JPH0388290A - Electric contact - Google Patents

Abstract

PURPOSE: To keep a spring within an elastic limit and ensure sufficient contact pressure by forming a pivot region in the joint part of a contact part and a base part, forming at least one additional pivot region for absorbing the turning motion of the pivot region in an elastic part, and interconnecting two conductors between a terminal part and a contact surface. CONSTITUTION: A pivot region 128 is formed in the joint part of a contact part 114 and a base part 112, at least one additional pivot region 104 for absorbing the turning motion of the pivot region 128 is formed in an elastic part, and two conductors are connected each other between a terminal part 126 and a contact surface 130. Even if the first contact part 114 is moved relatively largely, variation in distance between two pivot regions 128, 104 is very small. Even if the contact part is largely varied caused by the large dimension tolerance of an IC chip, sufficient contact pressure can be ensured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention is used for electrical contacts, particularly sockets for tC chips, etc., for interconnection between a plurality of conductor parts of an IC chip and corresponding conductor parts of a circuit board. Concerning suitable electrical contacts.

[Prior art and its problems]

A conventional example of a connector (or socket) assembly used with an IC (semiconductor integrated circuit) chip is US Pat. No. 4.
513.353, 4.645.279, 4.684.184, etc. When designing such an assembly, different requirements must be met for the contact elements that form the conductive path between the IC chip and the circuit board on which the assembly is mounted.

One of the requirements is contact (grinding) with the chip carrier.
The contact portion of the chip package is capable of withstanding relatively large deformations to accommodate manufacturing dimensional variations or tolerances between chip packages.

At present, it is not unusual that the maximum and minimum dimensions of chip carriers from different manufacturers vary by as much as about 0.8 am. At the same time, the contact pressure over this range must not vary significantly. Therefore, a relatively flat Kerr deformation curve is preferred. for example,
If the electrical contacts are tin-plated, the contact pressure is approximately 220 g at minimum deformation of the contact and approximately 400 g at maximum deformation. This places additional requirements on the springs that create the contact pressure. Moreover, the space in which this compliant spring is designed must be small for various reasons. The first reason is that the material is expensive and the size immediately increases the cost. The second reason is that the conductive paths need to be short to minimize the self-inductance of the contacts.

A known effect of counteracting these requirements is that significant deformation of metals involves permanent or plastic deformation of the metal itself. However, for example, when a straight beam is deformed by a predetermined amount and remains within the elastic limit (i.e., the amount of deformation at which each part completely returns to its initial position when the deforming force is removed), the beam is relatively long and therefore may not satisfy the above-mentioned conductive path length and space requirements. The conventional electrical contacts described above do not completely satisfy these requirements and have unresolved problems.

[Purpose of the invention]

Therefore, the main object of the invention is to enable a relatively short beam whose deformation beyond its elastic limit is transformed into a smaller deformation elsewhere where it acts as a spring, thus allowing the spring to remain within its elastic limit. The purpose of the present invention is to provide electrical contacts of the type.

Another object of the invention is to provide an electrical contact that is a monolithic element.

[Means for solving problems]

According to the electrical contact of the present invention, a base, a terminal portion extending from the base, a contact portion extending in a cantilever shape from the base and having a contact surface movable to a position away from the base, together with the contact portion and the base, approximately an elastic part formed in a loop shape, forming a pivot area at the joint between the contact part and the base part, and the elastic part has at least one additional pivot area for absorbing the pivoting movement of the pivot area. The two conductors are interconnected between the terminal portion and the contact surface. Such an electrical contact is integrally formed into a substantially flat plate shape by punching an elastic metal plate and performing the necessary work steps.

