TWI643274B - Copper alloy thin wire for ball bonding - Google Patents

Abstract

It is an object of the present invention to provide a copper alloy bonding wire which does not bend a tail wire by containing nickel (Ni) in a copper-phosphorus alloy, and the present invention solves the following problem: directly after the second bonding When pulled up to cut off, the tail wire will bend inside the welding pin or the front end of the wire will bend.

The copper alloy fine wire for ball bonding of the present invention is characterized in that nickel (Ni) is 0.02% by mass or more and 2% by mass or less, and phosphorus (P) is 5 ppm by mass or more and 800 ppm by mass or less. The total amount of metal elements is less than 100 ppm by mass and the remainder is copper (Cu).

Description

Copper alloy thin wire for ball bonding

The present invention relates to a copper alloy thin wire for ball bonding, which is suitable for connecting an IC wafer electrode for a semiconductor device to a substrate such as an external lead frame, and more particularly to a very thin wire having a wire diameter of 15 μm or less. A thin copper alloy wire that does not bend.

In general, a method called ball bonding is used for the first bonding of the copper bonding wire and the electrode, and a wedge bonding is used for the wedge bonding of the wiring between the copper bonding wire and the semiconductor circuit wiring substrate. The first bonding applies a thermal arc to the front end of the wire from a torch electrode in an electronic frame off (EFO) manner, whereby the leading end of the wire forms a true ball called a solder ball (FAB). Next, while the FAB was pressed against an aluminum pad heated in the range of 150 to 300 ° C by a capillary, ultrasonic waves were applied to bond the bonding wires to the aluminum pad.

Next, the welding pin is lifted while the bonding wire is pulled out, and the welding pin is moved to the wedge bonding portion while drawing the loop toward the lead frame. As illustrated by the drawings, the wedge welding by the welding pin is as shown in the first figure, and the bonding wire (1) can be wedge-welded to the lead frame (3) by the welding pin (2). At this time, the end portion of the wedge-bonded bonding wire (1) is flattened by the tip end portion of the welding pin (2). As shown in the second figure, the area of the end face of the wire at the joint becomes thinner than the wire diameter. Next, the bonding wire (1) is cut out from the joint. If the wire (1) is clamped by the wire clamp (4) located at the upper part of the welding pin (2) and pulled up, as shown in the third figure, it is located in the lead frame (3). The wire is simply cut off at the front end portion of the bonding wire (1) at the joint.

Next, the solder pins are moved to the first joint, and this step is omitted in the drawings. Next, spark discharge is performed by a discharge torch, and a molten solder ball (FAB) is formed at the tip end of the bonding wire to first bond the bonding wire and the aluminum pad. This bonding cycle is repeated, and the pad and the lead frame (3) are sequentially connected through the bonding wire (1).

However, it is difficult to obtain homogeneous mechanical properties from a copper alloy bonding wire composed of 10 to 500 ppm of phosphorus (P) and copper (Cu) having a purity of 99.9% or more (see Japanese Patent Laid-Open Publication No. Hei 7-122564). ). Therefore, after the second bonding of the bonding wire (1), if the soldering pin (2) and the wire holder (4) are raised to cut the wire in a state where the wire holder (4) is closed, the first As shown in the four figures, the front end of the bonding wire may be bent. In severe cases, the bonding wire may be bent into a zigzag shape in the soldering pin.

Therefore, in the related art, the neck portion of the bonding wire is formed by stretching the bonding wire upward (slightly) after the second bonding, temporarily loosening the wire holder, and then closing the wire holder again (strongly) pulling In the wire rod, the bonding wire is cut from the neck portion by the improvement of the bonding machine (Japanese Patent Laid-Open Publication No. 2007-66991 (Patent Document 1)) to solve the defect of the mechanical properties of the bonding wire.

In the copper bonding wire, in the case where the wire diameter is as thick as 25 μm, the wire which is deformed into such a J-shape is hardly seen. However, if the wire diameter of the bonding wire is as low as 20 μm, and the bonding speed is increased and the bonding speed is increased, the improvement of the bonding machine described above cannot be employed, and the wire formed into a J-shape starts to appear.

