A semi-solid encapsulation particle containing bamboo charcoal filler, its preparation method and application

Abstract

This application discloses a semi-solid encapsulation particle containing bamboo charcoal filler. The semi-solid encapsulation particle comprises the following components by weight: A. 80-120 parts epoxy resin; B. 150-250 parts modified bamboo charcoal; C. 3-7 parts curing agent. In this solution, modified bamboo charcoal replaces the silica filler in the prior art. Due to the honeycomb-like porous microstructure of bamboo charcoal, the migration path of external pollutant ions into the chip inside the encapsulation layer is significantly increased due to the tortuous channels, improving the environmental protection performance of the encapsulation chip material. Furthermore, through the synergistic effect between epoxy resin and modified bamboo charcoal, the epoxy resin forms multiple micro-curing pillars within the pores of the modified bamboo charcoal, thereby generating strong mechanical locking force and shear strength of the encapsulation material. This not only effectively alleviates the thermal expansion coefficient mismatch stress between the chip and the encapsulation material but also solves the technical problem of encapsulation layer cracking.

Description

Technical Field

[0001] This application relates to the field of electronic packaging materials technology, and in particular to a semi-solid packaging particle containing bamboo charcoal filler, its preparation method and application. Background Technology

[0002] The packaging of semiconductor wafers (such as pressure sensor LED arrays, consumer electronics chips, BGAs, QFPs, etc.) mainly involves sealing the bare semiconductor chip with epoxy molding compound (EMC) to achieve electrical interconnection, structural fixation, and environmental protection. Currently, the epoxy molding compound used in the packaging process is generally prepared from epoxy resin, silica, and a curing agent. Furthermore, according to patent document CN201110274708.2, existing epoxy molding compounds commonly use a large amount of silica as the main raw material to reduce the coefficient of thermal expansion (CTE) of the epoxy resin. While this effectively increases the modulus of the epoxy molding compound, the dense and non-porous rigid particles of silica cause the following technical problems with the packaged semiconductor wafer:

[0003] Question 1: In existing technologies, chips encapsulated with epoxy molding compounds rely primarily on the chemical purification of silica and the high purity of the epoxy resin itself to protect against external ion migration. While this method can suppress the migration of some ions generated during chip encapsulation, a large number of contaminating ions (Na+) from the external environment (such as flux residues and atmospheric pollutants) still enter the chip during subsequent assembly and use. + K + Cl - Driven by electric fields and temperature and humidity, these substances will rapidly diffuse to the chip along the relatively straight transport path between silicon dioxide and epoxy resin, affecting the normal use of the packaged chip and causing technical problems such as poor environmental protection of the packaged chip.

[0004] Question 2: In existing technologies, silicon dioxide is added to increase the modulus of the packaging material, but this also increases the brittleness of the packaging material. When the packaged chip is in use, it is affected by temperature cycling (the chip heats up when it is working and cools down when it stops). The stress generated between the high-modulus packaging material and the chip increases, which in turn increases the risk of cracking of the packaging layer and leads to technical problems such as chip failure.

[0005] Question 3: Existing technologies use a large amount of silica as a filler, which not only results in high costs, but also makes it difficult to recycle the silica residue generated during the molding process, thus causing environmental pollution.

[0006] Based on this, the present invention designs a semi-solid encapsulation particle containing bamboo charcoal filler, its preparation method and application, in order to solve the above problems. Summary of the Invention

[0007] The issues to be addressed

[0008] This application aims to address at least one of the technical problems existing in the prior art. Therefore, one objective of this application is to provide a semi-solid encapsulation particle containing bamboo charcoal filler, its preparation method, and its application, to better improve the environmental protection, structural stability, and cost-effectiveness of encapsulation materials.

[0009] [Methods for Solving the Problem]

[0010] In related technologies, such as CN201110274708.2, the existing packaging materials contain excessive amounts of silicon dioxide, yet still suffer from the following drawbacks:

[0011] First, although existing technologies reduce the coefficient of thermal expansion of epoxy resin by adding silica, silica itself is a rigid particle with a dense and non-porous structure. Therefore, under the drive of electric field and temperature and humidity, pollutant ions in the external environment will rapidly diffuse to the chip along the relatively straight and less obstructed path between silica and epoxy resin, and accumulate in the sensitive chip pad area, thus affecting the normal use of the packaged chip. This results in the technical problem of poor environmental protection effect of the packaged chip in the existing technology.

[0012] Secondly, adding silica filler can increase the brittleness of the packaging material; this increases the stress between the high-modulus packaging material and the chip during use, leading to the risk of cracking of the packaging layer and the technical problem of poor stability of the packaged chip.

[0013] To address the aforementioned issues, the inventors conducted repeated and in-depth research and realized that, based on this realization, they creatively discovered a method using modified bamboo charcoal filler to replace silica filler. Firstly, the honeycomb-like porous microstructure of bamboo charcoal significantly increases the migration path of external pollutant ions due to the tortuous nature of the pores, reducing the diffusion of pollutant ions and thus improving the environmental protection performance of the encapsulated chip material. Simultaneously, the formation of micro-curing pillars within the pores by epoxy resin generates a strong mechanical locking force. This not only effectively alleviates the thermal expansion coefficient mismatch stress between the chip and the encapsulation material, solving the technical problem of encapsulation layer cracking, but also, because the modified bamboo charcoal is prepared from natural bamboo, it not only reduces production costs but also facilitates recycling and offers high environmental performance. Thus, this invention was completed.

[0014] This application provides a semi-solid encapsulation granule containing bamboo charcoal filler, comprising the following components by weight:

[0015] A. 80-120 parts epoxy resin;

[0016] B. 150-250 parts of modified bamboo charcoal;

[0017] C. 3-7 parts of curing agent.

[0018] In any embodiment, the porosity of the modified bamboo charcoal is greater than 0.5 cm. 3 / g.

[0019] In any embodiment, the curing agent is a microencapsulated imidazole curing agent, which is composed of a core material and a shell material; the core material of the microencapsulated imidazole curing agent is an imidazole or a modified imidazole derivative, and the shell material of the microencapsulated imidazole curing agent is polyurea or a polyurea.

[0020] In any embodiment, it also includes 1-2 parts of silane coupling agent.

[0021] In any embodiment, the diameter of the semi-solid encapsulation particle is 0.8-1.5 mm.

[0022] The second aspect of this application provides a method for preparing semi-solid encapsulated particles containing bamboo charcoal filler, the method comprising the following steps:

[0023] S1. Preparation of modified bamboo charcoal: Bamboo biomass is placed in a carbonization furnace and subjected to high-temperature carbonization treatment. After acid washing, modified bamboo charcoal is obtained for later use.

[0024] S2. Preparation of semi-cured granules: Take the modified bamboo charcoal, epoxy resin and curing agent from step S1 in sequence and place them in a twin-screw extruder. Control the multi-stage heating temperature of the extruder and extrude to obtain semi-cured granules.

[0025] In any embodiment, step S1, preparing modified bamboo charcoal, includes the following sub-steps:

[0026] S11. Raw material selection and pretreatment: Take bamboo biological powder and wash it in an ultrasonic cleaning device to remove surface ash, then dry it at high temperature to powder for later use; wherein, the particle size of bamboo biological powder is 2000-3000 mesh; the moisture content of bamboo biological powder is <1%.

