Coated electromagnetic interference (EMI) shielding mesh, method of producing the same, and applications thereof

Abstract

The present invention relates to metal coated electromagnetic interference (EMI) shields and specifically the present invention relates to a mesh or cloth coated with metal plating solution for use in shielding from EMI and wireless communication signals, and a method of producing the same.

Description

[0001] COATED ELECTROMAGNETIC INTERFERENCE (EMI) SHIELDING MESH, METHOD OF PRODUCING THE SAME, AND APPLICATIONS THEREOF

[0002] TECHNICAL FIELD OF THE INVENTION

[0003] The present invention relates to metal coated electromagnetic interference (EMI) shields and specifically the present invention relates to a mesh or cloth coated with metal plating solution for use in shielding from EMI and wireless communication signals, and a method of producing the same.

[0004] BACKGROUND AND PRIOR ART OF THE INVENTION

[0005] The radiation which is a key for the functioning of mobile phones, however the same is a health hazard. Therefore, there is a need to suppress the radiation in a specific area of a residence.

[0006] Electronic components are sources of electromagnetic (EM) radiation. Electronic components such as mobile phones, transmitters, transceivers, microcontrollers, microprocessors and the like radiate a portion of the electric signals propagating through a device as EM radiation. Said electronic devices can be enclosed in a shield and may be made of various materials, for example, metal sheets, plastic composites, conductive polymer sprays, metal-filled epoxy pastes and the like. The shields absorb the EM radiation and act as EMIs.

[0007] There are some reports known in the art which cover EMI shielding and its application. For example, Chinese patent CN117569076A covers a preparation method of an aramid fiber for electromagnetic shielding comprising - immersing aramid fibers in a mixed solution of a diamine monomer containing active carboxyl, pyridine or imidazole units / ethanol and a metal salt such as nickel sulfate, then immersing in a TMC / n-hexane solution, treating with a reducing agent such as NaBH4 at 40 °C to form a metal such as nickel nanoparticles on the fiber surface, and finally passing the obtained fiber through a metal electroless plating solution wherein the metal can be nickel or silver and the nickel-plating solution contains NiCh bHiO, NaHiPCE-HiO (sodium hypophosphite): NasCeHTh^HiO (sodium citrate), and NH4CI at a pH of 8.5-9.5, to form a continuous metal conductive layer on the fiber surface to afford the aramid fiber for electromagnetic shielding. However, this aramid fiber as substrate contains aromatic polyamide, with ^-electronic configuration, and this ^-electronic configuration causes instability due to oxidation in the coating of metal for EMI shielding. Thus, there is need in the art to provide a net or mesh cloth which is easy to use to shield EM radiation and can potentially act as EMI shield product effectively.

[0008] The present invention addresses the need for EMI shielding materials that can be used in the context of preventing the residential areas from EMs by using the surface-modified nets or cloths.

[0009] OBJECTS OF THE INVENTION

[0010] The general object of the present disclosure is to provide materials for use in shielding from EMI and wireless communication signals in residential and / or commercial settings.

[0011] An object of the present disclosure is to provide a mesh or cloth coated with metal plating solution for use in shielding from EMI and wireless communication signals.

[0012] Another object of the present disclosure is to provide a method of producing a mesh or cloth coated with metal plating solution for use in shielding from EMI and wireless communication signals.

[0013] SUMMARY OF THE INVENTION

[0014] Aspects of the invention relate to metal coated electromagnetic interference (EMI) shields and specifically the present invention relates to a mesh or cloth coated with metal plating solution for use in shielding from EMI and wireless communication signals.

[0015] In another aspect, the present disclosure provides an electromagnetic interference (EMI) shielding net or cloth coated with metal plating solution for use in residential area comprising a mesh or cloth coated with metal plating solution which is used as an EMI shielding material.

[0016] In an aspect of the present invention, the EMI shielding coating material is selected from but not limited to nickel, silver, palladium, lead, or a combination thereof.

