Photosensitive composition, photosensitive cover film, circuit board and preparation method thereof

Abstract

The present invention provides a photosensitive composition, a photosensitive cover film, a circuit board and a preparation method thereof. In parts by weight, the photosensitive composition comprises: 40 to 60 parts of a carboxylated resin polymer, 12.5 to 15.5 parts of an alkali-soluble resin, 1.5 to 4.0 parts of a photoinitiator, 20 to 40 parts of a metal ion source, and 0.1 to 1.9 parts of a reducing agent, based on the metal ions in the metal ion source; wherein the reducing agent reduces the metal ions in the metal ion source to metal under light or heating conditions, and the acid value of the alkali-soluble resin is 70 to 100 KOH / (mg / g). The above-mentioned photosensitive composition can form a conductive metal thin layer with excellent conductivity and strength. Subsequently, the required thickness of the circuit board can be achieved by electroplating copper, avoiding the waste of copper foil and the pollution of etching solution due to etching, which simplifies the process and reduces costs.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit board preparation, and in particular to a photosensitive composition, a photosensitive cover film, a circuit board and a preparation method thereof. Background Art

[0002] As electronic products such as smartphones and laptops gradually develop towards being thinner, lighter and shorter, the internal components of electronic products tend to be smaller in size or have more components in order to increase the application flexibility of the internal space of electronic products and achieve higher density. Therefore, the demand for flexible circuit boards with finer lines is also increasing.

[0003] Known flexible circuit boards are all processed from a semi-finished product of a precursor substrate, on which a metal conductive layer needs to be coated first to facilitate subsequent processing and manufacturing. Generally speaking, the surface of these substrate materials is difficult to be attached by metal. For this reason, well-known methods of attaching metal to the surface of substrate materials include metal spraying, sputtering, CVD, evaporation, and dry plating. However, these methods are prone to problems such as thick thickness of the semi-finished product of the precursor substrate, difficulty in plating, or long plating time. Too high thickness will be detrimental to the trend of product miniaturization, and long plating time will lead to limited capacity improvement and increased costs. In addition, when making circuits, known processes must use a large number of etching techniques to form circuit configurations, which results in most of the material being wasted due to etching, which not only increases costs but also pollutes the environment.

[0004] Therefore, the polymer metallization process can alleviate the above problems to a certain extent. Its process flow includes steps such as degreasing, ring opening, catalyst, reduction, nickel plating, copper plating, etc. However, its overall process flow is complicated, the production yield is low, and the production cost is high. In addition, in the process of degreasing and ring opening the polymer substrate to form OH groups and carboxyl groups, the structure of the polymer substrate is easily destroyed, thereby destroying the performance of the polymer substrate. Summary of the invention

[0005] The main purpose of the present invention is to provide a photosensitive composition, a photosensitive cover film, a circuit board and a preparation method thereof, so as to solve the problem of complex preparation process and high cost of thin and light flexible circuit boards in the prior art.

[0006] To achieve the above object, according to one aspect of the present invention, a photosensitive composition is provided, which comprises, by weight: 40 to 60 parts of a carboxylated resin polymer, 12.5 to 15.5 parts of an alkali-soluble resin, 1.5 to 4.0 parts of a photoinitiator, 20 to 40 parts of a metal ion source, and 0.1 to 1.9 parts of a reducing agent, based on the metal ions in the metal ion source; wherein the reducing agent reduces the metal ions in the metal ion source to metals under light or heating conditions, and the acid value of the alkali-soluble resin is 70 to 100 KOH / (mg / g).

[0007] Furthermore, the weight ratio of the above-mentioned carboxylated resin polymer to the metal ion source is 3:2 to 3:1, the acid value of the carboxylated resin polymer is 80 to 200 KOH / (mg / g), and the carboxylated resin polymer is preferably selected from any one or more of carboxylated polyurethane and carboxylated polyimide resins; the carboxylated resin polymer is preferably polyurethane and / or carboxylated polyamide imide; and / or the metal ion source is selected from any one or more of water-soluble silver salts, water-soluble copper salts, water-soluble palladium salts, water-soluble gold salts and water-soluble nickel salts, and / or the alkali-soluble resin is an epoxy acrylic resin, and the epoxy acrylic resin is preferably selected from any one or more of carboxylic acid-modified bisphenol A epoxy resin, carboxylic acid-modified bisphenol F epoxy resin, carboxylic acid-modified phenolic epoxy resin, and carboxylic acid-modified o-cresol epoxy resin. The weight ratio of the carboxylated resin polymer to the alkali-soluble resin is preferably 3 to 4.5:1.

