Ultrathin electromagnetic shielding layer based on magnetron sputtering technology and preparation method thereof

Abstract

The invention discloses an ultrathin electromagnetic shielding layer based on a magnetron sputtering technology and a preparation method thereof, and the method comprises the steps: carrying out the oxygen plasma etching of the surface of a flexible substrate through a reactive ion etching technology, the reactive ion etching power ranges from 100 W to 140 W, so that an activated substrate surface chemical group is formed on the surface of the flexible substrate; a seed layer is formed on the etched surface of the flexible substrate in a sputtering mode through the magnetron sputtering technology, the thickness of the seed layer ranges from 1 nm to 100 nm, and the roughness of the seed layer is 10 nm or below; forming a layer of shielding metal film on the surface of the seed layer through sputtering by using a magnetron sputtering technology, wherein the thickness of the shielding metal film is less than 1 [mu] m; wherein the sputtering temperature in the magnetron sputtering process ranges from 100 DEG C to 150 DEG C.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to an ultrathin electromagnetic shielding layer based on magnetron sputtering technology and its preparation method. Background Technology

[0002] FPC (Flexible Printed Circuit Board), also known as flexible circuit board or flexographic board, is a type of printed circuit board made with polyimide or polyester film as the substrate. FPC has the characteristics of high reliability, excellent flexibility, light weight, thinness, and good bending ability, and is widely used in electronic products that require high-density wiring.

[0003] To prevent electromagnetic fields from affecting the electrical signals transmitted in Flexible Printed Circuit Board (FPC) circuitry, an electromagnetic shielding material needs to be applied to the critical signal transmission lines in specific locations within the FPC. This prevents external electromagnetic fields from interfering with signal transmission. Currently, the commonly used electromagnetic shielding material on the market is an electromagnetic shielding film. This material is manufactured by third-party companies and is easily processed. After purchasing it, FPC manufacturers attach the electromagnetic shielding film to the FPC surface through a series of processes, including punching, machine bonding, pressing, and baking. This protects the signal transmission of the circuitry layer beneath the electromagnetic shielding film. The electromagnetic shielding film typically consists of conductive materials (such as copper, aluminum, and silver), conductive adhesive, and a protective film. The conductive materials have excellent conductivity, guiding electromagnetic waves away from the FPC circuitry and providing shielding. The protective film protects the inner conductive materials from oxidation, improving reliability.

[0004] However, the thickness of commercial electromagnetic shielding films is currently quite thick. Although the thickness of conductive adhesive in electromagnetic shielding films has been gradually reduced to 3 μm and the thickness of organic polymer films has been reduced to 5 μm, almost reaching the limit of industry technical capabilities, their thickness is still relatively thick, which affects the further thinning of FPCs and the further improvement of their bending capabilities.

[0005] The above content is only used to help understand the technical solution of the present invention and does not represent an admission that the above content is prior art. Summary of the Invention

[0006] The main objective of this invention is to provide an ultrathin electromagnetic shielding layer based on magnetron sputtering technology and its preparation method, in order to solve the above-mentioned problems.

[0007] To achieve the above objectives, the present invention provides a method for preparing an ultrathin electromagnetic shielding layer based on magnetron sputtering technology, the method comprising:

[0008] Provide flexible substrates;

[0009] The surface of a flexible substrate is etched with oxygen plasma using reactive ion etching technology to form activated chemical groups on the substrate surface. The reactive ion etching power is 100-140W and the gas pressure is 1-15mTorr.

[0010] A seed layer is formed by sputtering the etched surface of the flexible substrate using magnetron sputtering technology. The thickness of the seed layer is 1-100 nm and the roughness is less than 10 nm.

[0011] A shielding metal film is formed on the surface of the seed layer by magnetron sputtering technology, and the thickness of the shielding metal film is less than 1 μm;

[0012] During magnetron sputtering, the sputtering temperature is 100℃-150℃, and the slope of the resistance fitting curve of the ultrathin electromagnetic shielding layer after 500,000 bends is less than or equal to 7×10⁻⁶. -6 ;

[0013] The total thickness of the metal seed layer and the shielding metal film is less than 2 μm.

[0014] Preferably, in the method for preparing the ultrathin electromagnetic shielding layer based on magnetron sputtering technology, when the sputtering temperature is between 100℃ and 150℃ during the magnetron sputtering process, the holding time is 1-5 hours.

[0015] Preferably, in the method for preparing the ultrathin electromagnetic shielding layer based on magnetron sputtering technology, the gas flow rate of reactive ion etching is 1~50 SCCM and the time is 1~30 min.

[0016] Preferably, in the method for preparing the ultrathin electromagnetic shielding layer based on magnetron sputtering technology, the flexible substrate is made of a flexible thin film or a flexible circuit board.

[0017] The seed layer is made of one of Cr, Ti, or Ni-Cr.