[0017] In an aspect, the present disclosure provides an electromagnetic interference (EMI) shielding material, comprising: a substrate coated with a metal coating layer or film, wherein the metal coating layer or film is based on metal selected from nickel, silver, palladium, and lead, or a combination thereof, the substrate is selected from mesh, cloth, fabric, web, mat, and screen, and wherein the substrate does not comprise 71 electrons. In an embodiment, the mesh is an expanded metal mesh, a metal wire screen, or a metal- plated fabric sheet.

[0018] In an embodiment the mesh is made of a material selected from fiberglass mesh, polyester mesh, polymeric material-based mesh, metal wires, carbon fibers, graphite fibers, inherently- conductive polymer fiber, and a metal or metal alloy, or any of combination thereof.

[0019] In an embodiment, a thickness of the metal coating layer or film onto the substrate is in the range of 10 to 500 nm.

[0020] In an embodiment, the cloth or the fabric is made of a material selected from cotton, wool, silk, cellulose, polyester, polyamide, nylon, and polyimide, or any of combination thereof. In an embodiment, the metal wire screen of the mesh is having a diameter in the range of 50 to 200 pm.

[0021] In an embodiment, the inherently-conductive polymer fiber is selected from polyester, polyamide, nylon, and polyimide monofilaments and yarns.

[0022] In an embodiment, the metal or metal alloy is selected from copper, nickel, silver, aluminum, bronze, steel, tin, stainless steel (SS), and iron, or any of combination thereof.

[0023] In an aspect, the present disclosure provides a process of preparation of the EMI shielding material, comprising: a) providing a substrate; b) optionally treating and immersing with a metal solution to obtain a sample; c) treating the sample of step b) with a reducing agent to reduce metal contained in the sample to obtain metal nanoparticle coated or anchored substrate material; d) immersing the substrate of step a) or the metal nanoparticle coated or anchored substrate material of step c) in a metal plating solution bath, followed by heating at a temperature in the range of 30-70°C to obtain the EMI shielding material; wherein the metal plating solution comprises a metal selected from nickel, silver, palladium, and lead, or a combination thereof.

[0024] In an embodiment, when the metal plating solution is based on nickel metal, then the metal plating solution comprises nickel sulfate or nickel chloride, ammonium chloride, sodium hypophosphite, sodium citrate, and ammonium hydroxide.

[0025] In an embodiment, when the metal plating solution is based on palladium metal, then the metal plating solution comprises palladium chloride, ammonium chloride, sodium hypophosphite, hydrochloric acid, and ammonium hydroxide. In an embodiment, when the metal plating solution is based on silver metal, then the metal plating solution comprises silver nitrate or silver chloride, ammonium chloride, cobalt chloride, and ammonium hydroxide.

[0026] In an embodiment, when the metal plating solution is based on lead metal, then the metal plating solution comprises lead acetate or lead chloride, thiourea, and ethylene diamine tetraacetic acid (EDTA).

[0027] In an embodiment, the pH of the in the range of metal plating solution bath is in the range of 8-11.

[0028] In an embodiment, the metal solution of step b) comprises a metal selected from nickel, silver, palladium, and lead, or a combination thereof.

[0029] In an embodiment, the reducing agent is selected from sodium borohydride, and hydrazine hydrate.

[0030] In an embodiment, when the metal plating solution is based on nickel metal, then the metal plating solution comprises 1-5% w / v of nickel sulphate or nickel chloride, 1-10% w / v of ammonium chloride, 1-5% w / v of sodium hypophosphite, and 1-10% w / v of sodium citrate.

[0031] In an embodiment, when the metal plating solution is based on palladium metal, then the metal plating solution comprises 0.05-0.5% w / v of palladium chloride dissolved in 10-20% v / v of hydrochloric acid, 40-80% w / v of ammonium chloride, 1-4% w / v of sodium hypophosphite, 5-11% w / v of hydrochloric acid, and 0.5 to 5 ml of ammonium hydroxide.