[0008] Further, the above-mentioned photoinitiator is selected from any one or more of 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-[4-(2-hydroxy)-phenyl]-3-hydroxy-2-methyl-1-propanone-1-one, 2-methyl-1-(4-methylthiophenyl)-2-morpholine-1-propanone, 2-phenylbenzyl-2-dimethylamine-1-(4-morpholinebenzylphenyl)butanone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl ester.

[0009] Furthermore, the reducing agent is sodium borohydride and / or vitamin C.

[0010] According to another aspect of the present invention, a photosensitive cover film is provided. The photosensitive cover film comprises a photosensitive layer and a polymer substrate layer stacked in sequence. The polymer substrate layer comprises a polymer material. The photosensitive layer is obtained by curing the above-mentioned photosensitive composition.

[0011] According to another aspect of the present invention, a method for preparing a circuit board is provided, the method comprising: step S1, coating a photosensitive colloid on a polymer substrate layer to obtain a photosensitive substrate layer; step S2, covering the photosensitive layer of the photosensitive substrate layer with a mask plate and then performing exposure and development treatment to obtain a circuit board, the photosensitive colloid comprising the above-mentioned photosensitive composition.

[0012] Furthermore, the preparation method further comprises: using the circuit board as a cathode, copper plating is performed on the circuit surface of the circuit board under the action of an external anode and a copper sulfate electroplating solution.

[0013] Furthermore, the intensity of the exposure is 200-600 mJ, and the time is 30-60 seconds. Preferably, step S1 also includes a thermal curing process between the exposure and development treatments, and the thermal curing temperature is 150-230° C. and the time is 0.5-2 hours.

[0014] Furthermore, the above-mentioned polymer substrate layer includes a polymer material, and preferably the polymer material is selected from any one or more of polyethylene terephthalate, polyethylene naphthalate, polyparaphenylene terephthalamide, and polyimide resin. Preferably, the polymer material is polyimide resin, and the thickness of the polymer substrate layer is 12.5 to 50 μm, preferably 12.5 to 20 μm.

[0015] According to another aspect of the present invention, a circuit board is provided. The circuit board is prepared by the above-mentioned preparation method.

[0016] By applying the technical solution of the present invention, the carboxylate radicals generated by the carboxylated resin polymer and the metal ions in the metal ion source undergo a chemical reaction of coordination, and the alkali-soluble resin with the acid value in the above range helps to synergistically promote the coordination of the carboxylate radicals with the metal ions in the metal ion source, thereby better and more evenly fixing the metal ions in the photosensitive layer, thereby ensuring that when the circuit board is prepared by exposure and development, on the one hand, the circuit is formed by ultraviolet irradiation, and on the other hand, the metal ions in the metal ion source are concentratedly reduced and loaded on a certain resin carrier, and the alkali-soluble resin is photocured into a polymer with a higher molecular weight under the conditions of a photoinitiator and light, thereby facilitating the improvement of the strength of the obtained conductive metal thin layer, and forming a conductive metal thin layer with both excellent conductivity and strength. Subsequently, the required thickness of the circuit board can be achieved by electroplating copper, avoiding the waste of copper foil and the pollution of etching solution due to etching, which simplifies the process and reduces the cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0018] Figure 1 A schematic diagram of a photosensitive cover film of the present application is shown;

[0019] Figure 2 A schematic structural diagram of a circuit board is shown;

[0020] Figure 3 A schematic structural diagram of a circuit board after copper plating is shown.

[0021] The above drawings include the following reference numerals:

[0022] 1. Photosensitive layer; 2. Polymer substrate layer; 3. Circuit; 4. Copper plating layer. DETAILED DESCRIPTION

[0023] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0024] As analyzed in the background technology, the thin and light flexible circuit boards in the prior art have the problems of complex preparation process and high cost. To solve this problem, the present invention provides a photosensitive composition, a photosensitive cover film, a circuit board and a preparation method thereof.

