A selective dry film for circuit boards and preparation method thereof

Abstract

The present invention relates to a selective dry film for circuit boards and a preparation method thereof. The selective dry film for circuit boards comprises the following components: an acrylic resin, an active monomer, modified boron nitride, a hyperbranched polyether, an additive, and a solvent. The modified boron nitride is obtained by reacting a silane coupling agent, trifluoromethylacrylic acid, and glycidyl methacrylate with boron nitride. The hyperbranched polyether is a polymer of glycerol and glycidol. The present invention utilizes materials such as acrylic resin as the main component and compounding with the modified boron nitride. This improves the compatibility and stability between the components while introducing more active groups, thereby achieving a more rigid cross-linked structure. This further improves the strength of the dry film and also contributes to enhancing properties such as adhesion and precision. This is of great significance to the development and promotion of selective dry film products.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit board dry films, in particular to a selective dry film for circuit boards and a preparation method thereof. Background Art

[0002] Selective dry film for circuit boards is a photosensitive material used in the circuit board manufacturing process. Its primary function is to serve as a pattern transfer medium for selective gold plating. During the PCB manufacturing process, exposure and image development techniques enable precise selective electroless gold plating of pre-defined circuit layouts to achieve specific circuit design requirements.

[0003] With the rapid development of the electronics industry, higher requirements have been placed on the selective dry films used in circuit boards. Although the selective dry films used in circuit boards on the market can meet basic production needs, there are still some technical problems that need to be solved urgently.

[0004] First, when applying the dry film to the circuit board, poor adhesion and air bubbles are prone to occur, leading to deviations during the circuit fabrication process, affecting the circuit's precision and reliability, ultimately resulting in scrapping or rework, which increases production costs and time. Second, the adhesion between the selected dry film for circuit boards and the substrate needs to be improved. When the circuit board is subjected to mechanical stresses such as bending and stretching during the manufacturing process, the less flexible dry film may crack or partially detach. Therefore, it is necessary to prevent the separation between the selected dry film for circuit boards and the substrate. Therefore, as an important functional material in the electronics industry, selected dry film for circuit boards still faces technical issues such as air bubbles, insufficient strength, low adhesion, and insufficient resolution.

[0005] In summary, there is an urgent need to develop a new technical solution to improve the various properties of selective dry film in order to solve the shortcomings of existing technologies and meet the needs of the market and industry. Summary of the Invention

[0006] Based on this, the present invention provides a selective dry film for circuit boards and a preparation method thereof. This invention utilizes materials such as acrylic resin as the primary component, compounded with modified boron nitride. This improves the compatibility and stability between the components while introducing more active groups, resulting in a more robust cross-linked structure. This further enhances the dry film's strength and helps improve adhesion, precision, and other properties. This is of great significance to the development and promotion of selective dry film products.

[0007] One object of the present invention is to provide a selective chemical dry film for a circuit board, wherein the selective chemical dry film for a circuit board comprises the following components in parts by mass:

[0008]

[0009]

[0010] in,

[0011] The modified boron nitride is obtained by reacting a silane coupling agent, trifluoromethylacrylic acid, glycidyl methacrylate and boron nitride.

[0012] Furthermore, the hyperbranched polyether is a polymer of glycerol and glycidol.

[0013] Furthermore, the acrylic resin includes carboxyl-containing acrylic resin and polyurethane acrylate.

[0014] Furthermore, the reactive monomer is a monomer having a monofunctional or multifunctional acrylate unit.

[0015] Furthermore, the auxiliary agent is selected from one or more of an initiator, a photoinitiator, a catalyst, a cross-linking agent, a colorant, a dispersant, a leveling agent, a curing agent, and an antioxidant.

[0016] Another object of the present invention is to provide a method for preparing the above-mentioned selective dry film for circuit boards, the method comprising the following steps:

[0017] S1, mixing boron nitride and a silane coupling agent, heating and reacting to obtain an intermediate product;

[0018] S2, mixing the intermediate product, trifluoromethylacrylate, glycidyl methacrylate and an initiator, and heating and stirring the mixture under inert gas protection to obtain modified boron nitride;

[0019] S3, blending acrylic resin, active monomer, modified boron nitride, hyperbranched polyether, additives, and solvent to obtain a selected dry film mixture;

[0020] S4, applying the selected dry film mixture to a substrate, and covering it with a protective film after drying to obtain the selected dry film for the circuit board.

[0021] Furthermore, in step S1, the temperature of the heating reaction is 50-90°C.

[0022] Furthermore, the silane coupling agent is an acryloxysilane coupling agent.

[0023] Furthermore, in step S2, the temperature of the heating reaction is 60-100°C.

[0024] Furthermore, the mass ratio of the intermediate product, trifluoromethylacrylate, and glycidyl methacrylate is (3-6):(2-4):(0.5-1).

