CONTACT PROBE FOR A PROBE HEAD

Abstract

A contact probe for a probe head for test equipment of electronic devices is provided. The contact probe includes a first end portion and a second end portion configured to realize a contact with suitable contact structures, and a body portion extended along a longitudinal development axis between respective the first and second end portions. The first end portion includes a base portion, a peripherally protruding element protruding from the base portion, and a hollow part having a base at a surface of the base portion and being surrounded by the peripherally protruding element. In addition, the peripherally protruding element is configured to penetrate into the contact structures.

Claims

1. A contact probe for a probe head for a test equipment of electronic devices comprising: a first end portion and a second end portion configured to realize a contact with suitable contact structures; a body portion extended along a longitudinal development axis between respective the first and second end portions; wherein the first end portion comprises: a base portion; a peripherally protruding element protruding from the base portion; and a hollow part having a base at a surface of the base portion and being surrounded by the peripherally protruding element and wherein the peripherally protruding element is configured to penetrate into the contact structures.

2. The contact probe of claim 1, wherein the peripherally protruding element extends continuously at the entire circumference of the end portion of the contact probe.

3. The contact probe of claim 1, wherein the peripherally protruding element extends discontinuously at a circumference of the first end portion of the contact probe and comprises a plurality of single protruding elements.

4. The contact probe of claim 3, wherein the single protruding elements are formed at side walls of the first end portion of the contact probe.

5. The contact probe of claim 3, wherein the single protruding elements are formed at the edges of the first end portion of the contact probe.

6. The contact probe of claim 3, wherein the single protruding elements are L-shaped and are formed at edges and so as to extend along contiguous walls of the first end portion of the contact probe.

7. The contact probe of claim 3, wherein the peripherally protruding element comprises one or more between: a plurality of single protruding elements formed at side walls of the first end portion of the contact probe; a plurality of single protruding elements formed at edges of the first end portion of the contact probe; a plurality of single L-shaped protruding elements and formed at edges and so as to extend along contiguous walls of the first end portion of the contact probe.

8. (canceled)

9. (canceled)

10. The contact probe according to claim 1, wherein the first end portion is made by a multilayer comprising a plurality of conductive layers.

11. The contact probe of claim 10, wherein the conductive layers of the plurality of conductive layers have different heights in correspondence of the peripherally protruding element.

12. The contact probe of claim 11, wherein the conductive layers have gradually increasing heights respectively decreasing in the direction of the hollow part.

13. The contact probe of claim 11, wherein at least one layer of the conductive layers is made of a second conductive material having higher hardness than the hardness of a first conductive material forming the remaining conductive layers of the first end portion.

14. The contact probe of claim 13, wherein the at least one layer protrudes with respect to the remaining conductive layers of the first end portion.

15. (canceled)

16. The contact probe of claim 1, wherein the base of the hollow part of the first end portion has an irregular or not planar shape, comprising reliefs.

17. (canceled)

18. (canceled)

19. (canceled)

20. (canceled)

21. The contact probe according to claim 9, wherein the first end portion is formed by a first conductive material and comprises, in correspondence of the peripherally protruding element, at least one coating of a second conductive material having higher hardness than a hardness of the first conductive material.

22. The contact probe of claim 21, wherein the first conductive material is selected from the group consisting of a metal, a metallic alloy selected from nickel, nickel alloy, copper, copper alloy, palladium, palladium alloy, cobalt, cobalt alloy and in that said second conductive material is chosen between a metal, a metallic alloy selected from rhodium, rhodium alloy, platinum, platinum alloy, iridium, iridium alloy.

23. The contact probe of claim 22, wherein the coating is arranged at the hollow part defined at the first end portion by the peripherally protruding element.

24. (canceled)

25. The contact probe of claim 1, wherein the first end portion is a contact tip configured to contact a contact structure of a device under test.

