Copper alloy strip and its preparation method and application

Abstract

The present invention provides a copper alloy strip, a preparation method, and an application thereof, relating to the technical field of nonferrous metal processing. By optimizing the composition of the copper alloy strip and controlling the size and precipitation density of the primary phase, the copper alloy strip obtained by the present invention has low residual stress, high strength, high conductivity, and good resistance to high-temperature softening. The results of the embodiment show that the tensile strength σ of the copper alloy strip is b The alloy has a tensile strength of 540-700 MPa, a plastic elongation δ of 1-5%, an electrical conductivity of 75-85% IACS, a high-temperature softening temperature of 550-600°C, a macroscopic plate shape stability control of ≤1.0I, and a strip warping height of ≤2mm after chemical etching. Compared with the C19400 (Cu-Fe-P) alloy, it has higher strength and electrical conductivity, and has more excellent surface properties and electroplating properties after etching, which can meet the use requirements of the alloy strip for corrosion-resistant lead frames of extremely large-scale circuits.

Description

Technical Field

[0001] The present invention relates to the technical field of nonferrous metal processing, and in particular to a copper alloy strip and a preparation method and application thereof. Background Art

[0002] The development of high-strength and high-conductivity copper alloys has generally gone through three stages. The first stage, from the 1960s, was when copper was generally alloyed with elements that did not significantly reduce conductivity, such as Ag, Cd, As, Te, and Rb. The resulting materials had conductivity exceeding 90% IACS, but their strength and other properties were less than ideal. The second stage, from the 1970s onwards, began to select strengthening phase elements with low solid solution content and the ability to precipitate during aging. The use of thermomechanical treatment methods promoted the sufficient precipitation of the solid solution elements as nano-second phase particles, resulting in a synergistic improvement in conductivity and strengthening effects. However, their resistance to high-temperature softening was poor. The third stage, from the 1980s onwards, focused on the selection of alloying elements to conserve precious metals and avoid the addition of toxic elements (such as Ag, Cd, and As). The main focus was on developing copper alloys containing Cr, Zr, Ni, Si, Fe, Mg, Sn, Zn, P, RE, and Ti to improve their resistance to high-temperature softening. Attention was also paid to improvements and innovations in the preparation process.

[0003] With the urgent demand for high-end chips in extremely large-scale integrated circuits, the lead frame is required to have ultra-thin (≤0.08mm), high-precision pin count (≥340), conductivity ≥80% IACS and other characteristics, which has put higher requirements on the performance and residual stress of alloy foil. The existing Cu-Cr-Sn alloy strip cannot meet the above needs. Summary of the Invention

[0004] The purpose of the present invention is to provide a copper alloy strip and its preparation method and application. The copper alloy strip provided by the present invention has low residual stress, high strength and high conductivity as well as good resistance to high-temperature softening, which can meet the use requirements of copper alloy strips for corrosion-resistant lead frames of extremely large-scale circuits.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a copper alloy strip, which comprises, by weight percentage, 0.15-0.5% Cr, 0.05-0.25% Zr, 0.005-0.05% Si, and the balance Cu. In terms of phase composition, the copper alloy strip comprises a primary Cr phase, a primary CrSi phase, and a primary CuZr phase. The average length of the primary Cr phase is 0.5-2 μm, and the average width is 0.2-0.5 μm. The average diameter of the primary CrSi phase is 0.2-0.5 μm. The average diameter of the primary CuZr phase is 0.5-1 μm. The precipitation density of the primary Cr phase is 5×10 5 ~1×10 6 m -3 The precipitation density of the primary CrSi phase is 2×10 5 ~5×10 5 m -3 The precipitation density of the primary CuZr phase is 1×10 3 ~3×10 3 m -3 .

[0007] Preferably, the copper alloy strip further comprises at least two of Sc, La and Mn, wherein Sc: 0.005-0.01%, La: 0.005-0.01%, and Mn: 0.005-0.01%.

[0008] Preferably, the tensile strength σ of the copper alloy strip is b The plastic elongation δ is 1-5%, the electrical conductivity is 75-85% IACS, and the high temperature softening temperature is 550-600°C.

[0009] The present invention provides a method for preparing the copper alloy strip described in the above scheme, comprising the following steps:

[0010] corresponding to the elemental composition of the copper alloy strip, melting and casting the prepared raw materials to obtain ingots;

[0011] hot rolling the cast slab to obtain a hot-rolled slab;

[0012] The hot-rolled billet is subjected to a multi-stage high-temperature heat treatment to obtain a heat-treated billet; the multi-stage high-temperature heat treatment comprises: first heating to 850-900° C., holding at this temperature for 8-12 hours, and then second heating to 950-1000° C., holding at this temperature for 2-4 hours;

[0013] performing a first cold rolling on the heat-treated billet to obtain a first cold-rolled billet;

[0014] performing a first intermediate annealing on the first cold-rolled billet to obtain a first annealed billet;

[0015] performing a second cold rolling on the first annealed billet to obtain a second cold rolled billet;

[0016] performing a second intermediate annealing on the second cold-rolled billet to obtain a second annealed billet;

[0017] performing a third cold rolling on the second annealed billet to obtain a third cold rolled billet;

[0018] The third cold-rolled billet is subjected to online aging treatment to obtain an aged billet; the online aging treatment temperature is 400-600° C. and the speed is 20-40 m / min;

[0019] performing a fourth cold rolling on the aging treated billet to obtain a fourth cold rolled billet;

[0020] The fourth cold-rolled billet is subjected to low-temperature tension annealing to obtain the copper alloy strip; the temperature of the low-temperature tension annealing is 300-400°C, and the applied tension is 40-60N / m 2 .

