Reducing power consumption of chip-scale atomic clocks (CSACs) is a common goal for researchers. An effective but challenging issue for this goal is the reduction of power dissipation of the physics package. Here, we analyze the power consumption through thermal conduction, radiation and convection of a microelectromechanical systems (MEMS) cell physics package for CSACs. The physics package consisting of small coefficient of thermal conductivity and emissivity materials is proposed, which is vacuum sealed by gold-tin eutectic bonding. The helium leak rate is measured to be 4 × 10^–11 Pa·m³/s. Thus, the physics package could keep high vacuum for about 3 years. The total power consumption of the proposed physics package is measured to be less than 20 mW. And the vacuum packaging also improves the frequency stability performance of CSACs, due to the increased insensitivity to ambient temperature change. The frequency performance of the prototype CSAC is improved from 8.8 × 10^–12 @1000 s to 5.38 × 10^–12@1000 s. The results show that the gold-tin eutectic bonding can be used as vacuum packaging for MEMS devices.

降低芯片级原子钟 (CSAC) 的功耗是研究人员的共同目标。实现这一目标的一个有效但具有挑战性的问题是降低物理封装的功耗。在这里，我们分析了用于 CSAC 的微机电系统 (MEMS) 电池物理封装的热传导、辐射和对流的功耗。提出了由导热系数和发射率小的材料组成的物理封装，采用金锡共晶键合进行真空密封。测得氦泄漏率为 4 × 10 ^–11  Pa·m ³/秒。因此，物理包可以保持高真空约 3 年。所提议的物理封装的总功耗经测量小于 20 mW。由于对环境温度变化的不敏感性增加，真空封装还提高了 CSAC 的频率稳定性能。原型 CSAC 的频率性能从 8.8 × 10 ^–12 @1000 s 提高到 5.38 × 10 ^–12 @1000 s。结果表明，金锡共晶键合可用于MEMS器件的真空封装。