[0027] S12. Carbonization treatment: Take the dried powder from step S11 and place it in a vacuum carbonization furnace or a nitrogen-filled carbonization furnace to carbonize it into bamboo charcoal for later use; wherein, the heating rate is 3-5℃ / min; the target carbonization temperature is 500-700℃; and the carbonization holding time is 3-4 hours.

[0028] S13. Deionization and purification: The bamboo charcoal in step S12 is subjected to ultrasonic-assisted acid leaching with hydrochloric acid, followed by rinsing with ultrapure water 5-8 times until the conductivity of the washing solution is lower than 5µS / cm, and finally dried at 110-130℃ for 3-4 hours to obtain dried bamboo charcoal for later use.

[0029] S14. Surface functionalization treatment: Take the coupling agent and the dried bamboo charcoal from step S13 and place them in a reaction vessel protected by argon or nitrogen and stir evenly to obtain modified bamboo charcoal. The stirring time is 45-60 minutes.

[0030] In any embodiment, step S2, preparing semi-cured particles, includes the following sub-steps:

[0031] S21. Raw material ratio: Take 80-120 parts of epoxy resin, 150-250 parts of modified bamboo charcoal and 3-7 parts of curing agent in sequence, mix them evenly and set aside; wherein, the epoxy resin is phenol A type epoxy resin or multifunctional epoxy resin, and the epoxy equivalent of the epoxy resin is 170-190g / eq; the particle size of the curing agent is 6-20µm;

[0032] S22. Multi-stage temperature-controlled reactive extrusion: The mixture from step S21 is placed in a twin-screw extruder and extruded to obtain shaped round bars;

[0033] S23. Cooling and granulation: The shaped round strips prepared in step S22 are cooled to 40–50°C by air cooling, and then semi-cured granules with a diameter of 0.9–1.2 mm are prepared by cold cutting pelletizer.

[0034] In any embodiment, step S22. Multi-stage temperature-controlled reactive extrusion includes the following sub-steps:

[0035] Step S221: Take the mixture from step S21 and place it in a twin-screw extruder to extrude and obtain a shaped cylindrical strip. The rotation speed of the twin-screw extruder is 40-80 rpm. The extrusion temperature of the twin-screw extruder includes: 50-60℃ in the feeding section, 70-80℃ in the mixing section, 80-90℃ in the curing section, and 75-85℃ in the discharge section.

[0036] Step S222: Every 1-2 minutes, take a sample of the shaped cylindrical bar prepared in step S221 from the discharge port for real-time monitoring of the pre-reaction degree α. If the pre-reaction degree α of the sample is <15%, reduce the speed of the twin-screw extruder in step S221 or increase the extrusion temperature of the twin-screw extruder. If the pre-reaction degree α of the sample is >25%, increase the real-time speed of the twin-screw extruder in step S221 or decrease the extrusion temperature of the twin-screw extruder. If the pre-reaction degree of the sample is 15%≤α≤25%, keep the twin-screw extruder in step S221 in normal operation.

[0037] The third aspect of this application provides a method for using the aforementioned semi-solid encapsulation particles containing bamboo charcoal filler in the encapsulation of semiconductor chips.

[0038] The semi-solid encapsulation particles containing bamboo charcoal filler are used in the semiconductor chip encapsulation process, which includes the following steps:

[0039] Step 1: Particle feeding and preheating: First, place the semi-solid encapsulated particles containing bamboo charcoal filler into a low-pressure injection molding machine, and then preheat the heating sleeve of the low-pressure injection molding machine in sections; wherein, the temperature of the feeding zone is controlled at 70-80℃; the temperature of the mixing zone is controlled at 100-120℃; and the temperature of the molding zone is controlled at 115-125℃.

[0040] Step 2: Low-pressure injection filling: The mold is filled by low-pressure injection using a screw; wherein the injection pressure is 0.5-2.0MPa, the injection speed is 100-300mm / s, and the filling time is 30-120 seconds.

[0041] Step 3: Mold Heating and Curing: Set the heating temperature and curing time for the injected material in the mold;

[0042] The mold heating process includes the following stages of temperature and / or time:

[0043] Mold preheating: 145-155℃; Post-filling heat preservation: 140-160℃ for 30-60 seconds; Isothermal curing: 140-160℃ for 360-420 seconds; Cooling before demolding: 80-100℃ for 60-120 seconds;

[0044] The curing time depends on the thickness of the chip.

[0045] When the chip thickness is less than 0.5 mm, cure at 150℃ for 5-6 minutes; when the chip thickness is 0.5-1.0 mm, cure at 150℃ for 6-7 minutes; when the chip thickness is 1.0-2.0 mm, cure at 150℃ for 7-10 minutes.

[0046] Step 4: Demolding and Post-processing: After demolding, the packaged chip undergoes post-curing to obtain the semiconductor chip package. The post-curing conditions can be any one of the following:

[0047] Curing temperature 120℃, curing time 2h; curing temperature 140℃, curing time 4h; curing temperature 150℃, curing time 6h; and curing temperature 175℃, curing time 1h.

[0048] [Invention Effects]

[0049] The main technical effects of this invention are as follows:

[0050] (1) The present invention provides a semi-solid encapsulation particle, which completes the preparation of the encapsulation material by adding modified bamboo charcoal to replace the silica filler in the prior art; since bamboo is a natural renewable resource, its raw material cost is not only cheap but also generates less pollution and has a high recycling rate; due to the honeycomb porous microstructure of bamboo charcoal, the migration path of external pollutant ions into the chip inside the encapsulation layer is greatly increased due to the tortuous channels. At the same time, the carbonized bamboo charcoal surface has abundant unsaturated carbon atoms and oxygen-containing functional groups, which can naturally electrochemically adsorb pollutant ions, thereby effectively reducing the diffusion of pollutant ions and improving the environmental protection performance of the encapsulation chip material; moreover, through the synergistic effect between epoxy resin and modified bamboo charcoal, epoxy resin forms multiple micro-curing pillars in the pores of modified bamboo charcoal, thereby generating strong mechanical internal locking force and shear strength of the encapsulation material; it can not only effectively alleviate the thermal expansion coefficient mismatch stress between the chip and the encapsulation material, but also solve the technical problem of encapsulation layer cracking.

[0051] (2) The semi-solid encapsulation particles provided by the present invention, by adding a curing agent, and the curing agent is a microencapsulated imidazole curing agent, the microencapsulated latent curing agent can encapsulate the active curing agent (imidazole or modified imidazole derivative) in the microcapsule shell (polyurea or polyurea), preventing it from reacting with epoxy resin at room temperature. This allows the curing agent to only soften and rupture when the temperature rises to above 120°C, releasing the active curing agent. This not only makes the semi-solid encapsulation particles last longer, but also prevents the particles from sticking, clumping, or hardening. Furthermore, the cross-linking density with epoxy resin during the encapsulation injection process is higher and faster, resulting in higher quality and more stable use of the prepared encapsulated chip.

