Probe head for testing electronic devices, having a contact probe with improved elastic properties.

Abstract

A probe head (100) for testing electronic devices is described herein, the probe head (100) comprises at least one contact probe (10) having a body (10') extending along a longitudinal axis (HH) between a first end (10a) and a second end (10b), the ends (10a, 10b) configured to contact respective contact pads (20a, 30b), and the body (10') having a maximum thickness (Tmax) measured along a direction perpendicular to the longitudinal axis (HH), 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 intermediate section (10s) positioned between a first end (10a) and a second end (10b) and being elastically flexible, the elastically flexible intermediate section (10s) comprising at least one reduction portion having a thickness (Tel) less than the maximum thickness (Tmax) of the body (10') of the contact probe (10).

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 in which a plurality of contact pads, i.e., a plurality of pads of a microstructure, particularly an electronic device integrated on a semiconductor wafer, are configured to electrically contact 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 encapsulation packages.

[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 (generally, there are a lower guide and an upper guide). These plate-shaped supports are provided with appropriate guide holes and are positioned at a distance from each other leaving a free region or gap for the movement and possible deformation of the contact probes, and the contact probes are usually formed of wires of a special alloy having good electrical and mechanical properties.

[0005] A contact probe generally 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 or overdrive) 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 carefully 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.

[0007] Therefore, it is especially important to ensure proper contact of the contact probe with various pads during testing.

[0008] 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.

[0009] 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.

[0010] 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.

[0011] 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, and in particular, a contact probe having elastic properties that ensure optimal contact with the contact pad during testing. [Overview of the Initiative]

[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 occurring mainly in the longitudinal direction (though not necessarily so). In particular, the contact probe has at least one elastically flexible (flexible) intermediate section, so that the contact probe functions substantially as an elastic spring, and the aforementioned elastically flexible intermediate section is thinner than the rest of the probe body, thus reducing the overall rigidity of the contact probe.

[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 including a body extending along a longitudinal axis between a first end and a second end, the ends configured to contact respective contact pads, the body comprising at least one contact probe having a maximum thickness measured along a direction perpendicular to the longitudinal axis, and at least one guide having at least one guide hole configured to accommodate at least a portion of the contact probe, the contact probe comprising at least one intermediate section located between the first end and the second end and being elastically flexible (flexible), the elastically flexible intermediate section comprising at least one reduction portion having a thickness thinner than the maximum thickness of the body of the contact probe.

[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 entire elastically flexible intermediate section can have a thickness thinner than the maximum thickness of the body of the contact probe.

[0016] According to one aspect of the present invention, the thickness of the reduced portion of the elastically flexible intermediate section can be in the range of 5 μm to 195 μm overall, while the maximum thickness of the contact probe body can be in the range of 10 μm to 200 μm.

[0017] According to one aspect of the present invention, the elastically flexible intermediate section can be a single section between a first end and a second end, which is obtained by removing material from at least one side of the body of the contact probe.

[0018] According to one aspect of the present invention, an elastically flexible intermediate section can be divided into a plurality of elastically flexible intermediate sections, each of which has at least one reduction portion having a thickness less than the maximum thickness of the body of the contact probe. In any case, in this embodiment, the sum of the thicknesses of the reduction portions of a single elastically flexible intermediate section is less than the maximum thickness of the body of the contact probe, and the plurality of elastically flexible intermediate sections take the form of arms separated from each other by their respective openings extending along the longitudinal axis of the contact probe.

[0019] According to one aspect of the present invention, a contact probe may comprise two elastically flexible intermediate sections separated from each other by a single opening.

[0020] According to one aspect of the present invention, the thickness of each of the two elastically flexible intermediate section reduction portions can be in the range between 5 μm and 100 μm.

[0021] According to one aspect of the present invention, the contact probe may comprise a first elastically flexible intermediate section, a second elastically flexible intermediate section, and a third elastically flexible intermediate section.

[0022] According to one aspect of the present invention, a first elastically flexible intermediate section can be separated from a second elastically flexible intermediate section by a first opening, and the second elastically flexible intermediate section can be separated from a third elastically flexible intermediate section by a second opening.

[0023] According to one aspect of the present invention, the thickness of each of the first, second, and third elastically flexible intermediate section reduction portions can be in the range between 5 μm and 95 μm.

[0024] According to one aspect of the present invention, the elastically flexible intermediate section can have a thickness that is less than the maximum thickness of the body of the contact probe.

