A method for preparing a high-erosion-resistant and high-conductivity bonded thick copper wire

Abstract

The application discloses a preparation method of high-corrosion-resistance and high-conductivity bonded thick copper wire and relates to the technical field of bonding wire. In order to improve the corrosion resistance of the bonding wire, the bonding wire is improved through a modification mode of pure copper material; through the mode of adding graphene, micro-alloyed graphene copper material is formed, the corrosion potential of the bonding wire is greatly improved, the bonding wire has good heat dissipation performance and high-temperature conductivity, accumulation and temperature rise of heat in the bonding wire are avoided, and the service performance of the bonding wire is improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of bonding wires, and particularly relates to a high-corrosion-resistance and high-conductivity bonded thick copper wire and a production process thereof. BACKGROUND

[0002] Pure copper wire has better conductive and heat conductive performances than aluminum wire, can effectively reduce temperature rise and improve current carrying capacity, and is the future development direction of chip miniaturization and large-current high-power transmission. However, copper has higher hardness than aluminum, is easy to be oxidized under high-temperature or high-humidity conditions, and the oxide has higher hardness, which brings challenges to wedge bonding process, is easy to cause damage (Cratering) to a chip pad, is easy to form unstable copper-aluminum intermetallic compound (IMC) at a copper-aluminum bonding interface compared with an aluminum-aluminum bonding interface, and needs strict atmosphere protection during storage and use.

[0003] In order to realize protection of the copper core material, current mainstream technologies mostly use oxygen-free copper as the core material, deposit a uniform palladium layer on the surface of the core material through electroplating or chemical plating, so as to avoid oxidation and other phenomena of the copper wire and inhibit the growth of copper-aluminum interface IMC; but after the coating is damaged, the original cell reaction is easy to occur between the palladium layer and the copper core, which further seriously aggravates the decline of product reliability and affects product use.

[0004] Under the condition of continuous power supply, hydrogen embrittlement caused by electroplating will cause pores or cracks in the wire and the plating layer; secondly, the core material will be oxidized and corroded under the condition of power supply, causing the formation of oxide film on the wire surface, so that the wire resistance sharply rises, affecting the conductivity and reliability of the wire.

[0005] Therefore, it is a technical problem to be solved in the field to develop a new thick copper bonding wire which has high current carrying capacity, excellent heat dissipation performance, high reliability and good process compatibility. SUMMARY

[0006] The application aims to provide a preparation method of a high-corrosion-resistance and high-conductivity bonded thick copper wire.

[0007] The application provides a preparation method of a high-corrosion-resistance and high-conductivity bonded thick copper wire, which comprises the following steps:

[0008] S1. preparing micro-alloyed graphene copper;

[0009] S11. dispersing graphene raw material in water, and mixing Cu 2+The ion generation adsorption reaction is reduced by using a strong base to obtain a mixed powder material of copper and reduced graphene oxide, and the copper and the reduced graphene oxide form a molecular layer combination; the composite powder material is placed in a hydrogen reaction furnace to be reduced into a reduced graphene oxide copper powder material; the reduced graphene oxide copper powder material is pressed into a blank and placed in an SPS sintering furnace, protected by an argon atmosphere, and then heated to 900-1200°C at a rate of 90-300°C / min after a pressure of 100-1000kN is applied to the blank, and then the blank is sintered into a block and cooled to room temperature in the furnace to obtain a graphene copper alloy original ingot;

[0010] S12. The graphene copper alloy original ingot is mixed with a reinforcing metal material and pure copper in a certain proportion, and is smelted by electromagnetic induction heating to 1050-1250°C in an argon atmosphere, and then the smelted metal liquid is continuously cast into a mother rod with a diameter of 8mm after being stirred and mixed for 10s-15min;

[0011] S13. The mother rod is subjected to multi-pass wire drawing extension treatment until the diameter of the mother rod is 700-2000μm to obtain a micro-alloyed graphene copper mother copper wire;

[0012] S2. The micro-alloyed graphene copper mother copper wire is subjected to surface copper stripping treatment by using a direct current of 50-500mA / dm 2 , and a graphene enrichment layer is formed on the surface through the electric stripping treatment; and the treated mother copper wire is immediately subjected to surface passivation treatment by using a benzotriazole solution; and the treated mother copper wire is drawn to 75-500μm by using a multi-pass wire drawing method (the reduction rate between passes is 5-15%) to obtain a micro-alloyed graphene copper wire.

[0013] S3. The micro-alloyed graphene copper wire is subjected to annealing treatment at an annealing temperature of 250-600°C and an annealing time of 0.5-3.5h to obtain a high-corrosion-resistance high-conductivity bonding copper wire.