〔Example〕

Embodiments of the electrical contact of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view of a connector assembly in which the electrical contacts of the present invention can be used. The connector assembly IO is attached to a circuit board 12 and can use a number of electrical contacts according to the present invention. The connector assembly 10 is used for burn-in testing of IC chips, and generally includes a main body 14,
It includes a hinge cover member 16 and a latch member 18 that releasably secures the cover member 16 to the body portion 14 in the closed position. Body portion 14 has a plurality of cavities 20 formed therein which hold electrical contacts indicated by reference numeral 22 . cavity 2
0 are arranged along the outer periphery of the central pocket 24, and the central pocket 24 is sized to insert an IC chip package 26 therein. A spring member 28 is disposed within the bottom of the pocket 24 and is used to spring the package 26 so that the package 26 is partially pushed out when the cover member 16 is opened.

A lead is formed along the outer periphery of the package 26, as indicated by reference number 3o. These leads 30 are empty#
20 and is configured to contact one of the corresponding electrical contacts 22 disposed within 20 . As shown in FIG. 1, each electrical contact 22 has a base 32 formed with downward contact legs 34 that are inserted into openings (through-holes) of a predetermined size and at predetermined intervals in the circuit board 12, as in the prior art.
has. A contact arm 36 is formed upwardly from the base 32 and when the package 26 is inserted into the pocket 24,
It is brought into surface contact with the leads 3o of the package 26.

One requirement for contacts 22 is that contact arms 36 apply sufficient contact pressure to leads 30. If all the components are perfectly manufactured and the dimensions of the package 26 are consistent, this contact pressure would be caused by the elasticity of the contact arm 36 cantilevered on the base 32. However, in reality, the package 26 has manufacturing tolerances and slight variations from manufacturer to manufacturer. Therefore, this contact arm 36 must be able to absorb these tolerances, and there is a variation of about 0.8 mm between the large and small ends of the bag 26, and even in that case, sufficient contact pressure cannot be applied. Must not be.

If the contact arm 36 is formed into a simple beam shape as shown in FIG. 1, if the package 26 has large dimensions and undergoes large deformation, the contact arm 36 will deform beyond its elastic limit, and the small package 26 will be in the pocket. 24, the contact arm 36 may lack spring repulsion and may not be able to provide the necessary contact pressure. Contact arm 36 can be made long if there is no size limit. but,
As mentioned above, the dimensions are also limited. Therefore, contact 2
2 is small in size and can absorb relatively large deformations as mentioned above;
Moreover, it possesses effective elasticity so that the required contact pressure can be generated for all package dimensions.

FIG. 2 is a mechanical model diagram of an electrical contact according to a first embodiment of the present invention, in which the spring is brought within its elastic limit by converting a large deformation in a short beam into an extremely small deformation in another part that acts as a spring. It is something that stays. The model has a base 38 and a first end 42 and a second end 44.
A beam 40 is included. First end 4 of first beam 4o
2 is pivotably attached to the base 38. A second beam 46 is attached to the first end 48 and is pivotable at the second end 44 of the first beam 40 and extends toward the base 38 . A first end 52 of a third beam 54 is rotatably attached to the second end 5o of the second beam 46. First spring 56
connects the first end 42 of the first beam 40 to the second end of the second beam 46.
A second spring 58 is coupled to the end 50 of the third beam 54 .
a support 62 having an end 60 secured to the base 38;
to be elastically bonded to.

If a force is applied to the first beam 40 as indicated by arrow 64, this force is equivalent to the force applied to the contact arm 36 by the package lead 30 of FIG.
Beam 40 pivots clockwise about its first end 42 to the position shown in phantom in the figure. This causes the pivot point of the second end 50 of the second beam 46 to also be the same as that of the first end 50 of the first beam 40.
Pivoting around end 42 will result in a small downward vertical displacement. This displacement corresponds to the second end 4 of the first beam 40.
This is only a small part of the horizontal displacement of 4.

The movement from the equilibrium state shown in solid lines to the position shown in broken lines in FIG. 2 is effected by springs 56,58.

In fact, the springs 56, 58 are in the area 65 where the force 64 is applied.
is elastically coupled to the base 38 to create the required contact pressure. When the force 64 indicated by arrow 64 is removed, the mechanism shown in FIG. 2 returns from the displaced position shown in dashed lines to the equilibrium position shown in solid lines.