[0025] The present invention has the following beneficial effects:

[0026] The present invention provides a selective dry film for circuit boards, which is compounded from carboxyl-containing acrylic resin, polyurethane acrylate, and modified boron nitride. The modified boron nitride is first prepared by reacting hydroxylated pre-treated boron nitride with an acryloxysilane coupling agent to introduce double bonds. The modified boron nitride is then polymerized with trifluoromethylacrylate and glycidyl methacrylate, resulting in a grafted polyacrylic acid structure on the surface of the modified boron nitride. The modified boron nitride also possesses reactive groups such as carboxyl and epoxy groups, which not only improve the compatibility and affinity between the boron nitride and the acrylic resin, but also prevent defects such as agglomeration, resulting in a dry film with better surface precision. Furthermore, the aforementioned groups react with the carboxyl-containing acrylic resin and other components to form crosslinks, resulting in a network structure and enhancing the strength and stability of the dry film. Furthermore, the introduction of multiple reactive groups also helps improve adhesion to circuit boards. In particular, the surface of the modified boron nitride of the present invention also has a large number of trifluoromethyl structures. The introduction of fluorine atoms further enhances the stability and solvent resistance of the boron nitride and the dry film. At the same time, the trifluoromethyl group has a large electronegativity, which is conducive to the formation of hydroxyl groups between the modified boron nitride and with the active groups of other components, thereby enhancing the multiple properties of the dry film through intermolecular forces.

[0027] In addition, the present invention also uses a hyperbranched polyether as a component. This component first reacts with a polyurethane acrylate containing an isocyanate group to obtain an acrylate with a hyperbranched structure, and then is mixed with modified boron nitride and other components. During curing, it can be cross-linked and entangled with other components to obtain a more three-dimensional and stable three-dimensional structure. Therefore, compared with conventional linear polymers, it can more effectively improve the strength and stability of the dry film. DETAILED DESCRIPTION

[0028] In order to more clearly illustrate the technical solutions of the present invention, the following examples are given. Unless otherwise stated, the raw materials, reactions and post-processing methods mentioned in the examples are common raw materials on the market and technical methods well known to those skilled in the art.

[0029] The terms "preferred," "preferably," "more preferred," and the like, used herein, refer to embodiments of the invention that may provide certain benefits under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, nor is it intended to exclude other embodiments from the scope of the invention.

[0030] It should be understood that, except in any operating examples, or where otherwise indicated, all numbers expressing, for example, quantities of ingredients used in the specification and claims are to be understood as being modified in all instances by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and appended claims are approximations that may vary depending upon the desired properties to be obtained by the present invention.

[0031] The carboxyl-containing acrylic resin in the embodiment of the present invention is Sartomer SB520A20 (acid value 200 mgKOH / g); the polyurethane acrylate is Sartomer CN1073 NS.

[0032] The active monomers in the embodiment of the present invention are trimethylolpropane triacrylate (TMPTA) and polydipentaerythritol hexaacrylate (DPHA) in a mass ratio of 1:1.

[0033] The auxiliary agents in the embodiment of the present invention are: initiator BPO, photoinitiator 819, leveling agent isopropyl alcohol and catalyst dibutyltin dilaurate.

[0034] The solvent in the embodiment of the present invention is dibasic acid ester (DBE).

[0035] The boron nitride in the embodiment of the present invention is subjected to a hydroxylation pretreatment, comprising the following steps:

[0036] The hexagonal boron nitride was immersed in a 5 mol / L sodium hydroxide solution and ultrasonically treated for 6 hours, then placed in a high-pressure reactor at 180° C. for reaction for 24 hours, and then washed and dried to obtain a product.

[0037] The preparation method of the hyperbranched polyether in the embodiment of the present invention comprises the following steps:

[0038] 0.1 mol of glycerol and 0.01 mol of sodium methoxide were mixed, stirred and reacted at 30°C for 1.5 hours, then heated to 60°C and evacuated until no bubbles were generated in the reaction system; then 20 mL of 1,4-dioxane was added, the temperature was raised to 95°C, and 2.1 mol of glycidol was added with stirring within 10 hours. The reaction was then continued at this temperature for 5 hours, and the 1,4-dioxane was removed under reduced pressure to obtain a hyperbranched polyether.

[0039] The “parts” in the embodiments of the present invention refer to parts by mass.

