An underfill composition includes a thermosetting resin and a thermally cleavable component that releases sulfonic acid upon thermal activation. The underfill composition is applied to flip-chip technology during no-flow underfill mounting of the flip-chip to a mounting substrate. The mounting substrate can be further mounted on a board. A process includes formation of the underfill composition. A method includes assembly of the underfill composition with the flip-chip, and further can include assembly of the mounting substrate to a board. A computing system is also included that uses the underfill composition.