阅读说明：本技术 悬臂接触探针及相应的探针头 (Cantilever contact probe and corresponding probe head ) 是由 里卡尔多·维托里 于 2019-01-16 设计创作，主要内容包括：描述了一种悬臂接触探针(31),包括包含在下倾的探针部(31b)和上倾的探针部(31c)之间的探针体(40),当接触探针被安装在悬臂探针头(30)上时,该下倾的探针部(31b)沿着预先设定的纵向轴线(HH)延伸,该纵向轴线相对于参考平面(π)倾斜,该参考平面对应于被测器件(35)的晶圆的平面,该悬臂接触探针(31)还包括：形成在下倾的探针部(31b)中的至少一个端部(31a),其相对于起始于弯曲点(PG1)并终止于适于抵靠在晶圆的被测器件(35)的接触垫(35A)上的悬臂接触探针(31)的接触尖端(36A)的纵向轴线(HH)弯曲,合适地,该探针体(40)被合适地构造成形并且包括至少一个基部(40a),其设置有上部(40d),该上部从基部(40a)开始,沿成形体(40)的纵向延伸轴线(AA)延伸,纵向延伸轴线(AA)正交于参考平面(π)和顶部(40e),该顶部连接至上部(40d)并具有比上部(40d)的直径(D1)更大的直径(D2),这些上部和顶部(40d,40e)基本上构造成T形,上部(40d)是T形的竖杆,而顶部(40e)是T形的横档。(A cantilever contact probe (31) is described, comprising a probe body (40) comprised between a declined probe portion (31b) and an upturned probe portion (31c), the declined probe portion (31b) extending along a predetermined longitudinal axis (HH) when the contact probe is mounted on a cantilever probe head (30), the longitudinal axis being inclined with respect to a reference plane (pi), the reference plane corresponding to a plane of a wafer of a device under test (35), the cantilever contact probe (31) further comprising: at least one end portion (31a) formed in the declining probe portion (31b) which is curved with respect to a longitudinal axis (HH) of a contact tip (36A) of a cantilever contact probe (31) originating at a bending point (PG1) and terminating at a contact pad (35A) of a device under test (35) adapted to rest on a wafer, suitably the probe body (40) is suitably configured shaped and comprises at least one base portion (40a) provided with an upper portion (40D) which, starting from the base portion (40a), extends along a longitudinal extension axis (AA) of the shaped body (40), the longitudinal extension axis (AA) being orthogonal to the reference plane (pi) and to a top portion (40e) connected to the upper portion (40D) and having a diameter (D2) which is larger than the diameter (D1) of the upper portion (40D), these upper and top portions (40D, 40e) being substantially configured in a T-shape, the upper portion (40d) is a T-shaped vertical bar and the top portion (40e) is a T-shaped crosspiece.)

1. A cantilever contact probe (31) comprising a probe body (40) interposed between a down-tilting probe portion (31b) and an up-tilting probe portion (31c), the down-tilting probe portion (31b) extending along a pre-set longitudinal axis (HH) tilted with respect to a reference plane (π) corresponding to a plane of a wafer of a device under test (35) when the contact probe is mounted in a cantilever probe head (30), the cantilever contact probe (31) further comprising at least one end portion (31a) formed in the down-tilting probe portion (31b) bent with respect to the longitudinal axis (HH) starting at a bending point (PG1) and ending at a contact tip (36A) of the cantilever contact probe (31), the contact tip (36A) being adapted to abut against a contact pad (35A) of a device under test (35) of the wafer, characterized in that said shaped body (40) is suitably shaped and comprises at least one base (40a) provided with an upper portion (40D) extending from said base (40a) along a longitudinal extension axis (A) of said shaped body (40), said longitudinal extension axis (A) being orthogonal to said reference plane (π) and a top portion (40e), said top portion (40e) being connected to said upper portion (40D) and having a diameter (D2) greater than a diameter (D1) of said upper portion (40D), said upper and top portions (40D, 40e) being substantially configured in a T shape, said upper portion (40D) being a stem of said T shape, and said top portion (40e) being a crosspiece of said T shape.

2. The cantilever contact probe (31) of claim 1, wherein the up-tilt probe portion (31c) is connected to the shaped body (40) at the top (40e) and the down-tilt probe portion (31b) is connected to the shaped body (40) at the base (40 a).

3. The cantilever contact probe (31) of claim 1 or 2, wherein the base (40a) of the shaped body (40) comprises at least one pair of arms (40b1, 40b2) extending from opposite portions of the base (40a) along a transverse extension axis (BB) of the shaped body (40) perpendicular to the longitudinal extension axis (AA) and parallel to the reference plane (pi).

4. The cantilever contact probe (31) of claim 3, wherein each of the arms (40b1, 40b2) comprises a respective protrusion (40c1, 40c2) extending therefrom orthogonally in the direction of the top (40e) along the longitudinal extension axis (AA) of the shaped body (40).

5. The cantilever contact probe (31) according to one or more of the preceding claims, wherein the base (40a) of the shaped body (40) has a substantially rectangular longitudinal cross-section and a maximum transverse dimension along the transverse extension axis (BB) which is greater than the diameter (D1, D2) of the upper and top portions (40D, 40 e).

6. The cantilever contact probe (31) according to one or more of the preceding claims, wherein the shaped body (40) comprising at least the base (40a), the upper portion (40d) and the top portion (40e) is made in a single piece.

7. The cantilever contact probe (31) according to one or more of the preceding claims, comprising a further bending point (PG2) defined in the inclined probe portion (31c) close to the top portion (40e) of the shaped body (40), the inclined probe portion (31c) being substantially orthogonal to the reference plane (pi) and terminating in a further contact end (36B) of the cantilever contact probe (31).

8. The cantilever contact probe (31) according to one or more of the preceding claims, wherein the shaped body (40) comprises an opening (38).

9. The cantilever contact probe (31) of claims 3 and 8, wherein the opening (38) is formed adjacent to one of the arms (40b1, 40b2), one of the arms (40b1, 40b2) having a greater extension than the other of the arms (40b1, 40b 2).

10. The cantilever contact probe (31) according to one or more of the preceding claims, further comprising at least one damping portion (50, 51) formed at the declined probe portion (31b) and/or the declined probe portion (31 c).

11. The cantilever contact probe (31) of claim 10, wherein the at least one damping portion (50) is formed along the declined probe portion (31b), preferably configured as a zoom portion connected to the tip portion (31a) and the declined probe portion (31b) at respective bending points (PG1a, PG1b), and substantially comprises four faces (50a-50d) having variable cross-sections arranged substantially as a parallelepiped and defining an empty space (50e) therein.

12. The cantilever contact probe (31) of claim 10 or 11, wherein the at least one damping portion (51) is formed at the tilt-up probe portion (31c) and is substantially configured as a spring portion connected to the shaped body (40) at the further bending point (PG2) and comprises the further contact end (36B) of the cantilever contact probe (31).

13. Cantilever probe head (30) comprising a support structure (32) adapted to accommodate a plurality of cantilever contact probes (31), a cantilever contact probe (31) protruding in a cantilever manner from said support structure (32) on a device under test (35), characterized in that each cantilever contact probe (31) is realized according to any of the preceding claims and comprises a shaped body (40) for insertion in a respective accommodation seat (41) formed in said support structure (32) and is adapted to retain said cantilever contact probe (31) in said cantilever probe head (30) in a precise manner.

14. The cantilever probe head (30) according to claim 13, wherein the support structure (32) comprises at least one first portion (32A) and one second portion (32B), preferably annular, overlapping each other and provided with a respective housing seat (41) of the shaped body (40) of each cantilever contact probe (31).

15. The cantilever probe head (30) according to claim 13 or 14, wherein the support structure (32) further comprises at least one third portion (32C) placed at least one arm (40b1, 40b2) of the shaped body (40) of each cantilever contact probe (31) and provided with a recess adapted to accommodate the at least one arm (40b1, 40b 2).

