Halogen-free flame-retardant epoxy resin composition and ultrathin ion migration-resistant cover film prepared by using halogen-free flame-retardant epoxy resin composition

Abstract

The invention discloses a halogen-free flame-retardant epoxy resin composition which comprises the following components in parts by weight: 10-25 parts of halogen-free bisphenol A type epoxy resin, 10-25 parts of halogen-free polyurethane modified epoxy resin, 5-15 parts of halogen-free polyfunctional epoxy resin, 5-15 parts of halogen-free organic silicon modified epoxy resin, 5-15 parts of halogen-free phosphorus-containing epoxy resin and 15-40 parts of a toughening agent. The flame retardant is prepared from the following components in parts by weight: 15-30 parts of a phosphorus-containing flame retardant, 1-10 parts of an amine curing agent, 0.01-1 part of a curing accelerator and 0.5-8 parts of an ion trapping agent. The invention also provides an ultrathin ionic migration-resistant cover film prepared from the resin composition, and the cover film has good flame retardance and can pass an ionic migration-resistant test under the condition that the line width / line distance is 50 [mu] m.

Description

Technical Field

[0001] The invention belongs to the technical field of halogen-free flame-retardant epoxy resins, and in particular relates to a halogen-free flame-retardant epoxy resin composition and an ultra-thin ion migration resistant covering film prepared using the same. Background Art

[0002] With the rapid development of social economy, there are currently two methods for making ultra-thin covering films: one is to remove the film layer such as polyimide, and superimpose the coating and adhesive layer to make a pure adhesive film material. Although this method can reduce the thickness of the covering film, it is difficult for the pure adhesive film to have flame retardant properties, and the lack of a film support carrier, the physical properties such as the strength of the covering film are poor, and it is difficult to meet the increasingly stringent process requirements of the circuit board industry, such as the method for making ultra-thin covering films in patents CN106590458A and CN109041403B. The other is to prepare an ultra-thin covering film by a conventional method of coating an adhesive layer on a supporting film such as a polyimide film. This method can ensure the strength of the covering film and is currently the main method for making ultra-thin covering films, such as the method for making ultra-thin covering films in patents CN210394241U, CN207630642U, CN109628005B, CN104476882B, and CN108102569B. However, the ultra-thin covering films prepared by the above two methods do not have the function of resisting ion migration.

[0003] Currently, some of the covering films with ion migration resistance function do not specify the size of the comb-type circuit used in the test, and some mentioned that the size of the comb-type circuit for the ion migration resistance test is only 4 / 4 (line width 100μm, line spacing 100μm) or 3 / 3 (line width 75μm, line spacing 75μm). There is no relevant record of 2 / 2, that is, line width 50μm, line spacing 50μm. For example, although patents CN115851179A, CN116515239A, CN108676475A, and CN105482442A have the ion migration resistance function, the size of the comb-type circuit for the ion migration resistance test does not reach 2 / 2. Summary of the invention

[0004] The purpose of the present invention is to provide a halogen-free flame-retardant epoxy resin composition and an ultra-thin ion migration resistant covering film prepared using the same in view of the deficiencies in the prior art. The covering film has good flame retardancy and can pass the ion migration resistance test under the condition that the line width / line spacing is 50μm.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides a halogen-free flame-retardant epoxy resin composition, which comprises the following components in parts by weight, calculated by parts by solid weight:

[0007]

[0008] The halogen-free flame-retardant epoxy resin composition of the present invention also includes an appropriate amount of organic solvent.

[0009] (1) Halogen-free bisphenol A epoxy resin

[0010] Halogen-free bisphenol A epoxy resin is produced by the reaction of bisphenol A and epichlorohydrin in the presence of sodium hydroxide. It has high bonding strength, wide bonding surface, good dimensional stability, low curing shrinkage (less than 2%), acid and alkali resistance, high mechanical strength, and excellent electrical insulation. Depending on the molecular weight and degree of polymerization n, the resin is a yellow to amber transparent viscous liquid (or solid). Generally, those with an average molecular weight between 300 and 700, n<2, and a softening point below 50°C are called low molecular weight bisphenol A epoxy resins (i.e., soft resins); those with a molecular weight above 1000, n>2, and a softening point above 60°C are called high molecular weight bisphenol A resins (i.e., hard resins). Regardless of the above type, as long as it can meet the performance requirements of use, it can be used in the formulation of the present invention. Currently commercially available bisphenol A epoxy resins include MY 790-1 and GT 7072 (manufactured by Huntsman Company, USA), etc.

