Probe head with contact probe having an improved configuration

Abstract

A probe head (100) for testing an electronic device is described, the probe head (100) having 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), and at least one guide (40) having at least one guide hole (40h) configured to accommodate at least a portion of the contact probe (10). The contact probe (10) comprises at least one elastically flexible intermediate section (10s) positioned between a first end (10a) and a second end (10b), 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, and at least one of these elastic elements (10sr) is in contact with the wall (40W) of the guide hole (40h).

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 provided with reference to its field of application 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 with a fine structure, particularly a plurality of contact pads of 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, typically, a probe head is used to test these circuits before the circuits integrated on the wafer are cut and assembled into chip-sealed packages.

[0004] A probe head essentially includes 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 positioned at a certain interval from each other leaving a free region or gap for the movement and possible deformation of the contact probes. The contact probes are usually formed of wires of a special alloy having good electrical and mechanical properties.

[0005] The contact probe usually extends between a first end intended to contact the pad of the 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; however, 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, very 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 the failure of these pads, 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 reliably improve 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, the probe head in particular enabling, for example, improved control of the probe's contact force to ensure optimal contact with the contact pad during testing, while ensuring proper retention of the probe and its contact with the guide hole wall. [Overview of the Initiative]

[0011] The underlying solution idea of ​​the present invention is to manufacture a probe head in which the contact probe undergoes elastic deformation during testing, which preferably occurs mainly in the longitudinal direction (though not necessarily so). In particular, the contact probe has at least one intermediate section that is substantially elastically flexible (or pliable) along the longitudinal direction, so that the contact probe functions substantially as an elastic spring, and the aforementioned elastically flexible intermediate section is not linear, so that at least a portion of it contacts the corresponding wall of the guide hole housing the contact probe.

[0012] 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; and at least one guide having at least one guide hole configured to accommodate at least a portion of the contact probe, wherein the contact probe comprises at least one intermediate section positioned between the first end and the second end and being elastically flexible (or pliable), the elastically flexible intermediate section comprising a plurality of elastic elements (or elastic half-sections or elastic sections) that are connected to one another such that the cross section of the elastically flexible intermediate section is not linear, and at least one of these elastic elements is in contact with the wall of the guide hole.

[0013] More specifically, the present invention comprises the following additional and optional features individually or in combination as appropriate.

[0014] According to one aspect of the present invention, at least two of the elastic elements can be offset from one another with respect to a reference axis perpendicular to the guide, i.e., a vertical axis (for example, the longitudinal axis of the contact probe).

[0015] According to one aspect of the present invention, these elastic elements can extend along their respective axes, and each of these axes is shifted relative to one another such that the elastic elements are offset (shifted) relative to one another.

[0016] According to one aspect of the present invention, one or more of the edges of at least these elastic elements that come into contact with the wall of the guide hole (i.e., the intersections of the edges of the elastic elements or half sections) can be beveled.

[0017] According to one aspect of the present invention, the probe head may further comprise a conductive portion formed on a guide, the conductive portion comprising at least one group of the guide holes, and in contact with a corresponding group of contact probes housed in the group of holes and intended to transmit a predetermined type of signal, and configured to short-circuit the corresponding group of contact probes, thereby forming a predetermined conductive domain, and at least a portion of the contact probes in contact with the conductive portion.

[0018] According to one aspect of the present invention, at least a portion of at least one wall of the guide hole can be covered with a conductive portion, and the contact of the probe therewith is made by the metallized wall.

[0019] According to one aspect of the present invention, at least one of these elastic elements can be configured to contact a conductive part.

[0020] In an embodiment, only the wall (or at least a portion thereof) of the probe described above is covered with a metal layer, and an elastically flexible intermediate section is in contact with the wall having the metal layer.

[0021] According to one aspect of the present invention, the length of the contact probe, measured along the longitudinal axis of the contact probe, can be less than 2000 μm, preferably less than 1000 μm, and more preferably 800 μm or less.

