Semiconductor memory device and method of fabricating the same

Abstract

Provided is a semiconductor device and method of fabricating the semiconductor memory device. The semiconductor device may be formed by 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. The method may further include inserting the first welding protrusion into the first welding groove to enclose a memory module in an inner accommodating space of the upper and lower cases, 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.

1 .- 17 . (canceled) 
     
     
         18 . A method of forming a case for holding a semiconductor, comprising:
 forming a first cover and a second cover, a contour of the first cover being substantially symmetrical to a contour of the second cover such that the first cover and the second cover fit to form the case, the first cover including a first upper portion and a first lower portion, the second cover including a second upper portion and a second lower portion;   forming a first inner wall across an inner surface of the first cover to separate an inner portion of the first cover into the first upper portion and the first lower portion;   forming a plurality of first ribs on the inner surface of the first lower portion; and   coupling the first cover and the second cover to hold the semiconductor device in an inner accommodating room defined by the first upper portion and the second upper portion.   
     
     
         19 . The method of  claim 18  further comprising:
 forming a second inner wall across an inner surface of the second cover to separate an inner portion into the second upper portion and the second lower portion. 
 
     
     
         20 . The method of  claim 19 , wherein
 the forming a first inner wall includes connecting the first inner wall to two side edges of the first cover, and   the forming a second inner wall includes connecting the second inner wall to two side edges of the second cover.   
     
     
         21 . The method of  claim 18  further comprising:
 forming a plurality of second ribs on an inner surface of the second lower portion. 
 
     
     
         22 . The method of  claim 18  further comprising:
 forming a plurality of openings in the first upper portion. 
 
     
     
         23 . The method of  claim 18  further comprising:
 forming a recessed portion at one of side edges of the first upper portion and the second upper portion such that the recessed portion of the first upper portion and the recessed portion of the second upper portion are symmetrical to each other and fit to each other. 
 
     
     
         24 . The method of  claim 23  further comprising:
 mounting a knob in the recessed portions of the first upper portion and the second upper portion. 
 
     
     
         25 . The method of  claim 23  further comprising:
 forming a welding portion at edges of each inner surface of the first cover and the second cover, the welding portion protruding from the respective inner surface of the first cover and the second cover. 
 
     
     
         26 . The method of  claim 25 , wherein the protruding welding portion of each of the first cover and the second cover is not formed at edges of each recessed portion. 
     
     
         27 . The method of  claim 26 , wherein the recessed portion of the first upper portion and the recessed portion of the second upper portion are not extended to the first lower portion and the second lower portion, respectively. 
     
     
         28 . The method of  claim 21  further comprising:
 coupling an insertable reinforcing member to either the first lower portion or the second lower portion, the thickness of the first lower portion or the second lower portion that is coupled with the insertable reinforcing member being greater than the thickness of the first upper portion or the second upper portion, respectively. 
 
     
     
         29 . The method of  claim 28 , wherein the coupling an insertable reinforcing member includes passing the plurality of first or second ribs through a plurality of holes formed in the insertable reinforcing member. 
     
     
         30 . The method of  claim 21 , wherein the plurality of first and second ribs are substantially spread around the first lower portion and the second lower portion. 
     
     
         31 . The method of  claim 21 , wherein the forming a plurality of first and second ribs includes forming a plurality of first-type ribs perpendicular to the respective inner wall of the first cover or the second cover, the plurality of first-type ribs being formed such that a distance between two adjacent first-type ribs is substantially equal. 
     
     
         32 . The method of  claim 31 , wherein the plurality of first-type ribs are formed such that a distance between one of two outermost ribs among the plurality of first-type ribs and a closer side edge among two side edges of each respective cover that are parallel to the plurality of first-type ribs is shorter than the distance between two adjacent first-type ribs. 
     
     
         33 . The method of  claim 31 , wherein the plurality of first-type ribs are formed such that each of two outermost ribs among the plurality of first-type ribs abuts to a respective side edge of each respective cover. 
     
     
         34 . The method of  claim 31 , wherein the forming a plurality of first and second ribs includes forming a plurality of second-type ribs perpendicular to the plurality of first-type ribs, the plurality of second-type ribs being formed such that a distance between two adjacent second-type ribs is substantially equal. 
     
     
         35 . The method of  claim 31 , wherein the forming the plurality of first-type ribs includes connecting the plurality of first-type ribs to the respective ones of the first and second inner walls, and to respective bottom edges of the first and second lower portions. 
     
     
         36 . The method of  claim 31 , wherein the plurality of first-type ribs are not connected to the first and second inner walls and to bottom edges of the first and second lower portions. 
     
     
         37 . The method of  claim 21 , wherein the forming a plurality of first and second ribs includes forming a plurality of first-type ribs perpendicular to the respective inner wall of the first cover or the second cover, a plurality of second-type ribs perpendicular to the plurality of first-type ribs, and a plurality of third-type ribs diagonal to the plurality of first-type ribs and the plurality of second-type ribs. 
     
     
         38 . The method of  claim 37 , wherein the forming the plurality of first-type ribs, the plurality of second-type ribs and the plurality of third-type ribs includes,
 coupling the plurality of first-type ribs and the plurality of second-type ribs at junction points, and   connecting each of the plurality of third-type ribs to at least two junction points.   
     
     
         39 . The method of  claim 26  further comprising:
 forming welding protrusions on the welding portion of one of the first cover and the second cover; and 
 forming welding grooves on the welding portion of the other of the first cover and the second cover such that the welding grooves are shaped to receive the welding protrusions and the welding protrusions have a volume larger than the welding grooves. 
 
     
     
         40 . The method of  claim 39  further comprising:
 forming a junction portion between the welding portion of the first cover and the welding portion of the second cover using a portion of the welding protrusions outside the welding grooves. 
 
     
     
         41 . The method of  claim 19  further comprising:
 forming welding protrusions on one of the first inner wall and the second inner wall, and forming welding grooves on the other of the first inner wall and the second inner wall, the welding grooves being shaped to receive the welding protrusions. 
 
     
     
         42 . The method of  claim 21  further comprising:
 forming welding protrusions on one of the plurality of first ribs and the plurality of second ribs; and 
 forming welding grooves on the other of the plurality of first ribs and the plurality of second ribs, the welding grooves being shaped to receive the welding protrusions. 
 
     
     
         43 . A method of forming a case for holding a semiconductor device comprising:
 forming a first cover;   forming a first inner wall on an inner surface of the first cover, the first inner wall separating an inner portion of the first cover into a first upper portion and a first lower portion;   forming a second cover with a second upper portion and a second lower portion;   forming a plurality of ribs on the inner surface of the first lower portion;   forming a recessed portion at a side edge of the first upper portion and a recessed portion at a side edge of the second upper portion such that the recessed portion of the first upper portion and the recessed portion of the second upper portion are symmetrical to each other and fit to each other, the recessed portion of the first upper portion being not extended to the first lower portion, the recessed portion of the second upper portion being not extended to the second lower portion; and   coupling the first cover and the second cover to hold the semiconductor device in an inner accommodating room defined by the first upper portion and the second upper portion.   
     
     
         44 . A method of manufacturing a semiconductor memory assembly comprising:
 forming a first cover;   separating an inner portion of the first cover into a first upper portion and a first lower portion by forming a first inner wall on an inner surface of the first cover;   forming a second cover with a second upper portion and a second lower portion;   forming a plurality of openings on the first upper portion;   forming a plurality of ribs on the inner surface of the first lower portion;   forming a recessed portion at a side edge of the first upper portion and a recessed portion at a side edge of the second upper portion such that the recessed portion of the first upper portion and the recessed portion of the second upper portion are symmetrical to each other and fit to each other, the recessed portion of the first upper portion being not extended to the first lower portion, the recessed portion of the second upper portion being not extended to the second lower portion;   mounting to the first upper portion or the second upper portion a memory module with a substrate and a semiconductor memory device mounted on the substrate; and   coupling the first cover and the second cover to hold the memory module in an inner accommodating room defined by the first upper portion and the second upper portion.   
     
     
         45 . The method of  claim 44 , wherein the substrate of the memory module is shaped substantially similar to the first upper portion and the second upper portion. 
     
     
         46 . The method of  claim 44 , wherein the substrate is a printed circuit board. 
     
     
         47 . A method of forming a case for holding a semiconductor device comprising:
 forming a first cover   separating an inner portion of the first cover into a first upper portion and a first lower portion by forming a first inner wall across an inner surface of the first cover;   forming a second cover with a second upper portion and a second lower portion, a contour of the first cover and a contour of the second cover being substantially symmetrical to each other such that the first cover and the second cover fit to form the case;   forming a welding portion at edges of the inner surface of the first cover and a welding portion at edges of an inner surface of the second cover, the welding portion of the first cover and the welding portion of the second cover protruding from the respective inner surface;   forming welding protrusions on the welding portion of one of the first cover and the second cover;   forming welding grooves on the welding portion of the other of the first cover and the second cover such that the welding grooves are shaped to receive the welding protrusions; and   coupling the first cover and the second cover to hold the semiconductor device in an inner accommodating room defined by the first upper portion and the second upper portion.