Curable compositions and insulating films

Abstract

The present invention provides a curable composition and an insulating film. [Solution] This disclosure provides a curable composition comprising (a) an epoxy resin, (b) a curing agent, (c) a curing catalyst, (d) boron nitride as a filler, and (e) an optional additive. This disclosure also provides an insulating film comprising the aforementioned curable composition, which is particularly suitable for manufacturing printed circuit boards (PCBs). The insulating film exhibits excellent electrical properties, including a low dielectric loss tangent (Df) and a low coefficient of thermal expansion (CTE). Furthermore, the insulating film offers significant advantages in reducing production time in PCB manufacturing processes involving plasma etching steps.

Description

Technical Field

[0001] The present disclosure generally relates to a curable composition containing boron nitride, and more particularly to an insulating film and / or a printed circuit board containing the same.

Background Art

[0002] Due to current trends towards thinner and lighter electronic products, printed circuit boards (PCBs) need to have a higher wiring density. A PCB typically consists of a plurality of insulating layers and conductive layers laminated on top of each other. To achieve a high wiring density, through-holes or blind holes are provided to connect circuits between different conductive layers.

[0003] Conventional via fabrication techniques use a laser beam as a drilling tool. The friction generated during drilling creates resin smears on the channel walls. In order to enable optimal connections, it is necessary to remove this smear. Usually, a wet process is used after laser drilling to remove the smear and form a suitable through-hole. This wet process includes surface cleaning, swelling of the smear, permanganate desmear, and neutralization reactions. However, the waste liquid and waste water discharged in each process may carry a large amount of harmful substances, deteriorate the environment, and harm people's physical and mental health.

[0004] Compared to subtractive or (modified) semi-additive processes in PCB manufacturing, pattern and / or via formation by plasma etching is considered a more environmentally friendly process because it does not involve a wet process. However, the etching rate of plasma etching is typically too slow to be cost-effective for manufacturing PCBs. For example, (Patent Document 1) discloses the use of plasma etching to manufacture a multilayer circuit structure having an embedded circuit layer, but the materials tested in this prior art demonstrated an etching rate of less than 1.0 μm / min.

Prior Art Documents

[0005] [Patent Document 1] U.S. Patent Application Publication No. 2022 / 0201853 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] From the above perspective, there is a need to develop new materials for PCB insulating layers, and the ability to process them using plasma etching processes will bring overall benefits to the printed circuit board industry. [Means for solving the problem]

[0007] To address the aforementioned problems, this disclosure provides a novel composition for an insulating layer of a PCB. A PCB composed of this material has a higher plasma etching rate without sacrificing its electrical and mechanical properties, such as dielectric loss tangent (DF) and coefficient of thermal expansion (CTE). The novel composition is a viable alternative to conventional PCB insulating layers.

[0008] According to one aspect of this disclosure, a curable composition is provided. The curable composition, 100 parts by weight of epoxy resin having an average epoxy equivalent weight of 500 g / equivalent or less, 35 to 300 parts by weight of hardener, 0.025 to 20 parts by weight of curing catalyst, A filler comprising 50 to 420 parts by weight, containing boron nitride, having a median particle size of 8 μm or less, and a maximum particle size of 20 μm or more. Includes.

[0009] According to a second aspect of the present disclosure, an insulating film comprising the curable composition described above is also provided. The insulating film comprises, in order, a support film, a resin layer composed of the curable composition described above, and a protective film. The resin layer has a thickness of 10 μm to 60 μm.

[0010] A printed circuit board is also provided according to a third aspect of the present disclosure. The PCB is a cured product of the curable composition described above, or comprises an insulating layer made from the insulating film described above. [Brief explanation of the drawing]

[0011] [Figure 1] A cross-sectional view of a test coupon according to one embodiment of the present disclosure is shown. [Modes for carrying out the invention]

[0012] Before we delve into the details of the embodiments described below, some terms will be defined or clarified.

[0013] definition All publications, patent applications, patents, and other references mentioned herein are expressly incorporated herein by reference in their entirety for all purposes, as if they were fully specified unless otherwise noted.

[0014] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in which this invention pertains. In case of any conflict, this specification, including its definitions, shall prevail.

