JP2006313660A - Low dielectric constant molding material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low dielectric constant molding material which is a composite material making an insulating mold for an electronic part and having an excellent heat-resistant property withstanding a reflow using a Pb free solder and also a high rigidity and a low dielectric constant. <P>SOLUTION: The low dielectric constant molding material contains a cross-linking material of polyolefin resin having an annular olefin of a glass transition temperature 120°C or less and a storage elastic modulus 0.5 MPa or more at 300°C. Preferably, the same had better contain 5 to 100 pts.wt. of an inorganic filler against 100 pts.wt. of a polyolefin resin additionally. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a molding material for forming an insulating molding used for an electronic component, and relates to a low dielectric constant molding material having high heat resistance and rigidity and low dielectric constant.

  Various properties are required for a molding material for forming an insulating molded body for electronic parts depending on the usage environment and application of the product. For example, molding materials used for surface-mount type terminal connectors are required to have high heat resistance (reflow heat resistance) that can withstand solder reflow temperatures for component mounting, as well as rigidity to ensure pluggability as a connector. . In addition, a molding material for parts used in a high frequency band is required to have a low dielectric constant in order to reduce the problem of signal delay. Therefore, a molding material having a high heat resistance and rigidity and a low dielectric constant is required for a surface mount type terminal connector for a high frequency cable.

  A liquid crystal polymer is known as a material having high heat resistance. Therefore, liquid crystal polymers are often used for surface mount type terminal connectors that require high heat resistance, but liquid crystal polymers have a high dielectric constant, so they should be used for parts used in high frequency bands. I can't.

Examples of the material having a low dielectric constant include polymers of cyclic olefins. It is also known that heat resistance and the like are improved by polymerizing a cyclic olefin (cyclic olefin-based resin) by sulfur crosslinking, organic peroxide crosslinking, electron beam crosslinking, and radiation crosslinking (Japanese Patent Application Laid-Open (JP-A)). Sho 62-34924). However, in recent years, in order to prevent the occurrence of environmental problems, it is desired to use Pb-free solder having a high melting point. Therefore, molding materials for electronic parts are increasingly required to have higher heat resistance. Conventionally, this requirement has been satisfied by a crosslinking reaction under conditions that do not cause deterioration such as resin coloring. It was not possible to obtain a crosslinked product of a cyclic olefin polymer.
JP-A 62-34924

  The present invention is a molding material for forming an insulating molding for electronic parts, has excellent heat resistance that can withstand reflow using Pb-free solder, has high rigidity, and has a low dielectric constant. It is an object to provide a low dielectric constant molding material.

  In general, in order to improve the heat resistance of the resin, it is considered that a higher glass transition temperature of the resin is preferable. However, as a result of studying a crosslinked product of a polyolefin resin obtained from a cyclic olefin, the present inventor has found that when a polyolefin resin obtained from a cyclic olefin has a glass transition temperature of a predetermined temperature or less, crosslinking proceeds. It has been found that heat resistance can be improved without causing problems of resin degradation. Furthermore, by performing the cross-linking so that the storage elastic modulus at high temperature is not less than a predetermined value, it has excellent heat resistance that can withstand reflow using Pb-free solder and is rigid from room temperature to high temperature. The present inventors have found that a low dielectric constant molding material having a high value can be obtained.

  That is, the present invention includes a cross-linked polyolefin resin obtained by polymerizing a monomer containing a cyclic olefin monomer and having a glass transition temperature of 120 ° C. or lower, as an invention for achieving the above-mentioned problems. A low dielectric constant molding material characterized by having a storage elastic modulus at 300 ° C. of 0.5 MPa or more is provided.

  As described above, one of the features of the low dielectric constant molding material of the present invention is that it contains a crosslinked product of a polyolefin resin obtained by polymerizing a monomer containing a cyclic olefin monomer. The cyclic olefin monomer is known from JP-A-8-20692, and preferred examples include cyclopentene, 2-norbornene, and tetracyclododecene monomers. Claim 2 corresponds to this preferable mode.

