KR20180101468A - Coated wire - Google Patents

Abstract

1. A wire comprising a wire core having a surface, the wire core having a coating layer superimposed on its surface, the wire core itself comprising:
(a) 0.1 to 0.3% by weight of silver,
(b) copper in an amount in the range of 99.64 to 99.9% by weight,
(c) an amount in the range of 0 to 100 ppm by weight, and
(d) additional components in an amount in the range of 0 to 500 ppm by weight (silver, copper and phosphorus and different components)
/ RTI >
The individual amounts of any additional components are less than 30 ppm by weight,
All amounts in wt.% And ppm by weight are based on the total weight of the core, and
The coating layer is a double-layer comprising an inner layer of palladium and an adjacent outer layer of gold,
The weight of the inner palladium layer is in the range of 1.5 to 2.5 wt.%, As compared to the weight of the wire core, and
Wherein the weight of the outer gold layer is within a range of 0.09 to 0.18 weight%, as compared to the weight of the wire core.

Description

Coated wire

The present invention relates to a coated wire comprising a copper-based core and a coating layer superimposed on the surface of the core. The invention also relates to a process for making such a coated wire.

The use of bonding wires in electronic and microelectronic applications is well known prior art. While bonding wires were initially made of gold, less expensive materials are nowadays used, such as copper, copper alloys, silver and silver alloys. Such wires may be provided with a metal coating.

For wire geometry, the most common are bonding rods having circular cross-section bonding wires and substantially rectangular cross-sections. Both types of wire geometry have their advantages in making them useful for a particular application.

It is an object of the present invention to provide a coated copper alloy wire suitable for use in wire bonding applications wherein the wire is in particular a free air ball (FAB), corrosion resistant, OCB (off center ball) But also exhibits a generally well balanced characteristic spectrum related to the bonding applications of wires and wires including, for example, the distribution of coating materials in FAB and the like. will be.

Contributions to the above objective solution are provided by the objects of the category formation claims. Dependent sub-claims of the category-forming claims denote preferred embodiments of the invention, the object of which also contributes to addressing the objects mentioned above.

In a first aspect, the present invention provides a wire comprising a wire core having a surface (hereinafter also referred to as a short term "core"), the wire core having a coating layer superimposed on its surface, The core itself is:

(a) 0.1 to 0.3% by weight, preferably 0.2% by weight, of a positive silver,

(b) copper in an amount in the range of 99.64 to 99.9 wt.%, preferably 99.7 to 99.9 wt.%, or even more preferably 99.75 to 99.85 wt.%,

(c) from 0 to 100 ppm by weight, preferably from 50 to 100 ppm by weight, more preferably from 70 to 80 ppm by weight, in particular in an amount of 75 ppm by weight, and

(d) 0 to 500 ppm by weight, preferably 0 to 100 ppm by weight, of additional components in an amount (silver, copper and phosphorous and different components)

/ RTI >

The individual amounts of any additional components are less than 30 ppm by weight,

All amounts in wt.% And ppm by weight are based on the total weight of the core, and

The coating layer is a double-layer comprising an inner layer (lower layer) of palladium and an adjacent outer layer (upper layer) of gold,

The weight of the inner palladium layer is in the range of 1.5 to 2.5 wt.%, As compared to the weight of the wire core, and

Wherein the weight of the outer gold layer is in the range of 0.09 to 0.18 weight%, as compared to the weight of the wire core.

The following table lists some preferred embodiments for the composition of the wire core:

The wire of the present invention is preferably a bonding wire for bonding in microelectronics. This is preferably a single piece object. Numerous shapes are known and useful for the wires of the present invention. Preferred shapes are circular, oval and rectangular in cross-section. For the purposes of the invention, the term "bonding wire" includes all shapes of cross-sections and all available wire diameters, although bonding wires having circular cross-section and thin diameters are preferred. The average cross-sectional area is, for example, within the range of 50 to 5024 占 퐉 ² or preferably 113 to 2375 占 퐉 ² ; Accordingly, in the case of the preferred circular cross section, the average diameter is, for example, in the range of 8 to 80 占 퐉 or preferably in the range of 12 to 55 占 퐉.

