Selective dry film for circuit board and preparation method of selective dry film

Abstract

The invention relates to an selective dry film for a circuit board and a preparation method of the selective dry film. The selective dry film for the circuit board comprises the following components: acrylic resin, an active monomer, modified boron nitride, hyperbranched polyether, an auxiliary agent and a solvent, wherein the modified boron nitride is obtained by reacting a silane coupling agent, trifluoromethacrylic acid and glycidyl methacrylate with boron nitride. The hyperbranched polyether is a polymer of glycerol and glycidyl. Materials such as acrylic resin are adopted as main components and compounded with modified boron nitride, so that compatibility and stability among the components are improved, more active groups are introduced, a firmer cross-linked structure is obtained, the strength of the dry film is further improved, and improvement of properties such as adhesive force and precision is facilitated; and the method has important significance on development and popularization of selective dry film products.

Description

Technical Field

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

[0002] Selective chemical dry film for circuit boards is a photosensitive material used in the manufacturing process of circuit boards. Its main function is to serve as a pattern transfer medium in selective gold plating. In the circuit board manufacturing process, with the help of exposure and image development technology, the preset circuit layout can be selectively chemically gold plated accurately to achieve specific circuit design requirements.

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

[0004] First, when the dry film is attached to the circuit board, it is easy to have poor adhesion and bubble defects, which will lead to deviations in the circuit production process, affect the accuracy and reliability of the circuit, and eventually scrap it or require rework, thereby increasing production costs and time costs. Secondly, 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 stress such as bending and stretching during the manufacturing process, the dry film with poor flexibility may crack or partially detach. Therefore, it is necessary to prevent the peeling between the selected dry film for circuit boards and the substrate. Therefore, as an important functional material in the electronics industry, the selected dry film for circuit boards still faces technical problems such as bubbles, insufficient strength, low adhesion and insufficient resolution.

[0005] In summary, it is urgent to develop a new technical solution to improve the performance of the selected dry film to solve the deficiencies in the existing technology 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. The present invention uses acrylic resin and other materials as the main components, and compounding with modified boron nitride, while improving the compatibility and stability between the components, introduces more active groups, thereby obtaining a more rigid cross-linked structure, further improving the strength of the dry film, and also helping to improve the adhesion, precision and other properties, which 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 active 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 color powder, 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 chemical dry film for circuit boards, the method for preparing the selective chemical dry film for circuit boards 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 the protection of an inert gas to react 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 mixed solution;

[0020] S4, coating the selected dry film mixture on 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 selective dry film for circuit boards provided by the present invention is compounded with carboxyl-containing acrylic resin, polyurethane acrylate and modified boron nitride and other components. Among them, the modified boron nitride first reacts the hydroxylated pre-treated boron nitride with an acryloxysilane coupling agent to introduce double bonds, and then polymerizes with trifluoromethylacrylate and glycidyl methacrylate, thereby grafting a polyacrylic acid structure on the surface of the modified boron nitride, and at the same time has active groups such as carboxyl and epoxy groups, which not only improves the compatibility and affinity of boron nitride with acrylic resin, but also can prevent defects such as agglomeration, and promote the dry film to have better surface accuracy; it can also react with the above-mentioned groups with carboxyl-containing acrylic resin and other components to form crosslinks, thereby obtaining a network structure, and improving the strength and stability of the dry film; and the introduction of multiple active groups also helps to improve the adhesion to the circuit board. 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, which 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 solution of the present invention, the following examples are listed. Unless otherwise stated, the raw materials, reactions and post-treatment methods shown in the examples are common raw materials on the market and technical methods well known to those skilled in the art.

[0029] The words "preferred", "preferably", "more preferably", etc. in the present invention refer to embodiments of the present invention that can provide certain beneficial effects in certain circumstances. However, other embodiments may also be preferred under the same circumstances or other circumstances. In addition, the description of one or more preferred embodiments does not imply that other embodiments are not applicable, nor is it intended to exclude other embodiments from the scope of the present invention.

[0030] It should be understood that, except in any operating examples, or where otherwise indicated, all numbers indicating, for example, the amounts of ingredients used in the specification and claims should be understood to be modified in all cases by the term "about". Therefore, unless indicated to the contrary, the numerical parameters set forth in the following specification and the appended claims are approximate values ​​that vary depending on 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 hydroxylation pretreatment, comprising the following steps:

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

[0037] The method for preparing 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 the temperature was raised to 60°C and vacuumed 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, 2.1 mol of glycidol was added with stirring within 10 hours, and the reaction was 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 weight:

[0042]

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

[0044] S1. Using ethanol as solvent, blend boron nitride and KH-570 in a mass ratio of 1:0.5, react at 60°C for 6h, and wash and dry to obtain an intermediate product;

[0045] S2, using water as solvent, mixing the intermediate product, trifluoromethylacrylate, glycidyl methacrylate and BPO in a mass ratio of 5:3:0.8:0.02, stirring and reacting at 80° C. for 12 h under a nitrogen atmosphere, filtering, washing and drying to obtain modified boron nitride;

[0046] S3, according to the above mass fractions, the solvent, polyurethane acrylate, hyperbranched polyether and catalyst are mixed, reacted at 85°C for 2h, cooled to room temperature, and then carboxyl-containing acrylic resin, active monomer, modified boron nitride, initiator, photoinitiator and leveling agent are added, stirred evenly, and a selected dry film mixture is obtained;

