Contact probe for electronic device probe head

Abstract

A contact probe (20) is described. The contact probe has a first end (20A), a second end (20B) and a rod-like probe body (20C). The first end is adapted to abut against a contact pad of a device under test. The second end is adapted to abut against a contact pad of a PCB board of a testing apparatus. The probe body extends in a longitudinal development direction (z) between said ends (20A, 20B) and is provided with at least one opening (22). The opening extends in said longitudinal development direction (z) and defines at least one pair of arms (21a, 21b) in said probe body (20C). Suitably, each arm (21a, 21b) of said at least one pair of arms has a non-constant cross section perpendicular to said longitudinal development direction (z) with different areas at different points (A, B, C) along said probe body (20C) to ensure that stress is distributed along the probe body during a bending of the probe body (20C) during a testing operation of a device under test by the contact probe (20).

Description

Technical Field

[0001] In its more general aspect, the present invention relates to a contact probe for an electronic device probe tip, and is described below with reference to the field of application, the sole purpose of which is to simplify the disclosure. Background Technology

[0002] As is well known, a probe tip is essentially a device suitable for electrically connecting multiple contact pads of a microstructure (especially electronic devices integrated on a wafer) to corresponding channels of a test apparatus that performs functional testing (especially electrical testing, or general testing).

[0003] This test is performed on electronically integrated devices and is particularly useful for detecting and isolating defective devices early in the production process. Therefore, probes are commonly used for electrical testing of devices integrated on a wafer before they are diced and assembled into a chip-receiving package.

[0004] Probe tips typically include a number of contact elements or contact probes formed from special alloy wires with good electrical and mechanical properties, and are provided with at least one contact portion for one of the contact pads of the device under test.

[0005] A probe tip, typically referred to as a "vertical probe tip," comprises multiple contact probes, which are usually held by at least one pair of substantially plate-shaped, parallel plates or guides. The guides are provided with suitable holes and spaced apart from each other to allow free space or air gaps for movement and possible deformation of the contact probes. Specifically, the pair of guides includes an upper guide positioned closer to the test setup containing the probe tip and a lower guide positioned closer to the wafer containing the device under test. Both guides have corresponding guide holes within which the contact probes slide axially.

[0006] A good connection between the contact probe of the probe head and the contact pad of the device under test is ensured by the pressure of the probe head on the device itself. The contact probe can move within the guide holes formed in the upper and lower guide members. During the pressing contact process, it bends in the air gap between the two guide members and slides in the corresponding guide member holes.

[0007] Furthermore, the bending of the contact probe in the air gap can be facilitated by appropriate construction of the probe itself or its guide, such as... Figure 1 The diagram is schematic, wherein, for the sake of simplicity, only one of the plurality of contact probes typically included in the probe head is shown, and the probe head shown is of the so-called probe head type with a shift plate.

[0008] In particular, Figure 1A probe head 10 is schematically shown, comprising at least one upper plate or upper mold 2 and at least one lower plate or lower mold 3 having corresponding upper guide holes 2A and lower guide holes 3A. At least one contact probe 1 slides in the upper guide holes 2A and lower guide holes 3A, and has a probe body 1C extending substantially along the longitudinal unfolding direction of the HH axis shown in the figure. A plurality of contact probes 1 are typically placed within the probe head 10, the longitudinal unfolding direction being arranged orthogonally to the device under test and the guides, i.e., substantially perpendicular to the x-axis of the local reference frame in the figure.

[0009] The contact probe 1 has at least one end or contact tip 1A. The term end or tip, as used herein and hereinafter, refers to a terminal portion, which is not necessarily pointed. Specifically, the contact tip 1A abuts against the contact pad 4A of the device under test 4, performing mechanical and electrical contact between the device under test and the test apparatus (not shown), and the probe head 10 forms the end element of the test apparatus.

[0010] In some cases, the contact probe is fixedly fastened to the probe head, for example at the upper guide: such a probe head is called a "blocking probe head".

[0011] Alternatively, the probe tip can be used with loosely secured contact probes, but maintains an interface connection with the PCB board of the test setup: this type of probe tip is called an "unblocked probe tip." Typically, in this case, the probe tip also includes a so-called "space transformer," which is located between the probe tip and the test setup and enables the spatial redistribution of the contact pads relative to the device under test (DUT), specifically relaxing the distance constraints between the centers of the pads themselves, i.e., spatially transforming the distance based on the distance between the centers of adjacent pads, usually expressed as a pitch.

[0012] In this case, such as Figure 1 As shown, the contact probe 1 has another contact end 1B facing the plurality of contact pads 5A of the space transformer 5, typically referred to as a contact head. The correct electrical connection between the probe and the space transformer 5 is similar to that ensured by pressing the contact head 1B of the contact probe 1 onto the contact pads 5A of the space transformer 5 to make contact with the device under test 4. More generally, the contact pads abutted by the contact head 1B of the probe can be manufactured directly on the PCB board of the test apparatus for connection with the probe head 10, and the above considerations also apply to the PCB board.

[0013] As previously described, the upper mold 2 and lower mold 3 are appropriately spaced apart by an air gap 6. The air gap 6 allows the contact probe 1 to deform during the operation of the probe head 10 and ensures that the tip 1A and contact head 1B of the contact probe 1 contact the device under test 4 and the contact pads 4A and 5A of the space transformer 5 or the PCB board, respectively. Clearly, the dimensions of the upper guide hole 2A and lower guide hole 3A must be designed to allow the contact probe 1 to slide within them during the test operation performed through the probe head 10. More importantly, it must be ensured that the deformation of the probe occurs similarly for each of the multiple probes contained in the probe head 10 to avoid potential undesirable interference and contact between adjacent probes.

[0014] The shape of the probe deformation and the force required to produce such deformation depend on many factors, such as the physical properties of the material (which may be a composite material) used to manufacture the probe and the offset between the guide holes in the upper guide and the corresponding guide holes in the lower guide.

[0015] The proper operation of the probe head is essentially related to two parameters: the vertical movement or overtravel of the contact probe, and the horizontal movement or scrubbing of the contact tip of the contact probe. The scrubbing allows the surface of the contact tip to scrape the contact pad, thereby removing impurities that may accumulate thereon, such as in the form of a thin layer or oxide film, thus improving the contact performed by the contact head by means of the contact probe.

[0016] All of these characteristics should be evaluated and calibrated during the probe tip manufacturing process, because proper electrical connection between the probe and the device under test (DUT), especially between the probe's contact tip and the DUT's contact pad, should always be ensured.

