Comparison pastes / foils / DCB / IMS - Zth Messtechnik - transient thermal impedance of power semiconductors - thermal-electrical simulation

Your partner for thermal impedance measurement of power semiconductors
Zth-Messtechnik Kiffe
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Comparison pastes / foils / DCB / IMS

Example
Thermally conductive pastes, thermal conductive foils, ceramic substrates (DCB) or insulated metal substrates (IMS) are used to reduce the thermal resistance
between power semiconductors and heat sink. Of these interface materials, there is a broad spectrum with very different properties up to electrical insulation.
An exact calculation of the chip temperature with a thermal model based on the data sheet values ​​is almost impossible since influences such as surface structure,
pressure, flow or wettability are missing. The developer only has the option to integrate the interface material into its own structure and to measure thermally
(Zth-measurement).

Using the Zth-measurement technique, the following comparison shows the transient temperature profile of an IGBT for different materials between chip and
water cooled heat sink with a power loss of 30W and a contact pressure of 100N (IGBT Rthjc=0,28K/W).


Experimental setup:



Measurement results:


interface material
construction
characteristics
heat conduction    thermal resistance manufacturer
thermal resistance IGBT against closed water cooling
thermisches Klebeband 1
thermal adhesive tape 1
thickness: 0,30mm
dielectric strength: 6kV
1,4W/mK
0,52K/W
2,155K/W
thermisches Klebeband 2
thermal adhesive tape 2
thickness: 0,25mm
dielectric strength: 6kV
1,0W/mK
1,898K/W
Luft
air

0,024W/mK
1,508K/W
Wärmeleitfolie 1
heat conducting foil 1
silicone-free
thickness: 0,20mm
dielectric strength: 4kV
6W/mK
0,09K/W
1,283K/W
Wärmeleitfolie 2
heat conducting foil 2
silicone with ceramic filling
fiberglass tissue
thickness: 0,20mm
dielectric strength: 3kV
5W/mK
1,099K/W
Standard-IMS
standard-IMS
cu-thickness above:35µm
thickness Dielektrikum: 100µm
alu-thickness below: 1,50mm
dielectric strength: 3kV
1,3W/mK (dielectric)
1,2K/W (dielectric)
1,080K/W
Grafitfolie
graphite foil
highly compressed graphite foil
thickness 0,29mm
not insulating
7,5W/mK
0,08K/W
0,973K/W
Ethanol
ethanol

0,2W/mK
0,821K/W
Hochleistungs-IMS
high-performance-IMS
cu-thickness above: 105µm
thickness Dielektrikum: 75µm
cu-thickness below: 1,55mm
dielectric strength: 6kV
4,1W/mK
0,45K/W
0,760K/W
Al2O3-DCB
Al2O3-DCB
cu-thickness above: 0,30mm
thickness Al2O3: 0,65mm
cu-thickness below: 0,30mm
dielectric strength: ~ 8.5kV
~ 28W/mK
0,752K/W
Wärmeleitpaste 1
thermal compounds 1
silicone-free
thickness: ~50µm
not insulating
0,5W/mK
0,705K/W
AIN-DCB
AIN-DCB
cu-thickness above: 0,225mm
thickness AIN: 0,65mm
cu-thickness below: 0,225mm
dielectric strength: ~ 8,5kV
> 180W/mK
0,645K/W
Wasser (destilliert)
water (distilled)

0,6W/mK
0,628K/W
Wärmeleitpaste 2
thermal compounds 2
silicone-free
thickness: ~50µm
not insulating
10W/mK
0,006K/W bei 30µm
0,563K/W
Wärmeleitpaste 3
thermal compounds 3
99,9% silver
thickness: ~50µm
not electrically conductive
9W/mK
0,553K/W
Hochleistungs-Silikonfolie
high-performance-silicone foil
graphite filled silicone
thickness: 0,20mm
not insulating
50W/mK
0,545K/W
Transient temperature profile for various interface materials between IGBT and water heat sink after shutdown t=0s, Pv=30W.

*least. water as a solder substitute between IGBT and interface material; least. Water as heat-conducting layer between interface material and water heat sink.



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