LDC1312-Q1: Coil PCB issue

Shrikant,

Are the OK and NOK PCBs the same design and/or the same materials?

Regards,
John

OK and NOK PCB are of same gerber file and same materiel.

Till now we have approximately 12K parts  produced. Out of that i got two such failures..

Shrikant,

Thank you for the information.
Are the NOK coils being substituted onto the same PCBs as the OK coils, or are they being used on different PCBs?

Regards,
John

Hi John,

Thank you for your support.

There are two PCBA in our part, Coil PCB and Controller PCB.

Coil PCB has coil and controller PCB has LDC1312,microcontroller and other stuffs.

After replacing NOK coil PCB by OK coil PCB in controller PCB (controller PCB of NOK part), unit becomes OK.

When i put NOK coil PCB in OK part, OK part becomes NOK.New Microsoft PowerPoint Presentation.pptx

Below are the snaps of coil PCB, controller PCB and controller + coil PCB assembly for your reference

Shrikant,

Thank you for the snaps.
So it sounds like the problem follows the coil, not the controller or the LDC1312.
Please let me know if I am not understanding this correctly.

You mentioned earlier that the OK and NOK coils had similar L and R as measured on and LCR meter.
Would it be possible to re-do those measurements and compare any changes in L & R between OK and NOK coils as you heat them with a hair dryer?
If that measurement does not show anything helpful, can your LCR meter measure the self-resonant frequency of the coils? If not, do you have equipment that will let you do this?
It may or may not be important, but it may give a clue as to what is different between the OK and NOK coils.

Regards,
John

Hi John,

Thanks i will do the measurement as you directed and let u know the results...

Hi John,

Please note the measurement data.1524.New Microsoft PowerPoint Presentation.pptx

i will share Inductance data of OK and NOK coil at elevated temperature soon..

PPT is updated with elevated temperature data3326.New Microsoft PowerPoint Presentation.pptx

Shrikant,

Many thanks for uploading the details on what you are seeing.
The OK and NOK coils seem to have the same resonant frequency, which (I think) says the inductances are ok, but they have very different Rp which goes against your measurements with the function generator. I'm not sure what could be going on here. I will check with my colleagues to see f they have nay suggestions and will update this thread within two days.

Regards,
John

Shrikant,

Just confirm: are you using the same device settings for the OK & NOK coil?
If you are, is it possible to adjust the current drive settings (Table 38 of the data sheet) with an NOK coil to make it work?

Regards,
John