Lead frame surface mount metal oxide varistor devices

Abstract

The present invention discloses a lead frame surface mount metal oxide varistor device, comprising an upper housing, a lower housing, and an MOV chip body. The upper and lower housings are connected to form a sealed cavity. The MOV chip body is disposed within the cavity. Electrode terminals are provided on both sides of the MOV chip body. Two sets of patch mounting slots are provided at the lower end of the lower housing, corresponding to the two sets of electrode terminals. Patches are mounted within the patch mounting slots. The two sets of patches are connected to the corresponding electrode terminals in sequence via legs and electrode leads. A first heat conducting layer, a microchannel heat sink, and a second heat conducting layer are sequentially disposed on the outer side of the MOV chip body. 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 and lower housings. The present invention transfers heat generated by the MOV chip body to the microchannel heat sink via the first heat conducting layer. Microchannels provided within the microchannel heat sink rapidly remove the heat from the heat source, thereby preventing local overheating and chip damage.

Description

Technical Field

[0001] The present invention relates to the technical field of surface mount 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 commonly used in electronic circuits to provide transient voltage suppression. MOVs generate significant heat during operation. If this heat is not promptly removed from the heat source, it can lead to heat concentration and increased heat flux, potentially damaging the device. Summary of the Invention

[0003] The present invention aims to at least partially address one of the technical problems in the related art. To this end, one object of the present invention is to provide a lead frame surface mount metal oxide varistor device that can quickly remove heat from the heat source, thereby preventing local overheating and chip damage.

[0004] The present invention provides a lead frame surface-mounted metal oxide varistor device, comprising an upper shell, a lower shell, and an MOV chip body. The upper shell and the lower shell are connected to form a sealed cavity, the MOV chip body is arranged inside the cavity, and electrode terminals are respectively provided on both sides of the MOV chip body. 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, and patches are installed in the patch mounting grooves. The two groups of patches are respectively connected to the corresponding electrode terminals through supporting legs and electrode leads. A first heat conducting layer, a microchannel heat sink, and a second heat conducting layer are sequentially provided on the outer side of the MOV chip body. The side of the second heat conducting layer away from the microchannel heat sink is connected to the inner wall of the cavity formed inside 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 the microchannel side wall of the microchannel radiator close to the buffer layer mounting cavity is provided with multiple groups of through holes, and the extrusion plate is installed with micro-protrusions at the positions corresponding to the through holes, and the 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 a side of the through hole close to the interior of the micro-channel, and an end of the micro-protrusion away from the extrusion plate is connected to the flexible sealing gasket.

[0008] Preferably, an inner wall of the buffer layer installation cavity is provided below the extrusion plate with a limiting block for preventing excessive displacement of the micro-protrusions.

[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 adapted to 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 radiator through the first heat conducting layer, and the heat is quickly taken away from the heat source through the microchannels set inside the microchannel radiator to avoid local overheating and damage to the chip;

[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, releasing buffer space for gas expansion, alleviating the phenomenon of chip bulging caused by gas thermal expansion. 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 back by the temperature sensor, so that the heat dissipation effect of the device is better. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In the attached figure:

[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 schematic structural diagram of the main body of the MOV chip proposed in the present invention;

[0021] Figure 3A cross-sectional view of the 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 proposed in the present invention near the buffer layer installation cavity.

[0023] In the figure: 1-upper shell, 2-lower shell, 3-support leg, 4-MOV chip body, 5-electrode lead, 6-patch, 7-first thermal conductive layer, 8-temperature sensor, 9-second thermal conductive 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 gasket, 18-micro-convex column. DETAILED DESCRIPTION

[0024] Reference Figure 1 、 Figure 2 and Figure 3 A lead frame surface mount metal oxide varistor device includes 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 closed cavity. The MOV chip body 4 is arranged inside the cavity. Electrode terminals are respectively provided 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 the support legs 3 and the electrode leads 5 in sequence. The outside 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. 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.

[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, referring 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, and 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 heat inside the expansion chamber 12, forming pressure around it. The pressure acts on the upper surface of the extrusion plate 13, squeezing 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 current situation of bulging in the chip shell.

