KR20110005485A - Resin composition for printed circuit board and printed circuit board using the same - Google Patents

Abstract

PURPOSE: A resin composition for a printed circuit board is provided to impart tenacity and plasticity to a cured material by introducing an epoxy resin in which acrylic rubber particles with a core-shell structure are dispersed and to reduce thermal stress according to hardening shrinkage. CONSTITUTION: A resin composition for a printed circuit board includes a composite epoxy resin, hardener, curing accelerator and inorganic filler. The composite epoxy resin comprises an epoxy resin in which acrylic rubber particles with a core-shell structure are dispersed, a DGEBA(diglycidyl ether of bisphenol A)-based epoxy resin, a cresol novolac epoxy resin, a rubber-modified epoxy resin, and a phosphor-based epoxy resin.

Description

Resin composition for printed circuit board and printed circuit board using same {Resin composition for printed circuit board and printed circuit board using the same}

The present invention relates to a resin composition for a printed circuit board and a printed circuit board using the same.

The demand for thin boards with fine circuits is increasing along with the high functionality, high capacity, and miniaturization and thinning of mobile phones. In addition, high reliability is required to maintain electrical characteristics in thermal and physical shocks. Therefore, instead of the existing method of fabricating copper foil and insulating layer, for example, prepreg by using vacuum-press, the insulating film was laminated using a build-up method, and then fined by plating. There is a need for an introduction of a method for implementing a circuit.

In order to introduce a new method, it is required to develop a new concept of insulating material that can replace the existing insulating material. The existing build-up insulation material has a peel strength of about 0.5 to 0.8 kN / m depending on the desmear condition, and the build-up insulation material stably exhibiting a value of 1.0 kN / m or more is currently It is not commercialized. However, according to the trend of high performance, high capacity, and slimness of mobile phones, in order to reduce the thickness and fine pattern of mobile phone boards, it is necessary to use insulation materials for build-up on the outer layer of mobile phone boards and to use existing prepregs or Resin Coated Copper (RCC). In order to secure the above-mentioned falling reliability, it is necessary to develop an insulation material for build-up which can exhibit a peel strength value of 1.0 kN / m or more.

The manufacturing process of the existing printed circuit board is made of a prepreg-type insulating material containing glass fiber and copper foil using a copper foil laminated plate using a V-press, and then subjected to a circuit such as plating, exposure, development, peeling, and etching. In this way, as the copper foil and the prepreg are stacked in a V-press, it is difficult to implement a microcircuit due to a certain Cu thickness, and window exposure and an additional process are added to form micro vias after lamination. There are problems such as an increase in manufacturing procurement time and an increase in process cost.

On the other hand, if the insulating material of the build-up method is used, since only the insulating film is formed into a vacuum laminate and then a circuit is formed by plating method, there is no base Cu, so it is easy to implement a fine circuit, and the number of processes can be reduced, thereby increasing productivity. have. Accordingly, in order to introduce a new construction method, the development of a new concept of insulating material that can replace the existing insulating material is urgently required.

The present invention is to solve the above-mentioned problems of the prior art, one aspect of the present invention by introducing an epoxy resin in which the acrylic rubber particles of the core-shell structure is dispersed to give toughness and plasticity to the cured product according to the curing shrinkage It is to provide a resin composition for a printed circuit board and a printed circuit board using the same which can reduce the thermal stress.

Another aspect of the present invention is a resin composition for a printed circuit board and a printed circuit board using the same to prevent excellent defects such as delamination (crack) in the reliability test, such as high temperature thermal shock to secure excellent reliability characteristics To provide.

According to a first preferred aspect of the invention,

Epoxy resin in which core-shell structured acrylic rubber particles are dispersed, digecidyl ether of bisphenol A (DGEBA) epoxy resin, cresol novolac epoxy resin, rubber modified epoxy resin, phosphorus epoxy resin Composite epoxy resin containing; Curing agent; Curing accelerators; And a resin composition for a printed circuit board comprising an inorganic filler is provided.

The acrylic rubber particles preferably have a core-shell structure in which a shell of an acrylic component surrounds a core of the acrylic rubber component.