[0052] (3) The present invention provides a method for preparing semi-solid encapsulated particles. Through a modification process, bamboo powder is first carbonized at high temperature to form bamboo charcoal with a liquid permeation network with high porosity and large specific surface area. Then, through deionization and purification and modification with coupling agent, the surface of bamboo charcoal is changed from hydrophilic to oleophilic. This not only makes the compatibility between bamboo charcoal and epoxy resin better, but also makes the composite material stronger. At the same time, when epoxy resin is combined with bamboo charcoal, after the epoxy resin enters the pores of bamboo charcoal and is cured, multiple resin columns or internal locking structures not only increase the effective migration distance of water molecules and external harmful ions, but also improve the shear strength of the encapsulated particles.

[0053] (4) The present invention provides a method for preparing semi-solid encapsulated particles. By real-time monitoring of the pre-reactivity α of the molded sample, the pre-reactivity α of the semi-solid encapsulated particles after extrusion is monitored in real time. If the pre-reactivity α of the sample is <15% or α>25%, the real-time speed or extrusion temperature of the twin-screw extruder is adjusted so that the reactivity α of the sample is 15-25%, ensuring that the particles do not react during room temperature storage and have a long storage time. Rapid reaction is achieved at a low temperature of 150℃ and the post-curing time of the encapsulated particles is reduced.

[0054] (5) The present invention provides a semi-solid encapsulation particle for semiconductor chip encapsulation process. This process can achieve chip encapsulation through low-pressure injection. Compared with the high-pressure encapsulation process in the prior art, it not only reduces the requirements for encapsulation equipment, but also simplifies the encapsulation equipment, and is easy to popularize and transfer technology. Specifically, due to the modification and particle refinement of modified bamboo charcoal, the molten epoxy resin has excellent flow characteristics, and void-free filling can be achieved under low pressure. Attached Figure Description

[0055] Figure 1 The image shown is a micrograph (SEM) of bamboo powder in the example.

[0056] Figure 2 This is a photograph of the semi-solid encapsulated particles in the embodiment. Detailed Implementation

[0057] The embodiments of this application are disclosed in detail below with appropriate reference to the accompanying drawings. However, unnecessary details may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of actually identical structures may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims. The "scope" disclosed in this application is defined in the form of a lower limit and an upper limit, whereby a given scope is defined by selecting a lower limit and an upper limit, which define the boundaries of the particular scope. Scopes defined in this way may include or exclude end values ​​and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a scope. For example, if a scope of 60-120 and 80-110 is listed for a specific parameter, it is expected that the scopes of 60-110 and 80-120 are also included. Furthermore, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4, and 5 are listed, then the following ranges can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range “ab” represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range “0-5” means that all real numbers between “0-5” have been listed herein, and “0-5” is merely a shortened representation of these numerical combinations. Additionally, when a parameter is stated as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0058] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0059] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0060] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0061] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0062] Semi-solid packaged particles

[0063] As used in this article, the term "semi-solid encapsulation material" refers to the material properties of the outer encapsulation layer of a chip, other than its shape or structure. It encompasses both the raw materials (raw materials) of the outer encapsulation layer and the molded materials obtained from these raw materials through conventional plastic processing.

[0064] This invention discloses a semi-solid encapsulation granule containing bamboo charcoal filler, comprising the following components by weight:

[0065] A. 80-120 parts epoxy resin;

[0066] B. 150-250 parts of modified bamboo charcoal;

[0067] C. 3-7 parts of curing agent.

[0068] The diameter of semi-solid encapsulation particles directly affects encapsulation efficiency and storage life. Suitable, but not limiting, semi-solid encapsulation particle diameters are 0.8–1.5 mm, with examples including: 0.80–0.88 mm, 0.86–0.94 mm, 0.92–1.00 mm, 0.98–1.06 mm, 1.04–1.12 mm, 1.10–1.18 mm, 1.16–1.24 mm, and 1.22–1. Aspect ratios within this range include 30mm, 1.28–1.36mm, 1.34–1.42mm, 1.40–1.48mm, 0.82–0.90mm, 0.89–0.97mm, 0.95–1.03mm, 1.01–1.09mm, 1.07–1.15mm, 1.13–1.21mm, 1.19–1.27mm, 1.25–1.33mm, and 1.31–1.39mm. Within this range, the aspect ratio offers a good balance between storage performance and injection molding performance.

[0069] If the diameter of the semi-solid encapsulation particles is greater than 1.5mm, the contact area between them and the injection mold is small, the melting time is long, and the encapsulation efficiency is reduced. If the diameter of the semi-solid encapsulation particles is less than 0.5mm, they are prone to sticking together during storage, resulting in poor storage stability.

[0070] Modified bamboo charcoal

[0071] In any embodiment, the amount of modified bamboo charcoal added can be obtained by those skilled in the art through conventional experiments based on protective performance and other specific performance requirements such as shear properties, storage stability, and cost of use. Suitable but not limiting amounts of modified bamboo charcoal include 150-250 parts, with exemplary amounts being 151-247 parts, 154-174 parts, 155-199 parts, 156-201 parts, 161-169 parts, 162-170 parts, 172-177 parts, 178-202 parts, 224-225 parts, 227-240 parts, 239-241 parts, and 247 parts. ~248 portions, 155~227 portions, 169~207 portions, 174~212 portions, 177~216 portions, 199~224 portions, 201~225 portions, 154~239 portions, 161~240 portions, 170~241 portions, 172~247 portions, 178~248 portions, 155~202 portions, 156~198 portions, 198~227 portions, 201~239 portions, etc.

[0072] When the amount of modified bamboo charcoal is less than 150 parts, the filler content is insufficient, failing to form an effective heat conduction path. This results in low thermal conductivity and poor heat dissipation, failing to meet the heat dissipation requirements of electronic device packaging. Insufficient support and constraint on the epoxy resin matrix leads to a high coefficient of thermal expansion (CTE), resulting in high thermal stress during device operation and a tendency for warping, cracking, and delamination. This fails to demonstrate the technical advantages of high filler content, low cost, and high thermal stability of this invention, thus failing to achieve the invention's objectives. When the amount of modified bamboo charcoal exceeds 250 parts, excessive filler can easily cause agglomeration, worsening the interfacial bonding with epoxy resin, increasing interfacial defects, and significantly reducing shear performance. High filler content leads to internal stress concentration, causing greater fluctuations in the coefficient of thermal expansion, worsening dimensional stability, and making cracking after packaging more likely. Dispersion becomes significantly more difficult; even with extended stirring time and increased temperature, uniform mixing is still difficult, resulting in poor process stability and hindering industrial production.

[0073] It should be noted that the bamboo biomass used for the modified bamboo charcoal can be selected from moso bamboo powder, phoenix bamboo powder, light bamboo powder, etc. Among them, moso bamboo has thick culm walls, high density (about 0.6 g / cm³), dense fiber tissue, and well-developed natural vessels and pits. After high-temperature oxygen-limited carbonization, it retains a complete tubular skeleton and forms multi-level pores. Its microscopic morphology is a honeycomb interconnected network, with micropores densely distributed on the bamboo fiber wall, and mesopores serving as transport channels connecting micropores and macropores. The surface is rich in oxygen-containing functional groups such as hydroxyl and carboxyl groups, which enhance polar adsorption.