Studying the mechanism shown in Figure 2, the first beam 40
It can be seen that a relatively large deformation of causes a small deformation at the first end 52 of the third beam 54 and a small deformation along the third beam 54.

This is effected by a conventional spring 58, which may have a very steep Kerr deformation curve, but whose resultant spring ratio returning the first beam 40 to its equilibrium position is relatively flat.

As previously mentioned, the dimensions of cavity 20 are limited.

In some cases, this cavity 20 is approximately 3.8 am x 5.6
mm, and must accommodate contacts with a thickness of approximately 0.25 mm. Although the mechanism shown in Figure 2 cannot be created with currently available technology under these dimensional constraints, the principles of the present invention allow for the creation of a direct model of the mechanism shown in Figure 2 in monolithic metal. be able to. A first form of such electrical contact is shown at 66 in FIG. This electrical contact 66 is formed as a monolithic element from a metal plate. It forms a conductive path between the first contact portion 68 and the second contact portion 70 and applies contact pressure to the first contact portion 68 in the left direction in FIG. Contact element 66 , an electrical contact, includes a base 72 from which a second contact portion 70 extends and a first beam 74 cantilevered from base 72 .

The first contact portion 68 is formed as part of the first beam 74 . A second beam 76 extends from the distal end of the first beam 74 toward the base 72 . As part of the base 72, an L-shaped sabot element 78 extends upwardly from the base 72;
A third beam 80 is joined to its end. This third beam 80 extends toward the base 72 and has a second
It is joined to beam 76. 1) second and third beams of base 72 and electrical contacts 66? 4,76.80 refers to the base 38, first beam 40, and second beam of the dynamic model in Figure 2.
They correspond to the beam 46 and the third beam 54, respectively. Furthermore,
All pivoting movements of the mechanical model are realized by the elasticity of the metal plates forming the electrical contacts 66. Therefore, the first
There is some relative pivoting movement at the junction of beam 74 and base 72.

FIG. 4 shows a second form of the electrical contact of the present invention according to the mechanical model of FIG. 2, and is designated generally by the reference numeral 84. Both first and second forms of electrical contact 6
6 and 84 is that the third beam 86 of the latter electrical contact 84 is serpentine rather than straight like the former electrical contact 66. This makes it possible to provide the second form of electrical contact 84 with greater elasticity and to adjust the contact pressure more freely.

It may be necessary to further improve the flexibility of the contact. As shown in FIG. 4, the primary plastic deformation due to overstress occurs in region 88, which is the joint between third beam 86 and second beam 90. Furthermore, the first
Area 9 where beam 94 is cantilevered at base 96
In No. 2, plastic deformation hardly occurs.

According to the principles of the invention, the plastic deformation in region 92
This is advantageously utilized in the preferred embodiment of the electrical contact designated by the reference numeral 98 shown in the figures. As shown in FIG. 5, the second beam 100 and the third beam 102 are separated. The serpentine beam 102 has a pocket 104 formed by the serpentine end 106, and the free end 108 of the second beam 100 is contained within the pocket 104. This configuration allows pivoting movement between both beams 100 and 102. If the electrical contact 98 were stamped from a metal plate in the shape shown in FIG. . As will be apparent from the following description, some preliminary work on the electrical contacts 98 will fully satisfy all requirements.

6A, 6B, 6C, and 6D illustrate the process of obtaining the final shape of electrical contact 98 shown in FIG. The first step is to form a monolithic flat blank from a metal sheet.

This blank 1)0 is shown in FIG. 6A, with the base 1)2,
It includes a first beam 1)4 extending away therefrom and a second beam 1)6 extending from the distal end 1)8 of the first beam 14 towards the base 1)2. L-shaped support 1
20 extends away from the base 1) 2 and its distal end 1
22 extends in a meandering manner to the base 1)2.

A plurality of contact legs 126 extend from the base 1) 2 to the beam 1)
4.1) 6 and L-shaped support 120 and protrudes to the opposite side. In the final form, only one of the contact legs 126 remains, but it is a common multi-leg blank so that the contact legs can be arranged in a staggered manner during final assembly of the 1rIIJ connector assembly.