[0025] In a typical embodiment of the present application, a photosensitive composition is provided, which includes, by weight: 40 to 60 parts of a carboxylated resin polymer, 12.5 to 15.5 parts of an alkali-soluble resin, 1.5 to 4.0 parts of a photoinitiator, 20 to 40 parts of a metal ion source, and 0.1 to 1.9 parts of a reducing agent, based on the metal ions in the metal ion source; wherein the reducing agent reduces the metal ions in the metal ion source to metals under light or heating conditions, and the acid value of the alkali-soluble resin is 70 to 100 KOH / (mg / g).

[0026] In addition, the weight of the carboxylated resin polymer can be 40 parts, 45 parts, 48 ​​parts, 49 parts, 50 parts, 52 parts, 53 parts, 55 parts, 60 parts, etc., preferably 40 parts, 48 ​​parts, 49 parts, 52 parts, 53 parts, 60 parts; the weight of the alkali-soluble resin can be 12.5 parts, 13 parts, 13.5 parts, 14 parts, 15 parts, 15.5 parts, etc., preferably 12.5 parts, 15 parts, 15.5 parts; the weight of the gold The weight portion of the metal ion source can be 20 parts, 25 parts, 27 parts, 28 parts, 30.5 parts, 32 parts, 35 parts, 40 parts, etc., preferably 20 parts, 27 parts, 30.5 parts, 32 parts, 40 parts, the weight portion of the above-mentioned photoinitiator can be 1.5 parts, 2 parts, 2.5 parts, 3 parts, 4 parts, etc., preferably 4 parts; the weight portion of the above-mentioned reducing agent can be 0.1 parts, 0.5 parts, 1 parts, 1.5 parts, 1.9 parts, etc., preferably 1 part. Specifically, those skilled in the art can select the weight portions of each component within the range of each component according to actual conditions, and will not be repeated here.

[0027] The carboxylate radicals produced by the carboxylated resin polymer and the metal ions in the metal ion source are coordinated chemically, and the alkali-soluble resin with the acid value in the above range helps to synergistically promote the coordination between the carboxylate radicals and the metal ions in the metal ion source, thereby better and more evenly fixing the metal ions in the photosensitive layer, thereby ensuring that when the circuit board is prepared by exposure and development, the ultraviolet light is irradiated, on the one hand, the circuit is formed, and on the other hand, the metal ions in the metal ion source are concentratedly reduced and loaded on a certain resin carrier. The alkali-soluble resin is photocured into a polymer with a higher molecular weight under the conditions of a photoinitiator and light, which is conducive to improving the strength of the obtained conductive metal thin layer and forming a conductive metal thin layer with excellent conductivity and strength. Subsequently, the required thickness of the circuit board can be achieved by electroplating copper, avoiding the waste of copper foil and the pollution of etching solution due to etching, which simplifies the process and reduces costs.

[0028] Preferably, the weight ratio of the carboxylated resin polymer to the metal ion source is 3:2 to 3:1, which is beneficial to improve the immobilization effect of the carboxylated resin polymer and the metal ion source. Preferably, the acid value of the carboxylated resin polymer is 80 to 200 KOH / (mg / g). Preferably, the carboxylated resin polymer is selected from any one or more of carboxylated polyurethane and carboxylated polyimide resins; preferably, the carboxylated resin polymer is polyurethane and / or carboxylated polyamideimide; thereby, it is beneficial to concentrate the metal ion source as much as possible, thereby helping to form a highly conductive conductive metal thin layer. Preferably, the metal ion source is selected from any one or more of water-soluble silver salts, water-soluble copper salts, water-soluble palladium salts, water-soluble gold salts and water-soluble nickel salts, because they are more active and easier to be reduced.

[0029] In order to further improve the curing efficiency of the alkali-soluble resin, the alkali-soluble resin is preferably an epoxy acrylic resin, and the epoxy acrylic resin is preferably selected from any one or more of carboxylic acid-modified bisphenol A epoxy resin, carboxylic acid-modified bisphenol F epoxy resin, carboxylic acid-modified phenolic epoxy resin, and carboxylic acid-modified o-cresol epoxy resin. For example, ZAR-1035, ZAR-2000, ZAR-1000, ZFR-1491H, CCR-1291H, CCR-1235, etc. of Nippon Kayaku. The carboxyl functional group of the alkali-soluble resin itself can also capture metal ions. The weight ratio of the carboxylated resin polymer to the alkali-soluble resin is preferably 3 to 4.5:1, which is conducive to the synergistic effect of the two. After exposure, curing and heating, the formed metal element particles are more evenly distributed in the photosensitive layer, thereby obtaining a conductive metal thin layer that takes into account both its strength and conductivity.

