High-strength photosensitive dry solder resist film and method for preparing the same

Abstract

The application relates to a high-strength photosensitive dry solder resist film and a preparation method thereof. The high-strength photosensitive dry solder resist film comprises the following components: acrylic resin, active monomer, modified titanium dioxide, epoxy resin, photoinitiator, additive, and solvent. The modified titanium dioxide is obtained by the following steps: first, hydroxylated titanium dioxide is reacted with isophorone diisocyanate; then, the product is reacted with 2-vinylphenol; finally, the product is polymerized with oleic acid, allyl glycidyl ether, and methyl methacrylate. The modified titanium dioxide introduces various active groups, improves the compatibility of the components, and forms a stable crosslinked structure after solidification, so that the dry solder resist film has good hardness, warpage resistance, bending resistance, and mechanical properties. In addition, the dispersant based on polyacrylate can synergize with the modified titanium dioxide to improve the various performances of the dry solder resist film.

Description

Technical Field

[0001] This invention relates to the field of solder resist dry film technology, and in particular to a high-strength photosensitive solder resist dry film and its preparation method. Background Technology

[0002] Photosensitive solder resist dry film is a functional dry film material used in the manufacture of printed circuit boards (PCBs). Its core feature is its "photosensitive curing" property—selective curing is achieved through ultraviolet (UV) light irradiation, followed by development to remove uncured areas, ultimately forming a precise solder resist pattern on the PCB surface. Photosensitive solder resist dry film is an upgraded form of traditional liquid solder resist ink, combining the ease of use of dry film with the high-precision patterning capability of photosensitive materials. It is a key material for the manufacture of high-precision PCBs (such as mobile phone motherboards and automotive electronic PCBs).

[0003] Photosensitive solder resist dry film typically has a three-layer structure, from the outside in: a protective film (outer layer), a photosensitive solder resist layer (core layer), and a substrate film (support layer). The protective film provides physical protection, preventing the middle photosensitive solder resist layer from being scratched or contaminated during storage and transportation. The photosensitive solder resist layer is responsible for photosensitive curing, solder resist insulation, and resistance to soldering heat. The substrate film provides support and positioning, offering structural strength to the dry film and facilitating the application process.

[0004] The main functions of photosensitive solder mask dry film include: insulation and short-circuit protection, covering non-pad areas on the PCB surface, isolating adjacent conductors, and preventing short circuits caused by dust, moisture, or accidental contact; heat resistance, the cured solder mask layer can withstand soldering temperatures of 260-300℃ (such as reflow soldering and wave soldering) without softening or bubbling, protecting the substrate and circuit from high-temperature damage; corrosion and wear resistance, the solder mask layer can resist the corrosion of moisture, salt, and chemical reagents (such as cleaning agents) in the environment, while reducing mechanical wear of the PCB during assembly and use; and assisting in soldering positioning: through precise "solder mask openings" (exposing the pads), it guides the component leads to precise soldering, avoiding cold solder joints and incorrect soldering.

[0005] With the rapid development of the electronics industry, although the photosensitive solder resist dry film currently on the market can meet basic production needs, there are still some technical problems that need to be solved, such as: insufficient adhesion, which causes the solder resist dry film to fall off; poor mechanical properties, which make it easy to crack when subjected to external forces such as bending, etc.

[0006] In conclusion, it is necessary to develop a new technical solution to address the shortcomings of existing technologies. Summary of the Invention

[0007] This invention provides a high-strength photosensitive solder resist dry film and its preparation method. The high-strength photosensitive solder resist dry film comprises acrylic resin, active monomers, modified titanium dioxide, etc. The modified titanium dioxide of this invention introduces various active groups, improving the compatibility of each component and forming a stable cross-linked structure, giving the solder resist dry film good hardness, anti-warping, anti-bending, and mechanical properties. Furthermore, the dispersant of this invention is based on polyacrylate, which can synergistically work with the modified titanium dioxide to jointly improve the various properties of the solder resist dry film.

[0008] The purpose of this invention is to provide a high-strength photosensitive solder resist dry film, wherein the high-strength photosensitive solder resist dry film comprises the following components in parts by weight:

[0009] 30-40 parts of acrylic resin

[0010] 5-10 parts of active monomer

[0011] 5-10 parts of modified titanium dioxide

[0012] 10-20 parts epoxy resin

[0013] 5-10 parts of photoinitiator

[0014] 0.1-3 parts of additives

[0015] Solvent 20-40 parts;

[0016] The modified titanium dioxide is obtained by first reacting hydroxylated titanium dioxide with isophorone diisocyanate, then with 2-vinylphenol, and finally polymerizing it with oleic acid, allyl glycidyl ether, and methyl methacrylate.

