CN109686714B - Silver alloy wire with composite palladium-tungsten coating and manufacturing method thereof - Google Patents
Silver alloy wire with composite palladium-tungsten coating and manufacturing method thereof Download PDFInfo
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- CN109686714B CN109686714B CN201811530789.6A CN201811530789A CN109686714B CN 109686714 B CN109686714 B CN 109686714B CN 201811530789 A CN201811530789 A CN 201811530789A CN 109686714 B CN109686714 B CN 109686714B
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- 229910052721 tungsten Inorganic materials 0.000 title claims abstract description 105
- 239000010937 tungsten Substances 0.000 title claims abstract description 105
- 229910001316 Ag alloy Inorganic materials 0.000 title claims abstract description 41
- 239000002131 composite material Substances 0.000 title claims abstract description 39
- 239000011248 coating agent Substances 0.000 title claims abstract description 30
- 238000000576 coating method Methods 0.000 title claims abstract description 30
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 21
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims abstract description 178
- 229910052763 palladium Inorganic materials 0.000 claims abstract description 89
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims abstract description 66
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical group [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims abstract description 44
- 229910052709 silver Inorganic materials 0.000 claims abstract description 42
- 239000004332 silver Substances 0.000 claims abstract description 42
- 229910052802 copper Inorganic materials 0.000 claims abstract description 7
- 229910052791 calcium Inorganic materials 0.000 claims abstract description 5
- 229910052742 iron Inorganic materials 0.000 claims abstract description 3
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 3
- 238000007747 plating Methods 0.000 claims description 65
- 238000000137 annealing Methods 0.000 claims description 45
- 238000000034 method Methods 0.000 claims description 34
- 230000008569 process Effects 0.000 claims description 21
- UYKQQBUWKSHMIM-UHFFFAOYSA-N silver tungsten Chemical compound [Ag][W][W] UYKQQBUWKSHMIM-UHFFFAOYSA-N 0.000 claims description 19
- 238000010438 heat treatment Methods 0.000 claims description 14
- WPYMKLBDIGXBTP-UHFFFAOYSA-N benzoic acid Chemical compound OC(=O)C1=CC=CC=C1 WPYMKLBDIGXBTP-UHFFFAOYSA-N 0.000 claims description 12
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 claims description 12
- 239000002994 raw material Substances 0.000 claims description 9
- NWZSZGALRFJKBT-KNIFDHDWSA-N (2s)-2,6-diaminohexanoic acid;(2s)-2-hydroxybutanedioic acid Chemical compound OC(=O)[C@@H](O)CC(O)=O.NCCCC[C@H](N)C(O)=O NWZSZGALRFJKBT-KNIFDHDWSA-N 0.000 claims description 8
- IKDUDTNKRLTJSI-UHFFFAOYSA-N hydrazine monohydrate Substances O.NN IKDUDTNKRLTJSI-UHFFFAOYSA-N 0.000 claims description 8
- USFZMSVCRYTOJT-UHFFFAOYSA-N Ammonium acetate Chemical compound N.CC(O)=O USFZMSVCRYTOJT-UHFFFAOYSA-N 0.000 claims description 6
- 239000005695 Ammonium acetate Substances 0.000 claims description 6
- 239000005711 Benzoic acid Substances 0.000 claims description 6
- 235000019257 ammonium acetate Nutrition 0.000 claims description 6
- 229940043376 ammonium acetate Drugs 0.000 claims description 6
- 235000010233 benzoic acid Nutrition 0.000 claims description 6
- 239000008139 complexing agent Substances 0.000 claims description 6
- 238000009792 diffusion process Methods 0.000 claims description 6
- 238000009713 electroplating Methods 0.000 claims description 6
- 229910001961 silver nitrate Inorganic materials 0.000 claims description 6
- XMVONEAAOPAGAO-UHFFFAOYSA-N sodium tungstate Chemical compound [Na+].[Na+].[O-][W]([O-])(=O)=O XMVONEAAOPAGAO-UHFFFAOYSA-N 0.000 claims description 6
- 238000003723 Smelting Methods 0.000 claims description 3
- 239000003638 chemical reducing agent Substances 0.000 claims description 3
- 150000002500 ions Chemical class 0.000 claims description 3
- 239000012299 nitrogen atmosphere Substances 0.000 claims description 3
- 238000004806 packaging method and process Methods 0.000 abstract description 4
- 230000008901 benefit Effects 0.000 abstract description 3
- 239000004065 semiconductor Substances 0.000 abstract description 3
- 239000000243 solution Substances 0.000 description 13
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 7
- 238000005491 wire drawing Methods 0.000 description 7
- 239000011575 calcium Substances 0.000 description 6
- 239000012298 atmosphere Substances 0.000 description 5
