Heat sink

Abstract

A heat sink includes a plurality of fins arranged parallel to each other. The fins include a first fin, a second fin, a third fin, a fourth fin, and a plurality of middle fins sandwiched between the third fin and the fourth fin. The first fin is at an outmost side of the heat sink. The first fin has a protrusion. The second fin is located at an opposite outmost side of the heat sink. The third fin is adjacent to the first fin. The protrusion of the first fin abuts against the third fin. The fourth fin is adjacent to the second fin and has a protrusion to abut against the second fin. The middle fins being flat with no protrusions.

1 . A heat sink comprising a plurality of fins arranged parallel to each other, the fins comprising:
 a first fin at an outmost side of the heat sink, the first fin comprising a protrusion;   a second fin at an opposite outmost side of the heat sink;   a third fin adjacent to the first fin, the protrusion abutting against the third fin;   a fourth fin adjacent to the second fin, the fourth fin comprising another protrusion abutting against the second fin; and   a plurality of middle fins sandwiched between the third fin and the fourth fin, the middle fins being flat with no protrusions.   
     
     
         2 . The heat sink of  claim 1 , wherein each of the fins has two flanges extending from opposite sides thereof. 
     
     
         3 . The heat sink of  claim 2 , wherein the protrusions of the first fin and the fourth fin are formed between the flanges. 
     
     
         4 . The heat sink of  claim 3 , wherein the protrusions of the first fin and the fourth fin are punched from middle portions of the first fin and the fourth fin. 
     
     
         5 . The heat sink of  claim 1 , wherein each of the protrusions has a trapezoid-shaped cross section. 
     
     
         6 . The heat sink of  claim 5 , wherein the protrusion of the first fin has a narrow portion abutting against the third fin and two inclined portions interconnecting the first fin and the narrow portion. 
     
     
         7 . The heat sink of  claim 5 , wherein the protrusion of the fourth fin has a narrow portion abutting against the second fin and two inclined portions interconnecting the fourth fin and the narrow portion. 
     
     
         8 . A heat sink comprising a plurality of fins arranged parallel to each other, each of the fins comprising a body and two flanges extending from opposite sides of the body, the fins comprising:
 an outermost fin;   an adjacent fin adjacent to the outermost fin;   a plurality of middle fins sandwiched between the adjacent fins, the body of each middle fin being flat with no protrusion; and   at least a protrusion extending from the body of one of the outermost fin and the adjacent fin to contact the other one of the outermost fin and the adjacent fin.   
     
     
         9 . The heat sink of  claim 8 , wherein the protrusion and the flanges of the same fin are located at opposite sides of the body of the corresponding fin. 
     
     
         10 . The heat sink of  claim 8 , wherein the protrusion is formed between the flanges. 
     
     
         11 . The heat sink of  claim 8 , wherein the protrusion is punched from a middle portion of the outermost fin to the adjacent fin. 
     
     
         12 . The heat sink of  claim 11 , wherein the protrusion has a narrow portion abutting against the adjacent fin and two inclined portions interconnecting the outermost fin and the narrow portion. 
     
     
         13 . The heat sink of  claim 8 , wherein the protrusion is punched from a middle portion of the adjacent fin to the outermost fin. 
     
     
         14 . The heat sink of  claim 13 , wherein the protrusion has a narrow portion abutting against the outermost fin and two inclined portions interconnecting the adjacent fin and the narrow portion. 
     
     
         15 . The heat sink of  claim 8 , wherein the protrusion has a trapezoid-shaped cross section.