CN113338050A

CN113338050A - High-temperature-resistant metallized fiber cloth and conductive silica gel composite material, preparation method thereof and application thereof in SMT (surface mounting technology)

Info

Publication number: CN113338050A
Application number: CN202110632151.9A
Authority: CN
Inventors: 胡友根; 何金名; 林志强; 孙蓉
Original assignee: Shenzhen Institute of Advanced Electronic Materials
Current assignee: Shenzhen Institute of Advanced Electronic Materials
Priority date: 2021-06-07
Filing date: 2021-06-07
Publication date: 2021-09-03

Abstract

The invention relates to a high-temperature-resistant metallized fiber cloth and conductive silica gel composite material, a preparation method thereof and an application in SMT. The composite material is prepared from a high-temperature resistant metallized fiber cloth substrate and conductive silica gel; the high-temperature-resistant metallized fiber cloth is high-temperature-resistant fiber cloth plated with two layers of metal; the conductive silica gel is organic silica gel containing conductive filler; the composite material is prepared by coating conductive silica gel on high-temperature-resistant metallized fiber cloth, and then heating and curing to obtain the composite flaky material of the high-temperature-resistant metallized fiber cloth and the conductive silica gel. The composite material has smaller size and can meet the smaller size requirement of the SMT patch material. The coating structure of the composite material can avoid electrochemical corrosion, the organic silica gel substrate can meet the use requirement of an FIP dispensing process, and the composite material has the advantages of simple preparation method, good stretchability and flexibility.

Description

High-temperature-resistant metallized fiber cloth and conductive silica gel composite material, preparation method thereof and application thereof in SMT (surface mounting technology)

Technical Field

The invention relates to a micro EMI (electromagnetic shielding) material of high-temperature-resistant metallized fiber cloth composite conductive silica gel mainly used for SMT (surface mount technology) and a preparation method thereof.

Background

Surface Mounted Technology (SMT) is one of the most popular techniques and processes in the electronics assembly industry. The Surface Mount Device (SMD) is Mounted on the Surface of a Printed Circuit Board (PCB) or other substrate, and is soldered and assembled by reflow soldering or dip soldering. The SMT pad is a ground terminal that can be used in surface mount technology, and is one of the surface mount components. In electric and electronic equipment, an available ground terminal is soldered to a PCB to prevent malfunction due to unnecessary electromagnetic waves and prevent EMC measures for reducing noise of an EMI shielding material. The conductive elastic terminal for grounding PCB has the advantages of high-speed surface assembly, proper electrical conductivity, excellent heat resistance and grounding property, excellent durability and reliability, excellent impact absorption characteristic when the electric/electronic machine is impacted by external impact or falling, and buffer effect for protecting internal parts. However, with the miniaturization of electronic and electrical devices and products, the SMT patch device on the PCB printed component is required to be adjusted in a micro-structured manner, and the traditional SMT patch foam is limited to meet the requirements of future development because the production cost is high and the production process conditions are limited so that a smaller miniaturized size cannot be realized, so that the SMT patch EMI material integrating the miniaturization, the high conductivity and the low compression force and the low cost is the development direction of future electronic and electrical products, which is also widely concerned, researched and developed by people.

The traditional SMT foam patch is generally prepared by coating high-elasticity foam with a PI (polyimide) film with a copper-plated tin-plated metal layer on a single surface and using high-viscosity adhesive glue through a coating production process. Patent CN207820462U has prepared a high temperature resistant high elasticity electrically conductive electromagnetic shielding SMT bubble cotton, and it is formed by substrate and the metal plating polyimide film layer of parcel at the substrate surface. The substrate is generally made of high-temperature-resistant low-compression-force silica gel foam and the high-viscosity adhesive is used for coating the substrate and the silica gel foam. However, the current traditional coating process is limited by the height dimension of the product (the minimum height H is 1.5mm), and is limited by the thickness and precision of the raw material of the silica gel foam, so that the requirement of the future micro-thickness specification of the SMT EMI patch material cannot be met.

Meanwhile, in order to replace the traditional common SMT metal elastic sheet and SMT foam paster, the patent CN108424653A also prepares an SMT paster EMI material consisting of conductive rubber, a weldable metal layer and a conductive bonding layer, wherein the conductive rubber is an SMD conductive rubber composition with a hollow structure, the SMD conductive rubber composition can be obtained by mixing the raw materials of the conductive rubber, and then carrying out co-extrusion vulcanization with the metal layer and the bonding layer and then cutting, the prepared composition is subjected to hollow rubber structure design, and the compression force of the conductive rubber composition is further reduced. However, the thickness of the composition is between 1.0mm and 10mm, so that the composition cannot better solve and meet the requirement of the future smaller thickness specification of the SMT EMI patch material.

