Fabrication of plastic module with exposed backside contact

This invention relates to fabrication of high-density interconnect (HDI) electric or electronic modules, and more particularly to arrangements for encapsulating the components of modules in which at least one of the components requires connections to the "back" side opposite to that side of the component bearing an array of electrical connection pads. A chip-on-flex HDI module is fabricated by dispensing encapsulant material onto the components of a populated dielectric film or sheet in an interrupted pattern which leaves the backsides of selected components free of encapsulant. The dispensing is accomplished by relative motion of the dispenser tip and the populated film, with the dispenser tip at a height slightly above the desired liquid fill height during dispensing. At the locations of the components which are to be free of encapsulant, the dispensing stops, and the tip may be raised to prevent residual viscous matter on the dispenser tip from contacting the backside of the exposed component.