Probe head with improved configuration

Abstract

A probe head (100) for testing an electronic device is described herein, the probe head comprising at least one contact probe (10) having a body (10') extending between a first end (10a) and a second end (10b), the ends (10a, 10b) being configured to contact respective contact pads (20a, 30b); a first guide (40a) having a first guide hole (40ah) and a second guide (40b) having a second guide hole (40bh). The contact probe (10) comprises at least one elastically flexible intermediate section (10s) positioned between a first end (10a) and a second end (10b), the elastically flexible intermediate section (10s) positioned in at least one of a first guide hole (40ah) and a second guide hole (40bh), and the contact probe (10) further comprises an intermediate stopping means positioned between the first guide (40a) and the second guide (40b), the intermediate stopping means being configured to mechanically contact at least a portion of the first guide (40a) and / or the second guide (40b) to hold the contact probe (10) within the probe head (100).

Description

Technical Field

[0001] The present invention relates to a probe head configured to perform tests on electronic devices integrated on a semiconductor wafer, such as high-frequency devices. The following description is presented with reference to its application fields only for the purpose of simplifying the description of the present invention.

Background Art

[0002] As is well known, a probe head is essentially a device configured such that a plurality of contact pads, i.e., a plurality of pads of a micro-structure, particularly an electronic device integrated on a semiconductor wafer, are electrically contacted to corresponding channels of a test apparatus that performs a functional test thereon.

[0003] Tests performed on integrated circuits are particularly useful for detecting and isolating defective circuits at an early stage of the manufacturing process. Therefore, usually, a probe head is used to test these circuits before cutting the circuits integrated on a wafer and assembling them into a chip encapsulation package.

[0004] A probe head essentially comprises a plurality of contact probes housed in a pair of supports or guides that are substantially plate-shaped and parallel to each other. These plate-shaped supports are provided with appropriate guide holes and are spaced apart from each other to leave a free region or gap for the movement and possible deformation of the contact probes. The contact probes are usually formed by wires of a special alloy having good electrical and mechanical properties.

[0005] The contact probe usually extends between a first end intended to contact a pad of a device under test and a second end intended to contact a space transformer or a printed circuit board (PCB).

[0006] The correct operation of a probe head is fundamentally related to two parameters: the vertical movement (or overtravel) of the contact probe, and the horizontal movement (or scrub) of the contact tip of these probes on the pad while in contact with the device under test. All of these characteristics must be evaluated and calibrated during the manufacturing of the probe head, and a good electrical connection between the contact probe and the device under test must always be ensured. Therefore, ensuring proper contact of the contact probe with various pads during testing is particularly important.

[0007] Generally, the maximum overtravel of a contact probe is equal to the dimension of the probe portion that protrudes relative to the lower guide. This protrusion retracts into the lower guide upon contact with the device under test due to bending or deformation of the probe itself. However, the height of this protrusion is limited by the mechanical resistance of the probe and is usually low. It should also be added that the maximum overtravel of a probe is only theoretically achievable, as problems related to probe interlocking and deformation arise even at much smaller overtravel levels.

[0008] According to some known solutions, pre-deformed contact probes are manufactured, but these solutions have various drawbacks, such as difficulty in maintenance, the need for special means to hold the probe, and of course, interlocking problems during testing. Another problem with these known solutions is related to contact pad wear caused by the probe itself.

[0009] Furthermore, in the past, extremely short probes were manufactured to ensure optimal performance even for high-frequency testing. In this case, probe length becomes a significant issue, particularly due to the self-inductance phenomenon. However, shortening the probe body significantly increases the rigidity of the probe itself, increasing the force exerted on various pads by each contact tip. This can lead to pad failure, potentially causing irreparable damage to the device under test. The increased rigidity of the contact probe due to its shortened length also increases the risk of the probe itself breaking. Therefore, even in this case, a contact probe that can ensure improved contact during testing is necessary.

[0010] The technical problem of the present invention is to devise a probe head having structural and functional features that can overcome the limitations and drawbacks that still affect known solutions, in particular, that can ensure improved control of the contact force of the contact probe and, at the same time, proper retention of the contact probe.

[0011] Another second objective is to ensure proper contact between the contact probe and the metallization formed on the guide. [Overview of the project]

[0012] The underlying solution idea of ​​the present invention is to create a probe head in which the contact probe undergoes elastic deformation during testing, preferably mainly in the longitudinal direction (though not necessarily), and the contact probe has an elastically flexible (or pliable) intermediate section, so that these contact probes function substantially as an elastic spring. A pair of intermediate guides are provided, and between the pair of intermediate guides, appropriate stopping means for the contact probe are housed for optimal retention of the contact probe, and the elastically flexible intermediate section is located in one or both of the intermediate guides.

[0013] Based on the idea of ​​this solution, the above technical problem is solved by the following probe head for testing electronic devices, the probe head comprising: at least one contact probe having a body extending between a first end and a second end, the ends of which are configured to contact the respective contact pads; one first guide having each first guide hole; and at least one second guide having each second guide hole. The contact probe comprises at least one intermediate section positioned between the first end and the second end and being elastically flexible or pliable (for example, at least along the longitudinal axis of the probe), the elastically flexible intermediate section being positioned in at least one of the first guide hole or the second guide hole; the contact probe further comprises an intermediate stopping means positioned between the first guide and the second guide, the intermediate stopping means being configured to mechanically contact at least a portion of the first guide and / or the second guide in order to hold the contact probe within the probe head.

[0014] More specifically, the present invention comprises the following additional and optional features individually or in combination as appropriate.

[0015] According to one aspect of the present invention, the probe head may comprise a plurality of contact probes and a plurality of respective guide holes, and may further comprise a conductive portion formed on a first guide and / or a second guide, the conductive portion comprising at least one group of the first guide holes or the second guide holes, and configured to contact and short-circuit a corresponding group of contact probes housed in such group of holes and intended to transmit a predetermined type of signal, thereby forming a predetermined conductive domain, with at least a portion of the contact probes in contact with the conductive portion.

[0016] According to one aspect of the present invention, the conductive portion can be formed on the surface of the first guide and / or the second guide.

[0017] According to one aspect of the present invention, the probe head may comprise a plurality of conductive portions corresponding to a plurality of conductive domains, these conductive portions being arranged on the same plane of the first guide and / or the second guide, on opposite planes of the first guide and / or the second guide, or in any other suitable configuration.

[0018] According to one aspect of the present invention, the intermediate stopping means may include an intermediate stopper having a body with a lateral extension that defines at least one shoulder portion configured to contact the surface of a first guide and / or a second guide by its contact surface (generally, the stopper bonded to the probe body may have a lateral extension larger than that of the guide hole in order to properly hold the contact probe).

[0019] According to one aspect of the present invention, contact of the contact probe with the conductive part can be by pressing contact with one or more contact surfaces of at least one shoulder portion of the intermediate stopper, thereby causing an electrical connection between the contact probe and the conductive part.

[0020] According to one aspect of the present invention, the intermediate stopper may be provided with a plurality of projections protruding from at least one shoulder portion, which are configured to contact at least a portion of the conductive part, thereby causing an electrical connection between the contact probe and the conductive part.

[0021] According to one aspect of the present invention, the projection can be triangular in shape or can be defined by the surface irregularities of the intermediate stopper.

[0022] According to one aspect of the present invention, the probe head may be provided with a further stopper or upper stopper configured to abut against the upper surface of the second guide, which is the surface furthest from the device under test.

[0023] According to one aspect of the present invention, the intermediate stopping means may include a retaining element formed as an elastic hook, which is configured to elastically deform while inserting the contact probe through either a first guide hole or a second guide hole, and while withdrawing the contact probe through the other of the first and second guide holes. The retaining element is configured not to deform when housed between the first and second guides (i.e., after the probe head is assembled), and is configured to mechanically contact the first and / or second guides to hold the contact probe.

[0024] According to one aspect of the present invention, the intermediate stopping means may include an elastic film, such as a Kapton® sheet or Kapton® film, disposed between a first guide and a second guide.

[0025] According to one aspect of the present invention, the probe head may be provided with a first elastically flexible intermediate section in a first guide hole and a second elastically flexible intermediate section in a second guide hole, and the stopping means is positioned between the first elastically flexible intermediate section and the second elastically flexible intermediate section.

[0026] According to one aspect of the present invention, the first elastically flexible intermediate section may have a different elastic constant than the second elastically flexible intermediate section.

[0027] According to one aspect of the present invention, the first guide and the second guide can be positioned at an intermediate location between the semiconductor wafer and the interface board associated with the second end of the contact probe.

[0028] According to one aspect of the present invention, the first guide and the second guide are shiftable relative to each other with respect to the longitudinal axis of the contact probe.