Disclosure of Invention

In view of the above, in order to overcome the above-mentioned defects and problems, the present invention provides a high temperature resistant metallized fiber cloth composite conductive silica gel micro EMI material with simple structure composition, high conductivity, low compression, excellent electromagnetic shielding performance, and multiple processing process selectivity, and a preparation method thereof. The invention selects high temperature resistant metallized fiber cloth as a substrate, firstly, copper is chemically plated on the surface of the substrate, and then, tin or nickel is electroplated to prepare a substrate material with a double-layer metal layer; simultaneously, a silica gel matrix with high viscosity and low compression rate is selected, the conductive filler is silver-plated filler with high conductivity, and the liquid conductive silica gel is prepared by a series of auxiliaries and processes; coating a layer of adhesion promoter on one surface of a base material, coating liquid silica gel on the surface of a metal base material, controlling the thickness precision of the material through process equipment, and finally preparing an EMI gasket material with smaller thickness and size through high-temperature curing; common EMI gasket materials of anisotropic construction are made by a die-cutting process.

One aspect of the invention provides a composite material of high-temperature-resistant metallized fiber cloth and conductive silica gel, which is prepared from a high-temperature-resistant metallized fiber cloth substrate and conductive silica gel; the high-temperature-resistant metallized fiber cloth is high-temperature-resistant fiber cloth plated with two layers of metal; the conductive silica gel is organic silica gel containing conductive filler; the composite flaky material of the high-temperature-resistant metallized fiber cloth and the conductive silica gel is prepared by coating the conductive silica gel on the high-temperature-resistant metallized fiber cloth and then heating and curing the conductive silica gel.

In a specific embodiment of the invention, the high-temperature-resistant metallized fiber cloth is plated with a metal layer by a chemical method or a physical method.

In a specific embodiment of the invention, the first metal coating is a metal priming coating on the surface of the high-temperature resistant fiber cloth, and the coating metal is selected from one or more of copper plating, aluminum plating, gold plating and silver plating.

In a specific embodiment of the invention, the second metal plating layer is a second layer of metal plating layer plated on the first plating primer plating layer, and the second layer of metal plating layer is one or more selected from aluminum plating, nickel plating, tin plating and chrome plating.

Preferably, the thickness of the first metal plating layer is 0.01mm to 0.10 mm.

Preferably, the thickness of the second metal plating layer is 0.01mm to 0.10 mm.

More preferably, the second metal plating layer of the high-temperature resistant metallized fiber cloth is single-sided or double-sided.

In a specific embodiment of the invention, the high temperature resistant fiber cloth is a fiber cloth capable of resisting more than 500 ℃, and is selected from one or more of carbon fiber cloth, carbon nanotube fiber cloth, aramid fiber cloth, polyimide fiber cloth, polyether ketone fiber cloth, polyether ether ketone fiber cloth, polytetrafluoroethylene fiber cloth, polyether sulfone fiber cloth, glass fiber cloth and silicone resin fiber cloth.

Preferably, the thickness of the high-temperature resistant fiber cloth is 0.10 mm-0.50 mm.

More preferably, the thickness of the refractory fiber cloth is 0.10mm to 0.20mm, such as 0.10mm, 0.15mm, 0.20mm, 0.30mm, 0.40 mm.

In one embodiment of the invention, the conductive silicone gel is made from a vinyl-functional siloxane polymer with a conductive filler and its associated adjuvants.

In a specific embodiment of the invention, the siloxane polymer containing vinyl functional groups accounts for 12-30 wt% of the conductive silica gel; preferably, the mass percentage of the silicone polymer containing vinyl functional groups is between 15% and 25% by weight; for example, 15 wt%, 17 wt%, 21 wt%, 23 wt%, 25 wt%.

Preferably, the vinyl-functional siloxane polymer is selected from one or more of methylvinylsiloxane, dimethyldiphenylvinylpolysiloxane, methylphenylvinylsiloxane, vinyl polydimethylsiloxane.

More preferably, the vinyl functional silicone has a viscosity in the range of 1000mPas to 30000mPas, preferably a viscosity in the range of 8000mPas to 20000mPas, for example 10000mPas, 12000mPas, 14000mPas, 16000mPas, 18000 mPas.

In a specific embodiment of the invention, the conductive filler is one or more of hollow silver glass microsphere conductive powder, silver glass fiber conductive powder, silver-nickel conductive powder, silver-copper conductive powder and gold-nickel conductive powder.

In one embodiment of the invention, the conductive filler particles have a particle size of 20 μm to 40 μm, or a fiber diameter of 10 μm to 20 μm and a length of 50 μm to 200 μm, more preferably 80 μm to 150 μm.

In a specific embodiment of the invention, the conductive filler accounts for 65 wt% to 81.5 wt%, and more preferably 68 wt% to 80 wt% of the conductive silica gel; for example, 65 wt%, 70 wt%, 72 wt%, 75 wt%, 78 wt%, 80 wt%.

In one embodiment of the invention, the relevant auxiliary agents include a viscosity modifier, a cross-linking agent and a catalyst.

In a specific embodiment of the invention, the viscosity regulator is low-viscosity organic silicone oil or mineral olein, preferably, the low-viscosity organic silicone oil or mineral olein is one or more of dimethyl siloxane silicone oil and hydroxyl silicone oil; more preferably, it is selected from the range of viscosity from 0.1mpas to 1.0 mpas.

Preferably, the low-viscosity organic silicone oil accounts for 0-2 wt% of the conductive silica gel; more preferably 0.5 wt% to 1.8 wt%, such as 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1.0 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%.

In one embodiment of the invention, the catalyst is a platinum catalyst with ppm values between 10000 and 30000; more preferably ppm values between 20000-25000.

In a particular embodiment of the invention, the cross-linking agent is a polymer of a hydrogen containing functional group siloxane and a hydroxyl terminated silicone oil with a viscosity in the range of 500mPas to 2000mPas, preferably with a viscosity in the range of 1000mPas to 2000mPas, such as 1200mPas, 1400mPas, 1600mPas, 1800mPas, 2000 mPas.

In one embodiment of the invention, the sum of the components of the conductive silica gel is 100%.

In a specific embodiment of the invention, the thickness of the composite material of the high temperature resistant metallized fiber cloth and the conductive silica gel is 0.50mm to 2.0mm, and more preferably 0.50mm to 1.5 mm.

In another aspect, the present invention provides the composite material of the high temperature resistant metallized fiber cloth and conductive silica gel as an electromagnetic shielding gasket material, preferably an electromagnetic shielding gasket material for a surface-mounted patch.

The invention further provides a preparation method of the composite material of the high-temperature-resistant metallized fiber cloth and the conductive silica gel, which comprises the following steps:

s1) plating a first metal plating layer on the surface of the high-temperature resistant fiber cloth;

s2) plating a second metal plating layer on the surface of the high-temperature resistant fiber cloth plated with the first metal plating layer on the surface obtained in the step S1) to obtain high-temperature resistant metallized fiber cloth;

s3) preparing conductive silica gel: sequentially mixing siloxane polymer containing vinyl functional groups, conductive filler and related auxiliaries to prepare conductive silica gel;

s4) coating the conductive silica gel on the surface of the two layers of plated metal of the high-temperature resistant metallized fiber cloth, and curing to obtain the composite material of the high-temperature resistant metallized fiber cloth and the conductive silica gel.

In one embodiment of the present invention, the preparation method of step S1) plating the first metal layer on the surface of the refractory fiber cloth comprises:

s1-1) roughening the surface of the high-temperature resistant fiber cloth before electroplating;

s1-2) carrying out sensitization treatment on the coarsened high-temperature resistant fiber cloth;

s1-3) carrying out activation treatment on the sensitized high-temperature resistant fiber cloth;

s1-4) plating a first metal plating layer on the surface of the activated high-temperature resistant fiber cloth;

s1-5) cleaning and drying.

In a specific embodiment of the invention, the step S1-1) of roughening the surface of the high-temperature resistant fiber cloth before electroplating is to weigh the electroplating roughening solution, completely soak the high-temperature resistant fiber cloth for 5-10min, and then clean the high-temperature resistant fiber cloth with deionized water.

In a specific embodiment of the invention, the step S1-2) of sensitizing the coarsened high-temperature resistant fiber cloth is to weigh the electroplating sensitizing solution, completely soak the high-temperature resistant fiber cloth for 5-10min at 20-65 ℃, and then clean the cloth with deionized water.

In a specific embodiment of the invention, the step of S1-3) activating the sensitized high-temperature-resistant fiber cloth is to weigh an electroplating activator solution, completely immerse the high-temperature-resistant fiber cloth in the activator solution, immerse the high-temperature-resistant fiber cloth at normal temperature for 5-10min, and then clean the high-temperature-resistant fiber cloth with deionized water.

In a specific embodiment of the invention, S1-4) the activated fiber cloth with the first metal plating layer plated on the surface of the activated high-temperature resistant fiber cloth is immersed into the prepared first metal plating solution, the temperature is kept at 30-45 ℃, the stirring is kept, the generated gas is removed, and the time for plating the first metal plating layer is 30-60 min.

In a specific embodiment of the present invention, the first metal plating solution in S1-4) is any one of a copper plating solution, an aluminum plating solution, a gold plating solution, and a silver plating solution.

In a specific embodiment of the invention, the preparation method of the copper plating solution comprises the following steps of weighing chemical copper plating solution A and solution B, and mixing the chemical copper plating solution A: and B, liquid B: deionized water is prepared according to the proportion of 1:2:3, is mechanically stirred and mixed to form uniform, and the pH value of the plating solution is adjusted to 12.5-13.

