Toshiba TMPR7901, User Manual

Page: 24 / 309

3 General Safety Precautions and Usage Considerations
3-3
•
When storing printed circuit boards which have devices mounted on them, use a board
container or bag that is protected against static charge. To avoid the occurrence of static charge
or discharge due to friction, keep the boards separate from one other and do not stack them
directly on top of one another.
•
Ensure, if possible, that any articles (such as clipboards) which are brought to any location
where the level of static electricity must be closely controlled are constructed of anti-static
materials.
•
In cases where the human body comes into direct contact with a device, be sure to wear anti-
static finger covers or gloves (suggested resistance value: 10
8 Ω or less).
•
Equipment safety covers installed near devices should have resistance ratings of 10 9
Ω
or less.
•
If a wrist strap cannot be used for some reason, and there is a possibility of imparting friction to
devices, use an ionizer.
•
The transport film used in TCP products is manufactured from materials in which static
charges tend to build up. When using these products, install an ionizer to prevent the film from
being charged with static electricity. Also, ensure that no static electricity will be applied to the
product’s copper foils by taking measures to prevent static occuring in the peripheral
equipment.
3.1.2 Vibration, impact and stress
Handle devices and packaging materials with care. To avoid damage
to devices, do not toss or drop packages. Ensure that devices are not
subjected to mechanical vibration or shock during transportation.
Ceramic package devices and devices in canister-type packages which
have empty space inside them are subject to damage from vibration
and shock because the bonding wires are secured only at their ends.
Plastic molded devices, on the other hand, have a relatively high level
of resistance to vibration and mechanical shock because their bonding
wires are enveloped and fixed in resin. However, when any device or package type is installed in
target equipment, it is to some extent susceptible to wiring disconnections and other damage from
vibration, shock and stressed solder junctions. Therefore when devices are incorporated into the
design of equipment which will be subject to vibration, the structural design of the equipment
must be thought out carefully.
If a device is subjected to especially strong vibration, mechanical shock or stress, the package or
the chip itself may crack. In products such as CCDs which incorporate window glass, this could
cause surface flaws in the glass or cause the connection between the glass and the ceramic to
separate.
Furthermore, it is known that stress applied to a semiconductor device through the package
changes the resistance characteristics of the chip because of piezoelectric effects. In analog circuit
design attention must be paid to the problem of package stress as well as to the dangers of
vibration and shock as described above.
Vibration