JPH113759A - Test socket and test jig for integrated circuit package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a test socket for an integrated circuit package with upper and lower housings fixed to the upper and lower faces of a circuit board. SOLUTION: An upper housing 14 has a cavity 26 for receiving an integrated circuit package 12 and contains a hole at the base to put a socket plunger 38 in contact with the test seat of the integrated circuit package 12. The plunger 38 is positioned in a channel formed in a lower housing 16 and extended into a hole in a circuit board. An elastic barrier 46 or a spring is set between the lower housing 16 and the circuit board and extended under the plunger in the channel of the lower housing 16 for energizing the plunger 38 towards the integrated circuit package 12 with spring force. A conductive eyelet formed in the hole in the circuit board guides the plunger 38 to be moved and transmits a test signal from the plunger 38 to the circuit board.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a test socket for an integrated circuit package, such as a ball grid array package, the socket including an upper housing and a lower housing positioned around a load board, and from the lower housing to the load board. And applied to the integrated circuit package by a compliance element such as an elastic diaphragm positioned between the load board and the lower housing to apply an independent spring force to the solid contact pins of the test socket.

[0002]

BACKGROUND OF THE INVENTION Testing of integrated circuits contained in ball grid array (GBA) packages is typically performed using what is referred to in the art as a test socket. BGA test sockets typically include a housing that attaches to a load board that interfaces with the test electronics. The load board is typically a small circular circuit board for transmitting test signals from the integrated circuit in the BGA to the test electronics.

[0003] Conventional methods of attaching test sockets to a load board include through hole forming techniques and surface mounting techniques. In surface mount technology, the test socket is BGA
The BGA is compressed against the test pads and the test signals are transmitted to the load board. A problem with the test socket device using the surface mounting method is that the height of the solder balls on the lower surface of the BGA varies, and good electrical contact between each solder ball and the test pad cannot be ensured constantly. A second problem with surface mounts is that once the test pads become contaminated by solder balls, the entire socket assembly must be replaced.

A method of forming a through hole for connecting a socket to a load board includes drilling the load board to form a path for a spring-loaded contact pin, wherein the contact pin is a B-type contact hole.
A test signal is transmitted to the load board by contacting these test pins with holes in the load board by contacting the solder balls on the GA. A problem associated with through-hole socket devices is that the test pins extending to the load board are easily bent or damaged, which negatively impacts the test results. To solve this problem, a receptacle can be placed between the socket and the load board to protect test pins that enter the load board. As a result of the use of the receptacle, it is necessary to increase the length of the test pin in the socket, which causes a problem in testing a high-speed integrated circuit. In order to solve this problem, a spring probe having a short moving distance is employed, but a spring having a short moving distance has a short life and requires periodic replacement. Furthermore, the use of spring probes in sockets creates impedance problems with respect to the transfer of test signals from the BGA to the load board.

As a result, there remains a need for new test sockets for BGA packages that solve the problems associated with prior art test sockets.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a newly designed test socket, and in particular, a test socket for a ball grid array integrated circuit package which solves the above-mentioned problems associated with the conventional test socket device. I do. In a preferred embodiment, the test socket is BG
Designed for A package, but this socket is Q
It can be used for other integrated circuit packages such as FP packages.

[0007]

SUMMARY OF THE INVENTION A test socket according to the present invention is a test socket for an integrated circuit package having a plurality of test seats, the test socket having a cavity for receiving the integrated circuit package and being mounted on a circuit board or load board. An upper housing positioned at a lower position, a lower housing positioned below the circuit board and having a plurality of channels for receiving solid test pins, and a test seat on the integrated circuit package biasing the test pins against the circuit board. It comprises compliance means positioned beneath the circuit board for electrical contact.

The present invention further provides a test jig for an integrated circuit package having a plurality of test seats positioned on a lower surface of the integrated circuit package, the test jig comprising a cavity for receiving the integrated circuit package. An upper housing positioned on a circuit board having a plurality of cavities extending below the base of the upper housing to an opening for the test seat, positioned below the circuit board and receiving solid test pins; A lower housing having a channel and a compliance diaphragm positioned between the circuit board and the lower housing for applying an axial force to the test pins to allow electrical contact with the test seat. It is characterized by comprising.

