Domestic optical modules are more mature in industrialization, mass production, and customer acceptance than photonic chips. Key players: Zhongji Innolight, Accelink Technologies, and Xinyiseng demonstrate strong production capacity and supply chain stability at the module level. The Printed Circuit Board (PCB) at the heart of these modules is no longer a simple substrate but a highly engineered system. Designing and producing these complex PCBs presents formidable challenges, requiring a convergence of disciplines—from high-frequency signal integrity and advanced thermal. Definition: An Optical Module PCB is the internal circuit board of a transceiver (like SFP, QSFP, or OSFP) responsible for converting electrical signals to optical signals and vice versa. Critical Metrics: Signal integrity (insertion loss, return loss) and thermal management are the two. The optical PCB incorporates an optical data transmission layer in its design, achieving higher transfer rates than the traditional board that relies on conductive materials. This article takes you through this PCB's ins and outs, exploring how it works, its advantages over other circuit boards. Optical module circuit boards, also called optical module PCB s, are circuit boards used in optical fiber communication devices.