Aluminum bonding wire for power semiconductor
An aluminum wire with which, at the time of bonding a bonding wire for a power semiconductor, the wire is not detached from a wedge tool, and a long life is achieved in a power cycle test. The aluminum wire is made of an aluminum alloy having an aluminum purity of 99 mass % or more and contains, relative to a total amount of all elements of the aluminum alloy, a total of 0.01 mass % or more and 1 mass % or less of iron and silicon. In a lateral cross-section in a direction perpendicular to a wire axis of the aluminum wire, an orientation index of is 1 or more, an orientation index of is 1 or less, and an area ratio of precipitated particles is in a range of 0.02% or more to 2% or less.
1 . An aluminum wire comprising an aluminum alloy having an aluminum purity of 99 mass % or more,
the aluminum wire containing, relative to a total amount of the aluminum alloy, a total of 0.01 mass % or more and 1 mass % or less of iron and silicon,
wherein in a lateral cross-section in a direction perpendicular to a wire axis of the aluminum wire, an orientation index of (111) is 1 or more, an orientation index of (200) is 1 or less, and an area ratio of precipitated particles to the lateral cross-section in the direction perpendicular to the wire axis is 0.02% or more and 2% or less.
2 . The aluminum wire according to claim 1 , wherein the aluminum alloy contains a total of 0.1 mass % or more and 1 mass % or less of iron and silicon relative to the total amount, and an area ratio of the precipitated particles is 0.1% or more and 2% or less.
3 . The aluminum wire according to claim 1 , further containing, relative to the total amount of the aluminum alloy, a total of 50 mass ppm or more and 800 mass ppm or less of at least one element of gallium and vanadium.
4 . The aluminum wire according to any one of claim 1 , wherein a residual resistance ratio represented by the following formula is 10 or more,
Residual resistance ratio=(electric resistance at room temperature of 300 K/(electric resistance in liquid helium at 4.2 K) (1)
5 . The aluminum wire according to any one of claim 1 , wherein an area ratio of the precipitated particles is 0.2% or more and 1.8% or less.
6 . The aluminum wire according to any one of claim 1 , wherein an aluminum purity of the aluminum alloy is 99.9 mass % or less.
7 . The aluminum wire according to any one of claim 1 , wherein an orientation index of the (111) is 1.3 or more.
8 . The aluminum wire according to any one of claim 1 , wherein an orientation index of the (200) is 0.6 or less.
9 . The aluminum wire according to any one of claim 1 , wherein a content ratio of iron and silicon in the aluminum alloy is 0.3 or more and 90 or less by mass ratio represented by iron/silicon.
10 . The aluminum wire according to any one of claim 1 , wherein a wire diameter thereof is 40 μm or more and 700 μm or less.
11 . An aluminum wire manufacturing method comprising:
a step of preparing an aluminum alloy material, the aluminum alloy material being an aluminum alloy having an aluminum purity of 99 mass % or more and containing, relative to a total amount of the aluminum alloy, a total of 0.01 mass % or more and 1 mass % or less of iron and silicon; and
a step of performing wire drawing on the aluminum alloy material,
wherein in a lateral cross-section in a direction perpendicular to a wire axis of the aluminum wire, an orientation index of (111) is 1 or more, an orientation index of (200) is 1 or less, and an area ratio of precipitated particles to the lateral cross-section in the direction perpendicular to the wire axis is 0.02% or more and 2% or less.
12 . The aluminum wire manufacturing method according to claim 11 ,
wherein the step of performing wire drawing comprises:
an intermediate wire drawing step of obtaining an intermediate wire rod by performing wire drawing on the aluminum alloy material so as to have a wire diameter of 7 to times or more to 130 times or less a final wire diameter thereof;
an intermediate heat treatment in which the intermediate wire rod is heated at 400° C. or more to 560° C. or less for 60 minutes or more to 420 minutes or less;
a solution treatment step in which the intermediate wire rod is quenched at a quenching of 20° C./second or more and 300° C./second or less;
a final wire drawing step of performing wire drawing so as to obtain a final wire diameter of 40 μm or more and 700 μm or less; and
a final heat treatment of performing a batch heat treatment at 200° C. or more and 340° C. or less.
13 . A semiconductor device comprising:
a semiconductor element having an electrode; and
an aluminum wire connected to the electrode,
the aluminum wire comprising an aluminum alloy having an aluminum purity of mass % or more, and the aluminum wire containing, relative to a total amount of the aluminum alloy, a total of 0.01 mass % or more and 1 mass % or less of iron and silicon,
wherein in a lateral cross-section in a direction perpendicular to a wire axis of the aluminum wire, an orientation index of (111) is 1 or more, an orientation index of (200) is 1 or less, and an area ratio of precipitated particles to the lateral cross-section in the direction perpendicular to the wire axis is 0.02% or more and 2% or less.