PCA9674ATS datasheet(28/34 Pages) PHILIPS

28 / 34 page

PCA9674_PCA9674A_2

Product data sheet

Rev. 02 — 12 October 2006

28 of 34

NXP Semiconductors

PCA9674/74A

Remote 8-bit I/O expander for Fm+ I2C-bus with interrupt

15. Handling information

Inputs and outputs are protected against electrostatic discharge in normal handling.

However, to be completely safe you must take normal precautions appropriate to handling

integrated circuits.

16. Soldering

16.1 Introduction

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 Through-hole mount packages

16.2.1 Soldering by dipping or by solder wave

Typical dwell time of the leads in the wave ranges from 3 seconds 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.

16.2.2 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

°C and 400 °C, contact may be up to 5 seconds.

16.3 Surface mount packages

16.3.1 Reﬂow soldering

Key characteristics in reﬂow soldering are:

• Lead-free versus SnPb soldering; note that a lead-free reﬂow process usually leads to

higher minimum peak temperatures (see Figure 29) than a PbSn process, thus

reducing the process window

• Solder paste printing issues including smearing, release, and adjusting the process

window for a mix of large and small components on one board

• Reﬂow temperature proﬁle; this proﬁle includes preheat, reﬂow (in which the board is

heated to the peak temperature) and cooling down. It is imperative that the peak

temperature is high enough for the solder to make reliable solder joints (a solder paste

characteristic). In addition, the peak temperature must be low enough that the

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