FIELD OF THE INVENTION 0001 The present invention relates to a socket connector and a contact for use in a socket connector, and more particularly, a socket connector for use in high frequency applications and in test and evaluation sockets.

BACKGROUND OF THE INVENTION 0002 A socket for a semiconductor package with a plurality of solder balls arranged in a grid shape has been conventionally known in, for example, Japanese Patent Application Laid-open No. Hei 8-222335. As shown in FIGS. 13 to 15, the socket 300 disclosed in the publication is provided with a contact 305 provided with a substantially U-shaped cross-sectional base 302 formed by punching out of a metal plate and having side walls 301 on both sides, a substantially C-shaped elastic contact piece 303 extending from the lower portion of the base 302 to the side wall 301 side, extending upwardly of the base 302 and having a contact portion 303a contacting in the vicinity of the tip end with a solder ball S owned by an IC package 400, and a contact portion 304 extending from the lower end portion of the base 302 to the opposite side to the contact piece 303. 0003 However, in the above-described conventional socket, in order that the solder ball S is in pressure contact with the contact portion 303a, the contact piece 303 is formed as an arcuate leaf spring. For this reason, it is difficult to shorten an electric path length from the contact portion 303a to the contact portion 304, it is impossible to reduce a self-inductance and it is impossible to test or evaluate the semiconductor package in a high frequency range. A socket, of the type shown in FIG. 16, provided at its upper and lower ends with contact portions and provided with a contact having a spring therebetween suffers from the same problems as described above.

SUMMARY OF THE INVENTION 0004 An object of the present invention is to provide a socket capable of performing a test or an evaluation of a semiconductor package in a high frequency range. 0005 Another object of the present invention is to provide a socket connector for using in a high frequency range. 0006 Another object of the present invention is to provide a socket in which the electric path length is shortened to reduce a self-inductance to thereby make it possible to perform a test or an evaluation of a semiconductor package (such as an IC package) in a high frequency range, and a contact for being mounted on the socket. 0007 In one embodiment of the present invention, the novel contact is used in a test evaluation socket for a semiconductor package, although the contact is not limited solely to test socket applications. Rather, the novel contact may be used in any application where shortened electric path length is desired. 0008 In one embodiment, the contact includes an arcuate leaf spring portion, a fixture portion for fixing said leaf spring portion to said socket connector, a contact portion provided at one end of said leaf spring portion, a conductive pattern contact portion provided at the other end of said leaf spring portion, a first contact piece provided at one end of said leaf spring, extending toward the other end of said leaf spring portion, and shiftable relative to said fixture portion, and a second contact piece provided at the other end of said leaf spring portion, extending toward one end of said leaf spring portion, and shiftable relative to said fixture portion. 0009 The first contact piece and said second contact piece are set so as to be out of contact with each other in a first condition and in contact with each other in a second position. 0010 The contact may contact with either a solder ball or a pin contact from the device being placed in contact with the contact. 0011 The first contact piece and said second contact piece may be set so as to form an electric path length substantially in a linear form under the condition that said first contact piece and said second contact piece are in contact with each other. 0012 Other objects, features and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS 0013 The features of this invention which are believed to be novel are set forth with particularity in the appended claims. The invention, together with its objects and the advantages thereof, may be best understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements in the figures and in which: 0014 FIG. 1 is a plan view showing a test evaluation socket in accordance with an embodiment of the present invention. 0015 FIG. 2 is a cross-sectional view showing a condition that the semiconductor package is mounted on the substrate connector in accordance with the embodiment of the present invention. 0016 FIG. 3 is a perspective view of a contact provided in the test evaluation socket in accordance with the embodiment of the present invention. 0017 FIG. 4 is a perspective view of the contact provided in the test evaluation socket in accordance with the embodiment of the present invention. 