PURPOSE: To decrease thermal resistance in the heat path from the part at which an electronic cooling element is fixed on a dual-in-line package to an external heat sink while increasing heat dissipating properties for improving cooling capacity, by fixing the electronic cooling element on the flange-side inner wall of the package such that the side of the cooling element showing a higher temperature is brought into contact with the package.
CONSTITUTION: A submount 2 is soldered on a stem 6 of a material having high heat conductivity such as copper or copper tungsten, together with a monitoring photodiode 3, an optical coupling ball lens 4 and a thermistor 5. The stem 6 in turn is soldered on an electronic cooling element 7. The electronic cooling element 7 is soldered on an inner wall of a dual-in-line package 9 on which a flange 8 is provided so as to be attached to an external heat sink. Heat generated by the electronic cooling element 9 is conducted through the wall and the flange 8 of the package 9 in the direction of thickness while heat diffusion in involved, and the heat reaches the outer surface of the flange and hence the interface with the external heat sink. Since heat is not conducted to the flange through the bottom plate of the package as would be in case of prior arts, thermal resistance can be decreased significantly.
KONO TSUTOMU
ISOZAKI RYUZO
| JPS62276892A | 1987-12-01 |