Electrical socket apparatus

Description

FIELD OF THE INVENTION

This invention relates to an electrical socket for removably loading an electric part such as an IC (integrated circuit) having electrical terminals on its lower surface and electrically connecting each terminal to external equipment and more particularly to such a socket especially adapted for use with semiconductor packages of the BGA (Ball Grid Array) type.

BACKGROUND OF THE INVENTION

Ordinarily, plastic encapsulated IC packages are subjected to electric property tests and a reliability test called a burn-in test prior to shipment in order to distinguish between good and defective products. In an electrical property test, input and output characteristics of the IC chip, pulse properties, noise leeway, and the like, are tested. Those IC packages that pass the electric property test are then subjected to a burn-in test in which they are arranged in an oven and caused to function for a certain period of time at a selected high temperature, for example, 125° C., and under a source voltage which is approximately 20 per cent higher than the rated value. IC packages that fail the burn-in test are discarded as defective products and only those IC packages that continue functioning properly are shipped out as good products.

BGA packages having spherical solder balls arranged on the lower side of the packages in a selected matrix or zigzag fashion are in wide use. This type of package is capable of having an increased terminal pitch with a small outer dimension and is more resistant to damage caused by contact with other parts.

FIGS. 6

a

and

6

b

show a typical prior art socket used for burn-in tests of IC's such as BGA packages. Socket

101

comprises a plastic (in plan view) rectangular base

102

on which is mounted a horizontally movable slider

103

which receives thereon a BGA package. A frame shaped cover defining an opening

104

a

, also made of plastic, is received on top of base

102

and is vertically movable relative to the base. The cover is biased in a direction away from the base by means of compression coil springs

105

. A through hole corresponding to each solder ball

100

a

of the BGA package is formed in slider

103

and base

102

. A contact member

106

for electrical connection with a respective solder ball

100

a

of the BGA package is arranged to run through each of the through holes of slider

103

and base

102

. Each contact member

106

comprises an elongated metallic member having a pair of arms

106

a

and

106

b

provided at one end thereof. Each contact member

106

is fixed in a vertical attitude on base

102

, with arms

106

a

and

106

b

facing upwardly. Each contact member has a protruding part such as a tab (not shown in the drawing), on one of side by side arms

106

a

,

106

b

. Arms

106

a

,

106

b

open relative to one another as the tab engages with a partition wall (not shown in the drawing) of slider

103

. A sliding mechanism for moving slider

103

in parallel with the bottom of base

102

comprises a pair of generally L-shaped lever member

108

rotatably connected at opposite ends of a shaft

107

. Shaft

107

is received in a slot formed at the right side of slider

103

as seen in the drawings. A short arm

108

a

of each lever member

108

is rotatably connected to a shaft

109

mounted in base

102

thereof at one side (the right-hand side shown in the drawing), installed so that it extends in parallel with shaft

107

. A respective lever member

111

is rotatably connected at both ends of a shaft

110

mounted on the opposite side of base

102

and extending in parallel with shafts

107

,

109

and the end portion of each lever member

108

is slidably connected in a longitudinally extending slot formed in the middle part of lever members

111

by means of pins

112

. The distal tip

11

l

a

of lever member

111

engages a protruding part

104

b

of the top wall of cover

104

. Horizontally disposed compression coil springs

113

are placed between base

102

and slider

103

in the vicinity of shaft

110

for biasing the slider in the direction shown by the head of arrow X in

FIG. 6

b.

