Polyurethane temporary bonding adhesive as well as preparation method and application thereof

Abstract

The invention discloses a polyurethane temporary bonding adhesive as well as a preparation method and application thereof. The polyurethane temporary bonding adhesive is prepared from the following components in parts by weight: 20 to 50 parts of reactive diluent, 40 to 70 parts of polyurethane prepolymer, 1 to 5 parts of photoinitiator and 0.1 to 1.8 parts of flatting agent, wherein the polyurethane prepolymer is prepared by reaction of a molecular chain main body, polyisocyanate, acrylate and a catalyst, and the molecular chain main body is one or a combination of at least two of a polyether-polyamide block copolymer, polyether glycol diformate, polyhydroxyalkanoate, polytetrahydrofuran, polypropylene glycol, polyethylene glycol and polyether amine. And the reactive diluent is one or a combination of at least two of ethoxy ethoxy ethyl acrylate, propylene glycol methyl ether acetate, 1, 5-pentanediol diacrylate, 1, 6-hexanediol diacrylate and butyl acrylate, and the reactive diluent is one or a combination of at least two of ethoxy ethoxy ethyl acrylate, propylene glycol methyl ether acetate, 1, 5-pentanediol diacrylate, 1, 6-hexanediol diacrylate and butyl acrylate. The bonding glue film prepared by the invention is relatively high in crosslinking density, so that the bonding glue film has excellent acid resistance and can tolerate etching of a mixed solution of nitric acid, sulfuric acid and hydrofluoric acid in a specific ratio.

Description

Technical Field

[0001] The present invention relates to the technical field of bonding adhesive preparation, and more specifically, to a polyurethane temporary bonding adhesive and a preparation method and application thereof. Background Art

[0002] To ensure chip yield during processing, thick silicon wafers are used to prevent substrate breakage. However, thick wafers make heat dissipation difficult, increase thermal stress, and increase device size. To avoid these problems, the silicon wafer is usually thinned before chip packaging, and a temporary bonding adhesive is used to temporarily bond the silicon wafer to a carrier with a certain mechanical strength. The temporary bonding adhesive needs to provide a certain degree of mechanical support for the silicon wafer during this process and withstand the tests of strong acid, high temperature, vacuum, and high pressure in subsequent processing. After the silicon wafer is processed and thinned, the temporary bonding adhesive should be able to be peeled off the silicon wafer without any residue.

[0003] CN 120158265 A discloses a silicone-based temporary bonding adhesive. Its components include a reactive diluent, vinyl rubber, vinyl silicone oil, hydrogenated silicone oil, a light-absorbing filler, a platinum catalyst, and an inhibitor. The temporary bonding adhesive prepared by this method has strong adhesion and can be separated from the supporting carrier by laser irradiation. However, the temporary bonding debonding adhesive uses silicone material, which has a strong similarity to the silicon wafer substrate, resulting in strong adhesion and relatively high peeling force. Furthermore, since no additional debonding layer is used, it may contaminate the wafer surface, requiring further cleaning of the wafer after debonding.

[0004] CN 119193060 A discloses a method for preparing a temporary bonding adhesive that exhibits excellent chemical and heat resistance, high adhesion, and ease of cleaning. However, due to the use of 60-80% reactive diluents such as alkanes, ethers, and esters, the adhesive cannot cure with the primary resin, resulting in residual organic matter after stripping, necessitating further cleaning of the wafer after debonding.

[0005] In response to the above problems in this field, this patent aims to develop a temporary bonding adhesive that can achieve low peel force, high temperature resistance, chemical resistance, clean debonding, and no need for further cleaning. Summary of the Invention

[0006] Another object of the present invention is to provide a polyurethane temporary bonding adhesive and its preparation method and application. The prepared bonding adhesive film has a high cross-linking density, which makes it have excellent acid resistance and can withstand etching by a mixed solution of nitric acid, sulfuric acid and hydrofluoric acid in a specific proportion.

