What are Box Build Assemblies in Electronics Manufacturing? Box build assemblies take electronics manufacturing beyond the circuit board. They bring together fully assembled PCBAs, wiring, enclosures, sub-panels, firmware loading, and functional testing into one finished. This process refers to the entire process of installing the already assembled PCB into the product shell and completing the internal cable connection, module integration, functional testing, and overall packaging. That is to say, box build is responsible for turning the electronic functional. Customized Box Build Assembly Solutions and Superior Customer Service.