[0074] Phoenix bamboo: The culms are thin and dense, with thin walls but strong toughness and a short growth cycle; after high-temperature oxygen-limited carbonization, the formation of pores is significantly affected by the distribution of thin-walled cells and vascular bundles, resulting in more uniform microscopic pores, a smaller wall-to-cavity ratio, and micropores concentrated around the vascular bundles; the surface minerals are more evenly attached, and the pH is more neutral.

[0075] Bamboo stalks: Medium-sized, scattered bamboo with moderate culm wall thickness, flexible material, and high cellulose content; carbonization temperature 750–950℃, combining the strength of moso bamboo with the permeability of phoenix bamboo; its microstructure features short cylindrical micropores, a regular mesoporous network, and orderly arranged surface carbon microcrystals, resulting in better electrical conductivity than ordinary bamboo charcoal; low ash content (<3%), making it suitable for fine adsorption and catalytic carriers.

[0076] The porosity of the modified bamboo charcoal in any embodiment can be obtained by those skilled in the art through conventional tests based on water absorption rate, interfacial shear strength, etc. Suitable, but not limiting, modifications to the porosity of bamboo charcoal result in a porosity greater than 0.5 cm. 3 / g, with an exemplary porosity of 0.6cm. 3 / g, 0.55cm 3 / g, 0.62cm 3 / g, 0.66cm 3 / g, 0.58cm 3 / g, 0.71cm 3 / g, 0.68cm 3 / g, 0.58cm 3 / g, etc., when the porosity of modified bamboo charcoal is greater than 0.5cm 3 At / g, it can increase the penetration path of the liquid, which facilitates subsequent mixing with epoxy resin. At the same time, it can also provide more space for the epoxy resin to enter the pores and cure, forming a larger reinforced interfacial bonding area.

[0077] Epoxy Resin

[0078] In any embodiment, the amount of epoxy resin added can be obtained by those skilled in the art through conventional experiments based on factors such as crosslinking density, mechanical properties, thermal properties, chemical resistance, processing, and cost. Suitable, but not limiting, amounts of epoxy resin added are 80-120 parts, with exemplary amounts including 82-87 parts, 85-93 parts, 88-95 parts, 90-98 parts, 91-102 parts, 94-101 parts, 81-89 parts, 86-96 parts, 92-105 parts, 97-106 parts, 83-92 parts, 89-99 parts, 95-108 parts, 100-109 parts, 103-112 parts, 105-115 parts, 107-114 parts, 101-110 parts, and 96-120 parts. 04 parts, etc., the epoxy equivalent of the epoxy resin is 170-190 g / eq, and the exemplary epoxy equivalents are 171-176 g / eq, 173-180 g / eq, 175-182 g / eq, 172-179 g / eq, 177-184 g / eq, 174-181 g / eq, 178-185 g / eq, 170-175 g / eq, 176-183 g / eq, 180-186 g / eq, 181-187 g / eq, 179-185 g / eq, etc.

[0079] When the epoxy resin content is less than 80 parts, it will result in poor strength and hardness of the encapsulated product; insufficient cross-linking and incomplete curing. When the epoxy resin content is higher than 120 parts, it will result in brittle, tough, and easily cracked encapsulated products. When the epoxy equivalent of the epoxy resin is 170-190 g / eq, its low melting point is suitable for production.

[0080] It should be noted that the epoxy resins mentioned above are bisphenol A type epoxy resins or multifunctional epoxy resins, etc.

[0081]

Curing agent

[0082] In any embodiment, the amount of curing agent added can be obtained by those skilled in the art through conventional testing based on the integrity and density of the cross-linked network. Suitable, but not limiting, amounts of curing agent added are 3-7 parts, with exemplary amounts being 3.1-3.6 parts, 3.5-4.2 parts, 3.8-4.5 parts, 4.2-5.0 parts, 4.6-5.3 parts, 5.1-5.8 parts, 5.5-6.2 parts, 6.0-6.8 parts, etc.

[0083] When the curing agent content is less than 3 parts, a large number of epoxy groups will remain unreacted, resulting in an under-cured / semi-cured system. When the curing agent content is higher than 7 parts, it will lead to excessively high crosslinking density and unreacted curing agent residue.

[0084] It should be noted that the curing agent is a microencapsulated imidazole curing agent, which is composed of a core material and a shell material; the core material of the microencapsulated imidazole curing agent is an imidazole or a modified imidazole derivative (such as 2-methylimidazolium, 2-phenylimidazolium, etc.), and the shell material of the microencapsulated imidazole curing agent is polyurea or polyurea. The diameter of the microencapsulated imidazole curing agent directly affects its mixing effect with epoxy resin. A suitable, but not limiting, diameter for the microencapsulated imidazole curing agent is 6-20 μm; examples include: 6.2–8.5 μm, 7.1–9.3 μm, 8.0–10.2 μm, 9.5–11.8 μm, 10.1–12.4 μm, 11.3–13.7 μm, 12.2–14.5 μm, 13.5–15.9 μm, 14.1–16.3 μm, 15.2–17.6 μm, 16.0–18.2 μm, 16.8–19.1 μm, 17.3–19.7 μm, 18.1–19.9 μm, and 6.8–11.5 μm. Within this range, the long axis facilitates mixing with epoxy resin and modified bamboo charcoal.

[0085] Silane coupling agents

[0086] In any embodiment, the amount of silane coupling agent added can be obtained by those skilled in the art through conventional testing based on compatibility and other factors. Suitable, but not limiting, amounts of silane coupling agent added include 1-2 parts of curing agent; exemplary amounts include 1.1-1.3 parts, 1.2-1.5 parts, 1.4-1.6 parts, 1.3-1.7 parts, 1.5-1.8 parts, 1.6-1.9 parts, etc.; adding 1-2 parts of curing agent can further improve compatibility.

[0087] [Preparation method of semi-solid encapsulated particles containing bamboo charcoal filler]

[0088] The preparation method of the above-mentioned semi-solid encapsulation particles containing bamboo charcoal filler includes the following steps:

[0089] Step 1: Place bamboo biological powder in an ultrasonic cleaning device to wash and remove surface ash, then dry it at high temperature until it becomes powder for later use;

[0090] Among them, bamboo biological powders include the aforementioned moso bamboo powder, phoenix bamboo powder, light bamboo powder, etc.

[0091] Ultrasonic washing and rinsing until the conductivity of the powder is <5µS / cm;

[0092] High-temperature drying involves drying at 110 degrees Celsius for 2 hours until the moisture content of the powder is less than 1%.

[0093] Step 2: Take the dried powder from step S11 and place it in a vacuum carbonization furnace or a nitrogen-filled carbonization furnace to carbonize it into bamboo charcoal for later use;

[0094] The heating rate inside the furnace is 3-5℃ / min; if the temperature is higher than this, the rapid heating will cause the powder to break, and if the temperature is lower than this, the drying efficiency will be too slow and the drying efficiency will drop significantly.

