Hitachi AP1 Data Book page 32

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4.
PRECAUTIONS
4.1 Storage
To prevent deterioration of electrical characteristics, solder-
ability, appearance or structure, Hitachi recommends semicon-
ductor devices be stored as follows:
(I)
Store in ambient temperatures of 5 to 30°C, with a relative
humidity of 40 to 60%.
(2) Store in a clean, dust- and active gas-free environment.
(3) Store in conductive containers to prevent static electricity.
(4) Store without any physical load.
(5) When storing devices for an extended period, store in an
unfabricated form, to minimize corrosion of pre-formed
lead wires.
(6) Unsealed chips should be stored in a cool, dry, dark and
dust-free environment. Assembly should be performed
within 5 days of unpacking. Devices can be stored for up to
20 days in dry nitrogen gas with a dew point at -30° C or less.
(7) Prevent condensation during storage due to rapid tempera-
ture changes.
4.2 Transportation
General precautions for electronic components are appli-
cable in transporting semiconduCtors, units incorporating semi-
conductors, and other similar systems. In addition, Hitachi
recommends the following:
(I) When transporting semiconductor devices or printed circuit
boards, minimize mechanical vibration and shock. Use con-
tainers or jigs which will not induce static electricity as a
result of vibration. Use of an electrically conductive con-
tainer or aluminum foil is recommended.
(2) To prevent device deterioration from clothing-induced static
electricity, workers should be properly grounded while hand-
ling devices. Use of a I M ohm resistor is recommended to
prevent electric shock.
(3) When transporting printed curcuit boards containing semi-
conductor devices, suitable preventive measures against
static electricity must be taken. Voltage build-up can be
avoided by shorting the card-edge terminals. When a belt
conveyor is used, apply some surface treatment to prevent
build-up of electrical charge.
(4) Minimize mechanical vibration and shock when trans-
porting semiconductor devices or printed circuit boards.
30
4.3 Handling for Measurement
Avoid static electricity, noise and voltage surge when meas-
uring or mounting devices. Precaution should be taken against
current leakage through terminals and housings of curve tracers,
synchroscopes, pulse generators, and DC power sources.
When testing devices, prevent voltage surges from the tester,
attached clamping circuit, and any excessive voltage possible
through accidental contact.
In inspecting a printed circuit board, power should not be
applied if any solder bridges or foreign matter is present.
4.4 Soldering
Semiconductor devices should not be exposed to high
temperatures for excessive periods. Soldering must be performed
consistent with temperature conditions of 260° C for 10 seconds,
350° C for 3 seconds, and at a distance of I to 1.5mm from the end
of the device package.
A soldering iron with secondary voltage supplied through a
grounded transformer is recommended to protect against
leakage current. Use of alkali or acid flux, which may corrode the
leads, is not recommended.
4.5 Removing Residual Flux
Detergent or ultrasonic removal of residual flux from circuit
boards is necessary to ensure system reliability. Selection of
detergent type and cleaning conditions are important factors.
When chloric detergent is used for plastic packaged devices,
care must be taken against package corrosion. Extended
cleaning periods and excessive temperature conditions can cause
the chip coating to swell due to solvent permeation. Hitachi
recommends use of Lotus and Dyfron solvents. Trichloroeth-
ylene solvent is not suitable.
The following conditions are advisable for ultrasonic
cleaning:
Frequency: 28 to 29 k Hz (to avoid device resonation)
• Ultrasonic output: 15W/f
• Keep devices from making direct contact with power
generator
• Cleaning time: Less than 30 seconds.