In a socket

101

constructed as described above, if cover

104

is pressed down from the position shown in

FIG. 6

a

to the position shown in

FIG. 6

b

, lever members

108

and

111

rotate toward base

102

and shaft

107

moves slider

103

in conformity with the movement of lever member

108

, thereby shifting it in the opposite direction from the one indicated by arrow head X. As a result of this, one of the arms, for example, arm

106

a

of each contact member

106

, engages the partition wall of slider

103

and is thereby opened. If, in this state, BGA package

100

is inserted into adaptor

103

c

of slider

103

, each solder ball

100

a

of BGA package

100

enters the gap between the open arms

106

a

and

106

b

of a respective contact member

106

. When the downward force on cover

104

is removed, lever members

108

and

111

rise and slider

103

moves in the direction of the head of arrow X by means of the force exerted by compression coil springs

113

, closing arms

106

a

and

106

b

of each contact member

106

with each solder ball

100

a

of BGA package

100

held by arms

106

a

and

106

b

of a respective contact member

106

. As a result of this, each solder ball

100

a

of BGA package

100

can be electrically connected to a respective contact member

106

.

In the case of a prior art socket as described above, however, the linkage mechanism made by lever members

108

,

111

and associated shafts used for moving slider

103

requires an increased number and complexity of parts along with an increase in the number of steps and time for assembling the product.

Further, such linkage mechanisms increase the size and weight of the socket itself.

SUMMARY OF THE INVENTION

An object of the present invention is the provision of an electrical socket of light weight and small size in which the number of parts involved is small and the construction is simple. Another object of the invention is the provision of a socket which overcomes the limitations of the prior art noted above and having fewer parts, of a simple structure, light weight and small size.

An electrical socket made in accordance with the invention comprises a base for removably loading an electric part such as a plastic encapsulated IC package in which the conductive terminals of the electric part are arranged according to a selected pattern, a plurality of contact members arranged in the base in accordance with the arrangement pattern of the conductive terminals of the electric part with each contact member having a pair of contact arms capable of elastically opening and closing to sandwich a respective conductive terminal of the electric part. A contact actuating member is provided having engagement parts for engaging with at least one arm of each pair of contact arms of each contact member to open or close the contact arms. The contact actuating member moves in the opening and closing direction of the contact arms by receiving an external force on a force receiving surface in a direction which crosses, approximately at a right angle, the opening and closing direction of the contact arms. The force receiving surface includes a portion inclined by a selected angle relative to the direction of the external force. According to a feature of the invention, a motion transfer portion engages the force receiving surface of the contact actuating member. The movement of the motion transfer portion is in a direction which crosses, approximately at a right angle, the opening and closing direction of the contact arms. According to the first preferred embodiment, the motion transfer portion extends downwardly from a cover positioned over the socket body. According to a feature of an alternate embodiment, the motion transfer portion extends downwardly from a head movable toward and away from the socket base, the head provided with a holding part which is capable of removably holding the electric part. According to another feature of the alternate embodiment, the head holds the electric part by air suction.

According to the invention, the motion transfer portion directly engages force receiving surfaces of the contact actuating member for moving the contact actuating member in the opening and closing direction of the contact arms. Accordingly, prior art lever members and associated linkage mechanism are no longer necessary. As a result, the number of the parts is drastically reduced and, at the same time, the construction simplified. In addition, the assembling steps can also be simplified. According to the invention, moreover, the size of the socket itself can be reduced and, at the same time, its weight can be drastically reduced.

These and other objects and features of the invention will be apparent to the following description taken with reference tot the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of a socket made according to the invention will be explained below in detail by referring to the attached drawings.

FIG. 1

is a front elevational view, partly in cross section, showing an electrical socket having a cover

3

in the raised position;

FIG. 2

is a front elevational view of the main body of the

FIG. 1

socket and a BGA package receivable in the socket;

FIG. 3

a

is a top plan view showing the external appearance of the

FIG. 2

main socket body;

FIG. 3

b

is an enlarged portion of

FIG. 3

a;

FIG. 4

is a perspective view showing the external appearance of the main socket body;

FIG. 5

is an exploded perspective view of a main body and a head made in accordance with an alternate preferred embodiment along with a BGA package; and

FIGS. 6

a

and

6

b

are cross sectional views of a prior art socket used for burn-in tests.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to

FIGS. 1-4

, socket

1

comprises a main socket body l

a

having a base

2

and a slide member

4

which serves as; an actuation member disposed on the base. A cover

3

is received on base

2

for providing a contact actuation force. These components are composed of suitable moldable plastic such as polyetherimide, etc. Base

