A LOW INSERTION FORCE ELECTRICAL SOCKET ASSEMBLY

Abstract: A low insertion force socket assembly includes, a base 2, cavities 24, electrical receptacles 4 in the cavities, rails 6, 8 which engage and close the receptacles onto electrical leads 46 of an electronic package 48 and a cover 10 integral with a reciprocating cam 12 and latches 42 and a detent finger 44, and pilot holes 36A, 36B, 36C for aligning the parts during assembly.

Description: A LOW INSERTION FORCE ELECTRICAL SOCKET ASSEMBLY A low insertion force electrical socket assembly is disclosed for electrical terminals, called leads, projecting from an electronic package. By way of example, an electronic package comprises miniature electrical circuit components interconnected by a metal lead frame. The lead frame has projecting multiple terminals, called leads. The circuit components and parts of the lead frame are imbedded in encapsulant to form an electrical package. The leads project from the encapsulant and provide connections for electrical inputs and outputs to the circuit components in the electrical package. A socket assembly for an electronic package allows pluggable connection of the leads of the package with circuits of a printed circuit board. A typical socket assembly includes an insulation base carrying electrical receptacle contacts that are connected with respective circuits of a printed circuit board. The leads of the electronic package are pluggably inserted into the receptacle contacts and are readily withdrawn to remove the electronic package from the socket assembly. The receptacle contacts often are damaged when the leads of the package are inserted, especially if the leads are misaligned slightly with the receptacle contacts, and the misaligned leads are forced into the receptacle contacts. There is known in U.S.A. 3,763,459 a low insertion force socket assembly into which misaligned leads are inserted without damaging the receptacle contacts of the socket. This advantage is achieved by having the receptacle contacts open during insertion of the misaligned leads. A reciprocating shutter mechanism is operated to close the receptacle contacts onto the leads and establish electrical connections therewith. The shutter mechanism also allows opening of the receptacle contacts to permit withdrawal of the leads. In this known socket the receptacle contacts must be received into respective apertures of the shutter mechanism. Assembly of the shutter mechanism apertures with the receptacle contacts is difficult especially if the socket is of miniature size. Another problem to overcome is the need for reducing the number and complexity of component parts required in the assembly. The present invention is a low insertion force socket assembly having parts few in number and of minimum complexity, and comprises a base, contact receiving cavities in the base along sides of the base, an electrical contact in each of the cavities, each of the contacts having a pair of opposed fingers spaced apart for receiving therebetween an electrical lead, and the fingers of each of the contacts engage opposite sides of a respective lead upon resilient deflection of one resilient finger of each contact toward the other finger of the contact, characterized in that; a pair of elongated rails are mounted on the base alongside the resilient fingers of respective contacts, each rail has an elongated sinuous follower surface, a cover overlies the rails, a cam on the cover is interposed between the rails, the cam has sinuous edges facing the sinuous follower surfaces of the rails, and upon reciprocation of the cam together with the cover, the sinuous edges of the cam slidably traverse against the sinuous follower surfaces of the rails, and the rails are urged to move toward and engage and resiliently reflect the resilient fingers of the contacts toward the opposed fingers, The present invention Is further characterized In that, the base includes an elongated slot, the cover Includes a resilient, projecting, internal finger in detented engagement with each of the detents, alternately in turn, upon reciprocation of the cam together with the cover, The present invention is further characterized in that, the base includes an elongated slot, the cover includes a projecting latch hooked in the slot of the base, and the latch slidably reciprocates in the slot upon reciprocation of the cam together with the cover. The present invention is further characterized in that, the cover and the cam are of one piece molded dielectric construction, the latch and the finger are cantilever beams joined integrally with the cover. The present invention is further characterized in that the base and the rails and the cover have pilot holes therein which align with one another as an indicator of correct assembly of the base, the rails, and the cover. A better understanding of the present invention will be apparent by way of example from the following detailed description taken in conjunction with the drawings. Figure 1 is an enlarged perspective view of a socket assembly with the parts exploded for the purposes of illustration; Figure 2 is a plan view of the assembly with the parts assembled and a cover and a cam partially broken away and in section for the purpose of illustrating the cam in a first, detented position, and the receptacle contacts are shown as being open; Figure 3 is a side elevation of the assembly as shown in Figure 2, and with the assembly shown in section taken along the line 3-3 of Figure 2; Figure 4 is an enlarged plan view similar to Figure 2 and illustrating the cam in a second detented position, and the receptacle contacts closed; Figure 5 is a view similar to Figure 3 with the assembly shown in section taken along the line 5-5 of Figure 4; Figure 6 is an enlarged elevation view of the assembly shown in section taken along the line 6-6 of Figure 3; and Figure 7 is a view similar to Figure 6 with the assembly shown in section taken along the line 7-7 of Figure 5. By way of example, Figure 1 shows a socket assembly I, comprising a base 2, electrical receptacle contacts 4, a pair of rails 6, 8, and a cover 10 having a cam 12. The base 2 is of one piece molded plastic construction having a flat central table 14 encircled by projecting side walls 16, 18, and end walls 20,22. Alongside the sidewall 16 is a row of open cavities 24 recessed into the base 2 and separated by partitions 26. The cavities project, at 28, past end walls 36 of the partitions 26 and part ally into the table 14. Alongside the sidewall 18 is another row of oper cavities 24 similar in all respects to the cavities 24 which are alongside the sidewall 16. Additional partitions 26 on the sidewall 18 sep¯-ate the cavities 24. Each contact 4 is stamped and formed in one piece from a blank of resi ent, conductive metal, and comprises a first finger 4A and a second, resi' ent finger 4B which is doubled back on itself and projects toward the ringer 4A. A projecting post type terminal 4C is partially severed out from the finger 4B and remains attached at one end to the finger 4B. The fingers 4A, 4B of each contact are opposed and are spaced apart frorr each other, and define an open electrical receptacle. As shown in Figures 1, 2, 6 each contact 4 is mounted in a respective cavity 24. A finger 4A lies against a respective sidewall 16 or 18. Since the wall 16 or 18 is tapered, the finger 4A is flared and defines a funnel entry into the electrical receptacle defined by the opposed fingers 4A and 4B. The resilient finger 4B of each contact 4 projects into the portion 28 of a respective cavity. Each finger 48 extends past the end walls 30 of the partitions 26 and projects partially into the table 14. The terminal 4C: of each contact projects through a respective slot 32 in the bottom of each cavity 24 through the base 2. With reference to Figure 1, the rails 6, 9 are of elongated, molded plastic construction, each having a sinuous cam follower surface 34 and a pair of spaced apart pilot holes 36A. Figures 2 and 6 show the rails 6, 8 mounted on the table 14 alongside respective resilient fingers 4B of the contacts 4. Figure 1 shows the table 4 of the base 2 having pilot holes 36B. The pilot holes 36B may have removable alignment pins 36 which align with the pilot holes 36A of the rails 6, 8 during assembly with the base 2, With reference to Figure 1, the cover 10 and cam 12 are of unitary, one piece, molded plastic construction. The cover includes end walls 38 which project out from a plate portion 40 in which are provided pilot holes 36C, The cam 12 projects out from the plate portion 40 and is provided with sinuous edges 12A on opposite elongated sides of the cam 12. The cover 10 also includes resilient L-shaped latches 42 and a resilient, L-shaped detent finger 44 projecting through and beyond the cam 12. The table 14 has a pair of slots 42A communicating with recesses 42B under the table 14, and a pair of recessed detents 44A to receive the detent finger 44. Figures 2 and 6 show the assembly of the cover 10 and cam 12 on the base 2. The pilot holes 36C of the cover are aligned with the alignment pins 36, and the cover is urged toward the table 14 until the L-shaped latches 42 pass through the slots 42A and hook in recesses 42B under the table 14. The cam 12 is then interposed between the rails 6, 8 with the edges 12A facing and nesting with the follower surfaces 34. Figure 3 shows the detent finger 44 in detented registration with a first detent 44A. Following assembly, the pilot pins 36 are removed, since they are not needed. The assembly 1 as shown in Figures 2, 3, and 6 provides a low insertion force socket for electrical terminals in the form of leads 46 of a known electronic package 48. The leads 46 are readily inserted, without undue force, into the open receptacles defined by the opposed fingers LIA, 4B of the contacts 4. Figures 4, 5, and 7 show the cam 12 together with the cover 10 reciprocated to a second position, with the detent finger 44 transferred from detented registration in a first 44A to a second detent 44A. As the cam is reciprocated the latches 42 slide in and along the slots 42A. In addition, the sinuous edges 12A of the cam 12 slidably traverse against the sinuous follower surfaces 34 of the rails 6, 8, and the rails engage and deflect the resilient fingers 4B of the contacts 4 toward the opposed fingers 4A. Thereby the fingers 4A, 4B engage opposite sides of respective leads 46 to establish electrical connections therewith. Resilient spring energy becomes stored by the resilient fingers 4B during deflection thereof. The cam 12 together with the cover 10 is reciprocated to the first position shown in Figures 2, 3, and 6, allowing the receptacles to open by return resilient deflection of the fingers 4B, due to the stored energy. The stored energy is sufficient to cause the fingers 4B to push against the rails, and return the rails 6, 8 to their positions shown in Figures 2, 3, and 6. The spirit and scope of the appended claims is intended to cover all forms of the invention disclosed herein by way of example only.

