Probe card comprising contact elements for high-frequency applications

Abstract

A probe card for testing a device under test is described, which has a plurality of contact elements arranged at a given distance from each other along a side by side placing direction. The contact elements have an interface end configured to transmit a signal coming from the device under test to a signal transmission line of the probe card, a body portion, and a contact portion comprising an end adapted to contact contact pads of the device under test. The end of the contact portion is spaced from the interface end along a first axis, and a dimension of the body portion measured along a second axis that is different from the first axis is selected in a range between 50% and 150% with respect to the distance between the contact elements along the side by side placing direction.

Description

[0001] Title: "Probe card comprising contact elements for high-frequency applications"

[0002] DESCRIPTION

[0003] Field of application

[0004] The present invention relates to a probe card adapted to perform the test of electronic devices integrated on a semiconductor wafer, for example high-frequency devices. The following description is made with reference to this field of application with the only purpose of simplifying the exposition thereof.

[0005] Prior art

[0006] As it is well known, a probe card is essentially a device adapted to electrically connect a plurality of contact pads of a microstructure, in particular an electronic device integrated on a semiconductor wafer, with corresponding channels of a testing apparatus which performs the functionality testing thereof, in particular the electrical one, or generically the test.

[0007] The test performed on integrated circuits serves in particular a detect and isolate defective circuits as early as in the production phase. Usually, the probe cards are thus used for the test of the circuits integrated on wafers before cutting and assembling them inside a chip containment package.

[0008] A probe card generally comprises a plurality of movable contact elements or contact probes retained by at least one pair of supports or guides which are substantially plate-like and parallel to each other. These platelike supports are provided with suitable holes and are located at a distance from each other so as to create a free area or air gap for the movement and the possible deformation of the contact probes, which are usually formed by wires of special alloys with good electrical and mechanical properties. The contact probes generally extend between a first end portion, intended to contact contact pads of the device under test, and a second and opposite end portion, intended to contact a space transformer or a printed circuit board (PCB) .

[0009] Nowadays the need to perform tests at high frequencies, up to radiofrequencies, is increasingly felt. In the case of high-frequency tests, probes with a reduced length are normally used, in order to ensure optimal performance. In fact, it is well known that the length of the contact probe is a significant problem as the frequency of test signals increases, in particular due the self-inductance phenomenon. However, the reduced length of the probe body dramatically increases the stiffness thereof, causing an increase of the force exerted by the respective contact tip on the contact pads of the device under test, which can lead to a damage or even to a breaking of these pads, with irreparable damage of the device under test. The increase in the stiffness of the contact probe (due to the reduction of the length thereof) also increases the risk of breaking the probes themselves.

[0010] In the RF testing field, it is known to manufacture short contact elements electrically connected to a flexible membrane on which the conductive tracks for the transmission of high-frequency signal are formed. Generally, in accordance with known solutions, the contact elements of the probe card always have the same configuration, which often results in a wrong sizing of said contact elements which causes some drawbacks during the test, in particular at high frequencies.

[0011] The technical problem of the present invention is to devise a probe card having such structural and functional features as to allow the limitations and drawbacks still affecting known solutions to be overcome, in particular which is able to increase the efficiency of the tests performed at high frequencies.

[0012] Summary

[0013] The solution idea underlying the present invention is to manufacture a probe card whose contact elements comprise a body sized depending on the pitch of the device under test; in particular, the contact elements are equipped with a protruding tip portion adapted to contact contact pads of the device under test and with a body portion which can be sized based on the pitch (and thus based on the relative distance between the several contact elements in the probe card) so as to optimize the magnetic coupling between ground contact elements and contact elements adapted to carry the operating signals that are adjacent to each other in the probe card.

