Socket for electronic part

In a connector board (socket) for an electronic component, each electrode member is a leaf spring formed by bending a conductive plate into a substantially U-shape with an opening facing substantially parallel to a surface of the connector board. A first contact is unitary with one free end of the leaf spring and is held in electrical contact with a corresponding terminal of electronic component, and a second contact is unitary with the other free end of the leaf spring and is held in electrical contact with a corresponding terminal of a printed circuit board. The leaf spring includes a first leg which extends substantially in parallel with a surface of the connector board, a coupling portion which is unitary with the first leg, and a second leg which is unitary with the coupling portion so as to oppose the first leg and which extends obliquely toward a surface of the connector board. Engagement elements are seated within grooves provided in partition walls and are formed unitarily with the coupling portion.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a connector board for connecting an electronic component to a printed circuit board. More particularly, it relates to a connector board (or “socket”) which is so designed that, when the electronic component of a CPO, an MPU or the like is pushed against it, the electrode terminals of the electronic component and those of a printed circuit board can be electrically connected through electrode portions disposed in the connector board.

2. Description of the Related Art

One known type of connector board for an electronic component is so constructed that, when the electronic component is pushed against the connector board, the electrical contact between the electrode terminals of the electronic component and the electrode portions of the connector board is maintained, while the electrode portions of the connector board are connected to the electrode terminals of a printed circuit board (refer to, for example, U.S. Pat. No. 6,004,141).

With the connector board for the electronic component, a clamping member is coupled to one end edge portion of the socket body, and it is swung about in the coupled state, to thereby urge the electronic component onto the connector board. A hook which is mounted to the other end of the clamping member is engaged with an engaging portion of the connector board. Thus, the electronic component is fixed (mounted) on the connector board, and the electrical contact between the electrode terminals of the electronic component and the electrode portions of the connector board is maintained.

As shown inFIG. 15, each of the electrode portions of the connector board includes a sliding contact10which comes into contact with the corresponding electrode terminal of the electronic component, and a spring contact20, which is the form of a leaf spring, lies in contact with the sliding contact10. The sliding contact10and the spring contact20are arranged in opposition within the recess40of the connector board30.

When the electronic component is pushed against the connector board30, the contact point50between the sliding contact10and the spring contact20is slidably moved in a direction b, perpendicular to a pushing direction a. In turn, the degree of pressure of the contact between the sliding contact10and the spring contact20increases in proportion to the amount of movement of the sliding contact10owing to the resilience of the spring contact20.

In a connector board thus constructed, electrical contact between the electrode terminals of the electronic component and the electrode portions of the connector board is not harmed by the attachment or detachment of the electronic component. Moreover, the electrode portions are comparatively simple in structure and are easy to fabricate.

However, such a connector board remains unsatisfactory for the reasons stated below. Since each electrode portion of the connector board has a so-called “two-piece contact structure”, consisting of the sliding contact10and the spring contact20, the contact point50between the sliding contact10and the spring contact20may unintentionally slide to make the contact pressure unstable, depending upon the state of the contact position between the two. Moreover, the contacts have complicated shapes and are in two parts, so that the workability and assembly of the contacts are difficult, and the cost thereof is comparatively high. Further, since the displacement of the spring contact20is within the connector board30, the connector board30itself must be sufficiently thick to allow for the displacement of the spring contact20.

SUMMARY OF THE INVENTION

The present invention has been made in order to eliminate such difficulties, and it has for its object provision of a connector board for electrically connecting electrode terminals of an electronic component with a printed circuit board which facilitates the assembly of the electrode terminals, which provides a stable contact resistance, which allows reduction in the thickness of a connector board and which is comparatively low in cost.