[0032] In an embodiment, when the metal plating solution is based on palladium metal, then the metal plating solution comprises 0.01-09% w / v of palladium chloride, 30-80% w / v of ammonium chloride, 2.4% w / v of sodium hypophosphite, 5-11% w / v of hydrochloric acid, and 5- 10 ml of ammonium hydroxide.

[0033] In an embodiment, when the metal plating solution is based on silver metal, then the metal plating solution comprises 0.1-0.3% w / v of silver nitrate or silver chloride, 1-1.5% w / v of ammonium chloride, and 0.5-0.6% w / v of cobalt chloride.

[0034] In an embodiment, when the metal plating solution is based on silver metal, then the metal plating solution comprises 1-3% w / v of lead acetate, 0.1-0.5% w / v of thiourea, and 0.01- 0.03% w / v of EDTA.

[0035] In specific aspect, the present invention provides a method of coating the mesh with metal plating solution to afford the EMI shielding material comprising the steps of:

[0036] (a) providing a mesh;

[0037] (b) anchoring Ni2+on the fibers or wires of the mesh; (c) immersing the Ni2+-anchored mesh in NaBt , which reduces the Ni2+into Ni nanoparticles to obtain Ni nanoparticle-coated mesh; and

[0038] (d) immersing the Ni nanoparticle-coated mesh in Ni plating solution to obtain the Ni film- covered mesh.

[0039] In specific aspect, the present invention provides a method of coating the cloth with metal plating solution to afford the EMI shielding material comprising the steps of:

[0040] (a) providing a cloth;

[0041] (b) anchoring Ni2+on the fibers of the cloth by immersing the same in NiSCh solution;

[0042] (c) immersing the Ni2+-anchored mesh in NaBtU, which reduces the Ni2+into Ni nanoparticles to obtain Ni nanoparticle-coated mesh; and

[0043] (d) immersing the Ni nanoparticle-coated mesh in Ni plating solution to obtain the Ni film- covered cloth.

[0044] In another specific aspect, the present invention provides a method of coating the SS mesh with metal plating solution to afford the EMI shielding material comprising the steps of: a. providing a mesh; b. immersing the Ni nanoparticle-coated mesh in Ni plating solution to obtain the Ni film covered mesh.

[0045] In an aspect of the present invention, the nickel-plating solution comprises 3-5% w / v of nickel sulphate, 3-5% w / v of ammonium chloride, 3-5% w / v of sodium hypophosphite, 3-5% w / v of sodium citrate, Ammonium hydroxide q.s. to adjust the pH of the nickel-plating solution to 8-9. In some embodiments, the temperature of the palladium plating solution is 60 °C. In an aspect of the present invention, the palladium plating solution comprises 0.05-0.5% w / v of Palladium chloride dissolved in 10-20% v / v of HC1 (based on total plating solution volume), 40-80% w / v of ammonium chloride, 1-4% w / v of sodium hypophosphite, 5-11% w / v of HC1, Ammonium hydroxide 0.5 to 5 ml to adjust the pH of the palladium plating solution to 8-9. In some embodiments, the temperature of the palladium plating solution is 60 °C.

[0046] In an aspect of the present invention, the silver plating solution comprises 0.1 - 0.3% w / v of silver nitrate, 0.8- 1.2% w / v of ammonium chloride, 0.2 - 0.7% w / v of cobalt chloride, Ammonium hydroxide q.s. to adjust the pH of the palladium plating solution to 10.8. In some embodiments, the temperature of the silver plating solution is 70 °C.

[0047] In an aspect of the present invention, the lead plating solution comprises 1-3% w / v of lead acetate, 0.1 - 0.9% w / v of thiourea, and 0.01-0.06% w / v of EDTA. In some embodiments, the temperature of the lead plating solution is 70 °C. BREIF DESCRIPITION OF THE DRAWINGS

[0048] Fig. 1 depicts the EMI shielding efficiency of cotton and stainless steel-based substrates.