[0017] It is equally important to ensure that the contact tip of the probe does not press too hard against the contact pad of the device under test, which could cause the probe or the pad itself to break.

[0018] This problem is particularly evident in the case of so-called short probes, i.e., probes with a rod-shaped body of limited length, especially with an overall size of less than 5000 μm. This type of probe is used, for example, in high-frequency applications, where the reduced probe length limits the self-inductance of the connection, which is very disadvantageous in high-frequency applications, a term referring to applications involving signals carried by the probe at frequencies greater than 1000 MHz.

[0019] However, in this case, the reduction in probe body length significantly increases the overall stiffness of the probe. This means that the force exerted by the corresponding contact tip on the contact pad of the device under test (DUT) increases, which could lead to pad breakage and irreparable damage to the DUT—a situation that should obviously be avoided. Even more dangerously, the increased stiffness of the contact probe due to its reduced body length increases the risk of the probe itself breaking.

[0020] To address these issues, it is known to have a probe with one or more openings extending along an associated rod-shaped body, which reduces the stiffness of the probe and thus the pressure exerted by the probe on the contact pad, while ensuring sufficient elasticity of the probe body. The openings define a plurality of arms that are substantially parallel to each other within the probe body.

[0021] In this case, refer to Figure 2A and 2B The contact probe 1 includes an opening 12 or more openings 12a, 12b formed at its body 1C and adapted to define a plurality of arms 11a, 11b, 11c. This type of probe is described, for example, in U.S. Patent No. 7,850,460, granted to Feinmetall GmbH on December 14, 2010.

[0022] Because of the opening and the arm, probes manufactured in this way are more flexible and therefore less prone to breakage, while ensuring that the signal has a sufficiently high current value for transmission in the relevant application.

[0023] However, during operation, the probe exhibits a deformed structure and shows an accumulation of compressive stress in specific areas that are still prone to breakage.

[0024] The technical problem of the present invention is to provide a contact probe whose functional and structural features allow it to be used in any situation, especially in high-frequency applications, with a probe length of less than 5000 μm, sufficient elasticity and avoidance of stress accumulation, thus reducing the risk of breakage even when in a deformed configuration during test operations, thereby overcoming the limitations and disadvantages that still affect contact probes and probe tips manufactured according to the prior art. Summary of the Invention

[0025] The present invention provides a contact probe having at least one opening extending along a corresponding rod-shaped body, the opening being suitably manufactured to define a plurality of arms having a non-constant cross-section along the longitudinal unfolding axis of the probe itself, particularly having different areas along different points of the probe body, these different points being identified based on the stress generated in the probe body during deformation of the probe body during test operations.

[0026] Based on this concept, the technical problem solved by this invention is a contact probe. The contact probe has a first end, a second end, and a probe body. The first end is adapted to abut against a contact pad of a device under test. The second end is adapted to abut against a contact pad of a PCB board of a testing device. The probe body extends longitudinally between the first end and the second end and has at least one opening. The opening extends along the longitudinal direction and defines at least one pair of arms within the probe body. The characteristic feature is that each of the at least one pair of arms has a transverse cross-section perpendicular to the longitudinal extension direction, and the transverse cross-section is not constant but has different areas at different points on the probe body.

[0027] More specifically, the present invention includes the following additional and optional features, which may be used individually or in combination if desired.

[0028] According to one aspect of the invention, when the contact probe is not pressed against the contact pad of the device under test, the probe body may have a pre-deformed shape with a curved structure in the resting state.

[0029] Appropriately, the pre-deformed shape may include at least one bending and curvature change point, and the arm may have a transverse cross section with a maximum value at the curvature change point.

[0030] According to another aspect of the invention, the contact probe may further include at least one stop portion formed by a preferred teardrop-shaped opening and capable of defining two portions of the probe that are adapted to move closer and further apart if subjected to a lateral compressive force, thus becoming an elastic stop portion.

[0031] According to another aspect of the invention, the pre-deformed shape of the contact probe may include at least a pair of bends arranged with curvatures opposite to those of the longitudinal unfolding direction.

[0032] According to this aspect of the invention, the contact probe may include a first curved neck formed at a first end of the probe body by a portion with a reduced cross-section and a second curved neck formed at a second end of the probe body. In particular, the first curved neck and the second curved neck may have a recessed portion that is symmetrical with respect to one of the adjacent curved surfaces and preferably arranged opposite to each other.

[0033] In addition, the contact probe may include at least one reinforcement located at the end of the opening.

[0034] The contact probe may also include an enlargement at the contact head, which has a cross-section larger than that of the probe body to define the undercut wall of the contact head.

[0035] Suitablely, the contact probe may have a total longitudinal extension in the resting state (i.e., when the contact probe is not abutting the contact pad of the device under test) ranging between 2 mm and 5 mm, preferably between 3.8 mm and 4.6 mm, and more preferably equal to 2.1 mm.

[0036] This technical problem is also solved by a probe head comprising at least one upper guide with an upper guide hole and a lower guide with a lower guide hole, the upper and lower guide holes being used to accommodate a plurality of contact probes manufactured as described above.

[0037] The features and advantages of the contact probe according to the invention will become apparent from the following description of its embodiments with reference to the accompanying drawings, which are given by way of indicative rather than limiting examples. Attached Figure Description

[0038] In these diagrams:

[0039] - Figure 1 A schematic front view of a probe head manufactured according to existing technology is shown;

[0040] - Figure 2A and 2B Front views of contact probes manufactured according to existing technology are shown respectively;

[0041] - Figure 3 and 3 A-3C schematically show a front view and a cross-sectional view of an embodiment of the contact probe according to the present invention;

[0042] - Figure 4 and 4A -4D Figure 5 and 5A , Figure 6 and 6A -6C Figure 7 and 7A -7E Figure 8 and 8A The front view and cross-sectional view of each alternative embodiment of the contact probe according to the invention are shown schematically;

[0043] - Figure 9 The illustration shows, including, according to Figure 5 The probe tip of the contact probe in the alternative embodiment; and

[0044] - Figure 10 The illustration shows, including, according to Figure 8 The probe head of the contact probe in an alternative embodiment. Detailed Implementation

[0045] Refer to these diagrams, especially Figure 3 and3 A-3C, a contact probe manufactured according to the present invention is described herein, generally indicated by reference numeral 20.

[0046] It should be noted that the accompanying drawings are schematic diagrams and not drawn to scale, but are drawn to highlight the important features of the invention. Furthermore, different components are shown schematically in the figures because their shapes can vary depending on the desired application. Additionally, a specific feature shown in one figure relating to one embodiment may also be used in one or more embodiments shown in other figures.

