A method for manufacturing a board assembly comprises the steps of: tin-plating a first terminal and a copper-made second terminal that are formed on a circuit board; mounting an electronic component on the circuit board by means of gold-tin eutectic bonding between a gold electrode of the electronic component and the tin-plated first terminal; forming a copper-tin alloy on a surface of the second terminal by heating the circuit board after the mounting step; and bonding the second terminal having the copper-tin alloy formed on its surface to a terminal of another board by means of a thermosetting conductive adhesive.