[0015] Unless otherwise specified, all percentages, parts, ratios, etc., are based on weight.

[0016] As used herein, the term “produced from” is synonymous with “contains.” As used herein, the terms “contains,” “includes,” “encompasses,” “incorporates,” “has,” “has,” “contains,” or “contains,” or any other variation thereof, are intended to encompass non-exclusive inclusion. For example, a composition, process, method, article, or apparatus containing a list of elements may not necessarily be limited to those elements alone, and may include other elements that are not explicitly listed or that are inherent to such composition, process, method, article, or apparatus.

[0017] The transitional phrase "consisting of" excludes any element, step or ingredient not expressly recited. In the case of a claim, such a phrase will limit the claim to exclude materials other than those recited, except for impurities ordinarily associated with them. When the phrase "consisting of" appears not immediately following the preamble but rather in the body clause of the claim, it limits only the elements recited in that clause and other elements are not excluded from the claim as a whole.

[0018] The transitional phrase "consisting essentially of" is used to define a composition, method or apparatus that includes materials, steps, features, components or elements, but only provided that these additional materials, steps, features, components or elements do not substantially affect the basic and novel characteristics of the claimed disclosure.

[0019] The term "consisting essentially of" occupies an intermediate area between "comprising" and "consisting of".

[0020] The term "comprising" is intended to include embodiments subsumed by the terms "consisting essentially of" and "consisting of". Similarly, the term "consisting essentially of" is intended to include embodiments subsumed by the term "consisting of".

[0021] The epoxy equivalent weight (EEW) is the weight (g / equivalent) of an uncured resin containing the equivalents per mole of epoxy groups. The EEW depends on the molecular weight and is useful in determining the hardener concentration.

[0022] When a quantity, concentration or other value or parameter is shown as either a range, a preferred range or a list of upper and lower preferred values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper limit range or preferred value and any lower limit range or preferred value, whether or not the ranges are disclosed individually. For example, when the range "1 to 5" is recited, the recited range should be construed as including the ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is recited herein, unless otherwise specified, the range is intended to include its endpoints, as well as all integers and fractions within that range.

[0023] Further, unless expressly stated to the contrary, "or" refers to an inclusive "or" and not an exclusive "or". For example, the condition A "or" B is satisfied by either A being true (or present) and B being false (or absent), A being false (or absent) and B being true (or present), or both A and B being true (or present).

[0024] The present disclosure is described in detail below herein.

[0025] The present disclosure is a curable composition comprising 100 parts by weight of an epoxy resin having an average epoxy equivalent weight of 500 g / equivalent or less, 35 to 300 parts by weight of a curing agent, 0.025 to 20 parts by weight of a curing catalyst, 50 to 420 parts by weight of a filler, which contains boron nitride, has a median particle size of 8 μm or less, and has a maximum particle size of 20 μm at most and relates to a curable composition.

[0026] In one embodiment of the present disclosure, the curable composition further comprises 70 parts by weight or less of an additive per 100 parts by weight of epoxy resin. In another embodiment of the present disclosure, the curable composition further comprises 25 to 70 parts by weight of an additive per 100 parts by weight of epoxy resin.

[0027] Non-limiting examples of epoxy resins include bisphenol A type epoxy, bisphenol F type epoxy, glycidylamine type epoxy, biphenyl type epoxy, naphthalene type epoxy, anthracene type epoxy, fluorene type epoxy, biphenylaralkylphenol type epoxy, dicyclopentadiene type epoxy, trihydroxyphenylmethane type epoxy, naphthol aralkyl type epoxy, phenol aralkyl type epoxy, phenol novolac type epoxy, cresol novolac type epoxy, bisphenol novolac type epoxy, naphthol-cresol novolac type epoxy, naphthalenediol novolac type epoxy, and hydrogenated or halogen-modified epoxy. However, in one embodiment of the present disclosure, the epoxy resin is selected from the group consisting of the above epoxy resins and mixtures thereof.

[0028] Non-limiting examples of curing agents include active ester-type curing agents, carbodiimide-type curing agents, phenol-type curing agents, naphthol-type curing agents, or acid-type curing agents. However, in one embodiment of the present disclosure, the curing agent is selected from the group consisting of the above curing agents and mixtures thereof.