16. The cantilever probe head (30) according to claim 14, wherein the first portion (32A) of the support structure (32) comprises at least one first housing seat (41d) for the passage and retention of the upper and top portions (40d, 40e) of the shaped body (40) of the cantilever contact probe (31).

17. The cantilever probe head (30) according to claim 16, wherein the cross-section of the first housing seat (41d) is equal to the sum of the cross-sections of the upper and top portions (40d, 40e) of the shaped body (40).

18. The cantilever probe head (30) according to claim 16 or 17, wherein the first portion (32A) of the support structure (32) further comprises a pair of second housing seats (41cl, 41c2), the pair of second housing seats (41cl, 41c2) having a cross section corresponding and complementary to the cross section of the protrusion (40cl, 40c2) of the arm (40bl, 40b2) of the shaped body (40), the protrusion (40cl, 40c2) being contained in the second housing seats (41cl, 41c2) during normal operation of the cantilever probe head (30).

19. The cantilever probe head (30) according to one or more of claims 16, 17 or 18, wherein the second portion (32B) of the support structure (32) comprises a suitable opening (41e) placed at the first housing seat (41a) for the passage of the top portion (40e) of the shaped body (40).

20. The cantilever probe head (30) according to any one of claims 13 to 19, further comprising at least one support plate (37) connected to the second portion (32B) of the support structure (32) and provided with an aperture (37A) adapted to be provided with the passage of the upwardly inclined probe portion (31c) of the further contact end (36B) of the cantilever contact probe (31).

21. The cantilever probe head (30) according to claim 20, wherein the support plate (37) is made of an insulating material and is integral with the second portion (32B) of the support structure (32) or the PCB board (33).

22. The cantilever probe head (30) according to any one of claims 20 or 21, wherein the second portion (32B) of the support structure (32) provided with the support plate (37) is mounted in pressing contact with the PCB board (33), the further contact end (36B) of the cantilever contact probe (31) abutting on a contact pad (33A) of the PCB board (33) at the up-tilt probe portion (31 c).

23. The cantilever probe head (30) according to any one of claims 13 to 22, comprising a plurality of modules (60), each module being provided with a support structure (32) from which cantilever contact probes (31) protrude, the cantilever contact probes terminating with respective contact tips or ends (36A, 36B), the dimensions of the modules (60) corresponding to the dimensions of a single device under test (35).

24. The cantilever probe head (30) of claim 23, wherein the plurality of modules (60) are distributed to cover an area of the PCB board (33) equal to an area of a wafer of the device under test (35).

25. The cantilever probe head (30) according to claim 23 or 24, wherein each of the modules (60) comprises at least one contact portion (61) suitably provided with at least one hole (61A) adapted to receive at least one fixing element (62).

26. The cantilever probe head (30) according to one or more of claims 23 to 25, wherein each of the modules (60) further comprises a locating pin (63) having a suitable shape complementary to as many housings as possible.

27. The cantilever probe head (30) according to one or more of claims 23 to 26, further comprising a support structure associated with the PCB board (33) for housing the module (60), the support structure being provided with the housing for the alignment pins (63) of the module (60).

28. The cantilever probe head (30) according to one or more of the preceding claims, comprising contact probes (31) having respective second ends (31c) of different sizes to vary the distribution of the contact pads (33A) of the PCB board (33).

29. Method of assembling a plurality of cantilever contact probes (31) realized according to one of claims 1 to 12 in a cantilever probe head (30) according to one of claims 13 to 28, comprising the steps of:

inserting each cantilever contact probe (31) into the cantilever probe head (30) by inserting the upper and top portions (40d, 40e) of the shaped body (40) of each cantilever contact probe (31) into respective portions having a greater diameter than the first portion (32A) of the support structure (32A) of the cantilever probe head (30) along a first direction of movement (Dirl) orthogonal to a reference plane (π) until they pass through the opening (41e) formed in the second portion (32B) of the support structure (32) of the cantilever probe head (30), and by inserting the protrusions (40cl, 40c2) of the arms (40B1, 40B2) of the shaped body (40) into respective second receptacles (41cl, 41c2) formed in the first portion (32A) of the support structure (32) of the cantilever probe head (30) along the first direction of movement (Dirl), the respective portions having a greater diameter than the first portions (32A) of the support structure (32A) of the cantilever probe head (30) ) A larger diameter of the first accommodation seat (41d), and

fitting the cantilever contact probes (31) into the cantilever probe head (30) by moving the shaped body (40) of each cantilever contact probe (31) laterally along a second direction of movement (Dir2) orthogonal to the reference plane (pi), the upper portion (40d) being to be received in a smaller diameter portion of the first receiving seat (41d) so as to block the cantilever contact probes (31) in the cantilever probe head (30),

the height of the upper portion (40d) of the probe body (40) of each cantilever contact probe (31) is lower than or equal to the thickness of the second portion (32B) of the support structure (32), thereby ensuring mechanical coupling between the shaped body (40) and the support structure (32) of the cantilever probe head (30).

30. The assembly method according to claim 29, wherein said step of inserting each of said cantilever contact probes (31) into said cantilever probe head (30) comprises: -inserting its upturned portions (31c) into respective first T-shaped housing seats (41D) at the crosspieces of the T, of a size equal to the diameter (D2) of the top portion (40e) of the shaped body (40) of each cantilever contact probe (31), and subsequent lateral displacement for fitting the upper portion (40D) of the shaped body (40) at the stem of the T, of a size equal to the diameter (D1) of the upper portion (40D).

Technical Field

The invention relates to a cantilever contact probe and a corresponding probe head.

The present invention relates particularly, but not exclusively, to a probe head adapted to be mounted in a test apparatus for electrical testing of devices integrated on a semiconductor wafer. Although the following description is made with reference to this field of application, the purpose is only to simplify the explanation.

Background

As is known, a probe tip is essentially a device adapted to electrically connect contact pads of a plurality of microstructures with corresponding channels of a testing apparatus for conducting a test thereof.

Tests performed on integrated circuits are used early in the production phase to detect and isolate defective circuits. It is common to use probe heads to electrically test the circuits integrated on the wafer before they are diced and assembled into packages containing chips.

A widely used is the so-called "cantilever" probe head, i.e. a probe head comprising a plurality of probes projecting in a cantilever manner from a suitable support.

Specifically, as schematically illustrated in FIG. 1, a probe head or cantilevered probe head 10 having cantilevered probes generally comprises a support ring 11, for example, made of aluminum, ceramic or other suitable material, associated with an integrated circuit board or PCB 12. A support 13, generally made of resin, is associated with the support ring 11 and is suitable for incorporating a plurality of movable contact elements or contact probes 14, the movable contact elements or contact probes 14 generally consisting of special alloy wires having good electrical and mechanical properties and projecting from the resin support 13 at a suitable angle α with respect to a reference plane, in particular the plane of a device under test 15, such as a wafer of integrated circuits tested by those contact probes 14. To this end, the contact probe 14 is in fact represented as a cantilever probe or a cantilever probe.

Specifically, the cantilever contact probe 14 has an end portion commonly referred to as a hook 14a, the hook 14a being bent at a suitable angle relative to the probe body 14 b. The hook 14a terminates in a contact tip 16A, which contact tip 16A rests on a contact pad 15A of the device under test 15. Thus, the hook 14a is bent at a bending point 14c defined between the probe body 14b and the hook 14a such that the hook 14a is substantially orthogonal to the plane of the device under test.

Thus, by using the partial reference of fig. 1, the device under test 15 is arranged horizontally and the hook 14a is arranged vertically, with the result that the probe body 14b is inclined at an angle α with respect to the plane of the device under test 15.

By pressing the cantilever probe head 10 onto the device itself, a good connection between the contact tips 16A of the contact probes 14 of the cantilever probe head 10 and the contact pads 15A of the device under test is ensured, the contact probes 14 being bent vertically in the opposite direction with respect to the movement of the device towards the cantilever probe head 10.

Specifically, as occurs during normal testing operation of a wafer of integrated circuits, when the device under test 15 is moved vertically against the hook 14a, the respective contact probe 14 is bent in a direction substantially orthogonal to the plane of this device under test 15, and thus its bending point 14c moves along an arc of a circle.

