Liquid molding compound for eliminating flow marks as well as method and application of liquid molding compound

Abstract

The invention discloses a liquid molding compound for eliminating flow marks and a method and application thereof, and relates to the technical field of electronic packaging materials, the liquid molding compound comprises the following components by mass: 85%-90% of silicon dioxide, 4%-8% of epoxy resin, 5%-8% of an anhydride curing agent, 0.2%-0.5% of organic pregel microparticles, 0.2%-0.3% of a catalyst, and 0.1%-0.2% of carbon black, the maximum particle size of the silicon dioxide is less than 75 microns, and the particle size distribution of the silicon dioxide is as follows: 1.4 microns < = D10 < = 1.6 microns, 12 microns < = D50 < = 18 microns, and 40 microns < = D90 < = 50 microns. The flow mark of the liquid molding compound is improved by adopting the silicon dioxide with different particle size distribution, the catalyst formed by compounding the silicon dioxide and the organic pre-gel microparticles, so that the liquid molding compound has no flow mark after being packaged and cured, and the comprehensive performance and the production yield of a packaged device are improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of electronic packaging materials, and particularly relates to a liquid molding compound capable of eliminating flow marks as well as a method and application thereof. BACKGROUND

[0002] In a liquid molding compound (LMC) packaging process, flow mark defects not only affect the appearance of a product, but also seriously damage the mechanical strength, electrical reliability and long-term service performance of an electronic device.

[0003] At present, two typical flow mark problems, i.e., edge white flow marks and center jet flow marks, are mainly faced in an electronic packaging process. The edge white flow marks are strip-shaped gray marks distributed along the edges of a chip or a frame, and are commonly seen at the end of flow or in a structure mutation area. The core cause of the edge white flow marks lies in the phase separation of fillers and resin induced by high shear force in a hot pressing process, i.e., a low-viscosity resin phase preferentially flows along a wall surface, and filler particles lag behind and deposit due to frictional resistance, thereby forming a local filler-rich area. Such defects will cause a hard and brittle interface to be formed between the filler-rich area and a matrix, and microcracks will be induced in subsequent thermal cycles due to the mismatch of thermal expansion coefficients, and finally, the encapsulation material and the chip will be delaminated, which seriously threatens the reliability of a device. The center jet flow marks are radial lines radiating from a glue dropping area, and the root cause of the center jet flow marks lies in the high-speed jetting of a low-viscosity melt under high pressure, thereby forming unsteady flow. Such turbulence causes the viscosity distribution inside the material to be uneven, and part of the melt is non-uniformly filled to the far end of a cavity in a jetting manner, instead of ideal laminar flow expansion. Such flow marks directly weaken the mechanical integrity, moisture-proof sealing and heat resistance of a plastic encapsulation material, and at the same time, the production yield is reduced due to the obvious surface defects, and the process fluctuation and maintenance cost are also increased.

[0004] Therefore, how to provide a liquid molding compound capable of eliminating flow marks to improve the comprehensive performance and production yield of a packaged device is a technical problem that those skilled in the art need to solve urgently. SUMMARY

[0005] The present application aims to provide a liquid molding compound capable of eliminating flow marks as well as a method and application thereof, so as to at least solve the above-mentioned technical problem.

[0006] To achieve the above object, the present application provides a liquid molding compound for eliminating flow marks, which comprises the following components in percentage by mass: 85-90% of silica, 4-8% of epoxy resin, 5-8% of acid anhydride curing agent, 0.2-0.5% of organic pre-gel microparticles, 0.2-0.3% of catalyst, and 0.1-0.2% of carbon black; the maximum particle size of the silica is less than 75 μm, and the particle size distribution of the silica is 1.4 μm≤D10≤1.6 μm, 12 μm≤D50≤18 μm, and 40 μm≤D90≤50 μm; the epoxy resin comprises at least one of bisphenol A type epoxy resin, naphthalene type epoxy resin, and alicyclic epoxy resin; and the catalyst is composed of latent microencapsulated imidazole and an accelerator.

[0007] In the first aspect, the accelerator comprises an imidazole type accelerator or an amine type accelerator.

[0008] In the first aspect, the imidazole type accelerator comprises 2-ethyl-4-methylimidazole, and the amine type accelerator comprises benzyl dimethyl amine.