[0029] According to one aspect of the present invention, the elastically flexible intermediate section can be at least partially extended along an axis that is not parallel (e.g., inclined) to the axis of symmetry of the first guide hole and / or the second guide hole, i.e., it can be non-linear with respect to other parts (e.g., end parts) of the contact probe, and this section can contact the wall of the guide hole.

[0030] According to another aspect of the present invention, the elastically flexible intermediate section can be structured as a plurality of elastic elements that are successively connected to each other such that the elastically flexible intermediate section is non-linear.

[0031] For example, at least two of the above elastic elements are offset from each other with respect to a reference axis that is orthogonal to, for example, the first guide and the second guide.

[0032] According to one aspect of the present invention, at least one of the above elastic elements can contact the wall of the guide hole.

[0033] According to one aspect of the present invention, both the first elastically flexible intermediate section and the second elastically flexible intermediate section are non-linear.

[0034] According to one aspect of the present invention, the intermediate stop means can project from only one wall of the contact probe.

[0035] The features and advantages of the probe head according to the present invention will become apparent from the following description of exemplary embodiments, which are shown by way of non-limiting examples, with reference to the accompanying drawings.

Brief Description of the Drawings

[0036] [Figure 1] A schematic diagram of a probe head is shown, in which at least one contact probe has an elastically flexible intermediate section. [Figure 2] The contact probes of probe heads according to various embodiments of the present invention are shown. [Figure 3] A schematic diagram of a probe head according to one embodiment of the present invention, which has two overlapping guide sections, is shown. [Figure 4] A schematic diagram of a probe head according to one embodiment of the present invention, assuming the presence of a lower guide and an upper guide, is shown. [Figure 5] A schematic diagram shows a probe head having a contact probe according to a different embodiment of the present invention, particularly one having a different geometry. [Figure 6] A schematic diagram shows a probe head having a contact probe according to a different embodiment of the present invention, particularly one having a different geometry. [Figure 6bis] A schematic diagram shows a probe head having a contact probe according to a different embodiment of the present invention, particularly one having a different geometry. [Figure 7] A schematic diagram shows a probe head having a contact probe according to a different embodiment of the present invention, particularly one having a different geometry. [Figure 7bis] A schematic diagram shows a probe head having a contact probe according to a different embodiment of the present invention, particularly one having a different geometry. [Figure 8] A schematic diagram shows a probe head having a contact probe according to a different embodiment of the present invention, particularly one having a different geometry. [Figure 8bis] A schematic diagram shows a probe head having a contact probe according to a different embodiment of the present invention, particularly one having a different geometry. [Figure 9] A schematic diagram shows a probe head having a contact probe according to a different embodiment of the present invention, particularly one having a different geometry. [Figure 10] A schematic diagram shows a probe head having a contact probe according to a different embodiment of the present invention, particularly one having a different geometry. [Figure 11] A schematic diagram shows a probe head having a contact probe according to a different embodiment of the present invention, particularly one having a different geometry. [Figure 12] A schematic diagram of a probe head according to one embodiment of the present invention, which assumes the presence of a conductive part for short-circuiting a group of probes, is shown. [Figure 13] The following schematic examples illustrate embodiments of the present invention in which the conductive portion is arranged in various ways on the guide of the probe head. [Figure 14] The following schematic examples illustrate embodiments of the present invention in which the conductive portion is arranged in various ways on the guide of the probe head. [Figure 15] The following schematic examples illustrate embodiments of the present invention in which the conductive portion is arranged in various ways on the guide of the probe head. [Figure 16A] A schematic probe head according to one embodiment of the present invention is shown. [Figure 16B] A schematic probe head according to one embodiment of the present invention is shown. [Figure 17A] A schematic probe head according to one embodiment of the present invention is shown. [Figure 17B] A schematic probe head according to one embodiment of the present invention is shown. [Figure 18] A schematic diagram of a probe head according to one embodiment of the present invention is shown, wherein the contact probe is equipped with a stopping mechanism in the form of a stopper. [Figure 19] A schematic diagram of a probe head according to one embodiment of the present invention is shown, in which the contact probe is equipped with a clip-shaped stopping mechanism. [Figure 20] A combination of the embodiments shown in Figures 18 and 19 is presented. [Figure 21A] A schematic diagram of a probe head according to one embodiment of the present invention is shown, in which the stopper contacts the conductive part. [Figure 21B]A schematic diagram of a probe head according to one embodiment in which the clip is in contact with a conductive part is shown. [Figure 22] A schematic diagram of a probe head according to one embodiment of the present invention, which has a non-linear guide hole, is shown. [Figure 23] A schematic diagram of a probe head according to one embodiment is shown, in which an elastically flexible intermediate section is embedded in a polymer material. [Figure 24A] A schematic diagram of a probe head according to one embodiment of the present invention is shown, which has a non-linear, elastically flexible intermediate section. [Figure 24B] A schematic diagram of a probe head according to one embodiment of the present invention is shown, which has a non-linear, elastically flexible intermediate section. [Figure 25] A schematic diagram of a probe head according to the present invention is shown, which has a pair of interconnected intermediate guides. [Figure 26] A schematic probe head according to one embodiment of the present invention is shown. [Figure 27] A schematic diagram of a probe head according to one embodiment is shown, in which an intermediate stopper positioned between two intermediate guides has multiple protrusions. [Figure 28] A schematic diagram of a probe head according to one embodiment of the present invention, assuming the presence of an additional upper stopper, is shown. [Figure 29] A schematic probe head according to one embodiment of the present invention is shown. [Figure 30] A schematic diagram of a probe head according to a further embodiment of the present invention is shown. [Figure 31] A schematic diagram shows a probe head according to one embodiment of the present invention, which is provided with two separate intermediate guides and two elastic sections. [Figure 32] A schematic diagram of a probe head according to a further embodiment of the present invention is shown. [Figure 33] A schematic diagram of a probe head according to a further embodiment of the present invention is shown. [Figure 34]A schematic diagram of a probe head according to a further embodiment of the present invention is shown. [Figure 35] A schematic diagram of a probe head according to a further embodiment of the present invention is shown. [Figure 36] A schematic diagram of a probe head according to a further embodiment is shown, which includes an arm with a laterally protruding end of the contact probe. [Figure 37] A schematic diagram of a probe head according to a further embodiment of the present invention is shown. [Figure 38] A schematic diagram of a probe head according to a further embodiment of the present invention is shown. [Modes for carrying out the invention]

[0037] Referring to the drawings, a probe head for testing an electronic device manufactured according to the present invention is schematically shown overall at 100.

[0038] It should be noted that the figures are schematic diagrams and are not drawn to scale, but rather to highlight important features of the invention. Furthermore, various elements are schematically depicted in the figures, and their shapes can be modified depending on the desired application. Also, it should be noted that the same reference numeral in the figures refers to the same element in terms of shape or function. Finally, certain means described in relation to an embodiment shown in one figure can also be used in other embodiments shown in other figures.

[0039] Furthermore, unless explicitly stated otherwise, please note that the steps of the described process can be reversed as needed.

[0040] The probe head 100 is configured to connect (directly or more preferably indirectly by a space transformer and / or PCB) to equipment (not shown) for performing tests on electronic devices integrated on the semiconductor wafer 20, such as (but not necessarily) high-frequency devices.

[0041] In the context of the present invention, it should be noted that the term “probe head” is used to describe a test apparatus, without being limited by the presence or absence of specific components, in addition to being defined by the appended claims. Therefore, generally, the term refers to a set of components that can be associated with further components for checking devices integrated on the semiconductor wafer 20 described above, and thus generally refers to a system for measuring electronic devices.

[0042] Referring to the cross-sectional view in Figure 1, the probe head 100 first comprises a plurality of contact probes 10 intended to electrically contact the device under test, which is integrated on the semiconductor wafer 20, with the test apparatus.

[0043] To accommodate the contact probe 10, the probe head 100 includes at least one guide 40 having a guide hole 40h inside which the contact probe 10 is housed. Thus, the guide 40, together with its guide hole 40h, is capable of housing, in particular, at least a portion of the contact probe 10, in a slidable manner.

[0044] Each contact probe 10 comprises a probe body 10' extending along a longitudinal axis (indicated by the reference numeral HH) between a first end 10a and a second end 10b, and these ends are configured to contact their respective pads or contact pads. For example, the first end 10a (also called a contact tip and referred to in this art as a "plunger") is configured to contact a pad 20a of a device under test integrated on a semiconductor wafer 20, while the second opposite end 10b (also called a contact head) is configured to contact a pad 30b of a space transformer or printed circuit board (PCB) that can be associated with a probe head 100, and such components are collectively identified by the reference numeral 30 and commonly defined as an "interface card". Thus, generally, the term "end" refers to the terminal portion of the contact probe 10, which comprises the point of contact of the probe with the pad.

