High-bonding force pp-based film composite cu film based on nichrome transition layer, preparation method and application thereof

Abstract

This invention relates to the field of physical vapor deposition (PVD) technology, specifically to a high-adhesion PP-based composite Cu film based on a NiCr transition layer, its preparation method, and its applications. A stable interfacial transition structure is constructed by introducing a NiCr transition layer with a specific composition ratio and thickness range between the PP-based film and the Cu film. The NiCr transition layer contains 70%–90% Ni and has a thickness of 5–25 nm. By controlling the composition ratio and thickness range of the NiCr transition layer, an interfacial chemical bonding structure dominated by Cr-C and Cr-O bonds is formed at the PP-based film interface, while simultaneously achieving continuous and dense growth of the Cu film, thereby significantly improving the film-substrate adhesion of the composite Cu film. When the Ni to Cr mass ratio is 9:1 and the transition layer thickness is 10 nm, the adhesion of the composite Cu film can be increased to 47.70 gf / mm. This invention features a simple preparation process, strong controllability, and suitability for continuous production, making it applicable to lithium-ion battery current collectors, electromagnetic shielding materials, and electronic devices.

Description

Technical Field

[0001] This invention relates to the field of physical vapor deposition technology, specifically to a high-adhesion PP-based film composite Cu film based on a NiCr transition layer, its preparation method, and its application. Background Technology

[0002] PP-based films are widely used in lithium battery current collectors, electromagnetic shielding materials, and electronic devices due to their light weight, good flexibility, and high chemical stability. However, because PP material has low surface polarity and low surface energy, when copper films are directly deposited on its surface, metal atoms tend to grow in an island-like pattern, resulting in poor copper film density and low film-substrate adhesion, which seriously affects its reliability during subsequent electroplating, bending, and long-term service.

[0003] Existing technologies typically improve adhesion by optimizing Cu film deposition process parameters or introducing a metal transition layer. Chinese invention patent application CN202510547380.9 improves the adhesion and conductivity of Cu films by modifying DC magnetron sputtering process parameters; however, this method relies on the physical adsorption and van der Waals forces of copper atoms on the PP surface, making it difficult to fundamentally overcome the inherent defect of insufficient interfacial bonding strength caused by the inert surface of PP. Chinese invention patent application CN202311044478.X improves the adhesion of PP composite copper films by adding a NiXY multi-element alloy transition layer; however, this method only provides a broad range of alloy material selection directions and does not explore the synergistic influence of alloy ratio and thickness—two key parameters—on the electrical properties and adhesion of PP composite Cu films. Therefore, there is an urgent need for a preparation method that can precisely design the alloy composition ratio and thickness of the transition layer to achieve ultra-strong and stable interfacial adhesion while ensuring high conductivity, specifically targeting the interfacial characteristics of PP composite Cu films.

[0004] In view of the above-mentioned defects, the inventors of this invention have finally obtained this invention after a long period of research and practice. Summary of the Invention

[0005] The purpose of this invention is to solve the problems in the prior art where the interfacial bonding strength of PP composite Cu films is insufficient due to reliance on physical adsorption, and the difficulty in achieving high bonding strength of PP composite Cu films due to the lack of precise design of the alloy ratio and thickness of the transition layer. The invention provides a high-bonding-strength PP-based film composite Cu film based on a NiCr transition layer, its preparation method, and its application.

[0006] To achieve the above objectives, this invention discloses a method for preparing a high-adhesion PP-based film composite Cu film based on a NiCr transition layer, comprising the following steps:

[0007] S1 provides a flexible PP base film;

[0008] S2, a NiCr transition layer is deposited on the surface of a flexible PP base film using DC magnetron sputtering;

[0009] S3, Cu film is deposited on the surface of the NiCr transition layer obtained in step S2 to form a PP / NiCr / Cu composite structure.

[0010] In step S2, the mass ratio of Ni to Cr in the NiCr transition layer is 7:3 to 9:1, and the thickness is 5 to 25 nm.

[0011] In step S2, the mass ratio of Ni to Cr in the NiCr transition layer is 9:1, and the thickness is 10 nm.

[0012] In step S2, the DC magnetron sputtering power is 1.5 kW, the gas pressure is 0.24 Pa, the substrate stage speed is 2 r / min, and the deposition time is 30 s to 2.5 min.