The circuit board or load board is a small circular circuit board that is in electrical communication with the test electronics of the external tester. The upper housing has a cavity for receiving an integrated circuit package and includes a hole in a lower surface thereof to allow contact of a plurality of solid socket plungers with solder balls on a lower surface of the BGA. The socket plunger is positioned in a plurality of channels formed in rows and columns in the lower housing, and similarly extends from a plurality of holes in the rows and columns to the load board and contacts the solder balls.

In a preferred form, the compliance means is an elastic diaphragm extending from between the circuit board and the lower housing to a channel of the lower housing below the test pin. The compliance means extends below the socket plunger from top to bottom with a channel in the lower housing and biases the socket plunger upwardly toward the BGA by spring force.

In a preferred embodiment, the elastic diaphragm is a thin latex sheet. The elastic diaphragm comes into pressure contact with a movable socket plunger installed in the lower housing by an independent spring bias. In a preferred embodiment, the circuit board includes a plurality of holes, each of the holes guiding movement of the test pin to the circuit board and transmitting a test signal from a test seat of the integrated circuit package to the circuit board. Conductive eyelets for

Further, in a preferred embodiment, the compliance means is a spring positioned in each channel of the lower housing below the test pin. In a preferred embodiment, the apparatus further comprises a housing lid positioned above the upper housing to compress the integrated circuit package against the test pins. In another aspect, a test socket according to the present invention may include a refill cassette having a plurality of test pins for retrofitting the test socket.

The socket plunger according to the present invention eliminates the problem of long lead wires and spring inductance by electrically biasing the solid socket plunger with an elastic diaphragm, thereby solving the problems associated with conventional BGA test sockets. The device of the present invention also compensates for the lack of coplanarity of the solder balls on the BGA by providing a long movable length to the plunger. The use of an elastic diaphragm extends the useful life of the test socket as compared to a mechanical spring.

Further, the test socket apparatus of the present invention allows for simple and inexpensive retrofitting of the test socket by facilitating replacement of the plunger contaminated by solder balls. The socket plunger of the present invention can be easily replaced by removing the lower housing and the elastic septum, freeing the plunger from falling out of the test socket. Thereafter, the refill cassette containing the new replacement plunger is positioned on the underside of the load board, and then the load board is inverted to refill the new plunger into the test socket. The elastic diaphragm and lower housing are then reinstalled on the load board for subsequent testing. The design of the present invention allows retrofitting by simply replacing the plunger rather than the entire socket assembly. These and other advantages will be more clearly understood from the detailed description that follows.

[0015]

Next, the present invention will be described in more detail with reference to the accompanying drawings. 1 and 2, a test socket for a ball grid array integrated circuit package 12 is shown. The present invention relates to B
Although illustrated with a GA package, the new design of the test socket can be used to test other integrated circuit packages as well. To clarify the entire detailed description, a BGA package will be described. The test socket 10 of the present invention includes an upper housing 14 and a lower housing 16 secured to an upper surface 18 and a lower surface 20 of a load board 22, respectively. The upper housing 14 and the lower housing 16 are preferably made of plastic and have screws 24 passing through the housing and the load board.
Is firmly fixed to the load board. The load board is a small circular circuit board that is in electrical contact with the test electronics of an external tester (not shown).

The upper housing 14 includes a cavity 26 inside the upper housing 14 for receiving the ball grid array package 12. The ball grid array package comprises an integrated circuit 28 positioned on a substrate 30 and a plurality of solder balls 32 positioned on a lower surface of the substrate opposite the integrated circuit and in electrical communication with the integrated circuit from the substrate 30. Have. Solder balls 32 act as test pads for testing integrated circuits. The substrate 30 contacts the flange 34 at the base of the cavity 26,
In addition, the solder ball 32 reaches the upper surface 18 of the load board 22 from a hole 36 formed by the flange 34.

