Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
  • H01B13/0016—Apparatus or processes specially adapted for manufacturing conductors or cables for heat treatment
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
  • B21B1/16—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling wire rods, bars, merchant bars, rounds wire or material of like small cross-section
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B27/00—Rolls, roll alloys or roll fabrication; Lubricating, cooling or heating rolls while in use
  • B21B27/02—Shape or construction of rolls
  • B21B27/03—Sleeved rolls
  • B21B27/035—Rolls for bars, rods, rounds, tubes, wire or the like
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21H—MAKING PARTICULAR METAL OBJECTS BY ROLLING, e.g. SCREWS, WHEELS, RINGS, BARRELS, BALLS
  • B21H8/00—Rolling metal of indefinite length in repetitive shapes specially designed for the manufacture of particular objects, e.g. checkered sheets
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
  • B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
  • B21J5/06—Methods for forging, hammering, or pressing; Special equipment or accessories therefor for performing particular operations
  • B21J5/12—Forming profiles on internal or external surfaces
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/08—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of copper or alloys based thereon
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
  • H01B1/02—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of metals or alloys
  • H01B1/026—Alloys based on copper
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
  • H01B13/0006—Apparatus or processes specially adapted for manufacturing conductors or cables for reducing the size of conductors or cables
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
  • H01B13/0009—Apparatus or processes specially adapted for manufacturing conductors or cables for forming corrugations on conductors or cables

Definitions

• the invention relates to a method for producing a wire, including at least the following steps: (i) providing a wire precursor; (ii) imprinting indentations on the wire precursor and optionally deforming the wire precursor in the process; and (iii) annealing the dimpled wire precursor into wire; wherein the wire has a proportion of at least 95% by weight copper, the proportion based on the total weight of the wire.
• the invention further relates to a wire that can be obtained by the method mentioned and to the use of a roller for producing the wire and/or for adjusting the roughness at at least one point on the wire.
• Bond wires are used in the manufacture of semiconductor devices to electrically connect an integrated circuit and a printed circuit board together during the manufacture of semiconductor devices.
• bonding wires are used in power electronics to electrically connect transistors, diodes and the like to the contact surfaces of the housing, also known as pads or pins. While bonding wires used to be made of gold, cheaper materials such as copper are now used. Copper wire has very good electrical and thermal conductivity. However, copper wires are prone to oxidation.
• a special interest applies to the so-called laser bonding. This is a process in which the energy required for bonding is transferred to the bonding wire using laser beams.
• Metal ribbons are often used here instead of wires, since the ribbon offers a larger surface for coupling the laser.
• An advantage of bonding ribbons is that they are easy to position and hold compared to round wires. This increases the reliability of the bonding considerably. Due to the larger connection when bonding ribbons, higher currents can be carried via such connections. nothing- nevertheless, there is a constant need for further improvement of the technology with regard to the bonding wire itself and the bonding processes.
• overlapping of wire material can occur.
• these overlaps can cause the wire material to spatter as a result of the strong heating and sudden expansion of the air volume enclosed underneath.
• the spatter of the wire material can lead to an unreliable bonding result due to the loss of material on the one hand and to harmful contamination of other electronic components on the other.
• chemical methods have the disadvantage that the dimensions of the depressions are more difficult to adjust in terms of their depth and localization. For example, one-sided etching of a ribbon can only be accomplished with complex masking steps. The introduction of patterns in depressions can only be accomplished with increased effort.
• a further object of the invention is to specify a method by means of which a wire can be produced whose at least one surface has a defined roughness.
• a further object of the invention is a method for producing a wire whose wire surface absorbs as much as possible the portion of incident laser radiation during laser bonding.
• Another object of the invention is a method of making a wire which heats up more than other bonding wires for the same intensity of incident laser light.
• Another object of the invention is a method of manufacturing a wire wherein no impurities or residues are formed during laser bonding.
• a further object is to simplify the production process for manufacturing the bonding wires according to the invention, for example by reducing the required steps.
