An oxidized polyethylene wax modified curing agent, its preparation method, an epoxy encapsulant, and their applications

Abstract

The present invention relates to the technical field of epoxy encapsulation materials, and particularly relates to an oxidized polyethylene wax modified curing agent and its preparation method, an epoxy encapsulant and its application. The oxidized polyethylene wax modified curing agent is obtained by reacting raw materials containing oxidized polyethylene wax and phenolic resin, and the viscosity of the oxidized polyethylene wax modified curing agent is 0.5 - 5P. Adding the oxidized polyethylene wax modified curing agent prepared by the present invention to the raw material composition to prepare an epoxy encapsulant, so that when the prepared epoxy encapsulant is subjected to QFN encapsulation, it has fewer air holes, the air hole size is smaller, and there are no obvious imprints on the surface of the encapsulation body, meeting the usage standards.

Description

Technical Field

[0001] The present invention relates to the technical field of epoxy molding compounds, and particularly relates to an oxidized polyethylene wax modified curing agent, a preparation method thereof, an epoxy molding compound and an application thereof. Background Art

[0002] In the central position at the bottom of a QFN package (quad flat no-lead package), there is usually a large-area exposed pad for heat conduction. This pad can serve as a direct heat dissipation channel for conducting the heat generated by the chip working inside the package. After surface mounting, the pad is directly soldered to the circuit board, and the heat dissipation holes of the PCB (printed circuit board) can diffuse the excess power consumption into the copper ground plane to absorb the excess heat, greatly improving the heat dissipation performance of the chip. Different from traditional DIP (dual in-line package) or SOP (small outline package) with gull-wing pins, after surface mounting, the QFN package has a short conduction path between the pins and the PCB pads, and the self-inductance coefficient and the wiring resistance inside the package are very low, so it can also provide good electrical performance.

[0003] The encapsulation process of QFN products is similar to storing water in a pool with several isolated islands. Due to the existence of the isolated islands, the fluid-like molding compound will be greatly disturbed during the flowing process at high temperature. These disturbances make it very difficult for the gas in the mold cavity to be discharged, and it is extremely easy to form air holes after curing. Further, these disturbances will also cause the internal components of the molding compound to be unevenly dispersed during the flowing process, and it is extremely easy to form imprints on the surface of the molded body after curing. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art, and thus provide an oxidized polyethylene wax modified curing agent, a preparation method thereof, an epoxy molding compound and an application thereof. The present invention first generates an oxidized polyethylene wax modified curing agent by reacting oxidized polyethylene wax and phenolic resin under specific reaction conditions, and then adds the obtained oxidized polyethylene wax modified curing agent to the raw material composition to prepare an epoxy molding compound, so that the prepared epoxy molding compound has fewer air holes and smaller air hole sizes during QFN encapsulation, and there are no obvious imprints on the surface of the molded body, meeting the use standards.

[0005] To achieve the above purpose, in the first aspect of the present invention, an oxidized polyethylene wax modified curing agent is provided. The oxidized polyethylene wax modified curing agent is obtained by reacting a raw material containing oxidized polyethylene wax and phenolic resin, and the viscosity of the oxidized polyethylene wax modified curing agent is 0.5 - 5P.

[0006] Preferably, the weight ratio of the amount of the oxidized polyethylene wax to the phenolic resin is 1:20 - 100, and more preferably 1:30 - 50.

[0007] Preferably, the phenolic resin is selected from one or more of multifunctional phenolic resin, linear phenolic resin, biphenyl phenolic resin and XY-lock phenolic resin.

[0008] The second aspect of the present invention provides a method for preparing the aforementioned oxidized polyethylene wax modified curing agent, the method comprising: melting a phenolic resin under protective atmosphere conditions, and then adding the oxidized polyethylene wax to react.

[0009] Preferably, the melting temperature is 120-160°C.

[0010] Preferably, the reaction conditions include: temperature of 120-160° C. and time of 2-36 h.

[0011] Preferably, the method further comprises filtering and cooling the product obtained by the reaction.