[0014] The diameter of the obtained high-corrosion-resistance high-conductivity bonding copper wire is 75-1000μm, and the high-corrosion-resistance high-conductivity bonding copper wire is made of a micro-alloyed graphene copper material, and the graphene is uniformly distributed in the micro-alloyed graphene copper material and can be applied to wedge bonding.

[0015] Further, the graphene can be one or more combinations selected from the following forms: single-layer or few-layer graphene oxide (Graphene Oxide), single-layer or few-layer reduced graphene oxide (rGO).

[0016] In the micro-alloyed graphene copper material, the proportion of graphene is 100-8000ppm, and the proportion of the reinforcing metal material is 0-5000ppm; and the reinforcing metal material is any one or more of Ag, Pd, Au, Pt, Li, P, Ca, Ni, Be, Y, La, Ce, Zr, In, Ge, and Sc.

[0017] Preferably, the micro-alloyed graphene copper contains 500-3000 ppm graphene and 0-3000 ppm reinforcing metal material; the reinforcing metal material is any one or more of Au, Pd, In, P, Ni, Ca, Li, Sc; wherein Au, Pd, Ni, In have an anticorrosion effect, Li and P mainly have an oxygen removal effect, and Ca mainly modifies the spherical shape; rare earth elements can have an anticorrosion effect.

[0018] When any one of P, Li and Sc is contained in the reinforcing metal material, the single-component addition amount of P, Li and Sc is 0-300 ppm.

[0019] Compared with the prior art, the application has the following beneficial effects:

[0020] In order to improve the corrosion resistance of the bonding wire, the core material is modified and surface treatment is performed on the bonding wire; the pure copper material is modified to improve the corrosion resistance of the bonding wire; graphene is added to form a micro-alloyed graphene copper material, which greatly improves the corrosion potential of the bonding wire and has good heat dissipation performance and high-temperature electrical conductivity, thereby avoiding the accumulation of heat in the bonding wire and improving the use performance of the bonding wire.

[0021] The core material is improved by adding graphene oxide to the core layer, and then calcining the core material; in this way, the metal covalent bonds formed between graphene and the copper base material are uniformly distributed, thereby greatly improving the corrosion potential of the core material and reducing the corrosion current and halogen corrosion weight loss; and because the metal covalent bonds formed between graphene oxide and the copper base material are uniformly distributed, the copper core has good heat dissipation performance and high-temperature electrical conductivity, so that the electrical conductivity of the bonding wire prepared by the application is more than 30% higher than that of traditional oxygen-free copper at 150 DEG C; graphene itself has extremely high heat dissipation performance, can accelerate heat conduction, avoid the accumulation of heat in the bonding wire, and further improve the high-temperature reliability of the product; and because of the addition of graphene, the grain structure in the copper core is improved, which can effectively inhibit the growth of intermetallic compounds and improve the working performance of the bonding wire.

[0022] By taking advantage of the difference in reaction potential between graphene oxide and copper, the copper on the surface that does not form a molecular bond with graphene is subjected to electrostripping treatment, a graphene enrichment layer is formed on the surface of the wire, and benzene propyl triazole passivation treatment is performed to improve the corrosion resistance of the wire; and the bonding wire is further annealed to eliminate processing stress, recombine grains, and improve the use performance of the bonding wire. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 A micro-alloyed graphene copper interface prepared in Embodiment 1 of the present application is shown in the figure; wherein 1 is a surface graphene enrichment layer; and 2 is micro-alloyed graphene copper;

[0024] Figure 2 A grain structure diagram of the micro-alloyed graphene copper prepared in Embodiment 1 of the present application. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0026] The preparation method of the present application is as follows:

[0027] A preparation method of a high-corrosion-resistant and high-conductivity bonded thick copper wire, comprising the following steps:

[0028] S1. preparing micro-alloyed graphene copper;

[0029] S11. placing the graphene copper mixed raw material in an 80℃ environment for drying for 8h under nitrogen atmosphere protection, then pressing it into a blank, placing it in an SPS sintering furnace, applying 800kN pressure to the blank body under argon atmosphere protection, and then heating it to 1050℃ at a rate of 100℃ / min, sintering it into a block, and then cooling it to room temperature in the furnace to obtain a graphene copper alloy ingot;

[0030] The preparation method of the graphene copper mixed raw material is as follows:

[0031] a. dispersing graphene oxide into ultrapure water, stirring and ultrasonic dispersing and washing for 1h, then filtering by suction filtration, repeating for 3 times, detecting the pH value of the filtrate, confirming that the pH value is in the range of 6.3-7 to be qualified, otherwise repeating the above steps to wash the graphene with ultrapure water until the pH value of the filtrate is qualified, then drying the washed graphene oxide in a nitrogen atmosphere, and cooling it for standby use;

[0032] b. dispersing the graphene oxide raw material in water, adsorbing with Cu 2+ ions to generate an adsorption reaction, and then reducing it into a graphene oxide copper composite powder material precipitate using a strong base, drying the precipitate in a nitrogen atmosphere, and cooling it for standby use;

