Sealant composition for protective film layer, and protective film for electronic component

Abstract

[Problem] To provide a sealant composition for a protective film layer, said sealant composition being made of a resin and being cured at a lower temperature than the firing temperature of an overcoat agent comprising a glass paste. [Solution] This sealant composition for a protective film layer is characterized by including: a bisnadimide compound that is represented by chemical formula 1 and in which a divalent hydrocarbon group (R1) is bonded to nitrogen atoms of imide groups having norbornene skeletons; a phenolic resin; and a reactive diluent that has one or more epoxy groups. A resin cured film that has superior heat resistance can be formed using this composition, and thus this composition can be used as a sealant for a protective film layer of a chip resistor, a chip capacitor, or similar.

Description

Sealant composition for protective film layer and protective film for electronic components

[0001] This invention relates to a encapsulant composition for protective film layers used in chip electronic components such as chip resistors, chip capacitors, and chip inductors, and to a protective film for electronic components.

[0002] Chip electronic components such as chip resistors, chip capacitors, and chip inductors are widely used in the electrical circuits of electronic devices and electrical products, as well as in the electrical circuits of mobile devices such as automobiles.

[0003] Conventionally, when manufacturing this type of chip resistor, a thick film electrode paste is printed onto an insulating substrate such as alumina, dried, and then fired to form a pair of opposing electrodes. A thick film resistance paste is then printed between the resulting electrodes, dried, and fired to form a thick film resistor that will become a chip resistor.

[0004] However, thick-film resistors formed in this way have a large resistance distribution, which poses a problem in terms of yield when trying to achieve the desired resistance range.

[0005] To solve this problem, a protective glass paste is printed onto a thick film resistor, and after drying, it is fired to form a protective glass film (precoat film). Laser trimming is then performed through the resulting precoat film to adjust the resistance value of the thick film resistor (see, for example, Patent Document 1). The precoat film is provided to prevent debris generated by laser trimming from adhering to the thick film resistor. Furthermore, because the formation of the precoat film prevents the laser light from directly hitting the thick film resistor, it also reduces the damage the thick film resistor receives during laser trimming.

[0006] After laser trimming, an overcoat agent consisting of the same or a different glass paste as the precoat film is printed to cover the surface of the thick film resistor and the precoat film. After drying, it is fired to form a protective film that protects the thick film resistor from the external environment.

[0007] However, because the overcoat agent, which consists of glass paste, needs to be fired at a high temperature of 500°C to 700°C, the resistance value adjusted by laser trimming sometimes deviated from the desired range after firing.

[0008] For this reason, instead of conventional overcoat agents made of glass paste, resin-based overcoat agents that cure at a lower temperature than the firing temperature of glass paste-based overcoat agents have been mainly used in recent years. For example, Patent Document 2 discloses a encapsulant for a protective film layer containing a cresol novolac type epoxy resin, a phenol aralkyl resin, and a phenol-modified xylene resin.

[0009] Japanese Patent Publication No. 2003-020250, Japanese Patent Publication No. 2009-091424 (see Claim 1 and Table 2)

[0010] Incidentally, among the electronic components installed in modern automobiles, those used in control systems such as engines, electric motors, and regenerative brakes require high heat resistance against the heat generated by the engine and power semiconductors. Currently, epoxy resins, which are commonly used, are resins with excellent properties, but their glass transition temperature is between 100°C and 250°C, and therefore, when used in automobile control systems, they cannot be said to have sufficient heat resistance.

[0011] Although Patent Document 2 states that the thermal decomposition temperature of the protective film layer sealant is 421°C, epoxy resin becomes rubbery at temperatures higher than the glass transition temperature, so its function as a sealant is insufficient.

[0012] Thus, conventionally, there have been few heat-resistant encapsulants for protective film layers, and there have been concerns about the reliability of encapsulant compositions used in automotive control system electronic components.

[0013] This invention was made in view of these problems, and its objective is to provide a protective film layer encapsulant composition that can be cured at a temperature lower than the firing temperature of an overcoat agent made of glass paste, and that can form a heat-resistant protective film with no surface irregularities.