In order to accomplish the above object, the present invention provides a connector board including: an insulating plate having opposing surfaces extending in longitudinal and lateral dimensions and having recesses, each of the recesses being defined by opposing parallel side walls defining therebetween an opening at one of the opposing surfaces and extending from the opening toward the other opposing surface; and leaf spring electrode members mounted in the recesses, each leaf spring electrode member formed by bending a conductive plate material across its minor dimension (intermediate bend), into substantially a U-shape with first and second straight leg portions, and by bending it across its minor dimension adjacent both of its distal ends to form first and second distal contact sections extending from respective straight leg sections, outwardly of the insulating plate, beyond respective opposing surfaces of the insulating plate. Placement of a circuit board or electrical component against a surface of the insulating plate displaces the distal contact sections inwardly, into the recesses, against the spring forces of the leaf spring electrode member.

In a preferred embodiment, the first straight leg sections are in parallel with the opposing surfaces of the insulating plate and the second straight leg sections extend from the intermediate bend obliquely relative to the surfaces of the insulating plate.

Preferably, the length of the obliquely extending second straight leg sections of the leaf spring electrodes is longer than the length of the parallel extending first straight leg sections.

Preferably, the leaf spring electrode members include unitary engagement pieces extending from their sides toward the sidewalls of the recess and fitted in engagement with first engagement grooves which are provided in the sidewalls.

In another embodiment the leaf spring electrode member includes unitary shafts extending from its sides toward the sidewalls of the recess, and rotatably supported by bearings provided in the sidewalls.

In yet another embodiment, the electrode member includes unitary extension elements extending from its sides toward sidewalls of the recess, and engagement elements unitary with ends of the extension elements and extending in parallel with the sidewalls, with the engagement elements fitted within engagement grooves in the sidewalls.

According to the present invention, each electrode member has a simple, single-piece construction, so that the workability and assembly of the electrode member are sharply enhanced, and the cost thereof becomes comparatively low. Moreover, the electrical contact between each of the first distal contact sections and the corresponding electrode terminal of the electronic component (or a printed circuit board) is at an oblique angle so that the length of the leaf spring electrode member can be increased. In turn, even when the thickness of a connector board itself is small, each terminal of the electronic component and the corresponding terminal of the printed circuit board can be reliably brought into electrical contact, and a stable contact pressure can be attained.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, preferred embodiments of a connector board (or “socket”) for an electronic component according to the present invention will be described in detail with reference to the drawings.

Referring toFIG. 1, an electronic component1is shown in the form of, for example, a BGA (Ball Grid Array) and as including a housing1a, and a large number of connection terminals1bwhich are arrayed in a grid on the back surface of the housing1a. The connection terminals1bare spherical solder balls or the like.

As shown inFIG. 2, a connector board according to the present invention includes a body portion2and electrode members2afor connection with the electrode terminals1b(refer toFIG. 1) of the electronic component1, arranged substantially in the center of the principal surface thereof, a socket cover3which is pivotally mounted at one end edge of the connector board2, and a lever4which is pivotally mounted on the other end edge side of the connector board2.

As shown inFIG. 3, the body portion2includes a rectangular flat plate5, and a plate-like lining6which has the same shape as that bf the flat plate5and which is affixed onto the rear surface of the flat plate5. The flat plate5and the lining6are formed of an insulating plastic material or the like.

The flat plate5includes a plurality of laterally elongated recesses51in its rear surface52. The recesses51are arranged in so-called “columns” across the width (direction A) of the flat plate member5and with partition walls54therebetween. Here, each of the recesses51extends to a predetermined depth (equal to about ⅘ of the thickness of the flat plate member5) in the thickness (direction B) of the flat plate member5from the rear surface52thereof.

The opposing sidewalls54aof each recess51are provided with pairs of engagement grooves (hereinbelow, termed “first engagement grooves”)55at predetermined intervals along the length (direction C) of the recess51. Here, each of the first engagement grooves55extends over a predetermined length (a length equal to about ⅓ of the thickness of the flat plate member5) in the thickness direction B of the flat plate member5, from the rear surface52thereof.

