Electrical connector having latch means

Abstract: An electrical connector (2) for connecting a daughter board (6) to a mother board (4) comprises a dielectric housing (8) having a board receiving opening (20) therein for receiving the daughter board (6) and contacts positioned adjacent the board receiving opening (20) and arranged to make electrical contact with the daughter board when the latter is inserted into the opening in a first position and is rotated relatively to the connector into a second position. Separate resilient latch members (40) at opposite ends of the housing (8) engage the daughter board in its second position to retain the latter in this position. The latch members (40) are secured in recesses (24) of latch receiving portions at opposite ends of the housing by retention means comprising securing arms (60) engaged with the latch receiving portions.

Description: This invention relates to an electrical connector for connecting a first printed circuit board or mother board to a second printed circuit board or daughter board and, more particularly, to such a connector having latch means for retaining the daughter board in its operational position. Many electrical connectors are known which provide electrical connection between contact surfaces of a daughter board and contact areas of a mother board. In one type of such a connector, the connector has contacts positioned therein which extend from a first mating surface of the connector to a second mating surface. The contacts have posts which extend from the connector and make electrical engagement with the contact areas of the mother board. The daughter board is then inserted into the connector and rotated to its operational position. As this rotation occurs, contact projections of the contacts engage the contact surfaces of the daughter board. In order for this electrical engagement to be maintained, it is essential that latch means be provided to cooperate with and maintain the daughter board in the operational position. An example of this type of electrical connector is described in US-A-4,737,120. As shown in Figure 1 of that patent specification, the latch members are provided at the ends of the connector and are integrally molded with the housing. The configuration of the latch members provides the latch members with the resilient characteristics required in order to allow the latch members to cooperate with the daughter board to maintain the daughter board in electrical engagement with the terminals of the connector. However, several problems are associated with the configuration of the latch member described above. As the latch members are molded from plastic material, and as the resilient characteristics of plastic is not significant, the latch members are likely to take a permanent set, particularly when the connector is used over many cycles. This likelihood is increased due to the fact that the latch members must have a relatively thin width when molded. This requirement reduces the durability of the latch members, so that the latch members are only strong enough to support approximately 25 cycles (insertions and removals of the printed circuit board). Consequently, if the electrical connector is to be used over many cycles, the risk of failure of the electrical connector is greatly increased. It is also important to note that a relatively small displacement of the molded latch is enough to cause the latch to take a permanent set. Consequently, as the daughter boards can vary in size and still fall within the tolerance limits for the connector, it is possible that a relatively large board will be inserted into the slots, and then be followed by a relatively small board. The insertion of the large board into the slot can cause the plastic latch to take a permanent set, so that as the small board is inserted, the latch will not be effective in maintaining the board in the slot, resulting in an ineffective connector. It would therefore be advantageous if the latch members could be made from a material having the desired resilient characteristics. This requires the latch members to be separately manufactured and secured to the housing after the housing has been molded. EP-A-0 277 813 describes an electrical connector for connecting a first printed circuit board to a second printed circuit board in which the second or daughter board is linearly inserted into the connector, directly into its operational position. The connector comprises a housing having a board-receiving opening therein disposed between opposite ends of the housing for receiving the second printed circuit board, contacts positioned adjacent the board-receiving opening and configured to make electrical connections with the second printed circuit board when the latter is inserted into the board-receiving opening, and a latch receiving portion positioned outwardly of an adjacent end of the board-receiving opening and mounting a separate resilient latch member. The latch member has retention means securing the latch member to the latch receiving portion and a latch portion for engaging the second board to maintain the latter in position in the opening. US-A-3 803 533 describes an electrical connector in which an insulated connecting block is secured along one edge of a printed circuit board by a clip member having a pair of lugs engaging with the connecting block, a projection adapted to be fastened to the support and a resilient leaf spring member extending from the clip member which retains an electrical plug board in its operational position after connection with the block. The plug board is linearly inserted into the block. The present invention consists in an electrical connector for connecting