A cold rolling process of low stress high precision surface low expansion alloy 4J42 foil

Abstract

The application discloses a cold rolling process of low-stress high-precision surface low-expansion alloy 4J42 foil, which comprises the following steps: rough rolling: the blank is cold rolled to a first thickness, and cleaning and first annealing are carried out; wire drawing and secondary rolling: the strip is subjected to wire drawing treatment and cleaning, and is secondly rolled to a second thickness; intermediate annealing and micro-injury wire drawing: the strip is cleaned and secondly annealed, and is subjected to wire drawing treatment and cleaning by using a scouring pad; super-precision surface rolling: the strip is rolled to a finished product thickness by multiple passes and is cleaned, and the surface roughness of the working roller used for rolling is arranged in a gradient decreasing manner along the rolling direction; shape pre-locking and stress elimination: the hard-state foil rolled to the finished product thickness is subjected to shape correction by tension, and is finally annealed. The application can solve the problem that the existing rolling process is difficult to meet the processing requirements of low stress, high flatness and super-smooth surface of the ultra-thin 4J42 foil.

Description

Technical Field

[0001] This invention relates to the field of foil rolling technology, specifically a cold rolling process for low-stress, high-precision, low-expansion alloy 4J42 foil. Background Technology

[0002] 4J42 alloy, due to its coefficient of thermal expansion matching that of glass and ceramics, is widely used in packaging materials for precision instruments, lead frames, and substrate materials for microelectromechanical systems (MEMS). With the miniaturization and increasing precision of devices, the demand for foil materials with a thickness of less than 0.25 mm is growing, and extremely stringent requirements are being placed on them.

[0003] Low internal stress: During subsequent micro-processing such as photolithography and chemical etching, the release of residual stress in foil materials can lead to pattern distortion and material warping, which seriously affects the accuracy of the device.

[0004] Ultra-high surface quality: The surface roughness needs to be extremely low, typically Ra<0.1μm or even lower, to ensure coating uniformity, etching accuracy and device reliability.

[0005] Excellent sheet shape: Controlling the sheet shape and flatness of ultra-thin foil is extremely difficult.

[0006] Traditional processes typically employ an "annealing → straightening" procedure to ensure sheet shape and soften the material. However, for ultra-thin foils, straightening introduces new residual stress, which is difficult to completely eliminate during subsequent low-temperature stress-relief annealing and may affect sheet shape. Furthermore, to achieve a smooth surface, traditional processes rely on final polishing or high-gloss rolling. However, if earlier processes, such as wire drawing, leave excessively deep surface grooves, these are difficult to completely eliminate during ultra-thin rolling, easily leading to surface color differences or microscopic unevenness. Therefore, existing processes struggle to simultaneously meet the processing requirements of low stress, high flatness, and an ultra-smooth surface for ultra-thin 4J42 foils. Summary of the Invention

[0007] The purpose of this invention is to provide a cold rolling process for low-stress, high-precision surface, and ultra-smooth surface alloy 4J42 foil, in order to solve the problem that existing rolling processes cannot simultaneously meet the processing requirements of low stress, high flatness, and ultra-smooth surface of ultra-thin 4J42 foil.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: a cold rolling process for low-stress, high-precision, low-expansion alloy 4J42 foil, comprising the following steps:

[0009] S1. Rough rolling: The 4J42 alloy billet is initially cold rolled to the first thickness, and then cleaned and subjected to the first annealing softening heat treatment;

[0010] S2. Wire drawing and secondary rolling: The strip after the first annealing is wire drawn and cleaned, and then rolled to the second thickness.

[0011] S3. Intermediate Annealing and Micro-wound Fiber Drawing: The strip after secondary rolling is cleaned and annealed for the second time, and then drawn with a scouring pad. It is cleaned immediately after the process.

[0012] S4. Ultra-precision surface rolling: The strip processed in step S3 is rolled to the finished thickness through multiple passes and then cleaned. The finished thickness is less than or equal to 0.25 mm. During the rolling process, the surface roughness of the work rolls is set to decrease in a gradient along the rolling direction, and the last pass uses a polishing roll with a surface roughness Ra less than or equal to 0.05 μm.

