Power device integrated with thermistor

Abstract

The utility model belongs to the field of semiconductor devices, and provides a power device integrated with a thermistor, which mainly comprises a copper-clad ceramic substrate, the copper-clad ceramic substrate comprises a substrate upper copper layer, a substrate lower copper layer and a substrate ceramic layer, the substrate ceramic layer is provided with an upper side surface and a lower side surface, the substrate upper copper layer is arranged on the upper side surface of the substrate ceramic layer, and the substrate lower copper layer is arranged on the lower side surface of the substrate ceramic layer. The lower copper layer is arranged on the lower side surface of the substrate ceramic layer; the chip is arranged on one side of the substrate upper copper layer; the thermistor is arranged on one side of the copper layer on the substrate, a bonding pad is arranged on the copper layer on the substrate, the thermistor is connected to the bonding pad of the copper layer on the substrate through silver sintering, and a groove is formed in the bonding pad. The groove is formed in the bonding pad, so that the stress generated in the heating expansion and cooling shrinkage process of the bonding pad can be reduced, the stress on the thermistor is further reduced, the thermistor is prevented from being fractured and damaged due to overlarge stress, the service life of the thermistor is effectively prolonged, the working temperature of a chip can be monitored at any time, and the reliability of the chip is improved. And the stability of the power device is effectively improved.

Description

Technical Field

[0001] The utility model belongs to the field of semiconductor components, in particular to a power device with an integrated thermistor. Background Art

[0002] With the widespread popularity of semiconductor power devices, the requirements for the reliability and stability of power devices are gradually increasing. Among them, ensuring that the chip is in a suitable operating temperature range is the key to ensuring the normal operation of power devices.

[0003] In the prior art, a thermistor is set on the power device to monitor the working temperature of the chip. Generally, the thermistor is fixed at a position close to the high heating area of ​​the chip. The working temperature of the chip is monitored by detecting the resistance value of the thermistor to prevent the power device from failing due to excessive temperature. However, the thermistor is prone to fracture failure during the operation of the power device. This is mainly because the stress generated by the pad fixing the thermistor during repeated thermal expansion or cooling contraction will be transmitted to the thermistor. When the stress exceeds the strength of the thermistor, the thermistor will experience fatigue fracture. At this time, the thermistor loses the function of monitoring the chip temperature, increasing the probability of failure of the power device due to excessive temperature, and reducing the reliability of the power device. Utility Model Content

[0004] The utility model provides a power device with an integrated thermistor, which solves the problem of fatigue fracture of the thermistor during operation of the power device, so that the thermistor can continuously monitor the operating temperature of the chip, effectively prolong the working life of the chip, and further improve the reliability and stability of the power device.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] A power device with an integrated thermistor, comprising:

[0007] A copper-clad ceramic substrate, comprising an upper copper layer, a lower copper layer and a ceramic layer, wherein the ceramic layer is provided with an upper side and a lower side, the upper copper layer is arranged on the upper side of the ceramic layer, the lower copper layer is arranged on the lower side of the ceramic layer, and the chip is arranged on one side of the upper copper layer;

[0008] The thermistor is arranged on one side of the copper layer on the substrate, a pad is arranged on the copper layer on the substrate, and the thermistor is connected to the pad of the copper layer on the substrate, wherein a groove is arranged on the pad.

[0009] In some embodiments, the pad includes a first pad and a second pad, a preset distance is set between the first pad and the second pad, and the groove includes a first groove and a second groove, the first groove is located on the first pad, and the second groove is located on the second pad.

[0010] In some embodiments, the first groove passes through the first pad and / or the second groove passes through the second pad.

[0011] In some embodiments, the first groove is disposed at a center position of the first pad, and the second groove is disposed at a center position of the second pad.

[0012] In some embodiments, the first pad and the second pad are symmetrically arranged with respect to the preset interval.