[0029] In one embodiment of the present disclosure, the curing agent does not include a cyanate resin. In one embodiment of the present disclosure, the curing agent includes an activated ester-type curing agent.

[0030] In one embodiment of the present disclosure, the curable composition comprises 40 to 200 parts by weight of curing agent per 100 parts by weight of epoxy resin. In another embodiment of the present disclosure, the curable composition comprises 40 to 100 parts by weight of curing agent per 100 parts by weight of epoxy resin.

[0031] Non-limiting examples of curing catalysts include alkylamine-type catalysts, pyridine-type catalysts, imidazole-type catalysts, or piperidine-type catalysts. However, in one embodiment of the present disclosure, the curing catalyst is selected from the group consisting of the above curing catalysts and mixtures thereof.

[0032] Non-limiting examples of additives include antioxidants, flame retardants, colorants, thickeners, defoamers, elastomers, surface modifiers, polymerization inhibitors, UV absorbers, solvents, silane coupling agents, adhesion promoters, or antioxidants. However, in one embodiment of the present disclosure, the additive is selected from the group consisting of the above additives and mixtures thereof.

[0033] In one embodiment of the present disclosure, the amount of the additive is 70 parts by weight or less.

[0034] In one embodiment of the present disclosure, the additive is at least one solvent selected from the group consisting of methyl ethyl ketone, toluene, cyclohexanone, cyclopentanone, isophorone, methyl isobutyl ketone, and mixtures thereof.

[0035] In one embodiment of the present disclosure, the curable composition comprises 50 to 350 parts by weight of filler per 100 parts by weight of epoxy resin. In another embodiment of the present disclosure, the curable composition comprises 100 to 300 parts by weight of filler per 100 parts by weight of epoxy resin. In yet another embodiment of the present disclosure, the curable composition comprises 160 to 300 parts by weight of filler per 100 parts by weight of epoxy resin.

[0036] A second aspect of the present disclosure relates to an insulating film for fabricating printed circuit boards, which is particularly suitable for application of plasma etching. The insulating film is Support membrane and, A resin layer composed of the above-mentioned curable composition, protective film and It includes them in order.

[0037] In one embodiment of the present disclosure, the resin layer has a thickness of 10 μm to 60 μm. In another embodiment of the present disclosure, the support film is a thermoplastic film having a thickness of 10 μm to 50 μm or a metal foil having a thickness of 1 μm to 25 μm. In yet another embodiment of the present disclosure, the protective film is a thermoplastic film having a thickness of 10 μm to 50 μm.

[0038] In one embodiment of the present disclosure, the support film and the protective film are each independently composed of a polymer material selected from the group consisting of polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, and polyimide.

[0039] In one embodiment of the present disclosure, the support film is a metal foil selected from the group consisting of Au, Ag, Cu, Al and its alloys.

[0040] In one embodiment of the present disclosure, the resin layer is cured at 100°C to 250°C for 60 to 240 minutes.

[0041] In one embodiment of the present disclosure, the cured resin layer has a dielectric loss tangent (Df) of 0.006 or less when measured at 10 GHz and 23°C.

[0042] In one embodiment of the present disclosure, the cured resin layer has a coefficient of thermal expansion (CTE) of 40 ppm / K or less at 30°C to 120°C.

[0043] In one embodiment of the present disclosure, the cured resin layer has a plasma etching rate of 1 μm / min or more, and the plasma etching is performed under a chamber pressure of 2 Pa (15 milliliters) by applying a radio frequency (RF) power of 13.56 MHz, an ignition power of 8000 watts, and a DC bias setting of 3000 watts over a period of 15 minutes using a gas mixture of oxygen, tetrafluoromethane (carbon tetrafluoride, CF4), and nitrogen in a ratio of 10:10:1, and a flow rate of 1050 mL / second.

[0044] A third aspect of this disclosure relates to a printed circuit board comprising a cured product of the above-mentioned curable composition or an insulating layer made from the above-mentioned insulating film.

[0045] In one embodiment of the present disclosure, the printed circuit board includes circuits fabricated by a method comprising a plasma etching step for via and / or trench formation.