[0021] Preferably, the smelting temperature is 1300-1350°C; the casting temperature is 1200-1250°C.

[0022] Preferably, the total processing rate of the hot rolling is 85-95%.

[0023] Preferably, the final rolling temperature of the hot rolling is 700-750°C.

[0024] Preferably, the total processing rate of the first cold rolling is 75-85%; the total processing rate of the second cold rolling is 65-85%; the total processing rate of the third cold rolling is 40-60%; and the total processing rate of the fourth cold rolling is 10-30%.

[0025] Preferably, the temperature of the first intermediate annealing and the second intermediate annealing are independently 600-700° C., and the holding time is independently 4-6 hours.

[0026] The present invention provides the use of the copper alloy strip described in the above solution or the copper alloy strip prepared by the preparation method described in the above solution in an etched lead frame.

[0027] The present invention provides a copper alloy strip, which comprises, by weight percentage, 0.15-0.5% Cr, 0.05-0.25% Zr, 0.005-0.05% Si, and the balance Cu. In terms of phase composition, the copper alloy strip comprises a primary Cr phase, a primary CrSi phase, and a primary CuZr phase. The average length of the primary Cr phase is 0.5-2 μm, and the average width is 0.2-0.5 μm. The average diameter of the primary CrSi phase is 0.2-0.5 μm, and the average diameter of the primary CuZr phase is 0.5-1 μm. The precipitation density of the primary Cr phase is 5×10 5 ~1×10 6 m -3 The precipitation density of the primary CrSi phase is 2×10 5 ~5×10 5 m -3 The precipitation density of the primary CuZr phase is 1×10 3 ~3×10 3 m -3 .

[0028] The present invention optimizes the composition of the copper alloy strip and controls the size and precipitation density of the primary phase to obtain a copper alloy strip with low residual stress, high strength and high conductivity as well as good resistance to high temperature softening. The results of the examples show that the tensile strength σ of the copper alloy strip provided by the present invention is b The alloy has a hardness of 540-700 MPa, a plastic elongation δ of 1-5%, an electrical conductivity of 75-85% IACS, a high-temperature softening temperature of 550-600°C, a macroscopic plate shape stability control of ≤1.0I, and a strip warping height of ≤2mm after chemical etching. Compared with the C19400 (Cu-Fe-P) alloy, the alloy has higher strength and electrical conductivity, and has more excellent surface properties and electroplating properties after etching, and can meet the use requirements of the alloy strip for corrosion-resistant lead frames of extremely large-scale circuits. DETAILED DESCRIPTION

[0029] The present invention provides a copper alloy strip, which comprises, by weight percentage, 0.15-0.5% Cr, 0.05-0.25% Zr, 0.005-0.05% Si, and the balance Cu. In terms of phase composition, the copper alloy strip comprises a primary Cr phase, a primary CrSi phase, and a primary CuZr phase. The average length of the primary Cr phase is 0.5-2 μm, and the average width is 0.2-0.5 μm. The average diameter of the primary CrSi phase is 0.2-0.5 μm, and the average diameter of the primary CuZr phase is 0.5-1 μm. The precipitation density of the primary Cr phase is 5×10 5 ~1×10 6 m -3The precipitation density of the primary CrSi phase is 2×10 5 ~5×10 5 m -3 The precipitation density of the primary CuZr phase is 1×10 3 ~3×10 3 m -3 .

[0030] In terms of weight percentage, the copper alloy strip provided by the present invention includes 0.15-0.5% Cr, preferably 0.2-0.4%, and more preferably 0.25-0.35%.

[0031] In terms of weight percentage, the copper alloy strip provided by the present invention includes 0.05-0.25% Zr, preferably 0.1-0.2%, and more preferably 0.13-0.17%.

[0032] In terms of weight percentage, the copper alloy strip provided by the present invention includes 0.005-0.05% Si, preferably 0.01-0.04%, and more preferably 0.02-0.03%.

[0033] The copper alloy strip provided by the present invention preferably also includes, by weight percentage, at least two of Sc, La, and Mn, for example, Sc and La, Sc and Mn, La and Mn, or Sc, La, and Mn simultaneously. In the present invention, the Sc content is preferably 0.005-0.01%, more preferably 0.006-0.008%; the La content is preferably 0.005-0.01%, more preferably 0.006-0.008%; and the Mn content is preferably 0.005-0.01%, more preferably 0.006-0.008%. In the present invention, Sc primarily serves to refine the strengthening phase; La primarily serves to refine the grains and precipitate phases; and Mn primarily serves to purify the melt and refine the precipitate phases.

[0034] The copper alloy strip provided by the present invention further includes a balance of copper.

[0035] In terms of phase composition, the copper alloy strip comprises a primary Cr phase, a primary CrSi phase and a primary CuZr phase; preferably, it also comprises a nano-scale Cr-rich phase and a Zr-rich phase.

