Photosensitive adhesive and its preparation method and application

Abstract

The present invention belongs to the technical field of polymer materials, and specifically relates to a photosensitive adhesive liquid, a preparation method thereof and an application thereof. The photosensitive adhesive liquid of the present invention comprises, by weight, 48-65 parts of a polymer, 36-50 parts of a monomer, 1-4 parts of a powder, 0.1-4 parts of an additive, and 5-25 parts of a solvent. The present invention can improve the exposure resolution of a photosensitive dry film, improve the substrate adhesion of the photosensitive dry film, reduce exposure energy, improve the exposure efficiency of the dry film, reduce the film removal time of the substrate surface, and avoid dry film residue in small holes.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a photosensitive adhesive solution and a preparation method and application thereof. Background Art

[0002] Flexible circuit board is a kind of highly reliable and extremely flexible printed circuit board made of polyimide or polyester film as the substrate, referred to as soft board or FPC. Flexible circuit board has the characteristics of high wiring density, light weight and thin thickness. With the rapid growth of demand for wearable devices, flexible displays and smart devices, the demand for flexible circuit boards has increased significantly, and flexible circuit boards are being used more and more widely.

[0003] In the context of electronic products pursuing light, thin, short and small designs, the manufacturing of flexible circuit boards requires increasingly fine line widths and increasing number of circuit board layers. In order to produce high-precision circuit graphics with a higher yield, the photosensitive dry film is required to have excellent resolution performance, high adhesion, excellent film removal ability within small holes, and high exposure efficiency, etc.

[0004] However, existing domestic photosensitive dry films have insufficient resolution and adhesion, as well as serious problems such as incomplete film removal from small holes and residual film in the holes, resulting in low product yield. Summary of the invention

[0005] The first purpose of the present invention is to provide a photosensitive adhesive solution. The second purpose of the present invention is to provide a method for preparing the photosensitive adhesive solution. The third purpose of the present invention is to provide an application of the photosensitive adhesive solution.

[0006] According to the first aspect of the present invention, a photosensitive adhesive is provided, wherein the raw materials thereof comprise, by weight, 48-65 parts of polymer, 36-50 parts of monomer, 1-4 parts of powder, 0.1-4 parts of additive, and 5-25 parts of solvent.

[0007] In some embodiments, the polymer includes a first polymer and a second polymer, wherein the first polymer is synthesized from at least one of methyl methacrylate, methacrylic acid, ethyl acrylate, and styrene; and the second polymer is synthesized from at least one of methyl methacrylate, methacrylic acid, ethyl acrylate, and ethyl methacrylate.

[0008] In some embodiments, the monomers include a first monomer, a second monomer, a third monomer, and a fourth monomer, wherein the first monomer is ethoxylated propoxylated polyurethane acrylate, and the structural formula thereof is:

[0009] ,

[0010] In the formula, Y represents ethoxy (EO), X represents propoxy (PO), R 3Represents methyl, R 4 Represents methyl, n 4 +n 7 =2~10, n 5 +n 6 =15~23;

[0011] The second monomer is ethoxylated nonylphenol acrylate, and its structural formula is:

[0012] ,

[0013] In the formula, R represents C 9 H 19 , n=2~12;

[0014] The third monomer is ethoxylated bisphenol A dimethacrylate, and its structural formula is:

[0015] ,

[0016] Where a+b=6~12;

[0017] The fourth monomer is ethoxylated bisphenol A dimethacrylate, and its structural formula is:

[0018] ,

[0019] In the formula, a+b=26~36.

[0020] In some embodiments, the powder is at least one of 2,2'-di-o-chlorophenyl-4,4',5,5'-tetraphenyl-1,2'-diimidazole, 2,2',4-tris(2-chlorophenyl)-5-(3,4-dimethoxyphenyl)-4'5'-diphenyl-1,1'-diimidazole, 9-phenylacridine, 1,7-di(9-acridinyl)heptane, 2,2-dimethoxy-phenylacetophenone, benzoin dimethyl ether, benzoin diethyl ether, tribromomethylphenyl sulfone, tetraethyl Michler's ketone, N-phenylglycine, and 9,10-dibutoxyanthracene.

[0021] In some embodiments, the additive is at least one of a first additive, a second additive, and a third additive, wherein the first additive is invisible crystal violet, the second additive is p-toluenesulfonamide, and the third additive is color powder.

