1.HBM: Human Body Model, mannequin:

 

Human body of this model token is live discharge of osculatory parts of an apparatus, rb is resistor of equivalent human body, cb is capacitance of equivalent human body. Equivalent circuit pursues as follows. The ESD grade of model of HBM of parts of an apparatus gave out at the same time in the graph.

 

Graph of circuit of ESD mannequin equivalent reachs its ESD order and degree

 

2.MM: Machine Model, machine model:

 

The equivalent circuit of machine model and mannequin are similar, but equivalent capacitance (Cb) is 200pF, equivalent resistor is 0, the difference of machine model and mannequin is bigger, actually of the machine store change of electric electric capacity is bigger, but the unity for the description, take 200pF. Because when the model discharges, the machine does not have resistor, and store electric electric capacity is more than human body mode, the coequal voltage harm to parts of an apparatus, machine mode is ambitious at mannequin.

 

Graph of circuit of equivalent of ESD machine model reachs its ESD order and degree

 

3.CDM: Charged Device Model, charge model of parts of an apparatus:

 

Semiconductor device basically uses 3 kinds to enclose type (metal, pottery and porcelain, plastic) . They are being assembled, deliver, experiment, test, carry in reaching the process that put store, as a result of envelope and other insulating material (the polybag that if pack,uses, deliver used plastic container to wait) grind each other, can make envelope electrified. Itself of parts of an apparatus collects lay aside charge as a plate of capacitor. When CDM model is based on electrified already parts of an apparatus to pass pin and ground contact namely, produce what right discharge causes invalidation of parts of an apparatus and build, parts of an apparatus is electrified the model is as follows:

 

ESD charges graph of circuit of equivalent of model of parts of an apparatus and its ESD grade

 

The ESD grade of parts of an apparatus presses above commonly 3 kinds of models check, major ESD has the ESD data of parts of an apparatus on manual of sensitive parts of an apparatus, what give out commonly is HBM and MM.

 

The ESD data that passes parts of an apparatus or appliance can know the ESD character of parts of an apparatus, but want to notice, the ESD characteristic difference of every pin of parts of an apparatus is bigger, the ESD voltage of certain pin will be particularly low, generally speaking, high speed port, tall block inputs port, voltage of imitate port ESD will be lower.

 

ESD defends is project of a system, need each link to carry out overall control. Next graphs are the flow chart that an ESD defends:

 

ESD defends design flow chart

 

ESD defends the design can be divided defend for veneer design, system defends design, treatment environment design and applied environment defend design, veneer defends the design can raise veneer ESD level, those who reduce a system to design difficulty and system to assemble is electrostatic defend requirement. When systematic design still cannot satisfy a requirement, need undertakes applied an environment to design defending designing. When ESD sensitive parts of an apparatus is installing couplet and whole set outfit, ESD direct to load of the environment arrives parts of an apparatus, it is crucial that the ESD that machines an environment so defends.

 

The osculatory discharge of general and overall, veneer, interface should achieve ±2000V(HBM) above defend requirement. The ESD of parts of an apparatus defends the design is to be below the condition that parts of an apparatus cannot satisfy ESD environment to ask, the ESD energy that is added to parts of an apparatus through attenuation achieves the goal that protects parts of an apparatus. ESD is charge discharge, have voltage tall, the characteristic with short duration, according to these characteristics, ESD energy attenuation can pass voltage to connect filter wave, belt limitation, electric current limitation, high to connect the means such as filter wave to come true, the form that place protects circuit in case is varied, here is not listed one by one.