JP6857013B2 - LED curable moisture-proof insulation coating agent - Google Patents

Description

The present invention is a moisture-proof insulating coating agent used in a circuit board on which an electronic component is mounted. More specifically, it can be cured in a short time by an LED (light emitting diode) light source, has excellent insulation reliability, and is irritating to the skin. The present invention relates to a composition having a low characteristic, and a mounting circuit board to which an insulation treatment is performed using the composition.

When an electronic component such as a semiconductor is mounted on a printed wiring board typified by a base material such as glass epoxy, paper phenol, or polyimide, a moisture-proof insulating coating agent is applied to the connection portion to improve connection reliability. There is. Conventionally, a method of using a thermosetting resin or a method of applying a resin dissolved in an organic solvent and then drying it has been generally used for this coating agent. However, in the case of thermosetting resins, there is a problem in productivity because a heating process is required for resin curing and it takes a long time to cure, and resins using organic solvents have a problem that the load on the environment is high because the solvent is volatilized at the time of application. There was.

In order to solve these problems, an ultraviolet curable coating agent that can be cured in a short time has been developed. For example, Patent Document 1 discloses a composition containing polybutadiene having an acryloxy group or a methacryloxy group at the end, a monomer having an unsaturated double bond, and a polymerization initiator. Furthermore, as a coating agent having low moisture permeability and sufficient adhesiveness to the substrate material, in Patent Document 2, a urethane compound having an ethylenically unsaturated double bond synthesized from hydrogenated polybutadiene diol and isobornyl acrylate And benzophenone-containing compositions are disclosed. However, since these compositions have good ON / OFF responsiveness and long life, there is a problem that the curability of these compositions is insufficient for LED light sources, which have been rapidly increasing in recent years. Further, depending on the type of the reactive diluent and the monomer, there is a problem of skin irritation, and there is room for improvement.

JP-A-2009-179655 Japanese Patent No. 5162893

The present invention is a moisture-proof insulating coating agent used in a circuit board on which electronic components are mounted. Even when the light source to be irradiated is an LED, it can be cured in a short time, has excellent insulation reliability, and has low skin irritation. It is an object of the present invention to provide a circuit board having an insulation treatment using the composition having the above.

The invention according to claim 1 comprises a urethane acrylate (A) synthesized from a hydrogenated polybutadiene diol and having a number average molecular weight of 1,000 to 20,000, and at least an acyclic (meth) acrylamide-based monomer and an aliphatic cyclic skeleton. A photopolymerizable monofunctional monomer (B) containing a (meth) acrylate monomer containing a linear alkyl group and a (meth) acrylate monomer containing a linear alkyl group, and an initiator (C) having an absorption band at a wavelength of 380 nm or more. In the photocurable resin composition, the content of the acyclic (meth) acrylamide-based monomer is 0.5 to 8% by weight with respect to the entire composition, and the content of the component (C) is the component (A) and ( B) Provided is an LED curable moisture-proof insulating coating agent composition which is 9 to 15% by weight based on 100% by weight of the total components.

The LED curing type according to claim 1, wherein the blending amount of (B) is 60 to 75% by weight based on the total amount of the compositions of (A) and (B). A moisture-proof insulating coating agent composition is provided.

The invention according to claim 3 provides a mounting circuit board, which is subjected to an insulation treatment using the LED curable moisture-proof insulating coating agent composition according to any one of claims 1 or 2.

The moisture-proof and insulating coating agent of the present invention is an ultraviolet-curable resin composition that is excellent in moisture-proof and insulating properties, and can be cured in a short time even when the light source to be irradiated is an LED, and has a property of low irritation to the skin. ..

Hereinafter, the present invention will be described in detail.

The composition of the composition of the present invention is Mn. Synthesized from hydrogenated polybutadiene diol. A photopolymerizable monofunctional monomer (B) containing a urethane acrylate (A) having a value of 1,000 to 20,000 and at least an acyclic (meth) acrylamide-based monomer, and an initiator (C) having an absorption band at a wavelength of 380 nm or more. ). In addition, in this specification, (meth) acrylate includes both acrylate and methacrylate.

Mn. Synthesized from the hydrogenated polybutadiene diol of the present invention. The urethane acrylate (A) having a value of 1,000 to 20,000 is a base oligomer constituting a moisture-proof insulating layer, and the polyol is reacted with a compound having a plurality of isocyanate groups and a (meth) acrylate having a hydroxyl group. Can be obtained. The polyol used is a hydrogenated polybutadiene type that has low moisture permeability, excellent insulating properties, and imparts appropriate flexibility to the molded film. Mn. If it is less than 1,000, the obtained cured product has strong adhesiveness and a sticky feeling remains on the surface, and if it exceeds 20,000, the viscosity of the composition becomes high, which adversely affects workability. The number average molecular weight was measured and calculated in terms of standard polystyrene by a gel permeation chromatography method using a tetrahydrofuran developing solvent on a column based on styrenedivinylbenzene.