[0017] Furthermore, the active monomer is a monomer having a monofunctional or polyfunctional acrylate unit.

[0018] Furthermore, the additives include dispersants.

[0019] Another object of the present invention is to provide a method for preparing the high-strength photosensitive solder resist dry film, the method comprising the following steps:

[0020] S1. Hydroxylated titanium dioxide is obtained by hydroxylating titanium dioxide.

[0021] S2. Under an inert atmosphere, the hydroxylated titanium dioxide, isophorone diisocyanate, and catalyst are blended and heated and stirred to obtain intermediate product 1.

[0022] S3. Under an inert atmosphere, intermediate product 1, 2-vinylphenol, and catalyst are mixed and heated and stirred to obtain intermediate product 2.

[0023] S4. Under an inert atmosphere, the intermediate product 2, oleic acid, allyl glycidyl ether, methyl methacrylate, and initiator are mixed and heated and stirred to obtain modified titanium dioxide.

[0024] S5. The modified titanium dioxide, acrylic resin, active monomer, epoxy resin, photoinitiator, additives, and solvent are mixed and stirred to obtain a mixture.

[0025] S6. The mixture is coated onto the substrate, dried, and then covered with a protective film to obtain the high-strength photosensitive solder resist dry film.

[0026] Further, in step S2, the mass ratio of the hydroxylated titanium dioxide to isophorone diisocyanate is (1-2):(1-3).

[0027] Furthermore, in step S2, the temperature of the heating and stirring reaction is 60-80℃.

[0028] Further, in step S3, the mass ratio of the intermediate product 1,2-vinylphenol is (1-3):(0.5-3).

[0029] Furthermore, in step S3, the temperature of the heating and stirring reaction is 60-80℃.

[0030] Further, in step S4, the mass ratio of intermediate product 2, oleic acid, allyl glycidyl ether, and methyl methacrylate is (1-2):(0.5-3):(0.2-3):(0.5-3).

[0031] Furthermore, in step S4, the temperature of the heating and stirring reaction is 80-100℃.

[0032] The present invention has the following beneficial effects:

[0033] This invention provides a high-strength photosensitive solder resist dry film, the components of which include acrylic resin, active monomers, modified titanium dioxide, etc. The modified titanium dioxide of this invention is obtained by first reacting the hydroxyl groups on the surface of hydroxylated titanium dioxide with the isocyanate groups of isophorone diisocyanate to obtain intermediate product 1, then reacting the remaining isocyanate groups of intermediate product 1 with the hydroxyl groups on 2-vinylphenol to obtain intermediate product 2, and finally polymerizing intermediate product 2, oleic acid, allyl glycidyl ether, and methyl methacrylate through double bond polymerization. The modified titanium dioxide of this invention incorporates benzene rings, long alkyl chains, carboxyl groups, epoxy groups, and acrylate groups. The benzene rings possess a rigid structure, which improves properties such as hardness. The long alkyl chains can intertwine, the carboxyl groups generate intermolecular forces with other components, and the epoxy groups can react with active monomers and other components to form crosslinks, resulting in a network structure. This improves the mechanical properties of the solder resist dry film, enhancing its resistance to warping and bending, and also improves adhesion. The acrylate groups improve compatibility with acrylic resins and other components, further promoting the uniform distribution of each component.

[0034] Furthermore, the dispersant described in this invention is based on polyacrylate, which can improve the compatibility of each component and has a good combination effect with modified titanium dioxide, playing a synergistic role in promoting the uniform distribution of each component and jointly improving the various properties of the solder resist dry film. Detailed Implementation

[0035] To more clearly illustrate the technical solution of the present invention, the following embodiments are provided. Unless otherwise stated, the raw materials, reactions, and post-processing methods appearing in the embodiments are all commercially available raw materials and technical methods well known to those skilled in the art.

[0036] The terms "preferred," "more preferably," and "more suitable" used in this invention refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.

[0037] It should be understood that, except in any operational instance or otherwise indicated, the amounts or all figures representing ingredients used, for example, in the specification and claims, should be understood to be modified by the term "about" in all cases. Therefore, unless otherwise stated, the numerical parameters set forth in the following specification and appended claims are approximate values ​​varying according to the desired performance to be obtained according to the invention.

[0038] The embodiments of the present invention use the following raw materials:

[0039] The acrylic resins are Japanese Synthetic UV-7600B and Sartamomer CN115 NS in a 1:1 mass ratio.

[0040] The active monomers are trimethylolpropane triacrylate (TMPTA) and lauryl acrylate in a mass ratio of 1:1.

