Stock material or miscellaneous articles – All metal or with adjacent metals – Composite; i.e. – plural – adjacent – spatially distinct metal...
Reexamination Certificate
1998-10-20
2001-03-06
Jones, Deborah (Department: 1775)
Stock material or miscellaneous articles
All metal or with adjacent metals
Composite; i.e., plural, adjacent, spatially distinct metal...
C216S013000, C216S100000, C228S101000, C228S262100, C228S903000, C257S748000, C257S750000, C257S751000, C257S761000, C257S762000, C257S763000, C257S764000, C257S765000, C257S766000, C257S767000, C257S768000, C257S769000, C257S770000, C257S771000, C428S606000, C428S607000, C428S627000, C428S635000, C428S643000, C428S644000, C428S645000, C428S650000, C428S651000, C428S652000, C428S654000, C428S655000, C428S656000, C428S660000, C428S661000, C428S668000, C428S669000, C428S671000, C428S675000, C428S680000, C428S
Reexamination Certificate
active
06197435
ABSTRACT:
SUBSTRATE
The present invention relates to a substrate, a method for producing the same and a metal bonded product suitable for the substrate.
The substrate of the present invention is obtained by forming a metal circuit and/or a heat-radiating metal plate on a ceramic substrate. A substrate having a metal circuit only or a metal circuit and a heat-radiating metal plate formed is used as a circuit substrate, or a substrate having a heat-radiating metal plate only formed is used as a heat-radiating substrate. In the present invention, an essential difference between a circuit substrate and a heat-radiating substrate resides in simply that the heat-radiating substrate does not have a metal circuit formed, and accordingly the present invention is described by taking a circuit substrate as an example.
Recently, power modules including large-power and high-efficient inverters have been changed in accordance with improvements on industrial apparatuses such as robots, motors and the like, and heat generated from semiconductor elements steadily increases. In order to efficiently radiate this heat, various steps have been conventionally applied to power module boards. Particularly, a ceramic board having a good heat conductivity has been recently developed, and there is a tendency of employing a structure prepared by bonding a metal plate such as a copper plate onto a substrate board, forming a metal circuit and placing a semiconductor element on the metal plate as it is or after treated with nickel-plating. In this case, there is also a structure having a heat-radiating metal plate such as a copper plate formed on the opposite side of a ceramic substrate having a metal circuit.
Such a module has been used for simple machine tools at the first stage, but recently such a module is used for a welder, a driving part of electric railcar, an electric car and the like, which require durability under more severe environmental conditions end further miniaturization. Accordingly, with regard to a ceramic substrate also, a thickness of a metal circuit is increased to raise an electric current density and durability to thermal shock is required to be improved. In order to satisfy these requirements, a research is made for preparing a new ceramic sintered material.
Heretofore, a commonly used circuit substrate has a structure having a copper circuit formed on an alumina substrate or an aluminum nitride substrate, but in order to improve reliability to heat cycle resistance, a structure having an aluminum circuit formed on an aluminum nitride substrate has been developed. However, since aluminum is worse in electric properties such as electric current density than copper, such a circuit substrate is not widely prevalent.
The present invention has been made under the above circumstances, and its object is to provide a highly reliable substrate (a circuit substrate or a heat-radiating substrate) excellent in heat cycle resistance. Another object of the present invention is to provide a process for preparing such a highly reliable substrate at a satisfactory productivity. Further, other object of the present invention is to provide a metal bonded product suitable as a metal circuit and/or a heat-radiating metal plate to be used for such a highly reliable substrate.
Thus, the present invention resides in a substrate, a method for producing the substrate and a metal bonded product, which have the following essential features.