A plurality of insertion holes (hereinafter, “first insertion holes”)56are provided in the upper surface53of the flat plate member5corresponding to respective recesses51, and are arranged at predetermined intervals along the length (direction C) of the recesses51. Also, a plurality of insertion holes (hereinafter, “second insertion holes”)61are provided in the lining member6corresponding to the respective recesses51, and arranged at predetermined intervals along the length (direction C) of the recesses51. Thus, the first insertion holes56are provided in a grid array at the upper surface of the body portion2so as to correspond to the electrode terminals1bof the electronic component1, while the second insertion holes61are provided in a grid array at the lower surface of the body portion2so as to correspond to the electrode terminals9a(refer toFIG. 6) of a printed circuit board9(refer toFIG. 5). Thus, the first insertion holes56are in communication with the corresponding second insertion holes61through the respective recesses51. Here, the dimension of each of the first insertion holes56in the C-direction is about 3–4 times the dimension of the second insertion hole61in the C-direction. The second insertion holes61are positioned substantially opposite the upper surface “hole surrounding portions”53aof the flat plate member5which surround the first insertion holes56, and the first engagement grooves55are provided near the second insertion holes61which are adjacent the left side as viewed in the figure.

As shown inFIG. 4, each of electrode members2aincludes a leaf spring portion7which is a conductive plate member bent substantially in the shape of letter U at an intermediate bend or coupling portion72and which forms an opening7afacing in the lengthwise direction C of the recess51, substantially perpendicular to the thickness direction B (refer toFIG. 3) of the body portion2. A first distal contact section8a(hereinafter, “first contact”) is formed by a bend across the minor dimension b adjacent one free (distal) end of the leaf spring electrode7, and comes into electrical contact with the electrode terminal1bof the electronic component1. Likewise, a second distal contact section8b(hereinafter “second contact”), which is unitary with the other free end of the leaf spring portion7, is formed by another bend adjacent the other fee end and comes into electrical contact with the terminal9aof the printed circuit board9.

The leaf spring electrode member7includes a first straight leg section71which is arranged substantially in parallel with the surface of the printed circuit board9, the coupling portion (intermediate bend)72which is unitary and connected with one end of the first straight leg71so as to extend in the thickness direction (B-direction) of the body portion2, and an obliquely extending second straight leg portion73which is unitarily connected to the coupling portion72so as to oppose to the first straight leg portion71and to extend obliquely toward the electronic component1. A pair of engagement pieces (hereinafter “first engagement pieces”)72aand72b, which are received in the first engagement grooves55, are unitarily connected to the sides of the coupling portion72so as to protrude toward the first engagement grooves55. Here, the lateral width of the recess51(the “A” dimension) is substantially equal to or somewhat larger than the width of the leaf spring member7. The A dimension between the opposing pair of first engagement grooves55is set to be substantially equal to or somewhat larger than the dimension between the opposing ends of the pair of first engagement pieces72aand72b. The groove width of each of the first engagement grooves55is set to be substantially equal to or somewhat larger than the plate thickness of the first engagement pieces72aand72b.

Subsequently, the distal end portion of the obliquely extending second straight leg73, which constitutes the leaf spring portion7, is bent toward the side of the electronic component1so as to be substantially perpendicular to the obliquely extending portion73, and the distal end part of the parallel extending first straight leg portion71is bent toward the side of the printed circuit board9so as to be substantially perpendicular to the parallel extending first straight leg portion71. Thus, the first contact8a, which comes into electrical contact with the electrode terminal1bof the electronic component1, is formed at the distal end of the obliquely extending portion73, and the second contact8b, which comes into electrical contact with the electrode terminal9aof the printed circuit board9, is formed at the distal end of the parallel extending portion71. The electrode member2aas described above can be formed from one piece of plate material (length: 3 mm, width: 0.5 mm, and thickness: 0.06–0.08 mm) of, for example, phosphor bronze.

Next will be described a method for mounting the electrode members2ain the corresponding recesses51of the body portion2. First, the flat plate5is inverted as shown inFIG. 3, whereby the openings of the recesses51, arranged as columns, face upwards. Subsequently, each of the electrode members2ais inserted into a recess51with its opening7afacing in the lengthwise direction C of the recess51, that is, with the pair of first engagement pieces72aand72bperpendicular to the sides of the recess and fitted within a pair of first engagement grooves55. Thus, as shown inFIG. 5, the distal end first contact8aof each electrode member2aextends through a corresponding first insertion hole56, and protrudes about 0.3 mm beyond the upper surface53of the flat plate5. Also, the distal end second contact8bprotrudes about 0.6 mm beyond the rear surface52of the flat plate5.

