame 23. A TMOV-20D471 three-pin varistor component manufactured using these components is shown below. Figure 3 and 4 As shown, the specific structure is as follows:

[0029] The 20D471K varistor chip (chip varistor chip 10) is connected to the lower pin bracket 23; one end of the jumper 30 is connected to the upper surface of the chip varistor chip 10, and the other end of the jumper 30 is connected to the suspended upper pin bracket 21; one end of the fusible metal 40 is connected to the suspended upper middle pin bracket 22, and the other end of the fusible metal 40 is connected to the upper surface of the chip varistor chip 10. The insulating plastic encapsulation layer 50 encapsulates the soldered chip varistor chip 10, the main body of the three pin brackets, the jumper 30, and the fusible metal 40 inside it. The other ends of the three pin brackets extend to the outside of the insulating plastic encapsulation layer 50, thus forming a plastic-encapsulated TMOV-20D471K three-pin product for over-temperature protection.

[0030] The three embodiments differ in that embodiments one and two are two-pin products, but embodiment two has an upper pin bracket 21 encapsulated in plastic, although the encapsulated upper pin bracket 21 is not connected to other components. Embodiment three differs from embodiment one in that embodiment three is a three-pin product, with an additional upper pin bracket 21. One end of the upper pin bracket 21, which is encapsulated, is connected to the upper surface of the chip pressure-sensitive chip 10 via a jumper 30, and the other end of the upper pin bracket 21 also extends outside the insulating plastic encapsulation layer 50.

[0031] In the above embodiments, the specific structures of each component are as follows:

[0032] The chip-type pressure-sensitive chip 10 can be circular, square, or other polygonal, with diverse structures and is not limited to a certain structural form, thus adapting to different product structures.

[0033] The jumper 30 is a flat sheet of conductive metal material, which is easy to process and easy to connect with other components. It can also reduce the thickness of the entire product, making the product smaller.

[0034] The fusible metal 40 is a cylindrical, square, or elongated strip structure made of tin or tin alloy with a protection temperature of 120℃~250℃. When the temperature is exceeded, the fusible metal 40 melts, thereby enabling the product to have over-temperature protection.

[0035] The insulating molding layer 50 is an insulating material layer composed of one or more of epoxy resin, liquid crystal polymer, polycarbonate, ABS plastic material, polyethylene, and phenolic resin, ensuring good insulation performance.

[0036] The pin bracket is a flat pin bracket, which is easy to process and easy to connect with other components. It can also reduce the thickness of the entire product, making the product smaller.

Claims

1. A thermally protected varistor component, comprising a chip varistor chip (10), a lead frame, and an insulating plastic encapsulation layer (50), characterized in that: The pin bracket includes an upper middle pin bracket (22) and a lower pin bracket (23). The lower surface of the chip varistor (10) is connected to one end of the lower pin bracket (23). One end of the suspended upper middle pin bracket (22) is connected to the upper surface of the chip varistor (10) via a fusible metal (40). The chip varistor (10), the main body of the pin bracket, and the fusible metal (40) are encapsulated inside an insulating plastic encapsulation layer (50). The other ends of the two pin brackets extend to the outside of the insulating plastic encapsulation layer (50).

2. The thermally protected varistor component according to claim 1, characterized in that: The pin bracket also includes an upper pin bracket (21). One end of the suspended upper pin bracket (21) is connected to the upper surface of the chip pressure-sensitive chip (10) via a jumper (30). The main body of the upper pin bracket (21) and the jumper (30) are encapsulated inside the insulating plastic encapsulation layer (50). The other end of the upper pin bracket (21) extends to the outside of the insulating plastic encapsulation layer (50).

3. The thermally protected varistor device according to claim 1, characterized in that: The chip pressure-sensitive chip (10) is a circular, square or other polygonal chip pressure-sensitive chip.

4. The thermally protected varistor component according to claim 2, characterized in that: The jumper (30) is a flat sheet of conductive metal material.

5. A thermally protected varistor device according to claim 1, characterized in that: The fusible metal (40) is a cylindrical, square, or long and flat strip structure made of tin or tin alloy.

6. The thermally protected varistor component according to claim 1, characterized in that: The insulating molding layer (50) is an insulating material layer of one or more of epoxy resin, liquid crystal polymer, polycarbonate, ABS plastic material, polyethylene, and phenolic resin.

7. A thermally protected varistor device according to claim 1 or 2, characterized in that: The pin holder is a flat pin holder.

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