Composite sheet and process for producing the same

A composite sheet of given thickness in semi-cured form, comprising a semi-cured binder (B1) and, incorporated therein, a magnetic fibrous filler (A),

• said semi-cured binder (B1) comprising a thermosetting component and a component resulting from curing of a photocuring component,
• said magnetic fibrous filler (A) orientated in the direction of the thickness of the semi-cured composite sheet.

A composite sheet of given thickness in cured form, comprising a binder (B2) and, incorporated therein, a magnetic fibrous filler (A),

• said binder (B2) comprising a component resulting from curing of a thermosetting component and a component resulting from curing of a photocuring component,
• said magnetic fibrous filler (A) orientated in the direction of the thickness of the cured composite sheet.

A process for producing a composite sheet in semi-cured form, comprising the steps of:

• sheeting a composition for composite sheet into a sheet of given thickness, said composition comprising a magnetic fibrous filler (A) and a binder (B), said binder (B) comprising a photocuring component and a thermosetting component, and
• not only applying a magnetic field to the composition sheet in the direction of the thickness of the composition sheet so as to orientate the magnetic fibrous filler (A) in the direction of the thickness of the composition sheet but also curing the photocuring component of the sheeted composition, thereby obtaining a semi-cured composite sheet.

A method of using a composite sheet, said composite sheet being one of given thickness in semi-cured form comprising a semi-cured binder (B1) and, incorporated therein, a magnetic fibrous filler (A), said semi-cured binder (B1) comprising a thermosetting component and a component resulting from curing of a photocuring component, said magnetic fibrous filler (A) orientated in the direction of the thickness of the semi-cured composite sheet,

• which method comprises the steps of:
• interposing the semi-cured composite sheet between an electrode part of a semiconductor element or semiconductor package and a wiring part of a circuit substrate, and
• curing the thermosetting component of the semi-cured composite sheet to thereby convert the semi-cured composite sheet to a cured composite sheet so that the electrode part and the wiring part are electrically connected to each other.

A contact structure comprising an electrode part of a semiconductor element or semiconductor package and a wiring part of a circuit substrate and, interposed therebetween so as to electrically connect them to each other, a composite sheet, said composite sheet being one of given thickness in cured form comprising a binder (B2) and, incorporated therein, a magnetic fibrous filler (A), said binder (B2) comprising a component resulting from curing of a thermosetting component and a component resulting from curing of a photocuring component, said magnetic fibrous filler (A) orientated in the direction of the thickness of the cured composite sheet.

A composite sheet of given thickness comprising a binder and a magnetic fibrous filler (A), said magnetic fibrous filler (A) orientated in the binder in the direction of the thickness of the composite sheet, said orientated magnetic fibrous filler (A) forming a plurality of bundles.

A process for producing a composite sheet, comprising the steps of:

• interposing a sheeted composition of given thickness comprising a magnetic fibrous filler (A) and a thermosetting and/or photocuring binder (B) between a pair of magnetic pole plates each having on its surface projected magnetic pole surface portions, and
• not only applying a magnetic field parallel to the direction of the thickness of the sheet to the sheeted composition so that the magnetic fibrous fillers (A), while being orientated in the direction of the thickness of the sheet, are bundled in the vicinity of projected magnetic pole surface portions of the magnetic pole plates but also curing the binder (B) by heating and/or light irradiation.

A composite sheet of given thickness comprising a binder and a magnetic fibrous filler (A), said magnetic fibrous filler (A) orientated in the binder in the direction of the thickness of the composite sheet, said composite sheet having projections on at least one side thereof.

A process for producing a composite sheet, comprising the steps of:

• bringing at least one side of a sheeted composition of given thickness comprising a magnetic fibrous filler (A) and a thermosetting and/or photocuring binder (B) into contact with a surface of nonmagnetic substance having a plurality of concaves, and
• not only applying a magnetic field parallel to the direction of the thickness of the sheet to the sheeted composition so that the magnetic fibrous filler (A) is orientated in the direction of the thickness of the sheet but also curing the binder (B) by heating and/or light irradiation to thereby obtain a composite sheet having a plurality of projections on at least one side thereof.

A composite sheet of given thickness comprising a magnetic fibrous filler (A), a binder cured by heating and/or light irradiation, and organic fine particles or inorganic fine particles (C), said magnetic fibrous filler (A) orientated in the direction of the thickness of the composite sheet.

A process for producing a composite sheet, comprising the steps of:

• sheeting a composition into a sheet of given thickness, said composition comprising a magnetic fibrous filler (A), a thermosetting and/or photocuring binder (B), and organic fine particles or inorganic fine particles (C), and
• not only applying a magnetic field to the composition sheet in the direction of the thickness of the composition sheet so as to orientate the magnetic fibrous filler (A) in the direction of the thickness of the composition sheet but also curing the binder (B) by heating and/or light irradiation.

A composite sheet of given thickness to be interposed between a semiconductor element and a circuit substrate, comprising a magnetic fibrous filler (A) orientated in the direction of the thickness of the composite sheet, at least 80% of the magnetic fibrous filler (A) having a fiber length L1 satisfying the relationship:

• 0.5×D<L1<(L22+D2)1/2 (I)
• wherein L1 represents a fiber length of magnetic fibrous filler (A), D represents a thickness of composite sheet, and L2 represents a minimum distance between neighboring electrodes among neighboring-electrode distances with respect to electrodes arranged on a semiconductor element on its composite sheet side or neighboring-electrode distances with respect to electrodes arranged on a circuit substrate on its composite sheet side.