[0018] The material of the shielding metal film is one of Cu, Al, or Cu-Al.

[0019] Preferably, in the method for preparing the ultrathin electromagnetic shielding layer based on magnetron sputtering technology, when the seed layer material is Ni-Cr, the mass fraction ratio of Ni to Cr in Ni-Cr is 1:4.

[0020] Preferably, in the method for preparing the ultrathin electromagnetic shielding layer based on magnetron sputtering technology, the sputtering power of the seed layer is 1-150W, the gas pressure is 0.1-3Pa, and the sample disk rotation speed is 1-10r / min.

[0021] Preferably, in the method for preparing the ultrathin electromagnetic shielding layer based on magnetron sputtering technology, the sputtering power of the shielding metal film is 1~100 W, the sputtering gas pressure is 0.1~3.0 Pa, and the sample disk rotation speed is 1~10 r / min.

[0022] Preferably, in the method for preparing the ultrathin electromagnetic shielding layer based on magnetron sputtering technology, in the step of performing oxygen plasma etching on the surface of the flexible substrate using reactive ion etching technology, the etching gas is O2 or Ar.

[0023] Preferably, in the method for preparing the ultrathin electromagnetic shielding layer based on magnetron sputtering technology, after the step of forming a shielding metal film on the surface of the seed layer using magnetron sputtering technology, the method further includes:

[0024] The shielding metal film is subjected to heat annealing treatment at a temperature of 50-200℃ and a holding time of 1-5 hours.

[0025] To achieve the above objectives, the present invention provides an ultrathin electromagnetic shielding layer based on magnetron sputtering technology, characterized in that the ultrathin electromagnetic shielding layer is prepared by the above-described preparation method.

[0026] To achieve the above objectives, the present invention provides an application of magnetron sputtering technology, which is applied to the flexible circuit board with the aforementioned ultra-thin electromagnetic shielding layer.

[0027] The present invention has at least the following beneficial effects:

[0028] The present invention provides a method for preparing an ultrathin electromagnetic shielding layer based on magnetron sputtering technology. The method involves performing oxygen plasma etching on the surface of a flexible substrate using reactive ion etching (RIE) to form activated surface chemical groups. The RIE power is 100-140W. A seed layer is then sputtered onto the etched surface of the flexible substrate using magnetron sputtering. The seed layer has a thickness of 1-100 nm and a roughness of less than 10 nm. Finally, a shielding metal film with a thickness of less than 1 μm is sputtered onto the seed layer using magnetron sputtering. The sputtering temperature during magnetron sputtering is 100℃-150℃. This method results in an ultrathin electromagnetic shielding layer (seed layer and shielding metal film) with a thickness of less than 2 μm, and the conductive adhesive thickness can be reduced to zero.

[0029] Furthermore, this invention employs magnetron sputtering technology to form a shielding metal film, resulting in a thinner film with better bending resistance and higher adhesion. Additionally, the shielding metal film of this invention simplifies the structure, allowing the removal of the conductive adhesive layer from traditional shielding structures.

[0030] Furthermore, the present invention can effectively reduce the thickness of the shielding metal film through magnetron sputtering process, while achieving the same or better electromagnetic shielding effect as existing shielding films; the thickness of the shielding film layer can be further reduced, promoting the thinning of flexible boards and further improving their bending performance.

[0031] Furthermore, the ultrathin electromagnetic shielding layer provided by this invention, while ensuring that the thickness of the obtained ultrathin electromagnetic shielding layer (metal seed layer and shielding metal film) is less than 2μm, has a slope of less than or equal to 7×10⁻⁶ for the change in resistance fitting curve after 500,000 bends. -6 Furthermore, the peel strength can reach over 1 N / mm. Attached Figure Description

[0032] Figure 1 A schematic diagram illustrating the method for fabricating an ultrathin electromagnetic shielding layer based on magnetron sputtering technology provided by the present invention;

[0033] Figure 2 The bending performance diagram is for Comparative Example 6;

[0034] Figure 3 The bending performance diagram is for Comparative Example 7;

[0035] Figure 4 This is a bending performance diagram of Example 1.

[0036] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0037] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The present invention will be described in detail below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0038] In this embodiment of the invention, the term "and / or" describes the relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. The character " / " generally indicates that the preceding and following associated objects have an "or" relationship.

[0039] It should be noted that the terms "first," "second," etc., in the specification, claims, and drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0040] In this embodiment of the invention, the term "multiple" refers to two or more, and other quantifiers are similar.

[0041] In this invention, unless otherwise stated, directional terms such as "upper," "lower," "top," and "bottom" are generally used in relation to the direction shown in the accompanying drawings, or in relation to the vertical, perpendicular, or gravitational direction of the component itself; similarly, for ease of understanding and description, "inner" and "outer" refer to the inner and outer contours of each component itself, but the above directional terms are not intended to limit this invention.