[0049] Fig. 2 depicts the SEM image of uncoated cloth (a) and its elemental data (b). Morphology of nickel modified cloth (c) and its elemental mapping data (d).

[0050] Fig. 3 depicts the SEM image of uncoated stainless steel with small space (a) and its elemental data (b). Morphology of nickel-modified stainless steel with small space (c) and its elemental mapping data (d).

[0051] Fig. 4 depicts the SEM image of uncoated stainless steel with large space (a) and its elemental data (b). Morphology of nickel-modified stainless steel with large space (c) and its elemental mapping data (d).

[0052] DETAILED DESCRPITION OF THE INVENTION

[0053] The invention will now be described in detail in connection with certain preferred and optional embodiments, so that various aspects thereof may be more fully understood and appreciated.

[0054] Embodiments of the present invention relates to coated electromagnetic interference (EMI) shields and specifically the present invention relates to a mesh, cloth, fabric, web, mat, screen, and the like coated with metal plating solution for use in shielding from EMI and wireless communication signals.

[0055] In the literature, nickel is deposited by anchoring Sn2+, which reduces Ag+to Ag. The Ag reduces Pd2+to Pd. This Pd reduces Ni2+to Ni. In contrast to this, the present invention covers Ni2+is anchored on the cloth or mesh, followed by reducing the Ni2+with NaBH4 to Ni, which subsequently reduces Ni2+to nickel film.

[0056] In an embodiment of the present invention, the mesh can be, for example, an expanded metal mesh or a metal wire screen, or a metal-plated fabric sheet.

[0057] In an embodiment of the present invention, the wires of the mesh can have a diameter of 50 to 200 pm.

[0058] In an embodiment, the present disclosure provides an electromagnetic interference (EMI) shielding net or cloth coated with metal plating solution for use in residential or commercial space comprising a net or cloth coated with the EMI shielding material.

[0059] In an embodiment of the present invention, the mesh is made of a material selected from but not limited to fiberglass mesh, polyester mesh, polymeric material-based mesh, metal wires, carbon fibers, graphite fibers, inherently-conductive polymer fibers (polyester, polyamide, nylon, and polyimide monofilaments or yams), or a mesh made of any metal material (For example, copper, nickel, silver, aluminum, bronze, steel, tin, stainless steel (SS), iron, or an alloy or combination thereof), or a combination thereof.

[0060] In an embodiment of the present invention, the mesh is a net that are used to preclude insects from entering a specific area of the residential or commercial space. For example, mosquito nets, door nets, window nets, and the like.

[0061] In an embodiment of the present invention, the cloth or the fabric is made of a material selected from but not limited to cotton, wool, silk, cellulose, polyester, polyamide, nylon, polyimide, or a combination thereof.

[0062] In an embodiment of the present invention, the metals for plating solution to afford EMI shielding material are selected from but not limited to nickel, silver, palladium, lead, or a combination thereof.

[0063] In an embodiment, the mesh made of a material selected from fiberglass mesh, polymeric material-based mesh, metal wires, carbon fibers, graphite fibers, or any of combination thereof. In an embodiment, the mesh made of a material selected from fiberglass mesh, polymeric material-based mesh, carbon fibers, graphite fibers, or any of combination thereof, is aliphatic in nature and does not comprise 71 electrons.

[0064] In another embodiment, the present invention provides a method of coating the mesh with metal plating solution to afford the EMI shielding material comprising the steps of:

[0065] (a) providing a mesh;

[0066] (b) anchoring Ni2+on the fibers or wires of the mesh;

[0067] (c) immersing the Ni2+-anchored mesh in NaBFU, which reduces the Ni2+into Ni nanoparticles to obtain Ni nanoparticle-coated mesh; and

[0068] (d) immersing the Ni nanoparticle-coated mesh in Ni plating solution to obtain the Ni film covered mesh.

