JP2017048432A - Copper alloy fine wire for ball bonding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper alloy bonding wire without flexure of a tail wire capable of preventing the tail wire from bending in a capillary or a tip of the wire from folding when the wire is drawn up and cut immediately after second conjugation in a ball bonding method used for first conjugation of a copper bonding wire and an electrode in an IC chip.SOLUTION: There is provided a copper alloy fine wire for ball bonding containing Ni in a copper-phosphorus alloy and having a component composition consisting of Ni of 0.02 to 2 mass%, P of 5 to 800 mass.ppm and other base metal elements of less than 100 mass.ppm in total and the balance Cu.SELECTED DRAWING: Figure 2

Description

The present invention relates to a copper alloy fine wire for ball bonding suitable for connecting an IC chip electrode used in a semiconductor device and a substrate such as an external lead, and more particularly to a copper alloy fine wire in which a tail wire is not bent even with an extra fine wire of 15 μm or less.

Generally, a method called ball bonding is used for the first bonding between a copper bonding wire and an electrode, and a method called wedge bonding is used for wedge bonding between a copper bonding wire and a wiring on a semiconductor circuit wiring board. In the first joining, a true sphere called a free air ball (FAB) is formed at the tip of the wire by applying arc heat from the torch electrode to the tip of the wire by an electron frame off (EFO) method. Then, an ultrasonic wave is applied to the aluminum pad heated within the range of 150 to 300 ° C. while pressing the FAB with a capillary to bond the bonding wire and the aluminum pad.

Next, the capillary is raised while feeding out the bonding wire, and the capillary is moved to the wedge bonding point while drawing a loop toward the lead. Explaining by way of illustration, in wedge bonding using a capillary, as shown in FIG. 1, a bonding wire (1) is wedge-bonded to a lead (3) by a capillary (2). At this time, the end of the wedge-bonded bonding wire (1) is crushed by the tip of the capillary (2). As shown in FIG. 2, the area of the wire end surface at the joint location is thinner than the wire diameter. Then, the bonding wire (1) is cut off from the joint location. When the bonding wire (1) is grasped by the wire clamper (4) at the upper part of the capillary (2) and pulled upward, as shown in FIG. 3, the bonding wire (1 at the junction with the lead (3) is shown. ) Can be easily cut at the tip.

Next, although not shown, the capillary is moved to the first joining point. Then, a spark discharge is performed by a discharge torch, a molten ball (FAB) is formed at the tip of the bonding wire, and the bonding wire and the aluminum pad are first bonded. Such bonding cycle is repeated, and the pad and the lead (3) are sequentially connected through the bonding wire (1).

However, it is difficult to obtain uniform mechanical properties with a copper alloy bonding wire composed of 10 to 500 ppm of phosphorus (P) and the balance of copper (Cu) having a purity of 99.9% or more (Japanese Patent Laid-Open No. Hei 7- No. 122564). Therefore, after the bonding wire (1) is second bonded, the capillary (2) and the wire clamper (4) are lifted while the wire clamper (4) is closed, and the wire is cut as shown in FIG. When the tip of the wire is bent or severe, the bonding wire may be bent in a Z shape within the capillary.

Therefore, conventionally, after the second bonding, the diameter of the bonding wire is increased by pulling the bonding wire upwards (slightly), the wire clamper is opened, the wire clamper is closed, and the wire is tightened again. The bonding wire was cut from the reduced diameter portion by improving the pulling bonder (Japanese Patent Application Laid-Open No. 2007-66991 (Patent Document 1 described later)) to solve the problem of the mechanical properties of the bonding wire.

When the wire diameter was as thick as 25 μm even with the copper bonding wire, such a wire deformed into a J-shape was hardly found. However, when the wire diameter of the bonding wire is reduced to 20 μm, and it is attempted to increase the bonding speed, the bonder improvement as described above cannot be adopted, and the wire deformed into a J-shape has started to appear. .