[0025] 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 even more preferably 800 μm or less.

[0026] According to one aspect of the present invention, the elastically flexible intermediate section can extend along the longitudinal axis with a length of 80 μm to 1000 μm and a pitch of 100 μm to 5 μm.

[0027] According to one aspect of the present invention, the elastically flexible intermediate section can be arranged in the guide so as to be at least partially accommodated in the guide hole.

[0028] According to one aspect of the present invention, the probe head can include a lower guide and an upper guide separated from each other by a gap, and the lower guide and the upper guide each include a respective lower guide hole and upper guide hole for accommodating the contact probe.

[0029] According to one aspect of the present invention, the elastically flexible intermediate section can be arranged in the gap between the lower guide and the upper guide.

[0030] According to one aspect of the present invention, the contact probe can include stopping means formed on its body, and the stopping means is configured to mechanically contact at least a part of the guide so as to ensure the retention of the contact probe within the probe head.

[0031] According to one aspect of the present invention, the stopping means may comprise a stopper having a lateral extension to define at least one shoulder configured to abut against a surface of the guide, the surface being opposite to the surface of the guide facing the device under test, and / or the stopping means comprises at least one clip configured to mechanically interfere with a guide hole and to contact a corresponding wall of the guide hole, the clip protruding from the body of the contact probe and configured to elastically deform while in contact with the wall of the guide hole, thereby ensuring the retention of the contact probe by mechanical interference with the guide hole.

[0032] According to one aspect of the present invention, an elastically flexible intermediate section can be embedded in a polymer material.

[0033] According to one aspect of the present invention, an elastically flexible intermediate section can be configured to determine the strength and / or direction of the contact force exerted on the contact pad by the contact probe, and the contact probe functions as a spring.

[0034] According to one aspect of the present invention, an elastically flexible intermediate section can be configured such that the contact force exerted on the contact pad by the contact probe is substantially directed along the longitudinal axis with substantially zero lateral component.

[0035] According to one aspect of the present invention, the above-mentioned contact force may also have a component along an axis different from the longitudinal axis, for example, along the transverse axis.

[0036] According to one aspect of the present invention, the contact probe may have a rectangular cross-section.

[0037] According to one aspect of the present invention, the thickness of the reduced portion can be thinner than the maximum thickness when measured along one of the minor sides of the rectangular cross-section.

[0038] The features and advantages of the probe head according to the present invention will become apparent from the following description of a typical embodiment shown as a non-limiting example, with reference to the accompanying drawings. [Brief explanation of the drawing]

[0039] [Figure 1] The probe head, which features an elastically flexible intermediate section, is schematically shown. [Figure 2] A schematic diagram of a contact probe of a probe head according to the present invention, particularly a side view thereof, is shown. [Figure 3] A schematic diagram of a contact probe of a probe head according to one embodiment of the present invention, particularly a side view thereof, is shown. [Figure 4] A schematic diagram of a contact probe of a probe head according to one embodiment of the present invention, particularly a side view thereof, is shown. [Figure 5] A probe head according to one embodiment of the present invention is shown. [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 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 9bis] 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 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 11] A schematic diagram of a probe head according to one embodiment of the present invention, in which the contact probe is equipped with a clip-shaped stopping mechanism. [Figure 12] A combination of the embodiments shown in Figures 10 and 11 is presented. [Figure 13] 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. [Modes for carrying out the invention]

[0040] Referring to the drawings, a probe head for testing an electronic device manufactured according to the present invention is schematically shown overall at 100.

[0041] 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.

[0042] Furthermore, please note that unless explicitly stated otherwise, the steps of the described process can be reversed as needed.

[0043] 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.

[0044] 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.

[0045] Referring to the cross-sectional view in Figure 1 (which is essentially a cross-section of the front view), 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.

[0046] 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.

[0047] 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 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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 essentially functions as an elastic spring.

[0055] 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 oriented along the longitudinal axis HH on the contact pads 20a and 30b, but in other embodiments, there may be forces with other components, such as generating a scrubbing motion. In fact, it is possible to configure the elastically flexible intermediate section 10s 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 the elastically flexible intermediate section 10s with a not-so-symmetrical helical shape.