[0011] (2) Halogen-free polyurethane modified epoxy resin

[0012] In the present invention, the modification method of the halogen-free polyurethane modified epoxy resin can be to synthesize a polyurethane prepolymer from a polyhydroxy compound and a polyisocyanate, and then to synthesize the halogen-free polyurethane modified epoxy resin by grafting the prepolymer with an epoxy resin; or to directly synthesize the halogen-free polyurethane modified epoxy resin by bulk synchronous polymerization; no matter which of the above methods the halogen-free polyurethane modified epoxy resin is prepared, as long as it can meet the performance requirements of use, it can be used in the formulation of the present invention. Currently available halogen-free polyurethane modified epoxy resins include HyPox UA 10 and HyPox UA 11 (manufactured by CVC Thermosetting Specialty Materials Company, USA), etc.

[0013] In the present invention, the halogen-free polyurethane modified epoxy resin and the toughening agent are used together. By adjusting the formulation system, the toughening effects of the two can be fully exerted. In addition, since the molecular weight of the halogen-free polyurethane modified epoxy resin is not large, the cross-linking density of the cured product can be increased to a certain extent, thereby increasing the cohesive strength of the adhesive layer, and finally increasing the peel strength of the covering film.

[0014] (3) Halogen-free multifunctional epoxy resin

[0015] In the present invention, the halogen-free multifunctional epoxy resin is an epoxy resin having 3 or more epoxy groups in its molecular structure, or Structural compounds and their derivatives.

[0016] This type of halogen-free multifunctional epoxy resin has a high crosslinking density after curing, and can maintain excellent mechanical and insulating properties at high temperatures; some multifunctional epoxy resin molecules contain an alicyclic epoxy group and two glycidyl ester groups, so they have both the high temperature resistance and weather resistance of alicyclic epoxy compounds and the high strength and high adhesion of glycidyl ester epoxy compounds; and another type of multifunctional epoxy resin molecules has four epoxy groups and two aromatic rings, so the activity is much higher than that of ordinary bisphenol A epoxy resin, and its curing speed is fast, the crosslinking density of the cured product is extremely large, the shrinkage rate is low, and it has high Tg and high strength. The commercially available halogen-free multifunctional epoxy resins include MY-720, 742 (manufactured by Huntsman Company, USA).

[0017] (4) Halogen-free silicone modified epoxy resin

[0018] In the present invention, the halogen-free organosilicon-modified epoxy resin is prepared by introducing organosilicon into epoxy resin by physical blending or chemical reaction. The chemical reaction mainly utilizes the organosilicon terminal functional groups (such as alkoxy, amino and hydroxyl groups) to react with the epoxy groups in the epoxy resin to generate core-shell structure, graft or block structure copolymers. Such organosilicon-modified epoxy resin has both high heat resistance and strong toughness.

[0019] Compatibility is an important factor affecting the effect of silicone-modified epoxy resin. The above two methods have overcome this problem well.

[0020] In addition, the halogen-free organosilicon-modified epoxy resin itself has excellent flame retardancy and can form a heat-resistant protective layer, making it an environmentally friendly flame retardant material. Regardless of the above method of preparing the halogen-free organosilicon-modified epoxy resin, as long as it meets the performance requirements of use, it can be used in the formulation of the present invention. Introducing halogen-free organosilicon-modified epoxy resin into the formulation system can not only improve the toughness and heat resistance of the halogen-free flame-retardant epoxy resin composition (glue), but also improve weather resistance, low temperature resistance and reduce surface energy. Currently commercially available halogen-free organosilicon-modified epoxy resins include EP 2240A and A410 (manufactured by Evonik Industries AG), etc.

