A high-reliability underfill material with good electrical insulation

Abstract

The present invention relates to a high-reliability underfill material with excellent electrical insulation. The underfill material is composed of the following raw materials: 35-40 parts of a self-synthesized acid anhydride curing agent, 15-25 parts of a diphenol methane epoxy resin, 15-20 parts of an aminophenol-based trifunctional epoxy resin, 6-12 parts of a toughening agent, 0.5-1 part of a silane coupling agent, 4-7 parts of a diluent, and 8-12 parts of a latent curing accelerator. The underfill material of the present invention has the advantages of excellent electrical insulation, high and low temperature resistance, and good temperature and humidity resistance. Compared with traditional underfill materials, it has significant advantages and can improve the reliability of electronic devices.

Description

Technical Field

[0001] The invention relates to a high-reliability bottom filling material with good electrical insulation, belonging to the field of adhesives. Background Art

[0002] As the integration of electronic devices increases, device pin sizes and pitches shrink, placing increasingly stringent demands on the solder joints' ability to withstand impact stress and maintain electrical insulation. Underfill technology utilizes an epoxy resin material applied to the underside of the device to provide superior device protection. During temperature cycling, device solder joints are subject to additional stress, and underfill materials effectively absorb this stress. Under high temperature and humidity can cause short circuits between closely spaced solder joints, and underfill materials improve electrical insulation between these joints. Advanced underfill technology can meet the increasingly stringent reliability requirements of electronic devices.

[0003] The rapid development of underfill technology has led to the problem that traditional underfill materials have poor protection for the solder joints of electronic device pins during temperature cycling and high-temperature and high-humidity aging, which seriously affects the reliability of electronic devices. Summary of the Invention

[0004] Currently available underfill materials generally suffer from poor electrical insulation and reliability. The present invention addresses the shortcomings of the existing technology by providing a high-reliability underfill material with excellent electrical insulation. The resulting underfill material exhibits excellent electrical insulation, high and low temperature resistance, and high temperature and humidity resistance. Compared to traditional underfill materials, it offers significant advantages, resulting in higher reliability for electronic devices.

[0005] The present invention solves the above-mentioned technical problems with the following technical solution: a method for preparing a high-reliability underfill material with good electrical insulation:

[0006] a. By mass: 14 to 15 parts of trimellitic anhydride, 5.5 to 6.5 parts of pyridine, 22 to 24 parts of thionyl chloride, and 0.03 to 0.06 parts of dimethylformamide are added sequentially to a three-necked flask, and then an equal volume of dichloroethane is added as a solvent. A condenser is installed, heated to 55 to 65°C, the speed is set to 20 RPM, mechanically stirred for 0.5 to 1 hour, and cooled to room temperature; 14 to 15 parts of pyridine are added dropwise at a uniform rate under the stirring conditions, and the dropping speed is controlled to be completed within 1 hour; 40 to 45 parts of polypropylene glycol are added dropwise at a uniform rate under the stirring conditions, and the dropping speed is controlled to be completed within 2.5 hours; the speed is set to 35 RPM, mechanically stirred for 1 to 2 hours, the mixture is poured into a separatory funnel, and an equal volume of deionized water is added to the mixture. After shaking, the water layer is removed, and the remaining liquid is distilled at 80°C under reduced pressure for 1 hour to obtain a self-synthesized acid anhydride curing agent;

[0007] b. By mass: 35 to 40 parts of a self-synthesized curing agent, 15 to 25 parts of a diphenol methane epoxy resin, 15 to 20 parts of an aminophenol trifunctional epoxy resin, 6 to 12 parts of a toughening agent, 0.5 to 1 part of a silane coupling agent, 4 to 7 parts of a diluent, and 8 to 12 parts of a latent curing accelerator are sequentially added to a stirred tank, the speed is set to 35 RPM under vacuum conditions of -0.098 MPa, and stirred for 2 to 3 hours to obtain the bottom filling material of the present invention.

[0008] On the basis of the above technical solution, the present invention can also be improved as follows.

[0009] Furthermore, the polypropylene glycol is PPG-400 produced by Hai'an Petrochemical Plant in Jiangsu Province.