[0045] In one embodiment (as illustrated in a simple example), pad 30b is a pad on a PCB board, but the use of an interposer positioned between the PCB and the probe's contact head is obviously not ruled out.

[0046] Although the ends 10a and 10b in the attached drawings are shown to terminate with a pointed shape, they are clearly not limited to this and can have any shape as needed and / or in accordance with the circumstances.

[0047] Furthermore, while the diagram shows a single contact probe 10 for simplicity, please note that the probe head 100 can be equipped with any number of contact probes depending on the application.

[0048] In the embodiment shown in Figure 1, a frame F is also provided that functions as a structural support for the probe head 100 as a whole, and is positioned in particular between the guide 40 and the PCB 30. This frame F is omitted in subsequent figures solely for the sake of simplicity in illustration.

[0049] Ideally, to enable high-performance high-frequency testing, the contact probe 10 is shortened in length, particularly to less than 2000 μm, preferably less than 1000 μm, and even more preferably less than 800 μm, and this length is measured along the longitudinal axis HH of the probe. This appropriately reduces the self-induction phenomenon and ensures effective testing even at very high frequencies in the radio frequency range.

[0050] To ensure proper contact with the pads 20a and 30b, and in particular to ensure proper control of the contact force, the contact probe 10 comprises at least one intermediate section 10s positioned between the first end 10a and the second end 10b and being elastically flexible (or pliable) at least along the longitudinal axis HH. The elastically flexible intermediate section 10s (hereinafter also referred to as the “elastic section” of the probe) is configured to determine the contact force FC (particularly its direction and / or strength) exerted on the pads 20a and / or 30b by the contact probe 10. That is, the contact force FC can be controlled by the structure (shape / size) of the elastically flexible intermediate section 10s, and the probe functions as a spring.

[0051] In particular, in one embodiment, the elastically flexible intermediate section 10s is appropriately configured such that the contact probe 10 exerts a contact force FC substantially oriented along the longitudinal axis HH on the contact pads 20a and 30b, but in other embodiments, forces with other components may also be present (for example, generating a scrubbing motion; in fact, it is possible to configure the elastically flexible intermediate section to generate torsion or lateral scrubbing on the pads, and in fact, in some embodiments, it is possible to provide elastically weaker and elastically stronger portions of the elastically flexible intermediate section 10s, and similarly, it is possible to provide the elastically flexible intermediate section 10s with a not-so-symmetrical helical shape).

[0052] In non-limiting embodiments of the present invention, the elastically flexible intermediate section 10s can be obtained by interlocking engravings or notches 10i formed on the body 10' of the contact probe 10, wherein the interlocking engravings or notches 10i are configured such that the contact probe 10 functions substantially as an elastic spring. Thus, the substantially spring-like elastically flexible intermediate section 10s can be formed, for example, by removing some material, in which case the notches 10i are made symmetrically with respect to the longitudinal axis HH of the contact probe 10 (however, this is not strictly necessary, and an asymmetrical shape with respect to the axis can be provided).

[0053] In general, the present invention is not limited by a specific method for manufacturing the contact probe 10, but is important for the presence of the above-mentioned elastic sections having multiple turns that follow one another along the longitudinal axis HH. Here, the term “turn” in this specification refers to a single elastic element (or elastic sub-part) of a spring that is repeated along the above-mentioned longitudinal axis HH, as detailed below, thereby forming a predetermined elastic pattern without being limited by a specific shape (for example, it does not necessarily represent a circular cross-sectional contour such as a helical spring, although such a configuration is clearly possible).

[0054] Therefore, the intermediate section 10s is elastically flexible primarily in the longitudinal direction so as to be compressed along the longitudinal direction during testing of the device under test (however, in other configurations, other directions of deformation of the elastic section, and therefore other directions of contact force FC, can also be provided as described above). In particular, the elastically flexible intermediate section 10s, with a "spring effect" that ensures proper contact force during overdrive and also allows the contact probe 10 to return to its original dimensions when the probe head 100 moves away from the device under test, allows the contact probe 10 to shorten along its longitudinal direction during the normal operation of the probe head 100.

[0055] In the embodiments described above, it should be noted that the contact probe 10 exerts the above-mentioned contact force FC on the pad which is substantially oriented along the longitudinal axis HH, while the component perpendicular to the longitudinal axis HH is substantially zero (or reduced in any case), thereby eliminating the risk of interlocking of the contact probe 10 within the guide hole 40h.

[0056] Preferably, the contact probe 10 has a non-circular cross-section. In a preferred embodiment, the contact probe 10 has a rectangular cross-section, for example, with one side of the rectangle having a length of 30 μm and the other side having a length of 70 μm, but other dimensions are also obviously available.

[0057] Furthermore, it should be noted that the contact probe 10 can be made of composite materials such as layers of Pd, PdCo, ​​Ni, NiCo, Au, Pt, Ag, Rh, etc., without being limited by the specific materials or manufacturing methods used. In general, it is possible to select various materials or combinations of materials (e.g., the materials mentioned above or combinations thereof) depending on the need and / or circumstances.

[0058] The elastically flexible intermediate section 10s extends along the longitudinal axis HH of the contact probe 10 with a length of 1000 μm to 80 μm (preferably about 200 μm) and a pitch of 100 μm to 5 μm (i.e., the stationary distance between the centers of two adjacent turns).

[0059] Figure 2 shows contact probes manufactured according to different designs and pitches of each elastic section, where, for example, the number of loops and the thickness of a single turn vary in the embodiment. Other shapes of the elastically flexible intermediate section 10s are also described below.

[0060] In one embodiment, the elastically flexible intermediate section 10s is formed such that the end of the section is always located on the same side of the contact probe 10.

[0061] The stress on the contact probe 10 can be reduced when an elastically flexible intermediate section 10s having a longer length (for the same total length of the contact probe 10, which is always less than 2000 μm, preferably 800 μm or less, as described above) is manufactured.

[0062] To accommodate the elastically flexible intermediate section 10s, a deep guide hole 40h is formed (for example, having a length greater than 300 μm). As shown in Figure 3, to overcome this problem, instead of using a single guide 40 with a thicker thickness, it is possible to use two or more guides of a thinner thickness that are associated with each other. In other words, in one embodiment, the guide 40 may comprise a first guide portion 40' and a second guide portion 40''. The second guide portion 40'' is initially made structurally independent of the first guide portion 40' and then associated with it, and in particular, it is attached to the contact probe 10 after the contact probe 10 has been introduced into the first guide portion 40'. For example, the second guide portion 40'' may be superimposed on the first guide portion 40', or it may be fixed to it by mounting means, without limiting the present invention to a specific mounting method. This makes the depth of the guide hole of a single guide portion shallower than when using a single guide, and simplifies the formation of the hole.

[0063] A preferred embodiment has been described so far, in which a single guide 40 is provided (for example, its overall thickness is equal to 320 μm, but other thicknesses, such as thicker ones, are obviously possible, and thus the elastic section of the contact probe can be extended), and in this embodiment, the elastically flexible intermediate section 10s is positioned on the guide 40 at a substantially intermediate position so that it is at least partially housed in the guide hole 40h. In other words, an embodiment has been described so far that assumes the presence of a single intermediate guide 40 housing the elastic section of the contact probe 10. This embodiment has the advantage of being easier to assemble and having lower production costs.

[0064] Alternatively, referring to Figure 4, the probe head 100 may be equipped with a lower guide 45l and an upper guide 45u separated from each other by a void or gap G in which an elastically flexible intermediate section 10s is located, thus demonstrating the possibility of increasing the extension of this elastic section. The lower guide 45l and the upper guide 45u are equipped with lower guide holes 45lh and upper guide holes 45uh, respectively, for accommodating the contact probe 10.

[0065] In one embodiment (not shown), the lower guide hole 45lh and the upper guide hole 45uh do not have to be aligned with respect to each other, that is, with respect to a single probe, their centers do not lie on the same longitudinal axis, thereby causing slight deformation of the contact probe 10, which is advantageous for retention and any possible contact with the walls of these holes.

[0066] Next, referring to Figures 5-11, in addition to the standard shapes depicted in Figures 1-4, various shapes are possible for the elastically flexible intermediate section 10s, which is formed by elastic elements that appear as steps in the illustrated cross-sectional view. In these various shapes, a single elastic element (of varying shapes) is defined that is repeated along the longitudinal axis HH so that the different mechanical properties of the contact probe 10 determine the corresponding different elastic patterns.

[0067] For example, among the various possible geometries, the elastically flexible intermediate section 10s can have a shape with a serrated development (Figure 5) or a helical shape, or it can even be structured as a plurality of elastic elements having the shapes of interconnected polygonal elements in a longitudinal cross-section, such as a series of interconnected hexagonal elements (Figures 6 and 7). The above polygonal elements can have a closed contour (i.e., they can have regions that do not communicate with each other), but this is not necessarily required, and embodiments can also be provided in which the various connected polygonal elements have regions that communicate with each other, even if only in short sections.

