Power module and internal positioning method thereof

Abstract

The present invention provides a power module and an internal positioning method thereof, comprising a main body, the main body comprising a substrate assembly, a copper frame and a chip; the copper frame and the chip are respectively connected to the substrate assembly; the copper frame comprises a first copper belt; the substrate assembly or the chip is provided with a limiting assembly that enables the first copper belt to be positioned correspondingly on the chip. The present invention limits the movement of the copper frame or the copper belt by adding a limiting piece on the surface of the insulating substrate or the surface of the chip, thereby playing a positioning role, and can prevent the copper frame or the copper belt from being unable to be accurately positioned when the copper frame or the copper belt is used for chip surface connection, resulting in a positional deviation from the center of the chip, thereby causing a short circuit problem.

Description

Technical Field

[0001] The present invention relates to the technical field of power semiconductor module packaging, and in particular, to a power module and an internal positioning method thereof, and in particular, preferably to a power module and an internal positioning process thereof. Background Art

[0002] In power supply and power electronic converter applications, power semiconductor devices (IGBT, MOSFET, SiC and GaN, etc.) are widely used. In high power applications, module packaging is generally used. The widely used packaging forms are as follows: Figure 1 As shown in the figure, the power module is mainly composed of a metal base plate, a welding layer, a DBC (double-sided copper-clad ceramic substrate), an AMB (foil brazed copper-clad ceramic substrate), an insulating heat dissipation resin film or other insulating heat dissipation materials, a binding wire, a shell and silicone. After the power semiconductor chip is fixed to the insulating heat dissipation material by welding, it is electrically connected through an aluminum binding wire. Then, the AMB or other insulating heat dissipation material is welded to the metal base plate through processes such as reflow soldering or sintering. The heat generated by the power semiconductor chip is transmitted to the metal base plate through the AMB or other insulating heat dissipation material and the welding layer, and the metal base plate is then cooled by air or water cooling. IGBT is called Insulated Gate Bipolar Transistor in English, and its Chinese translation is Insulated Gate Bipolar Transistor; MOSFET is called Metal-Oxide-Semiconductor Field-Effect Transistor in English, and its Chinese translation is Metal-Oxide Semiconductor Field-Effect Transistor; SiC stands for silicon carbide; GaN stands for gallium nitride.

[0003] like Figure 1 As shown, the metal base plate is mainly used for heat dissipation when the module is working; the welding layer is solder paste or tin sheet welding, which is used for the connection between the base plate and the insulating substrate and between the insulating substrate and the chip; the insulating substrate realizes the circuit structure required by the design; the binding wire realizes the circuit connection of each component. The external structure of the module is mainly the outer shell and the terminal. The outer shell is connected to the base plate through the dispensing process. The terminal is generally injection molded into the shell and connected to the internal circuit through the binding wire or directly welded to the insulating substrate. The module needs to be filled with silicone, which is used to protect the internal circuit from corrosion and moisture, and at the same time isolate the internal components from high voltage.

[0004] With the increase in power density of power semiconductor chips, especially the emergence of broadband semiconductors such as SiC and GaN, the chip area is getting smaller and smaller under the same current output, and the number and area of ​​wire bonding are also getting smaller and smaller. The use of aluminum wire bonding will bring two problems. One is that the number of aluminum wire bonding that can be used is reduced, so the equivalent conductive cross-sectional area is also reduced, increasing the resistance of the circuit, increasing the loss in the power module, and the parasitic inductance of the circuit will also increase. The second is that the power cycle life will also decrease accordingly with the reduction of the contact area between the aluminum wire bonding and the chip, because the thermal expansion coefficient of the semiconductor chip is 2x10-6 / K to 4x10-6 / K, and that of aluminum is 23x10-6 / K. The mismatch of thermal expansion generated by the semiconductor chip during high and low temperature changes will cause mechanical fatigue of the contact surface between the two materials. If the contact area is smaller, the power cycle life will be shorter.