The first probe portion 18a, which projects relative to the resin support 13 in the direction of the device under test 15, thus defines a working arm for the connection probe 14 in its vertical bending movement, and is generally denoted by the term "free length".

During contact with the contact pads 15A of the device under test 15 and its upward movement or "over travel" beyond the preset contact point, the hook shape of the cantilever contact probe 14 causes the hook 14a to move over the contact pads 15A in a direction determined by the geometry of the probe head-device under test system, ensuring a so-called scrub (scrub) of the contact tip 16A of the cantilever contact probe 14 over those contact pads 15A.

Each cantilever contact probe 14 further comprises a second probe portion 18B, the second probe portion 18B projecting from the resin support 13 in the direction of the PCB12 and terminating at the other end 16B of the contact probe 14, the other end 16B being soldered to the PCB12, typically at a solder joint 17.

To form this welding point, the second probe portion 18b must have an appropriate size, particularly on the order of centimeters, and in particular, the welding point 17 is formed manually, probe by probe, usually using a microscope and tweezers.

It is therefore necessary to provide some space to form this solder joint 17 and thus for the probe portion 18b to project toward the PCB board 12; in particular, as the overall size of the cantilever probe head 10 increases due to the space, space must be provided around the support ring 11 to establish individual contacts, i.e., individual solder joints 17 for each contact probe 14.

It should be particularly remembered that when the size of the device under test 15 in the form of a chip or die is about 5mm, the length of the second probe portion 18b should have to be an even number of centimeters (at least 10mm ═ 1cm, i.e. twice the die size) in order to form the weld 17.

It should also be noted that the force that each contact probe 14 exerts on a contact pad 15A of a device 15 under test depends on many factors, among which are mainly: the kind of material of which the contact probe 14 is made, the shape of the contact probe 14, the angle a at which the contact probe 14 is arranged, the length of the first protrusion 18a or its free length, and the movement or excessive movement of the device under test 15. The factor also defines the extent to which the contact hook 14a slides or rubs over the contact pad 15A.

The use of a support ring 11, also well known in the art, is generally made of aluminum, ceramic or other suitable material, having different shapes according to the set of contact pads 15A on which the test has to be performed, so as to make the values of the free length of the contact probes 14 uniform and therefore of the force applied by the contact probes 14 to the pads themselves, thus guaranteeing the uniformity of consumption and performance of the entire cantilever probe head 10.

Alternatively, it is also known to produce probe heads with a vertical technique, as schematically shown in fig. 2.

Such a vertical probe head, indicated as a whole with 20, substantially comprises a plurality of contact probes 21, generally consisting of special alloy wires with good electrical and mechanical properties and held by at least one pair of supports or guides, substantially plate-shaped and parallel to each other and to the plane defined by the device under test 25, as indicated above, the device under test 25 being generally in the form of a wafer of integrated circuits, in which case the contact probes 21 extend in a direction substantially orthogonal to the plane of the device under test 25.

In particular, the vertical probe head 20 comprises at least one lower plate-like support (generally indicated as "lower die" or even simply as lower guide 22) and one upper plate-like support (generally indicated as "upper die" or even simply as upper guide 23) having guide holes 22A and 23A, respectively, through which at least one contact probe 21 slides.

The probe and the guide are housed inside a casing or shell 24 and are placed at a distance from each other to form a free area or aperture 24A for contact with the movement or possible deformation of the probe 21; for this reason, the region 24A is also denoted as a bending region.

Each contact probe 21 terminates in an end portion having a contact tip 21A, the contact tip 21A being intended to abut against a contact pad 25A of a device under test 25 to establish a mechanical and electrical contact between said device under test 25 and a testing apparatus (not shown), in which case the vertical probe head 20 of the testing apparatus forms an end element.

The term "contact tip" here and in the following refers to the area or extent of the end of a contact probe intended to make contact with a device or test equipment to be tested, which area or extent does not have to be sharp.

Sometimes, the contact probe 21 is fixedly constrained to the head itself at the upper guide 23: they are referred to as probe heads with blocked probes.

More frequently used, however, are probe heads with probes that are not blocked fixedly, but that are held in an interface (interfaced) with a so-called plate (in case by micro-contact plates provided with respective contact pads): they are referred to as probe heads with non-blocking probes. This micro-contact plate is commonly referred to as a space transformer because, in addition to the contact probes, it allows to spatially redistribute the contact pads formed on its opposite faces and connected by suitable metal tracks (metaltracks) inside the space transformer, so that it pulls apart the distance limit between the pad centers with respect to the distance limit allowed on the device under test. For ease of illustration, fig. 2 only shows the contact pads of the space transformer in contact with the contact probes.

In particular, in this case, with reference to fig. 2, the contact probe 21 has a further contact tip, denoted contact head 21B, which faces a pad 26B of the plurality of contact pads of the space transformer 26. Good electrical contact between the probes 21 and the space transformer 26 is always ensured by virtue of the contact heads 21B of the contact probes 21 being pressed against the contact pads 26B of the space transformer 26, the space transformer 26 being intended to be connected to a PCB board (not shown).

In the example of fig. 2, the contact probes 21 also comprise pre-deformed portions 21C, which pre-deformed portions 21C are adapted to assist bending of those probes during pressure contact of the probe head onto the device under test 25.

Thus, in this case, the contact heads 21B of the contact probes 21 are floating rather than being blocked, they making pressure contact with the contact pads 26B of the space transformer 26.

Furthermore, the space transformer 26 may be produced by different methods, for example according to the so-called direct attachment (directtatach), which provides for obtaining the space transformer directly from the PCB board to which the space transformer is intended to be connected, or according to the wired technology (wired technology), wherein the space transformer is physically isolated from the PCB board and connected to the PCB board by means of connecting wires.

The main advantage of the vertical technique is that devices with close contact pads, i.e. very narrow pitches, and full array type pitches, i.e. devices with pads arranged on all 4 sides, can be detected.

In fact, because the tips have a tapered shape in cantilever technology, cantilever probe heads are successful in pitch, especially using a multi-layer structure for the respective support ring and contacting pads that are very close (i.e., have a reduced pitch) with just a tapered tip pattern.

In the vertical technique, the distance between the pads is limited by the diameter of the probe and the ability to approximate guide holes formed in the guide. Here and in the following, the definition of "distance between pads" or pitch denotes the distance between the centers of symmetry of these pads.

With current technology, tips produced using vertical technology cannot successfully achieve the pitch achieved with cantilever tips.

In contrast, a probe head produced with the vertical technique has the following advantages with respect to a cantilever head: the die was successfully contacted with high parallelism and had contact tips that "replicated" the distribution of pads on the device under test.

With a probe head produced by cantilever technology, it is instead necessary to allow some space for the formation of the solder joints, and it is not possible to perform simultaneous testing of several parallel dies, even though known techniques may remedy such drawbacks and achieve higher parallelism than a single test, for example using a step of offsetting the probes, or testing two dies close to each other using diagonally arranged probes, without however achieving the performance of the perpendicular technology.

Furthermore, it should be kept in mind that the problem of positioning the contact probes of the cantilever contact probe head is linked to the use of a resin support which performs the desired retention of the probes themselves, but introduces undesired displacements and forces the designer of the cantilever probe head to consider suitable modifications when he determines the positions of the different probes therein, which obviously limits the reduction of the distance between these probes, in particular between their contact tips, and therefore the distance between the contact pads of the devices which can be tested by means of this probe head.

The technical problem underlying the present invention is that of providing a cantilever probe and a corresponding probe head having structural and functional characteristics capable of overcoming the limitations of the probe heads produced according to the prior art, in particular a probe capable of precisely immobilizing the inside of the probe head.

Disclosure of Invention

The solution idea underlying the present invention is to modify the structure of the cantilever probe so that it has at least one shaped probe body, to be mounted in a seat with a complementary shape suitably corresponding and formed in a rigid support, without the use of a retaining resin.