• bonding wires for so-called laser bonding, which are roughened on a side facing away from the electrical contact surface. It was observed that with the same emitted laser radiation, a higher energy transfer to the bonding wire takes place with roughened bonding wires than with smooth bonding wires. Without being bound to a theory, it is assumed that the incident laser radiation is absorbed to a higher degree by the bonding wire as a result of the roughened side, or that less laser radiation is reflected. Nevertheless, there is still a need for improvement in order to further increase the quality and reliability of the bonded connection.
• the quality of the bonded connection can be increased in terms of contamination/yield if the roughening of the bonding wire is not carried out by removing material, i.e. brushing or milling, but rather by introducing indentations, for example by embossing he follows.
• a method for producing a wire including at least the following steps:
• the wire is a bonding wire, preferably a ribbon.
• a cross-sectional plane Q E is laid through an element selected from the group consisting of the wire precursor and the wire, the cross-sectional plane Q E being perpendicular to a longitudinal direction L of the element, the cross-sectional plane Q E forms a cross-sectional area Q A with the element, the cross-sectional area Q A including two perpendicularly crossing lines LI and L2, a shortest possible portion A Li of line LI being defined by an intersection with the edge of Q A , and a longest possible section A L2 of line L2 is defined by an intersection with the edge of Q A , where the quotient of A L2 and A L1 is a number of 2 or more.
• a wire obtainable by a method according to at least one of the embodiments
• A device containing at least:
• D height difference
• a method for producing a device containing at least one electrically conductive connection including the following steps:
• range specifications also include the values specified as limits.
• An indication of the type "in the range from X to Y" in relation to a quantity A therefore means that A can take the values X, Y and values between X and Y.
• Unilaterally delimited areas of the type "up to Y" for a size A mean corresponding values Y and smaller than Y.
• a first subject matter of the present invention relates to a method for producing a wire, including at least the following steps:
• wire precursors In principle, all wires and raw wires known to those skilled in the art that appear suitable for use in bonding in microelectronics and power electronics can be considered as wire precursors.
• the wire precursor like the wire formed, is usually a one-piece article. Numerous forms are known and suitable. Preferred shapes are - in cross-sectional view - round, ellipsoidal and rectangular shapes.
• a wire for bonding with an approximately rectangular cross-section is also referred to as a ribbon wire.
• the wire has a copper content of at least 95% by weight, preferably at least 99.95% or at least 99.9% by weight, or at least 99.99% by weight copper, with the % by weight being based on the total weight of the wire are related.
• the wire thus has up to 5% by weight, e.g. 4% by weight, or 3% by weight of other components.
• All elements that are familiar to the person skilled in the art and appear suitable in the present case can be considered as further components, in particular metals that can be alloyed with copper, as well as metals, semimetals and nonmetals that can form intermetallic phases with copper.
• the following metals are preferably considered as further components: tin (Sn), iron (Fe), nickel (Ni).
• the following semimetals are preferably considered as further components: Si.
• the following non-metals preferably come into consideration as further constituents: phosphorus (P).
• the wire can also contain impurities.
• the wire precursor usually has the same proportion of copper as the wire formed from the wire precursor by the method according to the invention.
• the wire precursor is a ribbon. This can then be cut lengthwise into several ribbon wires after step (ii) or after step (iii). According to a further preferred embodiment, the wire produced according to the invention is a ribbon.
• step (i) can in principle take place in a manner that is known to anyone skilled in the art and appears suitable.
• the provision preferably takes the form of straightening the wire precursor in a device.
• step (ii) indentations are indented on the wire precursor.
• the wire precursor can be formed at the same time or afterwards. The forming preferably takes place at the same time as the indentations are indented.
• Pressing in is understood to mean processing of the wire that takes place essentially without material removal. This differs from abrasive machining, in which material removal is caused by the abrasive machining itself. Examples of abrasive processing are brushing and grinding. As a result, a wire due to abrasive processing is lighter than before processing.
• pressing in can be carried out in a manner that is known to anyone skilled in the art and appears suitable.
• the indenting is done by a means selected from the group consisting of grains, indentations, embossing, stamping, sinking, and furrows.
• Indentation is particularly preferably effected by embossing.
• the indentation is carried out by rolling.
