UV light-curing solder resist ink, preparation method and high temperature resistant printed circuit board

Abstract

The present invention relates to a UV light-curing solder resist ink, a preparation method and a high temperature resistant printed circuit board, comprising the following components by weight: 30-50 parts of a photocurable resin; 20-30 parts of a cross-linking agent; 1-5 parts of a photoinitiator; 5-10 parts of a diluent; and 10-30 parts of a composite filler; the composite filler comprises a matrix particle and a coating layer from the inside to the outside, and the coating layer comprises silicon nitride with a mesh structure. The composite filler and the photocurable resin are firmly combined in a complex network form, thereby improving the overall hardness and heat resistance of the solder resist ink.

Description

Technical Field

[0001] The invention relates to the technical field of UV light-curing solder resist ink, and in particular to a UV light-curing solder resist ink, a preparation method and a high-temperature resistant printed circuit board. Background Art

[0002] During the production process of printed circuit boards (PCBs), it is necessary to protect the parts that do not need to be soldered in order to improve the welding efficiency and avoid damage to components. Solder resist ink is a material used to protect the surface of PCBs. It is applied to the surface of PCBs by printing, spraying, etc., and forms a solder resist film after curing. The current solder resist ink has poor heat resistance and is prone to softening and cracking in high temperature environments, making it difficult to play the role of solder resistance and circuit protection. Summary of the invention

[0003] Based on this, it is necessary to provide a UV light-curing solder resist ink, a preparation method and a high-temperature resistant printed circuit board.

[0004] A UV light-curing solder resist ink, characterized in that it comprises the following components:

[0005]

[0006] The composite filler includes matrix particles and a coating layer from the inside to the outside, the matrix particles are used as a support for making the coating layer, and the coating layer includes silicon nitride (Si3N4) with a mesh structure.

[0007] Silicon nitride itself can form hydrogen bonds with photocurable resins, and after silicon nitride is exposed to ultraviolet rays, silicon oxide formed on part of the surface can also form hydrogen bonds with photocurable resins, which can increase the bonding strength between the composite filler and the photocurable resin. In addition, silicon nitride has a mesh structure, which increases the contact area between silicon nitride and the photocurable resin, promotes the formation of more hydrogen bonds between the two, and increases the bonding strength. The bonding sites of silicon nitride with a mesh structure are distributed in multiple directions, which is conducive to the formation of a complex network structure that is intertwined when the photocurable resin and silicon nitride are combined. In this way, the composite filler and the photocurable resin can be firmly combined in the form of a complex network, which improves the overall hardness and heat resistance of the solder mask ink.

[0008] In one embodiment, the matrix particles include at least one of silicon dioxide, aluminum hydroxide, aluminum oxide, titanium dioxide, barium sulfate, calcium carbonate, kaolin and talc. These composite fillers can increase the hardness and heat resistance of the solder resist ink and provide support for the production of silicon nitride with a mesh structure. The added silicon nitride can further improve the hardness and heat resistance of the solder resist ink.

[0009] In one embodiment, the coating layer has a thickness of 500-1000 nm, preferably 600-800 nm. Too small a thickness is not conducive to providing sufficient hydrogen bonding sites, while too large a thickness will excessively increase the size of the composite filler, which may easily lead to uneven stress distribution after UV light-curing solder resist ink is formed.

[0010] In one embodiment, the photocurable resin includes at least one of epoxy resin and acrylic resin. Epoxy resin and acrylic resin are commonly used resins in solder resist inks and can interact with the composite filler with silicon nitride to improve hardness and heat resistance.

[0011] In one embodiment, the diluent includes at least one of a ketone diluent, an ether diluent and a lipid diluent, which can reduce the viscosity of the UV light-curing solder resist ink, thereby making the UV light-curing solder resist ink easy to be coated on the surface of the circuit board.