[0007] In order to achieve these objects and other advantages according to the present invention, there is provided a polyurethane temporary bonding adhesive comprising the following components in parts by weight: 20-50 parts by weight of a reactive diluent, 40-70 parts by weight of a polyurethane prepolymer, 1-5 parts by weight of a photoinitiator, and 0.1-1.8 parts by weight of a leveling agent;

[0008] Among them, the polyurethane prepolymer is prepared by reacting a molecular chain body, polyisocyanate, acrylate and a catalyst, and the molecular chain body is one or a combination of at least two of polyether-polyamide block copolymer, polyether diformate glycol ester, polyhydroxyalkanoate, polytetrahydrofuran, polypropylene glycol, polyethylene glycol and polyetheramine.

[0009] Preferably, the reactive diluent is one or a combination of at least two of ethoxyethoxyethyl acrylate, propylene glycol methyl ether acetate, 1,5-pentanediol diacrylate, 1,6-hexanediol diacrylate, and butyl acrylate.

[0010] Preferably, the photoinitiator is any one of photoinitiator 184, photoinitiator 369, photoinitiator TPO, photoinitiator 1301, and photoinitiator 1173, or a combination of at least two of them.

[0011] Preferably, the leveling agent is one of byk348, byk320, byk333, byk410, or a combination of at least two of them.

[0012] Preferably, the method for preparing the polyurethane prepolymer comprises the following steps:

[0013] S1. Add the main molecular chain into the reactor and place it under vacuum to remove water at 80-120℃ for 3-8h;

[0014] S2. Mixing a polyisocyanate, an acrylate, and a catalyst in an ice-water bath and stirring for 30-120 minutes, then heating to 20-50° C. and reacting for 3-6 hours to obtain a first reactant, wherein the polyisocyanate is 0.13-0.35 times the weight of the main molecular chain, the acrylate is 0.1-0.2 times the weight of the main molecular chain, and the catalyst is 0.0002-0.0003 times the weight of the main molecular chain;

[0015] S3. Add the first reactant into the molecular chain body at 30-70°C, and react at 60-100°C for 3-6 hours to obtain a polyurethane prepolymer.

[0016] Preferably, the polyisocyanate is one or a combination of at least two of toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and polymethylene polyphenyl polyisocyanate.

[0017] Preferably, the acrylic acid ester is one or both of hydroxyethyl acrylate and hydroxyethyl methacrylate.

[0018] Preferably, the catalyst is one or a combination of at least two of dibutyltin dilaurate, stannous octoate, bismuth carboxylate, trimethylhydroxyethylpropylenediamine, and bis(dimethylaminoethyl) ether.

[0019] The present invention further provides a method for preparing a polyurethane temporary bonding adhesive, comprising the following steps:

[0020] Dissolve the photoinitiator in the active diluent, add the polyurethane prepolymer and the leveling agent to the system, stir for 4-10 hours to obtain a viscous liquid, and mature the viscous liquid in the dark at 30-100°C for 3-20 hours. After maturation, filter and let it stand to obtain a polyurethane temporary bonding adhesive.

[0021] The present invention further provides an application of a polyurethane temporary bonding adhesive in wafer processing.

[0022] The present invention has at least the following beneficial effects:

[0023] This bonding adhesive film can provide good support for the wafer. After thinning, the TTV value is <3μm. This bonding adhesive film has good high temperature resistance and can withstand baking at 175°C for 4 hours. After baking, the film can be smoothly peeled off from the surface of common semiconductor materials such as metal, PI, Si, etc. without leaving any residual adhesive. This bonding adhesive film has a high cross-linking density, which gives it excellent acid resistance and can withstand etching with a mixed solution of nitric acid, sulfuric acid, and hydrofluoric acid in a specific proportion.

[0024] Other advantages, objectives and features of the present invention will be reflected in part from the following description and will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is an infrared spectrum of the polyurethane prepolymer prepared in Example 1 of the present invention;

[0026] Figure 2 This is an infrared spectrum of the polyurethane prepolymer prepared in Example 4 of the present invention;

[0027] Figure 3 This is a GPC chart of the polyurethane prepolymer prepared in Example 4 of the present invention;

[0028] Figure 4 The results of the baking resistance test of the bonding adhesive prepared in Example 5 of the present invention are as follows;

[0029] Figure 5These are the bonding adhesives prepared in Example 3 and Example 4 of the present invention, wherein the left picture is the bonding adhesive prepared in Example 3, and the right picture is the bonding adhesive prepared in Example 4. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below with reference to the embodiments so that those skilled in the art can implement the invention with reference to the description.