[0046] In one embodiment of the present disclosure, the method for forming the circuit is a semi-additive process (SAP) or a modified semi-additive process (mSAP).

[0047] Composition and film preparation The curable compositions of this disclosure comprise the following components: (a) an epoxy resin, (b) a curing agent, (c) a curing catalyst, (d) boron nitride as a filler, and (e) an optional additive. In one non-limiting embodiment, embodiments of the compositions of this disclosure may be prepared from the components listed in Table A below. First, the epoxy resin, boron nitride filler, and solvent were mixed and dissolved, and then the other components, including the curing agent, catalyst, and optional additive, were added until they were sufficiently dissolved to obtain a varnish. The compositions were prepared into two different samples: a resin-coated copper (RCC) film structure and a resin sheet structure for further testing.

[0048] [Table 1] [Examples]

[0049] Example 1 47 grams of PCTP05 (boron nitride filler from Saint-Gobain) was mixed with 35 grams of MEK (methyl ethyl ketone), 15 grams of toluene, and 23.6 grams of YL7890 (biphenyl epoxy from Mitsubishi Chemical). The mixture was stirred for 20 minutes until the YL7890 epoxy was completely dissolved. Then, 1 gram of GPH65 (phenol-type curing agent from Nippon Kayaku), 19.7 grams of HPC-8150 (active ester curing agent from DIC, 62% in solution), 0.36 grams of 1B2PZ (catalyst from Shikoku Chemicals), and 4.1 grams of LA-1356 (triazine phenol curing agent from DIC, 60% in MEK solution) were added. The mixture was stirred again until all components were thoroughly dissolved.

[0050] The final ingredient, 14.5 grams of V03 (Nisshinbo carbodiimide, 50% in toluene), was added to the mixture and stirred for another 30 minutes to obtain a resin varnish. Adding this curing agent separately prevents solvent compatibility issues. In other cases, all ingredients can be mixed at once.

[0051] The obtained resin varnish was coated onto a support film MT18FL-3μm (a two-layer copper foil with an upper layer of 3μm thickness and a lower layer of 18μm thickness) at a coating speed of approximately 60 mm / s using a suitable quadruple-layer applicator (GMA Machinery, Taiwan) on an automated coating machine (Model Coatmaster 510, purchased from Erichsen GmbH). The coated film was then dried at 100°C for 3 minutes in a circulating oven (Model DCM704, purchased from Channel Instruments, Taiwan). After drying, the film was covered with 38X (protective film) to form a resin-coated copper (RCC) film structure sample.

[0052] In addition, the mixed varnish was coated onto 38X (protective film) and dried at 100°C for 3 minutes. Then, the dried film was covered with MA411 (protective film) to form a resin sheet structure.

[0053] The thickness of the composition layer was 30 μm for the two structures described above.

[0054] Example 2 The composition of Example 1, wherein the filler is replaced with PT180 (BN, with a median particle size of 7 μm), and the quantity is the same (47 g).

[0055] Comparative Example 1 The composition of Example 1, wherein the filler is replaced with SG-SO0700 (silica), but the amount is the same (47g).

[0056] Comparative Example 2 The composition of Example 1, wherein the filler is replaced with SFP130MC (silica), but the amount is the same (47g).

[0057] Example 3 The composition of Example 1, wherein the filler is replaced with 70 g of PT180(BN) and the epoxy is replaced with 23.6 g of ESN-475V (α-naphthol aralkyl epoxy resin manufactured by Nippon Steel Chemical Co., Ltd.).

[0058] Example 4 The composition of Example 3, in which the filler is adjusted to 47 g of PT180(BN).

[0059] Example 5 The composition of Example 3, in which the filler is adjusted to 25 g of PT180(BN).

[0060] Comparative Example 3 The composition of Example 3, in which the filler is replaced with SFP130MC (silica) in an amount of 87g.

[0061] Comparative Example 4 The composition of Example 3, wherein the filler is replaced with SFP130MC (silica) in an amount of 47 g.

[0062] Comparative Example 5 The composition of Example 3, wherein the filler is replaced with SFP130MC (silica) in an amount of 25 g.

