With modern microtechnology, there is an aggressive miniaturization of smart devices, despite an increasing level of integration and overall complexity. It is therefore becoming increasingly important to be achieve reliable, compact packaging.

For implantable medical devices (IMDs), the package must additionally provide a high quality hermetic environment to protect the device from the human body. For chip-scale devices, AuSn eutectic bonding offers the possibility of forming compact seals that achieve ultra-low permeability.

A key feature is this can be achieved at process temperatures of below 350315°C, therefore allowing for the integration of sensors and microsystems with CMOS electronics within a single package. Issues however such as solder wetting, void formation and controlling composition make formation of high-quality repeatable seals highly challenging.

Read more: Hermetic packaging for implantable microsystems

To extend operating life, all leading meter transmitter units (MTUs) are powered by long-life bobbin-type lithium thionyl chloride (LiSOCl2) cells that feature the highest capacity, highest energy density, the widest possible temperature range, and unrivaled battery life. These batteries represent only a small fraction of the overall AMI implementation cost, but remain top-of-mind among utility managers.

Pairing a 30-year MTU with a 10-year battery is hard to cost justify since it could result in high volume meter change-outs.

Due to low confidence in meter batteries, the City of Springfield, MA chose to preemptively replace thousands of batteries each year in order to avoid the chaos of disrupted billing systems, poor cash flow, and loss of valuable data. Preemptively replacing thousands of batteries cost local taxpayers millions and slashed total ROI: an outcome that may have been avoided with the choice of a different battery.

Bobbin-type LiSOCl2 batteries are overwhelmingly preferred for low-power wireless applications that draw current measurable in micro-amps, featuring the highest capacity, highest energy density, and extremely low annual self-discharge (less than 1 percent per year). Bobbin-type LiSOCl2 cells also deliver the widest possible temperature range (-80°C to 125°C), with a glass-to-metal hermetic seal that resists battery leakage.

All batteries experience some form self-discharge, with cell capacity being exhausted even when the battery is not connected to an external load. Bobbin-type LiSOCl2 batteries are less affected by annual self-discharge, the result of controlled passivation.

Read more: Long-Life Batteries Result in Greater ROI