26. The contact probe of claim 1, wherein the contact structure is a contact three-dimensional structure selected from the group consisting of: a bump, a pillar, a contact planar structure, a contact pad, a contact pad coated by a layer of oxide, a contact pad coated by a layer of dirt.

27. (canceled)

28. A probe head for a test equipment of electronic devices wherein it comprises a plurality of contact probes, each contact probe comprising: a first end portion and a second end portion configured to realize a contact with suitable contact structures; a body portion extended along a longitudinal development axis between respective the first and second end portions; wherein the first end portion comprises: a base portion; a peripherally protruding element protruding from the base portion; and a hollow part having a base at a surface of the base portion and being surrounded by the peripherally protruding element and wherein the peripherally protruding element is configured to penetrate into the contact structures.

29. The probe head of claim 28, wherein the peripherally protruding element is chosen between: a peripherally protruding element extending continuously at the entire circumference of the end portion of the contact probe; a peripherally protruding element extending discontinuously at a circumference of the first end portion of the contact probe and comprising a plurality of single protruding elements, the single protruding elements being formed at side walls of the first end portion of the contact probe; a peripherally protruding element extending discontinuously at a circumference of the first end portion of the contact probe and comprising a plurality of single protruding elements, the single protruding elements being formed at the edges of the first end portion of the contact probe; a peripherally protruding element extending discontinuously at a circumference of the first end portion of the contact probe and comprising a plurality of single protruding elements, the single protruding elements being L-shaped and formed at edges, so as to extend along contiguous walls of the first end portion of the contact probe; a peripherally protruding element comprising one or more between: a plurality of single protruding elements formed at side walls of the first end portion of the contact probe; a plurality of single protruding elements formed at edges of the first end portion of the contact probe; a plurality of single L-shaped protruding elements and formed at edges and so as to extend along contiguous walls of the first end portion of the contact probe.

30. The probe head of claim 28, wherein the first end portion is made by a multilayer comprising a plurality of conductive layers chosen between: a plurality of conductive layers having different heights in correspondence of the peripherally protruding element; a plurality of conductive layers have gradually increasing heights respectively decreasing in the direction of the hollow part; a plurality of conductive layers with at least one layer being made of a second conductive material having higher hardness than the hardness of a first conductive material forming the remaining conductive layers of the first end portion; a plurality of conductive layers with at least one layer being made of a second conductive material having higher hardness than the hardness of a first conductive material forming the remaining conductive layers of the first end portion and protruding with respect to the remaining conductive layers of the first end portion.

31. The probe head of claim 28, wherein the base of the hollow part of the first end portion has an irregular or not planar shape, comprising reliefs.

32. The probe head of claim 28, wherein the first end portion is formed by a first conductive material and comprises, in correspondence of the peripherally protruding element, at least one coating of a second conductive material having higher hardness than a hardness of the first conductive material, the first conductive material being chosen between a metal, a metallic alloy selected from nickel, nickel alloy, copper, copper alloy, palladium, palladium alloy, cobalt, cobalt alloy and in that said second conductive material is chosen between a metal, a metallic alloy selected from rhodium, rhodium alloy, platinum, platinum alloy, iridium, iridium alloy.

33. The probe head of claim 28, wherein the first end portion is a contact tip configured to contact a contact structure of a device under test.

34. The probe head of claim 28, wherein the contact structure is a contact three-dimensional structure chosen between a bump, a pillar, a contact planar structure, a contact pad, a contact pad coated by a layer of oxide, a contact pad coated by a layer of dirt.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0053] In such drawings:

[0054] FIG. 1 schematically shows a probe head with vertical probes made according to the prior art;

[0055] FIG. 2 schematically shows a vertical probe of the pogo pin type made according to the prior art;

[0056] FIG. 3 schematically shows an embodiment of a contact probe according to the present invention, in a partial perspective view;

[0057] FIGS. 4A-4D, 5A-5D, 6, 7A-7B, 8A-8B, 9A-9C, 10A-10C and 11A-11C schematically show perspective views of alternative embodiments of a contact probe according to the present invention; and

[0058] FIGS. 12A-12B and 13A-13B schematically show section views of further alternative embodiments of a contact probe according to the present invention.