[0036] In the present invention, the average length of the primary Cr phase is 0.5 to 2 μm, preferably 1 to 1.5 μm; the average width is 0.2 to 0.5 μm, preferably 0.3 to 0.4 μm; the average diameter of the primary CrSi phase is 0.2 to 0.5 μm, preferably 0.3 to 0.4 μm; the average diameter of the primary CuZr phase is 0.5 to 1 μm, preferably 0.6 to 0.8 μm; the precipitation density of the primary Cr phase is 5×10 5~1×10 6 m -3 , preferably 6×10 5 ~8×10 5 m -3 The precipitation density of the primary CrSi phase is 2×10 5 ~5×10 5 m -3 , preferably 3×10 5 ~4×10 5 m -3 The precipitation density of the primary CuZr phase is 1×10 3 ~3×10 3 m -3 , preferably 1.5×10 3 ~2.5×10 3 m -3 .

[0037] In the present invention, the etching performance is mainly affected by the coarse primary phase. The present invention controls the size and precipitation density of the primary phase to ensure that the copper alloy strip has good etching performance.

[0038] In the present invention, the tensile strength σ of the copper alloy strip is b It is preferably 540-700 MPa, the plastic elongation δ is preferably 1-5%, the conductivity is preferably 75-85% IACS, and the high temperature softening temperature is preferably 550-600°C; the macroscopic plate shape stability control is preferably ≤1.0I, and the strip warping height after chemical etching is preferably ≤2mm.

[0039] The present invention provides a method for preparing the copper alloy strip described in the above scheme, comprising the following steps:

[0040] corresponding to the elemental composition of the copper alloy strip, melting and casting the prepared raw materials to obtain ingots;

[0041] hot rolling the cast slab to obtain a hot-rolled slab;

[0042] The hot-rolled billet is subjected to a multi-stage high-temperature heat treatment to obtain a heat-treated billet; the multi-stage high-temperature heat treatment comprises: first heating to 850-900° C., holding at this temperature for 8-12 hours, and then second heating to 950-1000° C., holding at this temperature for 2-4 hours;

[0043] performing a first cold rolling on the heat-treated billet to obtain a first cold-rolled billet;

[0044] performing a first intermediate annealing on the first cold-rolled billet to obtain a first annealed billet;

[0045] performing a second cold rolling on the first annealed billet to obtain a second cold rolled billet;

[0046] performing a second intermediate annealing on the second cold-rolled billet to obtain a second annealed billet;

[0047] performing a third cold rolling on the second annealed billet to obtain a third cold rolled billet;

[0048] The third cold-rolled billet is subjected to online aging treatment to obtain an aged billet; the online aging treatment temperature is 400-600° C. and the speed is 20-40 m / min;

[0049] performing a fourth cold rolling on the aging treated billet to obtain a fourth cold rolled billet;

[0050] The fourth cold-rolled billet is subjected to low-temperature tension annealing to obtain the copper alloy strip; the temperature of the low-temperature tension annealing is 300-400°C, and the applied tension is 40-60N / m 2 .

[0051] The present invention melts and casts raw materials corresponding to the element composition of the copper alloy strip to obtain a casting blank.

[0052] In the present invention, the preparation raw materials preferably include electrolytic copper, copper-chromium master alloy, copper-zirconium master alloy and copper-silicon master alloy; when the copper alloy strip also includes at least two of Sc, La and Mn, the preparation raw materials also include at least two of copper-scandium master alloy, copper-lanthanum master alloy and copper-manganese master alloy.

[0053] In the present invention, the smelting temperature is preferably 1300-1350°C; the smelting is preferably carried out in a medium-frequency induction furnace. In the present invention, when the raw materials include at least two of a copper-scandium master alloy, a copper-lanthanum master alloy, and a copper-manganese master alloy, the smelting preferably includes: adding electrolytic copper to the medium-frequency induction furnace for melting, then adding a copper-chromium master alloy, a copper-zirconium master alloy, and a copper-silicon master alloy; after all the master alloys are melted, continuing to add at least two of the copper-scandium master alloy, the copper-lanthanum master alloy, and the copper-manganese master alloy; sequentially adding a covering agent and burning charcoal to the medium-frequency induction furnace, raising the temperature to 1300-1350°C, and after the melt is completely melted, introducing argon gas and stirring.

[0054] The present invention has no particular requirements for the type and amount of the covering agent, as long as it can prevent oxygen and other elements from reacting with the alloying elements. The present invention also has no particular requirements for the amount of charcoal used; an appropriate amount can be selected based on the actual conditions of the melt. In the present invention, the burning charcoal is used to prevent oxidation of the melt.

[0055] In the present invention, the casting temperature is preferably 1200-1250°C; the present invention preferably keeps the melt obtained by smelting at the casting temperature for more than 20 minutes before casting. In the present invention, the casting is preferably semi-continuous casting, the casting speed is preferably 60-100 mm / min, and the primary cooling intensity is preferably 100-150 m 3 / h; The present invention has no special requirements on the size of the ingot, and a suitable size can be selected according to actual needs.

[0056] After obtaining the ingot, the present invention hot-rolls the ingot to obtain a hot-rolled ingot. Before the hot rolling, the present invention preferably heats the ingot, and the heating temperature is preferably 850-920°C, more preferably 880-900°C, and the holding time is preferably 4-6h, more preferably 4.5-5.5h. In the present invention, the heating is preferably carried out in a walking furnace. In the present invention, the total processing rate of the hot rolling is preferably 85-95%, more preferably 88-92%. In the present invention, the finishing temperature of the hot rolling is preferably 700-750°C, more preferably 710-740°C, and further preferably 720-730°C. In the present invention, the purpose of the hot rolling is to achieve dimensional change and structural crushing.

