DocID025978 Rev 1

11/26

AN4450

Hardware (designing PCB schematics and layout)

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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 Figure 7).

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 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.