An LED light module assembly for use with high power, high light output LED's includes a thin flexible circuit board with surface mounted LED's and other electronic components which is attached to a metal heat sink using a layer of a thermally conductive adhesive, such as a thermally conductive epoxy adhesive. A conduction path is provided from the LED carrier through the flexible circuit board by the incorporation of one or more thermally conductive vias in the region of the attachment pad used to bond the LED to the flexible circuit board. These vias provide a conduction path from the back side of the LED carrier through the circuit board to the thermally conductive adhesive and heat sink. The LED light module assembly has the capacity to dissipate between about 10-14 W of power without exceeding a maximum LED junction temperature of about 125.degree. C.