An adhesive for semiconductor packaging and its preparation method

Abstract

This application discloses an adhesive for semiconductor packaging and its preparation method. The adhesive comprises the following raw materials in parts by weight: 100 parts epoxy resin, 1-5 parts curing agent, 0.1-1 parts accelerator, 10-20 parts silicone-modified polyurethane, 5-10 parts thermally conductive filler, 3-6 parts thickener, and 20-30 parts diluent. The silicone-modified polyurethane is prepared by hydrosilylation of an alkenyl polyurethane prepolymer and a siloxane compound in a mass ratio of 10:0.3-1. The alkenyl polyurethane prepolymer is obtained by polymerization of raw materials containing polyether polyol, alkenyl polyethylene glycol ether, and isocyanate. This application, by adding silicone polyurethane to the epoxy resin system, introduces flexible segments and forms an interpenetrating network structure, effectively compensating for the loss of flexibility in the epoxy adhesive layer and effectively solving the problem of flexibility degradation of epoxy resin encapsulants after filling with thermally conductive fillers.

Description

Technical Field

[0001] This application relates to the field of semiconductor packaging, and in particular to an adhesive for semiconductor packaging and a method for preparing the same. Background Technology

[0002] With the rapid development of power semiconductor devices and highly integrated chips, the power consumption per unit area of ​​chips continues to rise, and heat dissipation has become a key factor restricting the reliability and lifespan of devices. In existing packaging processes, adhesives are typically used to bond the chip to a heat sink or metal substrate, transferring internal heat to the external heat dissipation structure through interfacial heat transfer. Epoxy resin-based adhesives have become the mainstream packaging material due to their excellent bonding strength, electrical insulation, and process adaptability. However, the thermal conductivity of pure epoxy resin is relatively low, making it difficult to meet the heat dissipation requirements of high power density devices. To improve thermal conductivity, the industry generally adds highly thermally conductive inorganic fillers to adhesives, thereby improving the thermal conductivity by constructing a filler thermally conductive network.

[0003] However, the addition of fillers significantly increases the hardness of the adhesive system while drastically reducing its flexibility. Epoxy resin itself has a relatively rigid molecular chain, exhibiting significant brittleness after the glass transition. The introduction of a large amount of rigid filler further restricts molecular chain movement, resulting in a cured adhesive layer with low elongation at break and high flexural modulus. Such high-modulus materials are prone to interfacial stress concentration under temperature cycling or mechanical vibration, leading to delamination or cracking between the chip and the heat dissipation substrate, especially damaging to heterogeneous material interfaces with mismatched coefficients of thermal expansion (CTE) (such as silicon chip-copper substrate). Furthermore, in flexible electronics or wearable devices, the encapsulating adhesive needs to withstand repeated bending; the brittleness of existing highly filled epoxy adhesives will directly lead to fatigue failure. Summary of the Invention

[0004] To address the issue of reduced flexibility in epoxy resin encapsulants after the addition of thermally conductive fillers, this application provides an adhesive for semiconductor encapsulation and its preparation method. By adding organosilicon polyurethane to the epoxy resin system, flexible segments are introduced and an interpenetrating network is formed, effectively compensating for the loss of flexibility in the epoxy adhesive layer.

[0005] In a first aspect, this application provides an adhesive for semiconductor packaging, comprising the following raw materials in parts by weight: 100 parts epoxy resin, 40-60 parts curing agent, 0.1-1 parts accelerator, 10-20 parts silicone-modified polyurethane, 5-10 parts thermally conductive filler, 3-6 parts thickener, and 20-30 parts diluent; wherein the silicone-modified polyurethane is prepared by hydrosilylation of an alkenyl polyurethane prepolymer and a siloxane compound in a mass ratio of 10:0.3-1, and the alkenyl polyurethane prepolymer is obtained by polymerization of raw materials comprising polyether polyol, alkenyl polyethylene glycol ether and isocyanate.

[0006] In any of the above technical solutions, the mass ratio of the polyether polyol, the alkenyl polyethylene glycol ether and the isocyanate is 1:(0.2-0.4):(0.3-0.6) by mass parts.