[0095] The target carbonization temperature is 500-700℃, and the carbonization holding time is 3-4 hours. Combining this target temperature and holding time results in carbon powder with maximum porosity and the highest specific surface area. Specifically, at 600℃, the fixed carbon content of the bamboo charcoal reaches 68%, and the specific surface area is >400m². 2 / g, porosity >0.5cm 3 / g.

[0096] Step 3: Use hydrochloric acid to perform ultrasonic-assisted acid leaching on the bamboo charcoal in step S12, then rinse with ultrapure water 5-8 times until the conductivity of the washing solution is lower than 5µS / cm, and finally dry at 110-130℃ for 3-4 hours to obtain dried bamboo charcoal for later use.

[0097] The concentration of hydrochloric acid was 0.08-0.12 mol / L; the resistivity of ultrapure water was 18-19 MΩ·cm.

[0098] The dried bamboo charcoal powder prepared by the above steps must meet the following quality indicators:

[0099] Fixed carbon content ≥95%;

[0100] Ash content <2%;

[0101] Volatile matter <3%;

[0102] pH value 7.5-8.5;

[0103] Specific surface area (BET) ≥ 350 m² / g;

[0104] Porosity: 0.5-0.8 cm³ / g;

[0105] Electrical conductivity <100µS / cm;

[0106] Heavy metals (Pb, Hg, Cd) < 10 ppbeach;

[0107] Step 4: Place the coupling agent and the dried bamboo charcoal with composite quality indicators from Step 3 into a reaction vessel protected by argon or nitrogen and stir evenly to obtain modified bamboo charcoal.

[0108] The coupling agent is monoalkoxytitanate, γ-glycidoxypropyltrimethoxysilane, epoxypropoxypropyltriisopropoxytitanate, epoxyalkyltitanate, etc.; the amount of coupling agent added is 1-3 parts.

[0109] The temperature of the reactor is 75-85℃, and the stirring time is 45-60 minutes.

[0110] The purpose of step four above is to form an organic-inorganic coupling layer on the surface of bamboo charcoal. The reaction mechanism is that the alkoxy groups on the titanate ester react with the -OH groups on the surface of bamboo charcoal to form Ti-OC bonds, which changes the surface of bamboo charcoal from hydrophilic to oleophilic, thereby enhancing the compatibility between bamboo charcoal and epoxy resin matrix.

[0111] Step 5: Take 80-120 parts of epoxy resin, 150-250 parts of modified bamboo charcoal and 3-7 parts of curing agent in sequence, mix them evenly, and then place them in a twin-screw extruder to extrude and obtain shaped round strips.

[0112] The rotational speed of the twin-screw extruder is 40-80 rpm.

[0113] The extrusion temperature of a twin-screw extruder includes: 50-60℃ in the feed section, during the initial mixing stage, to prevent the resin from melting rapidly;

[0114] The mixing section temperature is 70-80℃; thorough mixing begins the pre-reaction process.

[0115] The temperature in the maturation section is 80-90℃; the degree of pre-reaction is controlled, and the viscosity is monitored.

[0116] The discharge section temperature is 75-85℃. The material is cooled down to stabilize the viscosity and prepare for granulation.

[0117] Step Six: Every 1-2 minutes, take a sample (approximately 100 mg) of the shaped cylindrical bar prepared in Step Five from the discharge port for real-time monitoring of the pre-reaction degree α. If the pre-reaction degree α of the sample is <15%, reduce the speed of the twin-screw extruder in Step S221 or increase the extrusion temperature of the twin-screw extruder. If the pre-reaction degree α of the sample is >25%, increase the real-time speed of the twin-screw extruder in Step S221 or decrease the extrusion temperature of the twin-screw extruder. If the pre-reaction degree of the sample is 15%≤α≤25%, continue normal operation of the twin-screw extruder.

[0118] When the pre-reaction degree α is less than 15%, it indicates insufficient reaction and there is a risk of poor particle flowability and easy stratification.

[0119] When the pre-reaction degree α is greater than 25%, it indicates that the reaction is excessive, the viscosity rises rapidly, granulation is difficult, or even agglomeration occurs.

[0120] Among them, the pre-reaction degree α is calculated by comparing the exothermic values ​​of the main solidification peak of the sample with the exothermic values ​​of the unreacted raw material mixture using differential scanning calorimetry (DSC) in the online collection, and then radially calculated.

[0121] Pre-reactivity (α) = (ΔH) total -ΔH partial ) / ΔH total ×100%;

[0122] ΔH in the above formula partial The exothermic value of the main solidification peak, ΔH total The exothermic value of the unreacted raw material mixture;

[0123] Step 7: Cool the shaped round bar prepared in Step 5 to 40–50℃ using air cooling, and the viscosity will rise back to a formable state. Then, use a cold pelletizer to prepare semi-cured encapsulated particles with a diameter of 0.9–1.2 mm.

[0124] Finally, place the semi-cured encapsulated particles in a sealed, dry plastic or paper bag, maintaining an ambient temperature of 18-25℃ and a relative humidity of <50% for stable storage.

[0125] Semi-solid encapsulation particles containing bamboo charcoal filler are used in semiconductor chip packaging processes.

[0126] The aforementioned semi-solid encapsulation particles containing bamboo charcoal filler are used in semiconductor chip packaging processes, including the following steps:

[0127] Step 1: First, place the semi-solid encapsulated granules containing bamboo charcoal filler into a low-pressure injection molding machine, and then preheat the heating sleeve of the low-pressure injection molding machine in sections.

[0128] The temperature in the feeding zone is controlled at 70-80℃ for initial softening to prevent cold shock.

[0129] The temperature in the mixing zone is controlled at 100-120℃ to ensure complete melting and mixing;

[0130] The temperature in the molding zone is controlled at 115-125℃ to stabilize the melt viscosity and prepare for injection.

[0131] Step 2: Use a screw to perform low-pressure injection filling of the mold;

[0132] The injection pressure is 0.5-2.0 MPa, the injection speed is 100-300 mm / s, and the mold filling time is 30-120 seconds.

[0133] Step 3: Set the heating temperature and curing time of the injected material in the mold;

[0134] The mold heating process includes the following stages of temperature and / or time:

[0135] Mold preheating: 145-155℃, to be completed before injection;

[0136] After filling the mold, maintain the temperature at 140-160℃ for 30-60 seconds until the initial flow of the material is complete and it begins to solidify.

[0137] Isothermal curing: 140-160℃, time 360-420s, during which the main curing reaction takes place;

[0138] Cooling before demolding: 80-100℃ for 60-120 seconds, partial cooling to avoid overheating stress during demolding;

[0139] The curing time depends on the thickness of the chip.

[0140] When the chip thickness is less than 0.5mm, it is cured at 150℃ for 5-6 minutes. Thin chips have fast heat transfer.

[0141] When the chip thickness is 0.5-1.0mm, it is cured at 150℃ for 6-7 minutes, standard BGA / QFP;

[0142] When the chip thickness is 1.0-2.0mm, it is cured at 150℃ for 7-10 minutes for large chips or highly integrated SiP.

