Deformation heat treatment process of special-shaped copper strip for lead frame

Abstract

The invention relates to the technical field of semiconductor processing, in particular to a deformation heat treatment process of a special-shaped copper strip for a lead frame. Comprising the following steps that edge cutting is conducted, specifically, a raw material copper strip with the purity being 98.5%-99.5% is taken to be subjected to edge cutting treatment, and a to-be-treated copper strip is obtained; cold rolling: carrying out third cold rolling treatment on the to-be-treated copper strip to obtain a first semi-finished copper strip; hot rolling: carrying out hot rolling treatment on the first semi-finished copper strip to obtain a second semi-finished copper strip; and cooling: carrying out third cooling treatment on the second semi-finished copper strip to obtain a third semi-finished copper strip. After the copper strip is subjected to hot rolling treatment, the copper strip needs to be subjected to three times of cooling treatment, and the cooling temperature of each time is in a gradually decreasing state, so that the cooling process of the copper strip is performed in a stepped gradually decreasing form, the copper strip cannot be damaged due to rapid temperature change, and the yield of the copper strip is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor processing, and in particular relates to a deformation heat treatment process for a special-shaped copper strip for a lead frame. Background Art

[0002] Copper tape is the main raw material for making lead frames. In order to make the lead frames durable during use, the processing of copper tape in the early stage is particularly important.

[0003] After searching, the patent document with publication number CN117778915A and publication date March 29, 2024, named "A lead frame copper strip and its preparation process", includes the following preparation process: ingredients: according to the above-mentioned alloy components, standard cathode copper or old materials, Cu-P alloy, Cu-Mg alloy, zinc ingot or high zinc brass old materials, tin ingot, nickel plate, iron sheet or Cu-Fe alloy, Cu-Cr, Cu-Mn alloy, etc. are weighed separately; smelting: the weighed metal mixture is added to the coreless induction furnace for smelting, and charcoal, graphite powder or graphite block is added after melting. During the smelting process, the charcoal covering thickness is 100-150mm, the smelting temperature reaches 1140-1320℃, and the heat preservation is carried out for more than 25 minutes. After sampling and analysis of the components are qualified, the converter is started; after the converter, the melt is covered with charcoal with a covering thickness of 150-250mm; it is allowed to stand for more than 25 minutes, and after the component analysis is qualified, the discharge casting is started. The above embodiment not only increases the amount of precipitated second phase particles, but also makes the second phase particles finer and more dispersed, thereby significantly improving the strength and electrical conductivity of the alloy.

[0004] However, the above embodiment still has the following defects: After cold rolling and hot rolling, the temperature of the copper strip is usually as high as 700°C or above. However, in the prior art, cooling equipment is used to directly cool the copper strip at one time, resulting in a sharp change in the temperature of the copper strip in a short period of time. For the copper strip with high thermal conductivity, the rapid cooling may cause deformation and damage. In addition, the existing hot rolling technology cannot conduct heat evenly when processing special-shaped copper strips, resulting in a decrease in the yield and the quality of heat treatment. Summary of the invention

[0005] In view of the above problems, the present invention provides a deformation heat treatment process for a special-shaped copper strip for a lead frame, comprising the following steps: Trimming: taking the raw copper strip with a purity of 98.5%-99.5% and performing trimming treatment to obtain the copper strip to be treated; Cold rolling: performing cold rolling treatment on the copper strip to be processed three times to obtain a first semi-finished copper strip; Hot rolling: hot rolling the first semi-finished copper strip to obtain a second semi-finished copper strip; The second semi-finished copper strip is cooled and cooled three times to obtain a third semi-finished copper strip.

[0006] Further, the cold rolling comprises the following steps: The copper strip to be treated is subjected to a cold rolling treatment, wherein the cold rolling treatment temperature is 500°C±30°C and the duration is 8h±1h.

