The spacecraft for deep space exploration missions will face extreme environments, including cryogenic temperature, intense radiation, wide-range temperature variations and even the combination of conditions mentioned above. Harsh environments will lead to solder joints degradation or even failure, resulting in damage to onboard electronics. The research activities on high reliability solder joints using in extreme environments can not only reduce the use of onboard protection devices, but effectively improve the overall reliability of spacecraft, which is of great significance to the aviation industry. In this paper, we review the reliability research on SnPb solder alloys, Sn-based lead-free solder alloys and In-based solder alloys in extreme environments, and try to provide some suggestions for the follow-up studies, which focus on solder joint reliability under extreme environments.

Electrically conductive adhesives (ECAs) are one of the low temperature bonding materials. It can be used to replace toxic Sn-Pb solder. The key issue for the application of ECAs is how to improve their electrical properties. In the present study, we develop an effective method to promote the electrical properties of ECAs by addition of polyaniline (PANI) nanoparticles. PANIs were synthesized via a facile one-step chemical oxidative polymerization method. After adding 0.5 wt% PANI nanoparticles, the conductivity of ECAs increased dramatically by an order of magnitude. The bulk resistivity of 8.8 × 10⁻⁵ Ω·cm is achieved for 65 wt% silver fillers with 0.5 wt% PANIs loaded ECAs. Besides, this improvement has no negative effect on the shear strength and the aging life of ECAs. Moreover, the use of PANIs not only lowers the percolation threshold of ECAs, but also reduces the cost and improves the bonding reliability. Finally, PANIs enhanced ECAs patterns were successfully printed by a stencil printing method, which proved their potential applications in replacing conventional solder pastes and printing functional circuits.