If the joint line has such a front end portion that is deformed into a J-shape, the loop shape is skewed when the loop is drawn. Further, there is a case where the spark current cannot smoothly hit the tip end of the bonding wire or the center of the molten solder ball is shifted, which may cause the FAB to become a flat shaped solder ball. Further, if the deformation of the J-shape is too severe, it becomes a zigzag deformation as found in the past, and it becomes a cause of clogging of the welding pin.

On the other hand, if phosphorus (P) is added to high purity oxygen-free copper of 99.99 wt% or more, Phosphorus (P) forms an oxide at 350 ° C to perform deoxidation of copper (Cu), so that surface oxidation can be prevented when the first bonding forms FAB, and a pure spherical shape is obtained, which is known (Japanese special) Kai-zhao 62-80241). Further, phosphorus (P) rapidly diffuses in polycrystalline high-purity copper (Cu) (P. SPINDLER et al., Metallurgic TRANSACTIONS A, June 1978, Vol. 763, p. 763), and is easily segregated to its surface (IN). SERGEEV et al., Bulletin of the Russian Academy of Sciences: Physics Magazine, October 2008, Vol. 72, No. 10, 1388, is also known.

Further, the high-purity copper having a purity of 99.99% by weight or more (4N) or more refers to the number of "9" in the percentage ratio of copper to the purity of the entire metal component from which gas components such as H, N, C, and O are removed by weight. It is 4. Generally, high-purity copper does not contain an expensive precious metal component, so high-purity copper having a purity of 99.99% by weight or more means that the total amount of the elemental metal other than copper (Cu) is less than 100 ppm by mass. Further, generally, high-purity copper is defined as a gas component removal (Qingmu Zhuangsi et al., Journal of Copper and Copper Alloys, January 2003, Vol. 42, No. 1, page 21). On the other hand, it is considered that if a gas component such as oxygen is present in the bonding wire at a high concentration, the FAB of the bonding wire is adversely affected.

Therefore, there are a large number of patent applications for controlling gas components in high purity copper. For example, in the specification of Japanese Laid-Open Patent Publication No. Sho 61-20693, it is described that these additive elements fix H, O, N, and C in the alloy, and suppress generation of H ₂ , O ₂ , N _{2 ,} and CO gases (the publication of the Gazette) 2 pages upper right column 12~14). Also, in Japanese Laid-Open Patent Publication No. 2003-225705, the Vickers hardness of the initial solder ball of each of the soft copper wires of each wire diameter is measured, and the Vickers hardness (Hv) of the copper bonding wire and the oxygen and carbon present in the copper material are found. Since the amount of nitrogen and sulfur is related to the gas content, a method for processing soft copper is disclosed, which is characterized in that 99.98% by weight or more of copper is used as a material, and the cross-sectional area is extended to 0.01 mm ² or less, and annealing and quenching are performed. The total amount of oxygen, carbon, nitrogen, and sulfur gas components present in the copper material is 0.005% by weight or less, and an aqueous solution containing 0.02% by weight or less of the total amount of the oil component and the surfactant is used as the extension step. The lubricating fluid used.

In addition, an application for arranging a high-purity copper raw material metal of 4N or more does not contain chlorine (Japanese Laid-Open Patent Publication No. 2008-153625, No. 2011-3745).

On the other hand, there are currently a large number of patent applications in which nickel (Ni) is added as a additive element to a high-purity copper-phosphorus alloy. For example, Japanese Laid-Open Patent Publication No. Sho 61-20693 (Patent No. JP-A-61-20693) discloses a bonding wire comprising 0.001 to 2% by weight of 24 elements selected from the group consisting of Ni and P (the rare earth element is also used as one type). Species or more than two elements, the remainder being substantially copper. Further, a bonding wire containing 0.001% by weight or more and less than 0.1% by weight, which is selected from seven types of silver (Ag), etc., is also disclosed in the patent application scope (1) of JP-A-61-52333 (first) One or two or more elements of the element group are added, and one or two or more elements selected from the group consisting of 22 elements (second additive element groups) such as Ni, Pd, Pt, Au, and P are contained in an amount of 0.001 to 2% by weight. The remainder is essentially copper.