[0014] Therefore, in order to solve the above problems, the inventors diligently conducted research and found that this could be achieved by creating a protective film layer encapsulant composition containing a bisnadiimide compound with a glass transition temperature of 300°C or higher and a phenolic resin.

[0015] In other words, the first invention of the present invention relates to a sealant composition for a protective film layer, wherein a divalent hydrocarbon group (R) is attached to the nitrogen atom of an imide group having a norbornene skeleton. 1 It is characterized by comprising a bisnadiimide compound represented by the following chemical formula 1 to which ) is bonded, a phenol resin, and a reactive diluent having one or more epoxy groups,

[0016]

[0017] The second invention relates to the protective film layer sealing agent composition described in the first invention, wherein the bisnadiimide compound has a monovalent hydrocarbon group (R) on the norbornene skeleton. 2 It is characterized by being composed of a bisnadiimide represented by the following chemical formula 2, to which ) is bonded.

[0018]

[0019] Furthermore, the third invention according to the present invention is characterized in that, in the protective film layer sealing agent composition described in the first or second invention, the phenol resin is composed of a novolac-type phenol resin, and the fourth invention is characterized in that, in the protective film layer sealing agent composition described in the first or second invention, the reactive diluent is composed of a glycidyl ether having one epoxy group.

[0020] Next, the fifth invention according to the present invention is a protective film for electronic components in which a divalent hydrocarbon group (R) is attached to the nitrogen atom of an imide group having a norbornene skeleton. 1 It is characterized by being composed of a cured film formed by a curing reaction between a bisnadiimide compound represented by the following chemical formula 1, to which the ) is bonded, and a phenol resin,

[0021]

[0022] The sixth invention relates to a protective film for electronic components described in the fifth invention, wherein the bisnadiimide compound has a monovalent hydrocarbon group (R) on the norbornene skeleton. 2 It is characterized by being composed of a bisnadiimide represented by the following chemical formula 2, to which ) is bonded.

[0023]

[0024] According to the protective film layer encapsulant composition of the present invention, since it contains a bisnadiimide compound represented by the above chemical formula 1 and a phenol resin, which have a glass transition temperature of 300°C or higher, the curing reaction between the bisnadiimide compound and the phenol resin proceeds at a temperature lower than the firing temperature of the overcoat agent made of glass paste, making it possible to form a heat-resistant protective film with no surface irregularities.

[0025] Embodiments of the present invention will be described in detail below.

[0026] First, the protective film layer sealing agent composition according to the present invention comprises a divalent hydrocarbon group (R) attached to the nitrogen atom of an imide group having a norbornene skeleton. 1 The present invention is characterized by comprising a bisnadiimide compound represented by the following chemical formula 1 to which ) is bonded, a phenol resin, and a reactive diluent having one or more epoxy groups.

[0027]

[0028] The following describes in detail each component of the protective film layer encapsulant composition according to the present invention.

[0029] 1. Bisnadiimide compounds Bisnadiimide compounds have a divalent hydrocarbon group (R) attached to the nitrogen atom of an imide group having a norbornene skeleton. 1 It is a thermosetting imide compound represented by the following chemical formula 1, in which ) is bonded, possessing a rigid structure and high reactivity.

[0030]

[0031] In chemical formula 1, R 1 R is a divalent hydrocarbon group, 1Examples include aliphatic hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. The inclusion of the aromatic hydrocarbon groups enables the molecules of the bisnadimide compound to be more rigid.

[0032] Examples of the aliphatic hydrocarbon group include a hydrocarbon group (alkene group) represented by the following chemical formula 3. Examples of the aromatic hydrocarbon group include a hydrocarbon group represented by the following chemical formula 4 having a structure in which an aromatic ring (phenylene group) is sandwiched by methylene groups, and a hydrocarbon group represented by the following chemical formula 5 having a structure in which a methylene group is sandwiched by an aromatic ring (phenylene group).

[0033]

[0034]

[0035]

[0036] And R 1 Preferably, the hydrocarbon groups represented by Chemical Formula 4 and Chemical Formula 5 are used, and more preferably, the hydrocarbon group represented by Chemical Formula 5 is used. When the aromatic ring (phenylene group) is directly bonded to the nitrogen atom, the bisnadimide compound becomes more rigid, and if the molecule becomes rigid, the heat resistance of the molecule is further improved.