[0057] After obtaining the hot-rolled slab, the present invention subjects the hot-rolled slab to a multi-stage high-temperature heat treatment to obtain a heat-treated slab. In the present invention, the multi-stage high-temperature heat treatment comprises: first heating to 850-900°C, holding for 8-12 hours, followed by a second heating to 950-1000°C, holding for 2-4 hours; preferably: first heating to 860-890°C, holding for 9-11 hours, followed by a second heating to 960-980°C, holding for 2.5-3.5 hours. In the present invention, the cooling method for the multi-stage high-temperature heat treatment is preferably water cooling. In the present invention, the first heating to 850-900°C, holding for 8-12 hours, eliminates the Zr phase, followed by a second heating to 950-1000°C, holding for 2-4 hours, eliminates the Cr-rich phase. By employing multi-stage high-temperature heat treatment, the present invention achieves control over the quantity and size of the primary secondary phase, thereby avoiding the appearance of burrs during the strip etching process.

[0058] After obtaining the heat-treated ingot, the present invention performs a first cold rolling on the heat-treated ingot to obtain a first cold-rolled ingot. Prior to the first cold rolling, the present invention preferably performs face milling on the heat-treated ingot. In the present invention, the total processing rate of the first cold rolling is preferably 75-85%, more preferably 78-83%. The present invention utilizes the first cold rolling to reduce the thickness while simultaneously achieving grain crushing.

[0059] After obtaining the first cold-rolled billet, the present invention performs a first intermediate annealing on the first cold-rolled billet to obtain a first annealed billet. In the present invention, the temperature of the first intermediate annealing is preferably 600-700°C, more preferably 620-680°C, and even more preferably 640-660°C. The holding time of the first intermediate annealing is preferably 4-6 hours, more preferably 4.5-5.5 hours. The present invention utilizes the first intermediate annealing to increase the plasticity of the material, facilitating subsequent processing and deformation.

[0060] After obtaining the first annealed billet, the present invention performs a second cold rolling on the first annealed billet to obtain a second cold rolled billet. In the present invention, the total processing rate of the second cold rolling is preferably 65-85%, more preferably 70-80%, and even more preferably 73-77%.

[0061] After obtaining the second cold-rolled billet, the present invention performs a second intermediate annealing on the second cold-rolled billet to obtain a second annealed billet. In the present invention, the temperature of the second intermediate annealing is preferably 600-700°C, more preferably 620-680°C, and even more preferably 640-660°C; the holding time of the second intermediate annealing is preferably 4-6 hours, more preferably 4.5-5.5 hours.

[0062] After obtaining the second annealed billet, the present invention performs a third cold rolling on the second annealed billet to obtain a third cold rolled billet. In the present invention, the total processing rate of the third cold rolling is preferably 40-60%, more preferably 45-55%.

[0063] After obtaining the third cold-rolled slab, the present invention subjects the third cold-rolled slab to an online aging treatment to obtain an aged slab. In the present invention, the online aging treatment temperature is 400-600°C, preferably 450-550°C, and more preferably 480-520°C; the online aging treatment speed is 20-40 m / min, preferably 25-35 m / min. The present invention utilizes online aging treatment to achieve the precipitation of nano-precipitated phases, thereby improving the strength and conductivity of the material.

[0064] After obtaining the aging-treated billet, the present invention performs a fourth cold rolling on the aging-treated billet to obtain a fourth cold-rolled billet. In the present invention, the total processing rate of the fourth cold rolling is preferably 10-30%, more preferably 15-25%.

[0065] After obtaining the fourth cold-rolled billet, the present invention performs low-temperature tension annealing on the fourth cold-rolled billet to obtain the copper alloy strip. In the present invention, the temperature of the low-temperature tension annealing is 300-400°C, more preferably 320-380°C, and even more preferably 340-360°C; the applied tension is 40-60 N / m 2 , preferably 45 to 55 N / m 2 , more preferably 48 to 52 N / m2 The present invention does not require the time of the low temperature tension annealing. The present invention facilitates the control of microstructure and reduces the residual stress of the strip through multiple cold rolling and annealing.

[0066] After completing the low-temperature tension annealing, the present invention preferably further comprises shearing the billet after the low-temperature tension annealing to obtain the copper alloy strip.

[0067] The present invention realizes the control of the amount and size of the primary second phase by adopting multi-stage high-temperature heat treatment, thereby avoiding the occurrence of burrs in the strip etching process; and realizes the preparation of low-stress strip by online rapid aging treatment, multi-stage combined deformation heat treatment and low-temperature tension annealing, and the tensile strength σ of the obtained copper alloy strip is b The alloy has a hardness of 540-700 MPa, a plastic elongation δ of 1-5%, an electrical conductivity of 75-85% IACS, a high-temperature softening temperature of 550-600°C, a macroscopic plate shape stability control of ≤1.0I, and a strip warping height of ≤2mm after chemical etching. Compared with the C19400 (Cu-Fe-P) alloy, the alloy has higher strength and electrical conductivity, and has more excellent surface properties and electroplating properties after etching, and can meet the use requirements of the alloy strip for corrosion-resistant lead frames of extremely large-scale circuits.