[0012] In one embodiment, the photoinitiator includes at least one of a free radical photoinitiator and a cationic photoinitiator. Under the irradiation of ultraviolet light, both types of photoinitiators can initiate photocuring of the photocurable resin, thereby allowing the UV light-curing solder mask ink to be stably formed on the surface of the circuit board.

[0013] In one embodiment, the photoinitiator includes a free radical photoinitiator, including at least one of a benzil photoinitiator, an α-hydroxyketone photoinitiator and an acylphosphine oxide photoinitiator. These free radical photoinitiators have a fast initiation rate and can enable UV light-curing solder mask ink to be quickly formed.

[0014] In one embodiment, the photoinitiator includes a cationic photoinitiator, including at least one of an aromatic diazonium salt photoinitiator, a diaryl iodonium salt photoinitiator and a triaryl sulfonium salt photoinitiator. These cationic photoinitiators have good molding quality and can make the UV light-curing solder mask ink have higher hardness.

[0015] For example, the photoinitiator is selected from one or more of 2-isopropylthioxanthone, 2-ethylanthraquinone, benzoin diethyl ether 651, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide and 2-methyl 1-[4-(methylthio)phenyl]-2-morpholinyl-1-propanone 907.

[0016] In one embodiment, the crosslinking agent includes at least one of an amine crosslinking agent, an imidazole crosslinking agent, and an organic anhydride crosslinking agent. These crosslinking agents can enhance the curing effect of the photocurable resin during the baking stage, and play a role in shaping and increasing the degree of crosslinking.

[0017] In one embodiment, the UV light curing solder resist ink further includes 1 to 5 parts of a colorant for providing color to the solder resist ink. For example, the colorant includes one of phthalocyanine blue, yellow pigment, green pigment, red pigment, titanium dioxide and carbon black.

[0018] In one embodiment, a method for preparing a UV light-curable solder resist ink as in any of the above embodiments is provided, comprising the following steps:

[0019] Providing a mixed gas of H2 and SiH4;

[0020] The substrate particles are placed in a CVD rotary furnace, and after evacuation, ammonia and the mixed gas are introduced to perform deposition to obtain an intermediate product A; specifically, the deposition temperature is between 250 and 350° C., and the deposition time is 3 to 6 hours.

[0021] A photoresist is coated on the surface of the intermediate product A and dried, and the photoresist is exposed with a mask to obtain an intermediate product B; for example, the photoresist includes at least one of AZ4620, AZ4526, and PR11000A1. For example, the mesh area of ​​the mask is 1 to 2um2, and the distribution of silicon nitride can be controlled by setting different mesh areas. By controlling the mesh area, silicon nitride with different specific surface areas can be obtained. Too large a specific surface area will make it difficult for the photocurable resin to extend into the grid of the silicon nitride, while too small a specific surface area will reduce the bonding performance.

[0022] The intermediate product B is subjected to development treatment, etching treatment and degumming treatment to obtain a composite filler; specifically, in the development step, the developer includes at least one of TBAH, TMAH, and NTD. Specifically, the etching gas of the etching treatment is a mixed gas of CF4, C4F8 and SF6, and the etching time is 1 to 3 hours. The degumming solution of the degumming treatment includes alcohol. It is worth mentioning that the above steps can also be called a method for preparing a composite filler.

[0023] The UV light-curing solder resist ink is obtained by mixing 30 to 50 parts of a photocurable resin, 1 to 3 parts of a cross-linking agent, 1 to 5 parts of a photoinitiator, 5 to 10 parts of a diluent and 10 to 30 parts of the composite filler.

[0024] In the UV light-curing solder resist ink prepared by the above method, the composite filler and the light-curing resin are firmly combined together in the form of a complex network, thereby improving the overall hardness and heat resistance of the solder resist ink.

[0025] In one embodiment, a high temperature resistant printed circuit board is provided, comprising solder resist ink, wherein the raw material of the solder resist ink comprises the UV light curing solder resist ink as described in any of the above embodiments. The high temperature resistant printed circuit board has good hardness and heat resistance by using the solder resist ink of any of the above embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of a composite filler according to an embodiment.

