WO2008026875A1

WO2008026875A1 - Probe beam assembly

Info

Publication number: WO2008026875A1
Application number: PCT/KR2007/004154
Authority: WO
Inventors: Yong Whan Kim
Original assignee: Nemsprobe Co., Ltd.
Priority date: 2006-09-01
Filing date: 2007-08-29
Publication date: 2008-03-06

Abstract

A probe beam assembly is disclosed. The probe beam assembly includes a plurality of probe beams, each of which includes a rectangular body, a contact part protruding from the upper end of the body, and a connector part protruding from the left, middle or right portion of the lower part of the body. Two outer sockets receive therein the left and right edges of the probe beams, with predetermined intervals defined between the probe beams. An elastic receiving unit receives therein the connector parts of the probe beams. Two locking pins are inserted into respective locking holes formed in the upper and lower portions of the bodies of the probe beams after the probe beams have been arranged in the space between the two outer sockets such that the surfaces of the probe beams face each other. The present invention provides simple sockets for arranging the probe beams therein at predetermined intervals.

Description

[invention Title]

PROBE BEAM ASSEMBLY

[Technical Field] The present invention relates, in general, to a probe beam assembly constituting a probe card used for inspecting semiconductor chips and, more particularly, to a probe beam assembly, which is easily engaged with and disengaged from the lower connector parts of probe beams, and includes an elastic receiving unit capable of reducing contact resistance of the probe beams relative to PCB pads or PCB lands compared to conventional probe beam assemblies.

[Background Art] As an example of conventional probe beam assemblies, reference can be made to "A Probe Pin and Socket Assembly for Probe Cards" disclosed in Korean Utility Model Registration No. 20-0396613 (hereinbelow, referred to simply as "prior art document") . As shown in FIG. 1 and FIG. 2, the assembly disclosed in the prior art document includes a plurality of probe pins 20' and a probe pin socket 10' , which is provided with a plurality of slots 3a' for receiving the left or right edges of the respective probe pins 20' therein. Hereinbelow, the technical term "probe pin," used in the prior art document, will be substituted with "probe beam" , in consideration of technical terms used in the present invention.

The slots 3a' are formed on the opposite side surfaces of the probe beam socket 10' and hold the left or right edges of the probe beams 20' therein. Further, the lower surface of the socket 10' is provided with a locking protrusion 5' having locking holes 5a' . The locking protrusion 5' is seated in the locking groove 30a' of a PCB 30' and is fastened to the PCB 30' by driving locking bolts 9' into the respective locking holes 5a' at positions below the locking groove 30a' of the PCB 30' . Because the slots 3a' and locking holes 5a' are formed by- machining them, it is very difficult to form the slots 3a' and locking holes 5a' on the assembly such that the precision with which the slots 3a' and holes 5a' are machined meets the precision of semiconductor chips having micro pitches between chip pads. This is attributable to the fact that the precision of machining is fundamentally limited.

Further, the probe beam assembly must be locked to a PCB 30' using locking bolts 9', and thus the locking process incurs excessive cost and excessive time, thus being inefficient. Further, when it is required to remove the probe beam assembly from the PCB 30' to change the assembly with a new one, the assembly reduces work efficiency.

Further, the probe beam assembly is configured such that electric contact of the probe beam 20' with a PCB is accomplished by contacting or welding the lower end of a connector part 16' (in the prior art document, the element corresponding to the connector part 16' is called a "contact part") with or to a PCB pad or PCB land. However, because the probe beam is very thin, the surface area with which the probe beam comes into contact with the PCB pad is very small. This means that the contact resistance between the probe beam and the PCB pad is very high. Thus, in the prior art document, the following solution was proposed to reduce the unacceptably high contact resistance between the probe beam and the PCB pad. As shown in FIG. 1 and 2, the shape of the connector part 16' is configured to be a zigzag shape, thus mechanically- providing predetermined elasticity to the connector part 16' . Therefore, when the socket 10' is. mounted to a PCB using the locking bolts 9', the connector parts 16 can be deformed in opposite directions relative to the PCB pads. This can be accomplished through contraction of the elastic body. After the socket 10' is mounted to the PCB, elastic restoring force is applied to the PCB pad, so that the looseness of the contact part on the pad can be minimized and the contact resistance between the contact part and the pad can be minimized within predetermined conditions .

