Electronic components for surface mounting. Reference data

Encyclopedia of radio electronics and electrical engineering / Reference materials

 Comments on the article

Surface mounting due to its advantages is widely used in modern electronics. In recent years, radio amateurs have also begun to use this type of installation - such designs are increasingly appearing on the pages of Radio.

In terms of electrical characteristics, electronic components for surface mounting (PM) in most cases correspond to their conventional counterparts, differing only in the design of the leads.

The purpose of this article is to acquaint readers with the range of the most popular surface mount radio components currently being produced and their marking so that radio amateurs can more boldly use these components (abroad they are called Surface Mounted Device - SMD) in their developments.

Of greatest interest in this regard are elements with two leads - PM resistors, PM capacitors, PM diodes, etc. - since they do not cause any problems with the manufacture of the printed circuit board. It is more difficult to make a printed circuit board for transistors, microcircuits and other multi-pin parts, but there are appropriate techniques for this (for example, using stencils).

When choosing the type of mounting, it should be taken into account that the small dimensions of the PM parts and, accordingly, the small gaps between the pads for them on the board limit the allowable operating voltage of the device. Therefore, those nodes that operate at high voltage are best performed by conventional installation.

The diminutiveness of many PM parts causes quite understandable problems with their marking. There are special standards for this, but since they are only advisory in nature, many firms use their own designation systems or do not label products at all.

For particularly small parts, such as resistors, the absence of marking is legal. It is not customary to apply denominations to low-capacity ceramic capacitors (although there are standards for them). All this leads to complications in the repair of imported equipment.

The small size of PM components requires much more care and accuracy during installation than conventional ones. The soldering iron must be equipped with a temperature controller. Due to overheating of the part, contact with the terminals may be broken, and since this is difficult to notice, troubleshooting is very time consuming.

Resistors

The appearance of a constant PM resistor is shown in fig. 1 (in this and other figures, the conclusions are highlighted in gray).

The size designation consists of four digits (Table 1). The first two correspond rounded to the length L in the accepted measurement system (either metric or inch), and the last two correspond to the width W. The sizes 0805 and 1206 are of greatest interest to radio amateurs.

A number of firms use "personal" designations for the size of resistors. Table 2 introduces some of them. XNUMX.

To indicate the resistance value, a widespread digital marking is usually used, in which the first digits are the value, and the last one serves as a multiplier (an exponent of the number 10). Resistors with tolerances of ±20, ±10 and ±5% are marked with three digits, and with a tolerance of ±1% or more accurate - with four. For resistors with a resistance of less than 10 ohms with a tolerance of ± 5% or more, two digits are sufficient, and the letter R is placed between them; if the tolerance of the resistor is ±1% or less, then three digits are required and the letter R is placed before the last of them.

Examples of marking:

472 = 47-102 ohms = 4700 ohms = 4,7 kOhm; 105 \u10d 105-1 Ohm \u000d 000 Ohm \u1d 3482 MΩ; 348 \u102d 34800-34,8 \u8d 2 ohms \u8,2d 10 kOhm; XNUMXRXNUMX = XNUMX ohms. For resistors with a resistance of XNUMX ohms or more, it is more convenient to use a simple rule: the number of zeros equal to the last digit must be assigned to significant digits.

Resistors of size 0603 (1608) with a tolerance of ±1% or less have a code marking of two numbers and a letter indicated in Table. 3. Significant digits of the denomination are determined by the numerical code of the designation, and the multiplier by the alphabetic code (the last two columns). Example: 53C \u348d 102 34,8 Ohm \uXNUMXd XNUMX kOhm.

(click to enlarge)

In addition to resistors, several sizes of jumpers are produced, which can be considered as zero-resistance resistors. Such jumpers for surface mounting are more convenient than those used in conventional wire. The most common jumper sizes are 0805 (2012) and 1206(3216). Jumpers are always marked in the same way - OOO.