Further, in claim 2 and claim 5 of Japanese Laid-Open Patent Publication No. 2010-171235 (Patent Document 2), a copper alloy wire for high-purity ball bonding is disclosed, which is characterized by: adding phosphorus (P) The room temperature hardness of the initial solder ball of the bonding wire is lower than the copper alloy having the purity equal to or higher than the phosphorus (P), and the total amount of the metal elements other than the phosphorus is equal to or less than the content of phosphorus (P), and copper ( The metal element other than the phosphorus (P) in the Cu) is one or more selected from the group consisting of Pt, Au, Ag, Pd, Ca, Fe, Mn, Mg, Ni, Al, Pb, and Si.

Further, in the patent application scope (2) of Japanese Laid-Open Patent Publication No. Hei 01-290231 (Patent Document 3), a copper alloy ultrafine wire for a semiconductor device is disclosed, which is characterized in that the total of S, Se, and Te is made. In addition, at least 1.0 ppm of Si is added to the high-purity oxygen-free copper having a content of 1.0 ppm or less, and one or two or more of eight elements such as Ni and P having a total of 1.0 to 500 ppm of Si are added. The following is shown in 17: the alloy composition and the content (ppm) are Si: 132, Ni: 28, and P: 76 to produce a copper alloy fine wire having a diameter of 25 μm.

The prior art related to high-purity copper for controlling gas components and the prior art related to high-purity copper-phosphorus alloys are intended to provide excellent material cost, excellent ball bonding shape and wire bondability, and good loop formation properties. The mass production property is also an excellent copper bonding wire for a semiconductor element. However, if only the concentrated layer of phosphorus (P) is provided on the surface of the bonding wire, the mechanical properties of the wire itself of the thin bonding wire become unstable, and the problem of the above-described bending of the tail wire or the bending of the tip end of the wire is not solved.

Prior technical literature

Patent literature

Patent Document 1 Japanese Patent Laid-Open Publication No. 2007-66991

Patent Document 2 Japanese Patent Laid-Open Publication No. 2010-171235

Patent Document 3 Japanese Patent Publication No. 01-290231

SUMMARY OF THE INVENTION An object of the present invention is to provide a copper alloy bonding wire which is formed by causing a copper-phosphorus alloy to contain nickel (Ni) so that the tail wire is not bent into a J shape, and the present invention solves the following problems: after the second bonding When the wire is pulled up directly to cut off, the tail wire is bent inside the welding pin or the front end of the wire is bent.

An invention of a copper alloy fine wire for ball bonding for solving the problem of the present invention is characterized in that nickel (Ni) is 0.02% by mass or more and 2% by mass or less, and phosphorus (P) is 5 ppm by mass. The above 800 ppm by mass or less, the total amount of other elemental metal elements is less than 100 ppm by mass, and the remainder is copper (Cu).

Further, in one of the copper alloy thin wires for ball bonding for solving the problems of the present invention, a copper alloy core material comprising the following components is coated with a palladium (Pd) extension layer: nickel (Ni) 0.02% by mass or more and 2% by mass or less, and phosphorus (P) is 5 ppm by mass or more and 800 ppm by mass or less, and other base metal elements The total amount is less than 100 ppm by mass and the remainder is copper (Cu).

Further, one of the copper alloy thin wires for ball bonding for solving the problem of the present invention is characterized in that a palladium (Pd) extension layer and a gold (Au) thin layer are coated on a copper alloy core material composed of the following components. The extension layer: nickel (Ni) is 0.02% by mass or more and 2% by mass or less, phosphorus (P) is 5 ppm by mass or more and 800 ppm by mass or less, and the total amount of other elemental metal elements is less than 100 ppm by mass and the remainder is copper (Cu) ).

An embodiment of the present invention is characterized in that the upper limit of the nickel (Ni) is 1% by mass or less.

Furthermore, an embodiment of the present invention is characterized in that the upper limit of the phosphorus (P) is 200 ppm by mass or less.

Further, an embodiment of the present invention is characterized in that: in the above-mentioned three inventions of the copper alloy fine wire for ball bonding, a copper alloy fine wire for ball bonding in which nickel is replaced by palladium (Pd) or platinum (Pt) (Ni) up to 30% by mass of nickel (Ni).

