阅读说明：本技术 可双面蚀刻的且具有高介电常数的柔性薄膜电容材料及其制备方法 (Double-sided-etchable flexible thin-film capacitor material with high dielectric constant and preparation method thereof ) 是由 李峰 刘侠侠 陶玉红 李露 卢星华 袁启斌 于 2019-10-10 设计创作，主要内容包括：本发明公开了一种柔性薄膜电容材料及其制备方法,按照重量百分比计,柔性薄膜电容材料包括25～40wt％丙烯酸树脂、1～5wt％固化剂以及55～75wt％高介电常数填料,其中,丙烯酸树脂由40～60wt％硬单体、35～50wt％软单体以及1～10wt％功能单体的自由基聚合而成,且丙烯酸树脂的Tg值在50℃～80℃之间,功能单体用于提高丙烯酸树脂与高介电常数填料的结合力。本发明通过使用特殊设计的聚合物提高柔性薄膜电容材料的强度和韧性。从而使得制备的柔性薄膜电容材料可以在埋容前进行双面蚀刻,介电材料能够耐受蚀刻时冲洗水压而不会被破坏。解决目前分步双面蚀刻存在工艺效率低,在搬运和卸放料过程中容易产生弯曲折皱等问题。(The invention discloses a flexible film capacitor material and a preparation method thereof, wherein the flexible film capacitor material comprises, by weight, 25-40 wt% of acrylic resin, 1-5 wt% of a curing agent and 55-75 wt% of a high dielectric constant filler, wherein the acrylic resin is prepared by polymerizing 40-60 wt% of a hard monomer, 35-50 wt% of a soft monomer and 1-10 wt% of a functional monomer, the Tg value of the acrylic resin is between 50 ℃ and 80 ℃, and the functional monomer is used for improving the bonding force between the acrylic resin and the high dielectric constant filler. The invention improves the strength and toughness of the flexible film capacitor material by using specially designed polymers. Therefore, the prepared flexible thin film capacitor material can be subjected to double-sided etching before capacitance embedding, and the dielectric material can resist the flushing water pressure during etching without being damaged. The problems that the process efficiency is low, and bending wrinkles are easily generated in the carrying and discharging processes in the prior step double-sided etching are solved.)

1. The flexible film capacitor material is characterized by comprising, by weight, 25-40 wt% of acrylic resin, 1-5 wt% of a curing agent and 55-75 wt% of a high-dielectric-constant filler, wherein the acrylic resin is formed by polymerizing 40-60 wt% of a hard monomer, 35-50 wt% of a soft monomer and 1-10 wt% of a functional monomer, the Tg value of the acrylic resin is between 50 ℃ and 80 ℃, and the functional monomer is used for improving the bonding force between the acrylic resin and the high-dielectric-constant filler.

2. The flexible thin film capacitor material as defined in claim 1, wherein the hard monomer is selected from one or two of methyl methacrylate, styrene, acrylonitrile, iso-glacial methacrylate and iso-glacial acrylate.

3. The flexible thin film capacitor material as defined in claim 1, wherein the soft monomer is selected from one or two of butyl acrylate, butyl methacrylate, ethyl acrylate, methyl acrylate and isooctyl methacrylate.

4. The flexible thin film capacitor material as defined in claim 1, wherein the functional monomer is one of acrylic acid, methacrylic acid, maleic anhydride, acrylamide, hydroxyethyl acrylate, and hydroxyethyl methacrylate.

5. The flexible thin film capacitor material as claimed in claim 1, wherein the curing agent is one of an aziridine curing agent, an isocyanate curing agent and a melamine resin curing agent, and the curing agent performs a curing reaction with the functional monomer groups of the acrylic resin, by which the Tg value of the acrylic resin is increased to 120 ℃ or higher.

6. The flexible thin film capacitor material as claimed in claim 1, wherein the high dielectric filler is selected from one or more of barium sodium titanate, barium titanate, strontium titanate, copper calcium titanate, barium strontium titanate, calcium titanate, barium calcium titanate, lead zirconate titanate, sodium lead titanate and lead titanate, the high dielectric filler has a dielectric constant of 1000 or more, a dielectric loss of 0.05 or less, and a particle size D of the high dielectric filler₅₀The high dielectric filler is preferably spherical powder material of 0.1-1.5 um.