Based on the technical scheme, the technical problem is solved by the following cantilever test probe, wherein the cantilever test probe comprises: a probe body interposed between a declined probe portion and an upwardly declined probe portion, the declined probe portion extending along a predetermined longitudinal axis that is inclined with respect to a reference plane corresponding to a plane of a wafer of a device under test when a contact probe is mounted on a cantilever probe head, the cantilever contact probe further comprising: at least one end portion formed in a downwardly inclined probe portion, which is curved with respect to a longitudinal axis starting at a bending point and ending at a contact tip of a cantilever contact probe adapted to rest on a contact pad of a device under test of a wafer, characterized in that the probe body is suitably configured to comprise at least one base portion provided with an upper portion, which extends from the base portion along a longitudinal extension axis of a shaped body (shaped body), which is orthogonal to a reference plane and a top portion, which is connected to the upper portion and has a larger diameter than the diameter of the upper portion, the upper portion and the top portion being substantially shaped to form a T-shape, the upper portion being a stem of the T-shape and the top portion being a crosspiece of the T-shape.

More specifically, the invention includes the following additional and optional features, which may be used alone or in combination if desired.

According to another aspect of the invention, the upwardly inclined probe portion may be connected to the forming body at the top portion and the downwardly inclined probe portion may be connected to the forming body at the base portion. Further, the base of the forming body may include at least one pair of arms extending from opposite portions of the base along a laterally extending axis of the forming body that is orthogonal to the longitudinally extending axis and parallel to the reference plane.

In particular, each arm may comprise a respective protrusion extending orthogonally from the respective arm in a top direction along a longitudinal extension axis of the shaped body.

According to another aspect of the invention, the base of the shaped body may have a substantially rectangular longitudinal section and a maximum transverse dimension along the transversely extending axis which is greater than the diameter of the upper part and the top part.

Furthermore, the shaped body comprising at least a base, an upper part and a top part may be made in one piece.

According to another aspect of the invention, the cantilever contact probe may include an additional bending point defined in the upturned probe portion proximate the top of the forming body. The tilted-up probe portion is substantially orthogonal to the reference plane and terminates at the other contact end of the cantilever contact probe.

According to yet another aspect of the invention, the shaped body may comprise an opening.

In particular, the opening may be formed close to one of the arms, which extends over a larger extent than the other of the arms.

Suitably, the cantilever contact probe may further comprise at least one damping portion formed at the declined probe portion and/or the declined probe portion.

In particular, the at least one damping portion may be formed along the declined probe portion, preferably configured as a pantograph (pantograph portion) connected to the tip and the declined probe portion at respective bending points, and the pantograph substantially comprises four faces arranged substantially as a parallelepiped and defining an empty space therein.

At least one damping portion may also be formed at the upwardly inclined probe portion and configured substantially to connect to the spring portion of the shaped body at a further bending point, and the spring portion may comprise a further contact end of the cantilever contact probe.

The problem is also solved by the following cantilever probe head: the cantilever probe head comprises a support structure adapted to receive a plurality of cantilever contact probes projecting in a cantilever manner from the support structure on the device under test, characterized in that each cantilever probe is produced as described above and comprises a shaped body inserted in a suitable housing seat formed in the support structure and adapted to hold the cantilever contact probes in a precise manner in the cantilever probe head.

According to another aspect of the invention, the support structure may comprise at least one first and one second portion, preferably annular, mutually superposed and provided with respective housing seats of the shaped body of each cantilever contact probe.

According to yet another aspect of the invention, the support structure may further comprise at least one third portion placed at least one arm of the shaped body of each contact probe and provided with a notch adapted to accommodate the at least one arm.

In particular, the first portion of the support structure may comprise at least one first housing seat for the passage and retention of the upper portion and the top portion of the shaped body of the cantilever contact probe.

Furthermore, the first containing seat may have a cross section equal to the sum of the cross sections of the upper portion and the top portion of the shaped body.

More particularly, the first portion of the support structure may also comprise a pair of second housing seats having a cross section corresponding to and complementary to the cross section of the projections of the arms of the shaped body, these projections being housed in the second housing seats during normal operation of the cantilever probe head.

Furthermore, the second portion of the support structure may comprise a suitable opening placed at the first housing seat for the passage of the top of the shaped body.

According to another aspect of the invention, the cantilever probe head may further comprise at least one support plate connected to the second portion of the support structure and provided with an aperture adapted for passage of an upturned probe portion having a further contact end of said cantilever contact probe.

More particularly, the support plate may be made of an insulating material and be made in one piece with the second part of the support structure or with the PCB board.

According to another aspect of the invention, the second part of the support structure provided with the support plate may be mounted in pressure contact with the PCB plate, the contact probes abutting on the contact pads of the PCB plate at the further contact ends of the upwardly inclined probe portions.

According to yet other aspects of the invention, a cantilever probe head may include a plurality of components, each component providing a support structure from which cantilever contact probes protrude, each component terminating in a respective contact tip or end, the components having dimensions comparable to the dimensions of a single device under test.

According to this aspect of the invention, the plurality of components may be distributed so as to cover an area of the PCB board equal to an area of the wafer of devices under test.

More particularly, each of these assemblies may comprise at least one contact portion suitably provided with at least one hole suitable for housing at least one fixing element.

Each of these assemblies may also include a locating pin having a suitable shape that is complementary to the plurality of housings.

In addition, the cantilever probe head may further comprise a support structure associated with the PCB board for receiving the assembly, the support structure being provided with a housing for the alignment pins of the assembly.

Finally, the cantilever probe head may include contact probes having respective upturned probe portions having different dimensions to vary the distribution of the contact pads of the PCB board.

Finally, the problem is solved by a method of assembling a plurality of cantilever contact probe sets in a cantilever probe head, the production of which is as described above, the method comprising the steps of:

inserting each of the cantilever contact probes into the cantilever probe head by inserting an upper portion and a top portion of the shaped body of each of the cantilever contact probes into respective portions in a first direction of movement orthogonal to the reference plane until they pass through openings formed in a second portion of the support structure of the cantilever probe head, and by inserting projections of arms of the shaped body into respective second receptacles formed in a first portion of the support structure of the cantilever probe head in the first direction of movement, the respective portions having a diameter greater than a diameter of the first receptacles, the first receptacles being formed in the first portion of the support structure of the cantilever probe head, and

mounting the cantilever contact probes into the cantilever probe head by laterally moving the shaped body of each cantilever contact probe in a second direction of movement orthogonal to the reference plane, the upper portion to be received in the smaller diameter portion of the first receiving nest to block the cantilever contact probes in the cantilever probe head,

the height of the upper portion of the probe body of each cantilever contact probe is less than or equal to the thickness of the second portion of the support structure to ensure mechanical coupling between the forming body and the support structure of the cantilever probe head.

According to another aspect of the present invention, the step of inserting each cantilever contact probe into a cantilever probe head may comprise: its upsets are inserted into the respective first T-shaped receptacles at the rungs of the T, which are equal in size to the diameter of the top of the shaped body of each of the cantilever contact probes, and are then laterally displaced for mounting the upper portion of the shaped body at the stem of the T, which is equal in size to the diameter of the upper portion.

Brief description of the drawings

In the drawings:

FIG. 1 schematically illustrates a cross-sectional view of a cantilever probe head implemented according to the prior art.

Figure 2 schematically shows a cross-sectional view of a vertical probe head implemented and produced according to the prior art.

FIG. 3A schematically illustrates a cross-sectional view of an embodiment of a cantilever contact probe and a cantilever probe head, implemented according to the present invention.

Figures 3B and 3C schematically illustrate cross-sectional views of alternative embodiments of cantilever contact probes implemented in accordance with the present invention.

Figures 4A-4C schematically illustrate cross-sectional views of alternative embodiments of details of a cantilever contact probe implemented in accordance with the present invention.

Figures 5A-5C schematically illustrate top plan views of alternative embodiments of details of a cantilever probe head implemented according to the present invention.

Figures 6A and 6B schematically illustrate cross-sectional views of another alternative embodiment of a cantilever contact probe implemented in accordance with the present invention.