0018 FIG. 5 is a partially enlarged view of an A-A sectional view shown in FIG. 1. 0019 FIG. 6 is a partially enlarged view of a B-B sectional view of the test evaluation socket shown in FIG. 1. 0020 FIG. 7 is a partially enlarged view of a bottom surface 14 shown in FIG. 1. 0021 FIG. 8 is a plan view showing a test evaluation socket in accordance with another embodiment of the present invention. 0022 FIG. 9 is a cross-sectional view of the test evaluation socket shown in FIG. 8. 0023 FIG. 10 is a cross-sectional view of the test evaluation socket shown in FIG. 8. 0024 FIG. 11 is a cross-sectional view of the test evaluation socket shown in FIG. 8. 0025 FIG. 12 is a cross-sectional view of the test evaluation socket shown in FIG. 8. 0026 FIG. 13 is a view illustrative of a conventional socket. 0027 FIG. 14 is a frontal view of a contact provided in the conventional socket. 0028 FIG. 15 is a side view of the contact provided in the conventional socket. 0029 FIG. 16 is a view illustrative of the contact provided in the conventional socket.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 0030 A test evaluation socket for a semiconductor package in accordance with an embodiment of the present invention will now be described with reference to the accompanying drawings. 0031 As shown in FIGS. 1, 2 and 7, the test evaluation socket 10 is a BGA (Ball Grid Array) test evaluation socket for a semiconductor package 50 having on its bottom surface a plurality of solder balls S arranged in a grid shape. The test evaluation socket 10 is provided with a plurality of contacts 11, arranged in a grid shape corresponding to the arrangement of the solder balls S and a socket body 12 provided with the respective contacts 11. 0032 As shown in FIGS. 3, 5 and 6, each contact 11 is formed by bending a conductive metal plate. Each contact 11 is provided with an arcuate leaf spring portion 11a, a fixture portion 11b press fitted in a contact receiving hole 16 formed in the socket body 12 for fixing a substantially middle portion of the leaf spring portion 11a, a solder ball contact portion 11c provided outside one end of the leaf spring portion 11a and in pressing contact with the solder ball S, a conductive pattern contact portion 11d provided outside the other end of the leaf spring portion 11a and in pressing contact with a conductive pattern (not shown) of a substrate B, an upper contact piece 11e as a first contact piece provided at one end of the leaf spring portion 11a, extending in a linear manner toward the other end of the leaf spring portion 11a, and shiftable relative to the fixture portion 11b, and a cantilever type lower contact piece 11f as a second contact piece provided at a side surface of the other end of the leaf spring portion 11a, extending in a linear manner toward one end of the leaf spring portion 11a, and shiftable relative to the fixture portion 11b. 0033 Each length of the upper contact piece 11e and the lower contact piece 11f and each bending angle thereof to the leaf spring portion 11a are set such that the contact pieces are not brought into contact with each other under the condition that the solder ball S is not in contact with the solder ball contact portion 11c and the conductive pattern of the substrate B is not in contact with the conductive pattern contact portion 11d (see the contact 11 indicated by dotted lines in FIGS. 5 and 6). 0034 Also, each length of the upper contact piece 11e and the lower contact piece 11f and each bending angle thereof to the leaf spring portion 11a are set such that the contact pieces are brought into contact with each other under the condition that the solder ball S is in pressing contact with the solder ball contact portion 11c, the conductive pattern of the substrate B is in pressing contact with the conductive pattern contact portion 11f and both the upper contact piece and the lower contact piece are shifted in a direction close to each other (see the contact 11 indicated by solid lines in FIGS. 5 and 6). 0035 A slant surface 11g with which the lower contact piece 11f contacts is provided on the side surface of the upper contact piece 11e. With respect to the slant surface 11g, the tip end of the lower contact piece 11f is brought into linear contact with the slant surface 11g and moved relative thereto and along therewith in the process that the solder ball S comes into pressing contact with the solder ball contact portion 11c and the conductive pattern of the substrate B comes into pressing contact with the conductive pattern contact portion 11d so that the upper contact piece 11e and the lower contact piece 11f are shifted in the direction close to each other. The contact 11 indicated by the dotted lines in FIGS. 5 and 6 represents a position before the shift and the contact 11 indicated by the solid lines represents a position after the shift. 