Adamantane-based low-dielectric-constant photocurable resin for 3D printing electronics

In this work, a novel formulation is developed to prepare photocurable polyurethane acrylate (PUA) resin with a low dielectric constant for 3D printing applications. To amend the deficient electronic properties of regular 3D printed PUA materials, a symmetric polymer structure 1,3-adamantanediol (ADO) is introduced into the PUA polymer matrix to effectively decrease the dielectric constant. A low dielectric constant (Dk = 2.26) and a low loss tangent (Df = 0.018) at 10 GHz after formulation, are significantly lower than commercial PCB materials (High Tg FR-4, Dk = 4 and Df = 0.02). The modified PUA also exhibits great mechanical properties (tensile strength 12.02 MPa and elongation break at 111.35%) and can be further metalized with adhesive copper layers (5B adhesion test). With little addition of BN powder (1 wt%), the Df of PUA resin can also be effectively reduced (Df = 0.006), and the measured values of its metalized substrate antenna parameters are proven to be within the acceptable range for 5 G devices. The PUA resin can also be printed into complex 3D structures for 5 G flexible circuit board applications with good design flexibility, and the low dielectric constant provides the opportunity to replace traditional rigid FR-4 substrates for 5 G flexible board applications.