[0068] Alternatively, the elastically flexible intermediate section 10s can be structured as a plurality of elastic elements, each having the shape of interconnected elements with an elliptical contour (e.g., oblong) and continuing to one another along the longitudinal axis HH (Figure 8), where each of the elements having an elliptical contour unfolds along an axis of symmetry substantially perpendicular to the longitudinal axis HH of the contact probe 10 and is slightly compressed in the middle.

[0069] More specifically, referring to the geometry described above, the embodiment in Figure 5 allows for increased overdrive of the contact probe 10, while the embodiment in Figure 6 helps maintain the contact probe 10 in a linear configuration, while simultaneously increasing its force and rigidity. On the other hand, the embodiment in Figure 7, in which the slanted sides of the hexagon are replaced with curved sections, helps maintain the contact probe 10 in a linear configuration as in Figure 6, but simultaneously increases its flexibility and decreases its strength. The embodiment in Figure 8 replicates the effect of two joined standard springs, with the aim of increasing the symmetry of the contact probe 10 and maintaining good flexibility.

[0070] Furthermore, the deformations shown in Figures 6bis, 7bis, and 8bis correspond to the geometries of Figures 6, 7, and 8, respectively, except that the single elastic elements in the aforementioned figures are then grouped into interconnected pairs, with each pair being defined by a single closed or single semi-closed contour, for the purpose of further reducing the stiffness of the elastic section and thus the overall stiffness of the contact probe 10.

[0071] Furthermore, referring to the embodiment shown in Figure 9, the elastically flexible intermediate section 10s is formed by a plurality of turns having an asymmetric shape with respect to the longitudinal axis HH, each of which defines a hysteresis curve (when viewed, for example, in cross-section). In other words, in this embodiment, the asymmetric shape of the turns is such that, in cross-section, two edges (for example, the larger edge) are offset from each other. This results in the elastic section 10s having a cross-sectional dimension larger than the cross-sectional dimension of the guide hole 40h (as shown in Figure 9), creating friction between the elastic section 10s and the walls of the guide hole 40h, preventing, for example, the contact probe 10 from coming out of the guide 40 during maintenance of the probe head 100, and also ensuring better electrical contact with the possible metallized walls of the guide hole 40h, as will be discussed later. Figure 10 shows a case where the various turns are not aligned along the same axis HH and define a non-linear section, although in other embodiments they can be aligned on the same axis HH.

[0072] Figure 10 shows a further embodiment comprising an elastically flexible intermediate section 10s, in which turns that define a closed curve of hysteresis shape (i.e., elastic elements described in relation to the previous Figure 9) are arranged alternately with standard turns (e.g., standard turns of a helical spring, or standard turns of any other suitable shape) along the longitudinal axis HH of the contact probe 10.

[0073] Furthermore, Figure 11 shows an embodiment in which the standard turn is integrated with an elastic deformation mechanism in an elastically flexible intermediate section 10s, which is shown here as an “additional elastic element 10sm” (spring bounce). In other words, in this embodiment, it is possible to place an additional elastic element 10sm having different deformation characteristics between two elastic elements that deform substantially along the longitudinal axis HH (i.e., perform the standard deformation as described above), and the elastic element 10sm comprises, for example, arms 10sa having different elasticity (in this case, for example, one arm may be less elastic than the other). This occurs not only along the longitudinal direction but also along other directions and helps to modify the deformation characteristics of the above-described elastic section 10s, for example, causing a scrubbing motion of the first end 10a of the contact probe 10 on the pad 20a of the device under test. It is also possible that the elastically flexible intermediate section 10s is formed solely by the above-described additional elastic element 10sm.

[0074] Clearly, the illustrated embodiments are for illustrative purposes only and do not limit the scope of the present invention, but various embodiments can be modified depending on the application and may be combined with each other.

[0075] As will be discussed in more detail later, in another embodiment, a plurality of elliptical rings are envisioned, in which case, unlike those shown in Figure 8, each of the rings has a length that extends along the longitudinal axis HH of the contact probe 10, in particular to facilitate contact with the wall of the guide hole 40h when these rings are compressed, which is advantageous when there is metallization to short-circuit the group of probes together.

[0076] In this regard, it is well known in the art that the fixed positions of the power and ground signals (for example, due to the layout of the pads of the device under test) and the shape of the probe limit the control of the impedance of the signals inside the probe head, and also limit the control of noise induced in the signal probe by other nearby signals, thereby limiting the frequency performance of the probe head.

[0077] Therefore, in high-frequency applications (especially RF applications), ground probes (and power probes as well) are short-circuited through metallization on the guide, and consequently, probes in the same domain are short-circuited to connect any existing shields, making ground available within the probe head. Also, when devices with different ground / power domains are joined on a PCB, metallization can reduce loop inductance between the power and associated ground.

[0078] For example, consider a case where a single probe contacts a predetermined power supply of the device under test, and that probe is short-circuited to other probes that transmit power from the same power supply unit. In such a case, when the current from this power supply touches the metallization that short-circuits all probes in this domain, it is distributed among all the short-circuited probes, thereby reducing the inductance and equivalent resistance compared to the case where the current to the PCB is limited to a single probe.

[0079] Thus, it is clear that the presence of metallization on the guide, which short-circuits the group of probes and creates a common conductive surface, reduces noise and improves the frequency performance of the probe head.

[0080] Similarly, it is also possible to short-circuit signal probes with each other, for example, using loopback technology.

[0081] For this purpose, according to an embodiment (as shown in Figure 12), the guide 40 of the probe head 100 comprises at least one conductive portion 21, which includes at least one group of holes (indicated by reference numeral 40h') of guide holes 40h, which are configured to electrically connect these holes and to contact and thus short-circuit the corresponding group of contact probes, which are intended to transmit signals of the same kind, in particular, a predetermined ground or power signal, or an operating signal.

[0082] The conductive portion 21 formed on the guide 40, also referred to below as "metallization 21", makes it possible to form a predetermined conductive domain in which at least a portion of the contact probe 10 comes into contact with the conductive portion 21.

[0083] In the non-limiting embodiment shown in Figure 12, two contact probes short-circuited by the conductive portion 21 and a contact probe electrically insulated from them are shown, but this is clearly only a schematic example and any number can be provided.

[0084] For example, the contact probes 10, which are short-circuited from each other by the conductive portion 21, can be contact probes intended to transmit a ground signal or contact probes intended to transmit a power signal. In other words, in the probe head 100, the contact probes that are short-circuited from each other by the metallization of the guide 40 and housed in the group 40h' of the guide holes 40h are configured to transmit the same ground signal or power signal, thereby improving the performance of the probe head.

[0085] Furthermore, as mentioned above, the short-circuited probe can also be a contact probe intended to transmit input / output operating signals between the device under test and the test equipment interfaced with the probe head 100, for example, in the case of loopback technology.

[0086] In any case, the conductive portion 21 forms a common conductive surface within the probe head, which is particularly useful in high-frequency testing where a short contact probe 10 can be performed.

[0087] Clearly, the probe head 100 can have any number of conductive parts 21 positioned in any way on the guide, or even embedded within the guide, to transmit any kind of signal. For example, the conductive parts can be formed on the upper surface FB of the guide 40 (as shown in Figure 12) or positioned on its lower surface FA (as shown in Figure 13), and can also be formed inside the guide 40 (i.e., embedded within the guide 40 as depicted in Figure 14).

[0088] Furthermore, it is possible to envision the presence of a first conductive part for short-circuiting the ground probe and a second conductive part for short-circuiting the power probe, located on the opposite side of the guide, and similarly, many other configurations can be provided, such as those described in, for example, the present applicant's international patent application number PCT / EP2017 / 082180.

[0089] As a simple example, as shown in Figure 15, it is possible to provide multiple conductive parts 21' and 21'' corresponding to multiple different conductive domains (e.g., different power domains), and these conductive parts 21' and 21'' are located on the opposite side of the guide 40 (as shown in the non-limiting embodiment of Figure 15) and / or embedded in the guide 40, or even located on the same side of the guide 40.

[0090] The method for manufacturing the conductive part is not limited to a specific method; for example, it can be formed by depositing a conductive material onto a ceramic guide.

[0091] In other words, the present invention is not limited by the number and arrangement of conductive parts, and the number and arrangement of conductive parts can be determined based on necessity and / or circumstances.

[0092] In any case, the important point is that the presence of at least one conductive portion 21 makes it possible to form a common conductive surface, which electrically connects to each other several contact probes (i.e., contact probes 10 housed in groups of holes 40h') that have elastically flexible intermediate sections 10s as described above, and whose length is shortened to improve the overall performance of the probe head 100.

