Low-warpage and high-reliability liquid epoxy molding compound, its preparation method, and applications

Abstract

This invention discloses a low-warpage and high-reliability liquid epoxy molding compound, its preparation method, and its applications. The liquid epoxy molding compound comprises the following components by weight percentage: 86%–88% inorganic filler, 6%–10% alicyclic epoxy resin monomer, 1.5%–7% silicon-epoxy hybrid resin, 0.3%–0.8% stress-relieving agent, 0.2%–0.5% cationic thermal initiator, 0.1%–0.2% first silane coupling agent, and 0.1%–0.2% colorant. The inorganic filler is silica surface-modified with a second silane coupling agent; the first silane coupling agent is a silane coupling agent containing alicyclic epoxy groups. The liquid epoxy molding compound of this application exhibits excellent flowability, warpage inhibition performance, resistance to damage, adhesion performance, and resistance to damp heat, making it suitable as an encapsulation material in 2.5D packaging.

Description

Technical Field

[0001] This application belongs to the field of electronic packaging materials technology, and specifically relates to low-warpage and high-reliability liquid epoxy molding compounds, their preparation methods, and applications. Background Technology

[0002] 2.5D packaging is an advanced heterogeneous chip packaging technology that achieves high-density circuit connections between multiple chips by introducing an interposer layer. Due to the more complex structure of 2.5D packaging, more stringent performance requirements are placed on the epoxy molding compound used as the packaging material.

[0003] Due to the relatively large size and complex structure of the interposer and substrate in 2.5D packaging, the epoxy molding compound must possess excellent flowability to ensure complete and defect-free filling. Significant warpage directly leads to a decrease in bonding yield and causes difficulties or even failures in subsequent surface mount technology (SMT) processes. Therefore, the cured epoxy molding compound should suppress warpage. Mismatch between the large-sized interposer and substrate is the primary cause of warpage. Although high-modulus epoxy molding compounds, due to their high rigidity, can effectively resist bending stress caused by mismatch, they can also easily lead to localized stress concentration, causing subsequent reliability issues. Therefore, while suppressing warpage, the epoxy molding compound should also have the ability to resist damage. In 2.5D packaging, multiple high-temperature reflow soldering processes are typically required to achieve reliable connections between the chip and the interposer, and between the interposer and the substrate. To suppress warpage at high temperatures, and especially to prevent epoxy molding compound performance failure, the epoxy molding compound should possess excellent heat resistance. Summary of the Invention

[0004] The purpose of this application is to provide a low-warpage and high-reliability liquid epoxy molding compound, its preparation method, and its application. The provided liquid epoxy molding compound is suitable as an electronic packaging material in 2.5D packaging.

[0005] The low-warpage and high-reliability liquid epoxy molding compound provided in the first aspect of this application comprises the following components by weight percentage: 86%–88% inorganic filler, 6%–10% alicyclic epoxy resin monomer, 1.5%–7% silicone-epoxy hybrid resin, 0.3%–0.8% stress-relieving agent, 0.2%–0.5% cationic thermal initiator, 0.1%–0.2% first silane coupling agent, and 0.1%–0.2% dye; wherein the inorganic filler is silica surface-modified with a second silane coupling agent; and the first silane coupling agent is a silane coupling agent containing alicyclic epoxy groups.

[0006] Optionally, the modification ratio of inorganic filler is 0.1% to 0.7%.

[0007] Optionally, the inorganic filler has an average particle size of 6µm to 8µm and a maximum particle size of no more than 28µm.

[0008] Optionally, the silicone-epoxy hybrid resin may be a cage-like siloxane silicone-epoxy hybrid resin.

[0009] Furthermore, the cage-like siloxane-silicon-epoxy hybrid resin is octafunctional.

[0010] Optionally, the cationic thermal initiator may be a hexafluoroantimonate cationic thermal initiator or a thioonium salt cationic thermal initiator.

[0011] Optionally, the first silane coupling agent is selected from 2-(3,4-epoxycyclohexyl)ethyltrimethylsiloxane or 2-(3,4-epoxycyclohexyl)ethyltriethylsiloxane.

[0012] Optionally, the second silane coupling agent is selected from silane coupling agents containing epoxy groups.

[0013] The second aspect of this application provides a method for preparing the above-mentioned liquid epoxy molding compound, comprising: mixing and dispersing the components according to the proportions, and then degassing under vacuum to obtain the liquid epoxy molding compound.