[0031] The present invention provides a polyurethane temporary bonding adhesive, comprising the following components in parts by weight: 20-50 parts by weight of a reactive diluent, 40-70 parts by weight of a polyurethane prepolymer, 1-5 parts by weight of a photoinitiator, and 0.1-1.8 parts by weight of a leveling agent;

[0032] Among them, the polyurethane prepolymer is prepared by reacting a molecular chain body, polyisocyanate, acrylate and a catalyst, and the molecular chain body is one or a combination of at least two of polyether-polyamide block copolymer (PEBA), polyether dicarboxylic acid glycol ester (PEDA), polyhydroxyalkanoate (PHA), polytetramethylene glycol (PTMEG), polypropylene glycol (PPG), polyethylene glycol (PEG), and polyetheramine (PEA). In the present invention, the amount of the reactive diluent can be 20, 25, 30, 35, 40, 45, or 50 parts by weight, the amount of the polyurethane prepolymer can be 43.5, 48.5, 53.5, 58.5, 63.5, or 68.5 parts by weight, the amount of the photoinitiator can be 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, or 5 parts by weight, and the amount of the leveling agent can be 0.1, 0.3, 0.5, 0.7, 0.9, 1.1, 1.3, 1.5, 1.7, or 1.9 parts by weight.

[0033] In another technical solution, the active diluent is one or a combination of at least two of ethoxyethoxyethyl acrylate (EOEOEA), propylene glycol methyl ether acetate (PGMEA), 1,5-pentanediol diacrylate (PDDA), 1,6-hexanediol diacrylate (HDDA), and butyl acrylate (BA).

[0034] In another technical solution, the photoinitiator is one or a combination of at least two of photoinitiator 184, photoinitiator 369, photoinitiator TPO, photoinitiator 1301, and photoinitiator 1173.

[0035] In another technical solution, the leveling agent is one of byk348, byk320, byk333, byk410, or a combination of at least two of them.

[0036] In another technical solution, the preparation method of the polyurethane prepolymer comprises the following steps:

[0037] S1. Add the main molecular chain into a reactor and place it under vacuum dehydration at 80-120°C for 3-8h (the temperature can be 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, and the drying time can be 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours), and dry it in the reactor;

[0038] S2, polyisocyanate, acrylate and catalyst are mixed and stirred in an ice water bath for 30-120min (the time can be 30 minutes, 40 minutes, 50 minutes, 60 minutes, 70 minutes, 80 minutes, 90 minutes, 100 minutes, 110 minutes, 120 minutes), and then heated to 20-50°C for 3-6h (the temperature can be 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, and the time can be 3 hours, 4 hours, 5 hours, 6 hours) to obtain a first reactant, wherein the polyisocyanate is % by weight of the molecular chain main body. The amount of the acrylate is 0.13-0.35 times (which may be 0.13, 0.15, 0.17, 0.20, 0.23, 0.25, 0.28, 0.30, or 0.35 times), the amount of the acrylate is 0.1-0.2 times (which may be 0.12, 0.14, 0.16, 0.18, or 0.2 times) based on the weight of the main molecular chain, and the amount of the catalyst is 0.0002-0.0003 times (which may be 0.00020, 0.00022, 0.00024, 0.00026, 0.00028, or 0.00030 times) based on the weight of the main molecular chain;

[0039] S3. Add the first reactant to the molecular chain body (react in a reactor) at 30-70°C (the temperature can be 30°C, 40°C, 50°C, 60°C, or 70°C), and react for 3-6h (the time can be 3 hours, 4 hours, 5 hours, or 6 hours) at 60-100°C (the temperature can be 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, or 100°C) to obtain a polyurethane prepolymer.

[0040] In another technical solution, the polyisocyanate is one or a combination of at least two of toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and polymethylene polyphenyl polyisocyanate (PAPI).

[0041] In another technical solution, the acrylate is one or both of hydroxyethyl acrylate (HEA) and hydroxyethyl methacrylate (HEMA).

