Solder alloys and arrangements

Abstract

Containing solder alloy: Zinc, aluminum, magnesium and gallium, wherein the aluminum constitutes 8% to 20% of the alloy by weight, the magnesium constitutes 0.5% to 20% of the alloy by weight and the gallium constitutes 0.5% to 20% of the alloy by weight, and wherein the remainder of the alloy comprises zinc.

Description

TECHNICAL FIELD

[0001] Different embodiments generally concern solder alloys and arrangements. BACKGROUND

[0002] The European Union has made decisions to ban environmentally hazardous substances in the near future. Such decisions were made with regard to end-of-life vehicles (ELVs), indicating that hazardous substances such as lead will be banned. Lead-based products, such as lead-based solder materials used in chip or semiconductor chip assemblies, will be banned and removed from the market in the near future.

[0003] Suitable alternative solder materials will be selected in the future based on their economic viability. The costs of suitable alternatives should be at least comparable to those of current standard solder materials. Suitable alternatives will also have to meet requirements and exhibit necessary properties so that they can be used as connecting elements, such as for a solder joint. Such alternatives should be compatible for use on different surfaces, for example, on lead frames or on the backsides of chips. They should also be electrically and thermally conductive and robust and reliable enough for their application, for example, when exposed to high temperatures or changing temperature loads.

[0004] Another technical requirement is that the solidus temperature of the solder material should be above 260°C, so that the solder material does not melt and / or soften during subsequent processes, such as when soldering the circuit board. Further requirements for alternative solder materials include meeting the ductility requirements so that solder wire can be produced from the solder material.

[0005] To date, there is no lead-free soft solder alternative in the semiconductor field for connecting a chip to a lead frame or from a clip (spring contact, bracket) to a bond pad (contact pad) that is suitable for mass production. The technical challenge lies in finding a lead-free solder with a melting temperature higher than that of the solder material used in printed circuit boards, for example, Sn-Ag-Cu systems, which typically have melting temperatures of 260°C. However, the melting temperature should not be too high, as cooling and simultaneous solidification of the solder would introduce high mechanical stress into the system.

[0006] A lead-free solder material, regardless of the melting temperature requirements, should have good wettability on different metallic surfaces, such as chip surfaces or lead frames, which can be used to ensure an optimal connection. The solder material should also exhibit a certain degree of formability so that it can be produced and handled in wire form. This means that the solder material in wire form should not be brittle. The solder material must withstand repeated melting and hardening conditions and mechanical and thermomechanical stresses to which the material is exposed without undergoing wear.

[0007] US 2008 / 0122050 A1 describes coating a stress-absorbing metal foil on both sides with a high-melting solder layer and a low-melting solder layer. The low-melting solder layer is intended to enable better wettability and react chemically with the high-melting solder layer, resulting in a temperature-resistant reaction layer. The mechanical stress generated during this soldering process is intended to be absorbed by the metal foil.

[0008] US 2007 / 0125449 A1 describes a superconducting device containing a lead-free zinc-based solder alloy.

[0009] DE 10 2005 052 563 A1 describes a semiconductor chip in which the chips are contacted using a lead-free, tin-based solder alloy.

[0010] DE 103 92 947 T5 describes a lead-free solder alloy which, in addition to zinc, also contains nickel, aluminium and tin.

[0011] WO 02 / 09936 A1 describes an alloy of at least two metals selected from the group consisting of zinc, aluminum, magnesium and gallium, and wherein the alloy further comprises at least one chemical element other than zinc, aluminum, magnesium and gallium which has a higher oxygen affinity than the alloy.

[0012] JP 2000-61 686 A describes a lead-free solder alloy which, in addition to zinc, also contains aluminum, magnesium and gallium. DESCRIPTION OF THE INVENTION

[0013] One embodiment is a solder alloy comprising zinc, aluminum, magnesium, and gallium, wherein the aluminum comprises 8% to 20% by weight of the alloy, the magnesium comprises 0.5% to 20% by weight of the alloy, the gallium comprises 0.5% to 20% by weight of the alloy, and the remainder of the alloy comprises zinc. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In the drawings, similar reference numerals generally refer to the same parts throughout the figures. The drawings are not necessarily to scale, with emphasis instead placed upon illustrating the principles of the invention. In the following description, various embodiments of the invention are described with reference to the following drawings, in which: Fig. 1 a graph showing the thermal conductivity (W / mK) versus the electrical conductivity (10 6 S / m) of the solder alloy; Fig. 2 a phase diagram 200 of an Al-Zn alloy; Fig. 3 a phase diagram 300 of a Ga-Zn alloy; Fig. 4 a phase diagram 400 of a Sn-Zn alloy; Fig. 5 a phase diagram 500 of an Ag-Zn alloy; Fig. 6 a phase diagram 600 of a Cu-Zn alloy; Fig. 7 a phase diagram 700 of a Ni-Zn alloy; Fig. 8 shows a method for arranging a chip on a carrier according to various embodiments; Fig. 9A and Fig. 9B shows an arrangement when arranging a chip on a carrier according to various embodiments; Fig. 10A to 10C illustrate an arrangement comprising a solder alloy applied to a carrier according to various embodiments; Fig. 11A and Fig. 11B is an image of an assembly including a solder alloy according to various embodiments; Fig. 12 to 14 show differential calorimetric scan diagrams of a solder alloy according to various embodiments; Fig. Figure 15 is a graph of experimental solder composition versus theoretical prediction of the liquid phase for a solder alloy comprising zinc, aluminum, and magnesium; Fig. Figure 16 is a graph of experimental solder composition versus theoretical prediction of the liquid phase for a solder alloy comprising zinc, aluminum, and germanium. DETAILED DESCRIPTION

[0015] The following detailed description refers to the attached drawings, which show, by way of illustration, specific details and embodiments in which the invention may be practiced. The term "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment or design described herein as "exemplary" may not necessarily be considered preferred or advantageous over other embodiments or designs.