[0022] In some embodiments, the solvent is at least one of methanol, toluene, acetone, and butanone.

[0023] According to a second aspect of the present invention, there is provided a method for preparing the above-mentioned photosensitive adhesive solution, comprising the following steps:

[0024] (1) Mix the solvent, powder and additive according to the ratio and dissolve them evenly to obtain a mixed solution;

[0025] (2) Add the monomer and polymer to the mixed solution obtained in step (1), stir evenly, and prepare a photosensitive adhesive solution.

[0026] According to a third aspect of the present invention, there is provided a use of the above-mentioned photosensitive adhesive in the preparation of a flexible circuit board.

[0027] According to a fourth aspect of the present invention, there is provided a photosensitive dry film, which is obtained by thermally curing the above-mentioned photosensitive adhesive solution.

[0028] The photosensitive adhesive of the present invention improves the resolution and adhesion of the dry film through a combination of functional acrylic polymers (a first polymer and a second polymer) and a combination of ethoxylated bisphenol A dimethacrylate (a third monomer and a fourth monomer); introduces a propoxy (PO) group through an ethoxylated propoxylated polyurethane acrylate monomer (a first monomer), thereby enhancing the hydrophobicity and improving the dry film residue in the small holes in the wet pressing process of the FPC flexible plate; and improves the exposure efficiency of the dry film through a combination of powder and additives.

[0029] The beneficial effects of the present invention include:

[0030] The present invention can improve the exposure resolution of the photosensitive dry film, improve the substrate adhesion of the photosensitive dry film, reduce the exposure energy, improve the exposure efficiency of the dry film, reduce the film removal time of the substrate surface, and effectively avoid the dry film residue in the small hole. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below. It is worth noting that the following examples are only for better explanation of the present invention and are not intended to limit the scope of the present invention. The undisclosed process steps in the examples are prior art. Unless otherwise specified, the following raw materials are commercially available.

[0032] The following examples are used in raw materials:

[0033] 1. Polymer

[0034] The polymer includes polymer P1 and polymer P2, wherein the raw material compositions of polymer P1 and polymer P2 are shown in Table 1:

[0035] Table 1 Raw material composition of polymer P1 and polymer P2

[0036]

[0037] The synthesis method of the polymer can be carried out according to the conventional method in the prior art. Exemplarily, the synthesis method includes the following steps:

[0038] The experimental device is filled with protective gas nitrogen, and then 100 ml of butanone is added to a 500 ml four-necked flask equipped with a heating device, a stirring paddle, a serpentine condenser, a constant pressure dropping funnel and a thermometer. The raw materials are added according to the raw material ratio in Table 1, the stirring device is turned on, and the temperature of the heating device is raised to 80 ° C. Then, under a nitrogen atmosphere, 50 ml of butanone solution containing 0.6 g of azobisisobutyronitrile is slowly added to the reaction bottle, and the dropping process lasts for about 1.5 hours. After the dropwise addition is completed, the temperature is kept warm for 4 hours. Then, 0.3 g of azobisisobutyronitrile is dissolved in 40 ml of butanone and added dropwise to the above reaction solution twice, each dropwise addition time is 15 minutes, and the second dropwise addition is carried out after the first dropwise addition is completed and kept warm for 1 hour. After the dropwise addition is completed, the temperature is kept warm for 2 hours. Then stop heating and stirring, cool to room temperature, take out the reaction solution, and obtain.

[0039] 2. Monomer

[0040] The monomers include monomer M1, monomer M2, monomer M3 and monomer M4, wherein monomer M1 is ethoxylated propoxylated polyurethane acrylate (purchased from Changzhou Qiangli Electronic New Materials Co., Ltd.), wherein one part of ethoxylated propoxylated polyurethane acrylate contains 2 parts of ethoxy (EO) and 18 parts of propoxy (PO); the structural formula of monomer M1 is:

[0041] ,

[0042] In the formula, Y represents ethoxy, X represents propoxy, and R 3 Represents methyl, R 4 Represents methyl, n 4 +n 7 =2,n 5 +n 6 =18;

[0043] The monomer M2 is (4) ethoxylated nonylphenol acrylate (purchased from Sartomer (Guangzhou) Chemical Co., Ltd.), wherein (4) represents that one part of ethoxylated nonylphenol acrylate contains four parts of ethoxy groups (EO); the structural formula of the monomer M2 is:

[0044] ,

[0045] In the formula, R represents C 9 H 19 , n=4;

[0046] The monomer M3 is (10) ethoxylated bisphenol A dimethacrylate resin (purchased from Changxing Chemical Industry (China) Co., Ltd.), wherein (10) represents that one part of ethoxylated bisphenol A dimethacrylate contains 10 parts of ethoxy groups (EO); the structural formula of the monomer M3 is:

[0047] ,

[0048] Where a+b=10;

[0049] Monomer M4 is (30) ethoxylated bisphenol A dimethacrylate resin (purchased from Sartomer (Guangzhou) Chemical Co., Ltd.), wherein (30) represents 30 parts of ethoxy groups (EO) in one part of ethoxylated bisphenol A dimethacrylate; the structural formula of monomer M4 is:

[0050] ,

[0051] In the formula, a+b=30.

[0052] 3. Powder

[0053] The powders include powder C1 and powder C2, wherein powder C1 is 2,2',4-tris(2-chlorophenyl)-5-(3,4-dimethoxyphenyl)-4'5'-diphenyl-1,1'-diimidazole (purchased from Changzhou Qiangli Electronic New Materials Co., Ltd.) or 9-phenylacridine (purchased from Changzhou Qiangli Electronic New Materials Co., Ltd.), and powder C2 is tetraethyl Michler's ketone (purchased from Changzhou Qiangli Electronic New Materials Co., Ltd.) or N-phenylglycine (purchased from West Asia Chemical Technology (Shandong) Co., Ltd.).

[0054] 4. Additives

[0055] The additives include additive A1, additive A2, and additive A3, wherein:

[0056] Additive A1: Cryptocrystalline violet (purchased from Shanghai Bailingwei Chemical Technology Co., Ltd.);

[0057] Additive A2: p-toluenesulfonamide (purchased from SIGMA-ALDRICH);

[0058] Additive A3: brilliant green powder (purchased from TCI (Shanghai) Chemical Industry Development Co., Ltd.).

[0059] The raw material compositions of the photosensitive adhesive solutions of Examples 1-8 of the present invention are shown in Table 2 below.

[0060] Table 2 Composition of the photosensitive adhesive of Examples 1-8

[0061]

[0062] Note: Powder C1 of Example 1-6 is 2,2',4-tris(2-chlorophenyl)-5-(3,4-dimethoxyphenyl)-4'5'-diphenyl-1,1'-diimidazole, and powder C2 is tetraethyl Michler's ketone. Powder C1 of Example 7-8 is 9-phenylacridine, and powder C2 is N-phenylglycine.

[0063] The preparation method of the photosensitive adhesive comprises the following steps:

[0064] (1) 20 g of solvent (Note: the solvent is a mixed solution of 5 g acetone, 5 g toluene, and 10 g methanol) is placed in a conical flask, and then powder C1, powder C2, additive A1, additive A2, and additive A3 are added to the conical flask according to the formula in Table 2, and dissolved evenly to obtain a mixed solution;

[0065] (2) According to the formula in Table 2, monomer M1, monomer M2, monomer M3 and monomer M4 were added to the above conical flask, and then polymer P1 and polymer P2 were added to the above conical flask. The mixture was stirred at about 800 rpm for about 120 minutes to prepare a photosensitive adhesive solution.

[0066] Next, in order to verify the performance of the photosensitive dry film prepared by the photosensitive adhesive solution of the present invention, the photosensitive adhesive solutions prepared in Examples 1 to 8 were respectively made into photosensitive dry films, and then the performance of the prepared photosensitive dry films was tested.

[0067] The film making and testing conditions are shown in Table 3:

[0068] Table 3 Film preparation and testing conditions

[0069]

[0070] The test results of the photosensitive dry films prepared from the photosensitive adhesives of Examples 1-8 are shown in Table 4:

[0071] Table 4 Test results of photosensitive dry film

[0072]

[0073] Note: In the table, "OK" means there is no dry film residue in the hole, and "NG" means there is dry film residue in the hole.

[0074] It can be seen from Table 4 that the dry film prepared by the photosensitive adhesive solution of Example 1 has good adhesion and resolution, low exposure energy, short film removal time, high exposure efficiency, and no dry film residue in the Φ80um hole during the FPC flexible plate wet pressing process, indicating that the dry film residue in the small hole can be effectively avoided.

