Inorganic-organic composite type impregnation solution for inductor and preparation process

Abstract

The application relates to an inorganic-organic composite type inductance impregnation liquid and a preparation process, and relates to an impregnation liquid which is prepared from the following components in mass parts: bisphenol A type epoxy resin, tetraglycidyl ether, silica powder, a coupling agent, an active diluent and a curing agent. The silica powder is pretreated by using the coupling agent, and a layer of coupling agent molecules is wrapped on the surface of the silica powder, so that the interaction between the silica powder and the organic molecules is increased, the disadvantage of weak adhesion of the epoxy resin is improved, the inorganic substance advantages of high temperature resistance and aging resistance are fully exerted without reducing the strength, and the silica powder has high thermal stability, so that the flame retardation effect and the dielectric property of the impregnation liquid are obviously improved.

Description

Technical Field

[0001] This invention relates to an impregnation liquid, specifically an impregnation liquid for inductors. Background Technology

[0002] Inductors are core components in electronic circuits that realize electromagnetic induction, filtering, and energy storage, and are widely used in communication equipment, automotive electronics, power modules, industrial control, and other fields. As electronic devices develop towards higher frequencies, higher power, and smaller sizes, stringent requirements are placed on the performance indicators of inductors. They not only need to have stable inductance values ​​and low loss characteristics, but also need to meet long-term reliability under complex operating conditions such as high temperature, high humidity, and vibration.

[0003] Impregnation is one of the core processes in inductor manufacturing. The principle is that the impregnating solution penetrates the inductor windings and the frame, as well as the gaps between the winding turns, and after curing, forms a dense protective film. This improves the inductor's insulation performance, mechanical strength, moisture resistance, and shock resistance, while reducing the inductor's distributed capacitance and high-frequency losses. Therefore, the performance of the impregnating solution directly determines the final quality and lifespan of the inductor.

[0004] Currently, the mainstream inductor impregnation solutions on the market are mainly divided into three categories: epoxy resin, phenolic resin, and polyurethane. Among them, epoxy resin impregnation solutions are the most widely used due to their good insulation and strong adhesion. However, traditional epoxy resin impregnation solutions have obvious defects: First, they have insufficient heat resistance, with the glass transition temperature (Tg) after curing generally below 120℃. Under the high-temperature environment generated by the long-term operation of high-power inductors, they are prone to softening and cracking, leading to rapid degradation of inductor performance. Second, they have high viscosity and limited penetration ability, making it difficult to fully fill the tiny gaps in the inductor. After curing, they are prone to forming pore defects, affecting insulation and moisture-proof effects. Third, they have poor flame retardant properties, as most do not contain highly efficient flame retardant components, failing to meet the safety standards of automotive electronics, industrial equipment, and other fields. Summary of the Invention

[0005] The purpose of this invention is to provide an inorganic-organic composite impregnation solution that is resistant to high temperatures, has high permeability, and is highly flame-retardant. Simultaneously, by improving the processing technology, costs and process complexity are reduced.

[0006] The impregnation solution for the inorganic-organic composite inductor of the present invention comprises the following substances: Silica powder with a particle size of 60~100nm (30~40 phr by weight); Coupling agent (1-2 phr by weight); Bisphenol A type epoxy resin (40-60 phr by weight), epoxy equivalent of 200 g / mol; Tetraglycidyl ether (40-60 phr by weight), wherein the tetraglycidyl ether is pentaerythritol glycidyl ether, and the epoxy equivalent is 100 g / mol; the total amount of bisphenol A type epoxy resin and tetraglycidyl ether is 100 parts by weight. Reactive diluent (10-20 phr by weight), such as polyethylene glycol glycidyl ether, allyl glycidyl ether, phenyl glycidyl ether, etc. Curing agent (1-3 phr by weight), such as isocyanate, pyridine, amino resin, etc.

[0007] By adjusting the content of epoxy resin and silica powder, inductive impregnation solutions with different high temperature resistance, high permeability, and high flame retardancy can be obtained.