[0042] In another technical solution, the catalyst is one or a combination of at least two of dibutyltin dilaurate (T12), stannous octoate (T9), bismuth carboxylate (DY-20), trimethylhydroxyethylpropylenediamine (Polycat17), and bis(dimethylaminoethyl) ether (A-1).

[0043] In another technical solution, the following steps are included:

[0044] Dissolve the photoinitiator in the reactive diluent, add the polyurethane prepolymer and the leveling agent to the system, stir for 4-10 hours (the time can be 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 10 hours) to obtain a viscous liquid, and ripen the viscous liquid in the dark at 30-100°C (the temperature can be 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 100°C) for 3-20 hours (the temperature can be 3 hours, 5 hours, 7 hours, 9 hours, 11 hours, 13 hours, 15 hours, 17 hours, 19 hours). After ripening, filter and let stand to obtain a polyurethane temporary bonding adhesive.

[0045] Application of polyurethane temporary bonding adhesive in wafer processing.

[0046] The present invention is described in detail below in conjunction with the examples. It should be understood by those skilled in the art that the examples are merely for the purpose of helping to understand the present invention and should not be considered as specific limitations of the present invention. Unless otherwise specified, the raw materials in the examples of the present application were purchased from commercial sources.

[0047] Examples 1-5 and Comparative Example 1 respectively provide a temporary bonding adhesive, and the raw materials, amounts, and reaction conditions of the polyurethane prepolymers used therein are shown in Table 1. The raw materials and amounts of the bonding adhesives corresponding to Examples 1-5 and Comparative Example 1 are shown in Table 2. In Tables 1 and 2, unless otherwise noted, the unit of the amount of each component is "g";

[0048] Table 1 shows the amount of raw materials and synthesis parameters for polyurethane prepolymer synthesis

[0049]

[0050]

[0051] Table 2 shows the raw materials, dosage and reaction conditions of the bonding glue.

[0052]

[0053]

[0054] The infrared spectrum of the polyurethane prepolymer prepared by the preparation method of Example 1 is as follows: Figure 1As shown; the infrared spectrum of the polyurethane prepolymer prepared by the preparation method of Example 4 is as shown Figure 2 As shown, GPC Figure 3 As shown by Figure 3 It can be seen that the molecular weight of the polyurethane prepolymer is 3000-5000Da.

[0055] The bonding adhesive prepared by the method of Example 5 is as follows Figure 4 As shown, this indicates that the high temperature resistance of the formula is poor. This is because the sample uses too much leveling agent, which causes the cohesion of the film to decrease, and the film is pulled by thermal stress and breaks when heated.

[0056] The bonding adhesive prepared by Example 3 and Example 4 is as follows Figure 5 ( Figure 5 The left picture in the middle is the bonding glue prepared in Example 3, and the right picture is the bonding glue prepared in Example 4. As shown, since the bonding glue prepared in Example 4 has better acid resistance and is flatter, the bonding glue prepared in Example 3 has poor acid resistance, resulting in the bonding glue warping.

[0057] The acid resistance, TTV value, viscosity, residual adhesive, high temperature resistance and PI peeling force of the bonding adhesives prepared in Examples 1-5 and Comparative Example 1 were tested. The results are shown in Table 3:

[0058] Table 3 shows the test results

[0059] Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Acid resistance o o × o × × TTV value (μm) 3 4 3 3 5 / Viscosity (mPas) 4891 4631 4201 3737 3323 750 Residual glue o o × o o × High temperature resistance o × × o × × PI peeling force (N) 1.5 1.3 2.5 1.2 1.8 /

[0060] In Table 3, if the test results of acid resistance, high temperature resistance and residual adhesive are excellent or good, they are evaluated as "○"; if the test results are defective or poor, they are evaluated as "×".