[0013] S5. Plate shape pre-locking and stress relief: The hard foil rolled to the finished thickness is first stretched and straightened to correct the plate shape; then the stretched and straightened foil is finally annealed under a protective atmosphere to eliminate the processing stress inside the material.

[0014] As a further description of the above technical solution:

[0015] In step S1, the first thickness is 1.5-2.5 mm, and the first annealing is continuous bright annealing or box annealing at 1000-1100℃.

[0016] As a further description of the above technical solution:

[0017] In step S2, the second thickness is 0.4-0.6 mm.

[0018] As a further description of the above technical solution:

[0019] In step S3, the second annealing is a continuous bright annealing at 800-950°C.

[0020] As a further description of the above technical solution:

[0021] In step S3, the scouring pad is made of nylon and its abrasive mesh size ranges from 600 mesh to 2000 mesh.

[0022] As a further description of the above technical solution:

[0023] In step S4, at least three different roughnesses of work rolls are used, with the roughness values ​​decreasing sequentially, and the roughness difference between adjacent work rolls not exceeding Ra0.5μm;

[0024] The working rolls include: a first-stage texturing roll with a roughness Ra of 0.5-1.0 μm, a second-stage finishing roll with a roughness Ra of 0.1-0.5 μm, and a third-stage polishing roll with a roughness Ra of less than or equal to 0.1 μm.

[0025] As a further description of the above technical solution:

[0026] In step S5, the set elongation rate of the tension straightening is 0.5%-1.0%.

[0027] As a further description of the above technical solution:

[0028] In step S5, the final annealing is a continuous bright annealing at 750-900°C.

[0029] In summary, due to the adoption of the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0030] The cold rolling process of this invention adds a cleaning step after rolling and drawing to completely remove all material particles and foreign matter, preventing residual particles and ash from being pressed in and causing abnormal particle spots on the board surface. The strip is rolled a second time to 0.5mm and annealed. Then, a scouring pad is used for drawing to make the grooves formed on the surface shallow, ensuring high surface consistency. For the ultra-precision rolling process of rolling foil from 0.5mm to 0.2mm, the rolling process is adjusted to use gradient roughness rolls, from coarse to fine, with the roll roughness change not exceeding [a certain value]. With a surface roughness of Ra0.5μm, a texturing roller is used to homogenize the surface, and a gradient roughness roller is used to gradually improve the surface. Finally, a polishing roller with Ra0.03μm is used to achieve high-quality foil forming. Compared with the conventional process of annealing before tension straightening, this process adopts a design of tension straightening before annealing, and sets the elongation rate of tension straightening to 0.5%-1.0%. This allows the material to be tension straightened and flattened in a hard state, ensuring that the material has reached a flat state before heat treatment. This can ensure the material sheet shape while completely eliminating residual stress in the foil and improving the quality of cold rolling. Attached Figure Description

[0031] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a flowchart of the cold rolling process for a low-stress, high-precision, low-expansion alloy 4J42 foil.

[0033] Figure 2This is a photograph of a 4J42 foil, a low-stress, high-precision, low-expansion alloy, being rolled by polishing rollers in step S4 during the cold rolling process.

[0034] Figure 3 This is a photograph of the foil after straightening in step S5 of the cold rolling process of a low-stress, high-precision, low-expansion alloy 4J42 foil. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0036] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0037] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0038] In the description of the embodiments of the present invention, it should be noted that the terms "upper" and "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0039] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection, an indirect connection through an intermediate medium, or a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0040] Example 1:

[0041] Please see Figure 1-3This invention provides a technical solution: a cold rolling process for low-stress, high-precision, low-expansion alloy 4J42 foil. The cold rolling process in this embodiment is used to produce 0.2mm thick 4J42 foil with a surface roughness of less than Ra0.07μm. The process flow is as follows: rough rolling - cleaning - heat treatment - wire drawing - cleaning - secondary rolling - cleaning - annealing - wire drawing - cleaning - rolling - cleaning - tension leveling - annealing. This results in a foil with low internal stress and extremely low surface roughness, which allows users to perform etching processing on the foil, ensuring that the finished product is free from stress deformation and warping after etching.

[0042] The process specifically includes the following steps:

[0043] S1. Rough rolling: The 3.5mm thick 4J42 alloy billet is initially cold rolled to the first thickness, and then cleaned and subjected to the first annealing softening heat treatment.

