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IEC JEDEC EIAJ
92-11-17
SOT187-2 112E10 MO-047AC
95-02-25
September 1993 77
Philips Semiconductors Preliminary specification
8-bit microcontroller with EMC and
P8xCE528
FEEPROM
" The package footprint must incorporate solder thieves at
SOLDERING
the downstream corners.
Introduction
QFP
There is no soldering method that is ideal for all IC
packages. Wave soldering is often preferred when
Wave soldering is not recommended for QFP packages.
through-hole and surface mounted components are mixed
This is because of the likelihood of solder bridging due to
on one printed-circuit board. However, wave soldering is
closely-spaced leads and the possibility of incomplete
not always suitable for surface mounted ICs, or for
solder penetration in multi-lead devices.
printed-circuits with high population densities. In these
If wave soldering cannot be avoided, the following
situations reflow soldering is often used.
conditions must be observed:
This text gives a very brief insight to a complex technology.
" A double-wave (a turbulent wave with high upward
A more in-depth account of soldering ICs can be found in
pressure followed by a smooth laminar wave)
our IC Package Databook (order code 9398 652 90011).
soldering technique should be used.
Reflow soldering " The footprint must be at an angle of 45° to the board
direction and must incorporate solder thieves
Reflow soldering techniques are suitable for all PLCC and
downstream and at the side corners.
QFP packages.
Even with these conditions, do not consider wave
The choice of heating method may be influenced by larger
soldering the following packages: QFP52 (SOT379-1),
PLCC or QFP packages (44 leads, or more). If infrared or
QFP100 (SOT317-1), QFP100 (SOT317-2),
vapour phase heating is used and the large packages are
QFP100 (SOT382-1) or QFP160 (SOT322-1).
not absolutely dry (less than 0.1% moisture content by
weight), vaporization of the small amount of moisture in
METHOD (PLCC AND QFP)
them can cause cracking of the plastic body. For more
information, refer to the Drypack chapter in our Quality
During placement and before soldering, the package must
Reference Handbook (order code 9397 750 00192).
be fixed with a droplet of adhesive. The adhesive can be
applied by screen printing, pin transfer or syringe
Reflow soldering requires solder paste (a suspension of
dispensing. The package can be soldered after the
fine solder particles, flux and binding agent) to be applied
adhesive is cured.
to the printed-circuit board by screen printing, stencilling or
pressure-syringe dispensing before package placement.
Maximum permissible solder temperature is 260 °C, and
maximum duration of package immersion in solder is
Several techniques exist for reflowing; for example,
10 seconds, if cooled to less than 150 °C within
thermal conduction by heated belt. Dwell times vary
6 seconds. Typical dwell time is 4 seconds at 250 °C.
between 50 and 300 seconds depending on heating
method. Typical reflow temperatures range from
A mildly-activated flux will eliminate the need for removal
215 to 250 °C.
of corrosive residues in most applications.
Preheating is necessary to dry the paste and evaporate
Repairing soldered joints
the binding agent. Preheating duration: 45 minutes at
45 °C.
Fix the component by first soldering two diagonally-
opposite end leads. Use only a low voltage soldering iron
Wave soldering
(less than 24 V) applied to the flat part of the lead. Contact
time must be limited to 10 seconds at up to 300 °C. When
PLCC
using a dedicated tool, all other leads can be soldered in
Wave soldering techniques can be used for all PLCC one operation within 2 to 5 seconds between
packages if the following conditions are observed: 270 and 320 °C.
" A double-wave (a turbulent wave with high upward
pressure followed by a smooth laminar wave) soldering
technique should be used.
" The longitudinal axis of the package footprint must be
parallel to the solder flow.
September 1993 78
Philips Semiconductors Preliminary specification
8-bit microcontroller with EMC and
P8xCE528
FEEPROM
DEFINITIONS
Data sheet status
Objective specification This data sheet contains target or goal specifications for product development.
Preliminary specification This data sheet contains preliminary data; supplementary data may be published later.
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