Chip epoxy resin composition for packaging hollow structure type electronic device

Abstract

The invention discloses a chip epoxy resin composition suitable for packaging a hollow structure type electronic device. The composite material is prepared from 55-85 parts of an inorganic filler, 0.25-0.5 part of a coupling agent, 2.7-6.3 parts of I-type epoxy resin, 4-18 parts of II-type epoxy resin, 4.5-14.2 parts of a curing agent, 0.15-0.65 part of a curing accelerator, 3-7.4 parts of thermoplastic resin and 0.15-0.5 part of a coloring agent through the processes of glue preparation, primary coating, drying, semi-curing, secondary laminating, rolling and cutting and the like. The elasticity of the sheet type epoxy resin composition is greater than the viscosity at the use temperature, namely, the physical parameter tan delta (G '' / G ', loss modulus / storage modulus) lt is 0.7 for representing the viscoelastic characteristic, and the sheet type epoxy resin composition can well inhibit flow permeability, so that the packaging requirements of hollow structure type electronic devices are met.

Description

Technical Field

[0001] This invention relates to a sheet epoxy resin composition for packaging hollow electronic devices, belonging to the field of electronic packaging materials technology, specifically to the field of epoxy molding compounds for electronic device packaging. Background Technology

[0002] In recent years, electronic devices have become increasingly thinner, smaller, more powerful, and more multifunctional, leading to significant changes in sealing resins and methods. Many semiconductors are sealed with EMC (Epoxy Molding Compound), but with the diversification of semiconductors and applications, various packaging forms and requirements have emerged, resulting in many packages that cannot be handled by conventional EMC and packaging processes. Ordinary chip packages are hermetically sealed solid packages, meaning the chip is completely sealed by the molding compound. However, for some electronic devices (chips) mounted on circuit boards, there is a need for spatial gaps or cavities, such as surface acoustic wave (SAW) filters used to remove noise from mobile phones. A filter is an important semiconductor device. The main working principle of a SAW filter is to use the piezoelectric properties of piezoelectric materials to convert the input signal of an electromagnetic wave into a mechanical wave (sound wave) using input and output transducers. After processing, the mechanical energy (sound wave) is converted into an electrical signal to filter out unwanted signals. In order to use the surface waves propagating on the piezoelectric material (piezoelectric body) to filter the desired frequency, space needs to be left between the electrodes on the piezoelectric body and the circuit board on which the SAW chip is mounted.

[0003] Therefore, while encapsulating the filter to protect it from external environmental influences, it is necessary to preserve the filter's functional areas, i.e., the cavities. Clearly, existing molding compounds used for chip packaging, whether in disc form for traditional delivery packaging or in granular or liquid form for compression packaging, all possess good flow and filling properties, requiring complete penetration into the bottom of the chip for full filling. In other words, currently available molding compounds readily infiltrate the filter device during the molding process, contaminating and damaging the filter's functional areas and cavities, thereby affecting the device's normal operation.

[0004] Currently, various complex packaging processes have been developed to achieve the hollow structure packaging of filters. For example, blocking elements are set around the functional surface of the filter chip to prevent the plastic molding material from entering and forming a closed cavity functional area. Alternatively, liquid material is first applied to the outside of the cavity by dispensing or screen printing, and then thermosetting or UV curing is used to form a dam before packaging. Another method is to cover the chip with a protective film to prevent the plastic molding material from entering the cavity structure. All of these processes are not only complex and reduce production efficiency, but also increase the packaging size of the filter. At the same time, they have high requirements for the performance of some auxiliary materials, resulting in a low yield of functionally effective filters and greatly increasing the production and manufacturing costs.

[0005] Therefore, how to provide a packaging material and process that can achieve the packaging of hollow structure electronic devices in one step, thereby improving the production efficiency of device packaging, increasing the yield of finished products, and effectively reducing production costs, is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] To address the shortcomings of the prior art, this invention provides a sheet epoxy resin composition that exhibits specific viscoelastic flowability, enabling the one-time encapsulation of hollow electronic devices.