[0014] Based on this solution idea, the above technical problem is solved by a probe card for testing a device under test, comprising a plurality of contact elements that are adjacent to each other and arranged at a given distance from each other along a side by side placing direction, said contact elements comprising an interface end configured to transmit a signal coming from the device under test to a signal transmission line of the probe card, a body portion, and a contact portion (or tip portion) extending (protruding) from the body portion and comprising an end adapted to contact contact pads of the device under test, wherein said end of said contact portion is spaced from the interface end along a first axis, and wherein a dimension of the body portion measured along at least a second axis that is different (in particular substantially orthogonal) from the first axis is selected in a range between 50% and 150% with respect to the distance between the contact elements along the side by side placing direction (for example a distance between substantially central portions of the contact elements along the side by side placing direction) .

[0015] In general, according to the present invention, at least in a group of contact elements in the probe card, the dimension of the body portion of said contact elements (measured at least along the second axis) is proportional to the mutual distance thereof.

[0016] More particularly, the invention comprises the following additional and optional features, taken individually or, if necessary, in combination. These additional and optional features are illustrated for example in the dependent claims.

[0017] According to an aspect of the present invention, said range can be between 85% and 115%.

[0018] According to an aspect of the present invention, the first axis can be a symmetry axis that develops, in use, vertically.

[0019] According to an aspect of the present invention, the second axis can be a transverse axis that is substantially orthogonal to the first axis and to the side by side placing direction.

[0020] According to an aspect of the present invention, at least along the second axis, the dimension of the body portion of the contact elements can be greater than a corresponding dimension (i.e. along said second axis) of the contact portion of said contact elements.

[0021] According to an aspect of the present invention, the body portion of the contact elements can be arranged between the interface end and the contact portion of said contact elements.

[0022] According to an aspect of the present invention, the interface end of the contact elements can be a face of their body portion.

[0023] According to another aspect of the present invention, the interface end of the contact elements can be an end of a portion extending from the body portion and it can have a dimension along the second axis that is different from the dimension of said body portion.

[0024] According to an aspect of the present invention, the body portion of the contact elements can have the shape of a cylinder. In this case, according to an aspect of the present invention, said dimension can coincide with the diameter of the cylinder.

[0025] According to an aspect of the present invention, the contact portion of the contact elements can protrude from a face of the cylinder and it can have the shape of a cylinder as well with dimensions that are smaller than respective dimensions of the body portion (i.e. a smaller diameter, for example at least less than half) .

[0026] According to an aspect of the present invention, the contact portion of the contact elements can be shifted with respect to the centre of the face of the cylinder.

[0027] According to an aspect of the present invention, the contact portion of the contact elements can be made of a material having a greater hardness than the material of the body portion, for example it can be made of rhodium.

[0028] According to an aspect of the present invention, the diameter of the cylinder can be at least twice a diameter of the contact portion (still understood as a maximum transverse dimension) .

[0029] According to an aspect of the present invention, the height of the cylinder can be in a range between 30 gm and 100 gm.

[0030] According to an aspect of the present invention, the body portion of the contact elements can have a rectangular shape and can comprise at least one pair of faces of greater extension and one pair of faces of lesser extension that are adjacent to each other.

[0031] According to an aspect of the present invention, the contact portion can extend from one of said faces of lesser extension.

[0032] According to an aspect of the present invention, at least along the second axis, the dimension of the body portion of the contact elements can be greater than a corresponding dimension (i.e. along the second axis) of the contact portion.

[0033] According to an aspect of the present invention, the contact elements can comprise a junction tapered portion between the body portion and the contact portion thereof. According to an aspect of the present invention, the contact elements can be arranged (adjacent) in such a way that the faces of greater extension of the body portion of a contact element face respective faces of greater extension of contact elements that are adjacent to it along the side by side placing direction.

[0034] According to an aspect of the present invention, the probe card can further comprise a flexible membrane electrically connected to the contact elements and on which the signal transmission lines are formed.

[0035] According to an aspect of the present invention, the contact elements can be grown directly on the flexible membrane.

[0036] According to an aspect of the present invention, a contact element adapted to carry operating signals can be arranged between two contact elements adapted to carry ground signals.