[0037] Further, the degree of polymerization (n) of the hydrocarbon groups represented by Chemical Formula 4 and Chemical Formula 5 is preferably 1. Even if the bisnadimide compound used in this embodiment has a rigid molecular structure, if the divalent hydrocarbon group (R 1 ) becomes long, the structure of the bisnadimide compound may cause steric hindrance and prevent the curing reaction with the phenolic resin during heating. Therefore, the degree of polymerization (n) of the hydrocarbon groups represented by Chemical Formula 4 and Chemical Formula 5 is preferably 1.

[0038] Incidentally, the bisnadimide compound is an imide compound having a norbornene skeleton. The double bond of the norbornene ring is generally easily ring-opened and is known to be highly reactive. In the bisnadimide compound represented by Chemical Formula 1, the double bond of the norbornene ring is similarly highly reactive.

[0039] Further, a monovalent hydrocarbon group (R 2A bisnadiimide compound represented by the following chemical formula 2, to which ) is bonded, can also be used.

[0040]

[0041] Furthermore, monovalent hydrocarbon groups (R 2 To illustrate with an example of a group with three carbon atoms, the propyl group shown in chemical formula 6 and the allyl group shown in chemical formula 7 are given as examples.

[0042]

[0043]

[0044] When introducing the allyl group as described above, it is desirable to have a double bond at the terminal end.

[0045] [Solvents for Bisnadiimide Compounds] Incidentally, dissolving polyimide resins often requires highly polar solvents such as N-methyl-2-pyrrolidone (NMP). If the paste is wiped with a less polar solvent during paste preparation or cleaning during screen printing evaluation, polyimide may precipitate, causing the printing screen to clog. For this reason, it is always necessary to clean the screen with a highly polar solvent such as NMP, which makes handling difficult when manufacturing or evaluating protective film layer encapsulant compositions.

[0046] On the other hand, the bisnadiimide compound used in this embodiment has good compatibility with solvents, so it is possible to use solvents and diluents that are not highly polar, such as terpinol, butyl carbitol, and butyl carbitol acetate, which are widely used in thick film pastes. Therefore, since solvents such as terpinol can be used with the bisnadiimide compound, it is possible to adjust the viscosity to one suitable for screen printing and the like, making it suitable for the production of encapsulant compositions for protective film layers.

[0047] However, it is necessary to check in advance whether there is any risk of dissolving other resins, such as the emulsion of the screen used in screen printing, and if there is no problem, it can be used. In addition, it is preferable to dissolve the bisnadiimide compound in another solvent beforehand, and the solvent used should be one that can be completely eliminated by evaporation after the resin has hardened, and that does not cause the paste to thicken due to the volatilization of the solvent in the paste at room temperature during the coating process.

[0048] 2. Phenolic Resin The phenolic resin used in this embodiment functions as a curing agent for the bisnadiimide compound, but the function of the phenolic resin as a curing agent will be described later.

[0049] Phenolic resins come in novolac and resol types, but in this embodiment, it is preferable to use a novolac type phenolic resin. Resol type phenolic resins may react during storage, which can cause problems with the shelf life of the protective film layer encapsulant composition.

[0050] On the other hand, novolac-type phenolic resins are suitable from the viewpoint of the heat curing of the protective film layer encapsulant composition of this embodiment, as the curing reaction proceeds when heated, and it is desirable that they have excellent storage stability, moisture resistance of the cured product, and adhesion.