Further, another aspect of the present invention is characterized in that: the copper alloy fine wire for ball bonding of any one of the above three inventions of the copper alloy fine wire for ball bonding, in which gold (Au) or silver (Ag) is substituted Nickel (Ni) is up to 30% by mass of nickel (Ni).

In the present invention, the "extension layer" and the "thin extension layer" generally mean that the cross section of the bonding wire and the copper alloy core material are in a perfect circle, and the palladium (Pd) layer is uniformly coated on the outer ring of the copper alloy core material. Or a theoretical layer calculated by reducing the diameter of the palladium (Pd) layer and the gold (Au) layer. Therefore, the expressions of "extended layer" and "thin extension layer" may not be able to correctly express the actual surface morphology, but they are conveniently expressed in the presence of a "layer" of thickness by auger analysis. The range of the fine particles of palladium (Pd) and gold (Au) in the depth direction is detected from the surface of the bonding wire. Since the thickness of the bonding wire of the present invention is extremely thin, if the fine particles are detected from the surface of the bonding wire by high frequency inductively coupled plasma atomic emission spectrometry (ICP-AES), it is determined that there is an "extension layer" and " Thin extension layer."

In the copper alloy fine wire for ball bonding of the present invention, the high-purity copper alloy base material of 6N to 4N generally contains 0.2 ppm by mass or more and 50 ppm by mass or less of oxygen. The amount of such oxygen is hardly changed in the copper alloy composition of the present invention even when the copper alloy base material is re-dissolved, cast, once drawn, intermediate heat-treated, secondary drawn, finally heat-treated, and stored. When oxygen is contained in the copper (Cu) matrix, the base metal element is likely to form an oxide, so that the oxygen content is as small as possible, and is preferably 10 ppm by mass or less, more preferably 50 ppm by mass or less.

In the copper alloy thin wire for ball bonding of the present invention, nickel (Ni) is 0.02% by mass or more and 2% by mass or less because nickel (Ni) can fix oxygen contained in the copper alloy raw material metal and can also prevent Surface segregation of phosphorus (P). A predetermined amount of nickel (Ni) in the copper alloy matrix is finely dispersed to fix the oxygen in the matrix. The oxygen fixed by nickel (Ni) is not deoxidized by phosphorus (P), so the rigidity of the wire itself is increased. Therefore, the quantitative nickel (Ni) can increase the Young's modulus of the copper alloy.

The inventors of the present invention have known that the copper alloy fine wire having a high Young's modulus can be obtained by shortening the cut-off area of the end portion before the tail line and the second back when the second joint is not easily bent. That is, it is known that the bending property of the tail wire is such that the dynamic property of the bonding wire is derived from the static property of the copper alloy fine wire such as the Young's modulus.

In the copper alloy thin wire for ball bonding of the present invention, nickel (Ni) is bonded to an oxygen atom to prevent oxidation of the copper substrate. Nickel (Ni) bonded to oxygen is fixed in the copper alloy matrix. In this case, if oxygen is excessively supplied continuously, nickel oxide particles dispersed in the copper alloy matrix are observed. Further, nickel (Ni) is also easily bonded to phosphorus (P) to prevent the movement of phosphorus (P) in the copper matrix. Therefore, appropriate nickel (Ni) functions to increase the Young's modulus of copper (Cu).

When the lower limit amount of nickel (Ni) is less than 0.02% by mass, the surface of the phosphorus (P) cannot be prevented from segregating, and the cut state of the end portion of the tail line is destabilized, so that nickel (Ni) is lowered. Limited to 0.02 More than % by mass. The lower limit of nickel (Ni) is preferably 0.04% by mass or more, and more preferably 0.06% by mass or more.

In addition, when the upper limit of the amount of nickel (Ni) exceeds 2% by mass, the oxidation of the surface of the bonding wire is accelerated, so that the upper limit of the amount of nickel (Ni) is 2% by mass or less. The upper limit of nickel (Ni) is preferably 1% by mass or less. The upper limit of nickel (Ni) is more preferably 0.5% by mass or less, and still more preferably 0.3% by mass or less.