In the resin composition, the composite epoxy resin, preferably, 1 to 30% by weight of the epoxy resin in which the acrylic rubber particles of the core-shell structure is dispersed, 1 to 20% by weight of DGEBA-based epoxy resin, cresol novolac epoxy resin 30 To 70% by weight, rubber modified epoxy resin 1 to 20% by weight, and phosphorus-based epoxy resin may comprise 10 to 30% by weight.

Wherein the (i) core-shell structured acrylic rubber particle-dispersed epoxy resin, (ii) DGEBA-based epoxy resin, (iii) cresol novolac epoxy resin, (iv) rubber modified epoxy resin and (v) phosphorus-based epoxy resin The average epoxy resin equivalent may be (i) 220 to 240, (ii) 200 to 600, (iii) 100 to 300, (iv) 200 to 400 and (v) 400 to 800, respectively.

The curing agent may preferably be a phenol novolak type curing agent, a bisphenol novolak type curing agent or a mixture thereof.

The curing agent is also preferably contained in 0.5 to 1.5 equivalents relative to the total mixed equivalent of the epoxy groups of the composite epoxy resin.

It is preferable that the said hardening | curing agent has a softening point of 100-140 degreeC, and a hydroxyl group equivalent is 100-150.

The curing agent may also be 1: 0.2 to 1: 1.3 ratio of the epoxy group of the composite epoxy resin and the phenolic hydroxyl group of the curing agent.

The curing accelerator may preferably be an imidazole compound, more preferably 2-ethyl-4-methyl imidazole, 1- (2-cyanoethyl) -2-alkyl imidazole, 2-phenyl imide At least one compound selected from the group consisting of doazoles and mixtures thereof.

On the other hand, with respect to 100 parts by weight of the composite epoxy resin, 0.1 to 1 part by weight of a curing accelerator and 10 to 30 parts by weight of an inorganic filler may be included.

The inorganic filler may be surface treated with a silane coupling agent.

According to a second preferred aspect of the present invention, there is provided a printed circuit board manufactured using the resin composition described above.

The resin composition for a printed circuit board and the printed circuit board using the same according to the present invention may have excellent reliability characteristics to prevent defects such as delamination or cracks at a high temperature thermal shock test.

Accordingly, it is possible to introduce a new method of forming an insulating layer by vacuum lamination of an insulating film made of a composite epoxy resin from a conventional method of laminating a copper foil and a prepreg.

In addition, the peel strength is improved as compared with the conventionally developed build-up insulation material, thereby ensuring a drop reliability equal to or higher than when using a prepreg or an RCC.

In addition, by providing toughness and plasticity to the epoxy resin composition which is an insulating layer, it is possible to secure excellent reliability in a high temperature thermal shock test.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

The present invention provides toughness and plasticity to the cured product by introducing an epoxy resin in which core-shell structured acrylic rubber particles are dispersed in an insulating layer for a printed circuit board composed of various epoxy resins, thereby reducing thermal stress due to curing shrinkage. The present invention provides a flame retardant resin composition capable of improving the reliability of a final printed circuit board by exhibiting a peeling strength of a predetermined level or more and reducing internal thermal stress to exhibit a stable behavior against thermal shock.

In addition, the present invention provides a printed circuit board applied as an outer layer structural material of a multilayer wiring board using an existing substrate manufacturing process using such an epoxy resin composition. In particular, it exhibits excellent peel strength while being flame retardant and at the same time reducing thermal stress due to curing shrinkage of the final insulating material, has excellent thermal shock reliability.

The resin composition for a printed circuit board according to the preferred embodiment of the present invention includes a composite epoxy resin, a curing agent, a curing accelerator, and an inorganic filler.

The composite epoxy resin used in the present invention is an epoxy resin in which acrylic rubber particles of a core-shell structure are dispersed, a digecidyl ether of bisphenol A (DGEBA) -based epoxy resin, a cresol novolac epoxy resin, a rubber-modified epoxy resin, And phosphorus-based epoxy resins.

The structure of the acrylic rubber particles used in the epoxy resin in which the acrylic rubber particles of the core-shell structure is dispersed is schematically shown in FIG. 1.

Referring to FIG. 1, the acrylic rubber particles 10 have a structure in which a shell 12 of an acrylic component surrounds a core 11 of an acrylic rubber component.