• Rolling is understood as a processing method in which a material, here a wire precursor, is processed between two or more rotating tools.
• a relief is transferred into the wire precursor by rolling.
• the wire precursor is preferably formed at the same time during rolling. A ribbon wire can thereby be obtained.
• the rolling can be carried out both as hot rolling and as cold rolling.
• the rolling preferably takes place as cold rolling.
• Indentation is particularly preferably carried out by means of embossing rollers. This means that forming and embossing take place simultaneously and in one step.
• the rolling is carried out by at least one roll.
• the roller often has a cylindrical surface, with other roller geometries also being known to the person skilled in the art and possibly appearing suitable.
• the roller is provided with a relief, the relief being formed by height differences of the cylindrical surface.
• the relief has a pattern.
• the height difference (D) of the relief of the roller is in a range from 3 to 9 ⁇ m. for example from 4 to 8 pm, or 5 to 7 pm, or 4 to 9 pm, or 5 to 9 pm.
• the indentations form a pattern.
• a pattern in the present context means a recurring image or design.
• the pattern formed by the relief on the roller corresponds to the pattern of the indentations on a wire processed by rolling with the roller.
• the wire has a number of points, with the indentations being introduced only at a first point.
• the wire preferably has a plurality of sides, in particular if it is a ribbon wire, with the indentations being introduced only on a first side.
• the wire has a roughness R z at at least one point in a range from 3 to 9 ⁇ m, for example from 4 to 8 ⁇ m, or 5 to 7 ⁇ m, or 4 to 9 ⁇ m, or 5 to 9 ⁇ m .
• the wire is a ribbon wire, it preferably has a roughness Rz in a range from 3 to 9 ⁇ m, for example from 4 to 8 ⁇ m, or 5 to 7 ⁇ m, or 4 to 9 ⁇ m, or 5 to 10 ⁇ m on a first side 9pm on.
• the roughness is determined according to DIN EN ISO 4287 (2010-07) and DIN EN ISO 4288 (1998-04).
• At least one further point of the wire is smooth, the at least one further point being located on a point of the wire which is remote from the first point of the wire.
• smooth is understood to mean a point or a surface, or a part thereof, if this has a roughness R z in a range from 0.1 to 1 pm, for example from 0.2 to 0.6 pm, or from 0 .2 to 0.4 pm.
• the wire is a ribbon
• part of a first side, or an entire first side and instead of the further point, part of a further side of the band, or an entire further side can be used have the properties described here.
• At least one further side of the wire is smooth, the at least one further side being located on a side of the wire which is remote from the first side of the wire.
• an element selected from the group consisting of the wire and the wire precursor has a cross-sectional area QA in a range from 25000 to 900000 ⁇ m 2 , the cross-sectional area QA being arranged perpendicularly to a longitudinal direction L of the element. If the cross-sectional area of the element is not the same at all points, the cross-sectional area QA is calculated as the arithmetic mean of several measurements of the cross-sectional area at at least seven different points on the element.
• an element selected from the group consisting of the wire precursor and the wire has a cross-sectional plane QE, which is laid through the element, the cross-sectional plane QE being arranged perpendicular to a longitudinal direction L of the element, the cross-sectional plane QE forms a cross-sectional area QA with the element, the cross-sectional area QA including two perpendicularly intersecting lines L 1 and L2, a shortest possible portion A L I of line L 1 being defined by an intersection with the edge of QA, and where a longest possible section A L2 of line L2 is defined by an intersection with the edge of QA, where the quotient of A L2 and A Li is a number of 2 or more, for example in a range from 2 to 30, or from 5 to 20 , or from 5 to 10.
• the cross-sectional plane QE and the other features mentioned in this paragraph are determined as shown in FIGS. If the geometry of the element, whose cross-sectional plane QE and other features are to be determined, deviates from the form shown schematically in Figures 1 and 2, the person skilled in the art will recognize and select a method of determination that comes closest to the diagram shown, taking into account the different geometry. It is quite possible that a precursor wire has a different geometry, for example that the quotient of A L2 and A Li is a number of 1. In this case, the precursor wire is round. It is then formed by the process in such a way that the wire has the aforementioned quotient of 2 or more.
