Foamable resin composition

A foamable resin composition, comprising:

• a urethane (meth) acrylate oligomer having an inclusion quantity from 20 to 90 parts by weight;
• a photoinitiator having an inclusion quantity from 0.1 to 10 parts by weight;
• a heat-expandable microcapsule having an inclusion quantity from 1 to 25 parts by weight;
• and
• a photopolymerizable monomer having an inclusion quantity from 10 to 45 parts by weight, wherein the photopolymerizable monomer comprises at least one compound with chemical formula R-Xa, having a group of a reactive functional group X and a non-reactive functional group R, wherein the non-reactive functional group R is selected from a group consisting of a small molecule group, a group with steric hindrance, a group with side reaction sites, and a long chain group, a weight ratio of the urethane (meth) acrylate oligomer and the photopolymerizable monomer in the foamable resin composition is from 1.5:1 to 2.5:1.