[0005] To solve this problem, a copper frame can be used for connection. The copper frame is usually made by stamping. Figure 2 and Figure 3 As shown in FIG, the copper frame is connected to the chip surface by welding or sintering. There are also methods of using copper tape connected to a thick copper plate by ultrasonic welding, laser, sintering or welding to replace aluminum bonding wires, such as Figure 4 and Figure 5 As shown in the figure, the copper tape surface can be connected to the surface of the chip by welding or sintering. The contact surface between the copper material and the chip brings relatively large mechanical stress to the chip when the temperature changes. The copper tape is selected to be thinner with a thickness of 100um-400um. The strong conductivity of copper can reduce the on-resistance and parasitic inductance. The thickness of the copper plate is between 0.8mm and 2mm. The copper tape copper frame has a large contact area with the chip, and the thermal expansion coefficient is 16.9x10-6 / K, which is much lower than that of aluminum, which can enhance the power cycle life.

[0006] For chips with small soldering surfaces (less than 5mm*5mm), the copper tape and copper frame must be positioned on the chip with extremely high positioning accuracy, especially when multiple chips (2-10) are connected in parallel. If the physical fixture is deformed due to assembly or wear, the positioning may be inaccurate and offset from the center of the chip. Figure 6 As shown in the figure, the copper tape or copper frame and the contact surface of the chip may reach the voltage-resistant insulation area at the edge of the power chip. Because the positive and negative electrodes of the chip are short-circuited, the solder may also flow to the surface of the insulating substrate such as the AMB, further causing the chip to be short-circuited. There are even long-term reliability issues caused by marginal electrical passage. It is impossible to detect it at the first time. It is a serious problem that it fails after flowing to the customer's application end.

[0007] The Chinese invention patent document with publication number CN102347289A discloses a power semiconductor module having at least one positioning device for a substrate, the power semiconductor module having: a frame-shaped or cup-shaped housing; and at least one recess for at least one substrate. The substrate is configured as a switch substrate only or as a base plate with at least one switch substrate arranged on the base plate. In addition, the housing has at least one positioning device with an elastic section and a contact element in the recess, wherein at least one contact element is force-fitted against the assigned side of the substrate, and thereby applies pressure to the side.

[0008] With respect to the above-mentioned related technologies, the inventor believes that when a copper frame or copper tape is used for chip surface connection, the copper frame or copper tape cannot be accurately positioned, resulting in a positional deviation from the center of the chip, thereby causing a short circuit. Summary of the invention

[0009] In view of the defects in the prior art, an object of the present invention is to provide a power module and an internal positioning method thereof.

[0010] A power module provided according to the present invention comprises a main body, wherein the main body comprises a substrate assembly, a copper frame and a chip;

[0011] The copper frame and the chip are respectively connected to the substrate assembly;

[0012] The copper frame includes a first copper strip;

[0013] The substrate assembly or the chip is provided with a limiting assembly which enables the first copper strip to be positioned correspondingly on the chip.

[0014] Preferably, the substrate assembly comprises a first conductive layer, a second conductive layer and an insulating substrate;

[0015] The first conductive layer and the second conductive layer are disposed on an insulating substrate;

[0016] The chip is arranged on the first conductive layer;

[0017] The copper frame also includes a second copper strip and a copper plate;

[0018] The first copper strip and the second copper strip are connected by a copper plate;

[0019] The first copper tape and the chip are connected via a first connection layer;

[0020] The second copper tape and the second conductive layer are connected via a second connecting layer.

[0021] Preferably, the limiting assembly includes a limiting member for limiting the copper plate;

[0022] The first conductive layer and / or the second conductive layer is formed with a third conductive layer, and the formed third conductive layer is not connected to the first conductive layer and the second conductive layer respectively;

[0023] The limiting member is mounted on the third conductive layer, and the limiting member contacts the copper plate.

[0024] Preferably, the limiting components are arranged in multiple groups.

[0025] Preferably, the limiting assembly includes an auxiliary insulating substrate, a fourth conductive layer and a limiting member for limiting the copper plate;

[0026] The auxiliary insulating substrate is arranged on the first conductive layer and / or the second conductive layer;

[0027] The fourth conductive layer is disposed on the auxiliary insulating substrate;

[0028] The limiting member is mounted on the fourth conductive layer, and the limiting member contacts the copper plate.

[0029] Preferably, the limiting assembly includes a limiting member for limiting the first copper strip and / or the second copper strip;

[0030] The limiting member is arranged on the chip, and the limiting member contacts the first copper strip and / or the second copper strip.

[0031] A method for internal positioning of a power module provided by the present invention comprises the following steps:

[0032] Step S1: placing a chip on a substrate assembly;

[0033] Step S2: Setting a limit assembly on the substrate assembly or the chip;

[0034] Step S3: The limiting component limits the copper frame so that the first copper tape is positioned correspondingly on the chip.

