Surface-mount technology (SMT) is a method for producing electronic circuits in which the. An SMT component is usually smaller than its through-hole counterpart because it has either smaller leads or no leads at all. 8 Identification. And a similar.pdf list is also available, although these lists are not complete.
We should make sure that types of markings for all the types of resistors, caps, ICs, and everything else are thoroughly explained. This is not terribly important to engineers, who are more concerned with theory and just pull them out of a labeled box. But to the hobbyist this is pretty important, and also difficult to learn, because there are so many nonintuitive ways to label things.Should we put the color code and SMT numbering explanations at the top, and then tell in each section what they stand for? (ohms, picofarads, microhenries) 'The color-digit pairs used in the resistor example below are standard, but the tolerance and higher multiplier values are for resistors only.'
Contents.Resistors Identifying resistors Most axial resistors use a pattern of colored stripes to indicate resistance. SMT ones follow a numerical pattern.
Cases are usually brown, blue, or green, though other colors are occasionally found like dark red or dark gray.4-band axial resistors Axial resistors are also called 'thru-hole' resistors because they cross the plate to which they are welded. Four band identification is the most commonly used color coding scheme on all resistors.
It consists of four colored bands that are painted around the body of the resistor. The values of the resistors belong to series. The best-known series with 4 rings is called the E12 serie because this series contains 12 values.
The values are part of the preferred numbers. The scheme is simple: The first two numbers are the first two significant digits of the resistance value, the third is a multiplier, and the fourth is the tolerance of the value. Each color corresponds to a certain number, shown in the chart below. The tolerance for a 4-band resistor will be 2%, 5%, or 10%Color1st band2nd band3rd bandMultiplierToleranceTemp. CoefficientBlack000×10 0Brown111×10 1±1% (F)100 ppmRed222×10 2±2% (G)50 ppmOrange333×10 315 ppmYellow444×10 425 ppmGreen555×10 5±0.5% (D)Blue666×10 6±0.25% (C)Violet777×10 7±0.1% (B)Gray888×10 8±0.05% (A)White999×10 9Gold×0.1 (10 −1)±5% (J)Silver×0.01 (10 −2)±10% (K)None±20% (M)For example, if you are looking for a 12K (12000 ohm) resistor with ±5% tolerance, you would be looking for a Brown (1) Red (2) Orange (×10 3) Gold (±5%) resistor.12×10 3 ohm = 12000 Ω = 12 kΩNote that red to violet are the colors of the rainbow where red is low energy and violet is higher energy.
Resistors use specific values, which are determined by their tolerance. These values repeat for every exponent, 6.8, 68, 680. This is useful because the digits, and hence the first two or three stripes, will always be similar patterns of colors, which you will learn to recognize without checking a chart.
To help you remember them, the standard values for 10% resistors are:6882The E24 series therefore contains 24 values with 2 significant digits. As soon as the E48 series, the resistors contain 3 significant digits, so a code with 5 color rings. These numbers are not chosen at random, but are part of IEC 60063. Charles Renard proposed these numbers and have since been adopted in the international standard ISO 3.5-band axial resistors 5-band identification is used for higher precision (lower tolerance) resistors (1%, 0.5%, 0.25%, 0.1%), to notate the extra digit. The first three bands represent the significant digits, the fourth is the multiplier, and the fifth is the tolerance.SMD/SMT resistors SMD (surface mounted device) or SMT (surface mount technology; same thing) resistors are found mostly on devices where large scale integration is present. They generally use an alphanumeric numbering system.For surface mount resistors, a numerical code is used. For 10% tolerance resistors, 3 numbers are used, for 1% resistors, 4 digits are used.
The scheme is similar to color codes, in that the first two or three digits are the significant digits, and the last digit is the multiplier (expressed as an exponent of 10). This is easy to remember as 'the first digits then as many zeros as the last digit after it' ohms. '683' for instance, represents 68 with three zeros after it: 68 000 = 68 kΩ. Likewise, '4991' represents 499 with 1 zero after it: 499 0 = 4.99 kΩ.For small resistance values, an alternate notation is often used. For these, an R is used in place of the decimal.