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the various embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details are presented in the embodiments of the present invention to facilitate a better understanding of the invention. However, the technical solutions claimed in the present invention can be implemented even without these technical details and various variations and modifications based on the following embodiments. The division of the following embodiments is for ease of description and should not constitute any limitation on the specific implementation of the present invention. The various embodiments can be combined with and referenced by each other without contradiction.

[0043] This invention provides a method for preparing an ultrathin electromagnetic shielding layer based on magnetron sputtering technology. Figure 1 The diagram illustrates the method for preparing an ultrathin electromagnetic shielding layer based on magnetron sputtering technology provided by the present invention.

[0044] In step S100, a flexible substrate is provided. The flexible substrate is made of a flexible film or a flexible circuit board. In some other embodiments, the flexible substrate may also be made of other materials, which are not specifically limited here.

[0045] In step S200, oxygen plasma etching is performed on the surface of the flexible substrate using reactive ion etching technology to form activated substrate surface chemical groups. The reactive ion etching power is 100-140W and the gas pressure is 1-15mTorr.

[0046] Oxygen plasma etching is performed on the surface of a flexible substrate using reactive ion etching technology, forming activated chemical groups on the substrate surface. This facilitates the removal of residual impurities and adsorbed air molecules from the flexible substrate surface. The chemical reaction between oxygen and the flexible substrate generates activated chemical groups on the substrate surface, resulting in stronger adhesion. This process not only removes surface contaminants from the flexible substrate but also improves adhesion, enhancing the bond between the substrate and the shielding metal film.

[0047] Both excessively high and insufficient reactive ion etching power can lead to poor adhesion. Therefore, in this embodiment, the reactive ion etching power is 100-140W. In some embodiments, the reactive ion etching power can also be 110W, 120W, or 130W.

[0048] In some embodiments, the etching gas in reactive ion etching (RIE) is O2 or Ar. In other embodiments, the etching gas in RIE can be other gases, and no specific limitations are made here.

[0049] Excessive or insufficient gas pressure during reactive ion etching (RIE) can affect the peel strength. Therefore, in this embodiment, the gas pressure for RIE is 1-15 mTorr; in some embodiments, the gas pressure for RIE can also be 2 mTorr, 5 mTorr, or 8 mTorr. The gas flow rate for RIE is 1-50 SCCM, and the time is 1-30 min.

[0050] In step S300, a seed layer is formed by sputtering the etched surface of the flexible substrate using magnetron sputtering technology. The seed layer has a thickness of 1-100 nm, a roughness of less than 10 nm, and a sputtering temperature of 100℃-150℃ during the magnetron sputtering process.

[0051] The seed layer primarily serves as a buffer and stress release mechanism. Its thickness cannot be too large, as this would affect its flexibility. The seed layer is mainly used to connect the flexible substrate and the shielding metal film for buffering and stress release; if it is too thin, the desired buffering and stress release effects will not be achieved. Therefore, in this embodiment, the seed layer thickness is 1-100 nm. In some embodiments, the seed layer thickness can also be 20 nm, 40 nm, 60 nm, or 80 nm.

[0052] In this process, excessively low temperatures during magnetron sputtering result in poor adhesion, weak bonding, and the inability to desorb adsorbed impurities and gas molecules from the surface. Conversely, excessively high temperatures also lead to poor adhesion. Therefore, in this embodiment, the sputtering temperature in step S300 is 100℃-150℃, and the holding time is 1-5 hours. In other embodiments, the sputtering temperature in step S300 can also be 120℃ or 140℃.

[0053] Excessive sputtering power in the seed layer leads to excessive residual stress, resulting in too many cracks; conversely, insufficient sputtering power results in poor adhesion. Sputtering power and gas pressure interact during magnetron sputtering. In this embodiment, the sputtering power of the seed layer is 1-150W, and the gas pressure is 0.1-3Pa. In some embodiments, the sputtering power of the seed layer can also be 20W, 50W, or 100W. In some embodiments, the gas pressure can also be 0.5Pa, 1Pa, 1.5Pa, or 2Pa.

[0054] The sample disk rotation speed affects the uniformity of the seed layer. A higher rotation speed results in a more uniform seed layer, but excessively high rotation speeds place excessive demands on the equipment; conversely, insufficient rotation speeds lead to an uneven seed layer. Furthermore, excessively high rotation speeds result in a very slow deposition rate. To ensure both seed layer uniformity and deposition rate, in this embodiment, the sample disk rotation speed is 1-10 r / min. In other embodiments, the sample disk rotation speed can also be 3 r / min, 5 r / min, or 8 r / min.