[0007] In any of the above technical solutions, the alkenyl polyethylene glycol ether is selected from at least one of allyl polyethylene glycol ether (APEG), isobutylene polyethylene glycol ether (HPEG), and isopentenyl polyethylene glycol (TPEG).

[0008] In any of the above technical solutions, the molecular weight of the alkenyl polyethylene glycol ether is 400 to 1000.

[0009] In any of the above technical solutions, the silanol-containing siloxane compound is selected from one or more of trimethoxysilane, triethoxysilane, methyldimethoxysilane and ethyldimethoxysilane.

[0010] In any of the above technical solutions, the hydrosilylation of the alkenyl polyurethane prepolymer with the siloxane compound is carried out under a platinum catalyst.

[0011] In any of the above technical solutions, the polymerization of polyether polyol, alkenyl polyethylene glycol ether and isocyanate to prepare alkenyl polyurethane prepolymer is carried out under an organotin catalyst.

[0012] This application introduces alkenyl polyethylene glycol ethers into the synthesis of polyurethane prepolymers, endowing the prepolymer side chains with alkenyl active groups. These alkenyl groups react with silanol-containing siloxane compounds via hydrosilylation, grafting organosilicon segments onto the polyurethane backbone to form an organosilicon-modified polyurethane rich in siloxane groups. This design achieves both flexibility compensation and adhesive reinforcement.

[0013] Specifically, the high flexibility of the organosilicon segments and the elastic synergy of the polyether polyols can significantly improve the toughness of the adhesive layer. When this modified polyurethane is blended with epoxy resin, the two form an interpenetrating network structure. The flexible organosilicon segments are dispersed in the rigid epoxy network, absorbing stress through molecular chain slippage, increasing elongation at break, and effectively suppressing the risk of interfacial delamination caused by temperature cycling or mechanical vibration. Secondly, the siloxane groups can hydrolyze to generate silanol groups during the curing process, forming hydrogen bonds or chemical bonds with the metal oxides on the surface of the adhered material (such as chips or copper substrates), improving the interfacial adhesion strength. Compared with traditional methods of modifying polyurethane with silane coupling agents or silane crosslinking agents, this application can introduce active siloxane groups into the polyurethane segments to achieve an enhanced interfacial bonding effect.

[0014] In any of the above technical solutions, the polyether polyol is at least one of polyether diol, polyether triol and polyether tetraol; preferably, the polyether polyol is a composition of polyether triol and polyether diol in a mass ratio of 3 to 5:1.

[0015] In any of the above technical solutions, the curing agent is an acid anhydride-based curing agent.

[0016] In any of the above technical solutions, the thickener is selected from one or more of organobentonite, silica, cellulose derivatives, and polyvinyl alcohol.

[0017] In any of the above technical solutions, the thickener includes low oil-absorbing silica with an oil absorption value of 1.4 to 2.3 mL / g and high oil-absorbing silica with an oil absorption value of 2.7 to 3.5 mL / g, wherein the low oil-absorbing silica accounts for 30 to 50 wt%.

[0018] The thickener in this application is a blend of low-oil-absorption and high-oil-absorption silica, which achieves a balance between anti-overflow, anti-settling, and application flowability through synergistic effects. The high-oil-absorption silica has densely packed hydroxyl groups on its surface, which easily form a hydrogen bond network in solvents, providing strong support. On the one hand, this prevents the adhesive from overflowing out of the encapsulation area during coating, contaminating chips and other components, and potentially causing poor adhesion; on the other hand, it inhibits the settling of thermally conductive fillers.

[0019] It should be noted that under the shear force of spraying or dispensing, the hydrogen bond network temporarily dissociates, causing the adhesive viscosity to drop sharply, ensuring smooth application; after the external force is removed, the network recovers to prevent sagging.

[0020] It is worth noting that single high oil absorption fillers are prone to solvation in solvent systems, leading to a loosening of the hydrogen bond network and a decrease in stability. Adding low oil absorption silica can reduce solvent sensitivity and enhance network structural stability. Furthermore, the siloxane groups in silicone-modified polyurethane can further strengthen the network. The silanol groups generated by hydrolysis form additional hydrogen bonds with the hydroxyl groups on the silica surface and entangle with the silicone segments, forming an inorganic-organic hybrid network. This significantly improves resistance to solvent attack, enhances network stability, and provides long-term suppression of compound overflow and sedimentation.

