Lead frame surface-mounted metal oxide varistor device

Abstract

A lead frame surface mounting metal oxide rheostat device disclosed by the present invention comprises an upper shell, a lower shell and an MOV chip main body, the upper shell and the lower shell are connected to form a closed cavity inside, the MOV chip main body is arranged inside the cavity, two sides of the MOV chip main body are respectively provided with an electrode end, and the electrode ends are connected with the upper shell and the lower shell. Two groups of patch mounting grooves are formed in the positions, corresponding to the two groups of electrode ends, of the lower end of the lower shell, patches are mounted in the patch mounting grooves, the two groups of patches are connected with the corresponding electrode ends through supporting feet and electrode leads in sequence, and a first heat conduction layer, a micro-channel radiator and a second heat conduction layer are arranged on the outer side of the MOV chip body in sequence. The side, away from the micro-channel radiator, of the second heat conduction layer is connected with the inner wall of a cavity formed in the connecting interior of the upper shell and the lower shell. Heat generated on the MOV chip main body is transmitted to the micro-channel radiator through the first heat conduction layer, and the heat is rapidly taken away from a heat source through the micro-channel arranged in the micro-channel radiator, so that chip damage caused by local overheating is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of surface mounted devices, in particular to a lead frame surface mounted metal oxide varistor device. Background Art

[0002] Metal oxide varistor (MOV) is a voltage-dependent, nonlinear device that is commonly used in electronic circuits to provide transient voltage suppression. Metal oxide varistor tends to generate a lot of heat during use, and if the heat cannot be removed from the heat source in time, it is easy to cause device heat concentration and continuous increase in heat flux density, leading to device damage. Summary of the invention

[0003] The present invention aims to solve one of the technical problems in the related art to at least some extent. To this end, one object of the present invention is to provide a lead frame surface mounted metal oxide varistor device, which can quickly remove heat from the heat source to avoid local overheating and chip damage.

[0004] The present invention proposes a lead frame surface mounted metal oxide varistor device, comprising an upper shell, a lower shell and an MOV chip body, wherein the upper shell and the lower shell are connected to form a closed cavity, the MOV chip body is arranged inside the cavity, and electrode terminals are respectively arranged on both sides of the MOV chip body, and two groups of patch mounting grooves are respectively opened at the lower end of the lower shell corresponding to the two groups of electrode terminals, patches are installed inside the patch mounting grooves, and the two groups of patches are respectively connected to the corresponding electrode terminals through supporting feet and electrode leads in sequence, and a first heat conducting layer, a microchannel heat sink and a second heat conducting layer are sequentially arranged on the outer side of the MOV chip body, and the side of the second heat conducting layer away from the microchannel heat sink is connected to the inner wall of the cavity formed by the connection between the upper shell and the lower shell.

[0005] Preferably, a gas expansion chamber is provided inside the cavity formed by the connection of the upper shell and the lower shell, a buffer layer installation chamber is provided inside the expansion chamber, a buffer layer is provided inside the buffer layer installation chamber, an extrusion plate is provided at the upper end of the buffer layer, and the extrusion plate is slidably connected to the inner wall of the buffer layer installation chamber.

[0006] Preferably, the buffer layer mounting cavity is located at the upper end of the microchannel radiator, and a plurality of through holes are provided on the microchannel side wall of the microchannel radiator close to the buffer layer mounting cavity. Micro-protrusions are installed at the positions of the through holes on the extrusion plate corresponding to the positions of the through holes, and one end of the micro-protrusion away from the extrusion plate passes through the buffer layer and is arranged at the upper end of the through hole.

[0007] Preferably, a flexible sealing gasket is installed on one side of the through hole close to the inside of the microchannel, and one end of the micro-protrusion away from the extrusion plate is connected to the flexible sealing gasket.

[0008] Preferably, a limit block is provided on the inner wall of the buffer layer installation cavity below the extrusion plate to prevent excessive displacement of the micro-protrusion.

[0009] Preferably, a temperature sensor is installed on the outer wall of the MOV chip body.

[0010] Preferably, a leg fixing groove is formed on the side wall of the lower shell at the position of the patch mounting groove, and the leg is arranged inside the leg fixing groove.

[0011] Preferably, the buffer layer is a buffer rubber block, and the upper end of the buffer layer abuts against the extrusion plate.

[0012] Preferably, the inner contour of the through hole is matched with the outer contour of the micro-protrusion.

