Flexible films suitable for transmission of high frequency (RF) power signals and corresponding probe cards for high frequency (RF) power testing of electronic devices

Abstract

This application describes a flexible membrane (30) suitable for transmitting high-frequency power signals, the membrane comprising a plurality of contact pads (31A, 31B) adapted to be electrically connected to a plurality of micro-contact probes (25) and formed in a central portion (30A) of the flexible membrane (30), a plurality of contact structures (31C) adapted to be electrically connected to a support plate (24) and formed in a peripheral portion (30C) of the flexible membrane (30), and a plurality of conductive tracks (33A, 33B) formed in the flexible membrane (30), each of the conductive tracks (33A, 33B) electrically connecting one of the contact pads (31A, 31B) to one of the contact structures (31C), the flexible membrane (30) further comprising an intermediate portion (30B) arranged and connected between the central portion (30A) and the peripheral portion (30C). Suitablely, the flexible membrane is divided into a first region (34A) having a first total thickness (HA) and a second region (34B) having a second total thickness (HB), the first region (34A) being continuous and adjacent to the second region (34B), the first total thickness (HA) having a value less than or equal to 75 μm, and the second total thickness (HB) having a value greater than the first total thickness (HA). Furthermore, the first region (34A) of the membrane 20 (30) extends at a central portion (30A) and includes a plurality of contact pads (31A, 31B). This application also describes a probe card (20) including such a flexible membrane (30) for testing electronic devices.

Description

Technical Field

[0001] This invention relates to a flexible membrane suitable for transmitting high-frequency power signals.

[0002] More specifically, the present invention relates to a flexible membrane comprising a plurality of contact pads adapted for electrical connection to a plurality of micro-contact probes and formed in a central portion of the flexible membrane; a plurality of contact structures adapted for electrical connection to a support plate and formed in a peripheral portion of the flexible membrane; and a plurality of conductive tracks, each of which electrically connects one of the aforementioned contact pads to one of the aforementioned contact structures, the flexible membrane further comprising an intermediate portion arranged and connected between the central portion and the peripheral portion.

[0003] The present invention also relates to a probe card comprising such a flexible membrane.

[0004] The following description is based on this application area and is intended only to simplify the explanation. Background Technology

[0005] As is well known, a probe card is essentially a device suitable for electrically connecting multiple contact pads of a microstructure (especially electronic devices integrated on a semiconductor wafer) to corresponding channels of a test apparatus that performs functional testing (especially electrical testing, or general testing).

[0006] Testing integrated circuits is particularly helpful in identifying and isolating defective circuits early in the production process. Typically, probe cards are used to electrically test circuits integrated on the wafer before they are cut and assembled into a hermetically sealed chip package.

[0007] Probe cards typically include multiple contact probes formed from special alloy conductive wires with good electrical and mechanical properties. These probes allow suitable pads made on the device under test (DUT) to contact additional pads made on the interface card of the test setup, thereby allowing signals to be transmitted from and received by the DUT.

[0008] For high-frequency applications, the total length of the contact probe should be significantly reduced, especially to less than 5000 μm, to limit the well-known self-inductance phenomenon, which is amplified in the case of high-frequency or radio frequency (RF) signals. It should be noted that the term "probe for high-frequency applications" refers to a probe capable of transmitting signals with frequencies exceeding 1 GHz.

[0009] However, the reduction in probe body length significantly increases its stiffness, which translates to an increased force exerted on the contact pads of the device under test (DUT). This can lead to these pads breaking and causing irreparable damage to the DUT, a situation that is clearly undesirable. Furthermore, the increased stiffness due to the reduced contact probe length also increases the risk of the probe itself breaking.

[0010] To address these issues, several solutions are known, in which a probe card comprises a flexible membrane associated with multiple reduced-length contact probes or microprobes adapted to provide mechanical and electrical contact with the contact pads of the device under test (DUT), and at least one damping structure corresponding to these contact probes and associated with the membrane. The membrane is suitably equipped with metallic tracks capable of connecting the microprobes to the contact pads of the interface card of the test setup, enabling the transmission of high-frequency power signals (RF) between the interface card and the DUT.

[0011] Figure 1 A known solution of this type is illustrated schematically.

[0012] In particular, the figure illustrates by way of example a probe card 10, which includes at least one damping structure 17 inserted between a flexible membrane 15 and an interface plate or support plate 14, preferably a printed circuit board (PCB), to ensure the connection between the probe card 10 and the test device (not shown).

[0013] Suitablely, the flexible membrane 15 includes a first portion or central portion 15A, a second portion or intermediate portion 15B, and a third portion or peripheral portion 15C. More specifically, the central portion 15A is intended to contact the damping structure 17, the peripheral portion 15C is intended to contact the support plate 14, and the intermediate portion 15B is a portion intended to deform, particularly during test operations of the device itself, after movement of the device under test 12 integrated on the semiconductor wafer 11 in contact with the central portion 15A, elongating and shortening.

[0014] The probe card 10 also includes a plurality of miniature contact probes 16 arranged on the first surface F1 of the flexible membrane 15, particularly formed at its central portion 15A, according to Figure 1 In the local reference frame, the first surface F1 is the underside of the flexible membrane 15.

[0015] The miniature contact probe 16 is adapted to contact the contact pad 12A of the device under test 12 and is made of a conductive material, such as platinum, rhodium, palladium, silver, copper or alloys thereof, preferably platinum alloys.

[0016] Especially in high-frequency applications, the micro-contact probes 16 have reduced heights, for example, less than 200 μm, typically between 10 μm and 200 μm. Height refers to the dimension of these probes measured in a direction orthogonal to the device under test 12 (i.e., along the Z-axis of the local reference frame shown in the figure). In commercially known solutions, these micro-contact probes 16 are fabricated as pyramids and grown directly on the flexible film 15 using photolithography.

[0017] Furthermore, the damping structure 17 abuts against the second surface F2 of the flexible membrane 15, opposite to the first surface F1, and is positioned corresponding to the central portion 15A of the flexible membrane 15, that is, corresponding to the area of ​​the wafer 11 equipped with the micro-contact probe 16 and thus to the contact pad 12A of the device under test 12 integrated thereon. Therefore, the damping structure 17 forms an abutment element against the flexible membrane 15 in the central portion 15A and holds it in the Z-axis direction when the micro-contact probe 16 presses against the contact pad 12A of the device under test 12.

