Patent ID: 8513056
Filing Date: 2013-08-20
Classification: B29C,B29K,B29L,H01L

Abstract:
1. A method of fabricating a semiconductor memory device, the method comprising: forming a first welding groove along outside edges of one case of a pair of upper and lower cases; forming a first welding protrusion along outside edges of the other case, the first welding protrusion being formed to correspond to the first welding groove and having a volume larger than a volume of the first welding groove; inserting the first welding protrusion into the first welding groove; melting the first welding protrusion so that a first portion of the first welding protrusion fills the first welding groove and a second portion of the first welding protrusion fills a space between welding portions of the upper case and the lower case; and solidifying the first and second portions of the first welding protrusion, wherein the upper and lower cases include inner welding walls protruding from inner sides of the outside edges of the upper and lower cases, the inner welding wall of the upper case includes a first facing surface, and the inner welding wall of the lower case includes a second facing surface facing the first facing surface, wherein the inner welding walls partition an accommodating space into a holding space and a non-holding space, the accommodating space formed by coupling the upper and lower cases, wherein strength reinforcing ribs are formed on the upper and lower cases corresponding to the non-holding space, and wherein the ribs formed on the upper case have upper rib facing surfaces and the ribs formed at the lower cases have lower rib facing surfaces that face the upper rib facing surfaces, a third welding groove is formed in one of the upper and lower rib facing surfaces, and a third welding protrusion is formed on the other of the upper and lower rib facing surfaces, the third welding protrusion having a volume larger than a volume of the third welding groove, and the third welding protrusion is inserted into the third welding groove when the first welding protrusion is inserted in the first welding groove.