[0016] Various embodiments provide a multi-layer system of a lead-free (Pb-free) solder joint for electronic components, comprising at least one side of a chip, a solder joint, for example a solder alloy, a carrier, for example a lead frame, and a coating, for example a lead frame coating, formed on the carrier.

[0017] Compared to lead-based solders, zinc-based solder systems have better physical properties, such as better thermal (heat) and electrical conductivity. This is based on Fig. 1, where a diagram 100 shows the thermal conductivity (W / mK) versus the electrical conductivity (10 6S / m). It has been shown from measurements and calculations that pure zinc and a zinc alloy containing aluminum and germanium have higher thermal conductivity and electrical conductivity compared to lead-based and tin-based solders.

[0018] Fig. Figure 2 shows a phase diagram of a binary Al-Zn alloy. With an atomic composition of 87.5% zinc and 12.5% ​​aluminum, the binary Al-Zn alloy can reach a melting point of approximately 650°C.

[0019] Fig. Figure 3 shows a phase diagram 300 of a binary Ga-Zn alloy. With an atomic composition of 2.5% zinc and 87.5% gallium, the binary Ga-Zn alloy can reach a melting point of approximately 300°C.

[0020] Fig. Figure 4 shows a phase diagram 400 of a binary Sn-Zn alloy. The binary Sn-Zn alloy, formed with an atomic composition of 13% zinc and 87% tin, can reach a melting point of approximately 475°C.

[0021] Fig. Figure 5 shows a phase diagram of a binary Ag-Zn alloy. With an atomic composition of 98% zinc and 2% silver, the binary Ag-Zn alloy can reach a melting point of approximately 700°C.

[0022] Fig. Figure 6 shows a phase diagram 600 of a binary Cu-Zn alloy. With an atomic composition of approximately 2% copper and 98% zinc, the binary Cu-Zn alloy can reach a melting point of approximately 425°C. Table 606 shows different phases with corresponding alloy concentrations of the binary Cu-Zn alloy.

[0023] Fig. Figure 7 shows a phase diagram of a binary Ni-Zn alloy. With an atomic composition of approximately 1% nickel and 99% zinc, the binary Ni-Zn alloy can reach a melting point of approximately 700°C. Table 706 shows different phases with corresponding alloy concentrations of the binary Ni-Zn alloy.

[0024] Fig. 8 shows a method for arranging and / or attaching a chip 814 on a carrier. The method may include, in a step 800, selecting a carrier 802, for example, a substrate or a lead frame; in a step 804, forming a coating 806, for example, a nickel coating, on the carrier 802; and in a step 808, applying a solder alloy 810 to the carrier 802, wherein the solder alloy 810 may be formed directly on the coating 806. In step 808, the application of the solder alloy 810 may be performed as in a conventional wire bonding process by melting the solder alloy 810, for example, by forming a solder dot from the solder alloy 810, which may be in the form of a wire and / or soft solder, on the carrier 802. The solder alloy 810 may be applied in strip form or as a layer on the carrier 802.Alternatively, the solder alloy 810 may be placed at a wafer level above or directly on the chip 814, for example, prior to dicing the wafer or on the chip backside 820, where the chip backside 820 may include a chip backside metallization 816. In step 812, the chip 814 may be attached to the carrier 802 via the solder alloy 810, where the solder alloy 810 may couple or connect the material between the chip 814 and the carrier 802. In a step 822, a further solder alloy 828 may be formed to provide a clip-on connection to a contact pad on a chip front side 830 by applying the solder alloy 810 to one or more contact pads 818 on the chip front side 830. One or more contact lines 824 may be arranged on the chip 814 and / or the contact pads 818 via the solder alloy 828.The application and placement of the solder alloy 810 and the further solder alloy 828 can be carried out by dispensing a paste of the corresponding alloy and / or by means of a plasma gun.

[0025] The solder alloy 810 can be used to connect the chip backside 820 to the carrier 802, for example, a lead frame, even if the chip 814 is not a silicon-based chip. The chip backside 820 can have a backside metallization system 816 that has a multilayer system or is part of or a variation of a multilayer system. The multilayer system can have individual layers that have individual functions.

[0026] The multilayer system may include a contact layer 816a for contacting a semiconductor material, for example an aluminum contact layer, wherein the aluminum forms a layer having a thickness in the range of 50nm to 1000nm.

[0027] The multilayer system may include a barrier layer 816b, for example a titanium (Ti) or titanium-tungsten (TiW) barrier layer, wherein the barrier layer 816b may have a thickness in the range of 50nm to 1000nm.

[0028] The multilayer system may include a solder reaction layer 816c, wherein the solder reaction layer 816c comprises, for example, at least one element and / or an alloy with an element from a group of the following elements: nickel, nickel-vanadium, silver, aluminum, gold, platinum, palladium, and / or nickel, wherein the solder reaction layer 816c may have a thickness in the range of 50 nm to 1000 nm. The solder reaction layer 816c may be a "partner" layer of the solder alloy 810, since the thickness of the solder reaction layer 816c may be selected such that it does not completely dissolve into the solder alloy 810 during the soldering process.