- 239000010949 copper Substances 0.000 description 5
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 4
- 125000004429 atom Chemical group 0.000 description 4
- 229910052782 aluminium Inorganic materials 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 238000003466 welding Methods 0.000 description 3
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 229910052737 gold Inorganic materials 0.000 description 2
- 239000010931 gold Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 239000003292 glue Substances 0.000 description 1
- 238000007542 hardness measurement Methods 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000007373 indentation Methods 0.000 description 1
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 239000000565 sealant Substances 0.000 description 1
- 229910000679 solder Inorganic materials 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- -1 therefore Chemical compound 0.000 description 1
- 238000004073 vulcanization Methods 0.000 description 1
Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/48—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor
- H01L23/488—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor consisting of soldered or bonded constructions
- H01L23/49—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor consisting of soldered or bonded constructions wire-like arrangements or pins or rods
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/02—Making non-ferrous alloys by melting
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C5/00—Alloys based on noble metals
- C22C5/06—Alloys based on silver
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
- C23C18/48—Coating with alloys
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
- C23C28/02—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material
- C23C28/021—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material including at least one metal alloy layer
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D3/00—Electroplating: Baths therefor
- C25D3/02—Electroplating: Baths therefor from solutions
- C25D3/50—Electroplating: Baths therefor from solutions of platinum group metals
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D7/00—Electroplating characterised by the article coated
- C25D7/06—Wires; Strips; Foils
- C25D7/0607—Wires
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/48—Manufacture or treatment of parts, e.g. containers, prior to assembly of the devices, using processes not provided for in a single one of the subgroups H01L21/06 - H01L21/326
- H01L21/4814—Conductive parts
- H01L21/4885—Wire-like parts or pins
- H01L21/4889—Connection or disconnection of other leads to or from wire-like parts, e.g. wires
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Power Engineering (AREA)
- Computer Hardware Design (AREA)
- General Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Wire Bonding (AREA)
- Electroplating Methods And Accessories (AREA)
Abstract
A silver alloy wire with a composite palladium-tungsten coating is characterized by comprising a core wire and a composite palladium-tungsten coating coated outside the core wire; the core wire contains 8-100ppm of doping elements by weight, and the balance is silver; the doping element is one or the combination of more of Ca, Cu, Fe and Si; the composite palladium-tungsten coating consists of a palladium layer coated outside the core wire and a tungsten-containing silver layer coated outside the palladium layer. The invention also provides a manufacturing method of the silver alloy wire with the composite palladium-tungsten coating. The silver alloy wire with the composite palladium-tungsten coating has the advantages of low resistivity, high reliability and low hardness, and can be used for semiconductor packaging.
Description
Technical Field
The invention relates to a bonding wire, in particular to a silver alloy wire with a composite palladium-tungsten coating and a manufacturing method thereof.
Background
Bonding wires (bonding wires) are the main connection means for connecting a chip to an external package substrate (substrate) and/or a multilayer circuit board (PCB). The development trend of the bonding wire is mainly products with fine wire diameter, long workshop life (floor life) and high linear axis length from the application direction; from the chemical composition, copper wires (including bare copper wires, palladium-plated copper wires and gold-flash palladium-plated copper wires) are mainly used for replacing gold wires in the field of semiconductors, and silver wires and silver alloy wires are used for replacing gold wires in LED and partial IC packaging applications.