[0010] The beneficial effect of adopting the above further scheme is that the terminal hydroxyl groups of the polypropylene glycol molecular chain can generate a synthetic product with a trimellitic anhydride structure and pyridine hydrochloride through an esterification reaction; it effectively increases the flexibility and disorder of the molecular chain, keeps the synthetic product in a liquid state, and has good processability and reactivity.

[0011] Furthermore, the self-synthesized acid anhydride curing agent is a bifunctional acid anhydride curing agent with a viscosity of 800 to 1500 mPa·s and an acid anhydride equivalent of 275 to 295 g / mol.

[0012] The beneficial effect of adopting the above further scheme is that the bifunctional acid anhydride curing agent with a polyether long-chain molecular structure has better electrical insulation performance, better high and low temperature impact resistance, and better moisture and heat resistance than traditional acid anhydride curing agents, which is the key core of the present invention.

[0013] Furthermore, the diphenol methane epoxy resin is ZLF-160U produced by Xi'an Zhilun.

[0014] The beneficial effects of adopting the above further solution are: the diphenol methane type epoxy resin has the characteristics of low viscosity, high reactivity and high adhesion.

[0015] Furthermore, the aminophenol-based trifunctional epoxy resin is 630LSD produced by Shandong Shengquan Electronic Materials Co., Ltd.

[0016] The beneficial effect of adopting the above further solution is that the aminophenol-based trifunctional epoxy resin can form a higher cross-linking density during the thermal curing process, so that the system has high adhesion, good heat resistance and good electrical insulation performance.

[0017] Furthermore, the toughening agent is a polyurethane-modified epoxy resin, preferably EPU-133S produced by Shanghai Luohe High-tech Materials Co., Ltd.

[0018] The beneficial effect of adopting the above further solution is that the polyurethane-modified epoxy resin forms an interpenetrating polymer network structure with the polyurethane molecular segments and the epoxy molecular segments, which has a good toughening effect and can improve the toughness and bonding performance of the system.

[0019] Furthermore, the silane coupling agent is epoxytrimethoxysilane, preferably Dynasylan GLYMO produced by Evonik Industries AG of Germany.

[0020] The beneficial effect of adopting the above further solution is that the epoxy group and the siloxane group in the epoxytrimethoxysilane molecular structure interact with each other, which is beneficial to improving the wettability of the system to the substrate, and improving the flow filling performance and adhesion performance.

[0021] Furthermore, the diluent is diglycidyl tetrahydrophthalate, preferably XY815 produced by Anhui Xinyuan Technology Co., Ltd.

[0022] The beneficial effect of adopting the above further solution is that diglycidyl tetrahydrophthalate reduces the viscosity of the system, improves the flow and filling performance, and has good low-temperature resistance, thereby improving the low-temperature adhesion of the system.

[0023] Furthermore, the latent curing accelerator is an aromatic diamine salt, preferably HS-601 produced by Chuzhou Huisheng Electronic Materials Co., Ltd.

[0024] The beneficial effect of adopting the above further solution is that the liquid aromatic diamine salt has good dispersibility and stability in the system; and has a good promoting effect on the acid anhydride curing agent, which can meet the system's requirements of lowering the curing temperature and increasing the curing speed.

[0025] The beneficial effects of the present invention are as follows: the bottom filling material of the present invention has good electrical insulation, effectively reducing adverse effects such as short circuits caused by narrow solder joints and pin spacing; has good high and low temperature resistance, effectively absorbing the stress on the pin solder joints during temperature changes to protect them; and has good temperature and humidity resistance, effectively ensuring the reliability of electronic devices in actual working environments. DETAILED DESCRIPTION

[0026] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0027] Example 1 Synthesis of Self-synthesized Acid Anhydride Curing Agent An-1

