pcf8564a NXP Semiconductors, pcf8564a Datasheet - Page 38

• Manufacturer Part Number: pcf8564a
• Description: Real Time Clock And Calendar
• Manufacturer: NXP Semiconductors

NXP Semiconductors
PCF8564A_1
Product data sheet
19.2 Board mounting
19.3 Reflow soldering
All NXP WLCSP packages are lead-free.
Board mounting of a WLCSP requires several steps:
Key characteristics in reflow soldering are:
Table 35.
Moisture sensitivity precautions, as indicated on the packing, must be respected at all
times.
Studies have shown that small packages reach higher temperatures during reflow
soldering, see
Package thickness (mm)
< 1.6
1.6 to 2.5
> 2.5
1. Solder paste printing on the PCB
2. Component placement with a pick and place machine
3. The reflow soldering itself
•
•
•
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, such as 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) while being low enough that the packages and/or boards are not
damaged. The peak temperature of the package depends on package thickness and
volume and is classified in accordance with
Lead-free process (from J-STD-020C)
Figure
34.
Rev. 1 — 8 October 2009
Package reflow temperature ( C)
Volume (mm
< 350
260
260
250
3
)
Figure
350 to 2000
260
250
245
Table
34) than a PbSn process, thus
35.
Real time clock and calendar
PCF8564A
> 2000
260
245
245
© NXP B.V. 2009. All rights reserved.
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