A semiconductor power module

Abstract

The application provides a semiconductor power module, and relates to the technical field of power semiconductors, which comprises: a silicon carbide chip, the silicon carbide chip is welded on an emitter of a metallized ceramic substrate, a silver paste layer is sintered on the emitter of the silicon carbide chip, the silver paste layer is connected with the emitter of the metallized ceramic substrate through a bonding wire, and a gate of the silicon carbide chip is connected with the emitter of the metallized ceramic substrate through the bonding wire; and a power terminal, the bottom of the power terminal is welded on the emitter of the metallized ceramic substrate. The beneficial effect is that the sintering of the silver paste layer on the silicon carbide chip and the bonding of the silver alloy bonding wire can solve the problems of insufficient low conduction resistance, high power loss and short service life caused by the direct combination of the silver wire and the chip; the silver alloy bonding wire and the silver paste layer are of the same material, and the combination between them is more reliable, so that the combination between the silver alloy bonding wire and the silicon carbide chip is more firm.

Description

Technical Field

[0001] This invention relates to the field of power semiconductor technology, and more particularly to a semiconductor power module. Background Technology

[0002] With the booming development of the microelectronics industry, the requirements for packaging technology are becoming increasingly stringent. Packaging technology is developing towards high density, miniaturization, and adaptability to high heat generation, which in turn places higher demands on bonding wires. Gold bonding wires are widely used in mid-to-high-end products in the packaging industry due to their good corrosion resistance and high reliability. However, gold wires are expensive. To reduce packaging costs, various alternatives to gold wires have been introduced to the market. Silver wires have attracted industry attention due to their excellent resistivity and relatively low price. However, silver wires are directly bonded to chips, resulting in less than ideal mechanical properties. Furthermore, the on-resistance of semiconductor power modules is not low enough, leading to higher power loss and shorter lifespan. Summary of the Invention

[0003] To address the problems existing in the prior art, the present invention provides a semiconductor power module, comprising:

[0004] A silicon carbide chip, wherein the silicon carbide chip is soldered onto a metallized ceramic substrate, a silver paste layer is sintered on the emitter of the silicon carbide chip, and the gate of the silicon carbide chip is connected to the metallized ceramic substrate by bonding wires;

[0005] The silver paste layer and the metallized ceramic substrate are bonded together by silver alloy bonding wires, and the silver alloy bonding wires are bonded to the silver paste layer and the metallized ceramic substrate by ultrasonic bonding process.

[0006] A power terminal, the bottom of which is soldered to the metallized ceramic substrate.

[0007] Preferably, the metallized ceramic substrate comprises, from top to bottom, a first metal layer, an intermediate ceramic layer, and a second metal layer.

[0008] Preferably, both the first metal layer and the second metal layer are made of copper.

[0009] Preferably, the bonding line between the gate of the silicon carbide chip and the metallized ceramic substrate is a soft aluminum wire.

[0010] Preferably, the device further includes a housing, in which the metallized ceramic substrate is encapsulated. The housing has a plurality of openings corresponding to each of the power terminals, and the top of each power terminal extends out from the corresponding opening.

[0011] Preferably, the soft aluminum wire is prepared by a continuous casting and rolling process.

[0012] Preferably, the silver alloy bonding wire is prepared by continuous melting, casting, wire drawing and annealing process.

[0013] Preferably, the first metal layer, the intermediate ceramic layer, and the second metal layer are prepared into the metallized ceramic substrate using a direct copper plating process or an active metal brazing process.

[0014] The above technical solution has the following advantages or beneficial effects:

[0015] 1) By sintering a silver paste layer on a silicon carbide chip and then bonding silver alloy bonding wires, the problems of insufficient on-resistance, high power loss, and short service life caused by direct bonding of silver wires to the chip in the existing technology can be solved.

[0016] 2) The silver alloy bonding wires and the silver paste layer are made of the same material, which makes their bonding more reliable and correspondingly makes the bonding force between the silver alloy bonding wires and the silicon carbide chip stronger. Attached Figure Description

[0017] Figure 1 A schematic diagram of the structure of a semiconductor power module is shown in a preferred embodiment of the present invention.

[0018] Figure 2 This is a cross-sectional schematic diagram of a semiconductor power module, which is a preferred embodiment of the present invention. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The present invention is not limited to this embodiment; other embodiments that conform to the spirit of the present invention may also fall within the scope of the present invention.

[0020] In a preferred embodiment of the present invention, based on the above-mentioned problems existing in the prior art, a semiconductor power module is provided, such as... Figure 1 and Figure 2 As shown, it includes:

[0021] A silicon carbide chip 1 is soldered onto the emitter of a metallized ceramic substrate 2. A silver paste layer 3 is sintered onto the emitter of the silicon carbide chip 1. The silver paste layer is connected to the emitter of the metallized ceramic substrate 2 via bonding wires. The gate of the silicon carbide chip 1 is connected to the emitter of the metallized ceramic substrate 2 via bonding wires.

[0022] Power terminal 4, the bottom of which is soldered to the emitter of metallized ceramic substrate 2.

[0023] The bonding wire between the silver paste layer 3 and the emitter of the metallized ceramic substrate 2 is a silver alloy bonding wire, and the silver alloy bonding wire is bonded to the silver paste layer and the metallized ceramic substrate by an ultrasonic bonding process.

