47results about How to "Small dielectric coefficient" patented technology

The invention discloses a VDMOS transistor and a preparation method thereof and belongs to the field of semiconductors. The VDMOS transistor comprises a first conduction type substrate, a first conduction type epitaxial layer, a second conduction type injection region, a first conduction type highly doped source region and a grid structure, the second conduction type injection region and the first conduction type highly doped source region are arranged in the epitaxial layer, and the grid structure comprises a grid insulating layer, a semi-insulating polycrystalline silicon layer, a silicon oxynitride layer and a polycrystalline silicon layer. The grid insulating layer is arranged above a drift region of the epitaxial layer, the semi-insulating polycrystalline silicon layer is arranged above the grid insulating layer, the silicon oxynitride layer is arranged above a channel region, and the polycrystalline silicon layer is covered on the semi-insulating polycrystalline silicon layer and the silicon oxynitride layer. A heat nitriding silicon oxynitride layer is introduced into the preparation method, a traditional silica layer which is used as a gate medium layer on a channel is replaced, and the semi-insulating polycrystalline silicon layer is added on an oxide layer which is arranged above the drift region of the epitaxial layer. The VDMOS transistor and the preparation method thereof can obviously reduce grid-drain capacitance and achieve overcoming the defects that insulating performance of the grid insulating layer is poor, current leaking of a grid electrode is increased, and degeneration of the VDMOS performance is unreliable.

The invention discloses a positive-negative-mixed liquid crystal composition. The positive-negative-mixed liquid crystal composition is characterized by comprising a component A composed of at least one kind of negative compounds shown in the first general formula (please see the specification for the first general formula) and a component B composed of one or more kinds of positive compounds shown in the second general formula (please see the specification for the second general formula). The liquid crystal composition has the advantages of being positively dielectric, high in charge retention rate, low in rotary viscosity, short in response time and particularly high in transmittance; the positive-negative-mixed liquid crystal composition is suitable for manufacturing a high-transmittance and rapid-responding TFT-LCD.

The invention relates to a low dielectric constant polyhedral oligomeric silsesquioxane (POSS)/ epoxy resin hybrid material and a preparation method. Epoxy resin and eight epoxy group polyhedral oligomeric silsesquioxane (G-POSS) are evenly mixed in a 80 DEG C breaker according to a certain proportion, an equivalent amount of curing agent triethylene tetramine (TETA) (an amino group in the TETA and an epoxy group in the G-POSS, epoxy resin (EP) are measured according to a 1:1 molar rate) is added and fully stirred, after vacuum defoamation is conducted for 20-30 minutes, the mixture is slowly poured into a preheating mold, conducted solidification in a stove 50 DEG C/ 2 hours, 70 DEG C/ 3 hours and 80DEG C/ 1 hour, cooled to room temperature along with the stove and processed for 4-6 hours after demolding. The low dielectric constant POSS/ epoxy resin hybrid material is small in average grain size and excellent in transparent performance, mechanical property and dielectric property.

The invention relates to polyimide prepared from a trifluoromethyl-substituted aromatic diamine monomer containing a cyclohexane structure and a preparation method thereof. The molecular structural formula of polyimide is shown as the specification. The preparation method comprises the following steps: dissolving a trifluoromethyl-substituted aromatic diamine monomer containing the cyclohexane structure and an aromatic dianhydride monomer in an organic solvent in a molar ratio of 1:1 under the protection of nitrogen, adding isoquinoline to be used as the catalyst, performing a condensation reaction at 90-120 DEG C for 2-6 hours, performing an imidization reaction at 190-210 DEG C for 10-24 hours, performing a one-step polymerization reaction, pouring the reaction product in methanol or ethanol, collecting the separated precipitate, and drying to obtain fibrous polyimide. The method modifies the one-step preparation method of polyimide; and the prepared polyimide can be used to solve the defects of the traditional polyimide film on dissolubility, optical transparency and the like, and correct the problems such as high cost required by the manufacturing process and poor electric properties.