If the bonding wire has such a tip portion deformed in a J shape, the loop shape is distorted when the loop is drawn. Further, since the spark current does not strike the tip of the bonding wire well or the center of the molten ball is shifted, it may cause a flat deformed ball due to FAB. Further, when the J-shaped deformation becomes severe, the Z-shaped deformation as seen in the prior art becomes a cause of clogging of the capillary.

On the other hand, when phosphorus (P) is added to high-purity oxygen-free copper of 99.99 wt% or more, phosphorus (P) forms an oxide at 350 ° C. and deoxidizes copper (Cu). It is known that surface oxidation at the time of FAB formation in bonding is prevented, and a clean true spherical shape is obtained (Japanese Patent Laid-Open No. 62-80241). Phosphorus (P) diffuses quickly in polycrystalline high-purity copper (Cu) (P. SPINDLER et al., ETALLURGICAL TRANSACTIONS A, June 1978, Vol. 9A, page 763), and is easily segregated on the surface ( I. N. SERGEEV et al., Bulletin of the Russian Academy of Sciences: Physics, October 2008, Vol. 72, No. 10, page 1388).

Note that high purity copper having a purity of 99.99 wt% (4N) or higher is “9” in a percentage ratio in which the purity of copper with respect to the entire metal component excluding gas components such as H, N, C, and O is expressed by weight. Means the number of four. Usually, since an expensive noble metal component is not contained in high-purity copper, the high-purity copper having a purity of 99.99 wt% or more refers to one having a total amount of base metal elements other than copper (Cu) of less than 100 mass ppm. In addition, the gas component is usually excluded from the definition of high-purity copper (Shoji Aoki et al., Journal of Copper and Copper Alloy, January 2003, Vol. 42, No. 1, page 21). On the other hand, if a gas component such as oxygen is present in the bonding wire at a high concentration, it is said that the FAB of the bonding wire is adversely affected.

For this reason, there are many patent applications in which gas components are controlled in high-purity copper. For example, in the specification of Japanese Patent Application Laid-Open No. 61-20893, “These additive elements fix H, O, N, and C in the alloy and generate H ₂ , O ₂ , N _2, and CO gas. (Suppressed) "(right top column, pages 12 to 14 of the same publication, page 2). Similarly, in Japanese Patent Application Laid-Open No. 2003-225705, the copper bonding wire Vickers hardness (Hv) is determined by measuring the Vickers hardness of the initial ball of a soft copper wire for each wire diameter, oxygen, carbon, nitrogen present in the copper material. Since there is a correlation with the amount of gas component of sulfur, “99.98% by weight or more of copper is used as a raw material, and the cross-sectional area is processed to be 0.01 mm ² or less. In the processing method of the soft copper material in which the total amount of oxygen, carbon, nitrogen and sulfur gas components present in the steel is 0.005% by weight or less, as the lubricating liquid used in the spreading step, the sum of the oil and the surfactant A processing method of a soft copper material characterized by employing an aqueous solution of 0.02% by weight or less in an amount ”is disclosed.

There are also applications that specify chlorine not included in high purity copper ingots of 4N or higher (Japanese Patent Laid-Open Nos. 2008-153625 and 2011-3745).

On the other hand, there are many patent applications in which nickel (Ni) is added as an additive element to a high purity copper-phosphorus alloy. For example, in claim (1) of Japanese Patent Laid-Open No. 61-20893, one or more elements selected from 24 elements (including one rare earth element) such as Ni, P, etc. 0.001 to 2% by weight, and the balance being substantially copper "is disclosed. Further, in claim (1) of JP-A-61-52333, one or more elements selected from seven “(first additive element group) such as silver (Ag)” are included. 0.001% by weight or more and less than 0.1% by weight, and one or more selected from “(second additive element group)” of 22 elements such as “Ni, Pd, Pt, Au, P” There is also disclosed a “bonding wire containing 0.001 to 2% by weight of an element and the balance being substantially copper” and “a bonding wire containing 2% by weight and the balance being substantially copper”.