[0008] A method for preparing an impregnating solution for inductors, the method comprising the following steps: a. Place the silica powder in the bucket; b. Pour the dispersion solution (such as toluene) into the container, and then turn on the stirrer at a speed of 250-350 r / min (preferably 300 / min); c. Slowly pour the coupling agent into the silica powder solution and stir continuously for 2 hours; d. After stirring, let stand, pour off the clear liquid on top, place the silica powder in a tray and spread it out, bake in an oven at 60℃ for 1 hour, and then take it out for use. e. The total mass fraction of epoxy resin (bisphenol A type epoxy resin and tetraglycidyl ether) is 100. Then, weigh 30 parts by mass of treated silica powder, 1 part by mass of curing agent and 10 parts by mass of reactive diluent. Stir the above mixture evenly with a mixer for 1 hour and 400 r / min.

[0009] When adding coupling agent, attention should be paid to the dropping speed. If the speed is too fast, the coupling agent layer of some upper silica powder will be too thick, and the lower silica powder layer will be too thin. The dispersion solution can be toluene.

[0010] The inorganic-organic impregnation solution mixed with the resin is injected into a desiccant and heated to 75-85°C (preferably 80°C). Inductors are then placed in batches, impregnated for 1 hour, and then removed and air-dried for 2 hours. Finally, they are baked at 150°C for two hours.

[0011] The advantages of this invention are: First, the silica powder was pretreated with a coupling agent, which coated its surface with a layer of coupling agent molecules. This increased the interaction between the silica powder and the organic molecules, improved the weak adhesion of epoxy resin, and fully utilized the advantages of inorganic materials in high temperature resistance and aging resistance without reducing strength. Secondly, different types of epoxy resins can be used in combination. Bisphenol A type epoxy resin has rigid groups, which can increase the glass transition temperature of the cured resin. Pentaerythritol glycidyl ether has low viscosity, which can achieve good wettability on different inductive surfaces. At the same time, it has multiple functions, increases crosslinking sites, further improves the glass transition temperature and mechanical properties of the cured product, and increases the applicability of inorganic-organic impregnation solutions. Third, silica powder has high thermal stability, which can significantly improve the flame retardant effect and dielectric properties of the impregnation liquid; Fourth, the impregnation process is simplified. Simply pour the inorganic-organic impregnation solution into the dehydrator and heat the solution to the specified temperature to operate the impregnation process of the inductor. Detailed Implementation

[0012] The present invention will now be described in detail with reference to the embodiments.

[0013] Example 1 Step 1: Pretreatment of silica powder using a coupling agent: a. Place 3 kg of silica powder (particle size 60~100 nm) into a container; b. Pour 1L of toluene dispersion solution into the container, and then turn on the stirrer at 300 rpm; c. Slowly pour 200g of coupling agent (KH550) into the silica powder solution and stir continuously for 2 hours; d. After stirring, pour off the clear liquid on top, place the silica powder in a tray and spread it out, bake it in an oven at 60°C for 1 hour, and then take it out for later use.

[0014] Step 2: Preparation of the impregnation solution With a total mass fraction of 100 for bisphenol A epoxy resin and pentaerythritol glycidyl ether, add 4 kg of bisphenol A epoxy resin and 6 kg of pentaerythritol glycidyl ether. Then weigh out 30 parts by mass of treated silica powder, 3 parts by mass of curing agent and 10 parts by mass of reactive diluent. Stir the mixture evenly with a mixer for 1 hour and 400 r / min.

[0015] When adding coupling agent, attention should be paid to the dripping speed. If the speed is too fast, the coupling agent layer of the upper silica powder will be too thick and the lower silica powder layer will be too thin.

[0016] The inorganic-organic impregnation solution mixed with the resin was injected into a desiccant and heated to 80°C. Inductors were then placed in batches and impregnated for 1 hour. After that, the inductors were removed and dried for 2 hours, and then baked at 150°C for two hours.

