The present invention provides a voltage resonant converter that achieves ZVS over the entire allowable load range. In the formula : Nr1 represents a substituted or unsubstituted monocyclic nitrogen-containing aromatic ring having 2 to 5 ring carbon atoms, or a bicyclic nitrogen-containing aromatic ring having 2 to 9 ring carbon atoms; Ar represents an aromatic ring and the like; Fl1 and Fl2 represent a fluorenyl group; and Cz1 and Cz2 represent a carbazolyl group. First and second U-shaped clips are interfaced with the first and second sidewall members and have guide holes, wherein at least one clip has tapered guide holes.