[0063] Table B lists the actual solid content of the components in the above examples and comparative examples. The abbreviation "E" represents "Examples," and "CE" represents "Comparative Examples." The examples and comparative examples were prepared using similar methods. The difference between the examples and comparative examples lies in the filler. Examples 1-5 use boron nitride as the filler, while comparative examples 1-5 use silica as the filler.

[0064] [Table 2]

[0065] Measurement of plasma etching rate of RCC film Test coupon preparation The RCC films of the above examples and comparative examples were further processed as follows to prepare coupons for plasma etching tests: Lamination: A 15cm x 20cm RCC film was laminated using a vacuum laminator onto an EM526 H / H core board (15cm x 20cm, 0.6mm thick) pre-treated with CZ-8100 (a pre-treatment solution prepared by MEC). The vacuum laminator was heated to 100°C, vacuumed for 30 seconds, and then laminated at 100°C for 90 seconds at 7kgf / cm². 2 It was pressurized. Curing: The layered samples were cured in an air-flow oven at 130°C for 30 minutes, 180°C for 30 minutes, and then at 200°C for 90 minutes. Copper removal: After hardening, the support layer MT18FL (carrier copper of the RCC film) was removed. Tenting: A hard mask window (40 μm / 40 μm line / space pattern) was formed on the surface of the cured sample (without carrier). The sample was then cut into 5 cm x 5 cm pieces to serve as test coupons.

[0066] The structure of the test coupon is shown in Figure 1. The test coupon comprises a core layer EM526 (11) and its coating copper (12), a dielectric layer 20 (curable composition of the present disclosure), and a metal hard mask 30. The following plasma treatment etches the dielectric layer 20 through a window in the hard mask 30.

[0067] Plasma etching and measurement Coupons from the examples and comparative examples were subjected to plasma treatment, and the etching depth was measured using a 3D optical microscope (Olympus Lext OLS5100, 50× objective lens). The etching depth was calculated by subtracting the thickness of the hard mask from the depth from the surface. The etching rate was calculated by dividing the etching depth by the treatment time. The test results for each coupon are listed in Table C.

[0068] [Table 3]

[0069] As shown in Table C, the plasma etching rates of Examples 1-5 of this disclosure are higher than 0.9 μm / min. Plasma etching rates can reach more than 1 μm / min. Plasma etching rates can further reach more than 1.3 μm / min. In contrast, Comparative Examples 1-5 have relatively low plasma etching rates and may not be suitable for industrial applications.

[0070] Measurement of Df and CTE of resin sheets Sample preparation The resin sheets of the examples and comparative examples were further processed as follows to prepare samples for measuring DF and CTE: Lamination: Multiple resin sheets measuring 10cm x 10cm were laminated together, and a single dielectric layer with a thickness of 60μm was formed using a vacuum laminator. The vacuum laminator was heated to 100°C, vacuumed for 30 seconds, and then laminated at 100°C for 90 seconds at 7kgf / cm². 2 It was pressurized. Curing: The layered samples were cured in an air-flow oven at 130°C for 30 minutes, 180°C for 30 minutes, and then at 200°C for 90 minutes. PET film removal: After curing, the protective layer 38X (PET film) was removed.

[0071] The dielectric loss tangent (Df) of the dielectric / insulating layer was measured by the resonant cavity method at a frequency of 10 GHz. The coefficient of thermal expansion (CTE) was measured using a TA Instruments TMA 650 thermomechanical analyzer. Samples were heated to 280°C, cooled to room temperature, and then reheated at a rate of 5°C / min with a preload of 0.098 N. The CTE was calculated from the gradient of dimensional change with respect to temperature from 50°C to 100°C during the second heating cycle. The test results for each sample are listed in Table D.

[0072] [Table 4]

[0073] The curable compositions of this disclosure are particularly suitable for manufacturing printed circuit boards (PCBs).

[0074] As shown in Table D, when the filler is replaced from conventionally used silica to BN, the dielectric loss tangent (Df) and coefficient of thermal expansion (CTE) of Examples 1-5 are equivalent to those of Comparative Examples 1-5. In some examples, the dielectric loss tangent (Df) and coefficient of thermal expansion (CTE) are superior to those of the Comparative Examples. For example, the coefficient of thermal expansion can be as low as 13 ppm / °C. Insulating films having this curable composition exhibit excellent electrical properties, including low dielectric loss tangent (Df) and low coefficient of thermal expansion (CTE). Furthermore, the insulating films offer significant advantages in reducing production time in PCB manufacturing processes involving plasma etching steps.

