JUMO 906121 User Manual

JUMO GmbH & Co. KG

Delivery address: Mackenrodtstraße 14,

Postal address:
Phone: [phone]
Fax: [phone]
E-mail: [e-mail]
Internet: www.jumo.net

36039 Fulda, Germany
36035 Fulda, Germany

JUMO Instrument Co. Ltd.

JUMO House
Temple Bank, Riverway
Harlow - Essex CM20 2DY, UK
Phone: [phone]
Fax: [phone]
E-mail: [e-mail]
Internet: www.jumo.co.uk

JUMO Process Control, Inc.

8 Technology Boulevard
Canastota, NY 13032, USA
Phone: 315-697-JUMO

1-800-554-JUMO
Fax: [phone]
E-mail: [e-mail]
Internet: www.jumo.us

Application Notes for
Platinum-Chip Temperature Sensors

1 Introduction

Thin-film platinum-chip temperature sensors
from JUMO are basically formed from a
ceramic substrate on which a thinly struc­tured layer of platinum is applied. A glass
layer seals off the platinum layer and thus
protects the temperature sensor to a certain
extent from chemical and mechanical influ­ences.
During subsequent fabrication, the materials
that are used, and the type and method of
the processing, have a decisive effect on the
functionality and long-term stability of the
temperature sensors. In specific cases it may
be necessary to carry out qualification tests
for the selected design, to ensure that techni­cal specifications for measurement accuracy
are met over the temperature range of the
application.
The following application notes have been
put together by JUMO as a result of many
years of experience in processing and han­dling platinum-chip temperature sensors,
and are to be taken as recommendations.

2 Mechanical strength of

the connecting wires

2.1 PCA series

The connecting wires of the temperature sen­sors can be subjected to the maximum ten­sions shown below, without the functionality
being affected. Ensure that the wires are not
loaded laterally. Please refer to the table for
the maximum admissible horizontal tensile
load on one individual wire.

Sensor Connection Tension

LAg-wire 5N
S Pt-Ni sheathed wire 10N
M Pt-Ni sheathed wire 10N
HPd-wire 6N
ENi-wire 6N

If the connecting wires have to be bent, then
care must be taken that the bend is not made
directly at the point where the connecting
wire enters the component sealing. If neces­sary, use a suitable tool to keep the mechani­cal stress away from this point. Continuous
force on the connecting wires, or tight bends
(kinking) must also be avoided, since this not
only increases the resistance (leading to a
systematically higher temperature indication)
but also makes the wires fragile and liable to
break under temperature stress.

2.2 PCKL series

These temperature sensors have terminal
clamps which are soldered on and especially
stiff. It is therefore particularly important that
the connections are not subjected to a side­ways loading during processing. The maxi­mum permissible horizontal tension is 10
newtons per terminal clamp. Bending or kink­ing of the terminal clamps is not permissible.

3 Connection methods

Basically, the connecting wires of the temper­ature sensors can be fabricated with all the
usual connection methods.

These are: soft soldering, brazing, crimping,
resistance welding and laser welding.
In practice, the relevant parameters for a
good connection vary according to the type
of wire used (see data sheet). It is therefore
advisable to make some test welds to obtain
the best results.
During welding or soldering, care must be
taken that there is no concentrated local
heating of the sealing points of the connect­ing wires. If this occurs, the differences in
thermal expansion of the materials can lead
to strains or cracks and thus failure at some
later time. Furthermore, the maximum oper­ating temperature of the temperature sensors
must not be exceeded during handling and
processing. It is recommended that a heat
shunt or similar tool is used to prevent exces­sive heat reaching the temperature sensor via
the connecting wires.
Please also note that the nominal values
given are valid for the standard lengths of
connecting wires, whereby the point of mea­surement is always 2 mm from the open end
of the connecting wires. Alteration to the
length of the connecting wires will therefore
change the resistance. This may have the
result that the tolerance class limits are no
longer met.

4 Mounting and

installation

4.1 Handling

Soft plastic clamps or tweezers should be
used for handling temperature sensors. Metal
pliers or coarse gripping/clamping devices
can cause damage to the temperature sen­sors.

4.2 Potting, coating and gluing

During production processing of platinum­chip temperature sensors, it is important to
avoid any mechanical stresses between the
temperature sensor and the potting com­pound or casting resin, which can arise from
the difference between the coefficients of
thermal expansion of the various materials
that are used. It is therefore advantageous to
use potting compounds that retain some
elasticity after hardening. If not, it cannot be
ruled out that signal shifts may occur, or even
a total failure of the temperature sensor in
extreme cases. Potting compounds and
adhesives should therefore be qualified by
testing before being used for series produc­tion. For instance, we recommend tempera­ture cycling over the intended temperature
range of the application. Care must also be
taken that the potting or coating compounds
provide electrical insulation and are chemi­cally neutral with regard to the temperature
sensor (ceramic substrate material [Al

and various glass materials).
The upper operating limit for the temperature

B 90.6121.4

sensor must also not be exceeded during the
drying/hardening process. When the temper­ature sensor is placed in the protection tube
and positioned, care must be taken that there
is sufficient clearance between the sensor
and the wall of the tube. If the sensor is
skewed or fitted too tightly, it may be dam­aged.