The next step is shown in Figure 6B. In this process, the first beam 1
) 4 in a counterclockwise direction in region 128 beyond its elastic limit. The stress of this first beam 1)4 is the contact 1)
0 into the cavity 20 of FIG.
This is in the opposite direction to the stress experienced by Further, a force indicated by an arrow 129 is applied to the third beam 124 .

This force 129 deforms the beam 124 beyond its elastic limit. As with the stress on beam 1) 4, the stress due to force 129 on beam 124 is in the opposite direction to the stress experienced by this beam 124 by package 26.

The next step is to bend the first beam 1) 4 as far as possible clockwise, as shown in FIG. 6C. This allows the first
The end 1) 8 of the beam 1) 4 abuts an integral overstress stop 132 at the end of the L-shaped support 120. However, before reaching this limit, the second beam 1)
The free end 108 of 6 enters the pocket 104 at the end of the third beam 124, thereby causing the third beam 124 to bend in a counterclockwise direction. Both beams 1) 4, 124 are then further deformed in the bending step shown in FIG. 6B beyond the changed elastic limits previously determined by the bending. Therefore, the deformation region of beam 1) 4.124 becomes stiff.

The final step is to release the forces on both beams 1) 4, 1) 6 and move them and beam 124 to the equilibrium position shown in FIG. 6D. In this position, the resiliency of the serpentine beam 124 holds the free end 108 of the beam l16 within the pocket 104. By joining both beams 1)4, 1)6 in region 1)8 it is possible to strengthen the elasticity.

The key point in forming the electrical contact according to this particular embodiment of the invention is the curing operation of both beams 1)4.1)6. Although it has been shown and described that the beams are hardened by deforming them beyond their elastic limits, it will be appreciated that other hardening methods may be employed, such as shot peening.

Approximately 1O% of the amount of deformation of the recontact portion 130 due to this hardening.
was found to be able to withstand an increase in Furthermore, it has been found that by separating the second and third beams and freeing the pivot point (compare FIGS. 5 and 4), the allowable contact deformation is increased.

Next, another embodiment of the electrical contact of the present invention will be described with reference to FIGS. 7 to 13. Figure 7 is a mechanical model diagram. The model includes a base 38' and a first beam 40° having a first end 42° and a second end 44°.

A first end 42° of the first beam 40° is pivotally fixed to the base 38°.

The second beam 1) has a 46° first end 48' which is pivotally fixed to the second end 44' of the first beam 40' by a pivot of 49° and extends outwardly. Second end 45 of second beam 46°
0° is pivotally fixed to the first end 52' of the third beam 54'. Further, the second end 58° of the third beam 54° is pivotally attached to the base 38° at a pivot 59°. A spring 56° resiliently couples the second end 44° of the first beam 40° to the second end 58° of the third beam 54°.

If beam 40° is subjected to a force indicated by arrow 64° (this force is equivalent to the force exerted on contact arm 36 by package terminal 30 in FIG. 1), beam 40' will Rotate clockwise around the dashed line 60°
The position is not shown. This is the second end 5 of the third beam 54.
Rotate the 8° pivot point 59° clockwise until the end 4
The distance between the pivot points 49', 59' at 4° and 58°, respectively, is made to be a fraction of the horizontal displacement of the second end 44° of the first beam 40°. Movement from the equilibrium position shown in solid lines to the position shown in broken lines in FIG. 7 is effected by spring 56'. In fact, the spring 56'' elastically couples the region 65°, where the force 64' is applied, to the base 38°, creating the desired contact pressure. Upon releasing the force, indicated by the arrow 64°,
The mechanism shown in FIG. 7 returns from the displaced position indicated by the dashed line 60 DEG to the equilibrium position indicated by the solid line.

Considering the mechanism in Figure 7, it can be seen that a relatively large deformation of the first beam 40° causes a small change in the distance between the pivot points of the ends 44° and 58°, acting on the spring 56°. Good morning. Although the spring 56'' may have a very steep Kerr deformation curve, the resultant spring ratio that returns the beam 40° to its equilibrium position is relatively flat.