[0030] In addition, the carboxylated resin polymer and the alkali-soluble resin themselves and their polymers are not conductive. The preferred weight ratio of the above-mentioned carboxylated resin polymer to the metal ion source and the preferred weight ratio of the carboxylated resin polymer to the alkali-soluble resin are beneficial for obtaining a conductive metal thin layer with the highest possible conductivity and strength under the same weight of the photosensitive composition without causing waste of the carboxylated resin polymer and the alkali-soluble resin.

[0031] Preferably, the photoinitiator is selected from any one or more of 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-[4-(2-hydroxy)-phenyl]-3-hydroxy-2-methyl-1-propanone-1-one, 2-methyl-1-(4-methylthiophenyl)-2-morpholine-1-propanone, 2-phenylbenzyl-2-dimethylamine-1-(4-morpholinebenzylphenyl)butanone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and ethyl 2,4,6-trimethylbenzoylphenylphosphonate, so as to improve the polymerization efficiency of the alkali-soluble resin.

[0032] In one embodiment of the present application, the reducing agent is sodium borohydride and / or vitamin C.

[0033] The reducing agent has good reducing ability, high compatibility with the resin, and no harmful substances that affect the conductive properties will remain after reduction.

[0034] In another typical embodiment of the present application, a photosensitive cover film is provided. The photosensitive cover film includes a photosensitive layer and a polymer substrate layer stacked in sequence. The polymer substrate layer includes a polymer material. The photosensitive layer is obtained by curing the above-mentioned photosensitive composition.

[0035] The carboxylate generated by the carboxylated resin polymer and the metal ions in the metal ion source are coordinated chemically, and the alkali-soluble resin helps to synergistically promote the coordination of the carboxylate and the metal ions in the metal ion source, so as to better and more evenly fix the metal ions in the photosensitive layer, thereby ensuring that when the circuit board is prepared by exposure and development, the ultraviolet light is irradiated, on the one hand, the circuit is formed, and on the other hand, the metal ions in the metal ion source are concentrated and reduced and loaded on a certain resin carrier. The alkali-soluble resin is photocured into a polymer with a higher molecular weight under the conditions of photoinitiator and light, which is conducive to improving the strength of the obtained conductive metal thin layer and forming a conductive metal thin layer with excellent conductivity and strength. Subsequently, the required thickness of the circuit board can be achieved through copper electroplating, avoiding the waste of copper foil and the pollution of etching solution due to etching, which simplifies the process and reduces costs.

[0036] In addition, the above-mentioned photosensitive cover film can be obtained by preparing the photosensitive composition into a colloid, coating it on the polymer base material layer 2, and curing it.

[0037] In another typical embodiment of the present application, a method for preparing a circuit board is provided, such as Figure 1 , 2 As shown, the preparation method includes: step S1, coating a photosensitive colloid on a polymer substrate layer to obtain a photosensitive substrate layer; step S2, covering the photosensitive layer of the photosensitive substrate layer with a mask plate and then performing exposure and development treatment to obtain a circuit board, and the photosensitive colloid includes the above-mentioned photosensitive composition.

[0038] The carboxylate generated by the carboxylated resin polymer and the metal ions in the metal ion source are coordinated chemically, and the alkali-soluble resin helps to synergistically promote the coordination of the carboxylate and the metal ions in the metal ion source, so as to better and more evenly fix the metal ions in the photosensitive layer, thereby ensuring that when the circuit board is prepared by exposure and development, the ultraviolet light is irradiated, on the one hand, the circuit is formed, and on the other hand, the metal ions in the metal ion source are concentrated and reduced and loaded on a certain resin carrier. The alkali-soluble resin is photocured into a polymer with a higher molecular weight under the conditions of photoinitiator and light, which is conducive to improving the strength of the obtained conductive metal thin layer and forming a conductive metal thin layer with excellent conductivity and strength. Subsequently, the required thickness of the circuit board can be achieved by electroplating copper, avoiding the waste of copper foil and the pollution of etching solution due to etching, which simplifies the process and reduces the cost, thereby providing a simple preparation method for the circuit board.