[0093] Furthermore, the conductive portion 21 can cover at least a portion of the wall 40W of the guide hole of group 40h', thereby forming a metallized portion of the guide hole that the contact probe 10 contacts, in particular, the contact probe 10 making sliding contact with.

[0094] Preferably, the conductive portion 21 can completely cover part or all of the wall of the guide hole (in this case, the metallized portion coincides with the entire wall 40W of the hole), or the conductive portion 21 can be configured to only partially cover the wall 40W of the guide hole.

[0095] Due to the importance of the conductive portion 21, it is necessary to ensure optimal contact between the contact probe 10 and the conductive portion 21 (for example, between the probe and the metallized wall of the guide hole) during device testing, and for example, the above-mentioned sliding contact between the probe and the hole must always be ensured (however, in some configurations, this contact can be a pressing contact, for example, contact of a stopper on the conductive portion as discussed below).

[0096] In embodiments of the present invention described above and shown in detail in Figures 16A-16B and 17A-17B, to improve electrical contact between the contact probe 10 and the conductive portion 21, the elastically flexible intermediate section 10s is structured as a plurality of interconnected elastic elements (or elastic sub-parts, reference numeral 10sr') that are connected to one another along the longitudinal axis HH of the contact probe 10. As depicted in the above figures, each of the elastic elements 10sr' is configured to be compressed under the action of pressure generated during testing of the device under test, during which its dimension along the longitudinal axis HH of the contact probe 10 is reduced, its lateral dimension is increased, and consequently it undergoes a lateral bend that brings it closer to the wall of the guide hole.

[0097] As shown in the embodiments of Figures 16A-16B and 17A-17B, the elastic elements 10rs' are formed as interconnected rings, each having an elliptical shape that extends longitudinally along the longitudinal axis HH of the contact probe 10; that is, these rings are stretched longitudinally along the probe to increase lateral bending (and thus, generally speaking, they are elastic elements with an elongated shape along the longitudinal axis HH). These rings can have a closed or semi-closed profile.

[0098] This configures the elastic element 10sr' to contact the conductive portion 21 (at least partially covering the wall of the guide hole 40h) through at least one of its sidewalls (indicated by reference numbers 40W1 and / or 40W2) as its lateral dimension increases during testing of the device under test, ensuring optimal contact with the metallization described above (as shown in Figure 17B). In other words, when overdrive is applied, a single ring expands to contact the corresponding wall portion of the guide hole 40h.

[0099] In one embodiment, the first wall (wall W1 in the figure) of at least one elastic element 10sr' facing the corresponding wall of the guide hole 40h (wall 40W1 in the figure's embodiment) is elastically weaker than its second wall (i.e., wall W2 in this embodiment) located on the opposite side with respect to the longitudinal axis HH. Generally, it is possible to provide embodiments in which the entire wall of one of the two walls of the elastic section described above has lower elasticity, thereby changing the deformation characteristics of the contact probe 10 so that it does not deform symmetrically. Thereafter, only one of the walls of the contact probe 10 contacts the metallization in question (i.e., the ring contacts the single wall of the guide hole by expanding, particularly through the elastically weaker portion), thereby avoiding the problem of interlocking, while at the same time ensuring optimal contact and generating beneficial scrubbing action of the contact tip as much as possible.

[0100] Next, referring to Figure 18, in one embodiment of the present invention, the contact probe 10 also includes a stopping means formed on its body 10', the stopping means being configured to mechanically contact at least a portion of the guide 40 to hold the probe within the probe head 100.

[0101] This allows the position of the contact probe 10 within the probe head 100 to be fixed, preventing it from sliding out of the guide hole 40h.

[0102] In a particular embodiment shown in Figure 18, the stopping means is structured as a stopper having a lateral extension (indicated by reference no. 50) that defines at least one shoulder portion (reference no. S1 or S2) configured to abut against the upper surface FB of the guide 40, i.e., against the surface opposite to the surface FA facing the device under test. (The stopper 50 bonded to the probe body portion may have a lateral extension larger than that of the guide hole for properly holding the contact probe).

[0103] In particular, in a preferred embodiment, the stopper 50 comprises two shoulders S1 and S2 that are symmetrical with respect to the longitudinal axis HH of the contact probe 10 and define two surfaces for contacting the surface FB of the guide 40. It should be noted again that the figure is merely an example of the application of the present invention, and other configurations of the stopper can obviously be adopted (for example, the stopper may protrude from only one wall of the contact probe 10 rather than from two opposing walls as depicted).

[0104] Additionally or alternatively, in the embodiment depicted in Figure 19, the probe stopping means comprises at least one clip 60 configured to mechanically interfere with a guide hole 40h and thereby contact the wall 40W of the guide hole 40h. More specifically, the clip 60 protrudes from the body 10' of the contact probe 10 and is configured to elastically deform during contact with the wall 40W of the guide hole 40h, thereby holding the contact probe 10 by mechanical interference with the guide hole 40h.

[0105] In the embodiment shown in the figure, the clip 60 is formed on the surface FA of the guide 40, that is, on the lower surface facing the device under test DUT.

[0106] The presence of the stopper 50 and / or the clip 60 prevents the contact probe 10 from coming out of the guide hole 40h when the device under test and / or the PCB is absent (and therefore, in the latter case, when the probe head 100 is inverted), thus simplifying the handling of the probe head 100.

[0107] In a preferred embodiment, there are two clips 60 arranged symmetrically on the body 10' with respect to the longitudinal axis HH, and these clips 60 are configured to contact the respective walls 40W of the guide hole 40h, ensuring interlocking of the movement of the contact probe 10.

[0108] Clearly, a combination of stopper 50 and clip 60 can also be provided, as shown in the embodiment of Figure 20.

[0109] In general, it is preferable that the clip 60 has a lower stiffness than the elastically flexible intermediate section 10s, so as to avoid deformation of the contact probe 10 during assembly, but also to ensure that the contact probe 10 can be properly handled along the longitudinal axis HH during testing.

[0110] Suitablely, in the presence of conductive portions 21 for short-circuiting a group of probes, contact between the contact probe 10 and the conductive portion 21 can be pressurized contact by the shoulders S1 and / or S2 of the stopper 50, as shown in the embodiment of Figure 21A, or contact with one or more walls 40W of the guide hole 40h via one or more clips 60, as shown in the embodiment of Figure 21B, or a combination of both embodiments. Additionally, or alternatively, as described above and as will be discussed in more detail below, contact between the contact probe 10 and the conductive portion 21 can be sliding contact between at least one wall of the contact probe 10, in particular at least one wall of the elastically flexible intermediate section 10s, and at least one corresponding wall 40W of the guide hole 40h.

[0111] With regard to the retention of the contact probe 10, it is also possible to provide an embodiment in which the guide hole 40h is not linear (i.e., has a non-linear section), as shown in Figure 22, thereby preventing the contact probe 10 from coming loose. In other words, at least one guide hole 40h of the guide 40 has at least one wall inclined with respect to the longitudinal axis HH, and the guide hole 22h has a non-linear cross-sectional shape. Preferably, the guide hole 40h has a pair of inclined opposing walls, so that the desired retention is properly achieved without the need to introduce a stopping means for the contact probe 10.

[0112] Next, referring to the embodiment shown in Figure 23, the elastically flexible intermediate section 10s is at least partially embedded in a polymer material (identified here by reference no. P), thereby ensuring better mechanical stability of the contact probe 10 as a whole. For example, the elastically flexible intermediate section 10s can be completely embedded in the polymer material P, and therefore, in this case, the material can extend completely into the guide hole 40h.

[0113] In one embodiment, the polymer material P is a polyamide or selected from other materials similar to polyamide materials, but the present invention is not limited by the polymer coating material used, because any suitable material can be selected based on the requirements.

[0114] In this case, the presence of the polymer material P increases the elastic response of the elastically flexible intermediate section 10s itself, thereby ensuring greater strength against lateral deformation.

[0115] Clearly, this embodiment can be combined with other embodiments, such as the presence of a conductive portion 21.

[0116] Furthermore, in the embodiments shown in Figures 24A and 24B, the elastically flexible intermediate section 10s is structured as a plurality of elastic sub-parts or elastic elements (indicated in this case by reference no. 10sr"), which are not aligned with one another with respect to the same reference axis. For example, the elastic elements 10sr" unfold along their respective axes of symmetry, which are parallel to each other (and indicated by reference no. H'-H', H"-H"), and which do not necessarily coincide with the longitudinal axis of the probe as defined above. In other words, in this embodiment, the elastically flexible intermediate section 10s is formed by various sections (i.e., elastic elements) that are not aligned along the longitudinal axis of the contact probe 10, i.e., along the vertical reference axis. The elastic elements 10sr" are continuous and uninterrupted, and their respective axes of symmetry are (shifted) and not coincide with each other, shifted from one another (i.e., offset along the vertical reference axis) to define the entire elastically flexible intermediate section, which is not linear.