[0014] The third aspect of this application provides the application of the aforementioned liquid epoxy molding compound in 2.5D packaging.

[0015] The technical solution provided in this application may include the following beneficial effects:

[0016] The liquid epoxy molding compound of this application has excellent flowability, warpage inhibition, resistance to damage, adhesion and moisture and heat resistance, and is suitable as a packaging material in 2.5D packaging.

[0017] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0018] The above and other objects, features and advantages of this application will become more apparent from the following description of exemplary embodiments of this application in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of this application.

[0019] Figure 1 This is a schematic diagram of the warp test in an embodiment of this application;

[0020] Figure 2 This is a diagram illustrating the warpage height.

[0021] Figure 3 This is a schematic diagram of the warpage test of the epoxy molding compound in Example 5.

[0022] Figure reference numerals: 1-molding compound, 2-silicon wafer, 3-carrier board. Detailed Implementation

[0023] The following will describe this application and its technical effects in detail with reference to specific embodiments and examples. Those skilled in the art should understand that these specific embodiments and examples are for illustrative purposes only and are not intended to limit the scope of this application.

[0024] The low-warpage and high-reliability liquid epoxy molding compound provided in this application embodiment comprises the following components by mass percentage: 86%–88% inorganic filler, 6%–10% alicyclic epoxy resin monomer, 1.5%–7% silicone-epoxy hybrid resin, 0.3%–0.8% stress-relieving agent, 0.2%–0.5% cationic thermal initiator, 0.1%–0.2% first silane coupling agent, and 0.1%–0.2% dye; the inorganic filler is silica surface-modified with a second silane coupling agent; the first silane coupling agent is a silane coupling agent containing alicyclic epoxy groups.

[0025] The inorganic filler may be 86%–87% or 87%–88% by mass; the alicyclic epoxy resin monomer may be 6%–7%, 6%–9%, ​​7%–9%, ​​7%–10%, 8%–10%, or 9%–10% by mass; and the silicone-epoxy hybrid resin may be 1.5%–2%, 1.5%–4%, 1.5%–6%, 1.5%–7%, 2%–4%, 2%–6%, 2%–7%, 4%–6%, 4%–7%, or 1.8%–6.5% by mass.

[0026] Inorganic fillers are a common component of epoxy molding compounds. Currently, a common technique to reduce warpage is to increase the mass percentage of inorganic fillers, but this introduces the problem of increased viscosity. This is because inorganic fillers have poor compatibility with organic epoxy resins; increasing the mass percentage of inorganic fillers increases the difficulty of dispersing them, thus affecting the rheological properties of the epoxy molding compound. Therefore, this application selects silica surface-modified with a silane coupling agent.

[0027] Silane coupling agents contain both inorganic and organic functional groups. The inorganic functional groups bind to the silanol groups on the surface of silica particles, thereby introducing organic functional groups onto the silica particle surface. These introduced organic functional groups form active sites on the silica particle surface, which often exhibit strong compatibility and / or reactivity with organic epoxy resins. Based on steric hindrance, these active sites on the silica particle surface can prevent agglomeration between silica particles. Furthermore, by connecting the epoxy resin through these active sites, the bonding force between silica and epoxy resin is enhanced. Macroscopically, this manifests as a decrease in the viscosity and an increase in flowability of the epoxy molding compound, as well as enhanced adhesion that is less affected by thermal stress.

[0028] One possible option for surface-modified silica using a silane coupling agent is to modify the silica surface using a silane coupling agent containing epoxy groups. A suitable silane coupling agent containing epoxy groups is 3-(2,3-epoxypropoxy)propyltrimethoxysilane, whose chemical formula is shown in formula (Ⅰ), CAS number: 2530-83-8.

[0029] (I)

[0030] When silica is surface modified using a silane coupling agent of formula (I), the siloxane group of the silane coupling agent is chemically bonded to the silanol group on the surface of silica particles, thereby introducing reactive epoxy groups onto the surface of silica particles.

[0031] However, the modification ratio of silane coupling agent to silica should not be too high. If the modification ratio is too high, for example, exceeding 0.7%, it can lead to increased warpage of the molding compound and may even cause small molecules of the silane coupling agent to precipitate during the high-temperature chip packaging process, thus affecting the packing density of the chip packaging structure. Therefore, the modification ratio of inorganic filler is preferably 0.1% to 0.7%, where the modification ratio = silane coupling agent mass / (silane coupling agent mass + silica mass).