[0037] The features and advantages of the probe card according to the invention will be apparent from the following description of an exemplary embodiment thereof given by way of non-limiting example with reference to the attached drawings.

[0038] Brief description of the drawings

[0039] In the drawings:

[0040] - figure 1 schematically shows a probe card comprising a plurality of contact elements;

[0041] - figures 2A-2C schematically show contact elements of the probe card according to a first embodiment of the present invention with different sizing of a body portion thereof;

[0042] - figures 3A-3B show respective contact elements according to the first embodiment of the present invention which are arranged adjacent to each other; - figure 4 is a diagram representing a different sizing of the contact elements according to the first embodiment of the present invention depending on the pitch of the device under test;

[0043] - figures 5A-5B show different views of contact elements according to a second embodiment of the present invention with a different sizing of a body portion thereof; and

[0044] - figure 6 is a diagram representing a different sizing of the contact elements according to the second embodiment of the present invention depending on the pitch of the device under test.

[0045] Detailed description

[0046] With reference to the figures, a probe card for testing a device under test (herein indicated with the abbreviation DUT - acronym for “Device Under Test”), for example a probe card adapted to perform the test of electronic devices integrated on a semiconductor wafer is globally and schematically indicated with 100.

[0047] It should be noted that the figures are schematic views and are not drawn to scale, but instead they are drawn so as to emphasize the important features of the invention. Furthermore, in the figures, the different elements are schematically depicted, the shape thereof being changeable depending on the desired application. Moreover, it should be noted that, in the figures, identical reference numbers refer to identical elements in terms of shape or function. Finally, special arrangements described in relation to an embodiment illustrated in a figure can also be used for the other embodiments illustrated in the other figures.

[0048] Clearly, some technical details of the invention can be replaced by other technically equivalent details without departing from the scope of the claimed invention, as it is well known by the person skilled in the art.

[0049] In the following description, relative terms such as “above”, “below”, “upwards”, “downwards”, “upper”, “lower” will be used, referring to the illustrations of the solutions given in the figures only to simplify the exposition thereof.

[0050] Furthermore, indications of particular geometries (circular, rectangular) or of the arrangement of the elements (parallel, orthogonal, contiguous), as well as the term “substantially” are always to be understood in relation to physical and not geometrically abstract elements, and thus the tolerances introduced by the transition from a pure mathematical / geometrical world to the real world must always be taken into consideration.

[0051] It should then be noted that, unless it is expressly stated to the contrary, process steps can also be inverted if necessary.

[0052] Moreover, it is noted that, in the context of the present invention, the term “probe card” is used to indicate a testing system without being limited by the presence or absence of particular components, in addition to what is defined by the attached claims. In general, this term thus indicates a set of components (for example the components of a probe head and interface cards interfaced therewith, such as for example a PCB board) which can be associated to further components (for example components of a testing apparatus) for testing devices integrated in the semiconductor wafer, and thus it generally indicates a system for measuring electronic devices.

[0053] The probe card 100 is thus adapted to connect to an apparatus (not illustrated in the figures) to perform the test of devices under test DUT integrated on a semiconductor wafer (indicated with reference SW), for example, for example high-frequency devices, however without being limited to a particular application.

[0054] Referring to figure 1, the probe card 100 comprises a plurality of contact elements (indicated with reference 10) adapted to contact contact pads or pads DUTa of the device under test DUT and to carry the signal from said device under test DUT to the testing apparatus. It is noted that figure 1 shows merely by way of example four contact elements 10 although, obviously, the present invention is not limited at all by the number of the contact elements 10 of the probe card 100, and any, even high, number can be provided.

[0055] In an embodiment, the probe card 100 comprises a flexible membrane (reference 150) electrically connected to the contact elements 10 and on which the signal transmission lines are formed; these transmission lines can be for example conductive tracks formed on one or both faces FA and FB of the flexible membrane 150 and they allow to carry high-frequency signals to a printed circuit board or PCB, here indicated with reference 160; this configuration is advantageous to carry high-frequency signals, since the contact elements 10 can be manufactured as very short ones (with lengths less than 1000 gm), and the signals are then carried in the conductive tracks formed on the flexible membrane 150.