[0056] The presence of the contact force FC primarily in the longitudinal direction reduces the risk of interlocking of the contact probe 10, but embodiments having various force components are not excluded, as described above. However, as previously stated, according to other embodiments of the present invention, the contact force FC can also have a lateral component. That is, the elastically flexible intermediate section 10s can be configured such that the contact force FC exerted on the contact pad by the contact probe 10 has both longitudinal / axial and lateral components, for example, to cause scrubbing of the contact tip.

[0057] For example, in one embodiment of the present invention, the elastically flexible intermediate section 10s may have a wall that is less elastic than the wall on the opposite side, thereby causing lateral movement during overtravel.

[0058] According to one embodiment of the present invention, the elastically flexible intermediate section 10s may be equipped with an elastic deformation mechanism (also called a further elastic element, as described later in relation to Figure 11) having arms having different elasticity (for example, one arm may be more elastically weaker than the other arm), as a result, the elastic deformation of the section may occur not only along the longitudinal direction but also along other directions, for example, causing a scrubbing motion of the first end of the contact probe on the pad of the device under test.

[0059] According to one aspect of the present invention, the elastically flexible intermediate section 10s may also be configured to twist during contact with the device under test and therefore during overtravel.

[0060] 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).

[0061] 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 like a helical spring, although such a configuration is clearly possible).

[0062] 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.

[0063] 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 (thus generally having a long side and a short side), but other dimensions can obviously also be provided.

[0064] 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.

[0065] Furthermore, the body 10' of the contact probe 10 has a maximum thickness, which is expressed herein as "Tmax," and this thickness is measured along a direction perpendicular to (crossing) the longitudinal axis HH of the contact probe 10.

[0066] 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).

[0067] Thanks to the elastic properties of the contact probe 10, which is an extremely short microprobe that is easy to inspect at very high frequencies, the configuration shown here ensures optimal contact with the pads of the device under test and / or interface board.

[0068] Referring next to Figure 2 (showing a side view of the contact probe 10), advantageously, according to the present invention, in order to further reduce the rigidity of the contact probe 10, the elastically flexible intermediate section 10s comprises at least one reducing portion having a thickness (represented by the reference numeral "Tel") that is thinner than the maximum thickness Tmax of its body 10'.

[0069] As described above, the elastically flexible intermediate section 10s is structured as a plurality of elastic elements (or elastic sub-parts) repeated along at least the longitudinal axis HH of the contact probe, thereby forming a predetermined elastic pattern without being limited by a specific shape, and the portion of the probe having a thinner thickness Tel lies in the above elastic pattern (in other words, the thickness reduction occurs in the elastic pattern that forms the elastically flexible intermediate section 10s which is different from the rest of the contact probe, for example, from the end portion).

[0070] In the embodiment shown in the figure, the entire elastically flexible intermediate section 10s has a thickness Tel that is thinner than the maximum thickness Tmax of the body 10' of the contact probe 10. In other words, in this embodiment, the reduced portion of the contact probe 10 coincides with the entire elastically flexible intermediate section 10s.

[0071] In the illustrated embodiment (and considering the contact probe 10 having a rectangular cross-section with a pair of long sides and a pair of short sides), it should be noted that the thickness of the probe body 10' is reduced along only one of the two lateral directions. In particular, the thickness of the probe body 10' in the elastically flexible intermediate section 10s is thinner than when measured along the short side of the contact probe 10 (i.e., the probe's thickness is reduced according to its side view), whereas the elastically flexible intermediate section 10s is not reduced along the long side of the contact probe (i.e., according to its front view). However, other configurations in which the thickness is reduced along the long side or along all sides are possible, but the above embodiment is preferred because it allows for optimal elastic properties of the contact probe 10.

[0072] For example, the thickness Tel of the reduced portion of the elastically flexible intermediate section 10s generally falls within the range of 5 μm to 195 μm, while the maximum thickness Tmax of the body 10' of the contact probe 10 falls within the range of 10 μm to 200 μm (obviously always having a value greater than the thickness Tel). These values ​​can be varied based on the application and specific shape of the elastically flexible intermediate section 10s.

[0073] In one embodiment, as shown in Figure 2, the elastically flexible intermediate section 10s is a single section located between the first end 10a and the second end 10b, which is obtained by removing material from at least one side of the body 10' of the contact probe 10. In the embodiment shown in the figure, the reduced portion of the contact probe 10 is obtained by symmetrically removing material from two opposing sides of the probe body 10'.