[0021] In any of the above technical solutions, the oil absorption value of the silica is measured in accordance with the specifications of ASTM D6854-15a.

[0022] In any of the above technical solutions, the thermally conductive filler is selected from one or more of boron nitride, aluminum nitride, aluminum oxide, and zinc oxide.

[0023] In any of the above technical solutions, the D50 particle size of the thermally conductive filler is 1-100 μm, preferably 20-60 μm.

[0024] In any of the above technical solutions, the diluent is selected from at least one of ethanol, isopropanol, ethyl acetate, butyl acetate, acetone, and toluene.

[0025] In any of the above technical solutions, the accelerator is selected from one or more of tertiary amine accelerators, imidazole accelerators, and quaternary ammonium salt accelerators.

[0026] The adhesive raw materials of this application may be supplemented with other additives such as dispersants, tackifiers, leveling agents, defoamers, and coupling agents as needed.

[0027] Secondly, this application provides a method for preparing an adhesive for semiconductor packaging, which involves adding epoxy resin, silicone-modified polyurethane, thermally conductive filler, and thickener to a diluent and mixing them, then adding a curing agent and an accelerator, and stirring to obtain the final product.

[0028] In summary, this application has the following beneficial effects:

[0029] The semiconductor encapsulation adhesive of this application utilizes an interpenetrating network constructed from silicone-modified polyurethane and epoxy resin. While maintaining high thermal conductivity, it reduces the flexural modulus to <800 MPa and increases the elongation at break to >30%, effectively solving the brittleness problem of highly filled epoxy adhesives. A silica thickening system, combined with the siloxane groups of the silicone polyurethane, constructs an inorganic-organic hybrid network, preventing filler sedimentation and adhesive overflow while ensuring smooth application. Furthermore, the siloxane groups in the silicone-modified polyurethane enhance interfacial adhesion strength through interfacial bonding, reducing the risk of failure due to thermal stress. Detailed Implementation

[0030] Preparation Example

[0031] Preparation Example 1

[0032] Organosilicon-modified polyurethane is prepared according to the following steps:

[0033] Reactant materials: 800g polyether triol (Mn = 5000g / mol), 200g polyether diol (Mn = 2000g / mol), 300g allyl polyethylene glycol ether (APEG-1000, Mn = 1000g / mol), 450g isophorone diisocyanate, 60g trimethoxysilane, and 3g dibutyltin dilaurate (catalyst).

[0034] S1. Polyether diol and polyether triol were dehydrated at 110℃ and -0.1MPa for 1 hour, then cooled to 60℃ and added to a reaction vessel. Nitrogen gas was introduced to purge the air from the vessel. Isophorone diisocyanate was added, and the temperature was controlled at 60±2℃. The mixture was stirred and reacted for 1 hour. Dibutyltin dilaurate was added, and the reaction was continued for 2 hours. Finally, allyl polyethylene glycol ether was added, and the reaction was continued at 60±2℃ for 2 hours to obtain an alkenyl-containing polyurethane prepolymer.

[0035] S2. Take 1000g of alkenyl-containing polyurethane prepolymer and 60g of trimethoxysilane and stir to mix well to obtain a premix; add 20ppm of caster platinum catalyst (calculated as Pt) by mass of the premix, react at 80℃ under nitrogen protection for 6h, after the reaction is completed, cool to 40℃, vacuum at -0.08MPa for 2h to remove unreacted silane, and obtain organosilicon modified polyurethane.

[0036] Preparation Example 2

[0037] Organosilicon-modified polyurethane is prepared according to the following steps:

[0038] Reactant materials: 750g polyether triol (Mn = 3000g / mol), 250g polyether diol (Mn = 1000g / mol), 200g isobutylene polyethylene glycol ether (Mn = 1000g / mol), 300g toluene diisocyanate, 30g methyl dimethoxysilane, and 2g dibutyltin dilaurate (catalyst).

