Highly reliable dry film solder resist and its application on integrated circuit board

Abstract

The application provides a high-reliability dry solder resist film, and preparation raw materials of the dry solder resist film comprise, by weight parts, 35-45 parts of a carboxyl-containing polyurethane resin, 40-60 parts of an epoxy resin, 5-10 parts of a curing agent, 90-120 parts of a filler, 1-4 parts of a flame retardant, 0.1-3 parts of a nitrogen-containing heterocyclic compound and 15-25 parts of a solvent; by controlling the weight ratio of the polyurethane resin, the nitrogen-containing heterocyclic compound and the epoxy resin, and by optimizing processes such as compounding inorganic fillers with different particle sizes, the dry solder resist film has good flexibility, flame retardant performance, high-temperature resistance, low thermal expansion coefficient, salt mist resistance and chemical resistance, can be used for manufacturing PCB circuit boards, and has excellent reliability.

Description

Technical Field

[0001] This invention relates to the field of C08L63 / 00, and more particularly to a high-reliability solder resist dry film and its application on integrated circuit boards. Background Technology

[0002] With the current trend towards refinement in integrated circuits, the solder resist dry films used on integrated circuit substrates need to possess high resolution, high imaging quality, and high reliability. However, commonly used phosphorus-containing compounds, especially phosphate esters, in solder resist dry films exhibit weak hydrolysis resistance and poor migration resistance, thus limiting their large-scale use. Furthermore, to enhance via-masking capability and electroplating stability, polymeric monomers that improve adhesion or increase the molecular weight of alkali-soluble resins are added to the solder resist dry film components, which also significantly impacts the dry film's performance. To ensure high reliability, it is necessary to improve the solder resist dry film's resistance to high temperature and humidity conditions and to alleviate the stress it experiences during PCT, HAST, and TC tests.

[0003] Patent CN2010106028638 discloses an epoxy resin composition and a flexible cover film for printed circuits prepared therefrom. By using brominated epoxy resin, rubber-modified epoxy resin, nitrile rubber, different types of curing agents, curing accelerators, and inorganic fillers, the prepared cover film has good flexibility and flame retardancy, but its chemical resistance and heat resistance are still insufficient. Patent CN2008100823427 discloses an adhesive composition for halogen-free cover films and a cover film using the adhesive composition. By using nitrile rubber, non-halogen multifunctional epoxy resin, hardener, curing agent, phosphorus flame retardant, and other components, its cover film has excellent heat resistance and anti-spill properties, but the aging and poor ion migration resistance caused by rubber cannot be ignored. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention first provides a highly reliable solder resist dry film. The raw materials for preparing the solder resist dry film include: by weight, 35-45 parts of carboxyl-containing polyurethane resin, 40-60 parts of epoxy resin, 5-10 parts of curing agent, 90-120 parts of filler, 1-4 parts of flame retardant, and 15-25 parts of solvent.

[0005] Furthermore, the carboxyl-containing polyurethane resin is obtained by polymerizing alcohol polymers, diisocyanates, and dimethylolpropionic acid.

[0006] Furthermore, the alcohol polymer may be selected from one or a combination of several of polyester polyols, acrylic-modified polyester polyols, and polyether polyols.

[0007] Preferably, the alcohol polymer is an acrylic acid-modified polyester polyol.

[0008] Furthermore, the diisocyanate is selected from one or more of aliphatic diisocyanates, aromatic diisocyanates, and alicyclic diisocyanates.

[0009] Furthermore, the diisocyanate is an aliphatic diisocyanate, which may be one or a combination of two of HDI or IPDI.

[0010] Further, the weight ratio of the alcohol polymer, diisocyanate, and dimethylolpropionic acid is (30-40):(15-25):(6-9). By controlling the amount of diisocyanate and dimethylolpropionic acid added, the content of hard segments such as amide bonds in the polyurethane resin can be further controlled. When the amount of diisocyanate added is increased, the heat resistance of the carboxyl-containing polyurethane resin is improved, but the resulting solder resist film is rigid, brittle, and prone to cracking under impact. When the amount of alcohol polymer is increased, the flexibility of the resin chain is relatively improved, but when the amount added is too much, the hygroscopicity of the resin also increases, which is not conducive to the storage of the film and its stability during development.

