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参数资料
| 型号： | SAA5491H/NNN |
| 厂商： | NXP SEMICONDUCTORS |
| 元件分类： | 微控制器/微处理器 |
| 英文描述： | 8-BIT, MROM, 12 MHz, MICROCONTROLLER, PQFP80 |
| 封装： | 14 X 20 MM, 2.80 MM HEIGHT, PLASTIC, SOT-318-2, QFP-80 |
| 文件页数： | 65/72页 |
| 文件大小： | 498K |
| 代理商： | SAA5491H/NNN |
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1998 Dec 14
68
Philips Semiconductors
Preliminary specication
Economy teletext and TV microcontrollers
SAA5x9x family
18 SOLDERING
18.1
Introduction
This text gives a very brief insight to a complex technology.
A more in-depth account of soldering ICs can be found in
our
“Data Handbook IC26; Integrated Circuit Packages”
(document order number 9398 652 90011).
There is no soldering method that is ideal for all IC
packages. Wave soldering is often preferred when
through-hole and surface mount components are mixed on
one printed-circuit board. However, wave soldering is not
always suitable for surface mount ICs, or for printed-circuit
boards with high population densities. In these situations
reflow soldering is often used.
18.2
Through-hole mount packages
18.2.1
SOLDERING BY DIPPING OR BY SOLDER WAVE
The maximum permissible temperature of the solder is
260
°C; solder at this temperature must not be in contact
with the joints for more than 5 seconds. The total contact
time of successive solder waves must not exceed
5 seconds.
The device may be mounted up to the seating plane, but
the temperature of the plastic body must not exceed the
specified maximum storage temperature (Tstg(max)). If the
printed-circuit board has been pre-heated, forced cooling
may be necessary immediately after soldering to keep the
temperature within the permissible limit.
18.2.2
MANUAL SOLDERING
Apply the soldering iron (24 V or less) to the lead(s) of the
package, either below the seating plane or not more than
2 mm above it. If the temperature of the soldering iron bit
is less than 300
°C it may remain in contact for up to
10 seconds. If the bit temperature is between
300 and 400
°C, contact may be up to 5 seconds.
18.3
Surface mount packages
18.3.1
REFLOW SOLDERING
Reflow soldering requires solder paste (a suspension of
fine solder particles, flux and binding agent) to be applied
to the printed-circuit board by screen printing, stencilling or
pressure-syringe dispensing before package placement.
Several methods exist for reflowing; for example,
infrared/convection heating in a conveyor type oven.
Throughput times (preheating, soldering and cooling) vary
between 100 and 200 seconds depending on heating
method.
Typical reflow peak temperatures range from
215 to 250
°C. The top-surface temperature of the
packages should preferable be kept below 230
°C.
18.3.2
WAVE SOLDERING
Conventional single wave soldering is not recommended
for surface mount devices (SMDs) or printed-circuit boards
with a high component density, as solder bridging and
non-wetting can present major problems.
To overcome these problems the double-wave soldering
method was specifically developed.
If wave soldering is used the following conditions must be
observed for optimal results:
Use a double-wave soldering method comprising a
turbulent wave with high upward pressure followed by a
smooth laminar wave.
For packages with leads on two sides and a pitch (e):
– larger than or equal to 1.27 mm, the footprint
longitudinal axis is preferred to be parallel to the
transport direction of the printed-circuit board;
– smaller than 1.27 mm, the footprint longitudinal axis
must be parallel to the transport direction of the
printed-circuit board.
The footprint must incorporate solder thieves at the
downstream end.
For packages with leads on four sides, the footprint must
be placed at a 45
° angle to the transport direction of the
printed-circuit board. The footprint must incorporate
solder thieves downstream and at the side corners.
During placement and before soldering, the package must
be fixed with a droplet of adhesive. The adhesive can be
applied by screen printing, pin transfer or syringe
dispensing. The package can be soldered after the
adhesive is cured.
Typical dwell time is 4 seconds at 250
°C.
A mildly-activated flux will eliminate the need for removal
of corrosive residues in most applications.
18.3.3
MANUAL SOLDERING
Fix the component by first soldering two
diagonally-opposite end leads. Use a low voltage (24 V or
less) soldering iron applied to the flat part of the lead.
Contact time must be limited to 10 seconds at up to
300
°C.
When using a dedicated tool, all other leads can be
soldered in one operation within 2 to 5 seconds between
270 and 320
°C.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| SAA5491PS | 制造商:PHILIPS 制造商全称:NXP Semiconductors 功能描述:Economy teletext and TV microcontrollers |
| SAA5496 | 制造商:PHILIPS 制造商全称:NXP Semiconductors 功能描述:Economy teletext and TV microcontrollers |
| SAA5496H | 制造商:PHILIPS 制造商全称:NXP Semiconductors 功能描述:Economy teletext and TV microcontrollers |
| SAA5496PS | 制造商:PHILIPS 制造商全称:NXP Semiconductors 功能描述:Economy teletext and TV microcontrollers |
| SAA5497 | 制造商:PHILIPS 制造商全称:NXP Semiconductors 功能描述:Economy teletext and TV microcontrollers |
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