  Specifically, 2-norbornene, 5-methyl-2-norbornene, 5,5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, 5-butyl-2-norbornene, 5-ethylidene-2-norbornene 5-methoxycarbonyl-2-norbornene, 5-cyano-2-norbornene, 5-methyl-5-methoxycarbonyl-2-norbornene, 5-phenyl-2-norbornene, 5-phenyl-5-methyl-2-norbornene Dicyclopentadiene, 2,3-dihydrodicyclopentadiene, tetracyclo-3-dodecene, 8-methyltetracyclo-3-dodecene, 8-ethyltetracyclo-3-dodecene, 8-hexyltetracyclo-3-dodecene, 2,10-dimethyltetracyclo-3-dodecene, 5,10-dimethyltetra Clo-3-dodecene, 1,4: 5,8-dimethano-1,2,3,4,4a, 5,8,8a-2,3-cyclopentadienonaphthalene, 6-ethyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 1,4: 5,10: 6,9-trimethano-1,2,3,4,4a, 5,5a, 6,9,9a, 10,10a-dodecahydro-2,3-cyclopentadienoanthracene and the like. Furthermore, adducts of cyclopentadiene and tetrahydroindene, and derivatives and substitutes similar to those mentioned above can be mentioned.

The polyolefin resin, which is an essential component of the low dielectric constant molding material of the present invention, can be obtained by polymerizing a monomer containing the cyclic olefin monomer. The monomer to be subjected to the polymerization reaction may contain a monomer other than the cyclic olefin monomer. As the monomer other than the cyclic olefin monomer, a monomer having an unsaturated group copolymerizable with the cyclic olefin monomer is used, specifically,
Ethylene, propylene, 1-butene, 3-methyl-1-butene, 1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1- Α-olefins such as dodecene, 1-tetradecene, 1-hexadecene, 1-icocene;
Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid;
Acrylic acid esters and methacrylic acid esters such as methyl acrylate, ethyl acrylate, hydroxyethyl acrylate, methyl methacrylate, ethyl methacrylate, hydroxyethyl methacrylate;
Unsaturated dicarboxylic acid diesters such as dimethyl maleate, dimethyl fumarate, diethyl itaconate, dimethyl citraconic acid;
Unsaturated carboxylic anhydrides such as maleic anhydride, itaconic anhydride, citraconic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride;
Vinyl alcohol and vinyl esters such as vinyl alcohol and vinyl acetate;
Styrenes such as styrene and α-methylstyrene are exemplified.

  The ratio of the cyclic olefin monomer in the monomer used for the production of the polyolefin-based resin is preferably 10 to 60 mol%, and particularly excellent heat resistance and rigidity are obtained in this range. A more desirable low dielectric constant is achieved. On the other hand, when the ratio of the cyclic olefin monomer exceeds the above range, the glass transition temperature of the polyolefin resin becomes high, so that the crosslinking reaction hardly proceeds.

  Polyolefin resin is, for example, a method of random addition copolymerization of the cyclic olefin monomer and other monomers, or ring-opening polymerization of the cyclic olefin monomer together with other monomers to form a ring-opened polymer. Manufactured by a method of hydrogenation. As the polymerization conditions such as the catalyst and solvent to be used, and the reaction temperature, known conditions described in JP-A-8-20692 can be employed.

  Examples of the polyolefin-based resin thus obtained include resins represented by the following structural formula (1) or (2).

In the formula, R ₁ , R ₂ and X are a hydrogen atom, a hydrocarbon group, or a polar group-substituted hydrocarbon group such as a halogen, a hydroxyl group, an ester group, an alkoxy group, a cyano group, an amide group, an imide group or a silyl group. And they may be the same or different.

