Probe head for electronic devices and corresponding probe card

Abstract

A probe head for a test equipment of electronic devices comprises a plurality of contact probes inserted in guide holes provided in at least one upper guide and one lower guide, a bending area for the contact probes being defined between the upper and lower guides, each contact probe having at least one first terminal portion which protrudes of a first length from the lower guide and ends with a contact tip (22A) adapted to abut onto a respective contact pad of a device to be tested, as well as a second terminal portion which protrudes of a second length from the upper guide and ends with a contact head adapted to abut onto a contact pad of a board for connecting or interfacing with the test equipment, suitably comprising at least one protection structure projecting from the upper guide in direction of a longitudinal development axis of the contact probes towards the board, the protection structure thus extending in correspondence of the contact heads of the contact probes.

Claims

1. A probe head for a test equipment of electronic devices, able to test devices provided with a plurality of contact pads by connecting them with corresponding contact pads of a board for connecting or interfacing with the test equipment, the probe head comprising: at least one upper guide and one lower guide, provided with respective guide holes; a plurality of contact probes developed along a longitudinal development axis and inserted in the guide holes of the upper and lower guides, and a bending area for the contact probes defined between the upper and lower guides, wherein each of the contact probes has: at least one first terminal portion which protrudes of a first length from the lower guide and ends with a contact tip adapted to abut onto a respective contact pad of the device to be tested, and a second terminal portion which protrudes of a second length from the upper guide and ends with a contact head adapted to abut onto a contact pad of the board for connecting or interfacing with said test equipment, the probe head further comprising at least one protection structure projecting from the upper guide in direction of the longitudinal development axis of the contact probes towards said board, the protection structure thus extending in correspondence of the contact heads of the contact probes.

2. The probe head according to claim 1, wherein the protection structure is fastened to the upper guide.

3. The probe head according to claim 2, wherein the fastening of the protection structure is in a removable manner.

4. The probe head according to claim 2, wherein the protection structure is fastened to said upper guide by means of an adhesive glue layer, a welding or fastening means selected from screws or clips, which at least partially cross the protection surface and the upper guide.

5. The probe head according to claim 1, wherein the protection structure is provided by projecting portions of the upper guide in the direction of the longitudinal development axis of the contact probes towards the board.

6. The probe head according claim 1, wherein the protection structure comprises a plurality of individually detachable layers which are stacked one upon another between the board and the upper guide. The probe head according to claim 6, wherein the protection structure comprises an adhesive material or removable coupling means adapted to make the layers integral with each other.

8. The probe head according to claim 7, wherein the protection structure comprises a glue with low seal as adhesive material.

9. The probe head according to claim 1, wherein the protection structure has a shape selected from a frame, pairs of half-frames, single projecting elements such as pillars.

10. The probe head according to claim 1, wherein the protection structure and layers thereof, if any, are provided so as to protrude with respect to the upper guide or the board.

11. The probe head according to claim 1, wherein the protection structure and layers thereof, if any, are provided so as to protrude with respect to the upper guide and the board.

12. The probe head according to claim 1, wherein the protection structure and layers thereof, if any, are made of transparent or semitransparent plastic material, or ceramic material, or metallic material or organic material or silicon.

13. The probe head according to claim 1, wherein the upper guide and/or a lower guide includes a pair of elementary supports and is provided with a spacer structure positioned between the elementary supports.

14. The probe head according to claim 13, wherein the spacer structure is fastened to one of the elementary supports, or it is provided by projecting portions thereof, or it comprises a plurality of overlapping and individually removable layers.

15. The probe head according to claim 13, wherein the spacer structure is fastened to one of the elementary supports in a removable manner.

16. The probe head according to claim 1, wherein the protection structure has a height equal to or greater than one of the greatest among all heights of enlarged portions of the contact heads of the contact probes.

17. The probe head according to claim 1, wherein the protection structure has a height equal to or greater than one of the greatest among all heights of tapered portions of the contact heads of the contact probes.

