ESDAXLC4-1BF3 Datasheet, PDF (8/10 Pages) STMicroelectronics – Single line extra low capacitance TVS

PCB recommendations
ESDAXLC4-1BF3
4.2
Assembly
For chip scale package mounting on the PCB, STMicroelectronics recommends the use of a
solder stencil aperture of 330 x 330 µm² 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 14.
Figure 14. ST ECOPACK® recommended soldering reflow profile for PCB mounting
Temperature (°C)
260°C max
255°C
220°C
180°C
125 °C
3°C/s max
3°C/s max
2°C/s62r°°eCCc//ossm6mr°emCacx/eosnmmdmeadxended
0
0
1
2
3
4
5
6
7
10-30 sec
Time (min)
90 to 150 sec
90 sec max
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 damages. 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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Doc ID 018522 Rev 2