[0117] Ideally, at least one of these elastic elements 10sr'' is in contact with the wall 40W of the guide hole 40h and, in particular, with the conductive portion 21 extending within this hole (as shown in Figure 24B), thereby achieving the desired electrical contact with the metallization.

[0118] According to one embodiment, one or more edges of the elastic element 10sr'' (in particular, the edges of the elastic element that are in contact with the wall 40W of the guide hole 40h, i.e., the protruding portions) are beveled (i.e., provided with a beveled surface 10bl) to avoid interlocking of the contact probe 10 within the guide hole.

[0119] This embodiment assumes the formation of a non-linear or curved intermediate elastic section, which is advantageous because it ensures that the contact probe 10 remains in place during testing of the device under test while maintaining proper contact with the wall of the guide hole 40h and therefore with the associated metallization. In particular, in this embodiment (as seen in the embodiment of Figure 9), the elastic section 10s has a cross-sectional dimension (at least locally) larger than the cross-sectional dimension of the guide hole 40h (as shown in Figures 24A and 24B), creating friction between the elastic section 10s and the wall of the guide hole 40h. This friction prevents the contact probe 10 from coming out of the guide 40, for example during maintenance of the probe head 100, and ensures better electrical contact with the conductive part 21 (Figure 24B).

[0120] Advantageously, according to the present invention, next with reference to Figure 25, the guide 40 may comprise a first guide 40a having a first guide hole 40ah and a second guide 40b associated with the first guide 40a and having a second guide hole 40bh (these may be structured as the first and second guides 40a and 40b).

[0121] In one embodiment, the first guide 40a and the second guide 40b are preferably positioned close to the intermediate region of the probe head 100 (between the semiconductor wafer 20 and the interface card 30), but this is not necessarily required.

[0122] In other words, according to the present invention, the probe head 100 preferably comprises two intermediate guides, a first guide 40a and a second guide 40b.

[0123] According to the present invention, the elastically flexible intermediate section 10s is positioned in one of the first guide hole 40ah and the second guide hole 40bh (in the embodiment of Figure 26, the elastically flexible intermediate section 10s is positioned in the first lower guide hole 40ah, but the present invention is not necessarily limited to this particular configuration).

[0124] Preferably, according to the present invention, the contact probe 10 further comprises intermediate stopping means positioned between the first guide 40a and the second guide 40b, which are not limited to a particular type and can have various configurations (including the aforementioned configurations depicted in Figures 18-20), as detailed below. Generally, the intermediate stopping means are configured to mechanically contact at least a portion of the first guide 40a and / or the second guide 40b for holding the contact probe 10 in the probe head 100, in particular to prevent it from sliding out of the first guide hole and / or the second guide hole, for example, when the device under test and / or PCB is not present.

[0125] For example, as shown in Figure 25, the intermediate stopping means includes an intermediate stopper (identified here by reference no. 50'), which may have the same configuration as the stopper 50 discussed with reference to Figure 18 (it may protrude from two walls, or from one wall of the probe body, or any other suitable configuration is possible). Thus, the intermediate stopper 50' has a lateral extension to define at least one shoulder portion (in particular, two shoulder portions S1' and S2') configured to abut against the surfaces of the first guide 40a and / or the second guide 40b, and thus to define a contact surface for abutting against these surfaces (the intermediate stopper 50' bonded to the probe body portion may have an entire lateral extension larger than that of the guide hole for properly holding the contact probe).

[0126] Therefore, the presence of the intermediate stopper 50' ensures that the contact probe 10 is properly held within the probe head 100, and in particular, the combination of the intermediate stopper 50' with the first guide 40a and the second guide 40b prevents the contact probe from coming out in either direction, thus allowing the short contact probe 10 to be held in an easy manner when neither the semiconductor wafer 20 nor the interface card 30 is present.

[0127] As shown in Figure 26, in one embodiment of the present invention, the intermediate stopper 50' can be configured to abut against a conductive portion 21 formed on the surface of the first guide 40a or the second guide 40b, thereby forming an electrical connection with the conductive portion 21 and thus enabling a short circuit of the contact probe 10 within the corresponding domain. In the embodiment of Figure 26, the intermediate stopper 50' abuts against the lower surface of the second upper guide 40b where the conductive portion 21 is located, through its shoulder portions S1' and S2', although the conductive portion 21 can be formed on the first lower guide 40a to which the intermediate stopper 50' can abut.

[0128] In general, the conductive portion 21 can be formed on the surfaces FA and / or FB of the first guide 40a and / or the second guide 40b, and can also be formed in any suitable manner (even such as being embedded within the guide). Furthermore, it is possible to provide multiple conductive portions corresponding to multiple conductive domains, and these conductive portions can be located on the same surface of the first guide 40a and / or the second guide 40b, or on opposite surfaces of the first guide 40a and / or the second guide 40b.

[0129] In this case, the conductive portion 21 includes at least one group of first guide holes 40ah and / or second guide holes 40bh (also indicated by reference no. 40h'), which is configured to contact a corresponding group of contact probes housed in the group 40h' of the holes and short-circuit the contact probes.

[0130] Figure 26 shows only two contact probes 10 short-circuited by the conductive portion 21 as an example, but it should be noted that the present invention is not limited thereto, and group 40h' can comprise any number of guide holes, and therefore any number of contact probes 10.

[0131] Therefore, in the embodiment shown in Figure 26, the contact between the contact probe 10 and the conductive part 21 is a pressing contact by one or more contact surfaces of at least one shoulder portion S1 and / or S2 of the intermediate stopper 50', and in this way an electrical connection is formed between the contact probe 10 and the conductive part 21.

[0132] In general, everything discussed so far regarding the conductive portion 21 is also applicable to the present invention which provides a double intermediate guide, and it should be noted that all of the above geometries, and / or the presence of polymer materials, etc., for an elastically flexible intermediate section 10s (for example, a spring with an elliptical elastic element, or a non-linear elastically flexible intermediate section) can also be applied to this configuration.

[0133] To increase contact with the aforementioned metallization and enhance the performance of the probe head 100, the intermediate stopper 50' is provided with a plurality of projections (and identified here by reference numeral 50p) protruding from at least one of the shoulders (i.e., they protrude from the contact surfaces defined by the shoulders S1' and / or S2' described above), as depicted in the embodiment of Figure 27. In particular, the projections 50p are configured to contact a portion of the conductive portion 21, forming an optimal electrical connection with the conductive portion 21.

[0134] Furthermore, it should be noted that the present invention is not limited by the specific shape of the projection 50p; for example, the projection 50p can be triangular-toothed (as shown in Figure 27), but any suitable shape can be used. In one embodiment, the projection 50p can be generally defined by the surface irregularities of the intermediate stopper 50'. In addition to, or as an alternative to, those shown in Figure 27, these projections 50p can also protrude downward so as to abut against the first guide 40a.

[0135] According to the embodiment shown in Figure 28, the probe head 100 may also be equipped with an additional stopper (also referred to here as the “upper stopper” and indicated by reference numeral 50”), the above-mentioned additional stopper is positioned to abut against the upper surface FB of the second guide 40b, which is the surface furthest from the device under test. In other words, the upper stopper 50”) functions as a cap to hold the contact probe 10 more effectively. The upper stopper 50”) may have the same shape and dimensions as the intermediate stopper 50', but this is not strictly required.

[0136] Furthermore, in this embodiment, which assumes the presence of a first guide 40a and a second guide 40b, the probe is housed in the first guide 40a, and then the latter is attached to the contact probe 10.

[0137] Furthermore, to facilitate the assembly of the probe head 100, a retaining element formed as an elastic hook (indicated by reference numeral 90 in Figure 29) can be provided instead of the intermediate stopper 50'. In particular, this elastic hook 90 is configured to elastically deform during the insertion of the contact probe 10, for example, when it is inserted from above through the second guide hole 40bh, as well as during the withdrawal of the contact probe 10 through other guide holes, i.e., through the first lower guide hole 40ah (and thus by forced withdrawal from below).

[0138] Once the probe head 100 is assembled, the elastic hook 90 is housed between the first guide 40a and the second guide 40b, in an undeformed configuration that allows it to mechanically contact the first guide 40a and / or the second guide 40b for holding the contact probe 10.

[0139] Advantageously, this allows the contact probe 10 to be inserted with the first guide 40a and the second guide 40b already assembled in their operating positions, while to withdraw the contact probe 10, it is sufficient to simply pull the latter downward through its first end 10a, that is, through its lower end.

[0140] According to a further embodiment of the present invention shown in Figure 30, the intermediate stopping means may comprise an elastic film, such as a Kapton® sheet, positioned between a first guide 40a and a second guide 40b (and shown herein by reference no. 95).