[0040] Example 1

[0041] A selective dry film for circuit boards, comprising the following components in parts by mass:

[0042]

[0043] The method for preparing the selected dry film for circuit boards comprises the following steps:

[0044] S1. Using ethanol as solvent, boron nitride and KH-570 in a mass ratio of 1:0.5 were mixed, reacted at 60°C for 6 hours, and washed and dried to obtain an intermediate product;

[0045] S2. Using water as a solvent, the intermediate product, trifluoromethylacrylate, glycidyl methacrylate, and BPO in a mass ratio of 5:3:0.8:0.02 were blended, stirred at 80° C. under a nitrogen atmosphere for 12 h, and filtered, washed, and dried to obtain modified boron nitride;

[0046] S3. Blend the solvent, polyurethane acrylate, hyperbranched polyether and catalyst according to the above-mentioned mass fractions, react at 85° C. for 2 h, cool to room temperature, add carboxyl acrylic resin, active monomer, modified boron nitride, initiator, photoinitiator and leveling agent, and stir evenly to obtain a selected dry film mixture;

[0047] S4. Apply the selected dry film mixture to a PET film, dry it at 80° C., and then cover it with a PE protective film to form a sandwich structure to obtain the selected dry film for the circuit board (the thickness of the middle layer of the selected dry film is 20 μm).

[0048] Example 2

[0049] A selective dry film for circuit boards, comprising the following components in parts by mass:

[0050]

[0051]

[0052] The method for preparing the selected dry film for circuit boards comprises the following steps:

[0053] S1. Using ethanol as solvent, blend boron nitride and KH-570 in a mass ratio of 1:0.5, react at 60°C for 6 hours, and wash and dry to obtain an intermediate product;

[0054] S2. Using water as a solvent, the intermediate product, trifluoromethylacrylate, glycidyl methacrylate, and BPO in a mass ratio of 5:3:0.8:0.02 were blended, stirred at 80° C. under a nitrogen atmosphere for 12 h, and filtered, washed, and dried to obtain modified boron nitride;

[0055] S3. Blend the solvent, polyurethane acrylate, hyperbranched polyether and catalyst according to the above-mentioned mass fractions, react at 85° C. for 2 h, cool to room temperature, add carboxyl acrylic resin, active monomer, modified boron nitride, initiator, photoinitiator and leveling agent, and stir evenly to obtain a selected dry film mixture;

[0056] S4. Apply the selected dry film mixture to a PET film, dry it at 80° C., and then cover it with a PE protective film to form a sandwich structure to obtain the selected dry film for the circuit board (the thickness of the middle layer of the selected dry film is 20 μm).

[0057] Example 3

[0058] A selective dry film for circuit boards, comprising the following components in parts by mass:

[0059]

[0060] The method for preparing the selected dry film for circuit boards comprises the following steps:

[0061] S1. Using ethanol as solvent, blend boron nitride and KH-570 in a mass ratio of 1:0.5, react at 60°C for 6 hours, and wash and dry to obtain an intermediate product;

[0062] S2. Using water as a solvent, the intermediate product, trifluoromethylacrylate, glycidyl methacrylate, and BPO in a mass ratio of 5:3:0.8:0.02 were blended, stirred at 80° C. under a nitrogen atmosphere for 12 h, and filtered, washed, and dried to obtain modified boron nitride;

[0063] S3. Blend the solvent, polyurethane acrylate, hyperbranched polyether and catalyst according to the above-mentioned mass fractions, react at 85° C. for 2 h, cool to room temperature, add carboxyl acrylic resin, active monomer, modified boron nitride, initiator, photoinitiator and leveling agent, and stir evenly to obtain a selected dry film mixture;

[0064] S4. Apply the selected dry film mixture to a PET film, dry it at 80° C., and then cover it with a PE protective film to form a sandwich structure to obtain the selected dry film for the circuit board (the thickness of the middle layer of the selected dry film is 20 μm).

[0065] Comparative Example 1

[0066] A selective dry film. The difference between this comparative example and Example 1 is that step S2 is deleted, the intermediate product is used as the modified boron nitride, and the other components and preparation methods are the same as those in Example 1.

[0067] Comparative Example 2

[0068] A selective dry film, the difference between this comparative example and Example 1 is that in step S2, methyl methacrylate is used instead of trifluoromethylacrylate, and other components and preparation methods are the same as those in Example 1.

[0069] Comparative Example 3

[0070] A selective dry film, the difference between this comparative example and Example 1 is that: the hyperbranched polyether is deleted, and the other ingredients and preparation method are the same as those of Example 1.

[0071] Test Case

[0072] The performance tests were conducted on the selected dry films prepared in Examples 1-3 and Comparative Examples 1-3.

[0073] The test method is as follows:

[0074] The selected dry films prepared in the examples and comparative examples were pressed onto the surface of the copper clad laminate at a temperature of 400 mJ / cm 2 Exposure, followed by thermal curing at 150°C for 1 hour.

[0075] Adhesion: Use a needle to make an X-shape on the film. Then, apply cellophane tape to the cut and pull. The evaluation criteria are as follows:

[0076] Qualified: not torn off or a small amount torn off;

[0077] Unqualified: A lot of tearing off.