[0011] Furthermore, the preparation method of the carboxyl-containing polyurethane resin is as follows: an alcohol polymer, dimethylolpropionic acid and p-benzoquinone are mixed, and then diisocyanate is added under stirring and heating. Heating is stopped after heating to 60°C. Heating is immediately turned on when the temperature of the reactor decreases and maintained at 80°C for 1-3 hours.

[0012] Furthermore, p-benzoquinone is added as a polymerization inhibitor at an amount of 0.2wt%-0.3wt% of the total amount of alcohol polymer, diisocyanate and dimethylolpropionic acid.

[0013] Furthermore, the carboxyl-containing polyurethane resin has a hydroxyl value of 50-160 mg KOH / g and a weight-average molecular weight of 8000-50000. The carboxyl-containing polyurethane resin contains a large number of hydroxyl and amino groups in its molecular chain, which can form cross-linking active sites, increasing its hydroxyl value and improving the developing effect of the dry film. However, when the content is too high, the alkali solution may corrode the photocured resin. Additionally, it may lead to excessively high cross-linking density of the carboxyl-containing polyurethane resin itself and with the epoxy resin, resulting in overly rigid molecular chains. This can easily cause the film to crack or peel off during subsequent circuit board soldering. When the weight-average molecular weight is too low, the film-forming properties of the dry film are poor, and the fixation of inorganic fillers is reduced. However, when the weight-average molecular weight is too high, the system viscosity is high, making coating inconvenient and reducing the dry film strength.

[0014] Furthermore, the epoxy resin is selected from one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and biphenyl phenol type epoxy resin.

[0015] Furthermore, the epoxy resin is a biphenyl phenol type epoxy resin.

[0016] Furthermore, the epoxy resin is a bismaleimide-modified biphenyl phenol type epoxy resin. In this experimental system, the epoxy resin has low heat resistance, and the reliability of the prepared dry film cannot be guaranteed. Therefore, bismaleimide is used in this application to modify the epoxy resin and enhance the high-temperature stability of the resin molecular chain.

[0017] Furthermore, in the bismaleimide-modified biphenyl phenol type epoxy resin, the weight ratio of bismaleimide to biphenyl phenol type epoxy resin is (0.8-1.2):(1.0-1.5). This application found that increasing the amount of bismaleimide increases the high-temperature resistance of the epoxy resin to a certain extent. However, excessive addition results in too much amine content in the epoxy resin, too dense volume crosslinking points, a significant increase in epoxy resin viscosity, poor processing fluidity, uneven dry film, and excessively strong interaction with carboxyl-containing polyurethane resin, leading to brittle solder resist dry film and poor dispersion of impact stress.

[0018] In a preferred embodiment, the weight ratio of the bismaleimide to the biphenyl phenol type epoxy resin is 1:1.2.

[0019] Furthermore, the curing agent is selected from one or more of phenolic resins, polyammonium salts, amides, and imidazoles.

[0020] In a preferred embodiment, the curing agent is N,N,N',N'-tetra(2-hydroxyethyl)hexamethylenediamide.

[0021] Furthermore, the filler is selected from at least one of the following: silicon dioxide, aluminum oxide, magnesium oxide, titanium oxide, aluminum hydroxide, magnesium hydroxide, aluminum nitride, boron nitride, barium sulfate, barium titanate, talc, calcium silicate, mica, and graphene.

[0022] Furthermore, the filler particle size is in the nanometer range.

[0023] In this study, it was found that although the flame retardant properties and heat resistance of the resin in the solder resist dry film have been effectively improved by the use and optimization of epoxy resin and carboxyl-containing polyurethane resin, and the use of phosphorus-based flame retardants has been reduced to a certain extent, the ion migration resistance of the prepared solder resist dry film is still unstable, and some dry films still show dendritic patterns in the ion migration resistance test.

[0024] Furthermore, the filler is a combination of silicon dioxide, aluminum hydroxide, and magnesium hydroxide.