[0056] In the probe card 100, the contact elements 10 are adjacent to each other and arranged at a given distance (indicated with reference “Dis”) along a side by side placing direction (indicated with reference “Dir”), which is thus along the axis X of the reference system of the figures.

[0057] More particularly, the contact elements 10 comprise a body portion 10’ whose configuration will be detailed below. There is then a contact portion 10a (also indicated below as “tip portion”) extending and protruding from the body portion 10’; the contact portion 10a comprises an end 10a’ adapted to contact contact pads DUTa of the device under test DUT.

[0058] Moreover, the contact elements 10 comprise an interface end 10b configured to transmit a signal coming from the device under test DUT to a signal transmission line of the probe card 100, and thus it is the end connected to the flexible membrane 150.

[0059] The end 10a’ of the contact portion 10a is spaced from the interface end 10b along a first axis (herein indicated with reference H-H), which can be seen as a longitudinal axis or symmetry axis of the contact element 10 and develops, in use, vertically, i.e. along the axis Z of the reference system of the figures.

[0060] The body portion 10’ of the contact elements 10 is thus arranged between the interface end 10b and the contact portion 10a, in particular the end 10a’, of said contact elements 10, with reference to the above first axis H- H.

[0061] For convenience of illustration, a second axis is now defined as well, indicated with reference Y-Y, that develops along a different direction with respect to the first axis H-H, in particular it is a transverse axis that is substantially orthogonal to said first axis H-H and to the side by side placing direction Dir (and thus it is along the axis Y of the reference system of the figures). More generally, the second axis Y-Y is thus an axis that is different from the side by side placing direction Dir and different from the first axis H-H.

[0062] Advantageously according to the present invention, the body portion 10’ of the contact elements 10 is so sized as to optimize the magnetic coupling between close contact elements. In general, as will be detailed below, the body portion 10’ is sized based on the pitch of the device under test DUT, i.e. based on the distance between the centres of the contact pads DUTa, and thus based on the distance Dis between the contact elements themselves (for example based on the distance between the centres thereof, with reference to the above direction Dir).

[0063] Specifically, the dimension (or size, indicated with reference D) of the body portion 10’ measured at least along the second axis Y-Y is selected in a range between 50% and 150% with respect to the distance Dis between the adjacent contact elements 10 along the side by side placing direction Dir.

[0064] In a preferred embodiment of the present invention, the above range is between 85% and 115%. In other words, the dimension D of the body portion 10’ of the contact elements 10, when measured along the second axis Y-Y, is selected in the above percentage range with reference to the pitch of the contact pads DUTa of the device under test DUT, thereby optimizing the magnetic coupling between adjacent contact elements.

[0065] As illustrated in the figures, at least along the second axis Y-Y, the dimension of the body portion 10’ of the contact elements 10 is greater than the corresponding dimension of the contact portion 10a.

[0066] In an embodiment, the interface end 10b of the contact elements 10 corresponds to an upper face of their body portion 10’. As an alternative, the interface end 10b can be the end of a portion extending from the body portion 10’ and having a dimension along the second axis Y-Y that is different from the dimension D of the body portion 10’ (which is greater for example), i.e. in this case it can be the upper face of an appendix extending above from the body portion 10’. In other words, the interface end 10b can be a face of the body portion 10’ or it can be part of a specific portion of the contact element 10.

[0067] Furthermore, in general, embodiments are envisageable, in which, inside the probe card 10, there are different groups of contact elements 10, each of which is characterized by a respective distance between its contact elements, and thus different distances Dis can be defined, for example in the case of devices under test DUT in which the pitch is variable. In this case, contact elements are thus provided, having a given dimension D of their own body portion 10’, and other contact elements having a different dimension D, i.e. the dimension D can be variable inside the probe head 100 itself.