[0009] In the first aspect, the product model of the latent microencapsulated imidazole is PN50.

[0010] In the first aspect, the product model of the organic pre-gel microparticles is F351.

[0011] In the first aspect, the acid anhydride curing agent comprises at least one of methylhexahydrophthalic anhydride and methyltetrahydrophthalic anhydride.

[0012] The second aspect of the present application provides a method for eliminating flow marks of a liquid molding compound, which comprises the following steps: S1, adding each component of the raw material of the liquid molding compound according to the first aspect into a stirring cup in proportion and mixing uniformly to obtain a first slurry; S2, transferring the first slurry to a three-roll mill for dispersion treatment to obtain a second slurry; S3, performing vacuum degassing on the second slurry to obtain a third slurry; and S4, extruding the third slurry on a device to be packaged and performing vacuum curing to obtain a packaged device without flow mark defects.

[0013] In the second aspect, in S2, the entry gap of the three-roll mill is 150-200 μm, and the exit gap is 90-120 μm.

[0014] In the second aspect, in S3, the vacuum degassing time is 60-90 s.

[0015] The third aspect of the present application provides an application of the liquid molding compound for eliminating flow marks according to the first aspect in integrated circuit packaging.

[0016] Advantages: The application provides a liquid molding material capable of eliminating flow marks, which comprises the following components in percentage by mass: 85-90% of silica, 4-8% of epoxy resin, 5-8% of acid anhydride curing agent, 0.2-0.5% of organic pre-gel microparticles, 0.2-0.3% of catalyst and 0.1-0.2% of carbon black; wherein the maximum particle size of the silica is less than 75 microns, and the particle size distribution of the silica is 1.4 microns <= D10 <= 1.6 microns, 12 microns <= D50 <= 18 microns and 40 microns <= D90 <= 50 microns; the flowability of the liquid molding material during extrusion diffusion and the shrinkage rate of the liquid molding material during encapsulation curing are adjusted by controlling the particle size distribution of the silica; the catalyst composed of latent microencapsulated imidazole and accelerant can significantly reduce the initial curing temperature, reduce the residence time of the liquid molding material at the lowest viscosity point during heating, and improve the lowest rheological viscosity of the liquid molding material during heating and curing, thereby improving the flow marks caused by high pressure outward ejection of the liquid molding material during encapsulation and heat pressing; the pre-gel property of the organic pre-gel microparticles is used to increase the rheological viscosity by microparticle swelling when the liquid molding material is not completely cured, so as to prevent the glue liquid from collapsing during encapsulation and curing, and then improve the flow marks caused by high pressure during the low viscosity stage of the liquid molding material. The application improves the flow marks of the liquid molding material by using silica with different particle size distributions, a catalyst formed by two kinds of compounding and organic pre-gel microparticles, so that the liquid molding material has no flow marks after encapsulation and curing, and the comprehensive performance and production yield of the encapsulated device are improved. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings described below only show some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort.

[0018] Figure 1 The flowchart of the method for eliminating flow marks of liquid molding material provided by the present application is shown in the figure. Figure 2 The test method diagram of the warpage of the liquid molding material in the present application is shown in the figure. Figure 3 The test method diagram of the flow marks of the liquid molding material in the present application is shown in the figure. Figure 4 The observation effect diagram of the liquid molding material prepared in Example 3 of the present application under strong light is shown in the figure. Figure 5 The SAT ultrasonic scanning effect diagram of the liquid molding material prepared in Example 3 of the present application is shown in the figure. Figure 6 The SAT ultrasonic scanning effect diagram of the liquid molding material prepared in Comparative Example 1 of the present application is shown in the figure. Figure 7 ultrasonic scanning effect diagram of liquid molding material SAT prepared for the present application comparative example 3; Reference signs: 1, upper plate of vacuum vulcanizing machine; 2, liquid molding material; 3, silicon wafer; 4, lower plate of vacuum vulcanizing machine; 5, cured liquid molding material; 6, glass wafer; 7, liquid molding material after vacuum hot pressing; a, warping height. DETAILED DESCRIPTION

[0019] The advantages and various effects of the present application will be more clearly presented hereinafter with specific embodiments and examples. Those skilled in the art should understand that these specific embodiments and examples are used to illustrate the present application, not to limit the present application.

