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SMT / SMD Component Packages
----an overview of the different SMD component packages used for surface mount technology, SMT components

Surface mount technology, SMT includes:
SMT overview
SMD component packages
SMD resistor
SMD resistor markings
MELF SMD resistor
SMD capacitor
Quad Flat Package, QFP
BGA, Ball Grid Array
SMD PLCC
Surface mount technology, SMT components come in a variety of packages.
As surface mount technology has improved many packages have decreased in size. Additionally there is a variety of different SMT packages for integrated circuits dependent upon the interconnectivity required, the technology being used and a variety of other factors.

Standards for surface mount packages
To provide some degree of uniformity, sizes of most SMT components conform to industry standards, many of which are JEDEC specifications. Obviously different SMT packages are used for different types of components, but the fact that there are standards enables activities such as printed circuit board design to be simplified. Additionally the use of standard size packages simplifies the manufacture because pick and place machines can use standard feed for the SMT components, considerably simplifying the manufacturing process and saving costs.
The different SMT packages can be categorised by the type of component, and there are standard packages for each.

Passive rectangular components
These SMT components are mainly resistors and capacitors which form the bulk of the number of components used. There are several different sizes which have been reduced as technology has enabled smaller components to be manufactured and used.

Of these sizes, the 1812, and 1206 sizes are now only used for specialized components or ones requiring larger levels of power to be dissipated The 0603 and 0402 SMT sizes are the most widely used.

Tantalum capacitors SMD packages
As a result of the different construction and requirements for tantalum SMT capacitors, there are some different packages that are used for them. These conform to EIA specifications.

Semiconductor SMD packages
There is a wide variety of SMT packages used for semiconductors including diodes, transistors and integrated circuits. The reason for the wide variety of SMT packages for integrated circuits results from the large variation in the level of interconnectivity required. Some of the main packages are given below

Transistor & diode packages
SMD transistors and diodes often share the same types of package. While diodes only have two electrodes a package having three enables the orientation to be correctly selected.

SMD diodes on a printed circuit
Although a variety of SMT transistor and diode packages are available, some of the most popular are given in the list below.
SOT-23 - Small Outline Transistor:   This is SMT package has three terminals for a diode of transistor, but it can have more pins when it may be used for small integrated circuits such as an operational amplifier, etc. It measures 3 mm x 1.75 mm x 1.3 mm.
SOT-223 - Small Outline Transistor:   This package is used for higher power devices. It measures 6.7 mm x 3.7 mm x 1.8 mm. There are generally four terminals, one of which is a large heat-transfer pad.

Integrated circuit SMD packages
There are many forms of package that are used for SMD ICs. Although there is a large variety, each one has the areas where its use is particularly applicable.
SOIC - Small Outline Integrated Circuit :   This SMD IC package has a dual in line configuration and gull wing leads with a pin spacing of 1.27 mm
SOP - Small Outline Package:   There are several versions of this SMD package:

TSOP - Thin Small Outline Package:   This SMD package is thinner than the SOIC and has a smaller pin spacing of 0.5 mm
SSOP - Shrink Small Outline Package:   This package has a pin spacing of 0.635 mm
TSSOP - Thin Shrink Small Outline Package:  
QSOP - Quarter-size Small Outline Package:   It has a pin spacing of 0.635 mm
VSOP - Very Small Outline Package:   This is smaller than the QSOP and has pin spacing of 0.4, 0.5, or 0.65 mm.
QFP- Quad flat pack:   The QFP is the generic type of flat package for ICs. There are several variants as detailed below.

