Study of methoxyphenylquinoxalines (MOPQs) as photoinitiators in the negative photo-resist

To develop photoinitiator systems of high performance for the negative photo-resist, we synthesized six methoxyphenylquinoxalines (MOPQs) and investigated the photopolymerization of 2,2-bis(4-(acryloxypolyethoxy)phenyl)propane (A-BPE-10) initiated by these MOPQs in the negative photo-resist. MOPQs possess suitable UV–vis maximum absorption wavelengths in the range of 349–402 nm, along with high extinction coefficients ɛ. Except for T3MOP-DQ and T4MOP-DQ, the other four MOPQs, D3MOP-Q, D4MOP-Q, D3MOP-BenQ and D4MOP-BenQ, could initiate photopolymerization of A-BPE-10 in the negative photo-resist very efficiently. In particular, D3MOP-BenQ was the most efficient, with almost 100% final conversion in the presence of 2-mercaptobenzothiazole (MBO) as a coinitiator. Among the four coinitiators LCV, MBO, NPG and MDEA, MBO was the best coinitiator for MOPQs. The negative photo-resist containing MOPQs as a photoinitiator can also form good patterns on copper through photolithography. These characteristics make MOPQs potential photoinitiators in the negative photo-resist.