[0013] In step S2, the temperature at which the NiCr transition layer is deposited is -15℃.

[0014] In step S3, the Cu film thickness is 50–100 nm.

[0015] In step S3, the temperature for depositing the Cu film is -15℃.

[0016] In step S3, Ar gas is used as the working gas during the deposition process, and the purity of Ar gas is not less than 99.99%.

[0017] This invention also discloses a high-adhesion PP-based film composite Cu film based on a NiCr transition layer prepared by the above-described method, and the application of this high-adhesion PP-based film composite Cu film based on a NiCr transition layer in the fields of lithium battery current collectors, electromagnetic shielding materials, and electronic devices.

[0018] This invention does not simply involve setting a metal transition layer between a PP base film and a Cu film. Instead, by limiting the composition ratio and thickness range of the NiCr transition layer, a synergistic structure is formed between Ni and Cr at the interface. Cr can form stable chemical bonds with the PP base film interface, improving interfacial bonding strength. Ni has better conductivity than Cr and, like Cu, has an FCC structure, which facilitates the formation of a substitution solid solution. This improves the adhesion of the Cu film while enhancing the density and conductivity of the metal layer. Through the synergistic ratio of these two elements and the control of the film thickness window, a stable bond between the polymer base film and the metal film is achieved. This technological advancement represents a significant technological breakthrough as it has not been effectively achieved in existing technologies.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] 1. This invention significantly improves the adhesion of Cu film to PP base film surface by introducing a NiCr transition layer with a specific composition ratio;

[0021] 2. The thickness and composition of the NiCr transition layer in this invention are controllable and have good repeatability. Attached Figure Description

[0022] Figure 1 The following are the test results of Cu film adhesion under NiCr transition layers of different ratios and thicknesses in Examples 1 and 3-16 of the present invention: (a) Ni:Cr=7:3; (b) Ni:Cr=8:2; (c) Ni:Cr=9:1;

[0023] Figure 2 The sheet resistance test results of Cu films under NiCr transition layers of different ratios and thicknesses in Examples 1, 3-16 and Comparative Example 1 of the present invention are as follows: (a) Ni:Cr=7:3; (b) Ni:Cr=8:2; (c) Ni:Cr=9:1;

[0024] Figure 3 These are XPS full spectrum images of different etching depths in Examples 1 and 2 of the present invention;

[0025] Figure 4 This is a graph showing the variation of elemental content at different etching depths in Examples 1 and 2 of the present invention;

[0026] Figure 5 The peak fitting results are for O 1s, Ni 2p, Cu 2p and Cr 2p in the third etched region of Examples 1 and 2 of the present invention.

[0027] Figure 6 The results are the C 1s peak fitting results for different etched regions in Examples 1 and 2 of the present invention. Detailed Implementation

[0028] The above-mentioned and other technical features and advantages of the present invention will be described in more detail below with reference to the accompanying drawings.

[0029] Example 1

[0030] The specific preparation method is as follows:

[0031] (1) A flexible organic PP base film with a thickness of 47 μm was placed in a roll-up magnetron sputtering equipment and fixed to the substrate stage with high-temperature tape. The chamber door was then closed. The chamber vacuum was evacuated to 2 × 10⁻⁶ using a mechanical pump and a molecular pump in sequence. -3 Below Pa;

[0032] (2) The purity of the NiCr and Cu targets used was 99.99%, and the size was 550 mm × 120 mm. The magnetron power supply was turned on, and a NiCr transition layer with a composition ratio of 8:2 was sputtered using the control panel. The sputtering power was 1.5 kW, the gas pressure was 0.24 Pa, the stage (cold drum) rotation speed was 2 r / min, the deposition time was 30 s, and the cold drum temperature was set to -15℃. Then, a Cu film was sputtered. Furthermore, high-temperature tape was used to prefabricate steps on the Si substrate (the areas covered by the high-temperature tape could not deposit a thin film, thus forming steps on the Si wafer). The film thickness was obtained by measuring the step height using a profilometer. The tested NiCr transition layer thickness was approximately 5 nm, and the Cu film thickness was approximately 80 nm.

[0033] (3) After the deposition process is completed, turn off the magnetic power supply; turn off the molecular pump and mechanical pump in sequence, and after the chamber temperature reaches room temperature, open the vent valve to take out the sample.