[0029] The multilayer system may include an oxidation protection layer 816d to prevent oxidation of the solder reaction layer 816c, since the solder reaction layer 816c, which comprises silver, gold, platinum, palladium, or alloys containing these materials, may be subject to oxidation. The oxidation protection layer 816d may have a thickness in the range of 50 nm to 1000 nm.

[0030] The substrate 802 can, for example, be formed from a material from the following group of materials: copper, nickel, silver, or ceramic. The layer 806 can be formed on the substrate 802, wherein the substrate 802 can, for example, be a lead frame, wherein, for example, a lead frame coating can be formed on the lead frame. The coating 806 can, for example, comprise a material from the following group of materials: silver, gold, nickel, platinum, palladium, vanadium, molybdenum, tin, copper, arsenic, antimony, gallium, zinc, aluminum, niobium, tantalum, phosphorus, silver, nickel, and / or nickel-phosphorus in elemental form and / or in the form of nitrides and / or in the form of oxides, wherein the at least one material from the group of materials can be present alone or in combination with other materials. The coating 806 can be configured to be in conjunction with the solder alloy 810.

[0031] According to various embodiments, the substrate 802 may include the coating 806, which may include copper in combination with nickel and / or nickel phosphorus, wherein the coating 806 may be a leadframe coating configured to be in contact with the solder alloy. According to various embodiments, the thickness of the coating 806 may range from approximately 100 nm to approximately 3 μm.

[0032] According to various embodiments, the chip 814 may have a chip backside 820, which may, for example, comprise at least one material from the following group of materials: aluminum, titanium, nickel, vanadium and / or silver, wherein the chip backside 820 may be configured to form a connection with the solder alloy 810.

[0033] The solder alloy 810A according to various embodiments may comprise zinc, aluminum, magnesium, and gallium, wherein aluminum comprises 8% to 20% by weight of the alloy 810A, magnesium comprises 0.5% to 20% by weight of the alloy 810A, and gallium comprises 0.5% to 20% by weight of the alloy 810A, and wherein the remainder of the alloy 810A may comprise zinc. The solder alloy 810A may be represented by the chemical formula ZnAl 4,5 Ga1Mg1. The solder alloy 810A can be represented by the chemical forms ZnAl 12 Ga1Mg1 may be represented. According to various embodiments, the solder alloy 810A may be a solder wire. The aluminum may, for example, comprise 3% to 12% of the 810A alloy by weight. Magnesium may, for example, comprise 0.5% to 4% of the 810A alloy by weight. Gallium may, for example, comprise 0.5% to 4% of the 810A alloy by weight.

[0034] A solder alloy 810B may, according to various embodiments, comprise zinc, aluminum, tin, and magnesium, wherein aluminum constitutes greater than 8% to 30% by weight of alloy 810B, magnesium constitutes greater than 0.5% to 20% by weight of alloy 810B, and tin constitutes 0.5% to 6.5% by weight of alloy 810B, and wherein the remainder of alloy 810B comprises zinc. Aluminum may constitute 3% to 8% by weight of alloy 810B. Magnesium may constitute 0.5% to 4% by weight of alloy 810B. Tin may constitute 0.5% to 4% by weight of alloy 810B. Solder alloy 810B may be represented by the chemical formula ZnAl4Sn2Mg1.

[0035] According to various embodiments, the 810C solder alloy may comprise zinc, aluminum, germanium, and gallium, wherein aluminum may comprise 1% to 30% by weight of the 810C alloy, germanium may comprise 0.5% to 20% by weight of the 810C alloy, and gallium may comprise 0.5% to 20% by weight of the 810C alloy, and wherein the remainder of the 810C alloy may comprise zinc. Aluminum may comprise 3% to 8% by weight of the 810C alloy. Germanium may comprise 0.5% to 4% by weight of the 810C alloy. Gallium may comprise 0.5% to 4% by weight of the 810C alloy.

[0036] For example, a brazing alloy 810D according to various embodiments may comprise zinc, aluminum, and germanium, wherein aluminum may comprise 1% to 20% by weight of the 810D alloy, germanium may comprise 1% to 20% by weight of the 810D alloy, and the remainder of the 810D alloy may comprise zinc. The brazing alloy 810D may be represented by the chemical formula ZnAl5Ge3. The brazing alloy 810D may be represented by the chemical formula ZnAl 12 Ge3. The 810D solder alloy can be represented by the chemical formula ZnAl6G3. The solder alloy can be represented by the chemical formula ZnAl6Ge5. According to various embodiments, aluminum can comprise 3% to 8% by weight of the 810D alloy. According to various embodiments, germanium can comprise 1% to 6% by weight of the 810D alloy.

[0037] According to various embodiments, the brazing alloy 810E may comprise zinc, aluminum, and magnesium, where aluminum may comprise 1% to 20% of the 810E alloy by weight, magnesium may comprise 1% to 20% of the 810E alloy by weight, and the remainder of the 810E alloy may comprise zinc. Aluminum may comprise 3% to 8% of the 810E alloy by weight. Magnesium may comprise 0.5% to 4% of the 810E alloy by weight.

[0038] The solder alloy 810F can, according to various embodiments, comprise zinc and tin, where zinc can make up 10% to 91% by weight of the alloy 810F. The solder alloy 810F can be characterized by the chemical formula Zn 40 Sn 60 For example, zinc can make up 10% to 15% of alloy 810F by weight.