In the copper alloy fine wire for ball bonding of the present invention, the content of the phosphorus (P) is 5 ppm by mass or more and 800 ppm by mass or less. Phosphorus (P) is an element which acts on copper (Cu) and oxygen and is easily surface segregated. Further, if phosphorus (P) is present in a percentage order, it is known that a copper-like (Cu) and palladium (Pd) flux-like flux acts. Therefore, even if phosphorus (P) is present in the above range, it is considered that it precipitates on the surface of the molten solder ball and has an effect of improving the bonding strength with the aluminum pad. Further, since phosphorus (P) and oxygen form volatile phosphate ions (PO ₄ ^2- ), when FAB is formed, it functions to discharge oxygen existing in the copper alloy matrix from the molten solder ball to the atmosphere. However, it is known that nickel (Ni) plays a role earlier than phosphorus (P) for oxygen in a copper alloy matrix.

The upper limit of the phosphorus (P) is 800 ppm by mass or less because the tail wire is unstable if it exceeds 800 ppm by mass. It is preferably 500 ppm by mass or less, more preferably 200 ppm by mass or less, still more preferably less than 100 ppm by mass. The reason why the lower limit is 5 ppm by mass or more is that if it is less than 5 ppm by mass, the flux action cannot be exhibited.

In the copper wire for ball bonding of the present invention, in the case where the nickel (Ni) content is set to 100% by mass, it may be substituted with palladium (Pd) or platinum (Pt) up to 30% by mass because palladium is only required When (Pd) or platinum (Pt) is also in this range, it exerts the same effect as nickel (Ni). The content of expensive palladium (Pd) or platinum (Pt) is preferably 20% by mass or less of nickel (Ni), more preferably 10% by mass or less of nickel (Ni).

Further, in the case of setting the nickel (Ni) content to 100% by mass in the copper alloy thin wire for ball bonding of the present invention, it can be replaced by gold (Au) or silver (Ag) by up to 30% by mass. Because as long as gold When (Au) or silver (Ag) is also within this range, it exerts the same effect as nickel (Ni). The content of expensive gold (Au) or silver (Ag) is preferably 20% by mass or less of nickel (Ni), more preferably 10% by mass or less of nickel (Ni).

Further, in the copper alloy thin wire for ball bonding of the present invention, the total amount of other elemental metal elements is less than 100 ppm by mass in order to prevent formation of an oxide of a base metal element in the copper alloy matrix. If the oxide of the base metal element is formed at the grain boundary of the copper, the tail line of the second back is easily deformed. It is preferably 50 ppm by mass or less, and if the raw material metal price is neglected, it is more preferably less than 10 ppm by mass, and still more preferably 5 ppm by mass or less. For example, when a copper raw material metal having a purity of 6N (99.9999 mass%) or more is used, the total amount of other metal elements is less than 1 mass ppm, but the copper raw material metal is too expensive and is not practical, and thus is not preferable. In addition, "other base metal elements" means elements such as bismuth (Bi), selenium (Se), tellurium (Te), zinc (Zn), iron (Fe), nickel (Ni), and tin (Sn).

Further, a gas component other than oxygen, such as hydrogen or chlorine, which is generally contained in a 6N to 4N high-purity copper alloy base material, does not affect the Young's modulus of the copper alloy fine wire. For example, the amount of hydrogen contained in the 6N high-purity copper alloy base material is equal to or less than the detection limit (0.2 ppm by mass) of the analyzer. Further, when hydrogen is present in the copper alloy, hydrogen and oxygen are combined into water vapor when the molten solder ball is formed, and the molten solder ball is unstable. Hydrogen has the following conditions: hydrogen intrudes into the molten liquid from the dissolved crucible wall, or in the heat treatment step, if it is rapidly cooled, hydrogen is mixed into the surface of the copper raw material metal, or if the palladium (Pd) is coated by wet plating, The stored hydrogen remains, so it is necessary to avoid the incorporation of such hydrogen.

Further, in the copper alloy thin wire for ball bonding of the present invention, even if it is covered with a palladium (Pd) extension layer, or a palladium (Pd) extension layer and a gold (Au) thin extension layer, since the extension layer is less than 100 nm It is extremely thin, so it does not damage the Young's modulus of the copper alloy core material. The palladium (Pd) extension layer of 20 nm or more and 60 nm or less has the effect of delaying the oxidation of the fine line of the copper alloy. In addition, when it is covered with a gold (Au) thin extension layer of 3 nm or less, after the surface current, the heat generation phenomenon of the wire itself is generated, so that the current is not passed. The spark discharge of the Pd stretch layer is stabilized to form a uniform molten solder ball.