[0061] As shown in Table 3, due to the differences in the prepolymers used during the synthesis process, excessive NCO groups were retained at the end of the synthesis in Comparative Example 1, resulting in severe adhesive residue and difficulty in film formation. Consequently, TTV measurement was difficult and the overall performance was very poor. Comparing the other samples, the viscosity increased with the ratio of prepolymer to reactive diluent, and the TTV values ​​were all within an acceptable range. Examples 1 and 4 both met the application requirements for acid resistance, adhesive residue, and high temperature resistance. The viscosity varied, and the method could be selected based on the application needs. Although the methods differed, they could meet the needs of different application scenarios. The main reason for this difference is the different ratios of reactive diluent to prepolymer: the more reactive diluent, the lower the viscosity. Examples 2 and 5 had poor high-temperature resistance but strong adhesion. This is primarily due to the differences in the molecular structure of the prepolymers used. The amount of isocyanate used was higher than the stoichiometric amount, resulting in residual NCO groups and improved adhesion. The poor acid resistance of Example 2 was primarily due to the insufficient photoinitiator and dosage to provide sufficient crosslinking density.

[0062] In Example 3, due to the stronger adhesive force, it has caused difficulty in peeling off the film, and residual glue appears during the peeling process.

[0063] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. Polyurethane temporary bonding adhesive, characterized in that: The method comprises the following components in parts by weight: 20-50 parts by weight of a reactive diluent, 40-70 parts by weight of a polyurethane prepolymer, 1-5 parts by weight of a photoinitiator, and 0.1-1.8 parts by weight of a leveling agent; Among them, the polyurethane prepolymer is prepared by reacting a molecular chain body, polyisocyanate, acrylate and a catalyst, and the molecular chain body is one or a combination of at least two of polyether-polyamide block copolymer, polyether diformate glycol ester, polyhydroxyalkanoate, polytetrahydrofuran, polypropylene glycol, polyethylene glycol and polyetheramine.

2. The polyurethane temporary bonding adhesive according to claim 1, characterized in that: The active diluent is one or a combination of at least two of ethoxyethoxyethyl acrylate, propylene glycol methyl ether acetate, 1,5-pentanediol diacrylate, 1,6-hexanediol diacrylate, and butyl acrylate.

3. The polyurethane temporary bonding adhesive according to claim 1, characterized in that: The photoinitiator is any one of photoinitiator 184, photoinitiator 369, photoinitiator TPO, photoinitiator 1301, and photoinitiator 1173, or a combination of at least two of them.

4. The polyurethane temporary bonding adhesive according to claim 1, characterized in that: The leveling agent is one of byk348, byk320, byk333, and byk410, or a combination of at least two of them.

5. The polyurethane temporary bonding adhesive according to claim 1, characterized in that: The preparation method of the polyurethane prepolymer comprises the following steps: S1. Add the main molecular chain into the reactor and place it under vacuum to remove water at 80-120℃ for 3-8h; S2. Mixing a polyisocyanate, an acrylate, and a catalyst in an ice-water bath and stirring for 30-120 minutes, then heating to 20-50° C. and reacting for 3-6 hours to obtain a first reactant, wherein the polyisocyanate is 0.13-0.35 times the weight of the main molecular chain, the acrylate is 0.1-0.2 times the weight of the main molecular chain, and the catalyst is 0.0002-0.0003 times the weight of the main molecular chain; S3. Add the first reactant into the molecular chain body at 30-70°C, and react at 60-100°C for 3-6 hours to obtain a polyurethane prepolymer.

6. The polyurethane temporary bonding adhesive according to claim 5, characterized in that: The polyisocyanate is one or a combination of at least two of toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and polymethylene polyphenyl polyisocyanate.

7. The polyurethane temporary bonding adhesive according to claim 5, characterized in that: The acrylate is one or both of hydroxyethyl acrylate and hydroxyethyl methacrylate.

8. The polyurethane temporary bonding adhesive according to claim 5, characterized in that: The catalyst is one or a combination of at least two of dibutyltin dilaurate, stannous octoate, bismuth carboxylate, trimethylhydroxyethylpropylenediamine, and bis(dimethylaminoethyl) ether.

9. The method for preparing the polyurethane temporary bonding adhesive according to any one of claims 1 to 8, characterized in that: The following steps are involved: Dissolve the photoinitiator in the active diluent, add the polyurethane prepolymer and the leveling agent to the system, stir for 4-10 hours to obtain a viscous liquid, and mature the viscous liquid in the dark at 30-100°C for 3-20 hours. After maturation, filter and let it stand to obtain a polyurethane temporary bonding adhesive.

10. Use of the polyurethane temporary bonding adhesive according to any one of claims 1 to 8 in wafer processing.

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