[0039] A brazing alloy 810G according to various embodiments may comprise zinc and silver, where zinc may comprise 26% to 98% of the 810G alloy by weight. Zinc may comprise 83% to 99% of the 810G alloy by weight.

[0040] A brazing alloy 810H according to various embodiments may comprise zinc and copper, wherein zinc may comprise 80% to 98% of the alloy 810H by weight. Zinc may comprise 88% to 99% of the alloy 810H by weight.

[0041] According to one embodiment, each of the alloys 810A to 810H may further comprise, for example, at least one material from the following group of materials: silver, gold, nickel, platinum, palladium, vanadium, molybdenum, tin, copper, arsenic, antimony, gallium, zinc, aluminum, niobium and / or tantalum, each individually and / or in combination comprising by weight from 0.001% to 10% of the corresponding alloy 810A to 810H.

[0042] Fig. 9A shows arrangements 930, 932, and 934 according to various embodiments. Arrangement 930 shows a solder alloy 810, for example, the solder alloy 810D, applied to the carrier 802, for example, a lead frame, prior to attaching the chip 814 to the carrier 802. Arrangement 932 shows an ultrasonic image of the arrangement 930 after arranging the chip 814 using a chip arrangement method on the solder alloy 810, for example, the solder alloy 810D, which has the chemical formula ZnAl5Ge3. Arrangement 934 shows an ultrasonic image according to arrangement 932, wherein the solder alloy 810 has the chemical formula ZnAl 12 Ge3 has.

[0043] Fig. 9B shows arrangements 936, 938, and 940 according to various embodiments. Arrangement 936 shows an ultrasonic image of a solder alloy 810, for example, the solder alloy 810A, on the carrier 802, for example, a lead frame, after arranging the chip 814 using a chip arrangement method on the solder alloy 810, for example, the solder alloy 810A having the chemical formula ZnAl 4,5 Ga1Mg1. Arrangement 938 shows an ultrasonic image according to arrangement 936, where the solder alloy 810 has the chemical formula ZnAl 12 Ga1Mg1. In ultrasonic imaging, white colored spots indicate detachments or voids, whereas black areas represent directly connected homogeneous solder regions.

[0044] Fig. 10A shows an arrangement 1030 wherein a solder alloy 810, for example, solder alloy 810A comprising zinc, aluminum, magnesium, and gallium, is applied to a carrier 802, for example, a lead frame, wherein the lead frame has a lead frame coating 806 comprising NiNiP. Fig. 10B shows an arrangement 1032 illustrating various embodiments according to the arrangement 1030, wherein the leadframe coating 806 comprises copper instead of NiNiP. The solder alloy 810A exhibits good wetting behavior on the copper surface and the NiNiP surface of the carrier 802, with the best results regarding the homogeneity of the solder alloy 810A being achieved on the surface of the leadframe coating 806. Fig. 10C shows arrangements 1034 and 1036 according to various embodiments. Arrangement 1034 shows an image of the interface between the carrier 802, e.g., a lead frame, and the solder alloy 810A. Arrangement 1036 shows an image of the interface between the carrier 802, e.g., a lead frame, the solder alloy 810A, and the chip 814. At both 1034 and 1036, two chips 814 are arranged on the lead frame 802. The white dots in the chip regions 814 may be associated with delaminations or voids. The void rate obtained with the solder alloy 810A on the cladding 806, e.g., a lead frame cladding comprising NiNiP, is lower compared to that of the cladding 806 comprising a copper lead frame cladding.

[0045] Fig. 11A shows an electron scanning microscope (SEM) image 1130 of a section through solder alloy 810A, which has the chemical formula ZnAl 12Ga1Mg1, applied to the carrier 802, for example, a copper leadframe, and solder alloy 810A, which is connected to the chip backside 820. The chip backside 820 may include a chip backside metallization 816, wherein the backside metallization 816 may include an Al-Ti-Ag stack (an Al-Ti-Ag layer). The backside metallization 816 may include a contact layer 816A, for example, an aluminum contact layer; a barrier layer 816B, for example, a titanium barrier layer; and a solder reaction layer 816, for example, a silver solder reaction layer.

[0046] Fig. 11B shows an image 1132, providing labeled regions of the SEM image 1130 from which the Energy Dispersive X-ray Spectroscopy (EDX) data can be extracted. Spectrum 2 1134 includes zinc, copper, and aluminum. Spectrum 3 1136 includes zinc, copper, aluminum, and silver. Spectrum 4 1138 includes zinc, copper, silver, and trace amounts of aluminum (less than 2%). Spectrum 5 1140 includes zinc, aluminum, copper, and trace amounts of silver (less than 2%). Spectrum 6 1142 includes zinc, aluminum, and trace amounts of silver (less than 2%). The silver diffuses from the solder reaction layer 816 into the solder alloy 810A. Gallium can be detected between the grain boundaries, which improves the mechanical properties of the solder, with a tensile strength of 345MPa of the solder alloy 810A, which has the chemical formula ZnAl 12Ga1Mg1. Copper diffusion from the lead frame into all bright areas of the cross-section is detected.

