JP2018083853A - Led-curable moisture-proof insulation coating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition that is a moisture-proof insulation coating material used in a circuit board on which electronic components are mounted, can be cured in a short time even when an irradiating light source is an LED and is excellent in insulation reliability, and has low irritation to skin, and a circuit board insulation treated therewith.SOLUTION: An LED-curable moisture-proof insulation coating material composition that is a photo-curable resin composition including: urethane acrylate (A) that is synthesized from hydrogenated polybutadiene diol and has a number average molecular weight of 1,000 to 20,000; a photopolymerizable monofunctional monomer (B) containing at least noncyclic (meth)acrylamide-based monomer; and an initiator (C) having an absorption band at a wavelength of 380 nm or longer, in which a content of the noncyclic (meth)acrylamide-based monomer is 0.5 to 8% by weight relative to an entire composition, a content of the (C) component is 9 to 15% by weight relative to 100 parts of the entirety of the (A) component and the (B) component, and a packaging circuit board that is insulation-treated therewith.SELECTED DRAWING: None

Description

The present invention is a moisture-proof insulating coating agent used on a circuit board on which electronic components are mounted, and more specifically, can be cured in a short time with an LED (light emitting diode) light source, has excellent insulation reliability, and irritation to the skin. The present invention relates to a composition having low characteristics and a mounted circuit board that is insulated using the composition.

  When mounting electronic components such as semiconductors on printed wiring boards such as glass epoxy, paper phenol, and polyimide, a moisture-proof insulating coating agent is applied to the connection area to improve connection reliability. There is. Conventionally, a thermosetting resin or a method of drying after applying a resin dissolved in an organic solvent is generally used for this coating agent. However, in the case of a thermosetting resin, there is a problem in productivity because a heating process is required for resin curing and it takes a long time to cure. There was.

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

JP 2009-179655 A 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, and can be cured in a short time even when the light source to be irradiated is an LED, has excellent insulation reliability, and has low irritation to skin And a circuit board that is insulated using the composition.

The invention described in claim 1 includes urethane acrylate (A) synthesized from hydrogenated polybutadiene diol having a number average molecular weight (hereinafter referred to as “Mn.”) Of 1,000 to 20,000, and at least acyclic (meta) ) A photocurable resin composition comprising a photopolymerizable monofunctional monomer (B) containing an acrylamide monomer and an initiator (C) having an absorption band at a wavelength of 380 nm or more, which is acyclic (meta) The content of the acrylamide monomer is 0.5 to 8% by weight with respect to the whole composition, and the content of the component (C) is 9 to 15% by weight with respect to the total 100 weights of the components (A) and (B). An LED curable moisture-proof insulating coating agent composition is provided.

The invention according to claim 2 is a claim in which the photopolymerizable monofunctional monomer (B) further includes a (meth) acrylate monomer containing an aliphatic cyclic skeleton and a (meth) acrylate monomer containing a linear alkyl group. An LED curable moisture-proof insulating coating agent composition according to Item 1, is provided.

  The invention according to claim 3 provides the LED curable moisture-proof insulating coating composition according to claim 1 or 2, wherein the photopolymerizable monofunctional monomer (B) has a PII value of 2.5 or less. To do.

The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the initiator (C) has a wavelength absorption at 380 nm of 0.5% or more in a 0.1% acetonitrile solution. An LED curable moisture-proof insulating coating agent composition is provided.

  According to a fifth aspect of the present invention, there is provided a mounting circuit board which is insulated using the LED curable moisture-proof insulating coating composition according to any one of the first to fourth aspects.

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

  The present invention will be described in detail below.

The composition of the present invention is composed of Mn. Of 1,000 to 20,000 urethane acrylate (A), a photopolymerizable monofunctional monomer (B) containing at least an acyclic (meth) acrylamide monomer, and an initiator having an absorption band at a wavelength of 380 nm or more (C ). In the present specification, (meth) acrylate includes both acrylate and methacrylate.

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

Examples of the compound having a plurality of isocyanate groups used in the present invention (A) include hexamethylene diisocyanate, heptamethylene diisocyanate, octamethylene diisocyanate, tolylene diisocyanate, methylcyclohexane diisocyanate, dicyclohexylmethane diisocyanate, 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 preferred. Examples of the (meth) acrylate having a hydroxyl group include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, and 2-hydroxyethyl methacrylate. Among these, 2-hydroxyethyl acrylate is preferable.

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 property balance of the composition, with respect to the total composition of (A) and (B). Is more preferable. By setting it to 25% by weight or more, moisture permeability can be stably lowered, and by setting it to 40% by weight or less, the viscosity does not become too high and workability is stabilized. Examples of commercially available urethane acrylates having a hydrogenated polybutadiene skeleton include Excelate RX 71-44 (trade name: manufactured by Asia Industrial Co., Ltd., number average molecular weight 3,000), RX 71-67 (trade name: manufactured by Asia Industrial Co., Ltd., number average molecular weight 13, 000).