[0055] When the seed layer is bonded to the flexible substrate, the bonding force is influenced by the sputtering power, gas pressure, and sample disk rotation speed during the magnetron sputtering process. Higher sputtering power, higher gas pressure, and lower sample disk rotation speed result in lower residual stress; conversely, lower sputtering power, lower gas pressure, and higher sample disk rotation speed result in higher residual stress. Therefore, in this embodiment, the sputtering power of the seed layer is 1-150W, the gas pressure is 0.1-3Pa, and the sample disk rotation speed is 1-10r / min.

[0056] In some embodiments, the seed layer is made of one of Cr, Ti, or Ni-Cr, wherein the mass fraction ratio of Ni to Cr in Ni-Cr is 1:4. In some embodiments, the seed layer is made of Cr, and using Cr as an adhesion layer can enhance adhesion to the flexible substrate.

[0057] In step S400, a shielding metal film is formed on the surface of the seed layer by magnetron sputtering technology, and the thickness of the shielding metal film is less than 1 μm; wherein, the sputtering temperature during the magnetron sputtering process is 100℃-150℃.

[0058] In this process, if the temperature of the shielding metal film is too low during magnetron sputtering, the adhesion will be poor, the bonding force will be weak, and the adsorbed impurities and gas molecules on the surface will not be able to desorb. Conversely, if the temperature is too high, the adhesion will also deteriorate. Therefore, in this embodiment, the sputtering temperature in step S300 is 100℃-150℃, and the holding time is 1-5 hours. In other embodiments, the sputtering temperature in step S400 can be 120℃ or 140℃. In other embodiments, the holding time in step S400 can be 2 hours or 3 hours. By maintaining the sputtering temperature for a certain duration during the sputtering process, a constant temperature can be maintained to ensure good crystallization of the shielding metal film.

[0059] Excessive sputtering power of the shielding metal film leads to excessive residual stress, resulting in too many cracks; conversely, insufficient sputtering power results in poor adhesion. Sputtering power and gas pressure interact during magnetron sputtering. In this embodiment, the sputtering power of the shielding metal film is 1-100W, and the gas pressure is 0.1-3Pa. In some embodiments, the sputtering power of the seed layer can also be 20W, 50W, or 80W. In some embodiments, the gas pressure can also be 0.5Pa, 1Pa, 1.5Pa, or 2Pa.

[0060] The sample disk rotation speed affects the uniformity of the shielding metal film. A higher rotation speed results in a more uniform film, but excessively high speeds place excessive demands on the equipment; conversely, insufficient rotation speeds lead to uneven film formation. Furthermore, excessively high rotation speeds result in a very slow deposition rate. To ensure both uniformity and deposition rate, in this embodiment, the sample disk rotation speed is 1-10 r / min. In other embodiments, the rotation speed can be 3 r / min, 5 r / min, or 8 r / min.

[0061] When the shielding metal film is bonded to the seed layer, the bonding force is influenced by the sputtering power, gas pressure, and sample disk rotation speed during the magnetron sputtering process. Higher sputtering power, higher gas pressure, and lower sample disk rotation speed result in lower residual stress; conversely, lower sputtering power, lower gas pressure, and higher sample disk rotation speed result in higher residual stress. Therefore, in this embodiment, the sputtering power of the shielding metal film is 1-100W, the gas pressure is 0.1-3Pa, and the sample disk rotation speed is 1-10r / min.

[0062] In some embodiments, the material of the shielding metal film is one of Cu, Al, or Cu-Al. By selecting Al or Cu as the material of the shielding metal film, the shielding metal film can have the best bending effect.

[0063] After step S400, step S500 is also included.

[0064] In step S500, the shielding metal film is subjected to thermal annealing at a temperature of 50-200℃ and a holding time of 1-5 hours.

[0065] Thermal annealing of the shielding metal film can relieve stress. If the annealing temperature is too low, the shielding metal film will not achieve the desired stress relief; if the annealing temperature is too high, it will lead to abnormal grain growth and structural deterioration of the shielding metal film. Therefore, in some embodiments, the annealing temperature is 50-200℃, and the holding time is 1-5 hours. In other embodiments, the annealing temperature can also be 100℃ or 150℃.

[0066] This invention utilizes magnetron sputtering technology to form a shielding metal film, resulting in a thinner film with better bending resistance and higher adhesion. Furthermore, the shielding metal film of this invention simplifies the structure, allowing the removal of the conductive adhesive layer in traditional shielding structures.

[0067] The present invention provides a method for preparing an ultrathin electromagnetic shielding layer based on magnetron sputtering technology. The method involves performing oxygen plasma etching on the surface of a flexible substrate using reactive ion etching (RIE) to form activated surface chemical groups. The RIE power is 100-140W. A seed layer is then sputtered onto the etched surface of the flexible substrate using magnetron sputtering. The seed layer has a thickness of 1-100 nm and a roughness of less than 10 nm. Finally, a shielding metal film with a thickness of less than 1 μm is sputtered onto the seed layer using magnetron sputtering. The sputtering temperature during magnetron sputtering is 100℃-150℃. This method results in an ultrathin electromagnetic shielding layer (seed layer and shielding metal film) with a thickness of less than 2 μm, and the conductive adhesive thickness can be reduced to zero.