[0039] The viscosity of the photosensitive colloid is preferably controlled to be in the range of 1500 to 2500 cps, so as to facilitate coating the photosensitive colloid on the polymer substrate layer 2 to obtain a photosensitive cover film.

[0040] The circuit is preferably washed with water, and the developing sodium carbonate can be used for cleaning to obtain a clean formed circuit board. The circuit after the water washing treatment is preferably dried. To improve the efficiency and effect of drying, the preferred drying method is baking.

[0041] In addition, in order to reduce the contamination of the photosensitive cover film by impurities in the environment before making the circuit board, the photosensitive cover film preferably also includes a release paper, which covers the photosensitive cover film, and the thickness of the release paper is preferably 110 μm. The thickness of the photosensitive layer is preferably 1 to 5 μm, preferably 1 to 3 μm.

[0042] In one embodiment of the present application, Figure 3 As shown, the above preparation method also includes: using the circuit board as a cathode, copper plating is performed on the circuit surface of the circuit board under the action of an external anode and a copper sulfate electroplating solution.

[0043] During the exposure and development process after covering the photosensitive layer of the photosensitive substrate layer with a mask, the metal ion source in the photosensitive layer 1 is reduced to a conductive metal element. Therefore, when the circuit board is used as the electroplating cathode, a copper-plated layer 4 is selectively formed on the surface of the circuit 3, and copper is not plated on the parts between the insulating circuits. This can achieve the required thickness of the circuit board as a whole, avoid wasting copper foil due to etching and contamination of the etching solution, simplify the process and reduce costs. For example, the present application can achieve copper plating on the circuit surface of the circuit board by a constant current method.

[0044] In one embodiment of the present application, the intensity of the above-mentioned exposure is 200-600 mJ, and the time is 30-60 seconds. Preferably, step S1 also includes a thermal curing process between the exposure and development treatments, and the thermal curing temperature is 150-230° C. and the time is 0.5-2 hours.

[0045] The intensity and time of the above exposure are helpful to improve the formation rate of the circuit, and the heat curing process between the exposure and development treatment is conducive to the curing of the alkali-soluble resin to obtain a photosensitive cover film with a certain strength, thereby providing excellent protection for the circuit.

[0046] The polymer substrate layer 2 has an insulating effect on the protected circuit and can improve the strength of the circuit board. Preferably, the polymer substrate layer 2 includes a polymer material, and the polymer material is preferably selected from any one or more of polyethylene terephthalate, polyethylene naphthalate, polyparaphenylene terephthalamide, and polyimide resin. The polymer material is preferably polyimide resin, and the thickness of the polymer substrate layer 2 is 12.5 to 50 μm, preferably 12.5 to 20 μm. On the basis of taking into account both the insulating effect and the strength, the thickness of the circuit board can be minimized as much as possible, thereby reserving a wider operating space for the design of the circuit, copper plating layer, etc. in the context of pursuing a thin circuit board.

[0047] In another typical embodiment of the present application, Figure 2 As shown, a circuit board is provided, and the circuit board is prepared by the above-mentioned preparation method.

[0048] The circuit board obtained by the above-mentioned preparation method of the present application not only has excellent conductivity and strength, but also can flexibly achieve the required thickness of the entire circuit board through copper electroplating according to actual needs, avoiding the waste of copper foil and pollution of etching solution due to etching, which simplifies the process and reduces costs.

[0049] The beneficial effects of the present application will be described below in conjunction with specific embodiments and comparative examples.

[0050] Example 1

[0051] Preparation of photosensitive colloid:

[0052] 60 parts of polyurethane BX-39SS, whose acid value is 90KOH / (mg / g), are added to the reactor, followed by 15 parts of carboxylic acid modified epoxy resin (5 parts of ZAR-1035, 10 parts of ZFR-1491H) for stirring and mixing, the carboxylic acid modified epoxy resin is ZAR-1035, whose acid value is 100KOH / (mg / g), and the mixing time is about 2 hours. After the mixing is completed, 4 parts of photoinitiator (3 parts of photoinitiator 184, 1 part of photoinitiator 907) are added and stirred for 30 minutes. Then, 20 parts of copper nitrate (in terms of copper ions) and 1 part of reducing agent sodium borohydride are added, and the mixing and stirring are controlled for 2 hours to obtain a photosensitive colloid. The viscosity of the prepared photosensitive colloid is controlled at 2000cps, and the solid content is about 45wt%.