  The photopolymerizable monofunctional monomer (B) containing at least an acyclic (meth) acrylamide monomer used in the present invention is blended to increase the film hardness by reacting with (A) at the same time as (A) is diluted. The In order to suppress irritation to the skin, an acyclic (meth) acrylamide monomer is an essential component, and other monomers are aliphatic cyclic from the viewpoint of adhesion to the substrate, moisture permeability, compatibility with (A), etc. A (meth) acrylate monomer containing a skeleton and a (meth) acrylate monomer containing a linear alkyl group are preferred. In order to suppress irritation to the skin, the PII value (primary irritation index) is preferably 2.5 or less.

The blending amount of the acyclic (meth) acrylamide 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 whole composition becomes low, so that the peel strength is lowered. If it exceeds 8% by weight, the compatibility balance is lost and phase separation occurs. Furthermore, 0.5 to 10 weight% is preferable and the acyclic (meth) acrylamide type monomer with respect to the whole (B) is more preferable 1 to 7 weight%. Skin irritation can be reduced at 0.5% by weight or more, and 10% by weight or less ensures sufficient compatibility with other components and ensures good storage stability 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 properties such as film strength and viscosity, with respect to the total composition of (A) and (B). A viscosity suitable for workability can be ensured by setting it to 60% by weight or more, and a good balance between curing shrinkage and curability can be achieved by setting it to 75% by weight or less. About the polyfunctional monomer more than bifunctional, since the hardness of a cured film becomes high too much and peeling strength falls, it is not preferable.

Examples of (meth) acrylates containing acyclic amino groups 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 (meta ) Acrylamide, diacetone acrylamide, hydroxyethyl acrylamide and the like can be mentioned, and these can be used alone or in combination of two or more. Of these, hydroxyethylacrylamide having low skin irritation and low odor is preferred. A (meth) acrylate having a cyclic amino group such as acryloylmorpholine 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, cyclohexyl (meth) acrylate, and the like. Can be used alone or in combination of two or more. Among these, isobornyl acrylate is preferable from the viewpoint of low viscosity and 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. Among these, versatility, good dilution, low From the viewpoint of odor and low outgas, n-octyl acrylate is preferred.

  The photopolymerization initiator (C) used in the present invention generates radicals by absorption of ultraviolet rays, electron beams, and the like, and the radicals trigger a polymerization reaction, and has an absorption band at an emission wavelength of 380 nm or more of the LED. The characteristic with is necessary. The blending amount is 9 to 15% by weight based on 100% of the total composition of (A) and (B). If it is less than 9% by weight, fast curability cannot be obtained, and tack remains on the surface. Stability issues can arise.

  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 in a solution (C) 0.1% dissolved in acetonitrile 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-morpholin-4-yl- Phenyl) -butan-1-one, bis (2.4.6-trimethylbenzoyl) -phenylphosphine oxide, 2.4.6-trimethylbenzoyl-diphenyl-phosphine oxazide, alone or in combination Can be used in combination. Examples of commercially available products include Irgacure 379, 379EG, 369 and 369E, Lucirin TPO, Darocur 4265 (trade name: manufactured by BASF Japan).

If necessary, the composition contains a curing aid, a silane coupling agent, a plasticizer, a sensitizer, an antioxidant, an anti-aging agent, an antifoaming agent, a flame retardant, a filler, a polymerization inhibitor, a colorant, Additives such as leveling agents, dispersants, thixotropic agents may be used in combination.

The mounting circuit board of the present invention can be obtained by applying the composition to a printed wiring board on which an electronic device such as a semiconductor, a flat panel display, or a resistor is mounted, and subjecting the bonded portion to insulation treatment. The method for applying the composition to a printed wiring board is not particularly specified, and known methods such as a brush coating method, a spray method, a dipping method, and a coating method using a dispenser can be used. After coating, the film is cured by irradiating with ultraviolet rays using an LED as a light source to obtain a mounted circuit board. 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.

  The composition is characterized by very low skin irritation. Some reactive oligomers and monomers are irritating to the skin and mucous membranes, and even if they are less irritating, long-term exposure may cause problems in actual production sites. In general, when a chemical substance touches the skin, a substance having a small molecular weight has a large influence 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 in an actual production line.

EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example and a comparative example, a specific example is shown and it does not specifically limit to these. In addition, when there is no description, it measured on the conditions of 25 degreeC relative humidity 65% of room temperature.

Example 1
Mn. Synthesized from hydrogenated polybutadiene diol. Exelate RX71-44 (trade name: manufactured by Asia Industrial Co., Ltd., Mn. 3,000) as urethane acrylate (A) having a molecular weight of 1,000 to 20,000, and HEAA (trade name as photopolymerizable monofunctional monomer (B)) : KJ Chemicals, hydroxyethylacrylamide, PII value 0) and IB-XA (trade name: Kyoeisha Chemical Co., isobornyl acrylate, PII value 0.6) and NOAA (trade name: Osaka Organic Chemical Industries, Ltd.) , N-octyl acrylate, PII value 0.7), using Irgacure 379EG (trade name: manufactured by BASF Japan Ltd., wavelength absorption rate of 380 nm is 1.0%) as an initiator (C), according to the formulation shown in Table 1. It stirred until it melt | dissolved uniformly and the moisture-proof insulation coating agent composition of Example 1 was adjusted.

