Heat-conducting packaging laminating film and preparation method thereof

Abstract

The invention provides a heat-conducting packaging laminating film and a preparation method thereof, the heat-conducting packaging laminating film comprises 10 wt.% to 30 wt.% of water-based resin and 70 wt.% to 90 wt.% of silver powder with solid content, and the silver powder comprises a piece of flake silver powder and a piece of spherical silver powder. The water-based resin comprises epoxy resin, a silane coupling agent and polyethylene glycol. The preparation method provided by the invention comprises the following steps of: mixing 10 to 30 weight percent of water-based resin and 70 to 90 weight percent of silver powder with solid content to obtain a mixed sizing material; grinding and dispersing the mixed rubber material by using three rollers to obtain a heat-conducting packaging laminating rubber material; and coating, forming and drying the heat-conducting packaging and laminating adhesive material to obtain the heat-conducting packaging and laminating film. The arithmetic mean roughness of the heat-conducting packaging laminating film is less than 0.35 mu m.

Description

Technical Field

[0001] The present invention relates to a packaging film material and a preparation method thereof, in particular to a thermally conductive packaging bonding film applied to wafer packaging and a preparation method thereof. Background Art

[0002] Semiconductor packaging is to cover the diced die with packaging materials after processes such as sawing, pick-up, die bonding, and wire bonding of the wafer completed in the front-end processing of the semiconductor, so as to protect the durability and service life of the completed integrated circuit (IC) components (such as chips), and is easy for wide application in circuit board assembly.

[0003] With the popularization of the 5G era, terminal electronic products are becoming more and more demanding for thin, light, short, and small applications. The related packaging technologies are gradually developing towards miniaturization, high density, and thinness. The current density increases, and the requirements for heat dissipation and insulation increase accordingly. The requirements for the thermal conductivity of packaging materials are also gradually increasing. Further, in the process of cutting small-sized products, problems such as flying materials, water seepage, edge chipping, and residual glue are extremely likely to occur.

[0004] In the existing packaging film materials, the main fillers are micron-sized SiO 2 or Al 2 O 3 powders mainly. The thermal conductivity of Al 2 O 3 powder is 17.65 W / mK. However, due to its large size, it is difficult to increase the solid content, the powder contactability is poor, it is difficult to improve the thermal conductivity of the adhesive, the thermal conductivity of the bonding film is about 0.766 W / mK, the solid content is about 70 wt.% to 80 wt.%, and the surface roughness (arithmetic mean roughness Ra) is about 1.15 μm. It is difficult to effectively bond with the wafer cutting tape, resulting in situations such as flying materials and water seepage during the cutting process.

[0005] Therefore, providing a thermally conductive packaging bonding film and a preparation method thereof to solve the technical problems of the prior art, such as improving powder contactability, reducing powder agglomeration, and reducing surface roughness, is an important topic that the inventors of this case are committed to researching. Summary of the Invention

[0006] The main object of the present invention is to provide a thermally conductive encapsulation bonding film that can be bonded to a wafer dicing tape and is applied to wafer encapsulation. It is made of a thermally conductive encapsulation bonding material. Taking the total weight of the thermally conductive encapsulation bonding material as 100 wt.%, the thermally conductive encapsulation bonding material includes: 10 wt.% to 30 wt.% of an aqueous resin, which includes an epoxy resin, a silane coupling agent, and polyethylene glycol; and silver powder with a solid content of 70 wt.% to 90 wt.%, and the silver powder includes flaky silver powder and spherical silver powder; wherein, the arithmetic mean roughness of the thermally conductive encapsulation bonding film is less than 0.35 μm.

[0007] In a specific embodiment of the present invention, the ratio of the flaky silver powder to the spherical silver powder is between 65:15 and 72.5:7.5.

[0008] In a specific embodiment of the present invention, the epoxy resin is at least one or a combination selected from bisphenol A epoxy resin, bisphenol F epoxy resin, and cyanuric acid epoxy resin.

[0009] In a specific embodiment of the present invention, the silane coupling agent is at least one or a combination selected from methacryloxy silane, epoxy silane, and isocyanate silane.

[0010] In a specific embodiment of the present invention, taking the total weight of the aqueous resin as 100 wt.%, the weight percentages of epoxy resin: silane coupling agent: polyethylene glycol are between 90 - 95 wt.%: 3 - 5 wt.%: 1 - 7 wt.%.