The average diameter of the wire or wire core or, simply stated, the diameter can be achieved by a "sizing method ". According to this method, the physical weight of the wire for a defined length is determined. Based on this weight, the diameter of the wire or wire core is calculated using the density of the wire material. The diameter is calculated as the arithmetic mean of the five measurements for the five segments of a particular wire.

As described above, the wire cores include (a), (b) copper and (c) phosphorus in the proportions described above. However, the silver alloyed copper core of the coated wire of the present invention may comprise (d) 0 to 500 ppm by weight, preferably 0 to 100 ppm by weight, of additional components. In the context presented, additional components, also referred to as "inevitable impurities," are chemical elements and / or compounds that originate from the impurities present in the raw materials used or from the wire making process, , the presence of additional components of type (d) is derived, for example, from impurities which are inherent in silver and / or copper. Examples of such additional components are Au, Ni, Pd, Pt, Fe, Si, Mn, Cr, Ce, Mg, La, Al, B, Zr, Ti, A low total amount of 0 to 500 ppm by weight or even 0 to 100 ppm by weight of additional components (d) ensures excellent reproducibility of the wire properties. The additional components (d) present in the core are generally not added separately. Each individual additional component is included in an amount less than 30 weight ppm based on the total weight of the wire core.

The core of the wire is a homogeneous region of the bulk material. The properties of the core of the wire are understood as properties of the homogeneous region of the bulk material, since any bulk material can always have surface areas that can exhibit different properties to some extent. The surface of the bulk material region may be different in terms of morphology, composition (e.g., sulfur, chlorine and / or oxygen content) and other characteristics. The surface is the interface region between the wire core and the coating layer superimposed on the wire core. Typically, the coating layer is completely superimposed on the surface of the wire core. In the region of the wire between the wire core and the overlying coating layer, there may be a combination of materials of both the core and the coating layer.

The coating layer superimposed on the surface of the wire is a double-layer comprising an inner layer of palladium and an adjacent outer layer of gold. The weight of the inner palladium layer is in the range of 1.5 to 2.5 weight% compared to the weight of the wire core and the weight of the outer gold layer is in the range of 0.09 to 0.18 weight% . Both the inner palladium layer as well as the outer gold layer are thin layers. In this context, the term "thin "," thick ", or "coating layer thickness" means the size of the coating layer in a direction perpendicular to the longitudinal axis of the core. For circular wires having an average cross-sectional area within the above exemplary range of 50 to 5024 占 퐉 ² , or for circular wires having an average diameter in the above-mentioned exemplary range of 8 to 80 占 퐉, the inner palladium layer may, For example, the thickness of the outer gold layer may be in the range of 1 to 25 nm, preferably in the range of 2 to 20 nm, and may have a thickness in the range of 20 to 350 nm, preferably 30 to 340 nm. There will be. In an exemplary embodiment of a circular wire having a diameter of 18 占 퐉, the inner palladium layer may have a thickness in the range of, for example, 60 to 90 nm, and the thickness of the outer gold layer may be, for example, 1 To 10 nm, preferably from 2 to 6 nm.

With respect to the composition of the double-layer, the palladium content of the inner layer of the double-layer is at least 50% by weight, preferably at least 95% by weight, based on, for example, the total weight of the inner coating layer. Particularly preferably, the inner coating layer is made of pure palladium. Pure palladium generally has less than 1% by weight of additional components (different components from palladium), based on the total weight of the inner coating layer. The gold content of the adjacent outer gold layer is, for example, at least 50 wt%, preferably at least 95 wt%, based on the total weight of the outer coating layer. Particularly preferably, the outer coating layer is made of pure gold. Pure gold generally has less than 1% by weight of additional components (gold and different components), based on the total weight of the outer coating layer.