[0025] Furthermore, the weight ratio of silica, aluminum hydroxide, and magnesium hydroxide in the filler is (3-5):(3-4):(1-2). Silica has a low coefficient of thermal expansion and good insulation and heat resistance. Its addition can effectively improve the heat resistance and flame retardant properties of the dry film, but its compatibility with the resin system is low. Aluminum hydroxide and magnesium hydroxide, along with their layered structure, can effectively absorb and fix the hydrolyzed ions of phosphorus-based flame retardants. Aluminum hydroxide and magnesium hydroxide also have good flame retardant and thermal conductivity properties. However, excessive addition can easily cause thermal stress cracking of the solder resist dry film. Therefore, the weight ratio of the three is limited to (3-5):(3-4):(1-2) to improve the heat resistance, flame retardancy, and reliability of the solder resist dry film, reduce ion migration within the film, and inhibit high-temperature cracking. However, the use of solid fillers may cause a decrease in the dry film resolution and the adhesion between the dry film and the circuit board substrate.

[0026] Preferably, the average diameter of the silicon dioxide particles is 350-600 nm.

[0027] Preferably, the aluminum hydroxide particles have an average diameter of 20-150 nm.

[0028] Preferably, the average particle diameter of the magnesium hydroxide is 50-120 nm.

[0029] Furthermore, the raw materials for preparation also include 0.1-3 parts by weight of a nitrogen-containing heterocyclic compound.

[0030] The applicant unexpectedly discovered that when the weight ratio of the carboxyl-containing polyurethane resin, the nitrogen-containing heterocyclic compound, and the epoxy resin is (3-6):(0.03-0.1):(1-6), the resulting solder resist dry film exhibits high adhesion density to the substrate, and no defects such as dry film peeling, cracking, curling, or lifting occur during development. The applicant speculates that the reason is that the carboxyl-containing polyurethane resin undergoes self-polymerization during dry film development, forming amide bonds and ester groups. Since amide bonds are hard segment chains, excessive amounts of carboxyl-containing polyurethane resin result in excessive hard segment formation, reducing the flexibility of the dry film and causing ester groups to... The hydrolyzability of the resin reduces the reliability of the dry film. In addition, the increased cross-linking degree between the resin and epoxy resin weakens the extensibility of the molecular chains at high temperatures. The nitrogen heterocyclic rings in the nitrogen-containing heterocyclic compounds can effectively improve the adhesion between the solder resist dry film and the circuit board substrate, but their molecular structure creates a certain steric hindrance to the rotation of other molecular chains in the system. When the amount of the resin is too high, the high-temperature crack resistance of the system decreases to a certain extent. Epoxy resin mainly plays a bonding role in the system, increases the cross-linking of the system and stabilizes the inorganic filler. When its content increases, it will also reduce the flexibility of the molecular chains.

[0031] Furthermore, the weight ratio of the carboxyl-containing polyurethane resin, the nitrogen-containing heterocyclic compound, and the epoxy resin is (3-5):(0.03-0.08):(3-6).

[0032] Preferably, the weight ratio of the carboxyl-containing polyurethane resin, the nitrogen-containing heterocyclic compound, and the epoxy resin is 4:0.06:5.

[0033] Furthermore, the nitrogen-containing heterocyclic compound is an imidazole or a derivative thereof.

[0034] Further, the nitrogen-containing heterocyclic compound includes at least one of 2-propylimidazolium, 2-phenyl-4-methylimidazolium, and 2-methyl-1-(3-aminopropyl)imidazolium.

[0035] Preferably, the nitrogen-containing heterocyclic compound is 2-phenyl-4-methylimidazole.

[0036] Furthermore, the flame retardant is a phosphorus-based flame retardant.

[0037] Furthermore, the flame retardant is selected from at least one of phosphates, polyphosphates, phosphate esters, phosphites, and phosphoethanols.

[0038] Furthermore, the flame retardant is selected from at least one of tricresyl phosphate, triphenyl phosphite, and dimethyl N,N-bis(2-hydroxyethyl)aminomethylphosphonate.

[0039] Furthermore, the solvent is selected from ethyl acetate, butanone, acetone, and ethylene glycol monoethyl ether acetate.

[0040] Secondly, the present invention also provides an application of a highly reliable solder resist dry film on an integrated circuit board.