[0075] Fabrication of PCBs using curable compositions Step 1: Preparation of a substrate with an existing electrical circuit. A PCB board with an existing electrical circuit was fabricated using EM526 (a core board supplied by Elite Electronic Material Co. Ltd., with a thickness of 64 μm and a copper thickness of 22 μm).

[0076] Step 2: Laminating RCC coupons onto the substrate The RCC coupons from Example 1 were laminated onto a substrate using a laminator (Vigor, VLPH-150 ton vacuum laminator). After lamination, the lower layer of the support film was removed, and the structure from top to bottom consisted of copper, resin, and substrate.

[0077] Step 3: Metal patterning to form a hard mask A photoresist layer was formed by laminating a dry film (Riston® DI61, 15 μm thick, manufactured by DuPont Electronics, Inc.) onto the copper layer of the substrate from step 2 using a roll laminator at 100°C, a pressure of 1.4 MPa, and a rolling speed of 1.0 m / min.

[0078] A photoresist pattern was formed using a direct exposure patterning machine (FDi3, ORC) with the desired pattern. Uncured portions of the photoresist layer were peeled and removed by treating with a 2% Na2CO3 solution for 3 minutes, then rinsed with DI water and dried.

[0079] The unmasked copper areas were etched in a conventional horizontal line at a rate of 1 m / min using a sodium persulfate (Na2S2O8) solution (130 g / L) until completion, followed by rinsing with DI water and drying. The photoresist pattern was then stripped and removed by treatment with a 10% NaOH solution for 90 seconds, followed by rinsing and drying to form a copper hard mask on the substrate.

[0080] Step 4: Plasma etching of the dielectric layer The exposed dielectric layer was removed by plasma etching using a reactive ion etching plasma system (Linco Tech). The process gas was a mixture of CF4 (500 ml / sec), O2 (500 ml / sec), and N2 (50 ml / sec) for 20 minutes with an ignition power of 8 kW and a DC bias of 3 kW to expose a portion of the underlying conductor.

[0081] Step 5: Formation of the seed layer A seed layer was formed by sputtering copper using a PVD coating machine (UVAT Technology Co., model: UHSD-060302T) with a standard concentration of 4N copper. The resulting copper layer had a thickness of 0.8 μm.

[0082] Step 6: Addition of photoresist pattern layer A photoresist layer was formed on a copper layer by laminating a dry film (Riston® DI61, 25 μm thick, manufactured by DuPont Electronics, Inc.) using a roll laminator at 100°C, a pressure of 1.4 MPa, and a rolling speed of 1.0 m / min.

[0083] Photoresist patterns were generated using a direct exposure patterning machine (ORC FDi3) with conventional test patterns from PCB manufacturers, including line / space sets at 15 μm / 15 μm. Uncured portions of the photoresist layer were peeled and removed by treating with a 2% Na2CO3 solution for 3 minutes, rinsed with DI water, and dried.

[0084] Step 7: Filling trenches and vias by metal deposition The trenches and vias were filled with copper by electroplating. The coupons were plated to a copper thickness of 22 μm using a plating solution (DuPont SFP2M) for 40 minutes at 23.13 ASF (amplitude per square foot).

[0085] Step 8: Removal of photoresist The photoresist pattern was removed by treatment with a 10% NaOH solution for 90 seconds.

[0086] Step 9: Removal of the hard mask layer Flash etching to remove the hard mask layer Immerse the coupon in a 5% by volume sulfuric acid solution for 20 seconds. Transfer the coupon to the etchant solution (ST121-M from Chemtronic Technology) for 48 seconds. Rinse with DI water to remove any remaining solution. It was done by [the person / organization].

[0087] After the flash etching process, a new circuit layer containing vias and conductor wires was completed.