[0022] According to one aspect of the present invention, an elastically flexible intermediate section can be positioned in the guide so as to be at least partially housed within the guide hole.

[0023] According to one aspect of the present invention, the first end of the contact probe may include a high-hardness material such as rhodium.

[0024] According to one aspect of the present invention, at least one of these elastic elements can be provided with a protruding element configured to protrude towards an adjacent elastic element and contact a part of the adjacent elastic element during testing of the electronic device, and a part of the adjacent elastic element is separated from the protruding element in a stationary state.

[0025] The features and advantages of the probe head according to the present invention will become apparent from the following description of exemplary embodiments shown as non-limiting examples with reference to the accompanying drawings.

Brief Description of the Drawings

[0026] [Figure 1] Schematically shows a probe head in which the contact probe has an elastically flexible intermediate section. [Figure 2] Schematically shows a probe head according to an embodiment of the present invention assuming two overlapping guide portions. [Figure 3] Schematically shows a probe head according to an embodiment of the present invention providing for the presence of a lower guide and an upper guide. [Figure 4] Schematically shows a probe head according to an embodiment of the present invention assuming the presence of a conductive portion for short-circuiting a group of probes. [Figure 5] Schematically shows embodiments of the present invention in which the conductive portion is arranged in various ways in the guide of the probe head. [Figure 6] Schematically shows embodiments of the present invention in which the conductive portion is arranged in various ways in the guide of the probe head. [Figure 7] Schematically shows embodiments of the present invention in which the conductive portion is arranged in various ways in the guide of the probe head. [Figure 8A] Schematically shows a probe head according to the present invention in which there is a non-linear elastically flexible intermediate section. [Figure 8B] Schematically shows a probe head according to the present invention in which there is a non-linear elastically flexible intermediate section. [Figure 9] A schematic diagram of a probe head according to a further embodiment of the present invention is shown. [Figure 10] A schematic diagram of a probe head according to a further embodiment of the present invention is shown. [Modes for carrying out the invention]

[0027] Referring to the drawings, a probe head for testing an electronic device manufactured according to the present invention is schematically shown overall by reference numeral 100.

[0028] It should be noted that the figures are schematic and not drawn to scale, but rather to highlight key 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.

[0029] Furthermore, unless explicitly stated otherwise, please note that the steps of the described process can be reversed as needed.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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 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.

[0034] 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 reference numeral 30 and commonly defined as an "interface board". 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.

[0035] 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.

[0036] Although the ends 10a and 10b in the attached drawings are shown to end in a pointed shape, they are clearly not limited to this and can have any shape as needed and / or in accordance with the circumstances.

[0037] 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.

[0038] 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 particularly between the guide 40 and the PCB 30. This frame F is omitted in subsequent figures solely for the sake of simplicity in illustration.

[0039] 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.

[0040] 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 includes at least one intermediate section 10s positioned between the first end 10a and the second end 10b and being elastically flexible (flexible) 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.

[0041] In particular, in a preferred embodiment, the elastically flexible intermediate section 10s is appropriately configured such that the contact probe 10 exerts a contact force FC substantially 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 an elastically weaker portion and an elastically stronger portion of the elastically flexible intermediate section 10s, and similarly, it is possible to provide a (not necessarily symmetrical) helical shape of the above-mentioned elastically flexible intermediate section 10s.

[0042] 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).

[0043] 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 the spring that is repeated along the above-mentioned longitudinal axis HH, as detailed below, thereby forming a predetermined elastic pattern.

[0044] 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.

[0045] In the embodiments described above, 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.

[0046] 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.

[0047] 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.

[0048] 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).

[0049] When an elastically flexible intermediate section 10s having a longer length (for the same total length of the contact probe 10, which is less than 2000 μm, preferably 800 μm or less, as described above) is manufactured, the stress on the contact probe 10 can be reduced.