[0011] To achieve the above object, the present invention also provides a method for preparing a thermally conductive encapsulation bonding film, which includes: mixing 10 wt.% to 30 wt.% of an aqueous resin with silver powder having a solid content of 70 wt.% to 90 wt.% to obtain a mixed adhesive; grinding and dispersing the mixed adhesive with a three-roll mill to obtain a thermally conductive encapsulation bonding material; and coating, forming, and drying the thermally conductive encapsulation bonding material to obtain a thermally conductive encapsulation bonding film; wherein, the aqueous resin includes an epoxy resin, a silane coupling agent, and polyethylene glycol, and the silver powder includes flaky silver powder and spherical silver powder; wherein, the arithmetic mean roughness of the thermally conductive encapsulation bonding film is less than 0.35 μm.

[0012] In a specific embodiment of the present invention, the method for preparing the thermally conductive encapsulation bonding film of the present invention further includes: mixing silver powder and an aqueous solution of 5 wt% silane coupling agent in a ratio of 30 wt.%: 70 wt.% to obtain a silver aqueous solution; and subjecting the silver aqueous solution to spray drying granulation to obtain silver powder surface-modified by a silane coupling agent. Description of the Drawings

[0013] Figure 1AThe wafer cutting diagram of the thermal conductive encapsulation bonding film of Example 1;

[0014] Figure 1B The wafer cutting diagram of the thermal conductive encapsulation bonding film of Example 3;

[0015] Figure 1C The wafer cutting diagram of the thermal conductive encapsulation bonding film of Example 5;

[0016] Figure 1D The wafer cutting diagram of the encapsulation bonding film of Comparative Example 1;

[0017] Figure 2A The SEM diagram of silver powder that has not been modified by spray granulation;

[0018] Figure 2B The SEM diagram of silver powder modified by spray granulation; and

[0019] Figure 3 The first flow chart of the preparation method of the thermal conductive encapsulation bonding film of the present invention;

[0020] Figure 4 The second flow chart of the preparation method of the thermal conductive encapsulation bonding film of the present invention;

[0021] Among them, reference numerals:

[0022] S200, S400, S600: steps;

[0023] S102, S104: steps. Detailed Description of the Invention

[0024] Hereinafter, specific embodiments of the present invention will be described in detail in conjunction with the accompanying drawings. Those of ordinary skill in the art can understand the advantages and effects of the present invention through the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified and changed based on different viewpoints and applications without departing from the concept of the present invention. The following embodiments will further detail the related technical content of the present invention, but the disclosed content is not intended to limit the protection scope of the present invention.

[0025] The main object of the present invention is to provide a thermally conductive encapsulation bonding film, which is made of a thermally conductive encapsulation bonding material. Taking the total weight of the thermally conductive encapsulation bonding material as 100 wt.%, the thermally conductive encapsulation bonding material includes: 10 wt.% to 30 wt.% of an aqueous resin and 70 wt.% to 90 wt.% of silver powder with a solid content. The aqueous resin includes an epoxy resin, a silane coupling agent, and polyethylene glycol, and the silver powder includes flaky silver powder and spherical silver powder. Further, the arithmetic mean roughness of the thermally conductive encapsulation bonding film is less than 0.35 μm.

[0026] Preferably, the ratio of the flaky silver powder to the spherical silver powder is between 65:15 and 72.5:7.5.

[0027] To specifically compare the influence of the ratio of different types of silver powder on the surface roughness, in Examples 1 to 6, silver powder with a solid content of 80 wt.% was mixed with 20 wt.% of an aqueous resin to prepare a thermally conductive adhesive material. In the composition of the aqueous resin, bisphenol F type epoxy resin, epoxy group silane coupling agent, and polyethylene glycol of PEG-200 were selected, and the surface roughness was tested. The composition ratios are shown in Table 1.

[0028] As can be seen from Table 1, with the same ratio of the aqueous resin, the addition ratio of the flaky silver powder to the spherical silver powder also affects the surface roughness of the product. Preferably, the ratio is flaky:spherical = 65:15 to 72.5:7.5. Optimally, when the shape of the silver powder is in the ratio of flaky:spherical = 70:10, the best surface roughness (arithmetic mean roughness Ra) value can be presented.

[0029] Table 1

[0030]

[0031] Further, Comparative Example 1, Comparative Example 3, Example 2, and a commercially available thermally conductive encapsulation bonding film were further applied to wafer encapsulation cutting to test their effects, and the records are as shown in Table 2 below.