[0068] In general, according to the present invention, at least in a group of contact elements in the probe card 10, the dimension of the body portion of said contact elements (measured at least along the second axis Y-Y) is proportional to the mutual distance thereof. This selection (resulting for example in the above range), has the technical effect of optimizing the magnetic coupling.

[0069] Two main embodiments of the present invention corresponding to different geometries of the contact elements 10 will be now illustrated.

[0070] First embodiment

[0071] In an embodiment of the present invention illustrated in figures 2A-2C, the body portion 10’ (also indicated as “shell”) of the contact elements 10 has a rectangular section (and thus it has, at least in one part thereof, the shape of a rectangle) and it comprises at least one pair of faces of greater extension and one pair of faces of lesser extension that are adjacent to each other. In this case, the contact portion 10a (which has lower dimensions along the axis Y-Y) extends from a base face of said rectangle, i.e. from one of said faces of lesser extension, so that said contact elements 10 are substantially T-shaped.

[0072] In some exemplary embodiments, the contact elements 10 can comprise a junction tapered portion (reference lOr) between the body portion 10’ and the contact portion 10a thereof. The tapered portion lOr can also be seen as part of the body portion 10’ (which thus comprises a rectangular part and a tapered part), where the above dimension D is the maximum dimension of said body portion 10’ along the axis Y-Y.

[0073] In any case, as indicated in figures 3A-3B and in figure 4, in this embodiment, the contact elements 10 are adjacent in such a way that the faces of greater extension of the body portion 10’ of a contact element face respective faces of greater extension of the contact elements that are adjacent to it along the side by side placing direction Dir.

[0074] With particular reference to figure 4, the left column ColA shows a device under test DUT with a large pitch and contact elements 10 for which their mutual distance Dis has a given value, while the right column ColB shows a device under test DUT with a narrower pitch and contact elements 10 for which their mutual distance Dis is lower than what is shown in the left column ColA. In this case, the dimension D, along the axis Y-Y, of the body portion 10’ of the contact elements 10 of the left column ColA is greater than the corresponding dimension D of the contact elements 10 of the right column ColB, in order to optimize the magnetic coupling between adjacent contact elements.

[0075] In other words, summarizing the above, the contact element 10 has a variable geometry, with a geometric element (i.e. the above body portion 10’ or shell) that is sized to promote the magnetic coupling between ground contact elements and signal contact elements, obtaining a configuration adapted to RF testing; the shells of the contact elements 10 are thus sized depending on the pitch, in particular a narrow shell, along the axis Y-Y, with narrow pitches and a large shell with larger pitches are provided, as in the above figure 4 which shows an example of a ground- signal-ground layout.

[0076] Second embodiment

[0077] Referring now to figures 5A-5B, in another advantageous embodiment of the present invention, the body portion 10’ of the contact elements 10 has the shape of a cylinder (also indicated below as “base cylinder”); in this case, the above-discussed dimension D corresponds to the diameter of the base cylinder forming the body portion 10’. Accordingly, in this case, the dimension D is measured not only along the previous axis Y-Y, but in any radial direction along which it is possible to define a diameter of the base cylinder (i.e. in this case it is possible to define a plurality of radially directed axes Y-Y).

[0078] In this embodiment, as described above, the base cylinder of the contact element 10 is sized depending on the pitch of the device under test DUT to achieve the ideal RF coupling. This embodiment is thus characterized by the same inventive concept as the previous embodiment, although in this case it affects the diameter of the base cylinder, whose ideal dimension D is selected in the above range with reference to the distance Dis between adjacent contact elements 10, in this case with reference to the distance between the centres of adjacent cylinders.

[0079] In an embodiment, the above cylinder- shaped contact elements 10 can be grown directly on the flexible membrane 150, although the present invention is not limited thereto and other methods are envisageable.

[0080] In this embodiment, the contact portion 10a of the contact elements 10 protrudes from a face of the cylinder and it has the shape of a cylinder as well with dimensions that are smaller than respective dimensions of the body portion 10’.