[0069] In another embodiment, the present invention provides a method of coating the cloth with metal plating solution to afford the EMI shielding material comprising the steps of:

[0070] (a) providing a cloth;

[0071] (b) anchoring Ni2+on the fibers of the cloth by immersing the same in NiSo4 solution;

[0072] (c) immersing the Ni2+-anchored mesh in NaBFU, which reduces the Ni2+into Ni nanoparticles to obtain Ni nanoparticle-coated mesh; and (d) immersing the Ni nanoparticle-coated mesh in Ni plating solution to obtain the Ni film- covered cloth.

[0073] In an embodiment of the present invention, the SS mesh probably contains ~8% Ni, and the same auto-catalyzed the reduction of Ni2+and deposited Ni film on the SS net. This nickel- modified net is efficient in shielding electromagnetic radiation

[0074] In another embodiment, the present invention provides a method of coating the SS mesh with metal plating solution to afford the EMI shielding material comprising the steps of:

[0075] (a) providing a mesh;

[0076] (b) immersing the Ni nanoparticle-coated mesh in Ni plating solution to obtain the Ni film- covered mesh.

[0077] In an embodiment of the present invention, the nickel plating solution when used to generate Ni-based EMI shielding material comprises nickel sulphate, ammonium chloride, sodium hypophosphite, sodium citrate, Ammonium hydroxide q.s. to adjust the pH of the nickel plating solution to 8-9. In some embodiments, the temperature of the nickel plating solution is 60 °C. In an embodiment of the present invention, the nickel plating solution comprises 1-5% w / v of nickel sulphate, 1-10% w / v of ammonium chloride, 1-5% w / v of sodium hypophosphite, 1- 10% w / v of sodium citrate, Ammonium hydroxide q.s. to adjust the pH of the nickel plating solution to 8-9. In some embodiments, the temperature of the nickel plating solution is 60 °C. In an embodiment of the present invention, the nickel plating solution comprises 3% w / v of nickel sulphate, 4.5% w / v of ammonium chloride, 3% w / v of sodium hypophosphite, 4.5% w / v of sodium citrate, Ammonium hydroxide q.s. to adjust the pH of the nickel plating solution to 8-9. In some embodiments, the temperature of the palladium plating solution is 60 °C. In an embodiment of the present invention, the palladium plating solution when used to generate palladium-based EMI shielding material comprises Palladium chloride, ammonium chloride, sodium hypophosphite, HC1, Ammonium hydroxide q.s. to adjust the pH of the palladium plating solution to 8-9. In some embodiments, the temperature of the palladium plating solution is 60 °C.

[0078] In an embodiment of the present invention, the palladium plating solution comprises 0.05- 0.5% w / v of Palladium chloride dissolved in 10-20% v / v of HC1 (based on total plating solution volume), 40-80% w / v of ammonium chloride, 1-4% w / v of sodium hypophosphite, 5- 11% w / v of HC1, Ammonium hydroxide 0.5 to 5 ml to adjust the pH of the palladium plating solution to 8-9. In some embodiments, the temperature of the palladium plating solution is 60 OC' In an embodiment of the present invention, the palladium plating solution comprises 0.01- 09% w / v of Palladium chloride, 30-80% w / v of ammonium chloride, 2.4% w / v of sodium hypophosphite, 5-11% w / v of HC1, Ammonium hydroxide 5-10 ml to adjust the pH of the palladium plating solution to 8-9. In some embodiments, the temperature of the palladium plating solution is 60 °C.

[0079] In an embodiment of the present invention, the silver plating solution when used to generate silver-based EMI shielding material comprises silver nitrate, ammonium chloride, cobalt chloride, Ammonium hydroxide q.s. to adjust the pH of the silver plating solution to 10-11. In some embodiments, the temperature of the silver plating solution is 30 °C.