[0053] Carboxylated resin polymer: polyester resin, BX-39SS, Toyobo, Japan; polyimide resin: PI-380G, Jinyi Chemical;

[0054] Epoxy acrylic resin: ZAR-1035, ZAR-2000, ZAR-1000, ZFR-1491H, CCR-1291H, CCR-1235, Nippon Kayaku;

[0055] Sodium borohydride: Huashuo Chemical;

[0056] Photoinitiator: Photoinitiator 184, Photoinitiator 907;

[0057] The photosensitive colloid was coated on a polyimide film (12.5 μm thick), and the solvent was removed at 85° C. / 30 minutes to form a photosensitive layer 1 on the polyimide film. A layer of 110 μm thick release paper was covered on the photosensitive layer 1 to obtain a photosensitive substrate layer.

[0058] After the release paper is removed, the photosensitive cover film, such as Figure 1 As shown, the photosensitive layer of the photosensitive substrate layer (including the photosensitive layer and the polyimide substrate layer) is covered with a mask and then exposed (exposure intensity is 500mJ, exposure time is 45 seconds), and developed to obtain a patterned circuit. At the same time, the copper ions are reduced to a copper conductive metal layer. Then, the patterned circuit board is degummed, the residual sodium bicarbonate salt is washed with water, and baked at 150°C / 30 minutes to initially obtain a circuit board with a thickness of 16μm, as shown in FIG. Figure 2 shown.

[0059] The external copper electrode was used as the anode and copper sulfate solution was used as the electroplating solution. The constant current method (3A / cm 2 ) directly at 2cm 2 Copper electroplating was performed on the circuit board to obtain a circuit board with a total thickness of 20 μm, and the time required for electroplating was recorded.

[0060] The situations where some conditions in Examples 1 to 9 and Comparative Examples 1 to 6 were changed (the copper nitrate was calculated as copper ion) are listed in Table 1. The specific operations in Examples 1 to 9 and Comparative Examples 1 to 6 refer to Example 1.

[0061] Table 1

[0062]

[0063]

[0064] Example 10

[0065] The difference between Example 10 and Example 1 is that, calculated on the basis of silver ions, the metal precursor salt is 20 parts of silver nitrate, and a circuit board with a total thickness of 20 μm is finally obtained.

[0066] Embodiment 11

[0067] The difference between Example 11 and Example 1 is that the reducing agent is 1 part of vitamin C, and the circuit board with a total thickness of 20 μm is finally obtained.

[0068] Example 12

[0069] The difference between Example 12 and Example 1 is that the photosensitive colloid is coated on the polyimide film (with a thickness of 20 μm), and finally a circuit board with a total thickness of 27.5 μm is obtained.

[0070] Example 13

[0071] The difference between Example 13 and Example 1 is that the photosensitive colloid is coated on a polyethylene naphthalate film (with a thickness of 12.5 μm), and finally a circuit board with a total thickness of 20 μm is obtained.

[0072] Embodiment 14

[0073] The difference between Example 14 and Example 1 is that the exposure intensity is 450 mJ, the exposure time is 60 seconds, and finally a circuit board with a total thickness of 20 μm is obtained.

[0074] Embodiment 15

[0075] The difference between Example 15 and Example 1 is that the photosensitive colloid is coated on a polyimide film (with a thickness of 12.5 μm), and the solvent is removed at 200° C. / 30 minutes to finally obtain a circuit board with a total thickness of 20 μm.

[0076] Example 16

[0077] The difference between Example 16 and Example 1 is that the carboxylic acid-modified epoxy resin is ZCR-1642H, and its acid value is 70KOH / (mg / g), and finally a circuit board with a total thickness of 20 μm is obtained.

[0078] Embodiment 17

[0079] The difference between Example 17 and Example 1 is that the carboxylic acid-modified epoxy resin is ZCR-1569H, and its acid value is 85KOH / (mg / g), and finally a circuit board with a total thickness of 20 μm is obtained.