[0028] By mass: 74.23 g of trimellitic anhydride, 30.38 g of pyridine, 114.62 g of dichlorothionyl, and 0.25 g of dimethylformamide were added sequentially into a three-necked flask, and an equal volume of dichloroethane was added as a solvent. A condenser was installed, and the mixture was heated to 60° C., the speed was set to 20 RPM, and mechanical stirring was performed for 1 hour. The mixture was cooled to room temperature; under the same stirring condition, 73.08 g of pyridine was added dropwise at a uniform rate, and the dropping speed was controlled to complete the addition within 1 hour; under the same stirring condition, 207.69 g of polypropylene glycol PPG-400 was added dropwise at a uniform rate, and the dropping speed was controlled to complete the addition within 2.5 hours; the speed was set to 35 RPM, and mechanical stirring was performed for 2 hours. The mixture was poured into a separatory funnel, and an equal volume of deionized water was added to the mixture. After shaking, the water layer was removed, and the remaining liquid was distilled under reduced pressure at 80° C. for 1 hour to obtain a self-synthesized acid anhydride curing agent An-1.

[0029] Example 2, Example 3, Example 4

[0030] According to the formula shown in Table 1, the synthetic anhydride curing agent An-1, diphenol methane type epoxy resin ZLF-160U, aminophenol trifunctional epoxy resin 630LSD, toughening agent EPU-133S, silane coupling agent GLYMO, diluent XY815, and latent curing accelerator HS-601 were weighed and placed in a double planetary stirred tank in sequence. The mixture was set to 35 RPM under vacuum at -0.098 MPa and stirred for 3 hours to prepare the underfill material.

[0031] Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4

[0032] According to the formula shown in Table 1, the following ingredients were weighed: synthetic anhydride curing agent An-1, Shin Nippon Rika hexahydrophthalic anhydride curing agent MH700G, American Vantrus dodecenylsuccinic anhydride curing agent K-12, diphenol methane epoxy resin ZLF-160U, aminophenol trifunctional epoxy resin 630LSD, toughening agent EPU-133S, silane coupling agent GLYMO, diluent XY815, and latent curing accelerator HS-601. The mixture was placed in a double planetary stirred tank, and the mixture was stirred for 3 hours at a speed of 35 RPM under vacuum of -0.098 MPa.

[0033] Specific test examples

[0034] The following tests were conducted to evaluate the performance of the underfill materials of Examples 2-4 and Comparative Examples 1-4. Flowability and fillability were characterized by viscosity and fill time; reliability of electronic devices was characterized by adhesion after exposure to a high-low temperature cycle chamber and a double 85°C aging chamber; and electrical insulation was characterized by surface resistivity after exposure to a double 85°C aging chamber.

[0035] Test Example 1 Flow and Filling Test

[0036] The viscosity was measured using a Brookfield viscometer with a 42# rotor at 25°C, in mPa·s. The filling time was measured using a simulated packaged chip with dimensions of 20 mm × 20 mm and a gap of 30 μm at 25°C, in seconds.

[0037] Test Example 2 Electrical insulation test

[0038] The bottom filling material is made into a functional sample and heated and cured at 130°C for 10 minutes. It is then placed in a damp heat aging environment box (set temperature 85°C, humidity 85% RH). After a 50V DC power supply is applied for 500 hours, an insulation resistance tester is used to test the surface insulation resistance of the functional sample after damp heat aging, in Ω.

[0039] Experimental Example 3 Reliability Test

[0040] The bottom filling material was made into a PCB bonding sample and heated and cured at 130°C for 10 minutes. The sample was then placed in a high and low temperature cycle box (set high temperature 70°C, low temperature -25°C) and a damp heat aging environment box (set temperature 85°C, humidity 85% RH) for 168 hours. After being taken out, the sample was placed at room temperature for 24 hours. The shear strength before and after aging was tested using a universal testing machine, with the unit being MPa.

[0041] Table 1 Formulation and performance list

[0042]

[0043] As can be seen from the data in Table 1, the bottom filling material of the present invention has the advantages of good electrical insulation, good high and low temperature resistance, good heat and moisture resistance, etc., which has obvious advantages over traditional bottom filling materials and makes electronic devices have higher reliability. Among them, Comparative Example 1 does not use aminophenol trifunctional epoxy resin 630LSD, and the bonding strength decreases, the electrical insulation is poor, and the high and low temperature resistance and heat and moisture resistance are acceptable; Comparative Example 2 does not use tetrahydrophthalic acid diglycidyl ester XY815, and the bonding strength is not affected, the electrical insulation is good, the heat and moisture resistance is good, but the high and low temperature resistance is poor. Comparative Examples 3 and Comparative Examples 4 do not use the self-synthesized acid anhydride curing agent in Example 1 of the present invention, but use commercially available products hexahydrophthalic anhydride MH700G and dodecenyl succinic anhydride K-12; MH700G has acceptable bonding strength, but poor electrical insulation and aging resistance; K-12 has acceptable bonding strength and high and low temperature resistance, but poor electrical insulation and heat and moisture resistance.