a first printed circuit board to a second printed circuit board, comprising a first major surface and an oppositely facing second major surface, a board receiving opening for receiving the second printed circuit board extending from the first major surface toward the second major surface and having contacts positioned adjacent the board receiving opening and configured to extend from the board receiving opening to beyond the second major face, and a separate resilient latch member disposed adjacent each end of the board receiving opening and having a resilient arm projecting from a base portion, a latch portion at the free end of the resilient arm for engaging the second board to maintain the latter in position in the opening, and retention means for securing the latch member to the connector, characterised by wall means upstanding from the first major surface of the connector adjacent each end of the board receiving opening and defining a latch receiving recess positioned outwardly of the adjacent end of the opening, the base portion of the associated latch member being seated on a bottom wall of the recess, and the retention means comprising securing arm means extending from the base portion and retaining the latch member in the latch receiving recess, and further characterised in that the contacts are positioned and configured to make said electrical connections with the second board when the latter is rotated, relatively to the connector, from a first position in the board-receiving opening into a second position. An embodiment of the invention will now be described by way of example with reference to the accompanying drawings, in which:- FIGURE 1 is a perspective view of the connector with a separate latch member provided therein, the connector electrically connecting a mother board with a daughter board or card. FIGURE 2 is a perspective view of the connector showing the cooperation of the latch member with the daughter card. FIGURE 3 is a cross-sectional view of an end portion of the connector showing the latch member provided in a latch receiving recess, the motion of the latch member as the daughter card is inserted into the connector is indicated by the lines shown in phantom. FIGURE 4 is a perspective view of the latch member removed from the latch receiving recess of the connector. FIGURE 5 and 6 are perspective views of the latch member removed from the latch receiving recess, these views differ from Figure 4 only in the angle at which the latch member is viewed. FIGURE 7 is a plan view of a sheet metal blank from which the latch member is formed. Referring to Figures 1 and 2, there is illustrated a low insertion force electrical connector 2. The connector electrically and mechanically connects printed circuit board 4 to printed circuit board 6. The connector 2 has an elongated housing 8 having a plurality of contact receiving cavities 10 located in an elongated base 12. The housing is made from any material having the desired dielectric characteristics. The plurality of contact receiving cavities 10, as shown in Figure 2, extend from top surface 14 of base 12 to proximate bottom surface 16 of the base. The cavities are provided in spaced apart parallel relationship to each other and to ends 18 of base 8. The cavities are in communication with a board-receiving opening 20. The exact shape of the cavities 10 varies according to the shape of contacts 22 to be secured therein. Contacts 22 are disposed in cavities 10. Each contact is made from sheet metal stock having the desired conductive and resilient characteristics. A more detailed explanation of a particular type of contact which can be used in the connector is more fully disclosed in US-A-4,737,120. Proximate ends 18 of base 8 are latch receiving recesses 24, as best shown in Figures 1 through 3. Each latch receiving recess 24 is provided proximate the board-receiving opening 20. As is shown in Figures 1 and 2, each latch receiving recess 24 has three side walls 26 which extend from an upper surface 28 of the connector housing toward the bottom surface 16 of the base. As shown in Figures 1 and 2, a recess 32 is provided in one of the side walls 26, the recess extending from the upper surface 28 of the housing toward the top surface 14 of the base 8. The fourth side wall 30 (Figure 3), which is positioned adjacent the board-receiving opening 20, does not extend to the upper surface 28 of the housing. Post receiving openings 34 extend from the bottom surface 16 of base 8 to the bottom walls 36 of recesses 24. As is shown in Figure 3, post receiving openings 34 have lead-in surfaces 38 provided proximate the bottom walls 36 of the recesses 24. Latch members 40 are positioned in the latch receiving recesses 24. As is shown in Figure 7, each latch member is stamped from sheet metal stock having the desired resilient and electrical characteristics. The latch members are then formed into the configuration shown in Figures 4 through 6. For ease of explanation and understanding, only one latch member 40 will be described in detail. However, it is important to note that in most applications, more than one latch member will be used in a connector. As shown in Figure 5, each latch member 40 has a resilient section 42 and a mounting section 44. The resilient section 42 has a base portion 46 which has two ends provided thereon. Extending from a first end of the base portion 46 is resilient arm 48. The resilient arm has an angled portion 50 which extends at an angle from the free end of the base portion 46. An intermediate portion 52 extends from an end of the angled portion 50 in a direction which is essentially perpendicular to the base portion 46. A latch projection 54 is provided