[0047] S4, coating the selected dry film mixture on a PET film, drying at 80° C., and covering with a PE protective film to form a sandwich structure, thereby obtaining 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 weight:

[0050]

[0051]

[0052] The method for preparing the selected chemical dry film for the circuit board 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 6h, and wash and dry to obtain an intermediate product;

[0054] S2, using water as solvent, mixing the intermediate product, trifluoromethylacrylate, glycidyl methacrylate and BPO in a mass ratio of 5:3:0.8:0.02, stirring and reacting at 80° C. for 12 h under a nitrogen atmosphere, filtering, washing and drying to obtain modified boron nitride;

[0055] S3, according to the above mass fractions, the solvent, polyurethane acrylate, hyperbranched polyether and catalyst are mixed, reacted at 85°C for 2h, cooled to room temperature, and then carboxyl-containing acrylic resin, active monomer, modified boron nitride, initiator, photoinitiator and leveling agent are added, stirred evenly, and a selected dry film mixture is obtained;

[0056] S4, coating the selected dry film mixture on a PET film, drying at 80° C., and covering with a PE protective film to form a sandwich structure, thereby obtaining 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 weight:

[0059]

[0060] The method for preparing the selected chemical dry film for the circuit board 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 6h, and wash and dry to obtain an intermediate product;

[0062] S2, using water as solvent, mixing the intermediate product, trifluoromethylacrylate, glycidyl methacrylate and BPO in a mass ratio of 5:3:0.8:0.02, stirring and reacting at 80° C. for 12 h under a nitrogen atmosphere, filtering, washing and drying to obtain modified boron nitride;

[0063] S3, according to the above mass fractions, the solvent, polyurethane acrylate, hyperbranched polyether and catalyst are mixed, reacted at 85°C for 2h, cooled to room temperature, and then carboxyl-containing acrylic resin, active monomer, modified boron nitride, initiator, photoinitiator and leveling agent are added, stirred evenly, and a selected dry film mixture is obtained;

[0064] S4, coating the selected dry film mixture on a PET film, drying at 80° C., and covering with a PE protective film to form a sandwich structure, thereby obtaining 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 modified boron nitride, and the other components and preparation method 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 to replace trifluoromethylacrylate, and other components and preparation methods are the same as those in Example 1.

[0069] Comparative Example 3

[0070] A selected dry film, the difference between this comparative example and Example 1 is that: the hyperbranched polyether is deleted, and the other components 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 400 mJ / cm 2 Exposure, followed by thermal curing at 150°C for 1 hour.

[0075] Adhesion: Use a needle tip to make an "X" on the film, then stick a cellophane tape on the cut and pull it. The evaluation criteria are as follows:

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

[0077] Failure: Extensive 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 resistance / alkali resistance: At 20°C, immerse the sample in a 10wt% sulfuric acid solution or a 10wt% sodium hydroxide solution, take it out after 30 minutes, and evaluate the state and adhesion of the coating. 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 carried out according to the method in IPC-SM-840E, and 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: Complete film removal;

[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 Failure qualified Failure Bending resistance qualified qualified qualified Failure Failure Failure Acid resistance qualified qualified qualified qualified qualified qualified Alkali resistance qualified qualified qualified Failure Failure Failure Heat resistance qualified qualified qualified Failure Failure Failure Film removal qualified qualified qualified qualified qualified qualified

[0093] According to Table 1, it can be concluded that the selected dry film for circuit boards prepared in the embodiment of the present invention can effectively avoid bubble defects, and has excellent mechanical properties and stability; Comparative Examples 1-3 replace modified boron nitride or hyperbranched polyether, resulting in reduced affinity between components, and it is difficult to form a good synergistic effect, and it is impossible to obtain a stable cross-linked structure. The flexibility and stability of the dry film are reduced. Compared with the embodiments, there are more shortcomings, and the performance improvement is not 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 present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0095] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description 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 may also be appropriately combined to form other implementation modes 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 board includes the following components in parts by mass: in, The modified boron nitride is obtained by reacting a silane coupling agent, trifluoromethylacrylic acid, glycidyl methacrylate and boron nitride.

2. The selective dry film for circuit board 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 acrylic resin includes carboxyl-containing acrylic resin and polyurethane acrylate.

4. 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.

5. The selective dry film for circuit board 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 color powder, a dispersant, a leveling agent, a curing agent, and an antioxidant.

6. The method for preparing the selectively dried film for circuit board according to any one of claims 1 to 5, characterized in that: The method for preparing the selected chemical dry film for the circuit board 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 the protection of an inert gas to react 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 mixed solution; S4, coating the selected dry film mixture on a substrate, and covering it with a protective film after drying to obtain the selected dry film for the circuit board.

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

8. The method for preparing a selectively chemical dry film for a circuit board according to claim 6, characterized in that: The silane coupling agent is an acryloxysilane coupling agent.

9. The method for preparing a selectively chemical dry film for a circuit board according to claim 6, characterized in that: In step S2, the temperature of the heating reaction is 60-100°C.

10. The method for preparing a selectively chemical dry film for a circuit board according to claim 6, 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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