To make things even worse, the names of discrete components are sometimes different depending on whether you are using metric or imperial measurements (cms versus inches), although imperial names (0603, 0805, etc.) are common even in European and other metric regions.At the present time, component handling equipment capable of handling 0402 size components is not widely available. ICs are often referred to by abbreviations such as LQFP, TQFP, TSOP, SSOP, etc., and discrete components (resistors, capacitors, etc.) are typically given names that correspond to their physical dimensions, such as 0402, 0603, 0805, and 1206. This allows you more room to define quiet I/O areas and to fit suppression and filtering components when these prove to be needed.Integrated circuits (ICs) and electronic components come in a bewildering variety of shapes and sizes (often called ‘packages’), and it can be difficult for any beginner to keep track of what the main characteristics are of each package type. A further advantage of surface mount is that, rather than taking advantage of the component size reduction to pack more functions into a given board area, you can reduce the board area needed for a given function.For pas-sive chip devices, such as laminated ceramic capaci-tors (LCCs) and resistors, their sizes have been de-creased from conventional 1005-size (1.0 &165 0.5 &165 0.5 mm) and 0603-size (0.6 &165 SMD stands for Surface Mounted Device. Discrete Componentsforts to downsize the surface-mount devices (SMDs) and increase the board density are underway. This article will provide a basic understanding of SMD packaging types, sizes, and relevant standards to engineers involved or interested in electronic component sourcing in their respective industries.This guide will hopefully serve two purposes: To give you an overview of the most common IC and component packages and sizes, and to help you decide which package type you should be buying or using in different situations. Small sized components are also more difficult to solder and service in the field.Surface-mount devices (SMDs) encompass a wide range of electronic components that electronic engineers use in their daily work.The most common of these standard packages sizes are 0402, 0603, 08. ResistorsResistors, along with many other discrete components, most commonly come in rectangular packages named after their physical dimensions. Most of these discrete components come in common shapes and sizes, and are relatively easy to identify. TE Connectivity (TE) Need Help +1 8 or Live ChatA “discrete component” is a fancy label for the single circuit electronic components that make up most of your board, and they are generally divided into two categories: passive components (Resistors, Capacitors, Diodes, etc.) and active components (Transistors, LEDs, etc.). We offer a wide array of reliable and cost-effective products from standard solutions to custom designs. SMT was developed to meet the ongoing desire for printed circuit board (PCB) manufacturers to use smaller components and to be faster, more efficient, and cheaper when assembling components to the PCBs.Search our portfolio of Surface Mount Resistors products and select your specifications.They come in a wide variety of packages, depending on the type of capacitor used and their technical specifications. 0603, 08 resistors (seen below) can all be hand-soldered with a bit of practice and perhaps some magnification.Capacitors act as ‘mini-batteries’ of sorts, helping ensure that you have a smooth, steady power supply available to all your on-board components and peripherals. 0402 can be difficult to precisely handle due to its very small size. For example, 1/8 watt resistors are widely available in 0805 packages, but you will need to move up to 1206 or larger if you need a 1/2 watt or higher resistor.If you are manually placing the components on the board, or hand-soldering them, it’s best to use 0603 or larger components. Since there is a relationship between the physical size of a component and the amount of current that it can safely handle, manufacturers need to increase the size of the resistors as the rating goes up. I say ‘theoretically’ because there is always some variation between manufactuers and different component types.It’s worth noting that resistors are only able to handle a certain amount of electrical current before burning out (a 1/4 watt resistor, for example, can handle twice as much power — or about 41% more current — as a 1/8 watt resistor).
As such, you may need to pay a bit more attention when adding electrolytic capacitors to your board. Electrolytic capacitors are usually round and ‘stick up’ from the board, but there aren’t really any strictly followed standard sizes used by all manufacturers. Tantalum capacitors have their own standard rectangular package sizes, referred to by letters A, B, C, D, E, etc. Download chess for macBefore placing any LEDs on your board, be sure to read the datasheet to determine which side is A and which is K.Diodes, Transistors, and other discrete componentsWhile Diodes are available in SOT223 and SOT23 packages (see below), they also have their own standard package sizes, with one of the more common sets being SMA, SMB and SMC (an SMA diode can be seen in the second photo below). The electrical current on your LEDs should flow from the Anode (A) to the Cathode (K) side of your LED, with a current-limiting resistor to keep the LED from drawing too much current and burning out (see our entry on “ Ohm’s Law” for information on this and a calculator to help you determine which resistor to use with your LED). Ceramic capacitors are not polarised and can be place in any direction.Surface-mount LEDs (or Light Emitting Diodes) most commonly come in 0603, 08 packages, and are polarised meaning that they need to be placed in the right direction on your board. To help you with this, the + side on tantalum and electrolytic capacitors is usually marked by a solid line or bar, as seen in the last two images below. As well, you need to be careful when placing tantalum and electrolytic capacitors since they are ‘polarised’, meaning they have a + and a – side, and absolutely have to be placed in the proper direction. Ulead 12For example, while a SOT223 device has four pins (three on the bottom and one on top), a SOT223-4 device has 5 pins (four on the bottom), and a SOT223-5 device has 6 pins (five on the bottom). Depending on the number of pins, the package names vary slightly. A very common example is the LM1117 adjustable voltage regulator seen in the first photo below, which is in a four pin SOT223 package. (QFN packages, which have their leads hidden underneath the edge of the chip can still be hand-soldered, but inspection is harder and some care is required when working with them. Variations exist in each of these ‘families’, such as LQFP, TQFP, etc., but the differences are minimal and often refer to the physical height of the package.In general, leaded packages will probably be the easiest to work with for prototyping and small scale production and should be given preference if you have the choice since they can be easily hand-soldered and removed from PCBs, and are very easy to inspect. They are probably the most common type of IC package that you are likely to encounter, though “leadless” packages like QFN (see below) are becoming more and more common.While a wide variety of leaded packages exist, three of the most common families are QFP (Quad-Flat Package), TSOP (Thin Small-Outline Package) and SOIC (Small-Outline Integrated Circuit). (If you’re having a hard time to understand the differences between these admittedly similar package sizes, we’ve added some footprint outlines in the images below.)QFP, SOIC, TSOP, and other “leaded” packagesThese types of IC packages are easy to identify because they have external ‘leads’ (or ‘pins’) that are soldered directly to the PCB. A third SOT package you may encounter is the three pin SOT323, which has one pin on top and two pins on the bottom. ![]() While somewhat challenging to work with due to their size, you can hand-place and inspect small chipscale packages under a microscope, so long as there is only one row of balls on each side (i.e. An exception to this is Chipscale (CS/CSP) packages, which often have only a few pins (6 or 8 isn’t uncommon).
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