[0047] Fig. 12 shows differential scanning calorimetry (DSC) diagrams 1230, 1236 of the solder alloy 810A. DSC diagram 1230 shows a heat flux (W / g) 1232 versus temperature (°C) 1234 with respect to the solder alloy 810A, which according to one embodiment has the chemical formula ZnAl 4,5Ga1Mg1. The solder alloy 810A exhibits exothermic maxima at approximately 262°C, 340°C, and 366°C. The maximum, which represents an enthalpy of 9.0 J / g and occurs at a maximum temperature of 261.8°C, reflects a eutectic reaction between zinc and aluminum. All other maxima at higher temperatures arise due to ternary reactions of Zn-Al with another alloying element of the alloy, for example, Ga or Mg. The other maxima reflect the melting temperature range and are important for setting the process parameters. The occurrence of two or more maxima at specific positions is characteristic of a special alloy composition with specific phases formed during the wire manufacturing process.

[0048] DSC diagram 1236 shows a heat flow (W / g) 1238 versus temperature (°C) 1240 with respect to the solder alloy 810A, which according to one embodiment has the chemical formula ZnAl 12 Ga1Mg1. The solder alloy 810A exhibits exothermic maxima at approximately 273°C and 344°C. Therefore, a melting point of approximately 344°C can be maintained for the solder alloy 810A, which has the chemical formula ZnAl 12 Ga1Mg1. The maximum, which represents an enthalpy of 24.4 J / g and occurs at a maximum temperature of 272.6°C, reflects a eutectic reaction between zinc and aluminum. All other maxima at higher temperatures are caused by ternary reactions of Zn-Al with other alloying elements of the alloy, such as Ga or Mg.

[0049] Fig. 13 shows a DSC diagram 1330 plotting heat flux (W / g) 1332 versus temperature (°C) 1334 with respect to the solder alloy 810B, which, according to various embodiments, has the chemical formula ZnAl4Sn2Mg1. The solder alloy 810B exhibits exothermic maxima at approximately 284°C, 336°C, and 365°C. The maximum, representing an enthalpy of 9.0 J / g and occurring at a maximum temperature of 284.4°C, reflects a eutectic reaction between zinc and aluminum. All other maxima at higher temperatures arise due to further reactions of Zn-Al with other alloying elements of the alloy, for example, Sn or Mg.

[0050] Fig. Figure 14 shows differential scanning calorimetry (DSC) diagrams 1430, 1436 of the solder alloy 810D. DSC diagram 1430 shows a heat flow (W / g) 1432 versus temperature (°C) 1434 with respect to the solder alloy 810D, which has the chemical formula ZnAl5Ge3, according to various embodiments. The solder alloy 810D exhibits exothermic maxima at approximately 283°C and 359°C. The maximum, representing an enthalpy of 8.6J / g and occurring at a maximum temperature of 282.8°C, reflects a eutectic reaction between zinc and aluminum. All other maxima at higher temperatures arise due to ternary reactions of Zn-Al with other alloying elements of the alloy, for example, Ge.

[0051] DSC diagram 1436 shows a heat flow (W / g) 1438 versus temperature (°C) 1440 with respect to the solder alloy 810D, which according to various embodiments has the chemical formula ZnAl 12Ge3. The solder alloy 810D exhibits exothermic maxima at approximately 283°C, 359°C, 368°C, and 412°C. The maximum, representing an enthalpy of 24.4 J / g and occurring at a maximum temperature of 282.8°C, reflects a eutectic reaction between zinc and aluminum. All other maxima at higher temperatures are caused by ternary reactions of Zn-Al with other alloying elements of the alloy, such as Ge.

[0052] Fig. 15 shows a graph 1500 of an experimental solder composition versus a theoretical prediction of the liquid phases of a solder alloy comprising zinc, aluminum, and magnesium. According to various embodiments, a lowest achievable melting temperature for the solder alloy can be achieved at approximately 350°C at an atomic zinc composition of approximately 91% to 96%. Axis 1532 denotes the molar fraction of aluminum relative to zinc. Axis 1534 denotes the molar fraction of zinc relative to magnesium. Axis 1536 denotes the molar fraction of magnesium relative to aluminum. The quaternary solder compositions 810B (ZnAl4Sn2Mg1) and 810A (ZnAl5Mg1Ga1) can be found slightly above the horizontal 400°C line of the graph in Fig. 15, since the low concentrations of tin for 810B and gallium for 810A will not significantly change the liquidus temperatures of the 810B and 810A solders.

[0053] Fig.Figure 16 shows a diagram 1600 of an experimental solder composition versus a theoretical prediction of the liquid phase for a solder alloy comprising zinc, aluminum, and germanium. Axis 1632 indicates the molar fraction of aluminum relative to zinc. Axis 1634 indicates the molar fraction of zinc relative to germanium. Axis 1636 indicates the molar fraction of germanium relative to aluminum. Diagram 1638 shows an enlarged section of the selected section 1640, where, at an atomic composition of 97%Zn, 1.5%Al, and 1.5%Ge, the lowest achievable melting temperature of the solder alloy can be reached at approximately 335°C. The solder alloy 810 has the chemical formula ZnAl 12Ge3 or ZnAl5Ge3, which are shown as points in diagrams 1600 and 1638. With an atomic composition of 1.6% aluminum, 80% zinc, and 3.4% germanium, a four-phase division can be achieved. Furthermore, a melting temperature of 343.42°C can be achieved.