The main advantage of silver wire over gold wire is the low cost of the product. The main problems of the early silver alloy wires are that the surfaces of the wires are easy to be vulcanized and oxidized, so that the wire bonding performance and the high temperature and high humidity reliability (PCT, HAST) are affected, and in addition, serious electromigration problems are caused, so that the short circuit failure of the circuit is caused. The above problems can be improved by introducing palladium (Pd in an amount of 1-4%) into the silver wire, especially its high temperature and high humidity reliability (PCT, HAST) problem. The palladium plays roles of electromigration resistance, vulcanization resistance and reliability improvement in the wire, and the functions of the palladium on the surface and the interface are embodied, and the palladium is introduced into the silver alloy core wire, so that the method is simple, but the resistivity and the hardness of the wire are improved (the introduction of 3-4% of palladium into the silver alloy wire can cause the conductivity to be reduced, and the hardness of the wire is also improved).
Disclosure of Invention
The invention aims to solve the technical problem of providing a silver alloy wire with a composite palladium-tungsten plating layer and a manufacturing method thereof. The technical scheme is as follows:
a silver alloy wire with a composite palladium-tungsten coating is characterized by comprising a core wire and a composite palladium-tungsten coating coated outside the core wire; the core wire contains 8-100ppm of doping elements by weight, and the balance is silver; the doping element is one or the combination of more of Ca, Cu, Fe and Si; the composite palladium-tungsten coating consists of a palladium layer coated outside the core wire and a tungsten-containing silver layer coated outside the palladium layer.
Preferably, the palladium layer has a thickness of 10 to 30 nm and the tungsten-containing silver layer has a thickness of 8 to 15 nm, the thickness of the palladium layer is a thickness of a layered region having a molar content of palladium of more than 30% and a molar content of tungsten of less than 0.5%, and the thickness of the tungsten-containing silver layer is a thickness of a layered region having a molar content of tungsten of 0.5% or more.
It is worth mentioning that in the manufacturing process of the wire rod, after the surface of the core wire is plated with palladium, the heat treatment is performed, so that the palladium concentration of the palladium layer in the outer palladium plating layer is diffused to the inner silver layer, thereby the palladium concentration of the palladium layer is gradually decreased along the direction perpendicular to the surface of the wire rod and toward the bobbin (i.e. the palladium concentration is gradually decreased from the outside to the inside along the direction perpendicular to the surface of the wire rod and toward the bobbin). In addition, silver-plated tungsten is further treated outside the palladium layer, and then heat treatment is performed to promote the diffusion of tungsten into the palladium layer, so that in the surface region of the wire rod, the concentration of tungsten is gradually reduced along the direction perpendicular to the surface of the wire rod and toward the bobbin (i.e., the concentration of tungsten is gradually reduced from outside to inside along the direction perpendicular to the surface of the wire rod and toward the bobbin).
In the ball burning process of ball bonding (EFO), arc high voltage breaks through protective gas (95% nitrogen +5% hydrogen) in ball bonding, a large amount of heat is released, the tail end of a bonding wire is melted, a round ball, namely a Free air ball (FAB for short), is formed at the tail end of the bonding wire due to the action of surface tension, palladium can be melted into the main body of a silver alloy ball and disappears on the surface of the FAB due to the fact that palladium can form a solid solution with silver, therefore, palladium is difficult to be uniformly distributed around the FAB, especially cannot be enriched on the portion of the FAB bottom in contact with an IC aluminum pad, however, the enrichment of palladium in the area is beneficial to the reliability of a subsequent welding point. The composite palladium-tungsten coating can effectively promote the enrichment of palladium and tungsten on the surface of FAB, particularly at the bottom of FAB, on one hand, tungsten is used as metal with the highest melting point and has certain solubility in palladium, and the dissolution restricts the process of diffusion of palladium into FAB in the ball burning process, so that the palladium and the tungsten are uniformly distributed around the FAB; on the other hand, because the densities of palladium and tungsten are higher than that of silver, the palladium and tungsten are preferentially concentrated at the bottom of FAB, so that the diffusion of aluminum on the aluminum pad to the FAB can be delayed, and the reliability of the product is improved.