Further, in claims 2 and 5 of JP 2010-171235 A (Patent Document 2 described later), “the addition of phosphorus (P) excludes phosphorus (P) from the room temperature hardness of the initial ball of the bonding wire. The purity is lower than that of a copper alloy of equivalent or higher, and the total amount of metal elements other than phosphorus is equal to or less than the content of phosphorus (P), and “other than phosphorus (P) in copper (Cu)” Copper for high-purity ball bonding, wherein the metal element is one or more of Pt, Au, Ag, Pd, Ca, Fe, Mn, Mg, Ni, Al, Pb and Si An “alloy wire” is disclosed.

Further, in claim (2) of Japanese Patent Laid-Open No. 01-290231 (Patent Document 3 to be described later), “High purity oxygen-free copper having a total content of S, Se and Te of 1.0 ppm or less is included. Further, at least 1.0 ppm of Si is added, and further 8 elements such as Ni, P, etc. are added, and one or more of them are added in a total amount of 1.0 to 500 ppm with Si. In Example 17 of the present invention, “alloy component and content (ppm) of Si: 132 Ni: 28 P: 76” was added to produce a copper alloy fine wire having a diameter of 25 μm. It is shown.

Prior art of high-purity copper and high-purity copper-phosphorus alloy related technology that controlled these gas components are low in material cost, excellent in ball joint shape, wire bondability, etc., and in loop formation. An object of the present invention is to provide a copper-based bonding wire for semiconductor elements that is excellent in mass productivity. However, simply having a phosphorous (P) enriched layer on the surface of the bonding wire makes the mechanical properties of the wire itself unstable with a thin bonding wire, causing the tail wire to bend or the tip of the wire to be Bending remains unresolved.

JP 2007-66991 A JP 2010-171235 A JP 2010-171235 A

The present invention has been made to solve the problem that the tail wire is bent in the capillary or the tip of the wire is bent when the wire is pulled up and cut after the second bonding. It is an object of the present invention to provide a copper alloy bonding wire in which a tail wire does not bend in a J shape by adding nickel (Ni) to a phosphorus alloy.

One of the copper alloy fine wires for ball bonding for solving the problems of the present invention is that nickel (Ni) is 0.02 mass% to 2 mass%, phosphorus (P) is 5 mass ppm to 800 mass ppm, The total amount of other base metal elements is less than 100 ppm by mass and the balance is copper (Cu).

One of the copper alloy fine wires for ball bonding for solving the problems of the present invention is that nickel (Ni) is 0.02 mass% or more and 2 mass% or less, and phosphorus (P) is 5 mass ppm or more and 800 mass ppm. Hereinafter, a palladium (Pd) stretched layer is coated on a copper alloy core material having a total amount of other base metal elements of less than 100 mass ppm and the balance copper (Cu).

One of the copper alloy fine wires for ball bonding for solving the problems of the present invention is that nickel (Ni) is 0.02 mass% or more and 2 mass% or less, and phosphorus (P) is 5 mass ppm or more and 800 mass ppm. In the following, the total amount of other base metal elements is less than 100 ppm by mass and the copper alloy core material composed of the remaining copper (Cu) is coated with a palladium (Pd) stretched layer and a gold (Au) thin stretched layer. .

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

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

In addition, one of the embodiments of the present invention is that any one of the three inventions of the copper alloy fine wire for ball bonding is 30% by mass when the nickel (Ni) content is 100% by mass. The above is substituted with palladium (Pd) or platinum (Pt).

Another aspect of the present invention is that, according to any of the three inventions of the copper alloy fine wire for ball bonding, 30 masses when the nickel (Ni) content is 100 mass%. % Is substituted with gold (Au) or silver (Ag).