In this way, the electrode members2aare respectively received in the corresponding recesses51and are disposed in a grid array. Thereafter, the lining member6is adhered to the rear surface52of the flat member5so as to be united with this member5. Thus, as shown inFIG. 5, the distal ends of the second contacts8bof the electrode member2apass through the corresponding second insertion holes61, respectively, so that they protrude about 0.25 mm beyond the rear surface63of the lining member6.

In the first embodiment, as shown inFIG. 6, the lengthwise dimension L1of the obliquely extending second straight leg portion73is nearly double the lengthwise dimension L2of the first straight leg portion71. Thus, the electrical contact (hereinbelow, termed “first electrical contact portion”) P1between the first contact8aand the electrode terminal1bof the electronic component1is at an oblique angle and a second electrical contact portion P2is established between the second contact8band the terminal9aof the printed circuit board9. A vertical line V1which passes through the first electrical contact portion P1is spaced a predetermined distance L3(about 0.5 mm) in the lengthwise direction C from a vertical line V2which passes through the second electrical contact portion P2.

Next, a method for electrically connecting the terminals1bof the electronic component1and the terminals9aof the printed circuit board9, through the electrode members2a, will be described with reference toFIG. 2,FIGS. 7A–7CandFIGS. 8A–8E. Incidentally, for brevity of description,FIGS. 7A–7Cillustrate three electrode members2a, and the terminals1bof the electronic component1and the terminals9aof the printed circuit board9which correspond to these electrode members2a.

As shown inFIG. 7A, the distal end of the first contact8aof each electrode member2aprotrudes beyond the upper surface of the body portion2, and the distal end of the second contact8bprotrudes beyond the rear surface of the body portion2. In this state, as shown inFIG. 7B, the body portion2is placed on the printed circuit board9so that the distal ends of the second contacts8bof the electrode members2acome into electrical contact with the corresponding terminals9aof the printed circuit board9, as the body2is pushed against the side of the printed circuit board9. Then, since the pair of first engagement pieces71aand71bare fixed within the pair of first engagement grooves55, the parallel extending first straight leg sections71of the electrode members2amove slightly away from (float) the upper surface of the printed circuit board9while electrical contact is established between the distal ends of the second contacts8bof the electrode members2aand the terminals9aof the printed circuit board9.

Subsequently, as shown inFIG. 8A, the electronic component1is received into the concave portion2d(refer toFIG. 2) of the body portion2, and the cover3is pivoted onto the body portion2. Thus, as shown inFIG. 7C, the terminals1bof the electronic component1and the distal ends of the first contacts8aof the electrode members2acome into electrical contact, and the electronic component1is lightly pressed by a first pawl3a(refer toFIG. 2) which is provided in the cover3. With the free end of the socket cover3pivoted toward the end edge of the body2(toward the right side as viewed in the figure), the grip4aof the hand lever4is partially turned toward the other end edge of the body2(onto the left side as viewed in the figure) as indicated by two-dot chain lines, until a clasp member4b(refer toFIG. 2) integral with the lever4is brought into engagement with a catch3e(refer toFIG. 2) which is provided on the free end side of the cover3. Thus, the electronic component1is fixed by first–fourth pawls3a–3d(refer toFIG. 2) provided in the socket cover3, in a state where the electrical contact between the electrode terminals1bof the electronic component1and the distal ends of the first contacts8aof the electrode member2aassume the position shown inFIG. 7C. Subsequently, as shown inFIG. 8C, the grip4aof the lever4is further turned toward the other end edge of the body2. When the arm portion4cof the lever4has arrived over a hook2eprovided on the side edge portion of the socket body2, it is somewhat shifted laterally of the body2. Then, as shown inFIG. 8D, the grip4ais pushed further downward to bring the arm portion4cinto engagement with the hook2e.FIG. 8Eshows the state where the electronic component1has been completely fixed within the socket body2.

