Active solid-state devices (e.g. – transistors – solid-state diode – Combined with electrical contact or lead – Of specified material other than unalloyed aluminum
Reexamination Certificate
2002-04-30
2004-04-27
Flynn, Nathan J. (Department: 2826)
Active solid-state devices (e.g., transistors, solid-state diode
Combined with electrical contact or lead
Of specified material other than unalloyed aluminum
C257S690000, C257S741000, C257S751000, C257S761000, C257S762000, C257S772000
Reexamination Certificate
active
06727587
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a connection device and, more particularly, to a connection device in or for a circuitry device, for instance, in or for a semiconductor module or the like. Further, the present invention relates to a method for producing such a connection device.
When constructing or constituting circuitry configurations, it is often necessary to combine different materials with each other to ensure a mechanical and/or electrical contact. In particular, this is true in the field of contacting circuitry units, for instance, chips or the like, with respective contact devices. Because of the different thermo-mechanical properties, which are primarily based on different heat expansion coefficients, in use and operation of such circuitry units and electronic elements or the like mechanical stresses and tensions between different components thereof may occur.
These effects regarding mechanical stresses between different components are of major disadvantage with respect to the lifetime of the different electronic components.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a connection device and method for producing the same that overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices and methods of this general type and that is capable of compensating thermo-mechanical stresses and/or tensions at interfaces between a circuitry unit and a contact device in a particular easy and reliable manner involving only a small amount of surface areas.
With the foregoing and other objects in view, there is provided, in accordance with the invention, a connection device for at least one of mechanically and electrically connecting at least one circuitry unit of a circuitry device with at least one contact device and to thereby thermo-mechanically uncouple the circuitry unit and the contact device, the connection device including a preformed section of at least one of the group consisting of a metallic section and an alloy section, the preformed section having a buffer region including silver, an intermediate region including a silver-tin alloy, and a connection region including an intermetallic substrate of at least one of tin, silver, a metal able to form an intermetallic compound with at least one of tin and silver, and a metal material able to form an intermetallic compound with at least one of tin and silver, and the preformed section disposed at one of the group consisting of the circuitry unit and the contact device.
The connection device of the invention in or for a circuitry device is, in particular, configured to be contained in or applied for a semiconductor module or the like. The connection device is adapted to mechanically and/or electrically connect at least one circuitry unit of the circuitry device with at least one contact device and to thereby thermo-mechanically uncouple the circuitry unit and the contact device. The circuitry unit may be built up as a chip or the like. The connection device is substantially formed as a metallic section and/or as an alloy section at least in part of a region of the circuitry unit and/or at least in part of a region of the contact device. The contact device may be built up as a preformed metallic section and/or alloy section. According to the invention, the connection device has a buffer region, an intermediate region, and a connection region. The buffer region contains or is formed of silver, the intermediate region contains or is formed of a silver-tin alloy region, and the connection region has or is formed as an intermetallic substrate of tin and/or silver with at least one further metal and/or metal like material, the further metal and/or metal like material being capable of forming an intermetallic compound with tin and/or silver.
It is, therefore, a basic aspect of the present invention to build up the connecting device with three regions, the first region being a buffer region of silver and, therefore, being capable of absorbing thermo-mechanical stresses between its surrounding. Furthermore, the present invention provides an intermediate region containing or being formed of a silver-tin alloy region and a connection region having or being formed as an intermetallic substrate, wherein the intermetallic substrate is made of tin and/or silver with at least one further metal and/or metal like material, the further metal and/or metal like material being capable of forming an intermetallic compound with tin and/or silver.
In accordance with another feature of the invention, the at least one further metal or metal like material is one metal or metal like material from the group including Cu, Ag, Ni, NiP, Au, NiPd, Fe, Pd, Pt, Ti, V, or the like.
In accordance with a further feature of the invention, the intermetallic substrate is an intermetallic tin-substrate.
The buffer region may be formed as at least one layer or film; a plurality of layers or films is also possible.
In accordance with an added feature of the invention, the buffer region is formed with at least one surface portion thereof as an integral part of the structure of the circuitry unit. This particular measure ensures a particularly reliable mechanical and electrical contact between the connection device and the circuitry unit to be connected thereto.
Alternatively or additionally, in accordance with an additional feature of the invention, the connection region may also be formed as at least one layer or film; also, in this case, a plurality of layers of films is possible.
In accordance with yet another feature of the invention, it is preferred to form the connection region at least with one surface portion thereof as an integral part of the connection device and/or of the circuitry. With such a measure, a particular reliable connection between the connection device and the contact device and/or the circuitry unit is possible and ensured.
In accordance with yet a further feature of the invention, the connection region for mechanically and/or electrically connecting the connection device with the contact device is preferably formed as a tin-alloy region with at least one metal component of the contact device. For instance, copper is employed at least as a part of the contact device, then the tin-alloy region may include or may be formed as a region of Cu
6
Sn
5
(&egr;) or the like.
To better ensure the compensation of thermo-mechanical stresses between the contact device and the circuitry unit, in accordance with yet an added feature of the invention, the intermediate region preferably contains a sequence of a plurality of layers or films.
In accordance with yet an additional feature of the invention, the sequence of layers or films includes a first layer containing or being formed of Ag(Sn), a second layer containing or being formed of Ag
5
Sn(&zgr;), and a third or last layer containing or being formed of Ag
3
Sn(&egr;).
In accordance with again another feature of the invention, it is of further advantage if the first layer of the intermediate region is in contact and/or at least in part integral with the buffer region.
Further, preferably, the third layer or last layer of the intermediate region is in contact and/or at least partially integral with the contact region.
With the objects of the invention in view, there is also provided a method for producing a circuitry connection device including the steps of at least one of mechanically and electrically connecting at least one circuitry unit of a circuitry device with at least one contact device to thermo-mechanically uncouple the circuitry unit and the contact device by providing a metal/alloy portion between respective predetermined surface portions of the circuitry unit and the contact device, the metal/alloy portion having a first section including silver and facing the surface portion of the circuitry unit, a second section including a silver-tin alloy and facing the surface portion of the contact device, and the first and second sections facing each other, heating at least one of the metal/alloy
Flynn Nathan J.
Locher Ralph E.
Mandala Jr. Victor A.
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