IXAN0031 - IXYS Corporation

New ISOPLUS247TM Power Package Features 2500V Internal Isolation
Revolutionary Approach Improves Thermal Conductance and Reliability
pability because the thermal expansion coefficient
IXYS Corporation has introduced a new, isoof the silicon die matches that of the DCB;
lated plastic encapsulated package for all types of
6. Small chip-to-heatsink stray capacitance for
discrete power semiconductors, one which promreduced EMI/RFI emissions;
ises to change the way power devices are attached
7.The DCB substrate can be etched like a PC
to heatsinks. The new ISOPLUS247TM has an inboard allowing for more circuit configurations than
ternally isolated mounting tab with a 2500V(RMS)
normally found in a non-isolated TO-247, e.g. epitaxial ultra-fast recovery diodes and Schottky connected common anode or in series, multiple diPlastic housing
Silicon die
odes in series, MOSFET connected in series with
a Schottky diode with or without an antiparallel
The primary advantage of ISOPLUS247 packaging is the very low thermal resistance achievable in
DCB lead frame
a rugged, high voltage, isolated mounting system.
Table 1 compares the thermal resistance of a 55A/
500V MOSFET chip in the ISOPLUS247 package
Figure 1: Cut-away view of the ISOPLUS247 package
(IXFR55N50) to the hole-less TO-247 version
(IXFX55N50) when isolated with various interface
isolation voltage rating. The package meets the stanmaterial. Figure 2 shows the allowable current handard JEDEC TO-247 outline and is intended for
dling capabilities of the various mounting conditions.
pressure mounting applications since there is no
Inspection of this table shows that depending
mounting screw hole. As can be seen in Figure 1,
the usual copper lead frame has been replaced by a upon the mounting technique, allowable output curdirect-copper-bonded (DCB) alumina substrate rent can be increased by about 50% for the same juncpossessing both high thermal conductance and high tion temperature. Conversely, the chip can run up to
29OC cooler for the same operating conditions that
electrical isolation (2500V).
translates into more reliable operation. Because there
There are multiple advantages to this isolated
is such a potentially large decrease in junction-to-case
and hole-less packaging concept.
thermal resistance, it may be possible to use a smaller
1. The dielectric breakdown voltage of the DCB chip for the same current, which would more than
is 6,000V although the package is only rated to cover for the extra price (approximately $0.50 in pro2500V(RMS) due to the creep and strike distances duction volumes) for the internal isolation.
of the TO-247 outline;
IXYS plans on introducing over 100 new part
2. The electrical insulation barrier is plastic encapsulated and therefore protected from the envi- types in this revolutionary package during 1999. Initial product will consist of high power MOSFETs ofronment;
3.Very low, isolated thermal resistance junction- fering the industry’s lowest on-resistance for this packto-heatsink due to the use of DCB and only one age outline. Future product will include IGBTs, IGBTs
non-soldered interface between the silicon chip co-packaged with diodes, and ultra-fast and Schottky
and the heatsink;
4.Ease of assembly due to pressure mounting (no
For more information, contact Mr. Ralph Locher
screws) and no additional isolation interface maat
terial required for mounting to a heatsink;
5.Increased temperature and power cycling ca- © 1999 IXYS Corporation
IXYS Corporation
3540 Bassett St; Santa Clara, CA 95054
Tel: 408-982-0700; Fax: 408-496-0670
IXYS Semiconductor GmbH
Edisonstr. 15; D-68623 Lampertheim, Germany
Tel: +49-6206-503-0; Fax: +49-6206-503627
7M &
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SIL-PAD is a trademark of Bergquist Co.
Table: Performance Comparison of ISOPLUS247 IXFR55N50 to
IXFX55N50 Mounted Using Various Interface Materials
Figure 2: Graphical comparison showing the current handling capability of the ISOPLUS247
IXFR55N50 MOSFET vs the IXFX55N50 MOSFET as a function of heatsink mounting conditions.
7- 2&
IXYS Corporation
3540 Bassett St; Santa Clara, CA 95054
Tel: 408-982-0700; Fax: 408-496-0670
IXYS Semiconductor GmbH
Edisonstr. 15; D-68623 Lampertheim, Germany
Tel: +49-6206-503-0; Fax: +49-6206-503627