In the present invention, the “stretched layer” and the “thin stretched layer” are generally assumed that the cross section of the bonding wire and the copper alloy core material are complete circles, and the palladium (Pd) layer is formed on the outer ring of the copper alloy core material. Or a theoretical layer calculated on the assumption that the palladium (Pd) layer and the gold (Au) layer are uniformly coated and reduced in diameter. Therefore, the expression of “stretched layer” and “thin stretched layer” is not necessarily an accurate representation of the actual surface morphology, but fine particles of palladium (Pd) and gold (Au) are formed from the surface of the bonding wire. The range in the depth direction detected by Auger analysis or the like is expressed as a “layer” having a thickness for convenience. Since the bonding wire of the present invention is extremely thin, if it is detected from the surface of the bonding wire by high frequency inductively coupled plasma optical emission spectrometry (ICP-AES), it is assumed that there are “stretched layer” and “thin stretched layer”. .

In the copper alloy fine wire for ball bonding of the present invention, oxygen is usually contained in the high purity copper alloy base material of 6N to 4N in an amount of 0.2 mass ppm to 50 mass ppm. These amounts of oxygen hardly change in the copper alloy composition of the present invention even if the copper alloy base material is remelted / cast, primary wire drawing, intermediate heat treatment, secondary wire drawing, final heat treatment, storage and the like. When oxygen is contained in the copper (Cu) matrix, the base metal element easily forms an oxide. Therefore, the oxygen content is preferably as low as 10 ppm by mass or less, more preferably 50 ppm by mass or less.

In the copper alloy fine wire for ball bonding of the present invention, the nickel (Ni) is 0.02 mass% or more and 2 mass% or less because the nickel (Ni) fixes oxygen contained in the copper alloy ingot, and This is because surface segregation of phosphorus (P) can also be prevented. A predetermined amount of nickel (Ni) in the copper alloy matrix is finely dispersed to fix oxygen in the matrix. Since oxygen fixed by nickel (Ni) is not subjected to deoxidation of phosphorus (P), the rigidity of the wire itself is increased. For this reason, a predetermined amount of nickel (Ni) increases the Young's modulus of the copper alloy.

The present inventors have found that a copper alloy fine wire having a high Young's modulus has a reduced cutting area at the tip end portion of the tail wire, and can obtain a tail wire in which the second back at the time of the second bonding is not easily bent. That is, it was found that the dynamic property of the bonding wire, which is the bending of the tail wire, is caused by the static property of the copper alloy thin wire, which is the Young's modulus.

In the copper alloy fine wire for ball bonding of the present invention, nickel (Ni) is bonded to oxygen atoms and prevents oxidation of the copper matrix. Nickel (Ni) combined with oxygen is fixed in a copper alloy matrix. In this case, if oxygen continues to be excessively supplied, it is observed as nickel oxide particles dispersed in the copper alloy matrix. Nickel (Ni) is also easily bonded to phosphorus (P) and prevents the movement of phosphorus (P) in the copper matrix. For this reason, moderate nickel (Ni) acts to increase the Young's modulus of copper (Cu).

If the lower limit amount of nickel (Ni) is less than 0.02% by mass, surface segregation of phosphorus (P) may not be prevented, and the cutting of the tip of the tail wire becomes unstable. Was set to 0.02% by mass or more. Preferably, the lower limit of nickel (Ni) is 0.04% by mass or more, and more preferably 0.06% by mass or more.

Further, if the upper limit of nickel (Ni) exceeds 2% by mass, oxidation from the bonding wire surface is accelerated, so the upper limit of nickel (Ni) is set to 2% by mass or less. Preferably, the upper limit of nickel (Ni) is 1% by mass or less. More preferably, the upper limit amount of nickel (Ni) is preferably 0.5% by mass or less, and more preferably 0.3% by mass or less.

In the copper alloy fine wire for ball bonding of the present invention, the phosphorus (P) content is 5 mass ppm or more and 800 mass ppm or less. Phosphorus (P) is an element that easily acts on copper (Cu) and oxygen to cause surface segregation. It is well known that phosphorus (P) exhibits a solder-like flux action on copper (Cu) and palladium (Pd) when present in percent order. Therefore, even if it exists in said range, it thinks that it acts on the surface of a molten ball and raises the joint strength with an aluminum pad. In addition, phosphorus (P) forms oxygen and volatile phosphate ions (PO ₄ ²⁻ ), and thus acts to release oxygen present in the copper alloy matrix from the molten ball to the atmosphere during FAB formation. . However, it was found that nickel (Ni) preferentially acts on oxygen in the copper alloy matrix over phosphorus (P).