[0012] The third aspect of the present invention provides an epoxy molding compound, which is made of a raw material composition containing an epoxy resin, an oxidized polyethylene wax modified curing agent, a accelerator, an inorganic filler, a flame retardant, a release agent, an ion capture agent, a coupling agent, a modifier and a colorant, wherein the oxidized polyethylene wax modified curing agent is the oxidized polyethylene wax modified curing agent described above.

[0013] Preferably, the weight ratio of the epoxy resin, oxidized polyethylene wax modified curing agent, accelerator, inorganic filler, flame retardant, release agent, ion capture agent, coupling agent, modifier and colorant is 1: 0.1-5: 0.01-0.5: 5-40: 0.03-0.5: 0.001-0.5: 0.001-0.2: 0.01-0.5: 0.01-0.5: 0.01-0.5.

[0014] Preferably, the weight ratio of the epoxy resin, the oxidized polyethylene wax modified curing agent and the inorganic filler is 1:0.1-2:10-25.

[0015] Preferably, the epoxy resin is selected from one or more of phenolic epoxy resin, bisphenol A epoxy resin, biphenyl epoxy resin, naphthalene ring-containing epoxy resin, o-cresol epoxy resin, dicyclopentadiene phenolic epoxy resin, multifunctional epoxy resin, alicyclic epoxy resin and bisphenol F epoxy resin.

[0016] Preferably, the inorganic filler is selected from one or more of silicon dioxide, aluminum oxide and magnesium oxide.

[0017] Preferably, the maximum particle size of the inorganic filler is 15 μm, 20 μm, 30 μm, 45 μm, 55 μm or 75 μm.

[0018] The fourth aspect of the present invention provides an application of the foregoing epoxy molding compound as a semiconductor packaging material.

[0019] Through the above technical solutions, the present invention first reacts phenolic resin and oxidized polyethylene wax under specific conditions to obtain an oxidized polyethylene wax-modified curing agent, and then uses the oxidized polyethylene wax-modified curing agent as a component in the raw material composition of the epoxy molding compound to prepare the epoxy molding compound. While the prepared epoxy molding compound has excellent fluidity, low warpage and water absorption, etc., when the epoxy molding compound is subjected to QFN packaging, it has fewer air holes, and the air hole size is smaller, and there are no obvious imprints on the surface of the plastic package, meeting the use standards. Description of the Drawings

[0020] Figure 1 is the epoxy molding compound prepared in Examples 1-4; [[ID=eleven]]

[0021] Figure 2 is the epoxy molding compound prepared in Comparative Example 1;

[0022] Figure 3 is the epoxy molding compound prepared in Comparative Example 2. Detailed Embodiments

[0023] The following will describe in detail the specific embodiments of the present invention with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0024] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range and a single point value, and between single point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0025] The inventor found through research that by reacting phenolic resin and oxidized polyethylene wax under specific conditions to obtain an oxidized polyethylene wax-modified curing agent, and then using the obtained oxidized polyethylene wax-modified curing agent with a viscosity range of 0.5-5P as a component in the raw material composition of the epoxy molding compound to prepare the epoxy molding compound, when the prepared epoxy molding compound is subjected to QFN packaging, it has fewer air holes, and the air hole size is smaller, and there are no obvious imprints on the surface of the plastic package, meeting the use standards.

[0026] The viscosity of the epoxy molding compound directly determines the flow state during the packaging process. An appropriate viscosity is very helpful for suppressing the generation of air holes and surface imprints, and the viscosity of the used oxidized polyethylene wax-modified curing agent has a great influence on the viscosity of the epoxy molding compound.

[0027] In the first aspect of the present invention, an oxidized polyethylene wax modified curing agent is provided. The oxidized polyethylene wax modified curing agent is obtained by reacting a raw material containing oxidized polyethylene wax and phenolic resin. The viscosity of the oxidized polyethylene wax modified curing agent is 0.5 - 5P. In a preferred case, the viscosity of the oxidized polyethylene wax modified curing agent is 1P.

