阅读说明：本技术 一种具有自我修复功能的模压电感 (Mould pressing inductance with self-repairing function ) 是由 郭峰 汪贤 黄裕茂 金叶萍 许玉成 于 2019-04-24 设计创作，主要内容包括：本发明提供了一种具有自我修复功能的模压电感。本发明在软磁金属粉末表面设计三层不同性质和功能的绝缘层。内层具有最优的绝缘性、耐热性,中间层是具有热塑性的涂层,外层具有最佳的强度、韧性、耐吸湿性及最厚的薄膜厚度,且最外层作为造粒用粘结剂树脂。然后将该造粒粉末在模具中压制为模压电感行并固化处理。由此方法制备的模压电感在使用过程中(一般在85-165℃之间)具有自我修复内部绝缘层裂纹的功能,从而抑制电感短路甚至烧机等故障,该发明的特殊之处在于利用模压电感使用过程的热能和裂纹等缺陷出现的内部未占用空间将热塑性的树脂熔融体自动填补缺陷处的为占用空间,从而保证模压电感的绝缘特性不明显下降甚至还有所提高。(The invention provides a molded inductor with a self-repairing function. The invention designs three layers of insulating layers with different properties and functions on the surface of the soft magnetic metal powder. The inner layer has the best insulation and heat resistance, the middle layer is a coating layer with thermoplasticity, the outer layer has the best strength, toughness, moisture absorption resistance and the thickest film thickness, and the outermost layer is used as a binder resin for granulation. The granulated powder is then pressed in a mould to form a moulded inductor row and cured. The molded inductor prepared by the method has the function of self-repairing cracks of the internal insulating layer in the use process (generally between 85 and 165 ℃), so that the faults of short circuit of the inductor, even burning and the like are inhibited.)

1. The utility model provides a moulded inductor with self-healing function which characterized in that: (1) the invention adopts soft magnetic metal powder as a base material, then three insulating layers with different properties and functions are formed on the surface of the soft magnetic metal powder, the inner layer completely covers the soft magnetic metal powder and has optimal insulation, heat resistance and thinnest film thickness, the outer layer completely covers the soft magnetic metal powder and has optimal strength, toughness, moisture absorption resistance and thickest film thickness, the middle layer is composed of thermoplastic resin powder which is dispersed and distributed, the layer material is melted and flows at a certain temperature, and the covering process is carried out at plus or minus 50 ℃ of the softening temperature of the thermoplastic resin powder; (2) then pressing the soft magnetic metal powder with the three insulating layers and the coil winding thereof in a mould to form a mould pressing inductor, and carrying out curing treatment to ensure that the binder resin of the outermost insulating layer is completely cured; (3) the molded inductor prepared by the method has the function of self-repairing cracks of the internal insulating layer in the use process, so that the molded inductor is prevented from short circuit, even burning and other faults.

2. The molded inductor with self-repairing function as claimed in claim 1, wherein: the innermost material of the soft magnetic metal powder may be one or more of phosphate, silicate, borate, chromate, permanganate, nitrate, aluminate, etc. the treatment method may be chemical conversion method or physical coating method depending on whether the insulating layer and the surface of the metal powder are chemically reacted, and the thickness of the insulating layer is 60 nm or less.

3. The method of claim 1, wherein the step of improving the surface insulation of the molded inductor comprises the steps of: the thermoplastic resin material can be one or more than one mixture of thermoplastic resin or its resin modified substance with softening temperature between 80-160 ℃, and the thermoplastic resin powder does not react with the adhesive resin used for granulation, further the thermoplastic material is required to have the initial decomposition temperature of more than or equal to 260 ℃, the powder particle size distribution is 0.01-10.00um, and the volume average particle size D50 is 0.2-2.0um, more importantly, the ratio of the volume average particle size D50 of the resin powder to the volume average particle size D50 of the soft magnetic metal powder is less than or equal to 0.20, preferably less than or equal to 0.05, and the weight percentage of the thermoplastic resin powder in the soft magnetic metal powder is 0.5-2.0%.

4. The method of claim 1, wherein the step of improving the surface insulation of the molded inductor comprises the steps of: the main body of the outermost layer insulating layer material can be one or more than one of epoxy resin, phenolic resin, cyanate ester, silicon resin and the like, and is matched with a corresponding curing agent to form a binder system; the binder accounts for 2.5-4.5% of the weight of the soft magnetic metal powder, and corresponding diluent is added in the preparation process of the outermost layer, wherein the diluent accounts for 5-15% of the weight of the binder.