2

is formed in a suitable configuration, such as a rectangular shape, as seen in a top plan view, and has a contact member support portion

7

, as shown in

FIG. 2

, formed at the center of the base for mounting a large number of contact members

6

for attachment to a circuit substrate, such as a printed circuit board (not shown in the drawing). Cover

3

is formed as a window frame in a shape and size complimentary to base

2

, with an opening (not shown in the drawing) being formed for the insertion of a BGA package (electric part) at its center. A guide portion

3

a

extends downwardly from each side of cover

3

and is slidably received in a respective guide groove

2

a

provided on each side of base

2

. Cover

3

moves toward and away from base

2

while maintaining a mutually parallel relationship therewith. Compression coil spring means (not shown) are provided between cover

3

and base

2

to bias cover

3

in a direction away from the base to normally cause their mutual separation.

As shown in

FIG. 3

a

, seating parts

40

are provided on the upper surface of slide member

4

at each corner thereof for the placement of a BGA package

5

. A positioning guide

41

is provided around seating parts

40

for guiding and positioning the BGA package at a preselected location. A lattice-shaped partition wall, also called engagement part

4

a

, is formed by a large number of through holes

4

b

. The partition wall is disposed inside the seating parts

40

on top of slider

4

. The distal free end tips of a pair of arms

6

a

and

6

b

of each contact member

6

run through the holes and protrude above the top of slide member

4

. Each contact member is arranged so that arms

6

a

,

6

b

are disposed on opposite sides of a partition wall

4

a

of slider member

4

, as seen in

FIG. 3

b

. That is, arms

6

a

,

6

b

of each contact

6

, are positioned in different adjacent through holes

4

b

so that upon the movement of slide member

4

in the direction indicated by arrowhead A, arm

6

a

is moved to the dotted line position (open position) relative to arm

6

b

as shown in

FIG. 3

b

. Slide member

4

is so constructed as to be able to move in the opening and closing directions of arms

6

a

,

6

b

of contact members

6

on base

2

.

Positioning parts

42

are provided on two opposite sides of slide member

4

, as shown in

FIGS. 3

a

and

4

. As these positioning parts

42

are guided by the inner surface

2

b

of base

2

, slide member

4

is movable in the direction indicated by arrow head A or B which are the opening and closing directions of arms

6

a

,

6

b

of contact members

6

. Slide member

4

is biased away from movable arms

6

a

by the spring force of compression coil springs

8

when no external force is applied to cover

3

. A force receiving surface

43

, shown in

FIG. 1

, is formed at the top of each positioning part

42

of slide member

4

for receiving an external force to open arms

6

a

,

6

b

of contact members

6

. Force receiving surface

43

is disposed at a location on the side of positioning part

42

of slide member

4

indicated by arrow head B. Each force receiving surface

43

is tapered to lie in a generally flat plane, inclined by a selected angle, in the opening and closing directions of arms

6

a

,

6

b

of contact members

6

. The angle of inclination of each force receiving surface

43

is not restricted as long as it is greater than zero and smaller than 90° relative to the opening and closing direction of arms

6

a

,

6

b

of contact members

6

. Each force receiving surface

43

can also be formed as a curved surface, if desired. Motion transfer portions

30

are formed on cover

3

, for providing an external force to each force receiving surface

43

of the slide member as the cover is depressed. Motion transfer portions

30

extend downwardly from cover

3

at an interval which is the same as the interval of the receiving surfaces

43

of slide member

4

at a position on cover

3

that corresponds to slide member

4

. An engagement surface

31

is formed at a position on the side of each motion transfer portion

30

of cover

3

indicated by the side in which the arm

6

a

of the contact

6

is opened. According to the preferred embodiment, engagement surfaces

31

are preferably each formed having a wedge shape with a slight curve at the bottom thereof. As shown in

FIG. 1

, openings

20

are formed in base

2

having a depth and size to slidingly receive each respective motion transfer portion

30

at a position corresponding to each motion transfer portion of cover

3

. Cover

3

is disposed at a location away from base

2

due to the force of compression coil springs in the absence of a downward force on the cover so that engagement surfaces

31

of motion transfer portions

30

of cover

3

and the receiving surfaces

43

of slide member

4

are out of engagement with each other.