• the wire is a ribbon, it can optionally be divided into several ribbons by suitable cutting processes after embossing, so that the longest possible section of the ribbon A L2 while retaining the shortest possible borrowed section A Li is shortened.
• the cutting process can optionally take place before or after the annealing of the ribbon.
• a tool is used to press it in.
• all devices that are known to the person skilled in the art and appear suitable are suitable as tools.
• a preferred tool is a roller.
• a roller is generally understood to mean a substantially cylindrical body. In principle, the roller can have any desired diameter. Rollers with a diameter of 50-150 mm are preferably suitable for the intended purpose. Furthermore, the roller should be formed from a material that is harder than an object to be formed under conditions of use. Rollers are often formed from forged steel, hard metal or cast steel.
• the tool is designed as an arrangement containing at least one roller. Arrangements with several rollers, for example two or more rollers, are also possible. For example, an arrangement is suitable in which at least two rollers rotate in opposite directions and the object to be shaped is passed between the two rollers rotating in opposite directions. The two counter-rotating rollers are arranged so that there is a gap between the two rollers. This distance is preferably equal to the thickness of the wire being formed.
• At least one first roller has a relief on its surface.
• the height differences of the relief on the first roller can form a pattern.
• the relief (also in the form of a pattern) is introduced into the object when an object to be formed passes through the tool.
• the depth of the indentations made in the wire depends on the penetration depth of the relief of the first roller into the object. It is quite possible that the difference in height (D) of the relief is greater than the indentations made in the object.
• the introduced height difference (D) of the transferred relief is referred to as roughness R z or also as embossing depth.
• the forming of an object with rollers, with at least one first roller having a relief that is transferred to the object during forming is also referred to as “embossing rollers”.
• the (first) roller accordingly as "embossing roller”.
• the impression is effected by stamping.
• a stamp is a surface with a relief.
• the relief shows a height difference (D).
• D height difference
• all materials that are known to the person skilled in the art and appear suitable are suitable for a stamp, but in particular the same materials as for the rollers.
• stamping a stamp is lowered onto an object to be processed. The relief is pressed into the object until the desired depth of the indentations is formed. This often corresponds to the height difference (D) of the relief, but sometimes the depth of the depressions is less than the height difference (D) of the relief.
• the introduced height difference (D) of the transferred pattern is referred to as roughness R z or also as stamping depth. not.
• the dimpled wire precursor is annealed into wire.
• the annealing takes place below the melting temperature of copper, preferably at temperatures T G in a range from 500 to 900°C, for example in a range from 550 to 650°C, or from 750 to 850°C.
• the specified annealing temperature T G is the temperature that a workpiece, here the wire, has over a specified period of time. The wire takes about 10 seconds to 6 minutes to glow.
• the annealing can be carried out batchwise or continuously.
• the annealing is preferably carried out continuously.
• a continuous furnace is suitable for this.
• a throughput distance in the continuous furnace and a temperature T o of the continuous furnace are selected in such a way that a wire passing through the throughput distance has the temperature T G for the duration specified above.
• the furnace temperature for example of the continuous furnace T o can be higher than the annealing temperature T G .
• the throughput section of the continuous furnace can also be longer and have a temperature gradient at the inlets and outlets. It is also possible to use a continuous furnace with multi-zone heating. This allows certain temperature profiles to be applied to a wire that is passing through.
• the continuous furnace can be heated and maintained at a conventional temperature by means of a heating device located in the furnace wall or acting on the furnace wall from the outside.
• An electric heater is suitable for this.
• the annealing temperature T G can be generated by a plasma in the continuous furnace.
• a nitrogen plasma can be used for this, for example with a typical output of 750 W and a process gas pressure (N 2 ) of 25 mbar.
• the annealing of the wire is performed in an atmosphere such as nitrogen (N 2 ).
• N 2 nitrogen
• oxygen (O 2 ) is excluded as far as possible in order to avoid surface oxidation of the wire.
• the atmosphere has a proportion of up to 10% by volume, for example in a range from 2 to 8% by volume, or about 5% by volume hydrogen (H 2 ).
