Basic knowledge of integrated circuit packaging TO packaging

What is TO encapsulation?

The full English name of TO is: Transistor Outline, which is a kind of transistor package designed to enable the lead to be molded and used for surface mounting.

What is a transistor?

Transistor is a kind of solid semiconductor device, which has many functions such as detection, rectification, amplification, switching, voltage stabilization, signal modulation, etc. Strictly speaking, transistor generally refers to all single elements based on semiconductor materials, including diodes, triodes, field effect transistors, thyristor, etc. made of various semiconductor materials. Transistors use electrical signals to control themselves, with fast response speed and high accuracy. They can be used for various digital and analog functions, including amplification, switching, voltage stabilization, signal modulation and oscillator. It is small in size, solid and reliable, with minimal power consumption and longer service life. It is often used in amplifiers or electronic control switches.

Classification of transistors

Transistors are mainly divided into two categories: bipolar transistor (BJT) and field effect transistor (FET).

Bipolar transistor (BJT) is a transistor with current amplification function composed of two back-to-back PN structures. Its three poles are composed of N-type and P-type emitter, base and collector respectively. There are two types of NPN-type tube and PNP-type tube:

Field effect transistor (FET) uses the electric field effect of the control input circuit to control the output circuit. Its three poles are source, gate and drain. There are two types of junction FET (JFET for short) and metal-oxide semiconductor FET (MOS for short):

With the application of transistors, the TO packaging technology has also begun to develop. From plastic materials to metal materials, different manufacturers have different names for TO packaging, but the naming rules are composed of packaging code+pin number: for example, TO-220-5, where TO-220 represents the packaging code, and the rear 5 represents its pin number.