[0050] 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 2, 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 can be structured with a first guide portion 40' and a second guide portion 40''. The second guide portion 40'' is initially constructed structurally independently of the first guide portion 40', then associated with it, and in particular, after the latter is introduced into the first guide portion 40', it is attached to the contact probe 10. For example, the second guide portion 40'' can be superimposed on the first guide portion 40', or it can 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.

[0051] 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.

[0052] Alternatively, referring to Figure 3, 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.

[0053] In one embodiment (not shown), the lower guide hole 45lh and the upper guide hole 45uh can be shifted as far as possible relative to each other, that is, with respect to a single probe, their centers are not located 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.

[0054] Furthermore, 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 on 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.

[0055] Therefore, in high-frequency applications (especially RF applications), ground probes (and power probes as well) are short-circuited through metallization on the guide, thereby short-circuiting probes in the same domain and making ground available within the probe head to connect shields where possible. Also, when devices with different ground / power domains are joined on a PCB, metallization can reduce loop inductance between the power and associated ground.

[0056] 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.

[0057] Thus, it is clear that the presence of metallization on the guide, which short-circuits the probe group and creates a common conductive surface, reduces noise and improves the frequency performance of the probe head.

[0058] Similarly, it is also possible to short-circuit signal probes with each other, for example, using loopback technology.

[0059] For this purpose, according to an embodiment of the present invention (as shown in Figure 4), 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 groups of contact probes, which are intended to transmit signals of the same kind, in particular to transmit a predetermined ground or power signal or an operating signal.

[0060] 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.

[0061] In the non-limiting embodiment shown in Figure 4, 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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 4) or positioned on its lower surface FA (as shown in Figure 5), and can also be formed inside the guide 40 (i.e., embedded within the guide 40 as depicted in Figure 6).

[0066] Furthermore, it is possible to provide a first conductive part that short-circuits the ground probe and a second conductive part that short-circuits the power probe located on the opposite side of the guide, and similarly, many other configurations can be provided, such as those described in the International Patent Application No. PCT / EP2017 / 082180 in the name of the present applicant.

[0067] As a simple example, as shown in Figure 7, 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 7) and / or embedded in the guide 40, or even located on the same side of the guide 40.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] Furthermore, in embodiments not shown, it is possible that only a metal layer is present that at least partially covers the walls of the holes, and the elastically flexible intermediate section is in contact with this layer.

[0074] Given 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 to always ensure the aforementioned sliding contact between the probe and the hole (however, in some configurations, this contact can be a pressing contact, for example, the abutment of a stopper against the conductive portion as discussed below).

[0075] Advantageously, according to the present invention, as shown in Figures 8A and 8B, the elastically flexible intermediate section 10s is divided into a plurality of elastic sub-parts or elastic elements or elastic half-sections (indicated by reference no. 10sr"), and these elastic sub-parts or elastic elements or elastic half-sections are not aligned with respect to each other with respect to the same reference axis (for example, they are shifted from each other with respect to the longitudinal axis HH of the probe when taken as a reference).

[0076] For example, the elastic elements 10sr'' unfold along their respective axes, which are as parallel as possible to each other (and indicated by reference numbers H'-H', H''-H''), and these axes do not necessarily coincide with the longitudinal axis HH of the probe.

[0077] In other words, the elastically flexible intermediate section 10s is formed by various sections (i.e., elastic elements) that cannot be aligned along the longitudinal axis of the contact probe 10, i.e., along the vertical reference axis.

[0078] The elastic elements 10sr'' are continuous and uninterrupted from one another, with their respective axes of symmetry being (appropriately shifted) and not coincident with each other, and are shifted from one another (i.e., offset along the vertical reference axis) to define an elastically flexible intermediate section that is not a straight line as a whole.