LQFP - Low profile Quad Flat Pack:   This package has pins on all four sides. Pin spacing varies according to the IC, but the height is 1.4 mm.
PQFP - Plastic Quad Flat Pack:   A square plastic package with equal number of gull wing style pins on each side. Typically narrow spacing and often 44 or more pins. Normally used for VLSI circuits.
CQFP - Ceramic Quad Flat Pack:   A ceramic version of the PQFP.
TQFP - Thin Quad Flat Pack:   A thin version of the PQFP.
Read more about the QFP - Quad Flat Pack
BGA - Ball Grid Array:   A package that uses pads underneath the package to make contact with the printed circuit board. Before soldering the pads appear as solder balls, giving rise to the name.
By placing the pads underneath the package there is more room for them, thereby overcoming some of the problems of the very thin leads required for the quad flat packs. The ball spacing on BGAs is typically 1.27 mm. Read more about the Ball Grid Array
PLCC - Plastic Leaded Chip Carrier:   This type of package is square and uses J-lead pins with a spacing of 1.27 mm. Read more about the PLCC Plastic Leaded Chip Carrier

SMD package applications
SMT surface mount technology packages are used for most printed circuit designs that are going to be manufactured in any quantity. Although it may appear there are a relatively wide number of different packages, the level of standardization is still sufficiently good. In any case it arises mainly out of the enormous variety in the function of the components.

Standard Recovery Rectifiers 50/60 Hz Rectification--> Polarity protection
Fast Recovery Rectifiers--> Rectification of medium frequencies
Ultrafast Recovery Rectifiers 50ns < trr < 100ns--> Rectification of high frequency
Superfast Recovery Rectifiers 15ns < trr < 75ns--> Rectification of high frequencies
Schottky Barrier Diode Output rectification--> Polarity protection
Zener Diodes--> Voltage stabilization
Transient Voltage Suppressor Diodes--> Overvoltage Protection
Current Limiting Diode--> Constant current source
Small Signal Diodes--> Signal processing
Single Phase Bridge Rectifiers--> Single phase input rectification
3 Phase Bridge Rectifiers--> Three phase input rectification
High Voltage Rectifiers--> Rectification of high voltages
Arrays--> Combination of diodes in SIL package
Bipolar Transistors--> Control and signal processing
Field Effect Transistors--> Control and signal processing
Diacs--> Trigger diodes

At the maximum lead wire temperature of 260°C, the soldering time must not exceed 10s. This assumes that the solder joint is spaced not less than 5mm from the case. If the joint is spaced less than 5mm, the soldering time must be reduced to 3s.
 Dip or Wave Soldering
Leaded devices: At the maximum soldering temperature of 260°C, the soldering time must not exceed 10s (or two times 5s at dual wave soldering). The soldering joint should be spaced not less than 1.5mm from the case.
 SMD devices: The soldering time must not exceed 10s at 260°C when the device is submerged completely into the solder. At dual wave soldering, this corresponds to two times 5s.
 Reflow Soldering
For reflow soldering of SMD devices the maximum admissible solder temperature is 260°C, for package outlines up to SMC/DO-214AB and peak time not exceeding 5s. Time above 255°C must not exceed 30s. For bigger case outlines, the solder temperature must be reduced.

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What is a Switching Diode?
Switching diodes are a single p-n diode in a discrete package. A switching diode provides the same functionality as a switch. It has high resistance below the specified applied voltage similar to an open switch, whereas above that voltage it changes in a sudden way to the low resistance of a closed switch. Switching diodes are used in devices such as ring modulation.

Types of Switching Diodes:
There are many different kinds of switching diodes. At Topdiode, we supply many of the most common types categorized by power dissipation, maximum reverse recovery time, maximum reverse voltage, maximum average forward current, packaging type and maximum peak current. The most common values for power dissipation are 200 mW, 250 mW, 350 mW and 500 mW. Please refer to our products page.

Applications for Switching Diodes:
The switching diode is the most basic function of almost every electronic application. Switching diodes are also used in high-speed rectifying applications, such as in radiofrequency receivers. Applications also include high-speed switching, general-purpose switching and reverse polarity protection in the consumer, automotive, and telecommunication industry.

Switching Diodes from Topdiode:

What is a Bridge Rectifier?  