[0028] In the oxidized polyethylene wax modified curing agent of the present invention, in a specific embodiment, the phenolic resin is selected from one or more of polyfunctional phenolic resin, linear phenolic resin, biphenyl type phenolic resin, and XY-lock phenolic resin. In a preferred embodiment, the phenolic resin is polyfunctional phenolic resin, for example, it can be a phenolic resin with the structure shown in the following formula (1).

[0029]

[0030] In the oxidized polyethylene wax modified curing agent of the present invention, the dosage ratio of the phenolic resin to the oxidized polyethylene wax should be controlled within a suitable range. In a specific embodiment, the weight ratio of the dosage of the phenolic resin to the oxidized polyethylene wax is 1:20 - 100. In a preferred embodiment, the weight ratio of the dosage of the phenolic resin to the oxidized polyethylene wax is 1:30 - 50, for example, it can be 1:30, 1:35, 1:40, 1:45, or 1:50.

[0031] In the second aspect of the present invention, a method for preparing the above-mentioned oxidized polyethylene wax modified curing agent is provided. The method includes: under the condition of a protective atmosphere, melting the phenolic resin and then adding oxidized polyethylene wax for reaction.

[0032] In the method of the present invention, in a specific embodiment, the melting temperature is 120 - 160 °C, for example, it can be 120 °C, 130 °C, 140 °C, 150 °C, or 160 °C.

[0033] In the method of the present invention, in a specific embodiment, the reaction conditions include: the temperature is 120 - 160 °C, for example, it can be 120 °C, 130 °C, 140 °C, 150 °C, or 160 °C, and the time is 2 - 36 h, for example, it can be 2 h, 4 h, 6 h, 8 h, 12 h, 16 h, 20 h, 24 h, 30 h, or 36 h.

[0034] In the method of the present invention, in a specific embodiment, the protective atmosphere is nitrogen or inert gas.

[0035] In the method of the present invention, in a specific embodiment, the method further includes cooling the product obtained from the reaction to 80 - 100 °C, for example, it can be 80 °C, 85 °C, 90 °C, 95 °C, or 100 °C.

[0036] In the method of the present invention, in a specific embodiment, the method further includes filtering and cooling the cooled material to obtain an oxidized polyethylene wax modified curing agent. In a preferred embodiment, the filtering is performed using a 100-mesh filter.

[0037] The third aspect of the present invention provides an epoxy molding compound, which is made from a raw material composition containing epoxy resin, oxidized polyethylene wax modified curing agent, accelerator, inorganic filler, flame retardant, mold release agent, ion scavenger, coupling agent, modifier and colorant, wherein the oxidized polyethylene wax modified curing agent is the oxidized polyethylene wax modified curing agent described above.

[0038] In the epoxy molding compound of the present invention, in a specific embodiment, the weight ratio of the amounts of the epoxy resin, oxidized polyethylene wax modified curing agent, accelerator, inorganic filler, flame retardant, mold release agent, ion scavenger, coupling agent, modifier and colorant is 1: 0.1-5: 0.01-0.5: 5-40: 0.03-0.5: 0.001-0.5: 0.001-0.2: 0.01-0.5: 0.01-0.5: 0.01-0.5.

[0039] In the epoxy molding compound of the present invention, in a preferred embodiment, the weight ratio of the amounts of the epoxy resin, oxidized polyethylene wax modified curing agent and inorganic filler is 1: 0.1-2: 10-25. In a more preferred embodiment, the weight ratio of the amounts of the epoxy resin, oxidized polyethylene wax modified curing agent and inorganic filler is 1: 0.5-0.8: 15-20, such as 1: 0.5: 15, 1: 0.6: 16, 1: 0.63: 16.7, 1: 0.7: 16.7 or 1: 0.8: 20.

[0040] In the epoxy molding compound of the present invention, in a specific embodiment, the epoxy resin is selected from one or more of phenolic epoxy resin, bisphenol A epoxy resin, biphenyl epoxy resin, naphthalene ring structure-containing epoxy resin, o-cresol novolac epoxy resin, dicyclopentadiene novolac epoxy resin, multi-functional group structure epoxy resin, alicyclic epoxy resin and bisphenol F structure epoxy resin.