• the hydrogen has a reducing effect in the protective gas atmosphere. The effect of this is that any copper oxidized on the surface to form copper oxides (CuO or Cu 2 O) on the wire is reduced to elemental copper.
• a second subject matter of the present invention is a wire obtainable by a method according to the first subject matter of the invention or one of the embodiments described therefor, or a combination of several of the embodiments described therefor.
• a third object, preferably obtainable by the method according to the first object, or as an embodiment of the second object, is a wire at least characterized by at least the following features:
• a first point of the wire in the case of a ribbon a first side, has a roughness R z of 3 to 9 pm, for example 4 to 8 pm, or 5 to 7 pm, or 4 to 9 pm, or 5 to 9pm on;
• At least one other point of the wire is smooth; in the case of a ribbon is at least one more
• the wire has a cross-sectional area QA in a range from 25,000 to 900,000 ⁇ m 2 .
• the wire preferably has the features (a) to (c), and additionally at least one of the further features (d) or (e), more preferably both features.
• a fourth subject matter is a method for producing a device containing at least one electrically conductive connection, the method including the following steps:
• Laser beams are preferably selected as the electromagnetic radiation.
• Laser beams are electromagnetic waves, often in a very narrow frequency range and with a high radiation intensity. Laser beams with a wavelength in the range from 700 to 1100 nm are particularly preferred.
• a 400 W fiber laser with a focus diameter of 25 ⁇ m is used, for example, to heat a wire as in step (III).
• the wire is a ribbon. The first and further positions of the tape are then each a part of a first or a further page, or a first or a further page as a whole.
• the wire mentioned in the fourth subject is producible by the method described as the first subject of the invention, or a wire according to the second or third subject of the invention. Preferred embodiments of the first, second and third aspects of the invention relating to the wire are also preferred in the fourth aspect for the wire.
• an electrically conductive connection is understood to mean a contact between two electrically conductive elements, for example a wire with a contact surface (for example a power semiconductor or a substrate surface (for example DCB or leadframe).
• a contact surface for example a power semiconductor or a substrate surface (for example DCB or leadframe).
• the wire according to the fourth subject of the invention is preferably obtainable by the method according to the first subject of the invention or one of its embodiments.
• the roughness R z according to the fourth subject matter of the invention was preferably produced at least at the first point of the wire by indentation.
• the indentation was preferably selected from the group consisting of grains, indentations, embossing, stamping, sinking and furrows, or a combination of two or more thereof.
• the roughness R z was brought about at least at the first point of the wire by rolling, for example embossing.
• a roll could include a relief for making wire.
• the relief preferably had a height difference (D) in a range from 3 to 9 ⁇ m. Indentations could thus be introduced at least at one point of the wire by the roller.
• Another object of the present invention is a device containing at least:
• a wire according to the second or third subject of the invention or a wire obtainable by a method according to the first subject of the invention, or according to one or more of the embodiments described in each case; wherein the wire is electrically conductively connected to the first contact surface.
• the wire can be electrically conductively connected to one or more further contact surfaces.
• a fifth subject matter of the present invention relates to the use of a roller containing a relief for producing a wire, the roller having a—preferably cylindrical—surface, and the relief being characterized by a height difference (D) of the surface in a range from 3 to 9 ⁇ m. for example from 4 to 8 gm, or 5 to 7 pm, or 4 to 9 pm, or 5 to 9 pm - indentations being introduced by the roller on at least one point of the wire.
• the indentations are preferably made on one side of the wire.
• a sixth subject of the present invention relates to the use of a roller containing a relief for setting the roughness R z at least at one point on a wire in a range from 3 to 9 ⁇ m—for example from 4 to 8 ⁇ m, or 5 to 7 ⁇ m, or 4 to 9 ⁇ m, or 5 to 9 ⁇ m, the roller having a surface—preferably cylindrical—and the relief being characterized by a height difference (D) of the surface.
• the wire is a ribbon
• the roughness R z is preferably introduced on one side of the wire.
• Preferred embodiments of the first subject matter of the invention are also preferred here insofar as they relate to the roller, the setting of the roughness R z , the roughness R z and the height difference (D).
