High Voltage
Planar Resistors
4500 Series
Construction
A high quality alumina substrate is printed with a specially
selected high voltage thick film resistor ink based on a
ruthenium oxide/glass system. A choice of protective systems
is available.
Strength
Welwyn Components
The terminations meet the requirements of
IEC 68.2.21.
Solderability
The terminations meet the requirements of
IEC 115-1, Clause 4.17.3.2
Choice of Protection
As standard components are supplied conformally coated
with an epoxy resin. By special request components can be
supplied unprotected or with a screen printed epoxy
‘handling’ protection.
Marking
Type and protection system references, resistance value
tolerance and manufacturing date code are legend marked.
The resistance value conforms to IEC 62.
Solvent Resistance
The body protection and marking are resistant to all normal
industrial cleaning solvents suitable for printed circuits.
Terminations
Material
Solder coated phosphor bronze leadframe.
Resistors can be supplied without leads, in
which case palladium silver pads enable
electrical connection to be made.
Performance Data
Actual
Maximum
Load at rated power: 1000 hours at 70°C
Shelf life: 12 months at room temperature
Derating
Temperature rapid change
Resistance to solder heat
Voltage coefficient of
Resistance ppm/volt
∆R%
∆R%
4501 and 4502
4503 and 4504
4505, 4506 and 4507
0.1
0.05
5
3
1.5
<3
<2
<1
∆R%
∆R%
Zero at 125°C
Typical
0.3
<0.1
Application Notes
The terminations should not be bent closer than 1.5mm from
the body, and the recommended minimum bend radius is 1mm.
Due to the high voltage which can appear between the resistor
body and any adjacent metal part, resistors should be mounted
at an adequate distance from other conducting parts.
Due to the possibility of surface condensation it is
recommended that high voltages are not applied to resistors
in conditions of high humidity.
Non Standard Optional Features
The options listed below are some of the special features
which may be provided, subject to agreement.
Special substrate size.
Leadless version with palladium silver solder pads.
Special termination length, diameter and pitch.
Special designs for pulse applications.
Resistance value outside stated range.
Tolerance better than ± 1%
Temperature coefficient of ± 50ppm/°C.
Design Flexibility
The experience of Welwyn engineers has been used to design
this generation of high voltage planar resistors to be suitable
for a majority of applications. However, should an application
require particular consideration, Welwyn designers are
available to provide advice and where applicable, to
recommend a non-standard product. Special sizes, designs
etc, can be prototyped at short notice.
Enquiries Welcomed
Packaging
Packed in foam within a box.
© Welwyn Components Limited
Bedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: info@welwyn-tt.com · Website: www.welwyn-tt.com
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Issue B · 03.02
WELWYN [ WELWYN COMPONENTS LIMITED ]