In a specific embodiment of the invention, the drying after the cleaning of S1-5) is to soak the high temperature resistant fiber cloth plated with the first metal plating layer in hot water at 80-90 ℃ for 10min, then wash the fiber cloth with deionized water for 3 times, preferably dry the fiber cloth in a vacuum oven at 60 ℃ for 12h, and store the fiber cloth in vacuum after drying to avoid passivation.

In one embodiment of the present invention, the preparation method of the second metal plating layer of step S2) comprises:

s2-1) cleaning the surface of the high-temperature resistant fiber cloth plated with the first metal plating layer;

s2-2) plating a second metal plating layer on the surface of the first metal plating layer;

s2-3) drying.

In one embodiment of the present invention, the cleaning process of step S2-1) is cleaning degreasing.

In one embodiment of the present invention, the step S2-2) of plating the second metal layer on the surface of the first metal layer is to prepare a plating solution for the second metal layer, and add the high temperature resistant fiber cloth plated with the first metal layer to the plating solution for the second metal layer to obtain the high temperature resistant metallized fiber cloth.

Preferably, the temperature of the second metal plating layer is 60-80 ℃ and the time is 10-60min, more preferably 15-40 min.

In a specific embodiment of the invention, the step S2-2) is vacuum drying, and the drying time is 12-24h at the temperature of 60-80 ℃ in a vacuum state.

In one embodiment of the present invention, S3) is a method for preparing a conductive silica gel comprising:

s3-1) conducting pretreatment on the conductive filler;

s3-2) preparing conductive silica gel liquid:

s3-21) premixing the siloxane polymer containing the vinyl functional group and the cross-linking agent;

s3-22) adding the conductive filler into the premixed liquid in several times, and mixing uniformly;

s3-23) adding a catalyst and mixing;

optionally, in the steps S3-21), S3-22) and/or S3-23), a step of adding a viscosity regulator to regulate the viscosity is further included.

In one embodiment of the present invention, vacuum mixing is performed in steps S3-21), S3-22), and/or S3-23).

In one embodiment of the present invention, in step S4), the conductive silica gel is coated on the two-layer metal-plated surface of the high temperature resistant metallized fiber cloth and cured as one-time coating and curing, twice coating and curing or three-time coating and curing.

In one embodiment of the present invention, the coating and curing are performed in two times in step S4), the thickness of the first coating is 0.1 to 0.2mm, and the thickness of the second coating is 0.20 to 1.50 mm.

In a specific embodiment of the invention, the curing condition is 90-150 ℃ and the curing time is 60-90 min.

In a specific embodiment of the invention, the preparation method further comprises the step of preparing the composite material of the high-temperature resistant metallized fiber cloth and the conductive silica gel in various thicknesses and sizes and shapes by a cutting and die cutting method.

Advantageous effects

1. In order to solve the problem of providing an electromagnetic shielding material of smaller size for surface mounting technology, the present invention provides a composite sheet material of a structure completely different from the prior art, which can have a minimum thickness of up to 0.5 mm. The problem of can't realize the surface mounting of less dimension among the prior art is solved.

2. The invention adopts the high-temperature resistant fiber cloth as the substrate, has thin and controllable thickness, can meet the requirement of high temperature during welding, and further realizes automatic SMT (surface mount technology) mounting production and use.

3. The invention carries out metal plating operation on the high-temperature resistant fiber cloth, and the welding with the solder paste in the SMT pasting technology can avoid electrochemical corrosion caused by metal potential difference and improve the use stability.

4. The organic silica gel matrix used in the invention has the characteristic of high viscosity, can be effectively cured and bonded with a circuit substrate at high temperature in the field of electronic packaging, and can simultaneously meet the use of FIP dispensing technology, thereby further improving the application range of the composite sheet material.

5. The invention uses the silver-plated series conductive filler, the conductive particles have low density, are not easy to deposit in organic silica gel, and have higher conductivity, and the prepared conductive silica gel has more uniform mixing, stable performance and good conductivity.

6. The composite sheet material of the high-temperature-resistant metallized fiber cloth and the conductive silica gel, which is prepared by the invention, is combined by adopting the high-temperature-resistant fiber cloth, the metal coating and the organic silica gel, so that the composite sheet material shows good stretchability and flexibility, and can bear large-scale deformation of the gel, such as compression, stretching, bending, folding, winding, twisting and the like.

7. The composite sheet material can realize high-speed surface assembly and has proper electrical conductivity and grounding property; the conductive elastic terminal for grounding PCB has excellent durability and reliability.

8. When the electric/electronic machine is impacted by external impact or falling, the composite sheet material of the invention endows the electronic device with excellent impact absorption characteristic and has the function of protecting internal fittings for buffering.

Drawings

FIG. 1 is a SEM surface micrograph of copper-coated carbon cloth fiber filaments.

FIG. 2 is an SEM surface view of a copper-plated tin-plated carbon cloth fiber cloth.

