NOVELTY - A fuel cell assembly comprises a pair of separators each bonded to a frame of an electrolyte layer via a metallic material deposited on a peripheral portion of one of the frame and separator and forming a eutectic with the other of the frame and separator.    USE - As a fuel cell assembly.    ADVANTAGE - Because the frame and separator can be bonded with the eutectic formed by irradiating radiation energy onto the metallic material, there is no need for additional heaters or electrodes. The structure is simplified. Manufacturing cost is minimized. The eutectic bond can provide a high bonding strength, making it possible to bond the separator and the frame of the electrolyte layer with a small area but with sufficient strength that can ensure reliable sealing even if the internal pressure is increased in an operating state of the fuel cell assembly. This can reduce the area of peripheral portion of the separator and the electrolyte layer (frame) to minimize the weight and volume of the fuel cell assembly.    DETAILED DESCRIPTION - A fuel cell assembly comprises: an electrolyte layer (2); a pair of catalyst electrode layers interposing the electrolyte layer; and a pair of separators (5, 6) disposed on either outer side of the pair of catalyst electrode layers. Each separator is formed with a recess in a surface facing an associated catalyst electrode layer, so that a fuel fluid or an oxidizer fluid can flow through the recess to contact the associated catalyst electrode layer. The electrolyte layer comprises a frame (21) and an electrolyte retained in the frame. Each separator is bonded to the frame via a metallic material (27) deposited on a peripheral portion of the one of the frame and separator and forming a eutectic with the other of the frame and separator.    An INDEPENDENT CLAIM is also included for a method for bonding a separator and an electrolyte layer of a fuel cell by depositing a metallic material on one of the frame and separator; and irradiating radiation energy onto the metallic material through the frame or the separator in a state that the frame and the separator contact each other with the metallic material being disposed between them to form a eutectic of the metallic material and the other of the frame and separator.    DESCRIPTION OF DRAWING(S) - The figure shows a partial cross-sectional view of a method for bonding an electrolyte layer and a separator.    Electrolyte layer (2)    Separators (5, 6)    Frame (21)    Silicon nitride film (25)    Metallic material (27)    Titanium layer (28)