High Voltage
Metal Film Resistors
MH Series
Welwyn Components
•
BSEN 60065 Approval for MH37
in value range 680K to 3M
•
•
•
•
•
High working voltage to 3.5KV
Small size
High pulse load capability
Robust cement coating
Value up to 10M
Electrical Data
MH25
Power rating at 70°C max
Resistance range
Limiting element voltage
Isolation voltage
TCR
Resistance tolerance
Standard values
Thermal impedance
Ambient temperature range
°C/watt
°C
140
- 55 to 155
watts
ohms
volts dc or ac peak
volts
ppm/°C
%
0.25
100K - 10M
1,600
700
100
1, 2, 5
E24 and E96 preferred
112
MH37
0.5
100K - 3M
3,500
Physical Data
Dimensions (mm) and Weight (g)
PCB
mounting
centres
10.2
12.7
Min
Bend
Radius
0.6
1.2
Type
MH25
MH37
L max
6.2
9.0
D max
2.5
3.7
f min
21.0
19.6
d nom
0.6
0.8
Wt.nom
0.3
0.5
d
D
L
f
Construction
Thin film material is sputtered on to high grade ceramic rods.
Nickel plated steel caps are force fitted and the termination
wires are welded to the caps. The value is obtained by a
helical cut in the film and finally the resistor body is protected
by a cement protection applied so that the terminations
remain completely clear.
Terminations
Material
Strength
Solder-coated copper wire.
The terminations satisfy the requirements of
IEC 68.2.21.
Solderability
The terminations meet the requirements of
IEC 115-1, Clause 4.17.3.2
Marking
1% tolerance resistors are colour coded with 5 bands.
2% and 5% tolerance have 4. Band IEC 62 colours are used.
Solvent resistance
The body protection and marking are resistant to all normal
industrial cleaning fluids suitable for printed boards.
General Note
Welwyn Components reserves the right to make changes in product specification without notice or liability.
All information is subject to Welwyn’s own data and is considered accurate at time of going to print.
A subsidiary of
TT electronics plc
Issue E · 10.05
© 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
191
High Voltage
Metal Film Resistors
MH Series
Welwyn Components
Performance Data
Maximum
Load at rated voltage : 1000 hrs at 70°C
Derating from rated power at 70°C
Overload
56 days at DHSS
Climatic
Climatic category
Temperature rapid change
Resistance to solder heat
Vibration and bump
Voltage proof
∆
R%
∆
R%
∆
R%
volts
0.5
0.5
0.5
700 min
∆
R%
∆
R%
∆
R%
1.0
1.5
1.5
55/155/56
0.05
0.05
0.05
∆
R%
1.5
Zero at 155°C
0.25
0.2
0.2
Typical
0.4
Application Notes
To ensure reliable performance at high voltages care should
be taken to avoid potential sources of ionic contamination
contacting the resistor body, for example, flux applied by
spraying, encapsulation materials or contaminants from the
environment of use.
Packaging
All MH series resistors are supplied tape packed ready for
loading on automatic sequencing and insertion machines.
Component wires will not protrude beyond the outside edge
of the tape.
Alternative packing available by request.
Standard Quantities Per Package
Type
Ammo pack
MH25
5000
MH37
2500
6
52
6
5
Lead Formed Resistors can also be supplied. Standard options
of Lancet, Radial and Goal Post forming are shown in the
Lead Form information sheet.
f
1
f
2
Body Location f
1
– f
2
≤
1.4 mm
Ordering Procedure
Specify type reference, value and tolerance as shown in this example of MH25 10MR 1%:
Type
Resistance value
(IEC62 code)
Tolerance
(IEC62 code)
F
G
J
1%
2%
5%
MH25
10MO
F
© 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
192
Issue E · 10.05
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