[0054] In various embodiments, a solder alloy is provided. The solder alloy may comprise zinc, aluminum, magnesium, and gallium, wherein aluminum comprises 8% to 20% by weight of the alloy, magnesium comprises 0.5% to 20% by weight of the alloy, gallium comprises 0.5% to 20% by weight of the alloy, and the remainder of the alloy comprises zinc. In various embodiments, the solder alloy may be represented by the chemical formula ZnAl 4,5 Ga1Mg1. In various embodiments, the solder alloy can be represented by the chemical formula ZnAl 12Ga1Mg1 may be represented. In various embodiments, the solder alloy may be a solder wire. In various embodiments, aluminum may comprise 3% to 12% of the alloy by weight. In various embodiments, magnesium may comprise 0.5% to 4% of the alloy by weight. In various embodiments, gallium may comprise 0.5% to 4% of the alloy by weight. In various embodiments, the alloy may further comprise, for example, at least one material from the following group of materials: silver, gold, nickel, platinum, palladium, vanadium, molybdenum, tin, copper, arsenic, antimony, gallium, zinc, aluminum, niobium, and / or tantalum, each individually and / or in combination comprising 0.001% to 10% by weight of the alloy.

[0055] In various embodiments, a solder alloy is provided. The solder alloy may comprise zinc, aluminum, tin, and magnesium, wherein aluminum comprises 1% to 30% of the alloy by weight, magnesium comprises 0.5% to 20% of the alloy by weight, tin comprises 0.5% to 6.5% of the alloy by weight, and the remainder of the alloy comprises zinc. In various embodiments, the aluminum may comprise 3% to 8% of the alloy by weight. In various embodiments, magnesium may comprise 0.5% to 4% of the alloy by weight. In various embodiments, tin may comprise 0.5% to 4% of the alloy by weight. In various embodiments, the solder alloy may be represented by the chemical formula ZnAl4Sn2Mg1.In various embodiments, the alloy may further comprise, for example, at least one material from the following group of materials: silver, gold, nickel, platinum, palladium, vanadium, molybdenum, tin, copper, arsenic, antimony, gallium, zinc, aluminum, niobium and / or tantalum, each individually and / or in combination comprising by weight from 0.001% to 10% of the alloy.

[0056] In various embodiments, a solder alloy is provided. The solder alloy may comprise zinc, aluminum, germanium, and gallium, wherein aluminum comprises 1% to 30% of the alloy by weight, the germanium comprises 0.5% to 20% of the alloy by weight, the gallium comprises 0.5% to 20% of the alloy by weight, and the remainder of the alloy comprises zinc. In various embodiments, the aluminum may comprise 3% to 8% of the alloy by weight. In various embodiments, the germanium may comprise 0.5% to 4% of the alloy by weight. In various embodiments, the gallium may comprise 0.5% to 4% of the alloy by weight.In various embodiments, the alloy may further comprise, for example, at least one material from the following group of materials: silver, gold, nickel, platinum, palladium, vanadium, molybdenum, tin, copper, arsenic, antimony, gallium, zinc, aluminum, niobium and / or tantalum, each individually and / or in combination comprising by weight from 0.001% to 10% of the alloy.

[0057] In various embodiments, an assembly is provided. The assembly may include a chip; a solder alloy suitable for attaching the chip to a lead frame; the solder alloy comprising: zinc, aluminum, and germanium, wherein the aluminum comprises 1% to 20% by weight of the alloy, the germanium comprises 1% to 20% by weight of the alloy, and the remainder of the alloy comprises zinc. In various embodiments, the solder alloy may be represented by the chemical formula ZnAl5Ge3. In various embodiments, the solder alloy may be represented by the chemical formula ZnAl 12Ge3. In various embodiments, the solder alloy is represented by the chemical formula ZnAl6Ge3. In various embodiments, the solder alloy may be represented by the chemical formula ZnAl6Ge5. In various embodiments, the aluminum may comprise 3% to 8% of the alloy by weight. In various embodiments, germanium may comprise 1% to 6% of the alloy by weight. In various embodiments, the alloy may further comprise, for example, at least one material from the following group of materials: silver, gold, nickel, platinum, palladium, vanadium, molybdenum, tin, copper, arsenic, antimony, gallium, zinc, aluminum, niobium, and / or tantalum, each individually and / or in combination comprising 0.001% to 10% by weight of the alloy.In various embodiments, the leadframe may have a leadframe coating that, for example, comprises at least one material from the following group of materials: silver, gold, nickel, platinum, palladium, vanadium, molybdenum, tin, copper, arsenic, antimony, gallium, zinc, aluminum, niobium, tantalum, phosphorus, silver, nickel, and / or nickel-phosphorus in elemental form and / or in the form of a nitride and / or in the form of an oxide, wherein the leadframe coating may, for example, comprise at least one material from the group of materials individually or in combination; wherein the leadframe coating is configured to be in contact with the solder alloy. In various embodiments, the leadframe may have a leadframe coating that comprises copper in combination with nickel and / or nickel-phosphorus; wherein the leadframe coating is configured to be in contact with the solder alloy.In various embodiments, the thickness of the leadframe coating is between 100 nm and 3 µm. In various embodiments, the chip may have a chip backside 820, which, for example, comprises at least one material from the following group of materials: aluminum, titanium, nickel, vanadium, and / or silver, wherein the chip backside 820 is configured to be in contact with the solder alloy.