Claims: CLAIMS: 1. A low insertion force socket assembly having a base, contact receiving cavities in the base along sides of the base, an electrical contact in each of the cavities, each of the contacts having a pair of opposed fingers spaced apart for receiving therebetween an electrical terminal, and the fingers of each of the contacts engage opposite sides of a respective terminal upon resilient deflection of one resilient finger of each contact toward the other finger of the contact, characterized in that; ; A pair of elongated rails are mounted on the base alongside the resilient fingers of respective contacts, each rail has an elongated sinuous follower surface, a cover overlies the rails, a cam on the cover is interposed between the rails, the cam has sinuous edges facing the sinuous follower surfaces of the rails, and upon reciprocation of the cam together with the cover the sinuous edges of the cam slidably traverse against the sinuous follower surfaces of the rails, and the rails move toward and engage and resiliently deflect the resilient fingers of the contacts toward the opposed fingers. 2. The socket according to Claim 1, further characterized in that, the base includes an elongated slot, the cover includes a projecting latch hooked in the slot of the base, and the latch slidably reciprocates in the slot upon reciprocation of the cam together with the cover. 3. The socket according to Claims 1 and 2, further characterized in that, the base includes a pair of spaced apart detents facing toward the cover, and the cover includes a resilient projecting finger in detented engagement with each of the detents, alternately in turn, upon reciprocation of the cam together with the cover. 4. The socket according to Claims 1 and 3, further characterized in that, the cover and the cam are of one piece molded dielectric construction, the latch and the finger are cantilever beams joined lnwgrally with the cover. 5. The socket according to Claims 1, 2, and 3 further characterized in that, the base and the rails and the cover have pilot holes therein which align with one another as an indicator of correct assembly of the base, the rails, and the cover.

Inventors: MACDOUGALL, ALAN ROBERT
Applicants: AMP INCORPORATED
Application year: 1982
Main classification: H01R23
IPC codes: H05K7, H01R12