[0021] (5) Halogen-free phosphorus-containing epoxy resin

[0022] In the present invention, the halogen-free phosphorus-containing epoxy resin refers to an epoxy resin that is inherently flame-retardant and is chemically bonded to the epoxy resin molecular chain using reactive phosphorus compounds. Commercially available halogen-free phosphorus-containing epoxy resins include XEN-0140, SEN-6085 (SHIN-A T&C, South Korea), and the like.

[0023] Optionally, the phosphorus content of the halogen-free phosphorus-containing epoxy resin is 0.5%-16%.

[0024] The reactive phosphorus compound can be DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide), DOPO-BQ, DOPO-NQ, DOPO-2OH and other phosphaphenanthrene compounds, and DOPO derivatives: 10-(2,5-diphenyl)-10-hydrogen-9-oxa-10-phosphaphenanthrene-10-oxide, or other reactive organic phosphorus and inorganic phosphorus compounds. As long as the performance requirements of use are met, any modified phosphorus-containing epoxy resin can be used in the formulation of the present invention.

[0025] The structural formulas of DOPO-BQ, DOPO-NQ and DOPO-2OH are shown below:

[0026]

[0027] (6) Toughening agent

[0028] In the present invention, the toughening agent is one or more of synthetic rubber, polyurethane toughening agent and elastomer.

[0029] The synthetic rubber is one of nitrile rubber, styrene butadiene rubber, butadiene rubber and ethylene propylene rubber. Commercially available nitrile rubber includes CTBN 1300×8 (manufactured by CVC Thermosetting Special Materials Company, USA), styrene butadiene rubber includes BunaVSL 5025-2HM (manufactured by Lanxess), butadiene rubber includes BR-9000 (manufactured by Sinopec), ethylene propylene rubber includes EPDM6950 (manufactured by Lanxess), and polyurethane tougheners and elastomers include Desmocap11A (manufactured by Covestro).

[0030] (7) Phosphorus-containing flame retardants

[0031] In the present invention, the phosphorus-containing flame retardant includes but is not limited to PX-200 (manufactured by Daihachi Chemical Industry Co., Ltd., Japan) and OP930 (manufactured by Clariant, Germany).

[0032] (8) Amine curing agent

[0033] In the present invention, the amine curing agent is one or more of 4,4'-diaminodiphenylmethane, meta-phenylenediamine, meta-phenylenediamine or dicyandiamide.

[0034] (9) Curing accelerator

[0035] In the present invention, the curing accelerator is one or more of N-(2-hydroxyphenyl)-N',N'-dimethylurea, N-(2-hydroxy-4-nitrobenzene)-N',N'-dimethylurea, N-(4-chlorophenyl)-N',N'-dimethylurea, N-(5-chloro-2-hydroxybenzene)-N',N'-dimethylurea, 2,4,6-tris(dimethylaminomethyl)phenol, and boron trifluoride.

[0036] (10) Ion Scavenger

[0037] In the present invention, the ion capture agent is a zirconium compound cation exchanger containing a single Zr(HPO4)2·H2O structure, and a zirconium compound containing Zr(HPO4)2·H2O and Mg6Al2(CO3)(OH) 16 ·4H2O magnesium aluminum compound two structures together composed of zwitterionic ion exchanger.

[0038] Commercially available ion scavengers include IXE-100, IXEPLAS-A1, IXEPLAS-A2 (Toagosei Co., Ltd.), and the like.

[0039] In addition, the present invention also provides an ultra-thin ion migration resistant covering film prepared from the above-mentioned halogen-free flame retardant epoxy resin composition, comprising: a polyimide film, a halogen-free flame retardant epoxy resin composition layer coated on the polyimide film, and a release paper attached to the halogen-free flame retardant epoxy resin composition layer.

[0040] Wherein, the polyimide insulating film is an amber or light brown transparent insulating film, and the thickness of the polyimide insulating film is 3-10 μm; the coating thickness of the halogen-free flame-retardant epoxy resin composition layer is 3-10 μm.

[0041] The thickness of the release paper is 50-150 μm.