The acrylic rubber component of the core 11 is, for example, an acrylic compound having a Tg of about −40 ° C., and a polymer or copolymer of a conjugated diene such as butadiene, or n-butyl-, Polymers or copolymers of low molecular acrylates such as ethyl-, isobutyl- or 2-ethylhexyl acrylate may be selected, but are not particularly limited thereto.

The acrylic component of the shell 12 is, for example, an acrylic compound having a Tg of about 110 ° C., optionally chemically grafted or crosslinked with the rubber core, preferably methyl-, ethyl- or t- It may be polymerized from at least one low molecular weight alkyl methacrylate, such as butyl methacrylate, but is not particularly limited thereto. In addition, homopolymers of the aforementioned methacrylate monomers can be used. Furthermore, up to 40% of the acrylic component of the shell may be formed from other monovinyldiene monomers such as styrene, vinyl acetate, vinyl chloride, methyl acrylate, ethyl acrylate, butyl acrylate and the like, but in particular It is not limited.

The core-shell structured acrylic rubber particles may have, for example, a particle diameter of about 0.5 μm, but are not particularly limited thereto.

The epoxy resin in which the above-described core-shell structured acrylic rubber particles are evenly dispersed has excellent thermal stability, break strength, flexibility strength, tensile strength, modulus of elasticity, and the like. Excellent mechanical properties

The epoxy resin in which the acrylic rubber particles of the core-shell structure are dispersed is used together with a curing agent such as acid anhydride, dicyandiamide (DICY), diaminodiphenylmethane (DDM), polyamide amine, and the like, and further improves physical properties. In addition, by using a mixture of structurally brittle epoxy with a certain ratio, toughness and plasticity can be imparted to the blend system, thereby exhibiting excellent properties at high temperature reliability such as thermal shock test.

During the curing process of the epoxy system in which the acrylic rubber particles of the core-shell structure are dispersed, when the temperature of the shell is increased above the Tg, the shell component swells and gels and the low molecular epoxy prepolymer can easily penetrate into the shell. As such, the core-shell structured rubber particles are not simply dispersed in the epoxy system, but rather form chemical bonds with the epoxy monomolecules in the system during the curing process, thereby achieving a stronger bond than the system in which the rubber particles are dispersed. It can exhibit uniform properties. Chemically bonded core-shell structured acrylic rubber with epoxy matrix lowers the crosslink density of the epoxy matrix in close proximity to the shell, thereby improving toughness in the system. When stress is applied in the system, such as hardening shrinkage, the rubber component of the core interferes in all directions, canceling the generated stress. In addition, even when cracking or tearing occurs due to stress, an elastomer chemically bonded to the epoxy matrix is stretched in the vertical direction of the cracking or tearing, thereby controlling the propagation of the crack.

The epoxy resin in which the acrylic rubber particles of the core-shell structure are dispersed is preferably an average epoxy resin equivalent of 220 to 240. If the equivalent amount of the epoxy resin in which the acrylic rubber particles of the core-shell structure are dispersed is less than 220, it is difficult to impart desired physical properties to the composite epoxy resin structure, and if it exceeds 240, the melting point becomes too high and difficult to control.

In addition, the epoxy resin in which the acrylic rubber particles of the core-shell structure are dispersed may be included in an amount of 1 to 30% by weight of the composite epoxy resin. When the content of the epoxy resin in which the acrylic rubber particles of the core-shell structure is dispersed is less than 1% by weight, it is difficult to secure high-temperature thermal shock reliability. When the content of the epoxy rubber is greater than 30% by weight, the elasticity of the cured product may be increased to reduce dimensional stability and Tg. have.

In the DGEBA type epoxy resin used in the present invention, the epoxy functional group and the secondary alcoholic hydroxyl group present in the resin are reactive, and thus curing reaction by, for example, the epoxy functional group and / or the hydroxyl group may occur. In general, the DGEBA-based epoxy resin is excellent in high temperature characteristics because it is difficult to free-rotate the benzene core of bisphenol-A, and has an ether group in the molecule, which has chemical resistance and plasticity. In addition, since hydrophilic hydroxyl groups and hydrophobic hydrocarbon groups are regularly arranged, adhesiveness is excellent, and electrical properties such as electrical insulation and dielectric constant after curing are excellent. The above-described properties may vary depending on the degree of polymerization.