[0051] Furthermore, the phenolic resin is preferably one with a hydroxyl group equivalent of 90 g / eq or more, more preferably one with a hydroxyl group equivalent of 100 g / eq to 250 g / eq, even more preferably one with a hydroxyl group equivalent of 100 g / eq to 200 g / eq, and even more preferably one with a hydroxyl group equivalent of 100 g / eq to 140 g / eq. The hydroxyl groups of the phenolic resin contribute to the reactivity of the electrophilic reaction as a curing agent; therefore, if the hydroxyl group equivalent is less than 90 g / eq, it is insufficient for the curing reaction of the bisnadiimide compound. On the other hand, if the hydroxyl group equivalent exceeds 250 g / eq, the curing reaction of the bisnadiimide compound proceeds rapidly, and cracks may occur in the cured film (i.e., protective film). For this reason, a phenolic resin with a hydroxyl group equivalent of 90 g / eq to 250 g / eq is desirable. Furthermore, from the viewpoint of the storage properties and reactivity of the protective film layer encapsulant composition, the softening point of the phenolic resin is preferably 60°C or higher, more preferably 65°C or higher, and even more preferably 70°C or higher.

[0052] Furthermore, hydroxyl group equivalent refers to the value measured by the neutralization method in accordance with JIS K 0070.

[0053] Furthermore, the amount of phenol resin added is preferably 5 to 35 parts by mass, more preferably 5 to 30 parts by mass, and even more preferably 15 to 30 parts by mass, per 100 parts by mass of the bisnadiimide compound.

[0054] If the amount of phenol resin added is less than 5 parts by mass per 100 parts by mass of bisnadiimide compound, cracks and irregularities may occur in the protective film, which is the cured product of the protective film layer sealing agent composition, and it will not function as a protective film. On the other hand, if the amount of phenol resin added exceeds 35 parts by mass, the properties of the cured product do not improve in proportion to the amount exceeding the limit.

[0055] 3. Reactive Diluent The protective film layer encapsulant composition according to this embodiment uses a reactive diluent having one or more epoxy groups. The reactive diluent reacts with the bisimide compound and phenol resin described above to cure, contributing to the formation of the protective film and improvement of its strength.

[0056] Furthermore, since the reactive diluent is a liquid, it is possible to adjust the viscosity of the protective film layer encapsulant composition using the reactive diluent.

[0057] Examples of reactive diluents include monofunctional epoxy such as glycidol, cyclohexylglycidyl ether, tert-butylglycidyl ether, allylglycidyl ether, and p-tert-butylphenylglycidyl ether, and examples of difunctional epoxy such as ethylene glycol diglycidyl ether, glycerol diglycidyl ether, polyethylene glycol diglycidyl ether, polyethylene glycol polyglycidyl ether, polyglycerol diglycidyl ether, diglycerol polyglycidyl ether, glycerol triglycidyl ether, and propylene glycol diglycidyl ether.

[0058] In the reactive diluent used in the encapsulant composition for protective film layers, it is preferable to use a reactive diluent of monofunctional epoxy in order to avoid increasing viscosity due to the reactive diluent. Among these, it is preferable to use tert-butylglycidyl ether, allylglycidyl ether, or p-tert-butylphenylglycidyl ether.

[0059] Furthermore, the amount of reactive diluent added is 50 parts by mass or more and 80 parts by mass or less per 100 parts by mass of bisnadiimide compound. If the amount of reactive diluent added is less than 50 parts by mass, the fluidity of the protective film layer sealing agent composition when cured at 200°C to 300°C (a condition lower than the firing temperature of the overcoat agent consisting of glass paste) will be impaired, and irregularities or cracks may occur in the cured protective film. On the other hand, if the amount of reactive diluent added exceeds 80 parts by mass, unreacted reactive diluent may remain and impair the function of the cured protective film.

[0060] 4. Other Contents The protective film layer encapsulant composition according to this embodiment may also contain solvents and diluents that are not highly polar, such as terpinol, butyl carbitol, and butyl carbitol acetate, which are widely used in thick film pastes. These solvents and diluents can control the viscosity of the protective film layer encapsulant composition and improve printability and coatability. The boiling point of these solvents and diluents is preferably 200°C to 250°C. By using solvents and diluents with a boiling point of 200°C to 250°C, it is possible to prevent the protective film layer encapsulant composition from drying out during screen printing. Furthermore, even if these solvents and diluents are included in the protective film layer encapsulant composition, they are almost entirely removed by volatilization during the drying process at 80°C to 150°C performed after printing or coating, and therefore do not affect the curing reaction between the bisimide compound and the phenolic resin.

