As we all know, the packaging industry belongs to the back-end production process of the entire IC production. In this process, for plastic-encapsulated ICs, hybrid ICs or single-chip ICs, there are mainly wafer thinning (grinding), wafer cutting (dicing), core loading (bonding), pressure welding (bonding), packaging (encapsulation), pre-curing, electroplating, printing, post-curing, rib cutting, tube installation, post-sealing testing, etc. Special anti-static equipment is required to eliminate static electricity, such as ion blowers, ion wind rods, etc.

Each process has different requirements for different process environments:

1. The impact of electrostatic factors on IC packaging

First of all, the causes of static electricity can be found everywhere. There are mainly the following reasons:

The building decoration materials of the production workshop are mostly made of high-resistance materials, and the IC production process requires the use of clean workshops or ultra-clean workshops. The particle size of the dust particles is required to change from the previous 0.3μm to 0.1μm, and the dust particle density is about 353/m3. For this reason, in addition to installing various dust collection equipment, inorganic and organic dust-free materials should be used to prevent dust. However, the electrical properties of building materials are not taken into account as an indicator. There is no regulation in the design specifications for clean workshops of industrial enterprises. The main indoor decoration materials used in the clean workshops of IC factories are: polyurethane elastic floor, nylon, hard plastic, polyethylene, plastic wallpaper, resin, wood, white porcelain board, enamel, gypsum, etc. Most of the above materials are polymer compounds or insulators. For example, the resistivity of organic glass is 10^12~10^14Ωcm, and the resistivity of polyethylene is 10^13~10^15ncm, so the conductivity is relatively poor. Static electricity generated for some reason is not easy to leak to the ground through them, thus causing the accumulation of static electricity.

2. Human body static electricity

The different movements and back-and-forth movement of operators in clean rooms cause the soles of their shoes to be in close contact and separation with the ground. The various parts of the human body also move and rub against each other. Whether walking fast, walking slowly, or jogging, static electricity will be generated, which is the so-called walking charge. Static electricity will also be generated when the human body stands up after activities, and when the work clothes worn by the human body come into contact with the surface of the chair and then separate. If the static voltage of the human body cannot be eliminated and it comes into contact with the IC chip, it may cause the IC to break down without knowing it.

3. Static electricity caused by air conditioning and air purification

Since IC production requires to be carried out under the condition of 45-55% RH, air conditioning and air purification are required. The dehumidified air is sent to the clean room through the primary filter, medium filter, high efficiency filter and air duct. Generally, the total air duct wind speed is 8~10m/s, and the inner wall of the air duct is painted. When the dry air and the air duct, the dry air and the filter move relative to each other, static electricity will be generated. It should be noted that static electricity has a sensitive relationship with humidity. In addition, static electricity will be generated during the packaging and transportation of semi-finished products and IC finished products, which is one of the factors of static electricity electrification. Secondly, static electricity is quite harmful to IC. Generally speaking, static electricity has the characteristics of high potential and strong electric field. In the process of static electricity electrification-discharge, transient large current discharge and electromagnetic pulse (EMP) are sometimes formed, generating a wide spectrum electromagnetic radiation field. In addition, compared with conventional electrical energy, static electricity is relatively small. In the natural electrification-discharge process, the electrostatic discharge (ESD) parameters are uncontrollable and it is a random process that is difficult to repeat, so its role is often ignored. Especially in the field of microelectronics technology, the harm it causes to us is alarming. It is reported that the direct economic losses caused by static electricity are as high as several hundred million yuan each year. The harm of static electricity has become a major obstacle to the development of the microelectronics industry.

In the semiconductor device production workshop, the yield rate of IC, especially very large scale integrated circuit (VLSI), will be greatly reduced due to dust adsorbed on the chip. Operators in the IC production workshop all wear clean work clothes. If the human body is static, it is very easy to adsorb dust and dirt. If these dust and dirt are brought to the operation site, it will affect the product quality, deteriorate product performance, and greatly reduce the yield rate of IC. If the radius of the adsorbed dust particles is greater than 100μm, the line width is about 100μm, and the film thickness is below 50μm, it is easy to make the product scrapped.