MODES FOR CARRYING OUT THE INVENTION

[0059] With reference to said Figures, and in particular to FIG. 3, a contact probe for a probe head for a testing apparatus of electronic devices integrated on a wafer, globally indicated by 30, is described.

[0060] It should be noted that the figures represent schematic views of the contact probe according to the invention and are not drawn to scale, but instead they are drawn so as to enhance the important features of the invention. In the figures, the different pieces are shown schematically and their shape may vary according to the desired application.

[0061] In particular, as seen in connection with the prior art, the contact probe 30 is used to make an electric connection between a device under test integrated on a wafer and a testing apparatus, not illustrated in the figure, and comprises a body portion 30C and a first end portion 30A and a second end portion 30B, respectively, which are usually indicated as a contact tip 30A configured to abut onto a contact structure of the device under test and a contact head 30B, configured to interface with a board configured to make the contact with the testing apparatus.

[0062] The contact probe 30 may be a vertical contact probe or a probe of the pogo pin type; substantially it extends along a longitudinal development axis HH arranged as the z axis of the local reference of FIG. 3 and preferably has, as in the illustrated example, a rectangular section.

[0063] In an embodiment, the body portion 30C has a longitudinal dimension LC, i.e. according to axis HH, comprised between 70 μm and 7000 μm, the contact tip 30A has a longitudinal dimension LA comprised between 12 μm and 1000 μm and the contact head 30B has a longitudinal dimension LB comprised between 20 μm and 2000 μm.

[0064] According to an aspect of the invention, at least one end portion of the contact probe 30, in particular the contact tip 30A comprises a base portion 31 and a peripherally protruding element 32 starting from said base portion 31. A hollow part 34 having a base 33 at an upper surface (according to the local reference of the Figure) of the base portion 31 and surrounded by the peripherally protruding element 32 is thus defined in the contact tip 30A.

[0065] In particular, the peripherally protruding element 32 extends starting from the base 33, i.e. from the base portion 31, according to the longitudinal development axis HH of the contact probe 30 in a direction opposite the body portion 30C, by a longitudinal dimension L1 comprised between 10 μm and 150 μm, i.e. equal to 15-85% of the longitudinal dimension LA of the contact tip 30A. Along said axis HH, i.e. according to the z axis direction of the local reference of the Figure, the body portion 30C, the base portion 31 and the peripherally protruding element 32 are thus arranged in succession and contiguously to each other. In a preferred embodiment, as illustrated in the figures, the contact probe 30 has a squared section having side D comprised between 10 μm and 80 μm.

[0066] The peripherally protruding element 32 realizes, indeed, the portion configured to contact a contact structure of a device under test, not represented. Such a contact structure may be a pad or contact pad, i.e. a substantially planar structure, or a three-dimensional structure, such as for instance a bump or a pillar.

[0067] Suitably, the peripherally protruding element 32 is able to penetrate, at least partially a three-dimensional contact structure, as well as a possible surface layer of a planar contact structure, such as an oxide or dirt layer covering a contact pad, thus ensuring the proper electric contact between the contact probe 30 and the device under test.

[0068] Substantially the contact tip 30A of the contact probe 30 comprising the peripherally protruding element 32 has a straw shape, in the example in the Figure a squared-section straw. Obviously it is possible to make the contact probe 30 and its contact tip 30A with a different section, such as a circular or rectangular section based on the needs.

[0069] Tests performed by the same Applicant highlighted an excellent penetrative ability of the contact tip 30A thanks to the peripherally protruding element 32, besides a reduced accumulation of material inside the hollow part 34 further to the testing operations, in particular of three-dimensional contact structures.

