A method of thermally coupling a flow tube or like component to a thermal sensor comprises bonding the component to the thermal sensor such that thermally conductive portions formed on the component are thermally coupled to corresponding sensing/heating elements disposed on the thermal sensor. The method can be employed to form a capillary mass flow sensor system. Thermally conductive portions, such as metal bands, can be formed on the outer surface of a capillary tube for bonding with corresponding resistive heat sensing and heating elements disposed on the substrate of a micro mass flow sensor. Bonding metal pads can be formed on the sensor surface preparatory to solder bonding the tube metal bands to the resistive sensing and heating elements.