[0007] Furthermore, the cold rolling further comprises the following steps: The copper strip after the primary cold rolling treatment is subjected to a secondary cold rolling treatment, wherein the secondary cold rolling treatment temperature is 600°C±30°C and the duration is 11h±1h.

[0008] Furthermore, the cold rolling further comprises the following steps: The copper strip after the secondary cold rolling treatment is subjected to a third cold rolling treatment to obtain a first semi-finished copper strip, wherein the third cold rolling treatment temperature is 650°C±10°C and the duration is 14h-18h.

[0009] Furthermore, the hot rolling comprises the following steps: The first semi-finished copper strip is subjected to a hot rolling treatment, wherein the hot rolling treatment temperature is 800°C ± 10°C and the duration is 2h ± 0.5h; The first hot rolling is a preheating treatment. Before hot rolling, the first semi-finished copper strip needs to be cooled, and the cooling temperature is 25°C ± 15°C.

[0010] Furthermore, the hot rolling further comprises the following steps: The copper strip after the primary hot rolling treatment is subjected to a secondary hot rolling treatment, wherein the secondary hot rolling treatment temperature is 1000°C ± 10°C and the duration is 2h ± 0.5h; The secondary hot rolling is a heating treatment.

[0011] Furthermore, the hot rolling further comprises the following steps: The copper strip after the secondary hot rolling treatment is subjected to a third hot rolling treatment to obtain a second semi-finished copper strip, wherein the third hot rolling treatment temperature is 700°C ± 10°C and the duration is 4h ± 0.5h; The three hot rolling processes are uniform heat treatments, so that each part of the first semi-finished copper strip receives heat evenly.

[0012] Further, the method comprises the following steps: The second semi-finished copper strip is subjected to a primary cooling treatment, wherein the ambient temperature of the primary cooling treatment is 400° C., until the temperature of the second semi-finished copper strip drops to 400° C.±10° C.; The copper strip after the primary cooling treatment is subjected to a secondary cooling treatment, wherein the ambient temperature of the secondary cooling treatment is 150° C., until the temperature of the second semi-finished copper strip drops to 150° C.±10° C.

[0013] Furthermore, the cooling further comprises the following steps: The copper strip after the secondary cooling treatment is subjected to a tertiary cooling treatment, wherein the ambient temperature of the tertiary cooling treatment is 25° C., until the temperature of the copper strip drops to 25° C.±15° C., to obtain a third semi-finished copper strip.

[0014] Furthermore, the heat treatment process further comprises the following steps: Shearing: The third semi-finished copper strip is sheared according to actual needs to obtain a finished copper strip.

[0015] The beneficial effects of the present invention are: 1. After the copper strip is hot-rolled, it needs to be cooled three times, and the cooling temperature is decreasing each time, which is 400℃, 150℃ and 25℃ respectively, so that the cooling process of the copper strip is carried out in a step-by-step decreasing form, so that the copper strip will not be damaged by the rapid temperature change, thereby improving the yield of the copper strip.

[0016] 2. When processing copper strips, they first need to undergo three hot rolling treatments. The three hot rolling treatments correspond to preheating, heating and uniform heating, respectively. Especially for irregular-shaped special-shaped copper strips, the use of different temperatures and durations not only makes the copper strips more evenly heated, but also prevents the copper strips from being damaged due to excessive heating speed, thereby improving the quality of heat treatment.

[0017] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 A flow chart of a heat treatment process according to an embodiment of the present invention is shown.

[0020] Figure 2 A flow chart of the cold rolling step according to an embodiment of the present invention is shown.

[0021] Figure 3 A flow chart of hot rolling steps according to an embodiment of the present invention is shown.

