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Jan 24 2019

Resistance Classification and Its Parameters

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Introduction

Resistor is generally called resistance directly in daily life. It is a current-limiting component. After the resistor is connected to the circuit, the resistance of the resistor is fixed. Generally, it is two pins, which can limit the current through the branch connected to it. A resistor cannot be changed and is called a fixed resistor. A variable resistance is called a potentiometer or a variable resistor. The ideal resistor is linear, ie the instantaneous current through the resistor is proportional to the applied instantaneous voltage. Variable resistor for voltage division. On the exposed resistor body, one or two movable metal contacts are pressed. The contact position determines the resistance between either end of the resistor body and the contact.

Article Core

Resistance classification and its Parameters

Purpose

Introduce what the resistance classification and its parameters are.

Application

Semiconductor industry.

Keywords

Resistor.

Catalog

Introduction



Resistance Overview

1.Classification

2. Main Performance Indicators

3. Naming Methods

4. Use Common Sense

Model Name of the Resistor


Main Characteristic Parameters




Chip Resistor Brief

Chip Resistor Classification

Chip Resistor Package And Size

Chip Resistor Package And Power Relationship

Chip Resistor Characteristics

Name Method of Chip Resistor

Chip Resistor Purchase

Chip Resistance Value Recognition


Resistance Overview

The basic knowledge resistor is the most widely used one of the circuit components. It accounts for more than 30% of the total number of components in electronic equipment. The quality of the circuit has a great influence on the stability of the circuit. Its main purpose is to stabilize and regulate the current and voltage in the circuit, and secondly as a shunt divider and load.

Types of Resistor│ Resistor Types │ Different Type of resistor


1.Classification

Resistors commonly used in electronic circuits have fixed resistors and potentiometers. According to different materials and processes, fixed resistors can be divided into: film resistors (carbon film RT, metal film RJ, synthetic film RH and oxide film). RY), solid core resistance (organic RS and inorganic RN), metal wirewound resistor (RX), special resistor (MG type photoresistor, MF type thermistor).

Table 1 Structure and characteristics of several commonly used resistors:

Type of resistance

Resistor structure and characteristics

 

Carbon film resistor

Gaseous hydrocarbons decompose at high temperatures and in vacuum, and carbon deposits on porcelain rods or porcelain tubes to form a crystalline carbon film. Different resistance values can be obtained by changing the thickness of the carbon film and changing the length of the carbon film by the method of notching. Carbon film resistors have lower cost and performance.

 

Metal film resistor

The alloy is heated in a vacuum and the alloy is evaporated to form a conductive metal film on the surface of the ceramic rod. The groove can be changed by changing the thickness of the metal film. Compared with the carbon film resistor, this resistor has a small volume, low noise, and good stability, but the cost is high.

 

Carbon resistor

The mixture of carbon black, resin, clay and the like is pressed and then heat-treated. The resistance is represented by a color circle on the resistor. This kind of resistor has low cost and wide resistance range, but its performance is poor and it is rarely used.

Wirewound resistor

It is made of a copper or nickel-chromium alloy resistance wire wound on a ceramic skeleton. This type of resistance is fixed and variable. It is characterized by stable operation, good heat resistance and small error range. It is suitable for high power applications, and the rated power is generally above 1 watt.

 

Carbon film potentiometer

Its resistor body is made of a carbon film coated on a horseshoe-shaped paper board. Its resistance change and the position of the intermediate contact are linear, logarithmic and exponential. There are several types of carbon film potentiometers, large and small, and some are combined with switches to form a switch potentiometer.There is also a straight-slip carbon film potentiometer that slides on the carbon film to change the resistance. This potentiometer is easy to adjust.

Wirewound potentiometer

It is wound on a ring skeleton with a resistance wire. It is characterized by a small resistance range and a large power.