[0079] Ideally, at least one of these elastic elements 10sr" contacts the wall 40W of the guide hole 40h, in particular the conductive portion 21 extending within the hole (as shown in Figure 8B), thus ensuring proper and simple retention of the contact probe 10 while establishing the desired electrical contact with the metallization.

[0080] Therefore, generally speaking, in short, according to the present invention, the elastically flexible intermediate section 10s is structured as a plurality of elastic elements 10sr'' that are continuous with each other such that the cross-section of the elastically flexible intermediate section is nonlinear, and at least one of the elastic elements is in contact with the wall of the guide hole. In particular, at least two of the elastic elements 10sr'' can be shifted from each other with respect to a reference axis orthogonal to the guide, i.e., a vertical axis (for example, the longitudinal axis HH of the contact probe 10 as described above).

[0081] Ideally, these elastic elements 10sr'' of the elastically flexible intermediate section 10s are connected to one another such that the elastically flexible intermediate section 10s is nonlinear even when it is at rest (i.e., not only when compressed), and contact with the wall of the guide hole occurs through at least one of the elastic elements 10sr'' (i.e., through at least a portion of the elastically flexible intermediate section 10sr'' due to its shape).

[0082] In one embodiment, the elastically flexible intermediate section 10s is formed in a different shape from the rest of the contact probe and thus corresponds to a different part of the contact probe (for example, a different part with respect to the end portion).

[0083] 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 portion-loop) are beveled (i.e., provided with a beveled surface 10bl) in order to avoid interlocking of the contact probe 10 in the guide hole, in particular interlocking during assembly.

[0084] This geometry 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, according to the present invention, the elastic section 10s has a larger cross-sectional dimension (at least locally) than the cross-sectional dimension of the guide hole 40h (as shown in Figures 8A and 8B), 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 8B).

[0085] Next, referring to the embodiment in Figure 9, the first end 10a (i.e., the lower end) of the contact probe 10 may include a high-hardness material 10ins, in particular a material having higher hardness than the material of the probe body 10', such as rhodium.

[0086] Clearly, Figure 9, 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 on the first lower end 10a.

[0087] This embodiment in Figure 9 ensures a long service life for the contact probe 10 while maintaining high-quality contact.

[0088] Furthermore, referring to Figure 10, it should be noted that the actual length of the contact probe 10 is increased by the presence of the elastically flexible intermediate section 10s, which is characterized by several loops (and, more generally, by various elastic elements 10sr" or a continuum of parts or elastic subsections forming the elastic section, as described in the above embodiments). To solve this problem, the elastically flexible intermediate section 10s is provided with at least one protruding element or bump (reference number B) on at least one of its elastic elements, configured to contact an adjacent elastic element during testing of the device under test (i.e., when the elastic section is compressed), thereby causing an electrical connection between the elastic elements, shortening the actual length of the elastically flexible intermediate section 10s, and improving the performance of the probe head 100.

[0089] As a result, in this embodiment, at least one of the elastic elements of the elastically flexible intermediate section 10s includes a protruding element B configured to project toward an adjacent elastic element and to contact a portion of the adjacent elastic element during testing of the electronic device, the portion being separated from the protruding element B in a stationary state (i.e., when the elastic section is not compressed).

[0090] In other words, in this embodiment, the elastically flexible intermediate section 10s includes protruding elements B configured to create electrical contact between the portions of the elastically flexible intermediate section 10s that would otherwise be separated.

[0091] The protruding element B can be formed integrally with the elastically flexible intermediate section 10s, but the present invention is not limited by the manufacturing method.

[0092] For example, the protruding element B can be formed on the edge or loop of each elastic element, but other configurations are also possible.

[0093] It is also possible to provide multiple protruding elements B, the number of which is selected based on the length selected during compression of the elastically flexible intermediate section 10s, that is, based on the length to be obtained. Since the length of the elastic section becomes longer when compressed as there are more protruding elements B, it is preferable to limit the number of protruding elements B.