18. A probe card for a test equipment of electronic devices, able to test devices provided with a plurality of contact pads by connecting them with corresponding contact pads of a board for connecting or interfacing with the test equipment, comprising: at least one probe head comprising: at least one upper guide and one lower guide, provided with respective guide holes; a plurality of contact probes developed along a longitudinal development axis and inserted in the guide holes of the upper and lower guides, and a bending area for the contact probes defined between the upper and lower guides, and at least one board for connecting and interfacing with the test equipment, wherein each of the contact probes has: at least one first terminal portion which protrudes of a first length from the lower guide and ends with a contact tip adapted to abut onto a respective contact pad of the device to be tested, and a second terminal portion which protrudes of a second length from the upper guide and ends with a contact head adapted to abut onto a contact pad of the board for connecting or interfacing with said test equipment, the probe head further comprising at least one protection structure projecting from the upper guide in direction of the longitudinal development axis of the contact probes towards said board, the protection structure thus extending in correspondence of the contact heads of the contact probes.

19. The probe card according to claim 18, further comprising holding means adapted to make integral the guides of the probe head, the protection structure being provided with suitable housing seats for the holding means.

20. The probe card according to claim 18, wherein the upper guide and/or the lower guide includes a pair of elementary supports and is provided with a spacer structure positioned between the elementary supports, the probe card further comprising holding means adapted to make integral the elementary supports of the probe head, the elementary supports and/or the protection structure being provided with suitable housing seats for the holding means.

21. A probe head for a test equipment of electronic devices, able to test devices provided with a plurality of contact pads by connecting them with corresponding contact pads of a board for connecting or interfacing with the test equipment, the probe head comprising: at least one upper guide and one lower guide, provided with respective guide holes; a plurality of contact probes developed along a longitudinal development axis and inserted in the guide holes of the upper and lower guides, and a bending area for the contact probes defined between the upper and lower guides, wherein each of the contact probes has: at least one first terminal portion which protrudes of a first length from the lower guide and ends with a contact tip adapted to abut onto a respective contact pad of the device to be tested, and a second terminal portion which protrudes of a second length from the upper guide and ends with a contact head adapted to abut onto a contact pad of the board for connecting or interfacing with said test equipment, the probe head further comprising at least one protection structure projecting from the upper guide in direction of the longitudinal development axis of the contact probes towards the board, and the protection structure being provided by projecting portions of the upper guide in the direction of the longitudinal development axis of the contact probes towards the board, the protection structure being made in one piece with the upper guide.

22. The probe head according claim 21, wherein the protection structure comprises at least a fixed portion being made in one piece with the upper guide with a height equal or greater than the height of the contact heads of the contact probes and a further portion with individually removable layers.

23. The probe head according claim 22, wherein the further portion of the protection structure comprises a plurality of individually detachable layers which are stacked one upon another between the board and the upper guide.

24. The probe head according to claim 23, wherein the further portion of the protection structure comprises an adhesive material or removable coupling means adapted to make said layers integral with each other.

25. The probe head according to claim 21, wherein the protection structure has a shape selected from a frame, pairs of half-frames, single projecting elements such as pillars.

26. The probe head according to claim 21, wherein the protection structure and layers thereof, if any, are made of transparent or semitransparent plastic material, or ceramic material, or metallic material or organic material or silicon, preferably of Kapton™.

27. The probe head according to claim 21, characterized by comprising the upper guide and/or a lower guide (24) including a pair of elementary supports and provided with a spacer structure positioned between the elementary supports.

28. The probe head according to claim 27, wherein the spacer structure is fastened to one of the elementary supports, or it is provided by projecting portions thereof, or it comprises a plurality of overlapping and individually removable layers.

