Discrete devices refer to electronic devices with separate functions that cannot be disassembled. Discrete device is mainly composed of chip, / lead frame, encapsulation shell of several parts, including chip decision device features, such as rectifier, regulator, switches, protection, etc., lead/framework implementations chips with external circuit connections and the export quantity of heat, encapsulation shell is to provide protection for chip and internal structure, to ensure the steady implementation of its functions, and is associated with cooling core properties such as height.
Product classification of discrete devices
According to the chip structure and function, discrete semiconductor devices can be divided into diodes, triodes, and devices (such as rectifier Bridges) connected by them in certain ways. Semiconductor industry started in the 1950s, in the course of development, semiconductor diode, bipolar transistor (BJT), field effect transistor (POWER-MOSFET), insulated gate bipolar transistor (IGBT) and so on have appeared, generally bipolar transistor, field effect transistor and insulated gate bipolar transistor collectively referred to as the transistor.
With the gradual development of semiconductor industry, the current demand for chip supply mA level, product yield and the cost restriction of small power device integration, downstream products in semiconductor discrete devices volume requirements increasingly demanding problem gradually highlights, diode and triode, which face break the development bottleneck in manufacturing process needs.
To solve the above problems, the concept of "small signal device" with small volume and small current was listed separately, and a series of professional process methods were formed for the production of various diodes and triodes.
With the emergence of the concept of small signal devices, discrete semiconductor devices are divided into two categories of small signal devices and power devices according to the power and current indicators: WSTS also defines small signal devices as discrete devices with dissipation power less than 1W (or rated current less than 1A), while discrete devices with dissipation power less than 1W (or rated current less than 1A) are classified as power devices. The latest "White Paper on Power Semiconductor Discrete Device Industry and Standardization (2019 edition)" released by China Institute of Electronic Technology Standardization in November 2019 divides discrete devices into small signal devices and power devices. Therefore, it is a common classification method to divide discrete devices according to power and current.
There are also significant differences between small signal devices and power devices in production process and product application.
Small signal device chip size and packaging size are small, the production operation and mechanization automation requirements are very high control precision, and weak due to the product components, need good protection in the process of production and at the same time the electrical parameter values are relatively small, so the test system can quickly discern the tiny power change, has the high testing precision.
Small signal discrete device power rating is low, can satisfy the functional requirements of small current circuit, with the resistor, capacitor, inductor, and other components of the combination of reasonable connection, can constitute a circuits with different functions, these circuits can be realized to control the opening and closing of the circuit and postproduction, built for signal modulation wave, clipping, clamping, Voltage stabilization and pulse, electrostatic protection and other functions of the circuit.
However, the chip size and package size of power devices are relatively large, which requires that the chip and frame have good contact, the package body has good heat dissipation ability, the package stress should be as small as possible, the test process can provide large current and high voltage, and automatic comparison and screening under different test parameters. Because the power device is mainly used for power conversion and power control circuit in the high power (usually refers to the current is tens to thousands of ampere, voltage is hundreds of volts above).
Due to the above-mentioned differences, in the process of the gradual professional development of the semiconductor industry, the differences in the production process and product application of electronic components exceed their differences in chip structure and function, and the concepts of small signal devices and power devices have gradually been widely accepted.