PCA8574_PCA8574A_2

© NXP B.V. 2007. All rights reserved.

Product data sheet

Rev. 02 — 14 May 2007

21 of 27

NXP Semiconductors

PCA8574/74A

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

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:

reducing the process window

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

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