[0007] Another objective of this invention is to provide a method for preparing a sheet epoxy resin composition for packaging hollow electronic devices.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a chip epoxy resin composition for packaging hollow electronic devices, which is made of the following components in parts by weight:

[0009] 55-85 parts of inorganic filler

[0010] 0.25-0.5 parts of coupling agent

[0011] Type I epoxy resin 2.7-6.3 parts

[0012] Type II epoxy resin 4-18 parts

[0013] Hardener 4.5-14.2 parts

[0014] Curing accelerator 0.15-0.65 parts

[0015] 3-7.4 parts thermoplastic resin

[0016] Colorant 0.15-0.5 parts

[0017] The total composition of all the above components is 100 portions.

[0018] The inorganic filler is a spherical silica powder with a special particle size distribution. The particle size distribution of this powder, measured by a laser diffraction scattering particle size analyzer (Malvin 3000), is a bimodal particle size distribution spectrum. That is, the particle size frequency / cumulative distribution curve of the powder shows two obvious peaks, corresponding to two dominant particle size ranges in the system. The particle size ranges of the two groups are significantly different, and the proportion of particles in the middle region is relatively low. Using this bimodal particle size distribution filler can, on the one hand, improve the thixotropy of the resin, thereby effectively inhibiting the resin composition from entering the cavity due to the increased fluidity caused by the decrease in viscosity under temperature and pressure conditions during the encapsulation process; on the other hand, it can achieve high-density filling, thereby adjusting the molding compound to have appropriate storage modulus, loss modulus and appropriate viscoelastic properties at the operating temperature. At the same time, the encapsulated body can obtain an appropriate coefficient of thermal expansion, ensuring the delamination reliability of the molded product.

[0019] The two peaks in the bimodal particle size distribution spectrum correspond to the first mode particle size (d) from smallest to largest. mode，1 ) and second mode particle size (d mode，2 The preferred first-mode particle size is 1-3 μm, the preferred second-mode particle size is 8-12 μm, and the preferred peak area ratio between the two is 20-30:70-80.

[0020] The coupling agent is a commonly used silane coupling agent in the art, mainly used as a surface modifier for inorganic fillers. It changes the physicochemical properties of the inorganic filler surface through chemical reaction or chemical adsorption mechanisms, improves its dispersibility in the resin, increases the compatibility between the inorganic filler and the resin interface, and thus improves the mechanical, chemical and electrical properties of the molding compound. It is preferably one or more of N-phenyl-3-aminopropyltrimethoxysilane, 3-glycidyl etheroxypropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane, without particular limitation.

[0021] The type I epoxy resin is a fluorene-based epoxy resin that is liquid at room temperature, with an epoxy equivalent of 460 g / eq. This epoxy resin has high flexibility and can give the sheet epoxy resin composition of the present invention sufficient toughness.

[0022] The type II epoxy resin is selected from one or a mixture of several of the following: bisphenol A type epoxy resin, which is liquid at room temperature; bisphenol F type epoxy resin, which is liquid at room temperature; 1,6-dihydroxynaphthalene epoxy resin, which is liquid at room temperature; tetramethylbiphenyl type epoxy resin, which is solid at room temperature; and tetramethylbisphenol F type epoxy resin, which is solid at room temperature.

[0023] From the perspective of high curing reactivity and good toughness of the prepared sheet molding compound, the curing agent is a liquid phenolic resin that is liquid at room temperature.

[0024] In one embodiment of the present invention, the curing agent comprises a liquid phenolic resin that is liquid at room temperature, and a mixture of one or more phenolic resins that are solid at room temperature.

[0025] The curing accelerator mentioned is a commonly used curing accelerator in the art. It is not particularly limited to any substance that can promote the reaction between the epoxy groups of epoxy resin and the phenolic hydroxyl groups of phenolic resin. Phosphorus compounds and their derivatives, imidazole substances, etc., can be selected as such curing accelerators. To achieve pre-curing reaction at a certain temperature to prepare sheet materials, a substance that allows the initial reaction temperature to be below 125°C is preferred, as it satisfies the requirements for preparing sheet molding materials through subsequent drying and pre-curing processes. Furthermore, to ensure that the prepared sheet molding material has certain storage stability at low temperatures, triphenylphosphine or 2-phenyl-4-methylimidazole is preferred.