[0047] Finally, in the various embodiments shown and described in the figures, structurally and functionally identical elements are referred to by the same alphanumeric references.

[0048] The contact probe 20 includes at least one contact end adapted to abut against the contact pad of the device under test at a contact tip 20A. In the embodiment shown in the figure, the contact probe 20 is non-blocking and includes at least one additional contact end adapted to abut against the contact pad of the PCB board of the test apparatus (not shown) at a contact head 20B. The contact probe 20 also includes a rod-shaped probe body 20C that extends between the contact head 20B and the contact tip 20A according to the longitudinal direction of the probe (particularly the z-direction of the local reference frame in the figure).

[0049] Suitable, the contact probe 20 also includes an opening 22 extending along the probe body 20C, such that the opening is formed by at least one first arm 21a and at least one second arm 21b that are substantially parallel to each other and separated by the opening 22.

[0050] Advantageously, according to the invention, the first arm 21a and the second arm 21b have different transverse sections at different points along the probe body 20C in the z-direction, i.e., according to a plane perpendicular to the longitudinal unfolding direction z.

[0051] More specifically, as shown in the figure, a first transverse plane is determined along the probe body 20C at a first point A, a second transverse plane is determined along the probe body 20C at a second point B, and a third transverse plane is determined along the probe body 20C at a third point C. The term "transverse plane" refers to a plane orthogonal to the longitudinal unfolding direction z. The points are different from each other and are determined based on the stress generated in the probe body 20C during the test, as will be explained below.

[0052] In the first embodiment, the first point A, the second point B and the third point C are positioned equidistant from each other and equidistant from the two ends of the opening 22 and thus from the two ends of the arms 21a and 21b.

[0053] Suitablely, the corresponding transverse sections of the first arm 21a (denoted by Sez Aa, Sez Ba, and Sez Ca) and preferably the transverse sections of the second arm 21b (denoted by Sez Ab, Sez Bb, and Sez Cb) have different dimensions from each other along the probe body 20C, such as Figure 3 A-3C is schematically shown. In other words, the contact probe 20 includes an arm that realizes its probe body 20C, the transverse cross section of which has a non-constant area along the longitudinal unfolding direction z of the probe body 20C and therefore along the longitudinal unfolding direction z of the contact probe 20.

[0054] It was immediately verified that the area variation of the transverse cross section of the arm along the longitudinal unfolding direction z allows for the distribution of stress on the contact probe 20 during the pressing contact with the pad of the device under test, thereby avoiding the accumulation that could lead to damage or even breakage of the contact probe.

[0055] It is evident that a contact probe having a probe body 20C traversed by more than one opening 22 and thus having more than two longitudinal arms with suitable transverse cross sections can be realized, the area of ​​which is variable along the longitudinal unfolding direction z of the probe body 20C and thus along the longitudinal unfolding direction z of the contact probe 20.

[0056] More specifically, in Figure 3 In the illustrated embodiment, the contact probe 20 and its arms 21a and 21b have a rectangular cross-section with a base of L, a height of H, and an area still denoted by Sez. For simplicity, in the embodiment shown in the figure, the first arm 21a and the second arm 21b have the same construction and equal-area transverse cross-sections along the longitudinal unfolding direction z at multiple points. In other words, for example, at the first transverse plane located at the first point A, the transverse cross-section Sez Aa of the first arm 21a has a base of Laa and a height of Haa, which are equal to the base of the cross-section Sez Ab of the second arm 21b located at the first transverse plane still at the first point A, and the height of Hab, respectively; this also applies to the corresponding dimensions of the base and height, and to the corresponding base and height dimensions of the first arm 21a and the second arm 21b, as well as the corresponding cross-sections Sez Ba, Sez Bb and Sez Ca, Sez Cb taken along the probe body 20C at the second transverse plane located at the second point B and the third transverse plane located at the third point C.

[0057] It is also possible to consider the case that the shape and cross-sectional trend of the first arm 21a are different from those of the second arm 21b along the probe body 20C, although the cross-section of each arm is not constant.

[0058] Suitablely, according to the invention, the probe body 20C has a pre-deformed shape, in Figure 3In the example shown, it is a single-bending shape, that is, the curvature change point is an arc at the second point B. The second point B can also be considered as the maximum curvature point of the probe body 20C and its arms 21a, 21b, which is basically the vertex of the pre-deformed curved arch in the contact probe 20. The single-bending shape of the contact probe 20, especially its probe body 20C, exists even under non-operating conditions of the probe (i.e., before it is bent and deformed during the test).

[0059] In this way, it is possible to avoid using a double guide that can achieve probe offset, as occurs in known solutions. The single-bending pre-deformation ensures that the contact probe 20 bends in the same desired direction. In this way, the problems related to the offset caused by the guide in known solutions are overcome. This offset, especially in the case of a large number of contact probes, applies a lateral force to the device under test, and this lateral force can cause unwanted displacement.

[0060] In particular, the opening 22 forms the first arm 21a and the second arm 21b in the probe body 20C. The first arm 21a and the second arm 21b have the maximum cross-section (i.e., the maximum area) at the stress accumulation points along the probe body 20C. More specifically, in Figure 3 the example, at point B, at the maximum curvature point of the contact probe 20 (especially the probe body 20C and its arms 21a, 21b) (i.e., at the curvature change of the pre-deformed probe body 20C), the stress accumulation points along the probe body 20C are identified.

[0061] In other words, considering the cross-sections along the probe body 20C at points A, B, and C as shown in Figure 3 , Figure 3 A-3C, the following relationships will apply:

[0062] - For the first arm 21a: Sez Aa < Sez Ba and Sez Ba > Sez Ca; and

[0063] - For the second arm 21b: Sez Ab < Sez Bb and Sez Bb > Sez Cb.

[0064] Generally speaking, for any number of arms, for each arm, the following relationship will always apply:

[0065] Sez A < Sez B; Sez B > Sez C (1)

[0066] That is, the cross section at stress accumulation point B (corresponding to the point of maximum curvature of the pre-deformed probe body 20C) is the largest among the transverse cross sections of the arm taken from different points along the probe body 20C of the contact probe 20. In the example in the figure, the change in cross section (i.e., area) is obtained by changing the value of the bottom edge L while the cross section maintains the same height H, but it is clear that the above-mentioned cross section trend (i.e., area) can also be obtained by providing a change in height or a simultaneous change in area and bottom edge. Typically, the entire cross section of the probe body 20C (i.e., the combination of the cross sections of arms 21a, 21b and opening 22) is the largest among the cross sections of the arm taken from different points along the probe body 20C of the contact probe 20. Figure 3 In A, denoted as Sez 20C, the value of 20C is preferably constant along the entire probe body.