[0018] The damping structure 17 also serves as a damping element for the micro-contact probe 16, adjusting its contact force on the contact pad 12A of the device under test 12. Suitablely, the damping structure 17 can also be made of a suitable material to maximize the damping effect of the micro-contact probe 25 and ensure the flatness of the central portion 15A of the membrane 15 when in contact with the device under test 12.

[0019] The flexible membrane 15 also includes conductive tracks 13 adapted to transmit signals from the micro-contact probes 16 to and properly connect to the support plate 14. The conductive tracks 13 may be formed on the surface of the membrane 15, particularly on or above the second surface F2 according to the partial reference frame in the figure, and extend along the middle portion 15B of the flexible membrane 15 from the central portion 15A of the flexible membrane 15, corresponding to the respective micro-contact probes 16 to which they are connected, thereby connecting to the contact pads 14A of the support plate 14 at the peripheral portion 15C of the membrane 15.

[0020] The damping structure 17 can also be fabricated using a structure corresponding to the probe head, which is equipped with a body that extends multiple contact probes between the interface card of the test device and the flexible membrane 15, particularly adapted to abut against the second surface F2 of the flexible membrane 15. These contact probes are actually insulated from the conductive tracks 13 formed in the flexible membrane 15, and signals are transmitted by miniature contact probes 16.

[0021] In high-frequency or radio-frequency applications, it is well known that the impedance values ​​of these conductive tracks 13 need to be controlled, which limits the width value of these conductive tracks 13 as a function of the thickness of the flexible film 15 (typically formed of polyamide) on which they are fabricated.

[0022] In current RF applications, these conductive tracks 13 are fabricated on a 25μm thick polyamide flexible film 15 using copper tracks with a thickness of 10-15μm and a width of 50μm, ensuring a controlled impedance of 50 ohms. These conductive tracks 13 also have a certain length, potentially reaching several centimeters, to accommodate the interface card 14 of the test device. Specifically, according to... Figure 1The local reference frame shown has the following dimensions: thickness represents the dimension of conductive track 13 along the Z-axis, width represents its dimension along the Y-axis, and length represents its dimension along the X-axis.

[0023] The conductive rails 13 with the aforementioned dimensions can function normally in low- and medium-power RF applications, but they have proven ineffective in RF power applications, i.e., values ​​exceeding 35 dBm. In fact, in such cases, typical copper conductive rails can reach temperatures of 600°C, which would cause the conductive rails themselves to melt.

[0024] Therefore, the technical problem of the present invention is to provide a flexible membrane capable of transmitting high-frequency (RF) and high-power signals in conductive tracks fabricated therein, and a corresponding probe card including the membrane for contacting a plurality of miniature contact probes suitable for transmitting power signals, to ensure that the card functions properly when testing electronic devices integrated in RF power applications. Summary of the Invention

[0025] The present invention provides a flexible film having at least a portion of an increased thickness on conductive tracks for transmitting high-frequency (RF) power signals, these tracks having a width that prevents them from merging, and a portion of a reduced thickness in the contact area of ​​a micro-contact probe, the thickness of which ensures proper manipulation of the micro-contact probe.

[0026] Based on this solution approach, the technical problem is solved by a flexible film suitable for transmitting high-frequency power signals. This flexible film includes multiple contact pads formed in the central portion of the flexible film and suitable for electrical connection with multiple micro-contact probes, multiple contact structures formed in the peripheral portion of the flexible film and suitable for electrical connection with a support plate, and multiple conductive tracks formed in the flexible film. Each conductive track electrically connects one of the contact pads to one of the contact structures. The flexible film also includes an intermediate portion disposed between the central portion and the peripheral portion. The flexible film is characterized by being divided into a first region having a first total thickness and a second region having a second total thickness. The first region is continuous and adjacent to the second region. The value of the first total thickness is less than or equal to 75 μm, and the value of the second total thickness is greater than the value of the first total thickness. The first region of the film extends at the central portion and includes the aforementioned multiple contact pads.

[0027] More specifically, the present invention includes the following additional and optional features, taken individually or in combination.

[0028] According to one aspect of the invention, the second region may include a plurality of crossbars separated by air gaps.

[0029] Furthermore, the flexible membrane may include a multilayer structure formed by alternating multiple elastic layers and multiple conductive layers. The conductive layers include multiple conductive traces connected to form conductive tracks for connecting the contact pad to the contact structure. The width of the conductive traces formed in the first region is smaller than that of the conductive traces formed in the second region. The wider conductive traces are formed on crossbars, if any.

[0030] The flexible membrane may also include conductive structures suitable for connecting conductive traces made in different conductive layers.

[0031] According to another aspect of the invention, the flexible membrane may comprise a multilayer structure formed of at least a first elastic layer, an upper second elastic layer, a third elastic layer and a final elastic layer, wherein a first conductive layer is formed in the first elastic layer, a second conductive layer is formed in the second elastic layer, a third conductive layer is formed in the third elastic layer, and the final elastic layer covers the third elastic layer and the upper second elastic layer which is not the third elastic layer, wherein the third elastic layer includes crossbars, if present.

[0032] According to another aspect of the invention, the first elastic layer, the first conductive layer, and the second elastic layer may extend along a first region and a second region of the flexible film, and the third elastic layer and the third conductive layer may extend only along the second region. The second conductive layer includes a first plurality of conductive traces that extend along the first region, partially penetrate the middle portion of the flexible film, and connect with a plurality of conductive traces formed in the third conductive layer.

[0033] The second conductive layer may also include a second plurality of conductive traces extending along the first and second regions and formed opposite to the air gap of the dividing crossbar, if present.

[0034] According to another aspect of the invention, the flexible film may include a first conductive connection structure between conductive traces formed in a first conductive layer and conductive traces formed in a second conductive layer, a second conductive connection structure between conductive traces formed in a second conductive layer and conductive traces formed in a third conductive layer, and a third conductive connection structure between traces formed in a third conductive layer and traces formed in a base, the base protruding from the third conductive layer and electrically connected to the conductive portion of the flexible film.