[0032] Table 2

[0033]

[0034] Refer to Figure 1A 、 Figure 1B 、 Figure 1C and Figure 1D , which respectively show the wafer cutting diagrams of Comparative Example 1, Comparative Example 3, Example 2, and a commercially available thermally conductive encapsulation bonding film. It can be seen that in Comparative Example 1 and Comparative Example 3, Figure 1A 、 Figure 1B there are cases of material flying or water seepage, while in Example 2, Figure 1C there is no material flying or water seepage, and the commercially available product Figure 1DThere are situations of material flying and water seepage. Such as Figure 1C It can be seen that the thermal conductive encapsulation bonding film of Example 2 has better roughness values and there will be no water seepage during cutting.

[0035] Furthermore, the spherical silver powder of the present invention can be silver powder presenting a spherical shape after spray drying granulation treatment, which can increase the contact area of the silver powder. More preferably, the spherical silver powder of the present invention is modified. First, the spherical silver powder is dissolved in an aqueous solution containing 5 wt.% of an interface active agent (such as the KBM-403 product of Shin-Etsu) to make a 30 wt.% silver solution, and then spray drying granulation is carried out to obtain the modified spherical silver powder.

[0036] Refer to Figure 2A and Figure 2B which is the surface morphology analysis of the silver powder, Figure 2A showing the SEM image of generally unmodified silver powder, while Figure 2B showing the SEM image of the silver powder after spray drying granulation modification. It can be seen that after spray drying granulation modification, the SEM image of the silver powder shows less agglomeration phenomenon and has better fluidity.

[0037] Epoxy resin has excellent electrical properties, low curing shrinkage rate, low volatile by-products, high temperature resistance, solvent resistance and other characteristics, and is widely used as a packaging material for semiconductor components.

[0038] In a specific embodiment of the present invention, the epoxy resin selected by the present invention is at least one or a combination thereof selected from bisphenol A epoxy resin, bisphenol F epoxy resin and cyanuric acid epoxy resin. More preferably, the epoxy resin of the present invention is bisphenol F epoxy resin. Specifically, bisphenol F epoxy resin is also called bisphenol F diglycidyl ether, abbreviated as BPF, which has the characteristics of low viscosity, corrosion resistance, adhesiveness, thermal stability and insulation.

[0039] Silane coupling agent is a compound composed of an organic substance and silicon. In the molecule of the silane coupling agent, there are two or more different reactive groups, which can carry out chemical reactions with inorganic materials and organic materials. Specifically, the silane coupling agent of the present invention can improve the connectivity between copper oxide and epoxy resin, avoid defects such as holes at the interface, and maintain better thermal conductivity.

[0040] In a specific embodiment of the present invention, the silane coupling agent is at least one selected from methacryloxy silane, epoxy silane, isocyanate silane or a combination thereof. More specifically, the silane coupling agent of the present invention can be a commercially available product. For example, the methacryloxy silane can be a combination of 3-methacryloxypropyl and other silanes, such as methyl dimethoxysilane, trimethoxysilane, methyl diethoxysilane, and triethoxysilane; the epoxy silane can be 2-(3,4-epoxycyclohexylethyltrimethoxysilane, (3-glycidoxypropyl)trimethoxysilane, (3-glycidoxypropyl)methyldiethoxysilane, and (3-oxypropylpropyltriethoxysilane; the isocyanate silane can be 3-isocyanatopropyltriethoxysilane.

[0041] To specifically compare the thermal conductivity differences of the thermal conductive adhesives prepared with the silane coupling agents selected in the present invention, Examples 4 to 6 of thermal conductive adhesives were prepared by mixing silver powder with a solid content of 80 wt.% and 20 wt.% of a water-based resin. The composition of the water-based resin was selected as bisphenol F type epoxy resin, epoxy silane coupling agent, and polyethylene glycol of PEG-200, and the thermal conductivity was tested. The composition and ratio of the water-based resin are shown in Table 3.

[0042] Among them, the thermal conductive encapsulation bonding film prepared with methacryloxy silane, epoxy silane, and isocyanate silane and the thermal conductive encapsulation bonding film made with epoxy silane can exhibit the best thermal conductivity. More specifically, the thermal conductive encapsulation bonding film made with (3-glycidoxypropyl)trimethoxysilane can exhibit the best thermal conductivity.