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

In the copper alloy fine wire for ball bonding of the present invention, up to 30% by mass when the nickel (Ni) content is 100% by mass is replaced with palladium (Pd) or platinum (Pt). This is because palladium (Pd) or platinum (Pt) also exhibits the same effect as nickel (Ni) within this range. The content of expensive palladium (Pd) or platinum (Pt) is preferably up to 20% by mass of nickel (Ni), more preferably up to 10% by mass of nickel (Ni).

In addition, in the copper alloy thin wire for ball bonding of the present invention, up to 30% by mass when the nickel (Ni) content is 100% by mass is replaced with gold (Au) or silver (Ag). This is because if gold (Au) or silver (Ag) is also within this range, the same effect as nickel (Ni) is exhibited. The content of expensive gold (Au) or silver (Ag) is preferably up to 20% by mass of nickel (Ni), more preferably up to 10% by mass of nickel (Ni).

Moreover, in the copper alloy fine wire for ball bonding of the present invention, the total amount of other base metal elements is set to less than 100 mass ppm in order to prevent the formation of oxides of base metal elements in the copper alloy matrix. This is because when the oxide of the base metal element is formed at the crystal grain boundary of copper, the second back tail wire is easily deformed. Preferably it is 50 mass ppm or less, and if neglecting the metal price, it is preferably less than 10 mass ppm, more preferably 5 mass ppm or less. For example, if a copper ingot having a purity of 6N (99.9999 mass%) or more is used, the total amount of other metal elements is less than 1 ppm by mass, but the copper ingot is too expensive to be practical. This is not suitable. “Other base metal elements” refers to elements such as bismuth (Bi), selenium (Se), tellurium (Te), zinc (Zn), iron (Fe), nickel (Ni), tin (Sn), and the like. .

Moreover, gas components other than oxygen, such as normal hydrogen and chlorine, contained in a high purity copper alloy base material of 6N to 4N do not affect the Young's modulus of the copper alloy fine wire. For example, the amount of hydrogen contained in a 6N high-purity copper alloy base material is below the detection limit (0.2 mass ppm) of the analyzer. If hydrogen is present in the copper alloy, the hydrogen is combined with oxygen to form water vapor when the molten ball is formed, thereby destabilizing the molten ball. Hydrogen is occluded when hydrogen enters the hot metal from the wall of the melting crucible, or when hydrogen is entrained on the surface of the copper ingot when cooled rapidly in the heat treatment process, or when palladium (Pd) is coated by wet plating. Since hydrogen may remain, it is necessary to avoid such entrainment.

Further, in the copper alloy fine wire for ball bonding of the present invention, even if a palladium (Pd) stretched layer, or a palladium (Pd) stretched layer and a gold (Au) thin stretched layer are coated, these stretched layers are less than 100 nm. Since it is extremely thin, it hardly affects the Young's modulus of the copper alloy core material. A palladium (Pd) stretched layer of 20 nm or more and 60 nm or less has an effect of delaying oxidation of the copper alloy fine wire. In addition, when a thin gold (Au) stretched layer of 3 nm or less is coated, the wire itself generates heat following the surface current, so that the spark discharge of the palladium (Pd) stretched layer with poor current flow is stable. And has the effect of creating a uniform molten ball.

Note that the expression “stretched” layer and “thin stretched” layer are simply distinguished from the coating layer as it is after wet / dry plating. Even if the secondary wire is drawn to the final wire diameter and then a noble metal coating material such as palladium (Pd) or gold (Au) is coated, the object of the present invention cannot be achieved. This is because irregular longitudinal grooves due to die wear cannot be filled with the final coating layer, and the entire circumference of the wire cannot be covered on the nano level.