[0035] Suitablely, according to one aspect of the invention, the conductive traces formed in the third conductive layer may have a greater width than the conductive traces formed in the second conductive layer, preferably they may have a width of more than 50 μm.

[0036] These conductive traces can be further fabricated in grooves arranged in the elastic layer.

[0037] According to another aspect of the invention, the flexible film may include first conductive tracks, including a first portion formed by conductive traces made in a second conductive layer and a second portion formed by conductive traces having a greater width made in a third conductive layer. Each first conductive track is connected to a first contact pad made in a central portion of the flexible film and is adapted to contact a miniature contact probe for transmitting high-frequency power signals, i.e., signals with frequencies exceeding 1 GHz and power exceeding 35 dBm. These first conductive tracks are made on crossbars, if present.

[0038] The flexible membrane may also include grounding wires made by grounding conductive tracks, each grounding conductive track comprising a first portion formed by traces made in a second conductive layer and a second portion formed by traces made in a first conductive layer, the first and second portions being interconnected by conductive structures, each grounding conductive track being connected to a grounding pad made in a central portion of the flexible membrane, the grounding conductive track being made in a crossbar at the location of the first conductive track, if present.

[0039] The grounding conductive track may also include a third portion formed by traces made in a third conductive layer, which is interconnected with a first portion formed by traces made in a second conductive layer via additional conductive structures.

[0040] According to another aspect of the invention, the flexible film may include second conductive tracks made of conductive traces of a second conductive layer, the second conductive tracks being arranged in a region of the second elastic layer that does not have crossbars forming a third elastic layer, and if present, each second conductive track being connected to a second contact pad formed in the central portion of the flexible film and adapted to contact a miniature contact probe for transmitting high-frequency non-power signals, i.e. signals with frequencies exceeding 1 GHz and power less than 35 dBm.

[0041] Appropriately, the first conductive track, the second conductive track, and the ground conductive track may be further connected to the conductive portion formed in the peripheral portion of the flexible membrane.

[0042] In addition, the central portion may include multiple strips, on which the contact pads of the micro-contact probes are made.

[0043] According to one aspect of the invention, the flexible membrane may be made of a dielectric material, preferably polyamide, and may include conductive tracks made of a conductive material, preferably copper.

[0044] According to another aspect of the invention, the first elastic layer, the second elastic layer and the third elastic layer may have corresponding first thickness, second thickness and third thickness, the values ​​of which are between 10 μm and 30 μm, preferably 25 μm, and the last elastic layer may have a fourth thickness, the values ​​of which are between 5 μm and 15 μm, preferably 5 μm.

[0045] Furthermore, the thicknesses of the first conductive layer, the second conductive layer, and the third conductive layer can be between 10 μm and 15 μm, preferably 10 μm.

[0046] Finally, the first region may have a first total thickness between 40 μm and 50 μm, and the second region may have a second total thickness between 70 μm and 125 μm.

[0047] This technical problem is also solved by a probe card for testing electronic devices, which includes at least one support plate, at least one flexible film, and a plurality of micro-contact probes associated with a first side of the flexible film. These micro-contact probes are adapted to abut against a plurality of contact pads of the device under test and are electrically connected to a plurality of conductive tracks formed in the flexible film and to the contact pads of the support plate, the flexible film being manufactured as described above.

[0048] According to one aspect of the invention, the probe card may include a damping structure inserted between the flexible membrane and the support plate, preferably including a plurality of pre-mounted probes adapted to abut against the flexible membrane corresponding to the central portion.

[0049] Finally, the probe card may include multiple miniature contact probes with a height of less than 200 μm.

[0050] The features and advantages of the flexible membrane and probe card according to the invention will become apparent from the following description of its embodiments by way of non-limiting example with reference to the accompanying drawings. Attached Figure Description

[0051] - Figure 1 A probe card for high-frequency applications, fabricated according to existing technology, is illustrated schematically.

[0052] - Figure 2A A probe card for high-frequency (RF) power applications, fabricated according to the present invention, is illustrated schematically. Figure 2B Shown at an enlarged scale the contents contained Figure 2A The miniature contact probes in the probe card;

[0053] - Figures 3A-3C An alternative embodiment of a flexible membrane manufactured according to the present invention and included in the probe card of FIG2 is illustrated schematically;

[0054] - Figure 4 Schematally shown at an enlarged scale Figure 3A Details of the flexible membrane;

[0055] - Figure 5A and 5B They are shown at magnified scale. Figure 3B and Figure 3C Some details of the flexible membrane; and

[0056] - Figure 6 A schematic top view is shown. Figure 3B Flexible membrane. Detailed Implementation

[0057] Referring to Figure 2, in particular, the probe card manufactured according to the present invention is generally schematically represented by 20.

[0058] It should be noted that these figures are schematic diagrams, not drawn to scale, but are intended to emphasize key features of the invention. Furthermore, different elements are depicted schematically in the figures, and their shapes may vary depending on the desired application. Additionally, it should be noted that in the figures, the same reference numerals refer to elements that are identical in shape or function. Finally, the special arrangements relating to one embodiment shown in the figures can also be used for other embodiments shown in other figures.

[0059] In its most general form, probe card 20 is a component adapted to connect to a device (not shown) to test electronic devices 22 integrated on semiconductor wafer 21. More specifically, Figure 2A The probe card 20 shown is suitable for high-frequency (RF) power applications, that is, signals with transmission frequencies exceeding 1 GHz and power values ​​exceeding 35 dBm. These signals will be referred to as power RF signals below.

[0060] like Figure 2A Schematic illustration: In this configuration, the probe card 20 includes at least one damping structure 27 shaped like a probe tip, comprising a body 28 that houses and supports a plurality of contact elements, wherein four of the contact elements are located in… Figure 2A The examples shown are for illustrative purposes only. For instance, body 28 may include a pair of plate-like guides with guide holes in which contact elements slide, as described below, serving as damping elements or pre-mounted elements, and are therefore referred to hereinafter as pre-mounted probes 29. Each pre-mounted probe 29 includes at least one first end 29A and at least one second end 29B, and moves independently of adjacent pre-mounted probes.