If the board of the device being developed is supposed to use surface-mount elements, it is more than advisable to use tuned PM resistors. An exception can only be presented by those relatively rare cases when the resistor must be necessarily wire. The fact is that the industry produces only non-wire trimming PM resistors.

By design, tuning PM resistors almost do not differ from conventional ones. A resistive track in the form of an open ring made of a composite of a special composition is applied to the insulating (most often ceramic) base. At the ends of the track, conclusions are reinforced in the form of thin metal strips covering the edge of the base. These findings are soldered to the conductors of the printed circuit board during installation. A contact mounted on a rotor-motor slides along the resistive track, which is rotated with a special miniature screwdriver.

As an example, in fig. 2 and 3 schematically show a general view of two types of Bourns trimmers - 3303W-3 and 3314Z-2, respectively. The axis of rotation of the rotor is perpendicular to the board. They also produce design options for resistors, in which the axis of rotation of the rotor is parallel to the board.

The angle of rotation of the engine from lock to lock for different types of resistors is different and is usually in the range of 210 ... 270 degrees. There are in the range of these resistors and multi-turn. When purchasing a resistor, pay attention to its maximum allowable number of adjustment cycles (one cycle - turning the engine from lock to lock and back). For some types of resistors, this number does not exceed 10.

The standard range of trimming resistors manufactured by leading companies is quite wide. In particular, Bourns provides developers with resistors with a maximum resistance of 10, 20, 50, 100, 200, 500 Ohm, 1, 2, 5, 10, 20, 25, 50, 100, 200, 250, 500 kOhm and 1 MΩ. The ratings are marked with a code, the code is the same as for fixed resistors: the first two digits are significant, and the third is the number of zeros (the result is in ohms).

Due to the fact that there is often not enough space on the body of the trimmer to accommodate even just three characters of the denomination code, special codes with fewer characters have been developed. So, the companies Nidec and Bourns use a two-digit numeric code shown in Table. 4.

To designate the type when ordering products, each company, as a rule, uses its own system. For the same company Bourns, the designation consists of five elements. The first is four digits indicating the group type; it is followed by a letter indicating the packaging features of the finished product (this applies to mounting from a tape using automatic equipment in a production environment). Then through a hyphen - a number characterizing the design features of the engine (1 - with a slot for a regular screwdriver, 2 - a cross recess for a Phillips screwdriver, 3 - a low profile engine with rotation with a Phillips screwdriver). Further through a hyphen - a three-digit code of the nominal value of resistance and a letter indicating the relief features of the packaging tape.

Capacitors

For surface mounting, ceramic and oxide capacitors are produced.

The appearance of ceramic constant capacitors is shown in fig. 4, and in table. 5 - their sizes. The principle of marking ceramic capacitors is the same as that of resistors, you should only substitute picofarads instead of ohms as a result.

Marking with a special code consisting of one or two letters and a number is also possible. The first letter of the two indicates only the manufacturer. The second letter corresponds to the capacity (see Table 6), and the number - the degree of the factor 10. For example, S3=4f7-10³pF.

In practice, most of the manufactured permanent ceramic PM capacitors are not marked. And if their capacitance can be determined by measurement, then the TKE group and the rated voltage - only according to the accompanying documentation (the seller should have it). In reality, it is in the range of 6 ... 100 V (for some types of "large" capacitors - up to 500 V). Since PM capacitors are mainly used in low-voltage equipment, the question of their rated voltage, as a rule, does not arise.

In addition to constant, the industry produces ceramic trimmer capacitors. The appearance of the most popular of them - TZC03 and TZBX4 is shown in fig. 5a,b, respectively.

These capacitors have a ceramic disc between the plates, and the body (base) is plastic. Capacitance change limits - from 1...3 to 14...70 pF. The main technical characteristics of these capacitors are summarized in Table. 7.

