LPS33HWMechanical Design reference & Measurement results

Sept 2017

MEMS Sensor Division

LPS33HW Package Detail 2

Analog, MEMS and Sensors Product Group 26 September 2017

LPS33HW Package Details

• 3.3 x 3.3 x 2.9 mm (max) CCLGA-10L package

• Metal Lid with diameter 1.6mm vent hole size

CCLGA-10L,

3.3 x 3.3 x 2.9mmceramic

3

Analog, MEMS and Sensors Product Group 26 September 2017

LPS33HW Mechanical dimension

Water Proof Design Reference 4

Analog, MEMS and Sensors Product Group 26 September 2017

Simulated to to check enough contact pressure between O-ring and two contacts (metal lid

& plastic case) for hydrostatic pressure of 10 bar.

PCB

O-ring

LPS33HW with O-ring

2.98mm ± 0.03mm

O-ring

• Commercial O-ring

• 1.8mm inner diameter

• 1.0mm thickness

Reference of Water proof sealing

We recommend that O-Ring outer diameter (inner diameter + 2 x thickness) has overthan 3.15mm considering 2.98mm of inlet diameter. O-Ring diameter need to be widerthan inlet of IC.

Set-Up of Sealing STUDY 5

Comsol Model set up for contact pair FEM analysis ( cross section)

contact pairs

P=1[MPa] hydrostatic

press

0,95 mm

0,750 mm

1,7 mm

FR4

SS

Ste

el

FIXED boundary

O-Ring : NBR 7090

6Simulation Result

1.45Mpa contact pressure

Simulation Result with LPS33HW after assembly

7Summary

In simulation, estimated surface contact pressure between O-Ring and two contact sides

(Lid of LPS33HW & Plastic CASE) is 1.45Mpa.

Sealing against 10bar water is guaranteed in this case because:

Fluidic_hydrostatic_pressure < Contact_pressure (i.e 10bar (1Mpa) ≤ 1.45Mpa)

O-ring life time is preserved if groove depth is 70% of O-ring Section diameter

Contact pressure : 1.45Mpa

Water Pressure 1Mpa (10bar)

Overpressure Stress Test

Analog, MEMS and Sensors Product Group 26 September 2017

8

10 bar short time, 10sec and 60sec 9

Test condition : 1.5 / 3 / 5 / 10 bar over pressure for 10sec & 60sec

Recovery time analysis for becoming less than 0.5hPa

Less overpressure stress time makes the faster recovery time & result summary in below

Recovery time 0.7min @ 5bar for 10sec

Recovery time 1.2min @ 10bar for 10 sec Air pressure was used

1010 bar short time, 2 sec

10min

Assuming swimming use case: Short and repeated over-pressure

Air pressure was used

Water removal

and drying while

Device on

Zoom in

Takes several to come back to baseline.

No physical & electrical damage 10 bar over-pressure for 24hr

10 bar long time, 24hrs

Sensing part was covered by water,

and it was pressed through air.

Chemical testChlorine, Bromine and Salt Water

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User Condition TestChlorine, Bromine and Salt Water

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LPS33HW Test trial on real user Test @ Hot Chlorine or Bromine for case of swimming in the pool with each disinfectant.

Test @ Salt Water for case of swimming in the sea.

Test under each bottle of Chlorine , Bromine

and Salt water

Test strip using to confirm test condition.

Aqua check strip & measurement scale

Chlorine : 4ppm

Bromine : 5ppm

Ph : 8~8.2

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Test procedure of 1 cycle 10pcs samples in each water solution with 30’C (+/-1’C) for Chlorine & Bromine , 21’C(+/-1’C) for salt

water solution.

Leave this condition for 6hr

Take out the samples from each water and put in climatic Chamber @ 60’C/60%rH for 18hr

Test Points every 6 cycle (last round after 10 cycles) Electrical check of pressure reading.

Microscope inspection for verifying any possible damage at the end of last round.

User Condition Test Chlorine, Bromine and Salt Water

Summary - Test Result

• 10 device of LPS33HW were tested under Chlorine, Bromine and Salt

water solution up to 34 cycles (34days, 1cycle = 24hr)

• No physical damage confirmed by Microscope inspection & No

electrical accuracy drift problem after test with each disinfectant & salt

water condition .

• The result means No damage & electrical problem are predicted

under condition with swimming pool and sea as real user case.