[0043] Table 3

[0044]

[0045] Polyethylene glycol (PEG) is a polymer of ethylene oxide and has wide chemical compatibility and is commonly used in industries, medicine, cosmetics and other fields. Preferably, the polyethylene glycol of the present invention can be selected from PEG-200, PEG-400, PEG-600, and more preferably, polyethylene glycol PEG-200 with an average molecular weight of 200 can be selected.

[0046] The water-based resin used in the present invention includes epoxy resin, silane coupling agent, and polyethylene glycol. In a specific embodiment of the present invention, the water-based resin has a specific ratio. Based on the total weight of the water-based resin being 100 wt.%, the weight percentages of epoxy resin: silane coupling agent: polyethylene glycol are between 90-95 wt.%: 3-5 wt.%: 1-7 wt.%.

[0047] To specifically compare the difference in the surface roughness of the aqueous resin formulation of the present invention, silver powder with a solid content of 80% was mixed with 20 wt.% of the aqueous resin to prepare Examples 7 to 15 of the thermal conductive adhesive material. The composition of the aqueous resin was selected as bisphenol F type epoxy resin, epoxy group silane coupling agent (KBM-403), and polyethylene glycol of PEG-200, and the surface roughness (Ra) was tested. The composition ratios of the aqueous resin are shown in Table 4.

[0048] Table 4

[0049]

[0050]

[0051] As can be seen from Table 4, the formulation of Example 9 has better roughness. Optimally, the weight percentages of epoxy resin: silane coupling agent: polyethylene glycol are 90 wt.%: 5 wt.%: 5 wt.%.

[0052] To achieve the above object, the present invention also provides a method for preparing a thermal conductive encapsulation bonding film. Refer to Figure 3 , which are steps S200 to S600 of the method for preparing the thermal conductive encapsulation bonding film of the present invention.

[0053] S200 Mix 10 wt.% to 30 wt.% of an aqueous resin with 70 wt.% to 90 wt.% of a solid content of silver powder to obtain a mixed adhesive material. The aqueous resin includes epoxy resin, silane coupling agent, and polyethylene glycol, and the silver powder includes a flaky silver powder and a spherical silver powder. The selection of these components is as described in the specification of the present invention and will not be elaborated here.

[0054] S400 Grind and disperse the mixed adhesive material with a three-roll mill to obtain a thermal conductive encapsulation bonding adhesive material. A three-roll mill is a machine that generates shear force by rotating three parallel rollers in opposite directions and at different speeds, so as to achieve the purpose of mixing, refining, dispersing, or making the viscosity of an object uniform.

[0055] S600 Coat, form, and dry the thermal conductive encapsulation bonding adhesive material to obtain a thermal conductive encapsulation bonding film.

[0056] In addition, refer to Figure 4 , the method for preparing the thermal conductive encapsulation bonding film of the present invention further includes pre-treatments for surface modification of the silver powder in steps S102 and S104, and is applied before steps S200, S400, and S600.

[0057] S102 mixes silver powder and an aqueous solution of 5 wt% silane coupling agent at a ratio of 30 wt%:70 wt% to obtain a silver aqueous solution. Preferably, the silane coupling agent is at least one or a combination selected from methacryloxy silane, epoxy silane, and isocyanate silane. More preferably, the silane coupling agent is an epoxy silane coupling agent, which can be (3-glycidoxypropyl) trimethoxysilane.

[0058] Specifically, the silane coupling agent for silver powder pretreatment in step S102 and the aqueous resin in step S200 can be the same or different. More preferably, the silane coupling agent for silver powder pretreatment in step S102 and the aqueous resin in step S200 are silane coupling agents with the same type of functional groups, such as silane coupling agents with epoxy groups, or the same silane coupling agent.

[0059] S104 obtains silver powder surface-modified with a silane coupling agent by spray drying and granulating the silver aqueous solution. The spray dryer uses an exhaust fan and a blower to send heated and purified air into the machine body. Another group of high-speed rotating spray heads atomizes the copper oxide aqueous solution pumped in into extremely small water droplets. The hot air combines with each other and instantly evaporates and takes away the water in the liquid, and the solid components are obtained by a collector, achieving the purpose of direct drying.

[0060] Through the surface modification in steps S102 and S104, the compatibility between the resin and silver powder particles is increased, the generation of powder agglomeration is reduced, and the surface roughness of the finished product is effectively reduced.

