Basic knowledge of integrated circuit packaging Overview of packaging

The integrated circuit is the core of the information technology industry, and is a strategic, basic and pilot industry that supports economic and social development and ensures national security. In recent years, the global position of China's electronic information industry has been rapidly improved, and the industrial chain has become increasingly mature, providing a good opportunity for the development of China's integrated circuit industry. In 2014, the State Council issued the "National Integrated Circuit Industry Development Promotion Program", which defined the main tasks of China's integrated circuit industry development, and established the National Integrated Circuit Industry Development Leading Group and the National Integrated Circuit Industry Investment Fund, which further highlighted the importance of integrated circuit development. The integrated circuit is the core of the information technology industry, and is a strategic, basic and pilot industry that supports economic and social development and ensures national security. In recent years, the global position of China's electronic information industry has been rapidly improved, and the industrial chain has become increasingly mature, providing a good opportunity for the development of China's integrated circuit industry. In 2014, the State Council issued the "National Integrated Circuit Industry Development Promotion Program", which defined the main tasks of China's integrated circuit industry development, and established the National Integrated Circuit Industry Development Leading Group and the National Integrated Circuit Industry Investment Fund, which further highlighted the importance of integrated circuit development.

What is an integrated circuit?

Integrated circuit, referred to as IC, is a kind of micro electronic device or component. It refers to the use of a certain process to interconnect the transistor, resistor, capacitor, inductor and other components needed in a circuit and wiring, and then make them on a small or several small semiconductor chips or dielectric substrates, and then package them in a shell to become a micro structure with the required circuit functions.

The inventors of integrated circuits are Jack Kilby (integrated circuits based on germanium (Ge)) and Robert Noyes (integrated circuits based on silicon (Si)). Today, most of the semiconductor industry uses silicon-based integrated circuits. With the development of integrated circuits, their structures and functions become more and more diversified. As the basis and important part of integrated circuits, packaging technology also develops.

What is encapsulation?

The English name of packaging is Package, which means that the bare integrated circuit (Die) produced by the foundry is placed on a substrate that plays a bearing role, leads out the pins, and then fixes the packaging into a whole.

Take DIP packaging as an example: after passing the test, the bare chip (Die) drawn on the wafer will be placed tightly on the substrate for supporting and fixing (there is also a layer of material with good heat dissipation on the substrate), and then the metal contact point on Die will be connected with the external pin by welding with multiple metal wires, and then embedded with resin, sealed with plastic shell to form the chip as a whole.

The packaging materials were first metal, then ceramic, and finally plastic. According to industry statistics, metal packaging accounts for 6-7%, ceramic packaging accounts for 1-2%, and plastic packaging accounts for more than 90%. Metal and ceramic packaging is mostly used in harsh environments, such as military, aerospace and other fields, and packaging is "empty", that is, packaging does not contact with the chip.

The role of encapsulation

Packaging not only plays the role of installing, fixing, sealing, protecting the chip and enhancing the electric heating performance, but also connects to the pins of the packaging shell with wires through the contacts on the chip. These pins are connected with other devices through the wires on the PCB (Print Circuit Board), thus realizing the connection between the internal chip and the external circuit. Because the material of the chip is Si, which is oxidized to form silicon dioxide in the air, it must be isolated from the outside to prevent the corrosion of the chip circuit caused by impurities in the air and the decline of the electrical performance. On the other hand, the packaged chip is also easier to install and transport. In short, the role of encapsulation: 1. Physical protection. 2. Electrical connection. 3. Standardization.

Development and trend of packaging

From metal packaging in the 1960s, such as TO packaging, to dual-inline packaging in the 1970s, such as DIP packaging, to SMT (Surface Mount Technology) packaging in the 1980s, such as SOP, PLCC, QFP, and to area-array packaging in the 1990s, such as BGA, and to the current system-level packaging, such as CSP, SIP, etc. The development of packaging has experienced three major innovations: the first was from pin insertion packaging to surface mount packaging in the 1980s, which greatly improved the assembly density on printed circuit boards; The second was the appearance of spherical rectangular positive packaging in the 1990s, which not only met the market demand for high pins, but also greatly improved the performance of semiconductor devices; Wafer level packaging, system packaging and chip packaging are the products of the third innovation, which aims to minimize packaging.

It is not difficult to see that the development trend of packaging is constantly developing in the direction of "small and light":

Short. The pins should be as short as possible to reduce delay, and the pin spacing should be as far as possible to ensure no interference with each other and improve performance.

Small. The ratio of chip to packaging area should be as close as 1:1 to improve packaging efficiency.

Light. Lightweight and convenient for transportation.

Thin. Based on the requirements of heat dissipation, the thinner the package, the better.