at the upper surface of the intermediate portion 52. The latch projection 54 extends from the intermediate portion 52, in a direction which is essentially perpendicular to the intermediation portion. A board edge receiving opening 56 is provided in the latch projection 54 to allow the daughter board to be inserted therein, as will be more fully described. An engagement projection 58 extends from a side edge of the intermediation portion 52 and from an edge surface of the latch projection 54. As shown in Figures 1 and 2, the engagement projection 58 extends beyond the housing of the connector, thereby allowing a technician to engage the engagement projection 58. The general configuration of the resilient arm 48 of the latch member 40 provides the resilient characteristics required to insure for the proper and continued use of the latch member over many cycles. However, other configurations of the resilient arms are possible. In fact, it is conceivable that due to space considerations, each latch member provided in the connector may have a slightly different appearance. The operation of the each latch member, no matter the configuration, is essentially identical to the operation of the latch member described herein. A securing arm 60 is provided at a second end of base portion 46. As best shown in Figure 3, securing arm 60 extends from the base portion 46 towards the upper surface 28 of the connector housing, in essentially the same direction as the angled portion 50 of resilient arm 48. A free end 62 of securing arm 60 cooperates with a shoulder 64 provided on one of the side walls 26 of the latch receiving recess 24. It should be noted that the configuration of the securing arm and the shoulder of the side wall allows the latch member 40 to be inserted into the latch member receiving recess 24 through the upper surface 28 of the connector housing. As insertion occurs, securing arm 60 will be caused to move to the right as viewed in Figure 3, thereby placing the securing arm in a stressed position. Once the latch member 40 is fully inserted into the recess 24, the free end 62 of the securing arm 60 will be resiliently displaced into the shoulder 64 of the side wall, thereby preventing the removal of the latch member 40 from the latch receiving recess 24. The configuration of the securing arm 60 and the base portion 46 enhance the resilient characteristics of resilient arm 48. Referring back to Figure 5, mounting section 44 extends from the second end of base portion 46, in a direction toward the bottom surface 16 of the base of the connector. It should be noted that the width of the securing arm 60 plus the width of the mounting section 44 is equal to the width of the base portion 46, as best shown in Figure 7. Mounting section 44 extends beyond the bottom surface 16 of the base 12 to cooperate with a printed circuit board (mother board) 4. A board engagement portion 68 is provided on the mounting section 44 to insure that the latch member will be provided in engagement with an opening 70 provided in the printed circuit board 4. The width of portion 68 is slightly larger than the width of a corresponding opening 70 in the printed circuit board. Consequently, as the portion 68 is inserted into the opening 70, the portion 68 is allowed to deform due to the presence of slot 74. This deformation allows the board engagement portion 68 to be inserted into the opening 70. This type of deformation causes portion 68 to exert a force on the walls of the opening when the portion 68 is properly inserted therein, thereby insuring that the portion 68 will be maintained in the opening 70. With the connector secured to printed circuit board 4, a daughter card 6 is positioned in the board-receiving opening 20 at an angle. The daughter card 6 must then be rotated to the position shown in Figures 1 and 2. As this rotation occurs, the daughter card 6 engages the latching projection 54. This causes the resilient arm 48 to be moved toward the end 18 of the connector, as indicated by the lines drawn in phantom in Figure 3. The resilient deformation of the resilient arm allows the daughter card 6 to continue its turning motion. When the card is essentially perpendicular to printed circuit board 4, the daughter card 6 enters the board edge receiving opening 56, thereby disengaging the projections, allowing the resilient arm to snap back in place. The daughter card is now secured in position between the latching projection 54 and stop member 78 provided on the housing. To remove the daughter card 6 from the connector, the technician engages the engagement projection 58 and moves the projection toward end 18. This causes the resilient arm 48 to be moved to the position indicated by the lines drawn in phantom in Figure 3, thereby allowing the daughter card 6 to be rotated in the opposite direction of that previously described. Several advantages are provided by the type of latch member 40 described herein. Due to the fact that the latch member 40 is insertable into the housing, and therefore is not molded from the same plastic material as the housing, the latch member 40 is usable over many more cycles. The material from which the latch member 40 is manufactured can be chosen to maximize the resilient and strength characteristics of the resilient arm 48. Consequently, as daughter boards are inserted and removed, each resilient arm 48 will not take a permanent set, and will therefore be usable over a great number of cycles. Also, because of the enhanced characteristics of the latch member 40, the resilient arm 48 is capable of accommodating a wider range of card widths. This is an important advantage, as the tolerance limits associated with the daughter cards 