[0080] In an embodiment of the present invention, the silver plating solution comprises 0.1-0.3% w / v of silver nitrate, 1-1.5% w / v of ammonium chloride, 0.5-0.6% w / v of cobalt chloride, Ammonium hydroxide q.s. to adjust the pH of the palladium plating solution to 10.8. In some embodiments, the temperature of the silver plating solution is 30 °C.

[0081] In an embodiment of the present invention, the silver plating solution comprises 0.202% w / v of silver nitrate, 1.068% w / v of ammonium chloride, 0.538% w / v of cobalt chloride, Ammonium hydroxide q.s. to adjust the pH of the palladium plating solution to 10.8. In some embodiments, the temperature of the silver plating solution is 70 °C.

[0082] In an embodiment of the present invention, the lead plating solution when used to generate lead-based EMI shielding material comprises lead acetate, thiourea, and EDTA. In some embodiments, the temperature of the lead plating solution is 70 °C.

[0083] In an embodiment of the present invention, the lead plating solution comprises 1-3% w / v of lead acetate, 0.1-0.5% w / v of thiourea, and 0.01-0.03% w / v of EDTA. In some embodiments, the temperature of the lead plating solution is 70 °C.

[0084] In an embodiment of the present invention, the lead plating solution comprises 2% w / v of lead acetate, 0.5% w / v of thiourea, and 0.02% w / v of EDTA. In some embodiments, the temperature of the lead plating solution is 70 °C.

[0085] In some embodiments of the present invention, the thickness of the EMI shielding material coated onto the mesh ranges in the nanometer scale. In some embodiments, the thickness may be at least about lOnm - lOOnm. The thickness can range from any of the minimum values described above to any of the maximum values described above, for example from 10 nm to 100 nm. The thickness of the film on cotton can range from 10 nm 500 nm.

[0086] Conducting substrates are essential for EMI shielding. However, all conducting substrates can shield electromagnetic radiation. Certain type of objects is difficult and inconvenient to use. For example, stainless steel sheet is effective in shielding electromagnetic radiation, however they are inconvenient to use. The inventors have used nickel as EMI shielding material. Usually, nickel is coated via sensitization of substrate using Palladium, which is expensive. On Palladium, nickel nanoparticles form and they autocatalyze nickel deposition. Therefore, the real formation of film starts with the nanoparticles of the metal that eventually form the film. With this hypothesis, the inventors have anchored Ni2+on cotton cloth. The Ni2+anchors on hydroxyl groups. Then the cotton cloth was immersed in NaBFU, which reduced the Ni2+to Nickel nanoparticles. Then the nickel nanoparticles modified substrate was immersed into Nickel plating bath (Figure la) to obtain nickel film covered cotton cloth. The same technique can be used to coat metals such as Pd (Figure lb), Ag (Figure 1c) and Pb (Figure Id). The nickel-coated cloth showed-60 dB EMI shielding (Figure 2) compared to 0 dB showed by uncoated cloth. The measurements were carried out in AGIEENT PNA N522a network analyzer.

[0087] Table 1 depicts the of various plating solutions:

[0088] EXAMPLES The following examples, which include preferred embodiments, will serve to illustrate the practice of this invention, it being understood that the particulars shown are by way of example and for purpose of illustrative discussion of preferred embodiments of the invention.

[0089] Example 1: General method of coating the EMI shielding material:

[0090] The method involved providing a cloth or a mesh, which was then optionally anchored with the suitable EMI shielding metal (metal = Ni, Pd, Ag, Pb, etc.). In case of cotton cloth, the substrate was immersed in NiSCU solution. Subsequently, the sample was treated with NaBPU to obtain Nickel nanoparticle coated substrates. In the final step, the nickel nanoparticle decorated substrate was immersed in nickel plating bath to obtain nickel film coated substrates. In the case of SS mesh the method could be done devoid of the Ni2+anchoring step as the SS already contains Ni in small amounts. The metal plating solution is maintained at pH in the range of 8-11 and temperature in the range of 30-70°C of plating solution to obtain EMI shielding plating solution coated material.