4.3 Surface mounting

Platinum-chip temperature sensors can be
affixed to flat surfaces by using various types
of (SMD) adhesive, or double-sided adhesive
tapes. The usual curing/hardening methods
with UV radiation and/or heat do not create
critical stresses for the sensors. The notes of

4.2 must be observed.

4.4 Unprotected application

The sealing (glass covering) and connecting
wires of the sensors may be damaged if they
are exposed to a corrosive atmosphere,
especially in conjunction with moisture. Plati­num-chip temperature sensors should there­fore not be used in such an environment
without protection.
If bare sensors cannot be avoided, for
instance in HVAC applications, then we rec­ommend using our M series, or sensors that
have been sealed by an additional protective
coating. In this case, it is absolutely vital that
the user carries out an appropriate qualifica­tion test of the functionality and operating
life.

5 Thermal characteristics

5.1 Response times

JUMO measures the response times of the
platinum-chip temperature sensors in agi­tated water with a flow velocity of v = 0.4
meters/second, and the average values are:
t

= 0.2 sec and t

0.5

Subsequent fabrication, such as installation
in a protection tube, will increase the
response times, depending on the nature and
mass of the materials that are used. Care
must therefore be taken to ensure good heat
transfer between the temperature sensor and
the protection tube. Heat-conductive pastes
and alumina powder have proved suitable as
heat-conducting materials.

5.2 Self-heating

In order to measure the electrical resistance,
a current must flow through the temperature
sensor. This current will heat up the tempera­ture sensors by an amount that can be larger
or smaller, depending on external factors.

The size of the resulting error caused by this
self-heating depends on the applied power P

2

= I

x R, the amount of heat that is removed
by the medium being measured, the heat
capacity of the temperature sensor and its
surface. These specific characteristics are
combined in the self-heating coefficient E, so
that the error caused by self-heating is given

2

by ∆t = l

]

2O3

Self-heating coefficients of platinum-chip
temperature sensors are measured in air at v
= 2 m/sec and agitated water at v = 0.2 m/

x R x E.

= 0.4 sec.

0.9

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2009-07-07/00411240

JUMO GmbH & Co. KG

Delivery address: Mackenrodtstraße 14,

Postal address:
Phone: [phone]
Fax: [phone]
E-mail: [e-mail]
Internet: www.jumo.net

36039 Fulda, Germany
36035 Fulda, Germany

JUMO Instrument Co. Ltd.

JUMO House
Temple Bank, Riverway
Harlow - Essex CM20 2DY, UK
Phone: [phone]
Fax: [phone]
E-mail: [e-mail]
Internet: www.jumo.co.uk

JUMO Process Control, Inc.

8 Technology Boulevard
Canastota, NY 13032, USA
Phone: 315-697-JUMO

1-800-554-JUMO
Fax: [phone]
E-mail: [e-mail]
Internet: www.jumo.us

sec. The average coefficients are: in air

0.2°C/mW, in water 0.02°C/mW.
Precise details on items 5.1 and 5.2 can be

found in the appropriate data sheets.

5.3 Measuring current

To avoid self-heating effects and possible
damage to the temperature sensors, we rec­ommend the following maximum currents:

≤ 1.0mA for Pt100 temperature sensors,
≤ 0.7mA for Pt500 temperature sensors, and
≤ 0.1mA for Pt1000 temperature sensors.

6 Cleaning

JUMO temperature sensors come ready­cleaned from the factory. Further cleaning is
not normally required. However, if additional
cleaning operations are necessary during
processing, then the sensors can be cleaned
in baths containing mild cleaning agents,
such as ethanol. A quick cleaning by ultra­sonics is also permissible.

7 Storage

In the (standard) belt packaging, JUMO tem­perature sensors can be stored for several
months in a normal environment. But storage
in a corrosive atmosphere or corrosive
medium or under high-humidity conditions is
not permissible.

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8 Delivered quality

The electrical characteristics of JUMO tem­perature sensors are 100% tested in accor­dance with EN 60 751 during manufacture,
with a measurement uncertainty of 0.030 °C
(95% confidence interval) for the tolerance
classes.
The testing procedure includes the mechani­cal strength of the connecting wires and the
conformity to dimensional tolerances. After
the tolerance selection and cleaning, all
(standard) temperature sensors are individu­ally belt-packaged and stored for dispatch.
High quality, comprehensive information and
fast delivery capability are just a few of the
advantages of using JUMO temperature sen­sors.

2009-07-07/00411240