[0042] In the present invention, the method for preparing the ultra-thin ion migration resistant covering film comprises the following steps:

[0043] S1. Mix the components of the halogen-free flame-retardant epoxy resin composition in proportion, add an organic solvent to dissolve and mix to form a suspension slurry, and use the organic solvent to adjust the suspension slurry to a suitable rotational viscosity before coating the suspension slurry on the polyimide film;

[0044] S2. The polyimide film coated with the suspension slurry is passed through an oven and heated at 70-180° C. for 3 to 7 minutes to form a composition layer in a solvent-free adhesive film state after drying. Thereafter, a release paper is thermally laminated under conditions of 60-100° C. and 0.05-2.0 MPa, and a covering film is obtained after winding.

[0045] The rotational viscosity of the suspension slurry is 500-2000 cps. This viscosity range can achieve good processability and ensure that no appearance defects occur during the coating process.

[0046] The organic solvent is one or more of acetone, butanone, cyclohexanone, toluene, ethylene glycol methyl ether, propylene glycol methyl ether, propylene glycol methyl ether acetate, dimethylformamide and dimethyl sulfoxide.

[0047] In the process of preparing the halogen-free flame-retardant epoxy resin composition of the present invention, grinding equipment such as a sand mill is used in combination with dispersing equipment such as a high-speed stirrer, so that the resin component, inorganic solid component, curing agent, auxiliary agent and organic solvent in the composition of the present invention can be uniformly mixed together.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] The ultra-thin ion migration resistant covering film prepared by using the halogen-free flame retardant epoxy resin composition of the present invention has good flame retardancy, can meet the UL94 V0 flame retardancy requirement, has high peel strength, good dimensional stability, excellent processing performance, and can pass the ion migration resistance test under the condition that the line width / line spacing is 50 μm. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a schematic structural diagram of the ultra-thin ion migration resistant covering film of the present invention. DETAILED DESCRIPTION

[0051] The present invention will be further described below with reference to specific embodiments, but is not limited thereto.

[0052] In this specific embodiment, the halogen-free flame retardant epoxy resin composition, calculated by solid weight, includes the following components in parts by weight:

[0053]

[0054]

[0055] A proper amount of organic solvent is also added to the halogen-free flame-retardant epoxy resin composition to dissolve the solid composition.

[0056] The present embodiment also provides an ultra-thin ion migration resistant covering film prepared from the above-mentioned halogen-free flame retardant epoxy resin composition, comprising: a polyimide film 1, a halogen-free flame retardant epoxy resin composition layer 2 coated on the polyimide film 1, and a release paper 3 attached to the halogen-free flame retardant epoxy resin composition layer 2.

[0057] The polyimide insulating film 1 is an amber or light brown transparent insulating film, and the thickness of the polyimide insulating film 1 is 3-10 μm; the coating thickness of the halogen-free flame-retardant epoxy resin composition layer 2 is 3-10 μm; and the thickness of the release paper 3 is 50-150 μm.

[0058] In this embodiment, the method for preparing the ultra-thin ion migration resistant covering film comprises the following steps:

[0059] S1. Mix the components of the halogen-free flame-retardant epoxy resin composition in proportion, add an organic solvent to dissolve and mix to form a suspension slurry, and use the organic solvent to adjust the suspension slurry to a suitable rotational viscosity before coating the suspension slurry on the polyimide film;

[0060] S2. The polyimide film coated with the suspension slurry is passed through an oven and heated at 70-180° C. for 3 to 7 minutes to form a composition layer in a solvent-free adhesive film state after drying. Thereafter, a release paper is thermally laminated under conditions of 60-100° C. and 0.05-2.0 MPa, and a covering film is obtained after winding.

[0061] Wherein, the rotational viscosity of the suspension slurry is 500-2000cps.