[0068] This invention also provides an ultrathin electromagnetic shielding layer based on magnetron sputtering technology, which is prepared using the above-described preparation method. The embodiments of this ultrathin electromagnetic shielding layer based on magnetron sputtering technology include embodiments of the above-described preparation method for ultrathin electromagnetic shielding layers based on magnetron sputtering technology, and the beneficial effects of the above-described preparation method for ultrathin electromagnetic shielding layers based on magnetron sputtering technology can also be applied to this ultrathin electromagnetic shielding layer based on magnetron sputtering technology.

[0069] This invention provides an application of magnetron sputtering technology, which is applied to a flexible circuit board with the aforementioned ultrathin electromagnetic shielding layer. The embodiments of the magnetron sputtering technology include those with the aforementioned ultrathin electromagnetic shielding layer, and the beneficial effects of the ultrathin electromagnetic shielding layer can be applied to this magnetron sputtering technology.

[0070] Example 1

[0071] S1, oxygen plasma etching is performed on the surface of the flexible substrate using reactive ion etching technology to form activated substrate surface chemical groups on the surface of the flexible substrate. The reactive ion etching power is 120W, the etching gas pressure is 10mTorr, the O2 flow rate is 50 SCCM, and the time is 2 min. The flexible substrate is an FPC and a PI substrate.

[0072] S2 employs a magnetron sputtering system for sputtering the shielded metal film and seed layer. Before sputtering, the vacuum level in the coating machine chamber reaches 6×10⁻⁶. -4 When Pa is reached, the substrate heating function is activated, the heating temperature is 100 ℃, and the holding time is 2 h.

[0073] S3. A 35 nm thick Cr seed layer with a roughness of less than 10 nm was formed by sputtering on the etched surface of the flexible substrate using magnetron sputtering technology. The Cr target was sputtered using a 100 W DC power supply, the Ar flow rate was 10 SCCM, the sputtering pressure was 2.0 Pa, the sample disk rotation speed was 10 r / min to ensure uniform film thickness, and the sputtering time was 2.5 min.

[0074] S4. A 300 nm thick Cu shielding metal film was sputtered on the surface of the Cr seed layer using magnetron sputtering technology. The Cu target was sputtered using a 110 W DC power supply, the Ar flow rate was 15 SCCM, the sputtering pressure was 1.4 Pa, the sample disk rotation speed was 10 r / min to ensure uniform film thickness, and the sputtering time was 11 min.

[0075] The sputtering temperature during magnetron sputtering is 100℃.

[0076] Comparative Example 1

[0077] S1. A 70 nm thick Cr seed layer was sputtered at room temperature on an unheated and unetched FPC and PI substrate using magnetron sputtering technology. The Cr target was sputtered using a 100 W DC power supply, the Ar flow rate was 10 SCCM, the sputtering pressure was 2.0 Pa, the sample disk rotation speed was 10 r / min to ensure uniform film thickness, and the sputtering time was 5.0 min.

[0078] S2, continue to deposit a 300 nm thick Cu shielding layer on the Cr seed layer at room temperature. The Cu target is sputtered with a 110 W DC power supply, the Ar flow rate is 15 SCCM, the sputtering pressure is 1.4 Pa, the sample disk rotation speed is 10 r / min to ensure uniform film thickness, and the sputtering time is 11 min, finally obtaining the electromagnetic shielding layer.

[0079] Comparative Example 2

[0080] S1 employs a magnetron sputtering system for sputtering the shielded metal film and seed layer. Before sputtering, the vacuum level in the coating machine chamber reaches 6×10⁻⁶. -4 When Pa is reached, the substrate heating function is activated, the heating temperature is 50 ℃, and the holding time is 2 h.

[0081] S2, then a 35 nm thick Cr seed layer was deposited on the heated unetched FPC and PI substrate. The Cr target was sputtered using a 100 W DC power supply, the Ar flow rate was 10 SCCM, the sputtering pressure was 2.0 Pa, the sample disk rotation speed was 10 r / min to ensure uniform film thickness, and the sputtering time was 2.5 min.

[0082] S3. Continue to deposit a 300 nm thick Cu shielding layer on the Cr seed layer. The Cu target is sputtered using a 110 W DC power supply, the Ar flow rate is 15 SCCM, the sputtering pressure is 1.4 Pa, the sample disk rotation speed is 10 r / min to ensure uniform film thickness, and the sputtering time is 11 min, finally obtaining the electromagnetic shielding layer.