Examples of the compound having a plurality of isocyanate groups, which is the raw material of (A) used in the present invention, include hexamethylene diisocyanate, heptamethylene diisocyanate, octamethylene diisocyanate, tolylene diisocyanate, methylcyclohexane diisocyanate, dicyclohexylmethane diisocyanate, and isophorone. There are diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate, which can be used alone or in combination of two or more. Of these, isophorone diisocyanate is preferable. Examples of the (meth) acrylate having a hydroxyl group include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, and 2-hydroxyethyl methacrylate, and 2-hydroxyethyl acrylate is preferable among these.

The blending amount of (A) is preferably 25 to 40% by weight, preferably 30 to 35% by weight, based on the moisture permeability of the cured product and the characteristic balance of the composition with respect to the total composition of (A) and (B). Is more preferable. When it is 25% by weight or more, the moisture permeability can be stably lowered, and when it is 40% by weight or less, the viscosity does not become too high and the workability is stable. Commercially available urethane clearates having a hydrogenated polybutadiene skeleton include Excelate RX71-44 (trade name: manufactured by Asia Industries, Ltd., number average molecular weight of 3,000), RX71-67 (trade name: manufactured by Asia Industries, Ltd., number average molecular weight of 13,). 000) and so on.

The photopolymerizable monofunctional monomer (B) containing at least an acyclic (meth) acrylamide-based monomer used in the present invention is formulated to dilute (A) and at the same time react with (A) to increase the film hardness. To. An acyclic (meth) acrylamide-based monomer is an essential component to suppress irritation to the skin, and the other monomer is an aliphatic cyclic from the viewpoints of adhesion to the base material, moisture permeability, compatibility with (A), and the like. It is preferably a (meth) acrylate monomer containing a skeleton and a (meth) acrylate nomer containing a linear alkyl group. Further, the PII value (primary irritation index) is preferably 2.5 or less in order to suppress irritation to the skin.

The blending amount of the acyclic (meth) acrylamide-based monomer is 0.5 to 8% by weight, more preferably 0.8 to 5% by weight, based on the entire composition. If it is less than 0.5% by weight, the polarity of the entire composition becomes low, so that the peel strength decreases, and if it exceeds 8% by weight, the compatibility balance is lost and phase separation occurs. Further, the acyclic (meth) acrylamide-based monomer with respect to the whole (B) is preferably 0.5 to 10% by weight, more preferably 1 to 7% by weight. Irritation to the skin can be reduced with 0.5% by weight or more, and sufficient compatibility with other components is ensured with 10% by weight or less, and good storage stability is ensured without causing phase separation. be able to.

The blending amount of (B) is preferably 60 to 75% by weight, more preferably 65 to 70% by weight, based on the balance of characteristics such as film strength and viscosity with respect to the total composition of (A) and (B). When it is 60% by weight or more, a viscosity suitable for workability can be secured, and when it is 75% by weight or less, a good balance between curing shrinkage and curability can be achieved. A polyfunctional monomer having two or more functionalities is not preferable because the hardness of the cured film becomes too high and the peel strength decreases.

Examples of the (meth) acrylate containing an acyclic amino group include (meth) acrylamide, N, N-dimethylacrylamide, N, N-diethylacrylamide, N, N-dipropyl (meth) acrylamide, and N-methyl (meth). Acrylamide, N-ethyl (meth) acrylamide, N-isopropylacrylamide, N-butyl (meth) acrylamide, Nn-butoxymethyl (meth) acrylamide, N-isobutoxymethyl (meth) acrylamide, N-methoxymethyl (meth) ) Acrylamide, diacetoneacrylamide, hydroxyethylacrylamide and the like can be mentioned, and can be used alone or in combination of two or more. Among these, hydroxyethyl acrylamide, which has low skin irritation and low odor, is preferable. A (meth) acrylate having a cyclic amino group such as acryloyl morpholine is not preferable because the cured film becomes too hard and the peel strength decreases.

Examples of the (meth) acrylate having an aliphatic cyclic skeleton include dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, isobornyl (meth) acrylate, adamantanyl (meth) acrylate, and cyclohexyl (meth) acrylate. Can be used alone or in combination of two or more. Among these, isobornyl acrylate is preferable from the viewpoint of low viscosity, skin irritation and odor.

Examples of the (meth) acrylate having a linear alkyl structure include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, and n-pentyl (meth) acrylate. , N-hexyl (meth) acrylate, n-octyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, stearyl (meth) acrylate, etc. From the viewpoint of odor and low outgas, n-octyl acrylate is preferable.