[0039] S1. Polyether diol and polyether triol were dehydrated at 110℃ and -0.1MPa for 1 hour, then cooled to 50℃ and added to a reaction vessel. Nitrogen gas was introduced to purge the air from the vessel. Toluene diisocyanate was added, and the temperature was controlled at 55±2℃. The mixture was stirred and reacted for 1.5 hours. Dibutyltin dilaurate was added, and the reaction was continued for 1.5 hours. Finally, isobutylene polyethylene glycol ether was added, and the reaction was continued at 55±2℃ for 2 hours to obtain an alkenyl-containing polyurethane prepolymer.

[0040] S2. Take 1000g of alkenyl-containing polyurethane prepolymer and 30g of methyldimethoxysilane and stir to mix well to obtain a premix; add 15ppm of caster platinum catalyst (calculated as Pt) by mass of the premix, react at 70℃ under nitrogen protection for 5h, after the reaction is completed, cool to 40℃, and vacuum at -0.08MPa for 1h to remove unreacted silane to obtain organosilicon modified polyurethane.

[0041] Preparation Example 3

[0042] Organosilicon-modified polyurethane is prepared according to the following steps:

[0043] Reactant materials: 1000g polyether triol (Mn = 6000g / mol), 400g allyl polyethylene glycol ether (Mn = 800g / mol), 600g hexamethylene diisocyanate, 120g triethoxysilane, and 6g dibutyltin dilaurate (catalyst).

[0044] S1. Polyether triol was dehydrated at 110℃ and -0.1MPa for 1 hour, then cooled to 70℃ and added to a reaction vessel. Nitrogen gas was introduced to purge air from the vessel. Hexamethylene diisocyanate was added, and the temperature was controlled at 75±2℃. The mixture was stirred for 1 hour. Dibutyltin dilaurate was added, and the reaction was continued for 1.5 hours. Finally, allyl polyethylene glycol ether was added, and the reaction was continued at 75±2℃ for 4 hours to obtain an alkenyl-containing polyurethane prepolymer.

[0045] S2. Take 1000g of alkenyl-containing polyurethane prepolymer and 120g of triethoxysilane and stir to mix well to obtain a premix; add 30ppm of caster platinum catalyst (calculated as Pt) by mass of the premix, react at 80℃ under nitrogen protection for 4h, after the reaction is completed, cool to 40℃, evacuate at -0.1MPa for 2h to remove unreacted silane, and obtain organosilicon modified polyurethane.

[0046] Preparation Example 4

[0047] The silicone-modified polyurethane differs from that in Preparation Example 1 in that an equal amount of polyether diol is used instead of allyl polyethylene glycol ether.

[0048] Preparation Example 5

[0049] The modified polyurethane differs from that in Preparation Example 1 in that step S2 is omitted, and the alkenyl-containing polyurethane prepolymer obtained in step S1 is the final product.

[0050] Preparation Example 6

[0051] The silicone-modified polyurethane differs from Preparation Example 1 in that an equal amount of hydrogen-containing silicone oil (RH-H45) is used instead of trimethoxysilane.

[0052] Example

[0053] Example 1: An adhesive for semiconductor packaging is prepared according to the following steps:

[0054] Weigh out 1000g of epoxy resin (E-44), 150g of the silicone-modified polyurethane of Preparation Example 1, 80g of spherical alumina (D50 = 30 micrometers), and 20g of low oil-absorbing silica (oil absorption value 1.4–1.6 mL / g, Yosica). TM Add 505), 30g of highly oil-absorbing silica (oil absorption value 2.95mL / g, Evonik OK-520), and 15g of dispersant (Tego Dispers 673) to 260g of ethyl acetate and stir at 500rpm for 30min. Then add 500g of methyltetrahydrophthalic anhydride and 6g of DMP-30 and stir for 10min to obtain the final product.

[0055] Example 2: An adhesive for semiconductor packaging is prepared according to the following steps:

[0056] Weigh out 1000g of epoxy resin (E-44), 100g of the silicone-modified polyurethane from Preparation Example 2, 80g of spherical alumina (D50 = 30 micrometers), and 10g of low-oil-absorbing silica (oil absorption value 1.4–1.6 mL / g, Yosica). TM Add 505), 20g of high oil-absorbing silica (oil absorption value 2.7mL / g, Evonik OK-500), and 10g of dispersant (Tego Dispers 673) to 200g of ethyl acetate and stir at 500rpm for 30min. Then add 400g of methyl nadic anhydride and 3g of DMP-30 and stir for 10min to obtain the final product.