0036 The upper contact piece 11e and the lower contact piece 11f are set in a linear condition so as to form the electrical path length substantially in the linear manner under the condition that they are brought into contact with each other (see FIGS. 4, 5 and 6). 0037 As shown in FIGS. 1 and 2, a socket body 12 is formed into a box-shape having a substantially rectangular form in plane and is provided with an opening 13 into which the semiconductor package 50 is to be inserted, and a plurality of contact receiving holes 16, extending from the semiconductor package carrier surface 14 to a substrate facing surface 15. Also, bosses 15a that are to be inserted into boss holes (not shown) formed in the substrate B are provided in the substrate facing surface 15. 0038 Each contact receiving hole 16 is arranged in the grid shape corresponding to the arrangement of the solder balls S. As shown in FIGS. 5 and 6, solder ball receiving spaces 16a are located on the upper side of each contact receiving hole 16. 0039 Each contact 11 is received in the associated receiving hole 16 with its solder ball contact portion 11c located in the solder ball receiving space 16a and its conductive pattern contact portion 11d projecting from the substrate facing surface 15 (i.e., the condition indicated by the dotted lines of FIGS. 5 and 6). 0040 The operation of the test evaluation socket 10 for the semiconductor package with the above-described structure will now be described with reference to the drawings. 0041 First of all, the bosses 15a provided, respectively, at four corners of the bottom surface of the socket body 12 are inserted into the boss holes formed in the substrate B. Then, the socket body 12 and the substrate B are fixed to each other by means of the screw fastening holes 15b and screws N1 inserted in the screw holes formed in the substrate B and nuts N2. Under this condition, the conductive pattern contact portion 11d projecting from the substrate facing surface 15 of the socket body 12 is in pressing contact with the conductive pattern of the substrate B. Thus, the lower contact piece 11f is shifted in the direction close to the upper contact piece 11e. 0042 Subsequently, the semiconductor package 50 is inserted into the opening 13 of the socket body 12 and pressed against the semiconductor package carrier surface 14. Since the solder ball contact portion 11c of the contact 11 is located in the solder ball receiving space 16a, when the semiconductor package 50 is depressed against the semiconductor package carrier surface, the solder ball S is brought into pressing contact with the solder ball contact portion 11e and the upper contact piece 11e is shifted in the direction close to the lower contact piece 11f. The amount of shift thereof is limited by the contact of the lower surface (solder ball arrangement surface) of the semiconductor package 50 with the semiconductor package carrier surface 14. 0043 Since the slant surface 11g with which the lower contact piece 11f contacts is provided on the side surface of the upper contact piece 11e, under the process that the upper contact piece 11e and the lower contact piece 11f are shifted in the direction close to each other as described above, the slant surface 11g is brought into linear contact with the tip end of the lower contact piece 11f which is relatively moved to the slant surface 11g. Accordingly, since the respective amounts of shift in the upper and lower directions of the upper contact piece 11e and the lower contact piece 11f may be increased, it is possible to obtain the sufficient pressing contact by the action of the leaf spring portion 11a. The contact 11 shown by the dotted lines in FIG. 5 represents the position before the shift and the contact 11 indicated by the solid lines in FIG. 6 represents the position after the shift. 0044 Also, since the upper contact piece 11e and the lower contact piece 11f both extend in the linear manner, a new, substantially linear shortest electrical path length may be formed under the condition that the contact pieces are brought into linear contact with each other (see FIGS. 4, 5 and 6). Accordingly, it is possible to reduce the electrical path length to reduce the self-inductance, whereby it becomes possible to perform the test or the evaluation of the semiconductor package 50 in the high frequency range. Also, since the upper contact piece 11e and the lower contact piece 11f are brought into linear contact with each other, it is possible to ensure further stabilized and excellent contact. 0045 The semiconductor package 50 may be depressed against the semiconductor package carrier surface 14 by the well known mechanical device or by the manual work by the worker. Incidentally, the socket 10 and the contact 11 may also be used as PGA (Pin Grid Array) socket. 