[0061] Furthermore, to maintain the shape of the protective film formed when the protective film layer encapsulant composition hardens, fillers can be added to the protective film layer encapsulant composition. Examples of fillers include fused silica, mica, talc, clay, calcium carbonate, and hydrated alumina, with fused silica and talc being preferred from the viewpoint of heat resistance, stability, and adhesion. Inorganic pigments such as Cr-Cu-Mn composite oxides, Co-Cr-Fe composite oxides, and chromium oxide may also be added.

[0062] 5. Curing Reaction No curing agent is known that can cure the bisnadiimide compound used in this embodiment in a time of 45 to 120 minutes. That is, the bisnadiimide compound used in this embodiment is a thermosetting compound, and the standard curing temperature is 250°C to 350°C, and the curing time is long, such as 24 hours.

[0063] In the manufacturing process of chip electronic components, even if a curing temperature of 350°C is acceptable for curing the protective film layer encapsulant composition, the 24-hour curing time significantly impairs the productivity of chip electronic components.

[0064] Furthermore, conventional overcoat agents made of glass paste require up to 30 minutes for the drying process after printing and up to 60 minutes for the firing process.

[0065] Incidentally, nitrogen compounds such as diamines and cyanates, or diallyl compounds that cause an ene reaction at the terminal double bond, are known as curing agents for diphenylmethanebismaleimide compounds, which have a structure similar to bisnadiimide compounds and are represented by the following chemical formula 8.

[0066]

[0067] Bisnadiimide compounds and bismaleimide compounds (diphenylmethanebismaleimide compounds), which have a similar structure, have traditionally been used in prepregs for copper-clad laminates used in printed circuit boards and flexible circuit boards, as well as in molding resins for semiconductors. For prepregs, it is sufficient if the material can be applied to a single surface without considering the shape, and for semiconductor molding resins, it is sufficient if it can be molded using a mold. For these reasons, bisnadiimide compounds have not been used in encapsulant compositions for protective film layers that are applied to specific shapes using screen printing or the like.

[0068] Furthermore, curing bisnadiimide compounds using accelerators and curing agents widely used for thermosetting epoxy resins is difficult, and currently, no suitable curing agents or curing accelerators for bisnadiimide compounds are known. For example, even when using imidazoles or dicyandiamides, which are curing agents and curing accelerators for thermosetting epoxy resins, bisnadiimide compounds cannot be properly cured, and as a result, adhesion strength may not be achieved. In addition, if bisnadiimide compounds are cured in a short time, distortion occurs on the surface of the cured product, resulting in unevenness on the surface of the cured product and weak adhesive strength. If unevenness or cracks occur on the surface of the cured film, it will not function as a protective film.

[0069] Thus, it was difficult to create a resin-based overcoat agent that could achieve the required adhesive strength in a short time, possess high heat resistance, and be cured with simple equipment.

[0070] However, under these technical circumstances, the inventors diligently continued their experiments and analyses and discovered that when a phenolic resin is used as a curing agent for a bisnadiimide compound, a resin-based overcoat agent that satisfies the above requirements can be obtained.

[0071] Specifically, we prepared a encapsulant composition for a protective film layer containing a bisnadiimide compound, a phenolic resin, and a reactive diluent having one or more epoxy groups. We found that after applying this encapsulant composition to the desired shape by means of screen printing or the like, a desired cured film is formed under conditions of 200°C to 300°C and 45 minutes to 90 minutes.

[0072] Furthermore, the curing reaction between the bisnadiimide compound and the phenolic resin is thought to occur due to the strong electron donation by the nitrogen atom of the imide group of the bisnadiimide compound, and further curing through the reaction of the nitrogen atom of the imide group with the reactive diluent.

[0073] 6. Formation of a protective film (protective film for electronic components) using the protective film layer encapsulant composition according to this embodiment. Using the protective film layer encapsulant composition according to this embodiment, a protective film (protective film for electronic components) can be formed to cover, for example, the outermost surface of a chip resistor.