When cover

3

is pressed down from the raised position, engagement surface

31

of each motion transfer portion

30

of cover

3

engages each respective force receiving surface

43

of slide member

4

and, as an external force, including the component in the direction indicated by the head of arrow A, works on each of these force receiving surfaces

43

, slide member

4

moves in the direction which is indicated by arrow head A and partition wall

4

a

engages with arm

6

a

of each contact member

6

, with a result that the arms

6

a

,

6

b

are opened relative to one another. When, in this state, a BGA package

5

is placed on seating parts

40

of slide member

4

and the downward force on cover

3

is removed, a reverse procedure occurs and arms

6

a

,

6

b

of each contact member

6

are closed and each solder ball of BGA package

5

is compressively engaged by a respective pair of arms

6

a

,

6

b

.

The removal of BGA package

5

is effected by pressing the cover

3

once again to open the arms of the contact members

6

.

In the embodiment described above, engagement surfaces

31

of cover

3

are caused to directly engage the respective force receiving surfaces

43

of slide member

4

, thereby causing slide member

4

to move in the opening and closing directions of arms

6

a

,

6

b

. Accordingly, the prior art lever members and linkage mechanism are no long necessary thereby reducing the number of parts used and, at the same time, simplifying the structure. Further, the assembling steps

5

are also simplified. According to the invention, moreover, the size and weight of the socket can be reduced.

With reference to

FIG. 5

, an electric part loading device or socket

10

made according to another embodiment of the invention comprises a head

11

capable of holding a BGA package

5

by air suction. Head

11

is vertically movable when arranged at a position corresponding to slide member

4

of base

2

and includes force transfer portions

30

as described above. Force transfer portions

30

extend downwardly from head

11

at locations that correspond to those of slide member

4

at the same interval as the interval of forcing receiving surfaces

43

of slide member

4

. Engagement surfaces

31

having an angular part in the shape of a slightly curved surface are formed at the lower part on the side of the direction indicated by arrow head A (

FIG. 4

) of the force transfer portions

30

of head

11

, the side in the direction where arm

6

a

of the contact is opened. In view of the placement of force transfer portions on head

11

, cover

3

for the socket is no longer needed, with a result that it becomes possible to reduce still further the number of parts used for the electric part loading device and thus simplify the construction and reducing the size and weight. As the other structure, effects and functions are the same as in the first described embodiment, a detailed explanation thereof will not be repeated.

The invention is not intended to be limited to the specific embodiments described above. For example, while the force receiving surfaces

43

of the slider are inclined by a selected angle relative to the opening and closing directions of arms

6

a

,

6

b

of the contact members, it is possible to incline the engagement surfaces of the force transfer portions

30

in the same manner. Even though the slider and the adaptor have been formed integrally, they can also be formed as separate members. It should also be noted that sockets of the invention can be used not only for burn-in tests but also can be used in various electric property tests. Further, sockets made in accordance with the invention can be used not only in the case of BGA packages but also with various other packages including the PGA package, etc.

According to the invention which has been described above, it becomes possible to drastically reduce the number of the parts involved and simplify the structure thereof. In addition, the assembling steps can also be simplified. Further, the size and weight of the socket can be reduced. According to the invention, moreover, an electric part loading device of light weight, whose construction is simplified, can be obtained.

It is the intention that the invention include all modifications and equivalents of the disclosed embodiments falling within the scope of the appended claims.