[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high-reliability underfill material with good electrical insulation, comprising the following components, in parts by weight: 35-40 parts of a self-synthesized acid anhydride curing agent, 15-25 parts of a diphenol methane epoxy resin, 15-20 parts of an aminophenol trifunctional epoxy resin, 6-12 parts of a toughening agent, 0.5-1 part of a silane coupling agent, 4-7 parts of a diluent, and 8-12 parts of a latent curing accelerator; the self-synthesized acid anhydride curing agent is prepared as follows: 14-15 parts of trimellitic anhydride, 5.5-6.5 parts of pyridine, 22-24 parts of thionyl chloride, and 0.03-0.06 parts of dimethylformamide are sequentially added to three portions of the mixture, An equal volume of dichloroethane was added to the flask as a solvent, a condenser was installed, and the mixture was heated to 55-65°C, the rotation speed was set to 20 RPM, and mechanical stirring was performed for 0.5-1 hour. The mixture was then cooled to room temperature. Under the same stirring conditions, 14-15 parts of pyridine was added dropwise at a uniform rate, and the addition speed was controlled to complete the addition within 1 hour. Under the same stirring conditions, 40-45 parts of polypropylene glycol was added dropwise at a uniform rate, and the addition speed was controlled to complete the addition within 2.5 hours. The rotation speed was set to 35 RPM, and mechanical stirring was performed for 1-2 hours. The mixture was poured into a separatory funnel, and an equal volume of deionized water was added to the mixture. The mixture was shaken and the water layer was removed. The remaining liquid was distilled under reduced pressure at 80°C for 1 hour to obtain a self-synthesized acid anhydride curing agent. The reaction formula is as follows: 。 2. The high-reliability underfill material with good electrical insulation according to claim 1, characterized in that: The polypropylene glycol has a viscosity of 3000 to 4500 mPa·s, a molecular weight of 360 to 440, and a hydroxyl value of 255 to 312 mgKOH / g.

3. The high reliability underfill material with good electrical insulation according to claim 1, characterized in that: The self-synthesized acid anhydride curing agent has a viscosity of 800 to 1500 mPa·s and an acid anhydride equivalent of 275 to 295 g / mol.

4. The high-reliability underfill material with good electrical insulation according to claim 1, characterized in that: The diphenol methane epoxy resin has a viscosity of 1000-1400 mPa·s at 25° C., an epoxy equivalent of 156-165 g / eq, and a total chlorine content of less than 100 ppm.

5. The high reliability underfill material with good electrical insulation according to claim 1, characterized in that: The aminophenol-based trifunctional epoxy resin has a viscosity of 500-1000 mPa·s at 25° C., an epoxy equivalent of 95-105 g / eq, and a total chlorine content of less than 750 ppm.

6. The high-reliability underfill material with good electrical insulation according to claim 1, characterized in that: The toughening agent is polyurethane modified epoxy resin with a viscosity of 20,000 to 40,000 mPa·s at 25° C., an epoxy equivalent of 240 to 280 g / eq, and a total chlorine content of less than 900 ppm.

7. The high reliability underfill material with good electrical insulation according to claim 1, characterized in that: The silane coupling agent is epoxytrimethoxysilane.

8. The high reliability underfill material with good electrical insulation according to claim 1, characterized in that: The diluent is diglycidyl tetrahydrophthalate, with a viscosity of 500-1000 mPa·s at 25° C., an epoxy equivalent of 150-180 g / eq, and a total chlorine content of less than 900 ppm.

9. The high-reliability underfill material with good electrical insulation according to claim 1, characterized in that: The latent curing accelerator is an aromatic diamine salt with a viscosity of 50 to 300 mPa·s at 25° C. and an amine equivalent of 35 to 45 g / mol.

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