[0026] To achieve good film-forming sheet material properties and control the viscoelastic characteristics of the prepared sheet encapsulation material to meet hollow encapsulation requirements, the thermoplastic resin is polyvinyl acetal resin.

[0027] The thermoplastic resin accounts for 16%-22% of the total resin, i.e., the total of thermoplastic resin, type I epoxy resin, and type II epoxy resin.

[0028] The colorant is mainly used to distinguish / identify different types of devices and to cover the design of the encapsulation unit and prevent light transmission. It may contain one or more pigments as needed and is not particularly limited. The colorant used in the composition of the present invention is specifically carbon black.

[0029] The methyl ethyl ketone (MEK) is used as a solvent to dissolve the solid resin components to form a slurry suitable for coating processes. It completely evaporates during the subsequent drying process and is ultimately not present in the prepared sheet molding compound. The amount of MEK used is reasonably adjusted according to the viscosity of the prepared slurry to meet the requirements of the preparation process, and is not particularly limited.

[0030] A chip epoxy resin composition for encapsulating hollow electronic devices, the preparation process of which is as follows: Figure 1 As shown, it includes the following steps:

[0031] (1) Weigh the epoxy resin, curing agent and thermoplastic resin that are solid at room temperature according to the formula, and add methyl ethyl ketone solvent according to the dissolution to completely dissolve the solid resin to form solution 1.

[0032] (2) Weigh out the amount of epoxy resin and curing agent that are liquid at room temperature and add them to the solution 1 formed in step (1), and mix them thoroughly to form solution 2.

[0033] (3) Weigh out the remaining materials in the formula, such as inorganic filler, coupling agent, colorant, and curing accelerator, and add them to solution 2. Use a closed double planetary mixer to fully stir and disperse the materials to form slurry 3.

[0034] (4) Apply the slurry 3 evenly to the support film (heavy release film) using a reverse roller coating machine or a comma roller coating machine. Dry it in a tunnel oven at 80-120°C for 10-20 minutes to remove the solvent. Then, use a roller laminator to apply a protective film (light release film) at 50-100°C. Roll it up and store it at -20°C for later use.

[0035] Film thickness is controlled by adjusting the gap between the coating rollers according to customer requirements. The typical thickness is 100-300μm, and no special restrictions are imposed based on customer needs.

[0036] The supporting film (release film) is not particularly required as long as it does not damage the structure of the sheet resin composition of the present invention when peeled off after curing and can be peeled off smoothly. It is preferably a transparent PET film with a thickness of 70-100μm and a release force of 80-100gf / inch for 24h.

[0037] The upper protective film (light release film) is not particularly required as long as it can be easily peeled off during use without damaging the structure of the sheet resin composition of the present invention. It is preferably a white PE film with a thickness of 35-50 μm and a release force of 10-20 gf / inch for 24 hours.

[0038] The technical difficulties in achieving this invention lie in the following two points: firstly, how to form the resin liquid onto the supporting film to create a continuous and uniform sheet-like encapsulating material; secondly, how to effectively suppress the resin composition from entering the cavity during the encapsulation process due to increased fluidity caused by decreased viscosity under temperature and pressure conditions. The inventors of this application have discovered that by introducing thermoplastic polyvinyl acetal resin with a certain molecular weight into the resin system, while ensuring the film-forming properties of the resin liquid, the resulting sheet material has greater elasticity than viscosity at the operating temperature, i.e., the physical parameter characterizing viscoelastic properties, tan δ (G” / G’, loss modulus / storage modulus), is <0.7, thereby achieving the technical objective of this invention.

[0039] Compared with the prior art, the present invention has significant technical advantages and beneficial effects: 1. The present invention can successfully coat a sheet epoxy resin composition with good thickness consistency and uniform material distribution; 2. The sheet epoxy resin composition prepared by the present invention has good toughness and strong adhesion. When the edge is cut during application, it does not break or shrink, and can adhere well to the surface of the encapsulation body; 3. The sheet material obtained by the present invention has specific viscoelastic properties at the operating temperature, with a loss tangent <0.7, which can effectively suppress flow permeability, thereby meeting the requirements for one-time encapsulation of hollow structure electronic devices. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the preparation process of the present invention.