[0088] It will be apparent to those skilled in the art that various modifications and variations of the disclosed embodiments are possible. This specification and the examples are illustrative only, and the true scope of this disclosure is intended to be indicated by the following claims and their equivalents. [Explanation of Symbols]

[0089] 11 Core Layers 12 Coated copper 20 Dielectric layer 30 Metal Hard Masks

Claims

1. A curable composition, 100 parts by weight of epoxy resin having an average epoxy equivalent weight of 500 g / equivalent or less, 35 to 300 parts by weight of hardener, 0.025 to 20 parts by weight of a curing catalyst, A filler comprising 50 to 420 parts by weight, containing boron nitride, having a median particle size of 8 μm or less, and a maximum particle size of 20 μm. A curable composition containing the following:

2. The curable composition according to claim 1, wherein the curing agent does not contain a cyanate resin.

3. The curable composition according to claim 1, wherein the epoxy resin includes bisphenol A type epoxy, bisphenol F type epoxy, glycidylamine type epoxy, biphenyl type epoxy, naphthalene type epoxy, anthracene type epoxy, fluorene type epoxy, biphenylaralkylphenol type epoxy, dicyclopentadiene type epoxy, trihydroxyphenylmethane type epoxy, naphthol aralkyl type epoxy, phenol aralkyl type epoxy, phenol novolac type epoxy, cresol novolac type epoxy, bisphenol novolac type epoxy, naphthol-cresol novolac type epoxy, naphthalenediol novolac type epoxy, hydrogenated or halogen-modified epoxy, or mixtures thereof.

4. The curable composition according to claim 1, wherein the curing agent comprises an active ester-type curing agent, a carbodiimide-type curing agent, a phenol-type curing agent, a naphthol-type curing agent, an acid-type curing agent, or a mixture thereof.

5. The curable composition according to claim 1, wherein the curing catalyst comprises an alkylamine type catalyst, a pyridine type catalyst, an imidazole type catalyst, a piperidine type catalyst, or a mixture thereof.

6. The curable composition according to claim 1, further comprising 70 parts by weight or less of an additive, wherein the additive comprises an antioxidant, flame retardant, colorant, thickener, defoamer, elastomer, surface modifier, polymerization inhibitor, ultraviolet absorber, solvent, silane coupling agent, adhesion promoter, antioxidant, or a mixture thereof.

7. The curable composition according to claim 6, wherein the additive is at least one solvent selected from the group consisting of methyl ethyl ketone, toluene, cyclohexanone, cyclopentanone, isophorone, and methyl isobutyl ketone, and mixtures thereof.

8. An insulating film suitable for application of plasma etching, comprising a resin layer composed of the curable composition described in claim 1, wherein the resin layer has a thickness of 10 μm to 60 μm.

9. The insulating film according to claim 8, further comprising a support film and a protective film, wherein the resin layer is disposed between the support film and the protective film.

10. The insulating film according to claim 9, wherein the support film and the protective film are each independently composed of a polymer material selected from the group consisting of polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, and polyimide.

11. The insulating film according to claim 9, wherein the support film is a metal foil selected from the group consisting of Au, Ag, Cu, Al and their alloys.

12. The insulating film according to claim 8, wherein the cured resin layer has a dielectric loss tangent (Df) of 0.006 or less when measured at 10 GHz and 23°C, and the curing is performed at 100°C to 250°C for 60 to 240 minutes.

13. The insulating film according to claim 8, wherein the cured resin layer has a coefficient of thermal expansion (CTE) of 40 ppm / K or less at 30°C to 120°C, and the curing is performed at 100°C to 250°C for 60 to 240 minutes.

14. The insulating film according to claim 8, wherein the cured resin layer has a plasma etching rate of 1 μm / min or more, and the plasma etching is carried out under a chamber pressure of 2 Pa by applying a radio frequency (RF) power of 13.56 MHz, an ignition power of 8000 watts, and a DC bias of 3000 watts for 15 minutes using a gas mixture of oxygen, tetrafluoromethane, and nitrogen in a ratio of 10:10:1 and a flow rate of 1050 mL / second, and the curing is carried out at 100°C to 250°C for 60 to 240 minutes.

15. A printed circuit board comprising an insulating layer which is a cured product of the curable composition described in claim 1.

16. A printed circuit board according to claim 15, comprising a circuit fabricated by a method including a plasma etching step for via and / or trench formation.

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