29. A probe card for a test equipment of electronic devices, able to test devices provided with a plurality of contact pads by connecting them with corresponding contact pads of a board for connecting or interfacing with the test equipment, comprising: at least one probe head comprising: at least one upper guide and one lower guide, provided with respective guide holes; a plurality of contact probes developed along a longitudinal development axis and inserted in the guide holes of the upper and lower guides, and a bending area for the contact probes defined between the upper and lower guides, and at least one board for connecting and interfacing with the test equipment, wherein each of the contact probes has: at least one first terminal portion which protrudes of a first length from the lower guide and ends with a contact tip adapted to abut onto a respective contact pad of the device to be tested, and a second terminal portion which protrudes of a second length from the upper guide and ends with a contact head adapted to abut onto a contact pad of the board for connecting or interfacing with said test equipment, the probe head further comprising at least one protection structure projecting from the upper guide in direction of the longitudinal development axis of the contact probes towards the board, and the protection structure being provided by projecting portions of the upper guide in the direction of the longitudinal development axis of the contact probes towards the board, the protection structure being made in one piece with the upper guide.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0050] FIG. 1: schematically shows a probe card of electronic devices, in particular integrated on wafer, provided according to the prior art;

[0051] FIG. 2: schematically shows a section view of a probe head, provided according to an embodiment of the disclosure; and

[0052] FIGS. 3A-3C, 4A-4C, 5A-5D, 6 and 7: schematically show in respective section views a probe card comprising alternative embodiments of the probe head of the disclosure.

DETAILED DESCRIPTION

[0053] With reference to these figures, and in particular to FIG. 2, a probe head according to the disclosure is globally indicated with 21.

[0054] It should be noted that the figures represent schematic views and are not drawn to scale, but are instead drawn in such a way as to emphasize the important features of the disclosure. It is further pointed out that measures shown with reference to a particular embodiment can obviously be used in combination with other embodiments. Finally, the same numeral references are used in the different figures to indicate structurally and functionally corresponding elements.

[0055] The probe head 21 includes a plurality of contact probes 22 housed in suitable guide holes of respective supports or an upper guide 23 and a lower guide 24, that are plate-like and parallel. The probe head 21 also comprises a containment element or case 25 extended between the upper guide 23 and the lower guide 24, at an air area or bending area 26, having a height indicated with L, where the contact probes 22 can be further deformed in case of the pressing contact of the probes on a device to be tested, usually contained in a semiconductor wafer, onto which the probe head 21 abuts, at a first plane indicated in the figure with π1.

[0056] In particular, the probe head 21 illustrated in FIG. 2 is of the non-blocked vertical probe type and the contact probes 22 each have respective terminal portions 21A and 21B adapted to make a mechanical and electrical contact with respective contact pads; in particular a first terminal portion 21A ends with a contact tip 22A adapted to abut onto a contact pad of the device to be tested at the first plane π1, whereas a second terminal portion 21B ends with a contact head 22B adapted to abut onto a further contact pad of a connection element towards a test equipment, such as a layer of spatial transformation or space transformer or a generic connection or interface PCB, at a second plane indicated in the figure with 72. In this way, the contact probes 22 provide for the mechanical and electrical contact between the device to be tested and a test equipment (not shown) of which the probe head 21 is a terminal element. The contact probes 22 also have a substantially rod-like probe body 22C extended between said first and second end portions, 21A and 21B.

[0057] The term “terminal portion” means a part of the contact probes 22 which protrudes with respect to the guides and therefore to the case 25, in particular in the direction of the device to be tested or of the PCB of the probe card which comprises the probe head 21, respectively. Furthermore, like previously pointed out, the term tip indicates an end portion, not necessarily pointed.

[0058] In particular, the first terminal portion 21A of the contact probes 22 at the contact tip 22A extends below the lower guide 24 of the probe head 21, in the direction opposite to the longitudinal development axis of the probe indicated with z in the local reference of the figure. Likewise, the second terminal portion 21B of the contact probes 22 at the contact head 22A extends above the upper guide 23 of the probe head 21, in the direction of the longitudinal development axis z.

