<Dual-In-Line Package Intelligent Power Module>
1200V Mini DIPIPM with BSD Series APPLICATION NOTE
Publication Date: September 2015
7
2.1.2 Thermal Resistance
Table 2-1-2 shows the thermal resistance of PSS10S72FT.
Table 2-1-2 Thermal resistance of PSS10S72FT
THERMAL RESISTANCE
Symbol Parameter
Condition
Limits
Unit
Min. Typ. Max.
R
th(j-c)Q
Junction to case thermal
resistance (Note)
Inverter IGBT part (per 1/6 module)
-
-
1.5
K/W
R
th(j-c)F
Inverter FWDi part (per 1/6 module)
-
-
1.8
K/W
Note : Grease with good thermal conductivity and long-term endurance should be applied evenly with about +100
μ
m~+200
μ
m on the contacting surface of
DIPIPM and heat sink. The contacting thermal resistance between DIPIPM case and heat sink Rth(c-f) is determined by the thickness and the thermal
conductivity of the applied grease. For reference, Rth(c-f) is about 0.3K/W (per 1/6 module, grease thickness: 20
μ
m, thermal conductivity: 1.0W/m•k).
The above data shows the thermal resistance between chip junction and case at steady state. The thermal
resistance goes into saturation in about 10 seconds. The unsaturated thermal resistance is called as
transient thermal impedance which is shown in Fig.2-1-3. Zth(j-c)* is the normalized value of the transient
thermal impedance. (Zth(j-c)*= Zth(j-c) / Rth(j-c)max)
For example, the IGBT transient thermal impedance of PSS10S72FT in 0.2s is 1.61×0.8=1.288K/W.
The transient thermal impedance isn’t used for constantly current, but for short period current (ms order).
(e.g. in the cases at motor starting, at motor lock
･･･
)
0.1
1.0
0.01
0.1
1
10
Nor
m
aliz
ed t
h
e
rm
al i
m
p
edan
ce
Z
th
(j
-c
)
Time(s)
FWDi
IGBT
Fig.2-1-3 Typical transient thermal impedance (PSSxxS72FT)