In addition, in the silver alloy wire with the composite palladium-tungsten coating, the palladium layer on the surface of the core wire is only 10-30 nanometers, the thickness of the tungsten-containing silver layer is only 8-15 nanometers, the tungsten content in the tungsten-containing silver layer is low (the molar concentration of tungsten is generally between 0.5 and 0.6 percent), and most of the rest is silver, so the silver alloy wire with the composite palladium-tungsten coating has improved conductivity (reduced resistivity) and greatly reduced hardness. The invention successfully realizes that palladium and tungsten are kept on the surface of FAB when the ball bonding is carried out by skillfully utilizing the solubility of tungsten in palladium and the high-melting-point characteristic of tungsten, thereby ensuring the reliability of a wire rod, simultaneously improving the conductivity of the wire rod and reducing the hardness of the wire rod.
In a specific scheme, a palladium plating layer is formed on a core wire by electroplating, a silver-tungsten plating layer is formed on the surface of the palladium plating layer by a chemical plating method (electroplating), and then the palladium plating layer and the silver-tungsten plating layer are mutually permeated by increasing the temperature (the wire can be subjected to heat treatment at the temperature of 500-700 ℃) to obtain the composite palladium-tungsten plating layer. Because of the particularity of tungsten, tungsten cannot be directly flash-plated on the palladium plating layer at present, but tungsten and silver need to be flash-plated on the palladium plating layer at the same time.
The invention also provides a manufacturing method of the silver alloy wire with the composite palladium-tungsten coating, which is characterized by sequentially comprising the following steps of:
(1) manufacture of core wire
(1-1) adding doping elements into a silver raw material in proportion, and obtaining a core wire rod with the diameter of 6-8mm through smelting and directional continuous drawing processes;
(1-2) drawing the core wire rod obtained in the step (1-1) to obtain a core wire with the diameter of 18-50 um;
(2) palladium plating
Performing palladium electroplating operation on the core wire obtained in the step (1-2) to form a palladium plating layer on the surface of the core wire;
(3) silver-plated tungsten
Uniformly plating a silver-tungsten plating layer on the surface of the palladium plating layer of the palladium-plated core wire in the step (2) to obtain a semi-finished wire;
(4) thermal diffusion
And (3) placing the semi-finished wire into an annealing furnace, and carrying out heat treatment under the nitrogen atmosphere, wherein the heat treatment temperature is between 500 ℃ and 700 ℃, so that atoms in the palladium plating layer and the silver-tungsten plating layer are diffused, and the silver alloy wire with the composite palladium-tungsten plating layer is obtained.
Preferably, the silver raw material used in step (1-1) is 4N silver containing less than 5ppm of oxygen.
In the step (1-2), the wire drawing process generally comprises four stages of rough drawing, medium rough drawing, fine drawing, micro drawing and the like. The total of the above annealing steps is carried out two or more times during and after the completion of drawing, and pure nitrogen gas or a mixed gas of nitrogen and hydrogen (preferably, a mixed gas of nitrogen and hydrogen consisting of 5 vol% of H) may be used for the annealing step2And 95% by volume of N2Composition) as an annealing atmosphere.
In the preferable step (2), the thickness of the palladium plating layer is between 15 and 35 nanometers; in the step (3), the thickness of the silver-tungsten coating is between 2 and 15 nanometers. After the heat treatment in the step (4), atoms in the palladium plating layer and the silver-tungsten plating layer are diffused, and the thickness of the formed palladium layer is 10-30 nanometers, and the thickness of the tungsten-containing silver layer is 8-15 nanometers.