[0059] As previously described, the contact probes 22 have a first terminal portion 21A comprising the contact tip 22A having a tapered shape so as to make a substantially point-like contact on the contact pads of the device to be tested. Furthermore, the contact probes 22 have a second terminal portion 21B comprising the contact head 22B provided with at least one enlarged portion, that is, having a transverse diameter D2 of greater dimensions than a transverse diameter D1 of the rest of the second terminal portion 21B and in general of the probe body 22C, whereby diameter refers to a maximum transverse dimension of a section of said portion orthogonal to a longitudinal development axis z of the contact probe 22; the contact head 22B is further tapered so as to make a substantially point-like contact on the pads of the PCB of the probe card which comprises the probe head 21. The contact head 22B, thanks to its enlarged portion, also has respective undercut walls adapted to rest on the upper guide 23, realizing the desired holding of the contact probe 22 inside the probe head 21 even in the event of no contact of said probe head 21 with a device to be tested.

[0060] Precisely the presence of such an enlarged portion at the contact head 22B of the contact probes 22 increases the problems tied to the correct containment and freedom of movement of the contact probes 22 inside the probe head 21. As already explained, during the operation of said probe head 21, i.e. in case of a test operation of a device integrated on a semiconductor wafer, the contact probes 22 undergo a bending and a deformation when their contact tips 22A abuts onto the pads of the device to be tested and their contact heads 22B abut onto corresponding contact pads of a PCB or of a space transformer of the probe card which comprises said probe head 21; during said contact, the contact probes 22 but also the entire probe head 21 are substantially pushed up, that is towards the test equipment, according to the direction of the longitudinal development axis z in the figure.

[0061] Suitably, the probe head 21 according to an embodiment of the present disclosure therefore comprises at least one protection structure 27 projecting from the upper guide 23 in the direction of the test equipment, that is in the direction of the longitudinal development axis z indicated in the figure. The protection structure 27 therefore extends at the contact heads 22B, which protrude from the upper guide 23 precisely according to the direction of the longitudinal development axis z.

[0062] In particular, the protection structure 27 has a height H1 equal or preferably greater than a corresponding height HB (H1≥HB) of the contact heads 22B starting from their enlarged portions up to the substantially point-like end of real contact. More specifically, the height HB of each individual contact head 22B is measured from the undercut walls Sq, i.e. from the section of maximum diameter, to the tapered end that forms the real contact area, i.e. the section of minimum diameter, substantially point-like. Furthermore, the height H1 of the protection structure 27 is selected so as to be equal or preferably greater than the greatest among all heights of the contact heads 22B of the contact probes 22; in this way the protection structure 27 is able to correctly protect all the contact heads 22B of the contact probes 22 of the probe head 21.

[0063] It is pointed out that, although not illustrated in the figures, the probe head 21 can also comprise contact probes 22 with second terminal portions 21B provided with non-enlarged contact heads 22B. In this case, the protection structure 27 is used to avoid an excessive approach of the contact heads 22B, in particular of the real area of contact with the upper guide 23, which approach might cause an interlocking of the contact heads 22B in the respective upper guide holes 23H, with consequent malfunction of the probe head 21 as a whole, in particular due to the lack of contact with the PCB for connecting and interfacing with the test equipment. In this case, the height H1 of the protection structure 27 is selected so as to be greater than a tapered portion of the second terminal portion 21B which forms the contact head 22B or in any case such as to avoid an interlocking of the contact head 22B in the corresponding upper guide hole 23H which houses it in the upper guide 23; also in this case, the height H1 of the protection structure 27 is determined so as to be equal or preferably greater than one of the greatest among all heights of tapered portions of the contact heads 22B of the contact probes 22.

[0064] The protection structure 27 is fastened in a more or less removable manner to the upper guide 23, for example by means of an adhesive glue layer, by welding or with fastening means such as screws or clips, which at least partially cross the protection surface 27 and the upper guide 23.

[0065] Such a protection structure 27 can be substantially shaped as a frame or comprise one or more portions, at areas of the upper guide 23 not crossed by guide holes and therefore by the contact probes 22, all projecting from the upper guide 23 in the direction of the longitudinal development axis z.