Substrate embodiment 1: A substrate having a metal circuit and/or a heat-radiating metal plate formed on a ceramic substrate, herein the metal circuit and/or the heat-radiating metal plate comprise the following first metal-second metal bonded product (except for a combination of the same kinds of metals of the first metal and the second metal) and/or the following first metal-third metal-second metal bonded product, and the first metal is bonded to the ceramic substrate;
first metal: a metal selected from the group consisting of aluminum (Al), lead (Pb), platinum (Pt) and an alloy containing at least one of these metal components,
second metal: a metal selected from the group consisting of copper (Cu), silver (Ag), gold (Au), aluminum (Al) and an alloy containing at least one of these metal components, and
third metal: a metal selected from the group consisting of titanium (Ti), nickel (Ni), Zirconium (Zr), molybdenum (Mo), tungsten (W) and an alloy containing at least one of these metal components.
Substrate embodiment 2: The substrate according to Substrate embodiment 1, wherein the first metal is aluminum and the second metal is nickel-coated copper.
Substrate embodiment 3: The substrate according to Substrate embodiment 1, wherein the first metal is bonded to the third metal through an alloy layer (a) containing first metal-third metal-1b Group metal, an alloy layer (b) containing first metal-third metal-4b Group metal and an alloy layer (c) of first metal-third metal.
Substrate embodiment 4: The substrate according to Substrate embodiment 3, wherein the first metal is aluminum, the second metal is copper and the third metal is nickel.
Substrate embodiment 5: The substrate according to Substrate embodiment 3, wherein the 1b Group metal is copper and the 4b Group metal is silicon.
Substrate embodiment 6: The substrate according to Substrate embodiment 4, wherein the 1b Group metal is copper and the 4b Group metal is silicon.
Substrate embodiment 7: The substrate according to Substrate embodiment 1, wherein the substrate is a power module substrate.
Method embodiment 1: A method for preparing substrate of embodiment 1, which comprises bonding a first metal circuit pattern and/or a heat-radiating metal plate pattern to a metal circuit-forming surface and/or a heat-radiating metal plate-forming surface of a ceramic substrate by active metal-soldering method, and further bonding a second metal pattern different from the first metal thereto with or without intervening a third metal therebetween.
Method embodiment 2: A method for preparing substrate embodiment 1, which comprises bonding a solid metal plate of a first metal to a metal circuit-forming surface and/or a heat-radiating metal plate-forming surface of a ceramic substrate by active metal-soldering method, further bonding a solid metal plate of a second metal different from the first metal thereto with or without intervening a third metal therebetween, and then etching to form a metal circuit and/or a heat-radiating metal plate.
Method embodiment 3: The method according to Method embodiment 1, wherein the first metal is aluminum and the second metal is nickel-coated copper.
Method embodiment 4: The method according to Method embodiment 2, wherein the first metal is aluminum and the second metal is nickel-coated copper.
Method embodiment 5: The method according to Method embodiment 1, wherein the substrate is a power module substrate.
Metal bonded product embodiment 1: A metal bonded product obtained by bonding the following first metal to the following third metal through an alloy layer (a) containing first metal-third metal-1Group metal, an alloy layer (b) containing first metal-third metal-4b Group metal and an alloy layer (c) of first metal-third metal;
first metal: a metal selected from the group consisting of aluminum (Al), lead (Pd), platinum (Pt) and an alloy containing at least one of these metal components, and
third metal: a metal selected from the group consisting of titanium (Ti), nickel (Ni), Zirconium (Zr), molybdenum (Mo), tungsten (W) and an alloy containing at least one of these metal components.
Metal bonded product embodiment 2: The metal bonded product according to Metal bonded product embodiment 1, wherein the first metal is aluminum and the third metal is nickel.
Metal bonded product embodiment 3: The metal bonded product according to Metal bonded product embodiment 1, wherein the 1b Group metal is copper and the 4b Group metal is silicon.
Metal bonded product embodiment 4: The metal bonded product according to Metal bonded product embodiment 2, wherein the 1b Group metal is copper and the 4b Group meta
Fushii Yasuhito
Nakamura Miyuki
Tsujimura Yoshihiko
Denki Kagaku Kogyo Kabushiki Kaisha
Jones Deborah
Koehler Robert R.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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