PURPOSE: To prevent fluidizing of low melting point glass at the time of precedently mounting by altering a melting point of low melting point glass at each lead frame.

CONSTITUTION: A first lead frame is placed on the periphery 21 of a ceramic board 2, heated and secured through a layer 51 coated with paste in which organic solvent is mixed in low melting point glass powder. Then, a second lead frame is disposed between the first lead frames, heated and secured at a temperature lower by several 10°C than that of mounting the first lead frame through a low melting point glass layer 52 having a melting point lower by several 10°C than that of the layer 51. In this case, the layer 51 is not melted by mounting the second lead frame. Thus, irregular mounting of the lead frames can be prevented.