[0074] In other words, after laser trimming is performed through a pre-coat film formed on a thick film resistor that will become a chip resistor, the protective film layer encapsulant composition according to this embodiment is screen printed so as to cover the surfaces of the thick film resistor and the pre-coat film.

[0075] Next, the solvent such as terpinol is removed by drying at a temperature of 80°C to 150°C for 15 minutes to 45 minutes, and then curing at a temperature of 200°C to 300°C for 45 minutes to 90 minutes, thereby forming a protective film (i.e., a protective film for electronic components) that covers the surface of the thick film resistor and precoat film of the chip resistor.

[0076] Examples and comparative examples of the present invention will be described in detail below.

[0077] The protective film layer encapsulant compositions for each example and comparative example were prepared by blending the raw materials to achieve the compositions shown in [Table 1-1] and [Table 1-2].

[0078] The ingredients used were as follows:

[0079] 1. Raw materials (1) Bisnadiimide compound (bisallylnadiimide) As a bisnadiimide compound, a divalent hydrocarbon group (R) is attached to the nitrogen atom of an imide group having a norbornene skeleton. 1 ) is bonded, and a monovalent hydrocarbon group (R) is attached to the norbornene skeleton. 2 A bisnadiimide compound represented by the following chemical formula 2, to which ) is bonded, was applied.

[0080] Furthermore, R 1 R is a hydrocarbon group represented by the following chemical formula 9, in which a methylene group is sandwiched between p-phenylene groups. 2 It is composed of an allyl group shown in chemical formula 7 below, and an example of a bis-allyl-nadiimide compound (bis-allyl-nadiimide) having this structure is "BANI-M" manufactured by Maruzen Chemical Co., Ltd.

[0081]

[0082]

[0083]

[0084] (2) Reactive Diluent As a reactive diluent, p-tert-butylphenylglycidyl ether (para-tert-butylphenylglycidyl ether), a monofunctional epoxy, was applied, and 60% by mass of a bisnadiimide compound (bis-allylnadiimide) was dissolved in 40% by mass of this reactive diluent to prepare a bisnadiimide compound vehicle.

[0085] Furthermore, in the following examples and comparative examples, this bisnadiimide compound vehicle (containing 60% by mass of bisallylnadiimide and 40% by mass of p-tert-butylphenylglycidyl ether) is used.

[0086] (3) Phenolic resin A novolac-type phenolic resin with a hydroxyl group equivalent of 105 g / eq was used as the phenolic resin, and 30% by mass of this phenolic resin was dissolved in 70% by mass of terpineol to prepare a phenolic resin vehicle.

[0087] In Examples 1 and 2, this phenolic resin vehicle (containing 30% by mass of phenolic resin and 70% by mass of terpineol) was used.

[0088] (4) Imidazole: 2-phenyl-4-methyl-5-hydroxymethylimidazole was used as the imidazole (curing accelerator).

[0089] (5) Dicyandiamide: Dicyandiamide with a particle size of 3 μm was used as the curing accelerator.

[0090] 2. Production of encapsulant compositions for protective film layers [Examples 1-2] A bisnadiimide compound vehicle (containing 60% by mass of bisallylnadiimide and 40% by mass of p-tert-butylphenyl glycidyl ether) and a phenol resin vehicle (containing 30% by mass of phenol resin and 70% by mass of terpineol) were combined and kneaded in a three-roll mill to produce encapsulant compositions for protective film layers according to Examples 1-2, with the compositions shown in [Table 1-1].

[0091] [Comparative Example 1] As the encapsulant composition for the protective film layer according to Comparative Example 1, the above-mentioned bisnadiimide compound vehicle (containing 60% by mass of bisallylnadiimide and 40% by mass of p-tert-butylphenylglycidyl ether) was used.

[0092] [Comparative Examples 2-3] The above-mentioned bisnadiimide compound vehicle (containing 60% by mass of bisallylnadiimide and 40% by mass of p-tert-butylphenylglycidyl ether) and 2-phenyl-4-methyl-5-hydroxymethylimidazole were combined and kneaded in a three-roll mill to produce protective film layer encapsulant compositions according to Comparative Examples 2-3, with compositions shown in [Table 1-1] and [Table 1-2].