[0057] Example 3: An adhesive for semiconductor packaging is prepared according to the following steps:

[0058] Weigh 1000g of epoxy resin (DER 383), 200g of silicone-modified polyurethane from Preparation Example 3, 50g of spherical alumina (D50 = 30 μm), 50g of zinc oxide (D50 = 20 μm), 30g of low oil-absorbing silica (oil absorption value 2.3 mL / g, Evonik OK-412), 30g of high oil-absorbing silica (oil absorption value 2.8–3.5 mL / g, Jiejia JJ-150), and 20g of dispersant (TegoDispers 673). Add these to 300g of toluene and stir at 500 rpm for 40 min. Then add 600g of methylnadic anhydride and 10g of DMP-30 and stir for 10 min to obtain the final product.

[0059] Example 4, an adhesive for semiconductor packaging, differs from Example 1 in that it uses an equal amount of low-oil-absorbing silica (oil absorption value 1.4-1.6 mL / g, Yosica) TM Replace the high oil-absorbing silica (oil absorption value 2.95mL / g, Evonik OK-520) with 505.

[0060] Example 5: An adhesive for semiconductor packaging, differing from Example 1 in that an equal amount of high-oil-absorbing silica (oil absorption value 2.95 mL / g, Evonik OK-520) is used instead of low-oil-absorbing silica (oil absorption value 1.4–1.6 mL / g, Yosica). TM 505).

[0061] Example 6: An adhesive for semiconductor packaging, differing from Example 1 in that an equal amount of silicone dioxide (Evonik OK-412) with an oil absorption value of 2.3 mL / g is used instead of low-oil-absorbing silicone dioxide (oil absorption value 1.4–1.6 mL / g, Yosica). TM 505).

[0062] Example 7, an adhesive for semiconductor packaging, differs from Example 1 in that an equal amount of silica with an oil absorption value of 2.3 mL / g (Evonik OK-412) is used instead of high oil absorption silica (Evonik OK-520 with an oil absorption value of 2.95 mL / g).

[0063] Example 8, an adhesive for semiconductor packaging, differs from Example 1 in that an equal amount of ethyl cellulose (degree of substitution 2.3 to 2.6) is used to replace low-oil-absorbing silica and high-oil-absorbing silica.

[0064] Comparative Example

[0065] Comparative Example 1 is an adhesive for semiconductor packaging, which differs from Example 8 in that the silicone-modified polyurethane of Preparation Example 4 is used instead of the silicone-modified polyurethane of Preparation Example 1.

[0066] Comparative Example 2 is an adhesive for semiconductor packaging, which differs from Example 8 in that the modified polyurethane of Preparation Example 5 is used instead of the silicone-modified polyurethane of Preparation Example 1.

[0067] Comparative Example 3 is an adhesive for semiconductor packaging, which differs from Example 8 in that the silicone-modified polyurethane of Preparation Example 6 is used instead of the silicone-modified polyurethane of Preparation Example 1.

[0068] Performance testing

[0069] Experiment 1: Elongation at break test

[0070] Reference standard: GB / T 1040.2-2006 "Determination of tensile properties of plastics - Part 2: Test conditions for molded and extruded plastics".

[0071] Test method: Apply adhesive to a polytetrafluoroethylene (PTFE) sheet, controlling the thickness to 0.5 ± 0.05 mm, and cure completely under the curing conditions (120℃ / 1h + 150℃ / 2h). Cut the cured sample into dumbbell-shaped pieces (total length 75 mm, gauge length 25 × 6 × 0.5 mm). 3 Using a universal testing machine with a clamp spacing of 50 mm, a tensile speed of 10 mm / min, an ambient temperature of 23±2℃, and a humidity of 50±5%, the elongation at fracture ΔL was recorded, and the elongation at fracture was calculated as: Elongation at fracture = (ΔL / 25) × 100%.

[0072] Experiment 2: Flexural Modulus Test

[0073] Reference standard: GB / T 9341-2008 "Determination of bending properties of plastics".