[0061] The pre-mounted probe 29 has a length between 1.5 mm and 10 mm and is made of a material suitable for having sufficient bending capacity and for maximizing the damping effect. In particular, the pre-mounted probe can be made of a material commonly used to form contact probes for conventional probe heads.

[0062] The probe card 20 also includes a support plate 24, preferably a printed circuit board (PCB), which ensures the connection between the probe card 20 and the testing device (not shown); the support plate 24 thus acts as an interface card for the testing device. In particular, the first end 29A of the pre-mounted probe 29 is adapted to abut against the support plate 24.

[0063] The probe card 20 also includes a flexible membrane 30 manufactured according to the present invention, the flexible membrane having a first surface F1 and a second surface F2 opposite to the first surface F1, the second end 29B of the pre-mounted probe 29 being adapted to abut against the first surface, according to Figure 2A In the local reference frame, the second surface F2 is the lower surface, i.e., the surface facing the device under test 22 integrated in the semiconductor wafer 21, and according to Figure 2A The local reference frame, the first surface F1 is the upper surface, that is, the surface facing the damping structure 27 and the support plate 24.

[0064] Appropriately, the pre-mounted probe 29 has mechanical contact with the support plate 24 and the flexible membrane 30, but no electrical contact.

[0065] Therefore, the damping structure 27 is inserted between the flexible membrane 30 and the support plate 24. Specifically, the flexible membrane 30 includes a first portion or central portion 30A for contacting the damping structure 27 to contact the pre-mounted probe 29 and a second portion or peripheral portion 30C for contacting the support plate 24; the flexible membrane 30 also includes an intermediate connecting portion 30B located between the central portion 30A and the peripheral portion 30C. The intermediate portion 30B is the portion that deforms, particularly elongates and shortens, during the test operation of the probe card 20 as the device under test 22 integrated on the semiconductor wafer 21 moves into contact with the central portion 30A.

[0066] The flexible membrane 30 is electrically connected to the support plate 24 via its peripheral portion 30C. This electrical connection occurs, for example, through a suitable conductive contact pad 24A of the support plate 24 and a suitable contact pad or conductive portion 31C formed in the peripheral portion 30C of the flexible membrane 30.

[0067] like Figure 2A As shown, the contact pad 24A of the support plate 24 is formed on the surface F of the support plate facing the damping structure 27 and the flexible membrane 30, according to... Figure 2A The local reference frame is given by surface F, which is the lower surface.

[0068] In an embodiment not shown in the figures, the support plate 24 may include suitable openings to allow the flexible membrane 30 to pass through, in which case the flexible membrane 30 is formed on the side opposite to the surface F of the support plate 24 (i.e., according to...). Figure 2AA local reference frame is formed on the upper surface of the support plate, and contact pads (not shown) are connected. Alternatively, the flexible membrane 30 can be directly connected to the testing device.

[0069] In a preferred embodiment of the invention, the conductive portion 31C of the flexible film 30 is connected to the contact pad 24A of the support plate 24 via a pressing contact. Alternatively, the flexible film 30 and the support plate 24 may be associated with the peripheral portion 30C of the flexible film 30 via conductive rubber or a weld.

[0070] Suitable, the central portion 30A of the flexible membrane 30 is associated with at least one bearing element or support 26, which is preferably plate-shaped.

[0071] In a preferred embodiment of the invention, the support 26 on which the flexible membrane 30 is disposed includes a plurality of portions 26h for accommodating a plurality of micro-contact probes 25 adapted to contact the contact pad 22A of the device under test 22. The flexible membrane 30 (particularly its central portion 30A) is inserted between pre-mounted probes 29 and micro-contact probes 25 and is adapted to insulate each pre-mounted probe 29 from its corresponding micro-contact probe 25.

[0072] What's even more special is that, Figure 2B As shown in the enlarged view, each micro contact probe 25 includes a first end 25A and a second end 25B. The first end is adapted to abut against the contact pad 22A of the device under test 22, and the second end is adapted to abut against a corresponding contact pad formed on the second surface F2 of the central portion 30A of the flexible membrane 30. The central portion 30A is arranged correspondingly to the device under test 22.

[0073] In one embodiment, the micro-contact probe 25 is integral with the central portion 30A of the flexible membrane 30, and in particular, the micro-contact probe is formed on the central portion 30A.

[0074] The micro-contact probe 35 can be T-shaped (or inverted mushroom-shaped), wherein the trunk of the T is connected to the flexible film 30, and the head of the T is adapted to contact the contact pad 22A of the device under test 22. Alternatively, the contact probe 35 can be shaped as a conductive protrusion, which may in turn include a protruding contact portion for contacting the contact pad 22A of the device under test 22. Obviously, the above examples should not be construed as limiting the invention, and the micro-contact probe 25 can have any suitable shape for connecting to the contact pad 22A of the device under test 22 integrated on the semiconductor wafer 21; for example, they can be shaped as so-called cylindrical or inverted (preferably truncated) pyramidal shapes.

[0075] The miniature contact probe 25 is made of a conductive material selected from, for example, platinum, rhodium, palladium, silver, copper or alloys thereof, preferably a platinum alloy.

[0076] Suitable for use, the miniature contact probes 25 have a reduced height, particularly less than 200 μm, typically between 10 μm and 200 μm. The height refers to the dimension of these contact probes 25 measured along a direction orthogonal to the device under test 22 and therefore to the semiconductor wafer 21 (i.e., along the Z-axis of the local reference frame shown in the figure). Thus, the miniature contact probes 25 of the probe card 20 of the present invention are suitable for testing high-frequency devices, and their height is suitable for avoiding undesirable self-inductance phenomena.

[0077] Advantageously, according to the invention, the flexible membrane 30 includes suitable conductive tracks 33A or 33B adapted to transmit signals from the micro-contact probe 25 to the support plate 24, that is, to transmit signals from the central portion 30A of the flexible membrane to the peripheral portion 30C of the flexible membrane. Suitably, as will be explained below, the flexible membrane 30 according to the invention has a multilayer structure comprising suitably alternating and shaped dielectric and conductive layers.