6 can be significant. In the prior art, when a relatively wide card was inserted into the connector, it would cause the plastic latches to take a permanent set. Consequently, when a relatively small card was inserted, the latches could not retain the card in position. With the present invention this result is eliminated, as the latch members 40 will not take a permanent set due to the varied dimensions of the cards. In the prior art, if the latch is damaged, the entire connector must be replaced. This can be a costly proposition, as all the contacts, etc. in the connectors are discarded. However, in the present embodiment, if the latch members are damaged, only the latch member 40 need be replaced. Consequently, the remaining portion of the connector is salvaged. Another advantage of this latch member 40 relates to the strength characteristics of the mounting section 44. In prior art connectors, in which the mounting posts are molded from the same material as the housing, the posts are inherently weak. Consequently, the failure of the post during shipping or insertion resulted in a major problem, as the failure of the post caused the entire connector being ineffective. However, in the present invention, the mounting section 44 is made from a material having significant strength characteristics. Therefore, damage to the mounting section during shipping and insertion is essentially eliminated, resulting in a much more reliable connector. One of the most significant advantages of the latch member 40 described herein is directed to the electrical characteristics which are provided. In this age of miniaturization, when board real estate is at a premium, it is essential that connectors occupy minimal space. It is therefore important that the contact terminals provided in the connector be as few as possible. In an attempt to achieve this result, it is extremely beneficial to provide contact terminals which only transmit communication signals thereacross. In other words, the power and ground transmissions are provided by other means. In the present invention, due to the electrical characteristics of the latch members 40, the power and ground can be supplied from the printed circuit board 4 to the daughter card 6 through the latch members. The power is supplied from board 4 by way of opening 70. Board engagement section 68 is provided in electrical engagement with the opening, such that the power signals are transmitted from board 4 to latch member 40, which is comprised of electrically conductive material. The power signals are supplied to the daughter card 6 by means of the electrical connection provided between the latch projections 54 and conductive areas 80 of the daughter card 6, as shown in Figures 1 and 2. It should be noted that in order to provide for the electrical engagement required between the daughter card and the latch member, the board edge receiving recess with which the daughter card cooperates must be precisely dimensioned.

Claims: An electrical connector (2) for connecting a first printed circuit board (4) to a second printed circuit board (6), comprising a first major surface (14) and an oppositely facing second major surface (16), a board receiving opening (20) for receiving the second printed circuit board extending from the first major surface toward the second major surface and having contacts (22) positioned adjacent the board receiving opening and configured to extend from the board receiving opening to beyond the second major face (16), and a separate resilient latch member disposed adjacent each end of the board receiving opening and having a resilient arm (48) projecting from a base portion (46), a latch portion (54) at the free end of the resilient arm for engaging the second board (6) to maintain the latter in position in the opening (20), and retention means (44,60) for securing the latch member to the connector, characterised by wall means (26) upstanding from the first major surface (14) of the connector adjacent each end of the board receiving opening (20) and defining a latch receiving recess (24) positioned outwardly of the adjacent end of the opening, the base portion (46) of the associated latch member being seated on a bottom wall (36) of the recess, and the retention means comprising securing arm means (60) extending from the base portion and retaining the latch member in the latch receiving recess, and further characterised in that the contacts (22) are positioned and configured to make said electrical connections with the second board (6) when the latter is rotated, relatively to the connector, from a first position in the board-receiving opening (20) into a second position. An electrical connector as claimed in claim 1, wherein the latch portion (54) has means (58) providing a lead-in for movement of the second board (6) from the first to the second position and facilitating manual movement of the latch portion by a technician for release of the board and rotation in the opposite direction. An electrical connector as claimed in claim 2, wherein the resilient arm has engaging projections (54,56,58) provided at the free end thereof and forming the latch portion, said engaging projections cooperating with the second board (6) when the second board is in the second position to maintain the latter in said second position. An electrical connector as claimed in any preceding claim, wherein the latch member (40) is a resilient metal member.

Inventors: KOPP MONTE LYNN, KORSUNSKY IOSIF, SCHROEPFER RICHARD CLAIR, KOPP, MONTE LYNN, KORSUNSKY, IOSIF, SCHROEPFER, RICHARD CLAIR
Applicants: WHITAKER CORP, THE WHITAKER CORPORATION
Application year: 1990
Main classification: H01R12
IPC codes: H01R12, H01R13, H05K1