[0020] Throughout the specification, unless otherwise specifically indicated, the terms used herein are to be understood as having the meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs. If there is a contradiction, the present specification takes precedence.

[0021] Unless otherwise specifically stated, the various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be obtained by existing methods.

[0022] The present application provides a liquid molding material for eliminating flow marks, which comprises the following components in mass percentage: 85%-90% of silica, 4%-8% of epoxy resin, 5%-8% of acid anhydride curing agent, 0.2%-0.5% of organic pre-gel microparticles, 0.2%-0.3% of catalyst, and 0.1%-0.2% of carbon black; the maximum particle size of the silica is less than 75 μm, and the particle size distribution of the silica is: 1.4 μm≤D10≤1.6 μm, 12 μm≤D50≤18 μm, and 40 μm≤D90≤50 μm; the epoxy resin comprises at least one of bisphenol A type epoxy resin, naphthalene type epoxy resin and alicyclic epoxy resin; and the catalyst is composed of latent microencapsulated imidazole and accelerant.

[0023] Specifically, the application provides a liquid molding material for eliminating flow marks, which comprises the following components in percentage by mass: 85-90% of silica, 4-8% of epoxy resin, 5-8% of acid anhydride curing agent, 0.2-0.5% of organic pre-gel microparticles, 0.2-0.3% of catalyst, and 0.1-0.2% of carbon black; wherein the maximum particle size of the silica is less than 75 microns, and the particle size distribution of the silica is 1.4 microns ≤ D10 ≤ 1.6 microns, 12 microns ≤ D50 ≤ 18 microns, and 40 microns ≤ D90 ≤ 50 microns; the flowability of the liquid molding material during extrusion diffusion and the shrinkage rate of the liquid molding material during encapsulation curing are adjusted by controlling the particle size distribution of the silica; the catalyst composed of latent microencapsulated imidazole and an accelerator can significantly reduce the initial curing temperature, and the residence time of the liquid molding material at the lowest viscosity point when heated is reduced and the lowest rheological viscosity during the heating and curing process of the liquid molding material is improved by the latent microencapsulated imidazole, thereby improving the flow marks caused by the high pressure outward ejection of the liquid molding material during the encapsulation and hot pressing process; the pre-gel property of the organic pre-gel microparticles is used to increase the rheological viscosity by microparticle swelling when the liquid molding material is not completely cured, to prevent the glue liquid from collapsing during encapsulation and curing, and then to improve the flow marks caused by high pressure in the low viscosity stage of the liquid molding material. The application improves the flow marks of the liquid molding material by using silica with different particle size distributions, a catalyst formed by two kinds of compounding, and organic pre-gel microparticles, so that the liquid molding material has no flow marks after encapsulation and curing, and the comprehensive performance and production yield of the encapsulated device are improved.

[0024] In some possible embodiments, the accelerator comprises an imidazole type accelerator or an amine type accelerator.

[0025] In some possible embodiments, the imidazole type accelerator comprises 2-ethyl-4-methyl imidazole, and the amine type accelerator comprises benzyl dimethyl amine.

[0026] In some possible embodiments, the product model of the latent microencapsulated imidazole is PN50.

[0027] The activity of the latent microencapsulated imidazole PN50 is inhibited at room temperature or lower temperature, so that the liquid plastic encapsulation material has a longer storage time and can be suitable for complex encapsulation processes; when the temperature is increased to a specific activation temperature, the activity of PN50 is triggered, which can greatly reduce the activation energy required for the curing reaction, thereby significantly accelerating the reaction rate between the epoxy resin and the acid anhydride curing agent. In the present application, by using the latent microencapsulated imidazole PN50 in combination with another accelerator, the initial curing temperature can be significantly reduced, and the lowest rheological viscosity during the heating and curing process of the liquid molding material can be improved, thereby inhibiting the center ejection flow mark defects of the liquid molding material during the encapsulation process.

[0028] In some possible embodiments, the product model of the organic pre-gel microparticles is F351.