[0013] Preferably, the micro-convex column is cylindrical in shape.

[0014] The beneficial effects of the present invention are:

[0015] (1) The heat generated on the MOV chip body is transferred to the microchannel heat sink through the first heat-conducting layer, and the heat is quickly taken away from the heat source through the microchannels set inside the microchannel heat sink to avoid local overheating and chip damage;

[0016] (2) A gas expansion chamber is provided. When the temperature inside the shell is too high, the gas expansion drives the extrusion plate to move and squeeze the buffer layer, thereby releasing buffer space for the gas expansion and alleviating the phenomenon of chip bulging caused by the thermal expansion of the gas. At the same time, the buffer layer can also relieve the pressure generated by absorbing part of the gas.

[0017] (3) As the temperature changes, the area of ​​the micro-protrusions entering the micro-channel also changes. Therefore, the output power of the micro-channel heat sink can be regulated by the area of ​​the micro-protrusions entering the micro-channel and the surface temperature of the MOV chip body transmitted by the temperature sensor, thereby improving the heat dissipation effect of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In the attached picture:

[0019] Figure 1 This is a schematic diagram of the external structure of the lead frame surface mounted metal oxide varistor device proposed by the present invention;

[0020] Figure 2 This is a structural schematic diagram of the main body of the MOV chip proposed by the present invention;

[0021] Figure 3A cross-sectional view of a lead frame surface mounted metal oxide varistor device proposed by the present invention;

[0022] Figure 4 This is a schematic diagram of the structure of the microchannel near the buffer layer installation cavity proposed by the present invention.

[0023] In the figure: 1-upper shell, 2-lower shell, 3-support leg, 4-MOV chip body, 5-electrode lead, 6-patch, 7-first heat conducting layer, 8-temperature sensor, 9-second heat conducting layer, 10-limiting block, 11-buffer layer, 12-gas expansion chamber, 13-extrusion plate, 14-microchannel radiator, 15-microchannel, 16-through hole, 17-flexible sealing pad, 18-micro-convex column. DETAILED DESCRIPTION

[0024] Reference Figure 1 , Figure 2 and Figure 3 A lead frame surface mounted metal oxide varistor device comprises an upper shell 1, a lower shell 2 and a MOV chip body 4, wherein the upper shell 1 and the lower shell 2 are connected to form a closed cavity, the MOV chip body 4 is arranged inside the cavity, and electrode terminals are arranged on both sides of the MOV chip body 4, two groups of patch mounting grooves are respectively opened at the lower end of the lower shell 2 corresponding to the two groups of electrode terminals, patches 6 are installed inside the patch mounting grooves, and the two groups of patches 6 are respectively connected to the corresponding electrode terminals through the supporting legs 3 and the electrode leads 5 in sequence, and the outer side of the MOV chip body 4 is sequentially provided with a first heat conducting layer 7, a microchannel heat sink 14 and a second heat conducting layer 9, and the second heat conducting layer 9 is connected to the inner wall of the cavity formed by the upper shell 1 and the lower shell 2 at a side away from the microchannel heat sink 14.

[0025] Obviously, based on the above, when the surface temperature of the MOV chip body 4 exceeds the preset temperature, the microchannel heat sink 14 starts to work, and the heat generated by the MOV chip body 4 is discharged through the first heat conducting layer 7, the microchannel heat sink 14 and the second heat conducting layer 9 in sequence.

[0026] In this embodiment, refer to Figure 3 A gas expansion chamber 12 is provided inside the cavity formed by the connection of the upper shell 1 and the lower shell 2, a buffer layer installation chamber is provided inside the expansion chamber 12, a buffer layer 11 is provided inside the buffer layer installation chamber, an extrusion plate 13 is provided at the upper end of the buffer layer 11, and the extrusion plate 13 is slidably connected to the inner wall of the buffer layer installation chamber.

[0027] Obviously, based on the above, the heated air expands due to the heat inside the expansion chamber 12, forming pressure around it. The pressure acts on the upper surface of the extrusion plate 13 to squeeze the buffer layer 11. The buffer layer 11 is squeezed and deformed, which can provide a buffer space for the thermal expansion of the air. At the same time, the buffer layer 11 can absorb part of the pressure generated by the thermal expansion of the air, thereby alleviating the bulging of the chip shell.