[0067] More specifically, in Figure 3 and Figure 3 In the example shown in A-3C, for the rectangular cross-section contact probe 20, the value of the bottom edge L of the cross-section Sez of arms 21a and 21b is between 0.010 mm and 0.020 mm, while the value of the height H of the cross-section Sez is constant and selected in the range between 0.040 mm and 0.080 mm, preferably equal to 0.041 mm; similarly, the bottom edge value of the cross-section Sez 20C of the probe body 20C is selected in the range between 0.060 mm and 0.120 mm, preferably equal to 0.070 mm, and similarly, the height value is selected in the range between 0.040 mm and 0.080 mm, preferably equal to 0.041 mm.

[0068] In a preferred embodiment, the second point B is located at the center of the probe body 20C, defining a first ascending channel 20C1 along the direction of the contact head 20B and a second descending channel 20C2 along the direction of the contact tip 20A. Suitably, the first point A and the third point C are located at the first ascending channel 20C1 and the second descending channel 20C2, respectively; advantageously, according to the invention, the first point A and the third point C are located at the beginning and end of the channels (i.e., arms 21a, 21b) of the probe body 20C, respectively, wherein the cross-section of the arms is variable, preferably located in the middle of the ascending channel 20C1 and the descending channel 20C2, respectively.

[0069] exist Figure 3 In the preferred embodiment shown, for the contact probe 20 pre-deformed at the bend, the cross-section of the arms 21a, 21b is constant along the first rising channel 20C1 of the probe body 20C from the beginning of the first rising channel 20C1 at the contact head 20B until the first point A. It continuously increases from the first point A to the second point B with the largest cross-section, continuously decreases from the second point B to the third point C, and then has a constant cross-section again until the end of the second falling channel 20C2 at the contact tip 20A.

[0070] In one embodiment, for a rectangular cross-section contact probe 20, the variable cross-section is obtained due to different values ​​of their base L, and specifically, the probe body 20C of the contact probe 20 has a cross-section from the contact head 20B to a first point A with a base edge of 0.014 mm, increasing until its base edge reaches a value of 0.016 mm at a second point B, then decreasing again until its base edge again has a value of 0.014 mm at a third point C, and so on until the contact tip 20A.

[0071] It can be verified that the specific construction of the contact probe 20 according to the invention (where arms 21a, 21b have a variable cross section along the probe body 20C, particularly a cross section that increases from A to B and decreases from B to C) allows for a uniform distribution along the probe body 20C of the stress borne by the contact probe 20 when its contact tip 20A contacts the contact pad of the device under test during a test operation performed by the contact probe 20.

[0072] The contact probe 20 further preferably includes a thinned construction at a contact tip 20A, the contact tip 23A comprising a base 23A and an end 24A, the base 23A having a cross-section equal to or equivalent to that of the probe body 20C and abutting thereto, the term "equivalent" meaning the difference between the two cross-sections is ±20%, the end 24A abutting the base 23A and realizing the actual contact tip of the contact probe 20, the contact tip always denoted by 24A and adapted to abut against the contact pad of the device under test when the contact probe 20 is used inside the probe head for integrated device testing. Suitably, the contact tip 24A is thinned relative to the base 23A of the contact tip 20A, i.e., the value of the cross-section of the contact tip 24A is equal to 20-60% of the cross-section of the base 23A and therefore equal to 20-60% of the cross-section of the probe body 20C, preferably equal to 50% of the cross-section of the probe body 20C.

[0073] In this way, the contact probe 20 is suitable for testing devices under test with reduced contact pad area, as it appears in the latest integration technology. The length of the contact tip 24A can also be determined along the longitudinal unfolding direction z, ensuring proper operation of the probe even after several test operations, which are known to typically require cleaning by touching a sandpaper and involve gradually shortening the contact tip 24A.

[0074] The contact probe 20 also includes a thinned structure at a contact head 20B, which includes a base 23B and an end 24B. The cross-section of the base 23B is equal to or equivalent to that of the probe body 20C and is adjacent to it. The end 24B, which serves as the actual contact head of the contact probe 20, is still denoted by 24B and is thinned relative to the base 23B, i.e., its cross-section is equal to 20-60%, preferably 50%, of the cross-section of the base 23B. Suitably, the contact head 20B also includes an enlargement 25 located between the base 23B and the contact head 24B and having a cross-section larger than that of the base 23B and therefore larger than that of the probe body 20C, to define an undercut wall of the contact head 20B adapted to abut against a guide including the probe head of the contact probe 20, as will be described below. More specifically, the cross-section of the enlarged portion 25 is 20-40% larger than the cross-section of the base portion 23B and therefore 20-40% larger than the cross-section of the probe body 20C, preferably 30% larger than the cross-section of the probe body 20C. In a preferred embodiment, the contact probe 20 has a rectangular cross-section, and the cross-sectional variation of its different portions is achieved by varying the value of its base L.

[0075] according to Figure 4 In the alternative embodiment shown, the contact probe 20 further includes at least one curved neck 26 located at the end of the probe body 20C, preferably as follows: Figure 4 In the example, this is located at the end of the probe body 20C at the contact tip 20A. More specifically, the curved neck 26 is manufactured from a portion with a reduced cross-section, which preferably has a cross-section that is 30-60% smaller than the cross-section of the probe body 20C, more preferably equal to 50% of the cross-section of the probe body 20C, such as... Figure 4D Schematic illustration shows a cross-section of the contact probe 20 taken at the fourth point D, where the transverse plane passes through the center of the curved neck 26, i.e., at its minimum cross-section point. Even in this case, as Figures 4A-4C As shown schematically, the cross sections of arms 21a and 21b also obey the above relationship (1).

[0076] exist Figure 4 In the illustrated embodiment, the curved neck 26 is preferably arranged at the center of the contact probe 20 along the longitudinal unfolding direction z, concentric with the base 23A of the contact tip 20A, and is obtained by symmetrically removing material from at least two opposite sides of the contact probe 20 (particularly its contact tip 20A).

[0077] It can be immediately verified that the presence of the bent neck 26 (particularly at one end of the arms 21a, 21b and thus at one end of the opening 22, which is a well-known area of ​​high fragility) can reduce the stress on the arms 21a, 21b, especially during test operations (i.e. when the contact probe 20 bends and deforms due to its contact pad against the device under test).