Oxide fixed capacitors for surface mounting are represented by two groups - tantalum and aluminum.

Tantalum capacitors are designed in a rectangular case (Fig. 6). The positive terminal on the front side of the case is marked with a contrasting stripe (dark or light) applied across the case.

Capacitor sizes and their designation are summarized in Table. 8, and the "personal" designations used by some firms are in Table. 9.

(click to enlarge)

The marking of capacitors of sizes A and B consists of a letter and three numbers. The letter indicates the rated voltage of the capacitor in accordance with Table. 10, the first two digits are for the capacitance in picofarads, and the third is for the power of 10, which is a multiplier. On the case of capacitors of "large" sizes, the capacitance and voltage are indicated without coding. So, for example, the inscription 10 25V corresponds to a capacitance of 10 microfarads and a voltage of 25 V.

The capacitance of the produced capacitors is from 0,1 to 100 microfarads (row E6), the permissible deviation from the nominal value is ± 20%. Rated voltage - 4, 6,3, 10, 16, 20, 25, 35 and 50 V.

The appearance of aluminum capacitors is shown in fig. 7.

They are classified according to diameter D (Table 11).

For these capacitors, like for tantalum ones, the positive terminal is marked with a stripe of a contrasting color - light or dark. The capacitance and nominal voltage are usually applied directly to the case, for example, 10 16V corresponds to 10 uF, 16 V. Sometimes a code designation consisting of a letter and three numbers is used instead. The letter indicates the voltage (Table 12), and the numbers indicate the capacitance in picofarads and the degree of the multiplier 10. So, marking A475 means a capacitance of 4,7 microfarads and a voltage of 10 V.

Capacitors are produced with a capacity of 0,1 to 1000 microfarads (row E6) with a tolerance of ±20% from the nominal value; nominal voltages - 4, 6,3, 10, 16, 25, 35 and 50 V.

Diodes

Of the discrete surface mount semiconductor devices, the real effect in amateur radio devices is the use of components with only two leads - diodes, zener diodes, varicaps, etc. When using PM transistors, you will most likely get more minuses than pluses. Recall that the full advantages of surface mounting are revealed only in the conditions of factory serial production.

It is known that diodes, like other semiconductor devices, are manufactured in two stages. At the first stage, the device itself (the so-called crystal) is produced, and at the second stage it is mounted in a case. The characteristics of semiconductor devices, of course, do not depend on which package it is mounted in, with the exception of power dissipation.

In other words, if passive components, such as resistors, capacitors, chokes, etc., are directly manufactured either in a "normal" version or for PM, then the type of semiconductor devices is determined only at the stage of "packing" them into a case. Therefore, in relation to semiconductor devices (and to diodes, in particular), it is more correct to consider not the devices themselves, but their cases. Of course, there are devices that are produced only in one type of housing, but this only means that manufacturers do not consider it appropriate to mount them in other housings.

To date, a very large number of cases have been developed for the PM, so it is almost impossible to provide complete information on all cases produced in the world. The purpose of this article is more modest - to give a general overview of the most common of them.

By marking, semiconductor devices for PM are similar to conventional ones. If the body is too small and there is not enough space for a complete marking, an abbreviated one is used; sometimes it doesn't exist at all. There is no single international standard for their designations, there are only national standards. But they are not mandatory, so many firms use their own "personal" designations.

Professional developers, as a rule, use branded catalogs, which provide detailed information about the products. Radio amateur designers have to be content with catalogs of radio component sellers or look for the necessary information on the Internet.

Problems with the designation of radioelements cause considerable difficulties in the repair of imported equipment, and diagrams are usually absent. Often, even if it was possible to identify a faulty element, for example, a transistor, it is not possible to determine its type and possible replacement. Sometimes equipment manufacturers do this for frankly commercial purposes - in order not to leave their service centers without work, they remove markings from purchased radio elements of wide application and apply their own, "proprietary", something like A1 or the like.