However, the above-mentioned technique of minimizing the contact resistance proposed in the prior art document entails the following problems. The first problem is caused by the fact that it is necessary to provide a means for preventing the probe beams 20' from moving upwards and away from the socket 10' due to elasticity. In the prior art document, the means therefor is not clearly described, but a bonding agent, used for fixing the probe beams 20' to the slots 3a' , may be used as the means for preventing the probe beams 20' from moving upwards from the socket 10' due to elasticity. However, the bonding agent disclosed in the prior art document must be a reliable bonding agent capable of resisting a reaction caused by the elastic restoring force repeatedly imposed thereon.

The second problem is caused by the fact that the elastic restoring force is basically influenced by the locked state of the probe beam socket 10' relative to the PCB using the locking bolts. This second problem becomes worse in conjunction with the above-mentioned problem caused by the probe beam socket 10' . In other words, the probe beam socket 10' must be configured as a complicated structure due to the specific structure of the probe beams 20' . For example, the locking of the probe beam socket 10' to the PCB can be accomplished using only the locking bolts.

The third problem is caused by the fact that the connector part 16', configured to have a small sectional area to provide predetermined elasticity, inevitably has a long electric path. This third problem can be easily understood from Ohm' s law, which states that the electric resistance of a conductor is directly proportional to the length thereof and is inversely proportional to the sectional area thereof.

[Disclosure] [Technical Problem]

Accordingly, the present invention has been made keeping in mind the above problems occurring in the related art, and provides a probe beam assembly, which provides a simple connector part that does not require the application of elastic force, and provides an elastic receiving unit capable of easily engaging and disengaging with and from the connector part and reducing the contact resistance of probe beams relative to PCB lands or PCB pads .

Further, the present invention serves to provide a probe beam assembly, which prevents the application of upward and downward vertical force to the probe beams, thus preventing deformation of the probe beams.

[Technical Solution] In an aspect, the present invention provides a probe beam assembly, including: a plurality of probe beams, each having a rectangular body, a contact part protruding from a predetermined portion of the upper end of the rectangular body, and a connector part protruding from a left, middle or right portion of the lower end of the rectangular body; a pair of outer sockets for holding left and right edges of the probe beams in slots thereof such that the probe beams are arranged with predetermined intervals defined between them; a U-shaped elastic receiving unit, which is soldered to a pad or land of a PCB and holds the connector parts of the probe beams therein; and a pair of locking pins inserted into respective locking holes formed in upper and^' lower portions of the rectanguJar bodies of the probe beams in a state in which the probe beams are arranged in the space between the outer sockets while facing each other.

The probe beam assembly may further comprise: a longitudinal rectangular hole formed in the rectangular body of each of the probe beams at a location between the locking holes; an inner socket inserted into the probe beams through the space inside first edges of the longitudinal rectangular holes; and a support pin inserted into the probe beams through the space between the inner socket and second edges of the longitudinal rectangular holes .

The second edge of the longitudinal rectangular hole may be provided with a semicircular groove for placing the support pin therein.

Each of the locking pins may be made of an insulating material .

The support pin may be made of an insulating material . Each of the outer sockets may be made of the same material as that of a silicon wafer.

Each of the outer sockets may be coated with an oxide film on the surface thereof .

The inner socket may be made of the same material as that of a silicon wafer.

The inner socket may be coated with an oxide film on a surface thereof .

The elastic receiving unit may include: a plurality of U- shaped elastic pieces each having locking slots in left and right portions on upper and lower parts thereof; and a plurality of locking pins inserted into the locking slots of the elastic pieces in a state in which the elastic pieces are arranged to face each other.

Each of the elastic pieces may include: a flat part to be soldered to the pad or land of the PCB; and left and right arms extending from left and right portions of the flat part.

Each of the left and right arms may have a rounded edge on an inner edge on the upper end thereof .

The left and right arms may include respective concaves on the left side of the left arm and on the right side of the right arm.

Each of the elastic pieces may be made of a conductive material .

Each of the locking pins may be made of a conductive material .