In addition, it is expressed as an "extension" layer and a "thin extension" layer, which is purely for wet. The coating layer in the dry plating state is distinguished. Even if the palladium (Pd) or gold (Au) precious metal coating material is coated with the secondary wire to the final wire diameter, the object of the present invention cannot be achieved. The reason for this is that it is impossible to fill the irregular longitudinal grooves caused by the abrasion of the wire mold with the final coating layer, and it is impossible to cover the entire circumference of the wire with a nanometer scale.

Although it differs depending on the type of the combination of the core material and the covering material, in order to form the extremely thin and thin extending layer of the present invention, the diameter of the wire material generally needs to be reduced by 90% or more. In addition, in the present invention, the ultra-thin palladium (Pd) extension layer and/or the gold (Au) thin extension layer on the surface of the wire are all disappeared at the joint during the ultrasonic bonding of the second joint, but remain in the tail line. .

According to the copper alloy thin wire for ball bonding having the composition range of the present invention, the second back portion at the time of the second joining is less likely to be bent, and the bending of the tail wire is much smaller than that of the conventional copper alloy fine wire. Furthermore, if the shape of the tail wire is stable, the FAB at the time of the first joining does not become an effect of the shaped solder ball. Moreover, if the shape of the tail wire is stable, less heat can be used to obtain a positive ball for the FAB at the first joining. Therefore, the wire diameter can be made as small as 20 μm to 15 μm, and the effect of the high-density wiring which can form the bonding wires by the small-diameter solder balls can be obtained. Further, when the palladium (Pd) extension layer and the gold (Au) thin extension layer are coated on the nanometer scale, the molten solder balls can be stably formed.

Further, according to the copper alloy thin wire for ball bonding of the present invention, the base metal oxide is not dispersed in the copper matrix, so the wire itself is soft. Further, since the position of the spark discharge at the time of the first bonding is also stabilized, even if the coating of the palladium (Pd) extension layer or the palladium (Pd) extension layer and the gold (Au) thin extension layer is thinner than the conventional one, The effect of FAB stabilization at the time of bonding.

Further, in the case of the copper alloy thin wire for ball bonding of the present invention, when a gold (Au) stretching layer is provided on the outermost surface of the wire, even if the wires are wound in a plurality of times and wound up by 10,000 meters, the wires do not adhere to each other. As a result, the unwinding property of the wire becomes excellent. Further, as an additional effect, the slidability of the wire surface with respect to the welding pin becomes better. Further, according to the copper alloy thin wire for ball bonding of the present invention, the gold (Au) fine particles on the outermost surface of the wire are not peeled off from the extended layer of palladium (Pd). Therefore, even if the bonding is repeated a plurality of times, the oxide of copper (Cu) does not adhere to the soldering pin, so the soldering pin is not dirty.

1‧‧‧bonding line

2‧‧‧ solder pins

3‧‧‧ lead frame

4‧‧‧Wire holder

The first figure is a cross-sectional view of a bonding wire obtained by the wedge bonding of the copper alloy thin wires of the present invention.

The second figure shows a perspective view of the wedge bonding step of the copper alloy thin wires.

The third figure is a cross-sectional view schematically showing the cut state of the copper alloy fine wire after the wedge welding.

The fourth figure is a cross-sectional view showing a bonding line bent into a J-shape.

[Examples]

The core material is copper (Cu) having a purity of 99.9998 mass% (5N), and phosphorus (P) and nickel (Ni), and further palladium (Pd), platinum (Pt), gold (Au), and silver (Ag) are used. Add an element. As a base metal element, an element generally contained in high-purity copper is selected. That is, bismuth (Bi), selenium (Se), tellurium (Te), zinc (Zn), iron (Fe), nickel (Ni), and tin (Sn) are appropriately selected. These metals will be blended within the intended range as Examples 1 to 23.