[0041] Furthermore, the application steps of the solder resist dry film are as follows: S1. Mix the raw materials for preparing the solder resist dry film and coat them onto a polyester carrier film. Dry the film at a temperature of 60-85℃ and then apply the release protective film to the adhesive layer to obtain the solder resist dry film. S2. After removing the release liner and covering the surface of the integrated circuit board substrate, vacuum press-fit the substrate at a temperature of 50-70℃ and a pressing pressure of 0.2-0.7 kg / cm². 2 .

[0042] S3. The integrated circuit board undergoes exposure, development, and curing processes.

[0043] Furthermore, in step S1, the thickness of the dry solder resist film after drying is 15-50 μm.

[0044] Furthermore, in step S2, the pressing time is 15-30 seconds.

[0045] Furthermore, the integrated circuit board is a PCB circuit board.

[0046] Beneficial effects 1. This application controls the hardness, hydroxyl value and weight-average molecular weight of the resin by designing the types and contents of monomers containing carboxyl groups in the polyurethane resin, so that the solder resist dry film has excellent flexibility and flame retardancy, and greatly reduces the use of phosphorus-based flame retardants.

[0047] 2. This application specifies the weight ratio of carboxyl-containing polyurethane resin, nitrogen-containing heterocyclic compound, and epoxy resin, and controls the degree of crosslinking of the dry film system, so that the prepared solder resist dry film has good molecular chain extensibility and hydrolysis resistance, which not only improves the film-forming performance and adhesion to the substrate of the dry film, but also effectively reduces internal ion migration.

[0048] 3. This application effectively improves the high temperature resistance and flame retardant properties of dry film by compounding inorganic fillers with different particle sizes, and reduces ion migration caused by the hydrolysis of phosphorus-based flame retardants.

[0049] 4. The solder resist dry film of this application has good flexibility, flame retardancy, high temperature resistance, low coefficient of thermal expansion, salt spray resistance and chemical resistance, and can be used in the manufacture of PCB circuit boards, and exhibits excellent reliability. Detailed Implementation

[0050] Example Example 1 The present invention first provides a highly reliable solder resist dry film, wherein the raw materials for preparing the solder resist dry film include: by weight, 40 parts of carboxyl-containing polyurethane resin, 50 parts of epoxy resin, 8 parts of N,N,N',N'-tetra(2-hydroxyethyl)hexamethylenediamide, 115 parts of filler, 2 parts of flame retardant, 0.6 parts by weight of 2-phenyl-4-methylimidazole, and 20 parts of solvent.

[0051] The method for preparing the carboxyl-containing polyurethane resin is as follows: Acrylic acid-modified polyester polyol, dimethylolpropionic acid (CAS: 4767-03-7), and p-benzoquinone (CAS: 106-51-4) are mixed. Then, HDI is added while stirring and heating. Heating is stopped after reaching 60°C. Heating is immediately restarted when the reactor temperature decreases, and the mixture is maintained at 80°C for 2 hours. The weight ratio of acrylic acid-modified polyester polyol, HDI, and dimethylolpropionic acid (CAS: 4767-03-7) is 35:20:7. The amount of p-benzoquinone added is 0.25 wt% of the total amount of acrylic acid-modified polyester polyol, HDI, and dimethylolpropionic acid (CAS: 4767-03-7). The prepared carboxyl-containing polyurethane resin has a hydroxyl value of 135 mg KOH / g and a weight-average molecular weight of 35,000.

[0052] The epoxy resin is a bismaleimide-modified biphenyl phenol type epoxy resin, wherein the weight ratio of bismaleimide to biphenyl phenol type epoxy resin is 1:1.2.

[0053] The filler is a combination of silicon dioxide, aluminum hydroxide and magnesium hydroxide in a weight ratio of 4:3.5:1.6. The average diameter of the silicon dioxide particles is 520 nm, the average diameter of the aluminum hydroxide particles is 100 nm, and the average diameter of the magnesium hydroxide particles is 80 nm.

[0054] The flame retardant is tricresyl phosphate, and the solvent is ethylene glycol monoethyl ether acetate (CAS: 112-15-2).

