Stock material or miscellaneous articles – Composite – Of silicon containing
Reexamination Certificate
2001-08-17
2003-02-25
Dawson, Robert (Department: 1712)
Stock material or miscellaneous articles
Composite
Of silicon containing
C428S447000, C428S448000, C524S588000, C523S206000, C523S207000, C523S209000, C523S212000
Reexamination Certificate
active
06524717
ABSTRACT:
TECHNICAL FIELD
This invention relates to a prepreg, a metal-clad laminated board and a printed wiring board using these.
BACKGROUND ART
Accompanying with spread of electronic equipment for information terminals such as a personal computer or a cellular telephone, a printed wiring board to be mounted thereon becomes a small size and high density. A form of practically mounting a printed wiring board on an electronic part has progressed from a conventional pin insertion type to a surface mounting type, and in recent years, to an area array type represented by BGA (ball grid array) using a plastic substrate. Of these, in a substrate in which a bare chip is directly mounted as in BGA, it is general to carry out bonding between the chip and the substrate by thermal pressure wire bonding with ultrasonic wave. Thus, a substrate to which a bare chip is mounted is exposed to a high temperature of 150° C. or higher so that it is required to have a predetermined surface hardness at the time of pressure bonding. Moreover, accompanying with high speed processing, an I/O number of MPU (microprocessing unit) is increased whereby a number of terminals to be connected by wire bonding is increased and a width of the terminals becomes narrower. That is, it is required to effect wire bonding connection to an extremely small terminal within a shorter period of time than before so that excellent characteristics which can comply with high speed wire bonding are required for the laminated board to be used therefor. As characteristics of the laminated board to comply with high speed wire bonding, there may be mentioned an excellent surface hardness at high temperatures and an excellent surface smoothness of a substrate containing connecting terminals which are becoming narrower.
As a method of improving surface hardness at high temperatures, there has widely been carried out to improve resin properties by increasing a glass transition temperature (Tg) of a resin, etc. (Japanese Provisional Patent Publication No. 312316/1988). However, there is a limit in the method of raising Tg by making cross-linking density high, and decrease of the surface hardness at the temperature region at Tg or higher is extremely large, whereby it is difficult to comply with a high speed wire bonding which is becoming more severer in the future. Moreover, a resin having a high Tg is generally bulky with a high degree in a resin skeleton, and a shrinkage amount is large due to curing or cooling. Thus, if such a material is employed for a laminated board, unevenness is likely caused at the substrate surface whereby causing the problem of increasing surface roughness.
As a method for improving surface hardness and surface smoothness simultaneously, there is a method of changing woven fabric to be used in a substrate of a metal-clad laminated board. A woven fabric having high modulus of elasticity is effective for improvement of surface hardness, while it is effective to make the state of weave pattern of the woven fabric flatten for improvement of surface smoothness. However, only by the method of changing the woven fabric, it is difficult to improve the surface hardness and the surface smoothness to predetermined levels or more. On the other hand, there is a method of formulating an inorganic filler in the resin composition (Japanese Patent Publication No. 45348/1990). For improving the surface hardness and the surface smoothness according to this method, it is necessary to formulate a predetermined amount or more of an inorganic filler. However, if an amount of the inorganic filler in a resin composition is increased, aggregation of the inorganic filler itself and increase in viscosity of the resin composition occur. In a metal-clad laminated board prepared by impregnating a resin into a substrate and then heating and pressurizing, microvoids or portion to which no resin is impregnated frequently appear whereby causing the problem that heat resistance or insulating property of the metal-clad laminated board is markedly deteriorated thereby.
An object of the present invention is to solve the problems involved in the prior art technique, and to provide a prepreg, a metal-clad laminated board and a printed wiring board using these, which can be applied to a high speed wire bonding, is high in surface hardness at high temperatures and excellent in surface smoothness.
SUMMARY OF THE INVENTION
The present invention relates to a prepreg comprising a substrate and a resin composition containing a resin, an inorganic filler in an amount of 25% by volume based on the total volume of a solid component of the resin composition and a silicone polymer, which resin composition being impregnated into the substrate. A preferred prepreg can be obtained when the inorganic filler has previously been subjected to surface treatment by a silicone polymer or a silicone polymer and a coupling agent. It is more preferred when the resin composition further contains a coupling agent, and a resin composition is such that a resin is formulated in a silicone polymer liquor in which the inorganic filler is dispersed or in a solution containing silicone polymer and a coupling agent. Further, in the present invention, a preferred prepreg can be obtained when the silicone polymer is a three-dimensionally cross-linked polymer; and when the silicone polymer contains in its molecule at least one of a tri-functional siloxane unit represented by the formula: R
1
SiO
3/2
(wherein R
1
represents the same or different organic group) or a tetra-functional siloxane unit represented by the formula: SiO
4/2
; when the silicone polymer contains 15 to 100 mol % of at least one of a tetra-functional siloxane unit and a tri-functional siloxane unit in the molecule based on the total siloxane units, and 0 to 85 mol % of a bi-functional siloxane unit; or when the silicone polymer contains 15 to 100 mol % of a tetra-functional siloxane unit, 0 to 85 mol % of a tri-functional siloxane unit, and 0 to 85 mol % of a bi-functional siloxane unit in the molecule based on the total siloxane units. Moreover, the present invention relates to a metal-clad-laminated board which can be obtained by laminating at least one metal foil on both surfaces or one surface of this prepreg under heating and pressure; a metal-clad-laminated board wherein a surface hardness of the metal-clad-laminated board at a portion containing no metal foil is 30 or more at 200° C. in terms of a Barcol hardness; and a printed wiring board obtained by subjecting the metal-clad-laminating board as mentioned above to circuit processing.
BEST MODE FOR CARRYING OUT THE INVENTION
A kind of the resin to be used in the present invention is not specifically limited, and the resin may preferably include a thermosetting resin and also a thermoplastic resin enriched in heat resistance. Examples of such resins may include an epoxy resin, a polyimide resin, a phenol resin, a melamine resin, a triazine resin, a modified resin of the above-mentioned resins, and the like, and they may be used in combination of two or more kinds. Also, these resins may be dissolved in various kinds of solvents to form a solution and used, if necessary. As a solvent, there may be mentioned, for example, an alcohol type solvent, an ether type solvent, a ketone type solvent, an amide type solvent, an aromatic hydro-carbon type solvent, an ester type solvent, a nitrile type solvent, and the like, and they may be used in admixture of two or more kinds of the solvents. Moreover, various kinds of curing agents, accelerators and the like may be formulated in the resin, if necessary.
As the curing agents, various known curing agents can be used. When an epoxy resin is used, there may be mentioned, for example, an amine compound such as dicyanediamide, diaminodiphenyl methane, diaminodiphenyl sulfone, etc.; an acid anhydride compound such as phthalic anhydride, pyromellitic anhydride, etc.; a polyfunctional phenol compound such as a phenol novolak resin, a cresol novolak resin, etc. These curing agents may be used in combination of two or more kinds. Also,
Fukuda Tomio
Miyatake Masato
Ose Masahisa
Takano Nozomu
Antonelli Terry Stout & Kraus LLP
Dawson Robert
Hitachi Chemical Co. Ltd.
Robertson Jeffrey B.
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