[0013] In some embodiments, an inner edge of the first groove is set at a first distance from an edge of the first pad, and an inner edge of the second groove is set at a second distance from an edge of the second pad.

[0014] In some embodiments, the thermistor is sintered and fixed to the surface of the pad using silver paste solder.

[0015] In some embodiments, a heat sink is further included and disposed on the copper layer under the substrate, the heat sink covers the copper layer under the substrate, wherein a plurality of heat dissipation columns are arranged at intervals on a side of the heat sink away from the copper layer under the substrate.

[0016] In some embodiments, a gel layer is provided on the copper layer on the substrate, and the gel layer covers one side of the copper layer on the substrate, wherein the thickness of the gel layer is greater than the height of components arranged on one side of the copper layer on the substrate.

[0017] In some embodiments, a plastic shell is disposed outside the gel layer, and the plastic shell is provided with a cavity, and the cavity is used for filling glue to form the gel layer.

[0018] Compared with the prior art, the beneficial effects brought by the utility model are:

[0019] In the present application, by setting a pad and setting a groove on the pad, the stress generated by the pad expanding due to heat or contracting due to cooling is alleviated to a certain extent, thereby indirectly reducing the stress transmitted to the thermistor, avoiding fatigue fracture of the thermistor due to excessive stress, effectively extending the service life of the thermistor, and improving the reliability and stability of the power device. Furthermore, by setting the pad to be a first pad and a second pad that are stacked and distributed, setting a first groove on the first pad, and setting a second groove on the second pad, the stress at the pad is reduced. At the same time, the first pad and the second pad are symmetrically arranged so that the thermistor is evenly stressed, thereby improving the stability of its connection on the copper-clad ceramic substrate.

[0020] Additional aspects and advantages of the present application will be partially given in the following description, which will become apparent from the following description, or will be understood through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a cross-sectional schematic diagram of a pad of a power device with an integrated thermistor of the utility model;

[0022] Figure 2 It is a top view schematic diagram of one side of the copper layer on the substrate of a power device with an integrated thermistor of the utility model;

[0023] Figure 3 It is a schematic diagram of the enlarged structure of the first pad and the second pad of a power device of an integrated thermistor of the utility model. DETAILED DESCRIPTION

[0024] The present application is further described in detail below in conjunction with specific drawings. In the description of this embodiment, unless otherwise specified, the terms "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the present application must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present application.

[0025] like Figure 1-3 As shown, a power device of an integrated thermistor provided by the utility model mainly includes a copper-clad ceramic substrate, wherein the copper-clad ceramic substrate includes an upper copper layer 3 on the substrate, a substrate ceramic layer 4 and a lower copper layer 5 on the substrate, the substrate ceramic layer 4 is provided with an upper side surface and a lower side surface, the upper copper layer 3 on the substrate is arranged on the upper side surface of the substrate ceramic layer 4, and the lower copper layer 5 on the substrate is arranged on the lower side surface of the basic ceramic layer 4. In this embodiment, the chip 1 is arranged on the upper copper layer 3 on the substrate;

[0026] Thermistor 2 is arranged on the side of the copper layer 3 on the substrate with chip 1, fixed at a position close to the high heating area of ​​chip 1, and used to monitor the temperature emitted by chip 1 in real time when working. A pad is arranged on the copper layer 3 on the substrate, and thermistor 2 is fixed to the pad of copper layer 3 on the substrate by silver sintering process. It should be noted that a groove is arranged on the pad to reduce the stress generated by the pad during thermal expansion and cooling contraction, thereby reducing the stress transmitted to thermistor 2, reducing the deformation of thermistor due to stress, and avoiding fatigue fracture of thermistor 2, thereby achieving the reliability of temperature monitoring of chip 1 by thermistor 2, avoiding the failure of power module due to over-temperature, and improving the stability of power device. In this embodiment, the cross-sectional shape of the groove can be circular, rectangular or trapezoidal, etc. It can be understood that in this embodiment, the cross-sectional shape of the groove is not limited by the utility model.