[0032] In this application, the resin matrix is ​​selected from alicyclic epoxy resin monomers. During the curing process, the alicyclic epoxy resin monomers and the curing agent undergo a cross-linking reaction to obtain an alicyclic epoxy resin polymer with a three-dimensional network structure, which tightly encapsulates the inorganic fillers and other dispersed phases to form a stable whole. Specific alicyclic epoxy resin monomers can be selected from grades such as 8010 and S-06E.

[0033] Because the epoxy groups in alicyclic epoxy resins are directly attached to the alicyclic rings, resulting in significant steric hindrance, conventional curing agents struggle to fully contact and react with the epoxy groups. Consequently, compared to other epoxy resins such as bisphenol A type epoxy resins, alicyclic epoxy resins exhibit relatively slower curing speeds. Considering these reasons, this application selects a cationic thermal initiator as the curing agent. Due to the short molecular chains, compact structure, small molecular weight, and low viscosity of alicyclic epoxy resins, the active cations and epoxy groups in the cationic thermal initiator move more readily, exhibiting higher reactivity and thus enabling rapid curing of alicyclic epoxy resins.

[0034] Alicyclic epoxy resins possess excellent heat resistance and high glass transition temperatures. Furthermore, they play a crucial role in reducing warpage. The molecular structure of alicyclic epoxy resins imparts excellent rigidity and dimensional stability to epoxy molding compounds. Compared to other epoxy resins, such as bisphenol A type epoxy resins, alicyclic epoxy resins also exhibit relatively low curing shrinkage, reducing internal stress caused by volume changes.

[0035] Cationic thermal initiators exhibit excellent latency and relative stability at room temperature. However, once the reaction temperature is reached, they rapidly initiate the cationic polymerization of epoxy resin monomers, achieving curing within a very short time, such as 30 to 60 seconds. During cationic polymerization, the cationic burst curing freezes the expanded state, resulting in extremely low shrinkage. Burst curing also significantly shortens the time window for the free movement of inorganic fillers, allowing them to maintain an initial uniform dispersion in the epoxy molding compound. This ensures the homogeneity of the cured epoxy molding compound and avoids internal stress caused by poor homogeneity. Furthermore, burst curing suppresses thermal stress accumulation and reduces the shrinkage gradient, enabling near-synchronous curing and fundamentally reducing internal stress caused by different curing sequences.

[0036] In the embodiments of this application, the cationic thermal initiator is selected from hexafluoroantimonate cationic thermal initiators or thioonium salt cationic thermal initiators, such as SAN-Aid SI-100, SAN-Aid SI-60, and SAN-Aid SI-B7 from Sanxin Chemical Co., Ltd. SAN-Aid SI-100 and SAN-Aid SI-60 are hexafluoroantimonate cationic thermal initiators, while SAN-Aid SI-B7 is a thioonium salt cationic thermal initiator. Hexafluoroantimonate cationic thermal initiators and thioonium salt cationic thermal initiators are widely used in the thermosetting and photothermal dual-curing of epoxy resins. Under heating conditions, the thermal initiator decomposes to generate cationic active species, which initiate cationic polymerization of monomers containing epoxy groups.

[0037] The molecular structure of SAN-Aid SI-100 is as follows:

[0038] (II)

[0039] The molecular structure of SAN-Aid SI-60 is as follows:

[0040] (III)

[0041] The molecular structure of SAN-Aid SI-B7 is as follows:

[0042] (IV)

[0043] The core structure of the silicon-epoxy hybrid resin is composed of a siloxane backbone and epoxy molecular chains. In the embodiments of this application, the silicon-epoxy hybrid resin selected is an octafunctional cage-like polysiloxane (POSS) silicon-epoxy hybrid resin. The molecular core of POSS is a Si-O-Si cage-like backbone, surrounded by organic groups. POSS is covalently cross-linked with epoxy molecules through the surrounding organic groups, forming a three-dimensional network hybrid structure with POSS cage-like molecules as cross-linking nodes. It combines the characteristics of cage-like polysiloxane POSS and epoxy resin.

[0044] The first silane coupling agent selected is a silane coupling agent containing alicyclic epoxy groups, also known as an alicyclic epoxy silane coupling agent, such as Nengde New Materials' SCA-E86M and SCA-E86E products. The introduction of silane coupling agents can reduce the viscosity of epoxy molding compounds and improve their adhesion to substrates such as silicon wafers. The alicyclic epoxy groups contained in the alicyclic epoxy silane coupling agent can participate in the cationic polymerization reaction of the resin matrix, thereby transforming the interfacial bonding of the coupling agent into cross-linking with the resin network, thus achieving more stable adhesion performance.