In an embodiment, the core of the wire of the present invention is characterized by at least one of the following inherent characteristics (i) to (iii) (see "Test Method A "

(i) an average wire particle size (average particle size) measured in the longitudinal direction (the end direction of the wire core) is 3 to 6 mu m,

(ii) the ratio of the average particle size measured in the longitudinal direction to the diameter of the wire core is in the range of 0.05 to 0.25, preferably 0.1 to 0.20,

(iii) The standard deviation ratio (RSD) of the average particle size to the average particle size of the core measured in the longitudinal direction is within the range of 0.1 to 0.4.

The term "inherent properties" is used herein in connection with wire cores. Intrinsic properties refer to properties of the wire core itself (regardless of other factors). The extrinsic properties, as opposed to the intrinsic properties, depend on the relationship of the wire cores to the other factors, such as the measurement conditions and / or the measurement method used.

In another aspect, the present invention also relates to a process for the production of the coated wire of the present invention in any of the embodiments disclosed below. The process comprises at least the following steps (1) to (5):

(1) providing a precursor body of the desired composition, namely

(a) 0.1 to 0.3% by weight, preferably 0.2% by weight, of a positive silver,

(b) copper in an amount in the range of 99.64 to 99.9 wt.%, preferably 99.7 to 99.9 wt.%, or even more preferably 99.75 to 99.85 wt.%,

(c) from 0 to 100 ppm by weight, preferably from 50 to 100 ppm by weight, more preferably from 70 to 80 ppm by weight, in particular in an amount of 75 ppm by weight, and

(d) an additional component (silver, copper and phosphorus and different components) in an amount in the range of 0 to 500 ppm by weight, preferably 0 to 100 ppm by weight,

The individual amounts of any additional components are less than 30 ppm by weight,

Wherein all amounts in wt.% And ppm by weight are based on the total weight of the precursor body;

(2) stretching the precursor object to form an elongated precursor body until an intermediate cross-sectional area in the range of 5024 to 70650 占 퐉 ² and a median diameter in the range of 80 to 300 占 퐉, preferably in the range of 130 to 230 占 퐉, ,

(3) depositing a double-layer coating of an inner layer (lower layer) of palladium and an adjacent outer layer (upper layer) of gold on the surface of the elongated precursor body obtained after completion of process step (2) ,

(4) further elongating the coated precursor article obtained after completion of process step (3) until the required final cross-sectional area or diameter is achieved, and

(5) The coated precursor obtained after the completion of process step (4) is heated at an oven set temperature in the range of 450 to 650 占 폚 for an exposure time within the range of 0.1 to 3 seconds to finally form the coated wire, Strand annealing.

The term "strand annealing" is used herein. As opposed to "batch annealing ", which is a continuous process that allows high-speed production of wire with high reproducibility. In the context of the present invention, strand annealing is performed dynamically while the annealed is rolled on a reel after the coated precursor to be annealed is pulled or moved through a conventional annealing oven and leaves the annealing oven . Here, the annealing oven is typically in the form of a cylindrical tube of a given length. Annealing time / oven temperature parameters, along with their specified temperature profile at a given annealing speed, which can be selected, for example, in the range of 10 to 60 meters / minute, can be specified and set.

The term "oven set temperature" is used herein. This means the temperature which is fixed in the temperature controller of the annealing oven.

The annealing oven may be a chamber furnace type oven (in the case of batch annealing) or a tubular annealing oven (in the case of strand annealing).

This disclosure distinguishes between precursor objects, elongated precursor objects, coated precursor objects, coated precursors, and coated wires. The term "precursor" is used to refer to a wire dictionary at the desired final cross-sectional area or required final diameter, while the term "precursor article" is used for such pre-wire steps that do not reach the desired final cross-sectional area or final diameter of the wire core. Step. After completion of process step (5), i.e. after the final cross-sectional area required or the final strand anneal of the coated precursor at the required final diameter, a coated wire in the sense of the present invention is obtained.