[0081] Merely by way of example, the body portion 10’ has the shape of a first cylinder (i.e. the above base cylinder) with a height between 30 gm and 100 gm and having a variable diameter depending on the layout of the contact pads DUTa of the device under test DUT; the height of said base cylinder can instead be variable depending on the testing frequency. The contact portion 10a has instead the shape of a second cylinder with a height between 10 gm and 15 gm and a lower diameter than that of the base cylinder. However, it is noted that the present invention is not limited at all by the adopted dimensions, which can vary based on the needs and / or circumstances.

[0082] In an embodiment, the diameter of the base cylinder is at least twice a diameter (understood herein for example as a maximum transverse dimension) of the contact portion 10a (which is for example cylindershaped as well), and it is so sized as not to contact the adjacent base cylinders, for example with a margin of 5 gm; the exact dimension can be decided based on RF simulations.

[0083] In an embodiment, the body portion 10’ is made of a first metal material and the contact portion 10a is made of a second metal material (for example rhodium) which is harder than the first material and has a lower diameter, so as to be adapted to contact contact pads DUTa.

[0084] As illustrated in figures 5A-5B the contact portion 10a of the contact elements 10 can be shifted with respect to the centre of the face of the base cylinder 10’, although other configurations are envisageable.

[0085] Referring now to figure 6, similarly to what is seen in figure 4, the left column ColA shows a device under test DUT with a large pitch and contact elements 10 for which their mutual distance Dis has a given value, while the right column ColB shows a device under test DUT with a narrower pitch and contact elements 10 for which their mutual distance Dis is lower than what is shown in the left column ColA, where in this case the distance Dis corresponds to the distance between the centres of the base cylinders 10’. In this case as well, the dimension D, i.e. the diameter of the body portion 10’ and thus of the base cylinder, of the contact elements 10 shown in the left column ColA is greater than the corresponding diameter shown in the right column ColB, in order to optimize the magnetic coupling between adjacent probes. Thereby, the variable diameter of the base cylinder of the contact elements 10 allows to improve the magnetic coupling between ground contact elements and signal contact elements, obtaining a configuration adapted to RF testing, where a lower diameter with narrow pitches and a greater diameter with larger pitches are provided, as in the above figure 6 which shows an example of a ground-signal-ground layout.

[0086] In conclusion, summarizing the above, the present invention allows to successfully overcome the technical problem, providing the above probe card and solving all the drawbacks of the prior art, through contact elements for RF testing having a geometric element (i.e. the above body portion) of variable dimensions which are useful to improve the magnetic coupling.

[0087] Advantageously according to the present invention, the optimal sizing of the geometry of the contact elements improves the magnetic coupling between close contact elements, thus improving the high-frequency performance of the probe card as a whole.

[0088] Generally, in the probe card of the present invention, a contact element adapted to carry operating signals is arranged between two contact elements adapted to carry ground signals, and thus the above sizing promotes the correct magnetic coupling between said contact elements, i.e. there is an optimal coupling between the ground probes and the probes intended to carry the operating signals in every situation and for every pitch.

[0089] At least two types of contact elements are provided: a first type provides a rectangle-shaped body (also indicated as shell) of variable width, while a second type provides a base cylinder of variable diameter; in both cases, the shell or the base cylinder of the contact elements (and more generally their body portion) is thus sized depending on the pitch of the device under test, obtaining the above advantages.

[0090] Obviously, in order to meet contingent and specific requirements, a person skilled in the art will be allowed to bring several modifications and alternatives to the above-described probe card, all falling withing the scope of protection of the invention as defined by the following claims.