[0041] Titanium dioxide, model R-926, was purchased from Jiangsu Mingsheng Titanium Chemical Technology Co., Ltd.

[0042] The epoxy resin, brand name E-44, was purchased from Wuhan Jiyesheng Chemical Co., Ltd.

[0043] The photoinitiator was photoinitiator 819, purchased from Zhongshan Dixin Chemical Co., Ltd.

[0044] The additive is a dispersant, BASF Dispex® Ultra PA 4560.

[0045] The solvent is N-methyl-2-pyrrolidone.

[0046] The catalyst is dibutyltin dilaurate.

[0047] The initiator is benzoyl peroxide.

[0048] Example 1

[0049] A high-strength photosensitive solder resist dry film comprises the following components in parts by weight:

[0050] 40 parts of acrylic resin

[0051] 10 parts of active monomer

[0052] 10 parts of modified titanium dioxide

[0053] 20 parts epoxy resin

[0054] 10 parts of photoinitiator

[0055] 1 part of auxiliary agent

[0056] 40 parts solvent;

[0057] The method for preparing the high-strength photosensitive solder resist dry film includes the following steps:

[0058] S1. Heat titanium dioxide to 500℃ and calcine for 2 hours, then soak it in 2 mol / L NaOH solution, sonicate at 50℃ for 2 hours, wash and dry to obtain hydroxylated titanium dioxide;

[0059] S2. Under a nitrogen atmosphere, the hydroxylated titanium dioxide, isophorone diisocyanate, catalyst, and acetone were mixed in a mass ratio of 1:2:0.003:50, heated to 70°C and stirred for 6 hours. After centrifugation, washing, and drying, intermediate product 1 was obtained.

[0060] S3. Under a nitrogen atmosphere, intermediate product 1, 2-vinylphenol, catalyst, and acetone were mixed in a mass ratio of 3:0.5:0.003:50, heated to 70°C and stirred for 16 hours. After centrifugation, washing, and drying, intermediate product 2 was obtained.

[0061] S4. Under a nitrogen atmosphere, the intermediate product 2, oleic acid, allyl glycidyl ether, methyl methacrylate, initiator, and xylene are mixed in a mass ratio of 2:0.5:0.2:0.5:0.1:15, heated to 90°C and stirred for 10 hours. After centrifugation, washing, and drying, modified titanium dioxide is obtained.

[0062] S5. According to the above-mentioned mass proportions, the modified titanium dioxide, acrylic resin, active monomer, epoxy resin, photoinitiator, additives and solvent are mixed and stirred to obtain a mixture.

[0063] S6. The mixture is evenly coated onto a PET film using an extrusion die, and after baking at 80°C, a PE protective film is applied on top to obtain a high-strength photosensitive solder resist dry film, wherein the thickness of the intermediate layer is 20μm.

[0064] Example 2

[0065] A high-strength photosensitive solder resist dry film comprises the following components in parts by weight:

[0066] 40 parts of acrylic resin

[0067] 10 parts of active monomer

[0068] 8 parts of modified titanium dioxide

[0069] 20 parts epoxy resin

[0070] 10 parts of photoinitiator

[0071] 1 part of auxiliary agent

[0072] 35 parts solvent;

[0073] The method for preparing the high-strength photosensitive solder resist dry film includes the following steps:

[0074] S1. Heat titanium dioxide to 500℃ and calcine for 2 hours, then soak it in 2 mol / L NaOH solution, sonicate at 50℃ for 2 hours, wash and dry to obtain hydroxylated titanium dioxide;

[0075] S2. Under a nitrogen atmosphere, the hydroxylated titanium dioxide, isophorone diisocyanate, catalyst, and acetone were mixed in a mass ratio of 1:2:0.003:50, heated to 65°C and stirred for 6 hours. After centrifugation, washing, and drying, intermediate product 1 was obtained.

[0076] S3. Under a nitrogen atmosphere, intermediate product 1, 2-vinylphenol, catalyst, and acetone were mixed in a mass ratio of 3:0.5:0.003:50, heated to 70°C and stirred for 16 hours. After centrifugation, washing, and drying, intermediate product 2 was obtained.

[0077] S4. Under a nitrogen atmosphere, the intermediate product 2, oleic acid, allyl glycidyl ether, methyl methacrylate, initiator, and xylene are mixed in a mass ratio of 2:0.5:0.2:0.5:0.1:15, heated to 90°C and stirred for 10 hours. After centrifugation, washing, and drying, modified titanium dioxide is obtained.

[0078] S5. According to the above-mentioned mass proportions, the modified titanium dioxide, acrylic resin, active monomer, epoxy resin, photoinitiator, additives and solvent are mixed and stirred to obtain a mixture.