In order to form the ultrathin thin stretched layer of the present invention, although it depends on the kind of combination of the core material and the covering material, it is generally necessary to reduce the diameter of the wire by 90% or more. Note that both the ultrathin palladium (Pd) stretched layer and the gold (Au) thin stretched layer on the surface of the wire in the present invention disappear at the joining portion during the ultrasonic bonding of the second bonding, but remain on the tail wire.

According to the copper alloy fine wire for ball bonding having the composition range of the present invention, the second back at the time of the second bonding becomes difficult to bend, and there is an effect that the tail wire can be bent extremely less than the conventional one. Further, when the shape of the tail wire is stabilized, there is an effect that the FAB at the time of the first bonding does not become a deformed ball. Furthermore, when the shape of the tail wire is stabilized, a smaller sphere can be obtained with less heat energy at the time of the first bonding. Therefore, the wire diameter can be reduced from 20 μm to 15 μm, and there is an effect that high-density wiring of bonding wires can be achieved with small-diameter balls. Further, when the palladium (Pd) stretched layer and the gold (Au) thin stretched layer are coated on the nano level, the molten ball can be stably formed.

Moreover, according to the copper alloy fine wire for ball bonding of the present invention, since the base metal oxide is not dispersed in the copper matrix, the wire itself is soft. In addition, since the position of the spark discharge at the time of the first bonding is stabilized, even if the palladium (Pd) stretched layer, or the palladium (Pd) stretched layer and the gold (Au) thin stretched layer are coated thinner than before, the first This has the effect of stabilizing the FAB at the time of one joining.

Furthermore, in the copper alloy fine wire for ball bonding of the present invention, when a gold (Au) stretched layer is provided on the outermost surface of the wire, the wires do not stick to each other even if the wires are wound in multiple turns and wound by 10,000 meters. As a result, the wire unwinding property is improved. Further, as a concomitant effect, the slip of the wire surface with respect to the capillary is improved. Further, according to the copper alloy fine 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 stretched layer of palladium (Pd). Therefore, even if bonding is repeated many times, the oxide of copper (Cu) does not adhere to the capillary, so that the capillary is not contaminated.

The core material is copper (Cu) having a purity of 99.99998% by mass (5N), and phosphorus (P) and nickel (Ni) as well as palladium (Pd), platinum (Pt) gold (Au) and silver. (Ag) was used as an additive element. As the base metal element, an element generally contained in high-purity copper was selected. That is, bismuth (Bi), selenium (Se), tellurium (Te), zinc (Zn), iron (Fe), nickel (Ni) and tin (Sn) were appropriately selected. What blended these in the predetermined range was made into Examples 1-23.

Subsequently, this was continuously cast, and then a primary wire was drawn to obtain a thick wire (diameter 1.0 mm) before coating the stretched material. Next, an intermediate heat treatment (400 ° C. × 4 hours) was performed. Thereafter, a noble metal coating layer to be a gold (Au) thin stretched layer and a palladium (Pd) stretched layer was provided as necessary. These semi-finished wires were wet-drawn continuously with a diamond die and subjected to tempering heat treatment at 480 ° C. for 1 second to finally obtain a copper alloy fine wire for ball bonding having a diameter of 15 μm. The average diameter reduction rate is 6 to 20%, and the final drawing speed is 100 to 1000 m / min. Moreover, the purity of gold (Au) is 99.99 mass% or more, and the purity of palladium (Pd) is 99.9 mass% or more.

In Table 1, Examples 1 to 8 are examples according to Claim 1 of the present invention. Examples 15 and 16 are examples according to claim 2 of the present invention. The twenty-first embodiment is an embodiment according to claim 3 of the present invention. On the other hand, Examples 9, 10, 14, 17, 19, and 23 are examples according to claim 4 of the present invention. Examples 11 to 13, 18, 20, and 22 are examples according to claim 5 of the present invention.