A hole 36 in the base of the upper housing 14 engages a plurality of solid socket plungers 38 with solder balls 32.
It has an opening to make contact with. As seen in FIG. 3, the socket plunger 38 is positioned within a plurality of channels 40 formed in columns and rows within the lower housing 16 and extends into a plurality of holes 41 leading to the load board 22 to provide a solder plunger. It comes into contact with the ball 32. Holes 41 are similarly formed in columns and rows, similar to the pattern of solder balls 32 on the BGA package. The solid socket plunger 38 comprises an enlarged head 42 and an elongated arm 44 having a relatively small diameter. The arm 44 extends into a hole 41 in the load board 22 and the enlarged head 42 is held in a channel 40 in the lower housing 16.

The elastic diaphragm 46 is provided on the upper surface 4 of the lower housing 16.
8 and the lower surface 20 of the load board 22,
And extends below the head 42 of the socket plunger 38 onto the channel 40 in the lower housing 16 to force the socket plunger 38 above the BGA by spring force so that the inclined upper surface 50 of the plunger arm 44 Energize for good electrical contact. The inclined surface 50 at the end of the plunger arm 44 is machined so as to make a bias contact with the solder ball 32. The flexible diaphragm 46 is in bias contact with a movable socket plunger 38 mounted in the lower housing 16 by an independent spring pressure. The conductive cylindrical eyelets 52 are connected to the respective holes 41 in the load board 22.
To guide the movement of the arm portion 44 of the socket plunger and transmit a test signal generated from the solder ball 32 from the socket plunger 38 to the load board 22. The eyelet 52 is preferably formed of a conductive material such as copper beryllium or nickel silver. Through holes 41 in load board 22 are typically plated, and eyelets 52 include solder preform rings 53;
The preform ring 53 solders the eyelets 52 to the plated through holes to secure the eyelets 52 to the load board 22.

The elastic diaphragm 46 is held between the lower housing 16 and the load board 22 by screws 24. Elastic diaphragm 46
Is preferably a thin, flexible sheet of elastic latex rubber that allows direct contact with the socket plunger head. The elastic diaphragm 46 is preferably a latex rubber, but other materials can be used that allow the diaphragm 46 to provide a biasing spring force to the socket plunger 38. In the normal position, the septum 46 has been stretched to conform to the shape of each plunger head, and the axial force applied to each plunger 38 in the direction of the septum 46 during use causes the septum 46 to stretch, causing a general return spring and Similarly, compliance is given to the end of the plunger 38. In response to the axial movement of the plunger 38, the thin flexible diaphragm 46 freely expands into the channels 40 in the lower housing 16 so as to expand or expand into the voids in each channel 40. In one form illustrated in FIG. 1, an axial force is applied to the socket plunger 38 by a housing lid 54 hinged to the upper housing 14, and the upper housing 14 is secured in a closed position by a clasp (not shown). I do. The lid 54 includes an enlarged central portion 56 sized to press the BGA package against the socket plunger 38, thereby extending the elastic diaphragm 46. Optionally, an axial force is applied above the BGA package and from the cavity 26 as shown in FIG.
4, may be added to the BGA package. In this configuration, no housing lid is required and is kept in the open position.
The use of the robot arm 58 may be incorporated into an automated test configuration. The elastic diaphragm 46 of FIG. 2 is shown in a normal position before an axial force is applied to the BGA package.

The test socket device according to the present invention is designed so that the socket plunger 3
The ability to easily replace 8 allows a simple and inexpensive retrofit of the test socket. With repeated use, the inclined surface 50 of the socket plunger 38 is contaminated with the deposited tin or lead of the solder ball 32. Fig. 4
This can be easily performed by using the refill cassette 60 shown in FIG. The refill cassette 60 is adapted to receive the replacement socket plunger 64.
Plastic blocks that include a plurality of recesses 62 formed in rows and columns that extend into are preferred. FIG. 4 shows six replacement socket plungers extending upwardly from recesses 62 for illustration purposes. A separate socket plunger 64 is positioned in each recess 62 and matches the upper surface 66 of the refill cassette 60. The refill cassette 60 also includes positioning holes 68 for aligning the refill cassette 60 during retrofit.