[0041] Figure 2 The particle size distribution of silica used as filler in the embodiments of the present invention, as measured using a Malvern 3000 laser particle size analyzer, is shown.

[0042] Figure 3 The particle size distribution of silica used as filler in Comparative Example 3 of this invention, as measured using a Malvern 3000 laser particle size analyzer.

[0043] Figure 4 This is a photograph of the coating morphology of Comparative Example 4 of the present invention. Detailed Implementation

[0044] The following specific embodiments illustrate the specific implementation of the present invention. These embodiments are intended to further describe the present invention and are not intended to limit the present invention to the embodiments described herein.

[0045] <Composition of Liquid Slurry>

[0046] The following shows the composition of the substances used in the examples and comparative examples:

[0047] (Inorganic packing)

[0048] Inorganic filler 1: Spherical fused silica, Jiangsu Lianrui New Material Co., Ltd., grade NQ1165H, maximum particle size 20μm, average particle size (D50) 8.4μm measured using a Malvern 3000 laser particle size analyzer, bimodal distribution, first mode particle size 2.1μm, second mode particle size 10.3μm, peak area ratio 28:72, particle size distribution as shown below. Figure 1 As shown;

[0049] Inorganic filler 2: Spherical fused silica, Jiangsu Lianrui New Material Co., Ltd., grade NQ1110H, maximum particle size 20μm, average particle size (D50) 7.4μm measured using a Malvern 3000 laser particle size analyzer, unimodal distribution, particle size distribution as shown in the figure. Figure 2 Show.

[0050] (Coupled agent)

[0051] Coupling agent 1: 3-glycidyl etheroxypropyltrimethoxysilane, Shin-Etsu Chemical Co., Ltd., brand name KBM-403;

[0052] Coupling agent 2: 3-mercaptopropyltrimethoxysilane, Shin-Etsu Chemical Co., Ltd., brand name KBM-803;

[0053] Coupling agent 3: N-phenyl-3-aminopropyltrimethoxysilane, Shin-Etsu Chemical, Japan, brand name KBM-573.

[0054] (Type I epoxy resin)

[0055] Type I epoxy resin 1: Liquid fluorene-based epoxy resin, Osaka Gas, Japan, grade EG-280, epoxy equivalent (EEW) is 460 g / eq.

[0056] (Type II epoxy resin)

[0057] Type II epoxy resin 1: Liquid bisphenol A type epoxy resin, Anhui Xinyuan, brand name XY128L, epoxy equivalent EEW is 173g / eq;

[0058] Type II epoxy resin 2: Liquid bisphenol F type epoxy resin, Anhui Xinyuan, brand name XY170L, epoxy equivalent EEW is 155g / eq;

[0059] Type II epoxy resin 3: 1,6-dihydroxynaphthalene epoxy resin, liquid at room temperature, Anhui Xinyuan, grade XY643, epoxy equivalent EEW is 143g / eq;

[0060] Type II epoxy resin 4: Tetramethylbiphenyl epoxy resin, solid at room temperature, Anhui Xinyuan, grade XY641, epoxy equivalent EEW is 200g / eq;

[0061] Type II epoxy resin 5: Tetramethylbisphenol F type epoxy resin, solid at room temperature, Shandong Shengquan, brand name SQE-104, epoxy equivalent (EEW) is 195 g / eq.

[0062] (Curing agent)

[0063] Curing agent 1: Linear phenolic resin, solid at room temperature, Shandong Shengquan, brand name PF-8011, hydroxyl equivalent is 106g / eq;

[0064] Curing agent 2: Liquid phenolic resin, Shandong Shengquan, brand name SH-6380, hydroxyl equivalent is 145g / eq.

[0065] (Curing accelerator)

[0066] Curing accelerator 1: Triphenylphosphine, TPP;

[0067] Curing accelerator 2: 2-Phenylacetyl-4-methylimidazolium, 2P4MZ.