The DGEBA type epoxy resin preferably has an average epoxy resin equivalent of 200 to 600. If the average epoxy resin equivalent is less than 200, it is difficult to exhibit desired physical properties, and if it is 600 or more, it is not preferable because it is difficult to dissolve in the solvent and the melting point is too high to control.

The DGEBA type epoxy resin may be included in an amount of 1 to 20% by weight of the composite epoxy resin. If the content is less than 1% by weight, desired physical properties cannot be obtained, and if the content is more than 20% by weight, cracks due to brittleness are not preferable.

The cresol novolac epoxy resin used in the present invention can obtain a cured product having many functional groups and excellent heat resistance, chemical resistance, and electrical properties, and improve thermal stability and mechanical strength of the formed substrate. The average epoxy resin equivalent of the cresol novolac epoxy resin is preferably 100 to 300, it may be included in the content of 30 to 70% by weight of the composite epoxy resin. If the average epoxy resin equivalent of the cresol novolac epoxy resin is less than 100, it is difficult to exhibit desired physical properties, and if it exceeds 300, it may be difficult to dissolve in the solvent and the melting point may be too high to control. In addition, when the content of the cresol novolak epoxy resin is less than 30% by weight, it is not possible to obtain inherent heat resistance properties, and when it exceeds 70% by weight, the electrical mechanical properties are lowered, which is not preferable.

The rubber-modified epoxy resin used in the present invention provides toughness to the epoxy cured product to improve impact resistance. The rubber-modified epoxy resin preferably has an average epoxy resin equivalent of 200 to 400. If the rubber-modified epoxy resin equivalent is less than 200, it is difficult to improve brittleness, and if it exceeds 400, the melting point becomes too high and difficult to control, which is not preferable.

In addition, the rubber modified epoxy resin may be included in 1 to 20% by weight of the composite epoxy resin. If the content of the rubber-modified epoxy resin is less than 1% by weight, it is difficult to expect improvement in toughness, and when the content of the rubber-modified epoxy resin is more than 20% by weight, the elasticity of the cured product may be increased to lower dimensional stability.

Phosphorus-based epoxy resin used in the present invention is excellent in flame retardancy and self-extinguishing. In the present invention, in order to impart flame retardancy to a printed circuit board, a phosphorous epoxy resin is added, and halogen-free eco-friendly flame retardant substrates can be obtained. It is preferable that the said phosphorus epoxy resin is 400-800 in average epoxy resin equivalent weight. If the phosphorus-based epoxy resin equivalent is less than 400, it is difficult to impart flame retardant properties to the composite epoxy resin, and if it exceeds 800, it is not preferable because it is difficult to dissolve in the solvent and the melting point is too high to control.

In addition, the phosphorous epoxy resin may be included in an amount of 10 to 30% by weight of the composite epoxy resin. If the content of the phosphorus-based epoxy resin is less than 10% by weight, it is difficult to impart desired flame retardancy, and if it exceeds 30% by weight, the electrical mechanical properties are lowered, which is not preferable.

The composite epoxy resin can be dissolved in a mixed solvent such as 2-methoxy ethanol, methyl ethyl ketone (MEK), dimethyl formamide (DMF), or the like.

The curing agent used in the present invention may be one or more compounds selected from the group consisting of phenol novolak type, bisphenol novolak type and mixtures thereof, and may improve the adhesive strength of the final cured product. According to a preferred embodiment, it can be mixed in a ratio of 0.5 to 1.5 equivalents relative to the mixing equivalent of the epoxy groups of the composite epoxy resin. The curing agent has a softening point of 100 to 140 ℃, most preferably from the viewpoint of the desired physical properties of the equivalent of hydroxyl groups of 100 to 150. In addition, the curing agent is preferably a ratio of 1: 0.2 to 1: 1.3 of the epoxy group of the composite epoxy resin and the phenolic hydroxyl group of the curing agent in terms of the desired physical properties and reactivity.

