The Leakage of Pressure Sensor MPX2050DP

[zbin]

Hi, when using MPX2050, it is found that the pressure value decreases slightly. We have tested to eliminate problems that are not connecting pipes or joints. And when we measure it with another Honeywell sensor, the pressure will not decrease. So we doubt whether MP2050 is leaking. If there is such a problem, please tell me the speed of leaking. Thanks!

[reyes]

Hi,

The output voltage on the MPX2050 is ratiometric, this means that output voltage of the sensor is directly affected by the voltage supply. Make sure the input supply voltage is constant. If there is a small drop on the input voltage, the output voltage would be affected. For example, if you are using a battery in your system to supply the pressure sensor, there would be a small battery drain that could cause the voltage drop you are seen on the output of the sensor.

Another possible cause is the pressure connected on port P2 of the MPX2050DP, if I understand correctly, you are using the differential (two ported) version of the sensor, and you are only using Port P1 to measure the pressure, while port P2 is unconnected, is my understanding correct?

If it is correct, the local atmospheric pressure can be changing causing a change in the reference of the pressure measurement, which cause a shift on the output voltage of the sensor.

Have a great day,
Jose

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[zbin]

Hi, Jose

Thank you very much for your reply. As you think, port P1 of MPX2050 connects to the pressure source, and port P2 connects to the atmosphere. I've verified that the supply voltage is stable and the atmospheric pressure may fluctuate, but the problem now is that the pressure readings will gradually decrease from 20 kPa to 0. It's obvious that there is a leakage phenomenon.

And we have also done comparative experiments with Honeywell's pressure sensor. The experimental results show that Honeywell's sensor has no leakage problem and MPX2050 has this problem. I would like to ask MPX2050 whether there is such a leak problem. I hope you can give a positive answer from the performance of the sensor itself. If there is a leak, I want to know how fast it will leak.

Best regards,

zhang bin

[reyes]

Hi Zhang Bin,

Definitely it is not normal that the MPX2050 suffer a leakage of gradually decrease from 20 kPa to 0, it is possible that the device is damaged.

Do you think that there is a possibility that the device is getting damaged during the soldering?

You need to be very careful with the handling and soldering for this kind of devices, here are some solder recommendations for this device:

1. Use SAC solder alloy (i.e., Sn-Ag-Cu) with a melting point of about 217°C. It is recommended to use SAC305 (i.e., Sn-3.0 wt.% Ag-0.5 wt.% Cu).

2. Reflow:

• Ramp up rate: 2 to 3°C/s.
• Preheat flat (soak): 110 to 130s.
• Reflow peak temperature: 210°C to 220°C (depends on exact SAC alloy composition).
• Time above 217°C: 40 to 90s (depends on board type, thermal mass of the board/quantities in the reflow).
• Ramp down: 5 to 6°C/s.
• Using an inert reflow environment (with O2 level about 5 to 15 ppm).

Please make sure you are not exceeding the 220 Celcius of Peak Package Body Temperature (PPT) and the Maximum Time at Peak Temperature of 30 seconds.

Have a great day,
Jose

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[zbin]

We didn't solder the sensor's pins directly. We soldered a base and then inserted the sensor's pins into the base, so it won't be damaged by soldering.

Leakage does not change from 20 kPa to 0 at once. It is very slow. The leak rate is about 0.1 kPa/min at 20 kPa. With the decrease of pressure, the leak rate will be slower.

Sensors can be measured normally in a short time, and leaks can be found only when pressure readings are observed for a long time. This is not the case with a single sensor, but in batches. 

Now I want to know if leakage is an inherent feature of MPX2050. I'd like to ask if there is a long-term leak test for the sensor. Can you provide me with the test report, especially on leaks?

I hope you can answer me directly whether the sensor MPX2050 is leaking, yes or no. if there is leaking, we will find out how to improve it, if not, then we will look for other reasons.

Best regards,

Zhang bin

[reyes]

Hi Zhang bin,

Thanks for the clarification.

Answering to your question, there should not be any leakage on the pressure sensors, nor for the short term nor the long term.

There are no test reports for leakage.

If needed, you can ask for a CQC quality report, to do this, you need to contact your distributor and ask them to start the CQC process.

Have a great day,
Jose

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