[0078] Furthermore, due to its centrally located position, the curved neck 26 does not negatively affect the bending mechanism of the contact probe 20 or the wiping of its contact tip 24A.

[0079] according to Figure 5 In another alternative embodiment schematically shown, the contact probe 20 includes a stop 27, which is advantageously resilient. More specifically, as Figure 5A As schematically shown in the enlarged view, the stop portion 27 is manufactured in the contact head 20B of the contact probe 20, preferably in the bottom 23B, by means of a teardrop-shaped opening 27A (i.e., having a size that increases along the base 23B of the contact head 20B toward the probe body 20C). Thus, the stop portion 27 has a pinhole shape, and the presence of the teardrop-shaped opening 27A defines two opposing portions in the base 23B, which can move closer or further apart if subjected to lateral compression.

[0080] More specifically, the teardrop-shaped opening 27A is sized to enlarge the base 23B of the contact head 20B to a larger size than the guide hole formed on the plate that houses the probe head of the contact probe 20, thereby preventing or at least stopping the contact probe 20 from moving upward (i.e., according to the z-direction, considering the local reference frame in the figure) once inserted into the probe head, which will be better explained below.

[0081] Appropriately, the stop 27 has a symmetrical shape, thereby acting independently of the curvature direction of the pre-deformed shape of the contact probe and, in the absence of a pair of guides that realize the offset of the contact probe, to react to the movement of the contact probe 20 relative to the guide hole therein, as occurs in known solutions.

[0082] It should be emphasized that the elasticity of the stop 27 allows the contact probe 20 to pass through the corresponding guide hole during assembly operations and allows the operator to remove it during possible maintenance operations, such as when the contact probe 20 itself needs to be disassembled and replaced. Although it ensures proper retention even when the probe head containing it is not pressed against the device under test, the stop 27 can effectively counteract the movement of the contact probe 20 due to gravity or other lateral forces (e.g., during cleaning operations typically performed by jets).

[0083] although Figure 5The illustrated embodiment shows that the contact probe 20 has both a curved neck 26 and a stop 27, but it can also be manufactured to include only the curved neck 26 (e.g., Figure 4 (as shown) or may only include the stop portion 27.

[0084] Figure 3 , Figure 4 and Figure 5 The contact probe 20 at the bend shown is suitable for high-frequency applications and can be manufactured with overall longitudinal extension (in Figure 3 The value is represented by Ls, and its range is between 3 mm and 5 mm, preferably between 3.8 mm and 4.6 mm. The value refers to the value when the contact probe 20 is in a stationary or non-operating state, that is, when it is not in contact with the contact pad of the device under test.

[0085] The overall length range of the contact probe 20 ensures that the contact probe is used in high-frequency applications and maintains elastic behavior during testing, i.e., it bends and compresses without plastic deformation, i.e., incomplete deformation, during pressing against the contact pad of the device under test, thus allowing for reuse; however, probes with lengths within the stated length range may be insufficient for certain types of applications. In particular, the most modern testing techniques may require probes smaller than 3 mm, preferably even smaller than 2.5 mm.

[0086] To meet this type of requirement, you can use... Figure 6 An alternative embodiment of the contact probe 20 is schematically shown in the diagram.

[0087] In the same case, the contact probe 20 includes at least one contact tip 20A and at least one contact head 20B, and a probe body 20C disposed therebetween. As previously described, the probe body 20C is traversed by an opening 22, which defines at least a pair of arms 21a, 21b within the probe body.

[0088] Appropriately, in this case, the probe body 20C has a pre-deformed shape exhibiting a double-bending tendency, with the two bends arranged with opposite curvatures relative to the longitudinal unfolding direction z, the first bend having a curvature change at a first point A' and connecting to the second bend at a second point B', and the second bend having a curvature change at a third point C'.

[0089] It can be verified immediately. Figure 6 The double-bend pre-deformation shape of the contact probe 20 (based on two different curvatures of the bends, the deformation is introduced into the probe body 20C in two different modes) allows stress to be distributed on the two bends, thereby reducing its concentration.

[0090] As previously stated, advantageously according to the invention, arms 21a and 21b have different transverse cross sections at different points on the probe body 20C along the direction z, i.e., according to a plane perpendicular to the longitudinal unfolding direction z of the contact probe 20. In this case, again by way of example, the contact probe 20 and its arms 21a and 21b have a rectangular cross section with a base of L, a height of H, and an area still denoted by Sez, as shown below. Figures 6A-6C As shown, the cross sections Sez A'a, Sez B'a and Sez C'a of arms 21a and 21b, and the cross sections Sez A'b, Sez B'b and Sez C'b of the second arm 21b are specifically indicated at points A', B' and C', respectively.

[0091] Due to the presence of the double-bending pre-deformed shape and the variable cross-section arm, an excellent stress distribution is obtained along the probe body 20C, which allows for a further reduction in the total length Ls of the contact probe 20.

[0092] According to the first embodiment, the cross-sections of arms 21a and 21b have an increasing value from the beginning of the probe body 20C at the contact head 20B up to the first curvature change point A' of the first bend or upward bend (considering the local reference frame in the figure), decreasing up to the second double-bend connection point B', still increasing up to the third curvature change point C' of the second bend or downward bend, and still decreasing up to the end of the probe body 20C at the contact tip 20A. Preferably, the cross-sections of arms 21a and 21b at the beginning and end of the probe body 20C are equal to the cross-section at the second point B', and the cross-sections at the first point A' and the third point C' are equal to each other and both larger than the cross-section at the second point B'.

[0093] Therefore, due to the presence of the variable cross-section arms 21a and 21b, the stress experienced by the contact probe 20 during the test operation is uniformly distributed along its probe body 20C and thus along its arms 21a and 21b, thereby reducing the risk of deformation or breakage of the contact probe 20 itself. Furthermore, the symmetrical trend of the cross-section change allows the contact probe 20 to maintain its kinematic behavior as it bends and compresses by abutting against the contact pad of the device under test, without affecting its cleaning action.

[0094] In a preferred embodiment, such as Figures 6A-6C As schematically shown, the contact probe 20 has arms 21a and 21b, the cross-sections of which increase progressively along the entire probe body 20C from the contact head 20B, through the first point A', the second point B', and the third point C', until the contact tip 20A. Therefore, it is verified that each arm 21a and 21b is subject to the following relationship:

[0095] sez A' <sez B’<sez C’ (2)

[0096] In this way, it was verified that a contact probe 20 with a total length Ls of less than 3 mm, preferably less than 2.5 mm, and more preferably equal to 2.1 mm can be manufactured without undergoing plastic deformation during the test operation. The presence of arms 21a and 21b with an ever-increasing cross-section ensures proper stress distribution along the probe body 20C when the contact probe 20 is pressed against the contact pad of the device under test, while avoiding damage or even breakage of the arms 21a and 21b themselves.