The connector parts of the probe beams, held by the outer sockets, may be arranged in an oblique arrangement, in which the connector parts are sequentially placed at a left position, a middle position, a right position, a left position, a middle position, and a right position, or in a zigzag arrangement, in which the connector parts are sequentially placed at a left position, a middle position, a right position, a middle position, a left position, a middle position, and a right position.

[Advantageous Effects]

As described above, the probe beam assembly according to the present invention has a simple socket structure for arranging the probe beams at predetermined intervals, and does not require a separate means for adding elasticity to the probe beams for maintaining the contact state of the probe beams relative to a PCB pad.

Further, the probe beams are easily installed in and easily removed from the assembly, and the opposite surfaces of the connector part of each probe beam are in contact with an elastic receiving unit, thus reducing contact resistance compared to the conventional technique.

Further, the outer sockets and the inner socket are made of the same material as that of a silicon wafer, which is the basic material of the chips used in an IC. Thus, the sockets and the chips have the same thermal coefficient of expansion, and thus the probe beams can be rearranged at adjusted intervals corresponding to variation in the pitch between the chip pads . Further, no vertical force is imposed on the connector parts of the probe beams except for in the state in which the connector parts are in contact with the chip pads, and thus it is possible to prevent undesired deformation of the probe beams despite repeated use of the probe beams over a lengthy period of time. [Description of Drawings]

FIG. 1 and FIG. 2 are views illustrating a conventional probe beam assembly;

FIG. 3 is a view illustrating a probe beam assembly according to the present invention;

FIG. 4 is an exploded perspective view of the probe beam assembly according to the present invention;

FIG. 5 is a perspective view illustrating three probe beams according to the present invention; FIG. 6 is a view illustrating both the connector parts of the probe beams according to the present invention and the arrangements of an elastic receiving unit for holding the connector parts;

FIG. 7 is a perspective view illustrating an outer socket according to the present invention;

FIG. 8 is a perspective view illustrating an inner socket according to the present invention;

FIG. 9 is an exploded perspective view illustrating the elastic receiving unit according to the present invention; FIG. 10 is a view illustrating an elastic piece constituting the elastic receiving unit of FIG. 9;

FIG. 11 is a view illustrating the elastic deformation of the elastic piece of FIG. 10; and

FIG. 12 is a view illustrating the probe beam assembly according to the present invention, when it is installed in a probe card .

[Best Mode]

Hereinbelow, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, it is to be noted that, when the functions of conventional elements and the detailed description of elements related with the present invention may make the gist of the present invention unclear, a detailed description of those elements will be omitted.

FIG. 3 and FIG. 4 illustrate a probe beam assembly according to the present invention, in which FIG. 3 illustrates the probe beam assembly in a completely assembled state, and FIG. 4 is an exploded perspective view of the assembled probe beam assembly.

As shown in FIG. 4, the probe beam assembly includes a plurality of probe beams 10D, two outer sockets 200 for holding the left and right edges of the probe beams 100 in slots 210 thereof in the state in which the probe beams 100 are arranged at regular intervals such that the surfaces of the probe beams 100 face each other in a facially oriented direction D, a U- shaped elastic receiving unit 300 mounted to a PCB pad or to a PCB land through soldering and holding therein connector parts provided on the lower ends of the probe beams , and two locking pins 10, which are inserted into respective locking holes 112a and 112b formed in the upper and lower parts of the probe beam bodies and maintain the facially oriented arrangement of the probe beams in the assembly. These locking pins 10 may be made of an insulating material. Further, the assembly may further include an inner socket 400, which passes through the space defined around the first edges of longitudinal rectangular holes 114 formed in the middle portions of the probe beam bodies, thus maintaining the spaced arrangement of the probe beams . In the above state , a support pin 20 is frictionally fitted into the space defined between the inner socket 400 and the second edges of the longitudinal rectangular holes 114, so that the inner socket 400 can be securely maintained in the designated space of the longitudinal rectangular holes . In the same manner as that described for the locking pins 10, the support pin 20 may be made of an insulating material .

Described in detail, as shown in FIG. 5, the probe beam 100 comprises a rectangular body 110, a contact part 120, which protrudes from the left portion of the upper end of the body 110 and comes into contact with the chip pad, and a connector part 130, which protrudes from the left portion A, middle portion B or right portion ^'C of the lower end of the body 110 and is inserted into the elastic receiving unit 300.