[0035] Preferably, in step S2, the first conductive layer and / or the second conductive layer are formed into a third conductive layer, and a stopper is provided on the third conductive layer;

[0036] In step S3, the limiting member contacts the copper plate to limit the copper plate so that the first copper strip is positioned correspondingly on the chip.

[0037] Preferably, in step S2, an auxiliary insulating substrate is provided on the first conductive layer and / or the second conductive layer, a fourth conductive layer is provided on the auxiliary insulating substrate, and a stopper is provided on the fourth conductive layer;

[0038] In step S3, the limiting member contacts the copper plate to limit the copper plate so that the first copper strip is positioned correspondingly on the chip.

[0039] Preferably, in step S2, a stopper is provided on the chip;

[0040] In step S3, the limiting member contacts the first copper tape and / or the second copper tape to limit the first copper tape and / or the second copper tape, so that the first copper tape is positioned correspondingly on the chip.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] 1. The present invention limits the movement of the copper frame or copper belt by adding a stopper on the surface of the insulating substrate or the surface of the chip, thereby playing a positioning role, and can prevent the copper frame or copper belt from being misaligned with the center of the chip when the copper frame or copper belt is used for chip surface connection, thereby preventing the short circuit problem caused by the copper frame or copper belt being unable to be accurately positioned when connected to the chip surface;

[0043] 2. The present invention connects the auxiliary insulating substrate to the metal conductive layer on the insulating substrate by gluing, welding, sintering, etc., and then connects the aluminum binding wire, copper binding wire, aluminum tape or copper tape on the auxiliary insulating substrate for limiting. This allows the metal conductive layer to have normal conductivity and reduces parasitic resistance and inductance;

[0044] 3. The present invention directly connects auxiliary aluminum bonding wires or copper bonding wires on the chip, and limits the movement of the copper frame or copper tape by the aluminum bonding wires and the copper bonding wires to achieve the positioning effect. It does not need to occupy the area of ​​the metal conductive layer on the insulating substrate, which is simpler and does not require an auxiliary insulating substrate, and has a lower cost.

[0045] 4. The present invention avoids using other physical jigs to position the copper frame, thereby reducing assembly complexity. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0047] Figure 1 This is a traditional power module packaging diagram;

[0048] Figure 2 A power module package diagram showing the use of a copper frame to replace the wire bonds;

[0049] Figure 3 for Figure 2 Schematic diagram of the copper frame in;

[0050] Figure 4 A power module package diagram that uses copper tape and copper plate integrated components to replace the wire bonds;

[0051] Figure 5 It is a schematic diagram of an integrated component of a copper strip and a copper plate;

[0052] Figure 6 A schematic diagram of the positioning offset between the copper tape and the chip;

[0053] Figure 7 It is a front view of the first embodiment of the present invention;

[0054] Figure 8 It is an overall diagram of the first embodiment of the present invention;

[0055] Fig. 9 is a schematic diagram of a second embodiment of the present invention;

[0056] Fig.10 This is a schematic diagram of Embodiment 3 of the present invention. DETAILED DESCRIPTION

[0057] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0058] Embodiment 1 of the present invention discloses a power module, such as Figure 7 and Figure 8 As shown, it includes a main body, which includes a substrate assembly, a copper frame and a chip; the copper frame and the chip are respectively connected to the substrate assembly; the copper frame includes a first copper belt; and a limiting assembly is provided on the substrate assembly to position the first copper belt correspondingly on the chip.

[0059] The substrate assembly includes a first conductive layer, a second conductive layer and an insulating substrate. The first conductive layer and the second conductive layer are arranged on the insulating substrate; the chip is arranged on the first conductive layer; the copper frame also includes a second copper belt and a copper plate; the first copper belt and the second copper belt are connected through the copper plate; the first copper belt and the chip are connected through the first connecting layer; the second copper belt and the second conductive layer are connected through the second connecting layer.

[0060] The limiting assembly includes a limiting piece for limiting the copper plate. The first conductive layer and / or the second conductive layer forms a third conductive layer, and the formed third conductive layer is not connected to the first conductive layer and the second conductive layer. The limiting piece is mounted on the third conductive layer, and the limiting piece contacts the copper plate. The limiting assembly is arranged in multiple groups. The limiting piece is a copper strip, an aluminum strip, a copper binding wire or an aluminum binding wire.