[0068] (Thermoplastic resin)

[0069] Thermoplastic resin 1: Polyvinyl alcohol acetal resin, Sekisui Chemicals, Japan, brand name BX-5, molecular weight 137,000;

[0070] Thermoplastic resin 2: Phenoxy resin, Mitsubishi Chemical, Japan, grade SQP-50S, molecular weight 60,000.

[0071] (Coloring agent)

[0072] Colorant 1: Carbon black, Mitsubishi, Japan, No. 5 carbon black.

[0073] <Preparation of Sheet Molding Materials>

[0074] (Examples 1-6, Comparative Examples 1-6)

[0075] The raw materials shown in Table 1 are used to prepare the chip molding compound for hollow electronic device packaging as follows:

[0076] (1) Weigh the epoxy resin, curing agent and thermoplastic resin that are solid at room temperature according to the formula, and add an equal amount of methyl ethyl ketone solvent according to the dissolution to completely dissolve the solid resin to form solution 1.

[0077] (2) Weigh out the amount of epoxy resin and curing agent that are liquid at room temperature and add them to the solution 1 formed in step (1), and mix them thoroughly to form solution 2.

[0078] (3) Weigh out the remaining materials in the formula, such as inorganic filler, coupling agent, colorant, and curing accelerator, and add them to solution 2. Use a closed double planetary mixer to fully stir and disperse the materials to form slurry 3.

[0079] (4) Apply slurry 3 evenly to a transparent PET support film (heavy release film) with a thickness of 75μm and a release force of 90gf / inch for 24h using a reverse roller coating machine or a comma roller coating machine. Dry the film in a two-stage tunnel oven at 80℃ for 10 minutes and 110℃ for 10 minutes to remove the solvent. Then, use a roller laminator to laminate a white PE protective film (light release film) with a thickness of 45μm and a centrifugal force of 15gf / inch for 2h4 at 80℃. Roll it up and store it at -20℃ for later use.

[0080] <Evaluation>

[0081] The obtained sheet epoxy resin composition was tested for the following:

[0082] (Determination of loss tangent tanδ, storage modulus, and viscosity)

[0083] The minimum viscosity of the sheet epoxy resin composition was measured using a rheometer (TA Instruments, HR10) via the parallel plate method. More specifically, the viscosity was measured at a gap of 1 mm, a parallel plate diameter of 8 mm, and a rotation speed of 5 s. -1 Measurements were performed in the range of 30℃ to 150℃ under the conditions of strain 0.05% and heating rate 10℃ / min.

[0084] The loss tangent tanδ is the ratio of the storage modulus G' to the loss modulus (G”) at the operating temperature t: G” / G'. In this invention, 65°C is selected as the operating temperature, that is, the ratio of the storage modulus G' to the loss modulus (G”) at 65°C: G” / G is selected as the loss tangent tanδ of the sheet epoxy resin composition of this invention.

[0085] The lowest values ​​of storage modulus and viscosity between 30°C and 150°C are taken as the storage modulus and viscosity of the sheet epoxy resin composition of the present invention.

[0086] (Determination of glass transition temperature Tg, linear expansion coefficient CTE1 before glass transition temperature, and linear expansion coefficient CTE2 after glass transition temperature)

[0087] The test and evaluation were conducted in accordance with the "National Standard of the People's Republic of China GB / T 40564-2021 Test Method for Epoxy Molding Compounds for Electronic Packaging".

[0088] The test results are shown in Table 1.

[0089] As can be seen from the data in Table 1, by employing the technical means of the embodiments of the present invention, the present invention can prepare a sheet epoxy resin composition with a viscoelastic loss tangent of less than 0.7 at the operating temperature (65°C), which meets the encapsulation requirements for inhibiting penetration into the hollow cavity. In contrast, Comparative Example 1, which does not employ the type I epoxy resin of the present invention, although it can form a film, the prepared film is fragile and cannot meet the requirements for use; Comparative Example 2, which does not employ the thermoplastic resin polyvinyl acetal resin of the present invention, produces a sheet epoxy resin composition with a viscoelastic loss tangent greater than 1 at the operating temperature (65°C), reaching more than 1.7, thus exhibiting good flow permeability, but it is extremely unfavorable for hollow cavity retention and cannot meet the requirements for use; Comparative Example 3, which does not employ the filler system with a bimodal distribution of the present invention, produces a sheet epoxy resin composition with high viscosity, low modulus, and large expansion coefficient under the same conditions, which cannot meet the requirements for use; Comparative Example 4, which does not employ any thermoplastic resin, cannot be directly coated to form a film, and its coating state is shown in [see figure]. Figure 4 .