A precursor body as provided in process step (1) can be obtained by alloying / doping copper with the required amount of silver, and optionally, but preferably also in an appropriate amount of phosphorus. The copper alloy itself may be prepared by conventional processes known to those skilled in the art of metal alloys, for example by melting together the required proportions of copper, silver, and optional phosphorous. By doing so, it is possible to use a master alloy. The melting process can be carried out, for example, using an induction furnace, and it is appropriate to work under vacuum or under an inert gas atmosphere. The materials used may, for example, have a purity rating of 99.99% by weight and higher. The melt thus produced can be cooled to form a homogeneous piece of the copper-based precursor body. Typically, such a precursor article is in the form of a rod having a diameter of, for example, 2 to 25 mm and a length of, for example, 2 to 100 m. Such a rod can be made by casting the copper alloy melt in a suitable mold followed by cooling and solidifying.

In process step (2), the precursor object is stretched to form a stretched precursor object, preferably a stretched precursor object, until an intermediate cross-sectional area in the range of 5024 to 70650 占 퐉 ² and a median diameter in the range of 80 to 300 占 퐉, preferably 130 to 230 占 퐉, Lt; / RTI > Techniques for elongating precursor objects are known, and are useful in the context of the present invention. The preferred techniques are rolling, swaging, die drawing or the like, of which die drawing is particularly preferred.

In the latter case, the precursor object is drawn at various process steps until the desired intermediate cross-sectional area or required intermediate diameter is reached. Such wire die drawing processes are well known to those skilled in the art. Conventional tungsten carbide and diamond drawing dies may be used and conventional draw lubricants may be used to support the draw.

Step (2) of the process of the present invention may include one or more sub-steps for intermediate annealing of the elongated precursor object. Such intermediate annealing may be performed, for example, for an exposure time of 0.5 to 1 second, for example at an oven set temperature within the range of 200 to 650 ° C. Such intermediate annealing is generally carried out by a strand annealing method.

In process step (3), a double-layer coating comprising an inner layer of palladium and an adjacent outer layer of gold is formed on the surface of an elongated precursor body obtained after the end of process step (2) As shown in Fig. Those skilled in the art will appreciate that the inner palladium layer and the outer gold layer are formed so that the weight of the inner palladium layer is in the range of 1.5 to 2.5 weight percent as compared to the weight of the elongated precursor body and that the weight of the outer gold layer is the weight of the elongated precursor body Is in the range of 0.09 to 0.18 wt.%, Relative to the weight.

Those skilled in the art know how to calculate the thickness of such a coating on an elongated precursor object, in order to finally obtain a coating of the layer thickness disclosed for the embodiments of the wire, after finally stretching the coated precursor object . Those skilled in the art know a number of techniques for forming a coating layer of a material according to embodiments on a copper alloy surface. Preferred techniques are deposition of gas phase materials such as electroplating and electroless plating, plating, sputtering, ion plating, vacuum deposition and physical vapor deposition, and deposition of molten material. In the context of the present invention, electroplating is the preferred technique.

In process step (4), the coated precursor object obtained after completion of process step (3) is further elongated until the desired final cross-sectional area or diameter of the wire is achieved. Techniques for stretching a coated precursor article are the same stretching techniques, such as those mentioned above with respect to the initiation of process step (2).

In process step (5), the coated precursor obtained after completion of process step (4) is heated at an oven set temperature in the range of 450 to 650 占 폚 for an exposure time of, for example, 0.3 to 1 second, At 500 to < RTI ID = 0.0 > 600 C < / RTI > for 0.3 to 1 second. In an exemplary embodiment, especially in an exemplary embodiment of a wire having a diameter of about 18 占 퐉, the final strand anneal may be performed at an oven set temperature of 530 占 폚 for an exposure time of 0.8 seconds.