[0017] Using the method of Example 1, the amounts of bisphenol A epoxy resin and pentaerythritol glycidyl ether were adjusted (as shown in Table 1), and the operations of Examples 2-4 were performed respectively, resulting in the test results shown in Table 2.

[0018] Table 1 Formula and Composition composition Example 1 Example 2 Example 3 Bisphenol A epoxy resin 40 50 60 Pentaerythritol glycidyl ether 60 50 40 Silica powder 30 30 30 Coupling agent 2 2 2 Reactive diluent 10 10 10 curing agent 3 3 3 Toluene 80 80 80

[0019] Table 2 Comparison of some mechanical properties of different formulations performance Example 1 Example 2 Example 3 Heat distortion temperature (°C) 200 231 265 Tensile strength (MPa) 84 89 95 Level 3 moisture-sensitive tensile strength (MPa) 55 61 76 Flame retardant rating (UL94 standard) V0 V0 V0

[0020] The test method for heat distortion temperature is as follows: the size of the sample in the heat distortion temperature test is 80mm×10mm×4mm. According to the test requirements of GB / T 1634—2004, the heat distortion temperature of the resin after curing is determined by a heat distortion Vicat softening point tester.

[0021] The tensile strength test method is as follows: the size of the specimen in the tensile test is 200mm×20mm×4mm, and the mechanical properties of the specimen are tested using an INSTRON 3382 universal tensile testing machine.

[0022] The method for testing the tensile strength of a level 3 moisture-sensitive specimen is as follows: the specimen size in the tensile test is 200 mm × 20 mm × 4 mm, and the mechanical properties of the specimen are tested using an INSTRON 3382 universal tensile testing machine.

[0023] As can be seen from Table 2, the increased content of bisphenol A epoxy resin led to improvements in heat distortion temperature, tensile strength, and tensile strength after three-stage moisture sensitivity.

Claims

1. An impregnation solution for inorganic-organic composite inductors, characterized in that, The impregnation solution is prepared from the following components in parts by weight: Bisphenol A type epoxy resin and tetraglycidyl ether, with a weight ratio of 2~3:2~3, and a total mass fraction of 100, wherein the epoxy equivalent of the bisphenol A type epoxy resin is 200 g / mol, and the epoxy equivalent of the tetraglycidyl ether is 100 g / mol. 30-40 phr of silica powder with a particle size of 60-100 nm; Coupling agent 1~2 phr; 10-20 phr of reactive diluent; Hardener 1~3 phr.

2. The impregnation solution for inorganic-organic composite inductors as described in claim 1, characterized in that, The tetraglycidyl ether mentioned is pentaerythritol glycidyl ether.

3. The impregnation solution for inorganic-organic composite inductors as described in claim 1, characterized in that, The active diluent is one or more of polyethylene glycol glycidyl ether, allyl glycidyl ether, and phenyl glycidyl ether.

4. The impregnation solution for inorganic-organic composite inductors as described in claim 1, characterized in that, The curing agent is one or more of isocyanate, pyridine, and amino resin.

5. The method for preparing the impregnating solution for the inorganic-organic composite inductor according to any one of claims 1-4, characterized in that, The preparation method includes the following steps: a. Place the silica powder in the bucket; b. Pour the dispersion solution into the bucket and start stirring; c. Continue to slowly pour in the coupling agent and stir to complete the silica pretreatment; d. Let stand, pour off the clear liquid on top, and dry the pretreated silica powder; e. Take bisphenol A type epoxy resin, tetraglycidyl ether, silica powder obtained in step d, curing agent and reactive diluent, and stir the above substances evenly with a mixer to obtain the impregnation solution.

6. The method for preparing the impregnating solution for inorganic-organic composite inductors as described in claim 5, characterized in that, The dispersion solution is toluene.

7. The method of using the impregnating solution for inorganic-organic composite inductors as described in any one of claims 1-4, characterized in that, Inject the impregnation solution into the centrifuge, heat it to 75-85℃, then place the inductor in the machine. After impregnation, remove the inductor, air dry it, and then bake it.