[0078] Conductive tracks 33A or 33B can be fabricated on the surface of the flexible film 30. In particular, they can be fabricated on the second surface F2 or its upper surface according to the local reference frame in the figure, or they can be fabricated inside the flexible film 30 itself and start from the central portion 30A of the flexible film 30, contacting the corresponding micro-contact probe 25, extending along the middle portion 30B of the flexible film 30, until reaching its peripheral portion 30C. Conductive tracks can also be fabricated on the first surface F1 of the flexible film 30, and suitable electrical contact structures, such as metallized vias or conductive vias, can be fabricated between the first surface F1 and the second surface F2 of the flexible film 30 for contacting these conductive tracks with the support plate 24, and in particular with its contact pad 24A.

[0079] In a preferred embodiment, such as Figure 2A As shown, the flexible membrane 30 is suitably shaped to preferably include a plurality of strips or offcuts 31 in its central portion 30A. The distal end of each strip 31 includes a contact pad 31A or 31B, preferably made of a metallic material, on the first surface F1 facing the device under test 22, and the second end 25B of the micro-contact probe 25 abuts against the contact pad.

[0080] Furthermore, the second end 29B of each pre-mounted probe 29 always abuts against the second surface F2 of the flexible membrane 30 at the distal end of the strip 31. Thus, the second end 29B of the pre-mounted probe 29 and the second end 25B of the micro-contact probe 25 abut against the distal end 27B of the same corresponding strip 31 of the flexible membrane 30, but from the opposite side of the strip 31, i.e., abutting against the first surface F1 and the second surface F2 of the flexible membrane 30, respectively.

[0081] In this way, the pre-mounted probe 29 acts as a damping element for the miniature contact probe 25, ensuring signal transmission between the probe card 20 and the device under test 22 integrated on the semiconductor wafer 21 via conductive tracks fabricated in the flexible film 30. In other words, the electrical signal is transmitted from the device under test 22 to the support plate 24 via the miniature contact probe 25 and the conductive tracks 33A or 33B fabricated in the flexible film 30, while the overall mechanical behavior of the probe card 20 is determined by the movement of the miniature contact probe 25, the flexible film 30, and the damping structure 27 placed on the support plate 24.

[0082] Appropriately, each pre-mounted probe 29 moves independently of its adjacent probe, such that each micro-contact probe 25 moves independently of its adjacent probe when it contacts the contact pad 22A of the device under test 22. Combined with the flexibility of the intermediate flexible membrane 30, and particularly its strip 31, this effectively compensates for any potential horizontal differences in the device under test 22, especially its contact pad 22A.

[0083] The pre-mounted probes 29 also keep the flexible membrane 30, particularly its strip 31, pressed against the second end 25A of the micro-contact probe 25, thus ensuring suitable mechanical coupling between the micro-contact probe 25 and the flexible membrane 30, particularly its strip 31. Appropriately, each micro-contact probe 25 is pressed into contact with a contact pad 31A or 31B formed on the strip 31 at the first surface F1 of the flexible membrane 30, while the corresponding pre-mounted probe 29 rests on the strip 31 at the second surface F2 of the flexible membrane 30, thereby achieving ideal mechanical coupling of the probe card 20. Each contact pad 31A or 31B also contacts a corresponding conductive track 33A or 33B formed in the flexible membrane 30, which connects to the corresponding conductive portion 31C of the flexible membrane 30, thereby electrically connecting to the support plate 24, particularly its contact pad 24A.

[0084] The flexible membrane 30 is made of a dielectric material, preferably polyamide, which provides the required flexibility and electrical insulation, while the conductive tracks are preferably made of copper.

[0085] Typically, the conductive track is made of copper wire with a thickness of 10-15 μm on a polyamide film with a thickness of 50 μm; since a controlled impedance of 50 ohms must be ensured in typical applications, the copper wire has a width of 50 μm and a length of several centimeters to completely pass through the flexible film 30 and reach the support plate 24, thereby reaching the test device.

[0086] Traces with the aforementioned dimensions function normally when transmitting low-power RF signals (i.e., power values ​​less than 35 dBm). However, they have proven unsuitable for high-power RF applications, specifically when transmitting high-power RF signals. In fact, under these conditions, the high power and high current values ​​can cause the temperature of a 50 μm wide and 10-15 μm thick copper wire to reach up to 600°C, which degrades the polyamide substrate of the flexible film 30, leading to damage to the film itself and failure of its probe card 20.

[0087] In order to transmit these power radio frequency signals, it is necessary to use conductive tracks with a width of more than 50 μm, and to ensure a controlled impedance of 50 ohms, the thickness of the flexible film 30 also needs to be increased. However, the increased thickness of the flexible film 30 leads to its undesirable stiffness and makes it difficult to manipulate the micro-contact probe 25, which hinders the normal operation of the probe card 20 containing it.

[0088] Advantageously, according to the invention, such as Figure 3A As shown, the flexible membrane 30 is divided into a first region 34A with a first total thickness HA and a second region 34B with a second total thickness HB, the second total thickness HB being greater than the first total thickness HA. Thickness refers to the dimension of the membrane 30 in a direction orthogonal to its unfolded plane when at rest; the membrane is substantially planar. In its more general form, the central portion 30A has the first total thickness HA, the value of which corresponds to currently known solutions, particularly being less than or equal to 75 μm, preferably less than or equal to 50 μm.

[0089] Appropriately, the first region 34A extends to the central portion 30A of the flexible membrane 30, which corresponds to the device under test 22. Thus, the contact pads 31A or 31B of the micro-contact probe 25 are formed in the first region 34A of the flexible membrane 30.

[0090] Conversely, the second region 34B extends to include the middle portion 30B and the peripheral portion 30C of the flexible membrane 30, and thus includes the conductive portion 31C of the flexible membrane 30 connected to the contact pad 24A of the support plate 24.

