Patent Publication Number: US-6699047-B1

Title: Electrical connector with retention protrusions

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an electrical connector for electrically connecting an electronic package such as a land grid array (LGA) chip with a circuit substrate such as a printed circuit board (PCB), and particularly to an electrical connector with improved retention protrusions for conveniently and securely positioning an LGA chip in the electrical connector. 
     2. Description of the Prior Art 
     Land grid array (LGA) electrical connectors are widely used in the connector industry for electrically connecting LGA chips to printed circuit boards (PCBs) in personal computers (PCs). Details are provided in “Nonlinear Analysis Helps Design LGA Connectors” (Connector Specifier, February 2001, pp. 18-20). Conventionally, one kind of the LGA connector mainly comprises an insulative housing, a multiplicity of terminals received therein, and a load plate and a cam lever pivotably mounting on two opposite sides of the housing. The housing defines a multiplicity of terminal passageways in a rectangular array, for interferentially receiving corresponding terminals. Due to the very high density of the terminal array which an LGA chip may have, the LGA chip needs to be precisely seated on the LGA connector. This is to ensure reliable signal transmission between the terminals and the LGA chip. For example, means for accurately attaching an LGA chip to an LGA connector are disclosed in U.S. Pat. Nos. 4,504,105 and 4,692,790. 
     Referring to FIG. 5, a conventional LGA connector  6  comprises an insulative housing  60 , a multiplicity of terminals  61  received in the housing  60 , and a load plate  62  and a cam lever  63  pivotably mounted on two opposite sides of the housing  60 . The load plate  62  defines a channel  620  receiving the cam lever  63 . To mount an LGA chip (not shown) on the LGA connector  6 , the load plate  62  is rotated up until it is perpendicular to the housing  60 . The LGA chip is seated in the housing  60 , and is loosely engaged with the terminals  61 . The load plate  62  is rotated down so that it rests on the LGA chip. The cam lever  63  is rotated down until it engages in the channel  620  of the load plate  62 . When the cam lever  63  has reached the end of its travel, the load plate  62  presses the LGA chip into firm engagement with the terminals  61  of the connector  6 . 
     In the above-described assembly process, the load plate  62  presses the LGA chip between two opposite sides of the housing  60  of the connector  6 . Generally, a material of the housing  60  is not resilient, and the sides of the housing  60  can not elastically deform under pressure from the LGA chip. If the LGA chip is narrower than a distance between the opposite sides of the housing  60 , the LGA chip may be poorly positioned relative to the terminals  61 . This can adversely affect mechanical and electrical connection between the LGA chip and the connector  6 . If the LGA chip is wider than a distance between the opposite sides of the housing  60 , the housing  60  is liable to break. Furthermore, when the load plate  62  presses the LGA chip to firmly engage with the terminals  61 , the housing  60  is liable to break if asymmetrical force is inadvertently applied thereto. 
     FIG. 6 shows another conventional LGA connector  6 ′ devised to overcome the above-described problem. The connector  6 ′ comprises an insulative housing  60 ′, and a multiplicity of terminals  61 ′ received therein. In forming the connector  6 ′, a carrier strip (not shown) is used. The carrier strip comprises a row of the terminals  61 ′, and a row of connecting sections (not shown) respectively connecting the terminals  61 ′ with a main body of the carrier strip. The housing  60 ′ comprises four raised sidewalls  62 ′, and a flat base  63 ′ disposed between the sidewalls  62 ′. The base  63 ′ and the sidewalls  62 ′ cooperatively define a space therebetween for receiving an LGA chip (not shown) therein. The base  63 ′ defines a multiplicity of terminal passageways  64 ′ for receiving the terminals  61 ′ therein. When the LGA chip is seated on the LGA connector  6 ′, the four sidewalls  62 ′ can securely engage the LGA chip therebetween. 
     However, installation of terminals  61 ′ into those passageways  64  near two of the sidewalls  62 ′ is problematic. Once the terminals  61 ′ have been inserted into such passageways  64 ′, the connecting sections of the carrier strip must be cut from their corresponding terminals  61 ′. Because the carrier strip is located close to the relevant sidewall  62 ′, there is insufficient space to manipulate the carrier strip to allow easy cutting off of the connecting sections. Such manipulation is blocked by the sidewall  62 , which is liable to sustain damage as a result. 
     Therefore, a new LGA electrical connector which overcomes the above-mentioned problems is desired. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an electrical connector for electrically connecting an electronic package such as a land grid array (LGA) chip with a circuit substrate such as a printed circuit board (PCB), whereby the electrical connector can quickly and conveniently guide the LGA chip into its correct position. 
     Another object of the present invention is to provide an electrical connector having means for accurately positioning an electronic package such as an LGA chip thereon, whereby manufacturing and transportation costs of the electrical connector are reduced. 
     To achieve the above objects, an electrical connector in accordance with a preferred embodiment of the present invention is for connecting an LGA chip with a PCB. The connector includes an insulative housing, a frame engaged with the housing, and a plurality of terminals received in the housing. The housing defines four sides. A plurality of arcuate protrusions is formed on two adjacent of the sides. The frame has four sidewalls defining a central cavity therebetween for receiving the LGA chip therein. Two adjacent of the sidewalls define a plurality of cutouts in respective inner faces thereof, corresponding to the protrusions respectively. The frame is mounted on the housing, with the protrusions being engagingly received in the corresponding cutouts. When the LGA chip is engaged with the connector, the protrusions elastically deform to accurately guide and securely fix the LGA chip in the connector. 
    