In the above way, the first contacts8aof the electrode members2aare pushed into the recesses51of the body2as shown inFIG. 7C, whereby the obliquely extending second leg portions73of the electrode portions2aare displaced toward the parallel extending first leg portions71. That is, the openings7aof the leaf spring electrode members2aare narrowed, and in turn, the spring force of the second leg portions73toward the electronic component1is increased. When the electronic component1is detached from the body2, the distal ends of the first contacts8awill again extend beyond the upper surface of the body2as shown inFIG. 7B, owing to the spring forces of the obliquely extending second leg portions73. Further, when the body2is detached from the printed circuit board9, the distal ends of the second contacts8bwill extend to again protrude beyond the rear surface of the body2as shown inFIG. 7A.

A second embodiment of the present invention will now be described with reference toFIGS. 9,10and11A–11C. Throughout these figures, the same reference numerals and signs are assigned to features which are the same in FIG.3–FIG. 7Cillustrating the first embodiment.

In the second embodiment, hole surrounding portions53beach have a taper T as shown inFIG. 9and thereby differ from the hole surrounding portions53aof the flat plate member5as shown inFIG. 3. Further, this second embodiment has electrode members2bas shown inFIG. 10instead of the electrode members2aas shown inFIG. 4.

As shown inFIG. 9, an inner edge of the hole surrounding portion53bof the flat plate member5, which opposes the obliquely extending straight leg portion73is beveled to form a taper T which rises up obliquely from the left side toward the right side as viewed in the figure. Besides, the opposing sidewalls54aof each recess51of the flat member5are provided with bearings55bwhich are constructed similar to the first engagement grooves55(refer toFIG. 3). Further, shafts74aand74b, each of which has a diameter somewhat smaller than the width of the bearing55b, are unitary with and extend from opposing sides of the coupling portion72of each leaf spring7forming the electrode member2b, so as to seat within and be rotatably supported by the bearings55b.

According to the second embodiment, therefore, the leaf spring7constituting the electrode member2bis endowed with elasticity over its entire length, so that its spring force is greater than that of the electrode member2ain the first embodiment.

In the second embodiment, as shown inFIG. 11A, the distal ends of the first contacts8aof the electrode members2bdo not protrude beyond the upper surface of the body2, and only the distal ends of the second contacts8bprotrude beyond the rear surface of the body2. In this state, as shown inFIG. 11B, the body2is placed on the printed circuit board9so that the distal ends of the second contacts8bof the electrodes2bmay come into electrical contact with the terminals9aof the printed circuit board9, and the body2is simultaneously pushed against the side of the printed circuit board9. Then, the obliquely extending second leg portions73of the electrode members2brotate, with the bearing portions P3of the shafts74a(74b) as fulcra, up to position P4where these obliquely extending leg portions73abut against the tapered surfaces T of the hole surrounding portions53b. Thus, elasticity is bestowed to each leaf spring7which extends from the abutment position P4to a second electrical contact P2. In turn, the second contact8bside of the parallel extending leg portion71of the electrode2bis lifted so as to have a gap G larger than in the first embodiment. With the bearing portion P3as the fulcrum, a state of electrical contact between the distal end of the second contact8bof the electrode member2band the terminal9aof the printed circuit board9is established and held.

Subsequently, as in the first embodiment, the electronic component1is inserted into the recess2d(refer toFIG. 2) of the body2, and it is pushed toward the printed circuit board side. Then, as shown inFIG. 11C, the terminals1bof the electronic component1and the distal ends of the first contacts8aare brought into electrical contact, and the first contacts8aare pushed into the recesses51of the body2, whereby the obliquely extending leg portions73are bent toward the parallel extending portions71. That is, the opening7aof the leaf spring7is narrowed and, in turn, spring forces toward the side of the electronic component1and the side of the printed circuit board9derive from the whole leaf spring7.

A third embodiment of the present invention will now be described with reference toFIGS. 12,13and14A–14C. Throughout these figures, the same reference numerals and signs are assigned to features which are the same as in FIG.3–FIG. 11C.

