SMD LED ( Surface Mount Device-Light Emitting Diode ) - A Beginner's Guide

So What Is SMD?
SMD stands for Surface-mount device. It is derived from Surface-mount technology (SMT) which is a method for constructing electronic circuits in which the components are mounted directly over the surface of printed circuit boards (PCBs). Surface mounting lends itself well to a high degree of automation, reducing labor cost and greatly increasing production rates. SMDs can be 1/4th to 1/10th the size and weight, and half to 1/4th the cost of equivalent through-hole parts.
A pair of SMD Capacitor
A pair of SMD Capacitor

SMD Capacitor After Mounting on PCB
Different SMD Capacitor After Mounting on PCB

So What is SMD LED?

Different Types Of SMD LEDs
Different Types Of SMD LEDs
To be specific, it is a "light emitting diode" that can mounted & soldered on a Printed circuit board (PCB). An SMD LED like other SMD component, is quite small since it has no pins/leads or packaging that comes with a normal LED. So its best to be handled, not by a human, but by automated assembly equipment. An SMD LED also has a wide viewing angle,due to the fact that it does not have the standard LED's hemispherical epoxy enclosure that actually focuses the beam. 

Hemispherical Epoxy Of An Ordinary LED
Hemispherical Epoxy Of An Ordinary LED
USES: 
Practicle Implementation Of SMD LEDs
Practicle Implementation Of SMD LEDs
**They are commonly used to indicate device status on computer motherboards, WiFi routers, hard drives, USB flash drives and any other application where physical space is at a premium.
**The are used in LCD display backlighting, keyboard backlights, & pushbuttons.
**Used in instrument panels in aircraft, cars & various digital/analog indicators.
**Used in Microcontroller boards ( Arduino, 8051, AVR etc), for indication of power on, & serial communication in progress etc.  
 

Main advantages of SMD LED's over the normal LEDs are:
  • **Smaller sized (smallest one is nearly  0.4 × 0.2 mm ).
  • **Very low voltage and current requirements
  • **Much higher LED component density (components per unit area) can be achieved.
  • **Lower initial cost and time of setting up for production.
  • **Fewer holes need to be drilled, as only surface mounting is required.
  • **Simpler and faster automated assembly.
  • **They can be placed on both sides of the circuit board.
  • **Better mechanical performance under sudden shock & vibration conditions.
  • **Many SMD LEDs cost less than equivalent through-hole parts LEDs.
  • Longer Life Span, i.e., under proper current and voltage condition, the life span of SMD LED can reach more than 100,000 hrs, & that is equivalent to 11.41 years!!
Oval SMD LEDs
Oval Shaped SMD LEDs
SMD LEDs Notations:
You are going to find that in market, particularly 2 types of SMD LEDs are prevailing, they are LED 3528 & LED 5050

So what 3538 & 5050 indicates??

The answer lies in their dimensions...
For SMD 3528
  • ** Consisting of 1 light-emitting chip
  • ** Dimension of chip : 35 x 28 mm

SMD 5050
  • ** Consistind of 3 light-emitting chips
  • ** Dimension of chip : 50 x 50 mm
NOTE: Theoretically, SMD5050 is 3 times brighter than SMD3528.

SMD 5050 are used when you need high illumination for your project area and especially RGB color changing lights. 5050 LED is well suited for lighting up areas that may be subject to high levels of ambient light.Though they produce more heat than smaller chips, it is still drastically lower than other lighting options.

A 3528 SMD LED Array
A 3528 SMD LED Array
 
A SMD LED 5050 Array
A SMD LED 5050 Array

Dimension to Which It Is Used
Dimension to Which It Is Used

Reworking In Your PCB:
Removal of surface-mount device using soldering tweezers
Removal of surface-mount device using soldering tweezers
Defective surface-mount LEDs can be replaced by using soldering irons (for some connections), or using a non-contact rework system. In most cases a rework system is the better choice because SMD work with a soldering iron requires considerable skill, and is not always feasible.


Some Cool DIY Applications Possible For SMD
 LED: 
  Multi Pattern Display Using SMD Array Display: With An SMD array like the below, we can actually make them to display so many patterns( whatever we like ) to display over them.
Various Pattern Display Using SMD Array Display
Various Pattern Display Using SMD Array Display

 SMD LED CLOCK: In similar fashion, the following array can be used to display time, as a Clock!


Hope You Enjoyed Reading our Intro on SMD LEDs. Feel Free To Comment!

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