[0143] Step 4: Demolding and Post-processing: After demolding, the packaged chip undergoes post-curing to obtain the semiconductor chip package. The post-curing conditions can be any one of the following:

[0144] Curing temperature 120℃, curing time 2h;

[0145] Curing temperature 140℃, curing time 4h;

[0146] Curing temperature 150℃, curing time 6h

[0147] Curing temperature 175℃, curing time 1h.

[0148] In this embodiment, the encapsulation injection molding pressure is 0.5-2.0 MPa, which is 75%-98% lower than the 20-140 MPa of traditional injection molding. This corresponds to a 60-70% reduction in mold cost, a 75% reduction in equipment investment, and a more than 50% reduction in energy consumption.

[0149] [Implementation process of the examples and comparative examples]

[0150] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0151] Example 1

[0152] The raw materials for the semi-solid encapsulation granules containing bamboo charcoal filler are as follows by weight:

[0153] Epoxy resin (bisphenol A type epoxy resin): 100 parts

[0154] Modified bamboo charcoal: 200 parts

[0155] Curing agent (microencapsulated imidazole curing agent): 5 parts

[0156] Silane coupling agent: 1 part

[0157] The preparation method is as follows:

[0158] S1: Take 100 parts of epoxy resin, 200 parts of modified bamboo charcoal, 5 parts of curing agent and 1 part of silane coupling agent in sequence, mix them evenly, and then place them in a twin-screw extruder to extrude and obtain shaped round bars; wherein, the rotation speed of the twin-screw extruder is 60 rpm; the extrusion temperature of the twin-screw extruder includes: feed section temperature of 55℃; mixing section temperature of 75℃; curing section temperature of 85℃; discharge section temperature of 80℃.

[0159] S2: Every 1-2 minutes, take a sample of the shaped round bar obtained in step 5 from the discharge port (about 100mg) for real-time monitoring of the pre-reactivity α, and if the pre-reactivity of the sample is 15%≤α≤21%;

[0160] S3: The shaped round bar prepared in step five is cooled to 40–50°C by air cooling, and the viscosity is restored to a formable state. Then, semi-cured encapsulated particles with a diameter of 1.0±0.2 mm are prepared by cold cutting pelletizer.

[0161] Example 2

[0162] The only difference from Example 1 is that the modified bamboo charcoal content was adjusted to 150, the epoxy resin content was reduced to 90 parts, and the proportions of other components were adjusted accordingly.

[0163] Epoxy resin (bisphenol A type epoxy resin): 90 parts

[0164] Modified bamboo charcoal: 150 parts

[0165] Curing agent (microencapsulated imidazole curing agent): 5 parts

[0166] Silane coupling agent: 1 part.

[0167] Example 3

[0168] The only difference from Example 1 is that the modified bamboo charcoal content was adjusted to 250, the epoxy resin content was reduced to 110 parts, and the proportions of other components were adjusted accordingly.

[0169] Epoxy resin (bisphenol A type epoxy resin): 110 parts

[0170] Modified bamboo charcoal: 250 parts

[0171] Curing agent (microencapsulated imidazole curing agent): 5 parts

[0172] Silane coupling agent: 1 part.

[0173] Example 4

[0174] The only difference from Example 1 is that the curing agent is adjusted to 3 parts, and the proportions of other components are adjusted accordingly.

[0175] Epoxy resin (bisphenol A type epoxy resin): 100 parts

[0176] Modified bamboo charcoal: 200 parts

[0177] Curing agent (microencapsulated imidazole curing agent): 3 parts

[0178] Silane coupling agent: 1 part.

[0179] Example 5

[0180] The only difference from Example 1 is that the curing agent is adjusted to 7 parts, and the proportions of other components are adjusted accordingly.

[0181] Epoxy resin (bisphenol A type epoxy resin): 100 parts

[0182] Modified bamboo charcoal: 200 parts

[0183] Curing agent (microencapsulated imidazole curing agent): 7 parts

[0184] Silane coupling agent: 1 part.

[0185] Example 6

[0186] The only difference from Example 1 is that the epoxy resin was adjusted to 80 parts, and the proportions of other components were adjusted accordingly.

[0187] Epoxy resin (bisphenol A type epoxy resin): 80 parts

[0188] Modified bamboo charcoal: 200 parts

[0189] Curing agent (microencapsulated imidazole curing agent): 5 parts

[0190] Silane coupling agent: 1 part

[0191] Example 7

[0192] The only difference from Example 1 is that the epoxy resin is 120 parts, and the proportions of other components are adjusted accordingly.

[0193] Epoxy resin (bisphenol A type epoxy resin): 120 parts

[0194] Modified bamboo charcoal: 200 parts

[0195] Curing agent (microencapsulated imidazole curing agent): 5 parts

[0196] Silane coupling agent: 1 part

[0197] Example 8

[0198] The semiconductor chip packaging process using the semi-solid packaging particles in Example 1 includes the following steps:

[0199] S1. Select a chip size of 10 × 10 mm and a thickness of 0.7 mm; place it in the injection mold;

[0200] S2. Place the semi-solid encapsulated granules containing bamboo charcoal filler into a low-pressure injection molding machine, and then preheat the heating sleeve of the low-pressure injection molding machine in sections; wherein, the temperature of the feeding zone is controlled at 75℃; the temperature of the mixing zone is controlled at 110℃; and the temperature of the molding zone is controlled at 120℃.

[0201] S3. Low-pressure injection using a screw; wherein the injection pressure is 1.0-1.5MPa and the injection speed is 150mm / s;

[0202] S4. Set the heating temperature and curing time of the material injected into the mold; the mold preheating temperature is 150℃; and the mold is kept warm for 45 seconds after filling.

[0203] S5. The semiconductor chip package can be obtained by performing post-curing treatment on the demolded packaged chip, wherein the curing temperature is 150℃, the curing time is 400S, and the demolding temperature is 90℃.

[0204] Example 9

[0205] The only difference from Example 8 is that the semi-solid packaging particles from Example 2 will be used for the semiconductor chip packaging process, while the other components and steps remain unchanged.

[0206] Example 10

[0207] The only difference from Example 8 is that the semi-solid packaging particles from Example 3 will be used for the semiconductor chip packaging process, while the other components and steps remain unchanged.

[0208] Example 11

[0209] The only difference from Example 8 is that the semi-solid packaging particles from Example 4 will be used for the semiconductor chip packaging process, while the other components and steps remain unchanged.

[0210] Example 12

[0211] The only difference from Example 8 is that the semi-solid packaging particles from Example 5 will be used for the semiconductor chip packaging process, while the other components and steps remain unchanged.

[0212] Comparative Example 1

[0213] The only difference from Example 1 is that silicon dioxide, a material from the prior art, is used to replace the modified bamboo charcoal; all other components and processes are the same as in Example 1.

[0214] Comparative Example 2

[0215] The only difference from Example 1 is that unmodified bamboo charcoal is used instead of modified bamboo charcoal; all other components and processes are the same as in Example 1.

[0216] Comparative Example 3

[0217] The only difference from Example 1 is that the content of modified bamboo charcoal is increased to 300 parts, while the other components and processes are the same as in Example 1.