[0075] When the amount of monomer M1 in the photosensitive adhesive of Example 2, Example 3, Example 4, and Example 6 is 0, the obtained dry film has dry film residues in the holes of Φ150um during the wet pressing process of the FPC flexible plate; the photosensitive adhesive of Example 2 and Example 3 uses polymer P1 or polymer P2 alone, respectively, and the adhesion and resolution of the obtained dry film are average; the weight part of monomer M1 in the photosensitive adhesive of Example 4 is 0, and the weight part of polymer is less than 48, and the obtained dry film has serious residues in the holes of Φ300um during the wet pressing process of the FPC flexible plate. The problem of residual film in the hole is serious; the weight parts of polymer in the photosensitive adhesive of Example 5 are higher than 68, and the weight parts of monomer are lower than 32. The performance values ​​of resolution and adhesion of the obtained dry film are greater than 40um, and the precision is not high. Moreover, the obtained dry film has serious dry film residue in the hole of Φ80um during the wet pressing process of the FPC flexible plate; the weight parts of monomer M3 in the photosensitive adhesive of Example 7 are 0, and the weight parts of monomer M4 in the photosensitive adhesive of Example 8 are 0. The adhesion and resolution of the obtained dry film are both above 30um, and the precision performance is not good. The exposure energy of the photosensitive dry film prepared by the photosensitive adhesive of Examples 7-8 is low, and the initiation efficiency is good, but the precision performance of the dry film is not good. There is serious dry film residue in the hole of Φ80um during the wet pressing process of the FPC flexible plate, so the overall performance is poor.

[0076] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. Photosensitive adhesive, characterized in that: The raw material composition includes, by weight: 48-65 parts of polymer, 36-50 parts of monomer, 1-4 parts of powder, 0.1-4 parts of additive and 5-25 parts of solvent; The polymer comprises a first polymer and a second polymer, wherein the first polymer is synthesized from methyl methacrylate, methacrylic acid, ethyl acrylate and styrene; and the second polymer is synthesized from methyl methacrylate, methacrylic acid, ethyl acrylate and ethyl methacrylate; The monomers include a first monomer, a second monomer, a third monomer and a fourth monomer, wherein the structural formula of the first monomer is: ， In the formula, Y represents ethoxy, X represents propoxy, R3 represents methyl, R4 represents methyl, n4+n7=2~10, n5+n6=15~23; The structural formula of the second monomer is: ， In the formula, R represents C9H 19 , n=2~12; The structural formula of the third monomer is: ， Where a+b=6~12; The structural formula of the fourth monomer is: ， Where a+b=26~36; The powder is at least one of 2,2'-di-o-chlorophenyl-4,4',5,5'-tetraphenyl-1,2'-diimidazole, 2,2',4-tris(2-chlorophenyl)-5-(3,4-dimethoxyphenyl)-4'5'-diphenyl-1,1'-diimidazole, 9-phenylacridine, 1,7-di(9-acridinyl)heptane, 2,2-dimethoxy-phenylacetophenone, benzoin dimethyl ether, benzoin diethyl ether, tribromomethylphenyl sulfone, tetraethyl Michler's ketone, N-phenylglycine, and 9,10-dibutoxyanthracene.

2. The photosensitive adhesive according to claim 1, characterized in that: The additive is at least one of a first additive, a second additive, and a third additive, wherein the first additive is latent crystal violet, the second additive is p-toluenesulfonamide, and the third additive is toner.

3. The photosensitive adhesive according to claim 1 or 2, characterized in that: The solvent is at least one of methanol, toluene, acetone and butanone.

4. The method for preparing the photosensitive adhesive according to any one of claims 1 to 3, characterized in that: The steps include: (1) Mix the solvent, powder and additive according to the ratio and dissolve them evenly to obtain a mixed solution; (2) Add the monomer and polymer to the mixed solution obtained in step (1), stir evenly, and prepare a photosensitive adhesive solution.

5. Use of the photosensitive adhesive according to any one of claims 1 to 3 in the preparation of flexible circuit boards.

6. A photosensitive dry film, characterized in that: The photosensitive adhesive is obtained by thermally curing the photosensitive adhesive according to any one of claims 1 to 3.

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