[0061] Embodiment 1 of the present invention also discloses a method for positioning the interior of a power module. Figure 7 and Figure 8As shown, the following steps are included: Step S1: placing the chip on the substrate assembly; Step S2: placing a limit assembly on the substrate assembly. The first conductive layer and / or the second conductive layer form a third conductive layer, and a limit piece is placed on the third conductive layer.

[0062] Step S3: The limiting component limits the copper frame so that the first copper strip is positioned on the chip. The limiting component contacts the copper plate and limits the copper plate so that the first copper strip is positioned on the chip.

[0063] Aluminum binding wires, copper binding wires, aluminum strips or copper strips are used on an insulating substrate to form a limiting structure for a copper frame or an integrated structure of copper strips and copper plates. Because the aluminum binding wires, copper binding wires, aluminum strips or copper strips are metals, if they are connected to the metal conductive layer on the insulating substrate (if they are connected to the metal conductive layer on the insulating substrate), a short circuit problem between the aluminum binding wires, copper binding wires, aluminum strips or copper strips and the metal conductive layer will occur. The contact portion of the aluminum binding wires, copper binding wires, aluminum strips or copper strips with the insulating substrate layer should be isolated from other circuit parts. The metal conductive layer is covered on the insulating substrate. The first conductive layer and the second conductive layer are metal conductive layers. The first copper strip, the second copper strip and the copper plate are welded or integrally formed (copper frame). The first connection layer and the second connection layer are solder paste or solder layers.

[0064] The first step is to mount the "chip" on the "insulating substrate". The second step is to bind the "limiting piece (aluminum binding wire, or copper binding wire, aluminum tape or copper tape)" on the insulating substrate according to the size of the "copper frame or copper tape copper plate integrated structure". The third step is to clamp the "copper frame or copper tape copper plate integrated structure" in the "limiting piece". The "limiting piece" is bound to the "insulating substrate" through a binding process (ultrasound).

[0065] Embodiment 2 of the present invention discloses a power module, such as Fig. 9 As shown, the difference from Example 1 is that the limiting component includes an auxiliary insulating substrate, a fourth conductive layer and a limiting member for limiting the copper plate; the auxiliary insulating substrate is arranged on the first conductive layer and / or the second conductive layer; the fourth conductive layer is arranged on the auxiliary insulating substrate; the limiting member is mounted on the fourth conductive layer, and the limiting member contacts the copper plate.

[0066] The second embodiment of the present invention also discloses a method for positioning the interior of a power module. Fig. 9 As shown, the difference from the first embodiment is that in step S2, an auxiliary insulating substrate is arranged on the first conductive layer and / or the second conductive layer, a fourth conductive layer is arranged on the auxiliary insulating substrate, and a stopper is arranged on the fourth conductive layer;

[0067] In step S3, the limiting member contacts the copper plate to limit the copper plate so that the first copper tape is positioned correspondingly on the chip.

[0068] In the first embodiment, a certain area in the metal conductive layer on the insulating substrate is required for the connection of aluminum bonding wires, copper bonding wires, aluminum strips or copper strips. This will affect the normal conductivity of the metal conductive layer and increase parasitic resistance and inductance. Fig. 9 As shown, after the auxiliary insulating substrate is connected to the metal conductive layer on the insulating substrate by gluing, welding, sintering, etc., the auxiliary insulating substrate is then connected to an aluminum binding wire, or a copper binding wire, an aluminum tape or a copper tape for limiting.

[0069] Embodiment 3 of the present invention discloses a power module, such as Fig.10 As shown, the difference from the first embodiment is that a limiting assembly is provided on the chip to position the first copper strip correspondingly on the chip. The limiting assembly includes a limiting member for limiting the first copper strip and / or the second copper strip; the limiting member is provided on the chip, and the limiting member contacts the first copper strip and / or the second copper strip.

[0070] Embodiment 3 of the present invention discloses a method for positioning the interior of a power module. Fig.10 As shown, the difference from the first embodiment is that, step S2: a limiting component is provided on the substrate component or the chip. A limiting piece is provided on the chip.

[0071] In step S3, the limiting member contacts the first copper tape and / or the second copper tape to limit the first copper tape and / or the second copper tape, so that the first copper tape is positioned correspondingly on the chip.