[0055] Secondly, this invention also provides an application of a highly reliable solder resist dry film on an integrated circuit board. The application steps of the solder resist dry film are as follows: S1. Mix the raw materials for preparing the solder resist dry film and coat them onto a polyester carrier film. Dry the film at 80°C. The thickness of the solder resist dry film is 25μm. Then, attach the release protective film to the adhesive layer to obtain the solder resist dry film. S2. After removing the release liner and covering the PCB substrate, vacuum press-fit the substrate at 60℃ and a pressing pressure of 0.5 kg / cm². 2 The pressing time is 20 seconds.

[0056] S3. The integrated circuit board undergoes exposure, development, and curing processes.

[0057] Example 2 The present invention first provides a highly reliable solder resist dry film, wherein the raw materials for preparing the solder resist dry film include: by weight, 35 parts of carboxyl-containing polyurethane resin, 60 parts of epoxy resin, 10 parts of N,N,N',N'-tetra(2-hydroxyethyl)hexamethylenediamide, 120 parts of filler, 1 part of flame retardant, 0.8 parts by weight of 2-phenyl-4-methylimidazole, and 25 parts of solvent.

[0058] The method for preparing the carboxyl-containing polyurethane resin is as follows: Acrylic acid-modified polyester polyol, dimethylolpropionic acid (CAS: 4767-03-7), and p-benzoquinone (CAS: 106-51-4) are mixed. Then, HDI is added while stirring and heating. Heating is stopped after reaching 60°C. Heating is immediately restarted when the reactor temperature decreases, and the temperature is maintained at 80°C for 1 hour. The weight ratio of acrylic acid-modified polyester polyol, HDI, and dimethylolpropionic acid is 30:25:9, and the amount of p-benzoquinone added is 0.3 wt% of the total amount of acrylic acid-modified polyester polyol, HDI, and dimethylolpropionic acid (CAS: 4767-03-7). The prepared carboxyl-containing polyurethane resin has a hydroxyl value of 118 mg KOH / g and a weight-average molecular weight of 15000.

[0059] The epoxy resin is a bismaleimide-modified biphenyl phenol type epoxy resin, wherein the weight ratio of bismaleimide to biphenyl phenol type epoxy resin is 0.8:1.5.

[0060] The filler is a combination of silicon dioxide, aluminum hydroxide and magnesium hydroxide in a weight ratio of 5:3:1. The average diameter of the silicon dioxide particles is 350 nm, the average diameter of the aluminum hydroxide particles is 150 nm, and the average diameter of the magnesium hydroxide particles is 120 nm.

[0061] The flame retardant is tricresyl phosphate, and the solvent is ethylene glycol monoethyl ether acetate (CAS: 112-15-2).

[0062] Secondly, this invention also provides an application of a highly reliable solder resist dry film on an integrated circuit board. The application steps of the solder resist dry film are as follows: S1. Mix the raw materials for preparing the solder resist dry film and coat them onto a polyester carrier film. Dry the film at 60°C. The thickness of the solder resist dry film is 15μm. Then, attach the release protective film to the adhesive layer to obtain the solder resist dry film. S2. After removing the release liner and covering the PCB substrate, vacuum press-fit the substrate at 50℃ and a pressing pressure of 0.2 kg / cm². 2 The pressing time is 30 seconds.

[0063] S3. The integrated circuit board undergoes exposure, development, and curing processes.

[0064] Example 3 The present invention first provides a highly reliable solder resist dry film, wherein the raw materials for preparing the solder resist dry film include: by weight, 45 parts of carboxyl-containing polyurethane resin, 40 parts of epoxy resin, 5 parts of N,N,N',N'-tetra(2-hydroxyethyl)hexamethylenediamide, 90 parts of filler, 4 parts of flame retardant, 0.3 parts by weight of 2-phenyl-4-methylimidazole, and 15-25 parts of solvent.

[0065] The method for preparing the carboxyl-containing polyurethane resin is as follows: Acrylic acid-modified polyester polyol, dimethylolpropionic acid (CAS: 4767-03-7), and p-benzoquinone (CAS: 106-51-4) are mixed. Then, HDI is added while stirring and heating. Heating is stopped after reaching 60°C. Heating is immediately restarted when the reactor temperature decreases, and the mixture is maintained at 80°C for 3 hours. The weight ratio of acrylic acid-modified polyester polyol, HDI, and dimethylolpropionic acid is 40:15:6, and the amount of p-benzoquinone added is 0.2 wt% of the total amount of acrylic acid-modified polyester polyol, HDI, and dimethylolpropionic acid (CAS: 4767-03-7). The prepared carboxyl-containing polyurethane resin has a hydroxyl value of 160 mg KOH / g and a weight-average molecular weight of 45000.

