Photo-Cross-Linked Acrylate Resins Enabled by Tuning Various Flexible Diamine-Extended Species for High-Performance Printed Circuit Board Coatings

The arrival of the 5G era requires that the solder resist coating of electronic chips involved in high-frequency communication technology has more promising comprehensive properties, including strong mechanical properties, high heat resistance, and voltage breakdown resistance. Herein, an efficient method was proposed to modify bisphenol A diglycidyl ether (DGEBA) with various diamine chain extenders, and five representative chain-extended DGEBA epoxy resins were constructed by introducing aliphatic and aromatic segments. On this basis, the epoxy-terminated resins were reacted with acrylic acid (AA) and then with tetrahydrophthalic anhydride (THPA) to produce photocurable resin with alkaline development. Owing to the high reactivity of amino groups, chain extension with diamines possesses the characteristics of a fast reaction under relatively mild conditions. The characteristic molecular structures (various numbers of rigid benzene rings or flexible aliphatic chains bonded with different numbers of ethers) of diamine profoundly affect the mechanical/thermal properties of the prepared UV-cured resins. The chain extension strategy is the key to striking a balance between high heat resistance and robust mechanical properties for traditional epoxy resins. The optimal UV-cured TPER-modified (P-BA) film manifests superior elongation at break (8.6%), robust toughness (4.1 MJ cm–3), and high heat resistance (Tg = 141.8 °C). Furthermore, the practical application of the modified resin as the customized pattern of the solder resist coating was demonstrated, which is expected to provide important guiding significance for improving the multifunctional bisphenol A UV-curable epoxy resin.