0046 A test evaluation socket for a semiconductor package in accordance with another embodiment of the present invention will now be described with reference to the drawings. Incidentally, the contact applied to the present socket is the same as that described above, the same reference numerals are used for explanation. 0047 FIG. 8 is a plan view of the test evaluation socket in accordance with the other embodiment of the present invention. FIGS. 9 to 12 are cross-sectional views of the test evaluation socket shown in FIG. 8. 0048 As shown in FIGS. 8 and 9, the test evaluation socket 110 is a test evaluation socket for a semiconductor package 150 having around its outer circumference a plurality of pin terminals P. The test evaluation socket 110 is provided with a plurality of contacts 11, arranged correspondingly to the arrangement of the pin terminals P and a socket body 112 provided with the respective contacts 11. 0049 As shown in FIGS. 3, 9 and 12, each contact 11 is formed by means of a bending work of a conductive metal plate. Each contact 11 is provided with an arcuate leaf spring portion 11a, a fixture portion 11b press fitted in a contact receiving hole 116 formed in the socket body 112 for fixing a substantially middle portion of the leaf spring portion 11a, a pin terminal contact portion 11c provided outside one end of the leaf spring portion 11a and in pressing contact with the pin terminal P, a conductive pattern contact portion 11d provided outside the other end of the leaf spring portion 11a and in pressing contact with a conductive pattern (not shown) of the substrate B, an upper contact piece 11e as a first contact piece provided at one end of the leaf spring portion 11a, extending in a linear manner toward the other end of the leaf spring portion 11a, and shiftable relative to the fixture portion 11b, and a cantilever type lower contact piece 11f as a second contact piece provided at a side surface of the other end of the leaf spring portion 11a, extending in a linear manner toward one end of the leaf spring portion 11a and shiftable relative to the fixture portion 11b. 0050 Each length of the upper contact piece 11e and the lower contact piece 11f and each bending angle thereof to the leaf spring portion 11a are set such that the contact pieces are not brought into contact with each other under the condition that the pin terminal P is not in contact with the pin terminal contact portion 11c and the conductive pattern of the substrate B is not in contact with the conductive pattern contact portion 11d (see the contact 11 as indicated by dotted lines in FIGS. 3 and 11). 0051 Also, each length of the upper contact piece 11e and the lower contact piece 11f and each bending angle thereof to the leaf spring portion 11a are set such that the contact pieces are brought into contact with each other under the condition that the pin terminal P is in pressing contact with the pin terminal contact portion 11c, the conductive pattern of the substrate B is in pressing contact with the conductive pattern contact portion 11f, and both the upper contact piece and the lower contact piece are shifted in a direction close to each other (see the contact 11 indicated by solid lines in FIG. 11). 0052 A slant surface 11g with which the lower contact piece 11f contacts is provided on the side surface of the upper contact piece 11e. With respect to the slant surface 11g, the tip end of the lower contact piece 11f brought into linear contact with the slant surface 11g and moved relative thereto and along therewith in the process that the pin terminal P comes into pressing contact with the pin terminal contact portion 11c and the conductive pattern of the substrate B comes into pressing contact with the conductive pattern contact portion 11d so that the upper contact piece 11e and the lower contact piece 11f are shifted in the direction close to each other (see FIGS. 9, 10 and 11). The contact 11 indicated by the dotted line in FIG. 11 represents a position before the shift and the contact 11 indicated by the solid line represents a position after the shift. 0053 The upper contact piece 11e and the lower contact piece 11f are set in a linear condition so as to form the electrical path length substantially in the linear manner under the condition that they are brought into contact with each other (see FIGS. 4, 11 and 12). 0054 As shown in FIG. 8, a socket body 112 is formed into a box-shape having a substantially rectangular form in plane and is provided with an opening 113 into which the semiconductor package 150 is to be inserted. The semiconductor package 150 includes a semiconductor package carrier plate 114 mounted on a bottom surface 113a of the opening 113 of the socket body 112 through springs SP and is reciprocatingly movable between a first position (upper end position) and a second position (lower end position) within the opening 113. 