[0061] One beneficial effect of the present invention is that the "thermal conductive encapsulation bonding film" provided by the present invention, through the specific composition and formulation ratio of "10 wt% to 30 wt% of aqueous resin, which includes epoxy resin, silane coupling agent, and polyethylene glycol; and 70 wt% to 90 wt% of silver powder with a solid content", effectively reduces the arithmetic mean roughness of the thermal conductive encapsulation bonding film prepared by the present invention to less than 0.35 μm. Furthermore, the "thermal conductive encapsulation bonding film" of the present invention further improves the fluidity of the silver powder and increases the contact area by "the silver powder includes flaky silver powder and spherical silver powder", thereby increasing the solid content of the silver powder in the composition.

[0062] Furthermore, the thermal conductive encapsulation bonding film and its preparation method of the present invention effectively improve the powder contactability, reduce powder agglomeration, and reduce the surface roughness of the bonding film, so as to avoid situations such as flying materials and water seepage during the subsequent cutting process.

[0063] The above are only the preferred specific examples of the present invention, and thus do not limit the patent scope of the present invention. Therefore, all equivalent changes made by using the content of the present invention are equally included in the scope of the present invention, and this is hereby stated.

Claims

1. A thermally conductive encapsulation bonding film, characterized in that, it is made of a thermally conductive encapsulation bonding compound. Taking the total weight of the thermally conductive encapsulation bonding compound as 100 wt.%, the thermally conductive encapsulation bonding compound includes: 10 wt.% to 30 wt.% of an aqueous resin, which includes epoxy resin, silane coupling agent, and polyethylene glycol; and silver powder with a solid content of 70 wt.% to 90 wt.%, and the silver powder includes a flaky silver powder and a spherical silver powder; wherein, the arithmetic mean roughness of the thermally conductive encapsulation bonding film is less than 0.35 μm.

2. The thermally conductive encapsulation bonding film according to claim 1, characterized in that, the ratio of the flaky silver powder to the spherical silver powder is between 65:15 and 72.5:7.

5.

3. The thermally conductive encapsulation bonding film according to claim 1, characterized in that, the epoxy resin is at least one or a combination selected from bisphenol A epoxy resin, bisphenol F epoxy resin, and cyanuric acid epoxy resin.

4. The thermally conductive encapsulation bonding film according to claim 1, characterized in that, the silane coupling agent is at least one or a combination selected from methacryloxy silane, epoxy silane, and isocyanate silane.

5. The thermally conductive encapsulation bonding film according to claim 1, characterized in that, taking the total weight of the aqueous resin as 100 wt.%, the weight percentages of epoxy resin:silane coupling agent:polyethylene glycol are between 90 - 95 wt.%:3 - 5 wt.%:1 - 7 wt.%.

6. A preparation method of a thermally conductive encapsulation bonding film, characterized in that, it includes: mixing 10 wt.% to 30 wt.% of an aqueous resin with silver powder with a solid content of 70 wt.% to 90 wt.% to obtain a mixed compound; grinding and dispersing the mixed compound with a three-roll mill to obtain a thermally conductive encapsulation bonding compound; and coating, forming, and drying the thermally conductive encapsulation bonding compound to obtain a thermally conductive encapsulation bonding film; wherein, the aqueous resin includes epoxy resin, silane coupling agent, and polyethylene glycol, and the silver powder includes flaky silver powder and spherical silver powder; wherein, the arithmetic mean roughness of the thermally conductive encapsulation bonding film is less than 0.35 μm.

7. The preparation method of the thermally conductive encapsulation bonding film according to claim 6, characterized in that, it further includes: mixing silver powder and an aqueous solution of 5 wt.% silane coupling agent in a ratio of 30 wt.%:70 wt.% to obtain a silver aqueous solution; and spray-drying and granulating the silver aqueous solution to obtain silver powder surface-modified by a silane coupling agent.

8. The preparation method of the thermally conductive encapsulation bonding film according to claim 6, characterized in that, the ratio of the flaky silver powder to the spherical silver powder is between 65:15 and 72.5:7.

5.

9. The preparation method of the thermally conductive encapsulation bonding film according to claim 6, characterized in that, the epoxy resin is at least one or a combination selected from bisphenol A epoxy resin, bisphenol F epoxy resin, and cyanuric acid epoxy resin; the silane coupling agent is at least one or a combination selected from methacryloxy silane, epoxy silane, and isocyanate silane.

10. The preparation method of the thermally conductive encapsulation bonding film according to claim 6, characterized in that, taking the total weight of the aqueous resin as 100 wt.%, the weight percentages of epoxy resin: silane coupling agent: polyethylene glycol are between 90-95 wt.%, 3-5 wt.%, and 1-7 wt.%.

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