The invention provides a silica microparticle, a composition forming a polyimide aerogel, the polyimide aerogel and a manufacturing method thereof, and a composite material. The silica microparticle containing an amino group is prepared by subjecting alkoxy silane as shown in a formula (I) and alkoxy silane as shown in a formula (II) to hydrolytic condensation in the presence of a catalyst, wherein the formula (I) is Si(OR<1>)<4>, and the formula (II) is (NH<2>-Y)<m>-Si(OR<2>)<4-m>; in the formula (I), R<1> is an alkyl group with a carbon number of 1 to 10; and in the formula (II), Y is an alkyl group with a carbon number of 1 to 10 or an alkyl group with a carbon number of 2 to 10, R<2> is an alkyl group with a carbon number of 1 to 10, and m is an integer in a range of 1 to 3. According to the invention, the polyimide aerogel has the characteristics of high porosity, good thermal insulation properties, good flexural strength, flame resistance, resistance to UV light and chemicals, low dielectric coefficient and the like, does not need low-surface-energy solvents like hexane and pentane and a carbon dioxide supercutical fluid in the process of preparation, and is applicable to the composite material.

The invention provides a preparation method of a binary gradiently doped barium strontium titanate (BST) film, aiming at the technical problem that the comprehensive dielectric property of the BST film is difficult to increase owning to the ferroelectric phase or paraelectric phase single-phase structure caused by the narrow Curie temperature (Tc) range of the conventional BST film, and belonging to the technical field of functional materials. By controlling the molar ratio of Ba and Sr to Ti, the doping element, the concentration, the gradient, the direction and the film design and the preheating treatment and the film thickness (or layer number), the binary gradiently doped BST film with a wider Tc range, a ferroelectric phase and paraelectric phase composite structure and excellent comprehensive performance can be prepared, wherein the dielectric constant is less than 240, the tuning rate is more than 25%, the dielectric loss is less than 0.63% and the permittivity-temperature coefficient is less than 0.0024/K. The method is convenient, fast, cheap and efficient; and the prepared binary gradiently doped BST film can be used in microwave tuning elements.

The invention belongs to the field of lithium ion batteries, and discloses a non-aqueous electrolyte for a lithium ion battery with a ternary positive electrode material and a negative silicon-oxygen-carbon composite negative electrode material, which comprises a non-aqueous organic solvent, an electrolyte lithium salt and an electrolyte additive; the non-aqueous organic solvent comprises ethylene carbonate and methyl ethyl carbonate; and the electrolyte additives comprise vinylene carbonate, fluoroethylene carbonate, 1, 3-propane sultone, vinylethylene carbonate and lithium difluorophosphate. The non-aqueous electrolyte contains cyclic carbonate, a negative electrode film-forming agent, a positive electrode film-forming agent and three lithium salts. The lithium ion non-aqueous electrolyte can be applied to improvement of high-temperature and normal-temperature cycle performance.

The invention provides a radio frequency electronic component testing device which comprises an electrical tester, an antenna tester and a testing chamber, wherein the testing chamber is provided with a cover body with a first anti-interference component, the first anti-interference component is made of shielding-proof materials and has a low dielectric coefficient so that wireless signals can pass through, the cover body closes a first bearing tool to form a testing space, and the testing space is used for accommodating an electrical tester with a radio frequency electronic component; the testing chamber is located between the electrical tester and the antenna tester, so that the radio frequency electronic component can execute electrical testing operation in the electrical tester in the testing chamber, and can also execute wireless signal testing operation with the external antenna tester through the first anti-interference component in the testing chamber, thereby improving the testing quality. The invention further provides testing equipment applying the radio frequency electronic component testing device. The testing equipment comprises a machine table, a feeding device, a material receiving device, a radio frequency electronic component testing device, a conveying device, and a central control device.

