Many companies are only involved in one part of chip making. For example, huawei, Qualcomm, Apple, Mediatek, only design chips; Companies like TSMC, SMIC and Huahong only make chips, while companies like Ase and CHANGchang only test chips. China's share of closed beta in the world will also jump from 22 percent in 2018 to 32 percent in 2025. The design and manufacture of chip have been concerned by people. Today, I will introduce the last process of chip production - chip encapsulation technology in chip sealing test.
Package refers to the housing used to install semiconductor integrated circuit chips. Using a series of technologies, the chip on the frame layout paste fixed and connected, lead terminal and through the plastic insulating medium potting fixed, constitute the overall three-dimensional structure of the process. This concept is a narrow encapsulation definition. Colloquially, it is to add a shell to the chip and fix it on the circuit board.
More generalized packaging refers to the packaging engineering, the packaging body and the substrate connection fixed, assembly into a complete system or electronic equipment, and ensure the comprehensive performance of the entire system engineering. The first two definitions are combined to form the generalized concept of encapsulation.
Why encapsulate?
Packaging is of great significance. It takes a long process from design to manufacture to obtain an IC chip. However, a chip is quite small and thin, and can be easily scratched and damaged if it is not protected externally. In addition, because of the small size of the chip, it is difficult to install it on the circuit board manually without using a larger housing. This is where encapsulation technology comes in.
The package has the role of placing, fixing, sealing, protecting the chip and enhancing the electric heating performance. It also acts as a bridge between the inner world of the chip and the external circuitry. The contacts on the chip are connected by wires to the pins of the package case, and these pins are connected to other devices through wires on the printed board. Therefore, encapsulation plays an important role in integrated circuits.
First, the role of chip package
1, the protection of
Semiconductor chip production workshops have very strict production conditions control, constant temperature, constant humidity, strict air dust granularity control and strict electrostatic protection measures, exposed chip only in this strict environmental control will not fail. However, the environment we live in is completely impossible to have such conditions. The low temperature may be -40°C, the high temperature may be 60°C, and the humidity may reach 100%. If it is an automobile product, its working temperature may be as high as 120^C or more. At the same time, there are all kinds of external impurities, static electricity and other problems can disturb the fragile chip. Therefore, encapsulation is needed to better protect the chip and create a good working environment for the chip.
2, support
The support has two functions, one is to support the chip, the chip is fixed to facilitate the connection of the circuit, the other is to form a certain shape to support the whole device after the completion of packaging, so that the whole device is not easy to damage.
3, connection
The function of the connection is to connect the electrode of the chip to the external circuit. The pins are used to connect to the external circuit, and the gold wire connects the pins to the chip's circuit. The slide table is used to carry the chip, the epoxy adhesive is used to attach the chip to the slide table, the pins are used to support the entire device, and the plastic body is used to secure and protect.
4, heat dissipation
The enhancement of heat dissipation takes into account that all semiconductor products generate heat when they work, and when the heat reaches a certain limit, it will affect the normal operation of the chip. In fact, the various materials of the package itself can take away a part of the heat, of course, for most of the hot chip, in addition to cooling through the packaging material, but also need to consider an additional metal fin or fan on the chip to achieve better heat dissipation effect.
5. Reliability
Any package needs to form a certain reliability, which is the most important measurement index in the entire package process. The original chip will be damaged when it leaves a certain living environment and needs to be encapsulated. The working life of chip mainly depends on the choice of packaging material and packaging process.
Type and process of encapsulation
There are currently thousands of individual encapsulation types and no unified system to identify them. Some are named for their design (DIP, flat, etc.), some for their structural techniques (laminated, CERDIP, etc.), some by volume, and others by their application.
Chip packaging technology has been through several generations of change, technical indicators advanced generation than a generation, including the ratio of the chip area and packaging area is more and more close, use frequency is higher and higher, the heat resistance performance is getting better and better, and pin number increase, pin spacing decreases, and reduce weight, improve the reliability, it is more convenient to use and so on, are noticeable changes. This article does not cover much here, interested to find and learn about encapsulation types.
Here is the main process of encapsulation:
The process of packaging can be generally divided into two parts, with the process steps before the plastic packaging become the front operation, and the process steps after the molding become the back operation. The basic process includes: wafer thinning, wafer cutting, chip mounting, molding technology, fly burr removal, rib cutting molding, solder coding and other processes, and the following steps are specific to each step:
1, the front paragraph:
Backgrinding: The round mirror (wafer) is thin on the back to reach the thickness needed for packaging. When grinding on the back, tape the front to protect the circuit area. After grinding, remove the tape.
WaferSaw: Paste the circular mirror on the blue film, cut the circular mirror into independent Dice, and then clean the Dice.
Light inspection: check whether there is waste
Chip bonding (DieAttach) : chip bonding, silver paste curing (to prevent oxidation), lead welding.
2, after the paragraph:
Injection molding: prevent external impact, encapsulate the product with EMC(plastic sealing material), and heat hardening at the same time.
Laser typing: engraving the corresponding content on the product. For example: date of production, batch, etc.
High temperature curing: protect IC internal structure and eliminate internal stress.
To overflow material: trim corners.
Electroplating: improve electrical conductivity, enhance weldability.
Section molding to check waste products.
This is a complete chip package process. Chip packaging technology in China has been in the forefront of the world, which provides a good foundation for us to vigorously develop chip. In the next few years, the overall growth of the chip industry will be maintained at more than 30%. This is a very impressive growth rate and means the industry will double in size in less than three years. Such rapid growth will benefit all three segments of the chip industry: design, manufacturing, packaging and testing (" closed test "). I believe that with the efforts of Chinese people, our design and manufacturing level will one day be able to go to the world and lead The Times.