[0070] It is also worth stressing the fact that the peripherally protruding element 32 forming the real contact portion of the contact tip 30A has a constant section along the longitudinal axis HH, which is substantially kept unaltered over time even after cleaning operations made for instance by touch on abrasive cloth. Therefore, the contact probe 30 may be subjected to several cleaning operations, showing same performances, thus having a long useful life.

[0071] Suitably, according to the embodiment illustrated in FIG. 3, the peripherally protruding element 32 extends at the entire circumference or perimeter of the contact probe 30, in particular of its contact tip 30A, i.e. it runs continuously through all its side walls substantially in the shape of a ring, having a squared section according to the example illustrated in the Figure.

[0072] Several alternative embodiments of the peripherally protruding element 32 are possible, such as for instance illustrated in FIGS. 4A-4D, which only show the contact tip 30A of the contact probe 30.

[0073] In particular, according to a first embodiment illustrated in FIG. 4A, the peripherally protruding element 32 is in the shape of a continuous ring, which protrudes starting from the base portion 31 running through the entire circumference thereof and defines therein a hollow part 34 of the contact tip 30A, in a substantially correspondent manner to what has been illustrated in FIG. 3.

[0074] According to an alternative embodiment, schematically illustrated in FIG. 4B, the peripherally protruding element 32 is interrupted, in particular at corner portions. In this way, the peripherally protruding element 32 is made up of a plurality of single protruding elements 32a-32d arranged at the walls of the contact tip 30A of the contact probe 30 and extending just by a section of said walls, not comprising the corner portions. In a preferred embodiment, as illustrated in FIG. 4B, the single protruding elements 32a-32d extend at a central portion of the side walls of the contact tip 30A and have transversal dimensions Lt that are substantially equal to each other, thus forming a peripherally protruding element 32 that is substantially symmetric. Obviously it is possible to make the single protruding elements 32a-32d with different transversal dimensions and positioned in any way along the side walls of the contact tip 30A of the contact probe 30. It is also possible to provide for a peripherally protruding element 32 that comprises single protruding elements only at some but not all of the side walls of the contact tip 30A, possibly also at only two walls, which are contiguous or opposite each other.

[0075] According to a further alternative embodiment, schematically illustrated in FIG. 4C, the peripherally protruding element 32 is equally interrupted, in particular at central portions of the side walls of the contact tip 30A of the contact probe 30. In this way, the peripherally protruding element 32 is made up of a plurality of single protruding elements 32a-32d arranged at the edges of the contact tip 30A. In a preferred embodiment, as illustrated in FIG. 4C, the single protruding elements 32a-32d have a squared section of the same area. It is also possible to make the single protruding elements 32a-32d with sections different in shape or dimensions, for instance rectangular, or to provide for a peripherally protruding element 32 comprising single protruding elements only at some but not all of the edges of the contact tip 30A, possibly even at only two edges, that are contiguous and opposite each other.

[0076] Alternatively, as schematically illustrated in FIG. 4D, the interrupted peripherally protruding element 32 comprises single protruding L-shaped elements 32a-32b arranged at edges of the contact tip 30A of the contact probe 30. In the example of the Figure, the single protruding elements 32a e 32b are L-shaped having two arms of the same length and extending beyond the half of two contiguous side walls of the contact tip 30A, said elements being in the number of two and arranged at opposite edges. It is also possible to make the single protruding elements 32a-32b in the L-shape with two arms of different lengths or to provide for a number of single protruding L-shaped elements greater than two, for instance four single protruding L-shaped elements at the four edges of the contact tip 30A of the contact probe 30.