[0072] Auxiliary aluminum binding wires or copper binding wires are directly connected to the chip, and the movement of the copper frame or copper tape is limited by the aluminum binding wires and the copper binding wires to achieve the positioning effect. Compared with the first embodiment, it does not need to occupy the area of ​​the metal conductive layer on the insulating substrate, which is simpler. Compared with the second embodiment, an auxiliary insulating substrate is not required, and the cost is lower. The "limiting piece" is bound to the surface of the "chip" through a binding process.

[0073] The present invention is applicable to power semiconductor module packaging, motor drive, and power electronic converter. The present invention relates to packaging technology for power semiconductor modules. The present invention solves the problem of positioning a copper frame or an integrated copper strip and copper plate component when connected to a chip surface. The present invention solves (prevents) the problem of short circuit caused by the inability to accurately position the copper frame or copper strip when connecting the chip surface using the copper frame or copper strip, resulting in a positional deviation from the center of the chip.

[0074] The present invention adds aluminum binding wires, copper binding wires, aluminum strips, and copper strips to the surface of the insulating substrate or the chip surface to limit the movement of the copper frame or copper strips, thereby playing a positioning role. The copper frame or copper strip of the present invention can accurately position the surface of a single or multiple parallel chips, prevent the protruding structure on the copper strip, and effectively prevent the fused solder from being squeezed by the heavier copper strips and copper plates during welding.

[0075] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element 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 application.

[0076] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A power module, characterized in that: The invention comprises a main body, wherein the main body comprises a substrate assembly, a copper frame and a chip; The copper frame and the chip are respectively connected to the substrate assembly; The copper frame includes a first copper strip; The substrate assembly or the chip is provided with a limiting assembly that enables the first copper strip to be positioned correspondingly on the chip; The substrate assembly includes a first conductive layer, a second conductive layer and an insulating substrate; The first conductive layer and the second conductive layer are disposed on an insulating substrate; The chip is arranged on the first conductive layer; The copper frame also includes a second copper strip and a copper plate; The first copper strip and the second copper strip are connected by a copper plate; The first copper tape and the chip are connected via a first connection layer; The second copper tape and the second conductive layer are connected via a second connecting layer; The limiting assembly includes a limiting member for limiting the position of the copper plate; The first conductive layer and / or the second conductive layer is formed with a third conductive layer, and the formed third conductive layer is not connected to the first conductive layer and the second conductive layer respectively; The limiting member is mounted on the third conductive layer, and the limiting member contacts the copper plate; Or the limiting assembly includes an auxiliary insulating substrate, a fourth conductive layer and a limiting member for limiting the copper plate; The auxiliary insulating substrate is arranged on the first conductive layer and / or the second conductive layer; The fourth conductive layer is disposed on the auxiliary insulating substrate; The limiting member is mounted on the fourth conductive layer, and the limiting member contacts the copper plate; Or the limiting assembly includes a limiting member for limiting the first copper strip and / or the second copper strip; The limiting member is arranged on the chip, and the limiting member contacts the first copper strip and / or the second copper strip.

2. The power module according to claim 1, characterized in that: The limiting components are arranged in multiple groups.

3. A method for internal positioning of a power module, characterized in that: Applying the power module described in any one of claims 1-2 comprises the following steps: Step S1: placing a chip on a substrate assembly; Step S2: Setting a limit assembly on the substrate assembly or the chip; Step S3: The limiting component limits the copper frame so that the first copper strip is positioned correspondingly on the chip; In the step S2, the first conductive layer and / or the second conductive layer are formed into a third conductive layer, and a stopper is provided on the third conductive layer; In step S3, the limiting member contacts the copper plate to limit the copper plate so that the first copper strip is positioned correspondingly on the chip; Alternatively, in step S2, an auxiliary insulating substrate is provided on the first conductive layer and / or the second conductive layer, a fourth conductive layer is provided on the auxiliary insulating substrate, and a stopper is provided on the fourth conductive layer; In step S3, the limiting member contacts the copper plate to limit the copper plate so that the first copper strip is positioned correspondingly on the chip; Alternatively, in step S2, a stopper is provided on the chip; In step S3, the limiting member contacts the first copper tape and / or the second copper tape to limit the first copper tape and / or the second copper tape, so that the first copper tape is positioned correspondingly on the chip.

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