The locking holes 112a and 112b are formed in the upper and lower portions of the rectangular body 110 so that the locking pins 10a and 10b can be inserted into the locking holes 112a and 112b of the bodies 110. When the inner socket 400 is added to the probe beam assembly of the present invention, the longitudinal rectangular hole 114 is formed in the middle portion of the rectangular body 110 at a location between the two locking holes 112a and 112b such that the inner socket 400 can pass through the holes 114 of the rectangular bodies 110. Here, when the longitudinal rectangular hole 114 is formed in the body 110, a semicircular groove 116 is formed in the middle portion of the right edge of the longitudinal rectangular hole 114 for placing the support pin 20 therein.

As described above, in the embodiment, the connector part 130 protrudes downwards from the left, middle or right portion of the lower end of the rectangular body 110 to a predetermined length. When a plurality of probe beams 100 is arranged, the arrangement of the connector parts 130 may be selected from among the following two arrangements. The first arrangement is an oblique arrangement, in which the connector part of the first probe beam protrudes downwards from the left portion, the connector part of the second probe beam protrudes downwards from the middle portion, the connector part of the third probe beam protrudes downwards from the right portion, and the connector part of the fourth probe beam protrudes downwards from the left portion, as shown in the left-handed drawing of FIG. 6. The second arrangement is a zigzag arrangement, in which the connector part of the first probe beam protrudes downwards from the left portion, the connector part of the second probe beam protrudes downwards from the middle portion, the connector part of the third probe beam protrudes downwards from the right portion, the connector part of the fourth probe beam protrudes downwards from the middle portion, and the connector part of the fifth probe beam protrudes downwards from the left portion, as shown in the right-handed drawing of FIG. 6. The above-mentioned specific arrangements of the probe beams serve to prevent interference, which may be generated between the probe beams due to the size of the elastic receiving unit 300 arranged on the PCB.

In the embodiment, the contact part 120 protrudes from the left portion of the upper end of the rectangular body 110. However, the contact part 120 may protrude from the right portion of the upper end of the rectangular body 110. Further, in the embodiment, the contact part 120 is in direct contact with the chip pad. However, it should be understood that, in an actual implementation, the contact part 120 is in indirect contact with the chip pad through a tip formed on the distal As shown in FIG. 7, each of the outer sockets 200 is provided with a plurality of slots 210 on one surface thereof. The slots 210 are formed in the surface of the socket 200 at predetermined regular intervals and each have a predetermined depth d. The width w of each slot 210 is determined such that it corresponds to the thickness of each probe beam 100. As described above, the slots 210 of the two outer sockets 200 hold the left and right edges of the rectangular bodies 110 of the probe beams 100 therein.

FIG. 8 illustrates the inner socket 400. In the same manner as that described for the outer sockets 200, the inner socket 400 has a plurality of slots 410 in one surface thereof. However, unlike the outer sockets 400, the height h of the inner socket 400 is determined to be less than the height of the longitudinal rectangular hole 114 of the rectangular body 110 of each of the probe beams 100, such that the inner socket 400 can be smoothly inserted into the longitudinal rectangular holes 114 of the arranged probe beams 100. The outer sockets 200 and the inner socket 400 are made of the same material as that of a silicon wafer, which is the basic material of the chips used in ICs. The silicon material of the sockets 200 and 400 provides advantages in that it is possible to rearrange the probe beams 100 at adjusted intervals in the facially oriented direction D, as shown by the arrow in FIG. 4, such that the intervals correspond to variation in the pitch between the chip pads, which may be caused by heat during a probing process. Further, unlike the socket of a conventional probe beam assembly, each of the sockets according to the present invention has a simple structure. Further, an

12 oxide film (SiO₂, not shown) having a predetermined thickness may be formed on the surface of each of the outer sockets 200 and the inner socket 400 in order to insulate the sockets.