FIG. 7 schematically illustrates a cross-sectional view of the cantilever probe head of FIG. 6B including at least one pair of contact probes.

FIG. 8 schematically illustrates a top plan view of a cantilever probe head according to the present invention.

Figures 9A and 9B schematically show respective plan and side views of a probe head produced in a modular manner according to the invention.

Detailed description of the preferred embodiments

Referring to the drawings and in particular to FIG. 3A, a probe head in cantilever technology is described. The tip in cantilever technology is implemented according to the present invention, hereinafter referred to as a cantilever tip, and is generally designated 30.

It is to be noted that the figures are schematic representations of a probe head according to the invention and are not drawn to scale, but are drawn so as to emphasize the important features of the invention. Furthermore, in the figures, the various elements are shown in schematic form, the shape of which may vary according to the desired application. It should also be noted that in the drawings, like reference numerals indicate elements that are identical in shape or function. Finally, the different aspects of the invention shown by way of example in the drawings may obviously be combined with each other and interchanged from one embodiment to another.

More specifically, the cantilever probe head 30 comprises a plurality of movable contact elements or contact probes 31 projecting in a cantilever manner from a support structure 32, the support structure 32 being adapted to hold the cantilever contact probes 31 according to a predetermined distance relationship between each other and being associated with an integrated circuit board or PCB board 33. In the example of FIG. 3A, only one cantilever contact probe 31 is depicted for ease of illustration. Each cantilever contact probe 31 is typically made of a special alloy wire with good electrical and mechanical properties suitable for ensuring good electrical contact with the test equipment (not shown) and with the device under test 35 through the PCB board 33.

Suitably, the support structure 32 of the cantilever contact probe 31 comprises a first portion 32A and a second portion 32B, respectively, which are for example annular, overlap each other and are provided with respective housing seats of the contact probe body, suitably configured, as will be better clarified below. In the embodiment of fig. 3A, the first and second portions 32A, 32B of the support structure 32 are substantially plate-shaped.

More specifically, the first portion 32A is placed facing the device under test 35, i.e., downward according to the partial reference in fig. 3A, and the second portion 32B is placed facing the PCB board 33, i.e., upward according to the partial reference in fig. 3A.

The first and second portions 32A and 32B of the support structure 32 described above may be made of the same or different materials selected from among the materials used in the art for fabricating cantilever probe tips, particularly selected from among aluminum, ceramic, or other suitable materials.

With known cantilever probe heads, the cantilever contact probes 31 project from the support structure 32 along a longitudinal axis HH inclined at an angle α with respect to a reference plane pi, in particular the plane of a device 35 under test, such as a wafer of integrated circuits under test, each contact probe 31 projecting like a fishing rod, i.e. in a cantilever manner, above the wafer. In particular, the angle α may have a value of 0 to 65 degrees, preferably 8 degrees.

Suitably, the cantilever contact probe 31 has an end portion commonly referred to as a hook 31a that is curved relative to a declined probe portion 31b extending along the longitudinal axis HH; in particular, it is preferred that the hook 31a is bent to be substantially orthogonal to the reference plane pi of the device under test 35 and therefore it forms an angle with the declined probe portion 31b equal to the angle α plus a right angle, i.e. having a value between 90 and 155 degrees, preferably 98 degrees.

The hook 31a terminates in a contact tip 36A of the cantilever contact probe 31, which contact tip 36A is adapted to rest on a contact pad 35A of the device under test 35.

As is done in the prior art, it is emphasized here that the term "tip" means an end region or area that contacts the probe but is not necessarily sharp.

In particular, the hook 31a is bent at a bend point PG1 defined by the declined probe portion 31b, the declined probe portion 31b projecting in the direction of the device under test 35 when the cantilever contact probe 31 is mounted in the cantilever probe head 30; thus, the downtilt probe portion 31b defines the working arm of the cantilever contact probe 31 in its vertical bending motion during the time that the cantilever probe head 30 contacts the device under test 35 in its normal operation (i.e., the contact tip 36A of the cantilever contact probe 31 contacts the contact pad 35A of the device under test 35), and its length is generally referred to by the term "free length".

In fact, as explained in the prior art, by pressing the cantilever probe head 30 against the device under test 35, a good connection between the contact tip 36A of the cantilever contact probe 31 and the contact pad 35A of the device under test 35 is ensured, during which the cantilever contact probe 31 is subjected to a bending in the opposite direction with respect to the movement of the device itself in the direction orthogonal to the reference plane pi (i.e. the direction Z as shown in fig. 3A).

In particular, when the device under test 35 moves against the hook 31a, the respective cantilever contact probe 31 bends and its bending point PG1 travels along an arc of a circle, while the contact tip 36A, where the hook 31a ends, moves along the reference plane pi, in particular on the respective contact pad 35A, ensuring the so-called scrubbing of the surface of said pad.

Furthermore, the hooks 31a have a tapered shape, which may be used, in particular in multilayer structures, to contact pads 35A of the device under test 35, which contact pads are very close to each other, i.e. have a small pitch.

As is well known to those skilled in the art, the "pitch" or distance between contact pads refers to the distance between the respective centers, i.e., the centers of symmetry of the associated pads.

When the cantilever contact probes 31 are mounted in the cantilever probe head 30, each cantilever contact probe 31 further comprises an upwardly inclined probe portion 31c projecting from the support structure 32 in the direction of the PCB board 33. The upper inclined probe portion 31c also projects from the support structure 32 along a longitudinal axis KK which is substantially coincident with or parallel to the axis HH of the lower inclined probe portion 31 b.

The lower inclined probe portion 31b continues to contact the PCB board 33 upwardly, which is suitably connected to the PCB board 33 by a solder joint 34 in the example of fig. 3A.

Suitably, the cantilever contact probe 31 according to the present invention further comprises a body 40, the body 40 connecting the declined probe portion 31b and the declined probe portion 31c and being suitably configured to form a fit with the support structure 32, thereby obtaining a desired and accurate positioning of the cantilever contact probe 31 within the cantilever probe head 30 without the use of conventional resin supports, as will be explained below.

More specifically, the shaped body 40 comprises at least one base 40a, the base 40a being provided with at least one pair of arms 40b1, 40b2, the arms 40b1, 40b2 extending from opposite portions of the base 40a along a transversal extension axis BB of the shaped body 40, in particular parallel to a reference plane pi defined by the device under test 35, i.e. extending in a reference direction X according to fig. 3A; the arms 40b1, 40b2 are also provided with respective projections 40c1, 40c2, the projections 40c1, 40c2 extending orthogonally from the arms 40b1, 40b2 along a longitudinal extension axis a of the shaped body 40, in particular orthogonal to the reference plane pi, i.e. in the direction Z according to the reference of fig. 3A.

When the cantilever contact probe 31 is placed in the cantilever probe head 30 and held by the support structure 32, the pair of arms 40b1, 40b2 are intended to abut against a face of the first portion 32A of the support structure 32, in particular the face facing the device under test 35, and the projections 40c1, 40c2 are intended to be received in suitable receiving seats arranged in the first portion 32A, as shown in fig. 3A, which will be better clarified below.

Suitably, the shaped body 40 further comprises an upper portion 40D and a top portion 40e, the upper portion 40D extending from the base portion 40a along a longitudinal extension axis a of the shaped body 40, perpendicular to the reference plane pi, towards the PCB board 33, i.e. in the direction Z according to the reference of fig. 3A, the top portion 40e being connected to the upper portion 40D and having a diameter D2 greater than the diameter D1 of the upper portion 40D. The upper portion 40d and the top portion 40e are configured substantially to form a T-shape, with the upper portion 40d being a rod and the top portion 40e being a cross-piece of the T-shape.

The base 40a of the shaped body 40 has a substantially rectangular longitudinal section and a maximum transverse dimension along its transversely extending axis BB, which is greater than the diameter D1 of the upper portion 40D and the diameter D2 of the top portion 40 e.

In a preferred embodiment, the various parts of the shaped body 40, in particular the base 40a, the arms 40b1, 40b2 with the projections 40c1, 40c2, the upper part 40d and the top part 40e are made in one piece.

