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HDC1000: Soldering wires close to sensor

A K
Intellectual 905 points
Part Number: HDC1000
Other Parts Discussed in Thread: CC2650STK

My question is about the humidity sensor on CC2650STK board. We used the CC2650STK gerbers to make a board and only populated external flash, humidity and light. The boards have been running for couple months with CR2032 batteries. I then removed CR2032 and connected CR2477 battery with wires to BAT+ and BAT- terminals from assembly bottom. They have been running fine for a month or so. This time I connected CR2477 wire leads to assembly top and now I have boards that increasingly draw current until they short with irreversible damage in couple days. 

I have a post in BLE forum about this: https://e2e.ti.com/support/wireless_connectivity/bluetooth_low_energy/f/538/t/601502

Since the humidity sensor is between these terminals could the soldering or wires somehow trigger a higher current draw eventually damaging the PCB trace? Is this possible?

  • 0
    TI__Expert 5695 points
    Our applications engineer will contact you shortly
  • 0
    TI__Expert 5145 points
    Hi,
    I can exclude that the humidity sensor itself is the root cause of the problem.
    Also looking to the gerber file, I noticed that all the balls connected to VDD are in one side of the device, and all the signals connected to GND are on the other side, so I can also exclude that a short circuit between two adjacent balls can produce the issue.
    Please let me know if you have any doubts or need firther information.
    Best regards,
    Carmine
  • 0 in reply to Carmine Iascone
    Intellectual 905 points
    Carmine,
    I very much appreciate your quick response. I understand your explanation but have results in hand today from a few tests I have been doing over couple days that keeps my suspicion going.
    I had two boards with CR2477 shorter wire setup on their way to failure. Normal average draw is 0.024mA, failed board#1 was at 0.1mA, board#2 at 3mA.
    I removed the humidity sensor on both the boards, draw was still 0.1mA and 3mA resp. i.e removing sensor did not change the draw. I then left them running for a couple days with a CR2032 battery.
    Today the boards are still running - draw has not reduced nor has it worsened. On other boards that I left the sensor populated have shorted. This is why I suspect that the CR2477 shorter wire setup may be triggering something in the sensor. I will X-ray the boards soon to understand more and see if I can rule out the humidity sensor, but I narrowed in on humidity only because it is right between the terminals.
    Would this information change your analysis?

    Thanks!