[0045] The chemical name of Nengde New Materials' SCA-E86M is 2-(3,4-epoxycyclohexyl)ethyltrimethylsiloxane, CAS number: 3388-04-3, and its molecular structure is as follows:

[0046] (V)

[0047] The chemical name of Nengde New Materials' SCA-E86E is 2-(3,4-epoxycyclohexyl)ethyltriethylsiloxane, CAS number: 10217-34-2, and its molecular structure is as follows:

[0048] (VI)

[0049] Stress relief agents can be selected from acrylic resin-based stress relief agents. Through the flexible segments in the stress relief agent, energy is absorbed and dispersed, thereby releasing stress and reducing warping.

[0050] The method for preparing the above-mentioned liquid epoxy molding compound provided in this application embodiment includes the following steps:

[0051] The first step is to add each component to the mixing cup according to the formula and use a centrifugal mixer to mix them initially. The parameters for the centrifugal mixer in this step are: revolution speed 2200-2800 r / min, rotation speed 1100-1400 r / min, and mixing time 120-180 s.

[0052] The second step is to add the pre-mixed slurry into a three-roller drum for dispersion treatment; the feed gap of the three-roller drum is set to 80-120 μm, and the discharge gap is set to 45-75 μm.

[0053] The third step involves using a centrifugal mixer to perform vacuum degassing on the dispersed slurry to obtain the liquid epoxy molding compound product of this embodiment. The parameters for vacuum degassing of the centrifugal mixer in this step are set as follows: revolution speed 1200 r / min, rotation speed 96-120 r / min, and vacuum degassing time 60-90 s.

[0054] The raw materials used in the examples and comparative examples are as follows:

[0055] Surface-modified silica: self-made;

[0056] Alicyclic epoxy resin monomer: Daicel 8010;

[0057] Bisphenol A type epoxy resin: Grade EPLC-818S;

[0058] Naphthalene-type epoxy resin: EPICLON® HP-4032D;

[0059] Silicon-epoxy hybrid resin: cage-like siloxane silicon-epoxy hybrid resin, polychemical ES 520, core size: 1.5nm, functional group density: 8 epoxy groups / molecule, hybridization mode: cage-like siloxane non-physical mixing to bridge the organic phase;

[0060] Stress relief agent: epoxy-modified acrylic resin, Nekami Kogyo Co., Ltd. EG-26R;

[0061] Cationic thermal initiators: Sanxin Chemical SAN-Aid SI-100, Sanxin Chemical SAN-Aid SI-60, Sanxin Chemical SAN-Aid SI-B7;

[0062] Coupling agents: Nengde New Materials SCA-E86M, Nengde New Materials SCA-E86E, KH-540, KH-550; among them, the main component of KH-540 is 3-aminopropyltrimethoxysilane, CAS No.: 13822-56-5; the main component of KH-550 is γ-aminopropyltriethoxysilane, CAS No.: 919-30-2;

[0063] Dyeing agent: Commercially available carbon black.

[0064] The preparation method of the surface-modified silica is as follows: Micron-sized spherical silica is vacuum-baked at 150℃ for 120 min to completely remove moisture. After the silica cools to room temperature, it is mixed with silane coupling agent KH-560 in a homogenizer at high speed for 10 min. During this process, the silane coupling agent and silica are in full contact, and the silica surface is grafted and modified. The revolution and rotation speeds of the homogenizer are set to 2600 rpm and 1300 rpm, respectively. The resulting surface-modified silica has an average particle size of 8 μm and a maximum particle size not exceeding 28 μm.

[0065] In both the examples and comparative examples, the surface-modified silica was prepared using the above method, and the modification ratio was 0.3%. The modification ratio = mass of silane coupling agent / (mass of silane coupling agent + mass of silica).

[0066] Example 1

[0067] The liquid epoxy molding compound in this embodiment comprises the following components by weight percentage: 87.0% modified silica, 10.0% alicyclic epoxy resin monomer 8010, 2.0% silicon-epoxy hybrid resin ES520, 0.5% stress-relieving agent EG-26R, 0.3% cationic thermal initiator SI-100, 0.1% silane coupling agent E86M, and 0.1% carbon black.