[0077] Moreover, it is possible to provide for a combination of the different alternative embodiments of the interrupted peripherally protruding element 32 illustrated in FIGS. 4B-4D, for instance formed by single protruding elements arranged both at the side walls of the contact tip 30A and at the edges thereof, by combining the alternative embodiments illustrated in FIGS. 4B and 4C, in the shape of battlements of a castle. It is also possible to make the peripherally protruding element 32 so as to comprise single protruding elements both at the side walls of the contact tip 30A and as L-shaped elements at the edges thereof by combining the alternative embodiments illustrated in FIGS. 4B and 4D. The interrupted peripherally protruding element 32 may also comprise some protruding elements arranged at the side walls, some protruding elements arranged at the edges, and some protruding elements arranged at the edges being L-shaped elements, duly sized in order to fit within the perimeter of the contact tip 30A, so as to combine the embodiments of FIGS. 4B, 4C and 4D.

[0078] Other alternative embodiments with a different number of single protruding elements, in a symmetrical or asymmetrical shape or arrangement, may be provided, anyway formed at a peripheral portion of the contact tip 30A of the contact probe 30, so as to form the interrupted peripherally protruding element 32.

[0079] It is pointed out that the peripherally protruding element 32 in the different illustrated alternative embodiments, even when interrupted, is able to define therein a hollow part 34 of the contact tip 30A, which extends up to a base 33 corresponding to an upper surface of the base portion 31 of the contact tip 30A.

[0080] The contact tip 30A of the contact probe 30 illustrated in FIGS. 4A-4B is made of only one material. In particular, the contact tip 30A is made of a first conductive material that is metal or a metallic alloy and may be for instance nickel or an alloy thereof, such as nickel-manganese, nickel-cobalt or nickel-tungsten alloys, copper or an alloy thereof, palladium or an alloy thereof, cobalt or an alloy thereof. In a preferred embodiment of the invention, the first conductive material is palladium-cobalt.

[0081] In a preferred embodiment, the contact tip 30A is made as a single piece and of the same material as the body portion 30C of the contact probe 30. It is also possible to provide for a coating material of the contact tip 30A, such as a covering layer made of a low internal stress conductive alloy, such as a nickel alloy, able to improve the mechanical performances of the contact tip 30A of the contact probe 30.

[0082] The contact probe 30 may also be formed by means of a multilayer made up of a plurality of conductive layers, of the same or different materials. In this case, the contact tip 30A is also formed by a multilayer, as schematically illustrated in FIGS. 5A-5D, corresponding to the different alternative embodiments of the contact tip 30A of FIGS. 4A-4D and in particular comprising a continuous peripherally protruding element 32 (FIG. 5A) or an interrupted peripherally protruding element 32, of the type comprising single protruding elements 32a-32d arranged at the side walls of the contact tip 30A (FIG. 5B), or comprising single protruding elements 32a-32d arranged at the edges of the contact tip 30A (FIG. 5C), or comprising single L-shaped protruding elements 32a-32b (FIG. 5D). It is pointed out that, in this case, the base 33 also comprises a plurality of layers, as illustrated in FIGS. 5A-5D, said base 33 being substantially planar.

[0083] It is also possible to make the base 33 with an irregular or not planar shape, for instance comprising reliefs, as schematically illustrated in FIG. 6. Though in said FIG. 6, the contact tip 30A, and thus the base 33 as well, is made starting from a multilayer, it is also possible to obtain the irregular or not planar trend with reliefs of the base 33 even when the contact tip 30A is made of only one material.

[0084] Advantageously according to the present invention, it is also possible to make the peripherally protruding element 32, continuous or interrupted, with different thicknesses S1, S2 as illustrated in FIGS. 7A-7B for an interrupted peripherally protruding element 32 comprising single protruding elements 32a-32d arranged at the side walls of the contact tip 30A of the contact probe 30 and in FIGS. 8A-8B for an interrupted peripherally protruding element 32 comprising single protruding elements 32a-32d arranged at edges of the contact tip 30A of the contact probe 30. In the examples illustrated in the figures, the contact tips 30A are preferably made of a multilayer, one or more layers also forming the single protruding elements 32a-32d.

[0085] More particularly, the peripherally protruding element 32 and in particular its single protruding elements 32a-32d may have a thickness varying between 5 μm and 30 μm.

