Precision Metal Film Resistors
1. Applicable Scope:
This standard specification is for use in consumer electronics, computers,
telecommunications, control instruments...etc.
2. Part Number:
It is composed by Type, Rated Wattage, Nominal Resistance, Tolerance, Temperature
Coefficient and Package/Terminal Form. e.g.
RN
Type
1/4W
1KΩ
F
T/B
Rated Wattage Nominal Resistance Tolerance Temp. Coefficient Package/Terminal Form
2.1 Type :
Precision Metal Film Resistors are Called "RN".
2.2 Rated Wattage:
Shown by "W", such as 1/8W,1/4WS,1/4W,1/2WS,0.6W,1/2W,1W,1WL.
2.3 Nominal Resistance:
Ω,KΩ,MΩare
its unit, which be in accordance with JIS-C6409 article 6 (EIA
RS-196A) series.
2.4 Tolerance:
It is measured by Bridge-method at room temperature and expressed by a capital
letter.
Code
J
G
F
D
C
B
Tolerance(
±)
5%
2%
1%
0.5%
0.25%
0.1%
2.5 Temperature Coefficient:
±25ppm/℃, ±50ppm/℃.
Nil :
±100ppm/℃.
2.6 Package/Terminal Form:
T/B＝tape in box; Nil＝ Bulk; M form.
Remark : RN Series Resistors are RoHS Compliant.
3. Rated Power:
Rated power is the value of Max load voltage specified at the ambient temperature of
70℃, and shall meet the functions of electrical and mechanical performance. When
the ambient temperature surpasses above mentioned temperature, the value declines
as per following DERATING CURVE
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Precision Metal Film Resistors
3.1 Rated Voltage:
It is calculated through the following formula:
where E: rated voltage (V)
P: rated power (W)
E
=
PXR
R: nominal resistance value (Ω)
However, in case the voltage calculated exceeds the maximum load voltage,
such the maximum load voltage shall be regarded as its rated voltage, means
whichever less.
4. Dimension and structure:
4.1 Dimension:
TYPE
RN
1/8W
1/4WS
1/4W
1/2WS
0.6W
1/2W
1W
D±1
1.7±0.2
L±1
H±3
d±0.1
Resistance
Range
10Ω~1MΩ
3.7max
28
0.45
Unit: mm
Max
Working
Voltage
150V
200V
250V
300V
350V
350V
500V
500V
2.4±0.5
3.5
4.5
6.4
9
11
28
28
28
0.6
0.65
0.8
10Ω~2MΩ
10Ω~2MΩ
10Ω~2MΩ
10Ω~2MΩ
1WL
5
15
28
0.8
◎
Notes:1.Too low or too high ohmic value can be supplied only case by case
2. Max Overload Voltage is 2 times of Max Working voltage
3. RN 1W & RN 1WL are coated by flameproof paint
4.2 Structure :
4.2.1 Ceramic Rod:
It is made of Forste imported from Japan.
4.2.2 Terminal:
Terminal is to be firmly connected with resistors element, both electrically
and mechanically, and allow easy soldering.
4.2.3 Coating:
Coating is done by EPOXY insulating paint which is solid enough to be free
from looseness, crack and easy breakage. The paint shall be limited within
1mm of lead wires from resistors body. (Coating can also be made by
flameproof paint upon request.)
4.2.4 Marking:
Marking is made on resistors surface by color coding.
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Precision Metal Film Resistors
5. Operating Temperature Range: -65℃½175℃
6. Mechanical Performance:
6.1 Terminal tensile:
To Fix the resistor body, a static load of 1kg.is to be gradually applied into the
terminal for 10 seconds without causing any looseness and fall.
6.2 Twist withstand:
To bend the lead wire at the point of about 6mm from resistor body to 90°, then
catch the wire at 1.2
±0.4mm
apart from the bent point end and turn it (clockwise)
by 360 degrees perpendicular to the resistor axis at speed of 5 seconds per turn,
and do the same counterclockwise again which constitute a whole turn. Repeat
the turn 2 times without causing any break and looseness.
7. Electrical Performance:
7.1 Resistance Temperature Coefficient:
It shall be as follows:
Code
T-1
T-2
T-9
T.C.
±100ppm/℃
±50ppm/℃
±25ppm/℃
T.C. (ppm/℃) =［(R2－R1)÷R1½×［1÷(T2－T1)½×10
6
where
R1: resistance value at reference temperature
R2: resistance value at test temp.
T1: reference temp. (usu. 25℃)
T2: test temp. (about 75℃)
7.2 Temperature Cycle:
Following temp. cycles are to be made 5 times and then put at room temp. for
one hour, the resistance value change rate between pre-and-post test shall be
within
±0.25%.
Steps
1
st
step
2
nd
step
3
rd
step
4
th
step
Temperature(℃)
-65 ± 3
Room temp.
175 ± 3
Room temp.
Time (minutes)
30
3
30
3
7.3 Short Time Over Load:
When the resistors are applied 2.5 times as much as rated voltage for 5 seconds
continuously, it shows no evidence of arc, flame...etc. Removing the voltage and
place the resistors to the normal condition for 30 minutes, the resistance value
change rate between pre-and-post test shall be within
±0.5%.
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Precision Metal Film Resistors
7.4 Insulation Character :
Resistors are located in a V-shaped metal trough. Using the DC 500V megger
instrument 2 poles to clutch either side of lead wires and metal trough,
measuring the Insulation Resistance which shall be over 10000MΩ.
7.5 Voltage Withstanding:
Resistors are located in a V-shaped metal trough. Applying Max overload voltage
(RN 1W & RN 1WL:Applying AC 350V, RN 1/4WS:Applying AC 300V ) for one
minute and should find no physical damage to the resistors, such as
arc,char…etc.
7.6 Load Life:
The resistors arrayed are sent into the 70℃ oven, applying rated voltage at the
cycle of 1.5 hours ON, 0.5 hour OFF for 1000
-0
hours in total. Then, after
removing the voltage, take the resistors out of the oven and left under normal
temp. for one hour cooling. The resistance value change rate between
pre-and-post test shall be within
±2%.
7.7 Moisture-proof Load Life:
The resistors arrayed are placed into a constant temp./humidity oven at the temp.
of 40±2℃ and the humidity of 90½95%, then rated power is applied for 1.5 hours
and cut off for 0.5 hour. The similar cycle will be repeated for 1000
-0
hours in
total (including cut- off time). Then remove the voltage, taking the resistors out of
the oven and leaving them at room temp. for one hour. The resistance value
change rate between pre–and- post test shall be within
±1.5%.
There also shall
be no evidence of remarkable change on appearance, and the marking shall not
be illegible.
7.8 Solder-ability:
The leads with flux are dipped in a melted solder of 235
±5℃
for 2 seconds,
more than 95% of the circumference of the lead wires shall be covered with
solder.
7.9 Resistance to Soldering Heat:
Two leads are together dipped in a melted solder of 270
±5℃
for 10
±1
seconds,
or 350
±10℃
for 3.5
±0.5
seconds, Then remove the resistors and leaving them at
room temp. for one hour. The resistance value change rate between pre-and-post
test shall be within
±0.5%.
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