[0079] S6. The mixture is evenly coated onto a PET film using an extrusion die, and after baking at 80°C, a PE protective film is applied on top to obtain a high-strength photosensitive solder resist dry film, wherein the thickness of the intermediate layer is 20μm.

[0080] Example 3

[0081] A high-strength photosensitive solder resist dry film comprises the following components in parts by weight:

[0082] 30 parts acrylic resin

[0083] 5 parts of active monomer

[0084] 6 parts of modified titanium dioxide

[0085] 10 parts epoxy resin

[0086] 5 parts of photoinitiator

[0087] 0.8 parts of additives

[0088] 30 parts solvent;

[0089] The method for preparing the high-strength photosensitive solder resist dry film includes the following steps:

[0090] S1. Heat titanium dioxide to 500℃ and calcine for 2 hours, then soak it in 2 mol / L NaOH solution, sonicate at 50℃ for 2 hours, wash and dry to obtain hydroxylated titanium dioxide;

[0091] S2. Under a nitrogen atmosphere, the hydroxylated titanium dioxide, isophorone diisocyanate, catalyst, and acetone were mixed in a mass ratio of 1:2:0.003:50, heated to 70°C and stirred for 6 hours. After centrifugation, washing, and drying, intermediate product 1 was obtained.

[0092] S3. Under a nitrogen atmosphere, intermediate product 1, 2-vinylphenol, catalyst, and acetone were mixed in a mass ratio of 3:0.5:0.003:50, heated to 75°C and stirred for 16 hours. After centrifugation, washing, and drying, intermediate product 2 was obtained.

[0093] S4. Under a nitrogen atmosphere, the intermediate product 2, oleic acid, allyl glycidyl ether, methyl methacrylate, initiator, and xylene are mixed in a mass ratio of 2:0.5:0.2:0.5:0.1:15, heated to 90°C and stirred for 10 hours. After centrifugation, washing, and drying, modified titanium dioxide is obtained.

[0094] S5. According to the above-mentioned mass proportions, the modified titanium dioxide, acrylic resin, active monomer, epoxy resin, photoinitiator, additives and solvent are mixed and stirred to obtain a mixture.

[0095] S6. The mixture is evenly coated onto a PET film using an extrusion die, and after baking at 80°C, a PE protective film is applied on top to obtain a high-strength photosensitive solder resist dry film, wherein the thickness of the intermediate layer is 20μm.

[0096] Comparative Example 1

[0097] The difference between Comparative Example 1 and Example 1 is that oleic acid and allyl glycidyl ether in step S4 are replaced with methyl methacrylate, while the remaining components and preparation methods are the same as in Example 1.

[0098] Comparative Example 2

[0099] The difference between Comparative Example 2 and Example 1 is that the auxiliary agent is replaced with sodium dodecyl sulfate, while the remaining components and preparation methods are the same as in Example 1.

[0100] Test case

[0101] The performance of the solder resist dry films prepared in Examples 1-3 and Comparative Examples 1-2 was tested.

[0102] Test method:

[0103] The solder resist dry films prepared in Examples 1-3 and Comparative Examples 1-2 were respectively laminated onto the surface of copper-clad laminates at a pressure of 400 mJ / cm. 2 After exposure, the PE protective film is removed and developed. The film is then cured at 150°C for 1 hour to obtain the test piece.

[0104] Pencil hardness: measured based on JIS K5400.

[0105] Adhesion: Use a needle tip to draw an "X" shape on the film, then stick cellophane tape to the marks and pull it. The evaluation criteria are as follows:

[0106] Acceptable: Not torn off or only a small amount torn off;

[0107] Unacceptable: Too many pieces were torn off.

[0108] Acid / alkali resistance: At 20°C, the sample is immersed in a 10 wt% sulfuric acid solution or a 10 wt% sodium hydroxide solution for 30 minutes. After removal, the coating condition and adhesion are evaluated based on the following criteria:

[0109] Pass: No changes or slight changes were found;

[0110] Unacceptable: The coating shows swelling or swelling and peeling.

[0111] Heat resistance: Thermal shock performance was tested according to the method in IPC-SM-840E, and the evaluation criteria are as follows:

[0112] Pass: No bubbles or cracks;

[0113] Unacceptable: Bubbles or cracks appear.

[0114] Warpage: A 50×50mm section was cut from the prepared cured solder mask, and the warpage at the four corners was measured and the average value was calculated. The results were evaluated according to the following criteria:

[0115] A: Warpage is less than 0-3mm;

[0116] B: Warpage is greater than 3mm but less than 7mm;

[0117] C: Warpage is 7mm or more.