Fig. 3 is a SEM cross-sectional view of the conductive silica gel.

Fig. 4 is an SEM surface view of conductive silica gel.

Fig. 5 is a SEM cross-sectional view of a micro EMI material of a metallized fiber cloth and conductive silica gel.

Fig. 6 is an example test chart of the performance application of the micro EMI material of the high temperature resistant metallized fiber cloth composite conductive silica gel on the SMT patch material on the PCB.

FIG. 7 is a sample object diagram of a micro EMI material sample of high temperature resistant metallized fiber cloth compounded with conductive silica gel.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention more comprehensible, specific embodiments thereof are described in detail below, but the present invention is not to be construed as being limited to the implementable range thereof.

Example 1: preparation method of metallized fiber cloth substrate composite conductive silica gel material

Electroless copper plating

With an average thickness of about W₀High temperature resistant fiber cloth having an initial Z-axis resistance of 20m Ω, 100 μm, was subjected to electroless copper plating on both surfaces thereof by an electroless plating process, thereby obtaining copper-plated fiber cloth (as shown in fig. 1). The preparation steps of the electroless copper plating are as follows:

s1-1) coarsening: cutting the high-temperature resistant fiber cloth into 50mm multiplied by 50mm in size specification, putting the cut high-temperature resistant fiber cloth into a container, adding the rough electroplating solution into the container until the rough electroplating solution is completely soaked for 5min, and then washing the rough electroplating solution for 2 times by using deionized water;

s1-2) sensitization: weighing a proper amount of electroplating sensitizing solution, completely soaking the fiber cloth for 5min at the temperature of 65 ℃, then washing the fiber cloth for 2 times by deionized water and airing the fiber cloth;

s1-3) activation: taking out the sensitized and dried fiber cloth, completely soaking the fiber cloth in activating agent liquid after passing through clear water for one time, soaking at normal temperature for 5min, and washing with deionized water for 2 times;

preparing chemical copper plating solution: weighing commercially available chemical copper plating solution A and solution B, and mixing the solutions according to the ratio of solution A: and B, liquid B: preparing deionized water according to the proportion of 1:2:3, mechanically stirring and mixing the deionized water and the deionized water uniformly, and adjusting the pH value of the copper plating solution to 12.6;

s1-4) electroless copper plating: immersing the activated fiber cloth into the prepared plating solution, keeping the copper plating temperature of a water bath at 45 ℃, keeping stirring and removing generated gas, wherein the copper plating time is 40 min;

s1-5) washing and drying: soaking the copper-plated fiber cloth in hot water at 80 ℃ for 10 minutes, then washing with deionized water for 3 times, preferably drying in a vacuum oven at 60 ℃ for 12 hours, and storing in vacuum after drying to avoid passivation;

s1-6) detecting: measuring the thickness W of the copper-plated fiber cloth₁The copper plating layer thickness W was found to be 120.5 μm and the Z-axis resistance was 35m Ω₂＝W₁-W₀120.5-100 μm and 20.5 μm, and the resistance change of the Z axis is not large.

Electroless tin plating

Continuously plating a second tin plating layer on the surface of the copper plating layer on the fiber cloth, wherein the preparation steps of the chemical plating are as follows:

s2-1) cleaning and deoiling

Cleaning and drying the fiber cloth copper plating layer by using deionized water;

s2-2) electroless plating

Preparing a tinning solution, adding the copper-plated fiber cloth into the tinning solution, then adding a tinning additive, and reacting completely to obtain a composite metal foil layer plated with other metal layers, wherein the temperature of the tinning solution is 60 ℃, and the tinning time is 15 min.

S2-3) drying for 12h at 80 ℃ in a vacuum state to obtain the metallized fiber cloth substrate plated with copper and tin again.

S2-4) detecting: measuring the thickness W of the fiber cloth after tin plating₁The thickness W of the copper plating layer was found to be 130.5 μm and the Z-axis resistance was 38m Ω₂＝W₁-W₀130.5-120.5 μm and 10 μm, and the resistance change of the Z axis is not large.

Preparation of conductive silica gels

The preparation method comprises the following steps of preparing conductive silica gel by using hollow silver glass microsphere conductive powder with the average particle size of about 40 mu m as a conductive filler and a siloxane polymer containing a vinyl functional group and having the viscosity of 10000mPas as a matrix through a planetary mixer:

s3-1) preparing for early-stage material treatment: weighing 1000g of hollow silver glass microsphere conductive powder, drying in a vacuum oven at 150 ℃ for 3h, and fully cooling for later use;

s3-2) silica gel premixing: 174.375g of organic silica gel is weighed, 62.5g of cross-linking agent and 10g of micromolecular silicone oil are added for vacuum stirring and mixing, the temperature is controlled to be 10-20 ℃, the rotating speed is 500r/min, and the time is 10 min;