[0022] Figure 4 A flow chart of a cooling step according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] The embodiment of the present invention provides a deformation heat treatment process for a special-shaped copper strip for a lead frame. For example, Figure 1 As shown, the following steps are included: S100: trimming, taking the raw copper strip with a purity of 98.5%-99.5% and performing trimming treatment to obtain the copper strip to be treated; S200: cold rolling, performing cold rolling treatment on the copper strip to be processed three times to obtain a first semi-finished copper strip; S300: hot rolling, hot rolling the first semi-finished copper strip to obtain a second semi-finished copper strip; S400: cooling, cooling the second semi-finished copper strip three times to obtain a third semi-finished copper strip; S500: Shearing: Shearing the third semi-finished copper strip according to actual needs to obtain a finished copper strip. For example, Figure 2 As shown, the S200 cold rolling includes the following steps: S201: subjecting the copper strip to be processed to a cold rolling process, wherein the cold rolling process temperature is 500°C ± 30°C and the duration is 8h ± 1h; S202: performing a secondary cold rolling treatment on the copper strip after the primary cold rolling treatment, wherein the secondary cold rolling treatment temperature is 600°C ±30°C and the duration is 11h ±1h; S203: performing a third cold rolling process on the copper strip after the second cold rolling process to obtain a first semi-finished copper strip, wherein the third cold rolling process is performed at a temperature of 650°C±10°C and for a duration of 14h-18h. For example, Figure 2 As shown, the S300 hot rolling includes the following steps: S301: subjecting the first semi-finished copper strip to a hot rolling treatment, wherein the hot rolling treatment temperature is 800° C.±10° C. and the duration is 2 h±0.5 h; Specifically, the first hot rolling is a preheating treatment, and the first semi-finished copper strip needs to be cooled before hot rolling, and the cooling temperature is 25°C ± 15°C (i.e. room temperature); S302: performing a secondary hot rolling treatment on the copper strip after the primary hot rolling treatment, wherein the secondary hot rolling treatment temperature is 1000°C ±10°C and the duration is 2h±0.5h; Specifically, the secondary hot rolling is a heating treatment; S303: performing a third hot rolling treatment on the copper strip after the second hot rolling treatment to obtain a second semi-finished copper strip, wherein the third hot rolling treatment temperature is 700° C.±10° C. and the duration is 4 h±0.5 h; Specifically, the three hot rolling processes are uniform heat treatments, so that each part of the first semi-finished copper strip receives heat evenly. For example, Figure 3 As shown, the S400 cooling includes the following steps: S401: performing a primary cooling treatment on the second semi-finished copper strip, wherein the ambient temperature of the primary cooling treatment is 400° C., until the temperature of the second semi-finished copper strip drops to 400° C.±10° C.; S402: performing a secondary cooling treatment on the copper strip after the primary cooling treatment, wherein the ambient temperature of the secondary cooling treatment is 150° C., until the temperature of the second semi-finished copper strip drops to 150° C.±10° C.; S403: The copper strip after the secondary cooling treatment is subjected to a tertiary cooling treatment, wherein the ambient temperature of the tertiary cooling treatment is 25°C, until the temperature of the copper strip drops to 25°C±15°C (i.e. normal room temperature), thereby obtaining a third semi-finished copper strip. After the copper strip is hot-rolled, it needs to be cooled three times, and the cooling temperature is decreasing each time, which are 400°C, 150°C and 25°C respectively, so that the cooling process of the copper strip is carried out in a step-by-step decreasing form, so that the copper strip will not be damaged by the rapid temperature change, thereby improving the yield of the copper strip.

[0025] When processing copper strip, it first needs to undergo three hot rolling treatments. The three hot rolling treatments correspond to preheating, heating and uniform heating respectively. The use of different temperatures and durations not only makes the copper strip heated more evenly, but also prevents the copper strip from being damaged due to excessive heating speed, thereby improving the quality of heat treatment.