To simplify the presentation, under the Diodes in the future we will mean all types of semiconductor devices with two leads.

One of the common cases - cylindrical glass - is produced in two versions: MELF (D0213AB; MLL41) and MiniMELF (SOD80; D0213AA; MLL34). The appearance of this body is shown in Fig. 8, and dimensions - in table. 13. The cathode of the diode is marked with a dark circular stripe. The type of diode is usually indicated by a direct marking on the case, however, some companies use their own "personal" designations.

Packages SMA, SMB and SMC are plastic parallelepiped with end plate leads adjacent to the package (Fig. 9) and bent under it. The dimensions of the cases are summarized in Table. 14. The letter K in the table indicates the length of that part of each output, which is located under the body. On the side of the anode terminal, a recess is provided on the body of the diode, similar in shape to that which is called a key on plastic cases of microcircuits - it indicates the first terminal.

The SOD123 and SOD323 cases are also plastic and have the same shape as the SMA-SMC. The difference lies in the design of the leads (Fig. 10), which are lamellar, but directed away from the case. The dimensions of the SOD123 and SOD323 cases are presented in Table. 15.

The polarity of the diode is determined by a wide strip of contrasting color applied to the upper face of the housing from the cathode side. The marking of the type of diode is also placed here.

Along with single diodes, firms produce assemblies of two or four diodes.

The simplest assemblies of two diodes with a common terminal are usually "packed" into widely used three-terminal transistor packages SOT23 (Fig. 11) with terminals of the same shape as those of SOD123, SOD323. The common electrode of the assembly (most often the cathode) is usually connected to pin 3. A single diode is sometimes placed in such a case - in this case one of the pins remains free.

The pinout of diodes and assemblies is usually not a problem - the cathode and anode of each of them are easy to determine with an ohmmeter. However, in the case of zener diodes or varicaps, an ohmmeter may be powerless.

Diode bridges are produced in four-terminal packages DB and MB-S, the appearance of which is shown in fig. 12, and the dimensions are shown in Table. 16. Conclusions - the same as for SOD 123, SOD323 cases. The pinout of the bridge is usually indicated directly on the body.

The type of diodes, as a rule, is applied to the case, but due to its miniature size, the marking is often reduced. Some firms use their "personal" designation, including in an abbreviated form.

The electrical characteristics of PM diodes are presented in Table. 17 and 18.

In table. 18 summarized diodes and diode assemblies in a three-terminal SOT23 package.

Author: D.Turchinsky, Moscow

See other articles Section Reference materials.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

Traffic noise delays the growth of chicks 06.05.2024

The sounds that surround us in modern cities are becoming increasingly piercing. However, few people think about how this noise affects the animal world, especially such delicate creatures as chicks that have not yet hatched from their eggs. Recent research is shedding light on this issue, indicating serious consequences for their development and survival. Scientists have found that exposure of zebra diamondback chicks to traffic noise can cause serious disruption to their development. Experiments have shown that noise pollution can significantly delay their hatching, and those chicks that do emerge face a number of health-promoting problems. The researchers also found that the negative effects of noise pollution extend into the adult birds. Reduced chances of reproduction and decreased fertility indicate the long-term effects that traffic noise has on wildlife. The study results highlight the need ... >>

Wireless speaker Samsung Music Frame HW-LS60D 06.05.2024

In the world of modern audio technology, manufacturers strive not only for impeccable sound quality, but also for combining functionality with aesthetics. One of the latest innovative steps in this direction is the new Samsung Music Frame HW-LS60D wireless speaker system, presented at the 2024 World of Samsung event. The Samsung HW-LS60D is more than just a speaker system, it's the art of frame-style sound. The combination of a 6-speaker system with Dolby Atmos support and a stylish photo frame design makes this product the perfect addition to any interior. The new Samsung Music Frame features advanced technologies including Adaptive Audio that delivers clear dialogue at any volume level, and automatic room optimization for rich audio reproduction. With support for Spotify, Tidal Hi-Fi and Bluetooth 5.2 connections, as well as smart assistant integration, this speaker is ready to satisfy your ... >>

