Q:
The M2x0.4mm mounting holes on the EVAL-ADIS for my ADIS16485 do not line up with the holes in the package. Why?
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A:
The original intent of offering M2x0.4mm tapped mounting holes was to simplify the DUT installation process for a wide array of IMU products, such as the ADIS16485. For the most part, this has worked really well, but after observing a larger volume of EVAL-ADIS boards and packages, we have been able to better observe how normal, expected package variation impacts the PCB to package hole alignment. In the majority of cases where the holes do not line up, we have been able to twist the IMU bodies around to support the M2x0.4mm machine screws. However, this practice violates the "best practices" for mounting these types of devices by placing translational stress on the connector. In some units, this will impact the bias repeatability, bias temperature coefficient and axis to axis alignment, so we offer the following suggestions:
- Drill the tapped holes out to a diameter of at least 0.285" and use a washer/nut combination on the backside for securing the DUT to the EVAL-ADIS.
- For the ADIS1648x family, use Example #1 to guide your mounting approach:
http://ez.analog.com/docs/DOC-10634 - For the ADIS1644x family, note that direct contact between the substrate and the EVAL-ADIS will impact performance. For best performance, use a mounting approach like the one in this post and perhaps use J1 (EVAL-ADIS) and a short ribbon cable to connect to the EVAL-ADIS.
http://ez.analog.com/docs/DOC-2763
In the future, we are updating the EVAL-ADIS design to increase the mounting hole size to 0.285" and we are updating the machine screw kit to include M2 washers and M2x0.4mm machine nuts. While it is impossible to predict the roll-out schedule at this time, we expect to have the new design complete and available by March of 2014.
Best,
NevadaMark