1. Requirements for vacuum SMT nozzle in mounting
(1) No material throwing (throwing rate is within the allowable range).
(2) No slippage (insufficient vacuum suction will cause the components to slide in motion after detection).
(3) No stickiness (the components are reliably separated from SMT nozzle after the components are installed in place).
2. Basic principle of vacuum SMT nozzle
The principle of vacuum suction is to use the force formed by the vacuum system and atmospheric pressure difference to realize the object grasping and moving. This method of using pressure difference to fix or move objects has many applications in daily life, such as vacuum cleaner, vacuum adsorption hook and cupping cupping of traditional Chinese medicine.
(1) Atmospheric pressure and atmospheric pressure
According to the principle of fluid mechanics, all objects in the earth's atmosphere will be affected by air gravity. This force is the action of atmospheric pressure, and the atmospheric pressure per unit area is the atmospheric pressure. The standard atmospheric pressure on the ground (1 ATM) is about equal to the pressure produced by 760 mm high mercury column (mmHg). Different pressure units are used in different fields, countries and regions
(2) Vacuum and vacuum degree
Generally speaking, vacuum refers to a state in which the gas pressure is lower than atmospheric pressure, rather than a "vacuum" without air at all. In other words, the gas in vacuum is thinner than that in atmospheric pressure. A measure of the degree of rarefaction of a gas in a vacuum state is expressed by "vacuum degree". Conventionally, a high degree of vacuum means that the gas pressure is much lower than the atmospheric pressure; a low vacuum degree means that the gas pressure is less than that of the atmospheric pressure.