[0074] Next, referring to Figures 3 and 4, in another embodiment of the present invention, the elastically flexible intermediate section 10s is divided into a plurality of elastically flexible intermediate sections (each represented by reference numeral 10s'), each having at least one reduction portion having a thickness thinner than the maximum thickness Tmax of the body 10' of the contact probe 10 (now represented by reference numeral Tel'). In this way, it is possible to form different elastic sections at independent levels.

[0075] More specifically, in the embodiment shown in the figure, a number of elastically flexible intermediate sections 10s' take the form of arms separated from one another by their respective openings (represented by reference numeral 10op) that extend along the longitudinal axis HH of the contact probe 10.

[0076] More specifically, a number of elastically flexible intermediate sections 10s' are arranged along the short side of the contact probe, but other less preferred configurations can also be provided.

[0077] In any case, the sum of the reduced thicknesses Tel' of all the individual elastically flexible intermediate sections 10s' is always thinner than the maximum thickness Tmax of the body 10' of the contact probe 10, and therefore, as a result, the thickness of the elastic section is relatively ineffective, and the overall rigidity of the probe is reduced.

[0078] Even in this case, in the embodiment shown in the figure, a single elastically flexible intermediate section 10s' as a whole has a thinner thickness than the rest of the body 10', and therefore, a single reduction portion coincides with the single intermediate section described above. In other words, each of the elastically flexible intermediate sections 10s' as a whole has a thickness Tel' that is thinner than the maximum thickness Tmax of the body 10' of the contact probe 10, but the present invention is not limited to this particular configuration.

[0079] In the embodiment shown in Figure 3, the contact probe 10 comprises two elastically flexible intermediate sections 10s' separated from each other by a single opening 10op.

[0080] In this case, the thickness Tel' of each of the reduced portions of the two elastically flexible intermediate sections 10s' is in the range of 5 μm to 100 μm. The value of the maximum thickness Tmax in this case can be adapted depending on the value of the reduced thickness Tel'. For example, for a thickness Tel' equal to 100 μm, a thickness Tmax equal to 200 μm (as seen above) can be used. In any case, these values ​​can be varied based on the application and specific shape of the elastically flexible intermediate section 10s.

[0081] Furthermore, in another embodiment shown in Figure 4, the contact probe 10 comprises a first elastically flexible intermediate section, a second elastically flexible intermediate section, and a third elastically flexible intermediate section, that is, it is formed by three arms that are adjacent to each other along the short side of the contact probe 10. The first elastically flexible intermediate section is separated from the second elastically flexible intermediate section by a first opening, and the second elastically flexible intermediate section is separated from the third elastically flexible intermediate section by a second opening.

[0082] In this case, the thickness Tel' of each of the three elastically flexible intermediate sections 10s' is in the range between 5 μm and 95 μm. In this case, the value of the maximum thickness Tmax can be adapted based on the value of Tel'. For example, for a thickness Tel' equal to 95 μm, a thickness Tmax equal to 200 μm (as seen above) can be used. Even in this case, these values ​​can be varied based on the application and specific shape of the elastically flexible intermediate section 10s.

[0083] 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 accommodated in the guide hole 40h. In other words, an embodiment has been described so far that provides for the presence of a single intermediate guide 40 accommodating the elastic section of the contact probe 10. This embodiment is easier to assemble and has lower production costs.

[0084] Alternatively, referring to Figure 5, 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.

[0085] In one embodiment (not shown), the lower guide hole 45lh and the upper guide hole 45uh do not have to be aligned with each other (they can be shifted), 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.

[0086] Next, referring to Figures 6-12, 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.

[0087] In the case of a contact probe 10 provided with a number of elastic sections 10s', each of them may have one of the shapes described herein.

[0088] For example, among the various possible geometries, the elastically flexible intermediate section 10s can have a shape with a serrated development (Figure 6) 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 7 and 8). 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.

[0089] 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 toward one another along the longitudinal axis HH (Figure 9), 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.

[0090] More specifically, referring to the geometry described above, the embodiment in Figure 6 allows for increased overdrive of the contact probe 10, while the embodiment in Figure 7 helps maintain the contact probe 10 in a linear configuration, while simultaneously increasing its strength and rigidity. On the other hand, the embodiment in Figure 8, 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 7, but simultaneously increases its flexibility and decreases its strength. The embodiment in Figure 9 replicates the effect of two joined standard springs, with the aim of increasing the symmetry of the contact probe 10 and maintaining good flexibility.

[0091] Furthermore, the deformations shown in Figures 7bis, 8bis, and 9bis correspond to the geometries of Figures 7, 8, and 9, 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.