[0074] Test method: Adhesive injection into mold (80×10×4mm) 3The curing conditions are the same as for the tensile specimen. Polishing removes burrs to ensure a smooth surface. A three-point bending device is used, with a span of 64 mm, an indenter radius of 5 mm, and a loading speed of 2 mm / min. The slope of the linear segment of the stress-strain curve is recorded, and the flexural modulus is calculated.

[0075] Flexural modulus = (F × L) 3 ) / (4×b×h 3 ×d)

[0076] Where F: load, L: span, b: width, h: thickness, d: deflection.

[0077] Experiment 3: Adhesion Test

[0078] Reference standard: GB / T 7124-2008 Determination of tensile shear strength of adhesives.

[0079] Test method: The sample substrate is a silicon chip (10×10×0.5mm). 3 ) and copper substrate (40×10×1mm) 3 Adhesive layer thickness: 0.1 mm; Curing conditions: 120℃ / 1h + 150℃ / 2h; Bonding area: 10×10 mm 2 A universal testing machine was used to clamp both ends of a copper substrate. The tensile speed was 5 mm / min, and the maximum breaking load F was recorded. The tensile shear strength was calculated as follows: Tensile shear strength = F / 100 mm. 2 (Unit: MPa)

[0080] Test 4: Anti-adhesive performance test

[0081] Test method: Load the adhesive into a dispensing syringe (1mm diameter nozzle) and let it stand at 25℃ for 24 hours. Apply the adhesive to the surface of the silicon chip (10×10×0.5mm) using a dispensing machine. 3 Dispensing machine parameters: air pressure 0.3MPa, dispensing volume 0.5g. Immediately after dispensing, cover with a copper sheet (10×10×1mm). 3 Apply a pressure of 0.2 MPa for 10 seconds; observe the width of the adhesive overflowing from the silicon chip under a microscope and classify it according to the following criteria: no adhesive overflow (0 mm), slight adhesive overflow (<0.5 mm), and severe adhesive overflow (≥0.5 mm).

[0082] Experiment 5: Anti-settlement performance test.

[0083] Test method: Fill a transparent glass tube (Φ25×150mm) with adhesive to a height of 100mm. Let it stand vertically at 40℃ for 72 hours; measure the height of the top clarification layer H1 and the total height H2; calculate the settling rate = [(H2-H1) / H2]×100%.

[0084] Experiment 6: Construction fluidity test

[0085] Reference standard: GB / T 2794-2013 "Determination of viscosity of adhesives".

[0086] Test method: The adhesive was kept at 25℃ for 1 hour. The static viscosity η0 was measured at 0.5 rpm using a rotational viscometer (rotor model LV-4). The dynamic viscosity η1 was measured by shearing at 50 rpm for 1 minute.

[0087] Table 1 Performance Test Results

[0088]

[0089] Analysis of experimental results:

[0090] 1. Analysis of Elongation at Break and Flexural Modulus

[0091] The elongation at break of Examples 1-3 was significantly higher than that of Comparative Examples 1-3, while the flexural modulus was much lower, indicating that Examples 1-3 were superior to the Comparative Examples in terms of flexibility. This may be because the organosilicon-modified polyurethane (containing siloxane groups) forms an interpenetrating network structure with the epoxy resin, which, combined with the flexible organosilicon segments, absorbs stress, forming a flexible compensation mechanism. In contrast, Comparative Example 1 (without the introduction of alkenyl groups, thus unable to graft organosilicon segments); Comparative Example 2 (without hydrosilylation, thus not grafted organosilicon segments) lacked flexible segments, resulting in deteriorated flexibility; and Comparative Example 3 (grafted with organosilicon segments without siloxane groups) lacked silanol groups bonded to the substrate, leading to deteriorated tensile shear strength.

[0092] 2. Tensile shear strength analysis

[0093] Compared to Comparative Examples 1-3: In Examples 1-3, the hydrolysis of siloxane groups generates -Si-OH, which can bond with metal oxides on the substrate surface (hydrogen bonds / chemical bonds), enhancing the interfacial bonding strength. In contrast, the comparative examples lack active siloxane groups, resulting in weak interfacial bonding. Furthermore, as shown in Comparative Example 3 (which involved addition with hydrogen-containing silicone oil), grafting organosilicon segments without active siloxane groups can actually decrease interfacial adhesion strength due to factors such as surface energy.