[0024] Specifically, in existing technologies, bonding wires are widely used in mid-to-high-end products in the packaging industry due to their good corrosion resistance and high reliability. Among them, gold wire bonding has the best effect. However, gold wires are expensive. In order to reduce packaging costs, various alternatives to gold wires have been introduced on the market. Among them, silver wires have attracted industry attention due to their excellent resistivity and relatively low price, and are often used as the preferred alternative to gold wires. However, silver wires are directly bonded to the chip, and their mechanical properties are not very good. In addition, the on-resistance of semiconductor power modules is not low enough, resulting in high power loss and short service life. Therefore, in this embodiment, a silver paste layer is formed on the emitter of the silicon carbide chip through a silver paste sintering process. Then, the silver paste layer is connected to the metallized ceramic substrate through bonding wires. Compared with the traditional method of bonding silver wires to the chip in semiconductor power modules, it can have better mechanical properties, making the bonding between the silicon carbide chip and the metallized ceramic substrate more reliable.

[0025] Furthermore, using silver alloy bonding wires as the bonding material for bonding with the silver paste layer via ultrasonic bonding can achieve lower on-resistance in the semiconductor power module, reduce power loss, and extend the service life of the semiconductor power module. Since the silver alloy bonding wires and the silver paste layer are made of the same material, their bonding is more reliable.

[0026] In a preferred embodiment of the present invention, the metallized ceramic substrate 2 includes, from top to bottom, a first metal layer, an intermediate ceramic layer, and a second metal layer.

[0027] In a preferred embodiment of the present invention, both the first metal layer and the second metal layer are copper layers.

[0028] In a preferred embodiment of the present invention, a metallized ceramic substrate is prepared by using a direct copper plating process or an active metal brazing process to form a first metal layer, an intermediate ceramic layer, and a second metal layer.

[0029] Specifically, in this embodiment, the metal-ceramic substrate adopts a three-layer design (two copper layers with a ceramic layer sandwiched in between) and is prepared by a ceramic metallization process. The ceramic metallization process can be a direct copper bonding process (DBC, or direct copper cladding process), an active metal brazing (AMB) process, or other suitable processes.

[0030] DBC and AMB processes are two methods for fabricating ceramic copper substrates, each with its own advantages and disadvantages, mainly as follows:

[0031] The DBC process involves directly bonding copper to the surfaces of Al2O3 and AlN ceramics at high temperatures using a thermal fusion bonding method. This process creates a composite substrate with high thermal conductivity, insulation, and reliability, making it suitable for low-to-medium power electronic products such as refrigerators and air conditioners.

[0032] The AMB process utilizes active metal elements (such as Ti / Ag / Zr / Cu) in the solder to achieve bonding between ceramics and metals. The ceramic forms a reactive layer that can be wetted by the liquid solder, resulting in higher adhesion strength and thermal cycling performance. It is suitable for high-power electronic products, such as electric vehicles and electric locomotives.

[0033] The advantages of DBC technology are that it is a mature technology, low cost, and simple operation.

[0034] The advantage of the AMB process is that the interface strength between the copper layer and the ceramic layer is high, and it can withstand higher temperatures and voltages.

[0035] In a preferred embodiment of the present invention, the bonding line between the gate of the silicon carbide chip 1 and the emitter of the metallized ceramic substrate 2 is a soft aluminum wire.

[0036] In a preferred embodiment of the present invention, the soft aluminum wire is prepared by a continuous casting and rolling process.

[0037] In a preferred embodiment of the present invention, such as Figure 2 The diagram also includes a housing 5, in which a metallized ceramic substrate 2 is encapsulated. The housing 5 has multiple openings corresponding to each power terminal 4, and the top of each power terminal extends out from the corresponding opening.

[0038] Specifically, in this embodiment, the outer shell disposed on the outside of the metallized ceramic substrate is used to protect the metallized ceramic substrate and the power terminals and SiC chip disposed on the metallized ceramic substrate, reducing the impact of the external environment on the semiconductor power module, and the metallized ceramic substrate 2 and the outer shell 5 are sealed with sealant.

[0039] In a preferred embodiment of the present invention, the silver alloy bonding wire is prepared by a continuous melting, casting, wire drawing and annealing process.

[0040] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made using the content of this specification and illustrations should be included within the protection scope of the present invention.

Claims

1. A semiconductor power module, characterized in that, include: A silicon carbide chip, wherein the silicon carbide chip is soldered onto a metallized ceramic substrate, a silver paste layer is sintered on the emitter of the silicon carbide chip, and the gate of the silicon carbide chip is connected to the metallized ceramic substrate by bonding wires; The silver paste layer and the metallized ceramic substrate are bonded together by silver alloy bonding wires, and the silver alloy bonding wires are bonded to the silver paste layer and the metallized ceramic substrate by ultrasonic bonding process. A power terminal, the bottom of which is soldered to the metallized ceramic substrate.

2. The semiconductor power module according to claim 1, characterized in that, The metallized ceramic substrate comprises, from top to bottom, a first metal layer, an intermediate ceramic layer, and a second metal layer.

3. The semiconductor power module according to claim 2, characterized in that, Both the first metal layer and the second metal layer are made of copper.

4. The semiconductor power module according to claim 1, characterized in that, The bonding wire between the gate of the silicon carbide chip and the metallized ceramic substrate is a soft aluminum wire.

5. The semiconductor power module according to claim 1, characterized in that, It also includes a housing, in which the metallized ceramic substrate is encapsulated. The housing has multiple openings corresponding to each of the power terminals, and the top of each power terminal extends out from the corresponding opening.

6. The semiconductor power module according to claim 4, characterized in that, The soft aluminum wire is prepared using a continuous casting and rolling process.

7. The semiconductor power module according to claim 1, characterized in that, The silver alloy bonding wire is prepared by continuous melting, casting, wire drawing and annealing process.

8. The semiconductor power module according to claim 2, characterized in that, The first metal layer, the intermediate ceramic layer, and the second metal layer are prepared into the metallized ceramic substrate by using a direct copper plating process or an active metal brazing process.

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