[0066] The epoxy resin is a bismaleimide-modified biphenyl phenol type epoxy resin, wherein the weight ratio of bismaleimide to biphenyl phenol type epoxy resin is 1.2:1.

[0067] The filler is a combination of silicon dioxide, aluminum hydroxide and magnesium hydroxide in a weight ratio of 3:4:2. The average diameter of the silicon dioxide particles is 600 nm, the average diameter of the aluminum hydroxide particles is 20 nm, and the average diameter of the magnesium hydroxide particles is 50 nm.

[0068] The flame retardant is tricresyl phosphate, and the solvent is ethylene glycol monoethyl ether acetate (CAS: 112-15-2).

[0069] Secondly, this invention also provides an application of a highly reliable solder resist dry film on an integrated circuit board. The application steps of the solder resist dry film are as follows: S1. Mix the raw materials for preparing the solder resist dry film and coat them onto a polyester carrier film. Dry the film at 85°C. The thickness of the solder resist dry film is 50μm. Then, attach the release protective film to the adhesive layer to obtain the solder resist dry film. S2. After removing the release liner and covering the PCB substrate, vacuum press-fit the substrate at 70℃ and a pressing pressure of 0.7 kg / cm². 2 The pressing time is 15 seconds.

[0070] S3. The integrated circuit board undergoes exposure, development, and curing processes.

[0071] Comparative Example 1 Same as Example 1, except that: the weight ratio of acrylic acid modified polyester polyol, HDI, and dimethylolpropionic acid (CAS: 4767-03-7) is 50:15:7, and the amount of p-benzoquinone added is 0.25wt% of the total amount of acrylic acid modified polyester polyol, HDI, and dimethylolpropionic acid (CAS: 4767-03-7); the prepared carboxyl-containing polyurethane resin has a hydroxyl value of 220mg KOH / g and a weight-average molecular weight of 53000.

[0072] Comparative Example 2 Same as Example 1, except that: the epoxy resin is a bismaleimide-modified biphenyl phenol type epoxy resin, wherein the weight ratio of bismaleimide to biphenyl phenol type epoxy resin is 2:1.

[0073] Comparative Example 3 Same as Example 1, except that the filler is a combination of silicon dioxide, aluminum hydroxide and magnesium hydroxide in a weight ratio of 5:1:1.

[0074] Comparative Example 4 Same as Example 1, except that: the average diameter of the silicon dioxide particles is 350 nm, the average diameter of the aluminum hydroxide particles is 220 nm, and the average diameter of the magnesium hydroxide particles is 150 nm.

[0075] Comparative Example 5 Same as Example 1, except that the raw materials for preparing the solder resist dry film include: by weight, 70 parts of carboxyl-containing polyurethane resin, 30 parts of epoxy resin, 8 parts of N,N,N',N'-tetra(2-hydroxyethyl)hexamethylenediamide, 115 parts of filler, 2 parts of flame retardant, 1.2 parts by weight of 2-phenyl-4-methylimidazole, and 20 parts of solvent.

[0076] The acrylic-modified polyester polyol was purchased from Guangzhou Deqing Jixin Synthetic Resin Co., Ltd., LR-6363; the biphenyl phenol type epoxy resin was purchased from Hunan Jiashengde Materials Technology Co., Ltd., BPNE3501; the tricresyl phosphate was purchased from Wuhan Beiguofeng Chemical Co., Ltd., TCP; the silica was purchased from Foshan Oulite New Materials Technology Co., Ltd.; and the aluminum hydroxide and magnesium hydroxide were purchased from Hangzhou Hengna New Materials Co., Ltd.

[0077] Performance testing methods: Circuit board material information: The board material is FR4-S1000, substrate thickness is 1.5mm, double-sided copper plating, copper plating layer thickness is 2oz. In this example, the release liner is a PET release film with a thickness of 25μm, and the polyester carrier film has a thickness of 38μm. The circuit board with vacuum-pressed solder resist dry film in this example is exposed using a UV exposure machine with a wavelength of 365nm to remove the carrier film, immersed in a 1wt% sodium carbonate aqueous solution at 30℃ for development for 40s, and then heated and cured at 160℃ for 1 hour. The test pieces of this example are subjected to flame retardancy, electroless nickel-palladium-gold resistance, PCT test, and HAST test.