[0029] In the present application, the organic pre-gel microparticles of F351 model are selected, which have a particle size of about 0.3 μm and a double-layer structure, the outer shell is glassy polymer, and the epoxy resin has good compatibility during heating to increase the viscosity of the system; the core is rubbery polymer, which can enhance the impact resistance and prevent the glue from collapsing during thermal curing, thereby inhibiting the center jet stream trace defects of the liquid molding compound during packaging.

[0030] In some possible embodiments, the anhydride curing agent includes at least one of methylhexahydrophthalic anhydride and methyltetrahydrophthalic anhydride.

[0031] In the present application, the anhydride curing agent is cured with the epoxy resin under the action of the catalyst to form a compound with a three-dimensional network structure.

[0032] Based on one overall inventive concept, the second aspect of the present application provides a method for eliminating the flow trace of a liquid molding compound, the method comprising: S1, proportionally adding each component of the raw material of the liquid molding compound of the first aspect into a stirring cup and mixing uniformly to obtain a first slurry; using a centrifugal mixer for stirring and mixing, the stirring time is 120-180 s, the revolution is 2100-2400 r / min, and the rotation is 1050-1200 r / min; S2, transferring the first slurry to a three-roll mill for dispersion treatment to obtain a second slurry; the feeding gap of the three-roll mill is 150-200 μm, and the discharging gap is 90-120 μm; S3, vacuum debubbling the second slurry to obtain a third slurry; using a centrifugal mixer for stirring and mixing, the stirring time is 60-90 s, the rotation is 75-150 r / min, and the revolution is 1500 r / min; S4, extruding the third slurry on the device to be packaged, and vacuum curing to obtain a packaged device without flow trace defects.

[0033] In the present application, first, each component is weighed according to the above-mentioned formula proportion, and mixed uniformly to obtain a first slurry; second, the first slurry is transferred to a three-roll mill for dispersion treatment, and the feeding gap of the mill is controlled to be 150-200 μm and the discharging gap is controlled to be 90-120 μm to control the particle size of the second slurry; third, the second slurry is vacuum debubbled to remove the bubbles in the slurry; finally, the third slurry is extruded on the device to be packaged by an extruder, and the third slurry flows on the device to be packaged by the synergistic effect of each component, and vacuum curing can obtain a packaged device without flow trace defects.

[0034] Based on the same inventive concept, the third aspect of the present application provides an application of the flow mark eliminating liquid molding compound of the first aspect in integrated circuit packaging.

[0035] The present application will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present application and not used to limit the scope of the present application. The experimental methods in the following examples, if no specific conditions are noted, are generally determined according to national standards. If there is no corresponding national standard, the methods are determined according to the general international standards, conventional conditions, or the conditions suggested by the manufacturers.

[0036] The raw materials used in the examples and comparative examples are as follows: Epoxy resin: alicyclic epoxy resin 8010; naphthalene type epoxy resin 2,2'-[1,6-naphthalene di(oxy methylene)] diethylene oxide; bisphenol A type epoxy resin such as 818s; Anhydride curing agent: methylhexahydrophthalic anhydride (HN7000); methyltetrahydrophthalic anhydride (2000NT); Organic pre-gel microparticle: F351; Dye: carbon black; Catalyst: 2-ethyl-4-methylimidazole (2E4MZ); benzyldimethylamine (BDMA); latent microencapsulated imidazole (PN50); The four particle size distributions of silica are shown in Table 1 below: Table 1 Silica with different particle size distributions

[0037] Example 1 The raw materials of the liquid molding compound include, in mass percentage: Silica (particle size distribution 1): 88.80%, bisphenol A type epoxy resin 818s: 5.52%, anhydride curing agent HN7000: 5.03%, organic pre-gel microparticle F351: 0.30%, catalyst PN50: 0.05%, catalyst 2E4MZ: 0.20%, carbon black: 0.10%.

[0038] Example 2 The raw materials of the liquid molding compound include, in mass percentage: Silica (particle size distribution 1): 88.89%, bisphenol A type epoxy resin 818s: 3.12%, alicyclic epoxy resin 8010: 1.67%, anhydride curing agent HN7000: 5.67%, organic pre-gel microparticle F351: 0.30%, catalyst PN50: 0.05%, catalyst 2E4MZ: 0.20%, carbon black: 0.10%.

