pca8574 NXP Semiconductors, pca8574 Datasheet - Page 21

• Manufacturer Part Number: pca8574
• Description: Pca8574/pca8574a Remote 8-bit I/o Expander For I2c-bus With Interrupt
• Manufacturer: NXP Semiconductors

NXP Semiconductors
15. Handling information
16. Soldering
PCA8574_PCA8574A_2
Product data sheet
16.2.1 Soldering by dipping or by solder wave
16.2.2 Manual soldering
16.3.1 Reflow soldering
16.1 Introduction
16.2 Through-hole mount packages
16.3 Surface mount packages
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.
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.
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 (T
printed-circuit board has been pre-heated, forced cooling may be necessary immediately
after soldering to keep the temperature within the permissible limit.
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.
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
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
Rev. 02 — 14 May 2007
Remote 8-bit I/O expander for I
Figure
22) than a PbSn process, thus
PCA8574/74A
2
C-bus with interrupt
stg(max)
© NXP B.V. 2007. All rights reserved.
). If the
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