[0027] Furthermore, the pad is divided into a first pad 31 and a second pad 32, and a first notch is provided between the first pad 31 and the second pad 32 to form a preset spacing, so that the first pad 31 and the second pad 32 are two relatively independent parts, reducing the area of ​​the pad, and avoiding stress generated during thermal expansion or cooling of the pad. The groove includes a first groove 71 and a second groove 72, the first groove 71 is provided on the first pad 31, and the second groove 72 is provided on the second pad 32. By separately providing the pads and the grooves, stress concentration is further avoided.

[0028] Further, in this embodiment, as the best implementation, the first groove 71 penetrates the first pad 31, and the second groove 72 penetrates the second pad 32. Stress is released by providing the first groove 71 and the second groove 72 to avoid stress concentration. Optionally, as another variant implementation of this embodiment, only the first groove 71 penetrates the first pad 31, or only the second groove 72 penetrates the second pad 32.

[0029] In one embodiment, the first groove 71 is arranged at the center of the first pad 31, and the second groove 72 is arranged at the center of the second pad 32. A first distance is arranged between the inner edge of the first groove 71 and the edge of the first pad 31, and a second distance is arranged between the inner edge of the second groove 72 and the edge of the second pad 32. In this embodiment, the first distance is the same as the second distance. Optionally, the first distance and the second distance may also be different, for example, the first distance is greater than the second distance, or the first distance is less than the second distance. In this embodiment, by setting the first distance and the second distance, it is avoided that the contact area between the first pad 31 and the second pad 32 and the copper layer 3 on the substrate is too small, resulting in the instability of the structure of the thermistor 2 fixed on the copper-clad ceramic substrate through the first pad 31 and the second pad 32, resulting in the first pad 31 or the second pad 32 falling off, thereby making the connection of the thermistor 2 invalid, and being unable to monitor the over-high temperature of the chip 1 in real time, thereby reducing the reliability of the power device. Furthermore, the first soldering pad 31 and the second soldering pad 32 are symmetrically distributed about the first notch, so that the force conditions at the two connection points of the thermistor 2 are consistent, thereby preventing the thermistor 2 from falling off the first soldering pad 31 or the second soldering pad 32 due to uneven force when the thermistor 2 is connected to the first soldering pad 31 and the second soldering pad 32.

[0030] In one embodiment, since the pad formed by the traditional welding material under the thermistor 2 does not match the thermal expansion coefficient of the ceramic layer of the copper-clad ceramic substrate, the stress of the pad will increase during the thermal expansion process, and stress deformation is likely to occur, causing the thermistor 2 to fall off the pad on the copper-clad ceramic substrate. Therefore, silver paste solder is used, and the thermistor 2 is welded and fixed on the pad through a silver sintering process. By replacing the welding material with silver paste solder, the thickness of the silver paste solder after curing is only about one-fifth of that of the tin paste, and the thermal expansion coefficient of the silver paste solder is much smaller than that of the tin paste, thereby reducing the stress of the pad and avoiding fatigue fracture between the thermistor 2 and the pad, thereby improving the reliability of the thermistor connection, and reducing the risk of stress being transferred from the pad to the thermistor 2, avoiding the thermistor 2 from breaking due to excessive stress, thereby ensuring that the thermistor 2 can continuously monitor the chip temperature and improving the stability of the power device.

[0031] In one embodiment, a heat sink 6 is further included, and the heat sink 6 is arranged on one side of the copper layer 5 under the substrate. The heat sink 6 surrounds and covers the copper layer 5 under the substrate, wherein a plurality of heat dissipation columns arranged at intervals are arranged on the heat sink 6, and the heat dissipation columns are arranged on the side of the heat sink 6 away from the copper layer 5 under the substrate. In this embodiment, the heights of the plurality of heat dissipation columns are consistent to provide better support for the copper-clad ceramic substrate. When dissipating heat, the coolant or cold air flow passes through the gaps between the plurality of heat dissipation columns to take away the heat generated by the chip 1 in time, avoiding the situation of excessive temperature, and avoiding stress caused by thermal expansion of the copper-clad ceramic substrate.