[0027] Figure 2 The present invention is a flow chart of a method for preparing a UV light-curing solder resist ink according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] For ease of understanding of the application, the application will be described more fully below. The application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the application more thorough and comprehensive.

[0029] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In the description of the present application, the meaning of "several" is at least one, such as one, two, etc., unless otherwise clearly and specifically defined.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which the present application belongs. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0031] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0032] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0033] The percentage contents involved in this application, unless otherwise specified, refer to mass percentage for solid-liquid mixing and solid-solid mixing, and refer to volume percentage for liquid-liquid mixing.

[0034] The percentage concentrations mentioned in this application, unless otherwise specified, refer to the final concentration, which refers to the percentage of the added component in the system after the addition of the component.

[0035] The temperature parameters in this application, unless otherwise specified, allow for both constant temperature treatment and treatment within a certain temperature range. The constant temperature treatment allows the temperature to fluctuate within the accuracy range of instrument control.

[0036] The "particles" mentioned in this application, or materials with a defined particle size distribution, are not necessarily spherical in shape, but may be irregular, primary particles or secondary particles. The particle size of irregular particles is the average of their maximum diameter and minimum diameter.

[0037] The UV light-curing solder resist ink provided in one embodiment includes the following components by weight: 30-50 parts of a photocurable resin, 1-3 parts of a cross-linking agent, 1-5 parts of a photoinitiator, 5-10 parts of a diluent, and 10-30 parts of a composite filler; Figure 1 As shown, the composite filler 900 includes a matrix particle 100 and a coating layer 200 from the inside to the outside, and the coating layer 200 includes silicon nitride with a mesh structure. The preparation method of the UV light curing solder resist ink of this embodiment includes the following steps:

[0038] S1, provides a mixed gas of H2 and SiH4.

[0039] S2, placing the substrate particles in a CVD rotary furnace, evacuating the furnace, and introducing ammonia gas and the mixed gas to perform deposition to obtain an intermediate product A.

[0040] S3, coating a photoresist on the surface of the intermediate product A and drying it, and exposing the photoresist with a mask to obtain an intermediate product B.

[0041] S4, performing development treatment, etching treatment and degumming treatment on the intermediate product B to obtain a composite filler.

[0042] S5, mixing 30-50 parts of a photocurable resin, 20-30 parts of a crosslinking agent, 1-5 parts of a photoinitiator, 5-10 parts of a diluent and 10-30 parts of the composite filler to obtain the UV light-curing solder resist ink.

[0043] In the above-mentioned UV light-curing solder resist ink, silicon nitride itself can form hydrogen bonds with photocurable resins, and after silicon nitride is irradiated with ultraviolet rays, silicon oxide formed on part of the surface can also form hydrogen bonds with photocurable resins, and the bonding strength between the composite filler and the photocurable resin can be increased by forming hydrogen bonds. In addition, silicon nitride has a mesh structure, which increases the contact area between silicon nitride and the photocurable resin, promotes the formation of more hydrogen bonds between the two, and increases the bonding strength. The bonding sites of silicon nitride with a mesh structure are distributed in multiple directions, which is conducive to the formation of a complex network structure that is intertwined when the photocurable resin and silicon nitride are combined. In this way, the composite filler and the photocurable resin can be firmly combined in the form of a complex network, thereby improving the overall hardness and heat resistance of the solder resist ink.

[0044] The following are some more specific embodiments:

[0045] Example 1: The preparation of UV light curing solder resist ink in this example includes the following steps:

[0046] A mixed gas of H2 and SiH4 is provided, wherein the volume ratio of H2 to SiH4 is 4:1.

[0047] The base particles are placed in a CVD rotary furnace, and after vacuuming, ammonia and the mixed gas are introduced to perform deposition to obtain an intermediate product A. The base particles are silicon oxide particles, the volume ratio of ammonia and the mixed gas is 1:1, the deposition temperature is 230°C ± 2°C, the deposition time is 5h, and the thickness of the coating layer measured by a scanning electron microscope is 500nm.