The invention provides a preparation method of a polyimide flexible copper-clad plate. The method comprises the following steps: adding polyimide and a heat-conducting filler into dimethylformamide, and stirring to uniformly mix so as to obtain a polyimide glue solution; selecting rolled copper foil, and coating the rough surface of one piece of copper foil with the polyimide glue solution under the protection of inert gas; carrying out imidization in a nitrogen protection oven; covering the polyimide glue solution with another copper foil with the same size to obtain a semi-finished product,and heating and laminating the semi-finished product; and putting the semi-finished product glue-free copper-clad plate into a muffle furnace, and treating under the protection of heating inert gas toobtain the polyimide flexible copper-clad plate. The two-layer flexible copper-clad plate provided by the invention is small in size change and stable, the formed polyimide layer and the copper foilare good in cohesiveness, and the polyimide layer is low in moisture absorption rate, low in dielectric coefficient and excellent in performance.

The invention relates to a plane antenna which comprises a base plate, a feed line, a first radiating unit, a second radiating unit and a grounding unit, wherein the base plate is provided with an upper surface and a lower surface in parallel; the feed line is arranged on the upper surface; and the grounding unit is arranged on the lower surface and used for grounding. The plane antenna is characterized in that the feed line is divided into a long first feed section and a short second feed section by a feed point for feeding a signal, and the first feed section is longer than the second feed section by a half wavelength of the operation frequency of the plane antenna; and the first radiating unit and the second radiating unit are respectively two radiating metal sheets adjacent to the first feed section and the second feed section.

The invention discloses a surface modification process for a low-dielectric material. According to the surface modification process, a silicon dioxide wet gel thin film obtained by using a spin coating method is soaked in a modification solution for surface modification, and then is subjected to thermal treatment in an atmospheric environment, so that the silicon dioxide thin film material with a low dielectric constant is prepared. A method for reducing the dielectric coefficient of the material through using two simple and convenient techniques of soaking with a solvent and performing the thermal treatment is used in the process, so that the porosity of the material still maintains at a relatively low level, and the mechanical strength can keep a relatively high level.

The invention relates to an air coaxial center-fed antenna which comprises an outer conductor and an inner conductor, wherein the inner conductor is coaxially arranged in the outer conductor in a penetrating manner; one end of the inner conductor is connected with an antenna feed port formed at one end of the outer conductor; the outer conductor is hollow; and the other end of the inner conductor is connected with a tightener arranged at the other end of the outer conductor. The inner conductor is coaxially arranged in the hollow outer conductor in a penetrating manner by utilizing the characteristics of low air transmission loss and dielectric coefficient, no insulating material is filled in the outer conductor, the inner conductor and the outer conductor are tightened by the tightener to be coaxial, and the diameter of the inner conductor can be increased, so that the transmission loss is reduced, and the efficiency of the antenna is improved.

The invention provides a preparation method of a polyimide flexible copper-clad plate. The method comprises the following steps: adding polyimide and a heat-conducting filler into dimethylformamide, and stirring to uniformly mix so as to obtain a polyimide glue solution; selecting rolled copper foil, and coating the rough surface of one piece of copper foil with the polyimide glue solution under the protection of inert gas; carrying out imidization in a nitrogen protection oven; covering the polyimide glue solution with another copper foil with the same size to obtain a semi-finished product,and heating and laminating the semi-finished product; and putting the semi-finished product glue-free copper-clad plate into a muffle furnace, and treating under the protection of heating inert gas toobtain the polyimide flexible copper-clad plate. The two-layer flexible copper-clad plate provided by the invention is small in size change and stable, the formed polyimide layer and the copper foilare good in cohesiveness, and the polyimide layer is low in moisture absorption rate, low in dielectric coefficient and excellent in performance.

The invention discloses a ceramic co-sinter co-mode filter to overcome the defect of laminated or winding filter. Wherein, selecting proper materials of different electrical property according to different demand of parts of element, adjusting proper operation by material powder character to integrate together, then completing the element main body with special sintering curve and co-sinter method, finally, obtaining the objective filter.