[0083] Comparative Example 3

[0084] S1 employs a magnetron sputtering system for sputtering the shielded metal film and seed layer. Before sputtering, the vacuum level in the coating machine chamber reaches 6×10⁻⁶. -4 When Pa is reached, the substrate heating function is activated, the heating temperature is 100 ℃, and the holding time is 2 h.

[0085] S2, then a 35 nm thick Cr seed layer was deposited on the heated unetched FPC and PI substrate. The Cr target was sputtered using a 100 W DC power supply, the Ar flow rate was 10 SCCM, the sputtering pressure was 2.0 Pa, the sample disk rotation speed was 10 r / min to ensure uniform film thickness, and the sputtering time was 2.5 min.

[0086] S3. Continue to deposit a 300 nm thick Cu shielding layer on the Cr seed layer. The Cu target is sputtered using a 110 W DC power supply, the Ar flow rate is 15 SCCM, the sputtering pressure is 1.4 Pa, the sample disk rotation speed is 10 r / min to ensure uniform film thickness, and the sputtering time is 11 min, finally obtaining the electromagnetic shielding layer.

[0087] Comparative Example 4

[0088] S1, oxygen plasma etching is performed on the surface of the flexible substrate using reactive ion etching technology to form activated substrate surface chemical groups on the surface of the flexible substrate. The reactive ion etching power is 150W, the etching gas pressure is 50mTorr, the O2 flow rate is 50 SCCM, and the time is 2 min. The flexible substrate is an FPC and a PI substrate.

[0089] S2 employs a magnetron sputtering system for sputtering the shielded metal film and seed layer. Before sputtering, the vacuum level in the coating machine chamber reaches 6×10⁻⁶. -4 When Pa is reached, the substrate heating function is activated, the heating temperature is 100 ℃, and the holding time is 2 h.

[0090] S3. A 35 nm thick Cr seed layer with a roughness of less than 10 nm was formed by sputtering on the etched surface of the flexible substrate using magnetron sputtering technology. The Cr target was sputtered using a 100 W DC power supply, the Ar flow rate was 10 SCCM, the sputtering pressure was 2.0 Pa, the sample disk rotation speed was 10 r / min to ensure uniform film thickness, and the sputtering time was 2.5 min.

[0091] S4. A 300 nm thick Cu shielding metal film was sputtered on the surface of the Cr seed layer using magnetron sputtering technology. The Cu target was sputtered using a 110 W DC power supply, the Ar flow rate was 15 SCCM, the sputtering pressure was 1.4 Pa, the sample disk rotation speed was 10 r / min to ensure uniform film thickness, and the sputtering time was 11 min.

[0092] The sputtering temperature during magnetron sputtering is 100℃.

[0093] Comparative Example 5

[0094] S1, oxygen plasma etching is performed on the surface of the flexible substrate using reactive ion etching technology to form activated substrate surface chemical groups on the surface of the flexible substrate. The reactive ion etching power is 120W, the etching gas pressure is 50mTorr, the O2 flow rate is 50 SCCM, and the time is 2 min. The flexible substrate is an FPC and a PI substrate.

[0095] S2 employs a magnetron sputtering system for sputtering the shielded metal film and seed layer. Before sputtering, the vacuum level in the coating machine chamber reaches 6×10⁻⁶. -4 When Pa is reached, the substrate heating function is activated, the heating temperature is 100 ℃, and the holding time is 2 h.

[0096] S3. A 35 nm thick Cr seed layer with a roughness of less than 10 nm was formed by sputtering on the etched surface of the flexible substrate using magnetron sputtering technology. The Cr target was sputtered using a 100 W DC power supply, the Ar flow rate was 10 SCCM, the sputtering pressure was 2.0 Pa, the sample disk rotation speed was 10 r / min to ensure uniform film thickness, and the sputtering time was 2.5 min.

[0097] S4. A 300 nm thick Cu shielding metal film was sputtered on the surface of the Cr seed layer using magnetron sputtering technology. The Cu target was sputtered using a 110 W DC power supply, the Ar flow rate was 15 SCCM, the sputtering pressure was 1.4 Pa, the sample disk rotation speed was 10 r / min to ensure uniform film thickness, and the sputtering time was 11 min.

[0098] The sputtering temperature during magnetron sputtering is 100℃.

[0099] Comparative Example 6

[0100] It uses a commercial electromagnetic shielding layer, model SF-PC3900R1-C.

[0101] Comparative Example 7

[0102] It uses a commercial electromagnetic shielding layer, model SF-PC5900R1-C.

[0103] Table 1. Comparison of shielding layer adhesion results between the examples and comparative examples under different conditions.

[0104]

[0105] As can be seen from Table 1, the peel strength of the ultrathin electromagnetic shielding layer provided by the present invention can reach more than 1 N / mm, which has a significant advantage over the adhesion effect of the comparative example. The peel strength of the ultrathin electromagnetic shielding layer provided in the embodiments in Table 1 is even more than twice that of the comparative example.