In the formula, R _{3 to} R ₁₂ are hydrogen atoms or hydrocarbon groups, X is a hydrogen atom, hydrocarbon group, or halogen, hydroxyl group, ester group, alkoxy group, cyano group, amide group, imide group, silyl group A polar group-substituted hydrocarbon group such as

  One of the characteristics of the present invention is that the polyolefin resin, which is an essential component, has a glass transition temperature of 120 ° C. or lower. When a polyolefin resin containing a cyclic olefin having a glass transition temperature exceeding 120 ° C is used, sufficient crosslinking is not achieved, and as a result, excellent heat resistance that can withstand reflow using Pb-free solder is achieved. Can not do it.

  As a glass transition temperature, the range of 60-100 degreeC is preferable, and the rigidity in the time of the more excellent high temperature can be acquired by setting it as 70-90 degreeC especially. The glass transition temperature is a value obtained from a tan δ peak value obtained at a rate of temperature increase of 10 ° C./min in the viscoelasticity measurement by DVA-200 manufactured by IT Measurement & Control Co., Ltd.

  The cross-linked polyolefin resin is obtained by cross-linking the polyolefin resin. Examples of the crosslinking method include a method using sulfur or an organic peroxide, a method using an electron beam or other radiation, and the like. When sulfur is used, a sulfur compound, a vulcanization accelerator, and a vulcanization accelerator aid are blended into the polyolefin resin and heated to carry out a crosslinking reaction.

  In the case of using an organic peroxide, an organic peroxide is blended with the polyolefin resin, and a crosslinking aid is blended and heated as necessary to carry out a crosslinking reaction. Examples of the organic peroxide include dicumyl peroxide, t-butylcumyl peroxide, 2,5-bis (t-butylperoxy) 2,5-dimethylhexane, 2,5-bis (t-butylperoxy) 2 , 5-dimethylhexyne-3, di-t-butyl peroxide, isopropylcumyl-t-butyl peroxide, dialkyl peroxides such as bis (α-t-butylperoxyisopropyl) benzene or 1,1-bis (t- Butylperoxy) cyclohexane, 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclododecane, n-butyl-4,4-bis (t -Butylperoxy) valerate, ethyl-3,3-bis (t-butylperoxy) butyrate, 3, Peroxyketals such as 3,6,6,9,9-hexamethyl-1,2,4,5, -tetraoxycyclononane; bis (t-butylperoxy) isophthalate, t-butylperoxybenzoate, t-butyl Peroxyesters such as peroxyacetate; t-butyl hydroperoxide, t-hexyl hydroperoxide, cumin hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, diisopropylbenzene hydroperoxide, p-menthane hydroperoxide And hydroperoxides.

  As a method of crosslinking, a method of crosslinking using an electron beam or other radiation is preferable because it does not limit temperature and fluidity during injection molding. Claim 3 corresponds to this preferable mode. Examples of radiation include γ rays in addition to electron beams.

  In both cases of using sulfur, organic peroxides, etc. and crosslinking using radiation, crosslinking is promoted by using a crosslinking aid in combination, and excellent heat resistance and rigidity can be obtained. Therefore, it is preferable. Claim 4 corresponds to this preferred embodiment.

  Examples of crosslinking aids include oximes such as p-quinone dioxime and p, p'-dibenzoylquinone dioxime; ethylene dimethacrylate, polyethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, cyclohexyl methacrylate, acrylic acid / zinc oxide Mixtures, acrylates or methacrylates such as allyl methacrylate; vinyl monomers such as divinylbenzene, vinyltoluene, vinylpyridine; hexamethylene diallyl nadiimide, diallyl itaconate, diallyl phthalate, diallyl isophthalate, diallyl monoglycidyl isocyanurate, triary Allyl compounds such as lucyanurate and triallyl isocyanurate; N, N′-m-phenylenebismaleimide, N, N ′-(4,4′-methylene And maleimide compounds such as diphenylene) dimaleimide. These crosslinking aids may be used alone or in combination.

