3 General Safety Precautions and Usage Considerations
3-14
•
For surface-mount packages, complete soldering within 5 seconds at a temperature of 250°C or
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.
5 s
or less
60-120 s
(°C)
250
160
140
P
ack
age surface tem
perature
Time (s)
Figure 5 Sample temperature profile for solder flow
3.5.4
Flux cleaning and ultrasonic cleaning
(1)
When cleaning circuit boards to remove flux, make sure that no residual reactive ions such 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.
(2)
Washing devices with water will not cause any problems. However, make sure that no
reactive ions such as sodium and chlorine are left as a residue. Also, be sure to dry devices
sufficiently after washing.
(3)
Do not rub device markings with a brush or with your hand during cleaning or while the
devices are still wet from the cleaning agent. Doing so can rub off the markings.
(4)
The dip cleaning, shower cleaning and steam cleaning processes all involve the chemical
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.
(5)
Ultrasonic cleaning should not be used with hermetically-sealed ceramic packages such as a
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
∼
29 kHz
Ultrasonic output power: 300 W or less (0.25 W/cm
2
or less)
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.
Summary of Contents for TMPR7901
Page 1: ...TX System RISC TX79 Family TMPR7901 Symmetric 2 way superscalar 64 bit CPU ...
Page 14: ...Handling Precautions ...
Page 15: ......
Page 17: ...1 Using Toshiba Semiconductors Safely 1 2 ...
Page 41: ...4 Precautions and Usage Considerations 4 2 ...
Page 42: ...TX7901 User s Manual Rev 6 30T November 2001 DOCUMENT NUMBER M 99 00004 07 ...
Page 43: ......
Page 259: ...Chapter 13 Removed TX7901 User s Manual Rev 6 30T Nov 2001 13 1 13 Removed ...
Page 260: ...Chapter 13 Removed TX7901 User s Manual Rev 6 30T Nov 2001 13 2 ...