Suitably, the upper inclined probe portion 31c is connected to the forming body 40 at its top 40e and the lower inclined probe portion 31b is connected to the forming body 40 at its base 40 a.

The cantilever probe head 30 thus comprises a suitable housing seat, indicated as a whole with 41, of a shaped body 40 formed in the support structure 32.

More specifically, the support structure 32 comprises at least one first housing seat 41d and a pair of second housing seats 41cl, 41c2, the first housing seat 41d being formed in its first portion 32A and having a cross section equal to the sum of the cross sections of the upper portion 40d and of the top portion 40e of the shaped body 40 of the cantilever contact probe 31, as will be explained in more detail below, 41cl, 41c2 being always formed in its first portion 32A, in particular on its face facing the device under test 35, and having a shape corresponding and complementary to the projections 40c1, 40c2 of the arms 40b1, 40b2 of the shaped body 40 of the cantilever contact probe 31.

Similarly, the second portion 32B of the support structure 32 comprises a suitable opening 41e placed at the first housing seat 41a for the passage of the shaped body 40, in particular of the top 40e thereof.

Thus, the shaped body 40 can correctly hold the cantilever contact probe 31 within the cantilever probe head 30, in particular the support structure 32 thereof, the projections 40c1, 40c2 of the arms 40B1, 40B2 inserted into the second housing seats 41c1, 41c2 preventing the cantilever contact probe 31 from moving in a direction parallel to the reference plane pi, i.e. in the direction X of the reference according to fig. 3A, the top portion 40e abutting against the second portion 32B, since its diameter D2 is greater than the diameter D1 of the lower upper portion 40D, thereby preventing the cantilever contact probe 31 from moving in a direction orthogonal to the reference plane pi, i.e. in the direction Z of the reference according to fig. 3A.

According to an alternative embodiment, schematically illustrated in fig. 3B, the cantilever contact probe 31 further comprises a further bending point PG2 defined in the inclined upper probe portion 31c, preferably at its beginning, i.e. close to the top portion 40e, so that said inclined upper probe portion 31c is substantially orthogonal to the plane of the PCB board 33 parallel to the reference plane pi, to form a further end portion of the cantilever contact probe 31, which ends with a further end 36B, which further end 36B forms a further contact tip of the cantilever contact probe 31 on the PCB board 33.

Thus, when the cantilever contact probe 31 is pushed against the PCB 33, particularly during assembly of the cantilever probe head 30, the up-tilt probe portion 31c also defines a working arm for the cantilever contact probe 31, similar to when the down-tilt probe portion 31b is in compressive contact on the device under test 35, i.e., during normal operation of the cantilever probe head 30.

It should be noted that the other end 36B of the contact probe 31 can in this case function like a contact head of a vertical contact probe, as described in the prior art. Suitably, according to this alternative embodiment, as will be described in more detail below, since the cantilever contact probe 31 is provided with another bending point PG2, and thus with an upwardly inclined probe portion 31c orthogonal to the PCB board 33, a contact strategy between the probe and the PCB typical of the vertical technique can be employed.

More specifically, suitably, according to the present invention, the cantilever probe head 30 may further comprise a support plate 37 in this case, the support plate 37 being provided at the other end 36B of the cantilever contact probe 31 with a hole 37A adapted for the passage of the upwardly inclined probe portion 31 c.

The support plate 37 may be made of a suitable insulating material, such as ceramic or other suitable material, and is connected or made in one piece with the second portion 32B of the support structure 32, for example by welding, the support structure 32 being suitably configured such that at least one portion abuts the PCB board 33 at the support plate 37, as shown in fig. 3B.

The support plate 37 may be fixed to the PCB board 33.

It should be noted that advantageously, according to the invention, the other end 36B of the contact probe 31 thus directly contacts the PCB 33, in particular a suitable contact pad 33A realized thereon, the respective upward-inclined probe portion 31c being suitably guided by the hole 37A of the support plate 37.

Thus, due to the configuration of the contact probe 31 provided with the other bend point PG2 and the upturned probe portion 31c abutting the PCB 33, the solder joint 34 of the cantilever contact probe 31 to the PCB 33 can be eliminated and contact with the PCB 33 can instead be made by the other end 36B of the probe at the upturned probe portion 31 c.

In other words, the cantilever contact probe 31, and more specifically its upturned portion 31c, slides in the support plate 37 provided with a hole 37A, in the same way as the contact head of the probe in the vertical technique, and it is provided with another end 36B suitable for contact by pressure on the contact pad 33A of the PCB 33.

It should also be noted that the cantilever contact probe 31 has a suitable end or hook 31a which tapers and bends from a downwardly inclined probe portion 31b over a corresponding contact pad 35A of the device under test 35, the cantilever contact probe 31 being supported by the support structure 32 and retained at its forming body 40 by engagement therewith, thereby leaving a cantilever base structure for both the probe and the head as a whole.

In this case, the cantilever probe head 30 is connected to the PCB board 33 by a so-called "direct attach" method similar to the vertical technique.

Furthermore, in its operation, the hook 31a and the upturned probe portion 31c may be comparable to two springs placed at opposite ends of the cantilever contact probe 31, i.e., at ends adapted to abut respective contact pads when abutting the device under test 25 and contacting the PCB board 33 during normal operation of the cantilever probe head 30.

According to another alternative embodiment, schematically illustrated in fig. 3C, the cantilever contact probe 31 further comprises at least one opening 38 at its forming body 40, which opening 38 is substantially slot-shaped and arranged along an axis parallel to the transversely extending axis BB of the forming body 40, enabling to increase the elasticity of the forming body 40 itself, in particular during the operation of the cantilever probe head 30, i.e. during the movement of the hook 31a and the respective declined probe portion 31b of the cantilever contact probe 31 contained therein, during the press-contact on the device under test 35. Preferably, the opening 38 is placed in a portion of the shaped body 40 close to the first portion 32A against which the shaped body 40 abuts, in particular its base 40a, i.e. close to the interface between the shaped body 40 and the first portion 32A of the support structure 32. Preferably, the opening 38 is disposed proximate the more extended arm 40b 2.

In addition, the cantilever probe head 30 can include at least one third portion 32C of the support structure 32 that is disposed at least one arm, such as the arm 40b1 in the example of FIG. 3C, and suitably provided with a recess adapted to receive the arm 40b 1. In particular, the arm 40B1 is thus confined between the second and third portions 32B, 32C of the support structure 32, which prevents movement of the arm 40B 1.

A third portion 32C may also be formed at the other arm 40b2 or at both arms 40b1 and 40b 2.

Suitably, the third portion 32C of the support structure 32 is used to keep the contact probes 31, in particular the arms 40b1, 40b2 thereof, in contact, which prevents any possible falling of the material in case of breakage, thus ensuring the safety of the wafer being tested, which avoids the risk of some kind of material impact that might damage it.

Finally, it is possible to provide the projections 40cl, 40c2 of the arms 40b1, 40b2 with suitable notches 40fl, 40f2, the notches 40fl, 40f2 being formed at the portions of the projections 40cl, 40c2 housed in the respective housing seats 41c1, 41c2 and being able to increase the elasticity of the projections 40c1, 40c 2.

Different embodiments of forming body 40 are schematically illustrated in fig. 4A-4C.

In particular, in the example of fig. 4A, the shaped body 40 has arms 40B1, 40B2, arms 40B1, 40B2 having respective lengths L1, L2 equal to each other, whereas in the examples of fig. 4B and 4C, the arms 40B1, 40B2 have lengths L1, L2 different from each other, measured from the base 40 a.

In fig. 5A-5C schematically showing the housing seats 41 of the protuberances 40C1, 40C2 of the arms 40b1, 40b2 of the embodiment of the shaped body 40 of fig. 4A-4C, the second housing seats 41C1, 41C2 are placed at respective distances E1, E2 with respect to the first housing seat 41d, corresponding to the different lengths of the protuberances 40cl, 40C2 of the shaped body 40, measured from the top 40E.