FIG. 9 and FIG. 10 illustrate the elastic receiving unit 300. As shown in the drawings, the elastic receiving unit 300 according to the present invention comprises a plurality of elastic pieces 310, each of which has a U-shaped appearance. Four locking slots 3 are formed in the left and right portions of the upper and lower parts of each of the U-shaped elastic pieces 310. The elastic receiving unit 300 further comprises four locking pins 30, which are inserted into the respective locking slots 312 of the elastic pieces 310 in the state in which the pieces 310 are arranged to face each other at regular intervals, thus integrating the elastic pieces into a single structure. In the embodiment of the present invention, the elastic pieces 310 comprise five pieces made of a conductive material. However, it should be understood that the number of elastic pieces 310 is not limited to five. In this embodiment, the locking pins 30 are made of a conductive material. However, it should be understood that the locking pins may be made of an insulating material without affecting the functionality of the present invention.

Described in detail, the elastic piece 310 comprises a lower flat part 312, which is soldered to the PCB pad or PCB land through a Surface Mount Technology (SMT) , and left and right arms 314a and 314b, which protrude upwards from the left and right portions of the flat part 312, such that the elastic piece 310 has the above-mentioned U-shaped appearance. Each of the left and right arms 314a and 314b has a rounded edge 4a, 4b on the inner edge of the upper end thereof , so that , even when the left and right arms 314a and 314b are elastically deformed, the elastic piece 310 can come into reliable contact with the opposite surfaces of the contact part 130 of the probe beam 100. When the left and right arms 314a and 314b of the elastic piece 310 are elastically deformed, the elastic deformation force is concentrated on the junction between the left and right arms 314a and 314b and the flat part 312 such that the arms may be excessively deformed, exceeding the elastic restoring force thereof. Thus, to prevent such excessive deformation of the left and right arms 314a and 314b of the elastic piece 310, in the present invention, respective concaves 5a and 5b are formed in the left side of the left arm 314a and on the right side of the right arm 314b, thus distributing the elastic deformation force from the junction to other parts. Described in detail, when an elastic deformation force is imposed on the left and right arms 314a and 314b, most of the deformation force acts on the portion B rather than on the portion A, as shown in FIG. 11, so that the elastic deformation of the portion B is greater than that of the portion A. Of course, it should be noted that the deformation of the arms is exaggeratedly illustrated in FIG. 11 for ease of description.

Hereinbelow, the insertion of the probe beam assembly according to the present invention into a probe card will be described with reference to FIG. 12.

First, to insert the probe beam assembly according to the present invention into a probe card, an insertion space is formed in the block 50 of the probe card. Further, the opposite inner surfaces of the insertion space in the block 50 are provided with respective steps 52 for supporting the outer socket 200a and 200b thereon. A PCB is placed below the lower end of the block 50 and the elastic receiving unit 300 is soldered to the PCB pad or to the PCB land. Thus, the probe beam assembly, except for the elastic receiving unit 300, is inserted into the insertion space of the probe card such that the connector parts 130 of probe beams 100 are held by the elastic receiving unit 300. Further, to prevent the probe beam assembly from being removed upwards from the probe card, an upper cover 60 is placed above the probe beam assembly. This upper cover 60 is provided with an opening through which the contact parts 120 of the probe beams 100 pass.

The insertion of the probe beam assembly into the probe card provides the following advantages compared to the conventional technique. First, the socket has a simple structure for arranging the probe beams at predetermined intervals. Second, the probe beam assembly does not require separate means for adding elasticity to the probe beams for maintaining the state of contact between the probe beams and the PCB pad. Third, because the connector parts of the probe beams are in contact with the PCB pad or PCB land through the elastic receiving unit, it is easy to remove the probe beams when replacing the probe beams with new ones. Fourth, the opposite surfaces of the connector part of the probe beam are in contact with the elastic receiving unit, thus reducing contact resistance. Fifth, the outer sockets and inner socket are made of the same material as that of the silicon wafer, and thus it is possible to rearrange the probe beams at adjusted intervals in the facially oriented direction D such that the intervals correspond to the variation in pitch between the chip pads, which may be caused by heat during a probing process. Sixth, no vertical force is imposed on the connector parts of the probe beams, except for the state in which the connector parts are in contact with the chip pads, so that it is possible to prevent undesired deformation of the probe beams.

The probe beam assembly according to the present invention may be produced through a semiconductor manufacturing process, including photolithography, etching, plating, etc.

Although the embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible^ without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

[industrial Applicability]

As described above, the probe beam assembly according to the present invention has a simple socket structure for arranging the probe beams at predetermined intervals, and does not require a separate means for adding elasticity to the probe beams for maintaining the state of contact between the probe beams and a PCB pad.