[0091] Example la): when metal plating solution is of Nickel metal as provided below for 1 Litre solution:

[0092] Mixing Nickel sulphate (30 gm), Ammonium Chloride (45 gm), Sodium hypophosphite (30 gm) and sodium citrate (45 gm) at a temperature in the range of 50-70°C and maintaining the pH in the range of 8-9 with Ammonium hydroxide.

[0093] Example lb): when metal plating solution is of Palladium metal as provided below for 50 ml solution:

[0094] Mixing Palladium chloride (27 mg), Hydrochloric acid (50 ml), Ammonium chloride (3 gm) Sodium Hypophosphite (1.2 gm) at a temperature in the range of 50-70°C and maintaining the pH in the range of 8-9 with Ammonium hydroxide.

[0095] Example 1c): when metal plating solution is of Silver metal as provided below for 50 ml solution:

[0096] Mixing Silver nitrate (101 mg), Cobalt chloride (269 mg), Ammonium chloride (534 gm) Sodium Hypophosphite (1.2 gm) at a temperature in the range of 25-35°C and maintaining the pH in the range of 10-11 with Ammonium hydroxide.

[0097] Example Id): when metal plating solution is of Lead metal as provided below for 50 ml solution:

[0098] Mixing Lead acetate (1 g), EDTA (10 mg), Thiourea (250 gm) at a temperature in the range of 50-70°C.

[0099] Example 2: Nickel-coated EMI shielding SS Mesh As mentioned earlier, the metal in its neutral state can autocatalyze deposition of metals films. Therefore, the inventors envisioned the presence of 1-8% nickel in stainless steel to act as seed to initiate reduction of nickel to nickel film. Indeed, the inventors were able to coat two different stainless steel substrates by simply immersing them in nickel plating bath. The nickel-modified SS substrates showed impressive efficiency compared to uncoated SS (Figure 2). The SEM images of nickel-modified and nickel-unmodified SS are shown in Figure 3. Their elemental mapping details are shown in Figure 3. The unmodified and nickel modified SS with small spacing between the fibers along with their elemental mapping data are shown in Figure 4. The morphology of nickel modified and unmodified stainless steel with large space and their elemental mapping data are shown in Figure 5.

[0100] After electroless deposition of nickel onto SS, a 1 inch x 1 inch of Ni coated SS was cut, and used to measure the absorption and reflection quantities. From that total shielding is computed. The EMI shielding of SS coated material with said nickel layer is around 80-85 dB (refer, Figure 2).

[0101] ADVANTAGES AND APPLICATIONS OF THE PRESENT DISCLOSURE:

[0102] • The present disclosure provides an EMI shield coating method on cotton cloth and SS mesh that are flexible and inexpensive.

[0103] • EMI shield coating method on cotton cloth and SS mesh cover various surfaces easily.

[0104] • EMI shield coating method on cotton cloth and SS mesh can also be intertwined in comforters. This is not possible with other substrates.

Claims

We Claim:

1. An electromagnetic interference shielding material comprising a substrate coated with a metal coating layer or film, wherein the metal coating layer or film is selected from the group consisting of nickel, silver, palladium, and lead, or a combination thereof, wherein the substrate is selected from mesh, cloth, fabric, web, mat, and screen. wherein the substrate does not comprise TI electrons.

2. The electromagnetic interference shielding material as claimed in claim 1, wherein the mesh is selected from the group consisting of fiberglass mesh, polyester mesh, polymeric material-based mesh, metal wires, carbon fibers, graphite fibers, inherently-conduc- tive polymer fiber, and a metal or metal alloy, or any of combination thereof.

3. The electromagnetic interference shielding material as claimed in claim 2, wherein the metal wire screen of the mesh is having a diameter in the range of 50 to 200 pm.