[0106] A comparison of the bending performance of the ultrathin electromagnetic shielding layer in Example 1 with that in Comparative Examples 6 and 7 is shown below. Figures 2 to 4 . Figure 2 The diagram illustrates the bending performance of Comparative Example 6; Figure 3 The diagram illustrates the bending performance of Comparative Example 7; Figure 4 The diagram illustrates the bending performance of Example 1. From... Figures 2 to 4 It can be seen that the ultra-thin electromagnetic shielding layer provided by this invention has the best bending effect. The slope of the resistance fitting curve after 500,000 bends of the ultra-thin electromagnetic shielding layer provided by this invention is very small, much lower than the slope of the resistance fitting curves of the shielding layers provided by Comparative Example 6 and Comparative Example 7.

[0107] The slope of the resistance fitting curve of the ultrathin electromagnetic shielding layer provided by this invention after 500,000 bends is less than or equal to 7 × 10⁻⁶. -6 The slope of the resistance fitting curve of the ultrathin electromagnetic shielding layer provided in Example 1 after 500,000 bends is 7 × 10⁻⁶. -6 (like Figure 4 (As shown). However, the slope of the resistance fitting curve after 500,000 bends of the electromagnetic shielding layer provided in the prior art is much greater than 7 × 10⁻⁶. -6 For example, the slope of the resistance fitting curve after the electromagnetic shielding layer provided in Comparative Example 6 is 4 × 10⁻⁶ after being bent 500,000 times is 4 × 10⁻⁶. -5 (like Figure 2 As shown in the figure, the slope of the resistance fitting curve after the electromagnetic shielding layer provided in Example 7 is 3 × 10⁻⁶ after being bent 500,000 times. -5 (like Figure 3 (As shown).

[0108] For further explanation, the following description uses examples and comparative examples.

[0109] Example 2

[0110] S1, oxygen plasma etching is performed on the surface of the flexible substrate using reactive ion etching technology to form activated substrate surface chemical groups on the surface of the flexible substrate. The reactive ion etching power is 120W, the etching gas pressure is 10mTorr, the O2 flow rate is 50 SCCM, and the time is 2 min. The flexible substrate is an FPC and a PI substrate.

[0111] S2 employs a magnetron sputtering system for sputtering the shielded metal film and seed layer. Before sputtering, the vacuum level in the coating machine chamber reaches 6×10⁻⁶. -4 When Pa is reached, the substrate heating function is activated, the heating temperature is 100 ℃, and the holding time is 2 h.

[0112] S3. A 35 nm thick Cr seed layer with a roughness of less than 10 nm was formed by sputtering on the etched surface of the flexible substrate using magnetron sputtering technology. The Cr target was sputtered using a 100 W DC power supply, the Ar flow rate was 10 SCCM, the sputtering pressure was 2.0 Pa, the sample disk rotation speed was 10 r / min to ensure uniform film thickness, and the sputtering time was 2.5 min.

[0113] S4. A 500 nm thick Cu shielding metal film was sputtered on the surface of the Cr seed layer using magnetron sputtering technology. The Cu target was sputtered using a 110 W DC power supply, the Ar flow rate was 15 SCCM, the sputtering pressure was 1.4 Pa, the sample disk rotation speed was 10 r / min to ensure uniform film thickness, and the sputtering time was 11 min.

[0114] The sputtering temperature during magnetron sputtering is 100℃.

[0115] Example 3

[0116] S1, oxygen plasma etching is performed on the surface of the flexible substrate using reactive ion etching technology to form activated substrate surface chemical groups on the surface of the flexible substrate. The reactive ion etching power is 120W, the etching gas pressure is 10mTorr, the O2 flow rate is 50 SCCM, and the time is 2 min. The flexible substrate is an FPC and a PI substrate.

[0117] S2 employs a magnetron sputtering system for sputtering the shielded metal film and seed layer. Before sputtering, the vacuum level in the coating machine chamber reaches 6×10⁻⁶. -4 When Pa is reached, the substrate heating function is activated, the heating temperature is 100 ℃, and the holding time is 2 h.

[0118] S3. A 35 nm thick Cr seed layer with a roughness of less than 10 nm was formed by sputtering on the etched surface of the flexible substrate using magnetron sputtering technology. The Cr target was sputtered using a 100 W DC power supply, the Ar flow rate was 10 SCCM, the sputtering pressure was 2.0 Pa, the sample disk rotation speed was 10 r / min to ensure uniform film thickness, and the sputtering time was 2.5 min.