[0068] The present invention provides the use of the copper alloy strip described in the above solution or the copper alloy strip prepared by the preparation method described in the above solution in an etched lead frame.

[0069] The copper alloy strip provided by the present invention, its preparation method and application are described in detail below with reference to the embodiments, but they should not be understood as limiting the scope of protection of the present invention.

[0070] Example 1

[0071] The preparation steps are as follows:

[0072] 1. Melting and casting: Before melting, add electrolytic copper into the medium frequency induction furnace and wait for it to melt, then add copper chromium, copper zirconium, and copper silicon master alloys. After the above materials are melted, continue to add copper scandium master alloy and copper manganese master alloy. After using a covering agent, add burning charcoal and raise the temperature to 1300℃. After the melt is completely melted, introduce argon gas and stir evenly. The casting temperature is controlled at 1200℃. After keeping warm for 20 minutes, semi-continuous casting is carried out to form 190mm×620mm×L (L is the length, determined by weight) ingots. The casting speed is 60mm / min and the primary cooling intensity is 100m 3 / h.

[0073] 2. Hot rolling: The alloy ingot is placed in a walking beam furnace and heated to 920°C, kept at this temperature for 4 hours, with a total hot rolling processing rate of 85% and a final rolling temperature of 700°C.

[0074] 3. Multi-stage high-temperature heat treatment: adopt step-by-step heating, the heating system is to heat up to 850℃, keep warm for 12 hours; then heat up to 1000℃, keep warm for 2 hours, and cool by water;

[0075] 4. First cold rolling: The heat-treated billet is subjected to milling, followed by first cold rolling, with a total rolling processing rate of 75%.

[0076] 5. First intermediate annealing: The first cold-rolled billet is subjected to intermediate annealing treatment at an annealing temperature of 600° C. and a holding time of 6 hours.

[0077] 6. Second cold rolling: The first annealed billet is subjected to second cold rolling, with a total rolling processing rate of 85%.

[0078] 7. Second intermediate annealing: The obtained second cold-rolled billet is subjected to intermediate annealing treatment at an annealing temperature of 600°C and a holding time of 6 hours.

[0079] 8. Third cold rolling: The second annealed billet is subjected to third cold rolling, with a total rolling processing rate of 40%.

[0080] 9. Online aging treatment: The obtained third cold-rolled billet is subjected to online aging treatment at an aging temperature of 400° C. and an annealing speed of 20 m / min.

[0081] 10. Fourth cold rolling: The aging treated billet is subjected to the fourth cold rolling, with a total rolling processing rate of 10%.

[0082] 11. Low temperature tension annealing: The fourth cold rolled billet is subjected to low temperature tension annealing treatment, the annealing temperature is 300℃, the tension is 60N / m 2 , a copper alloy strip was obtained, the composition is shown in Table 1, and the organization and physical properties are shown in Table 2 and Table 3 respectively.

[0083] Example 2

[0084] 1. Melting and casting: Add electrolytic copper to the medium frequency induction furnace and wait for it to melt. Then add copper chromium, copper zirconium, and copper silicon master alloys. After the above materials are melted, continue to add copper scandium master alloy and copper lanthanum master alloy. Add burning charcoal after using a covering agent. Raise the temperature to 1350℃. After the melt is completely melted, introduce argon gas and stir evenly. Control the casting temperature at 1250℃. After keeping warm for 20 minutes, semi-continuous casting is carried out to form 190mm×620mm×L ingots. The casting speed is 100mm / min and the primary cooling intensity is 150m 3 / h.

[0085] 2. Hot rolling: The alloy ingot is placed in a walking beam furnace and heated to 850°C, kept at this temperature for 6 hours, with a total hot rolling processing rate of 95% and a final rolling temperature of 750°C.

[0086] 3. Multi-stage high-temperature heat treatment: adopt step-by-step heating, the heating system is to heat up to 900℃, keep warm for 8 hours; then heat up to 950℃, keep warm for 4 hours, and cool by water;

[0087] 4. First cold rolling: The heat-treated billet is subjected to milling, followed by first cold rolling, with a total rolling processing rate of 85%.

[0088] 5. First intermediate annealing: The first cold-rolled billet is subjected to intermediate annealing treatment at an annealing temperature of 700° C. and a holding time of 4 hours.

[0089] 6. Second cold rolling: The first annealed billet is subjected to second cold rolling, with a total rolling processing rate of 65%.

[0090] 7. Second intermediate annealing: The obtained second cold-rolled billet is subjected to intermediate annealing treatment at an annealing temperature of 700°C and a holding time of 4 hours.

[0091] 8. Third cold rolling: The second annealed billet is subjected to third cold rolling, with a total rolling processing rate of 60%.

[0092] 9. Online aging treatment: The obtained third cold-rolled billet is subjected to online aging treatment at an aging temperature of 600° C. and an annealing speed of 40 m / min.

[0093] 10. Fourth cold rolling: The aging treated billet is subjected to the fourth cold rolling, with a total rolling processing rate of 30%.

[0094] 11. Low temperature tension annealing: The fourth cold rolled billet is subjected to low temperature tension annealing treatment, the annealing temperature is 400℃, the tension is 40N / m 2 , a copper alloy strip was obtained, the composition is shown in Table 1, and the organization and physical properties are shown in Table 2 and Table 3 respectively.