[0026] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A deformation heat treatment process for a special-shaped copper strip for a lead frame, characterized in that: The following steps are involved: S100: trimming, taking the raw copper strip with a purity of 98.5%-99.5% and performing trimming treatment to obtain the copper strip to be treated; S200: cold rolling, performing cold rolling treatment on the copper strip to be processed three times to obtain a first semi-finished copper strip; S300: hot rolling, hot rolling the first semi-finished copper strip to obtain a second semi-finished copper strip; S400: Cooling: cooling the second semi-finished copper strip three times to obtain a third semi-finished copper strip.

2. The process for heat treatment of a shaped copper strip for a lead frame according to claim 1, characterized in that: The S200 cold rolling comprises the following steps: S201: subjecting the copper strip to be processed to a cold rolling process, wherein the cold rolling process temperature is 500° C.±30° C. and the duration is 8 h±1 h.

3. The process for heat treatment of a shaped copper strip for a lead frame according to claim 2, characterized in that: The S300 cold rolling further comprises the following steps: S202: subjecting the copper strip after the primary cold rolling treatment to a secondary cold rolling treatment, wherein the secondary cold rolling treatment temperature is 600°C±30°C and the duration is 11h±1h.

4. The process for heat treatment of a shaped copper strip for a lead frame according to claim 3, characterized in that: The S300 cold rolling further comprises the following steps: S203: performing a third cold rolling process on the copper strip after the second cold rolling process to obtain a first semi-finished copper strip, wherein the third cold rolling process is performed at a temperature of 650°C±10°C and for a duration of 14h-18h.

5. The process for thermomechanical treatment of a special-shaped copper strip for a lead frame according to claim 1, characterized in that: The S300 hot rolling comprises the following steps: S301: subjecting the first semi-finished copper strip to a hot rolling treatment, wherein the hot rolling treatment temperature is 800° C.±10° C. and the duration is 2 h±0.5 h; The first hot rolling is a preheating treatment. Before hot rolling, the first semi-finished copper strip needs to be cooled, and the cooling temperature is 25°C ± 15°C.

6. The process for thermomechanical treatment of a shaped copper strip for a lead frame according to claim 5, characterized in that: The S300 hot rolling further comprises the following steps: S302: performing a secondary hot rolling treatment on the copper strip after the primary hot rolling treatment, wherein the secondary hot rolling treatment temperature is 1000°C ±10°C and the duration is 2h±0.5h; The secondary hot rolling is a heating treatment.

7. The process for thermomechanical treatment of a shaped copper strip for a lead frame according to claim 6, characterized in that: The S300 hot rolling further comprises the following steps: S303: performing a third hot rolling treatment on the copper strip after the second hot rolling treatment to obtain a second semi-finished copper strip, wherein the third hot rolling treatment temperature is 700°C ±10°C and the duration is 4h±0.5h; The three hot rolling processes are uniform heat treatments, so that each part of the first semi-finished copper strip receives heat evenly.

8. The process for thermomechanical treatment of a shaped copper strip for a lead frame according to claim 7, characterized in that: The S400 cooling includes the following steps: S401: performing a primary cooling treatment on the second semi-finished copper strip, wherein the ambient temperature of the primary cooling treatment is 400° C., until the temperature of the second semi-finished copper strip drops to 400° C.±10° C.; S402: performing a secondary cooling treatment on the copper strip after the primary cooling treatment, wherein the ambient temperature of the secondary cooling treatment is 150° C., until the temperature of the second semi-finished copper strip drops to 150° C.±10° C.

9. The process for thermomechanical treatment of a special-shaped copper strip for a lead frame according to claim 8, characterized in that: The S400 cooling further comprises the following steps: S403: performing a third cooling treatment on the copper strip after the second cooling treatment, wherein the ambient temperature of the third cooling treatment is 25° C., until the temperature of the copper strip drops to 25° C.±15° C., to obtain a third semi-finished copper strip.

10. The process for thermomechanical treatment of a special-shaped copper strip for a lead frame according to claim 1, characterized in that: The heat treatment process also includes the following steps: S500: Shearing: Shearing the third semi-finished copper strip according to actual needs to obtain a finished copper strip.

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