  One of the characteristics of the low dielectric constant molding material of the present invention is that the storage elastic modulus at 300 ° C. is 0.5 MPa or more. When the storage elastic modulus at 300 ° C. is 0.5 MPa or more, a molding material having satisfactory heat resistance can be obtained, and satisfactory rigidity from room temperature to a high temperature exceeding the reflow temperature can be obtained. Therefore, an excellent molded body can be obtained without causing the problem of thermal deformation even during reflow heating. In order to obtain more excellent heat resistance and rigidity, the storage elastic modulus at 300 ° C. is preferably 1.0 MPa or more.

  Here, the storage elastic modulus is a term constituting a complex elastic modulus representing the relationship between stress and strain when sinusoidal vibrational strain is applied to the viscoelastic body, according to DVA-200 manufactured by IT Measurement & Control Co., Ltd. It is a value measured at a temperature elevation temperature of 10 ° C./min by a viscoelasticity measuring device.

  The low dielectric constant molding material of the present invention thus obtained has a low dielectric constant of about 2.5 to 3.0 together with excellent heat resistance and rigidity. Furthermore, this resin has a feature that it has a small specific gravity and is lightweight, and can contribute to miniaturization and weight reduction of electronic components.

  Furthermore, since the resin obtained from a cyclic olefin monomer is usually a transparent resin, it also has a feature of excellent transparency. Therefore, in the electronic component obtained using the molded body of this low dielectric constant molding material, it is possible to visually check the internal structure and to confirm the defect of the wiring from the outside, and to be excellent in design such as coloring. Features can be obtained.

  In the case of the above polyolefin resin alone, in order to obtain high rigidity (elastic modulus) at high temperature, that is, in order to make the storage elastic modulus at 300 ° C. 0.5 MPa or more, it is necessary to greatly increase the degree of crosslinking. Yes, it is necessary to increase the amount of the crosslinking agent or to increase the irradiation amount of the electron beam or the like. Therefore, preferably, an inorganic filler is added as a reinforcing material in an amount of 5 to 100 parts by weight with respect to 100 parts by weight of the polyolefin resin. Claim 5 corresponds to this preferable mode.

  When the content of the inorganic filler is less than 5 parts by weight, it is necessary to increase the amount of the crosslinking agent or increase the irradiation amount of an electron beam or the like, and in addition to problems such as coloring of the molded body, it becomes brittle. There is a tendency. When content of an inorganic filler exceeds 100 weight part, there exists a tendency for the molded object obtained to become weak.

  Examples of inorganic fillers include inorganic fibers such as glass fibers, basic magnesium sulfate whiskers, zinc oxide whiskers, and potassium titanate whiskers, montmorillonite, and synthetic smectites. Among them, chopped strand glass short fibers having an average fiber length of about 1 to 3 mm are preferably used. Claim 6 corresponds to this preferable mode.

  In general, as an inorganic filler, a short fiber filler has the greatest effect of increasing the elastic modulus, but the same applies when short glass fibers having the above-described size are used. Further, since the short glass fiber is made of glass, the transparency of the molded body can be enhanced. Furthermore, there is no problem that conductivity occurs as in the case of using carbon fiber.

  Especially, when the said glass short fiber is surface-treated with the surface treating agent, affinity with polyolefin resin and glass short fiber increases, and transparency further increases. In particular, the short glass fibers are surface-treated with a surface treatment agent, the cross-linked product of the polyolefin resin is a cross-linked product cross-linked with a cross-linking aid, and the cross-linking aid is the When it has a functional group that reacts with the surface treatment agent, the short glass fiber and the polyolefin resin are chemically bonded through the surface treatment agent and the crosslinking aid, which is preferable because the storage elastic modulus, strength, and transparency are further increased. Claim 7 corresponds to this preferable mode.