[0041] In the epoxy molding compound of the present invention, in a preferred embodiment, the repeating structural unit n in the phenolic epoxy resin, o-cresol novolac epoxy resin, bisphenol A epoxy resin, biphenyl epoxy resin, naphthalene ring structure-containing epoxy resin and dicyclopentadiene novolac epoxy resin is 0-5, and can be, for example, 0, 1, 2, 3, 4 or 5.

[0042] In the epoxy molding compound of the present invention, in a specific embodiment, the inorganic filler is selected from one or more of silica, alumina, and magnesia. In a preferred embodiment, the maximum particle size of the inorganic filler is 15μm, 20μm, 30μm, 45μm, 55μm, or 75μm.

[0043] In the epoxy molding compound of the present invention, in a preferred embodiment, the silica is fused spherical silica.

[0044] In the epoxy molding compound of the present invention, in a specific embodiment, the accelerator is selected from one or more of organic phosphorus compounds, imidazole compounds, tertiary amine compounds and their derivatives, aromatic ureido derivatives, and aliphatic ureido derivatives.

[0045] In the epoxy molding compound of the present invention, the flame retardant determines the flame retardancy level of the material, and generally, a flame retardant without bromine and antimony elements is used in a halogen-free epoxy resin composition.

[0046] In the epoxy molding compound of the present invention, in a specific embodiment, the flame retardant is one or more of metal hydroxides, hydrated metal compounds, metal oxides, molybdates, borates, phosphorus-containing compounds, and nitrogen-containing compounds.

[0047] In the epoxy molding compound of the present invention, in a specific embodiment, the mold release agent is one or more of mineral wax, plant wax, polyethylene, and polyamide wax.

[0048] In the epoxy molding compound of the present invention, in a specific embodiment, the ion scavenger is an inorganic ion scavenger. In a preferred embodiment, the ion scavenger is one or more of hydrated metal oxides, acidic metal salts, and magnesium-aluminum compounds.

[0049] In the epoxy molding compound of the present invention, in a specific embodiment, the coupling agent is one or more of γ-glycidoxypropyl ether trimethoxysilane, γ-aminopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, and γ-aminopropyltrimethoxysilane.

[0050] In the epoxy molding compound of the present invention, in a specific embodiment, the modifier is one or more of rubber and organosilane.

[0051] In the epoxy molding compound of the present invention, in a specific embodiment, the colorant is carbon black.

[0052] The preparation method of the epoxy encapsulant of the present invention is a conventional choice in the art. The specific preparation method may include: pulverizing and uniformly mixing each component weighed according to a specific ratio at room temperature, then performing melt mixing, pulverizing, and obtaining an epoxy resin composition after mixing.

[0053] In the present invention, the equipment used for the melt mixing can be a conventional choice in the art. For example, it can be a two-roll mill, a single-screw extruder, a twin-screw extruder, a kneader or a stirrer.

[0054] The present invention will be described in detail below through examples, but the protection scope of the present invention is not limited thereto.

[0055] Unless otherwise specified, the reagents involved in the examples and comparative examples of the present invention are all commercially available products.

[0056] A1 o-cresol novolac type epoxy resin: Manufacturer: Yueyang Petrochemical, Grade: CYDCN-200;

[0057] A2 Biphenyl type epoxy resin: Manufacturer: DIC Corporation, Japan, Grade: YX4000H;

[0058] A3 Naphthalene ring-containing structure epoxy resin: Manufacturer: DIC Corporation, Japan, Grade: HP4770;

[0059] A4 Bisphenol F type structure epoxy resin: Manufacturer: Shandong Shengquan Resin, Grade: SQE104;

[0060] A5 Bisphenol A type epoxy resin: Manufacturer: Mitsubishi, Japan, Grade: YL6810;

[0061] B1 Multifunctional phenolic resin: Manufacturer: Meiwafosis Co., Ltd., Japan, Grade: MEH7851SS;

[0062] C1 2-Methylimidazole: Manufacturer: Shikoku Kasei, Grade: 2MZ-A;