[0095] Example 3

[0096] 1. Melting and casting: Before melting, add electrolytic copper into the medium frequency induction furnace and wait for it to melt, then add copper chromium, copper zirconium, copper silicon master alloy. After the above materials are melted, continue to add copper manganese master alloy and copper lanthanum master alloy. After using covering agent, add burning charcoal, raise the temperature to 1325℃, wait for the melt to be completely melted, introduce argon gas, and then stir evenly. Control the casting temperature at 1230℃, keep warm for 20 minutes, and then semi-continuously cast into 190mm×620mm×L ingot, with a casting speed of 80mm / min and a primary cooling intensity of 125m 3 / h.

[0097] 2. Hot rolling: The alloy ingot is placed in a walking beam furnace and heated to 900°C, kept at this temperature for 4 hours, with a total hot rolling processing rate of 90% and a final rolling temperature of 725°C.

[0098] 3. Multi-stage high-temperature heat treatment: adopt step-by-step heating, the heating system is to heat up to 900℃, keep warm for 10 hours; then heat up to 975℃, keep warm for 4 hours, and cool by water;

[0099] 4. First cold rolling: The heat-treated billet is subjected to milling, followed by first cold rolling, with a total rolling processing rate of 80%.

[0100] 5. First intermediate annealing: The obtained first cold-rolled billet is subjected to intermediate annealing treatment at an annealing temperature of 650° C. and a holding time of 4 hours.

[0101] 6. Second cold rolling: The first annealed billet is subjected to second cold rolling, with a total rolling processing rate of 75%.

[0102] 7. Second intermediate annealing: The obtained second cold-rolled billet is subjected to intermediate annealing treatment at an annealing temperature of 650°C and a holding time of 4 hours.

[0103] 8. Third cold rolling: The second annealed billet is subjected to third cold rolling, with a total rolling processing rate of 50%.

[0104] 9. Online aging treatment: The obtained third cold-rolled billet is subjected to online aging treatment at an aging temperature of 500° C. and an annealing speed of 30 m / min.

[0105] 10. Fourth cold rolling: The aging treated billet is subjected to the fourth cold rolling, with a total rolling processing rate of 20%.

[0106] 11. Low temperature tension annealing: The fourth cold rolled billet is subjected to low temperature tension annealing treatment at 350°C and a tension of 50N / m. 2 , a copper alloy strip was obtained, the composition is shown in Table 1, and the organization and physical properties are shown in Table 2 and Table 3 respectively.

[0107] Example 4

[0108] 1. Melting and casting: Add electrolytic copper to the medium frequency induction furnace and wait for it to melt. Then add copper chromium, copper zirconium, and copper silicon master alloys. After the above materials are melted, continue to add copper scandium master alloy and copper lanthanum master alloy. Add burning charcoal after using a covering agent. Raise the temperature to 1300℃. After the melt is completely melted, introduce argon gas and stir evenly. Control the casting temperature at 1220℃. After keeping warm for 20 minutes, semi-continuous casting is carried out to form 190mm×620mm×L ingots. The casting speed is 80mm / min and the primary cooling intensity is 120m 3 / h.

[0109] 2. Hot rolling: The alloy ingot is placed in a walking beam furnace and heated to 870°C, kept at this temperature for 5 hours, with a total hot rolling processing rate of 90% and a final rolling temperature of 750°C.

[0110] 3. Multi-stage high-temperature heat treatment: adopt step-by-step heating, the heating system is to heat up to 860℃, keep warm for 8 hours; then heat up to 970℃, keep warm for 4 hours, and cool by water;

[0111] 4. First cold rolling: The heat-treated billet is subjected to milling, followed by first cold rolling, with a total rolling processing rate of 85%.

[0112] 5. First intermediate annealing: The first cold-rolled billet is subjected to intermediate annealing treatment at an annealing temperature of 630° C. and a holding time of 4 h.

[0113] 6. Second cold rolling: The first annealed billet is subjected to second cold rolling, with a total rolling processing rate of 75%.

[0114] 7. Second intermediate annealing: The obtained second cold-rolled billet is subjected to intermediate annealing treatment at an annealing temperature of 640°C and a holding time of 4 hours.

[0115] 8. Third cold rolling: The second annealed billet is subjected to third cold rolling, with a total rolling processing rate of 50%.

[0116] 9. Online aging treatment: The obtained third cold-rolled billet is subjected to online aging treatment at an aging temperature of 550° C. and an annealing speed of 40 m / min.

[0117] 10. Fourth cold rolling: The aging treated billet is subjected to the fourth cold rolling, with a total rolling processing rate of 20%.

[0118] 11. Low temperature tension annealing: The fourth cold rolled billet is subjected to low temperature tension annealing treatment at 320°C and a tension of 40N / m. 2 , a copper alloy strip was obtained, the composition is shown in Table 1, and the organization and physical properties are shown in Table 2 and Table 3 respectively.

[0119] Example 5

[0120] 1. Melting and casting: Add electrolytic copper to the medium frequency induction furnace and wait for it to melt, then add copper-chromium, copper-zirconium, and copper-silicon master alloys. After the above materials are melted, continue to add copper-manganese master alloys and copper-lanthanum master alloys. After using a covering agent, add burning charcoal and raise the temperature to 1300℃. After the melt is completely melted, introduce argon gas and stir evenly. The casting temperature is controlled at 1220℃. After keeping warm for 20 minutes, semi-continuous casting is carried out to form 190mm×620mm×L ingots. The casting speed is 70mm / min and the primary cooling intensity is 110m 3 / h.

