Structure for bonding metal plate and piezoelectric body and bonding method

A bonding method in which a metal plate and a piezoelectric body including an electrode provided on a side of the piezoelectric body opposed to the metal plate are bonded to each other using an electrically conductive adhesive including carbon black as an electrically conductive aid, so as to provide electrical conductivity between the metal plate and the electrode of the piezoelectric body, the bonding method comprising the steps of:

• applying the electrically conductive adhesive in a paste form between the metal plate and the electrode of the piezoelectric body, the electrically conductive adhesive including carbon black with a nano-level average particle size, and the electrically conductive adhesive being included in a solventless or solvent-based resin so that the carbon black form an aggregate with an average particle size of about 1 μm to about 50 μm;
• and
• after applying the electrically conductive adhesive, subjecting the metal plate and the piezoelectric body to heating and pressurization to deform the carbon black aggregate, and hardening the electrically conductive adhesive.