[0091] exist Figure 3AIn the preferred embodiment shown, the flexible film 30 includes a multilayer structure formed by alternating multiple elastic layers and multiple conductive layers; more specifically, the flexible film 30 includes a multilayer structure formed by a first elastic layer PL1, a top second elastic layer PL2, a third elastic layer PL3, and a final elastic layer FL. A first conductive layer ML1 is formed in the first elastic layer, a second conductive layer ML2 is formed in the second elastic layer, a third conductive layer ML3 is formed in the third elastic layer, and the final elastic layer covers the third elastic layer PL3 and the second elastic layer PL2 above it (which is not the third elastic layer PL3). More specifically, the first elastic layer PL1, the first conductive layer ML1, and the second elastic layer PL2 extend along the entire length of the flexible film 30, i.e., along the first region 34A and the second region 34B. The length refers to the length of the flexible film 30 along... Figure 3A The dimensions in the local reference frame X-axis direction. The second conductive layer ML2 includes traces extending along the entire first region 34A and partially penetrating the intermediate portion 30B, as well as traces extending along the entire length of the flexible film 30 (i.e., along the first region 34A and the second region 34B), as will be described below. Finally, the third elastic layer PL3 and the third conductive layer ML3 extend only along the second region 34B.

[0092] Suitablely, the first elastic layer PL1, the second elastic layer PL2, the third elastic layer PL3, and the final elastic layer FL are made of polyamide, while the first conductive layer ML1, the second conductive layer ML2, and the third conductive layer ML3 include copper traces suitable for forming conductive tracks 33A, 33B of the flexible film 30. More specifically, the first elastic layer PL1, the second elastic layer PL2, and the third elastic layer PL3 have corresponding first thickness H1, second thickness H2, and third thickness H3, the values ​​of which are between 10 μm and 30 μm, preferably 25 μm, while the final elastic layer FL has a fourth thickness H4, the value of which is between 5 μm and 15 μm, preferably 5 μm. The first conductive layer ML1, the second conductive layer ML2, and the third conductive layer ML3 have substantially the same thickness, denoted by HML, the value of which is between 10 μm and 15 μm, preferably 10 μm. Thickness refers to the thickness along... Figure 3A The dimension in the Z-axis direction of the local reference frame.

[0093] In one embodiment, the second thickness HB is 2 to 4 times the first thickness HA, allowing the formation of conductive tracks with a width 2 or 3 times that of conventional copper traces. In other words, for a first thickness HA with a value between 40 μm and 50 μm, the second thickness can have a value between 70 μm and 125 μm to enable the metal trace to be extended to a width of 200 μm–400 μm. Metal tracks with such widths can allow the transmission of signals with power from 35 dBm to 45 dBm while ensuring a controlled impedance of 50 ohms.

[0094] Appropriately, in the final elastic layer FL, openings Ap are arranged at corresponding positions to the contact pads 31A, 31B of the micro-contact probe 25. In particular, these openings Ap are formed in the central portion 30A, that is, in the thinner first region 34A, where only the first elastic layer PL1 and the second elastic layer PL2 overlap.

[0095] The flexible membrane 30 also includes protrusions formed on the last elastic layer FL corresponding to the peripheral portion 30C, i.e. in the second region 34B with a greater thickness. These protrusions have a base 32 on which conductive portions 31C are formed for connection with contact pads 24A of the support plate 24.

[0096] Suitable, the flexible film 30 also includes conductive structures or TH (Through-all vias) connecting different conductive layers, particularly traces formed in different conductive layers. For example, the flexible film 30 includes a first conductive structure TH1 connecting traces formed in a first conductive layer ML1 and traces formed in a second conductive layer ML2, a second conductive structure TH2 connecting traces formed in the second conductive layer ML2 and traces formed in a third conductive layer ML3, and a third conductive structure TH3 connecting traces formed in the third conductive layer ML3 and traces formed in the substrate 32 of the conductive portion 31C. According to an alternative embodiment, the TH-type conductive structure is also suitable for transmitting radio frequency signals.

[0097] Advantageously, according to the invention, the flexible film 30 includes traces formed in the third conductive layer ML3, the width of which is greater than the width of the traces formed in the second conductive layer ML2, the width referring to the width along... Figure 3A The dimensions in the Y direction of the local reference frame. Due to the overlap between the second elastic layer PL2 and the third elastic layer PL3, these traces can have a greater width in the third conductive layer ML3. That is, due to the presence of the second region 34B, which has a greater thickness than the first region 34A, the increased thickness under the third conductive layer ML3 allows for ensuring controlled impedance, especially for traces with greater width, where the controlled impedance is equal to 50 ohms.

[0098] In a preferred embodiment, the traces of the conductive layer are formed in suitable grooves arranged in the underlying elastic layer. In other words, the first conductive layer ML1 includes a plurality of traces formed in grooves arranged in the first elastic layer PL1, the second conductive layer ML2 includes a plurality of traces formed in grooves arranged in the second elastic layer PL2, and the third conductive layer ML3 includes a plurality of traces formed in grooves arranged in the third elastic layer PL3.

[0099] In particular, such as Figure 4As schematically shown, the flexible film 30 includes a first conductive track 33A, which comprises a first portion formed by traces made in the second conductive layer ML2 and a second portion formed by traces with a greater width made in the third conductive layer ML3. The first and second portions are interconnected by a second conductive structure TH2. Each first conductive track 33A is connected to a first contact pad 31A made in the central portion 30A of the flexible film 30 and is adapted to contact a miniature contact probe 25 for transmitting power radio frequency signals. Therefore, the first contact pad 31A is also referred to as a power radio frequency pad.

[0100] A suitable grounding wire or ground is made by grounding conductive track 33G, which includes a first portion formed by traces made in the second conductive layer ML2 and a second portion formed by traces made in the first conductive layer ML1. The first portion and the second portion are interconnected by a first conductive structure TH1. Each grounding conductive track 33G is connected to a grounding pad 31G made in the central portion 30A of the flexible film 30.

[0101] according to Figure 3B In the alternative embodiment schematically shown, the second region 34B of the flexible film 30 is not continuous, but is formed by a plurality of individual ridges or crossbars 35 separated by air gaps in the third elastic layer PL3. Suitably, the third conductive layer ML3 includes portions of the first conductive track 33A formed corresponding to the crossbars 35.