[0066] FIG. 3A shows the probe head 21 mounted on a probe card 20, which also comprises a space transformer or generally a PCB 28 for connecting and interfacing with a test equipment (not illustrated). In particular, the PCB 28 comprises a plurality of contact pads 28A onto which the contact heads 22B of the contact probes 22 abut. The probe card 20 is adapted to abut with its probe head 21 onto a device to be tested 30, in particular integrated on a semiconductor wafer 30′, and provided with a corresponding plurality of contact pads 30A onto which the contact tips 22A of the contact probes 22 abut.

[0067] As already indicated, during the testing operations carried out by the probe card 20, i.e. when the probe head 21 is in pressing contact onto the device to be tested 30 and onto the PCB 28, the contact probes 22 bend at the bending area 26, which extends between the upper guide 23 and the lower guide 24 and has a length L, corresponding to the height of the case 25.

[0068] The first terminal portion 21A of the contact probes 22 at the contact tip 22A extends in a first area ZA between the lower guide 24 and the device to be tested 30; in particular, the contact tip 22A protrudes of a suitable first length LA with respect to the lower guide 24 of the probe head 21, with reference to a plane π1 determined by the wafer 20′ of the device to be tested 30 in pressing contact with said probe head 21, corresponding to the length of the first area ZA. Said first area ZA allows a movement of the contact tips 22A of the contact probes 22 on the contact pads 30A of the device to be tested 30 during the operation of the probe head 21 and of the probe card 20 which comprises it and is therefore indicated as scrub area ZA.

[0069] Likewise, the second terminal portion 21B of the contact probes 22 at the contact head 22B extends in a second area ZB between the upper guide 23 of the probe head 21 and the PCB 28; in particular, the contact head 21B protrudes of a suitable second length LB with respect to said upper guide 23, with reference to a plane π2 of the PCB 28 in pressing contact with the probe head 21, in a similar way to the device to be tested 30, corresponding to the length of the second area ZB. Said second area ZB allows a movement of the contact heads 22B of the contact probes 22 during the operation of the probe head 21 and of the probe card 20 which comprises it and is therefore indicated as the floating area ZB.

[0070] Substantially, FIG. 3A shows the probe head 21 in operating conditions, i.e. during a test phase of the device to be tested 30 integrated in the wafer 30′, when the contact probes 22 contained therein each have the contact tip 22A in pressing contact with a contact pad 30A of said device to be tested 30 and the contact head 22B in pressing contact with a contact pad 28A of the PCB 28; in the example of the figure, the protection structure 27 is in turn in contact with the PCB 28.

[0071] It is pointed out that the protection structure 27 of the probe head 21 therefore allows the length LB of the floating area ZB to be kept constant, essentially acting as a spacer element between the contact heads 22B of the contact probes 22 and the PCB 28, so as to ensure a constant and correct contact with said PCB 28 and therefore with the test equipment of which the probe card 20 constitutes a terminal element, a contact made precisely by the contact heads 22B abutting onto the contact pads 28A of the PCB 28. Said protection structure 27 is also able to prevent contact probes 22, even without enlarged contact heads 22B, from interlocking in the upper guide holes 23H provided in the upper guide 23 and adapted to house them. Corresponding lower guide holes 24H are provided in the lower guide 24 to house the contact probes 22.

[0072] It is also possible to make the protection structure 27 by means of a suitable configuration of the upper guide 23, in particular by providing the same with projecting portions 23′ in the direction of the PCB 28, said projecting portions 23′ being able, for example, to be in the form of a frame or edge of the upper guide 23, extended outside an area of said upper guide 23 provided with the upper guide holes 23H and therefore adapted to house the contact probes 22 so as to guarantee the correct operation of the probe head 21 and of the probe card 20 which comprises it, as schematically illustrated in FIG. 3B. In this case, the protection structure 27 is made in one piece with the upper guide 23.

[0073] As illustrated in FIG. 3C, the protection structure 27 can also be made by means of a plurality of layers 27a, 27b, 27c, 27d, suitably stacked one upon another between the PCB 28 and the upper guide 23, individually detachable or peelable, so as to provide a protection structure 27 having a height H1 that can be modified. Said layers 27a, 27b, 27c, 27d are possibly made integral with each other by means of an adhesive material, such as a glue, with low seal, so as to easily allow the separation of the same from each other.