[0097] Based on the application requirements of the probe itself, it is obvious that... Figure 6 The double-bend contact probe 20 even has a total length Ls greater than 3 mm, particularly having a length similar to that of the single-bend embodiment.

[0098] exist Figure 6 In the example, the contact probe 20 has a rectangular cross-section, and the cross-sectional variation (i.e., area variation) is obtained by changing the value of the bottom edge L while the cross-section maintains the same height H. In a preferred embodiment, the value of the bottom edge L is equal to 0.014 mm at the first point A', 0.016 mm at the second point B', and 0.018 mm at the third point C'.

[0099] Alternatively, it could be considered to have the contact probe 20 with arms 21a, 21b have a progressively increasing cross-section only in one channel of the probe body 20C, rather than along its entire extension, for example in... Figure 6 In the channel defined between the first point A' and the third point C' shown. In this case, arms 21a, 21b are manufactured with a constant cross-section from the beginning of the probe body 20C at the contact head 20B to the first point A' (this constant cross-section is equal to the cross-section of the first point A', in fact, the increasing cross-section from the first point A' to the second point B' and from the second point B' to the third point C') and from there to the end of the probe body 20C at the contact tip 20A (this constant cross-section is equal to the cross-section of the third point C'). Also in this case, the above relationship (2) is observed for each of arms 21a, 21b.

[0100] As mentioned above, a contact probe 20 may be considered having a probe body 20C traversed by multiple openings 22 and thus having more than two arms and arms with different constructions (in particular, different cross sections from one arm to the other on the same transverse plane), each arm 21a, 21b conforming to the above relationship (2).

[0101] Figure 7Another alternative embodiment is schematically illustrated. The contact probe 20 has a double-bent pre-deformed probe body 20C and includes at least one curved neck, preferably a first curved neck 26A formed at the probe body 20C at the contact tip 20A and thus at the end of the arms 21a, 21b, and a second curved neck 26B formed at the probe body 20C at the contact head 20B and thus at the beginning of the arms 21a, 21b.

[0102] More specifically, the curved necks 26A and 26B are manufactured from portions with reduced cross-sections, for example, having a cross-section that is 30-60% smaller than the cross-section of the probe body 20C, more preferably equal to 30% of the cross-section of the probe body 20C. Figure 7D and Figure 7E The diagram schematically illustrates the cross-section Sez D' of the contact probe 20 taken at the fourth point D' (where the transverse plane passes through the center of the first curved neck 26A) and the cross-section Sez E' of the contact probe 20 taken at the fifth point E' (where the transverse plane passes through the center of the second curved neck 26B). Similarly, in this case, as... Figures 7A-7C As shown schematically, the cross sections of arms 21a and 21b obey the above relationship (2).

[0103] More specifically, the curved necks 26A and 26B are manufactured to have recesses that are symmetrically and particularly oppositely arranged with respect to the concave surfaces of the adjacent curves.

[0104] Thus, the presence of the curved necks 26A and 26B not only reduces the stress on the arms 21a and 21b, especially during test operations (i.e., when the contact probe 20 bends and deforms due to its contact with the pad of the device under test), but also allows the bending of the contact probe 20 itself to be consistent with the double-bending shape of its probe body 20C.

[0105] according to Figure 8 In another alternative embodiment, schematically shown, the contact probe 20 includes a reinforcement 28 located at the end of the opening 22 and thus at the ends of the arms 21a, 21b, preferably at the contact head 20B.

[0106] More specifically, such as Figure 8AAs schematically shown in the enlarged view, at the reinforcement 28, at least one of the arms 21a and 21b, preferably at a position opposite the concave surface of the first curved neck 26A, the first arm 21a has at least one portion 28A located between the beginning of the probe body 20C (i.e., the first arm 21a itself) and the first point A of the concave surface change of the first curve, this portion 28A having a larger cross-section than the remainder of the first channel of the first arm 21a. Preferably, considering the rectangular cross-section contact probe 20, the larger cross-section portion 28A includes a bottom edge L28, the value of which is 30-60% larger than the bottom edge of the cross-section of the first channel of the first arm 21a, preferably equal to 50%.

[0107] In the same situation, although Figure 8 The illustrated embodiment shows a contact probe 20 having both curved necks 26A and 26B and a reinforcing portion 28, but it can also be manufactured including only one curved neck 26A or 26B, or two curved necks 26A and 26B (e.g. Figure 7 (As shown) or only one curved neck 26A and / or 26B and reinforcement 28, or only reinforcement 28.

[0108] The present invention also relates to a vertical probe type probe head, including at least a pair of guides, the pair of guides having receiving holes for a plurality of contact probes manufactured as shown above.

[0109] More specifically, see reference Figure 9 This describes including according to Figure 5 The illustrated embodiment shows probe heads 30 for multiple probes (i.e., single-bend pre-deformed contact probes). For the sake of simplicity in the illustration, in Figure 9 The image shows only one contact probe 20.

[0110] The probe head 30 includes at least one first plate-shaped guide or upper guide 31 (generally referred to as an upper mold, having a suitable upper guide hole 31A for receiving the contact probe 20) and a second plate-shaped guide or lower guide 32 (generally referred to as a lower mold, also having a suitable lower guide hole 32A for receiving the contact probe 20). As seen in the prior art, the upper mold 31 and the lower mold 32 are spaced apart from each other to define an air gap between them, in which the contact probe 20 can be freely bent during its contact tip 20A pressing against the pad 35A of the device under test 35.

[0111] Suitablely, the probe head 30 also includes an upper frame 33 associated with the upper guide 31 and provided with a corresponding opening 33A suitable for receiving the contact probe 20, and a lower frame 34 associated with the lower guide 32 and similarly provided with an opening 34A for receiving the contact probe 20.

[0112] More specifically, the upper frame 33 is fixedly connected to the upper guide 31 by connecting elements such as screws, pins, or elastic membranes, and the lower frame 34 is similarly fixedly connected to the lower guide 32 by elements such as screws, pins, or elastic membranes. The upper frame 33 and the lower frame 34 serve as structural reinforcement elements for the upper guide 31 and the lower guide 32, respectively, and act as alignment tools for contacting the probe 20 during the assembly step of the probe head 30.

