In addition to the high-voltage form used by the discharge electrode (discharge needle), the static elimination device can be divided into two categories: AC and DC. In AC, it is divided into high frequency type and common AC type (commercial frequency), and DC is divided into continuous DC type. , DC pulse type.
1. The difference between the DC static elimination device is that positive and negative air ions can be alternately generated on one discharge needle of the AC type discharge device, and the discharge electrode is composed of the discharge needle and the ground electrode, and the discharge electrode of the DC type discharge device is not A grounding electrode is required, and the discharging electrode is composed of positive and negative independent discharge needles. In the absence of external air supply (such as fans, compressed gas, etc.), the DC-type static eliminator is farther away from the AC-type static eliminator. In the case of outside air supply, the static elimination distance depends mainly on the static eliminator. Structure, air volume and the strength of the high voltage power supply.
2. The difference between the DC static elimination devices is that the ion balance is different. The AC type discharge device generates both positive ions and negative ions on the same discharge needle, so even after the discharge needle wears for a long time, the ion balance There will be no major changes, and the ion balance performance is better. DC type discharger Because the discharge needle consists of independent positive and negative electrodes, the ion balance is poor when used at close distances. In addition, the discharge needle is affected by the environment and the degree of contamination of the needle during use, which will affect the balance of ions, especially discharge. After the needle is used for a long period of time, the positive and negative discharge needles are worn to a different extent, and the ion balance cannot be corrected even after washing.
Since the discharge needle will be polluted after long-term use, it directly affects the static elimination performance and ion balance. Therefore, the static elimination electrode part should be cleaned regularly during use. In particular, the DC discharger discharge needle is more susceptible to contamination than the AC type. Electrostatic equipment should be cleaned more frequently, and the degree of wear of the positive and negative discharge needles is different. Regular ion balance detection is required. When the discharge needle is severely worn, the discharge needle should be replaced in time.
General technical requirements for anti-static
Static electricity is like a bacteria. Although it is invisible and intangible, it exists anywhere, anytime. In daily life, such as walking, flipping books, and even air flow, static electricity is generated. When static electricity starts to be generated, the amount of static electricity increases with the continuation of time, but when it reaches a certain level, the amount of static electricity does not increase indefinitely and tends to a certain stable value. When the static electricity accumulated on the surface of the electronic component reaches a stable value, its performance is greatly affected.
The following is a description of the general process requirements for electrostatic protection in electronic manufacturing:
(1) The production area has a stable environment of constant temperature and constant humidity for a long period of time. The general temperature is controlled at 25 ° C, the humidity is controlled at 65%, and special personnel are tested every day and effectively recorded;
(2) Posting the eye-catching electrostatic sensitive device mark, Figure 7 is a variety of anti-static signs. (a) is the mark of the anti-static work area, (b) and (c) are the marks on the anti-static container, the component frame, the transport vehicle, etc.; (d) is the mark of the anti-static treated items and places.
