Connection process of internal binding wire of power module

Abstract

The invention is suitable for the technical field of power semiconductor module packaging, and provides a power module internal binding wire connection process, which comprises the following steps ofconnecting a copper binding wire to a metal plate in a bonding mode, and then connecting the copper binding wire to a chip and an electrode of a power module in a welding or sintering mode. Compared with an existing mode that a chip and DBC are connected directly through an aluminum binding wire, the method of the invention has the advantages that the thermal expansion coefficient of a metal plateis close to that of a semiconductor chip, so that the power cycle life is greatly prolonged; compared with an existing mode that a chip and DBC are connected directly through a copper binding wire, the method of the invention has the advantages that the surface of a chip does not need to be connected with a thick copper foil layer, so that the process is simple, and the cost is low; and comparedwith the two modes, the method of the invention has the advantages that the contact area with the surface of the chip is increased, most of the circuit passes through a thick metal plate, the on-resistance is greatly reduced, and the parasitic inductance is also reduced.

Description

technical field [0001] The invention belongs to the technical field of packaging of power semiconductor modules, and in particular relates to a connection process of bonding wires inside a power module. Background technique [0002] In the application of power supply and power electronic converter, power semiconductor (IGBT, MOSFET, SiC, GaN, etc.) devices are widely used, and the package form of module is generally used in the case of high power. The packaging form that is widely used now: the power module is mainly composed of a metal base plate, a solder layer, DBC (double-sided copper-clad ceramic substrate), AMB (foil brazed copper-clad ceramic substrate), insulating and heat-dissipating resin film or other insulating and heat-dissipating materials, Bonding wire, casing and silica gel; after the power semiconductor chip is fixed to the insulating and heat-dissipating material by welding, it is electrically connected through an aluminum bonding wire, and then the DBC o...

AI Technical Summary

Problems solved by technology

The use of aluminum bonding wires in this way will bring two problems: one is that the number of aluminum bonding wires that can be used is reduced, so that the equivalent conductive cross-sectional area is also reduced, increasing the resistance of the circuit and increasing the loss in the power module. The parasitic inductance of the circuit will also increase; the second is that the power cycle life will also decrease with the reduction of the contact area between the aluminum bonding wire and the chip, because the thermal expansion coefficient of the semiconductor chip is 2 X10 -6 / K to 4X10 -6 / K, aluminum is 23X10 -6 / K, the thermal expansion mismatch of the semiconductor chip during high and low temperature changes will cause mechanical fatigue on the contact surface between the two materials. If the contact area is smaller, the power cycle life will be shorter

[0004] There are also methods of using copper bonding wires instead of aluminum bonding wires, as shown in the attached figure 2 As shown, but the method of copper bonding wire also has a series of disadvantages. The hardness of copper bonding wire is much greater than that of aluminum bonding wire, and more force is needed to realize the bonding of copper bonding wire and semiconductor chip.

However, semiconductor chips cannot withstand large bonding forces, which often cause chip cracks.

At present, the method to solve this problem is to connect a layer of copper foil layer of tens of microns to 200 microns on the chip to absorb the force when the copper bonding wire is bonded to the surface of the chip, but this method (copper plating or sintered copper foil layer to chip surface) complex and costly

In addition, no matter the aluminum bonding wire or the copper bonding wire, because the general diameter is below 500um, the conductivity has its limit.

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