[0039] Example 3 The raw materials of the liquid molding compound include, in mass percent: Silica (particle size distribution 1): 88.47%, naphthalene type epoxy resin: 2.68%, alicyclic epoxy resin 8010: 1.88%, acid anhydride curing agent HN7000: 6.32%, organic pre-gel fine particles F351: 0.30%, catalyst PN50: 0.05%, catalyst 2E4MZ: 0.20%, carbon black: 0.10%.

[0040] Example 4 The raw materials of the liquid molding compound include, in mass percent: Silica (particle size distribution 2): 88.47%, naphthalene type epoxy resin: 2.68%, alicyclic epoxy resin 8010: 1.88%, acid anhydride curing agent HN7000: 6.32%, organic pre-gel fine particles F351: 0.30%, catalyst PN50: 0.05%, catalyst 2E4MZ: 0.20%, carbon black: 0.10%.

[0041] Example 5 The raw materials of the liquid molding compound include, in mass percent: Silica (particle size distribution 2): 88.9%, naphthalene type epoxy resin: 4.83%, acid anhydride curing agent 2000NT: 5.62%, organic pre-gel fine particles F351: 0.30%, catalyst PN50: 0.05%, catalyst 2E4MZ: 0.2%, carbon black: 0.10%.

[0042] Example 6 The raw materials of the liquid molding compound include, in mass percent: Silica (particle size distribution 2): 88.11%, naphthalene type epoxy resin: 2.74%, alicyclic epoxy resin 8010: 1.88%, acid anhydride curing agent HN7000: 6.42%, organic pre-gel fine particles F351: 0.50%, catalyst PN50: 0.05%, catalyst 2E4MZ: 0.20%, carbon black: 0.10%.

[0043] Example 7 The raw materials of the liquid molding compound include, in mass percent: Silica (particle size distribution 2): 88.53%, naphthalene type epoxy resin: 2.70%, alicyclic epoxy resin 8010: 1.90%, acid anhydride curing agent HN7000: 6.32%, organic pre-gel fine particles F351: 0.20%, catalyst PN50: 0.05%, catalyst 2E4MZ: 0.20%, carbon black: 0.10%.

[0044] Example 8 The raw materials of the liquid molding compound include, in mass percent: Silica (particle size distribution 2): 88.53%, Naphthalene type epoxy resin: 2.70%, Cyclic aliphatic epoxy resin 8010: 1.90%, Acid anhydride curing agent HN7000: 6.32%, Organic pre-gel fine particles F351 : 0.20%, Catalyst PN50: 0.05%, Catalyst BDMA: 0.20%, Carbon black: 0.10%.

[0045] Comparative Example 1 The raw materials of the liquid molding compound included, in mass percent: Silica (particle size distribution 3): 88.80%, Bisphenol A type epoxy resin 818s: 5.52%, Acid anhydride curing agent HN7000: 5.03%, Organic pre-gel fine particles F351 : 0.30%, Catalyst PN50: 0.05%, Catalyst 2E4MZ: 0.20%, Carbon black: 0.10%.

[0046] Comparative Example 2 The raw materials of the liquid molding compound included, in mass percent: Silica (particle size distribution 4): 88.80%, Bisphenol A type epoxy resin 818s: 5.52%, Acid anhydride curing agent HN7000: 5.03%, Organic pre-gel fine particles F351 : 0.30%, Catalyst PN50: 0.05%, Catalyst 2E4MZ: 0.20%, Carbon black: 0.10%.

[0047] Comparative Example 3 The raw materials of the liquid molding compound included, in mass percent: Silica (particle size distribution 2): 88.52%, Naphthalene type epoxy resin: 2.68%, Cyclic aliphatic epoxy resin 8010: 1.88%, Acid anhydride curing agent HN7000: 6.32%, Organic pre-gel fine particles F351 : 0.30%, Catalyst 2E4MZ: 0.20%, Carbon black: 0.10%.

[0048] Comparative Example 4 The raw materials of the liquid molding compound included, in mass percent: Silica (particle size distribution 3): 88.52%, Naphthalene type epoxy resin: 2.68%, Cyclic aliphatic epoxy resin 8010: 1.88%, Acid anhydride curing agent HN7000: 6.32%, Organic pre-gel fine particles F351 : 0.30%, Catalyst 2E4MZ: 0.20%, Carbon black: 0.10%.

