editor's blog
Subscribe Now

Why Is Plastic Package News?

A new device available in a plastic package. Big news! Wow, no one has ever done that before, right?

In so many other cases, this might be a reasonable reaction to a press release announcing a new plastic package. Except when the topic is MEMS. You can never take anything for granted with MEMS, it would seem. Least of all packaging.

So why is this news? It was a pressure sensor from STMicroelectronics. And here’s the deal: pressure sensors have to be open to the environment. That’s how they access the pressure, through a hole or port. If you take such a device, with its delicate diaphragm, and you subject it to the plastic molding process –which occurs under high pressure – you’re very likely to damage the pressure sensor itself.

Some folks have apparently addressed this issue by encasing the inner workings with a gel that can absorb the strain – in some cases even covering the sensor, meaning the pressure measurement has to act through the gel.

What ST did was to make a rather substantial change on the sensor die itself: they’ve decoupled the sensing element from the rest of the die, suspending the sense element by silicon springs. The springs handle the molding pressure without interfering with the sensed pressure. (Well, it would seem that the springs would have to be calibrated into the measurement, but they’re not blocking in the way a gel would.)

Rather a lot of work to accommodate something as silly as a simple plastic package. Which, of course, is neither silly nor simple… You can find out more in their announcement.

Leave a Reply

featured blogs
Sep 25, 2018
Robots are a hot topic these days. From helping doctors in the operating room to helping survivors of a natural disaster, it'€™s clear that robots are poised to play an important role......
Sep 25, 2018
CDNLive India took place a few weeks ago and we are just trying to catch our breath! If you missed it, I'm going to be posting two cool videos before the weekend with the highlights. Here are two blogs by the veteran blogger Paul McLellan - one on Asynchronous Design and...
Sep 24, 2018
One of the biggest events in the FPGA/SoC ecosystem is the annual Xilinx Developers Forum (XDF). XDF connects software developers and system designers to the deep expertise of Xilinx engineers, partners, and industry leaders. XDF takes place in three locations this year.  Sa...
Sep 21, 2018
  FPGA luminary David Laws has just published a well-researched blog on the Computer History Museum'€™s Web site titled '€œWho invented the Microprocessor?'€ If you'€™re wildly waving your raised hand right now, going '€œOoo, Ooo, Ooo, Call on me!'€ to get ...