A bridge rectifier is an arrangement of four or more diodes in a bridge circuit configuration which provides the same output polarity for either input polarity. It is used for converting an alternating current (AC) input into a direct current (DC) output. A bridge rectifier provides full-wave rectification from a two-wire AC input, therefore resulting in lower weight and cost when compared to a rectifier with a 3-wire input from a transformer with a center-tapped secondary winding.
Types of Bridge Rectifiers
There are many different kinds of bridge rectifiers at Topdiode, we supply many of the most common types categorized by maximum average rectified current, maximum reverse voltage, maximum peak current, forward voltage, packaging type and maximum reverse current.
 The most common sizes for maximum average rectified current are 1A, 1.5 A, 4 A, 25 A and 35 A. We also carry bridge rectifiers with maximum average rectified current as high as 1000 A. Forward voltage can range from 450 mV to 1.1 kV, with the most common bridge rectifier semiconductor chips having a forward voltage of 1.1 V or 1 V.
Bridge Rectifiers from Topdiode.
 Applications for Bridge Rectifiers:
The primary application of bridge rectifiers is to transform an AC supply into DC power. All electronic devices require direct current, so bridge rectifiers are used inside the power supplies of almost all electronic equipment. Bridge rectifiers are also used for detecting the amplitude of modulated radio signals. The signal may be amplified before it is detected. If it is not, then a very low voltage drop diode or a diode biased with a fixed voltage must be used. Rectifiers are also used to supply polarized voltage for welding applications. Control of the output current is required in such circuits, and this may be achieved by replacing some of the diodes in a bridge rectifier with thyristors, which are diodes whose voltage output can be regulated by switching on and off with phase fired controllers.
Bridge Rectifier from Topdiode
Topdiode has a full selection of bridge rectifier chips that can be used to design a full wave bridge rectifier circuit, half wave rectifier or any other type of circuits that may require a bridge rectifier. 

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What is a Zener Diode?

Zener diodes are a special kind of diode which permits current to flow in the forward direction. What makes them different from other diodes is that Zener diodes will also allow current to flow in the reverse direction when the voltage is above a certain value. This breakdown voltage is known as the Zener voltage. In a standard diode, the Zener voltage is high, and the diode is permanently damaged if a reverse current above that value is allowed to pass through it. Zener diodes are designed in a way where the Zener voltage is a much lower value. There is a controlled breakdown which does not damage the diode when a reverse current above the Zener voltage passes through a Zener diode.
Types of Zener Diodes
There are many different kinds of Zener diodes. Topdiode supply many of the most common types categorized by power dissipation, nominal working voltage, forward (drive) current, forward voltage, packaging type and maximum reverse current. The most common values for nominal working voltage are 5.1 V, 5.6 V, 6.2 V, 12 V and 15 V. Forward (drive) current can have a range from 200 uA to 200 A, with the most common forward (drive) current being 10 mA or 200 mA.
Applications for Zener Diodes
Zener diodes can be found in several applications. Some of these are: voltage stabilizers or regulators (in shunt mode), surge suppressors for device protection, peak clippers, switching operations, reference elements and in meter protection applications. The constant reverse voltage of a Zener diode renders it a very useful component in regulating the output voltage against variations in the load resistance or variations in the input voltage from an unregulated power supply. The current through the Zener diode will change in order to keep the voltage within the threshold limits of Zener action and the maximum power that it can dissipate.

Zener Diodes in Topdiode

What is a Fast Rectifier?

Rectification is the most popular use for diodes. Fast rectifiers convert alternating current (AC) to direct current (DC). They only allow one-way flow of electrons. Rectifiers have many uses and are often found serving as components of high-voltage direct current power transmission systems and DC power supplies. Fast rectifier diodes feature very low reverse recovery time, very low switching losses and low noise turn-off switching.
Types of Fast Rectifiers
There are several different kinds of fast rectifiers. At Topdiode we offer many of the most common types categorized by maximum average rectified current, maximum reverse recovery time, maximum reverse current, maximum reverse voltage, packaging type and forward voltage. The most common sizes for forward voltage are 1.1 V, 1.2 V and 1.3 V.
 Applications for Fast Rectifiers:
Fast rectifier diodes are found in strobe applications that require high surge resistance as well as in the industrial, commercial and automotive sectors. High voltage resistance fast rectifier diodes, which are ideal for use in switching power supplies of all types, feature fast switching speeds along with improved efficiency and reduced loss. Fast rectifiers are also used in PDPs (sustain circuits) and PFC circuits. Also, detectors of radio signals serve as rectifiers.