[0074] The protection structure 27 illustrated in FIG. 3C comprises four layers, by way of non-limiting example only, said structure being able to comprise any number of layers, possibly even just one, with equal or different thickness.

[0075] Such an embodiment proves to be particularly convenient. In fact, it is well known that the first terminal portion 21A reduces its length LA as the probe head 21 is used, by virtue of the passages of its contact tips 22A on the abrasive cloth, as explained above. Basically, the first terminal portion 21A wears out during each cleaning operation of the corresponding contact tip 22A, reducing the length LA of the scrub area ZA, until the probe head 21 can no longer work correctly.

[0076] Suitably according to the present embodiment, the protection structure 27 can be reduced in height by eliminating one or more layers 27a, 27b, 27c, 27d, which reduces the length LB of the floating area ZB, thus allowing a displacement towards the other of the assembly upper guide 23-lower guide 24-case 25, that is of the probe head 21, allowing the contact probes 22 housed therein to protrude more from the lower guide 24 and consequently increasing the length LA of the scrub area ZA.

[0077] The protection structure 27, in particular the number or height of its layers 27a, 27b, 27c, 27d is sized so as to have a height H1 that is sufficiently greater than the height HB of the contact head 22B, so as to be able to guarantee the correct containment of the contact heads 22B and in particular a sufficient length LB of the floating area ZB, even after the elimination of one or more of the layers 27a, 27b, 27c, 27d of the protection structure 27.

[0078] According to an alternative embodiment, not illustrated in the figures, the protection structure 27 comprises at least a fixed portion with a height equal or greater than the height HB of the contact heads 22B and a further portion with individually removable layers. In this way, it is ensured that the height H1 of the protection structure 27 is always greater than or equal to the height HB of the contact heads 22B even after the elimination of all the removable layers.

[0079] The protection structure 27 and layers 27a-27d thereof, if any, are made of transparent or semitransparent plastic material, or ceramic material, or metallic material or organic material or silicon, preferably of Kapton®. Furthermore, the layers can be made integral with each other, for example by means of a layer of adhesive material, preferably with low seal, or by means of further removable coupling means, such as screws or clips.

[0080] In the embodiment illustrated in FIG. 3C, again by way of example, the protection structure 27 and the individual layers thereof 27a-27d are made in the form of a frame. It is also possible to make the protection structure 27 in the form of pairs of half-frames, extended substantially along opposite and parallel sides of the probe head 21 and of the upper guide 23.

[0081] Although not illustrated in the figures, it is pointed out that the protection structure 27 and layers 27a-27d, if any, thereof can also be made so as to protrude with respect to the upper guide 23 and/or the PCB 28.

[0082] The protection structure 27 can also take on a totally different shape, such as for example one or more individual pillars positioned on the upper guide 23 also within the housing area of the contact probes 22, in areas without the corresponding upper guide holes 23H, as schematically illustrated in FIG. 4A. In the example of the figure, the protection structure 27 comprises a pair of pillars which extend between the upper guide 23 and the PCB 28 in areas not occupied by the contact probes 22.

[0083] Also in this case, the protection structure 27 projects from the upper guide 23 in the direction of the test equipment and is fastened to said guide in a more or less removable manner, for example by means of a layer of adhesive glue, by welding or by fastening means such as screws or clips which cross at least partially the protection structure 27 and the upper guide 23. Furthermore, like previously, the protection structure 27 has a height H1 equal to or preferably greater than a corresponding height HB (H1≥MB) corresponding to the overall volume of the contact heads 22B with their enlarged portions, always intended as the greatest among the heights of the individual contact heads 22B of the contact probes 22 housed in the probe head 21. Alternatively, the height H1 of the protection structure 27 is established in such a way as to avoid an interlocking of the contact head 22B in the corresponding upper guide holes 23H of the upper guide 23, in particular when an enlarged portion is not present.