In a preferred embodiment, the finally annealed coated precursor, i.e. still hot coated wire, in one embodiment, contains one or more additives such as, for example, from 0 to 1000 ppm by weight of the additive (s) It is quenched in water. Quenching in water can be accomplished either immediately or rapidly, i.e., within 0.2 to 0.6 seconds, by final dipping or dripping of the coated, annealed, precursor in process step 5 Means cooling from the experienced temperature to room temperature.

The optional sub-step intermediate annealing of process step (2), as well as the final strand annealing of process step (5), may be performed in an inert or reducing atmosphere. Numerous types of inert atmospheres as well as reducing atmospheres are known in the art and are used to clean the annealing oven. Of the known inert environments, nitrogen or argon is preferred. Of the known reduction atmospheres, hydrogen is preferred. Another preferred reducing atmosphere is a mixture of hydrogen and nitrogen. A preferred mixture of hydrogen and nitrogen is 90 to 98% by volume of nitrogen and accordingly 2 to 10% by volume of hydrogen, wherein the volume% is a total of 100% by volume. The preferred mixture of nitrogen / hydrogen is 93/7, 95/5 and 97/3% by volume / volume%, respectively, based on the total volume of the mixture.

The inert or reducing gas purging of these types is preferably carried out in a range of 10 to 125 min ^-1 , more preferably in the range of 15 to 90 min ^-1 , most preferably in the range of 20 to 50 min ^-1 , Gas exchange rate (= gas flow rate [liter / min]: inner oven volume [liter]).

After completion of process step (5) and optional quenching, the coated wire of the present invention is completed. In order to fully benefit from its properties, it is appropriate to use immediately for wire bonding applications, i.e. without delay, within a settling time of 60 days, for example after completion of the process step (5). Alternatively, to maintain the broad wire bonding process window characteristics of the wire and to protect the wire from oxidation or other chemical attack, the finished wire is typically immediately after the completion of the process step (5), i.e. without delay For example less than 1 hour to 5 hours after completion of the process step 5, is wound and vacuum sealed, and then stored for further use as a bonding wire. Storage in vacuum sealed condition shall not exceed 6 months. After opening the vacuum seal, the wire must be used for wire bonding within 60 days.

It is preferred that both process steps (1) - (5) as well as cold and vacuum sealing be performed under clean room conditions (US FED STD 209E Cleanroom Standards, 1k standard).

A third aspect of the present invention is a coated wire obtainable by the process as described above according to any of the embodiments of the present invention. The coated wire of the present invention has been found to be well suited for use as a bonding wire in wire bonding applications. Wire bonding techniques are well known to those skilled in the art. In the course of the wire bonding, ball bonding (first bonding) and stitch bonding (second bonding, wedge bonding) are formed. During bonding formation, a certain force (typically, the maximum force) is applied by application of scrub amplitude (typically measured in micrometers) or supported by application of ultrasonic energy (typically measured in mA) Measured in grams) is applied. A mathematical multiplication of the difference between the upper and lower limits of the applied force and the difference between the upper and lower limits of the applied rubbing amplitude in the wire bonding process or the difference between the upper and lower limits of the applied force and the upper limit of the applied ultrasonic energy The mathematical multiplication of the difference between the lower bounds defines the wire bonding process window:

(Upper limit of force applied - lower limit of applied force) · (upper limit of applied rubbing amplitude - lower limit of applied rubbing amplitude) = wire bonding process window.

or

(Upper limit of applied force - lower limit of applied force) · (upper limit of applied ultrasonic energy - lower limit of applied ultrasonic energy) = wire bonding process window.

The wirebonding process window has a wire bonding process window that meets specifications, i.e. passes through conventional tests, such as a conventional tensile test, a ball shear test and a ball pull test, to name just a few. / RTI > combinations of force / rubbing amplitude combinations or forces / ultrasonic energy combinations that allow for the formation of a plurality of force / ultrasonic energy combinations.