Preferably, the silver-tungsten plating process in the step (3) is a flash plating process, and the method comprises the following steps: and (3) allowing the palladium-plated core wire in the step (2) to pass through the prepared silver-plated tungsten solution, and simultaneously enabling the length of the core wire immersed in the silver-plated tungsten solution to be greater than or equal to 1 meter (preferably 1-3 meters), wherein the residence time of the core wire in the silver-plated tungsten solution is greater than 1 second (preferably 3-9 seconds), so that a silver-tungsten coating is uniformly plated on the surface of the palladium coating.
Preferably, the silver-plated tungsten solution uses silver nitrate and sodium tungstate as a silver source and a tungsten source respectively, Hydrazine hydrate (Hydrazine-hydrate) as a reducing agent, benzoic acid as a main ion complexing agent, and ammonium acetate as a secondary complexing agent. More preferably, the silver nitrate concentration in the silver-plated tungsten solution is 0.01-0.05M (mol/L), the sodium tungstate concentration is 0.04-0.08M, the hydrazine hydrate concentration is 0.006-0.012M, the benzoic acid concentration is 0.30-0.36M, and the ammonium acetate concentration is 0.24-0.28M. The silver-plated tungsten solution is a hydrosolvent.
Preferably, in the step (4), the heat treatment time is 0.5 to 3 minutes.
Compared with the prior art, the silver alloy wire with the composite palladium-tungsten coating has the following beneficial effects:
(1) in the composite palladium-tungsten plating layer, the thickness of the palladium layer is 10-30 nanometers, and the thickness of the palladium plating layer film containing tungsten is 8-15 nanometers, so that palladium and tungsten are enriched at the bottom and the surface of FAB during ball burning, and the reliability of a welding wire is improved;
(2) compared with the prior art, the method greatly reduces the total consumption of palladium, concentrates palladium and tungsten on the surface of the wire, reduces the resistivity of the wire body, and reduces the hardness of the wire and the air free ball FAB).
In short, the silver alloy wire with the composite palladium-tungsten plating layer has the advantages of low resistivity, high reliability and low hardness, and can be used for semiconductor packaging.
Detailed Description
Examples
The silver alloy wire with the composite palladium-tungsten coating comprises a core wire and a composite palladium-tungsten coating coated outside the core wire; the core wire contains 8ppm of Ca by weight, and the balance is silver; the composite palladium-tungsten coating consists of a palladium layer coated outside the core wire and a tungsten-containing silver layer coated outside the palladium layer.
The manufacturing method of the silver alloy wire with the composite palladium-tungsten plating layer sequentially comprises the following steps:
(1) manufacture of core wire
(1-1) adding Ca into a silver raw material (the silver raw material is 4N silver (the purity is 99.99%) containing oxygen less than 5 ppm) in proportion, and carrying out smelting and directional continuous drawing processes to obtain a core wire rod with the diameter of 8 mm;
(1-2) drawing the core wire rod obtained in the step (1-1) to obtain a core wire with the diameter of 23 um;
carrying out primary annealing treatment (when the wire is drawn to the diameter of 100 um) in the wire drawing process, and adopting N in the annealing process2The effective length of the annealing furnace is 600mm, the annealing temperature is 400 ℃, and the annealing speed is 60 m/min;
carrying out primary annealing treatment after wire drawing is finished, wherein N is adopted in the annealing process2The effective length of the annealing furnace is 600mm, the annealing temperature is 400 ℃, and the annealing speed is 60 m/min;
(2) palladium plating
Performing palladium electroplating operation on the core wire obtained in the step (1-2) to form a palladium plating layer on the surface of the core wire, wherein the thickness of the palladium plating layer is 25 nanometers;
