tmp1940cyaf TOSHIBA Semiconductor CORPORATION, tmp1940cyaf Datasheet - Page 33

• Manufacturer Part Number: tmp1940cyaf
• Description: 32-bit Tx System Risc Tx19 Family
• Manufacturer: TOSHIBA Semiconductor CORPORATION

3.5.4
(1) When cleaning circuit boards to remove flux, make sure that no residual reactive ions such
(2) Washing devices with water will not cause any problems. However, make sure that no
(3) Do not rub device markings with a brush or with your hand during cleaning or while the
(4) The dip cleaning, shower cleaning and steam cleaning processes all involve the chemical
(5) Ultrasonic cleaning should not be used with hermetically-sealed ceramic packages such as a
less in order to prevent thermal stress in the device.
Figure 5 shows an example of a recommended temperature profile for surface-mount packages
using solder flow.
Flux cleaning and ultrasonic cleaning
as Na or Cl remain. Note that organic solvents react with water to generate hydrogen
chloride and other corrosive gases which can degrade device performance.
reactive ions such as sodium and chlorine are left as a residue. Also, be sure to dry devices
sufficiently after washing.
devices are still wet from the cleaning agent. Doing so can rub off the markings.
action of a solvent. Use only recommended solvents for these cleaning methods. When
immersing devices in a solvent or steam bath, make sure that the temperature of the liquid
is 50°C or below, and that the circuit board is removed from the bath within one minute.
leadless chip carrier (LCC), pin grid array (PGA) or charge-coupled device (CCD), because
the bonding wires can become disconnected due to resonance during the cleaning process.
Even if a device package allows ultrasonic cleaning, limit the duration of ultrasonic cleaning
to as short a time as possible, since long hours of ultrasonic cleaning degrade the adhesion
between the mold resin and the frame material. The following ultrasonic cleaning conditions
are recommended:
Frequency: 27 kHz
Ultrasonic output power: 300 W or less (0.25 W/cm
Cleaning time: 30 seconds or less
Suspend the circuit board in the solvent bath during ultrasonic cleaning in such a way that
the ultrasonic vibrator does not come into direct contact with the circuit board or the device.
Figure 5 Sample temperature profile for solder flow
29 kHz
(°C)
250
160
140
3 General Safety Precautions and Usage Considerations
60-120 seconds
Time (in seconds)
19
5 seconds
or less
2
or less)