[0093] [Comparative Examples 4-6] The above bisnadiimide compound vehicle (containing 60% by mass of bisallylnadiimide and 40% by mass of p-tert-butylphenylglycidyl ether), 2-phenyl-4-methyl-5-hydroxymethylimidazole, and dicyandiamide were combined and kneaded in a three-roll mill to produce protective film layer encapsulant compositions according to Comparative Examples 4-6, with the compositions shown in [Table 1-2].

[0094] 3. Evaluation (1) Observation of cured film The protective film layer encapsulant compositions according to Examples 1-2 and Comparative Examples 1-6 were printed on a 1-inch square alumina substrate using a 200-mesh stainless steel screen to a thickness of 40 μm. Then, they were dried for 30 minutes in a drying oven set at 80°C to obtain a dried film. Furthermore, each dried film was cured for 60 minutes in a curing oven set at 250°C to obtain observation-grade cured films (i.e., observation-grade protective films) according to Examples 1-2 and Comparative Examples 1-6.

[0095] Then, the cured films (protective films for observation) according to Examples 1-2 and Comparative Examples 1-6 were observed with a laser microscope to check for cracks and irregularities in the cured films.

[0096] These results are shown in [Table 1-1] and [Table 1-2].

[0097] (2) Room temperature adhesive strength A protective film layer encapsulant composition according to Examples 1 to 2 and Comparative Examples 1 to 6 was printed on a 1-inch square alumina substrate using a 200-mesh stainless steel screen to a thickness of 40 μm to obtain a printed film.

[0098] A 2 mm square silicon chip was placed on the obtained printed film, and then dried for 30 minutes in a drying oven set at 80°C. Further curing was performed for 60 minutes in a curing oven set at 250°C to obtain samples for measuring adhesive strength according to Examples 1-2 and Comparative Examples 1-6, in which the silicon chip was fixed to the surface of the cured film.

[0099] Next, a horizontal force was applied to the silicon chip of the obtained adhesive strength measurement sample, and the force required to peel the silicon chip from the alumina substrate (hereinafter referred to as "peel strength") was measured.

[0100] Then, the same test was performed on 20 adhesive strength measurement samples from Examples 1-2 and Comparative Examples 1-6 to measure peel strength, and the average value was evaluated as the room temperature adhesive strength (N: Newton).

[0101] These results are also shown in [Table 1-1] and [Table 1-2].

[0102]

[0103]

[0104] 4. Results (1) The protective film layer encapsulant composition according to Example 1 has a composition containing approximately 5% by mass (4.46% by mass) of phenolic resin.

[0105] (1-1) Observation results of the cured film There were no cracks in the cured film, and the surface irregularities of the cured film were minimal, indicating good quality. The evaluation of the cured film was "○" for both.

[0106] (1-2) Room temperature adhesive strength. However, the room temperature adhesive strength was 18.5 N, which is lower than that of Comparative Example 1 (28.6 N) of the bisnadiimide compound (bisallylnadiimide) alone, suggesting that the curing of the protective film layer encapsulant composition was somewhat insufficient.

[0107] (2) The protective film layer encapsulant composition according to Example 2 has a composition containing about 10% by mass (9.99% by mass) of phenol resin.

[0108] (2-1) Observation results of the cured film There were no cracks in the cured film, and the surface was smooth with no irregularities on the surface of the cured film. The evaluation of the cured film was "○" for both.

[0109] (2-2) Room temperature adhesive strength The room temperature adhesive strength was also good at 38.5 N, confirming that the sealing agent composition for the protective film layer had cured sufficiently.

[0110] (3) The cured film according to Comparative Example 1 is a cured product of the above-mentioned bisnadiimide compound vehicle (containing 60% by mass of bisallylnadiimide and 40% by mass of p-tert-butylphenylglycidyl ether).

[0111] (3-1) Observation results of the cured film: "Irregularities on the surface of the cured film" were observed, resulting in a "×" rating, confirming that it is unsuitable for use as a protective film for electronic components.

[0112] (3-2) Room temperature adhesive strength. However, the room temperature adhesive strength was confirmed to be 28.6 N, which is better than that of Example 1 (18.5 N).