[0084] Like previously, it is also possible to make said protection structures 27 by means of a suitable configuration of the upper guide 23, in particular by providing it with projecting portions 23′ in the direction of the PCB 28, as schematically illustrated in FIG. 4B, or by means of a plurality of individually detachable or peelable layers 27a, 27b, 27c, suitably stacked one upon another between the PCB 28 and the upper guide 23, as illustrated in FIG. 4C, where the protection structure 27 comprises a single pillar formed by three layers only by way of example.

[0085] It is also well known that in vertical probe heads of the “buckling beam” type, as illustrated in the figures, the contact probes 22 show significant problems of friction inside the respective guide holes, which can make the sliding of the probes inside them difficult or even prevent it.

[0086] The shortening of the first terminal portion 21A of the contact probes 22 due to the cleaning operations increases the chances of the probes getting interlocked in the corresponding lower guide holes; in a similar way, an approach of the upper guide 23 to the PCB 28 and therefore a decrease in the length LB of the floating area ZB increases the risk of the contact probes 22 of getting interlocked in the upper guide holes 23H, in particular when there are no enlarged contact head 22B.

[0087] Suitably it is possible to obtain a decrease in said sliding friction of the probes thanks to the use of a plurality of elementary supports, preferably two, parallel to each other to form at least one of the upper and/or lower guides of the probe head, as schematically illustrated in the FIGS. 5A-5D.

[0088] For example, as in the embodiment illustrated in FIG. 5A, the probe head 21 can comprise an upper guide 23 formed by a pair of elementary supports, an upper elementary support 23A and a lower elementary support 23B, that are plate-like and parallel, separated by at least one upper air area ZU having a length LU.

[0089] The probe head 21 also comprises in this case a protection structure 27 projecting from the upper guide 23, in particular from its upper elementary support 23A in the direction of the PCB 28, while the bending area 26, where the contact probes 22 may further deform, in case of the pressing contact of the probes onto the device to be tested 30, is defined between the lower elementary support 23B and the lower guide 24.

[0090] Suitably, the probe head 21 also comprises an upper spacer structure 27u with height H2 positioned between the elementary supports of the upper guide 23, thus ensuring that the distances between them and therefore the length LU of the upper air area ZU, as schematically illustrated in FIG. 5A, is maintained.

[0091] It is also possible to provide the upper spacer structure 27u by means of a suitable configuration of the lower elementary support 23B of the upper guide 23, in particular by providing it with projecting portions 23B′ in the direction of the upper elementary support 23A and therefore of the PCB 28, as schematically illustrated in FIG. 5B, or by means of a plurality of individually detachable or peelable layers, suitably stacked one upon another between the upper elementary support 23A and the lower elementary support 23B, as illustrated in FIG. 5C, where the upper spacer structure 27u comprises three layers only by way of example and has a height such as to guarantee the desired length LU for the upper air area ZU.

[0092] Suitably, the upper spacer structure 27u made by means of a plurality of individually peelable layers can be used, as previously explained for the layered protection structure 27, to adjust the lengths of the floating area ZB and of the scrub area ZA, without modifying the length L of the bending area 26 defined between the lower elementary support 23B of the upper guide 23 and the lower guide 24.

[0093] In a preferred embodiment, schematically illustrated in FIG. 5D, the probe head 21 can comprise both a protection structure 27 and an upper spacer structure 27u made by means of a plurality of individually and independently removable or peelable layers.

[0094] The considerations just made can also be applied if the lower guide 24 is formed by a pair of elementary supports, 24A and 24B, separated by a lower spacer structure 27I with height H3, which defines a lower air area ZL having a length LL, as schematically illustrated in FIG. 6, and in case both guides are, the probe head therefore comprising two pairs of elementary supports 23A, 23B and 24A, 24B and two spacer structures 27u and 27I with respective heights H2 and H3, in addition to a protection structure 27 of the contact heads 22B of the contact probes 22, as schematically illustrated in FIG. 7.

[0095] Also for said alternative embodiments, it is possible to provide one or more of the structures as described above, combining the solutions with each other according to the application needs of the probe head 21 and of the probe card 20 which comprises it.