The photopolymerization initiator (C) used in the present invention generates radicals by absorption of ultraviolet rays, electron beams, etc., and the radicals trigger a polymerization reaction. The absorption band is 380 nm or more, which is the emission wavelength of the LED. It is necessary to have the property of. The blending amount is 9 to 15% by weight based on 100% by weight of the total composition of (A) and (B). If it is less than 9% by weight, quick curing is not obtained and tack remains on the surface, and if it exceeds 15% by weight, it is stored. Stability problems can occur.

As an index having an absorption band at 380 nm or more, the absorption amount at 380 nm when the absorption spectrum of each wavelength is measured with a spectroscopic hardness meter of the solution (C) dissolved in acetonitrile by 0.1% is 0.5% or more. Things are desirable. For example, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1, 2-dimethylamino-2- (4-methyl-benzyl) -1- (4-moriphorin-4-yl-) Phenyl) -butane-1-one, bis (2.4.6-trimethylbenzoyl) -phenylphosphine oxide, 2.4.6-trimethylbenzoyl-diphenyl-phosphine oxide, alone or in combination of two or more. Can be used in combination. Commercially available products include Irgacare 379, 379EG, 369 and 369E, Lucirin TPO, and Darocur 4265 (trade name: manufactured by BASF Japan Ltd.).

The composition may include curing aids, silane coupling agents, plasticizers, sensitizers, antioxidants, antioxidants, defoamers, flame retardants, fillers, polymerization inhibitors, colorants, as needed. Additives such as leveling agents, dispersants, and thixo-imparting agents can also be used in combination.

The mounting circuit board of the present invention can be obtained by applying the present composition to a printed wiring board on which electronic devices such as semiconductors, flat panel displays, and resistors are mounted, and insulating the joint portion. The method for applying the present composition to the printed wiring board is not particularly specified, and known methods such as a brush coating method, a spray method, a dipping method, and a dispenser coating method can be used. After coating, the film is cured by irradiating ultraviolet rays using an LED as a light source to obtain a mounting circuit board. Further, the light source for ultraviolet irradiation is not limited to the LED, and a known light source such as a high-pressure mercury lamp or a metal halide lamp may be used.

This composition is characterized by having very low skin irritation. Some reactive oligomers and monomers are irritating to the skin and mucous membranes, and even low irritation can be problematic in actual production sites with prolonged exposure. Generally, when a chemical substance comes into contact with the skin, a substance having a small molecular weight tends to have a large effect because it has high permeability to the skin, and a substance having a large polarity tends to be more irritating. The present invention refers to the primary irritation index (PII value) of the monomer, and there is no problem even if it is used for a long period of 3 months or more on an actual production line.

Hereinafter, the present invention will be described in detail based on Examples and Comparative Examples, but specific examples are shown and the present invention is not particularly limited thereto. Unless otherwise specified, the measurement was performed under the conditions of room temperature of 25 ° C. and relative humidity of 65%.

Example 1
Mn. Synthesized from hydrogenated polybutadiene diol. ExcelateRX71-44 (trade name: manufactured by Asia Industries, Ltd., Mn.3,000) as a urethane acrylate (A) having a value of 1,000 to 20,000, and HEAA (trade name) as a photopolymerizable monofunctional monomer (B). : KJ Chemicals, hydroxyethyl acrylamide, PII value 0) and IB-XA (trade name: Kyoeisha Chemical Co., Ltd., isobornyl acrylate, PII value 0.6) and NOAA (trade name: Osaka Organic Chemical Industry Co., Ltd.) , N-octyl acrylate, PII value 0.7), using Irgacure379EG (trade name: BASF Japan, Inc., 380 nm wavelength absorption rate: 1.0%) as the initiator (C), with the formulation shown in Table 1. The moisture-proof insulating coating composition of Example 1 was prepared by stirring until it was uniformly dissolved.

Examples 2-4
Using the material used in Example 1, the blending amount was changed as shown in Table 1 and stirred until uniformly dissolved to prepare the moisture-proof insulating coating composition of Examples 2-4.

Comparative Examples 1 to 7
In addition to the materials used in the examples, urethane acrylate RX8-7 (trade name: manufactured by Asia Industries, Ltd.) having a polytetramethylene glycol skeleton was used as (B), and 4HBA (trade name: manufactured by Osaka Organic Chemical Industry Co., Ltd.) was used as 4HBA. Acrylate, PII value 3.0) and ACMO (trade name: KJ Chemicals, acryloylmorpholin, PII value 0.5) as an initiator, Irgacure184 (trade name: BASF Japan, 380 nm wavelength absorption rate is 0). .1% or less) and Lucirin TPO (trade name: manufactured by BASF Japan, 380 nm wavelength absorption rate is 1.5%) as a photosensitizer, KAYACUREDETX-S (trade name: manufactured by Nippon Kayaku Co., Ltd., thioxanthone type) The moisture-proof insulating coating composition of Comparative Examples 1 to 7 was prepared by stirring until the mixture was uniformly dissolved in the formulation shown in Table 1.