[0058] In various embodiments, an assembly is provided. The assembly may include a chip; a solder alloy for attaching the chip to a lead frame; the solder alloy comprises zinc, aluminum, and magnesium, wherein the aluminum comprises 1% to 20% by weight of the alloy, the magnesium comprises 1% to 20% by weight of the alloy, and the remainder of the alloy comprises zinc. In various embodiments, the aluminum may comprise 3% to 8% by weight of the alloy. In various embodiments, magnesium may comprise 0.5% to 4% by weight of the alloy.In various embodiments, the alloy may further comprise, for example, at least one material from the following group of materials: silver, gold, nickel, platinum, palladium, vanadium, molybdenum, tin, copper, arsenic, antimony, gallium, zinc, aluminum, niobium and / or tantalum, each individually and / or in combination comprising 0.001% to 10% by weight of the alloy.In various embodiments, the leadframe may have a leadframe coating, which may, for example, comprise at least one material from the following group of materials: silver, gold, nickel, platinum, palladium, vanadium, molybdenum, tin, copper, arsenic, antimony, gallium, zinc, aluminum, niobium, tantalum, phosphorus, silver, nickel, and / or nickel-phosphorus in elemental form and / or in the form of a nitride and / or in the form of an oxide, wherein the at least one material from the group of materials may individually or in combination constitute the leadframe coating; wherein the leadframe coating is configured to be in contact with the solder alloy. In various embodiments, the leadframe may have a leadframe coating, which may comprise copper in combination with nickel and / or nickel-phosphorus; wherein the leadframe coating is configured to be in contact with the solder alloy.In various embodiments, the thickness of the leadframe coating may be between 100 nm and 3 µm. In various embodiments, the chip may have a chip backside 820, which may, for example, comprise at least one material from the following group of materials: aluminum, titanium, nickel, vanadium, and / or silver; wherein the chip backside 820 is configured to be in contact with the solder alloy.

[0059] In various embodiments, an assembly is provided. The assembly may include a chip; a solder alloy configured to attach the chip to a lead frame; the solder alloy includes zinc and tin, wherein the zinc may comprise 10% to 91% by weight of the alloy. In various embodiments, the solder alloy may be represented by the chemical formula Zn 40 Sn 60In various embodiments, the zinc may comprise 10% to 15% of the alloy by weight. In various embodiments, the alloy may further comprise, for example, a material from the following group of materials: silver, gold, nickel, platinum, palladium, vanadium, molybdenum, tin, copper, arsenic, antimony, gallium, zinc, niobium, and / or tantalum, each individually and / or in combination comprising 0.001% to 10% of the alloy by weight.In various embodiments, the leadframe may further comprise a leadframe coating, which may, for example, comprise at least one material from the following group of materials: silver, gold, nickel, platinum, palladium, vanadium, molybdenum, tin, copper, arsenic, antimony, gallium, zinc, aluminum, niobium, tantalum, phosphorus, silver, nickel, and / or nickel-phosphorus in elemental form and / or in the form of a nitride and / or in the form of an oxide, wherein the at least one material from the group of materials may individually or in combination constitute the leadframe coating; wherein the leadframe coating is configured to be in contact with the solder alloy. In various embodiments, the leadframe may comprise a leadframe coating, which may comprise copper in combination with nickel and / or nickel-phosphorus; wherein the leadframe coating is configured to be in contact with the solder alloy.In various embodiments, a thickness of the leadframe coating may be between 100 nm and 3 µm. In various embodiments, the chip may have a chip backside 820, which may, for example, comprise at least one material from the following group of materials: aluminum, titanium, nickel, vanadium, and / or silver; wherein the chip backside 820 is configured to be in contact with the solder alloy.

[0060] In various embodiments, an assembly is provided. The assembly may comprise a chip; a solder alloy suitable for attaching the chip to a lead frame; the solder alloy comprises zinc and silver, wherein zinc comprises 26% to 98% by weight of the alloy. In various embodiments, zinc may comprise 83% to 99% by weight of the alloy. In various embodiments, the alloy may further comprise, for example, at least one of the following group of materials: silver, gold, nickel, platinum, palladium, vanadium, molybdenum, tin, copper, arsenic, antimony, gallium, zinc, aluminum, niobium, and / or tantalum, each individually and / or in combination comprising 0.001% to 10% by weight of the alloy.In various embodiments, the leadframe may have a leadframe coating, which may, for example, comprise at least one material from the following group of materials: silver, gold, nickel, platinum, palladium, vanadium, molybdenum, tin, copper, arsenic, antimony, gallium, zinc, aluminum, niobium, tantalum, phosphorus, silver, nickel, and / or nickel-phosphorus in elemental form and / or in the form of a nitride and / or in the form of an oxide, wherein the at least one material from the group of materials may individually or in combination constitute the leadframe coating; wherein the leadframe coating is configured to be in contact with the solder alloy. In various embodiments, the leadframe may have a leadframe coating, which may comprise copper in combination with nickel and / or nickel-phosphorus; wherein the leadframe coating is configured to be in contact with the solder alloy.In various embodiments, the thickness of the leadframe coating is between 100 nm and 3 µm. In various embodiments, the chip may have a chip backside 820, which may, for example, comprise at least one material from the following group of materials: aluminum, titanium, nickel, vanadium, and / or silver; wherein the chip backside 820 is configured to be in contact with the solder alloy.

