A jig to be in contact with solder in reflow soldering is coated with diamond-like-carbon on at least a portion which is to be in contact with the solder. In this manner the solder is prevented from adhering to the jig. The diamond-like-carbon coating is preferably provided on the whole surface of the jig facing to the molten solder. In a method for connecting connection members using a jig which can be in contact with solder in reflow soldering, the jig is coated with the diamond-like-carbon on its surface which is likely to contact the solder.