Composition for forming substrate, and prepreg and substrate using the same

A composition for forming a substrate, comprising:

• a liquid crystal thermosetting oligomer having one or more soluble structural units in a main chain thereof and having thermosetting groups at one or more ends of the main chain thereof;
• and
• a metal alkoxide compound having reaction groups which is covalently bondable with the thermosetting groups;
• wherein the liquid crystal thermosetting oligomer is a compound represented by Formula 6 below:
• Z1—(R1)m—(R2)n—Z2 Formula 6
• wherein R1 is one or more structural units selected from among compounds represented by Formula 2 below;
• R2 is one or more structural units selected from among compounds represented by Formula 5 below;
• Z1 and Z2 are identical to or different from each other, and are each independently selected from the group consisting of hydrogen, halogen, a hydroxyl group, maleimide, nadimide, phthalimide, acetylene, propagyl ether, benzocyclobutene, cyanate, and substitution products or derivatives thereof;
• at least one of Z1 and Z2 is selected from the group consisting of maleimide, nadimide, phthalimide, acetylene, propagyl ether, benzocyclobutene, cyanate, and substitution products or derivatives thereof;
• n and m are each independently an integer of 1˜50;
• and n/(n+m+2) is more than 5% to 60% or less:
• wherein Ar is an aryl group of C4˜C30;
• wherein Ar is an aryl group of C4˜C30;
• and wherein the metal alkoxide compound includes a metal selected from the group consisting of Ti, Al, Ge, Co, Ca, Hf, Fe, Ni, Nb, Mo, La, Re, Sc, Si, Ta W, Y, Zr and V.