Analysis of soldering-induced cracking of BaTiO/sub 3/ ceramic capacitors
Cracks were found in ceramic capacitors after soldering on hydrid microcircuit boards during fabrication. Samples from an older batch of capacitors which had been successfully soldered were compared with capacitors from the problem group. X-ray elemental analysis showed differences in chemistries of the barium titanate (BaTiO/sub 3/) dielectrics, the capacitor plate elements, and the termination and solder layers. Crack initiation sites were found along the outer surfaces originating at the metal/ceramic interface; in many cases crack growth from an initial flaw occurred in discrete steps. The fractographic evidence indicated that thermal stress at the metal/ceramic interface were the driving force for the crack propagation. These stresses could have originated at several times: during the original manufacture of the capacitors, the reflow board soldering process, or subsequent reworking operations. Fracture toughness and hardness measurements were made from cracks and impressions, respectively, of a Vickers pyramid diamond. The fracture toughness of the older capacitor material was only half the value of the newer capacitor. Thus, the material was not the source of cracking, but rather a difference in design application between the old and the new.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (USA)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 5925106
- Report Number(s):
- SAND-82-2979C; CONF-830637-5; ON: DE83013980
- Resource Relation:
- Conference: IEEE international symposium on applications of ferroelectrics, Gaithersburg, MD, USA, 1 Jun 1983
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
CAPACITORS
CRACKS
SOLDERING
BARIUM OXIDES
CERAMICS
CRACK PROPAGATION
EXPERIMENTAL DATA
FRACTURE PROPERTIES
TITANIUM OXIDES
VICKERS HARDNESS
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
DATA
ELECTRICAL EQUIPMENT
EQUIPMENT
FABRICATION
INFORMATION
JOINING
MECHANICAL PROPERTIES
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
WELDING
420800* - Engineering- Electronic Circuits & Devices- (-1989)
360204 - Ceramics
Cermets
& Refractories- Physical Properties