[0078] 1. Electroless Nickel-Gold Resistance: Using commercially available electroless nickel plating solutions and electroless gold plating solutions, plating was performed at a nickel thickness of 0.5 μm and a gold thickness of 0.03 μm. The presence or absence of solder resist dry film penetration was assessed, followed by evaluation of solder resist dry film peeling through tape. Evaluation criteria: 1. No penetration or peeling observed; 2. A small amount of penetration was confirmed after plating, but no peeling was observed after tape peeling; 3. Peeling occurred after tape peeling.

[0079] 2. PCT test: Place the test plate from step 1 in a high-pressure, high-temperature and high-humidity bath at 121℃, 2 atmospheres, and 100% humidity for 50 hours. Evaluation criteria: 1. No obvious expansion or discoloration; 2. Some peeling or discoloration, but not obvious; 3. Obvious expansion and discoloration.

[0080] 3. HAST Test: The substrate circuit has a finger comb type with an L / S ratio of 15 / 15μm. Under 130℃ and 85% humidity, a 10V bias voltage is applied, and the resistance value is measured after 96 hours, and the dry film condition is observed. The resistance value is classified as follows: 1. Greater than 10... 8 Ω, 2, in 10 6 Ω and 10 8 Between Ω, 3, less than 10 6 Ω.

[0081] The flame retardancy of all embodiments passed the UL94VTM-0 test. Other test results are shown in Table 1.

[0082] Performance test results: Table 1

Claims

1. A highly reliable solder resist dry film, characterized in that, The raw materials for preparation include, by weight, 35-45 parts of carboxyl-containing polyurethane resin, 40-60 parts of epoxy resin, 5-10 parts of curing agent, 90-120 parts of filler, 1-4 parts of flame retardant, and 15-25 parts of solvent.

2. The high-reliability solder resist dry film according to claim 1, characterized in that, The carboxyl-containing polyurethane resin is obtained by polymerizing alcohol polymers, diisocyanates, and dimethylolpropionic acid.

3. The high-reliability solder resist dry film according to claim 2, characterized in that, The weight ratio of the alcohol polymer, diisocyanate, and dimethylolpropionic acid is (30-40):(15-25):(6-9).

4. The high-reliability solder resist dry film according to claim 3, characterized in that, The carboxyl-containing polyurethane resin has a hydroxyl value of 50-160 mg KOH / g and a weight-average molecular weight of 8000-50000.

5. The high-reliability solder resist dry film according to claim 4, characterized in that, The epoxy resin is a bismaleimide-modified biphenyl phenol type epoxy resin.

6. The high-reliability solder resist dry film according to claim 5, characterized in that, The filler is a combination of silicon dioxide, aluminum hydroxide and magnesium hydroxide.

7. The high-reliability solder resist dry film according to claim 6, characterized in that, The raw materials for preparation also include 0.1-3 parts by weight of nitrogen-containing heterocyclic compounds.

8. The high-reliability solder resist dry film according to claim 7, characterized in that, The weight ratio of the carboxyl-containing polyurethane resin, nitrogen-containing heterocyclic compound, and epoxy resin is (3-6):(0.03-0.1):(1-6).

9. The application of a high-reliability solder resist dry film according to any one of claims 1-8 on an integrated circuit board.

10. The application of a high-reliability solder resist dry film according to claim 9 on an integrated circuit board, characterized in that, The application steps for solder resist dry film are as follows: S1. Mix the raw materials for preparing the solder resist dry film and coat them onto a polyester carrier film. Dry the film at a temperature of 60-85℃ and then apply the release protective film to the adhesive layer to obtain the solder resist dry film. S2. After removing the release liner and covering the surface of the integrated circuit board with the solder mask, perform vacuum bonding at a temperature of 50-70℃ and a bonding pressure of 0.2-0.7 kg / cm². 2 ; S3. The integrated circuit board undergoes exposure, development, and curing processes.

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