Fast Recovery Rectifiers in Topdiode

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What is a Schottky Diode?

A Schottky diode, also known as a hot carrier diode, is a semiconductor diode which has a low forward voltage drop and a very fast switching action. There is a small voltage drop across the diode terminals when current flows through a diode. A normal diode will have a voltage drop between 0.6 to 1.7 volts, while a Schottky diode voltage drop is usually between 0.15 and 0.45 volts. This lower voltage drop provides better system efficiency and higher switching speed. In a Schottky diode, a semiconductor–metal junction is formed between a semiconductor and a metal, thus creating a Schottky barrier. The N-type semiconductor acts as the cathode and the metal side acts as the anode of the diode. This Schottky barrier results in both a low forward voltage drop and very fast switching.
Applications for Schottky Diodes:
Schottky diodes are useful in voltage clamping applications and prevention of transistor saturation due to the higher current density in the Schottky diode. Also, because of the low forward voltage drop in a Schottky diode, less energy is wasted as heat, therefore making them an efficient choice for applications that are sensitive to efficiency. Because of this, they are used in stand-alone photovoltaic systems in order to prevent batteries from discharging through the solar panels at night as well as in grid-connected systems containing multiple strings connected in parallel. Schottky diodes are also used as rectifiers in switched-mode power supplies. 

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What is a Standard Rectifier?

A rectifier diode lets electrical current flow in only one direction and is mainly used for power supply operation. Rectifier diodes can handle higher current flow than regular diodes and are generally used in order to change alternating current into direct current. They are designed as discrete components or as integrated circuits and are usually fabricated from silicon and characterized by a fairly large P-N-junction surface. This results in high capacitance under reverse-bias conditions. In high-voltage supplies, two rectifier diodes or more may be connected in series in order to increase the peak-inverse-voltage (PIV) rating of the combination.

Types of Standard Rectifiers
There are many different kinds of standard rectifiers and at Topdiode, we offer many of the most common types categorized by maximum reverse current, maximum peak current, maximum reverse voltage, forward voltage, packaging type and maximum average rectified current.

The most common sizes for maximum average rectified current are 1 A, 1.5 A, 3 A, 5 A and 6 A. We also carry standard rectifiers with maximum average rectified current as high as 400 A. Forward voltage can range from 1.1 mV to 1.3 kV, with the most common standard rectifier semiconductor chips having a forward voltage of 1.1 V or 1.15 V.

Applications for Standard Rectifiers:
Standard rectifiers can be found regulating the power in computers and the electrical power in motor vehicles. They can also be used in battery chargers for rechargeable batteries, computer power supplies and vehicle batteries. Also, while rectifier diodes are often used for AC to DC conversion, diodes with rectifying characteristics are found in other uses than in electronics. For example, a diode is used in the detector of radios in order to perform radio demodulation.

Standard diode rectifiers in Topdiode:

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What is a Current Limiting Diode?

A current limiting diode, also known as a CLD, current regulating diode, diode connected transistor or constant current diode, regulates or limits current over a wide voltage range. Current limiting diodes consist of a JFET with the gate shorted to the source and function like a two-terminal current limiter or current source, much like voltage limiting Zener diodes. They allow a current passing through them to rise to a certain value and then level off at a specific value. Contrary to Zener diodes, these diodes keep the current constant instead of keeping the voltage constant. Current limiting diodes keep the current which is flowing through them unchanged when the voltage changes.
Applications for Current Limiting Diodes:
Current limiting diodes offer high performance and simplicity characteristics compared with bipolar transistors. They offer versatility in several circuit applications and superior performance regarding dynamic and impedance temperature drift. Some examples of devices using current limiting diodes are waveform generator circuits, timing circuits and battery chargers. Current limiting diodes can also be found as a constant current source for driving LEDs and can be used in order to replace holding coils in telephone connection devices.

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