[0048] A photoresist is coated on the surface of the intermediate product A and dried, and the photoresist is exposed with a mask to obtain an intermediate product B. Specifically, the photoresist is AZ4620, and the mesh area of ​​the mask is 1 um. 2 .

[0049] The intermediate product B is subjected to development treatment, etching treatment and degumming treatment to set a mesh-structured silicon nitride on the surface of the matrix particles. The developing solution TBAH is used for the development treatment. In the etching treatment, the developed intermediate product B is placed in a plasma etcher, and after vacuuming, CF4, C4F8 and SF6 gases with a volume ratio of 1:1:1 are introduced for etching for 1 hour, and after etching treatment, it is placed in alcohol for degumming treatment.

[0050] The photocurable resin, the crosslinking agent, the photoinitiator, the diluent and the composite filler are mixed in a weight ratio of 30:1:1:5:10 to obtain the UV light-curable solder resist ink, wherein the photocurable resin is epoxy acrylate resin, the crosslinking agent is glycidylamine, the photoinitiator is 2-isopropylthioxanthone, and the diluent is hydroxyethyl methacrylate.

[0051] Example 2: The difference from Example 1 is that the weight ratio of the photocurable resin, the crosslinking agent, the photoinitiator, the diluent and the composite filler is 50:3:5:10:30.

[0052] Embodiment 3: The difference from Embodiment 1 is that the weight ratio of the photocurable resin, the crosslinking agent, the photoinitiator, the diluent and the composite filler is 40:2:3:10:20.

[0053] Embodiment 4: The difference from Embodiment 3 is that the thickness of the coating layer is 1000 nm.

[0054] Embodiment 5: The difference from Embodiment 3 is that the thickness of the coating layer is 700 nm.

[0055] Comparative Example 1: With silicon nitride as filler, a photocurable resin, a crosslinking agent, a photoinitiator, a diluent and a filler are mixed in a weight ratio of 30:1:1:5:10 to obtain a solder resist ink, wherein the photocurable resin is epoxy acrylate resin, the crosslinking agent is glycidylamine, the photoinitiator is 2-isopropylthioxanthone, and the diluent is hydroxyethyl methacrylate.

[0056] Comparative Example 2: The difference from Comparative Example 1 is that silicon oxide is used as the filler to obtain solder resist ink.

[0057] Comparative Example 3: The preparation of the solder resist ink in this embodiment includes the following steps:

[0058] A mixed gas of H2 and SiH4 is provided, wherein the volume ratio of H2 to SiH4 is 4:1.

[0059] The base particles are placed in a CVD rotary furnace, and after vacuuming, ammonia and the mixed gas are introduced to perform deposition to obtain a silicon oxide filler encapsulating homogeneous silicon nitride. The base particles are silicon oxide, the volume ratio of ammonia and the mixed gas is 1:1, the deposition temperature is 230°C ± 2°C, the deposition time is 5 hours, and the coating thickness is 500nm measured by scanning electron microscopy.

[0060] The photocurable resin, the crosslinking agent, the photoinitiator, the diluent and the silicon oxide filler encapsulating the homogeneous silicon nitride are mixed in a weight ratio of 30:1:1:5:10 to obtain a solder resist ink.

[0061] The solder resist ink obtained above was screen printed on the surface of the copper clad laminate to form a wet film, pre-baked at 80°C for 30 min, and coated with 300 mJ / cm 2 The film was exposed, developed with a sodium carbonate solution having a mass concentration of 1% for 90 seconds at a developing temperature of 30° C., and cured by baking at 150° C. for 60 minutes to obtain a test coating film.

[0062] Hardness test: The pencil hardness test of the test coating film shall be carried out according to "Determination of paint film hardness by pencil method for paints and varnishes" GB / T 6739-2022.

[0063] Temperature resistance test: The sample coated with solder resist ink is subjected to a solder resistance test three times for 10 seconds according to GB / T 4677-2002 to measure the temperature data that it can withstand.