The curing accelerator used in the present invention may be an imidazole compound, more preferably 2-ethyl-4-methyl imidazole, 1- (2-cyanoethyl) -2-alkyl imidazole, 2- One or more imidazole compounds selected from the group consisting of phenyl imidazole and mixtures thereof. The curing accelerator is preferably mixed in an amount of 0.1 to 1 parts by weight based on 100 parts by weight of the composite epoxy resin. When the content of the curing accelerator is less than 0.1 parts by weight, the curing rate is significantly lowered and the curing reaction is not completely completed, so that uncuring may occur, and if it exceeds 1 part by weight, a problem may occur that rapid curing occurs.

Inorganic fillers used in the present invention are added to reinforce poor physical properties such as mechanical strength and adhesive properties of the cured composite epoxy resin, and include, for example, graphite, carbon black, silica, CaCO ₃ and clay. One or more may be selected from the group. Preferably, the inorganic filler may be treated with a silane coupling agent to improve dispersing characteristics, and the irregular filler may have irregular shape and size, thereby forming surface roughness by desorption of filler during roughening plating and mechanical anchoring effect with the wiring layer. It is preferable to show high peel strength because it is advantageous for increasing The amount of the inorganic filler is preferably 10 to 30 parts by weight with respect to 100 parts by weight of the composite epoxy resin, when less than 10 parts by weight it is difficult to expect the desired mechanical properties, if exceeding 30 parts by weight can reduce the peel strength It is not desirable because there is.

In addition, by adding an additional flame retardant aid, it is possible to lower the content of the relatively high phosphorus flame-retardant epoxy resin price. As the flame retardant aid, a compound such as Al ₂ O ₃ containing phosphorus may be used, but is not particularly limited thereto.

When the substrate is manufactured using the resin composition of the present invention as described above, it exhibits excellent reliability characteristics, for example, defects such as delamination or cracking in tests such as HAST (Highly Accelerated Stress Test) and high temperature thermal shock. You can prevent it.

In addition, since it has flame retardancy, it has excellent peel strength, excellent mechanical strength and the like, and excellent thermal shock reliability by reducing thermal stress caused by curing shrinkage of the final insulating material. The peel strength, which was realized by conventional crimping method while changing from the prepreg type to the build-up type, should be implemented after the desmear and plating process using the build-up method, which is very suitable for application as an interlayer insulation layer for such build-up. Do.

Hereinafter, the present invention will be described in more detail with reference to the following examples and comparative examples, but the scope of the present invention is not limited thereto.

≪ Example 1 >

1) A mixed solvent of 316.54 g of MEK (Methlyl Ethyl Ketone) and 1059.73 g of 2-methoxy ethanol are added to the resin compositions of 1 to 5 shown in Example 1 of Table 1, followed by stirring at 300 rpm at room temperature.

2) 1035.25 g of an irregularly shaped inorganic filler ⑦ having a size distribution of 2.5 to 3 μm is added to the mixture of 1), followed by stirring at 400 rpm for 3 hours.

3) Finally, the curing agent of ⑥ and the curing accelerator of ⑧ was added to the mixture of 2) and stirred for about 30 minutes to prepare the final epoxy composition.

4) The above epoxy composition is cast in a PET film to prepare a roll.

5) The above film is cut into 405 × 510 mm and lamination is performed at 80 ° C., followed by a series of drying and precure steps using a convection oven.

6) Then, after the vertical desmear and chemical copper roughening step for forming roughness on the surface of the film, electroplating and postcuring with a thickness of 25 μm are performed to form an insulating layer of the printed circuit board.

7) Physical properties such as measurement of peel strength and thermal properties between the insulating layer and the plating layer of the insulating material composition prepared as described above are shown in Table 2 below.

Comparative Example 1

1) A mixed solvent of 316.54 g of MEK (Methyl Ethyl Ketone) and 623.88 g of 2-methoxy ethanol are added to the resin compositions of ② to ⑤ shown in Comparative Example 1 of Table 1, followed by stirring at 300 rpm at room temperature.

2) 588.45 g of inorganic filler ⑦ of irregular shape having a size distribution of 2.5 to 3 μm is added to the mixture of 1), and then stirred at 400 rpm for 3 hours.

3) Finally, the curing agent of ⑥ and the curing accelerator of ⑧ was added to the mixture of 2) and stirred for about 30 minutes to prepare the final epoxy composition.

4) The subsequent steps are the same as in <Example 1> above.