The first housing seat 41d has a suitable T-shape, with a stem having a shape and dimensions corresponding and complementary to those of the cross section of the upper portion 40d of the shaped body 40, and a crosspiece having a shape and dimensions corresponding and complementary to those of the cross section of the top portion 40e, so that the first housing seat 41d has a shape combined by the cross sections of the upper portion 40d and the top portion 40 e.

It should be noted that an accurate positioning and a correct holding of the cantilever contact probe 31 in the support structure 32 of the cantilever probe head 30 comprising it can thus be obtained in a simple and straightforward manner. In particular, the upper portion 40d and the top portion 40e of the shaped body 40 of the cantilever contact probe 31 are inserted into the supporting structure 32, in particular into the first portion 32A of the supporting structure 32 at the crosspiece of the first housing seat 41d along a first movement direction Dir1, Dir1 being orthogonal to the reference plane pi, as shown in fig. 4A, until the opening 41e at the first housing seat 41d, the projections 40cl, 40c2 of the arms 40b1, 40b2 enter and block in the respective second housing seats 41c1, 41c2 and are therefore moved laterally along a second movement direction Dir2, Dir2 being orthogonal to the reference plane pi, as shown in fig. 5A, so as to house the upper portion 40d in the stem of the first housing seat 41d and block the movement of the cantilever contact probe 31.

Suitably, the height of the upper portion 40d of the shaped body 40 is less than or equal to the thickness of the second portion 32B, so that there is a mechanical coupling between the shaped body 40 of the cantilever contact probe 31 and the ceramic support structure 32 of the cantilever probe head 30.

Thus, the cantilever contact probe 31 can be mounted in the cantilever probe head 30 by inserting its upturned portion 31c into the corresponding first T-shaped receptacle 41D at the crosspiece of the T-shape, which is sized to be equal to the diameter D2 of the top portion 40e, and then laterally moving it by fitting the corresponding forming body 40, and in particular its upper portion 40D at the stem of the T-shape, which is sized to be equal to the diameter D1 of the upper portion 40D of the forming body 40.

According to another alternative embodiment, schematically illustrated in fig. 6A, the cantilever contact probe 31 may further comprise a damping portion, substantially configured as a pantograph portion 50, formed at the downtilt probe portion 31b and connected to the hook 31 a. For example, the cantilever contact probe 31 comprises a shaped body 40 corresponding to the embodiment shown in fig. 3C, but it is also contemplated that the cantilever contact probe 31 may be provided with a shaped body 40 and a zoom 50 as in fig. 4A or 4C. By way of example only throughout, the support structure 32 includes a third portion 32C for retaining the arms 40b1, 40b 2. More specifically, the zoom portion 50 is connected to the hook 31a and the declined probe portion 31b at respective bending points PGla and PGlb.

The pantograph 50 substantially comprises four faces 50a-50d having a variable section to distribute the stresses uniformly, the four faces 50a-50d being substantially arranged as a parallelepiped and defining an empty space 50e therein. It is apparent that the zoom portion 50 is able to perform the desired dampening function during the pressing contact of the contact tip 36A of the cantilever contact probe 31 onto the contact pad 35A of the device under test 35.

According to a preferred alternative embodiment, schematically illustrated in fig. 6B, the cantilever contact probe 31 may further comprise another damping portion, substantially configured as a spring portion 51, formed at the up-tilt probe portion 31 c. More specifically, spring portion 51 is connected to top portion 40e of forming body 40 at another bending point PG2 and defines another end 36B adapted to contact pad 33A of PCB board 33. As described above, the cantilever contact probe 31 includes a shaped body 40 corresponding to the embodiment shown in FIG. 3C, by way of example only, but cantilever contact probes 31 having shaped bodies 40 as in FIGS. 4A or 4C are also contemplated; further, the support structure 32 is illustrated as including a third portion 32C for retaining the arms 40b1, 40b2, although the third portion may be absent.

In the example shown in fig. 6B, the spring portion 51 is configured substantially in an elongated N-shape. It is apparent that the spring portion 51 can perform the desired damping function during the pressing contact of the other end 36A of the cantilever contact probe 31 to the contact pad 33A of the PCB board 33.

Obviously, it is possible to realize the cantilever contact probe 31 provided with the spring portion 51 (instead of the zoom portion 50).

It is to be noted that the presence of a further bending point PG2, defined in the inclined probe portion 31C, protruding in the direction of the PCB board 33, allows the spatial distribution of the other end 36B of the contact probe 31, in particular according to the spatial distribution of the contact pad 33A of the PCB board 33, when the contact probe 31 is mounted in the cantilever probe head 30, as schematically illustrated in fig. 7, using by way of non-limiting example the embodiment of the cantilever contact probe 31 of fig. 3C. In particular, the upwardly inclined probe portion 31c with the spring portion 51 and thus the other end 36B serving as a contact head for the contact probe 31 are thus distributed over several rows, two in the figure, while the contact tips 36A continue to line up, in the figure the zoomed portions 50 overlap.

It is noted that the distribution of the contact pads 33A on the PCB 33 may be varied, even over two rows, due to the different sizes of the tilt-up probe portions 31c and the spring portions 51 formed therein, if any. Therefore, the spacing restriction on those contact pads 33A of the PCB board 33 can be released with respect to the contact pads 35A of the device under test 35.

Advantageously, therefore, it is possible to produce contact between the cantilever contact probes 31 and the contact pads 33A of the PCB 33 without having to insert additional components, in particular space transformers, as are usually present in vertical technology.

In fact, it is well known that the distribution of the contact pads 33A of the PCB board 33 has more relaxed space constraints with respect to the distribution of the contact pads 35A of the device under test 35, including the cantilever probe head 30 of the above-mentioned cantilever contact probe 31 provided with the additional bending point PG2, allowing replication without using additional components.

In particular, in fig. 7, the cantilever probe head 30 is shown, comprising at least one first 31 and a second 31' cantilever contact probe, provided in their inclinations with respective further bending points connected to respective spring portions 51, 51', said spring portions 51, 51' being adapted to define respective further end portions 36B, 36B ', said end portions 36B, 36B ' being appropriately displaced between each other, so as to be able to contact the contact pads 33A of the PCB board 33 in different positions. More specifically, the ends of the tilt-up probe portions, i.e., the ends of the spring portions 51, 51', are appropriately received in the different holes 37A, 37A' of the support plate 37. The cantilever contact probes 31, 31' are also provided with respective zoom portions 50, which overlap in the view of fig. 7.

The spatial redistribution of the other ends 36B of the contact probes 31 relative to the corresponding contact tips 36A is further highlighted by the top plan view of the cantilever probe head 30, as shown in fig. 8, where the PCB board 33 is shown. It is particularly clear in this figure that the configuration of the contact probes 31 provided with the further bending points PG2 allows the contact pads 35A of the device under test 35 having a first distance or pitch P1 to be connected with the contact pads 33A of the PCB board 33 having a second distance or pitch P2 which is larger than the first pitch P1(P2> P1), so that the desired spatial transformation can be performed without having to resort to additional components such as a space transformer.

It should also be noted that in the assembly stage, the support structure 32 and the support plate 37 are properly pressed against the PCB board 33 to ensure that the upwardly inclined probe portion 31c of the cantilever contact probe 31, and in particular the other contact portion 36B, is in contact with the contact pad 33A of the PCB board 33 during normal operation of the cantilever probe head 30. Due to the presence of the further bending point PG2 forming the tilt-up probe portion 31c, an assembly under pressure can be obtained. The PG2 can act as a spring during the press contact of the cantilever contact probes 31 mounted in the cantilever probe head 30, especially when the support structure 32 provided with the contact plate 37 abuts against the PCB board 33.

As shown in fig. 6B and 7, in the case where the cantilever contact probe 31 is provided with the spring portion 51, this effect is further ensured.