[0121] 2. Hot rolling: The alloy ingot is placed in a walking beam furnace and heated to 880°C, kept at this temperature for 5 hours, with a total hot rolling processing rate of 90% and a final rolling temperature of 700°C.

[0122] 3. Multi-stage high-temperature heat treatment: adopt step-by-step heating, the heating system is to heat up to 870℃, keep warm for 8 hours; then heat up to 970℃, keep warm for 2 hours, and cool by water;

[0123] 4. First cold rolling: The heat-treated billet is subjected to milling, followed by first cold rolling, with a total rolling processing rate of 80%.

[0124] 5. First intermediate annealing: The first cold-rolled billet is subjected to intermediate annealing treatment at an annealing temperature of 640° C. and a holding time of 4 h.

[0125] 6. Second cold rolling: The first annealed billet is subjected to second cold rolling, with a total rolling processing rate of 80%.

[0126] 7. Second intermediate annealing: The obtained first cold-rolled billet is subjected to intermediate annealing treatment at an annealing temperature of 650°C and a holding time of 4 hours.

[0127] 8. Third cold rolling: The first annealed billet is subjected to third cold rolling, with a total rolling processing rate of 40%.

[0128] 9. Online aging treatment: The cold-rolled strip is subjected to online aging treatment at a temperature of 550° C. and an annealing speed of 30 m / min.

[0129] 10. Fourth cold rolling: The aging treated billet is subjected to the fourth cold rolling, with a total rolling processing rate of 20%.

[0130] 11. Low temperature tension annealing: The first cold rolled billet is subjected to low temperature tension annealing treatment at 350°C and a tension of 40N / m. 2 , a copper alloy strip was obtained, the composition is shown in Table 1, and the organization and physical properties are shown in Table 2 and Table 3 respectively.

[0131] Example 6

[0132] 1. Melting and casting: Add electrolytic copper to the medium frequency induction furnace and wait for it to melt. Then add copper-chromium, copper-zirconium, and copper-silicon master alloys. After the above materials are melted, continue to add copper-scandium master alloys and copper-manganese master alloys. After using a covering agent, add burning charcoal and raise the temperature to 1270℃. After the melt is completely melted, introduce argon gas and stir evenly. The casting temperature is controlled at 1220℃. After keeping warm for 20 minutes, semi-continuous casting is carried out to form 190mm×620mm×L billets. The casting speed is 90mm / min and the primary cooling intensity is 135m 3 / h.

[0133] 2. Hot rolling: The alloy ingot is placed in a walking beam furnace and heated to 880°C, kept at this temperature for 5 hours, with a total hot rolling processing rate of 90% and a final rolling temperature of 725°C.

[0134] 3. Multi-stage high-temperature heat treatment: adopt step-by-step heating, the heating system is to heat up to 860℃, keep warm for 8 hours; then heat up to 975℃, keep warm for 3 hours, and cool by water;

[0135] 4. First cold rolling: The heat-treated billet is subjected to milling, followed by first cold rolling, with a total rolling processing rate of 85%.

[0136] 5. First intermediate annealing: The obtained first cold-rolled billet is subjected to intermediate annealing treatment at an annealing temperature of 650° C. and a holding time of 4 hours.

[0137] 6. Second cold rolling: The first annealed billet is subjected to second cold rolling, with a total rolling processing rate of 75%.

[0138] 7. Second intermediate annealing: The obtained second cold-rolled billet is subjected to intermediate annealing treatment at an annealing temperature of 650°C and a holding time of 4 hours.

[0139] 8. Third cold rolling: The second annealed billet is subjected to third cold rolling, with a total rolling processing rate of 50%.

[0140] 9. Online aging treatment: The obtained third cold-rolled billet is subjected to online aging treatment at an aging temperature of 500° C. and an annealing speed of 30 m / min.

[0141] 10. Fourth cold rolling: The aging treated billet is subjected to the fourth cold rolling, with a total rolling processing rate of 20%.

[0142] 11. Low temperature tension annealing: The fourth cold rolled billet is subjected to low temperature tension annealing treatment, the annealing temperature is 350℃, the tension is 30N / m 2 , a copper alloy strip was obtained, the composition is shown in Table 1, and the organization and physical properties are shown in Table 2 and Table 3 respectively.

[0143] Comparative Example 1

[0144] The commercially available XYK-40 high-conductivity copper-chromium alloy sheet, strip and foil has a national standard GB of TCr0.5 and an American standard ASTM of C18140.

[0145] Table 1 Alloy composition formula (wt%) of Examples 1 to 6 and Comparative Example 1

[0146]

[0147]

[0148] Table 2 Microstructure characteristics of alloys of Examples 1 to 6 and Comparative Example 1

[0149]

[0150] Table 3 Physical properties of alloys of Examples 1 to 6 and Comparative Example 1

[0151]

[0152]

[0153] Note: The data of Comparative Example 1 in Tables 2 and 3 are the data of actual measurements of multiple alloy products.