    
     Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which: 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a simplified, exploded isometric view of an LGA electrical connector in accordance with a preferred embodiment of the present invention, together with an LGA chip; 
     FIG. 2 is an assembled view of the LGA electrical connector of FIG. 1; 
     FIG. 3 is an assembled view of FIG. 1; 
     FIG. 4 is an enlarged view of a circled portion IV of FIG. 3; 
     FIG. 5 is a simplified, exploded isometric view of a conventional LGA electrical connector; and 
     FIG. 6 is a simplified, exploded isometric view of another conventional LGA electrical connector. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Reference will now be made to the drawings to describe the present invention in detail. 
     Referring to FIGS. 1 and 2, an LGA electrical connector  1  in accordance with a preferred embodiment of the present invention comprises an insulative housing  12 , a frame  11  engaged with the housing  12 , and a multiplicity of terminals  13  received in the housing  12 . An LGA chip  2  comprises a top surface  20  and a bottom surface  21  opposite from the top surface  20 . A multiplicity of pins (not shown) depends from the bottom surface  21 , for engaging with the terminals  13  of the connector  1 . A raised heat sink portion  200  is formed at a middle of the top surface  20 , for contacting a heat sink (not shown). 
     The housing  12  is formed by molding, and is substantially rectangular. The housing  12  defines two opposite first sides  122 , two opposite second sides  123  interconnecting the first sides  122 , and a flat base  124  disposed between the first and second sides  122 ,  123 . The base  124  defines a space thereabove for receiving the LGA chip  2  thereon. The base  124  defines a multiplicity of terminal passageways  120  in a rectangular array, for interferentially receiving corresponding terminals  13  therein. One of the first sides  122  has two spaced first protrusions  1220  formed thereon, and one of the second sides  123  has a second protrusion  1230  formed thereon. A cross-section of each of the first and second protrusions  1220 ,  1230  is arcuate. Upper portions of the first and second protrusions  1220 ,  1230  are beveled, with the bevels facing generally toward a middle of the housing  12 . In addition, the first and second protrusions  1223 ,  1230  can elastically deform. Thus the LGA chip  2  can be guidably fixed between the first protrusions  1220  and the second protrusion  1230 . Two bifurcated latches  121  are formed on two diagonally opposite corners of the base  124 , such that one of the latches  121  is between the second protrusion  1230  and the first protrusions  1220 . Two extension portions  1221  extend coplanarly outwardly from the two opposite first sides  122  respectively. The extension portions  1221  are offset relative to each other such that they are substantially diagonally opposite each other. Two alignment posts  1222  are formed at the extension portions  1221  respectively. Each alignment post  1222  integrally spans from above a top face of the extension portion  1221  to below a bottom face of the extension portion  1221 . The alignment posts  1222  are for engagingly fixing the connector I on a PCB (not shown). 
     The frame  11  comprises a raised first sidewall  110 , a raised second sidewall  113 , a raised third sidewall  114  and a raised fourth sidewall  115 . A central cavity,  111  is defined between the four sidewalls  110 ,  113 ,  114 ,  115 , and is sized to receive the housing  12 . Cutouts  1110 ,  1130  are defined in respective inner faces of the first and second sidewalls  110 ,  113 , corresponding to the first and second protrusions  1220 ,  1230  respectively. Two holes  112  are defined in two diagonally opposite corners of the frame  11 , corresponding to the latches  121 . Apertures  1102  are respectively defined in the first and third sidewalls  110 ,  114 , corresponding to the alignment posts  1222  of the extension portions  1221 . Two spring members  1140 ,  1141  are formed at inside faces of the third sidewall  114 . Two spring members  1150 ,  1151  are formed at inside faces of the fourth sidewall  115 . 
     In assembly of the connector  1 , the terminals  13  are inserted into the terminal passageways  120  along a direction that is perpendicular to the base  124  of the housing  12 . The frame  11  is mounted on the housing  12 . The latches  121  are engagingly received in the holes  112 , the first protrusions  1220  and the second protrusion  1230  are engagingly received in the corresponding cutouts  1100 ,  1130 , and the alignment posts  1222  are engagingly received in the apertures  1102 . Thus, assembly of the LGA connector  1  is completed. Because the first and second protrusions  1220 ,  1230  are arcuate, less material is needed for making the housing  12 . This reduces manufacturing costs, and makes the connector  1  lighter. This accordingly reduces transportation costs of the connector  1 . 
     Referring to FIGS. 3 and 4, the LGA chip  2  is then pushed onto the housing  12  of the connector  1 . The pins of the LGA chip  2  are engaged with the terminals  13 , thus connecting the LGA chip  2  with the connector  1 . The first protrusions  1220  of the first side  122 , the second protrusion  1230  of the second side  123 , and the alignment posts  1222  of the first sides  1220  cooperate to precisely fittingly position the LGA chip  2  therebetween. The first and second protrusions  1220 ,  1230  and the spring members  1140 ,  1141 ,  1150 ,  1151  elastically deform when the LGA chip  2  engages with the connector  1 . This ensures that the engagement between the terminals  13  and pins of the LGA chip  2  is accurate and reliable. The first and second protrusions  1220 ,  1230  enable the LGA chip  2  to be quickly and conveniently guided into its correct position in the space above the base  124  of the housing  12 . 
     While a preferred embodiment in accordance with the present invention has been shown and described, equivalent modifications and changes known to persons skilled in the art according to the spirit of the present invention are considered within the scope of the present invention as defined in the appended claims.