In other words, the first junction (ball junction) process window region is the product of the difference between the upper and lower limits of the force used in the bonding and the difference between the upper and lower limits of the applied rubbing amplitude, and the product of the difference between the ultrasonic energy applied to the difference, and between the power upper and lower limits upper and lower limits, the bonding which is the result is the specific ball shear test specifications, for example, to view the front end of 0.0085 g / ㎛ ² (Stitch bonding) process window region must satisfy the difference between the upper and lower limits of the force used for bonding and the upper and lower limits of the applied rubbing amplitude, while the second bonding (stitch bonding) process window region must satisfy Or the difference between the upper and lower limits of the force used in the bonding and the difference between the upper and lower limits of the applied ultrasonic energy, Junction, a particular tensile test specifications, for example, must satisfy, such as the tensile force of 2.5g, eopji No tackiness on the lead.

For industrial applications, it is desirable to have a broad wire bonding process window (rubbing amplitude in grams per millimeter or ultrasound energy in grams of force per mA) for reasons of wire bonding process robustness. The wire of the present invention exhibits a fairly wide wire bonding process window.

The following non-limiting examples illustrate the present invention. These examples serve as illustrative explanations of the present invention and are not intended to limit the scope of the present invention or the claims in any way.

Examples

Preparation of airless ball (FAB):

According to the procedure described in the KNS process user guide for FAB [Kulicke & Soffa Industries Inc., Fort Washington, PA, USA, 2002, May 31, 2009] . FAB is a conventional electrical flame-off by standard firing (single stage, 17.8 탆 wire, 50 mA EFO current, EFO time 200 μs under 95 vol% nitrogen / 5 vol% hydrogen atmosphere) : EFO).

Test Methods A. to F.

All tests and measurements were performed at T = 20 ° C and RH = 50%.

A. Linear Intercept Method

The wires were first filled with cold-mounted epoxy resin and then polished (cross-section-treated) by standard metallographic techniques. A multi-prep semi-automatic polishing machine was used with low force and optimum speed to grind and grind samples with minimal deformation strain on the sample surface. Finally, the polished samples were chemically etched using ferric chloride to expose the grain boundaries. The average particle size was measured using a linear slicing method under an optical microscope with a magnification of 1000 according to ASTM E112-12 standard.

B. FAB type

The formed FAB was examined by a scanning electron microscope (SEM) with a magnification of 1000.

evaluation:

++, very good (round ball)

+, Excellent (round ball);

0, acceptable (not perfectly round, but with no flat parts on the FAB surface);

-, peach balls

-, serious peach balls

As used herein, the term "peach ball" refers to the formation of two flat portions with a pronounced hemisphere at the end of the FAB.

C. Shaped Ball Shape

The formed FAB was lowered to an Al-0.5 wt% Cu bonding pad from a predefined height (tip of 203.2 mu m) and speed (contact speed of 6.4 mu m / sec). Upon contact with the bonding pads, a set of defined bonding parameters (100 g of bonding force, 95 mA of ultrasonic energy and 15 ms of bonding time) influenced the FAB to deform and form a bonded ball . After forming the ball, the capillary rose to a predefined height (kink height of 152.4 mu m and loop height of 254 mu m) to form a loop. After forming the loop, the capillary was lowered to a lead to form a stitch. After forming the stitches, the capillaries were raised and the wire clamps were closed to cut the wires to create a predefined tail length (tail length extension of 254 [mu] m). For each sample, five bonded wires were optically inspected using a microscope with a magnification of 1000.

evaluation:

+, Circle;

0, acceptable;

-, flower shape.

D. Off-center ball (OCB)

The same method as described in Method C was applied, but instead of examining the roundness of the ball, the centricity of the ball was determined. For each sample, five bonded wires were optically inspected.

evaluation:

++, perfectly centered;

+, Centered;

0, tolerably eccentric;

- eccentric;

- Very eccentric.

E. Distribution of Pd on FAB

FAB was first embedded with cold-mounted epoxy and cross-processed by standard metallographic techniques. A multi-prep semi-automatic polishing machine was used with low force and optimum speed to grind and grind samples with minimal deformation strain on the sample surface. Finally, the polished samples were examined under a high power microscope with a magnification of 1000. For each sample, 5 FABs were optically inspected.

Visual evaluation:

++, Pd covers the FAB sheath very uniformly with a Pd coverage of 80% or more of the FAB height;

+, Pd covers the FAB sheath evenly with a Pd coverage of 70% or more of the FAB height;

0, Pd partially covers the FAB sheath to have a Pd coverage between 50 and 70% of the FAB height, and partially diffuses into the ball;

- most of the diffusion of Pd into the ball, along with the formation of a Cu-Pd alloy, to have a Pd coverage of less than 50% of the FAB height;

- Most of the Pd diffusion into the ball, along with the formation of a Cu-Pd alloy, to have a Pd coverage of less than 30% of the FAB height.

F. Corrosion resistance:

The wires were ball bonded to Al-0.5 wt% Cu bonding pads. The test devices with the thus bonded wires were stored in a highly accelerated stress test (HAST) chamber at a temperature of 130 DEG C, 85% relative humidity (RH) for 96 hours, Were inspected for the number of lifted balls under a low power microscope (Nikon MM-40) at 100X magnification. Observation of a greater number of lifted balls indicated severe intergalactic corrosion. An evaluation was made in terms of ranking:

++, least lifted balls;

+, Less lifted balls;

0, medium lifted balls;

-, a lot of lifted balls;

- the most lifted balls;

Example 1: wire  Samples 1 to 8

Certain amounts of copper, silver and phosphorus of at least 99.99% purity ("4N") were melted in a crucible in a vacuum oven at about 1200 ° C. The wire core precursor body in the form of 8 mm rods was then cast continuously from the melt. The rods were then drawn at various drawing steps to form a wire core precursor with a circular cross section with a diameter of 200 mu m. The wire core precursor was electroplated to have a double layer coating consisting of an inner palladium layer 840 nm thick and an outer gold layer 45 nm thick and then a final palladium coating layer thickness of 75 nm and a final gold coating layer of 4 nm Followed by final strand annealing at an oven set temperature of 530 DEG C for an exposure time of 0.8 seconds followed immediately by the coated wires thus obtained with 500 ppm by weight of surfactant < RTI ID = 0.0 > ≪ / RTI > in water.

By this procedure, several different inventive samples and comparative samples 1 to 9 of palladium and gold coated copper-based wires were prepared. Table 1 shows the composition of the wire cores.

Sample: Wire core composition: 1 (comparative example) 75 weight ppm P doped < RTI ID = 0.0 > Cu & 2 (invention) 0.0 > Cu < / RTI > doped with < RTI ID = 0.0 & 3 (invention) 0.2 wt% Cu alloyed with Ag and not doped with P 4 (invention) 0.2 wt% Cu alloyed with Ag and doped with 40 wt ppm P 5 (invention) 0.2 wt% Cu alloyed with Ag and doped with 75 wt ppm P 6 (invention) 0.3 wt% Cu alloyed with Ag and doped with 75 wt ppm of P 7 (comparative example) 0.4 wt% Cu alloyed with Ag and doped with 75 wt ppm of P 8 (comparative example) 0.5 wt% Cu alloyed with Ag and doped with 75 wt ppm of P

Yes 2: wire  Samples 9 to 10

The wire samples were processed similar to Sample 5 of Example 1, but the layer thicknesses of the inner palladium coating and the outer gold coating were changed as noted in Table 2.

Sample Inside Palladium Layer Thickness (nm) Outer gold layer thickness (nm) 9 (invention) 75 2.3 10 (invention) 68 2.3

Table 3 below shows specific test results.