A first form of electrical contact based on the mechanical model shown in FIG. 7 is shown at 66 in FIG. The electrical contact 66' is stamped from a metal plate. This provides a conductive path between the first contact portion 68° and the second contact portion 70′ and applies contact pressure to the first contact portion 68° in the left direction in FIG. Contact element 66° is base 72°
, from which a second contact portion 70' extends.

Cantilever member 74° has a first end 76′ and a second end 78′, with first end 76° extending cantilevered from base 72°. The first contact portion 68° is formed as part of the cantilever member 74′ near the second end 78′. A first pivot region 79° is provided in the region where the end 76° extends from the base 72". This pivot region allows a first elastic movement and then deforms within the pivot region 79" to form a cantilevered beam. The member 74° undergoes pivoting movement. A spring member 80°, generally C-shaped or any other shape, pivots the second end 78° of the cantilever member 74° by means of a second pivot region 84''.
and a second end 88' pivotally associated with the base 72° by a pivot region 84°. The contact 80° can be formed by punching out a metal plate, where the contact portion 68° is at the position indicated by the dashed line B in FIG. C-shaped spring member 8
0'' is applied to tilt the spring member 80' to the left with respect to the base 72°, causing an overstress condition in the spring member 80'.

When this force is released and the spring member 80° reaches its equilibrium position,
The first contact portion 68' is located at the position indicated by the solid line A in FIG. Note that tilting the C-shaped spring member 80° to the left preloads the cantilever member 74° to the left within its elastic limits. This effectively increases the operating range of cantilever member 74° from the preloaded position through the unloaded position B to position C. This C position is the most deformed to the right in FIG.

An overstress stop 94' projects upwardly from base 72' to limit movement of contact 66'.

Preferred electrical contact 100 according to a second embodiment of the invention
” is shown in Figure 9.

Like elements in both contacts 66° and 100' are given like reference numerals and will not be described again. As shown in FIG. 9, contact 100' is substantially the same as contact 66', but differs at pivot region 90'. Instead of using plastic deformation of the metal to allow pivoting movement of the end 88', the contact 100' employs a two-piece pivot nesting structure. This nesting structure 104' is provided at the end 88' and is a free end that pivotally engages the nest 106' formed in the base 72'. When the contact 100° is deformed to the right in FIG. 9 and the first contact portion 68 is moved from the A position to the B position, the portion 104′ undergoes a pivoting movement within the host 106°.

This contact 100° has a shape as shown in FIG. 9A immediately after being punched out from a metal plate. Next, the part 104°
Push the back member 1 to the left as shown by the arrow in Figure 98.
08° and latches into nest 106°.

By moving portion 104° to the left, C-shaped portion 80° moves first contact portion 68° to the left to position A, cantilevering it as well as preloading member 74° of contact 66'. Preload beam member 74''. Back member 108° assists in latching portion 104″ to nest 106°.

Another embodiment of an electrical contact 120' based on the mechanical model of FIG. 7 is shown in FIGS. 10 and 10A.

The substantially annular spring member 122° has a first end 124° extending from the base 126° and a second end 128° sheared from the base 126° along a dashed line 130° in a manner described below. A first contact portion 68° is formed at the left end of the spring member 122°, which is similar to the first contact portion 68° of contacts 66° and 100°. A tab 132° extends inwardly from the base 126' into the annular spring member 122'.

Contact 120' is stamped from a metal plate in a manner similar to that of contact 66' and is substantially the same as contact 66'.
Looks like the picture. Next, connect the end 128° to the base 126"
The latch retainer 134 is sheared along a dashed line 130° from
form. Therefore, the holder 134' is pulled out from the surface of the base 126', moved to the upper left, and then
Return to 6° plane and latch onto tab 132° as shown in Figure 1O.