For example, 5R6 = 5.6 Ω.They are the smallest class of discrete resistors available.Large resistors For large power resistors and potentiometers, the value is usually written out explicitly as '2Ω', for instance. Some power resistors have their power rating imprinted on the component body. An example of a 10W '2Ω' power resistor follows.Examples In the top example, the colors are. This means 1 0 ×10 3 Ω ± 5% = 10 ± 0.5 kΩ.
This resistor has a value anywhere from 9.5 to 10.5 kΩThe second example has 5 stripes. This means 1 0 0 ×10 2 Ω ± 1% = 10 ± 0.1 kΩ. This resistor then has a value anywhere from 9.9 to 10.1 kΩ.Note that these are both 10 kΩ.The third example is a larger power resistor, and is labeled. This means 5 6 ×10 0 Ω ± 5% = 56 ± 2.8 Ω. This resistor then has a value anywhere from 53.2 to 58.8 Ω.
It has a higher power rating than the others, which is not labeled, but is obvious from its larger size.Capacitors. Axial (top) and radial (bottom) electrolytic capacitors Electrolytic capacitors Axial electrolytic capacitors are electrolytic capacitors that have connections on both ends. These are most frequently used in devices where there is no space for vertically mounted capacitors. See photograph above.The arrowed stripe indicates the polarity, with the arrows pointing towards the negative pin. Warning: connecting electrolytic capacitors in reverse polarity can easily damage or destroy the capacitor.
Most large electrolytic capacitors have the voltage, capacitance, temperature ratings, and company name written on them without having any special color coding schemes. Most electrolytic capacitors in general have light blue, black, dark purple or brown colors, although some specialized ones come in yellow and other colors. If for some reason you are uncertain about the polarity, the can is always the negative connection. Most axial caps have both ends visible. The positive end has a rubber insulation and the negative side is only aluminium.Radial electrolytic capacitors are like axial electrolytic ones, except both pins come out the same end. Usually that end (the 'bottom end') is mounted flat against the PCB and the capacitor rises perpendicular to the PCB it is mounted on.
![Smd code book 2018 pdf Smd code book 2018 pdf](http://www.talkingelectronics.com/projects/Testing%20Electronic%20Components/images/Surface-mountCaps.jpg)
This type of capacitor probably accounts for at least 70% of capacitors in consumer electronics (that don't use SMT components). See photograph above.Like their axial counterparts, many radial electrolytic capacitors have the voltage, capacitance, temperature ratings, polarity, and company name directly written on them without having any special color coding schemes. Tantalum capacitors Tantalum capacitors are useful due to their low leakage current, reliability, and their ability to keep stable capacitance over a wide range of temperatures. Below is a diagram:They have special markings. The stripe on the side indicates polarity. Usually with a store bought component, the longer lead is positive. Warning: connecting tantalum capacitors in reverse polarity can easily damage or destroy the capacitor.
Generally it will have the capacitance written in µF, and the working voltage below it. In some cases (often when µF is not printed), the value (in pF) is encoded with three numbers; the first two digits being the significant figures, with the third being the multiplier (i.e. Number of zeros). Tantalum capacitors are most commonly dipped and have a shiny coating, as well as vary in color, being yellow, red, and sometimes blue. Most axial tantalum capacitors look completely different.The dark line on the SMT variety is the positive terminal. The dipped axial through-hole variety will be marked with a + or a dark line to indicate the positive terminal.Ceramic capacitors Ceramic capacitors are generally non-polarized and almost as common as radial electrolytic capacitors.Generally, they use an alphanumeric marking system.
The number part is the same as for SMT resistors, except that the value represented is in pF. They may also be written out directly, for instance, 2n2 = 2.2 nF.
One of the best ways of narrowing down SMT parts is to determine the manufacturer from the logo, which even in SMT parts is almost always stamped or etched into the top of the plastic part. Then, its easy to find sites that show the logos of all semiconductor and electronic part manufacturers. Once you've determined the mfg, and you have the marking, you're 90% there and if all else fails, call the manufacturer and ask the customer service people or the applicfation engineers.Regards,Kamran Kazemkkazem.