ATPAK Idea for Improving Heat Radiation

AND9295/D
ATPAK
Idea for Improving Heat Radiation
1. Overview
This application note is to discuss that ON
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Semiconductor’s original ATPAK package is
superior to DPAK (TO-252) in heat dissipation
APPLICATION NOTE
by using heat sink and measuring actual
thermal resistance.
However, this paper is not any guarantee for 3. Channel Temperature
operation. Installation of heat sink is on your
Power MOS Max. Power Dissipation (PD max)
own responsibility.
is calculated as follows:
2. Thermal Resistance
Thermal resistance is the coefficient that
indicates to what extent the temperature
increases to an object when applying 1W heat
to it. Its unit is C/W. it is common that, the
lower the thermal resistance is, the better the
heat dissipation performance is.
Thermal design model that uses a heat sink can
be shown by an equivalent circuit of series
resistors (see Figure 1).
In case of Surface Mount type packages like
ATPAK and DPAK, because the heat dissipates
almost
to
the
underneath
substrate,
measurement of Case Temperature (RJC) is
difficult. So, in this test, we evaluated the
superiority of heat dissipation from surface by
relatively comparing in the substrates with the
same copper foil area.
PD max =
Tch max - Ta
(1)
RJA
Tch = RJA x PD + Ta
(2)
Channel Temperature (Tch) can be calculated
from the ambient temperature and power
consumption. It is recommended that Tch is
designed to be about 80% of the allowable
maximum temperature (Tch max).
Ta
RHS
Heat Sink
Ts
Grease
Thermal resistance of heat sink
RGR
Case
Tc
Channel
Thermal resistance of grease
RJC
Substrate
Thermal resistance of the case
RJA = RJC + RGR + RHS
Tch
Figure 1. Thermal Resistance Model
© Semiconductor Components Industries, LLC, 2016
February 2016- Rev. 1
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Publication Order Number:
AND9295/D
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5. Initial comparison of thermal resistance
4. Spec. Comparison
Table 1 shows the performance comparison
between
ON
Semiconductor’s
ATPAK
(ATP113) and other company’s DPAK. You
can see from the table that devices with
identical performance were selected as much
as possible in order that the heat dissipation of
the package can be compared relatively.
As previously stated, we selected ATPAK and
DPAK devices with almost identical spec., and
measured their actual thermal resistance and
made comparison. For the measurement, we
used glass-epoxy substrates with the same
copper foil area of 1.0x1.0inch (Figure 2).
ATPAK and DPAK have almost the same footpattern, so completely the same substrate can
be used.
Table 1. Spec comparison between ATPAK and DPAK
Parameter
Symbol
Condition
Value
Unit
ATPAK
DPAK
Drain-Source Voltage
VDSS
-60
-60
V
Gate-Source Voltage
VGSS
±20
±20
V
Drain Current
ID
-35
-36
A
Drain Current(PW)
IDP
PW ≤ 10us,Duty ≤ 1%
-105
-108
A
Allowable Power Dissipation
PD
Tc = 25C
50
56
W
Channel Temperature
Tch
150
175
C
Zero Gate Voltage Drain Current
IDSS
Vds=-60V,Vgs=0V
-1
-10
uA
Gate Leakage Current
IGSS
Vgs=16V,Vds=0V
±10
±10
uA
Gate-Source Cut-off Voltage
VGS(off)
Vds=-10V,Id=-1mA
-2.6
-2.5
V
Drain-Source On-state Resistance
RDS(on)
Vgs=-10V,Id=-18A
29.5
30
m
Chip Size
same-size
Package
6.5x9.5x2.3
ATPAK
DPAK
Figure 2. Actual Evaluation Board
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2
6.5x9.8x1.5
mm
mm
AND9295/D
Figure 3 shows the transient thermal resistance
measurements. You can see from the graph
that thermal resistance (RJA) of either ATPAK
or DPAK is 80.3C/W, the same results are
obtained, so there is no difference in the heat
dissipation.
6. Comparison of heat resistance using
the heat sink
For ATPAK and DPAK selected and measured
previously, we applied silicon grease on the
surfaces of both packages and measured
thermal resistances with heat sink mounted
(Figure 4). Detail of the heat sink is shown in
Figure 5.
Figure 3. Transient Thermal Resistance
ATPAK
DPAK
Figure 4. Actual Evaluation Board with Heat Sink
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AND9295/D
Figure 6 shows the measurements of
transient thermal resistance.
For DPAK, thermal resistance (RJA) is
62.5C/W; for ATPAK, it is 56.4C/W.
The result shows that, even though the two
packages have the same thermal resistance
under the condition of no heatsink, by using
heatsink, the thermal resistance of ATPAK
becomes 6C/W lower than that of DPAK.
7. Summary
This test suggests that ON Semi’s original
ATPAK package shows more possibility of
lowering the inside semiconductor chip
(die) even than DPAK package in case of
using heatsink due to its good heat
dissipation from the surface.
Therefore,
ATPAK
can
support
applications with high heat dissipation by
using heatsink.
12.5
Maker : Fischer Elektronik
Part No. : ICKS 10x10x12.5
Thermal Resistance : 26.3KW
10
10
2
[mm]
Figure 5 Specification of Heat Sink
Figure 6 Transient Thermal Resistance with Heat Sink
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AND9295/D
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