FILM AND LAMINATE FOR ELECTRONIC BOARD, AND ELECTRONIC BOARD COMPRISING SAME
A film for an electronic board, according to one embodiment, has a low dielectric constant of 2.9 or lower at a frequency of 10-40 GHz, and thus can cause the signal transmission rate for a high frequency use, such as fifth generation (5G) mobile communication, to be superior to that of a conventional film for an electronic board. In addition, the film for an electronic board has flexibility and physicochemical characteristics that are greater than or equal to those of a conventional film, so as to be applicable to the manufacture of a laminate of a conductive film such as FCCL and an electronic board such as a FPCB, thereby enabling processability, durability, transmission capacity and the like to be improved.
1 . A film for an electronic board, which comprises a polyester resin in which a diol comprising 1,4-cyclohexanedimethanol and an aromatic dicarboxylic acid are polymerized, wherein the film has a dielectric constant of 2.9 or less at a frequency of 10 GHz to 40 GHz.
2 . The film for an electronic board of claim 1 , which has a dielectric constant of 2.9 or less at a frequency of 100 kHz and a temperature ranging from room temperature to 130° C. and a dielectric constant of 2.9 or less at a frequency of 3 GHz to 10 GHz.
3 . The film for an electronic board of claim 2 , which has:
a deviation in the dielectric constant of 0.1 or less at a frequency of 100 kHz and a temperature ranging from room temperature to 100° C.,
a rate of increase in the dielectric constant of 2% to 9% at a frequency of 100 kHz and a temperature of 100° C. to 130° C., and
a deviation in the dielectric constant of 0.2 or more at a frequency of 100 kHz and a temperature of 130° C. to 200° C.
4 . The film for an electronic board of claim 1 , wherein the aromatic dicarboxylic acid comprises isophthalic acid in an amount of 3% by mole to 25% by mole based on the total number of moles of the aromatic dicarboxylic acid, and the polyester resin has an intrinsic viscosity (IV) of 70% to 90% relative to the initial stage after treatment at 121° C. and 100% RH for 96 hours.
5 . The film for an electronic board of claim 1 , which withstands 100 times or more of repeated folding at an angle of 135° until the film is broken and which has a crystallinity of 35% to 55%.
6 . The film for an electronic board of claim 1 , wherein, when a first direction and a second direction perpendicular to each other in a plane are defined, the film for an electronic board has a thermal shrinkage rate (s1) in the first direction of 1% or less, a thermal shrinkage rate (s2) in the second direction of 3% or less, and a ratio (s2/s1) of the thermal shrinkage rate (s2) in the second direction to the thermal shrinkage rate (s1) in the first direction of 1 to 5, under the conditions of 150° C. and 30 minutes.
7 . A laminate for an electronic board, which comprises a substrate layer and a conductive layer disposed on at least one side of the substrate layer, wherein the substrate layer comprises a polyester resin in which a diol comprising 1,4-cyclohexanedimethanol and an aromatic dicarboxylic acid are polymerized, and the substrate layer has a dielectric constant of 2.9 or less at a frequency of 10 GHz to 40 GHz.
8 . The laminate for an electronic board of claim 7 , which comprises a flexible copper clad laminate (FCCL).
9 . An electronic board, which comprises a substrate layer and a conductive pattern layer disposed on at least one side of the substrate layer, wherein the substrate layer comprises a polyester resin in which a diol comprising 1,4-cyclohexanedimethanol and an aromatic dicarboxylic acid are polymerized, and the substrate layer has a dielectric constant of 2.9 or less at a frequency of 10 GHz to 40 GHz.
10 . The electronic board of claim 9 , which comprises a flexible printed circuit board (FPCB).