CURABLE COMPOSITION AND INSULATING FILM
The present disclosure provides a curable composition comprising: (A) copolymer with at least one reactive group; (B) crosslinker; (C) polymerization initiator; and (D) boron nitride. The present disclosure also provides an insulating film comprising the aforementioned curable composition, which are particularly suited for manufacturing printed circuit boards (PCBs). The insulating film exhibit excellent electrical properties, including low dissipation factor (Df) and a low coefficient of thermal expansion (CTE). Furthermore, the insulating film provides significant advantages in reducing the production time in PCB manufacturing processes that involve a plasma etching step.
1 . A curable composition, comprising:
100 parts by weight of a copolymer (A) with at least one reactive group;
250-350 parts by weight of a crosslinker (B);
0.5-6 parts by weight of a polymerization initiator (C);
50-900 parts by weight of boron nitride (D) having a median particle size of 10 μm or less.
2 . The curable composition of claim 1 , wherein the copolymer (A) is derived from a composition comprising a C2-8 olefin (a-1), a C6-20 aromatic vinyl compound (a-2), and a C10-20 aromatic polyene (a-3).
3 . The curable composition of claim 2 , wherein the copolymer (A) is derived from a composition comprising 10-70 wt % of the C2-8 olefin (a-1), 10-60 wt % of the C6-20 aromatic vinyl compound (a-2), and 1-30 wt % of the C10-20 aromatic polyene (a-3) based on the total weight of the copolymer is 100 wt %.
4 . The curable composition of claim 1 , wherein the copolymer (A) has a number average molecular weight (Mn) of 15,000 to 100,000 and a number of the reactive group per Mn of 1 to 10.
5 . The curable composition of claim 1 , wherein the crosslinker (B) has at least one functional group selected from the group consisting of a maleimide group, an aromatic vinyl group, an aliphatic vinyl group, a cycloaliphatic vinyl group, an acrylate group, a (meth)acrylate group, and combinations thereof.
6 . The curable composition of claim 1 , wherein the polymerization initiator (C) is selected from 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, 2,3-dimethyl-2,3-diphenylbutane, 1-bis(t-butylperoxy)-3, 3, 5-trimethylcyclohexane, benzoyl peroxide, lauroyl peroxide, di-t-butyl peroxide, di-(2-t-butylperoxyisopropyl)benzene, dicumyl peroxide, t-butyl peroxybenzoate, t-butyl peroxypivalate, methyl ethyl ketone peroxide, cyclohexanone peroxide, diisopropyl peroxydicarbonate, dicyclohexyl peroxycarbonate, and combinations thereof.
7 . The curable composition of claim 1 , wherein the curable composition further comprises an additive (E), and the additive (E) is selected from the group consisting of an adhesion promoter, an antioxidant, a colorant, a defoamer, a flame retardant, a polymerization inhibitor, a thickener, a solvent, and combinations thereof.
8 . The curable composition of claim 7 , wherein the additive (E) is a solvent comprising cyclohexanone, cyclopentanone, isophorone, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, naphtha solvent of boiling point between 100° C. to 200° C., or combinations thereof.
9 . An insulating film for fabricating a printed circuit board, comprising sequentially:
a support film,
a resin layer composed of the curable composition of claim 1 , and
a protective film,
wherein the resin layer has a thickness of 10 μm to 60 μm.
10 . The insulating film of claim 9 , wherein the support film and the protective film are each independently composed of a polymeric material selected from the group consisting of polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, and polyimide.
11 . The insulating film of claim 9 , wherein the support film is a metallic foil selected from the group consisting of Au, Ag, Cu, Al, and alloys thereof.
12 . The insulating film of claim 9 , wherein the resin layer after curing has a dissipation factor (Df) of 0.003 or less when measured at 10 GHz and 23° C., and the curing is conducted at 100° C. to 250° C. for 60 minutes to 240 minutes.
13 . The insulating film of claim 9 , wherein the resin layer after curing has a coefficient of thermal expansion (CTE) of 70 ppm/K or less between 30° C. to 120° C., and the curing is conducted at 100° C. to 250° C. for 60 minutes to 240 minutes.
14 . The insulating film of claim 9 , wherein the resin layer after curing has a plasma etching rate of 0.4 μm/min or more, and the plasma etching is performed under a chamber pressure of 2 Pa (15 mtorr) by applying a radiofrequency (RF) power of 13.56 MHz, an ignition power of 8000 Watts, a DC bias of 5000 Watts with a gas mixture of oxygen, tetrafluoromethane (carbon tetrafluoride, CF 4 ) and nitrogen at a ratio of 2:2:1, at a flow rate of 1250 mL/sec for 30 minutes, and the curing is conducted at 100° C. to 250° C. for 60 minutes to 240 minutes.
15 . A printed circuit board, comprising an insulating layer that is a cured product of the curable composition of claim 1 .
16 . The printed circuit board of claim 15 , wherein the circuit is fabricated by a method comprising a plasma etching step for via and/or trench formation.