As a result, the annular spring member 122' faces leftward in FIG. 10, and the first contact portion 68° moves from the unloaded position B shown by the broken line to the preloaded position shown by the solid line. Part 68°
When moving from position IB to A, portion 136' pivots through pivot area 79° to contact 100'
The cantilever member 74' operates in the same manner as the cantilever member 74'. Further, the portion 138° of the annular spring member 122° is a pivot region 841.
The contact 100' pivots similarly to that of the contact 100'.

Thus, contact 120' has similar functional elements as contact 100', although it has a somewhat different shape. That is,
Cantilevered members 74°, 136°, first and second contact portions 68', too, C-shaped spring portion 80' (section 122), pivot region 79°, 84°, 102', and base 72'. .

Electrical contact 100'120° of FIGS. 9 and 10
Further modified examples are shown in FIG. 1) and FIG. 12, respectively. In these variations, like elements are provided with like reference numerals.

As can be seen, the difference between both electrical contacts is that the pivot areas 102°, 84 are reversed.

A further variation of the 100° electrical contact is shown in FIG. 13 at 150°. This contact 150' is similar to contact 100° except that cantilever member 74 is replaced by a serpentine member 152'. Member 152
' extends from the end 76' of the substrate 72' through the pivot region 79' and the serpentine section to the end 78', which end 78' connects the end 82' of the C-shaped spring member 80' and the pivot region 84'.
Pivotally related by °. Meandering member 1
52° is arranged to resiliently respond to normal contact engagement forces. The direction of this force is in the direction of arrow F in FIG. 13, and pushes the first contact portion 68° slightly in the direction of arrow W. In this way, when the first contact portion 68' is brought into contact engagement with the package terminal 30 shown in FIG.
The inherent resiliency of the serpentine member 152' causes the first contact portion 68' to slightly wipe the mating surface. This wiping action removes dirt such as oxides from the contact surface and establishes good electrical contact.

〔Effect of the invention〕

The electrical contact of the present invention is relatively simple and compact in structure and manufacture, since it can be formed by punching out a single metal plate. More importantly, even if the first contact portion moves relatively large, the change in the distance between the two pivot areas is extremely small.

Therefore, it is possible to ensure sufficient contact pressure and counteract relatively large variations in contact portions due to large dimensional tolerances of IC chips. Therefore, it is suitable for application to electrical contacts used in sockets for IC chip burn-in tests, etc.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of one example of an electrical connector assembly in which the electrical contacts of the present invention are used. Figures 2 to 6 are explanatory diagrams of the electrical contact of the first embodiment of the present invention, Figure 2 is a mechanical model diagram, and Figures 3 and 4 are the mechanical model diagrams of Figure 2. Embodying Electrical Contacts, Figure 5 Preferred Electrical Contacts, Figures 6A-6D
The figure is an explanatory diagram of the manufacturing process of the electrical contact shown in FIG. 5. 7 to 13 are explanatory diagrams of an electric contact according to a second embodiment of the present invention, FIG. 7 is a mechanical model thereof, and FIG. 8 is an electric contact embodying the mechanical model of FIG. 9th
9A and 10A are illustrations of the manufacturing process of the electrical contacts shown in FIGS. 9 and 10, respectively, and FIGS. 1) to 13 show variations thereof. It is a diagram. 66.84,98,1) 0.86', lOO'. 120°, 150°1001. Electrical contacts? 2.9
6.1) 2.72', ..., base 70, 126.
70' , , , , Terminal part 68.130.68°1) 1
0. Contact surface 74, 94. 1)4. 74°, 136
゜0199. Contact portion 7B, 80, 86, 90, 100, 102, 80°. 82", 88°, 122', 128°, 138'19.
10 Elastic part 92.128.76°, 79', Pivot area 82.88, 104, 106, 108.84°
.

Claims (1)

[Claims] (1) a base portion, a terminal portion extending from the base portion, a contact portion extending substantially in a cantilever shape from the base portion and having a contact surface movable to a position away from the base portion; an elastic part formed in a loop shape, at least one additional pivot forming a pivot area at the engagement part between the contact part and the base part, and absorbing the pivoting movement of the pivot area in the elastic part; has an area,
An electrical contact, characterized in that it interconnects two conductors between the terminal portion and the contact surface.