[0102] according to Figure 3C In another alternative embodiment, which is schematically shown, the third conductive layer ML3 also includes a third portion of a grounded conductive track 33G formed corresponding to the crossbar 35, which is connected to a first portion formed by traces formed in the second conductive layer ML2 via an additional conductive structure TH2G.

[0103] Appropriately, each crossbar 35 has a width LS, i.e., along Figure 3B The dimension of the local reference frame in the Y-axis direction exceeds 1 mm, thus enabling the accommodation of a conductive track 33A with a width LT exceeding 50 μm for transmitting power radio frequency signals. A width L1 of more than 5 mm or a width L2 of more than 10-20 mm can be provided between the crossbars 35.

[0104] As previously stated, the first conductive track 33A is therefore made corresponding to the crossbar 35, with a pair of grounded conductive tracks 33G appropriately placed on both sides, such as... Figure 5A and Figure 5B According to respectively Figure 3B and Figure 3C Alternative embodiments are illustrated schematically.

[0105] In this case, a second conductive track 33B formed in the second conductive layer ML2 can be disposed in a region corresponding to the second elastic layer PL2 that is independent of the crossbar 35 forming the third elastic layer PL3. The second conductive track 33B is adapted to transmit radio frequency non-power signals and is connected to a second contact pad 31B, which is always formed in the central portion 30A of the flexible film 30 and connected to a miniature contact probe 25 adapted to transmit radio frequency non-power signals. Therefore, the second contact pad 31B is also referred to as a radio frequency non-power pad.

[0106] The distribution of the crossbars 35, and therefore the distribution of the first conductive tracks 33A used for transmitting power radio frequency signals, can differ correspondingly to different portions of the flexible membrane 30, such as... Figure 6 As schematically shown, the flexible membrane 30 includes a right portion 30R of the flexible membrane 30 having a higher density of crossbars 35, and a left portion 30L of the flexible membrane 30 having a lower density of crossbars 35.

[0107] The first conductive track 33A, the second conductive track 33B, and the ground conductive track 33G are also connected to the conductive portion 31C in the peripheral portion 30C of the flexible membrane 30.

[0108] In summary, the flexible film according to the invention allows for the fabrication of a probe card suitable for power radio frequency applications, the structure of which consists only of miniature contact probes capable of transmitting signals, including power radio frequency type and radio frequency non-power type, all thanks to the miniature contact probes and the metal tracks fabricated in the flexible film, without having to employ a mixed configuration of probes with conventional dimensions and miniature contact probes as in known solutions.

[0109] Suitable, the flexible membrane includes at least one first region having a reduced thickness and at least one second region having an increased thickness, the first region being formed in the portion of the membrane corresponding to the device under test, thereby enabling the fabrication of conductive tracks with a width suitable for transmitting radio frequency power signals while ensuring a controlled impedance of 50 ohms.

[0110] According to an alternative embodiment, the second portion with increased thickness is not continuous, but comprises multiple crossbars on which metal tracks with greater width are formed. The area of ​​the membrane between these crossbars has the same thickness as the first portion and is adapted to form metal tracks with a nominal width for transmitting radio frequency non-power signals.

[0111] Obviously, those skilled in the art will be permitted to make several modifications and substitutions to the above-described probe card in order to meet occasional and specific requirements, all of which fall within the scope of protection of the invention as defined in the appended claims.

[0112] For example, the flexible membrane can be made into a right half and a left half, the right half including a crossbar forming a portion with a larger thickness, and the left half including a portion with a uniformly increasing thickness. Alternatively, the crossbars can be made with different thicknesses.

[0113] Finally, different numbers of elastic and conductive layers can be provided, as described above and shown in the figures.

Claims

1. A flexible membrane (30) suitable for transmitting high-frequency power signals, comprising a plurality of contact pads (31A, 31B) adapted to electrically connect a plurality of micro-contact probes (25) and formed in a central portion (30A) of the flexible membrane (30), a plurality of contact structures (31C) adapted to electrically connect a support plate (24) and formed in a peripheral portion (30C) of the flexible membrane (30), and a plurality of conductive tracks (33A, 33B) formed in the flexible membrane (30), each of the conductive tracks (33A, 33B) electrically connecting one of the contact pads (31A, 31B) to one of the contact structures (31C), the flexible membrane (30) further comprising an intermediate portion (30B) arranged and connected between the central portion (30A) and the peripheral portion (30C), characterized in that, The flexible membrane is divided into a first region (34A) having a first total thickness (HA) and a second region (34B) having a second total thickness (HB), the first region (34A) being continuous and adjacent to the second region (34B), the first total thickness (HA) having a value less than or equal to 75 μm, and the second total thickness (HB) having a value greater than the first total thickness (HA), characterized in that the first region (34A) of the membrane (30) extends correspondingly to the central portion (30A) and includes the plurality of contact pads (31A, 31B).

2. The flexible membrane (30) according to claim 1, characterized in that, The flexible film includes a multilayer structure formed by alternating multiple elastic layers (PL1, PL2, PL3, FL) and multiple conductive layers (ML1, ML2, ML3). The conductive layers (ML1, ML2, ML3) include multiple conductive traces adapted to form conductive tracks (33A, 33B) for connecting the contact pads (31A, 31B) to the contact structure (31C). The conductive traces formed in the first region (34A) have a smaller width than the conductive traces formed in the second region (34B).

3. The flexible membrane (30) according to claim 2, characterized in that, The flexible film includes conductive structures (TH1, TH2, TH3, TH2G) adapted to connect conductive traces formed in different conductive layers (ML1, ML2, ML3).

4. The flexible membrane (30) according to claim 3, characterized in that, The flexible membrane comprises a multilayer structure consisting of at least a first elastic layer (PL1), an upper second elastic layer (PL2), a third elastic layer (PL3), and a final elastic layer (FL). A first conductive layer (ML1) is formed in the first elastic layer, a second conductive layer (ML2) is formed in the second elastic layer, and a third conductive layer (ML3) is formed in the third elastic layer. The final elastic layer (FL) covers the third elastic layer (PL3) and the upper second elastic layer (PL2), which is not the third elastic layer (PL3). The first elastic layer (PL1), the first... The conductive layer (ML1) and the second elastic layer (PL2) extend along the first region (34A) and the second region (34B) of the flexible film (30), and are characterized in that the third elastic layer (PL3) and the third conductive layer (ML3) extend only along the second region (34B), the second conductive layer (ML2) includes a first plurality of conductive traces extending along the first region (34A), partially penetrating the middle portion (30B) of the flexible film (30), and connecting with the plurality of conductive traces formed in the third conductive layer (ML3).