Next, this was continuously cast, and then the first drawing was performed to obtain a thick line (diameter: 1.0 mm) before the coating of the extending material. Next, an intermediate heat treatment (400 ° C × 4 hours) was carried out. after that, A noble metal coating layer formed of a gold (Au) thin extension layer and a palladium (Pd) extension layer is provided as needed. The semi-finished wire was continuously drawn for a second time by a wet method using a diamond drawing die, and subjected to a tempering heat treatment at 480 ° C for 1 second to finally obtain a copper alloy thin wire for ball bonding having a diameter of 15 μm. In addition, the average reduction ratio is 6 to 20%, and the final line speed is 100 to 1000 m/min. Further, the purity of gold (Au) is 99.99% by mass or more, and the purity of palladium (Pd) is 99.9% by mass or more.

In Table 1, Examples 1 to 8 are examples of the claim 1 of the present invention. Further, the fifteenth embodiment and the sixteenth embodiment are the embodiments of the claim 2 of the present invention. Further, the embodiment 21 is an embodiment of the claim 3 of the present invention. On the other hand, Embodiments 9, 10, 17, 19 and 23 are embodiments of the claim 4 of the present invention. Embodiments 11 to 13, 18, 20 and 22 are embodiments of the claim 5 of the present invention.

(bending test of bonding wire, etc.)

The bending test of the bonding wire was carried out in the following manner. In other words, a wire bonding machine (UTC-3000 manufactured by Shinkawa Co., Ltd.) was used to perform 100 wedges on a silver-plated (Ag) copper (Cu) plate at an ambient temperature of 25 ° C under conditions of ultrasonic output of 100 mA and bonding load of 90 gf. weld. Then, after the end of the wedge welding, as shown in the first figure, the welding pin (2) is raised and the bonding wire (1) is taken out from the front end of the welding pin (2), and then the wire holder (4) is closed. The welding pin (2) is raised together with the wire holder (4), as shown in the third figure, whereby the wire is cut in a state in which the bonding wire (1) of a predetermined length is extended out of the front end of the welding pin (2). . Perform this test a thousand times and check the number of bends of the bonding wire with the magnification projector. The results of this measurement are shown in the right column of Table 1. In addition, the Young's modulus is also measured and both show higher values.

[Comparative example]

The bonding wires of the compositions shown in Table 1 were used as Comparative Examples 1 and 2. In the wires of Comparative Examples 1 and 2, the compositions of phosphorus (P) and nickel (Ni) were out of range. In the same manner as in the examples, the bonding wires of Comparative Examples 1 and 2 were subjected to a bending test of the tail yarn to obtain the results in the right column of Table 1.

As is apparent from the results of the tests, all of the examples of the present invention have a high Young's modulus and no bending of the wire in the bending test of the tail wire, showing excellent performance. On the other hand, in the wires of Comparative Examples 1 to 3, bent wires were observed in the bending test.

[Industrial availability]

The copper alloy thin wire for ball bonding of the present invention can replace the conventional gold alloy wire, except for In addition to ICs, discrete integrated circuits (Discrete ICs), and memory ICs, it also has semiconductor applications such as IC packages for LEDs that require high-temperature, high-humidity and low-cost LEDs, and IC packages for automotive semiconductors.

Claims (5)

A copper alloy fine wire for ball bonding, which is characterized in that nickel (Ni) is 0.02% by mass or more and 2% by mass or less, and phosphorus (P) is 40 ppm by mass or more and 800 ppm by mass or less, and other elemental elements are The total amount is less than 100 ppm by mass and the remainder is copper (Cu). The copper alloy fine wire for ball bonding according to the first aspect of the invention, wherein the upper limit of the nickel (Ni) is 1% by mass or less. The copper alloy fine wire for ball bonding according to the first aspect of the invention, wherein the upper limit of the phosphorus (P) is 200 ppm by mass or less. The copper alloy fine wire for ball bonding according to the first aspect of the patent application, wherein nickel (Ni) is replaced by palladium (Pd) or platinum (Pt) up to a content of nickel (Ni) of 30% by mass. The copper alloy thin wire for ball bonding according to the first aspect of the patent application, wherein the content of nickel (Ni) is replaced by gold (Au) or silver (Ag) up to 30% by mass of nickel (Ni).