Fiber Optics
1. Fiber Optic cable shrinkback resulting in lack of mechanical suppport

Here are two images to illustrate how "shrinkback" of the jacket in a fiber optic cable, an expected phenomenon that occurs during thermal cycling, can affect reliability. In the first image, the jacket has released from the epoxy and shrunk back away from the connector leaving the fiber without mechanical support. In the second, the epoxy bonded sufficiently to the jacket so that the epoxy pulled out of the connector along with the jacket. Again, leaving the fiber with inadequate mechanical support.

Also, in the first image, you can see bubbles in the epoxy (yellow arrows). Bubbles and voids in the adhesive surrounding optical fibers in connectors result in uneven mechanical loads on the fiber and have been correlated to fiber breakage.

Reference :
NASA-STD-8739.5
6.8-9 Mixed adhesives shall be degassed (e.g., centrifuge or vacuum) before they are applied to optical fibers and connectors.

7.3-1 Fiber optic cables shall be thermally preconditioned prior to preparation for termination. Engineering documentation shall define parameters for preconditioning.