TDA5240T Datasheet, PDF (18/19 Pages) NXP Semiconductors – Brushless DC motor drive circuit

Philips Semiconductors
Brushless DC motor drive circuit
Product specification
TDA5240T
SOLDERING
Introduction
There is no soldering method that is ideal for all IC packages. Wave soldering is often preferred when through-hole and
surface mounted components are mixed on one printed-circuit board. However, wave soldering is not always suitable for
surface mounted ICs, or for printed-circuits with high population densities. In these situations reflow soldering is often
used.
This text gives a very brief insight to a complex technology. A more in-depth account of soldering ICs can be found in our
"IC Package Databook" (order code 9398 652 90011 ).
Reflow soldering
Reflow soldering techniques are suitable for all sa packages.
.
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 techniques exist for reflowing; for example, thermal conduction by heated belt. Dwell times vary between
50 and 300 seconds depending on heating 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 minutes at 45 °C.
Wave soldering
Wave soldering techniques can be used for all sa packages if the following conditions are observed:
.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-
.The package footprint must incorporate solder thieves at the downstream end.
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.
Maximum permissible solder temperature is 260 oC, and maximum duration of package immersion in solder is
10 seconds, if cooled to less than 150 oC within 6 seconds. Typical dwell time is 4 seconds at 250 oC.
A mildly-activated flux will eliminate the need for removal of corrosive residues in most applications.
Repairing soldered joints
Fix the component by first soldering two diagonally- opposite end leads. Use only a low voltage soldering iron (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 using a
dedicated tool, all other leads can be soldered in one operation within 2 to 5 seconds between 270 and 320 °C.
November 96
18/19