[0086] Further advantageously, it is possible to make the peripherally protruding element 32, continuous or interrupted, with different heights H1-H3 starting from the base portion 31, as illustrated in FIGS. 9A-9C for an interrupted peripherally protruding element 32 comprising single protruding elements 32a-32d arranged at the side walls of the contact tip 30A of the contact probe 30 and in FIGS. 10A-10C for an interrupted peripherally protruding element 32 comprising single protruding elements 32a-32d arranged at edges of the contact tip 30A of the contact probe 30.

[0087] As previously seen for the continuous peripherally protruding element 32, the interrupted peripherally protruding element 32 and in particular its single protruding elements 32a-32d may also have heights varying between 10 μm and 200 μm.

[0088] It is also pointed out how the possibility of making a contact tip 30A with a peripherally protruding element 32 having a considerable height, as illustrated for instance in FIGS. 9C and 10C, allows ensuring that said contact tip 30A may be subjected to a high number of cleaning operations, in particular by touch on abrasive cloth, before risking to modify its section at the area in contact with the three-dimensional or planar contact structure of the device under test, thus ensuring a prolonged useful life to the contact probe 30.

[0089] Finally, according to a preferred embodiment of the invention, the contact tip 30A comprises, at the peripherally protruding element 32, at least one coating 35 of a second conductive material having a higher hardness than the hardness of the first conductive material that forms the contact probe 30 and thus the contact tip 30A, as schematically illustrated in FIGS. 11A-11C, for the alternative embodiments with a continuous peripherally protruding element 32 (FIG. 11A) or with an interrupted peripherally protruding element 32, in particular comprising single protruding elements 32a-32d arranged at the side walls of the contact tip 30A of the contact probe 30 (FIG. 11B) and comprising single protruding elements 32a-32d arranged at edges of the contact tip 30A of the contact probe 30 (FIG. 11C).

[0090] More particularly, the second conductive material is a metal or a metallic alloy and may be rhodium or an alloy thereof, platinum or an alloy thereof, iridium or an alloy thereof, for instance a palladium-cobalt alloy, a palladium-nickel alloy or a nickel-phosphorus alloy. In a preferred embodiment of the invention, the second conductive material is rhodium.

[0091] Suitably, said coating 35 is arranged at the hollow part 34 defined in the contact tip 30A by the continuous or interrupted peripherally protruding element 32.

[0092] In this way, the coating 35 of high hardness material is able, in addition to delaying the consumption of the peripherally protruding element 32 and thus to extending the working life of the contact probe 30, to reduce the accumulation of material inside the hollow part 34 during the penetration of the contact tip 30A into three-dimensional or planar contact structures, in particular in surface layers of contact pads.

[0093] According to an alternative embodiment, the contact probe 30, and in particular the contact tip 30A, made by a multilayer comprising a plurality of conductive layers 36, of the same or different materials, may have layers of different heights at the peripherally protruding element 32, with increasing or decreasing values in the direction of the hollow part 34.

[0094] More particularly, in the sections illustrated in FIGS. 12A and 12B, corresponding to a section at a plane n arranged along the longitudinal development axis HH of the probe 30 and passing through the center of two single protruding elements arranged on opposite walls of the contact tip 30A, as indicated for instance in FIG. 11B, each single protruding element comprises a plurality, in the example three conductive layers 36 of different heights, H6.sub.1, H6.sub.2 e H6.sub.3 respectively, which may have a gradually decreasing value starting from the outer perimeter towards the hollow part 34, as illustrated in FIG. 12A, or a gradually increasing value, as illustrated in FIG. 12B.

[0095] It is pointed out that this alternative embodiment of the contact tip 30A of the contact probe 30 according to the present invention increases the penetrative ability of its peripherally protruding element 32, in particular of the single protruding elements 32a-32d and decreases the quantity of unwanted residual material that accumulates on said contact tip 30A during the testing operations, in particular on contact three-dimensional structures.