[0218] Comparative Example 4

[0219] The only difference from Example 1 is that the content of modified bamboo charcoal is reduced to 100 parts, while the other components and processes are the same as in Example 1.

[0220] Comparative Example 5

[0221] The only difference from Example 1 is that the content of the curing agent is reduced to 1 part, while the other components and processes are the same as in Example 1.

[0222] Comparative Example 6

[0223] The only difference from Example 8 is that hydrophobic fumed silica (Evonik AEROSIL R972 / R974) will be used as the raw material for the semiconductor chip packaging process.

[0224] Comparative Example 7

[0225] The only difference from Example 8 is that granular epoxy molding compound (Panasonic granular EMC) will be used as the raw material for the semiconductor chip packaging process.

[0226]

evaluate

[0227] A. Thermal conductivity and interfacial bonding strength test

[0228] Experimental participants: Examples 1-7, Comparative Examples 1-5;

[0229] Experimental equipment: Thermal conductivity tester (model: TC-3000, manufacturer: Beijing Huace Instrument Co., Ltd.), interfacial bonding strength tester (model: HTS-500, manufacturer: Shanghai Precision Instrument Co., Ltd.).

[0230] Experimental methods:

[0231] S1: Press the semi-solid particles prepared in each embodiment and comparative example into round discs with a thickness of 1 mm and a diameter of 20 mm;

[0232] S2: The thermal conductivity of each sample was measured at 25℃ using a thermal conductivity meter, employing the steady-state plate method.

[0233] S3: Use an interface bonding strength tester to perform shear peel test and record the maximum bonding strength;

[0234] S4: Test each group of samples 3 times and take the average value.

[0235] Experimental data: thermal conductivity and interfacial bonding strength.

[0236] B. Testing of heat release rate and internal stress during curing process

[0237] Experimental participants: Examples 1-7, Comparative Examples 1-5;

[0238] Experimental equipment: Differential scanning calorimeter (model: DSC-8000, manufacturer: PerkinElmer, USA), internal stress tester (model: ST-100, manufacturer: Guangzhou Stress Instrument Factory).

[0239] Experimental methods:

[0240] S1: Take the semi-solid particles from each example and comparative example and place them in the DSC sample tray respectively;

[0241] S2: Heat to 80℃, record the exothermic curve of the curing process, and analyze the exothermic peak and rate;

[0242] S3: Prepare standard-sized blocks and use an internal stress tester to measure the residual stress of the cured material;

[0243] S4: Test each group of samples 3 times and take the average value;

[0244] Experimental data: peak exothermic temperature and internal stress during the curing process.

[0245] C. Liquidity test;

[0246] Experimental participants: Examples 1-7, Comparative Examples 1-5

[0247] Experimental equipment: Flowability tester (model: FL-100, manufacturer: Beijing Rheology Instruments Co., Ltd.);

[0248] Experimental methods:

[0249] S1: Prepare semi-solid particle samples for each example and comparative example;

[0250] S2: Use a flowability tester to determine the slurry flow rate and molding properties;

[0251] S3: Each group of samples was tested 3 times, and the average value was taken;

[0252] Experimental data: flow rate.

[0253] D. Thermal cycling aging performance test Experimental participants: Examples 1-7, Comparative Examples 1-5;

[0254] Experimental equipment: Thermal cycling aging test chamber (model: TH-900, manufacturer: Suzhou Kerui Instrument Co., Ltd.), mechanical property tester (model: MTS-300, manufacturer: MTS Corporation, USA).

[0255] Experimental methods:

[0256] S1: Place each sample in a thermal cycling aging test chamber, with a cycling temperature range of 25℃ to 100℃, for a total of 2000 cycles; S2: After aging, use a mechanical property tester to determine the shear strength and elastic modulus of the material;

[0257] S3: Record performance changes before and after aging;

[0258] S4: Test each group of samples 3 times and take the average value.

[0259] Experimental data: Elastic modulus.

[0260] E. Water absorption performance test

[0261] Experimental participants: Examples 8-12, Comparative Examples 6-7;

[0262] Test standard: IPC-TM-650 2.3.28;

[0263] Experimental equipment and conditions: Constant temperature and humidity test chamber (model: BTH-225, manufacturer: Guangdong Bell); temperature 85℃, relative humidity 85% RH, test time 168 h;

[0264] Experimental data: water absorption rate.

[0265] F. Leakage Current Test

[0266] Experimental participants: Examples 8-12, Comparative Examples 6-7;

[0267] Experimental equipment and conditions: High resistance meter insulation resistance tester (model: 6517B, manufacturer: Keithley); temperature 85℃, relative humidity 85% RH, test time 168 h;

[0268] Experimental methods:

[0269] S1: Take the above-packaged sample and pretreat it at 85 ℃ and 85% RH for 168 h;

[0270] S2: Remove and cool to room temperature;

[0271] S3: Apply DC 100 V between the two electrodes;

[0272] S4: After holding for 60 seconds, read the insulation resistance R or leakage current I;

[0273] Convert using the formula: ;

[0274] Where: I is the leakage current (A), U is the test voltage (V), and R is the insulation resistance (Ω).

[0275] Experimental data: Leakage current.

[0276]

evaluate

[0277] The semi-solid encapsulation particulate materials prepared according to the various examples and comparative examples in Table 1 were evaluated as follows:

[0278] Table 1: Evaluation Results of Semi-Solid Encapsulated Particles

[0279] Sample number Thermal conductivity (W / m·K) Interfacial bond strength (MPa) Peak heat release during curing (°C) Internal stress (MPa) Flow rate (mm / s) Elastic modulus (GPa) Example 1 2.15 18.2 86 2.1 4.2 3.2 Example 2 2.35 17.8 85 2.0 4.0 3.1 Example 3 2.10 19.5 84 1.8 4.3 3.3 Example 4 2.20 18.0 83 1.7 4.1 3.2 Example 5 2.22 18.6 85 2.0 4.5 3.2 Example 6 2.08 17.2 86 2.1 4.1 3.0 Example 7 2.12 18.9 84 1.8 4.2 3.1 Comparative Example 1 1.30 10.2 97 4.5 2.2 2.2 Comparative Example 2 1.45 12.0 95 3.9 2.5 2.3 Comparative Example 3 2.05 15.0 92 3.2 1.2 2.7 Comparative Example 4 1.25 11.5 98 4.8 2.4 2.1 Comparative Example 5 2.18 16.0 86 2.7 1.0 2.9

[0280] As shown in Table 1, Examples 1-7 using surface-modified bamboo charcoal filler exhibit significantly higher thermal conductivity and interfacial bonding strength than Comparative Example 1, which uses traditional silica filler. Furthermore, Examples 1 show a marked increase in curing exothermic peak and internal stress, particularly compared to the sample in Comparative Example 5 which uses a curing agent, demonstrating excellent thermal management and interfacial reliability. Examples 1-7 exhibit good flowability, making them suitable for automated processing; while Comparative Examples 1-5 show poor flowability, affecting the material's application window.

[0281] The materials in Examples 1-7 exhibit high performance retention after aging and a small decrease in elastic modulus, demonstrating excellent long-term reliability; in Comparative Examples 1-5, the attenuation is significant, making it difficult to meet the requirements for long-term use.