[0080] Comparative Example 7

[0081] The difference between Comparative Example 7 and Example 1 is that the carboxylic acid-modified epoxy resin is CCR-1235, and its acid value is 60KOH / (mg / g), and finally a circuit board with a total thickness of 20 μm is obtained.

[0082] The circuit boards obtained in the above-mentioned Examples 1 to 17 and Comparative Examples 1 to 7 were subjected to adhesion test, bending test, heat resistance test, acid resistance test, alkali resistance test and alcohol resistance test, respectively.

[0083] Adhesion test (100-grid test): Paste the above circuit board with 100-grid tape, then tear off the tape and observe whether the metal layer of the circuit board falls off.

[0084] Bending test: bend the circuit board 180 degrees 10 times, and observe whether the metal layer of the circuit board falls off.

[0085] Heat resistance test: Soak the test circuit board in a tin furnace at a temperature of 288 degrees for 30 seconds. After taking out the test piece, observe whether the surface of the circuit board has blistering, discoloration, floating and peeling.

[0086] Acid resistance test: Soak the circuit board in 10% HCl and observe whether the metal layer of the circuit board falls off.

[0087] Alkali resistance test: The above circuit board is immersed in a NaOH solution with a mass concentration of 10%, and the metal layer of the circuit board is observed to see whether it falls off.

[0088] Alcohol resistance test: The above circuit board is immersed in an ethanol solution with a mass concentration of 95%, and the metal layer of the circuit board on the circuit board is observed to see whether it falls off.

[0089] The above test results are listed in Table 2.

[0090] Table 2

[0091]

[0092]

[0093] In Table 1, the constant current method (3A / cm 2 ) directly at 2cm 2 Copper electroplating is carried out on the material. When the plating reaches a certain overall thickness, the time required for electroplating is recorded, and the conductivity of the reduced metal layer can be evaluated. That is, for copper layers of the same thickness, the longer the electroplating time is, the worse the conductivity of the metal layer is.

[0094] Compared with Examples 1, 7, and 8, although the amount of copper nitrate was increased in Example 9, the amount of carboxylated resin polymer was correspondingly reduced, so that a portion of the copper ions of the copper nitrate were not fixed and reduced to the corresponding copper element. Therefore, the time required for electroplating a copper layer of the same thickness would be longer.

[0095] In Comparative Example 5, when the amount of alkali-soluble resin used is too much, the amount of carboxylated resin polymer coordinated with the metal ions in the metal ion source is reduced, thereby reducing and weakening the fixation effect of carboxylate on the metal ions in the metal ion source, thereby increasing the strength of the resulting conductive metal film.

[0096] In Comparative Example 6, when no alkali-soluble resin is added, the coordination effect of the alkali-soluble resin on the carboxylated resin polymer is lost, which not only weakens the fixation effect of the carboxylate on the metal ions in the metal ion source, but also reduces the conductivity and strength of the conductive metal film.

[0097] In Comparative Example 7, when the acid value of the alkali-soluble resin is too low, the coordination effect of the alkali-soluble resin on the carboxylated resin polymer is greatly reduced, which not only weakens the fixation effect of the carboxylate on the metal ions in the metal ion source, but also reduces the conductivity and strength of the conductive metal film.

[0098] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0099] The carboxylate generated by the carboxylated resin polymer and the metal ions in the metal ion source are coordinated chemically, and the alkali-soluble resin with the acid value in the above range helps to synergistically promote the coordination between the carboxylate and the metal ions in the metal ion source, so as to better and more evenly fix the metal ions in the photosensitive layer, thereby ensuring that when the circuit board is prepared by exposure and development, the ultraviolet light is irradiated, on the one hand, the circuit is formed, and on the other hand, the metal ions in the metal ion source are concentratedly reduced and loaded on a certain resin carrier, and the alkali-soluble resin is photocured into a polymer with a higher molecular weight under the conditions of photoinitiator and light, so as to improve the strength of the obtained conductive metal thin layer and form a conductive metal thin layer with excellent conductivity and strength. Subsequently, the required thickness of the circuit board can be achieved by electroplating copper, avoiding the waste of copper foil and the pollution of etching solution due to etching, which simplifies the process and reduces the cost.

