Process for producing two-layered tape for tab

A process for producing a two-layered tape for TAB, which is characterized by forming desired holes in a semi-cured polyamic acid film subjected to stretching of 10% or more, then laminating the film to a conductor foil, completing imidization, and thereafter forming a desired pattern in the conductor foil.

A process for producing a two-layered tape for TAB, which is characterized by forming desired holes in a semi-cured polyamic acid film formed on a release film, then laminating the polyamic acid film having said holes and the release film to a conductor foil so that the polyamic acid film having said holes is brought in contact with the conductor foil, peeling off the release film, completing imidization, and forming a desired pattern in the conductor foil.

A process for producing a flexible printed circuit board with a cover layer film, comprising the steps of forming desired holes in a stretched polyamic acid film, which is prepared by coating a polyamic acid solution on a release film or a release drum, drying the coated solution until it becomes tack-free to form a polyamic acid film, then peeling off the polyamic acid film from the release film or the release drum, and subjecting the polyamic acid film to stretching of 10% or more, to prepare a cover layer film;

• pressure-bonding the cover layer film to a two-layered flexible printed circuit board having no adhesive layer, one of the layers being a polyimide layer;
• and then completing imidization.

A process for producing a semi-cured stretched polyamic acid film, which is characterized by bringing in a contiguous relation two or more polyamic acid films of same or different compositions so that they face each other, simultaneously bonding them under heat and pressure to obtain a thick polyamic acid film, and then subjecting the polyamic acid film to stretching of 10% or more.

A process for producing a two-layered tape for TAB whose supporting film layer has different thicknesses depending upon the portions and has a lower sub-layer made of a light-transmittable polyimide having a yellowness index of 30 or less, which process is characterized by bonding, under heat and pressure, a semi-cured light-transmittable polyamic acid film having a yellowness index of 30 or less formed on a conductor foil and a semi-cured polyamic acid film with desired holes formed on a release film so that the two polyamic acid films contact with each other, peeling off the release film, then completing imidization, and thereafter forming a desired pattern in the conductor foil.

A process for producing a two-layered tape for TAB whose supporting film layer has different thicknesses depending upon the portions and has a lower sub-layer made of a light-transmittable polyimide, which process is characterized by bonding, under heat and pressure, a semi-cured light-transmittable polyamic acid film formed on a conductor foil and a semi-cured polyamic acid film with desired holes formed on a release film so that the two polyamic acid films contact with each other, peeling off the release film, then completing imidization, and thereafter forming a desired pattern in the conductor foil;

• the polyamic acid film with holes being formed by use of a varnish obtained by mixing (A) a polyamic acid solution obtained by reacting 3,3',4,4'-biphenyltetracarboxylic acid dianhydride and p-phenylenediamine with (B) a polyamic acid solution obtained by reacting pyromellitic acid dianhydride with 4,4'-diaminodiphenyl ether, at a solid content ratio of A/B=55/45 to 75/25.