High Voltage
Chip Resistors
HVC Series
© 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 Issue C · 10.03
Welwyn Components
85
Maximum Typical
Load at rated power: 1000 hours at 70°C ∆R% 0.5 0.25
Shelf life test: 12 months at room temperature ∆R% 0.1 0.02
Derating from rated power at 70°C Zero at 155°C
Short term overload: Lesser of 6.25 x rated power or 1.5 x LEV for 2S ∆R% 0.5 0.1
Dry heat: 1000 hours at 155°C ∆R% 0.5 0.2
Long term damp heat ∆R% 0.5 0.25
Temperature rapid change ∆R% 0.25 0.05
Resistance to solder heat ∆R% 0.25 0.05
Voltage proof Volts 500
Voltage coefficient of resistance ppm/V 1206: -25 1206: -15
2010: -15 2010: -5
2512: -5 2512: -1.5
Performance Data
Application Notes
Construction
Resistive thick film material, overglaze and organic protection
are screen printed on a 96% alumina substrate. The design
and laser adjustment of the resistive element optimises the
limiting element voltage of the resistor.
Terminations
The chips are supplied with wrap-around terminations suitable
for soldering. Consult factory for alternative termination
options.
Solderability
The terminations have an electroplated nickel barrier and
tin-lead solder coating, and this ensures excellent ‘leach’
resistance properties and solderability.
Marking
The body protection is resistant to all normal cleaning solvents
suitable for printed circuits.
The chips are not marked and the relevant information type,
value, tolerance date code and quantity are recorded on the reel.
HVC resistors are ideally suited for handling by automatic
methods due to their rectangular shape and the small
dimensional tolerances. Electrical connection to a ceramic
substrate or to a printed circuit board can be made by reflow
or wave soldering of wrap-around terminations.
Wrap-around terminations provide good leach properties and
ensure reliable contact. Due to the robust construction, the
HVC can be immersed in the solder bath for 30 seconds at
260°C. This enables the resistor to be mounted on one side
of a printed circuit board and wire-leaded components
applied on the other side.
HVC resistors themselves can operate at a maximum
temperature of 155°C (see performance above). For soldered
resistors, the joint temperature should not exceed 110°C.
This condition is met when the stated power levels at 70°C
are used.
The PCB layout should avoid tracks running between the HVC
mounting pads, as this would compromise the LEV.
The LEV stated applies to operation at sea-level pressure and
in a non-condensing atmosphere. Voltage derating should be
applied if low pressure or high humidity may be encountered.
The termination clearance dimension (B) should be used in
conjunction with the creepage limit applicable to the circuit
application in order to determine the derated LEV.
HVC_C.qxd 23/10/03 4:18 PM Page 2