| abstract |
The maximum length of the heat sink is denoted by L, the amount of warpage of the heat sink is denoted by Z, and the amount of warping Z by the deformation in which the joint surface of the heat sink with respect to the metal layer is concave is defined as a convex shape When the ratio Z / L of the maximum length L and the bending amount Z measured at 25 占 폚 in the range of -0.005 to 0.005 inclusive and the bending amount Z is minus, and when heated to 280 占 폚 and after heating, When cooled, the ratio Z / L is in the range of -0.005 to 0.005. |