SUBSTRATES AND MOUNTING INFORMATION
The use of epoxy FR4 boards is quite common for
surface mounting techniques, however, their poor
thermal conduction compromises the otherwise
outstanding thermal performanceof the PowerSO-
10. Some methods to overcome this limitation are
discussed below.
One possibility to improve the thermal conduction
is the use of large heat spreader areas at the cop-
per layer of the PC board. This leads to a reduction
of thermal resistance to 35 °C for 6 cm2 of the
board heatsink (see fig. 2).
Use of copper-filled through holes on conventional
FR4 techniques will increase the metallization and
TLPxxM/G/G-1
decrease thermal resistance accordingly. Using
a configurationwith 16 holes under the spreader of
the package with a pitch of 1.8 mm and a diameter
of 0.7 mm, the thermal resistance (junction -
heatsink) can be reduced to 12°C/W (see fig. 3).
Beside the thermal advantage, this solution allows
multi-layer boards to be used. However, a draw-
back of this traditional material prevents its use in
very high power, high current circuits. For instance,
it is not advisable to surface mount devices with
currents greater than 10 A on FR4 boards. A
Power Mosfet or Schottky diode in a surface mount
power package can handle up to around 50 A if
better substrates are used.
Fig. 2 : Mounting on epoxy FR4 head dissipation by extending the area of the copper layer
Copper foil
FR4 board
Fig. 3 : Mounting on epoxy FR4 by using copper-filled through holes for heat transfer
Copper foil
FR4 board
heatsink
heat transfer
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