[0113] (4) The protective film layer sealing agent compositions of Comparative Examples 2 to 3 have a composition in which imidazole (curing accelerator) is added to the above-mentioned bisnadiimide compound vehicle (containing 60% by mass of bisallylnadiimide and 40% by mass of p-tert-butylphenylglycidyl ether).

[0114] (4-1) Observation results of the cured film Comparative Example 2 was evaluated as "×" because "irregularities on the surface of the cured film" were observed, and Comparative Example 3 was evaluated as "×" because "cracking of the cured film" was observed. Therefore, it is confirmed that the protective film layer encapsulant compositions related to Comparative Examples 2 and 3 are unsuitable for use as protective films for electronic components.

[0115] (4-2) Room Temperature Bonding Strength The room temperature bonding strength of Comparative Example 2 was 22.6 N, and the room temperature bonding strength of Comparative Example 3 was 20.4 N, which is confirmed to be better than that of Example 1 (18.5 N).

[0116] Furthermore, a comparison of Comparative Example 2 and Comparative Example 3 confirms that the room-temperature adhesive strength decreases as the amount of imidazole (curing accelerator) added increases.

[0117] (5) The protective film layer sealing agent compositions of Comparative Examples 4 to 6 have a composition in which imidazole (curing accelerator) and dicyandiamide (curing accelerator) are added to the above-mentioned bisnadiimide compound vehicle (containing 60% by mass of bisallylnadiimide and 40% by mass of p-tert-butylphenylglycidyl ether).

[0118] (5-1) Observation results of the cured film: The evaluations for "cracking of the cured film" and "irregularity of the cured film surface" for comparative examples 4 to 6 are both "○".

[0119] (5-2) Room Temperature Adhesion Strength The room temperature adhesion strength of Comparative Example 4 was 13.3 N, the room temperature adhesion strength of Comparative Example 5 was 6.9 N, and the room temperature adhesion strength of Comparative Example 6 was 3.0 N, which are inferior to Example 1 (18.5 N), and it is confirmed that the encapsulant compositions for protective film layers according to Comparative Examples 4 to 6 are unsuitable for use as protective films for electronic components.

[0120] Furthermore, a comparison of Comparative Examples 4 to 6 confirms that, similar to imidazole (curing accelerator), the room-temperature adhesive strength decreases as the amount of dicyandiamide (curing accelerator) added increases.

[0121] The protective film layer encapsulant composition of the present invention can form a protective film with excellent heat resistance and no surface irregularities, and therefore has industrial applicability as a protective film layer encapsulant composition used in chip electronic components such as chip resistors, chip capacitors, and chip inductors.

Claims

1. A divalent hydrocarbon group (R) is attached to the nitrogen atom of an imide group having a norbornene skeleton. 1 A encapsulant composition for a protective film layer, characterized by comprising: a bisnadiimide compound represented by the following chemical formula 1 to which ) is bonded; a phenol resin; and a reactive diluent having one or more epoxy groups.

2. The above bisnadiimide compound has a monovalent hydrocarbon group (R) on the norbornene skeleton. 2 The protective film layer sealing agent composition according to claim 1, characterized in that it is composed of a bisnadiimide represented by the following chemical formula 2 to which ) is bonded.

3. The protective film layer encapsulant composition according to claim 1 or 2, characterized in that the phenol resin is composed of a novolac-type phenol resin.

4. The protective film layer sealing agent composition according to claim 1 or 2, characterized in that the reactive diluent is composed of a glycidyl ether having one epoxy group.

5. A divalent hydrocarbon group (R) attached to the nitrogen atom of an imide group having a norbornene skeleton. 1 A protective film for electronic components, characterized by being composed of a cured film formed by a curing reaction between a bisnadiimide compound represented by the following chemical formula 1, to which ) is bonded, and a phenolic resin.

6. The above bisnadiimide compound has a monovalent hydrocarbon group (R) on the norbornene skeleton. 2 The protective film for electronic components according to claim 5, characterized in that it is composed of a bisnadiimide represented by the following chemical formula 2 to which ) is bonded.

Images