RBO40 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'RBO40' PDF : 15 Pages View PDF
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 performance of 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
copper 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
RBO40-40G / RBO40-40M / RBO40-40T
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
drawback 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
11/15
®
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