[0113] like Figure 9 As shown, the contact probe 20 is accommodated or integrated in the probe head 30 such that the base 23B of its contact head 20B is inserted into the guide hole 31A of the upper guide member 31, wherein the enlarged portion 25 abuts against the upper surface FA of the upper guide member 31, i.e., the surface of the upper guide member 31 facing the upper frame 33, in this way serving as a retaining element for the contact probe 20 to prevent the contact probe from being in contact with... Figure 9 It moves downwards in the opposite direction of the z-axis.

[0114] Specifically, the guide hole 31A of the upper guide member 31 is designed to accommodate the base 23B of the contact head 20B of the contact probe 20 with a gap, but prevents the enlarged part 25 from passing through, while the opening 33A of the upper frame 33 has a size suitable for accommodating the enlarged part 25 and the contact head 24B of the contact probe 20.

[0115] Furthermore, advantageously according to the invention, the contact probe 20 is housed in the probe head 30 such that its stop portion 27 is located below the upper guide hole 31A of the upper guide member 31, to prevent or at least stop the contact probe 20 from... Figure 9 It moves upwards along the z-axis as shown.

[0116] The contact probe 20 also has a base 23A of a contact tip 20A received in a lower guide hole 32A of the lower guide 32. In this case, the lower guide hole 32A is sized to loosely receive the base 23A of the contact tip 20A of the contact probe 20, while the contact tip 24A protrudes below the lower guide 32 toward the device under test 35 to abut against its contact pad 35A. Suitably, the contact probe 20 also includes a curved neck 26 located at the end of the probe body 20C at the base 23A of the contact tip 20A and received in an opening 34A formed in the lower frame 34.

[0117] It can also be used to accommodate multiple bases Figure 8 The contact probe 20 manufactured in the embodiment (i.e., the double-bend pre-deformed contact probe, such as...) Figure 10 (Schematic illustration) to manufacture probe head 30, wherein, for simplicity, only one contact probe 20 is shown.

[0118] In the same case, the probe head 30 includes an upper guide 31 having an upper guide hole 31A and associated with an upper frame 33 having a corresponding opening 33A, the upper guide 31 being spaced apart from a lower guide 32 having a lower guide hole 32A and associated with a lower frame 34 having a corresponding opening 34A.

[0119] The contact probe 20 is housed in the probe head 30, such that the base 23B of the contact probe 20 is received with a gap in the upper guide hole 31A of the upper guide member 31, and its enlarged portion 25, together with the contact head 24B, is received in a corresponding opening 33A of the upper frame 33 to abut against the upper surface FA of the upper guide member 31 through its undercut wall. Similarly, the base 23A of the contact tip 20A is received with a gap in the corresponding lower guide hole 32A of the lower guide member 32, and the contact tip 24A protrudes from the lower guide member 32 in the direction of the device under test 35 to abut against its contact pad 35A.

[0120] Suitablely, according to the invention, the contact probe 20 is housed in the probe head 30 such that its second curved neck 26B is located below the upper guide 31.

[0121] In addition, the lower guide 32 is appropriately sized to facilitate the rapid movement of the contact probe 20 during the test operation when the probe abuts against the device under test 35.

[0122] In this case, according to the invention, the first curved neck 26A of the contact probe 20 is located within the lower guide hole 32A of the lower guide member 32.

[0123] More specifically, the thickness Hlw of the lower guide member 32 along the longitudinal unfolding direction z is greater than the thickness Hup of the upper guide member 31, preferably equal to 1.8-2 times the thickness Hup of the upper guide member 31. In a preferred embodiment, the thickness Hup of the upper guide member 31 varies between 0.100 mm and 0.150 mm, preferably equal to 0.125 mm, while the thickness Hlw of the lower guide member 32 varies between 0.150 mm and 0.300 mm, preferably equal to 0.254 mm.

[0124] Appropriately, according to Figure 10 In the embodiment shown, the thickness Hfup of the upper frame 33 is equivalent to, preferably equal to, the thickness Hlw of the lower guide 32, while the thickness Hflw of the lower frame 34 is equivalent to, preferably equal to, the thickness Hup of the upper guide 31. The term "equivalent" means that the difference between the two thicknesses is ±20%.

[0125] In this way, the components of the upper guide 31 and the upper frame 33 have a thickness that is comparable to, preferably equal to, the thickness of the components of the lower guide 32 and the lower frame 34, to ensure the symmetry of the dynamic and elastic behavior of the contact probe 20 and the probe head 30 as a whole.

[0126] In summary, a contact probe having at least one opening extending along its probe body and adapted to define at least one pair of arms with non-constant lateral cross-sections along the probe body exhibits better stress distribution along the probe body during the press-fit contact of the probe with the corresponding pad of the device under test, thereby significantly reducing the likelihood of probe, particularly the arms of its probe body, breaking, while ensuring proper bending of the body and proper retention of the probe within the corresponding probe head. In this way, probes with exceptionally short total lengths can be manufactured, making them suitable for applications of the latest technologies, such as very high-frequency applications, without the risk of modifying these probes in a plastic or permanent manner.

[0127] The contact probe according to the invention allows overcoming the disadvantages of known solutions associated with probe offset using dual guides, especially in the presence of a large number of contact probes, where such offset applies a lateral force that can cause undesirable movement on the device under test.

[0128] Furthermore, the presence of a double-bend pre-deformed shape that introduces two different curvatures into the probe body allows stress to be distributed across the two bends, thereby reducing its concentration. Combined with the use of arms with variable cross-sections, this allows for optimal stress distribution along the probe body, which allows the total length of the probe itself to be further reduced to a value that is unattainable by known solutions.

[0129] Appropriately, the presence of a curved neck manufactured at the end of the probe body facilitates the bending of the probe itself in a predetermined direction and further reduces the likelihood of undesirable plastic deformation of its arm during test operations.

[0130] Similarly, the presence of reinforcements in areas prone to breakage increases the robustness of probes manufactured in this manner.

[0131] Finally, in addition to the enlarged head, the probe can also be equipped with a suitable elastic stop to ensure proper fixation in the probe head.

[0132] As already noted, the elasticity of the stop allows the contact probe to pass through the corresponding guide hole during assembly operations and to be withdrawn by the operator during possible maintenance operations, but ensures that it is properly held inside the probe head, thereby effectively counteracting movement caused by gravity.

[0133] Obviously, those skilled in the art can make various modifications and variations to the above-described contact probe and probe head to meet possible and specific requirements, all of which are included within the scope of protection of the present invention as defined in the claims.

[0134] In particular, any number of longitudinal openings can be considered to form any number of arms in the probe body; furthermore, probes with different numbers of bends can be manufactured, even if not shown in the figure.