[0282] The following evaluation was conducted on the semiconductor chip packaging samples of the semi-solid packaging particles prepared according to the various embodiments and comparative examples in Table 2:

[0283] Table 2: Evaluation Results of Semiconductor Chip Packaging Samples Based on Semi-Solid Packaging Particles

[0284] Sample number Equipment pressure (MPa) Material utilization rate (%) In-mold curing time (s) Post-curing time (h) Water absorption rate (%) Stress Residue Leakage current (µA) Example 8 0.8 99 370 2.4 0.41 Low 93 Example 9 1.3 98 360 2.6 0.42 Low 95 Example 10 1.1 99 375 2.5 0.39 Low 98 Example 11 1.7 97 368 2.8 0.40 Low 97 Example 12 1.8 99 374 3.1 0.45 Low 96 Comparative Example 6 150 55 180 5 N / A medium 110 Comparative Example 7 60 85 150 2.5 0.29 Low 100

[0285] As shown in Table 2, the equipment pressure in Examples 8-12 is significantly lower than that in Comparative Examples 6 and 7. This indicates that the modification and particle refinement of the modified bamboo charcoal in this application gives the molten epoxy resin excellent flow characteristics, enabling void-free filling even under low pressure. The material utilization rate of Examples 8-12 is significantly better than that of Comparative Example 6, demonstrating the technical contribution of the modified bamboo charcoal in this application to the environmental performance of the product. Furthermore, the leakage current (µA) of Examples 8-12 is close to and better than that of Comparative Examples 1-2 (commonly used encapsulation materials in the prior art), further confirming that the encapsulation effect of modified bamboo charcoal on epoxy resin is consistent with that produced by conventional products, and does not affect the normal use of the encapsulated chip.

[0286] The above embodiments are merely illustrative of the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A semi-solid encapsulated granule containing bamboo charcoal filler, characterized in that, By weight, it includes the following components: A. 80-120 parts epoxy resin; B. 150-250 parts of modified bamboo charcoal; C. 3-7 parts of curing agent.

2. The semi-solid encapsulated granules containing bamboo charcoal filler according to claim 1, characterized in that, The modified bamboo charcoal has a porosity greater than 0.5 cm. 3 / g.

3. The semi-solid encapsulated granules containing bamboo charcoal filler according to claim 1, characterized in that: The curing agent is a microencapsulated imidazole curing agent, which is composed of a core material and a shell material; the core material of the microencapsulated imidazole curing agent is an imidazole or a modified imidazole derivative, and the shell material of the microencapsulated imidazole curing agent is polyurea or polyurea.

4. The semi-solid encapsulated granules containing bamboo charcoal filler according to claim 1, characterized in that, Its features are: It also includes 1-2 parts of silane coupling agent.

5. The semi-solid encapsulated granules containing bamboo charcoal filler according to any one of claims 1-4, characterized in that: The diameter of the semi-solid encapsulation particles is 0.8-1.5 mm.

6. A method for preparing semi-solid encapsulated particles containing bamboo charcoal filler as described in any one of claims 1-5, characterized in that, The preparation method includes the following steps: S1. Preparation of modified bamboo charcoal: Bamboo powder is placed in a carbonization furnace and subjected to high-temperature carbonization treatment. After acid washing, modified bamboo charcoal is obtained for later use. S2. Preparation of semi-cured granules: Take the modified bamboo charcoal, epoxy resin and curing agent from step S1 in sequence and place them in a twin-screw extruder. Control the multi-stage heating temperature of the extruder and extrude to obtain semi-cured granules.

7. The method for preparing semi-solid encapsulated particles according to claim 6, characterized in that, Step S1, preparing modified bamboo charcoal, includes the following sub-steps: S11. Raw material selection and pretreatment: Take bamboo biological powder and wash it in an ultrasonic cleaning device to remove surface ash, then dry it at high temperature to powder for later use; wherein, the particle size of bamboo biological powder is 2000-3000 mesh, and the moisture content of bamboo biological powder is <1%. S12. Carbonization treatment: Take the dried powder from step S11 and place it in a vacuum carbonization furnace or a nitrogen-filled carbonization furnace to carbonize it into bamboo charcoal for later use; wherein, the heating rate is 3-5℃ / min; the target carbonization temperature is 500-700℃; and the carbonization holding time is 3-4 hours. S13. Deionization and purification: The bamboo charcoal in step S12 is subjected to ultrasonic-assisted acid leaching with hydrochloric acid, followed by rinsing with ultrapure water 5-8 times until the conductivity of the washing solution is lower than 5µS / cm, and finally dried at 110-130℃ for 3-4 hours to obtain dried bamboo charcoal for later use. S14. Surface functionalization treatment: Take the coupling agent and the dried bamboo charcoal from step S13 and place them in a reaction vessel protected by argon or nitrogen and stir evenly to obtain modified bamboo charcoal. The stirring time is 45-60 minutes.

8. The method for preparing semi-solid encapsulated particles according to claim 7, characterized in that, Step S2, preparing semi-cured particles, includes the following sub-steps: S21. Raw material ratio: Take 80-120 parts of epoxy resin, 150-250 parts of modified bamboo charcoal and 3-7 parts of curing agent in sequence, mix them evenly and set aside; wherein, the epoxy resin is phenol A type epoxy resin or multifunctional epoxy resin, and the epoxy equivalent of the epoxy resin is 170-190g / eq; the particle size of the curing agent is 6-20µm; S22. Multi-stage temperature-controlled reactive extrusion: The mixture from step S21 is placed in a twin-screw extruder and extruded to obtain shaped round bars; S23. Cooling and granulation: The shaped round strips prepared in step S22 are cooled to 40–50°C by air cooling, and then semi-cured granules with a diameter of 0.9–1.2 mm are prepared by cold cutting pelletizer.

9. The method for preparing semi-solid encapsulated particles according to claim 8, characterized in that, Step S22, multi-stage temperature-controlled reactive extrusion, includes the following sub-steps: Step S221: Take the mixture from step S21 and place it in a twin-screw extruder to extrude and obtain a shaped cylindrical strip. The rotation speed of the twin-screw extruder is 40-80 rpm. The extrusion temperature of the twin-screw extruder includes: 50-60℃ in the feeding section, 70-80℃ in the mixing section, 80-90℃ in the curing section, and 75-85℃ in the discharge section. Step S222: Every 1-2 minutes, take a sample of the shaped cylindrical bar prepared in step S221 from the discharge port for real-time monitoring of the pre-reaction degree α. If the pre-reaction degree α of the sample is <15%, reduce the speed of the twin-screw extruder in step S221 or increase the extrusion temperature of the twin-screw extruder. If the pre-reaction degree α of the sample is >25%, increase the real-time speed of the twin-screw extruder in step S221 or decrease the extrusion temperature of the twin-screw extruder. If the pre-reaction degree of the sample is 15%≤α≤25%, keep the twin-screw extruder in step S221 in normal operation.

10. A semi-solid encapsulation particle containing bamboo charcoal filler as described in any one of claims 1-5, used for the encapsulation of semiconductor chips.

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