pca9922 NXP Semiconductors, pca9922 Datasheet - Page 22

• Manufacturer Part Number: pca9922
• Description: 8-channel Constant Current Led Driver With Output Error Detection
• Manufacturer: NXP Semiconductors

NXP Semiconductors
PCA9922_1
Product data sheet
16.4 Reflow soldering
Key characteristics in reflow soldering are:
Table 11.
Table 12.
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
Package thickness (mm)
< 1.6
1.6 to 2.5
> 2.5
•
•
•
•
•
2.5
Process issues, such as application of adhesive and flux, clinching of leads, board
transport, the solder wave parameters, and the time during which components are
exposed to the wave
Solder bath specifications, including temperature and impurities
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 11
SnPb eutectic process (from J-STD-020C)
Lead-free process (from J-STD-020C)
and
Figure
12
8-channel constant current LED driver with output error detection
18.
Rev. 01 — 15 January 2009
Package reflow temperature ( C)
Volume (mm
< 350
235
220
Package reflow temperature ( C)
Volume (mm
< 350
260
260
250
3
3
)
)
Figure
350 to 2000
260
250
245
18) than a SnPb process, thus
220
220
350
> 2000
260
245
245
PCA9922
© NXP B.V. 2009. All rights reserved.
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