[0141] Referring next to Figure 31, a particularly advantageous embodiment provides the presence of a first elastically flexible intermediate section 10sa (also referred to for convenience as the “first spring” or “lower spring”) in a first guide hole 40ah, and a second elastically flexible intermediate section 10sb (also referred to for convenience as the “second spring” or “lower spring”) in a second guide hole 40bh. An intermediate stopping means (for example, the intermediate stopper 50' described above (see Figure 31) or the aforementioned elastic hook 90 (see Figure 32)) is positioned between the first elastically flexible intermediate section 10sa and the second elastically flexible intermediate section 10sb.

[0142] This embodiment has the advantage of allowing for more precise control of the movement (particularly compression) of the contact probe 10, and therefore, more optimally determining and controlling the contact force in general. For example, it is possible to more precisely control the vertical movement along the longitudinal axis HH, but as mentioned above, in this case, various geometries of the elastically flexible intermediate sections 10sa and 10sb are also possible along with movement in various directions.

[0143] The first elastically flexible intermediate section 10sa may have a different elastic constant ka than the second elastically flexible intermediate section 10sb, which has a different elastic constant kb. Generally, these elastic constants can be appropriately selected.

[0144] Let xa and xb be the entities of compression experienced by the first and second springs, respectively. Then, the reaction force FR exerted by the contact probe 10 during the test (and therefore during its compression) is given by the known relationship FR = -ka × xa - kb × xb. As a mere example, assuming that the overdrive of the contact probe 10 is 100 μm, the elastic constants ka and kb can be selected such that the first spring 10sa has a compression of 70 μm, while the second spring 10sb has a compression of 30 μm. That is, in this case, the first spring 10sa has an elastic constant ka greater than the elastic constant kb of the second spring 10sb. Also, assuming that the distance d between the intermediate stopper 50' and the lower surface FA of the second guide 40b is equal to 30 μm, it is certainly guaranteed that the intermediate stopper 50' will contact the lower surface FA.

[0145] All of this is particularly advantageous when the group of probes is short-circuited to each other by the conductive part 21 (see Figure 33 for this purpose), because pressing contact with the conductive part 21 is always guaranteed by adjusting the elastic constant of the spring (thus, for example, by selecting the guide to be contacted, contact is thereby guaranteed and with the appropriate contact force). As mentioned above, this contact can be further improved by the presence of projection 50p, as shown in Figure 34.

[0146] Clearly, the various embodiments described above can be combined, for example, by also providing the presence of an upper stopper 50” (as shown in Figure 35) in the presence of one or more conductive parts 21 in some cases.

[0147] Furthermore, in embodiments not shown, the first guide 40a and the second guide 40b can be shifted from each other with respect to the longitudinal axis HH (i.e., the respective holes cannot be aligned with each other along the vertical reference axis), which is further advantageous for (sliding) contact with the wall of the guide hole 40h.

[0148] Referring next to the embodiment shown in Figure 36, the second end 10b of the contact probe 10 can be structured to include an arm 10bar that protrudes laterally from the probe body 10' and is configured to contact the contact pad 30b of the interface card 30. The protruding arm 10bar is configured to offset the contact point between the contact probe 10 and the contact pad 30b of the interface card 30 with respect to the longitudinal axis HH of the contact probe 10.

[0149] In the example shown in Figure 36, the arm 10bar extends along an axis YY that is substantially perpendicular to the longitudinal axis YY, but this is not strictly necessary.

[0150] This embodiment has the advantage that, due to the shape of the contact probe 10 itself, which has an arm 10bar protruding from the probe body 10', the contact pads formed on the interface card 30 are spatially redistributed compared to those of the device under test without using a space transformer interposed between the probe and the PCB. Therefore, it is possible not to place an interposer between the PCB and the probe head 100, and as a result, in this embodiment, the interface card 30 is essentially the PCB.

[0151] Furthermore, in embodiments not shown, the probe head 100 may comprise multiple contact probes having arms 10bar of varying lengths to obtain a more effective spatial redistribution of the contact pads 30b on the PCB 30 compared to that of the device under test, the length of which is measured along the longitudinal deployment direction YY. The presence of arms of different lengths makes it possible to vary the pitch of the pads 30b on the PCB compared to the pitch of the pads 20a on the device under test, and in particular, to relax the constraints on the distance between the centers of the contact pads on the PCB compared to that of the device under test. The length and arrangement of the arms 10bar are variable in the probe and selected based on specific requirements, and in some cases, contact probes without arms may also exist to obtain a particularly effective configuration.

[0152] This embodiment is particularly advantageous in the case of large probe heads, such as those used in testing storage devices like DRAM, because it allows for the use of fewer components with the configuration shown herein. In particular, it avoids the presence of complex, costly, and very time-consuming space transformers, such as MLC (an acronym for "Multi Layer Ceramic") or MLO (an acronym for "Multi Layer Organic"), between the PCB and the probe head. Furthermore, the probe head can be interfaced with a PCB having a simpler and less expensive structure and a looser pitch (e.g., a pitch with a larger relative distance to the device under test, and therefore lower density, and / or a configuration selected in a simple way based on the needs).

[0153] In the embodiment shown in Figure 36, actual contact between the PCB 30 and the pad 30b is made by a contact element formed on the upper surface of the arm 10bar, for example, at its free end. However, this contact element does not necessarily have to be pointed and can have other shapes than those shown in the figure.

[0154] Clearly, the embodiment shown in Figure 36 can be combined with other embodiments, and therefore, for example, one or more of the stopper, contact with conductive parts, a double intermediate guide, and many other configurations can be provided.

[0155] Referring to the embodiment in Figure 37, the first end 10a (i.e., the lower end) of the contact probe 10 may be made of a high-hardness material 10ins, other materials may also be used, but in particular, it may include a material having a higher hardness compared to the material of the probe body 10', such as rhodium.

[0156] Clearly, Figure 37, in which the high-hardness material constitutes the entire terminal portion of the contact probe 10, is provided merely as an example, and other configurations are also possible. Generally, the high-hardness material 10ins can be configured to make contact with the pad 20a of the device under test, thus ensuring that the contact tip has high hardness at least partially. For example, in one embodiment, the high-hardness material 10ins can be an insert supported by a supplementary section of the probe body 10' and intended to make contact with the pad 20a of the device under test, or it can be a coating or layer of material on the first lower end 10a, or any other suitable configuration.

[0157] This embodiment in Figure 37 ensures a long service life for the contact probe 10 while maintaining high-quality contact.

[0158] As previously mentioned, the elastically flexible intermediate section 10s is structured as a plurality of elastic elements (or a plurality of elastic sub-parts) repeated at least along the longitudinal axis HH of the contact probe, thereby forming a predetermined elastic pattern without being limited by a specific shape. Furthermore, the elastically flexible intermediate section 10s can extend over the entire length (or more) of the guide hole, or over only a specific (shorter) length.

[0159] With respect to the shape of the contact probe, in some embodiments, even in the case of two intermediate guides (i.e., in the case of the first guide 40a and the second guide 40b), the elastically flexible intermediate section 10s can unfold along a non-linear pattern. This can be achieved in different ways, as will be discussed below.

[0160] According to one embodiment, even in the case of two intermediate guides, the elastically flexible intermediate section 10s is at least partially extended along an axis not parallel to the axis of symmetry of the first guide hole 40ah and / or the second guide hole 40bh in which the intermediate section is housed. In other words, the elastically flexible intermediate section 10s can be nonlinear (e.g., inclined) with respect to the rest of the contact probe (e.g., with respect to its end portions and / or central portions), and the nonlinear section can contact the walls of the guide holes 40ah and / or 40bh. In the case of the presence of a first elastically flexible intermediate section 10sa and a second elastically flexible intermediate section 10sb, depending on the application or situation, both intermediate sections can be nonlinear (possibly with opposing inclinations), or only one of them can be nonlinear.

[0161] Furthermore, according to another embodiment of the present invention shown in Figure 38 (essentially in combination with Figure 24B), even in the case of the first guide 40a and the second guide 40b, the elastically flexible intermediate section 10s can be structured as a plurality of elastic elements 10sr'' that are continuous with each other such that the elastically flexible intermediate section 10s is not linear. In particular, at least two of the above elastic elements 10s'' are offset from each other with respect to a reference axis HH (e.g., the vertical longitudinal axis HH) that is orthogonal to the first guide 40a and the second guide 40b. Advantageously, at least one of the elastic elements 10sr'' is in contact with the wall 40W of the guide hole 40a. In the case of a first elastically flexible intermediate section 10sa and a second elastically flexible intermediate section 10sb, both the first elastically flexible intermediate section 10sa and the second elastically flexible intermediate section 10sb may not be linear (possibly having a specular shape), or only one of them may not be linear.