4. The electromagnetic interference shielding material as claimed in claim 2, wherein the in- herently-conductive polymer fiber is selected from polyester, polyamide, nylon, and polyimide monofilaments and yarns and wherein the metal or metal alloy is selected from copper, nickel, silver, aluminum, bronze, steel, tin, stainless steel (SS), and iron, or any of combination thereof.

5. The electromagnetic interference shielding material as claimed in claim 1, wherein the cloth or the fabric is made of a material selected from cotton, wool, silk, cellulose, polyester, polyamide, nylon, and polyimide, or any of combination thereof.

6. The electromagnetic interference shielding material as claimed in claim 1, wherein the metal coating layer or film onto the substrate is having a thickness in the range of 10 to 500 nm.

7. A process of preparation of the electromagnetic interference shielding material as claimed in claim 1, comprising the steps of: a) providing a substrate;b) optionally treating and immersing the substrate of step (a) with a metal solution to obtain a sample; c) treating the sample of step b) with a reducing agent to reduce metal contained in the sample to obtain a metal nanoparticle coated or anchored substrate material; d) immersing the substrate of step a) or the metal nanoparticle coated or anchored substrate material of step c) in a metal plating solution bath having the pH in the range of 8-11 wherein the metal plating solution comprising a metal selected from nickel, silver, palladium, and lead, or a combination thereof followed by heating at a temperature in the range of 30-70°C to obtain the electromagnetic interference shielding material.

8. The process as claimed in claim 7, wherein when the metal plating solution is based on nickel metal, then the metal plating solution comprises nickel sulfate or nickel chloride, ammonium chloride, sodium hypophosphite, sodium citrate, and ammonium hydroxide; when the metal plating solution is based on palladium metal, then the metal plating solution comprises palladium chloride, ammonium chloride, sodium hypophosphite, hydrochloric acid, and ammonium hydroxide; when the metal plating solution is based on silver metal, then the metal plating solution comprises silver nitrate or silver chloride, ammonium chloride, cobalt chloride, and ammonium hydroxide; and when the metal plating solution is based on lead metal, then the metal plating solution comprises lead acetate or lead chloride, thiourea, and ethylene diamine tetraacetic acid (EDTA).

9. The process as claimed in claim 7, wherein pH of the in the range of metal plating solution bath is in the range of 8-11.

10. The process as claimed in claim 7, wherein the metal solution of step b) comprises a metal selected from nickel, silver, palladium, and lead, or a combination thereof; and the reducing agent is selected from sodium borohydride, and hydrazine hydrate.

11. The process as claimed in claim 7, whereinwhen the metal plating solution is based on nickel metal, then the metal plating solution comprises 1-5% w / v of nickel sulphate or nickel chloride, 1-10% w / v of ammonium chloride, 1-5% w / v of sodium hypophosphite, and 1-10% w / v of sodium citrate; when the metal plating solution is based on palladium metal, then the metal plating solution comprises 0.05-0.5% w / v of palladium chloride dissolved in 10-20% v / v of hydrochloric acid, 40-80% w / v of ammonium chloride, 1-4% w / v of sodium hypophosphite, 5- 11% w / v of hydrochloric acid, and 0.5 to 5 ml of ammonium hydroxide; when the metal plating solution is based on palladium metal, then the metal plating solution comprises 0.01-09% w / v of palladium chloride, 30-80% w / v of ammonium chloride, 2.4% w / v of sodium hypophosphite, 5-11% w / v of hydrochloric acid, and 5-10 ml of ammonium hydroxide; when the metal plating solution is based on silver metal, then the metal plating solution comprises 0.1-0.3% w / v of silver nitrate or silver chloride, 1-1.5% w / v of ammonium chloride, and 0.5-0.6% w / v of cobalt chloride; when the metal plating solution is based on silver metal, then the metal plating solution comprises 1-3% w / v of lead acetate, 0.1-0.5% w / v of thiourea, and 0.01-0.03% w / v of EDTA.

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