[0094] Finally, additional stopping mechanisms, such as stoppers that abut against guides or clips interfering with holes (for example, at the top and / or bottom), which are not shown in the attached diagrams, may be provided in combination with the geometry discussed above.

[0095] 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.

[0096] It is possible to effectively control the strength of the contact force, and more generally, the compression of the contact probe, and to appropriately form and shape an elastically flexible intermediate section.

[0097] 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, when connected to one another, represent their basic units.

[0098] 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 stiffness problem of short probes in known solutions.

[0099] Advantageously, according to the present invention, the above configuration makes it possible to ensure proper stability of the contact probe, as well as to properly hold it and assemble it easily.

[0100] Unlike vertical probe heads manufactured according to conventional technology, probe heads according to several embodiments further allow the use of a single guide, where the contact probe deforms within the guide hole. The use of a single guide simplifies the assembly process of the probe head.

[0101] Furthermore, the probe head of the present invention, due to its advantageous shape, limits the wear of the contact pad.

[0102] 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, certain nonlinear shapes of the elastically flexible intermediate section according to the present invention can be combined with certain arrangements of metallization or various configurations of guides, or even with the presence of stopping means, and similarly with other configurations. In fact, most of the figures convey a contact probe having an elastically flexible intermediate section having a stepped section for simplicity, but the various embodiments shown for the stepped section are also applicable to the geometry according to the present invention.

[0103] 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 guide (40) having at least one guide hole (40h) configured to accommodate at least a portion of the contact probe (10), 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 structured as a plurality of elastic elements (10sr'') that are continuous with each other so as not to be linear, and at least one of the plurality of elastic elements (10sr'') is in contact with the wall (40W) of the guide hole (40h). Probe head (100).

2. The probe head (100) according to claim 1, wherein at least two of the plurality of elastic elements (10s'') are offset from each other with respect to a reference axis (H-H) perpendicular to the guide (40).

3. The probe head (100) according to claim 1 or 2, wherein the plurality of elastic elements (10s") extend along their respective axes (H'-H', H''-H''), and the respective axes (H'-H', H''-H'') are shifted relative to each other such that the plurality of elastic elements (10s'') are offset relative to each other.

4. The probe head (100) according to any one of claims 1 to 3, wherein one or more of the edges of the plurality of elastic elements (10sr'') that contact the wall (40W) of the guide hole (40h) are beveled.

5. The probe head (100) further comprises a conductive portion (21) formed on the guide (40), the conductive portion (21) including at least one group (40h') of the guide holes (40h), and contacting 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, and at least a portion of the contact probe (10) contacting the conductive portion (21), according to any one of claims 1 to 4.

6. The probe head (100) according to claim 5, wherein at least a portion of at least one wall of the guide hole (40h) is covered by the conductive portion (21), and contact between the contact probe and the conductive portion is also made by the metallized wall.

7. The probe head (100) according to claim 5 or 6, wherein at least one of the plurality of elastic elements (10sr'') is configured to contact the conductive portion (21).

8. The probe head (100) according to any one of claims 1 to 7, wherein the length of the contact probe (10) measured along the longitudinal axis (H-H) of the contact probe (10) is less than 2000 μm, preferably less than 1000 μm, and more preferably 800 μm or less.

9. The probe head (100) according to any one of claims 1 to 8, wherein the elastically flexible intermediate section (10s) is positioned on the guide (40) so as to be at least partially housed within the guide hole (40h).

10. The probe head (100) according to any one of claims 1 to 9, wherein the first end (10a) of the contact probe (10) comprises a high-hardness material such as rhodium.

11. The probe head (100) according to any one of claims 1 to 10, comprising a protruding element (B) configured such that at least one of the plurality of elastic elements protrudes toward an adjacent elastic element and contacts a portion of the adjacent elastic element during testing of the electronic device, wherein the portion of the adjacent elastic element is separated from the protruding element (B) in a stationary state.

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