[0068] The preparation method of the liquid epoxy molding compound in this embodiment is as follows:

[0069] The first step is to add each component to the mixing cup according to the formula and use a centrifugal mixer to mix them initially. The parameters for the centrifugal mixer in this step are: revolution speed 2200 r / min, rotation speed 1100 r / min, and mixing time 150 s.

[0070] The second step is to add the pre-mixed slurry into a three-roller drum for dispersion treatment; the feed gap of the three-roller drum is set to 90µm and the discharge gap is set to 60µm.

[0071] The third step involves using a centrifugal mixer to perform vacuum degassing on the dispersed slurry to obtain the liquid epoxy molding compound product of this embodiment. The parameters for vacuum degassing of the centrifugal mixer in this step are set as follows: revolution speed 1200 r / min, rotation speed 120 r / min, and vacuum degassing time 90 s.

[0072] Example 2

[0073] The liquid epoxy molding compound of this embodiment comprises the following components by weight percentage: 87.0% modified silica, 8.0% alicyclic epoxy resin monomer 8010, 4.0% silicon-epoxy hybrid resin ES520, 0.5% stress-relieving agent EG-26R, 0.3% cationic thermal initiator SI-100, 0.1% silane coupling agent E86M, and 0.1% carbon black. The preparation method of the liquid epoxy molding compound of this embodiment is the same as that of Example 1.

[0074] Example 3

[0075] The liquid epoxy molding compound of this embodiment comprises the following components by weight percentage: 87.0% modified silica, 6.0% alicyclic epoxy resin monomer 8010, 6.0% silicon-epoxy hybrid resin ES520, 0.5% stress-relieving agent EG-26R, 0.3% cationic thermal initiator SI-100, 0.1% silane coupling agent E86M, and 0.1% carbon black. The preparation method of the liquid epoxy molding compound of this embodiment is the same as that of Example 1.

[0076] Example 4

[0077] The liquid epoxy molding compound of this embodiment comprises the following components by weight percentage: 86.0% modified silica, 6.5% alicyclic epoxy resin monomer 8010, 6.5% silicon-epoxy hybrid resin ES520, 0.5% stress-relieving agent EG-26R, 0.3% cationic thermal initiator SI-100, 0.1% silane coupling agent E86M, and 0.1% carbon black. The preparation method of the liquid epoxy molding compound of this embodiment is the same as that of Example 1.

[0078] Example 5

[0079] The liquid epoxy molding compound of this embodiment comprises the following components by weight percentage: 88.0% modified silica, 9.2% alicyclic epoxy resin monomer 8010, 1.8% silicon-epoxy hybrid resin ES520, 0.5% stress-relieving agent EG-26R, 0.3% cationic thermal initiator SI-100, 0.1% silane coupling agent E86M, and 0.1% carbon black. The preparation method of the liquid epoxy molding compound of this embodiment is the same as that of Example 1.

[0080] Example 6

[0081] The liquid epoxy molding compound of this embodiment comprises the following components by weight percentage: 88.0% modified silica, 9.2% alicyclic epoxy resin monomer 8010, 1.8% silicon-epoxy hybrid resin ES520, 0.5% stress-relieving agent EG-26R, 0.3% cationic thermal initiator SI-60, 0.1% silane coupling agent E86M, and 0.1% carbon black. The preparation method of the liquid epoxy molding compound of this embodiment is the same as that of Example 1.

[0082] Example 7

[0083] The liquid epoxy molding compound of this embodiment comprises the following components by weight percentage: 88.0% modified silica, 9.2% alicyclic epoxy resin monomer 8010, 1.8% silicon-epoxy hybrid resin ES520, 0.5% stress-relieving agent EG-26R, 0.3% cationic thermal initiator SI-B7, 0.1% silane coupling agent E86M, and 0.1% carbon black. The preparation method of the liquid epoxy molding compound of this embodiment is the same as that of Example 1.

[0084] Example 8

[0085] This comparative example liquid epoxy molding compound comprises the following components by mass percentage: 87.0% modified silica, 10% alicyclic epoxy resin monomer 8010, 2% silicon-epoxy hybrid resin ES520, 0.5% stress-relieving agent EG-26R, 0.3% cationic thermal initiator SI-100, 0.1% silane coupling agent E86E, and 0.1% carbon black. The preparation method of the liquid epoxy molding compound in this example is the same as in Example 1.