• Figure 1 shows a schematic view of a wire or wire precursor.
• FIG. 2 shows a view of a cross-sectional area Q ⁇ of the object shown in FIG.
• FIG. 3 schematically shows a method for making indentations in a wire.
• Fig. 4 shows a ribbon a) with relief, b) with brushing.
• FIG. 5 schematically shows a device with a wire and a contact surface.
• FIG. 1 shows a schematic view of a wire 2 or a wire precursor 1 characterized by its length L and a cross-sectional plane Q E .
• FIG. 2 shows a view of a cross-sectional area Q ⁇ as part of the cross-sectional plane Q E shown in FIG.
• Two perpendicular lines LI, L2 are laid through the cross-sectional area Q ⁇ . These intersect the cross-sectional area Q ⁇ in the edges of the wire 2 or of the wire precursor 1. As a result, the sections A L1 and A L2 of the lines L1 and L2 are formed.
• FIG. 3 schematically shows a method for making indentations 3 in a wire 2 by means of a roller with a relief (upper roller, unnumbered).
• the bottom roller is optional and can be replaced with another counter surface.
• FIG. 4 shows the surface topography of a) a tape 2 with an incorporated pattern 6 of depressions 3; b) a brushed ribbon.
• FIG. 5 schematically shows a device 10 containing a wire 2 which connects a first contact surface 12 to a second contact surface 13 .
• the relief height D and the roughness Rz of the wire were determined based on the standards DIN EN ISO 4287 (2010-07) (definition and parameters) and DIN EN ISO 4288 (1998-04) (rules and procedures)., where the relief height of the roller and the roughness of the wire were determined transversely to the rolling direction. Deviating from the DIN EN ISO 4288 standard, measurements were taken over a shorter individual and overall measuring section due to the geometrical conditions of the ribbons. At least one third of the ribbon width or the effectively used roller width was defined as a sufficiently long individual measurement section. A Mahr Perthometer PCV with a 2 ⁇ m diamond tip was used. The determination is made at at least two different points on the wire or roll. The measured data was evaluated in accordance with DIN EN ISO 4287 using the MahrSurface XCR20 VI.20-4 program. b. Determination of the cross-sectional area of a wire or ribbon
• a metallographic section was prepared and measured using an optical microscope.
• Copper wire with a diameter of 0.78 mm and a purity of 99.98% by weight Cu was used as the starting material.
• the wires were guided through a forming plant with two hard metal rollers in the arrangement outlined in FIG.
• Roll No. 1 (in the figure below) was a smooth cylinder with a diameter of 96 mm.
• Roll No. 2 (in the figure above) also had a basic cylindrical shape with a diameter of 96 mm.
• the surface of roll No. 2 had a relief with a relief height D (D max ).
• D max relief height
• the surface of roll No. 2 was smooth and did not have any relief structure.
• the wires were passed between rollers #1 and #2 rotating in opposite directions but in the direction of travel of the wires.
• Rolls #1 and #2 had a nip S between them. This was set and determined as the shortest distance between the surface of roll no. 1 and the surface of the cylindrical basic shape of roll no. 2, ie at a point without relief.
• the exit speed of the wires in the direction of transport was identical to the rotational speed v of the rollers at the contact surface with the wire.
• a quickly evaporating B-Clean 62S rolling oil was used as the rolling oil.
• the worked wires (1) - (3) and (A) and (B) were processed in a 2.5 m long continuous furnace a throughput speed of 10 m/min and an annealing temperature T G of 650° C. in a hydrogen atmosphere. After annealing, the formed wires were cooled to ambient temperature.
• the formed comparison wires (A) and (B) were brushed according to the characteristic data in Table 2 after the annealing process.
• the characteristics of the formed wires (1) - (3) are given in Table 1.
• the shaped wires (1) and (2) with a roughness of R z less than 9 ⁇ m showed no spattering behavior in the laser bonding process.
• the formed (3) with an increased roughness of R z of 18.6 pm showed a clear spattering behavior in the laser bonding process.

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• 2021
  • 2021-09-15 CN CN202180055579.XA patent/CN116018218A/zh active Pending
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