TDA8559_3 © Koninklijke Philips Electronics N.V. 2006. All rights reserved.
Product data sheets Rev. 03 — 15 May 2006 31 of 36
Philips Semiconductors TDA8559T
Low-voltage stereo headphone amplifier
16. Soldering
16.1 Introduction to soldering surface mount packages
There is no soldering method that is ideal for all surface mount IC packages. Wave
soldering can still be used for certain surface mount ICs, but it is not suitable for fine pitch
SMDs. In these situations reflow soldering is recommended.
16.2 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. Driven by legislation and
environmental forces the worldwide use of lead-free solder pastes is increasing.
Several methods exist for reflowing; for example, convection or convection/infrared
heating in a conveyor type oven. Throughput times (preheating, soldering and cooling)
vary between 100 seconds and 200 seconds depending on heating method.
Typical reflow temperatures range from 215 °Cto260°C depending on solder paste
material. The peak top-surface temperature of the packages should be kept below:
Moisture sensitivity precautions, as indicated on packing, must be respected at all times.
16.3 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):
Table 8. SnPb eutectic process - package peak reflow temperatures (from
J-STD-020C
July 2004)
Package thickness Volume mm3 < 350 Volume mm3≥350
< 2.5 mm 240 °C+0/−5°C 225 °C+0/−5°C
≥2.5 mm 225 °C+0/−5°C 225 °C+0/−5°C
Table 9. Pb-free process - package peak reflow temperatures (from
J-STD-020C
July
2004)
Package thickness Volume mm3 < 350 Volume mm3 350 to
2000 Volume mm3 > 2000
< 1.6 mm 260 °C + 0 °C 260 °C + 0 °C 260 °C + 0 °C
1.6 mm to 2.5 mm 260 °C + 0 °C 250 °C + 0 °C 245 °C + 0 °C
≥ 2.5 mm 250 °C + 0 °C 245 °C + 0 °C 245 °C + 0 °C