[0034] Example 2

[0035] The only difference between this embodiment and embodiment 1 is that in step (2), the magnetron sputtering time of the NiCr transition layer is set to 1 min and the thickness is 10 nm, the thickness of the magnetron sputtering Cu film is 20 nm, and XPS analysis is performed on PP / NiCr / Cu.

[0036] Example 3

[0037] The only difference between this embodiment and embodiment 1 is that in step (2), the time for magnetron sputtering the NiCr transition layer is set to 1 min and the thickness is about 10 nm.

[0038] Example 4

[0039] The only difference between this embodiment and embodiment 1 is that in step (2), the magnetron sputtering time for the NiCr transition layer is set to 1.5 min and the thickness is approximately 15 nm.

[0040] Example 5

[0041] The only difference between this embodiment and embodiment 1 is that in step (2), the magnetron sputtering time for the NiCr transition layer is set to 2 min and the thickness is about 20 nm.

[0042] Example 6

[0043] The only difference between this embodiment and embodiment 1 is that in step (2), the magnetron sputtering time for the NiCr transition layer is set to 2.5 min and the thickness is approximately 25 nm.

[0044] Example 7

[0045] The only difference between this embodiment and embodiment 1 is that in step (2), the composition ratio of the NiCr transition layer is set to 7:3, the magnetron sputtering time of the NiCr transition layer is 30 s, and the thickness is about 5 nm.

[0046] Example 8

[0047] The only difference between this embodiment and embodiment 1 is that in step (2), the composition ratio of the NiCr transition layer is set to 7:3, the magnetron sputtering time of the NiCr transition layer is 1 min, and the thickness is about 10 nm.

[0048] Example 9

[0049] The only difference between this embodiment and embodiment 1 is that in step (2), the composition ratio of the NiCr transition layer is set to 7:3, the magnetron sputtering time of the NiCr transition layer is 1.5 min, and the thickness is about 15 nm.

[0050] Example 10

[0051] The only difference between this embodiment and embodiment 1 is that in step (2), the composition ratio of the NiCr transition layer is set to 7:3, the magnetron sputtering time of the NiCr transition layer is 2 min, and the thickness is about 20 nm.

[0052] Example 11

[0053] The only difference between this embodiment and embodiment 1 is that in step (2), the composition ratio of the NiCr transition layer is set to 7:3, the magnetron sputtering time of the NiCr transition layer is 2.5 min, and the thickness is about 25 nm.

[0054] Example 12

[0055] The only difference between this embodiment and embodiment 1 is that in step (2), the composition ratio of the NiCr transition layer is set to 9:1, the magnetron sputtering time of the NiCr transition layer is 30 s, and the thickness is about 5 nm.

[0056] Example 13

[0057] The only difference between this embodiment and embodiment 1 is that in step (2), the composition ratio of the NiCr transition layer is set to 9:1, the magnetron sputtering time of the NiCr transition layer is 1 min, and the thickness is about 10 nm.

[0058] Example 14

[0059] The only difference between this embodiment and embodiment 1 is that in step (2), the composition ratio of the NiCr transition layer is set to 9:1, the magnetron sputtering time of the NiCr transition layer is 1.5 min, and the thickness is about 15 nm.

[0060] Example 15

[0061] The only difference between this embodiment and embodiment 1 is that in step (2), the composition ratio of the NiCr transition layer is set to 9:1, the magnetron sputtering time of the NiCr transition layer is 2 min, and the thickness is about 20 nm.

[0062] Example 16

[0063] The only difference between this embodiment and embodiment 1 is that in step (2), the composition ratio of the NiCr transition layer is set to 9:1, the magnetron sputtering time of the NiCr transition layer is 2.5 min, and the thickness is about 25 nm.

[0064] Comparative Example 1

[0065] The difference between this comparative example and Example 1 is that the NiCr transition layer was omitted.