[0044] S2. Wire drawing and secondary rolling: The strip after the first annealing is wire drawn and cleaned, and then rolled to the second thickness.

[0045] S3. Intermediate Annealing and Micro-wound Fiber Drawing: The strip after secondary rolling is cleaned and annealed for the second time, and then drawn with a scouring pad. It is cleaned immediately after the process.

[0046] S4. Ultra-precision surface rolling: The strip processed in step S3 is rolled to the finished thickness through multiple passes and then cleaned. The finished thickness is less than or equal to 0.25 mm, specifically 0.2 mm. During the rolling process, the surface roughness of the work rolls is set to decrease in a gradient along the rolling direction, and the last pass uses polishing rolls with a surface roughness Ra less than or equal to 0.05 μm.

[0047] S5. Plate shape pre-locking and stress relief: The hard foil rolled to the finished thickness is first stretched and straightened to correct the plate shape; then the stretched and straightened foil is finally annealed under a protective atmosphere to eliminate the processing stress inside the material.

[0048] Specifically, in step S1, the first thickness is 1.5-2.5mm, preferably 1.8mm, and the first annealing is continuous bright annealing or box annealing at 1000-1100℃.

[0049] In step S2, the second thickness is 0.4-0.6 mm, preferably 0.5 mm.

[0050] In step S3, the second annealing is a continuous bright annealing at 800-950°C.

[0051] In step S5, the set elongation rate of the tension straightening is 0.5%-1.0%.

[0052] In step S5, the final annealing is a continuous bright annealing at 750-900°C.

[0053] The cold rolling process of this invention adds a cleaning step after rolling and drawing to completely remove all material particles and foreign matter, preventing residual particles and ash from being pressed in and causing abnormal particle spots on the board surface. The strip is rolled a second time to 0.5mm and annealed. Then, a scouring pad is used for drawing to make the grooves formed on the surface shallow, ensuring high surface consistency. For the ultra-precision rolling process of rolling foil from 0.5mm to 0.2mm, the rolling process is adjusted to use gradient roughness rolls, from coarse to fine, with the roll roughness change not exceeding [a certain value]. With a surface roughness of Ra0.5μm, a texturing roller is used to homogenize the surface, and a gradient roughness roller is used to gradually improve the surface. Finally, a polishing roller with Ra0.03μm is used to achieve high-quality foil forming. Compared with the conventional process of annealing before tension straightening, this process adopts a design of tension straightening before annealing, and sets the elongation rate of tension straightening to 0.5%-1.0%. This allows the material to be tension straightened and flattened in a hard state, ensuring that the material has reached a flat state before heat treatment. This can ensure the material sheet shape while completely eliminating residual stress in the foil and improving the quality of cold rolling.

[0054] Example 2:

[0055] Please see Figure 1 The figure illustrates a cold rolling process for a low-stress, high-precision, low-expansion alloy 4J42 foil according to Embodiment 2 of the present invention. This embodiment further improves upon the previous embodiment by making the following technical improvements: In step S3, the scouring pad is made of nylon, with an abrasive mesh size ranging from 600 to 2000 mesh. Compared to conventional abrasive belt drawing methods, this design significantly reduces the depth of the grooves formed on the strip surface, ensuring high surface consistency.

[0056] Example 3:

[0057] Please see Figure 1-2 The figure shows a cold rolling process for a low-stress, high-precision, low-expansion alloy 4J42 foil provided in Embodiment 3 of the present invention. Based on the above embodiments, this embodiment further makes the following improved technical solutions: In step S4, at least three different roughness work rolls are used, and their roughness values ​​decrease sequentially, with the roughness difference between adjacent work rolls not exceeding Ra0.5μm.

[0058] The working rolls include: a first-stage texturing roll with a roughness Ra of 0.5-1.0 μm, a second-stage finishing roll with a roughness Ra of 0.1-0.5 μm, and a third-stage polishing roll with a roughness Ra of less than or equal to 0.1 μm.