  Here, examples of the surface treatment agent include a silane coupling agent having an alkyl chain having an amino group, a glycidyl group, a mercapto group, a vinyl group, an acryloxy group, and a methacryloxy group, and a titanium coupling agent. Moreover, as a crosslinking adjuvant which has a functional group which reacts with a surface treating agent, what has an amino group, a glycidyl group, a hydroxyl group, an isocyanate group, a carboxyl group, and a carbodiimide group is illustrated.

  The low dielectric constant molding material of the present invention is within the range in which the above-described problems of the present invention are achieved, and other components such as an antioxidant, an ultraviolet absorber, a weather resistance stabilizer, a copper damage inhibitor, a flame retardant, A lubricant or the like can be added.

  The low dielectric constant molding material of the present invention is used for forming an insulating molded body used in an electronic component or used as an electronic component, for example, a terminal connector for a high frequency cable or a lens holder such as a DVD. . For example, a uniform mixture of the olefin resin constituting the low dielectric constant molding material of the present invention, an inorganic filler and a crosslinking aid added as necessary is molded by means such as injection molding, and then heated or irradiated with radiation. The low dielectric constant molding material of the present invention can be obtained. Other molding methods include blow molding and transfer molding. The low dielectric constant molding material obtained in this way may be a molding used as it is for electronic parts, but it is further used for electronic parts after being subjected to etching, plating, cutting, painting, polishing, etc. It may be processed into a molded product. Thus, the obtained molded object is excellent in heat resistance and rigidity, and has a low dielectric constant.

  As described in detail above, the low dielectric constant molding material of the present invention has excellent heat resistance that can withstand reflow using Pb-free solder, and has high rigidity (elastic modulus) from room temperature to high temperature. For example, the high insertability required for a connector or the like can also be achieved. Moreover, since the dielectric constant is low, it is applied to electronic parts used in a high frequency band.

  Furthermore, since the low dielectric constant molding material of the present invention also usually has high transparency, by using this low dielectric constant molding material, it is possible to visually check the internal structure and to confirm from outside the wiring defects, In addition, an electronic component having excellent design properties such as coloring can be manufactured. Furthermore, the low dielectric constant molding material of the present invention is lightweight and is preferable for reducing the size and weight of electronic components. Therefore, the low dielectric constant molding material of the present invention can be used in a high temperature environment, and is suitably used for manufacturing electronic parts and the like used in a high frequency band.

  Next, the best mode for carrying out the present invention will be described by way of examples. In addition, this invention is not limited to the form of this Example, The change to another form is also possible unless the meaning of this invention is impaired.

Examples 1-11 and Comparative Examples 1-3
[Polyolefin resin]
As the polyolefin resin, the following commercially available products were used. Each is a resin obtained by polymerizing a monomer containing a cyclic olefin monomer. (1) Appel 8008T and (4) Appel 6015T are represented by the structural formula (2) (cyclic olefin repeating unit). The ratio of Apel 8008T is about 20 mol%, and Apel 6015T is about 40 mol%. (2) Zeonore 750R and (3) Zeonore 1060R are resins represented by the structural formula (1). (5) Topas 8007 is a resin made of a copolymer of ethylene or α-olefin and 2-norbornene.

(1) Appel 8008T: Tg = 70 ° C .: Mitsui Chemicals, Inc. (2) Zeonore 750R: Tg = 70 ° C .: Nippon Zeon Co., Ltd. (3) Zeonore 1060R: Tg = 100 ° C .: Nippon Zeon Co., Ltd. (4 ) Apel 6015T: Tg = 145 ° C .: Mitsui Chemicals Co., Ltd. (5) Topas 8007: Tg = 75 ° C .: Polyplastics Tg: Glass transition temperature