[0049] Comparative Example 5 The raw materials of the liquid molding compound included, in mass percent: Silica (particle size distribution 3): 88.42%, Naphthalene type epoxy resin: 2.68%, Aromatic aliphatic epoxy resin 8010: 1.88%, Acid anhydride curing agent HN7000: 6.32%, Organic pre-gel microparticles F351: 0.30%, Catalyst PN50: 0.30%, Carbon black: 0.10%.

[0050] Comparative Example 6 The raw materials of the liquid molding compound include, in mass percentage: Silica (particle size distribution 3): 88.42%, Naphthalene type epoxy resin: 2.68%, Aromatic aliphatic epoxy resin 8010: 1.88%, Acid anhydride curing agent HN7000: 6.32%, Organic pre-gel microparticles F351: 0.30%, Catalyst PN50: 0.30%, Carbon black: 0.10%.

[0051] Comparative Example 7 The raw materials of the liquid molding compound include, in mass percentage: Silica (particle size distribution 3): 88.42%, Naphthalene type epoxy resin: 2.68%, Aromatic aliphatic epoxy resin 8010: 1.88%, Acid anhydride curing agent HN7000: 6.32%, Organic pre-gel microparticles F351: 0.30%, Catalyst PN50: 0.30%, Carbon black: 0.10%.

[0052] The formulation proportions provided by the above Examples 1-8 and Comparative Examples 1-7 are prepared into liquid molding compounds according to the following experimental steps: (1) The raw materials are weighed according to the formulation proportions of the respective examples and comparative examples, and are added to a stirring cup and mixed uniformly using a centrifugal mixer, with a revolution of 2100 r / min and a rotation of 1200 r / min, and a stirring time of 180 s; (2) The uniformly mixed slurry is added to a three-roll mill for dispersion treatment, to obtain uniformly dispersed slurry, wherein the feed gap of the three-roll mill is 200 μm and the discharge gap is 90 μm; (3) The uniformly dispersed slurry is vacuum degassed by a centrifugal mixer, to obtain a liquid molding compound, wherein the revolution of the centrifugal mixer is 1500 r / min, the rotation is 150 r / min, and the stirring time is 60 s.

[0053] The liquid molding compounds prepared according to the above Examples 1-8 and Comparative Examples 1-7 are tested, with the specific testing process as follows: 1. Viscosity test: measured using a digital rotary viscometer at 25°C; 2. Warpage Test Method: 150g of liquid molding compound is extruded onto a 12-inch silicon wafer (300μm thick), covered with a release film, and placed on a carrier plate of a vacuum vulcanizing machine at 125℃. The carrier plate is controlled to close the film, a vacuum is drawn, and hot pressing is performed at 3000kN pressure with a pressing height of 300μm. After holding the pressure for 10 minutes, the sample is removed and placed in a 150℃ vacuum drying oven for curing for 1 hour. After cooling, the height of warpage between the liquid epoxy molding compound and one end of the silicon wafer is measured, which is the material warpage value. (See attached diagram) Figure 2 As shown; 3. Flow Mark Test Method: 150g of liquid molding compound is extruded onto a 12-inch glass slide (1000μm thick), covered with a release film, and placed on a vacuum vulcanizing machine carrier plate at 125℃. The carrier plate is closed with the film, a vacuum is drawn, and hot-pressed at 3000kN pressure with a pressing height of 300μm. After holding the pressure for 10 minutes, the sample is removed. The pressed sample is then ultrasonically scanned using SAT (Scanning Acoustic Tomography) to observe whether there are central jet-like flow marks and discolored flow marks at the edges on the scanned surface. (See attached image.) Figure 3 As shown.

[0054] The test results are shown in Table 2 below: Table 2 Test Results It should be further noted that the liquid molding compound provided by this invention will be extruded using an instrument in the encapsulation process. The normal operating requirements of the instrument are as follows: the viscosity of the liquid molding compound is less than 800 Pa·s; stringing will occur when the viscosity is between 800-1200 Pa·s; and an extrusion pressure alarm will be triggered when the viscosity is greater than 1200 Pa·s.

