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Ultra-sonic welding connection between substrates

IP.com Disclosure Number: IPCOM000245759D
Publication Date: 2016-Apr-05
Document File: 7 page(s) / 130K

Publishing Venue

The IP.com Prior Art Database

Related People

Samuel Hartmann: AUTHOR [+3]

Abstract

The disclosure provides an ultra sonic welding connection between the substrates of a power semiconductor module being enabled by a ridge, which is connecting the long sides of the frame. The copper ribbons are molded in the ridge. This design feature allows to reduce the complexity of the manufacturing process, because only two (instead of three) different process-steps need to be mastered.

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05.04.2016

CH-1509101

Ultra‐sonic welding connection between substrates 

Authors: S. Matthias, D. Trüssel, S. Hartmann

TECHNICAL FIELD

The present disclosure describes a new solution for ultra sonic welding connection between substrates of a power semiconductor module.

BACKGROUND OF THE DISCLOSURE

State of the art power-module assembly relies on thick wire-bonding process to create electrical connections between power-terminals and substrate or between substrates (see Fig 1). Materials of choice are either aluminium-wires or copper-wires, which allow a higher current-density per wire for identical resistive losses compared to aluminium-wires. For the module assembly the following processes for creating electrical connections in the module need to be mastered:

Table 1) Electrical connection and its realization in power modules.

Conventional Latest generation Proposal Power-Terminal

Subtrate Aluminum wirebonding Copper wirebonding USW of copper ribbons

USW of copper ribbons

Aluminum wirebonding Copper wirebonding

Substrate Substrate

Copper wirebonding

Aluminum wirebonding

Chip Substrate

Aluminum wirebonding

Copper wirebonding

Auxiliary pins Substrate

Aluminum wirebonding Copper wirebonding

Everytime the material or the process is changed, the manufacturing gets more complex. This means that for the fabrication of state-of-the-art generation three process steps are required.

Ultra-sonic welding (USW) is the process of choice when it comes to lowest resistive losses combined with high reliability. Some competitors use therefore already ultra-sonic welding process of power-terminals to the main substrate. The power-terminals are in this case molded in the frame of the housing. Hence they are reliably guided, aligned and adjusted to the direct bonded copper (DBC)-substrate by the frame of the module.


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05.04.2016

CH-1509101

Aluminium wires connecting the substrates

Copper wires connecting the substrates

Aluminium wires connecting the power- terminals and the substrate

Copper wires connecting the power-terminal with the substrate

                                Ultra sonic welded copper power-terminals Fig. 1) State of the art realization of the electrical connection between substrates and between power-terminal and substrate


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05.04.2016

CH-1509101

Ultra-sonic welding of copper ribbons offers high reliability and lowest resistive losses, however it cannot be implemented for the substrate to substrate connection. This is simply a result of the missing guidance, alignment of the ribbons.

SUMMARY

The disclosure provides an ultra sonic welding connection between the substrates of a power semiconductor module being enabled by a ridge, which is connecting the long sides of the frame. The copper ribbons are molded in the ridge. This design feature allows to reduce the complexity of the manufacturing process, because only two (instead of three) different process-steps need to be mastered .

The described design will improve the...