[0063] C2 Aromatic ureido derivative: Manufacturer: Mitsubishi, Japan, Grade: U-CAT 3512T;

[0064] D Fused spherical silica: Manufacturer: Jiangsu Lianrui, Grade: NQ1151F;

[0065] E1 Nitrogen-containing phenolic resin: Manufacturer: Shandong Shengquan Resin, Grade: PF8705;

[0066] E2 Aluminum hydroxide: Manufacturer: Nippon Light Metal;

[0067] F1 Carnauba wax: Manufacturer: A Tree, Grade: CARNAUBA WAX;

[0068] F2 Glyceryl Monostearate: Manufacturer: Aladdin;

[0069] G Inorganic ion scavenger: Mg6Al2(CO3)(OH) 16 4H20;

[0070] H1 coupling agent: KH560, manufacturer: Jiangsu Chenguang;

[0071] H2 coupling agent: KH550, manufacturer: Jiangsu Chenguang;

[0072] I modifier: CTBN, manufacturer: Dow Chemical, USA;

[0073] Oxidized polyethylene wax: Manufacturer: Clariant, Germany, Brand: LICOWAX PED 522.

[0074] Example A and Comparative Examples B1-B3 are used to illustrate the preparation process of the curing agent.

[0075] Example A

[0076] The preparation process of the curing agent includes:

[0077] (1) Weigh 400 g of multifunctional phenolic resin and 10 g of oxidized polyethylene wax respectively, place the multifunctional phenolic resin in a three-necked flask under the protection of nitrogen, reflux and stir to melt in a constant temperature circulator at 140°C, add the oxidized polyethylene wax after the multifunctional phenolic resin is completely liquid, and maintain the temperature for 18 hours;

[0078] (2) After the reaction is completed, the temperature is lowered to 100°C and the material is discharged. During the discharge process, a 100-mesh filter is used for filtration. The material is cooled and hardened at room temperature to prepare an oxidized polyethylene wax modified curing agent A with a viscosity of 1P.

[0079] The viscosity was tested by using a cone-plate viscometer of model CAP2000+ to test the obtained oxidized polyethylene wax modified curing agent under the conditions of 150° C. and 400 rpm.

[0080] Comparative Example B1

[0081] The multifunctional phenolic resin B1 is directly used as a curing agent. The multifunctional phenolic resin B1 does not react with the oxidized polyethylene wax and has a viscosity of 0.8P.

[0082] Comparative Example B2

[0083] The preparation process of the curing agent includes:

[0084] (1) Weigh 400 g of multi-functional phenolic resin and 10 g of polyethylene oxide wax separately. Place the multi-functional phenolic resin in a three-necked flask, reflux and stir to melt it in a constant temperature circulator at 140 °C. After the multi-functional phenolic resin has completely turned into a liquid state, add the polyethylene oxide wax and keep the temperature for reaction for 18 hours;

[0085] (2) After the reaction is completed, cool down to 100 °C and then discharge the material. During the discharging process, use a 100-mesh filter for filtration, and cool and harden it at room temperature to prepare the polyethylene oxide wax modified curing agent B2 with a viscosity of 1 P.

[0086] Comparative Example B3

[0087] Carry out the implementation according to the method of Example A. The difference is that the polyethylene oxide wax is replaced with glycerol monostearate to obtain the curing agent B3 with a viscosity of 0.9 P.

[0088] Examples 1-4 and Comparative Examples 1-3 are used to illustrate the preparation process of the epoxy encapsulant.

[0089] The raw material components of Examples 1-4 and Comparative Examples 1-3 are proportioned according to Table 1 and carried out according to the following method:

[0090] (1) Weigh each raw material component, then mix each raw material composition, and melt and knead the mixed material on an open mill with a main roll at 75 °C and a sub-roll at 85 °C for 9 min;

[0091] (2) Cool and crush the melt-kneaded material obtained in step (1), and pre-form it into a cake to obtain the epoxy encapsulant.

[0092] Table 1 Raw material ratio of Examples 1-4 and Comparative Examples 1-3

[0093]

[0094]

[0095] Test Example

[0096] (1) Surface pores: Encapsulate the sample on a QFN copper frame (258 mm × 78 mm) by transfer molding at 175 °C. After demolding, use an optical microscope to observe and test the pores.