[0055] As can be seen from the table above, the formulation ratio of Example 3 is within the range defined by this invention, and the liquid molding compound prepared there are no flow marks or defects visually observed under strong light after curing. Figure 4 ) and no flow marks were found after SAT ultrasound scanning. Figure 5 In contrast, the silica with particle size distribution 3 used in Comparative Example 1 exhibited edge flow mark defects during the vacuum hot pressing process when preparing liquid molding compound (e.g., ...). Figure 6 As shown), this will affect the reliability of the packaged device; Comparative Example 3 uses a single catalyst (2E4MZ) to prepare liquid molding compound, which shows central flow mark defects during vacuum hot pressing (e.g., Figure 7 (As shown). Furthermore, in Comparative Example 7, an excessive amount of organic pregel microparticles was added. Although it exhibited low warpage and no flow marks after curing, its viscosity exceeded the instrument's operating range, easily triggering extrusion pressure alarms and consequently affecting the instrument's normal operation. Therefore, it is evident that the liquid molding compound prepared using the formulation ratio provided by this invention has a viscosity at room temperature that meets the requirements for normal instrument operation, and exhibits no flow marks after curing.

[0056] Finally, it should be noted that the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0057] While the preferred embodiments of the application have been described, additional variations and modifications can be made to the preferred embodiments by those of skill in the art once they have the benefit of the present disclosure without departing from the spirit and scope of the application. Accordingly, it is intended that the appended claims encompass all such variations and modifications as falling within the scope of the application.

[0058] Obviously, numerous modifications and variations of the present application are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims and their equivalents, the application can be practiced otherwise than as specifically described.

Claims

1. A liquid molding compound for eliminating flow marks, characterized in that, The liquid molding compound comprises the following components by weight percentage: 85%-90% silica, 4%-8% epoxy resin, 5%-8% acid anhydride curing agent, 0.2%-0.5% organic pregel microparticles, 0.2%-0.3% catalyst, and 0.1%-0.2% carbon black; The maximum particle size of the silica is less than 75 μm, and the particle size distribution of the silica is: 1.4 μm ≤ D10 ≤ 1.6 μm, 12 μm ≤ D50 ≤ 18 μm, 40 μm ≤ D90 ≤ 50 μm; The epoxy resin includes at least one of bisphenol A type epoxy resin, naphthalene type epoxy resin, and alicyclic epoxy resin; The catalyst consists of latent microencapsulated imidazole and an accelerator.

2. The liquid molding compound for eliminating flow marks according to claim 1, characterized in that, The accelerator includes imidazole-type accelerators or amine-type accelerators.

3. The liquid molding compound for eliminating flow marks according to claim 2, characterized in that, The imidazole-type accelerator includes 2-ethyl-4-methylimidazolium, and the amine accelerator includes benzyldimethylamine.

4. The liquid molding compound for eliminating flow marks according to claim 1, characterized in that, The product model of the latent microencapsulated imidazole is PN50.

5. The liquid molding compound for eliminating flow marks according to claim 1, characterized in that, The product model of the organic pregel microparticles is F351.

6. The liquid molding compound for eliminating flow marks according to claim 1, characterized in that, The anhydride curing agent includes at least one of methylhexahydrophthalic anhydride and methyltetrahydrophthalic anhydride.

7. A method for eliminating flow marks in liquid molding compound packaging, characterized in that, The method includes: S1. Add each component of the raw material of the liquid molding compound according to any one of claims 1-6 to a stirring cup in proportion and mix evenly to obtain the first slurry; S2. The first slurry is transferred to a three-roll mill for dispersion treatment to obtain the second slurry; S3. Vacuum degassing is performed on the second slurry to obtain the third slurry; S4. The third slurry is extruded onto the device to be packaged, and then cured under vacuum to obtain a packaged device without flow marks.

8. The method for eliminating flow marks in liquid molding compound packaging according to claim 7, characterized in that, In S2, the feed gap of the three-roll mill is 150-200μm, and the discharge gap is 90-120μm.

9. The method for eliminating flow marks in liquid molding compound packaging according to claim 7, characterized in that, In S3, the vacuum degassing time is 60-90 seconds.

10. The application of a flow-mark-eliminating liquid molding compound according to any one of claims 1-6 in integrated circuit packaging.

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