[0028] In this embodiment, referring to Figure 3 and Figure 4 The buffer layer mounting cavity is located at the upper end of the microchannel radiator 14. The side wall of the microchannel 15 on the side of the microchannel radiator 14 close to the buffer layer mounting cavity is provided with multiple groups of through holes 16. Micro-protrusions 18 are installed at the position of the extrusion plate 13 corresponding to the through holes 16. The end of the micro-protrusion 18 away from the extrusion plate 13 passes through the buffer layer 11 and is arranged at the upper end of the through hole 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 from the through-holes 16 into the micro-channel 15, so that the pressure drop inside the micro-channel becomes larger. Therefore, the area of ​​the micro-protrusions 18 entering the micro-channel 15 can be used to change the pressure drop inside the micro-channel to feedback the degree of heating of the gas and regulate the output of the micro-channel radiator 14.

[0030] In this embodiment, referring to Figure 4 A flexible sealing gasket 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 gasket 17 .

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

[0032] In this embodiment, referring 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, referring 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 adjusted based on the temperature change on the surface of the MOV chip body 4 .

[0036] In this embodiment, referring to Figure 1 and Figure 2 The side wall of the lower shell 2 is provided with a foot fixing groove at the position of the patch mounting groove, and the foot 3 is arranged inside the foot fixing groove.

[0037] Obviously, based on the above, the provision of the support leg fixing groove can further fix the support leg 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, referring to Figure 3 The buffer layer 11 is made of a buffer rubber block, and the upper end of the buffer layer 11 abuts against 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, the buffer layer 11 can change in deformation degree along with the change of gas pressure when the extrusion plate 13 is subjected to 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, referring to Figure 4 The inner contour of the through hole 16 is adapted to 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, the following examples are provided with reference to the accompanying drawings:

[0045] Reference Figure 1-4When the mounted metal oxide varistor device is working, the MOV chip body 4 generates heat, which is conducted 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 remove 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, causing the micro-convex pillars 18 to enter the interior of 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 change of the pressure drop 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 pillars 18 entering the microchannel 15 also change, causing the pressure drop inside the microchannel to also change. According to the change of the pressure drop inside the microchannel and the change of the surface temperature of the MOV chip body 4, the microchannel radiator 14 can operate with more precise power, while avoiding the waste of the output power of the microchannel radiator 14 and avoiding the damage of the device caused by insufficient output power of the microchannel radiator 14 resulting in untimely heat dissipation of the device.

Claims

1. A lead frame surface mount metal oxide varistor device, characterized in that: The MOV chip body (4) comprises an upper shell (1), a lower shell (2) and an MOV chip body (4), wherein the upper shell (1) and the lower shell (2) are connected to form a sealed cavity, the MOV chip body (4) is arranged inside the cavity, and electrode terminals are respectively arranged on both sides of the MOV chip body (4), and 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, and 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 support legs (3) and the electrode leads (5) in sequence, and a first heat-conducting layer (7), a microchannel heat sink (14) and a second heat-conducting layer (9) are sequentially arranged on the outside of the MOV chip body (4), and 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); A gas expansion chamber (12) is provided inside the cavity formed by the connection between 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; The buffer layer installation cavity is located at the upper end of the microchannel radiator (14); a plurality of through holes (16) are provided on the side wall of the microchannel (15) of the microchannel radiator (14) close to the buffer layer installation cavity; micro convex columns (18) are installed at positions corresponding to the through holes (16) on the extrusion plate (13); and 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 hole (16).

2. The lead frame surface mount metal oxide varistor device according to claim 1, characterized in that: A flexible sealing gasket (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 gasket (17).

3. The lead frame surface mount metal oxide varistor device according to claim 1, characterized in that: The inner wall of the buffer layer installation cavity is located below the extrusion plate (13) and is provided with a limiting block (10) for preventing excessive displacement of the micro-convex column (18).

4. The lead frame surface mount 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).

5. The lead frame surface mount 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 shell (2) at the position of the patch mounting groove, and the support foot (3) is arranged inside the support foot fixing groove.

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

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

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

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