DocID025978 Rev 1
11/26
AN4450
Hardware (designing PCB schematics and layout)
26
The PCB soldering profile depends on the number, size and placement of components on
the board. The soldering profile should be defined by experience, rather than the pressure
sensor soldering profile only.
The JEDEC reflow profile is provided below.
Figure 7. High temperature lead-free soldering profile 260 °C max
No solder material reflow on the side of the package is allowed since *LGA packages show
metal trace out of package side.
No need to use any tape to cover the hole on the CAP of the LPS25H during reflow. The
cleaning of the PCB is not a general task, as it should be cleaned only when the PCB is
contaminated during reflow. ST does not ship the LPS25H covered.
2.2.4 Manual
soldering
Apply solder paste (e.g. ALPHA® OM-338-T) on the PCB solder pads using a syringe (air,
bubble free), and position the *LGA accordingly. Then press it to ensure it is flat on the PCB,
and heat it in an oven using the 260 °C JDEC profile (the one shown in
).
Take care that hand soldering is within spec. In any case, in an emergency situation, coat
the solder pad with tin-lead, and use solder wick to flatten the solder ball. Then put the
soldering iron on the *LGA land marks to deposit solder on the *LGA pads. Then position it,
and use a hot air gun to melt both sides and obtain eutectic bonding (350 °C). However, this
is not recommended. Hot air from the gun must be spread around the package dynamically;
keep moving the air gun around the *LGA.
Solder heat resistance and environmental specification
The second level interconnect category on ST ECOPACK
®
lead-free package is marked on
the inner box label, in compliance with JEDEC standard JESD97. Soldering condition
maximum ratings are also marked on the same label.
HCLGA/HLGA packages for pressure sensors are qualified for soldering heat resistance
according to JEDEC J-STD-020, in MSL3 condition.