[0090] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent transformations or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

[0091] Table 1

[0092] .

Claims

1. A sheet epoxy resin composition for a hollow structural electronic device package, characterized by The composition is made of the following components by weight: Inorganic filler 55-85 parts Coupling agent 0.25-0.5 parts Type I epoxy resin 2.7-6.3 parts Type II epoxy resin 4-18 parts Curing agent 4.5-14.2 parts Curing accelerator 0.15-0.65 parts Thermoplastic resin 3-7.4 parts Coloring agent 0.15-0.5 parts The total composition of all the above components is 100 parts; The inorganic filler is spherical silica powder with a special particle size distribution, and the particle size distribution measured by a laser diffraction scattering method particle size measuring device (Malvern 3000) is a bimodal particle size distribution; The bimodal particle size distribution refers to the measured particle size frequency / cumulative distribution curve showing two obvious peaks (modal peaks), and the particle sizes corresponding to the two peaks are the first mode particle size (dmode, 1) and the second mode particle size (dmode, 2) from small to large, wherein the first mode particle size is 1-3 μm, and the second mode particle size is 8-12 μm, and the peak area ratio of the two is 20-30:70-80; The type I epoxy resin is a liquid fluorene-based epoxy resin with an epoxy equivalent of 460 g / eq.

2. The sheet epoxy resin composition for a hollow structured electronic device package according to claim 1, characterized by The type II epoxy resin is one or a mixture of several selected from liquid bisphenol A type epoxy resin which is liquid at room temperature, liquid bisphenol F type epoxy resin which is liquid at room temperature, 1,6-dihydroxynaphthalene epoxy resin which is liquid at room temperature, tetramethyl diphenyl type epoxy resin which is solid at room temperature, and tetramethyl bisphenol F type epoxy resin which is solid at room temperature.

3. The sheet epoxy resin composition for a hollow structured electronic device package according to Claim 1, wherein The curing agent is a liquid type phenolic resin which is liquid at room temperature.

4. The sheet epoxy resin composition for a hollow structured electronic device package according to Claim 1, wherein The curing agent comprises a liquid type phenolic resin which is liquid at room temperature, and one or more solid type phenolic resin mixtures at room temperature.

5. The sheet epoxy resin composition for a hollow structured electronic device package according to Claim 1, wherein The thermoplastic resin is a polyvinyl acetal resin.

6. The sheet epoxy resin composition for a hollow structured electronic device package according to claim 4, wherein The proportion of the thermoplastic resin in the total resin, i.e. the total proportion of thermoplastic resin, type I epoxy resin, and type II epoxy resin, is 16%-22%.

7. The sheet epoxy resin composition for a hollow structured electronic device package according to Claim 1, wherein The preparation process of the sheet type epoxy resin composition comprises the following steps: (1) Weigh the formula amount of solid epoxy resin at room temperature, solid curing agent at room temperature, and thermoplastic resin, and add butanone solvent according to the dissolution condition to make the solid resin completely dissolved to form solution 1; (2) Weigh the formula amount of liquid type epoxy resin which is liquid at room temperature, and liquid curing agent at room temperature into solution 1 formed in step (1), and mix well to form solution 2; (3) Weigh the formula amount of the remaining materials, such as inorganic filler, coupling agent, coloring agent, and curing accelerator, into solution 2 in sequence, and use a closed double-planetary mixer to fully stir and disperse to form slurry 3; (4) Uniformly coat slurry 3 on a supporting film (heavy separation film) through a reverse roller coating machine or a comma roller coating machine, dry and remove the solvent at 80-120°C for 10-20 minutes through a tunnel type oven, then use a roller laminator to coat and adhere a protective layer film (light separation film) at 50-100°C, roll up, and store in a cold storage at-20°C or below for standby use.

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