TDA3608THQ datasheet(18/22 Pages) PHILIPS

18 / 22 page

2003 Nov 28

Philips Semiconductors

Product speciﬁcation

Multiple voltage regulators with switch

TDA3608Q; TDA3608TH

SOLDERING

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. 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. Driven by legislation and environmental

forces the worldwide use of lead-free solder pastes is

increasing.

Through-hole mount packages

SOLDERING BY DIPPING OR BY SOLDER WAVE

Typical dwell time of the leads in the wave ranges from

3 to 4 seconds at 250

°C or 265 °C, depending on solder

material applied, SnPb or Pb-free respectively.

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.

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.

Surface mount packages

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,

convection or convection/infrared 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 270

°C depending on solder paste material. The

top-surface temperature of the packages should

preferably be kept:

• below 225 °C (SnPb process) or below 245 °C (Pb-free

process)

– for all the BGA, HTSSON..T and SSOP-T packages

– for packages with a thickness

≥ 2.5 mm

– for packages with a thickness < 2.5 mm and a

volume

≥ 350 mm3 so called thick/large packages.

• below 240 °C (SnPb process) or below 260 °C (Pb-free

process) for packages with a thickness < 2.5 mm and a

volume < 350 mm3 so called small/thin packages.

Moisture sensitivity precautions, as indicated on packing,

must be respected at all times.

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.

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