[0097] (2) Surface imprints: Encapsulate the sample on a QFN copper frame (258 mm × 78 mm) by transfer molding at 175 °C. After demolding, visually observe and test the surface imprints.

[0098] The surface pores and surface imprints of the epoxy molding compounds prepared in Examples 1-4 and Comparative Examples 1-3 were tested, and the results are shown in Table 2.

[0099] Table 2

[0100]

[0101]

[0102] It can be seen from the test results of Examples 1-4 and Comparative Examples 1-3 that after using the modified curing agent in Examples 1-4, the pores in the package are significantly reduced and the size is very small, meeting the use standard, and the surface whitening is completely eliminated, as Figure 1 shown; in Comparative Example 1, an unmodified curing agent was used, there are many and large pores, and the surface imprint is serious and the area is large, as Figure 2 shown; in Comparative Example 2, a modified curing agent was used, but a protective atmosphere was not used during the modification process. The number and diameter of the pores were reduced, but did not reach the qualified range. The surface imprint was reduced and the area was reduced, but not completely eliminated, as Figure 3 shown.

[0103] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent transformation made using the content of the specification of the present invention, directly or indirectly applied in other related technical fields, shall be included in the patent protection scope of the present invention by the same token.

Claims

1. An oxidized polyethylene wax modified curing agent, characterized in that, The oxidized polyethylene wax modified curing agent is obtained by reacting a raw material containing oxidized polyethylene wax and phenolic resin, and the viscosity of the oxidized polyethylene wax modified curing agent is 0.5 - 5P; The preparation method of the oxidized polyethylene wax modified curing agent includes: under the condition of a protective atmosphere, melting the phenolic resin and then adding oxidized polyethylene wax for reaction; The weight ratio of the amount of the oxidized polyethylene wax to the phenolic resin is 1:20 - 100.

2. The oxidized polyethylene wax modified curing agent according to claim 1, wherein, The weight ratio of the amount of the oxidized polyethylene wax to the phenolic resin is 1:30 - 50.

3. The oxidized polyethylene wax modified curing agent according to claim 2, characterized in that, The phenolic resin is selected from one or more of multi-functional phenolic resin, linear phenolic resin, biphenyl-type phenolic resin, and XY-lock phenolic resin.

4. The oxidized polyethylene wax modified curing agent according to claim 3, wherein The melting temperature is 120 - 160 °C.

5. The oxidized polyethylene wax modified curing agent according to claim 4, characterized in that, The reaction conditions include: the temperature is 120 - 160 °C, and the time is 2 - 36 h.

6. The oxidized polyethylene wax modified curing agent according to claim 4 or 5, characterized in that, The preparation method of the oxidized polyethylene wax modified curing agent further includes filtering and cooling the product obtained by the reaction.

7. An epoxy molding compound, characterized in that, The epoxy encapsulant is made of a raw material composition containing epoxy resin, oxidized polyethylene wax modified curing agent, accelerator, inorganic filler, flame retardant, mold release agent, ion scavenger, coupling agent, modifier, and colorant, wherein, the oxidized polyethylene wax modified curing agent is the oxidized polyethylene wax modified curing agent described in any one of claims 1 - 6.

8. The epoxy molding compound according to claim 7, wherein The weight ratio of the amounts of the epoxy resin, oxidized polyethylene wax modified curing agent, accelerator, inorganic filler, flame retardant, mold release agent, ion scavenger, coupling agent, modifier, and colorant is 1:0.1 - 5:0.01 - 0.5:5 - 40:0.03 - 0.5:0.001 - 0.5:0.001 - 0.2:0.01 - 9. The epoxy molding compound according to claim 8, wherein, ​ 10. The epoxy molding compound according to any one of claims 7-9, characterized in that, ​ 11. The epoxy molding compound according to any one of claims 7-9, characterized in that, ​ 12. The epoxy molding compound according to claim 11, characterized in that, ​ ​

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