[0086] Comparative Example 1

[0087] This comparative example liquid epoxy molding compound comprises the following components by mass percentage: 87.0% modified silica, 12.0% alicyclic epoxy resin monomer 8010, 0.5% stress-relieving agent EG-26R, 0.3% cationic thermal initiator SI-100, 0.1% silane coupling agent E86M, and 0.1% carbon black. The preparation method of this comparative example liquid epoxy molding compound is the same as in Example 1.

[0088] Comparative Example 2

[0089] This comparative example liquid epoxy molding compound comprises the following components by weight percentage: 87.0% modified silica, 2.0% alicyclic epoxy resin monomer 8010, 10.0% silicon-epoxy hybrid resin ES520, 0.5% stress-relieving agent EG-26R, 0.3% cationic thermal initiator SI-100, 0.1% silane coupling agent E86M, and 0.1% carbon black. The preparation method of this comparative example liquid epoxy molding compound is the same as in Example 1.

[0090] Comparative Example 3

[0091] This comparative example liquid epoxy molding compound comprises the following components by weight percentage: 87.0% modified silica, 12.0% silicon-epoxy hybrid resin ES520, 0.5% stress-relieving agent EG-26R, 0.3% cationic thermal initiator SI-100, 0.1% silane coupling agent E86M, and 0.1% carbon black. The preparation method of this comparative example liquid epoxy molding compound is the same as in Example 1.

[0092] Comparative Example 4

[0093] This comparative example liquid epoxy molding compound comprises the following components by weight percentage: 84.0% modified silica, 4.0% alicyclic epoxy resin monomer 8010, 11.0% silicon-epoxy hybrid resin ES520, 0.5% stress-relieving agent EG-26R, 0.3% cationic thermal initiator SI-100, 0.1% silane coupling agent E86M, and 0.1% carbon black. The preparation method of this comparative example liquid epoxy molding compound is the same as in Example 1.

[0094] Comparative Example 5

[0095] This comparative example liquid epoxy molding compound comprises the following components by mass percentage: 87.1% modified silica, 10.0% alicyclic epoxy resin monomer 8010, 2.0% silicon-epoxy hybrid resin ES520, 0.5% stress-relieving agent EG-26R, 0.3% cationic thermal initiator SI-100, and 0.1% carbon black. The preparation method of this comparative example liquid epoxy molding compound is the same as in Example 1.

[0096] Comparative Example 6

[0097] This comparative example liquid epoxy molding compound comprises the following components by mass percentage: 87.0% modified silica, 10.0% alicyclic epoxy resin monomer 8010, 2.0% silicon-epoxy hybrid resin ES520, 0.5% stress-relieving agent EG-26R, 0.3% cationic thermal initiator SI-100, 0.1% silane coupling agent KH-540, and 0.1% carbon black. The preparation method of this comparative example liquid epoxy molding compound is the same as in Example 1.

[0098] Comparative Example 7

[0099] This comparative example liquid epoxy molding compound comprises the following components by weight percentage: 87.0% modified silica, 10.0% alicyclic epoxy resin monomer 8010, 2.0% silicon-epoxy hybrid resin ES520, 0.5% stress-relieving agent EG-26R, 0.3% cationic thermal initiator SI-100, 0.1% silane coupling agent KH-550, and 0.1% carbon black. The preparation method of this comparative example liquid epoxy molding compound is the same as in Example 1.

[0100] Comparative Example 8

[0101] This comparative example liquid epoxy molding compound comprises the following components by weight percentage: 87.0% modified silica, 10.0% bisphenol A epoxy resin 818s, 2.0% silicone-epoxy hybrid resin ES520, 0.5% stress-relieving agent EG-26R, 0.3% cationic thermal initiator SI-100, 0.1% carbon black, and 0.1% silane coupling agent E86M. The preparation method of this comparative example liquid epoxy molding compound is the same as in Example 1.

[0102] Example 9

[0103] This comparative example liquid epoxy molding compound comprises the following components by weight percentage: 87.0% modified silica, 10.0% naphthalene-type epoxy resin 4032D, 2.0% silicon-epoxy hybrid resin ES520, 0.5% stress-relieving agent EG-26R, 0.3% cationic thermal initiator SI-100, 0.1% silane coupling agent E86M, and 0.1% carbon black. The preparation method of this comparative example liquid epoxy molding compound is the same as in Example 1.

[0104] For ease of comparison, the components and mass percentages of each component in Examples 1-8 and Comparative Examples 1-9 are listed in Tables 1-2 below.

