Datasheet

CAPACITIVE HUMIDITY SENSOR KFS140-MSMD
Released 01/2007 Rights reserved for change in technical data! HYGROSENS INSTRUMENTS GmbH Postfach1054 D-79839 Löffingen Tel: [phone] Fax: [phone]
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Packing
KFS140-SMD Tray of 448 pieces
KFS140-MSMD Tray of 400 pieces
The sensors in the tray are covered with an empty
tray. Care should be taken that the sensors do not
fall out while opening the trays. The sensors are
laid out in the tray in such a manner that the active
surface of the sensor faces downwards.
Storage
The sensors may be stored in the original tray
itself. Storage temperature -20°C ... +50°C. The
shelf life should not exceed 12 months.
Manual soldering
The sensor is not suitable for manual soldering, as
the sensor gets overheated and damaged with
high temperature.
PCB surface
Preferably, the PCB shall be coated with chemical
gold plating or tin plating. The shelf life of PCB
should be followed as per instructions of PCB
manufacturer to ensure proper solderability.
In principle, HAL-tin plated PCBs are also suitable
but care should be taken about the flat surface of
the tinned pads!
Carrier substrate
For carrier substrate, standard materials like FR4
are suitable. The response behaviour of sensor is
affected by the hygroscopic nature of substrate.
This can be avoided by using special carrier
substrate like ISOLA 640 or Roger RO 4003. It can
be processed like FR-4 and has a very low water
absorption property and high temperature
withstanding capability.
Ceramics are also very well suitable for the
purpose of carrier substrate, for example, as thick
layer hybrid.
Landing Pattern
KFS140-MSMD KFS140-SMD
Illustration: Chip geometry of the SMD-Humidity
sensors in µm
It should be ensured that the size and position of
SMD soldering pads are matching with the outer
rectangular part of the connection pad. The pads
should not to be bigger and under no
circumstances, they should go beyond the edge of
the carrier ceramic.
SMD soldering process
The KFS140-SMD can be placed and soldered on
the PCB together with other standard SMD
components as per the usual reflow manufacturing
process. The contact surfaces are of gold or
palladium, which guarantees a good wetting
behaviour.
The sensor is also suitable for vapour phase
soldering, for which the compatibility of sensor
must be checked for the applicable heat transfer
medium. In case of vapour phase soldering, a
boiling point temperature of 230°C is good enough
for most lead free soldering pastes, in order to
ensure proper melting. However, the data of paste
manufacturers should be considered.
Temperature profile
The resulting soldering profile depends on the
soldering paste used and concerned soldering
plant.
The recommended profile should be obtained from
the soldering paste manufacturer. The temperature
profile provided by paste manufacturer is to be
matched with other components used and the
maximum allowable temperature of sensor.
The maximum allowed short time temperature for
the sensor is around 250°C. The peak temperature
of the soldering profile should be maximum 240
°C. Care should be taken that the maximum peak
time of optimum 1 minute to a maximum 2 minutes
is not exceeded.
Illustration: Soldering profile recommended by the
manufacturer Alpha-Metals for paste OMNIX OM
338. For KFS 140, the peak temperature must be
below 240°C at approx. 1-minute peak hold time.