[0062] In this specific embodiment, Examples 1-4 are set to prepare the halogen-free flame-retardant epoxy resin composition and the ultra-thin ion migration resistant covering film of the present invention, wherein the formula of each component is shown in Table 1, and each formula composition is calculated in parts by weight of raw materials:

[0063] Table 1 Formula of each component in Examples 1-4 (unit: part)

[0064]

[0065] According to the above-mentioned method for preparing the ultra-thin ion migration resistant covering film, the composition in Examples 1-4 is evenly coated on a polyimide film with a thickness of 7.5 μm, and the coating thickness is 8 μm. It is then placed in an oven and baked for 4 minutes at 170°C. It is then laminated with the release paper by a hot roller and rolled up to obtain the thin ion migration resistant covering films prepared in Examples 1-4.

[0066] Comparative Example 1

[0067] The reference formula is calculated as 100 parts by weight except the solvent. Except for the halogen-free multifunctional epoxy resin, the addition ratio of other components is the same as that of Example 1; the halogen-free multifunctional epoxy resin is replaced with an equal amount of ordinary epoxy resin E51.

[0068] Comparative Example 2

[0069] The base formula is calculated as 100 parts by weight except the solvent. Except for the halogen-free organosilicon-modified epoxy resin, the addition ratio of other components is the same as that of Example 1; the halogen-free organosilicon-modified epoxy resin is replaced with an equal amount of ordinary epoxy resin E51.

[0070] Comparative Example 3

[0071] The base formula is calculated as 100 parts by weight except the solvent. Except for the ion scavenger, the addition ratio of other components is the same as that of Example 1; the ion scavenger is replaced with an equal amount of phosphorus-containing flame retardant OP930.

[0072] The specific component formula content is shown in Table 2

[0073] Table 2 Formula of each component in Comparative Examples 1-3 (unit: part)

[0074]

[0075]

[0076] The components of the comparative examples in Table 2 were prepared according to the method for preparing the ultra-thin ion migration resistant covering film in the above embodiments, and the compositions in comparative examples 1-3 were uniformly coated on a polyimide film with a thickness of 7.5 μm, with a coating thickness of 8 μm. The films were then placed in an oven at 170°C and baked for 4 minutes. The films were then laminated with release paper using a hot roller and rolled up to obtain the covering films prepared in the comparative examples.

[0077] Performance Testing

[0078] The performance tests were conducted on the covering film tapes prepared in Examples 1-4 and Comparative Examples 1-3. The test items, test methods and standards are as follows:

[0079] (1) Thickness: Tested according to GB / T7125-2014 method.

[0080] (2) Peel strength: Test the peel strength between the cover film and the copper foil according to IPC-TM-650 2.4.9 method.

[0081] (3) Glue overflow: Tested according to IPC-TM-650 2.3.17 method.

[0082] (4) Solder resistance: Tested according to IPC-TM-650 2.4.13 method.

[0083] (5) Ion migration resistance test: The test was conducted in accordance with IPC-TM-250 2.6.25 method, and the test line used a 2 / 2 (line width / line spacing: 50 / 50 μm) comb-type line.

[0084] (6) Dimensional stability: Tested in accordance with IPC-TM-650 2.2.4 method.

[0085] (7) Flame retardancy: tested according to UL94 vertical burning method.

[0086] The test results are shown in Table 3.

[0087] Table 3 Performance test results of embodiments and comparative examples

[0088]

[0089]

[0090] According to Table 3, the ultra-thin ion migration resistant covering films prepared in Examples 1-4 can pass the ion migration resistant test under the condition that the line width / line spacing is 50μm, and can pass the flame retardant requirements of UL94 V0, and have high peel strength and good dimensional stability. However, in Comparative Example 1, no halogen-free multifunctional epoxy resin is added compared to Example 1, and its line insulation resistance is greatly reduced under the condition of 85℃ / 85%RH / 1000h. In Comparative Example 2, no halogen-free organosilicon modified epoxy resin is added compared to Example 1, and the covering film prepared is not flame retardant. In Comparative Example 3, no ion scavenger is added compared to Example 1, and the covering film prepared has a poor process under the condition of 85℃ / 85%RH / 1000h. It can be seen that only by adding halogen-free multifunctional epoxy resin, halogen-free organosilicon modified epoxy resin, and ion scavenger at the same time can the ultra-thin ion migration resistant covering film of the present invention with high performance and capable of passing the ion migration resistant test under the condition that the line width / line spacing is 50μm be prepared.