[0078] Bending resistance: With the selected dry film as the outer side, bend it 180° and evaluate it according to the following criteria:

[0079] Good: No cracks on the film;

[0080] Poor: There are cracks on the film.

[0081] Acid / Alkali Resistance: Immerse the sample in a 10wt% sulfuric acid solution or a 10wt% sodium hydroxide solution at 20°C for 30 minutes. Remove the sample and evaluate the coating's condition and adhesion. The evaluation criteria are as follows:

[0082] Pass: No change or slight change was found;

[0083] Unqualified: There is swelling or shedding on the coating film.

[0084] Heat resistance: Thermal shock performance test is conducted according to the method in IPC-SM-840E. The evaluation criteria are as follows:

[0085] Qualified: no bubbles or cracks;

[0086] Unqualified: bubbles and cracks appear.

[0087] Film removal: Immerse the sample in 5% sodium hydroxide solution at 50°C for 5 minutes. The evaluation criteria are as follows:

[0088] Qualified: Completely stripped;

[0089] Unqualified: The film cannot be removed.

[0090] The test results are shown in Table 1.

[0091] Table 1 Performance test results

[0092] project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Appearance No bubbles No bubbles No bubbles A small amount of bubbles No bubbles No bubbles Adhesion qualified qualified qualified Unqualified qualified Unqualified Bending resistance qualified qualified qualified Unqualified Unqualified Unqualified Acid resistance qualified qualified qualified qualified qualified qualified Alkali resistance qualified qualified qualified Unqualified Unqualified Unqualified Heat resistance qualified qualified qualified Unqualified Unqualified Unqualified Film removal qualified qualified qualified qualified qualified qualified

[0093] According to Table 1, the selected dry films for circuit boards prepared in the embodiments of the present invention can effectively avoid bubble defects and have excellent mechanical properties and stability. However, in Comparative Examples 1-3, the modified boron nitride or hyperbranched polyether is replaced, resulting in reduced affinity between the components, difficulty in forming a good synergistic effect, and inability to obtain a stable cross-linked structure. The flexibility and stability of the dry films are reduced, and compared with the embodiments, there are many deficiencies, and the performance improvement is less than ideal.

[0094] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

[0095] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A selective dry film for circuit boards, characterized in that: The selected dry film for circuit boards includes the following components in parts by mass: 20-40 parts of acrylic resin 1-10 parts of active monomer 5-15 parts of modified boron nitride 1-3 parts of hyperbranched polyether 1-10 parts of additives 10-30 parts of solvent; in, The modified boron nitride is obtained by reacting a silane coupling agent, trifluoromethylacrylic acid, glycidyl methacrylate and boron nitride; The acrylic resin includes carboxyl-containing acrylic resin and polyurethane acrylate; The silane coupling agent is an acryloxysilane coupling agent.

2. The selective dry film for circuit boards according to claim 1, characterized in that: The hyperbranched polyether is a polymer of glycerol and glycidol.

3. The selective dry film for circuit board according to claim 1, characterized in that: The reactive monomer is a monomer having a monofunctional or multifunctional acrylate unit.

4. The selective dry film for circuit boards according to claim 1, characterized in that: The auxiliary agent is selected from one or more of an initiator, a photoinitiator, a catalyst, a crosslinking agent, a colorant, a dispersant, a leveling agent, a curing agent, and an antioxidant.

5. The method for preparing the selective dry film for circuit boards according to any one of claims 1 to 4, characterized in that: The method for preparing the selected dry film for circuit boards comprises the following steps: S1, mixing boron nitride and a silane coupling agent, heating and reacting to obtain an intermediate product; S2, mixing the intermediate product, trifluoromethylacrylate, glycidyl methacrylate and an initiator, and heating and stirring the mixture under inert gas protection to obtain modified boron nitride; S3, blending acrylic resin, active monomer, modified boron nitride, hyperbranched polyether, additives, and solvent to obtain a selected dry film mixture; S4, applying the selected dry film mixture to a substrate, and covering it with a protective film after drying to obtain the selected dry film for the circuit board; The acrylic resin includes carboxyl-containing acrylic resin and polyurethane acrylate; The silane coupling agent is an acryloxysilane coupling agent.

6. The method for preparing a selective dry film for a circuit board according to claim 5, characterized in that: In step S1, the temperature of the heating reaction is 50-90°C.

7. The method for preparing a selective dry film for a circuit board according to claim 5, characterized in that: In step S2, the temperature of the heating reaction is 60-100°C.

8. The method for preparing a selective dry film for a circuit board according to claim 5, characterized in that: The mass ratio of the intermediate product, trifluoromethylacrylate and glycidyl methacrylate is (3-6):(2-4):(0.5-1).

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