[0066] I. Effects of NiCr transition layer composition ratio and thickness on Cu film adhesion

[0067] In Examples 1 and 3-16, the substrate temperature was -15℃, the NiCr target power was 1.5 kW, the deposition gas pressure was 0.24 Pa, the NiCr transition layer composition ratios were 7:3, 8:2, and 9:1, respectively, the deposition times were 30 seconds, 1 minute, 1.5 minutes, 2 minutes, and 2.5 minutes, respectively, and the cooling drum rotation speed was 2 r / min. The prepared NiCr transition layer thicknesses were approximately 5 nm, 10 nm, 15 nm, 20 nm, and 25 nm. The variation law of Cu film adhesion under different NiCr transition layer thicknesses and composition ratios is as follows: Figure 1 As shown. In Comparative Example 1, due to the absence of a NiCr transition layer, the Cu film deposited on the PP base film exhibited poor adhesion, making it impossible to obtain effective measurement values ​​during the peeling test. In Examples 1 and 3-16, when the NiCr transition layer composition ratio was 7:3, the Cu film adhesion gradually decreased with increasing NiCr transition layer deposition time. When the NiCr transition layer composition ratio was 8:2 and 9:1, the Cu film adhesion first increased and then decreased with increasing NiCr transition layer deposition time, reaching its highest point when the NiCr transition layer thickness was 10 nm. Comparing the Cu film adhesion with different NiCr transition layer composition ratios, the strongest Cu film adhesion was observed when the NiCr transition layer composition ratio was 9:1 and the NiCr transition layer thickness was 10 nm.

[0068] II. Influence of NiCr transition layer composition ratio and thickness on Cu film sheet resistance

[0069] In Examples 1, 3-16, and Comparative Example 1, the substrate temperature was -15℃, the target power was 1.5 kW, the deposition gas pressure was 0.24 Pa, the NiCr transition layer composition ratios were 7:3, 8:2, and 9:1, respectively, the deposition times were 0 seconds, 30 seconds, 1 minute, 1.5 minutes, 2 minutes, and 2.5 minutes, respectively, and the cooling drum rotation speed was 2 r / min. The prepared NiCr transition layer thicknesses were approximately 0 nm, 5 nm, 10 nm, 15 nm, 20 nm, and 25 nm. The variation of Cu film sheet resistance under different NiCr transition layer thicknesses and composition ratios is as follows: Figure 2 As shown, with the increase of NiCr transition layer deposition time, the sheet resistance of Cu film first decreases and then increases, reaching its lowest point when the NiCr transition layer thickness is 10 nm. The sheet resistance of Cu film varies little among different NiCr transition layer compositions, and is consistently less than 2 Ω / □.

[0070] III. Influence of NiCr transition layer composition ratio and thickness on Cu film interface structure

[0071] In Examples 1 and 2, the substrate temperature was -15℃, the NiCr target power was 1.5 kW, the deposition gas pressure was 0.24 Pa, the NiCr transition layer composition ratio was 8:2, the deposition time was 1 minute, the deposition thickness was 10 nm, and the cooling drum rotation speed was 2 r / min. Figure 3 The XPS full spectrum is shown at different etching depths. Cu, C and O elements were mainly detected, and Ni and Cr element signals were detected in the third to sixth etching. Figure 4 The variation of elemental content with etching depth is shown. During the third etching, the Cu content rapidly decreased to 33.66 at.%, and Ni and Cr signals were detected, indicating that the Cu-NiCr interface had been reached. During the fourth etching, the Ni content increased significantly, and the C signal strengthened, indicating that the PP-NiCr interface was located at this point. During the fifth and sixth etchings, the Ni and Cr contents decreased, while the C content increased sharply (from 22.01 to 64.59 at.%), indicating that it had entered the PP matrix. Therefore, peak fitting was performed on the O 1s, Ni 2p, Cu 2p, and Cr 2p elements in the third etched region, and the results are as follows: Figure 5 As shown. Cu 2p 3 / 2 The peak is located at 932.6 eV and Cu 2p. 1 / 2 The peak is located at 952.35 eV, with a peak spacing of 19.75 eV. Comparison with the NIST database reveals that the spacing and position of these two peaks are consistent with the characteristics of zero-valent Cu, indicating that Cu in this region mainly exists in elemental form. The two peaks at 852.68 eV and 870.18 eV in the fitted spectrum of Ni 2p correspond to Ni 2p... 3 / 2 and Ni 2p1 / 2 The two peaks are spaced 17.5 eV apart. Comparison with the NIST database reveals that the spacing and position of these two peaks are consistent with the characteristics of zero-valent Ni, confirming that Ni exists in elemental form. Cr 2p spectrum analysis shows that the binding energies at 576.46 eV and 583.75 eV correspond to the Cr 2p ions of metallic Cr. 3 / 2 and Cr 2p 1 / 2 This indicates the presence of a metallic Cr phase. Furthermore, the peak with a binding energy of 586.4 eV corresponds to the Cr 2p phase of the Cr₂O₃ phase in the O1s spectrum at the position of the 530.3 eV peak. 1 / 2 This indicates the presence of Cr2O3 in the film. The 531.6 eV peak in the O 1s spectrum corresponds to either Ni2O3 or Ni(OH)2 phase; however, no other obvious oxide peaks were observed in the Ni 2p spectrum, so it cannot be confirmed whether it is Ni2O3 or Ni(OH)2. Subsequently, peak fitting was performed on the C 1s spectra of the third to sixth etched regions, and the results are as follows. Figure 6 As shown in the figure, the C 1s spectra after the third and fourth etchings show the presence of CC / CH peaks and Cr3C2 peaks, indicating that Cr has formed chemical bonds with C; in the fifth and sixth etchings, only CC / CH peaks are present. This indicates that Cr-C chemical bonds are formed at both the NiCr-Cu and PP-NiCr interfaces. However, no obvious Cr-C peaks are observed in the Cr 2p spectra, possibly because Cr 2p... 3 / 2 The peak position is similar to that of Cr3C2, which causes the Cr-C peak signal to be masked.