The probe beams are easily installed in and easily removed from the assembly, and the opposite surfaces of the connector part of each probe beam are in contact with the elastic receiving unit, thus reducing contact resistance compared to the conventional technique.

Further, the outer sockets and the inner socket are made of the same material as that of a silicon wafer, which is the basic material of the chips used in IC. Thus, the sockets and the chips have the same thermal coefficient of expansion, so that the probe beams can be rearranged at adjusted intervals corresponding to variation in the pitch between the chip pads.

Further, no vertical force is imposed on the connector parts of the probe beams except in for the state in which the connector parts are in contact with the chip pads, and thus it is possible to prevent undesired deformation of the probe beams despite repeated use of the probe beams over a lengthy period of time.

Claims

[CLAIMS]

[Claim l]

A probe beam assembly, comprising: a plurality of probe beams, each comprising a rectangular body, a contact part protruding from a predetermined portion of an upper end of the rectangular body, and a connector part protruding from a left, middle or right portion of a lower end of the rectangular body; a pair of outer sockets for holding left and right edges of the probe beams in slots thereof such that the probe beams are arranged with predetermined intervals defined between them; a U-shaped elastic receiving unit to be soldered to a pad or land of a PCB and holding the connector parts of the probe beams therein; and a pair of locking pins inserted into respective locking holes formed in upper and lower portions of the rectangular bodies of the probe beams in a state in which the probe beams are arranged in a space between the outer sockets while facing each other.

[Claim 2]

The probe beam assembly according to claim 1, further comprising: a longitudinal rectangular hole formed in the rectangular body of each of the probe beams at a location between the locking holes; an inner socket inserted into the probe beams through a space inside first edges of the longitudinal rectangular holes; and a support pin inserted into the probe beams through a space between the inner socket and second edges of the longitudinal rectangular holes .

[Claim 3] The probe beam assembly according to claim 2 , wherein the second edge of the longitudinal rectangular hole is provided with a semicircular groove for placing the support pin therein.

[Claim 4] The probe beam assembly according to claim 1, wherein each of the locking pins is made of an insulating material .

[Claim 5]

The probe beam assembly according to claim 2 or 3, wherein the support pin is made of an insulating material.

[Claim 6]

The probe beam assembly according to claim 1 , wherein each of the outer sockets is made of a same material as that of a silicon wafer.

[Claim 7]

The probe beam assembly according to claim 6 , wherein each of the outer sockets is coated with an oxide film on a surface thereof .

[Claim 8]

The probe beam assembly according to claim 2 , wherein the inner socket is made of a same material as that of a silicon wafer. [Claim 9]

The probe beam assembly according to claim 8, wherein the inner socket is coated with an oxide film on a surface thereof .

[Claim lθ]

The probe beam assembly according to claim 1, wherein the elastic receiving unit comprises: a plurality of U-shaped elastic pieces each having locking slots in left and right portions on upper and lower parts thereof ; and a plurality of locking pins inserted into the locking slots of the elastic pieces in a state in which the elastic pieces are arranged to face each other.

[Claim ll]

The probe beam assembly according to claim 10, wherein each of the elastic pieces comprises: a flat part to be soldered to the pad or land of the PCB; and left and right arms extending from left and right portions of the flat part.

[Claim 12] The probe beam assembly according to claim 11, wherein each of the left and right arms includes a rounded edge on an inner edge of an upper end thereof .

[Claim 13] The probe beam assembly according to claim 11 or 12, wherein the left and right arms include respective concaves in a left side of the left arm and in a right side of the right arm.

[Claim 14]

The probe beam assembly according to claim 10 or 11, wherein each of the elastic pieces is made of a conductive material .

[Claim 15]

The probe beam assembly according to claim 10, wherein each of the locking pins is ^{^}made of a conductive material .

[Claim 16] The probe beam assembly according to claim 1, wherein the connector parts of the probe beams, held by the outer sockets, are arranged in an oblique arrangement, in which the connector parts are sequentially placed at a left position, a middle position, a right position, a left position, a middle position, and a right position, or in a zigzag arrangement, in which the connector parts are sequentially placed at a left position, a middle position, a right position, a middle position, a left position, a middle position, and a right position.