Claims

1. An electrical socket comprising a base for removably loading an electric part having a plurality of conductive terminals arranged in a selected pattern, a slide member mounted on the base and being movable in a horizontal direction back and forth between two extremities, the slide member being formed with the contact receiving holes therethrough and a contact actuating member, a plurality of contact members mounted on the base and arranged in accordance with the pattern of the conductive terminals of each electric part, each contact member having at least one movable contact arm extending through the contact receiving holes, the contact actuating member engaging the at least one contact arm of each contact member to move each contact member between an open and a closed position, the slide member formed with force receiving surface forming an angle relative to the horizontal direction and a motion transfer member vertically movable into engagement with the force receiving surface to transfer motion directly to the slide member causing it to move.
2. An electrical socket according to claim 1 further comprising a plurality of motion transfer members movable into and out of engagement with a plurality of force receiving surfaces of the slide member.
3. An electrical socket according to claim 2 further comprising a cover which mounts the motion transfer members.
4. An electrical socket according to claim 2 further comprising a head which mounts the motion transfer members and a holding portion for removably holding an electronic part.
5. An electrical socket according to claim 4 in which the holding portion for holding the electric part comprises an air suction device.
6. An electrical socket for removably receiving an electric part having a plurality of terminals arranged in a selected pattern comprising a base, a slide member mounted on the base and being movable in a horizontal direction back and forth between first and second extremities, a spring member biasing the slide member in one direction between the extremities, the slide member being formed with an electric part seating surfaces and contact arm receiving holes therethrough and an actuating member, a plurality of contact members mounted in the base, each contact member having a pair of movable spring contact arms extending through the contact arm receiving holes, the contact actuating member engaging at least one contact arm of each pair to move a contact arm of each pair relative to the other contact arm of the respective pair upon movement of the slide member, the slide member formed with a force receiving surface forming an angle of more than zero degrees and less than 90 degrees relative to the horizontal direction and a motion transfer portion vertically movable into engagement with the force receiving surface to transfer motion directly to the slide member causing the slide member to move against the bias of the spring member.
7. An electrical socket according to claim 6 in which the force receiving surface is generally flat.
8. An electrical socket according to claim 6 further comprising a cover having a central opening therethrough, the cover vertically movable toward and away from the base and the motion transfer portion is wedge-shaped and extends downwardly from the cover.
9. An electrical socket according to claim 8 further comprising a plurality of wedge-shaped motion transfer portions extending downwardly from the cover and a plurality of force receiving surfaces are formed on the slide member, each motion transfer portion being aligned with a respective one of a plurality of force receiving surfaces.
10. An electrical socket according to claim 9 in which each motion transfer portion includes a tapered, generally vertically disposed engagement surface for engagement with a respective force receiving surface of the slide member.
11. An electrical socket according to claim 10 in which each tapered engagement surface forms a slight curve.
12. An electrical socket according to claim 6 further comprising a head having an air suction, electric part holding portion, the head vertically movable toward and away from the base and the motion transfer portion is wedge-shaped and extends downwardly from the head.
13. An electrical socket according to claim 12 further comprising a plurality of wedge-shaped motion transfer portions extending downwardly from the head and a plurality of force receiving surfaces are formed on the slide members, each motion transfer portion aligned with a respective one of the plurality of force receiving surfaces.
14. An electrical socket according to claim 13 in which each motion transfer portion includes a tapered, generally vertically disposed engagement surface for engagement with a respective force receiving surface of the slide member.

Priority Claims (1)

Number	Date	Country	Kind
11-341360	Nov 1999	JP

US Referenced Citations (6)

Number	Name	Date
4468072	Sadigh-Behzadi	Aug 1984
5147213	Funk et al.	Sep 1992
5807127	Ohshima	Sep 1998
6027355	Ikeya	Feb 2000
6050836	Tohyama	Apr 2000
6126467	Phashi	Oct 2000

Electrical socket apparatus

Information

Patent Number

Date Filed

Date Issued

Inventors

Original Assignees

Examiners

Agents

CPC

US Classifications

Field of Search

US

International Classifications

Abstract

Description

Claims

Priority Claims (1)

US Referenced Citations (6)