It should also be noted that the cantilever contact probe 31 is of a suitable size to ensure a sufficient contact force of the contact tip 36A with which the hook 31a terminates on the contact pad 35A of the device under test 35. In particular, the force F exerted by each contact probe 31 is proportional to the arm formed by the probe portion protruding from the support structure 32 and is equal to:

F＝E*D⁴/L³(1)

e is Young's modulus (or longitudinal elastic modulus);

d is the diameter of the contact probe 31, representing its maximum dimension of its cross-section at the down-dip probe portion 31 b; and

l is the length of the declined probe portion 31b, which defines its arm (or free length).

According to the invention, a similar force is applied to the PCB board 33, in particular to its contact pads 33A, suitably by compression of the contact probes 31 at their inclined portions 31c, the contact probes 31 acting substantially as contact head portions of vertical technology probes, as described above.

Advantageously, in the preferred embodiment shown in fig. 6B and 7, the force exerted on the contact pad 35A of the device under test 35 and the contact pad 33A of the PCB board 33 is attenuated by the damping portion, in particular the zoom portion 50 and the spring portion 51 formed at the down-tilt probe portion and the up-tilt probe portion 31B and 31c, respectively, of the cantilever contact probe 31, the cantilever contact probe 31 being provided with the further bending point PG 2.

As already indicated, the different position of the further bending point PG2 further allows to obtain a suitable spatial transformation, and the contact pads 33A of the PCB board 33 are distributed, in particular by placing them at a distance suitable for their larger size, as also shown in fig. 8.

It should also be noted that the cantilever probe head 30 according to the present invention also allows to overcome the disadvantageous aspect of the vertical technique, i.e. the head ends of the vertical probes are floating in contact with the PCB board and have to be re-created each time the respective tip ends contact (touch) the contact pads of the device under test, due to the contact between the upturned probe portions 31c of the cantilever contact probes 31 at the other end 36A and the contact pads 33A of the PCB board 33 formed during the assembly of the cantilever probe head 30, in particular due to the pressure of the support structure 32 provided with the support plate 37 on the PCB board 33.

In other words, in the cantilever probe head 30 according to the present invention, even in the case where the respective hooks 31a do not contact the contact pads 35A of the device under test 35, it is ensured that the upturned portions 31c of the cantilever contact probes 31 contact onto the contact pads 33A of the PCB board 33.

Furthermore, based on the features of the contact probe and the cantilever probe head according to the present invention, in particular the preferred embodiment of the cantilever probe head 30, further technical problems can be solved.

The configuration of the cantilever contact probe 31 provided with the further bending point PG2 and the contact of the other end 36B with the PCB board 33 under pressure actually allows the probe head to be produced in a modular way. More specifically, the modular probe head comprises a PCB board 33 and a plurality of modules 60, each provided with a support structure 32 from which a contact probe 31 projects, the contact probe 31 having a hook 31a at one end and an upturned portion 31c at the other end, the upturned portion 31c being suitably guided by a hole 37A formed in a support plate 37, the support plate 37 being integral with the support structure 32 and in particular with the second portion 32B thereof. Thus, each module 60 has the features of the cantilever probe head 30 as described above, but its dimensions are equivalent to, in particular only slightly larger than, the dimensions of a single device under test 35, "equivalent" meaning that the area occupied by the module 60 is equal to the area occupied by the device under test 35, or greater than 50%, preferably greater than 20%, of the value of the area occupied by the device under test 35.

In particular, a plurality of modules 60 are arranged to extend over an area corresponding to a chip wafer including devices under test, equivalent to the available surface of a PCB board, resulting in a modular probe head suitable for parallel testing of more devices.

More specifically, the PCB board 33 is provided with a suitable support structure or metal housing for accommodating the module 60.

Suitably, the modular probe head comprising a plurality of modules 60 associated with the PCB board 33 has the advantage of allowing individual replacement of the modules in case of damage, which replacement is allowed since the cantilever contact probe 31 does not require solder wires at its other end 36B, but is in contact with the contact pad 33A of the PCB board 33 in a so-called "direct attach" manner similar to the vertical technique.

More specifically, as shown in fig. 9A and 9B, each module 60 comprises at least one contact portion 61, which contact portion 61 is suitably provided with at least one hole 61A, in particular a threaded hole, suitable for housing at least one fixing element, in particular a screw 62, which module 60, thanks to its threaded connection, is integral with or fixed to the supporting structure of PCB 33, or directly to PCB 33 itself.

In a preferred embodiment, as shown in fig. 9A, each module 60 is provided with at least one pair of contact portions 61, the pair of contact portions 61 being arranged along the support structure 32 provided with the support plate 37, in particular at the corners of the substantially square support structure 32.

As schematically shown in fig. 9B, each module may also be provided with a positioning element or pin 63, the pair of positioning elements or pins 63 having a suitable shape complementary to as many housings (not shown) as previously arranged in the supporting structure of the PCB board 33, so as to ensure the correct positioning of each module 60 with respect to the PCB board 33 and facilitate its replacement.

More specifically, the positioning pins 63 may be configured as small cylinders or pyramids protruding from the support structure 32 in the direction of the PCB board 33, adapted to find their position with a limited clearance (for example less than 10 microns) in a suitable housing of the support structure of the PCB board 33, thereby ensuring a precise assembly of each module 60 due to the coupling between the housing and the positioning pins 63.

The support structure or metal housing for housing the module 60 is suitably also provided with contact points for positioning with the PCB board 33.

It is noted that another advantage of the modular probe head comprising a plurality of modules 60 is that, for example in case of damage, only a part thereof can be replaced, which is the only advantage of the vertical technique with so-called floating contact probes, allowing to replace one or more damaged probes by simply drawing them out. Suitably, the replaceable portion corresponding to one or more modules 60 has a smaller size than the entire probe card, i.e. smaller than the wafer size of the device under test, thus reducing the maintenance costs of the probe card itself, which is particularly desirable in the so-called low-cost or mass production field, such as the field of memory testing.

Using a module 60 provided with suitable contact portions 61, which contact portions 61 allow fixing, for example by screwing, to the supporting structure of the PCB board 33, makes the operation of replacing the damaged part easier than replacing one or more probes of a probe head produced in the vertical technique, the operation of replacing the module 60 allowing to take place directly in the testing equipment where the probe head is installed and without using highly skilled workers.

In summary, it is noted that the cantilever contact probe provided with the shaped body can be coupled in a correct and precise manner with a corresponding housing seat formed in the support structure of the cantilever probe head in which the probe is housed.

Therefore, the probe tip produced by the cantilever contacting the probe does not require the use of a holding resin as in the conventional cantilever technique.

Furthermore, as mentioned above, in case the cantilever contact probe is provided with at least one further bending point in its upturned portion to protrude from the support structure in the direction of the PCB, a cantilever probe head can be realized which combines the advantages of the cantilever technology with its basic structure with the advantages of the perpendicular technology, makes the contact without soldering, and does not need to have a much larger area with respect to the overall size of the support structure of the probe head, only the support plate being integral with the support structure.

It is important to note that the probe head is of course inexpensive to manufacture because of the typically reduced cost of cantilever technology and inexpensive during use of the probe head, particularly because of the use of individually replaceable modules.

Furthermore, since the configuration of the cantilever contact probe has an upturned portion substantially perpendicular to the PCB, the distance or pitch of the contact pads of the PCB itself can be easily changed; in fact, it is only necessary to modify its length enough to "fan out" (fan out) the upwardly inclined probe portion terminating in the further contact end, thus enabling even very large and very distant contact pads to be formed on the PCB.

Thus, the cost of the PCB associated with the cantilever probe head may also be reduced, which is actually related to the density or pitch and size of its contact pads.

It is further noted that the probe head itself, produced in accordance with the present invention, becomes a space transformer, which allows the cost of the PCB to be further reduced, which is the most relevant cost of the test equipment, and, as mentioned above, is actually related to the density or spacing and size of the contact pads.

Furthermore, the presence of the damping portions at one or more probe portions allows for improved contact of the respective end portions with contact pads of the device under test and/or the PCB board.

Finally, the cantilever probe head according to the present invention, implemented in a modular manner, ensures the possibility of replacing only the damaged head corresponding to one or more modules.