[0092] 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 (in some cases, it is also possible to use a single elastically flexible intermediate section 10s' having different shapes from each other).

[0093] Referring next to Figure 10, 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.

[0094] 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.

[0095] In a particular embodiment of Figure 10, the stopping means is formed as a stopper having a lateral extension (and 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 (and thus having at least one contact surface). Thus, the stopper 50 protrudes from at least one wall of the contact probe 10 (overall, the stopper 50 bonded to the probe body portion can have a lateral extension larger than that of the guide hole for properly holding the contact probe).

[0096] 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 employed (for example, the stopper may protrude from only one wall of the contact probe 10 rather than from two opposing walls as depicted, and may also have any suitable configuration).

[0097] In addition or alternatively, in one embodiment of the present invention depicted in Figure 11, 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.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] Clearly, a combination of stopper 50 and clip 60 can also be provided, as shown in the embodiment of Figure 12.

[0102] In general, it is preferable that the clip 60 has less rigidity 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.

[0103] Next, referring to the embodiment in Figure 13, the elastically flexible intermediate section 10s can be at least partially embedded in a polymer material (identified here by reference no. P), thereby ensuring better overall mechanical stability of the contact probe 10. 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.

[0104] 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.

[0105] 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.

[0106] Clearly, this embodiment can be combined with other embodiments, such as the presence of a stopping means, any of the geometries described herein, or any of the guide configurations.

[0107] 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.

[0108] By appropriately forming and sizing an elastically flexible intermediate section, it is thus possible to effectively control the strength of the contact force, and more generally, the compression of the contact probe.

[0109] Advantageously, according to the present invention, the thickness of the elastic section of the probe described above is made thinner so as to further reduce its rigidity.

[0110] The above-mentioned elastic sections, separated by longitudinal slots or openings, can also be formed at multiple levels independent of each other, while still maintaining the overall reduced thickness of the above-mentioned elastic sections.

[0111] Generally, this results in an elastic section with significantly reduced rigidity.

[0112] By shortening the length of the contact probe described above, it can therefore be viewed as a microspring, making the probe head of the present invention suitable for testing high-frequency devices while simultaneously solving the rigidity problem of short probes in known solutions.

[0113] Furthermore, thanks to its advantageous shape, the probe head according to the present invention can significantly limit the wear of the contact pad.

[0114] For the elastic section, various geometries, as well as various directions and types of deformation that are not necessarily solely longitudinal, can be assumed. The specific configuration described above makes it possible to ensure the proper stability of the contact probe, preventing deformation during testing, as well as enabling proper retention and easy assembly.

[0115] 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. Although most of the figures show elastically flexible intermediate sections having stepped cross-sections to avoid complicating the explanation, all of the various embodiments of the present invention can also be applied to other geometries described (which can sometimes be combined with each other). For this reason, configurations with reduced thickness are applicable to all possible designs for the above elastic sections.

[0116] 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 contact probe (10) having a body (10') extending along a longitudinal axis (H-H) between a first end (10a) and a second end (10b), wherein the ends (10a, 10b) are configured to contact respective contact pads (20a, 30b), and the body (10') has a maximum thickness (Tmax) measured along a direction perpendicular to the longitudinal axis (H-H), 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), wherein the intermediate section (10s) is elastically flexible. The elastically flexible intermediate section (10s) comprises at least one reduction portion having a thickness (Tel, Tel') that is thinner than the maximum thickness (Tmax) of the body (10') of the contact probe (10). Probe head (100).

2. The probe head (100) according to claim 1, wherein the entire elastically flexible intermediate section (10s) has a thickness (Tel) that is thinner than the maximum thickness (Tmax) of the body (10') of the contact probe (10).

3. The probe head (100) according to claim 1 or 2, wherein the thickness (Tel) of the reduced portion of the elastically flexible intermediate section (10s) is generally in the range of 5 μm to 195 μm, and the maximum thickness (Tmax) of the body (10') of the contact probe (10) is in the range of 10 μm to 200 μm.

4. The probe head (100) according to any one of claims 1 to 3, wherein the elastically flexible intermediate section (10s) is a single section between the first end (10a) and the second end (10b), and the single section is obtained by removing material from at least one side of the body (10') of the contact probe (10).