5. The method of claim 1, wherein the step of improving the surface insulation of the molded inductor comprises the steps of: the molded inductor prepared by the method has the function of self-repairing cracks of the internal insulating layer in the use process (generally between 85 and 165 ℃), and the service life is prolonged by more than 50 percent.

Technical Field

The invention relates to a molded inductor with a self-repairing function, and belongs to the field of electronic components.

Background

With the development of modern integrated circuit design and manufacturing process, chip design and manufacturing process, robot automation manufacturing technology, electronic component technology and internet application, intellectualization has become the mainstream technical trend of the information society and even the next generation of industrial technology revolution. At present, various direct current loads (including sensors) with intelligent operation functions rapidly transform the survival states of the traditional industry and human beings, and connect people to people, objects to objects, and people to objects.

These complex connections all rely on the transmission, communication and calculation of information, so that an intelligent terminal arises at the end of the day, and can be the transmission end of information, the receiving end of information and the tool for information communication and calculation. For example, the intelligent terminals all need to adopt chips as a tool for operation, so that a front inductor for providing electric energy for the intelligent terminals is indispensable, and the inductor is widely applied as a main electromagnetic conversion material; in addition, metal powder products are indispensable to smart phones, smart televisions, smart home appliances, tablet computers, notebook computers, various communication terminals, servers, and the like.

In various electronic and power electronic devices, the devices are generally required to have good insulation and EMI (electromagnetic interference) resistance properties while having functionality, so that the devices made of metal powder need to be subjected to surface insulation treatment, and the devices are mainly various patch type molded inductors. The requirement of the conventional application on the granularity of the metal powder is usually between 10 and 100 microns, the powder is usually produced by adopting a water atomization method, an air atomization method or a mechanical ball milling method, and the insulation treatment of the powder can be realized by adopting conventional mechanical mixing and drying. With the popularization and application of electric vehicles, internet of things, cloud servers, intelligent technologies and new semiconductor materials, the stability requirement of devices is higher and higher, and the use conditions of the devices are more and more demanding, so that the thermal stability and the efficiency of related metal powder devices (such as molded inductors) with functionality are required to be higher and higher, for example, the insulation resistance > =100M Ώ/cm during the long-term use of the molded inductors is required by automobile electronics, and therefore, it is a necessary trend to improve the insulation property of the metal powder surfaces.

However, the conventional surface treatment methods are all to complete the preparation of a passivation film or an insulating film under the process conditions of normal temperature or less than 200 ℃, and have a reliability problem more or less when used for a long time at high temperature, and thus the problem cannot be fundamentally solved. For example, the physical coating method generally forms a thin film by diluting a silicone resin, a silicate, a metal oxide, or the like with a solvent; the chemical conversion film method generally uses a redox reaction to reduce oxidation of metal atoms on the surface of the metal powder to form a chemical conversion film, such as phosphating.

However, the above prior art cannot adapt to long-term use at high temperature in terms of physical properties, such as cracking of silicone resin, cracking of phosphate film and even falling off, and basically because the bonding force between the above film and the substrate cannot adapt to long-term use at high temperature, on one hand, the physical properties of the film change, and on the other hand, the coefficient difference between the substrate and the film is large, so that the problems cannot be fundamentally solved.

The invention provides a mould pressing inductance with self-repairing function, which designs three insulating layers with different properties and functions on the surface of soft magnetic metal powder, wherein the insulating layers can have optimal insulation, heat resistance and thinnest film thickness, the outer layer has optimal strength, toughness, moisture absorption resistance and thickest film thickness, and the preparation method of the middle layer is to mix the soft magnetic metal powder generated at the innermost layer with special thermoplastic resin powder, so that the thermoplastic powder is uniformly distributed on the surface of the soft magnetic metal powder with the insulation of the inner layer. The innermost layer is generally obtained by a chemical conversion method or a physical coating method, and the outermost layer is generally obtained by uniformly stirring a binder and the above mixture and granulating the mixture into a granulated powder having a certain fluidity. Then the metal powder with the three insulating layers and the coil winding thereof are pressed into a die pressing inductor in a die, and curing treatment is carried out to ensure that the binder resin of the outer insulating layer is completely cured. The die-pressed inductor prepared by the method has the function of self-repairing cracks of the internal insulating layer in the use process, and the principle is that the internal powder insulating layer is easy to age and crack and other defects are easy to occur as the use temperature of the inductor is higher, so that short circuit, even burning and other faults occur.