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

Comparative Examples 1-7
In addition to the materials used in the examples, urethane acrylate RX8-7 (trade name: manufactured by Asia Kogyo Co., Ltd.) having a polytetramethylene glycol skeleton was used as 4BBA (trade name: Osaka Organic Chemical Industry Co., Ltd., 4 hydroxybutyl). Acrylate, PII value 3.0) and ACMO (trade name: manufactured by KJ Chemicals, acryloylmorpholine, PII value 0.5) as an initiator, Irgacure 184 (trade name: manufactured by BASF Japan Ltd., wavelength absorption at 380 nm is 0) 0.1% or less) and Lucirin TPO (trade name: manufactured by BASF Japan, wavelength absorption at 380 nm is 1.5%), and KAYACUREDETX-S (trade name: manufactured by Nippon Kayaku Co., Ltd., thioxanthone series) as a photosensitizer Use the moisture-proof insulating coating agent of Comparative Examples 1-7 by stirring until it is uniformly dissolved with the formulation shown in Table 1. Narubutsu was adjusted.

Table 1 (parts by weight)

The evaluation method was as follows.

Surface curability: A moisture-proof insulating coating agent composition is applied on a glass plate to a thickness of 100 μm, and an LED-UV irradiation device UD-40 manufactured by Panasonic is used from above, and the output is 400 mW / cm ² and the integrated light quantity is It is cured by ultraviolet irradiation so that it becomes 1000 mJ / cm ^2, and the presence or absence of stickiness on the surface of the film is confirmed by finger touch, ○ if there is no stickiness, △ if there is stickiness but the resin does not stick to the finger, and if stickiness is present, the resin is fingered The mark attached to was marked with ×.

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

  Peel strength: A moisture-proof insulating coating agent composition was applied on a glass plate to a thickness of 100 μm, and a PET film (trade name, manufactured by Toyobo, A4300, thickness 125 μm) cut to a width of 24 mm was superimposed on the glass plate. Peeling when the PET film end is pulled at 180 ° direction at a crosshead speed of 300 mm / min using Minebea's tensile compression tester Technograph TGI-1kN under the same conditions as above. The strength was measured, and a peel strength of 50 N / m or more was rated as ○, and a value less than 50 N / m was rated as x. The ultraviolet irradiation conditions are the same in the following unless there is a special notation.

Migration test: Moisture-proof insulation on ITO electrode substrate (line between anode / cathode / space = 15/15 μm) drawn on an area of 0.6 × 10.2 mm on a plate glass of 25 × 50 mm to a thickness of 100 μm Applying a coating agent, preparing a test piece cured by irradiating with ultraviolet rays under the same conditions as above, applying DC5V in an environment of 60 ° C./90% RH, and insulation resistance change and corrosivity after 300 hours Evaluation was made by visually observing no corrosion as ◯ and corrosion as x.

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

Evaluation results <br/> Table 2

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

On the other hand, Comparative Example 1 in which a cyclic amide was blended instead of a non-cyclic (meth) acrylamide monomer and Comparative Example 3 with a small amount of HEAA were inferior in peel strength, and Comparative Example 2 in which the amount of initiator (C) was less than 9%. Was inferior in surface curability. Further, Comparative Examples 5, 6 and 7 containing 4HBA instead of acyclic (meth) acrylamide monomers have a problem of skin irritation, and Comparative Example 6 containing (C) which is not applicable to Claim 4 The comparative example 7 which mix | blended urethane acrylates other than (A) was also inferior in surface curability. Further, Comparative Example 4 with a lot 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 on a circuit board on which electronic components are mounted, and can be cured in a short time even when the illuminating light source is an LED, and has excellent insulation reliability and low skin irritation. Useful as.

Claims (5)

A urethane acrylate (A) having a number average molecular weight of 1,000 to 20,000 synthesized from hydrogenated polybutadiene diol, a photopolymerizable monofunctional monomer (B) containing at least an acyclic (meth) acrylamide monomer, A photocurable resin composition comprising an initiator (C) having an absorption band at a wavelength of 380 nm or more, wherein the content of the acyclic (meth) acrylamide monomer is 0.5 to 8 with respect to the entire composition. The LED curable moisture-proof and insulating coating composition, wherein the content of the component (C) is 9 to 15% by weight based on 100% by weight in total of the component (A) and the component (B).   The LED curable moisture-proof according to claim 1, wherein the photopolymerizable monofunctional monomer (B) further includes a (meth) acrylate monomer containing an aliphatic cyclic skeleton and a (meth) acrylate monomer containing a linear alkyl group. Insulating coating agent composition.   The LED curable moisture-proof insulating coating composition according to claim 1, wherein the photopolymerizable monofunctional monomer (B) has a PII value of 2.5 or less. 4. The LED curable moisture-proof insulating coating composition according to claim 1, wherein the initiator (C) has a wavelength absorption at 380 nm of 0.5% or more in a 0.1% acetonitrile solution. 5. object. A mounting circuit board that is insulated using the LED curable moisture-proof insulating coating composition according to claim 1.