[0162] All these embodiments greatly increase the contact of the contact probe 10 with the wall of the guide hole, because during testing, especially during compression of the contact probe 10, they deform and easily come into contact with the wall of the hole. As discussed, this advantageous effect is achieved by various shapes. The elastically flexible intermediate sections 10s are not actually limited to a specific shape. They can extend along a single oblique axis, or along different axes shifted from each other, or according to any other suitable configuration.

[0163] In summary, the present invention successfully overcomes the technical challenges and provides the above-mentioned probe head (equipped with a very short contact probe that functions as an elastic spring), solving all the shortcomings of the prior art in a simple manner.

[0164] It is possible to effectively control the strength of the contact force, and more generally, the compression of the contact probe, by appropriately forming and sizing an elastically flexible intermediate section. However, it is also possible to adjust the strength of the contact force by changing the overtravel of the probe, starting from a predetermined configuration of the elastically flexible intermediate section.

[0165] In general, regardless of the manufacturing method (for example, by removing some material from the main body to locally reduce its rigidity), a reduced-rigidity elastic section is obtained, and this elastic section is formed by elastic elements that are successive to each other and are their basic units.

[0166] By shortening the length of the contact probe described above, it can be viewed as a microspring, and the probe head of the present invention is suitable for testing high-frequency devices while solving the rigidity problem of short probes in known solutions.

[0167] Furthermore, the specific configuration described above ensures proper stability of the contact probe, preventing deformation during testing, and allowing for proper handling and easy assembly.

[0168] Advantageously, according to the present invention, first and second intermediate guides are provided, for example, for more effective retention of the contact probe and for greater flexibility in the selection of various possible configurations having intermediate stopping means and advantageous configurations. The presence of double guides, intermediate stopping means and one (preferably two) elastic sections in each hole further helps to ensure proper preloading of the contact probe.

[0169] Furthermore, various geometries for the elastic section, as well as various deformations not necessarily limited to the longitudinal direction, can be provided. For example, in addition to helical springs and symmetrical springs with stepped cross-sections, other shapes (asymmetrical shapes and shapes with lateral deformation) are also possible.

[0170] Furthermore, the probe head of the present invention, due to its advantageous shape, limits the wear of the contact pad.

[0171] Finally, it should be noted that all of the above embodiments can be combined with each other, even if their combinations are not explicitly shown or described. For example, two or more of the following can be combined: a particular shape of the turn (or elastic portion), a particular nonlinear shape of the elastically flexible intermediate section, a particular arrangement of metallization, the presence of a double guide and intermediate stopping means according to the present invention, the presence of a protruding arm, or even two or more of the above can be combined with any configuration suitable for various applications.

[0172] Clearly, to satisfy non-specific and specific requirements, those skilled in the art can make various modifications and variations to the probe head described above, all of which fall within the scope of protection of the present invention as defined by the following claims.

Claims

1. A probe head (100) for testing electronic devices, The probe head (100) is A contact probe (10) comprising at least one body (10') extending between a first end (10a) and a second end (10b), wherein the ends (10a, 10b) are configured to contact the respective contact pads (20a, 30b), A first guide (40a) having each first guide hole (40ah), A second guide (40b) having each second guide hole (40bh), Equipped with, The contact probe (10) comprises at least one intermediate section (10s) positioned between the first end (10a) and the second end (10b), the intermediate section being elastically flexible. The elastically flexible intermediate section (10s) is positioned in at least one of the first guide hole (40ah) and the second guide hole (40bh), The contact probe (10) further comprises an intermediate stopping means positioned between the first guide (40a) and the second guide (40b), the intermediate stopping means being configured to mechanically contact at least a portion of the first guide (40a) and / or the second guide (40b) in order to hold the contact probe (10) within the probe head (100). Probe head (100).

2. The probe head (100) further comprises a conductive portion (21) formed in the first guide (40a) and / or the second guide (40b), the conductive portion (21) including at least one group (40h') of the first guide hole (40ah) or the second guide hole (40bh), the conductive portion (21) in contact with a corresponding group of contact probes housed in the group (40h') of the holes and intended to transmit a predetermined type of signal, and configured to short-circuit the corresponding group of contact probes, thereby forming a conductive domain. At least a portion of the contact probe (10) is in contact with the conductive portion (21), The probe head (100) according to claim 1.

3. The probe head (100) according to claim 2, wherein the conductive portion (21) is formed on the surfaces (FA, FB) of the first guide (40a) and / or the second guide (40b).

4. The probe head (100) according to claim 2 or 3, comprising a plurality of conductive portions (21', 21'') corresponding to a plurality of conductive domains, wherein the conductive portions are arranged on the same face of the first guide (40a) and / or the second guide (40b), or on the opposite face of the first guide (40a) and / or the second guide (40b).

5. The probe head (100) according to any one of claims 1 to 4, wherein the intermediate stopping means comprises an intermediate stopper (50') having a lateral extension so as to define at least one shoulder portion (S1', S2') configured to contact the surface of the first guide (40a) and / or the surface of the second guide (40b) by its contact surface.

6. The probe head (100) according to claims 2 and 5, wherein the contact of the contact probe (10) with the conductive portion (21) is by pressing contact by one or more contact surfaces of at least one shoulder portion (S1', S2') of the intermediate stopper (50'), thereby causing an electrical connection between the contact probe (10) and the conductive portion (21).

7. The probe head (100) according to claim 6, wherein the intermediate stopper (50') comprises a plurality of projections (50p) protruding from at least one shoulder portion (S1', S2'), the projections (50p) being configured to contact at least a portion of the conductive portion (21), thereby causing an electrical connection between the contact probe (10) and the conductive portion (21).

8. The projection (50p) has a triangular shape, or The probe head (100) according to claim 7, wherein the projection is defined by the irregularities on the surface of the intermediate stopper (50').

9. The probe head (100) according to claim 5, further comprising a stopper or upper stopper (50") positioned to abut against the upper surface (FB) of the second guide (40b), wherein the upper surface (FB) is the surface furthest from the device under test.

10. The probe head (100) according to any one of claims 1 to 4, wherein the intermediate stopping means comprises a retaining element (90) formed as an elastic hook, the retaining element (90) is configured to elastically deform while inserting the contact probe (10) through one of the first guide hole (40ah) or the second guide hole (40bh) and while withdrawing the contact probe (10) through the other of the first guide hole (40ab) and the second guide hole (40bh), the retaining element (90) is configured not to deform when housed between the first guide (40a) and the second guide (40b), and is configured to contact the first guide (40a) and / or the second guide (40b) to hold the contact probe (10).

11. The probe head (100) according to any one of claims 1 to 4, wherein the intermediate stopping means comprises an elastic film (95'), such as a Kapton® sheet, disposed between the first guide (40a) and the second guide (40b).

12. The probe head (100) according to any one of claims 1 to 11, wherein the probe head (100) comprises a first elastically flexible intermediate section (10sa) in the first guide hole (40ah) and a second elastically flexible intermediate section (10sb) in the second guide hole (40bh), and the intermediate stopping means is disposed between the first elastically flexible intermediate section (10sa) and the second elastically flexible intermediate section (10sb).

13. The probe head (100) according to claim 12, wherein the first elastically flexible intermediate section (10sa) has an elastic constant (ka) different from the elastic constant (kb) of the second elastically flexible intermediate section (10sb).

14. The probe head (100) according to any one of claims 1 to 13, wherein the first guide (40a) and the second guide (40b) are positioned at an intermediate position between the semiconductor wafer (20) and the interface board (30) associated with the second end (10b) of the contact probe (10).

15. The probe head (100) according to any one of claims 1 to 14, wherein the first guide (40a) and the second guide (40b) are shifted from each other with respect to the longitudinal axis (H-H) of the contact probe (10).

16. The probe head (100) according to any one of claims 1 to 15, wherein the elastically flexible intermediate section (10s) is at least partially extended along an axis not parallel to the axis of symmetry of the first guide hole (40ah) and / or the second guide hole (40bh).

17. The probe head (100) according to any one of claims 1 to 15, wherein the elastically flexible intermediate section (10s) is structured as a plurality of elastic elements (10sr'') that are continuous with each other such that the elastically flexible intermediate section (10s) is not linear.

18. The probe head (100) according to claim 17, wherein at least two of the elastic elements (10s") are offset from each other with respect to a reference axis (H-H) perpendicular to, for example, the first guide (40a) and the second guide (40b).

19. The probe head (100) according to claim 17 or 18, wherein at least one of the elastic elements (10sr'') is in contact with the wall (40W) of the guide hole (40h).

20. The probe head (100) according to claims 12 and 17, wherein both the first elastically flexible intermediate section (10sa) and the second elastically flexible intermediate section (10sb) are not linear.

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