Disclosure of Invention

The invention provides a molded inductor with a self-repairing function. The invention mixes a special thermoplastic resin powder into the soft magnetic metal powder after surface insulation treatment, so that the thermoplastic powder is uniformly distributed on the surface of the soft magnetic metal powder with an insulating layer, then the binder and the mixture are uniformly stirred and granulated into granulated powder with certain fluidity, finally the granulated powder and a coil winding thereof are pressed into a die pressing inductor in a die, and the solidification treatment is carried out so that the binder is completely solidified, and the invention specifically comprises the following steps:

the soft magnetic metal material suitable for the invention can be one or more of atomized iron powder, carbonyl iron powder, iron-silicon soft magnetic series powder, iron-silicon-chromium soft magnetic series powder, permalloy soft magnetic alloy powder and amorphous soft magnetic metal powder. After the materials are selected, the materials are subjected to insulation coating treatment, and the metal powder is subjected to insulation treatment three times in sequence, so that the insulation coating metal powder with a three-layer structure is obtained.

First, the surface of the metal soft magnetic powder is modified so as to form an insulating thin film on the surface, the main component of the thin film may be one or more of phosphate, silicate, borate, chromate, permanganate, nitrate, aluminate, and the like, and the treatment method may be a chemical conversion method or a physical coating method depending on whether or not the insulating layer and the surface of the metal powder are chemically reacted. The insulating layer is a covalent bond or an ionic bond compound, so the insulating layer has good insulating property and heat-resistant property so as to meet the requirements of heat aging resistance and voltage breakdown resistance in the use process of the molded inductor, and the thickness of the innermost layer film prepared by the method is less than or equal to 60 nanometers.

Secondly, selecting a thermoplastic resin powder material which can be one or more than one mixture of thermoplastic resin with the softening temperature of 80-160 ℃ or resin modified substance thereof, wherein the thermoplastic resin powder does not react with the adhesive resin used for granulation, further requiring the initial decomposition temperature of the thermoplastic material to be more than or equal to 260 ℃, the powder particle size distribution to be 0.01-10.00um, and the volume average particle size D50 to be 0.2-2.0um, more importantly, the ratio of the volume average particle size D50 of the resin powder to the volume average particle size D50 of the soft magnetic metal powder to be less than or equal to 0.20, preferably less than or equal to 0.05; then, the thermoplastic resin powder is uniformly mixed with the soft magnetic metal powder with the inner layer insulation, the thermoplastic resin powder accounts for 0.5 to 2.0 weight percent of the soft magnetic metal powder, the mixing process must be completed at a certain temperature to ensure that the resin powder is tightly combined with the insulation layer on the surface of the soft magnetic metal, and the mixing temperature is generally selected to be between plus or minus 50 ℃ of the softening temperature of the thermoplastic resin powder.

Then, the soft magnetic metal powder having the two-time insulation is mixed with the third layer resin. The third layer resin must be uniformly mixed with the soft magnetic metal powder having two times of insulation by means of a diluent thereof in a liquid state, and then the third layer resin is made into a granulated powder having a certain agglomerated particle size by a granulation method and the diluent in the binder is completely removed, so that the resulting granulated powder has fluidity and a certain bulk density, and the binder accounts for 2.5 to 4.5 weight percent of the soft magnetic metal powder. The main body of the adhesive can be one or more than one mixture of epoxy resin, phenolic resin, cyanate ester, silicon resin and the like, and is matched with a corresponding curing agent to form an adhesive system.

And secondly, molding and pressing the molded inductor. Molding the soft magnetic metal powder with three layers of insulation and the coil winding in a molding machine and a corresponding mold, wherein the molding process comprises the following steps: (1) placing a coil winding in a mould, wherein the coil is suspended in a powder forming space of the mould, fixing the two ends of an electrode of the coil to ensure that the coil is uniformly separated from the mould wall of the mould, closing the mould to form a mould pressing space, (2) filling a certain amount of granulated powder in the mould forming space and compacting the granulated powder by using a pneumatic valve to ensure that the coil is completely embedded by the granulated powder, (3) starting pressing, applying pressure by using a punch to mould the granulated powder and the coil winding into a mould pressing inductor, wherein the coil winding is arranged in the mould pressing inductor, the iron core formed by compacting the granulated powder is arranged outside the mould pressing inductor, the forming pressure is between 400 and 650MPa, the pressure maintaining time is between 0.5 and 5.0 seconds, (4) demoulding, opening a cavity, and then releasing the punch and ejecting a product by using a lower punch.

And thirdly, curing the molded inductor. And (3) putting the pressed molded inductor into a drying oven for binder curing treatment at 80-200 ℃, keeping the temperature for 10-300 minutes in atmosphere or protective atmosphere, so as to ensure that the binder is not oxidized while being cured completely.

Drawings

FIG. 1 is a schematic diagram of the structure of the powder of the present invention.

Fig. 2 is a schematic diagram of a molded inductive product of the invention.

Example 1