5. The probe head (100) according to any one of claims 1 to 3, wherein the elastically flexible intermediate section (10s) is divided into a plurality of elastically flexible intermediate sections (10s'), each of the plurality of elastically flexible intermediate sections (10s') has at least one reduced portion having a thickness (Tel') that is thinner than the maximum thickness (Tmax) of the body (10') of the contact probe (10), the sum of the thicknesses (Tel') of all the reduced portions of a single elastically flexible intermediate section (10s') is thinner than the maximum thickness (Tmax) of the body (10') of the contact probe (10), and the plurality of elastically flexible intermediate sections (10s') take the form of arms separated from each other by their respective openings (10op) extending along the longitudinal axis (H-H) of the contact probe (10).

6. The probe head (100) according to claim 5, wherein the contact probe (10) comprises two elastically flexible intermediate sections (10s') separated from each other by a single opening (10op).

7. The probe head (100) according to claim 6, wherein the thickness (Tel') of each of the reduced portions of the two elastically flexible intermediate sections (10s') is in the range of 5 μm to 100 μm.

8. The probe head (100) according to claim 5, wherein the contact probe (10) comprises a first elastically flexible intermediate section, a second elastically flexible intermediate section, and a third elastically flexible intermediate section, the first elastically flexible intermediate section being separated from the second elastically flexible intermediate section by a first opening, and the second elastically flexible intermediate section being separated from the third elastically flexible intermediate section by a second opening.

9. The probe head (100) according to claim 8, wherein the thickness (Tel') of each of the first, second, and third elastically flexible intermediate section reduction portions is in the range of 5 μm to 95 μm.

10. The probe head (100) according to any one of claims 5 to 9, wherein the plurality of elastically flexible intermediate sections (10s') have a thickness (Tel') that is thinner than the maximum thickness (Tmax) of the body (10') of the contact probe (10).

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

12. The probe head (100) according to any one of claims 1 to 11, wherein the elastically flexible intermediate section (10s) extends along the longitudinal axis (H-H) for a length of 80 μm to 1000 μm and at a pitch of 5 μm to 100 μm.

13. The probe head (100) according to any one of claims 1 to 12, 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).

14. The probe head (100) according to any one of claims 1 to 12, comprising a lower guide (45l) and an upper guide (45u) separated from each other by a gap (G), wherein the lower guide (45l) and the upper guide (45u) each comprise a lower guide hole (45lh) and an upper guide hole (45uh) for housing the contact probe (10).

15. The probe head (100) according to claim 14, wherein the elastically flexible intermediate section (10s) is positioned in the gap (G) between the lower guide (45l) and the upper guide (45u).

16. The probe head (100) according to any one of claims 1 to 15, wherein the contact probe (10) comprises a stopping means formed on the body (10') and configured to mechanically contact at least a portion of the guide (40) to cause the contact probe (10) to be held in place within the measuring head (100).

17. The stopping means comprises a stopper (50) having a lateral extension that defines at least one shoulder portion (S1, S2) configured to abut against the surface (FB) of the guide (40), wherein the surface (FB) is on the opposite side of the surface (FA) of the guide (40) that faces the device under test, and / or The stopping means comprises at least one clip (60) configured to mechanically interfere with the guide hole (40h) and to contact the corresponding wall (40W) of the guide hole (40h), wherein the clip (60) protrudes from the body (10') of the contact probe (10) and is configured to elastically deform while in contact with the wall (40W) of the guide hole (40h), thereby causing the mechanical interference with the guide hole (40h) to retain the contact probe (10), the probe head (100) according to claim 16.

18. The probe head (100) according to any one of claims 1 to 17, wherein the elastically flexible intermediate section (10s) is embedded in a polymer material (P).

19. The elastically flexible intermediate section (10s) is configured to determine the strength and / or direction of the contact force (FC) exerted on the contact pads (20a, 30b) by the contact probe (10), and the contact probe (10) functions as a spring. The probe head (100) according to any one of claims 1 to 18, wherein the elastically flexible intermediate section (10s) is configured such that the contact force (FC) exerted on the contact pads (20a, 30b) by the contact probe (10) has substantially zero lateral component and is substantially directed along the longitudinal axis (H-H), or the contact force (FC) also has a component along an axis other than the longitudinal axis (H-H), for example, a lateral axis.

20. The contact probe (10) has a rectangular cross-section. The thickness of the reduced portion (Tel, Tel') is less than the maximum thickness (Tmax) when measured along one of the shorter sides of the rectangular cross-section. A probe head (100) according to any one of claims 1 to 19.

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