SMTActive Components: Two And Three Terminal Packages & Integrated Circuits

Active Components

• Two-terminal devices

  • Diodes

• Three-terminal devices:

  • SOT Small Outline Transistors

• Integrated Circuits -Dual-in-Line

  • SOIC

  • SSOP

  • TSSOP

  • SOJ

1. Two terminal packages:

Diodes:

Diode is a two-terminal semiconductor device that will allow current to flow through it in only one direction. With the proper voltage polarity across the device, it will act as a conductor. When the voltage polarity is reversed, the device will act as a nonconductor, allowing no current to flow.

2. Three-Terminal Packages:

2.1 Transistors:

The transistor is a solid-state semiconductor device that can be used for amplification, switching, voltage stabilization, signal modulation and many other functions. It allows a variable current, from an external source, to flow between two of its terminals depending on the smaller voltage or current applied to a third terminal. Transistors are made either as separate components or as part of an integrated circuit.

2.2 SOT- Small Outline Transistor:

What is SOT?

SMALL OUTLINE TRANSISTOR SOT package is a rectangular surface mount transistor or diode with three or more gull wings leads. The leads are on two length sides of the package. Popular sizes are the SOT23, SOT143, SOT223 and SOT89.

1. SOT23: SOT23 is a Plastic surface-mounted package with 3 leads.

3. Integrated circuits (Four and more Terminals Packages):

Dual-In-Line:

Dual in-line package (DIP), sometimes called a DIL package, is an electronic device package with a rectangular housing and two parallel rows of electrical connecting pins, usually protruding from the longer sides of the package and bent downward. A DIP is usually referred to as a DIPn, where n is the total number of pins. For example, a microcircuit package with two rows of seven vertical leads would be a DIP14.

3.1 SOIC- Small Outline Integrated Circuit.

Small Outline Integrated Circuit is the standard package for logic ICs and it is the equivalent (although smaller) of the DIL package for leaded components.

3.2 SSOP – Shrink Small Outline Package.

Shrink Small Outline Package is smaller than the SOIC and has a pin spacing of 0.635 mm.

3.3 TSSOP – Thin Shrink Small Outline package.

TSSOP packages are ultra thin SOPs with a package L-Leaded mounting height of less than 1.27 mm, and are suited to ultra-thin electronic equipment such as smart cards.

Type-I

Type-II

3.4 SOJ (Small Out-line J-Leaded Package):

SOJ packages are characterized by J-shaped leads which are drawn out from each package body in two directions, and can be mounted flat. The standard lead pitch is typically 1.27 mm (50 mil).

Type-I