[0118] Bending performance: Cut a 50×50mm piece of the prepared cured solder resist dry film and bend it, recording the number of times before cracks appear.

[0119] The test results are shown in Table 1.

[0120] Table 1. Test results of solder resist dry film performance

[0121]

[0122] As can be seen from Table 1, the performance of the solder resist dry film of Examples 1-3 is significantly better than that of Comparative Examples 1-2. This is because the modified titanium dioxide of Comparative Example 1 did not introduce long alkyl chains, carboxyl groups, and epoxy groups, and reduced the degree of crosslinking. It also reduced the compatibility of each component, making it impossible to form an ideal crosslinking structure. As a result, the components could not form a good synergistic effect, leading to a decrease in performance. Comparative Example 2 replaced the dispersant, which reduced the synergistic effect with the modified titanium dioxide, and some properties also decreased.

[0123] 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 implemented 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 exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0124] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A high-strength photosensitive solder resist dry film, characterized in that, The mixture used to prepare the high-strength photosensitive solder resist dry film comprises the following components in parts by weight: 30-40 parts of acrylic resin 5-10 parts of active monomer 5-10 parts of modified titanium dioxide 10-20 parts epoxy resin 5-10 parts of photoinitiator 0.1-3 parts of additives Solvent 20-40 parts; The modified titanium dioxide is obtained by first reacting hydroxylated titanium dioxide with isophorone diisocyanate, then with 2-vinylphenol, and finally polymerizing it with oleic acid, allyl glycidyl ether, and methyl methacrylate. The modified titanium dioxide is obtained by first reacting the hydroxyl groups on the surface of hydroxylated titanium dioxide with the isocyanate groups of isophorone diisocyanate to obtain intermediate product 1, then reacting the remaining isocyanate groups of intermediate product 1 with the hydroxyl groups on 2-vinylphenol to obtain intermediate product 2, and finally polymerizing intermediate product 2, oleic acid, allyl glycidyl ether, and methyl methacrylate by double bond polymerization.

2. The high-strength photosensitive solder resist dry film according to claim 1, characterized in that, The active monomer is a monomer having a monofunctional or polyfunctional acrylate unit.

3. The high-strength photosensitive solder resist dry film according to claim 1, characterized in that, The additives include dispersants.

4. The method for preparing the high-strength photosensitive solder resist dry film according to any one of claims 1-3, characterized in that, The method for preparing the high-strength photosensitive solder resist dry film includes the following steps: S1. Hydroxylated titanium dioxide is obtained by hydroxylating titanium dioxide. S2. Under an inert atmosphere, the hydroxylated titanium dioxide, isophorone diisocyanate, and catalyst are blended and heated and stirred to obtain intermediate product 1. S3. Under an inert atmosphere, intermediate product 1, 2-vinylphenol, and catalyst are mixed and heated and stirred to obtain intermediate product 2. S4. Under an inert atmosphere, the intermediate product 2, oleic acid, allyl glycidyl ether, methyl methacrylate, and initiator are mixed and heated and stirred to obtain modified titanium dioxide. S5. The modified titanium dioxide, acrylic resin, active monomer, epoxy resin, photoinitiator, additives, and solvent are mixed and stirred to obtain a mixture. S6. The mixture is coated onto the substrate, dried, and then covered with a protective film to obtain the high-strength photosensitive solder resist dry film.

5. The method for preparing the high-strength photosensitive solder resist dry film according to claim 4, characterized in that, In step S2, the mass ratio of the hydroxylated titanium dioxide to isophorone diisocyanate is (1-2):(1-3).

6. The method for preparing the high-strength photosensitive solder resist dry film according to claim 4, characterized in that, In step S2, the temperature of the heating and stirring reaction is 60-80℃.

7. The method for preparing the high-strength photosensitive solder resist dry film according to claim 4, characterized in that, In step S3, the mass ratio of the intermediate product 1- and 2-vinylphenol is (1-3):(0.5-3).

8. The method for preparing the high-strength photosensitive solder resist dry film according to claim 4, characterized in that, In step S3, the temperature of the heating and stirring reaction is 60-80℃.

9. The method for preparing the high-strength photosensitive solder resist dry film according to claim 4, characterized in that, In step S4, the mass ratio of intermediate product 2, oleic acid, allyl glycidyl ether, and methyl methacrylate is (1-2):(0.5-3):(0.2-3):(0.5-3).

10. The method for preparing the high-strength photosensitive solder resist dry film according to claim 4, characterized in that, In step S4, the temperature of the heating and stirring reaction is 80-100℃.

Images