In order to retrofit the test socket, the contaminated socket plunger is mounted on the lower housing 16 and the elastic diaphragm 4.
It is easily moved by removing 6, thereby allowing the contaminated plunger to drop freely from the test socket. Thereafter, the refill cassette 60 is placed on the lower surface of the load board 22 and then inverted to refill the test socket with a new plunger. Next, the elastic diaphragm 46 and the lower housing 16 are reinstalled on the load board 22 for subsequent testing.

FIG. 5 illustrates another test socket device. The test socket 70 of FIG. 5 is identical to the test socket of FIGS. 1 and 2 except that the compliance means is a spring 72 positioned in the channel 40 in the lower housing 16. In this configuration, the upper surface 48 of the lower housing 16 is adjacent to the lower surface 20 of the load board 22. Channel 40 in lower housing 16 is a blind hole that does not extend completely through lower housing 16 and terminates at floor location 74. Although this test socket can be used to test a BGA package, FIG. 5 shows a situation where another integrated circuit package having another type of test seat 76, such as a test pad or test lead, may be tested.

While the present invention has been described and illustrated with reference to a preferred embodiment, other changes or modifications are possible without departing from the scope of the claims.

[Brief description of the drawings]

FIG. 1 is a sectional view of a BGA test socket of the present invention in a bias state.

FIG. 2 is a cross-sectional view of the test socket of FIG. 1 in a non-biased state.

FIG. 3 is an enlarged explanatory view of a socket plunger assembly.

FIG. 4 is a perspective view of a refill cassette of the test socket.

FIG. 5 is a cross-sectional view of another test socket device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Test socket 12 ... Ball grid array integrated circuit package 14 ... Upper housing 16 ... Lower housing 22 ... Load board 28 ... Integrated circuit 32 ... Solder ball

Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01R 23/68

Claims (10)

[Claims] 1. A test socket for an integrated circuit package having a plurality of test seats, the test socket having a cavity for receiving the integrated circuit package.
An upper housing positioned on the circuit board, a lower housing positioned below the circuit board and having a plurality of channels for receiving solid test pins, and biasing the test pins to the circuit board to place the test pins on the integrated circuit package; A test socket for an integrated circuit package comprising compliance means positioned under said circuit board for making electrical contact with a test seat. 2. The test socket according to claim 1, wherein said compliance means is an elastic diaphragm extending from between said circuit board and said lower housing to a channel of said lower housing below said test pin. 3. The test socket of claim 2, wherein said elastic diaphragm is a thin latex sheet. 4. The circuit board includes a plurality of holes, each of the holes guiding movement of the test pin to the circuit board and transmitting a test signal from a test seat of the integrated circuit package to the circuit board. Having a conductive eyelet for
The test socket of claim 1. 5. The test socket of claim 1, wherein said compliance means is a spring positioned in each channel of said lower housing below said test pin. 6. The test socket of claim 1, further comprising a housing lid positioned above the upper housing to compress the integrated circuit package against the test pins. 7. A refill cassette having a plurality of test pins for retrofitting the test socket, further comprising:
The test socket of claim 1. 8. A test jig for an integrated circuit package having a plurality of test seats positioned on a lower surface of the integrated circuit package, the test jig being positioned on a circuit board having a cavity for receiving the integrated circuit package. A lower housing having a plurality of channels positioned below the circuit board and receiving solid test pins; a housing, the cavity extending into an opening for the test seat within a base of the upper housing; A test jig for an integrated circuit package comprising a compliance diaphragm positioned between the circuit board and the lower housing for applying an axial force to the test seat to allow electrical contact with the test seat. 9. The test jig of claim 8, wherein said compliance diaphragm is a thin latex sheet. 10. The circuit board includes a plurality of holes, each of the holes guiding movement of the test pins to the circuit board and transmitting a test signal from the integrated circuit package to the circuit board. 9. A conductive eyelet.
Test jig.