[0096] It is pointed out that the different layers of the protection structures 27 and of the spacer structures 27u and/or 27I can be made so as to have portions protruding from the probe head 21, preferably with different lengths, so as to facilitate the correct removal thereof. Suitably, said protruding portions have equal lengths for corresponding layers of the different structures, for example the protruding portion of the layer that is the closest to the PCB 28 has the same minor length as the one of the subsequent layers, gradually closer to the guide or support positioned below said structure, considering the local reference of the figures. It is also possible to provide for a numbering for said layers, for example with numbering gradually increasing, said numbering being applied in the protruding portion of the layer so as to be visible and to make it possible to verify that all the structures comprise the desired number of layers simply by reading said numbering on all the protruding potions of the layers.

[0097] Asymmetrical removals of said layers can also allow to modify the relative distances between the supports and/or the guides, in particular causing an inclination of the same so as to compensate for any production or assembly inaccuracies of the supports and guides.

[0098] The probe card 20 also comprises respective holding means (not illustrated), adapted to integrate the various components of said board, in particular the elementary guides and/or supports, as well as the protection structures 27 and the spacer structures 27u and 27I, provided for said purpose with suitable housing seats for holding means. Said holding means can also be used to make the PCB 28, that is a space transformer, and the case 25 integral with each other.

[0099] It is pointed out that all the illustrated embodiments of the probe head and of the probe card according to the present disclosure allow an adjustment of the length of the terminal portion of the contact probes comprising the contact tips and therefore subject to consumption without modifying the length of the bending area of the probes themselves and therefore the movement dynamics of the same, in particular in terms of scrub as well as ensuring the constant maintenance of the floating area for the contact heads of the contact probes, so as to ensure a constant and correct contact with the PCB or the space transformer and therefore the test equipment, said floating area being maintained with a constant and unchanged length in case of the length of the contact tips of the contact probes being adjusted.

[0100] Furthermore, the presence of the protection structures allows to maintain a suitable distance between the upper guide and the PCB associated with the probe head, so as to guarantee the protection and correct holding of the contact probes and in particular of their contact heads possibly provided with enlarged portions.

[0101] In conclusion, the probe head according to the embodiments of the disclosure has a longer duration, since it is possible to provide for a large number of cleaning operations of the corresponding tip with a subsequent adjustment of the length of the terminal portions of the contact probes which protrude with respect to the lower guide so that it is equal to or greater than a length corresponding to a correct operation of the probe head, always ensuring the correct containment of the further terminal portions comprising the contact heads. In this way, the useful life of the probe card comprising such a head is also extended.

[0102] Suitably, the protection structure of said contact heads can be made in such a way as to extend over limited areas, even if severely limited, with respect to the extension of the guides, thus being positionable at will, both in number and position.

[0103] Furthermore, it is possible to make further adjustments to the length of the terminal portions of the contact probes at different times in the life of the probe head which includes them, in particular whenever said terminal portions comprising the contact tips have shortened due to use and cleaning and have a length smaller than a length corresponding to a correct operation of the probe head, also allowing to modify the length of the terminal portions in a different way for different contact probes in case of a misalignment of the respective contact tips due to the tolerances of the process for making the probes themselves.

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

[0105] In particular, it is obviously possible to consider geometric shapes other than those illustrated by way of example in the figures.

[0106] Furthermore, it is possible to provide the contact probes of the probe head according to the embodiments of the present disclosure with further measures, such as particular conformations for the tip portion, such as offsets or elongated portions, as well as for the body, like stoppers projecting therefrom.

[0107] Finally, the contact probes can be made by means of multilayer combinations of conductive, semiconductive or insulating materials, both in planar overlap and in concentric or coaxial manner; multilayer solutions are also possible in order to provide the guides and/or supports included in the probe head according to the embodiments of the present disclosure.

[0108] From the foregoing it will be appreciated that, although specific embodiments of the disclosure have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the disclosure.

[0109] The various embodiments described above can be combined to provide further embodiments. These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.