(3) silver-plated tungsten
Uniformly plating a silver-tungsten plating layer on the surface of the palladium plating layer of the palladium-plated core wire in the step (2) to obtain a semi-finished wire;
the step (3) adopts a flash plating process to plate silver tungsten, and the method comprises the following steps: allowing the core wire plated with palladium in the step (2) to pass through the prepared silver-plated tungsten solution (the temperature of the silver-plated tungsten solution is 40 ℃), simultaneously immersing the core wire in the silver-plated tungsten solution for 2 meters, and allowing the core wire to stay in the silver-plated tungsten solution for 6 seconds, so that a silver-tungsten plating layer with the thickness of 8nm is uniformly plated on the surface of the palladium plating layer;
silver nitrate and sodium tungstate are respectively used as a silver source and a tungsten source in the silver-plating tungsten solution, Hydrazine hydrate (Hydrazine-hydrate) is used as a reducing agent, benzoic acid is used as a main ion complexing agent, and ammonium acetate is used as an auxiliary complexing agent; the silver nitrate concentration in the silver-plated tungsten solution is 0.03M, the sodium tungstate concentration is 0.06M, the hydrazine hydrate concentration is 0.009M, the benzoic acid concentration is 0.33M, and the ammonium acetate concentration is 0.26M. The silver-plated tungsten solution is a hydrosolvent;
(4) thermal diffusion
And (3) putting the semi-finished wire into an annealing furnace, and carrying out heat treatment in a nitrogen atmosphere, wherein the heat treatment temperature is 600 ℃, and the heat treatment time is 1 minute, so that atoms in the palladium plating layer and the silver-tungsten plating layer are diffused, and the silver alloy wire with the composite palladium-tungsten plating layer is obtained.
And (4) after the atoms in the palladium plating layer and the silver-tungsten plating layer are diffused, the thickness of the formed palladium layer is 20 nanometers, and the thickness of the tungsten-containing silver layer is 10 nanometers.
Comparative example 1
The silver alloy bonding wire of the present comparative example contains by weight: 4.0 percent of palladium, 8ppm of Ca and the balance of silver.
In this comparative example, the method of manufacturing a silver alloy bonding wire includes the steps of:
(1) casting: adding palladium and calcium into the silver raw material according to the proportion, and obtaining a wire rod with the diameter of 8mm (millimeter) through an oriented continuous drawing process;
the silver raw material adopts silver with the purity of 99.99 percent;
(2) drawing: drawing the wire obtained in the step (1) to obtain a silver alloy bonding wire with the diameter of 23um (micrometer);
in the wire drawing process, performing primary intermediate annealing on the wire, wherein the intermediate annealing is performed when the wire is drawn to the diameter of 0.0877, N2 is used as an annealing atmosphere in the annealing process, the effective length of the annealing furnace is 600mm, the annealing temperature is 600 ℃, and the annealing speed is 90 m/min;
(3) and (3) final annealing: after wire drawing is finished, final annealing is carried out on the silver alloy bonding wire, N2 is used as an annealing atmosphere in the annealing process, the effective length of an annealing furnace is 600mm, the annealing temperature is 450 ℃, and the annealing speed is 100 m/min; the tension of the final annealed section of the wire was set at 0.3 grams.
Finally, annealing to obtain the silver alloy bonding wire.
Comparative example 2.
The silver alloy bonding wire of the comparative example comprises a core wire and a palladium coating coated outside the core wire; the core wire comprises by weight: ca 8ppm, and the balance being silver; the thickness of the palladium plating layer was 20 nm.