7. A method for preparing the flexible thin film capacitor material as claimed in any one of claims 1 to 6, wherein the method comprises the following steps:

uniformly stirring acrylic resin solution, curing agent and high-dielectric constant filler by using a high-speed dispersion machine, and then grinding the mixture by using a grinding machine until the mixture is D of the high-dielectric constant filler₅₀Forming a filler dispersion liquid with the thickness of 0.1-0.5 um;

coating the filler dispersion liquid on a copper foil substrate;

drying the solvent and then adding a second layer of copper foil base material;

heating and curing to form the flexible film capacitor material which can be etched on both sides and has high dielectric constant.

8. The method for preparing a flexible thin film capacitor material as claimed in claim 7, wherein the solution preparation method of the polypropylene resin comprises the steps of:

adding the solvent and the first part of initiator cumyl peroxide (BPO) into a reaction kettle, and introducing nitrogen to remove air for 5-15 min;

heating to 80-100 ℃, dropwise adding the hard monomer, the soft monomer, the functional monomer and the second part of initiator for 4-8 hours, and carrying out reaction heat release to raise the temperature of the reaction kettle to 120 ℃ or above; and

adding the rest of initiator when the temperature of the reaction kettle begins to decrease, and continuing to react for 3-5 hours to prepare the acrylic resin;

wherein the content of the first part of the initiator is 25-35%, and the content of the second part of the initiator is 35-45%; according to the weight percentage, the initiator accounts for 0.5-1 wt%, the solvent accounts for 60-70 wt%, and the hard monomer, the soft monomer and the functional monomer account for 25-40 wt%.

9. The method for manufacturing a flexible thin film capacitor material as claimed in claim 7, wherein the solvent is one or more of butyl acetate, ethylene glycol butyl ether acetate, toluene, xylene and pentanone.

10. The flexible thin film capacitor material as claimed in any one of claims 1 to 6, applied to a printed wiring board, having a strength of more than 50mPa and a tensile elongation at break of more than 10%.

Technical Field

The invention belongs to the technical field of dielectric materials, and particularly relates to a flexible thin-film capacitor material which can be etched on two sides and has a high dielectric constant and a preparation method thereof.

Background

Flexible dielectric materials with high dielectric constants have wide application in energy storage capacitors, field effect transistor dielectric materials, excitation power supplies and buried capacitor technologies. Although polymers have good flexibility, their dielectric constant is too low to meet application requirements. In order to prepare flexible dielectric materials having a high dielectric constant, much work has been devoted in recent years to the development of polymer-based dielectric composites. The dielectric constant of the polymeric material is increased by filling a conductive material or a dielectric material into the polymer matrix to form a 0-3 type composite material.

Because the dielectric material is thin and filled with a large amount of inorganic materials, the dielectric material has low strength, and if the double-sided etching is directly carried out and the metal film support is lacked, the strength of the dielectric material can not resist the destructive effect of flushing water flow on the dielectric material during flushing after exposure and development. Therefore, the existing capacitor-burying processing technology adopts two etching processes, wherein one surface is etched firstly, and then the single surface is laminated to be etched secondly after the etching is finished. However, this process is inefficient and is prone to bending wrinkles during handling and discharge. Therefore, if the strength of the material can be improved on the premise that the dielectric constant is kept unchanged, the material can adapt to a double-sided etching process, and great significance is brought to the improvement of the process efficiency and the product yield.

Therefore, there is a need to provide a flexible dielectric material with high dielectric constant having high strength.

Disclosure of Invention

The invention aims to provide a flexible thin film capacitor material which has the advantages of high strength and high dielectric constant.

The invention also aims to provide a preparation method of the flexible thin-film capacitor material, and the flexible thin-film capacitor material prepared by the preparation method has the advantages of high strength and high dielectric constant.

In order to achieve the purpose, the invention provides a flexible thin film capacitor material which comprises acrylic resin, a curing agent and a high dielectric constant filler, wherein the acrylic resin is prepared by polymerizing free radicals of a hard monomer, a soft monomer and a functional monomer, the Tg value of the acrylic resin is between 50 and 80 ℃, and the functional monomer is used for improving the bonding force of the acrylic resin and the high dielectric constant filler.

Furthermore, according to the weight percentage, the acrylic resin is 25-40 wt%, the curing agent is 1-5 wt%, and the high dielectric constant filler is 55-75 wt%.

Further, according to the weight percentage, the hard monomer proportion in the acrylic resin is 40-60 wt%, the soft monomer proportion is 35-50 wt%, and the functional monomer proportion is 1-10 wt%.

Further, the hard monomer is one or two selected from methyl methacrylate, styrene, acrylonitrile, iso-glacial methacrylate and iso-glacial acrylate.