As shown in Table 2, the insulating resin of the present invention has a Tg, peel strength, or the like as compared to Comparative Example 1, in which the acrylic rubber particles of the core-shell structure are not dispersed, and has a value equal to or greater than 260 ° C. High-temperature reliability has been significantly improved, with a 20-second dipping test on the solder, yielding more than 100% in two tests and 91% in three tests. This is because the core-shell structured acrylic rubber evenly dispersed in the epoxy resin is chemically and firmly bonded to the epoxy matrix to reduce the crosslinking density of the adjacent epoxy cured product, and the rubber particles cause interference in all directions, so that curing shrinkage and high temperature thermal shock etc. It is considered that this is because the internal thermal stress generated by this can be canceled, and a stable behavior can be exhibited by preventing defects such as delamination and cracks.

Although the present invention has been described in detail through specific embodiments, it is for explaining the present invention in detail, and the resin composition for a printed circuit board and the printed circuit board using the same according to the present invention are not limited thereto. It is apparent that modifications and improvements are possible by those skilled in the art within the scope of the idea.

All simple modifications and variations of the present invention fall within the scope of the present invention, and the specific scope of protection of the present invention will be apparent from the appended claims.

1 is a view schematically showing the structure of acrylic rubber particles of a core-shell structure dispersed in an epoxy resin according to a preferred embodiment of the present invention.

Claims (13)

Epoxy resin in which core-shell structured acrylic rubber particles are dispersed, digecidyl ether of bisphenol A (DGEBA) epoxy resin, cresol novolac epoxy resin, rubber modified epoxy resin, phosphorus epoxy resin Composite epoxy resin containing; Curing agent; Curing accelerators; And Resin composition for a printed circuit board comprising an inorganic filler. The method according to claim 1, The acrylic rubber particles have a core-shell structure in which a shell of an acrylic component surrounds a core of an acrylic rubber component. The method according to claim 1, The composite epoxy resin is 1 to 30% by weight of the epoxy resin in which the acrylic rubber particles of the core-shell structure is dispersed, 1 to 20% by weight of DGEBA-based epoxy resin, 30 to 70% by weight of cresol novolac epoxy resin, rubber modified epoxy resin 1 to 20% by weight, and a resin composition for a printed circuit board comprising 10 to 30% by weight of the phosphorus-based epoxy resin. The method according to claim 1, Average of the (i) core-shell structured acrylic rubber particle dispersion epoxy resin, (ii) DGEBA epoxy resin, (iii) cresol novolac epoxy resin, (iv) rubber modified epoxy resin and (v) phosphorus epoxy resin Epoxy resin equivalents are (i) 220 to 240, (ii) 200 to 600, (iii) 100 to 300, (iv) 200 to 400 and (v) 400 to 800, respectively. . The method according to claim 1, The curing agent is a resin composition for a printed circuit board, characterized in that the phenol novolak-type curing agent, bisphenol novolak-type curing agent or a mixture thereof. The method according to claim 1, The curing agent is a resin composition for a printed circuit board, characterized in that contained in 0.5 to 1.5 equivalents relative to the total mixed equivalent of the epoxy groups of the composite epoxy resin. The method according to claim 1, The curing agent has a softening point of 100 to 140 ℃, hydroxyl group equivalent resin composition for a printed circuit board, characterized in that 100 to 150. The method according to claim 1, The curing agent is a resin composition for a printed circuit board, characterized in that the ratio of the epoxy group of the composite epoxy resin and the phenolic hydroxyl group of the curing agent is 1: 0.2 to 1: 1.3. The method according to claim 1, The curing accelerator is a resin composition for a printed circuit board, characterized in that the imidazole compound. The method according to claim 9, The curing accelerator is at least one compound selected from the group consisting of 2-ethyl-4-methyl imidazole, 1- (2-cyanoethyl) -2-alkyl imidazole, 2-phenyl imidazole and mixtures thereof. Resin composition for a printed circuit board characterized in that. The method according to claim 1, A resin composition for a printed circuit board comprising 0.1 to 1 part by weight of a curing accelerator and 10 to 30 parts by weight of an inorganic filler based on 100 parts by weight of the composite epoxy resin. The method according to claim 1, The inorganic filler is a resin composition for a printed circuit board, characterized in that the surface treatment with a silane coupling agent. Printed circuit board manufactured using the resin composition according to claim 1.

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