[0032] In one embodiment, a gel layer is provided on the copper layer 3 on the substrate, and the gel layer covers one side of the copper layer 3 on the substrate, wherein the thickness of the gel layer is greater than the height of the components provided on one side of the copper layer 3 on the substrate. Figure 1 The outer edge in the vertical direction is set at a certain distance from the highest point of the thermistor 2, so as to seal and fix the components of the power device. Specifically, in this embodiment, the gel layer seals and fixes the chip 1, thermistor 2, pads and other components or connection points to protect the chip 1 and other components from external interference and damage. In addition, by sealing and fixing the thermistor 2, the stress generated by thermistor 2 and the pad due to heat is further resisted, thereby ensuring the stability of the connection point of the thermistor 2 and improving the bending resistance of the thermistor 2 itself. In this embodiment, the gel layer is sealed with silicone or epoxy resin.

[0033] Furthermore, a plastic shell is provided outside the gel layer, and the plastic shell is provided with a cavity, and the cavity is used for filling glue to form the gel layer. In this embodiment, the plastic shell is mainly formed of insulating material.

[0034] The above is only a preferred embodiment of the present invention. It should be noted that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications should also be considered as the protection scope of the present invention.

Claims

1. A power device with an integrated thermistor, characterized in that: include: A copper-clad ceramic substrate, comprising an upper copper layer, a lower copper layer and a ceramic layer, wherein the ceramic layer is provided with an upper side and a lower side, the upper copper layer is arranged on the upper side of the ceramic layer, the lower copper layer is arranged on the lower side of the ceramic layer, and the chip is arranged on one side of the upper copper layer; The thermistor is arranged on one side of the copper layer on the substrate, a pad is provided on the copper layer on the substrate, the thermistor is connected to the pad of the copper layer on the substrate through silver sintering, wherein a groove is provided on the pad.

2. A power device with integrated thermistor according to claim 1, characterized in that: The pad includes a first pad and a second pad, a preset distance is set between the first pad and the second pad, the groove includes a first groove and a second groove, the first groove is located on the first pad, and the second groove is located on the second pad.

3. A power device with integrated thermistor according to claim 2, characterized in that: The first groove passes through the first pad and / or the second groove passes through the second pad.

4. A power device with integrated thermistor according to claim 2, characterized in that: The first groove is arranged at the center of the first pad, and the second groove is arranged at the center of the second pad.

5. A power device with integrated thermistor according to claim 4, characterized in that: The first pad and the second pad are symmetrically arranged with respect to the preset interval.

6. A power device with integrated thermistor according to claim 4, characterized in that: A first distance is set between the inner edge of the first groove and the edge of the first pad, and a second distance is set between the inner edge of the second groove and the edge of the second pad.

7. A power device with integrated thermistor according to any one of claims 1 to 6, characterized in that: The thermistor is sintered and fixed to the surface of the pad by using silver paste solder.

8. A power device with integrated thermistor according to claim 7, characterized in that: It also includes a heat sink arranged on the copper layer under the substrate, and the heat sink covers the copper layer under the substrate, wherein a plurality of heat dissipation columns are arranged at intervals on a side of the heat sink away from the copper layer under the substrate.

9. A power device with integrated thermistor according to claim 8, characterized in that: A gel layer is arranged on the copper layer on the substrate, and the gel layer covers one side of the copper layer on the substrate, wherein the thickness of the gel layer is greater than the height of the components arranged on one side of the copper layer on the substrate.

10. A power device with integrated thermistor according to claim 9, characterized in that: A plastic shell is arranged outside the gel layer, and the plastic shell is provided with a cavity, and the cavity is used for filling glue to form the gel layer.

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