0055 The upper end position is a position where the semiconductor package 150 is laid on the semiconductor package carrier plate 114 with its pin terminals P projected from a circumferential edge of the semiconductor package carrier plate 114 (see FIG. 9). The lower end position is a position where the projected pin terminals P comes into pressing contact with the pin terminal contact portions 11c (see FIG. 11). 0056 Also, the socket body 112 is provided with a substrate facing surface 115 opposite to the bottom surface 113a and a plurality of contact receiving holes 116, bored through from the bottom surface 113a to the substrate facing surface 115. Also, bosses 115a to be inserted into the boss holes (not shown) formed in the substrate B are provided in the substrate facing surface 115. 0057 Each contact receiving hole 16 is arranged correspondingly to the arrangement of the pin terminals P. Each contact 11 is received in the associated contact receiving hole 116 with its pin terminal contact portion 11c projected from the bottom surface 113 and its conductive pattern contact portion 11d projected from the substrate facing surface 115 (i.e., the condition indicated by dotted line of FIG. 11). 0058 The operation of the test evaluation socket 110 for the semiconductor package with the above-described structure will now be described with reference to the drawings. 0059 First of all, the bosses 115a provided, respectively, at four corners of the bottom surface of the socket body 112 are inserted into the boss holes formed in the substrate B. Then, the socket body 112 and the substrate B are fixed to each other by means of the screw fastening holes 115b and screws N1 inserted in the screw holes formed in the substrate B and nuts N2. Under this condition, the conductive pattern contact portion 11d projecting from the substrate facing surface 115 of the socket body 112 is brought into pressing contact with the conductive pattern of the substrate B. Thus, the lower contact piece 11f is shifted in the direction close to the upper contact piece 11e. 0060 Subsequently, the semiconductor package 150 is inserted into the opening 113 of the socket body 112 and pressed against the semiconductor package carrier plate 114. Since the semiconductor package carrier plate 114 is mounted on the bottom surface 113a of the opening 113 of the socket body 112 through the springs SP, when the semiconductor package 150 is depressed against the semiconductor package carrier plate 114, the pin terminal contact portion 11e is brought into pressing contact with the pin terminal contact portion 11c and the upper contact piece 11e is shifted in the direction close to the lower contact piece 11f. The amount of shift thereof is limited by the contact of the lower surface of the semiconductor package carrier plate 114 with the bottom surface 113a of the opening 113. 0061 Since the slant surface 11g with which the lower contact piece 11f contacts is provided on the side surface of the upper contact piece 11e, under the process that the upper contact piece 11e and the lower contact piece 111f are shifted in the direction close to each other as described above, the slant surface 11g is brought into linear contact with the tip end of the lower contact piece 11f which is relatively moved to the slant surface 11g. Accordingly, since the respective amounts of shift in the upper and lower directions of the upper contact piece 11e and the lower contact piece 11f may be increased, it is possible to obtain the sufficient pressing contact by the action of the leaf spring portion 11a. The contact 11 shown by the dotted line in FIG. 11 represents the position before the shift and the contact 11 indicated by the solid line represents the position after the shift. 0062 Also, since the upper contact piece 11e the lower contact piece 11f both extend in the linear manner, a new, substantially linear shortest electrical path length may be formed under the condition that the contact pieces are brought into contact with each other (FIGS. 4, 11 and 12). Accordingly, it is possible to reduce the electrical path length to reduce the self-inductance, whereby it becomes possible to perform the test or the evaluation of the semiconductor package 50 in the high frequency range. Also, since the upper contact piece 11e and the lower contact piece 11f are brought into linear contact with each other, it is possible to ensure further stabilized and excellent contact. 0063 The semiconductor package 150 may be gripped by the well known mechanical device M or depressed against the semiconductor package carrier surface 14 by the manual work by the worker. 0064 It will be understood that the invention may be embodied in other specific forms without departing from the spirit or central characteristics thereof. The present examples and embodiments, therefore, are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein.