NOVELTY - An adhesive composition comprises thermoplastic resin, radical-polymerizable compound, radical polymerization initiator and boron-containing salt (I).    USE - Adhesive composition is used for manufacturing bonded structure, and adhesive film for adhesive sheet (all claimed). Uses include but are not limited to connection of liquid crystal display element and tape carrier package, connection of flexible printed circuit board and tape carrier package, connection of tape carrier package and printed wiring board, and connection of flexible printed wiring board and printed wiring board.    ADVANTAGE - The composition has excellent low-temperature curability, storage stability, adhesiveness and connection resistance.    DETAILED DESCRIPTION - An adhesive composition comprises thermoplastic resin, radical-polymerizable compound, radical polymerization initiator and boron-containing salt of formula: R2-B-(-R1)(-R3)-R4.X+ (I).    R1-R4=H, 1-18C alkyl or aryl;and    X+=cation containing quaternary phosphorus atom and/or quaternary nitrogen atom.    INDEPENDENT CLAIMS are included for the following:    (1) adhesive film;    (2) adhesive sheet, which has base material, and adhesive film arranged on the base material;    (3) bonded structure, which has primary circuit component (10) having primary connecting terminal (14) arranged on main surface (12a) of a primary substrate (12), secondary circuit component (20) having secondary connecting terminal (24) arranged on main surface (22a) of a secondary substrate (22), and connection component (30) arranged between primary circuit component and secondary circuit component. The connection component contains cured material of the adhesive composition which electrically connects primary and secondary connecting terminals; and    (4) manufacture of bonded structure, which involves adhering primary circuit component and secondary circuit component in the state at which primary connecting terminal and secondary connecting terminal are electrically connected by hardening the adhesive composition by interposing adhesive composition between primary circuit component and secondary circuit component.    DESCRIPTION OF DRAWING(S) - The drawing shows the cross-sectional schematic view of the bonded structure.    Primary circuit component (10)    Primary substrate (12)    Main surfaces (12a,22a)    Primary connecting terminal (14)    Secondary circuit component (20)    Secondary substrate (22)    Secondary connecting terminal (24)    Connection component (30)