[0033] c. placing the graphene oxide copper composite powder material in a hydrogen reaction furnace and reducing it into a reduced graphene oxide copper powder material at 500℃;

[0034] S12. The graphene copper alloy ingot is mixed with the reinforcing metal material and pure copper in proportion, melted by electromagnetic induction heating to 1200°C in an argon atmosphere, and after stirring and mixing for 3 min, the molten metal liquid is continuously cast into a mother bar with a diameter of 8 mm;

[0035] S13. The mother bar is subjected to multi-pass wire drawing elongation treatment until its diameter is 700-2000 μm, to obtain a micro-alloyed graphene copper mother copper wire;

[0036] S2. The micro-alloyed graphene copper mother copper wire is subjected to surface copper stripping treatment using a direct current of 50-500 mA / dm 2 , and immediately subjected to surface passivation treatment using a benzotriazole solution. The treated mother copper wire is drawn to 75-500 μm by multi-pass wire drawing (the reduction rate between passes is 5-15%), to obtain a micro-alloyed graphene copper wire;

[0037] S3. The micro-alloyed graphene copper wire is subjected to annealing treatment at an annealing temperature of 250-600°C and an annealing time of 0.5-3.5H, and after the annealing is completed, a high-corrosion-resistance high-conductivity bonding copper wire is obtained.

[0038] The reinforcing metal materials and the graphene content used in Examples 1-30 and Comparative Examples 1-5 are shown in the following table:

[0039]

[0040] The differences between Comparative Examples 1-5 and Example 1 are as follows:

[0041] Among them, Comparative Example 1 does not add graphene copper to the core material compared with Example 1;

[0042] Comparative Example 2 does not add graphene copper to the core material compared with Example 1, and does not perform intermediate annealing treatment;

[0043] Comparative Example 3 does not add graphene copper to the core material compared with Example 1, and does not perform surface electro-stripping treatment;

[0044] Comparative Example 4 does not add graphene copper to the core material compared with Example 1, and the reduction rate between passes during product drawing is 5% (Example 1 is 15%);

[0045] Comparative Example 5 does not add graphene copper to the core material compared with Example 1, and an organic protective layer is added to the surface, and the composition of the organic protective layer is methyl benzotriazole 0.01%+ dispersant 0.01%+ water compounded as an inhibitor in mass percentage, and the wire is soaked and dried to form a film.

[0046] The above examples and comparative examples are subjected to performance detection;

[0047] High temperature oxidation resistance test: the core material is processed to 10 mil, KS PowerFusion wire bonding machine is used, 100 wires are bonded to aluminum plate, and after welding, it is placed in a 150°C oven for 2 minutes; 20 times optical microscope is used to check the color of the wire surface. The wire appears black oxidation spot is unqualified; the wire color is dark red is general; the wire color is light red is qualified; the wire color is mostly bright yellow, the number of red is <5% is good; the wire is all bright yellow is excellent.

[0048] Tension test: the core material is processed to 10 mil, KS PowerFusion wire bonding machine is used, 100 wires are bonded to aluminum plate, and after bonding, DAGE STELLAR 4000 multifunctional welding strength tester is used to measure the tensile force of the welding spot, the greater the tensile force is the better; the tensile force is less than 120g is unqualified; greater than 120g is general, greater than 140g is qualified, greater than 160g is good, greater than 200g is excellent.

[0049] Shear force test: the core material is processed to 10 mil, KS PowerFusion wire bonding machine is used, 100 wires are bonded to aluminum plate, and after bonding, DAGE STELLAR 4000 multifunctional welding strength tester is used to measure the shear force of the welding spot, the greater the shear force is the better; the shear force test is less than 210g is unqualified, greater than 210g is general, greater than 240g is qualified, greater than 270g is good, greater than 300g is excellent.

[0050] Chisel wear test: the core material is processed to 10 mil, KS PowerFusion wire bonding machine is used, normal wire bonding is carried out, after 10W points are bonded, high power microscope is used to check the appearance of the welding spot, and SEM is used to observe the wear appearance of the chisel edge, W size wear is greater than 1.5 times is unqualified; less than 1.5 times is general, 1.3 times or less is qualified, 1.2 times or less is good, 1.1 times or less is excellent.

[0051] Hardness test: the core material is processed to 10 mil, HV micro Vickers hardness tester is used, hardness higher than 100Hv is unqualified; hardness lower than 100Hv is general; hardness lower than 90Hv is qualified; hardness lower than 80Hv is good, hardness lower than 70Hv is excellent.