Claims

CLAIMS1. A probe card (100) for testing a device under test (DUT), comprising a plurality of contact elements (10) arranged at a given distance (Dis) from each other along a side by side placing direction (Dir), said contact elements (10) comprising:- an interface end (10b) configured to transmit a signal coming from the device under test (DUT) to a signal transmission line of the probe card (100);- a body portion (10’); and- a contact portion (10a) comprising an end (10a’) adapted to contact contact pads (DUTa) of the device under test (DUT), wherein said end (10a’) of said contact portion (10a) is spaced from the interface end (10b) along a first axis (H-H), wherein a dimension (D) of the body portion (10’) measured along a second axis (Y-Y) that is different from the first axis (H-H) is selected in a range between 50% and 150% with respect to the distance (Dis) between the contact elements (10) along the side by side placing direction (Dir).

2. The probe card (100) according to claim 1, wherein said range is between 85% and 115%.

3. The probe card (100) according to claim 1 or 2, wherein the first axis (H-H) is a symmetry axis that develops, in use, vertically, and wherein the second axis (Y-Y) is a transverse axis that is substantially orthogonal to said first axis (H-H) and to the side by side placing direction (Dir).

4. The probe card (100) according to any one of the preceding claims, wherein, at least along the second axis (Y-Y), the dimension (D) of the body portion (10’) of the contact elements (10) is greater than a corresponding dimension of the contact portion (10a) of said contact elements (10).

5. The probe card (100) according to any one of the preceding claims, wherein the body portion (10’) of the contact elements (10) is arranged between the interface end (10b) and the contact portion (10a) of said contact elements (10).

6. The probe card (100) according to any one of the preceding claims, wherein the interface end (10b) of the contact elements (10) is a face of their body portion (10’).

7. The probe card (100) according to any one of claims 1 to 6, wherein the interface end (10b) of the contact elements (10) is an end of a portion extending from the body portion (10’) and having a dimension along the second axis (Y-Y) that is different from the dimension (D) of said body portion (10’).

8. The probe card (100) according to any one of the preceding claims, wherein the body portion (10’) of the contact elements (10) has the shape of a cylinder, and wherein said dimension (D) coincides with the diameter of the cylinder.

9. The probe card (100) according to claim 8, wherein the contact portion (10a) of the contact elements (10) protrudes from a face of the cylinder and has the shape of a cylinder as well with dimensions that are smaller than respective dimensions of the body portion (10’).

10. The probe card (100) according to claim 8 or 9, wherein the contact portion (10a) of the contact elements (10) is shifted with respect to the centre of the face of the cylinder.

11. The probe card (100) according to any one of claims 8 to 10, wherein the contact portion (10a) of the contact elements (10) is made of a material having a greater hardness than the material of the body portion (10’), for example it is made of rhodium.

12. The probe card (100) according to any one of claims 8 to 11, wherein the diameter of the cylinder is at least twice a diameter of the contactportion (10a), and wherein a height of said cylinder is in a range between 30 gm and 100 gm.

13. The probe card (100) according to claim 1, wherein the body portion (10’) of the contact elements (10) has a rectangular shape and comprises at least one pair of faces of greater extension and one pair of faces of lesser extension, wherein the contact portion (10a) extends from one of said faces of lesser extension, and wherein, at least along the second axis (Y-Y), the dimension (D) of the body portion (10’) of the contact elements (10) is greater than a corresponding dimension of said contact portion (10a).

14. The probe card (100) according to claim 13, wherein the contact elements (10) comprise a junction tapered portion (lOr) between the body portion (10’) and the contact portion (10a) thereof.

15. The probe card (100) according to claim 13 or 14, wherein the contact elements (10) are arranged in such a way that the faces of greater extension of the body portion (10’) of a contact element face respective faces of greater extension of contact elements that are adjacent to it along the side by side placing direction (Dir) .

16. The probe card (100) according to any one of the preceding claims, further comprising a flexible membrane (150) electrically connected to the contact elements (10) and on which the signal transmission lines are formed.

17. The probe card (100) according to claim 16, wherein the contact elements (10) are grown directly on the flexible membrane (150).

18. The probe card (100) according to any one of the preceding claims, wherein a contact element adapted to carry operating signals is arranged between two contact elements adapted to carry ground signals.

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