[0100] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A photosensitive composition, characterized in that: In parts by weight, the photosensitive composition comprises: 40 to 60 parts of a carboxylated resin polymer; 12.5 to 15.5 parts of alkali-soluble resin; 1.5 to 4.0 parts of photoinitiator; 20 to 40 parts of the metal ion source, based on the metal ions in the metal ion source; 0.1 to 1.9 parts of reducing agent; Wherein, the reducing agent reduces the metal ions in the metal ion source to metal under the condition of light or heating, and the acid value of the alkali-soluble resin is 70 to 100 KOH / (mg / g); The carboxylated resin polymer is selected from any one or more of carboxylated polyurethane and carboxylated polyimide resins; The alkali-soluble resin is epoxy acrylic resin.

2. The photosensitive composition according to claim 1, characterized in that: The weight ratio of the carboxylated resin polymer to the metal ion source is 3:2 to 3:1, The acid value of the carboxylated resin polymer is 80 to 200 KOH / (mg / g); And / or the metal ion source is selected from any one or more of water-soluble silver salts, water-soluble copper salts, water-soluble palladium salts, water-soluble gold salts and water-soluble nickel salts.

3. The photosensitive composition according to claim 1, characterized in that The carboxylated resin polymer is polyurethane and / or carboxylated polyamideimide.

4. The photosensitive composition according to claim 1, characterized in that The epoxy acrylic resin is selected from any one or more of carboxylic acid modified bisphenol A epoxy resin, carboxylic acid modified bisphenol F epoxy resin, carboxylic acid modified novolac epoxy resin, and carboxylic acid modified o-cresol epoxy resin.

5. The photosensitive composition according to claim 1, characterized in that The weight ratio of the carboxylated resin polymer to the alkali-soluble resin is 3 to 4.5:

1.

6. The photosensitive composition according to any one of claims 1 to 5, characterized in that The photoinitiator is selected from any one or more of 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-[4-(2-hydroxy)-phenyl]-3-hydroxy-2-methyl-1-propanone-1-one, 2-methyl-1-(4-methylthiophenyl)-2-morpholine-1-propanone, 2-phenylbenzyl-2-dimethylamine-1-(4-morpholinebenzylphenyl)butanone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and ethyl 2,4,6-trimethylbenzoylphenylphosphonate.

7. The photosensitive composition according to any one of claims 1 to 5, characterized in that The reducing agent is sodium borohydride and / or vitamin C.

8. A photosensitive cover film, characterized in that: The photosensitive cover film comprises a photosensitive layer and a polymer substrate layer stacked in sequence, the polymer substrate layer comprises a polymer material, and the photosensitive layer is obtained by curing the photosensitive composition according to any one of claims 1 to 7.

9. A method for preparing a circuit board, characterized in that: The preparation method comprises: Step S1, coating a photosensitive colloid on a polymer substrate layer to obtain a photosensitive substrate layer; Step S2, covering the photosensitive layer of the photosensitive substrate layer with a mask and then performing exposure and development treatment to obtain a circuit board, The photosensitive colloid comprises the photosensitive composition according to any one of claims 1 to 7.

10. The preparation method according to claim 9, characterized in that: The preparation method further comprises: The circuit board is used as a cathode, and copper is plated on the circuit surface of the circuit board under the action of an external anode and a copper sulfate electroplating solution.

11. The preparation method according to claim 9, characterized in that: The exposure intensity is 200-600 mJ, and the exposure time is 30-60 seconds.

12. The preparation method according to claim 9, characterized in that: The step S1 further includes a thermal curing process between the exposure and the development process, wherein the thermal curing temperature is 150-230° C. and the time is 0.5-2 hours.

13. The preparation method according to claim 9, characterized in that: The polymer substrate layer includes a polymer material.

14. The preparation method according to claim 13, characterized in that: The polymer material is selected from any one or more of polyethylene terephthalate, polyethylene naphthalate, polyparaphenylene terephthalamide, and polyimide resin.

15. The preparation method according to claim 13, characterized in that: The polymer material is polyimide resin, and the thickness of the polymer substrate layer is 12.5-50 μm.

16. The preparation method according to claim 15, characterized in that: The thickness of the polymer substrate layer is 12.5 to 20 μm.

17. A circuit board, characterized in that: The circuit board is prepared by the preparation method described in any one of claims 9 to 16.

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