[0105] Table 1. Components and mass percentage of each component in the examples

[0106]

[0107] Table 2. Components and mass percentage of each component in the comparative example.

[0108]

[0109] Performance tests were conducted on the epoxy molding compounds of Examples 1-8 and Comparative Examples 1-9, including:

[0110] 1. Viscosity: The viscosity of epoxy molding compound was measured using a digital rotational viscometer. Test conditions: 14# rotor at 25℃, rotation speed 5r / min.

[0111] 2. Storage modulus: The epoxy molding compound was cured at 150℃ / 1h to obtain a cured sample. The storage modulus of the cured sample at 25℃ was tested using a dynamic thermomechanical analyzer.

[0112] 3. Warpage value: See Figures 1-2150g of epoxy molding compound was extruded onto a 750µm thick 12-inch silicon wafer 2, and a release film was applied. The silicon wafer 2 was then placed on a carrier plate 3 of a vacuum vulcanizing machine at a temperature of 125℃. The carrier plate 3 was kept closed, a vacuum was drawn, and hot-pressed at a pressure of 3000kN with a pressing height of 900µm. After holding the pressure for 10 minutes, the wafer 2 was removed and placed in a 150℃ vacuum drying oven for curing at 150℃ for 1 hour. After curing and cooling, the warp height of the molding compound 1 and one end of the silicon wafer 2 was measured, i.e., the warp value.

[0113] 4. Flexural Strength: This includes the flexural strength of the epoxy molding compound in the T0 state and after uHAST. Cured epoxy molding compound was prepared into strips measuring 60mm × 10mm × 2mm. The curing conditions for the epoxy molding compound were 150℃ / 1h. The flexural strength of the strips was tested using a universal testing machine. A portion of the strips was placed in a high-accelerated life testing machine (uHAST testing machine) and placed at 130℃ and 85% RH for 96h. Afterward, the strips were removed and their flexural strength was tested again using the universal testing machine. During the flexural strength test, a three-point bending mode was selected, and a loading speed of 5mm / min was applied. The strength at which the strip broke was recorded as the flexural strength.

[0114] 5. Adhesion: This includes the adhesion between the epoxy molding compound and the silicon wafer in the T0 state and after uHAST. The adhesion data after uHAST can be used to characterize the moisture and heat resistance of the epoxy molding compound. The epoxy molding compound is poured into a pudding mold with an upper diameter of 2.3 mm, a lower diameter of 3.0 mm, and a height of 2 mm. The pudding mold is placed on the silicon wafer, so the bottom of the poured epoxy molding compound is in contact with the silicon wafer. The silicon wafer is fixed to the pudding mold, and after curing at 150℃ / 1h, the cured epoxy molding compound and the silicon wafer are removed from the pudding mold. The adhesion between the cured epoxy molding compound and the silicon wafer at 25℃ is tested using a push press, i.e., the adhesion in the T0 state.

[0115] A portion of the pudding mold was placed in a high-accelerated life testing machine (uHAST tester) and placed at 130°C and 85%RH for 96 hours. Afterward, the cured epoxy molding compound was removed, and the adhesion between the cured compound and the silicon wafer at 25°C was tested using a push press. During the adhesion test, the push press speed was 50µm / s, and the contact height was 20µm.

[0116] Since the epoxy molding compound of Comparative Example 9 could not be cured, its above properties were not tested. The performance parameters of the epoxy molding compounds of Examples 1-8 and Comparative Examples 1-8 are listed in Table 3 below.

[0117] It should be noted that in Table 3, the units for viscosity are Pa·s; warpage are mm; storage modulus is GPa; flexural strength is MPa; and adhesion is MPa.

[0118] Table 3 Performance parameters of liquid epoxy molding compound

[0119]

[0120] In Table 3 above, viscosity is used to characterize the flowability of epoxy molding compounds; lower viscosity generally indicates better flowability. Storage modulus is related to mechanical strength; generally, a higher storage modulus indicates better resistance to warping. Flexural strength characterizes the epoxy molding compound's ability to resist damage. Flexural strength and tack after uHAST characterize the epoxy molding compound's resistance to damp heat; the smaller the decrease in flexural strength and tack compared to the T0 state after uHAST, the better the resistance to damp heat.