s3-3) mixing conductive silica gel: dividing the cooled conductive powder into four equal parts, and sequentially adding 250g of the cooled conductive powder into the premixed silica gel obtained in the step 2), wherein the mixing conditions for each time are as follows: under vacuum state, controlling the temperature at 10-20 deg.C, rotating speed at 500r/min, and time at 5min, wherein proper amount of silicone oil is added for debugging according to fluidity of conductive silica gel during mixing;

adding other auxiliary agents: fully mixing the conductive powder with silica gel, adding 0.625g of platinum catalyst and 12.5g of hydroxyl silicone oil, controlling the temperature at 10-20 ℃ in a vacuum state, controlling the rotating speed at 500r/min for 10min, mixing the final conductive silica gel, performing vacuum packaging, and storing in a low-temperature refrigerator for 8-12 h for later use.

And detecting the performance of the silica gel sheet made of the conductive silica gel.

High-temperature curing: coating the mixed conductive silica gel on a coating machine to form a sheet sample with the thickness of 1.00mm, and curing in a forced air drying oven at the temperature of 130 ℃ for 1 h;

and (3) testing the performance of the sample: the cured sample was cut into a size of L25mm × W25mm, and tested for piezoelectric properties using a mechanical compression-resistance meter to a thickness of 1.00mm, at @ 30% compression gauge, when H is 0.70mm, the material compression force was 60.5psi and the Z-axis resistance was 0.120 Ω.

-material compounding

The prepared metallized fiber cloth substrate and the prepared conductive silica gel are compounded through a coating process, and the method mainly comprises the following steps:

s4-1) debugging equipment: the distance between the debugged equipment scrapers is 0.20mm, the equipment is started for debugging, the metallized fiber cloth substrate is adsorbed on a fixed position in a vacuum manner, and the scrapers are well adjusted;

s4-2) coating conductive silica gel: weighing 30g of conductive silica gel in a scraper, setting the coating rate to be 10mm/s, and performing operation, wherein the coating thickness is 0.205 mm;

s4-3) high-temperature first curing: and (3) putting the metallized fiber cloth coated with the silica gel into a forced air drying oven for curing at the temperature of 130 ℃ for 1h.

S4-4) attaching a layer of substrate low-viscosity film to the bottom surfaces of the metallized fiber cloth and the conductive silica gel material which are cured for the first time, weighing 100g of conductive silica gel, rolling the conductive silica gel on the surface of the first layer of silica gel by a roller press, and adjusting the rolling distance of the roller press to be 1.00mm and the speed to be 10 r/min;

s4-5) high-temperature secondary curing: and (3) putting the metalized fiber cloth with the rolled silica gel into a forced air drying oven for curing at the temperature of 100 ℃ for 1h.

S4-6) testing the performance of the high-temperature resistant metallized fiber cloth substrate composite conductive silica gel material sample: the cured sample was cut into a size of L25mm × W25mm, the total thickness W of the material was measured to be 1.25mm, and the piezoelectric performance was also measured by a mechanical compression-resistance meter, and the measurement data were: under the compression specification size of @ 30%, when H is 0.875mm, the compression force of the high-temperature-resistant metallized fiber cloth substrate composite conductive silica gel material is 65psi, the Z-axis resistance value is 0.075 omega, and the electromagnetic shielding effectiveness of the material is 75dB-80dB when the material is tested in the frequency range of 30MHz-3GHz by adopting a coaxial method.

Example 2: preparation method of metallized fiber cloth substrate composite conductive silica gel material

Electroless copper plating

s1-1) coarsening: cutting high temperature resistant fiber cloth into 50mm × 50mm size, placing into a container, adding into the container

Immersing the electroplating coarsening solution for 5min completely, and then washing the solution with deionized water for 2 times;

s1-2) sensitization: weighing appropriate amount of electroplating sensitization liquid, soaking the fiber cloth for 5min at 65 deg.C, and adding deionized water

Cleaning for 2 times and drying;

s1-5) washing and drying: soaking the copper-plated fiber cloth in hot water at 80 ℃ for 10min, then washing with deionized water for 3 times, preferably drying in a vacuum oven at 60 ℃ for 12h, and storing in vacuum after drying to avoid passivation;

Electroless tin plating

s2-1) cleaning and deoiling

s2-2) electroless plating

Preparing a tinning solution, adding the copper-plated fiber cloth into the tinning solution, then adding a tinning additive, and reacting completely to obtain a composite metal foil layer plated with other metal layers, wherein the temperature of the tinning solution is 60 ℃, and the tinning time is 15 min. And drying for 12 hours at the temperature of 80 ℃ in a vacuum state to obtain the metallized fiber cloth substrate plated with copper and then plated with tin.

