27 b is triangular the flow of the resin is as good as that in fig3 a a to fig3 a c and it is possible to secure a stable productivity and yield fig4 a is a cross sectional view showing a semiconductor device according to embodiment 4 and fig4 b is a bottom view of the same fig4 a shows a cross section taken along the line g g in fig4 b fig4 c is a bottom view of a heat sink plate 28 constituting the semiconductor device in this embodiment the heat sink plate 28 has a flat configuration without a protruding portion at the central portion thereof the semiconductor chip 1 is bonded by ag paste on the central portion of the heat sink plate 28 whose upper surface is flat in this case it is not necessary to form a protruding portion or a supporting portion that holds the protruding portion unlike in the embodiments described above as a result the external appearance of the exposed portion of the heat sink plate 28 on the lower surface of the semiconductor device is such that only heat releasing terminals 28 b are disposed on a half etched portion 28 a as shown in fig4 c since the exposed metal portions can be reduced to the extent possible it is possible to secure a higher degree of freedom in board wiring fig5 a a is a cross sectional view showing a semiconductor device according to embodiment 5 and fig5 a b is a bottom view of the same fig5 a a shows a cross section taken along the line h h in fig5 a b fig5 a c is a bottom view of a heat sink plate 29 constituting the semiconductor device.