[0059] Specifically, the adjustment design of the rolling process for the ultra-precision rolling process from 0.5mm to 0.2mm is shown in the table below:

[0060] path Strip entry thickness / mm Strip export thickness / mm Indentation / mm reduction rate Work roll type and surface roughness Ra 1 0.500 0.420 0.080 16.0％ Texturing roller 1.0μm 2 0.420 0.357 0.063 15.0％ Texturizing roller 0.7μm 3 0.357 0.307 0.050 14.0％ Texturizing roller 0.5μm 4 0.307 0.267 0.040 13.0％ 0.3μm precision roller 5 0.267 0.235 0.032 12.0％ 0.2μm precision roller 6 0.235 0.210 0.025 10.0％ Polishing roller 0.1μm 7 0.210 0.200 0.010 4.8％ Polishing roller 0.03μm

[0061] Specifically, seven rolling passes are set, with the reduction amount and reduction rate of each pass gradually decreasing sequentially. The first three passes use texturing rolls with roughness Ra of 1.0μm, 0.7μm, and 0.5μm respectively. The middle two passes use finishing rolls with roughness Ra of 0.3μm and 0.2μm respectively. The last two passes use polishing rolls with roughness Ra of 0.1μm and 0.03μm respectively. This improves the quality of multi-pass rolling processing with gradient surface roughness, resulting in a uniform and compliant surface roughness of the finished foil.

[0062] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A cold rolling process for low-stress, high-precision, low-expansion alloy 4J42 foil, characterized in that, Includes the following steps: S1. Rough rolling: The 4J42 alloy billet is initially cold rolled to the first thickness, and then cleaned and subjected to the first annealing softening heat treatment; S2. Wire drawing and secondary rolling: The strip after the first annealing is wire drawn and cleaned, and then rolled to the second thickness. S3. Intermediate Annealing and Micro-wound Fiber Drawing: The strip after secondary rolling is cleaned and annealed for the second time, and then drawn with a scouring pad. It is cleaned immediately after the process. S4. Ultra-precision surface rolling: The strip processed in step S3 is rolled to the finished thickness through multiple passes and then cleaned. The finished thickness is less than or equal to 0.25 mm. During the rolling process, the surface roughness of the work rolls is set to decrease in a gradient along the rolling direction, and the last pass uses a polishing roll with a surface roughness Ra less than or equal to 0.05 μm. S5. Plate shape pre-locking and stress relief: The hard foil rolled to the finished thickness is first stretched and straightened to correct the plate shape; then the stretched and straightened foil is finally annealed under a protective atmosphere to eliminate the processing stress inside the material.

2. The cold rolling process for a low-stress, high-precision, low-expansion alloy 4J42 foil according to claim 1, characterized in that, In step S1, the first thickness is 1.5-2.5 mm, and the first annealing is continuous bright annealing or box annealing at 1000-1100℃.

3. The cold rolling process for a low-stress, high-precision, low-expansion alloy 4J42 foil according to claim 1, characterized in that, In step S2, the second thickness is 0.4-0.6 mm.

4. The cold rolling process for a low-stress, high-precision, low-expansion alloy 4J42 foil according to claim 1, characterized in that, In step S3, the second annealing is a continuous bright annealing at 800-950°C.

5. The cold rolling process for a low-stress, high-precision, low-expansion alloy 4J42 foil according to claim 1, characterized in that, In step S3, the scouring pad is made of nylon and its abrasive mesh size ranges from 600 mesh to 2000 mesh.

6. The cold rolling process for a low-stress, high-precision, low-expansion alloy 4J42 foil according to claim 1, characterized in that, In step S4, at least three different roughnesses of work rolls are used, with the roughness values ​​decreasing sequentially, and the roughness difference between adjacent work rolls not exceeding Ra0.5μm; The working rolls include: a first-stage texturing roll with a roughness Ra of 0.5-1.0 μm, a second-stage finishing roll with a roughness Ra of 0.1-0.5 μm, and a third-stage polishing roll with a roughness Ra of less than or equal to 0.1 μm.

7. The cold rolling process for a low-stress, high-precision, low-expansion alloy 4J42 foil according to claim 1, characterized in that, In step S5, the set elongation rate of the tension straightening is 0.5%-1.0%.

8. The cold rolling process for a low-stress, high-precision, low-expansion alloy 4J42 foil according to claim 1, characterized in that, In step S5, the final annealing is a continuous bright annealing at 750-900°C.

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