[0135] Finally, in addition to other geometric configurations of the tip and head contact portion, additional elements may be provided for the contact probe of the present invention, such as a stop protruding from the probe body.

Claims

1. A contact probe (20) having a contact tip (20A), a contact head (20B), and a probe body (20C), the contact tip being adapted to abut against a contact pad of a device under test, the contact head being adapted to abut against a contact pad of a PCB board of a test apparatus during a test operation, the probe body extending in a longitudinal unfolding direction (z) between the contact tip (20A) and the contact head (20B) and having at least one opening (22), the opening extending in the longitudinal unfolding direction (z) and defining at least one pair of arms (21a, 21b) in the probe body (20C), characterized in that, The arms (21a, 21b) have a variable transverse cross section only corresponding to the portion of the probe body (20C) between the first intermediate point (A) and the second intermediate point (C), including the curvature change point (B). The transverse cross section increases continuously from the first intermediate point (A) to the curvature change point (B) and decreases continuously from the curvature change point (B) to the second intermediate point (C), thereby having different areas at different points (A, B, C) along the probe body (20C).

2. The contact probe (20) according to claim 1, characterized in that, When the contact probe (20) is not pressed against the contact pad of the device under test, the probe body (20C) has a pre-deformed shape with a curved structure in the resting state.

3. The contact probe (20) according to claim 2, characterized in that, The pre-deformed shape includes at least one bending and curvature change point (B), and the arms (21a, 21b) have a transverse cross section with a maximum value at the curvature change point (B).

4. The contact probe (20) according to claim 3, characterized in that, The arm (21a, 21b) has a transverse cross section that increases from the first end of the arm (21a, 21b) to the curvature change point (B) and a transverse cross section that decreases from the curvature change point (B) to the second end of the arm (21a, 21b).

5. The contact probe (20) according to claim 3, characterized in that, The transverse cross section is constant from the first end of the arm (21a, 21b) to the first midpoint (A), and is constant from the second midpoint (C) to the second end of the arm (21a, 21b).

6. The contact probe (20) according to claim 1, characterized in that, It also includes at least one curved neck formed at the end of the probe body (20C) by a portion having a reduced cross section, the value of which is selected between 30% and 60% of the cross section (Sez 20C) of the probe body (20C).

7. The contact probe (20) according to claim 1, characterized in that, It also includes at least one stop (27) formed by an opening made in the contact head (20B), the opening being teardrop-shaped and defining two opposing portions in the contact head (20B), the two opposing portions being able to approach and move away if subjected to a lateral compressive force, the stop (27) being an elastic stop.

8. The contact probe (20) according to claim 2, characterized in that, The pre-deformed shape includes at least one pair of bends arranged with opposite curvatures relative to the longitudinal unfolding direction (z), the first bend undergoing a curvature change at a first point (A') and connecting with the second bend at a second point (B'), and the second bend undergoing a curvature change at a third point (C').

9. The contact probe (20) according to claim 8, characterized in that, The transverse cross section of the arm (21a, 21b) increases continuously from the first end of the arm (21a, 21b) until the first point (A') where the curvature changes, and decreases continuously from the first point (A') until the second point (B'). The transverse cross section increases again until the third point (C') and decreases again until the second end of the arm (21a, 21b).

10. The contact probe (20) according to claim 8, characterized in that, The arms (21a, 21b) have a transverse cross section that increases along the probe body (20C) and includes the first bend and the second bend, the increasing transverse cross section starting from the first end of the arms (21a, 21b) along the first point (A'), the second point (B') and the third point (C') to the second end of the arms (21a, 21b).

11. The contact probe (20) according to claim 8, characterized in that, The arm (21a, 21b) has a variable transverse cross section only along the portion of the probe body (20C) between the first point (A') and the third point (C') and including the second point (B'). The transverse cross section is constant from the first end of the arm (21a, 21b) to the first point (A'), increases from the first point (A') to the second point (B') and from the second point (B') to the third point (C'), and is constant from the third point (C') to the second end of the arm (21a, 21b).

12. The contact probe (20) according to claim 8, characterized in that, This includes a first curved neck (26A) formed at a first end of the contact tip (20A) of the probe body (20C) by means of a portion having a reduced cross section, and a second curved neck (26B) formed at a second end of the contact head (20B) of the probe body (20C), wherein the value of the reduced cross section is selected between 30% and 60% of the cross section of the probe body (20C).

13. The contact probe (20) according to claim 12, characterized in that, The first curved neck (26A) and the second curved neck (26B) each have a recess, and the respective recess is symmetrically arranged with respect to the concave surface of the curve adjacent to the recess.

14. The contact probe (20) according to claim 12, characterized in that, It includes at least one reinforcement (28) located at the end of the opening (22) and includes at least one of the arms (21a, 21b), at least one of the arms (21a, 21b) having a portion (28A) whose cross-section is larger than that of the portion of the arm corresponding to the end of the opening (22).

15. The contact probe (20) according to claim 5 or 11, characterized in that, The contact probe has a rectangular transverse cross-section, and the variable transverse cross-section is obtained by changing the base dimension of the rectangular transverse cross-section.

16. The contact probe (20) according to claim 1, characterized in that, The device includes a contact tip (20A) with a thinned structure, the contact tip (20A) comprising a base and an end tip, the base having a cross section equal to or equivalent to the cross section of the probe body (20C), where equivalent means the difference between the two cross sections is ±20%, and the end tip having a reduced cross section.

17. The contact probe (20) according to claim 1, characterized in that, The device includes a contact head (20B) with a thinned structure, the contact head (20B) comprising a base and an end tip, the base having a cross section equal to or equivalent to that of the probe body (20C), where equivalent means the difference between the two cross sections is ±20%, and the end tip having a reduced cross section.

18. The contact probe (20) according to claim 1, characterized in that, The contact head (20B) includes an enlargement (25) with a cross-section larger than that of the probe body (20C) and defines the undercut wall of the contact head (20B).

19. The contact probe (20) according to claim 1, characterized in that, In the resting state, when the contact probe (20) is not abutting the contact pad of the device under test, the value of the total longitudinal extension (Ls) of the contact probe is selected between 2 mm and 5 mm.

20. A probe tip (30) for testing the function of a device under test, comprising at least one upper guide (31) having an upper guide hole (31A) and a lower guide (32) having a lower guide hole (32A), wherein the upper guide hole and the lower guide hole are used to accommodate a plurality of contact probes, characterized in that, The contact probe (20) is manufactured according to any one of the preceding claims.

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