S2-3) detecting: measuring the thickness W of the fiber cloth after tin plating₁The thickness W of the copper plating layer was found to be 130.5 μm and the Z-axis resistance was 38m Ω₂＝W₁-W₀130.5-120.5 μm and 10 μm, and the resistance change of the Z axis is not large.

Preparation of conductive silica gels

The preparation method comprises the following steps of preparing conductive silica gel by using silver fiber conductive powder with the average particle size of about 20 mu m and the length of 100 mu m and hollow silver glass microsphere conductive powder with the average particle size of 40 mu m as mixed conductive filler and siloxane silica gel containing vinyl functional groups with the viscosity of 10000mPas as a matrix through a planetary mixer, wherein the preparation steps are as follows:

s3-1) preparing for early-stage material treatment: weighing 500g of hollow silver glass microsphere conductive powder and 500g of silver fiber conductive powder, drying for 3h in a vacuum oven at 150 ℃, and fully cooling for later use;

s3-4) adding other auxiliary agents: fully mixing the conductive powder with silica gel, adding 0.625g of platinum catalyst and 12.5g of hydroxyl silicone oil, controlling the temperature at 10-20 ℃ in a vacuum state, controlling the rotating speed at 500r/min for 10min, mixing the final conductive silica gel, performing vacuum packaging, and storing in a low-temperature refrigerator for 8-12 h for later use.

High-temperature curing: the prepared conductive silica gel is coated on a coating machine to form a sheet sample with the thickness of 1mm in a scraping mode, and the sheet sample is solidified in a forced air drying oven at the temperature of 130 ℃ for 1 hour.

And (3) testing the performance of the sample: the cured samples were cut to a size of L25mm xw 25mm xh 1mm and tested for piezoelectric performance using a mechanical compression-resistance instrument in which: at @ 30% gauge, when H is 0.70mm, the material compression force is 54psi and the Z-axis resistance value is 0.090 Ω.

-material compounding

S4-6) testing the performance of the high-temperature resistant metallized fiber cloth substrate composite conductive silica gel material sample: the cured sample was cut into a size of L25mm × W25mm, the total thickness W of the material was measured to be 1.25mm, and the piezoelectric performance was also measured by a mechanical compression-resistance meter, and the measurement data were: under the compression specification size of @ 30%, when H is 0.875mm, the compression force of the high-temperature-resistant metallized fiber cloth substrate composite conductive silica gel material is 58.2psi, the Z-axis resistance value is 0.085 omega, and the electromagnetic shielding effectiveness of the material is tested to be 80dB-85dB in the frequency range of 30MHz-3GHz by adopting a coaxial method.

Example 3: preparation method of metallized fiber cloth substrate composite conductive silica gel material

Electroless copper plating

s1-6) detecting: measuring the thickness W of the copper-plated fiber cloth₁120.5 μm, Z-axis resistance 35m omega, the thickness W of the copper plating layer₂＝W₁-W₀120.5-100 μm and 20.5 μm, and the resistance change of the Z axis is not large.

Electroless tin plating

s2-1) cleaning and deoiling

s2-2) electroless plating

And drying for 12 hours at the temperature of 80 ℃ in a vacuum state to obtain the metallized fiber cloth substrate plated with copper and then plated with tin.

S2-3) detecting: measuring the thickness W of the fiber cloth after tin plating₁The thickness W of the copper plating layer was found to be 130.5 μm and the Z-axis resistance was 35m Ω₂＝W₁-W₀130.5-120.5 μm and 10 μm, and the resistance change of the Z axis is not large.

Preparation of conductive silica gels

High-temperature curing: the prepared conductive silica gel is coated on a coating machine to form a sheet sample with the thickness of 1.0mm in a scraping mode, and the sheet sample is cured in a forced air drying oven at the temperature of 130 ℃ for 1 hour.

-material compounding

S4-4) attaching a layer of substrate low-viscosity film to the bottom surfaces of the metallized fiber cloth and the conductive silica gel material which are cured for the first time, weighing 100g of conductive silica gel, rolling the conductive silica gel on the surface of the first layer of silica gel by a roller press, and adjusting the rolling distance of the roller press to be 0.35mm and the speed to be 10 r/min;

S4-6) testing the performance of the high-temperature resistant metallized fiber cloth substrate composite conductive silica gel material sample: the cured sample was cut into a size of L25mm × W25mm, the total thickness W of the material was measured to be 0.750mm, and the piezoelectric performance was also measured by a mechanical compression-resistance meter, and the measurement data were: under the compression specification size of @ 30%, when H is 0.525mm, the compression force of the high-temperature-resistant metallized fiber cloth substrate composite conductive silica gel material is 55.2psi, the Z-axis resistance value is 0.065 omega, and the electromagnetic shielding effectiveness of the material is 85dB-90dB when the material is tested in the frequency range of 30MHz-3GHz by adopting a coaxial method.

Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention.