[0061] In various embodiments, an assembly is provided. The assembly may include a chip; a solder alloy configured to attach the chip to a lead frame; the solder alloy comprises zinc and copper, wherein zinc may comprise 80% to 98% by weight of the alloy. In various embodiments, zinc may comprise 88% to 99% by weight of the alloy. In various embodiments, the alloy may further comprise, for example, at least one of the following group of materials: silver, gold, nickel, platinum, palladium, vanadium, molybdenum, tin, copper, arsenic, antimony, gallium, zinc, aluminum, niobium, or tantalum, each individually and / or in combination comprising 0.001% to 10% by weight of the alloy.In various embodiments, the leadframe may have a leadframe coating, which may, for example, comprise at least one material from the following group of materials: silver, gold, nickel, platinum, palladium, vanadium, molybdenum, tin, copper, arsenic, antimony, gallium, zinc, aluminum, niobium, tantalum, phosphorus, silver, nickel, and / or nickel-phosphorus in elemental form and / or in the form of a nitride and / or in the form of an oxide, wherein the at least one material from the group of materials may individually or in combination constitute the leadframe coating; wherein the leadframe coating is configured to be in contact with the solder alloy. In various embodiments, the leadframe may have a leadframe coating comprising copper in combination with nickel and / or nickel-phosphorus; wherein the leadframe coating is configured to be in contact with the solder alloy.In various embodiments, a thickness of the leadframe coating is between 100 nm and 3 µm. In various embodiments, the chip may have a chip backside 820, which may, for example, comprise at least one material from the following group of materials: aluminum, titanium, nickel, vanadium, and / or silver; wherein the chip backside 820 is configured to be in contact with the solder alloy.

[0062] While the invention has been particularly shown and described with reference to specific embodiments, it will be understood by those skilled in the art that various changes in form and details may be made without departing from the spirit and scope of the invention as defined by the appended claims. The scope of the invention is therefore indicated by the appended claims, and all changes which come within the meaning and range of equivalents of the claims are therefore intended to be embraced.

Claims

[1] Solder alloy comprising: Zinc, aluminum, magnesium and gallium, wherein the aluminum comprises 8% to 20% by weight of the alloy, the magnesium comprises 0.5% to 20% by weight of the alloy, and the gallium comprises 0.5% to 20% by weight of the alloy, and the remainder of the alloy comprises zinc. [2] Solder alloy according to claim 1, wherein the solder alloy has the chemical formula ZnAl 4,5 Ga1Mg1 or by the chemical formula ZnAl 12 Ga1Mg1 is represented. [3] Solder alloy according to claim 1, wherein the solder alloy is formed as a solder wire. [4] Solder alloy comprising: Zinc, aluminum, tin and magnesium, wherein the aluminum comprises greater than 8% to 30% by weight of the alloy, the magnesium comprises greater than 0.5% to 20% by weight of the alloy and the tin comprises 0.5% to 6.5% by weight of the alloy and the remainder of the alloy comprises zinc. [5] The solder alloy according to claim 4, wherein the solder alloy is represented by the chemical formula ZnAl4Sn2Mg1. [6] Solder alloy comprising: Zinc, aluminum, germanium and gallium, wherein the aluminum comprises 1% to 30% by weight of the alloy, the germanium comprises 0.5% to 20% by weight of the alloy, and the gallium comprises 0.5% to 20% by weight of the alloy, and the remainder of the alloy comprises zinc. [7] A solder alloy according to any one of the preceding claims, wherein the alloy further comprises at least one material from the following group of materials: silver, gold, nickel, platinum, palladium, vanadium, molybdenum, tin, copper, arsenic, antimony, gallium, zinc, aluminum, niobium and / or tantalum, each individually and / or in combination comprising by weight from 0.001% to 10% of the alloy. [8] Arrangement comprising: a chip; a solder alloy configured to attach the chip to a lead frame; the solder alloy comprising: Zinc, aluminum, and germanium, with aluminum comprising 1% to 20% by weight of the alloy, germanium comprising 1% to 20% by weight of the alloy, and the remainder of the alloy being zinc. [9] The assembly of claim 8, wherein the solder alloy is represented by one of the following chemical formulas: ZnAl5Ge3; ZnAl 12 Ge3; ZnAl6Ge3; or ZnAl6Ge5. [10] Arrangement according to claim 8, wherein the chip has a chip backside (820) comprising at least one material from the following group of materials: Aluminium, titanium, nickel, vanadium and / or silver, wherein the chip backside (820) is designed to be in contact with the solder alloy. [11] Arrangement comprising: a chip; a solder alloy for attaching the chip to a lead frame; the solder alloy comprises zinc, aluminum and magnesium, with the aluminum making up 1% to 20% by weight of the alloy, the magnesium making up 1% to 20% by weight of the alloy and the remainder of the alloy being zinc. [12] Arrangement comprising: a chip; a solder alloy configured to attach the chip to a lead frame; The solder alloy contains zinc and tin, with zinc accounting for 10% to 91% of the alloy by weight. [13] Arrangement according to claim 12, wherein the solder alloy has the chemical formula Zn 40 Sn 60 is represented. [14] Arrangement comprising: a chip; a solder alloy configured to attach the chip to a lead frame; The solder alloy contains zinc and silver, with the zinc accounting for 26% to 98% of the alloy by weight. [15] An assembly according to any preceding claim, wherein the alloy further comprises at least one material selected from the group consisting of silver, gold, nickel, platinum, palladium, vanadium, molybdenum, tin, copper, arsenic, antimony, gallium, zinc, aluminum, niobium, and / or tantalum, each individually and / or in combination comprising by weight from 0.001% to 10% of the alloy. [16] Arrangement comprising: a chip; a solder alloy configured to attach the chip to a lead frame; The solder alloy contains zinc and copper, with zinc accounting for 80% to 98% of the alloy by weight. [17] Arrangement according to claim 11, 12 or 16, wherein the lead frame has a lead frame coating comprising copper in combination with nickel and / or nickel phosphorus; wherein the leadframe coating is configured to be in contact with the solder alloy. [18] The device according to claim 17, wherein a thickness of the leadframe coating is between 100nm and 3µm.

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