A New Way to Control and Manipulate Optical Signals 05.05.2024

The modern world of science and technology is developing rapidly, and every day new methods and technologies appear that open up new prospects for us in various fields. One such innovation is the development by German scientists of a new way to control optical signals, which could lead to significant progress in the field of photonics. Recent research has allowed German scientists to create a tunable waveplate inside a fused silica waveguide. This method, based on the use of a liquid crystal layer, allows one to effectively change the polarization of light passing through a waveguide. This technological breakthrough opens up new prospects for the development of compact and efficient photonic devices capable of processing large volumes of data. The electro-optical control of polarization provided by the new method could provide the basis for a new class of integrated photonic devices. This opens up great opportunities for ... >>

Random news from the Archive A camera that can count photons 01.05.2020 Researchers at the Swiss Ecole Polytechnique Federale de Lausanne (EPFL) have created a first-of-its-kind megapixel camera based on single-photon avalanche diodes (SPAD) single-photon detectors. The sensor of this camera is able to detect single photons at an unprecedented speed, which is used for high-speed 3D image capture, and, due to this, this camera is an ideal option for building augmented reality systems, LiDAR laser scanner systems, etc. The new camera can capture 24D images at up to 24 frames per second, compared to standard film and TV video at 30 to 1 frames per second. In addition, scientists managed to make the smallest SPAD pixel and, through some tricks, reduce the amount of energy it consumes to XNUMX microwatt. It should be noted that the creation of a new camera is the result of 15 years of work by AQUALab laboratory specialists, who have come a long way from creating the first SPAD detectors, which had very mediocre characteristics, to modern detectors, which have very small dimensions and are capable of registering single photons at a speed of up to 150 million photons per second. This high speed "camera shutter speed" allows you to increase its dynamic range and capture very fast movements with it. The small size of one pixel of the new camera and the amazing speed of its work became possible thanks to the introduction of a feedback mechanism, which almost instantly suppresses an avalanche of electrons caused by a photon falling on the sensor. A high pixel density on the camera matrix was obtained using specialized software, which in a semi-automatic mode made it possible to find the most optimal method for arranging pixels on the surface of the matrix and conductors through which signals from these pixels are transmitted. In addition, scientists have shown that the parameters of individual pixels of a matrix made using the most common manufacturing technologies differ by no more than 3 percent, which is quite a satisfactory value. The Swiss researchers have already used the new camera to measure the flight time of photons emitted by a laser and reflected by the object being photographed. Moreover, the very wide dynamic range of the new camera made it possible to shoot in conditions where other methods simply do not work, for example, shooting objects far enough away through a partially transparent window.

Other interesting news:

▪ Logitech PowerPlay - mouse pad with recharging

▪ desert crocodiles

▪ Supertelescope Athena and its tasks

▪ The main problem of new generation lithium batteries is solved

▪ Sound card Creative Sound Blaster Z SE

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ site section Spectacular tricks and their clues. Article selection

▪ article All tryn grass. Popular expression

▪ Article How does hunger affect us? Detailed answer

▪ article Woodworking machine with a horizontal cutting tool. home workshop

▪ article Repair of the chainsaw ignition unit. Encyclopedia of radio electronics and electrical engineering

▪ article Amplifier for phone. Encyclopedia of radio electronics and electrical engineering

Leave your comment on this article:

All languages ​​of this page

Arabic	Hebrew	Polish
Bengali	Hindi	Portuguese
Chinese	Italian	Spanish
English	Japanese	Turkish
French	Korean	Ukrainian
German	Malay	Vietnamese

Home page | Library | Articles | Website map | Site Reviews

www.diagram.com.ua
2000-2024