[0028] In this embodiment, refer to Figure 3 and Figure 4 The buffer layer installation cavity is located at the upper end of the microchannel heat sink 14. The side wall of the microchannel 15 on the side of the microchannel heat sink 14 close to the buffer layer installation cavity is provided with multiple groups of through holes 16. Micro-protrusions 18 are installed at the positions of the extrusion plate 13 corresponding to the through holes 16. The end of the micro-protrusions 18 away from the extrusion plate 13 passes through the buffer layer 11 and is arranged at the upper end of the through holes 16.

[0029] Obviously, based on the above, when the air expands due to heat and reaches a certain threshold, the extrusion plate 13 is under pressure to drive the micro-protrusions 18 through the through holes 16 into the microchannel 15, so that the pressure drop inside the microchannel becomes larger. Therefore, the output of the microchannel radiator 14 can be regulated by adjusting the area of ​​the micro-protrusions 18 entering the microchannel 15 so that the pressure drop inside the microchannel changes and the heating degree of the gas is fed back.

[0030] In this embodiment, refer to Figure 4 A flexible sealing pad 17 is installed on one side of the through hole 16 close to the inside of the microchannel 15 , and one end of the micro-protrusion 18 away from the extrusion plate 13 is connected to the flexible sealing pad 17 .

[0031] Obviously, based on the above, the provision of the flexible sealing pad 17 can prevent the microchannel 15 from leaking.

[0032] In this embodiment, refer to Figure 3 The inner wall of the buffer layer installation cavity is located below the extrusion plate 13 and is provided with a limit block 10 to prevent excessive displacement of the micro-convex column 18.

[0033] Obviously, based on the above, when the extrusion plate 13 moves downward, it is restricted by the limit block 10 and cannot make the micro-protrusion 18 drop further. Therefore, the micro-protrusion 18 cannot move further after entering the specified position of the micro-channel 15, thereby avoiding excessive displacement of the micro-protrusion 18.

[0034] In this embodiment, refer to Figure 3 A temperature sensor 8 is installed on the outer wall of the MOV chip body 4.

[0035] Obviously, based on the above, the temperature change on the surface of the MOV chip body 4 can be monitored in real time, and the output of the microchannel heat sink 14 can be feedback-regulated by the temperature change on the surface of the MOV chip body 4 .

[0036] In this embodiment, refer to Figure 1 and Figure 2 A leg fixing groove is provided on the side wall of the lower shell 2 at the position of the patch mounting groove, and the leg 3 is arranged inside the leg fixing groove.

[0037] Obviously, based on the above, the provision of the foot fixing groove can further fix the foot 3, and can also provide a limit for the patch 6 during installation to prevent the patch from leaving the preset position.

[0038] In this embodiment, refer to Figure 3 The buffer layer 11 is made of a buffer rubber block, and the upper end of the buffer layer 11 is in contact with the extrusion plate 13 .

[0039] Obviously, based on the above, by utilizing the properties of the buffer rubber block that deforms under stress and recovers naturally when no stress is applied, when the extrusion plate 13 is subjected to gas pressure, the deformation degree of the buffer layer 11 also changes with the change of gas pressure. When there is no gas pressure, the buffer layer 11 can drive the extrusion plate 13 to return to its original state.

[0040] In this embodiment, refer to Figure 4 The inner contour of the through hole 16 is matched with the outer contour of the micro-protrusion 18.

[0041] Obviously, based on the above, the through hole 16 will not hinder the displacement of the micro-protrusion 18.

[0042] In this embodiment, the micro-protrusions 18 are cylindrical in shape.

[0043] Obviously, based on the above, the cylindrical shape of the micro-protrusion 18 can make it easier for the micro-protrusion 18 to move in the through hole 16.

[0044] In order to more clearly illustrate the scheme and effect of this implementation, examples are given in conjunction with the accompanying drawings:

[0045] Reference Figure 1-4When the mounted metal oxide varistor device is working, the MOV chip body 4 will generate heat, and the heat will be conducted out through the device housing by the first heat conducting layer 7, the microchannel heat sink 14 and the second heat conducting layer 9. The temperature sensor 8 monitors the surface temperature of the MOV chip body 4 in real time. When the temperature of the MOV chip body 4 exceeds the preset temperature value, the microchannel heat sink 14 works to quickly take away the heat generated by the MOV chip body 4 when it is working. When the working power of the MOV chip body 4 continues to increase, the surface temperature of the MOV chip body 4 continues to increase. The heat dissipation power is increased by the microchannel heat sink 14 to reduce the temperature of the MOV chip body 4. When the working power of the MOV chip body 4 continues to increase, the heat generated will cause the air to expand due to heat, resulting in The extrusion plate 13 is subjected to air pressure, so that the micro-convex column 18 enters the microchannel 15, increasing the pressure drop inside the microchannel. The microchannel radiator 14 increases the pumping power of the microchannel radiator 14 according to the pressure drop change inside the microchannel, thereby ensuring a better heat dissipation effect of the device. At the same time, as the degree of air expansion due to heat, the micro-convex column 18 entering the microchannel 15 also changes, causing the pressure drop inside the microchannel to also change. According to the pressure drop change inside the microchannel and the surface temperature change of the MOV chip body 4, the microchannel radiator 14 can work with more precise power, while avoiding the waste of the output power of the microchannel radiator 14 and avoiding the damage of the device due to the untimely heat dissipation of the device caused by insufficient output power of the microchannel radiator 14.

Claims

1. A lead frame surface mounted metal oxide varistor device, characterized in that: The invention comprises an upper shell (1), a lower shell (2) and an MOV chip body (4); the upper shell (1) and the lower shell (2) are connected to form a sealed cavity inside; the MOV chip body (4) is arranged inside the cavity; electrode terminals are arranged on both sides of the MOV chip body (4); two groups of patch mounting grooves are respectively opened at the lower end of the lower shell (2) corresponding to the two groups of electrode terminals; patches (6) are installed inside the patch mounting grooves; the two groups of patches (6) are respectively connected to the corresponding electrode terminals through supporting legs (3) and electrode leads (5); a first heat conducting layer (7), a microchannel heat sink (14) and a second heat conducting layer (9) are arranged on the outer side of the MOV chip body (4); the side of the second heat conducting layer (9) away from the microchannel heat sink (14) is connected to the inner wall of the cavity formed by the connection between the upper shell (1) and the lower shell (2).

2. A lead frame surface mounted metal oxide varistor device according to claim 1, characterized in that: A gas expansion chamber (12) is provided inside a cavity formed by connecting the upper shell (1) and the lower shell (2), a buffer layer installation chamber is provided inside the expansion chamber (12), a buffer layer (11) is provided inside the buffer layer installation chamber, an extrusion plate (13) is provided at the upper end of the buffer layer (11), and the extrusion plate (13) is slidably connected to the inner wall of the buffer layer installation chamber.

3. A lead frame surface mounted metal oxide varistor device according to claim 2, characterized in that: The buffer layer installation cavity is located at the upper end of the microchannel heat sink (14); a plurality of through holes (16) are provided on the side wall of the microchannel (15) of the microchannel heat sink (14) close to the buffer layer installation cavity; micro-convex columns (18) are installed at positions of the extrusion plate (13) corresponding to the through holes (16); one end of the micro-convex column (18) away from the extrusion plate (13) passes through the buffer layer (11) and is arranged at the upper end of the through holes (16).

4. A lead frame surface mounted metal oxide varistor device according to claim 3, characterized in that: A flexible sealing pad (17) is installed on one side of the through hole (16) close to the inside of the microchannel (15), and one end of the micro-convex column (18) away from the extrusion plate (13) is connected to the flexible sealing pad (17).

5. The lead frame surface mounted metal oxide varistor device according to claim 3, characterized in that: The inner wall of the buffer layer installation cavity is located below the extrusion plate (13) and is provided with a limit block (10) for preventing excessive displacement of the micro-convex column (18).

6. The lead frame surface mounted metal oxide varistor device according to claim 1, characterized in that: A temperature sensor (8) is installed on the outer wall of the MOV chip body (4).

7. The lead frame surface mounted metal oxide varistor device according to claim 1, characterized in that: A support foot fixing groove is provided on the side wall of the lower housing (2) at the position of the patch mounting groove, and the support foot (3) is arranged inside the support foot fixing groove.

8. The lead frame surface mounted metal oxide varistor device according to claim 2, characterized in that: The buffer layer (11) is made of a buffer rubber block, and the upper end of the buffer layer (11) is in contact with the extrusion plate (13).

9. The lead frame surface mounted metal oxide varistor device according to claim 3, characterized in that: The inner contour of the through hole (16) is matched with the outer contour of the micro-convex column (18).

10. The lead frame surface mounted metal oxide varistor device according to claim 3, characterized in that: The micro-convex column (18) is cylindrical in shape.

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