Table 1 (weight part)

The evaluation method was as follows.

Surface curability: A moisture-proof insulating coating composition is applied onto a glass plate so as to have a thickness of 100 μm, and a Panasonic LED-UV irradiation device UD-40 is used on the glass plate to achieve an output of 400 mW / cm ² and an integrated light amount. It is cured by UV irradiation so that it becomes 1000 mJ / cm ^2, and the presence or absence of stickiness on the film surface is confirmed by touch. The number attached to is x.

Viscosity: Using a cone plate type viscometer RC-550 manufactured by Toki Sangyo, the measurement was performed at a cone angle of 3 ° × R17.65 at 25 ± 1 ° C. and a rotation speed of 20 rpm. From the viewpoint of workability, less than 1,000 mPa · s was marked with ◯, and more than 1,000 mPa · s was marked with x.

Peeling strength: A moisture-proof insulating coating composition is applied on a glass plate so as to have a thickness of 100 μm, and a PET film (trade name, Toyobo Co., Ltd., A4300, thickness 125 μm) cut to a width of 24 mm is superposed on the glass plate. It is cured by irradiating it with ultraviolet rays from above under the same conditions, and peeling when the end of the PET film is pulled in the 180 degree direction at a crosshead speed of 300 mm / min using a tensile compression tester technograph TGI-1kN manufactured by Minebea. The strength was measured, and a peel strength of 50 N / m or more was evaluated as ◯, and a peel strength of less than 50 N / m was evaluated as x. Unless otherwise specified, the ultraviolet irradiation conditions shall be the same as below.

Migration test: Moisture-proof insulation to a thickness of 100 μm on an ITO electrode substrate (line / space between anode / cathode = 15/15 μm) drawn in an area of 0.6 × 10.2 mm on a 25 × 50 mm plate glass. A test piece was prepared by applying a coating agent and irradiating with ultraviolet rays under the same conditions to cure it. DC5V was applied in an environment of 60 ° C./90% RH, and the change in insulation resistance and corrosiveness after 300 hours had passed. After evaluation, no corrosion was visually evaluated as ◯, and with corrosion was evaluated as x.

Skin irritation: A case in which a monomer having a PII value of 2.5 or more was not used was evaluated as ◯, and a case in which a monomer having a PII value of 2.5 or more was used was evaluated as x.

Evaluation result <br /> Table 2

The examples were good with no problems in all aspects of surface curability, viscosity, peel strength, and migration test.

On the other hand, Comparative Example 1 in which cyclic amide was added instead of the acyclic (meth) acrylamide-based monomer and Comparative Example 3 in which HEAA was small had poor peel strength, and Comparative Example 2 in which the amount of the initiator (C) was less than 9% Was inferior in surface curability. Further, Comparative Examples 5, 6 and 7 in which 4HBA was blended instead of the acyclic (meth) acrylamide-based monomer had a problem in skin irritation, and Comparative Example 6 in which (C), which is not applicable to claim 4, was further blended. Comparative Example 7 in which a urethane acrylate other than (A) was blended was also inferior in surface curability. Further, Comparative Example 4 having a large amount of HEAA caused phase separation and could not be evaluated, and none of them was suitable for the present invention.

The present invention is a moisture-proof insulating coating agent used in a circuit board on which an electronic component is mounted. It can be cured in a short time even when the light source to be irradiated is an LED, and has excellent insulation reliability and low irritation to the skin. It is useful as.

Claims (3)

Urethane acrylate (A) synthesized from hydrogenated polybutadiene diol having a number average molecular weight of 1,000 to 20,000, and (meth) acrylate monomer containing at least acyclic (meth) acrylamide-based monomer and aliphatic cyclic skeleton. A photocurable resin composition containing a photopolymerizable monofunctional monomer (B) containing a (meth) acrylate monomer containing a linear alkyl group and an initiator (C) having an absorption band at a wavelength of 380 nm or more. The content of the acyclic (meth) acrylamide-based monomer is 0.5 to 8% by weight based on the entire composition, and the content of the component (C) is 100% by weight in total of the component (A) and the component (B). An LED curable moisture-proof insulating coating composition having a weight of 9 to 15% by weight. The LED curable moisture-proof insulating coating agent composition according to claim 1, wherein the blending amount of (B) is 60 to 75% by weight based on the total amount of the compositions of (A) and (B). A mounting circuit board characterized by being insulated using the LED curable moisture-proof insulating coating agent composition according to any one of claims 1 or 2.