  Glass fibers: ECS03T-289 / PL (aminosilane-treated chopped glass fiber: manufactured by Central Glass Co., Ltd.), Mosheidi A (basic magnesium sulfate whisker: Ube Material Co., Ltd.), Panatetra WZ0501 (Zinc oxide whisker: Matsushita Electric Industrial Co., Ltd.), Tismo N (potassium titanate whisker: Otsuka Chemical Co., Ltd.), Esven NX (Montmorillonite crystal surface modified with quaternary ammonium cations Organic bentonite: manufactured by Nippon Organic Clay Co., Ltd.), phenolic antioxidant: Irganox 1010 (manufactured by Ciba Specialty Chemicals Co., Ltd.), and the following cross-linking aid are blended, and 5 cm x 7 cm x thick by injection molding. Mold a 1mm plate It was.

[Crosslinking aid]
DA-MGIC: diallyl monoglycidyl isocyanurate TAIC: triallyl isocyanurate

  After molding, irradiation was performed with an electron beam having an irradiation amount shown in Tables 1 to 3 to perform crosslinking. Thereafter, the storage elastic modulus (30 ° C., 300 ° C.), reflow heat resistance and dielectric loss were measured by the following method, and the colored state after crosslinking was visually observed. The results are shown in Tables 1 to 3.

[Measurement method]
Storage elastic modulus: Value measured at a temperature rising rate of 10 ° C./min by a viscoelasticity measuring device by DVA-200 manufactured by IT Measurement Control Co., Ltd. Dielectric loss: Dielectric constant and tan δ were measured by a cylindrical cavity resonance method.

  As is clear from the results of Tables 1 to 3, crosslinking is performed by using a polyolefin resin having a glass transition temperature of 120 ° C. or lower and electron beam irradiation under a condition that the storage elastic modulus at 300 ° C. is 0.5 MPa or higher. In Examples 1 to 11, excellent storage elastic modulus and reflow heat resistance were obtained, and the dielectric constant was low. In particular, in Examples 2 to 4 and Examples 6 to 11 in which an inorganic filler such as glass fiber was added using a polyolefin resin having a glass transition temperature of 70 to 75 ° C., a better storage elastic modulus was obtained. Yes.

On the other hand, Reflow heat resistance is low in Comparative Examples 1 and 2 in which the crosslinking under the condition that the storage elastic modulus at 300 ° C. is 0.5 MPa or more is not performed. On the other hand, in Comparative Example 3 using a polyolefin resin having a glass transition temperature exceeding 120 ° C., it is necessary to increase the irradiation amount of electron beam irradiation in order to obtain a sufficient storage elastic modulus and reflow heat resistance at high temperatures. The resin is colored.

Claims (7)

  It is obtained by polymerizing a monomer containing a cyclic olefin monomer, contains a cross-linked polyolefin resin having a glass transition temperature of 120 ° C. or lower, and has a storage elastic modulus at 300 ° C. of 0.5 MPa or higher. Low dielectric constant molding material characterized by   The low dielectric constant molding material according to claim 1, wherein the cyclic olefin monomer has a cyclopentene, 2-norbornene, or tetracyclododecene monomer skeleton.   The low dielectric constant molding material according to claim 1 or 2, wherein the cross-linked product of the polyolefin resin is a cross-linked product by radiation cross-linking.   The low dielectric constant molding material according to any one of claims 1 to 3, wherein the cross-linked product of the polyolefin-based resin is a cross-linked product that has been cross-linked in combination with a cross-linking aid.   Furthermore, 5-100 weight part of inorganic fillers are contained with respect to 100 weight part of the said polyolefin resin, The low dielectric constant molding material in any one of Claim 1 thru | or 4 characterized by the above-mentioned.   The low dielectric constant molding material according to claim 5, wherein the inorganic filler is a short glass fiber. The short glass fiber is surface-treated with a surface treatment agent, the cross-linked product of the polyolefin resin is a cross-linked product obtained by using a cross-linking aid in combination, and the cross-linking aid is the surface treatment agent. The low dielectric constant molding material according to claim 6, which has a functional group that reacts with the low dielectric constant molding material.