Referring toFIG. 12, in the third embodiment hole surrounding portions53beach have a taper T similar to the hole surrounding portions53bof the flat plate member5shown inFIG. 9but have an electrode member2cas shown inFIG. 13instead of the electrode member2ashown inFIG. 4.

In the third embodiment, as shown inFIG. 12, the opposing sidewalls54aof each recess51of the flat plate member5are formed with pairs of engagement grooves (hereinbelow, termed “second engagement grooves”)55ceach of which is longer than the first engagement groove55(refer toFIG. 3), i.e., nearly equal to the depthwise dimension of the recess51). As shown inFIG. 13, on both sides of the coupling portion72of leaf spring7are second engagement sections consisting of first (perpendicular) portions75aand75bwhich are formed unitarily with the coupling portion72and second portions76aand76bwhich are formed unitarily with and at right angle to the first portions75aand75bat the distal ends thereof. Thus, second portions76aand76bextend in parallel with the sidewalls54a.

In the electrode2c, the pair of second portions76aand76bof the engagement elements are respectively seated within the corresponding second engagement grooves55c. According to the third embodiment, therefore, the leaf spring7constituting the electrode member2cderives elasticity over its entire length, and the second engagement pieces76aand76bare subjected to torsional forces, so that the spring force of the electrode member2cagainst an electronic component and a printed circuit board is greater than in the second embodiment.

In the third embodiment, as shown inFIG. 14A, the distal ends of the first contacts8ado not protrude beyond the upper surface of body2, and only the distal ends of the second contacts8bprotrude beyond the rear surface of the body2. As shown inFIG. 14B, the body2is placed on the printed circuit board9so that the distal ends of the second contacts8bcome into electrical contact with the terminals9aof the printed circuit board9, and the body2is simultaneously pushed against the side of the printed circuit board9. Then, the obliquely extending (second) leg portions73rotate, with the portions P5of the second engagement elements76a(76b) as fulcra, up to position P4where these obliquely extending leg portions73abut against the tapered surfaces T of the hole surrounding portions53b. Thus, elasticity of each leaf spring7extends from the abutment P4to a second electrical contact P2. In turn, the parallel extending leg portion71is lifted to form a gap G larger than that of the first embodiment. With the engagement portion P5as the fulcrum, the electrical contact between the distal end of the second contact8band the terminal9aof the printed circuit board9is maintained.

Subsequently, as in the first embodiment, the electronic component1is inserted into the recess2d(refer toFIG. 2) of the socket body2, and it is pushed toward the printed circuit board side. Then, as shown inFIG. 14C, the terminals1bof the electronic component1and the distal ends of the first contacts8aof electrodes2care brought into electrical contact, and the first contacts8aare pushed back into the recesses51of the body2, whereby the obliquely extending leg portions73are displaced toward the parallel extending leg portions71. That is, the opening7aof the leaf spring7is narrowed and, in turn, the spring forces toward the side of the electronic component1and the side of the printed circuit board9derive from the whole leaf spring7.

In each of the foregoing embodiments, the terminals1bof the electronic component1are held in electrical contact with the first contacts8a, and the second contacts8bare held in electrical contact with the terminals9aof the printed circuit board9, but it is also possible to hold the terminals9aof the printed circuit board9in electrical contact with the first contacts8a, and to hold the second contacts8bin electrical contact with the terminals1bof the electronic component1. Moreover, the electronic component1is not restricted to a BGA, but it may also be, for example, an LGA (Land Grid Array), a CSP (Chip Size Package), a PGA (Pin Grid Array) or a micro PGA.

As understood from the above description, according to the present invention, each electrode member has a simple, single-piece construction, so that the workability and assembly of the electrode member is sharply enhanced, and the cost thereof becomes comparatively low. Moreover, the electrical contact between each first contact and the corresponding electrode terminal of the electronic component (or a printed circuit board) is at an oblique angle, so that the leaf spring can be lengthened. In turn, even when the thickness of the body of the connector board is small, each terminal of the electronic component and the corresponding terminal of the printed circuit board can be reliably brought into electrical contact, with a stable pressure.