2. Main Performance Indicators

Rated power: The maximum power allowed to be dissipated on a resistor under the specified ambient temperature and humidity, assuming that ambient air is not circulated, in the case of long-term continuous load without damage or substantially no change in performance. To ensure safe use, the rated power is generally 1-2 times higher than the power it consumes in the circuit. The rated power is divided into 19 grades. Commonly used are 0.05W, 0.125W, 0.25 W, 0.5 W, 1 W, 2 W, 3 W, 5 W, 7 W, 10 W. The rated power of the non-wire wound resistor in the circuit diagram. The symbol is represented as follows:

Main Performance Indicators.png

Resistor resistance indication methods:

(1). Straight-mark method: The resistance value is marked on the surface of the resistor by the number and unit symbol. The allowable error is directly expressed as a percentage. If the resistance is not biased, it is ±20%.

(2). Text notation: A regular combination of Arabic numerals and literal symbols is used to represent the nominal resistance, and the allowable deviation is also indicated by a text symbol. The number before the symbol indicates the integer resistance, and the following numbers represent the first decimal resistance and the second decimal resistance.

a literal symbol indicating the tolerance

Text symbol D F G J K M

Allowable deviation ±0.5% ±1% ±2% ±5% ±10% ±20%

(3). Digital method: A three-digit digital representation of the nominal value on a resistor. From left to right, the first and second digits are valid values, and the third digit is the index, which is the number of zeros. The unit is Europe. Deviations are usually indicated by text symbols.

(4). Color scale method: Mark the nominal resistance and allowable deviation on the surface of the resistor with different colored bands or points. Most of the foreign resistors use the color standard method.

Black-0, Brown-1, Red-2, Orange-3, Yellow-4, Green-5, Blue-6, Purple-7, Gray-8, White-9, Gold-±5%, Silver-±10 %, colorless - ± 20%

When the resistance is four-ring, the last ring must be gold or silver, the first two digits are significant digits, the third digit is the power square, and the fourth digit is the deviation. When the resistance is five rings, the distance between the last ring and the front four rings is larger. The first three digits are significant digits, the fourth digit is the power square, and the fifth digit is the deviation.

Example:

1) A color ring is marked on one end of the resistor body, and the color code of the resistor is arranged from left to right. The resistance of Fig. 1 is 27000 Ω ± 0.5%.

2) The color ring mark of the precision resistor is represented by five color rings. The first to third color circles represent effective figures of the resistance, the fourth color ring represents a multiplier, and the fifth color ring represents a tolerance, and the resistance of FIG. 2 is 17.5 Ω ± 1%.

Represents 27000 Ω ± 5% Represents 27000 Ω ± 5%

Represents 27000 Ω ± 5% Represents 27000 Ω ± 5%

Represents 17.5 Ω ± 1% Represents 17.5 Ω ± 1%

Represents 17.5 Ω ± 1% Represents 17.5 Ω ± 1%

Unit labeling rules for resistors and potentiometers in the circuit diagram.

The resistance is above megaohms and the unit is marked M. For example, 1 megohm, marked 1M; 2.7 megohms, marked 2.7M.

The resistance is between 1 kohm and 100 kohm, and the unit is marked k. For example, 5.1 kilo ohms, marked 5.1k; 68 kilo ohms, marked 68k.

The resistance is between 100 kohm and 1 megohm, and the unit k can be marked or the unit M can be marked. For example, 360 kohms can be labeled 360k or 0.36M.

The resistance is below 1 kohm, and the unit Ω can be marked or not. For example, 5.1 ohms can be labeled 5.1 Ω or 5.1; 680 ohms, which can be labeled 680 Ω or 680.

Maximum working voltage: It refers to the voltage when the resistor works for a long time without overheating or electric breakdown damage. If the voltage exceeds the specified value, a spark is generated inside the resistor, causing noise or even damage. The table below shows the maximum operating voltage of the carbon film resistor.

Table 5 Maximum operating voltage of carbon film resistor

Nominal power ( W)

1/16

1/8

1/4

1/2

1

2

Maximum working voltage (V)

100

150

350

500

750

1000

Stability: Stability is a measure of the degree of resistance change of a resistor under external conditions (temperature, humidity, voltage, time, load properties, etc.)

(1) The temperature coefficient a indicates the relative change in resistance of the resistor for every 1 degree change in temperature, which is:

formula

In the formula: R1 and R2 are the resistance values at temperatures t1 and t2, respectively.

