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Kurzfassung

The technology describes the rejuvenation of the wire cross section at high current bonds. Such rejuvenation can be achieved by either an oblique cutting angle of the wire end or through a comb-shaped thinning of the wire material to its end.

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Hintergrund

Wire bonding is a common method used in the construction of electrical connections, for example to connect the semiconductors of an integrated semiconductor, a light emitting diode or a sensor to the electrical connections of a chip housing.

A distinction can be made between the bonding of thin wires (mostly consisting of pure gold or alloyed or doped gold with wire thicknesses between approximately 25μm and less than 100μm) and heavy wires (with diameters of between approximately 100μm and approximately 500μm). The latter are used to cope with high current loads, for example, in so-called power semiconductors.

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Bilder & Videos

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Problemstellung

In the field of heavy-wire bonding the different thermal expansion coefficients of the materials involved – in particular of the semiconductor and the heavy wire – lead to fatigue cracks that forming the contacting plane of the heavy-wire bond connections. Therefore, technologies are needed to prevent this problem in heavy-wire bond connections.

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Lösung

This invention comprises a heavy-wire bond arrangement which comprises a substrate, a heavy wire and a high-voltage heavy-wire bond connection.

In this connection one end bond section of the heavy wire is bonded with the substrate. Here, the section extends towards the end of the heavy wire, so that a bond contact between and the substrate is formed in the area of the bond section.

The heavy wire has a tapering section which adjoins the end of the wire. In this tapering section, the wire cross-section tapers towards the end of the wire.

The provision of the tapering section, which in the bond section extends from the heavy wire so far that it reaches the end of the wire, reduces the effective shear stress in the area of the bond section, resulting in an improved reliability of the bond connection between heavy wire and substrate. Moreover, the likelihood of reduced fatigue cracks is reduced and the current-carrying capacity is maintained in the area of the bond section.

 

First Results have proven that tapering the end of the wire reduces the stress in the interface as well as the accumulated distention and the tensions inside the tail area and the heel area

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Vorteile

• Reducing shear stress due to thermal extension
• Current bonding methods can still be used
• Avoidance of fatigue cracks
• Consistent good bonding
  

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Anwendungsbereiche

The technology can be used in the construction of electrical connections. Typically wire bonding is used for connecting a so-called die to electrical connections of a chip housing, like for example the semiconductors of an integrated semiconductor, a light emitting diode or a sensor.

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Service

Chances for Collaboration:

• R&D Cooperation
• Patent Purchase
• Licensing