In this comparative example, the method of manufacturing a silver alloy bonding wire includes the steps of:
(1) casting: adding calcium into the silver raw material according to the proportion, and obtaining a wire rod with the diameter of 8mm (millimeter) through an oriented continuous drawing process;
the silver raw material adopts silver with the purity of 99.99 percent;
(2) drawing: drawing the wire rod obtained in the step (1) to obtain a core wire with the diameter of 23um (micrometer);
in the wire drawing process, performing primary intermediate annealing on the wire, wherein the intermediate annealing is performed when the wire is drawn to the diameter of 0.0877, N2 is used as an annealing atmosphere in the annealing process, the effective length of the annealing furnace is 600mm, the annealing temperature is 600 ℃, and the annealing speed is 90 m/min;
(3) and (3) final annealing: after wire drawing is finished, carrying out final annealing on the core wire, wherein N2 is used as an annealing atmosphere in the annealing process, the effective length of an annealing furnace is 600mm, the annealing temperature is 450 ℃, and the annealing speed is 100 m/min;
(4) electroplating palladium: and (4) carrying out electro-palladium plating treatment on the core wire drawn to the final size, wherein the thickness of a palladium layer is 20 nanometers, and thus obtaining the silver alloy bonding wire.
The wires obtained in the above examples, comparative examples 1 and 2 were tested, and the test results were as follows:
1. resistivity of
2. Hardness and Process Window
The wire was split longitudinally along the center of the axis and Vicker hardness measurements were then made on the longitudinal section of the wire. Each set of readings was averaged over ten measurements. Hardness was measured by the size of the indentation using an FM-810e micro Vickers hardness tester at a force of 1 gram for 15 seconds, and the results were as follows:
3. reliability of
And performing ball bonding of a first welding point by using three wires (23 microns), and then performing glue pouring and packaging. The High Temperature storage Test (HTS) was performed at 200 ℃ for 1000 hours, and the sealant was peeled off, and then the shear strength Test of the first solder joint was performed to evaluate the performance of the three wires in the High Temperature storage reliability. Shear strengths of less than 5 grams are poor, between 5 and 8 grams are good, and greater than 8 grams are excellent.
The results of the three wire shear strength tests are as follows:
Claims (10)
1. a silver alloy wire with a composite palladium-tungsten coating is characterized by comprising a core wire and a composite palladium-tungsten coating coated outside the core wire; the core wire contains 8-100ppm of doping elements by weight, and the balance is silver; the doping element is one or the combination of more of Ca, Cu, Fe and Si; the composite palladium-tungsten coating consists of a palladium layer coated outside the core wire and a tungsten-containing silver layer coated outside the palladium layer.
2. The silver alloy wire with a composite palladium-tungsten plating according to claim 1, characterized in that: the thickness of the palladium layer is 10-30 nanometers, the thickness of the tungsten-containing silver layer is 8-15 nanometers, the thickness of the palladium layer refers to the thickness of a layered region with the mole content of palladium being more than 30% and the mole content of tungsten being less than 0.5%, and the thickness of the tungsten-containing silver layer refers to the thickness of a layered region with the mole content of tungsten being more than 0.5%.
3. The method of manufacturing a silver alloy wire with a composite palladium-tungsten plating layer according to claim 1, characterized by comprising the following steps in this order:
(1) manufacture of core wire
(1-1) adding doping elements into a silver raw material in proportion, and obtaining a core wire rod with the diameter of 6-8mm through smelting and directional continuous drawing processes;
(1-2) drawing the core wire rod obtained in the step (1-1) to obtain a core wire with the diameter of 18-50 um;
(2) palladium plating
Performing palladium electroplating operation on the core wire obtained in the step (1-2) to form a palladium plating layer on the surface of the core wire;
(3) silver-plated tungsten
Uniformly plating a silver-tungsten plating layer on the surface of the palladium plating layer of the palladium-plated core wire in the step (2) to obtain a semi-finished wire;
(4) thermal diffusion
And (3) placing the semi-finished wire into an annealing furnace, and carrying out heat treatment under the nitrogen atmosphere, wherein the heat treatment temperature is between 500 ℃ and 700 ℃, so that atoms in the palladium plating layer and the silver-tungsten plating layer are diffused, and the silver alloy wire with the composite palladium-tungsten plating layer is obtained.
4. The method for manufacturing a silver alloy wire having a composite palladium-tungsten plating layer according to claim 3, characterized in that: in the step (2), the thickness of the palladium plating layer is 15-35 nanometers; in the step (3), the thickness of the silver-tungsten coating is between 2 and 15 nanometers.