[0064] Experimental Group Pencil hardness (H) Temperature resistance (℃) Example 1 5 271 Example 2 4 254 Example 3 6 282 Example 4 5 260 Example 5 6 288 Comparative Example 1 3 238 Comparative Example 2 2 223 Comparative Example 3 3 243

[0065] From the above test data, it can be seen that compared with the comparative example, the composite filler made of mesh silicon nitride in each embodiment interacts with the photocurable resin, significantly increasing the hardness and temperature resistance of the solder mask ink. And by comparing Example 1, Comparative Example 1 and Comparative Example 3, it can be seen that by setting the silicon nitride with a mesh structure, the hardness and temperature resistance of Example 1 are better, while the silicon nitrides of Comparative Examples 1 and Comparative Examples 3 are both homogeneous layers, and there are fewer bonding points with the photocurable resin, so the final hardness and heat resistance are not as good as those of Example 1. From the comparison of the various embodiments, it can be seen that the components of Example 3 have a better ratio, so as to obtain better hardness and temperature resistance, and the coating layer of Example 5 further improves the thickness of the coating layer compared with Example 3, so that the composite filler and other materials of the solder mask ink are evenly distributed, the composite filler and the photocurable resin have the best bonding effect, and better temperature resistance is obtained.

[0066] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0067] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A UV light curing solder resist ink for high temperature resistant printed circuit boards, characterized in that: It includes the following components by weight: The composite filler comprises a matrix particle and a coating layer from the inside to the outside, the matrix particle comprises at least one of silicon dioxide, aluminum hydroxide, aluminum oxide, titanium dioxide, barium sulfate, calcium carbonate, kaolin and talc, the coating layer comprises silicon nitride having a network structure, the photocurable resin is epoxy acrylate resin, and the diluent is hydroxyethyl methacrylate, wherein the preparation method of the composite filler comprises the following steps: Providing a mixed gas of H2 and SiH4; The substrate particles are placed in a CVD rotary furnace, and after evacuation, ammonia gas and the mixed gas are introduced to perform deposition to obtain an intermediate product A; Coating a photoresist on the surface of the intermediate product A and drying it, and exposing the photoresist with a mask to obtain an intermediate product B; The intermediate product B is subjected to development treatment, etching treatment and degumming treatment to obtain a composite filler.

2. The UV light curing solder resist ink according to claim 1, characterized in that: The coating layer has a thickness of 500 to 1000 nm.

3. The UV light curing solder resist ink according to claim 1, characterized in that: The photoinitiator includes at least one of a free radical photoinitiator and a cationic photoinitiator.

4. The UV light curing solder resist ink according to claim 1, characterized in that: The cross-linking agent includes at least one of an amine cross-linking agent and an organic acid anhydride cross-linking agent.

5. The UV light curing solder resist ink according to claim 1, characterized in that: It also includes 1 to 5 parts of colorant.

6. A method for preparing the UV light-curing solder resist ink as claimed in claim 1, characterized in that: The steps include: Providing a mixed gas of H2 and SiH4; The substrate particles are placed in a CVD rotary furnace, and after evacuation, ammonia gas and the mixed gas are introduced to perform deposition to obtain an intermediate product A; Coating a photoresist on the surface of the intermediate product A and drying it, and exposing the photoresist with a mask to obtain an intermediate product B; Performing development treatment, etching treatment and degumming treatment on the intermediate product B to obtain a composite filler; The UV light-curing solder resist ink is obtained by mixing 30 to 50 parts of a photocurable resin, 1 to 3 parts of a cross-linking agent, 1 to 5 parts of a photoinitiator, 5 to 10 parts of a diluent and 10 to 30 parts of the composite filler.

7. A high temperature resistant printed circuit board, characterized in that: The invention comprises solder resist ink, wherein the raw material of the solder resist ink comprises the UV light curing solder resist ink as described in any one of claims 1 to 5.

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