European Ceramic Capacitor Crack Repair

Should ceramic chip capacitors be reworked?

Once the type II ceramic chip capacitors are accounted for, the European Space Agency (ESA) has initiated an investigation to assess whether submitting tantalum and flexible termination ceramic capacitors to rework or repair procedures should be forbidden or accepted.

How do ceramic capacitors prevent board failures?

Answers to the crack problem [1,2] To prevent board failures by failing ceramic capacitors the suppliers of the components took measures to stop catastrophic breakdowns even if they cannot entirely prevent the cracks themselves. First to name is the capacitor design called “open mode” or fail open” (see Fig. 10).

What causes cracks in ceramic chip capacitors?

Cracks in ceramic chip capacitors can be introduced at any process step during surface mount assembly. Thermal shock has become a “pat” answer for all of these cracks, but about 75 to 80% originate from other sources.

What happens if a capacitor cracks?

After a number of temperature excursions, for example due to circuit operation, the crack may propagate (Figure 3), creating an open-circuit device. In severe cases, the body of the capacitor may even fall out, leaving just remnants of ceramic surrounded by termination and solder joints.

Where are flex cracks located in a capacitor?

First to name is the capacitor design called “open mode” or fail open” (see Fig. 10). Here the overlapping capacitor plates are located only in the ceramic body way apart from the terminations. Flex cracks alwaysextendundertheterminationssonocrackcancrosstheoverlap- ping region where sparkovers can happen.

What causes elliptical cracks on a capacitor?

In severe cases, when a large surface mounted capacitor has been subjected to a sudden thermal shock, a clearly visible elliptical crack may form on the upper surface of the chip (Figure 1). This is primarily due to the tensile forces exerted by the terminations.