[0121] This application's liquid epoxy molding compound comprises an inorganic filler, an alicyclic epoxy resin monomer, a silicone-epoxy hybrid resin, a stress-relieving agent, a cationic thermal initiator, a first silane coupling agent, and a coloring agent; wherein the inorganic filler is silica surface-modified with a second silane coupling agent; and the first silane coupling agent is a silane coupling agent containing alicyclic epoxy groups. The alicyclic epoxy resin monomer, the silicone-epoxy hybrid resin, and the first silane coupling agent synergistically impart excellent warpage inhibition properties, resistance to damage, adhesion properties, and resistance to damp heat to the epoxy molding compound.

[0122] In this application, the inventors analyzed and believed that the following main synergistic effects exist among the alicyclic epoxy resin monomer, the silicone-epoxy hybrid resin, and the first silane coupling agent:

[0123] (1) The Si-O-Si bond in the silicon-epoxy hybrid resin itself has hydrophobic properties, and the siloxane molecular chain segment is more flexible, which helps to form an effective hydrophobic barrier inside the material system. At the same time, the rigid cyclic structure of the alicyclic epoxy resin monomer can reduce the concentration of polar groups such as hydroxyl groups, thereby reducing the inherent adsorption tendency of the material system to water molecules. Therefore, the combination of the two can reduce the hygroscopicity of the material system from both physical and chemical aspects, thereby improving the moisture resistance of the material system.

[0124] (2) The first silane coupling agent participates in the cationic polymerization reaction to form a stronger molecular bridge at the interface between the resin and the filler, which can effectively block the erosion of the interface by water vapor, thereby ensuring the bonding strength and the stability of the bonding strength.

[0125] (3) The high crosslinking density of alicyclic epoxy resins can enhance the rigidity and resistance to damp heat of the material system. The introduction of silicone-epoxy hybrid resins with cage-like structures can moderately increase the free volume of the polymer network, thereby changing the mechanical response characteristics of the cured product. Moreover, the two work together to form a dense and stable network structure that is not easily swollen by water molecules. In addition, the more flexible siloxane molecular chains in silicone-epoxy hybrid resins can reduce the internal stress of curing, reduce the generation of microcracks, and further cut off the potential channels for water vapor penetration.

[0126] The above demonstrates that the liquid epoxy molding compound of this application has excellent flowability, warpage inhibition performance, resistance to damage, adhesion performance, and resistance to damp heat, making it suitable as a packaging material in 2.5D packaging.

[0127] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A liquid epoxy plastic encapsulating material with low warpage and high reliability, characterized in that: it comprises the following components by mass percentage: inorganic filler 86-88%, alicyclic epoxy resin monomer 6-10%, silicon-epoxy hybrid resin 1.5-7%, stress release agent 0.3-0.8%, cationic thermal initiator 0.2-0.5%, first silane coupling agent 0.1-0.2%, and dyeing agent 0.1-0.2%; the inorganic filler is silica modified by a second silane coupling agent; the first silane coupling agent is a silane coupling agent containing alicyclic epoxy groups; the silicon-epoxy hybrid resin is selected from a cage silsesquioxane silicon-epoxy hybrid resin; the cage silsesquioxane silicon-epoxy hybrid resin has an octa-functionality and a product model of PolyOne ES 520; the modification ratio of the inorganic filler is 0.1-0.7%, wherein the modification ratio = mass of silane coupling agent / (mass of silane coupling agent + mass of silica); and the second silane coupling agent is selected from a silane coupling agent containing an epoxy group.

2. The liquid epoxy plastic encapsulating material of claim 1, characterized in that: the inorganic filler has an average particle size of 6-8 um and a maximum particle size of no more than 28 um.

3. The liquid epoxy plastic encapsulating material of claim 1, characterized in that: the cationic thermal initiator is selected from a hexafluoroantimonate cationic thermal initiator.

4. The liquid epoxy plastic encapsulating material of claim 1, characterized in that: the first silane coupling agent is selected from 2-(3,4-epoxycyclohexyl)ethyl trimethyl siloxane or 2-(3,4-epoxycyclohexyl)ethyl triethyl siloxane.

5. A method for preparing the liquid epoxy plastic encapsulating material of any one of claims 1-4, characterized in that: the components are mixed and dispersed according to the ratio, and then vacuum degassing is performed to obtain the liquid epoxy plastic encapsulating material.

6. Application of the liquid epoxy plastic encapsulating material of any one of claims 1-4 in 2.5D packaging. ​ ​ ​ ​ ​ ​ ​ ​

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