[0154] From the above examples and comparative examples, it can be seen that the tensile strength σ of the copper alloy strip provided by the present invention is b The alloy has a hardness of 540-700 MPa, a plastic elongation δ of 1-5%, an electrical conductivity of 75-85% IACS, a high-temperature softening temperature of 550-600°C, a macroscopic plate shape stability control of ≤1.0I, and a strip warping height of ≤2mm after chemical etching. Compared with the C19400 (Cu-Fe-P) alloy, the alloy has higher strength and electrical conductivity, and has more excellent surface properties and electroplating properties after etching, and can meet the use requirements of the alloy strip for corrosion-resistant lead frames of extremely large-scale circuits.

[0155] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A copper alloy strip, characterized in that: The copper alloy strip is composed of the following elements in weight percentage: Cr: 0.15-0.46%, Zr: 0.05-0.25%, Si: 0.005-0.05%, at least two of Sc, La and Mn, wherein Sc: 0.005-0.01%, La: 0.005-0.01%, Mn: 0.005-0.01%, and the balance is Cu; in terms of phase composition, the copper alloy strip comprises a primary Cr phase, a primary CrSi phase and a primary CuZr phase; the average length of the primary Cr phase is 0.5-2 μm, and the average width is 0.2-0.5 μm; the average diameter of the primary CrSi phase is 0.2-0.5 μm; the average diameter of the primary CuZr phase is 0.5-1 μm; the precipitation density of the primary Cr phase is 5×10 5 ~1×10 6 m -3 The precipitation density of the primary CrSi phase is 2×10 5 ~5×10 5 m -3 The precipitation density of the primary CuZr phase is 1×10 3 ~3×10 3 m -3 ; The method for preparing the copper alloy strip comprises the following steps: corresponding to the elemental composition of the copper alloy strip, melting and casting the prepared raw materials to obtain ingots; hot rolling the cast slab to obtain a hot-rolled slab; The hot-rolled billet is subjected to a multi-stage high-temperature heat treatment to obtain a heat-treated billet; the multi-stage high-temperature heat treatment comprises: first heating to 850-900° C., holding at this temperature for 8-12 hours, and then second heating to 950-1000° C., holding at this temperature for 2-4 hours; performing a first cold rolling on the heat-treated billet to obtain a first cold-rolled billet; performing a first intermediate annealing on the first cold-rolled billet to obtain a first annealed billet; performing a second cold rolling on the first annealed billet to obtain a second cold rolled billet; performing a second intermediate annealing on the second cold-rolled billet to obtain a second annealed billet; performing a third cold rolling on the second annealed billet to obtain a third cold rolled billet; The third cold-rolled billet is subjected to online aging treatment to obtain an aged billet; the online aging treatment temperature is 400-600° C. and the speed is 20-40 m / min; performing a fourth cold rolling on the aging treated billet to obtain a fourth cold rolled billet; The fourth cold-rolled billet is subjected to low-temperature tension annealing to obtain the copper alloy strip; the temperature of the low-temperature tension annealing is 300-400°C, and the applied tension is 40-60N / m 2 ; The tensile strength σ of the copper alloy strip b The plastic elongation δ is 1-5%, the electrical conductivity is 75-85% IACS, and the high temperature softening temperature is 550-600°C.

2. The method for preparing the copper alloy strip according to claim 1, characterized in that: The following steps are involved: corresponding to the elemental composition of the copper alloy strip, melting and casting the prepared raw materials to obtain ingots; hot rolling the cast slab to obtain a hot-rolled slab; The hot-rolled billet is subjected to multi-stage high-temperature heat treatment to obtain a heat-treated billet; The multi-stage high-temperature heat treatment includes: first heating to 850-900°C, keeping the temperature for 8-12 hours, and then second heating to 950-1000°C, keeping the temperature for 2-4 hours; performing a first cold rolling on the heat-treated billet to obtain a first cold-rolled billet; performing a first intermediate annealing on the first cold-rolled billet to obtain a first annealed billet; performing a second cold rolling on the first annealed billet to obtain a second cold rolled billet; performing a second intermediate annealing on the second cold-rolled billet to obtain a second annealed billet; performing a third cold rolling on the second annealed billet to obtain a third cold rolled billet; The third cold-rolled billet is subjected to online aging treatment to obtain an aged billet; the online aging treatment temperature is 400-600° C. and the speed is 20-40 m / min; performing a fourth cold rolling on the aging treated billet to obtain a fourth cold rolled billet; The fourth cold-rolled billet is subjected to low-temperature tension annealing to obtain the copper alloy strip; the temperature of the low-temperature tension annealing is 300-400°C, and the applied tension is 40-60N / m 2 .

3. The preparation method according to claim 2, characterized in that The smelting temperature is 1300-1350°C; the casting temperature is 1200-1250°C.

4. The preparation method according to claim 2, characterized in that The total processing rate of the hot rolling is 85-95%.

5. The preparation method according to claim 2 or 4, characterized in that The final rolling temperature of the hot rolling is 700-750°C.

6. The preparation method according to claim 2, characterized in that The total processing rate of the first cold rolling is 75-85%; the total processing rate of the second cold rolling is 65-85%; the total processing rate of the third cold rolling is 40-60%; and the total processing rate of the fourth cold rolling is 10-30%.

7. The preparation method according to claim 2, characterized in that The temperatures of the first intermediate annealing and the second intermediate annealing are independently 600-700° C., and the holding times are independently 4-6 hours.

8. Use of the copper alloy strip according to claim 1 or the copper alloy strip prepared by the preparation method according to any one of claims 2 to 7 in an etched lead frame.

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