We report a case of spontaneous rupture of the left common iliac vein diagnosed pre-operatively with CT and successfully treated with surgery and placement of a stent. A 60-year-old woman was referred to our emergency room because of a sudden left lower abdominal pain and swelling of the left lower extremity. CT revealed a huge retroperitoneal haematoma and extrinsic compression of the left common iliac vein with acute thrombosis of deep veins of the left lower extremity. Venous patch angioplasty was performed at the site of spontaneous rupture. After thrombectomy with use of a Forgaty catheter, a stent was placed at the occluded segment of the left common iliac vein under the C-arm fluroscopic guidance. Follow-up CT 10 days and 8 months after initial examination demonstrated a venous stent with preserved luminal patency and striking resolution of deep vein thrombosis of the left lower extremity.

In order to save the manufacturing cost of ULSI semiconductor device, there are two significant approaches; shrinking chip size by adopting CUP Pad (circuit under pad) and reducing package cost by using Cu wire bonding as a substitute for Au wire. However, these two approaches have a conflict that CUP pad is more sensitive to higher mechanical stress induced by Cu wire bonding than mechanical stress from Au wire. Thick pad metal is a way to enhance the strength of CUP pad but it brings enlargement of top metal design rule, which can increase chip size. Therefore it is highly required to develop a robust CUP pad structure with thin pad metal in order to apply Cu wire bonding without any negative effect on chip size. This study deeply investigated on the crack in CUP pad structure of ULSI with thin top metal caused by high mechanical stress of Cu wire bonding. FIB cross-sectional analysis for the crack revealed how and where the crack is started and propagated over the whole pad. Mechanism of pad crack was discovered by strain and strength analysis on each film layer which forms bonding pad structure. Cu wire bonding experiment was performed with several pad structures at various bonding conditions, the outcome of the experiment delivered major factors to enhance the strength of pad structure against physical damage during Cu wire bonding process. This study concentrates on a robust CUP pad structure of ULSI with thin pad metal for Cu wire designed with considering the major factors.

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