Described are apparatuses for modular printed circuit boards (PCB) and methods for producing modular PCBs. An apparatus may include a first PCB module with a first pattern of routing structures on one or more layers of the first PCB module. The apparatus may further include a second PCB module with a second pattern of routing structures on one or more layers of the second PCB module. The second pattern of routing structures may be aligned with and electrically coupled to the first pattern of routing structures without connectors. Other embodiments may be described and/or claimed.