LPC2925 NXP Semiconductors, LPC2925 Datasheet - Page 75

• Manufacturer Part Number: LPC2925
• Description: (LPC2921 - LPC2925) ARM9 microcontroller
• Manufacturer: NXP Semiconductors

NXP Semiconductors
LPC2921_2923_2925_0
Preliminary data sheet
www.DataSheet4U.com
12.4 Reflow soldering
Key characteristics in reflow soldering are:
Table 38.
Table 39.
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)
< 2.5
≥ 2.5
Package thickness (mm)
< 1.6
1.6 to 2.5
> 2.5
•
•
•
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
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
Table 38
SnPb eutectic process (from J-STD-020C)
Lead-free process (from J-STD-020C)
and
Figure
39
Rev. 00.01 — 24 October 2008
32.
Package reflow temperature (°C)
Volume (mm
< 350
235
220
Package reflow temperature (°C)
Volume (mm
< 350
260
260
250
3
3
)
)
Figure
ARM9 microcontroller with CAN and LIN
LPC2921/2923/2925
350 to 2000
260
250
245
32) than a SnPb process, thus
≥ 350
220
220
> 2000
260
245
245
© NXP B.V. 2008. All rights reserved.
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