[0052] HTSL test: the core material is processed to 10 mil, KS PowerFusion wire bonding machine is used, normal wire bonding is carried out after plastic packaging, 45pcs are subjected to high temperature storage life test (200°C 144H), and it is required that 45pcs are qualified in OS open short circuit test after completing the acceleration test; unqualified within 72H; qualified within 72H is general, qualified within 96H is qualified, qualified within 120H is good, and qualified within 144H is excellent.

[0053] Conductivity test: 1 m of finished wire is cut, the diameter is measured by micrometer, and then the resistance value is measured at room temperature 20°C and 100°C respectively: the resistance at room temperature is greater than 2.4 μΩ.cm is unqualified; the resistance at room temperature is lower than 1.9 μΩ.cm and the resistance at high temperature is lower than 2.4 μΩ.cm is general; the resistance at room temperature is lower than 1.85 μΩ.cm and the resistance at high temperature is lower than 2.3 μΩ.cm is qualified; the resistance at room temperature is lower than 1.8 μΩ.cm and the resistance at high temperature is lower than 2.2 μΩ.cm is good; the resistance at room temperature is lower than 1.75 μΩ.cm and the resistance at high temperature is lower than 2.0 μΩ.cm is excellent.

[0054] The test results are shown from left to right, from bad to good: X→△→□→○→◎;

[0055] The test results are shown in the following table

[0056]

[0057] It is apparent to those skilled in the art that the present application is not limited to the details of the foregoing exemplary embodiments, and that the present application can be carried out in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, it is to be understood that the embodiments are to be considered exemplary only, and are non-limiting, the scope of the application being defined by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope. No reference signs in the claims shall be construed as limiting the claim being referred to.

Claims

1. A method for preparing a high corrosion resistant and high conductive bonded thick copper wire, characterized by, The micro-alloyed graphene copper wire is treated by surface copper stripping to form a graphene enrichment layer on the surface, and then is passivated by benzotriazole and drawn into a wire, and the specific steps are as follows: S1. Preparation of micro-alloyed graphene copper: S11. Dispersing the graphene raw material in water, and reacting with Cu 2+ ions to adsorb, and then reducing with a strong base to obtain a mixed powder of copper and reduced graphene oxide; placing the mixed powder in a hydrogen reaction furnace to reduce to a reduced graphene oxide copper powder; pressing into a blank, placing in an SPS sintering furnace, and sintering under an argon atmosphere protection, applying a pressure of 100-1000 kN to the blank, and then heating at a rate of 90-300 ℃ / min to 900-1200 ℃, and after sintering into a block, cooling to room temperature in the furnace to obtain a graphene copper alloy ingot; S12. Mix the graphene copper alloy original ingot with the reinforcing metal material and pure copper in a certain proportion, melt under argon atmosphere protection by electromagnetic induction heating to 1050-1250℃, and stir and mix for 10s-15min, then cast the molten metal liquid into a 8mm diameter mother bar; S13. Perform multi-pass drawing extension treatment on the mother bar until its diameter is 700-2000μm to obtain a micro-alloyed graphene copper mother copper wire; S2. Surface copper stripping treatment is performed on the micro-alloyed graphene copper mother copper wire using 50-500 mA / dm 2 of direct current, and a graphene enrichment layer is formed on the surface through the electric stripping treatment; and immediately surface passivation treatment is performed using a benzotriazole solution; and the treated mother copper wire is drawn to 75-500 μm using a multi-pass drawing method to obtain a micro-alloyed graphene copper wire; S3. Annealing treatment is performed on the micro-alloyed graphene copper wire, the annealing temperature is 250-600℃, and the annealing time is 0.5-3.5h, and after the annealing is completed, a high corrosion-resistant and high-conductive bonding copper wire is obtained.

2. The method of claim 1, wherein the high-etch-resistant, high-conductive, bonded, bulk copper wire is prepared by the steps of: The micro-alloyed graphene copper contains 100-8000ppm of graphene and 0-5000ppm of reinforcing metal material; ​ The reinforcing metal material is any one or more of Ag, Pd, Au, Pt, Li, P, Ca, Ni, Be, Y, La, Ce, Zr, In, Ge, and Sc.

3. The method for preparing high corrosion-resistant and high conductivity bonding coarse copper wire as described in claim 2, characterized in that, The micro-alloyed graphene copper contains 500-3000ppm of graphene and 0-3000ppm of reinforcing metal; and the reinforcing metal material is any one or more of Au, Pd, In, P, Ni, Ca, Li, and Sc.

4. The method for preparing high corrosion-resistant and high conductivity bonding coarse copper wire as described in claim 3, characterized in that, When the reinforcing metal material contains any one of P, Li, and Sc, the single-component addition amount of P, Li, and Sc is 0-300ppm.

5. The method for preparing high corrosion-resistant and high conductivity bonding coarse copper wire as described in claim 1, characterized in that, The reduction rate between passes during the multi-pass drawing in S2 is 5-15%.

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