[0119] S4. A 1 μm thick Cu shielding metal film was sputtered on the surface of the Cr seed layer using magnetron sputtering technology. The Cu target was sputtered using a 110 W DC power supply, the Ar flow rate was 15 SCCM, the sputtering pressure was 1.4 Pa, the sample disk rotation speed was 10 r / min to ensure uniform film thickness, and the sputtering time was 11 min.

[0120] The sputtering temperature during magnetron sputtering is 100℃.

[0121] Comparative Example 8

[0122] It uses a commercial electromagnetic shielding layer, model SF-5900-Ag (300nm).

[0123] Table 2 Comparison of shielding effectiveness between the examples and comparative examples

[0124]

[0125] Table 2 illustrates a comparison of the shielding effectiveness of the embodiments and comparative examples. Comparative example 8 corresponds to the commercial SF-5900-Ag (300nm). The electromagnetic shielding layers used in embodiments 1 to 3 are under the same conditions, differing only in the thickness of Cr and Cu. As can be seen from Table 2, the ultrathin electromagnetic shielding layer provided by this invention exhibits significantly higher shielding effectiveness than comparative example 7.

[0126] Obviously, the embodiments described above are merely some, not all, embodiments of the present invention. Based on the embodiments of the present invention, those skilled in the art can make other variations or modifications without creative effort, and all such variations or modifications should fall within the scope of protection of the present invention.

Claims

1. A method for fabricating an ultrathin electromagnetic shielding layer based on magnetron sputtering technology, characterized in that, include: Provide flexible substrates; The surface of a flexible substrate is etched with oxygen plasma using reactive ion etching technology to form activated chemical groups on the substrate surface. The reactive ion etching power is 100-140W and the gas pressure is 1-15mTorr. A seed layer is formed by sputtering the etched surface of the flexible substrate using magnetron sputtering technology. The thickness of the seed layer is 1-100 nm and the roughness is less than 10 nm. A shielding metal film is formed on the surface of the seed layer by magnetron sputtering technology, and the thickness of the shielding metal film is less than 1 μm; During magnetron sputtering, the sputtering temperature is 100℃-150℃, and the slope of the resistance fitting curve of the ultrathin electromagnetic shielding layer after 500,000 bends is less than or equal to 7×10⁻⁶. -6 ; The total thickness of the metal seed layer and the shielding metal film is less than 2 μm.

2. The method for preparing an ultrathin electromagnetic shielding layer based on magnetron sputtering technology as described in claim 1, characterized in that, During magnetron sputtering, when the sputtering temperature is between 100℃ and 150℃, the holding time is 1-5 hours.

3. The method for preparing an ultrathin electromagnetic shielding layer based on magnetron sputtering technology as described in claim 1, characterized in that, The gas flow rate for reactive ion etching is 1~50 SCCM and the time is 1~30 min.

4. The method for preparing an ultrathin electromagnetic shielding layer based on magnetron sputtering technology as described in claim 3, characterized in that, The flexible substrate is made of flexible film or flexible circuit board. The seed layer is made of one of Cr, Ti, or Ni-Cr. The material of the shielding metal film is one of Cu, Al, or Cu-Al.

5. The method for preparing an ultrathin electromagnetic shielding layer based on magnetron sputtering technology as described in claim 4, characterized in that, When the seed layer is made of Ni-Cr, the mass fraction ratio of Ni to Cr in Ni-Cr is 1:

4.

6. The method for preparing an ultrathin electromagnetic shielding layer based on magnetron sputtering technology as described in claim 1, characterized in that, The sputtering power of the seed layer is 1-150W, the gas pressure is 0.1-3Pa, and the sample disk rotation speed is 1-10r / min.

7. The method for preparing an ultrathin electromagnetic shielding layer based on magnetron sputtering technology as described in claim 1, characterized in that, The sputtering power of the shielding metal film is 1~100 W, the sputtering gas pressure is 0.1~3.0 Pa, and the sample disk rotation speed is 1~10 r / min.

8. The method for preparing an ultrathin electromagnetic shielding layer based on magnetron sputtering technology as described in claim 1, characterized in that, In the step of oxygen plasma etching of the flexible substrate surface using reactive ion etching technology, the etching gas is O2 or Ar.

9. The method for preparing an ultrathin electromagnetic shielding layer based on magnetron sputtering technology as described in claim 1, characterized in that, After the step of forming a shielding metal film on the surface of the seed layer using magnetron sputtering technology, the method further includes: The shielding metal film is subjected to heat annealing treatment at a temperature of 50-200℃ and a holding time of 1-5 hours.

10. An ultrathin electromagnetic shielding layer based on magnetron sputtering technology, characterized in that, The ultrathin electromagnetic shielding layer is prepared using the preparation method described in any one of claims 1 to 9.

11. An application of magnetron sputtering technology, characterized in that, The magnetron sputtering technology is applied to flexible circuit boards with ultra-thin electromagnetic shielding layers as described in claim 10.

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