Surface Mount Device (SMD)

Surface Mount Device/components are very small as compared to normal electronics components like resistor, capacitor etc.Surface Mount Device is specially designed for the integration of the circuit i.e to make the circuit as small as possible. Integrated Circuit (IC) is the example of the SMD components, if you open datasheet of any IC you can see the circuit diagram of that particular IC, thus we can see the result of application of SMD components in electronic circuit.


You must have seen the above figure of SMD components, they are so minute that you will need magnifying
glass in order to read there values.
If you are interested to know how to read SMD components like Resistor, Capacitor etc. then click on the below link.
How To Read SMD Resistor.
How To Read SMD Capacitor.

Thus we have seen the size of the SMD components, while reading you must have been thinking about how to solder them or how are they soldered on pcb. Below explained are two methods of soldering surface mount devices.

METHOD 1 : Surface Mount Device are soldered by automatic placement (by Robots) onto a specially designed board. This device are placed on the board and thus held on the board using glue. This board is then exposed to an high temperature air, thus the small amount of solder on the board is sufficient to make the solder connection on each of the pins of the surface mount device. The solder on each of the point is melted and forms a bond with the leads of the component. This method is known as re-flow.


METHOD 2 : Another method of soldering SMD components is by shallow bath of molten solder. The parts are glued in place and then the board is turned over and placed above the solder and a wave is created that just touches the board and at the same time deposits a small amount of solder on each of the points. Surface-mount components are designed to withstand a 10 second immersion during the soldering process.This point is mentioned in order to let you know that the temperature of the solder bath is strictly controlled and the solder-time is kept to a minimum.
 
While in case of an average hobbyist you will be needing three major items,
1. Fine tweezers
2. Very fine tipped soldering iron with adjustable temperature.
3.Fine solder (very very fine).
4.Magnifying glass lamp to help with placement, soldering and inspection.


If you are going to solder your first SMD components i suggest you to first practice desoldering and soldering on a scrap printed circuit board.(Nowadays many electronic items are been made using SMD components, hence you can find them easily.)

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How To Read SMD Capacitor

Surface Mount Capacitor
Surface mount capacitor are usually of brownish or yellowish colour, from the colour one can identify whether given component is capacitor to some extent.

But Most SM capacitors values are not identified in any way by visualising ,most of them think that they are identified according to there size but SIZE OF THE COMPONENTS DOES NOT INDICATE THE CAPACITANCE as each capacitor has a different number of layers according to there manufacturer.

The only way to "read" the value of these SM capacitor is via a capacitance meter.
But some of the SM capacitor has number on there surface as that of SM resistor (A three digit number or alphabets).

Similarly as SM resistor there values are indicated, i.e if the number is 107 then first two digit are the answer and the third digit is the number of zero's.
107 = 10 (two numbers) 0000000 (seven zero's)
These value of capacitor is given in pf, hence the value is 100000000pf = 100uf (100 microfarad).

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