(2) The voltage coefficient av indicates the relative change in the resistance of the resistor for every 1 volt change, which is:

formula

In the formula: R1, R2 are the resistance values when the voltage is U1 and U2, respectively.

Noise Electromotive Force: The noise electromotive force of a resistor can be ignored in a general circuit, but it cannot be ignored in a weak signal system.

The noise of the wirewound resistor is only expected to be related to thermal noise (caused by molecular perturbations) only related to the resistance, temperature and frequency band of the external voltage. In addition to thermal noise, thin film resistors also have current noise, which is approximately proportional to the applied voltage.

High-frequency characteristics: Resistors are used under high-frequency conditions, taking into account the effects of their fixed inductance and inherent capacitance. At this time, the resistor becomes a DC resistance (R0) in series with the distributed inductance, and then the equivalent circuit in parallel with the distributed capacitance. LR=0.01-0.05 microhenry of the non-wire wound resistor, CR=0.1-5 picofarad The LR of the wirewound resistor is up to several tens of microhenries, and the CR is up to tens of picofarads. Even if it is a wirewound resistor without a sense winding, the LR still has a few microseconds.


3. Naming Methods

According to the ministerial standard (SJ-73), the name of the resistor and potentiometer consists of the following four parts: the first part (main name); the second part: (material); the third part (classification feature); the fourth part (Serial number). Their models and meanings are shown in the table below:

Table 6 Model Nomenclature of Resistors:

First part

Second part

Third part

Fourth part

Use letters to indicate the main name

Use letters to indicate material

Representing features by numbers or letters

Serial number

symbol

significance

symbol

significance

symbol

significance


R

RP

Resistor

Potentiometer

T

P

U

C

H

I

J

Y

S

N

X

R

G

M

Carbon film

Metal film

Synthetic film

Deposited film

Synthetic film

Glass glaze film

Metal film

Oxide film

Organic core

Inorganic solid core

Wire winding

Thermal

Photosensitive

Pressure sensitive

1,2

3

4

5

6

7

8

9

G

T

X

L

W

D

Ordinary

Ultra high frequency

High resistance

high temperature

Precision

Resistor - High Voltage

Potentiometer - special function

Special

High power

Adjustable

Small

Measuring

Fine tuning

Multiple circles

include:

rated power

Resistance

Allowable error


Part 1: Main name

Part 2: Materials

 Part 3: Feature Classification

Part 4: Serial Number

symbol

significance

symbol

significance

symbol

significance

Resistor

Potentiometer

R

Resistor

T

Carbon film

1

ordinary

ordinary

For the main name and material, only the performance index and size are different, but the products that are used interchangeably are not affected, and the same serial number is given; if the performance index and size obviously affect the interchangeability, the capital letters are used after the serial number. As a difference code.

W

Potentiometer

H

Synthetic film

2

ordinary

ordinary



S

Organic core

3

Ultra high frequency

――

N

Inorganic solid core

4

High resistance

――

J

Metal film

5

high temperature

――

Y

Oxide film

6

――

――

C

Deposited film

7

Precision

Precision

I

Glass glaze film

8

high pressure

Special function

P

Boron carbon film

9

special

special

U

Silicon carbon film

G

High power

――

X

Wire winding

T

Adjustable

――

M

Pressure sensitive

W

――

Fine tuning

G

Photosensitive

D

――

Multiple circles

R

Thermal

B

Temperature compensation

――



C

Temperature measurement

――

P

Side heat

――

W

Regulated

――

Z

Positive temperature coefficient

――

Example: Name of RJ71-0.125-5.1kI: R resistor - J metal film - 7 precision - 1 - 0.125 rated power - 5.1k nominal resistance - I error 5%.


4. Use Common Sense

According to the technical specifications of the electronic equipment and the specific requirements of the circuit, the type and error level of the resistor should be selected; the rated power should be 1.5-2 times of the actual power consumption; the check should be made before the resistor is connected, especially when the requirement is high, and manual Aging treatment to improve stability; select different types of resistors according to the circuit operating frequency.


Model Name of the Resistor

The resistance of the conductor to the current is called resistance, expressed by the symbol R, and the unit is ohm, kiloohm, and megaohm, which are represented by Ω, KΩ, and MΩ, respectively.

The model of the domestic resistor consists of four parts (not applicable to sensitive resistors)

The first part: the main name, expressed in letters, indicating the name of the product. For example, R represents a resistor and W represents a potentiometer.

The second part: materials, indicated by letters, indicate what material is used for the resistor body, T-carbon film, H-synthetic carbon film, S-organic solid, N-inorganic solid, J-metal film, Y-nitride film, C-deposited film, I-glass glaze film, X-ray wound.

The third part: classification, generally expressed by numbers, individual types are represented by letters, indicating what type of product belongs to. 1-Normal, 2-Normal, 3-UHF, 4-High Resistance, 5-High Temperature, 6-Precision, 7-Precision, 8-High Voltage, 9-Special, G-High Power, T-Adjustable.

The fourth part: Serial number, expressed in numbers, indicating different varieties in similar products to distinguish the product's dimensions and performance indicators.

For example: RT11 type ordinary carbon film resistor a1.


Main Characteristic Parameters

1. Nominal resistance: The resistance value indicated on the resistor.

2. Allowable error: The percentage of the difference between the nominal resistance and the actual resistance and the nominal resistance is called the resistance deviation, which indicates the accuracy of the resistor.

The correspondence between the allowable error and the accuracy level is as follows: ±0.5%-0.05, ±1%-0.1 (or 00), ±2%-0.2 (or 0), ±5%-I, ±10%-II, ± 20%-III

3. Rated power: The maximum power allowed to be dissipated by the resistor for long-term operation under normal atmospheric pressure of 90-106.6KPa and ambient temperature of -55°C to +70°C.

Wirewound resistor rated power series is (W): 1/20, 1/8, 1/4, 1/2, 1, 2, 4, 8, 10, 16, 25, 40, 50, 75, 100, 150, 250, 500

Non-wire wound resistor rated power series is (W): 1/20, 1/8, 1/4, 1/2, 1, 2, 5, 10, 25, 50, 100

4. Rated voltage: The voltage converted from resistance and rated power.

5. Maximum working voltage: The maximum continuous working voltage allowed. When operating at low air pressure, the maximum operating voltage is low.

6. Temperature coefficient: The relative change of the resistance value caused by the temperature change of 1 °C. The smaller the temperature coefficient, the better the stability of the resistor. The resistance increases with increasing temperature as a positive temperature coefficient, and vice versa.

7. Aging coefficient: The percentage of the relative change of the resistance of the resistor under the long-term load of rated power. It is a parameter indicating the length of life of the resistor.

8. Voltage coefficient: The relative change of the resistor for every 1 volt change in the specified voltage range.

9. Noise: An irregular voltage fluctuation generated in a resistor, including thermal noise and current noise. Thermal noise is due to the irregular movement of electrons inside the conductor, causing irregular voltage changes at any two points of the conductor. 


Chip Resistor Brief

A chip-type fixed resistor, directly translated from Chip Fixed Resistor, commonly known as SMD Resistor, is one of the metallic glass uranium resistors. It is a resistor made by mixing metal powder and glass uranium powder and printing it on a substrate by screen printing. Resistant to humidity, high temperature and low temperature coefficient. (Note: The following chip fixed resistors are called chip resistors)


Chip Resistor Classification

Chip resistors are divided into the following categories:

Conventional series thick film chip resistors
General purpose General purpose, 0201 - 0805
General purpose, 1206 - 2512

High precision and high stability chip resistor

High precision - high stability High precision - high stability, 0201 - 0603
High precision - high stability, 0805 - 1210
High precision - high stability, 2010 - 2512

Conventional series of film chip resistors
General purpose thin film General purpose thin film, 0201-2512

Low resistance chip resistor
Low ohmic Low ohmic, 0402 - 1206
Low ohmic, 2010 - 2512

Chip resistor array
Arrays Arrays, convex and concave

SMD current sensor
SMD current sensors Current Sensors - Low TCR

Patch network resistor
Network Network, T-type and L-type  


Chip Resistor Package and Size

The package and dimensions of the chip resistor are as follows:

Inch (mil) Metric (mm) Length (L) (mm) Width (W) (mm) Height (t) (mm) a (mm) b (mm)
0201 0603 0.60±0.05 0.30±0.05 0.23±0.05 0.10±0.05 0.15±0.05
0402 1005 1.00±0.10 0.50±0.10 0.30±0.10 0.20±0.10 0.25±0.10
0603 1608 1.60±0.15 0.80±0.15 0.40±0.10 0.30±0.20 0.30±0.20
0805 2012 2.00±0.20 1.25±0.15 0.50±0.10 0.40±0.20 0.40±0.20
1206 3216 3.20±0.20 1.60±0.15 0.55±0.10 0.50±0.20 0.50±0.20
1210 3225 3.20±0.20 2.50±0.20 0.55±0.10 0.50±0.20 0.50±0.20
1812 4832 4.50±0.20 3.20±0.20 0.55±0.10 0.50±0.20 0.50±0.20
2010 5025 5.00±0.20 2.50±0.20 0.55±0.10 0.60±0.20 0.60±0.20
2512 6432 6.40±0.20 3.20±0.20 0.55±0.10 0.60±0.20 0.60±0.20


Chip Resistor Package and Power Relationship

The package and power relationship of the chip resistor is as follows:

Package Rated power 70°C Maximum operating voltage (V) Inch (mil) Metric (mm) Conventional power series Lifting power series
0201 0603 1/20W / 25
0402 1005 1/16W / 50
0603 1608 1/16W 1/10W 50
0805 2012 1/10W 1/8W 150
1206 3216 1/8W 1/4W 200
1210 3225 1/4W 1/3W 200
1812 4832 1/2W / 200
2010 5025 1/2W 3/4W 200
2512 6432 1W / 200

Note: Voltage = √ power x resistance value (P = V2 / R) or the smaller of the maximum operating voltage


Chip Resistor Characteristics

Small size and light weight;

·Adapt to reflow and wave soldering;

· stable electrical performance and high reliability;

· Low assembly cost and matching with automatic mounting equipment;

·High mechanical strength and superior high frequency characteristics.


Name Method of Chip Resistor

The naming method of domestic chip resistors:

1, 5% precision naming: RS-05K102JT

2, 1% precision naming: RS-05K1002FT

R - indicates resistance

S - indicates that power 0402 is 1/16W, 0603 is 1/10W, 0805 is 1/8W, 1206 is 1/4W, 1210 is 1/3W, 1812 is 1/2W, 2010 is 3/4W, and 2512 is 1W.

05 - indicates size (inches): 02 indicates 0402, 03 indicates 0603, 05 indicates 0805, 06 indicates 1206, 1210 indicates 1210, 1812 indicates 1812, 10 indicates 1210, and 12 indicates 2512.

K - indicates a temperature coefficient of 100 PPM,

102-5% precision resistance representation: the first two digits represent a significant number, the third digit indicates how many zeros, the basic unit is Ω, 102 = 10000 Ω = 1 KΩ. 1002 is a 1% resistance representation: the first three digits represent significant digits, the fourth digit indicates how many zeros, the basic unit is Ω, and 1002 = 100,000 Ω = 10 kΩ.

J - indicates an accuracy of 5% and F- indicates an accuracy of 1%.

T - indicates tape packaging

Chip resistor resistance error accuracy is ±1%, ±2%, ±5%, ±10% accuracy, the most common use is ±1% and ±5%,

The rule of ±5% precision is to use three digits to represent the example 512. The first two digits are significant digits, the third digit 2 indicates how many zeros, the basic unit is Ω, which is 5100 ohms, 1000 Ω = 1 Ω, 1000000 Ω. =1MΩ

In order to distinguish ± 5%, ± 1% of the resistance, then ±1% of the resistance is mostly expressed by 4 digits.

Thus the first three digits represent a significant number, and the fourth digit indicates how many zeros are 4531, which is 4530Ω, which is equal to 4.53KΩ.


Chip Resistor Purchase

The application of surface mount technology (SMT) is very common, and the proportion of electronic products assembled by SMT has exceeded 90%. China has been using SMT since the 1980s. With the development of small SMT production equipment, the application scope of SMT is further expanded. In the fields of aviation, aerospace, instrumentation, machine tools, etc., SMT is also used to produce various electronic products or components with small quantities.

In recent years, in addition to the development of new products by electronic product developers using chip devices, maintenance personnel have begun to repair a large number of electronic products assembled by SMT. This article will introduce the main parameters and specifications of the most widely used chip resistors, capacitors and inductors, in order to help developers and maintenance personnel to purchase these chip components.

At present, the models of the chip resistors are not uniform, and are set by the manufacturers themselves, and the models are particularly long (consisting of more than a dozen English letters and numbers). If you can correctly propose various parameters and specifications of the chip resistor during the purchase, it is convenient to purchase (or order) the required resistance.

There are five parameters for the chip resistor, namely size, resistance, tolerance, temperature coefficient and packaging.

1. The size series of chip resistor series is generally available in seven sizes and is represented by two size codes. One size code is an EIA (American Electronics Industry Association) code represented by a 4-digit number. The first two digits and the last two digits indicate the length and width of the resistor, in inches. The other is a metric code, also represented by a 4-digit number, in millimeters. Different sizes of resistors have different power ratings. Table 1 lists the code and power ratings for these seven resistor sizes.

2. The nominal resistance of the resistance series is determined by series. Each series is divided by the tolerance of the resistor (the smaller the tolerance is, the more the resistance is divided), the most commonly used is E-24 (the tolerance of the resistance is ±5%), as shown in Table 2. .

The resistance value is represented by three digits on the surface of the chip resistor, wherein the first digit and the second digit are valid digits, and the third digit represents the number of subsequent zeros. When there is a decimal point, it is represented by "R" and takes up one effective digit. The nominal resistance code representation method is shown in Table 3.

3. The tolerance of the chip resistance (carbon film resistance) has 4 levels, namely F class, ±1%; G class, ±2%; J grade, ±5%; K grade, ±10%.

4. Temperature coefficient The temperature coefficient of the chip resistor has 2 levels, ie w level, ±200ppm/°C; X level, ±100ppm/°C. Only resistors with tolerances of class F are used for class x, while resistors for other classes are generally of class w.

5. The packaging is mainly available in bulk and in tape.

The operating temperature range of the chip resistor is -55--+125°C. The maximum operating voltage is related to the size: 0402 for 0402 and 0603, 150V for 0805, and 200V for other sizes.

The size codes of the most widely used chip resistors are 0805 and 1206. And gradually there is a trend to develop to 0603. The most common tolerance is J.

For example, in an electronic product, there is a size of 3.1 × 1.55mm, and the surface is printed with a 103 word resistance damage. As can be seen from Table 1, the resistor size code is 1206, the resistance is 10k, and the power is 1/8w. If the tolerance is ±5%, just ask when purchasing or ordering. 1206 type lOk, J level, 100 pieces in bulk (the general minimum purchase unit is 100). Since the temperature coefficient of the J-level tolerance is w (±200ppm/°C), the temperature coefficient requirement may not be proposed.


Chip Resistance Value Recognition

Chip resistor resistance error accuracy is ±1%, ±2%, ±5%, ±10% accuracy, the most commonly used is ±1% and ±5%, ±5% accuracy is conventionally used with three digits To illustrate

In Example 512, the first two digits are significant digits, the third digit 2 indicates how many zeros, and the basic unit is Ω, which is 5100 ohms, 102=1KΩ, 105=1MΩ.

In order to distinguish ±5%, ±1% of the resistance, then ±1% of the resistance is mostly expressed by 4 digits, so the first three digits represent the significant digits, and the fourth digit indicates how many zeros are 4531 or 4530Ω.


The following are physical pictures:

resistance

resistance

resiatance

resistance

resistance


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