(Bonding wire bending test, etc.)
The bending test of the bonding wire was performed as follows. That is, using a wire bonder (UTC-3000 manufactured by Shinkawa Co., Ltd.), 100 wedges were bonded to a silver (Ag) plated copper (Cu) plate at an ambient temperature of 25 ° C. under the conditions of an ultrasonic output of 100 mA and a bond load of 90 gf. Then, after the wedge bonding is finished, as shown in FIG. 1, the capillary (2) is raised, the bonding wire (1) is fed out to the tip of the capillary (2), and then the wire clamper (4) is closed. The capillary (2) and the wire clamper (4) are lifted together, and as shown in FIG. 3, the bonding wire (1) having a predetermined length is extended to the tip of the capillary (2). The wire was cut. This was performed 1,000 times, and the number of bendings of the bonding wire was examined with an enlargement projector. The measurement results are shown in the right column of Table 1. In addition, although Young's modulus was also measured, all showed a high value.

Comparative example

The bonding wires having the compositions shown in Table 1 were referred to as Comparative Examples 1, 2, and 3. The wires of Comparative Example 1 and Comparative Example 2 are out of the composition range of phosphorus (P) and nickel (Ni). The wire of Comparative Example 3 is out of the range of palladium (Pd) and gold (Au). When the bonding wires of these comparative examples 1 to 3 were subjected to a tail wire bending test in the same manner as in the example, the results in the right column of Table 1 were obtained.

As is clear from these test results, all the examples of the present invention showed high results with high Young's modulus and no bent wires in the tail wire bending test. On the other hand, the wires of Comparative Examples 1 to 3 were bent in the bending test.

The copper alloy thin wire for ball bonding of the present invention replaces the conventional gold alloy wire, in addition to general-purpose ICs, discrete ICs, and memory ICs, IC packages for LEDs that require low cost while being used in high temperature and high humidity, automotive semiconductors There are semiconductor applications such as IC packages.

It is sectional drawing of the bonding wire obtained by the wedge joining of the copper alloy fine wire of this invention. It is a perspective view which shows the wedge joining process of a copper alloy fine wire. It is typical sectional drawing which shows the cutting state immediately after wedge joining of a copper alloy fine wire. FIG. 3 is a schematic cross-sectional view of a bonding wire bent in a J shape.

1 Bonding wire 2 Capillary 3 Lead 4 Wire clamper

Claims (7)

Nickel (Ni) is 0.02 mass% or more and 2 mass% or less, phosphorus (P) is 5 mass ppm or more and 800 mass ppm or less, the total amount of other base metal elements is less than 100 mass ppm, and the balance is copper (Cu). A copper alloy fine wire for ball bonding. Copper made of nickel (Ni) of 0.02 mass% or more and 2 mass% or less, phosphorus (P) of 5 mass ppm or more and 800 mass ppm or less, the total amount of other base metal elements being less than 100 mass ppm and the balance copper (Cu) A copper alloy fine wire for ball bonding, wherein an alloy core material is covered with a palladium (Pd) drawn layer. Copper made of nickel (Ni) of 0.02 mass% or more and 2 mass% or less, phosphorus (P) of 5 mass ppm or more and 800 mass ppm or less, the total amount of other base metal elements being less than 100 mass ppm and the balance copper (Cu) A copper alloy fine wire for ball bonding, wherein an alloy core material is coated with a palladium (Pd) drawn layer and a gold (Au) thin drawn layer. The copper alloy fine wire for ball bonding according to any one of claims 1 to 3, wherein an upper limit of the nickel (Ni) is 1% by mass or less. The copper alloy fine wire for ball bonding according to any one of claims 1 to 3, wherein an upper limit of the phosphorus (P) is 200 ppm by mass or less. The palladium (Pd) or platinum (Pt) is substituted for up to 30% by mass when the nickel (Ni) content is 100% by mass, according to any one of claims 1 to 3. The copper alloy fine wire for ball bonding as described. 4. The method according to claim 1, wherein up to 30% by mass when the nickel (Ni) content is 100% by mass is replaced by gold (Au) or silver (Ag). The copper alloy fine wire for ball bonding as described.

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