[0072] In summary, XPS analysis shows that the NiCr transition layer enhances the bonding strength mainly because it forms Cr-O and Cr-C bonds at the PP base film interface, thereby strengthening the interfacial chemical bonding.

[0073] The above description is merely a preferred embodiment of the present invention and is illustrative rather than restrictive. Those skilled in the art will understand that many changes, modifications, and even equivalents can be made within the spirit and scope defined by the claims of the present invention, all of which will fall within the protection scope of the present invention.

Claims

1. A method for preparing a high-adhesion PP-based film composite Cu film based on a NiCr transition layer, characterized in that, Includes the following steps: S1 provides a flexible PP base film; S2, a NiCr transition layer is deposited on the surface of a flexible PP base film using DC magnetron sputtering; S3, Cu film is deposited on the surface of the NiCr transition layer obtained in step S2 to form a PP / NiCr / Cu composite structure.

2. The method for preparing a high-adhesion PP-based film composite Cu film based on a NiCr transition layer as described in claim 1, characterized in that, In step S2, the mass ratio of Ni to Cr in the NiCr transition layer is 7:3 to 9:1, and the thickness is 5 to 25 nm.

3. The method for preparing a high-adhesion PP-based film composite Cu film based on a NiCr transition layer as described in claim 1, characterized in that, In step S2, the mass ratio of Ni to Cr in the NiCr transition layer is 9:1, and the thickness is 10 nm.

4. The method for preparing a high-adhesion PP-based film composite Cu film based on a NiCr transition layer as described in claim 1, characterized in that, In step S2, the DC magnetron sputtering power is 1.5 kW, the gas pressure is 0.24 Pa, the substrate stage speed is 2 r / min, and the deposition time is 30 s to 2.5 min.

5. The method for preparing a high-adhesion PP-based film composite Cu film based on a NiCr transition layer as described in claim 1, characterized in that, In step S2, the temperature at which the NiCr transition layer is deposited is -15℃.

6. The method for preparing a high-adhesion PP-based film composite Cu film based on a NiCr transition layer as described in claim 1, characterized in that, In step S3, the Cu film thickness is 50–100 nm.

7. The method for preparing a high-adhesion PP-based film composite Cu film based on a NiCr transition layer as described in claim 1, characterized in that, In step S3, the temperature for depositing the Cu film is -15℃.

8. The method for preparing a high-adhesion PP-based film composite Cu film based on a NiCr transition layer as described in claim 1, characterized in that, In step S3, Ar gas is used as the working gas during the deposition process, and the purity of Ar gas is not less than 99.99%.

9. A high-adhesion PP-based film composite Cu film based on a NiCr transition layer, prepared by the preparation method according to any one of claims 1 to 8.

10. The application of a high-adhesion PP-based film composite Cu film based on a NiCr transition layer as described in claim 9 in the fields of lithium battery current collectors, electromagnetic shielding materials, and electronic devices.

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