September 1994
14
Philips Semiconductors
Preliminary specification
Integrated NTSC decoder
and sync processor
TDA8315T
SOLDERING
Plastic small-outline packages
B
Y WAVE
During placement and before soldering, the component
must be fixed with a droplet of adhesive. After curing the
adhesive, the component can be soldered. The adhesive
can be applied by screen printing, pin transfer or syringe
dispensing.
Maximum permissible solder temperature is 260
°
C, and
maximum duration of package immersion in solder bath is
10 s, if allowed to cool to less than 150
°
C within 6 s.
Typical dwell time is 4 s at 250
°
C.
A modified wave soldering technique is recommended
using two solder waves (dual-wave), in which a turbulent
wave with high upward pressure is followed by a smooth
laminar wave. Using a mildly-activated flux eliminates the
need for removal of corrosive residues in most
applications.
B
Y SOLDER PASTE REFLOW
Reflow soldering requires the solder paste (a suspension
of fine solder particles, flux and binding agent) to be
applied to the substrate by screen printing, stencilling or
pressure-syringe dispensing before device placement.
Several techniques exist for reflowing; for example,
thermal conduction by heated belt, infrared, and
vapour-phase reflow. Dwell times vary between 50 and
300 s according to method. Typical reflow temperatures
range from 215 to 250
°
C.
Preheating is necessary to dry the paste and evaporate
the binding agent. Preheating duration: 45 min at 45
°
C.
R
EPAIRING SOLDERED JOINTS
(
BY HAND
-
HELD SOLDERING
IRON OR PULSE
-
HEATED SOLDER TOOL
)
Fix the component by first soldering two, diagonally
opposite, end pins. Apply the heating tool to the flat part of
the pin only. Contact time must be limited to 10 s at up to
300
°
C. When using proper tools, all other pins can be
soldered in one operation within 2 to 5 s at between 270
and 320
°
C. (Pulse-heated soldering is not recommended
for SO packages.)
For pulse-heated solder tool (resistance) soldering of VSO
packages, solder is applied to the substrate by dipping or
by an extra thick tin/lead plating before package
placement.