In a solder reflow type building of modular electrical apparatus involving integrated circuit and discrete components, fabrication operations are arranged to include the providing of a general type series of steps for each component element involving a reflow or joining step at the highest joining temperature, immediately followed by a solder flux cleaning step and immediately followed by a testing of the entire module constructed thus far. There is provided a further specific type operation for each different type of component element that includes the providing of a loop for the introduction of a replacement for any broken discrete component with joining being achieved with use of a lower fusion temperature solder, flux cleaning and testing at each joining followed by reinsertion into the module. There is further provided an operation at the encapsulation stage of the module building for introducing underfill between the component and supporting carrier.