www.schurter.co.uk
Protection against thermal runaway
SMD thermal fuse offer a solution to the problem of thermal runaway.
A thermal runaway is an increasing threat
to electronic devices where more and more
power is packed in ever smaller spaces; it
is a threat that is poorly dealt with using
traditional means. SMD thermal fuses o er
a solution that can be re ow-soldered at
260°C and still open at 210°C.
What is meant by a thermal runaway
or the thermal damage of power
semiconductors? A thermal runaway refers
to the overheating of a technical apparatus
due to a self-reinforcing process that
generates heat. is damage usually causes
the destruction of the apparatus and often
leads to a re or explosion.
e causes of a thermal runaway
are varied and often random in nature.
However, the ever-higher power density
in electronic wiring and the trend
towards miniaturisation are of particular
importance. More and more functions
are packed in compact modules, which
then also have a correspondingly high
power consumption. Even slightly
excessive currents in power electronics with
only a little power loss lead to elevated
temperatures of approximately 200°C.
e possible consequences are damage or
disconnection of surrounding components,
damage to the printed circuit board
structure or in the worst case, the triggering
of a re.
With a power semiconductor (e.g.
MOSFET) the drain-source transmission
resistance increases with rising temperatures
when connected, which results in an
increasing loss of power in the barrier layer.
If the elements are not su ciently cooled
- the high power density permits cooling -
the power loss output in the form of heat
can no longer be su ciently dissipated,
which also increases the transmission
resistance. is process escalates and
ultimately leads to destruction of the
component.
How to protect against a short circuit?
e cooling of a system must dissipate
at least as much energy as it is supplied
with. e overcurrent during a thermal
runaway is too low to cause a conventional
fuse to trip. ermal circuit breakers or
PTCs would in principle be used, but
the products available for the assembly
of an SMD printed circuit board are too
complicated or completely unsuitable.
The SCHURTER Solution
SCHURTER has developed and
manufactured the RTS Re ow ermal
Switch. e RTS can be re ow soldered
@ 260°C after which it is mechanically
activated and can still e ectively trip at
210°C. Now available with an integrated
current measuring sensor (Shunt) enabling
precise current measurement. e RTS is
optimised for standard SMD processes like
pick and place other features include:
• High operating current up to 130 A
• High rated voltage 60 VDC
competition is limited to 16 VDC
• Low resistance: 120μOhm
• Very high Breaking Capacity 400A
• https://www.schurter.com/en/
datasheet/RTS
• https://uk.schurter.com/content/
download/2357131/40537784/fi le/
ApplicationNote_ThermalRunaway_
EN.pdf
Thermal Protection
SCHURTER Electronic Components
is a leading innovator and producer
of electronic components. In a
dynamic market the SCHURTER
Group is showing sustainable
growth due to the specialized
competence, innovative capacity,
proximity to customers and fi nancial
independence.
Product ranges
Connectors
Switches
Fuses
EMC
Input Systems
Solutions
Certifi cations
SCHURTER products are certifi ed
according to the following standards
and carry country specifi c approvals:
UL, CSA, VDE (ENEC10), METI,
CCC, KTL
Contact:
If you require further information,
please contact SCHURTER using the
following information.
SCHURTER Electronics Ltd
29 Pembroke Road
Aylesbury
Bucks
HP20 1DB
t: +44 (0)1296 319000
e: uksales@schurter.co.uk
www.schurter.co.uk
Follow us on Social media
@SCHURTER_UK
SCHURTER Electronics Ltd
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