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Principles and Measures of Electrostatic
Protection
Damage of Static Electricity
to Electronic Components and Protection Principles.
The damage of static electricity to electronic
components varies with the type of electronic components .The minimum
static voltage of 100V can damage them.Due tl the trend lf the integration
of electronic components,the corresponding static voltage is required
to be lower accordingly.
The static voltage induced by a human body
is typically more then 2-4KV.It is caused by the slight movement
of the human body or the friction lf the human body wigh an insulation
object .This means if the static potential contacts any IC,it will
be damaged ,this risk dxists in any operation environment without
electrostatic protection,static damage to IC happens not only in
the manufacturing process of electronic components but also during
the assembling and shipping of IC.
To solve the above problem ,the following
measures can be taken for electrostatic protection:
1.Electrostatic protection on the operation
site :All static-sensitive components must be operated in an anti-static
work area;
2.Electrostatic protection of human bodies:Operators
should wear anty-static work clothes,gloves,shoes,capsand anty-static
wrist strips;
3.Electrostatic protection during storage
and shipping:Static-sensitive components must not be stored and
shipped in the condition with electric charge.
To realize the above functions ,the basic
way is to reduce the voltage of charged objects to the sage value
required by the desingn or lower than that i.e.Thecharge (Q)and
the resistance (R)must be low and the static capacity(C)must be
high in the following epuations.
V=IR
Q=CV
Where V:voltage;Q:charge I:current,C:static
capacity and R:resistance.
Of course,it is not true that the lower
the resistance is ,the better it will be Particularly,in the anti-static
area of a larger site ,the material should be selected when the
safety measures for electric leakage and so on are taken into consideration.
Anti-static Measures
Check and install IC anti-static
operation site.The anti-static measures in this process aims to
set the operation site including human bodies at an epuipotential.The
specific method is as follows:
1.Ground an l-megohm resistor after it is
connected through.Anti-static wrist strip should be worn during
the operation;
2.Ground test instruments,tools and irons;
3.Lay anti-static table-pad onto the operating
table ,then ground it;
4.Operators should wear anti-static work
clothes and shoes;
5.Lay out anti-static floor or conductive
rubber pads on the ground;
6.An equipotential should be maintained
during IC transportation and packaging.
Cheking Period of Anti-static Performance
and Matters Needing Attention
Check anti-static
table pads,floor,work shoes,work cloghes and turnover containers
at least once every month and anti-static wrist strips,blast guns,blowers
and instruments etc once a day.
When checking,factors
such as temperature and humidity etc should be tacen into considration.
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