[0096] It is possible to further improve the penetrative ability of the contact tip 30A and to reduce possible accumulated material by making at least the layer of greater height of its peripherally protruding element 32, in particular of the single protruding elements 32a-32d, by means of the second conductive material with high hardness, in particular rhodium, thus forming the coating 35 arranged at the hollow part 34, i.e. in the case of conductive layers having gradually increasing heights, as illustrated in FIGS. 13A and 13B.

[0097] More particularly, the coating layer 35 may develop along the whole contact tip 30A, as illustrated in FIG. 13A (and possibly also continue in the rest of the contact probe 30) or be only formed at the hollow part 34, as illustrated in FIG. 13B.

[0098] Preferably, the coating layer 35 in this case is made so as to protrude with respect to the other layers forming the peripherally protruding element 32, or the single protruding elements 32a-32d, by a height H6 value varying from 2 μm to 50 μm.

[0099] Suitably, the contact tip 30A may be used to make an end portion of a vertical contact probe or of a probe of the pogo pin type.

[0100] Essentially, the contact probe having a contact tip equipped with a peripherally protruding element ensures a proper contact with contact structures of a device under test, in particular three-dimensional contact structures such as bumps or pillars, but also planar contact structures such as pads, in particular when covered with oxide or dirt layers which the contact tip must suitably penetrate.

[0101] Advantageously, the shapes of the contact tips comprising said peripherally protruding element have a constant section along a longitudinal development axis of the contact probe itself and ensures constant performances thereof also further to numerous testing and cleaning operations. Suitably, said peripherally protruding elements may have dimensions adapted to make a tip “on consumption” and are particularly advantageous to make contact tips of the so-called pogo pin probes.

[0102] It is further pointed out that the contact tips comprising the continuous or discontinuous peripherally protruding element may also further be made of multilayers of materials suitable to maximize the penetration ability of the tip itself, as well as to ensure a minimization of material retention, in particular further to the penetration into the three-dimensional contact structures or in possible oxide layers being on planar contact structures, such as the pads of the device under test. Suitably, said contact tips may also be equipped, at the peripherally protruding element, with a coating of a second conductive material having higher hardness than a hardness of the first conductive material forming the contact probe and thus the contact tip, preferably arranged at the hollow part defined in the contact tip, said coating delaying the consumption of the peripherally protruding element and thus extending the useful life of the contact probe, meanwhile allowing to further reduce the accumulation of material inside the hollow part of the contact tip during its penetration into contact structures of the device under test.

[0103] Suitably, the peripherally protruding element, or its single protruding elements, may be made by a plurality of conductive layers of different heights, the layer having greater height being preferably made of the second conductive material and being arranged at the hollow part, so as to increase the penetrative ability of said peripherally protruding element or of the single protruding elements that make it up, while limiting its consumption over time and reducing the accumulation of material inside the hollow part of the contact tip thus obtained.

[0104] Obviously, a person skilled in the art, in order to satisfy contingent and specific requirements, may make to the contact probe above described numerous modifications and variations, all included in the scope of protection of the invention as defined by the following claims.

[0105] For instance, it is possible to combine different ones of the illustrated embodiments to get closer and closer to a crown shape of the widely used pogo pin tips, while ensuring a constant section also further to touch on abrasive cloths, as well as a reduction of any material retained within the contact tip following testing of the device under test. In particular, it would be possible to make a contact tip equipped with a peripherally protruding element comprising single protruding elements positioned both at side walls of the contact probe and at edges thereof, as well as a base equipped with reliefs.

[0106] Furthermore, it is possible to make the contact probe by means of a multilayer and to make the contact tip of only one material or vice versa.

[0107] Finally, it is possible to use one of the embodiments above illustrated to make the contact head of the probe, i.e. the end portion configured to contact a space transformer or generically a board for the connection with a testing apparatus.