Sample: One 2 3 4 5 6 7 8 9 10 FAB type + 0 - - 0 - - - 0 + Bonded ball shape + + + + + + + + + + OCB + + + + + - - - - - Pd distribution on FAB - - + + + + ++ ++ + 0 Corrosion resistance - 0 + + + + ++ ++ + 0

Claims (14)

1. A wire comprising a wire core having a surface, the wire core having a coating layer superimposed on its surface, the wire core itself comprising:
(a) 0.1 to 0.3% by weight of silver,
(b) copper in an amount in the range of 99.64 to 99.9% by weight,
(c) an amount in the range of 0 to 100 ppm by weight, and
(d) an amount of additional components in the range of 0 to 500 ppm by weight (silver, copper and phosphorus and different components)
/ RTI >
The individual amounts of any additional components are less than 30 ppm by weight,
All amounts in wt.% And ppm by weight are based on the total weight of the core, and
The coating layer is a double-layer comprising an inner layer of palladium and an adjacent outer layer of gold,
The weight of the inner palladium layer is in the range of 1.5 to 2.5 wt.%, As compared to the weight of the wire core, and
Wherein the weight of the outer gold layer is within a range of 0.09 to 0.18 weight%, as compared to the weight of the wire core. The method according to claim 1,
And the amount of silver is 0.2 wt%. 3. The method according to claim 1 or 2,
Wherein the amount of phosphorus is 50 to 100, or 70 to 80 weight ppm. 4. The method according to any one of claims 1 to 3,
Wherein the amount of additional components is from 0 to 100 weight ppm. 5. The method according to any one of claims 1 to 4,
And an average cross-sectional area in the range of 50 to 5024 占 퐉 ² . 6. The method according to any one of claims 1 to 5,
And a circular cross section having an average diameter in the range of 8 to 80 mu m. 7. The method according to any one of claims 1 to 6,
Wherein the wire core is characterized by at least one of the following inherent characteristics:
(i) the average wire particle size, measured in the longitudinal direction, is from 3 to 6 [mu] m,
(ii) the ratio of the average particle size measured in the longitudinal direction to the diameter of the wire core is in the range of 0.05 to 0.25, preferably 0.1 to 0.20,
(iii) The standard deviation ratio (RSD) of the average particle size to the average particle size of the core measured in the longitudinal direction is within the range of 0.1 to 0.4. A process for producing a coated wire according to any one of claims 1 to 7, comprising at least the following steps (1) to (5):
(1) providing a precursor body of the desired composition,
(2) stretching the precursor body to form an elongated precursor body until an intermediate cross-sectional area in the range of 5024 to 70650 占 퐉 ² and an intermediate diameter in the range of 80 to 300 占 퐉 are achieved,
(3) depositing a double-layer coating of an inner layer of palladium and an adjacent outer layer of gold on the surface of an elongated precursor body obtained after completion of process step (2), wherein the weight of the inner palladium layer Is in the range of from 1.5 to 2.5% by weight relative to the weight of the elongated precursor body and so that the weight of the outer gold layer is in the range of 0.09 to 0.18% by weight relative to the weight of the elongated precursor body. Depositing a coating,
(4) further elongating the coated precursor article obtained after completion of process step (3) until the required final cross-sectional area or diameter is achieved, and
(5) The coated precursor obtained after the completion of process step (4) is heated at an oven set temperature in the range of 450 to 650 占 폚 for an exposure time within the range of 0.1 to 3 seconds to finally form the coated wire, Strand annealing. 9. The method of claim 8,
Wherein step (2) comprises at least one sub-step for intermediate annealing of the elongated precursor body. 10. The method according to claim 8 or 9,
Wherein the final strand anneal is performed at an oven set temperature of 500 to 600 DEG C for an exposure time of 0.3 to 1 second. 11. The method according to any one of claims 8 to 10,
Wherein the final annealed coated strand precursor is quenched in water that may contain one or more additives. The method according to any one of claims 8 to 11,
Wherein the final strand annealing of process step (5) is performed under an inert or reducing atmosphere. As a coated wire,
A coated wire obtained by the manufacturing process of any one of claims 8 to 12. 13. Use of a coated wire obtained by a manufacturing process according to any one of claims 1 to 7 or 8 to 12,
Use of coated wire as a bonding wire in wire bonding applications.