5. The method for manufacturing the silver alloy wire with the composite palladium-tungsten coating according to claim 3, wherein the step (3) adopts a flash plating process to plate silver-tungsten, and the method comprises the following steps: and (3) allowing the core wire plated with palladium in the step (2) to pass through the prepared silver-plated tungsten solution, wherein the length of the core wire immersed in the silver-plated tungsten solution is greater than or equal to 1 m, and the residence time of the core wire in the silver-plated tungsten solution is greater than 1 second, so that a silver-tungsten coating is uniformly plated on the surface of the palladium coating.
6. The method for manufacturing a silver alloy wire having a composite palladium-tungsten plating layer according to claim 5, characterized in that: in the step (3), the length of the core wire simultaneously immersed in the silver-plated tungsten solution is 1-3 m, and the staying time of the core wire in the silver-plated tungsten solution is 3-9 seconds.
7. The method for producing a silver alloy wire having a composite palladium-tungsten plating layer according to claim 5 or 6, characterized in that: the silver-plated tungsten solution takes silver nitrate and sodium tungstate as a silver source and a tungsten source respectively, takes hydrazine hydrate as a reducing agent, takes benzoic acid as a main ion complexing agent, and takes ammonium acetate as an auxiliary complexing agent.
8. The method for manufacturing a silver alloy wire having a composite palladium-tungsten plating layer according to claim 7, wherein: the concentration of silver nitrate in the silver-plated tungsten solution is 0.01-0.05M, the concentration of sodium tungstate is 0.04-0.08M, the concentration of hydrazine hydrate is 0.006-0.012M, the concentration of benzoic acid is 0.30-0.36M, and the concentration of ammonium acetate is 0.24-0.28M.
9. The method for manufacturing a silver alloy wire having a composite palladium-tungsten plating layer according to claim 3, characterized in that: in the step (4), the heat treatment time is 0.5 to 3 minutes.
10. The method for producing a silver alloy wire having a composite palladium-tungsten plating layer according to claim 3 or 4, characterized in that: after the heat treatment in the step (4), atoms in the palladium plating layer and the silver-tungsten plating layer are diffused, the thickness of the formed palladium layer is 10-30 nanometers, the thickness of the tungsten-containing silver layer is 8-15 nanometers, the thickness of the palladium layer refers to the thickness of a layered region with the mole content of palladium being more than 30% and the mole content of tungsten being less than 0.5%, and the thickness of the tungsten-containing silver layer refers to the thickness of a layered region with the mole content of tungsten being more than 0.5%.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102437136A (en) * | 2011-11-16 | 2012-05-02 | 浙江佳博科技股份有限公司 | Bonding alloy wire and production technology thereof |
| CN103928418A (en) * | 2013-01-11 | 2014-07-16 | 英飞凌科技股份有限公司 | Bonding wire and method for producing a bond connection |
| EP2822029A1 (en) * | 2012-02-27 | 2015-01-07 | Nippon Micrometal Corporation | Power semiconductor device, method for manufacturing same, and bonding wire |
| CN106486455A (en) * | 2015-09-01 | 2017-03-08 | 光大应用材料科技股份有限公司 | Multi-plating silver wire and manufacturing method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102437136A (en) * | 2011-11-16 | 2012-05-02 | 浙江佳博科技股份有限公司 | Bonding alloy wire and production technology thereof |
| EP2822029A1 (en) * | 2012-02-27 | 2015-01-07 | Nippon Micrometal Corporation | Power semiconductor device, method for manufacturing same, and bonding wire |
| CN103928418A (en) * | 2013-01-11 | 2014-07-16 | 英飞凌科技股份有限公司 | Bonding wire and method for producing a bond connection |
| CN106486455A (en) * | 2015-09-01 | 2017-03-08 | 光大应用材料科技股份有限公司 | Multi-plating silver wire and manufacturing method thereof |
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