[0094] 3. Analysis of anti-overflow adhesive and sedimentation performance

[0095] Anti-overflow: The test results show that Examples 1-3 (high oil absorption value gradient compounded SiO2 system) had no overflow, Examples 4-5 (single oil absorption value SiO2 system) had slight overflow, Examples 6-7 (low oil absorption value gradient compounded SiO2 system) had slight overflow, and Example 8 (ethyl cellulose) had severe overflow. This may be because the high and low oil absorption value SiO2 compounded systems can construct a stable and difficult-to-dissociate "inorganic-organic hybrid network" under static conditions, reducing the fluidity of the adhesive and suppressing overflow. In contrast, the networks of single oil absorption value SiO2, low oil absorption value gradient compounded SiO2, or ethyl cellulose (Example 8) lack sufficient stability and are prone to dissociation.

[0096] Settling properties: Its performance and mechanism are the same as those of anti-overflow adhesive properties.

[0097] 4. Construction fluidity (thixotropic index) analysis

[0098] The thixotropic index of the high and low oil absorption SiO2 compound (Examples 1-3) is ≥4.0, indicating that the high static viscosity prevents sagging and the low dynamic viscosity is beneficial for construction. The single SiO2 (Examples 4-5), the low oil absorption gradient compound SiO2 (Examples 6-7) and ethyl cellulose (Example 8) have poor thixotropy and poor construction performance.

[0099] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. An adhesive for semiconductor packaging, characterized in that, The raw materials comprise the following parts by weight: 100 parts epoxy resin, 40-60 parts curing agent, 0.1-1 parts accelerator, 10-20 parts silicone-modified polyurethane, 5-10 parts thermally conductive filler, 3-6 parts thickener, and 20-30 parts diluent; the silicone-modified polyurethane is prepared by hydrosilylation of an alkenyl polyurethane prepolymer and a siloxane compound containing silane in a mass ratio of 10:0.3-1, wherein the alkenyl polyurethane prepolymer is composed of polyether polyurethane... The mixture is obtained by polymerizing raw materials such as glycols, alkenyl polyethylene glycol ethers, and isocyanates; the silanol-containing siloxane compound is selected from one or more of trimethoxysilane, triethoxysilane, methyldimethoxysilane, and ethyldimethoxysilane; the thickener includes low oil-absorbing silica with an oil absorption value of 1.4-2.3 mL / g and high oil-absorbing silica with an oil absorption value of 2.7-3.5 mL / g, wherein the low oil-absorbing silica accounts for 30-50 wt%.

2. The adhesive according to claim 1, characterized in that, The mass ratio of the polyether polyol, alkenyl polyethylene glycol ether and isocyanate is 1:(0.2-0.4):(0.3-0.6) by mass.

3. The adhesive according to claim 1, characterized in that, The alkenyl polyethylene glycol ether is selected from at least one of allyl polyethylene glycol ether, isobutylene polyethylene glycol ether, and isopentenyl polyethylene glycol ether.

4. The adhesive according to claim 1, characterized in that, The polyether polyol is a composition of polyether triol and polyether diol in a mass ratio of 3 to 5:

1.

5. The adhesive according to claim 1, characterized in that, The thickener is selected from one or more of organobentonite, silica, cellulose derivatives, and polyvinyl alcohol.

6. The adhesive according to claim 1, characterized in that, The thermally conductive filler is selected from one or more of boron nitride, aluminum nitride, aluminum oxide, and zinc oxide.

7. The adhesive according to claim 1, characterized in that, The D50 particle size of the thermally conductive filler is 1–100 μm.

8. A method for preparing an adhesive for semiconductor packaging, characterized in that, According to the raw material ratio of the adhesive according to any one of claims 1 to 7, epoxy resin, silicone-modified polyurethane, thermally conductive filler, and thickener are added to a diluent and mixed evenly, and then a curing agent and an accelerator are added and stirred to obtain the adhesive.

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