PCB recommendations BAT30F3
8/10 Doc ID 16915 Rev 2
4.2 Assembly
For chip scale package mounting on the PCB, STMicroelectronics recommends the use of a
solder stencil aperture of 330 x 330 µm maximum and a typical stencil thickness of 75 or
80 µm. Chip scale packages are fully compatible with the use of near eutectic 95.5 Sn, 4 Ag,
0.5 Cu solder paste with no-clean flux. ST's recommendations for chip scale package board
mounting are illustrated on the soldering reflow profile shown in Figure 11.
Figure 11. ST ECOPACK
®
recommended soldering reflow profile for PCB mounting
Dwell time in the soldering zone (with temperature higher than 220 °C) has to be kept as
short as possible to prevent component and substrate damage. Peak temperature must not
exceed 260 °C. Controlled atmosphere (N2 or N2H2) is recommended during the whole
reflow, especially above 150 °C.
Chip scale packages are able to withstand three times the previous recommended reflow
profile in order to be compatible with a double reflow when SMDs are mounted on both sides
of the PCB and one additional repair.
A maximum of three soldering reflows are allowed for these lead-free packages (with repair
step included).
The use of a no-clean flux is highly recommended to avoid any cleaning operation. To
prevent any bump cracks, ultrasonic cleaning methods are not recommended.
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01234567
Time (min)
Temperature (°C)
2°C/s recommended
6°C/s max
220°C
125 °C
260°C max
255°C
180°C
90 sec max
10-30 sec
90 to 150 sec
3°C/s max
0
01234567
Time (min)
Temperature (°C)
2°C/s recommended
6°C/s max
220°C
125 °C
260°C max
255°C
180°C
90 sec max
10-30 sec
90 to 150 sec
3°C/s max