Claims

1. The composite material of the high-temperature resistant metallized fiber cloth and the conductive silica gel is characterized by being prepared from a high-temperature resistant metallized fiber cloth substrate and the conductive silica gel; the high-temperature-resistant metallized fiber cloth is high-temperature-resistant fiber cloth plated with two layers of metal; the conductive silica gel is organic silica gel containing conductive filler; the composite flaky material of the high-temperature-resistant metallized fiber cloth and the conductive silica gel is prepared by coating the conductive silica gel on the high-temperature-resistant metallized fiber cloth and then heating and curing the conductive silica gel.

2. The composite material of claim 1, wherein the first metal coating is a metal priming coating on the surface of the high-temperature resistant fiber cloth, and the coating metal is selected from one or more of copper plating, aluminum plating, gold plating and silver plating;

the second metal coating is a second metal coating plated on the first metal coating, and the second metal coating is one or more of aluminum plating, nickel plating, tin plating and chromium plating;

preferably, the thickness of the first metal plating layer is 0.01mm-0.10 mm;

3. The composite material according to claim 1, wherein the high temperature resistant fiber cloth is a fiber cloth resistant to a temperature of 500 ℃ or higher, and is selected from one or more of carbon fiber cloth, carbon nanotube fiber cloth, aramid fiber cloth, polyimide fiber cloth, polyether ketone fiber cloth, polyether ether ketone fiber cloth, polytetrafluoroethylene fiber cloth, polyether sulfone fiber cloth, glass fiber cloth and silicone resin fiber cloth;

4. The composite material according to claim 1, characterized in that the conductive silica gel is made of a siloxane polymer containing vinyl functional groups with conductive fillers and their related auxiliaries;

preferably, the siloxane polymer containing vinyl functional groups accounts for 12-30 wt% of the conductive silica gel;

preferably, the siloxane polymer containing vinyl functional groups is selected from one or more of methylvinylsiloxane, dimethyldiphenylvinylpolysiloxane, methylphenylvinylsiloxane;

preferably, the conductive filler is one or more of hollow silver glass microsphere conductive powder, silver glass fiber conductive powder, silver-nickel conductive powder, silver-copper conductive powder and gold-nickel conductive powder; more preferably, the conductive filler particles have a particle size of 20 μm to 40 μm, or a fiber diameter of 10 μm to 20 μm;

preferably, the conductive filler accounts for 65 wt% -81.5 wt% of the conductive silica gel.

5. The composite material of claim 4, wherein the associated additives include viscosity modifiers, cross-linking agents, and catalysts;

preferably, the viscosity regulator is low-viscosity organic silicone oil or mineral olein; more preferably, the low-viscosity organic silicone oil accounts for 0-2 wt% of the conductive silica gel;

preferably, the catalyst is a platinum catalyst;

preferably, the cross-linking agent is a polymer of hydrogen-containing functional group siloxane and hydroxyl-terminated silicone oil.

6. Composite material according to claim 1, characterized in that the thickness of the composite material of the high temperature resistant metallized fiber cloth and the conductive silica gel is 0.50mm-2.0mm, preferably 0.50mm-1.5 mm.

7. Use of a composite of high temperature resistant metallized fiber cloth and conductive silicone gel according to any one of claims 1 to 6 as an electromagnetic shielding gasket material, preferably an electromagnetic shielding gasket material for surface mount patches.

8. The method for preparing the composite material of the high-temperature resistant metallized fiber cloth and the conductive silica gel according to any one of claims 1 to 6, characterized by comprising the following steps:

s2) plating a first metal plating layer on the surface obtained in the step S1) and plating a second metal plating layer on the surface of the high-temperature resistant fiber cloth to obtain high-temperature resistant metallized fiber cloth;

s3) preparing a conductive silica gel liquid: sequentially mixing siloxane polymer containing vinyl functional groups, conductive filler and related auxiliaries to prepare conductive silica gel liquid;

9. The method according to claim 8,

step S1) the preparation method for plating the first metal plating layer on the surface of the high-temperature resistant fiber cloth comprises the following steps:

s1-5) cleaning and drying;

step S2) the method for preparing the second metal plating layer includes:

s2-3) drying.

10. The method for preparing the conductive silica gel according to claim 8, wherein S3) is prepared by the following steps:

s3-1) conducting pretreatment on the conductive filler;

s3-2) preparing conductive silica gel liquid:

s3-23) adding a catalyst and mixing;

optionally, in the steps S3-21), S3-22) and/or S3-23), a step of adding a viscosity regulator to regulate the viscosity is further included;

in step S4), coating the conductive silica gel on the surface of the high-temperature-resistant metallized fiber cloth plated with two layers of metal, and curing to be one-time coating and curing, two-time coating and curing or three-time coating and curing;

preferably, the coating is performed and cured in two times in step S4), the first coating having a thickness of 0.1 to 0.2mm and the second coating having a thickness of 0.20 to 1.50 mm.