Further, the soft monomer is one or two selected from butyl acrylate, butyl methacrylate, ethyl acrylate, methyl acrylate and isooctyl methacrylate.

Further, the functional monomer is one of acrylic acid, methacrylic acid, maleic anhydride, acrylamide, hydroxyethyl acrylate and hydroxyethyl methacrylate.

Further, the curing agent is one of an aziridine curing agent, an isocyanate curing agent and a melamine resin curing agent, the curing agent and the functional monomer groups of the acrylic resin are subjected to a curing reaction, and the Tg value of the acrylic resin is increased to 120 ℃ or higher through the curing reaction.

Further, the high dielectric filler is selected from one or more of barium sodium titanate, barium titanate, strontium titanate, copper calcium titanate, barium strontium titanate, calcium titanate, barium calcium titanate, lead zirconate titanate, sodium lead titanate and lead titanate, the dielectric constant of the high dielectric filler is more than or equal to 1000, and the dielectric loss is less than or equal to 0.05.

Further, the particle diameter D of the high dielectric filler₅₀The high dielectric filler is preferably spherical powder material of 0.1-1.5 um.

The invention also provides a preparation method of the flexible thin film capacitor material, which comprises the following preparation steps: uniformly stirring a solution of acrylic resin, a curing agent and a high-dielectric-constant filler to form a filler dispersion liquid; coating the filler dispersion liquid on a substrate; drying the solvent and then adding a second layer of base material; heating and curing to form the flexible film capacitor material which can be etched on both sides and has high dielectric constant.

Further, the solution preparation method of the polypropylene resin comprises the following steps: adding the solvent and the first part of initiator into the reaction kettle, and introducing nitrogen to remove air for 5-15 min; heating to 80-100 ℃, dropwise adding the hard monomer, the soft monomer, the functional monomer and the second part of initiator for 4-8 hours, and carrying out reaction heat release to raise the temperature of the reaction kettle to 120 ℃ or above; and when the temperature of the reaction kettle begins to drop, adding the rest initiator, and continuing to react to prepare the acrylic resin. The acrylic resin is rich in carboxyl, hydroxyl and amide groups.

Further, the initiator is cumene peroxide (BPO), the content of the first part of the initiator is 25-35%, the content of the second part of the initiator is 35-45%, and the reaction is continued for 3-5 hours after the rest of the initiator is added.

Further, the solvent is one or more of butyl acetate, ethylene glycol butyl ether acetate, toluene, xylene and pentanone.

Further, the initiator accounts for 0.5-1 wt%, the solvent accounts for 60-70 wt%, and the hard monomer, the soft monomer and the functional monomer account for 25-40 wt%.

Further, the acrylic resin solution and the high dielectric constant filler are uniformly stirred by using a high-speed dispersion machine and then ground to D of the high dielectric constant filler by using a grinding machine₅₀＝0.1～0.5um。

Further, the base material is a copper foil.

The flexible thin-film capacitor material is applied to a printed circuit board, the strength of the flexible thin-film capacitor material is more than 50mPa, and the tensile breaking elongation of the flexible thin-film capacitor material is more than 10%.

The strength and toughness of the flexible thin-film capacitor material are improved by using the specially designed polymer, and particularly, the polymerization of the soft and hard monomers improves the strength of the composite material and has relatively high toughness. Meanwhile, the functional monomer is used to improve the binding force of the resin and the ceramic filler, thereby further improving the strength and toughness of the composite material. Therefore, the prepared flexible thin film capacitor material can be subjected to double-sided etching before capacitance embedding, and the dielectric material can resist the flushing water pressure during etching without being damaged. The problems that the process efficiency is low, and bending wrinkles are easily generated in the carrying and discharging processes in the prior step double-sided etching are solved.

Detailed Description

The "ranges" disclosed herein are in the form of lower and upper limits. There may be one or more lower limits, and one or more upper limits, respectively. The given range is defined by the selection of a lower limit and an upper limit. The selected lower and upper limits define the boundaries of the particular range. All ranges that can be defined in this manner are inclusive and combinable, i.e., any lower limit can be combined with any upper limit to form a range. For example, ranges of 60-120 and 80-110 are listed for particular parameters, with the understanding that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present invention, all embodiments and preferred embodiments mentioned herein may be combined with each other to form a new technical solution, if not specifically stated.

In the present invention, all the technical features mentioned herein and preferred features may be combined with each other to form a new technical solution, if not specifically stated.

In the present invention, all the steps mentioned herein may be performed sequentially or randomly, if not specifically stated, but preferably sequentially.