[0091] In summary, the halogen-free flame-retardant epoxy resin composition of the present invention and the prepared ultra-thin ion migration resistant covering film not only achieve significant thinning in thickness, but also can pass the more stringent ion migration resistance test under the condition of line width / line spacing of 50 μm, meeting the requirements of the downstream industry for thinness and high insulation reliability, leading the industry; and can pass the flame retardant requirements of UL94 V0, with high peel strength, good dimensional stability and excellent processing performance.

Claims

1. A halogen-free flame retardant epoxy resin composition, calculated by solid weight, comprising the following components in parts by weight:

2. The halogen-free flame-retardant epoxy resin composition according to claim 1, characterized in that The halogen-free multifunctional epoxy resin is an epoxy resin having 3 or more epoxy groups in its molecular structure, or Structural compounds and their derivatives.

3. The halogen-free flame-retardant epoxy resin composition according to claim 1, characterized in that The halogen-free organosilicon-modified epoxy resin is prepared by introducing organosilicon into the epoxy resin through physical blending or chemical reaction.

4. The halogen-free flame-retardant epoxy resin composition according to claim 1, characterized in that The halogen-free phosphorus-containing epoxy resin refers to an epoxy resin with intrinsic flame retardancy synthesized by using reactive phosphorus compounds to be chemically bonded to the epoxy resin molecular chain; the phosphorus content of the halogen-free phosphorus-containing epoxy resin is 0.5%-16%.

5. The halogen-free flame-retardant epoxy resin composition according to claim 4, characterized in that The reactive phosphorus compound is one of DOPO, DOPO-BQ, DOPO-NQ, DOPO-2OH, 10-(2,5-diphenyl)-10-hydrogen-9-oxa-10-phosphaphenanthrene-10-oxide, or other reactive organic phosphorus and inorganic phosphorus compounds.

6. The halogen-free flame-retardant epoxy resin composition according to claim 1, characterized in that The ion capture agent is a zirconium compound cation exchanger containing a single Zr(HPO4)2·H2O structure, or a zirconium compound containing Zr(HPO4)2·H2O and Mg6Al2(CO3)(OH) 16 One of the zwitterionic ion exchangers composed of two structures of magnesium-aluminum compound of 4H2O.

7. An ultra-thin ion migration resistant covering film prepared from the halogen-free flame retardant epoxy resin composition according to any one of claims 1 to 6, characterized in that include: A polyimide film (1), a halogen-free flame-retardant epoxy resin composition layer (2) coated on the polyimide film (1), and a release paper (3) attached to the halogen-free flame-retardant epoxy resin composition layer (2).

8. The ultra-thin ion migration resistant covering film according to claim 1, characterized in that The polyimide insulating film is an amber or light brown transparent insulating film, and the thickness of the polyimide insulating film is 3-10 μm; the coating thickness of the halogen-free flame-retardant epoxy resin composition layer is 3-10 μm.

9. A method for preparing the ultra-thin ion migration resistant covering film according to claim 7 or 8, characterized in that The following steps are included: S1. Mix the components of the halogen-free flame-retardant epoxy resin composition in proportion, add an organic solvent to dissolve and mix to form a suspension slurry, and use the organic solvent to adjust the suspension slurry to a suitable rotational viscosity before coating the suspension slurry on the polyimide film; S2, passing the polyimide film coated with the suspension slurry through an oven, heating at 70-180° C. for 3 to 7 minutes to dry to form a composition layer containing a solvent-free adhesive film, and then thermally laminating the film with release paper at 60-100° C. and 0.05-2.0 MPa, and rolling the film to obtain a covering film; Wherein, the rotational viscosity of the suspension slurry is 500-2000cps.

10. The method for preparing the ultra-thin ion migration resistant covering film according to claim 9, characterized in that The organic solvent is one or more of acetone, butanone, cyclohexanone, toluene, ethylene glycol methyl ether, propylene glycol methyl ether, propylene glycol methyl ether acetate, dimethylformamide and dimethyl sulfoxide.

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