Compounds having the structure of formula I are describedwherein R, R\u2032, R1, R2, and R3 are as defined in the specification. A capacitor dielectric region is formed onto the first capacitor electrode. The guide pin has an enlarged head at a first end thereof which abuts the mounting face of the base to positively limit travel between the die shoe and the die pad, and a shoulder at the opposite or second end thereof with an alignment mechanism that precisely locates the second end of the guide pin on the die pad. The parallel arms are fixed to a vertical elongate guide to which the vacuum cups are slidably fixed, the parallel arms raising and lowering the vacuum cups and maintaining the guide substantially vertical. The recesses provide a flow path for the adhesive to reduce or prevent adhesive encroachment into an air chamber within which an actuator electrode is located. As a result, an undercut engagement portion 19 is formed along the contact faces of both rib strips 14 so that anti-cracking bottom strength of the bottom seal is enhanced.