5. The flexible membrane (30) according to claim 4, characterized in that, The second conductive layer (ML2) further includes a second plurality of conductive traces extending along the first region (34A) and the second region (34B). The flexible film includes a first conductive structure (TH1) connecting the conductive traces formed in the first conductive layer (ML1) and the conductive traces formed in the second conductive layer (ML2), a second conductive structure (TH2) connecting the conductive traces formed in the second conductive layer (ML2) and the conductive traces formed in the third conductive layer (ML3), and a third conductive structure (TH3) connecting the traces formed in the third conductive layer (ML3) and a base (32). The base protrudes from the third conductive layer (ML3) and is electrically connected to the contact structure (31C) of the flexible film (30).

6. The flexible membrane (30) according to claim 4, characterized in that, The conductive traces formed in the third conductive layer (ML3) have a wider width than the conductive traces formed in the second conductive layer (ML2).

7. The flexible membrane (30) according to claim 4, characterized in that, The conductive traces are formed in grooves arranged in the elastic layers (PL1, PL2, PL3).

8. The flexible membrane (30) according to claim 4, characterized in that, The flexible membrane includes first conductive tracks (33A), each first conductive track comprising a first portion formed by conductive traces formed in the second conductive layer (ML2) and a second portion formed by conductive traces of greater width formed in the third conductive layer (ML3). Each first conductive track (33A) is connected to a first contact pad (31A) formed in the central portion (30A) of the flexible membrane (30) and adapted to contact a miniature contact probe (25) for transmitting a high-frequency power signal, i.e., a signal with a frequency exceeding 1 GHz and a power exceeding 35 dBm. The flexible membrane also includes a grounding wire formed by a grounding conductive track (33G), the grounding conductive track comprising a first portion formed by conductive traces formed in the second conductive layer (ML3) and a second portion formed by conductive traces of greater width formed in the third conductive layer (ML3). The first portion is formed by traces made in the electrical layer (ML2) and the second portion is formed by traces made in the first conductive layer (ML1). The first portion and the second portion are interconnected by a first conductive structure (TH1). Each ground conductive track (33G) is connected to a grounding pad (31G) made in the central portion (30A) of the flexible film (30). The ground conductive track (33G) is made corresponding to the first conductive track (33A) and also includes a third portion formed by traces made in the third conductive layer (ML3). The third portion is interconnected with the first portion formed by traces made in the second conductive layer (ML2) by another conductive structure (TH2G).

9. The flexible membrane (30) according to claim 8, characterized in that, The flexible membrane includes a second conductive track (33B) made of conductive traces of the second conductive layer (ML2), the second conductive track being arranged in the second elastic layer (PL2), each second conductive track (33B) being connected to a second contact pad (31B) made in the central portion (30A) of the flexible membrane (30) and adapted to contact a miniature contact probe (25) for transmitting a high-frequency non-power signal, i.e. a signal with a frequency exceeding 1 GHz and a power less than 35 dBm.

10. The flexible membrane (30) according to claim 9, characterized in that, The first conductive track (33A), the second conductive track (33B) and the ground conductive track (33G) are also connected to a contact structure (31C) formed in the peripheral portion (30C) of the flexible membrane (30).

11. The flexible membrane (30) according to claim 1, characterized in that, The second region (34B) includes multiple crossbars (35) separated by air gaps.

12. The flexible membrane (30) according to claim 11, characterized in that, The flexible membrane comprises a multilayer structure formed by alternating multiple elastic layers (PL1, PL2, PL3, FL) and multiple conductive layers (ML1, ML2, ML3), wherein the conductive layers (ML1, ML2, ML3) include multiple conductive traces adapted to form conductive tracks (33A, 33B) for connecting the contact pads (31A, 31B) to the contact structure (31C), wherein the conductive traces formed in the first region (34A) have a smaller width than the conductive traces formed in the second region (34B), and the conductive traces having a larger width are formed at the crossbar (35).

13. The flexible membrane (30) according to claim 12, characterized in that, The flexible membrane includes a multilayer structure formed by at least a first elastic layer (PL1), an upper second elastic layer (PL2), a third elastic layer (PL3), and a final elastic layer (FL). A first conductive layer (ML1) is formed in the first elastic layer, a second conductive layer (ML2) is formed in the second elastic layer, and a third conductive layer (ML3) is formed in the third elastic layer. The final elastic layer (FL) covers the third elastic layer (PL3) and the second elastic layer (PL2) which is not the third elastic layer (PL3) above it. The third elastic layer (PL3) includes the crossbar (35).

14. The flexible membrane (30) according to claim 13, characterized in that, The first elastic layer (PL1), the first conductive layer (ML1), and the second elastic layer (PL2) extend along the first region (34A) and the second region (34B) of the flexible membrane (30), and are characterized in that the third elastic layer (PL3) and the third conductive layer (ML3) extend only along the second region (34B), the second conductive layer (ML2) includes a first plurality of conductive traces extending along the first region (34A), partially penetrating the middle portion (30B) of the flexible membrane (30), and connecting with the plurality of conductive traces formed in the third conductive layer (ML3), the second conductive layer (ML2) also includes a second plurality of conductive traces extending along the first region (34A) and the second region (34B), and are formed corresponding to the air gap separating the crossbar (35).

15. The flexible membrane (30) according to claim 14, characterized in that, The flexible membrane includes a first conductive track (33A), which comprises a first portion formed by conductive traces made in the second conductive layer (ML2) and a second portion formed by conductive traces with a greater width made in the third conductive layer (ML3). Each first conductive track (33A) is connected to a first contact pad (31A) made in the central portion (30A) of the flexible membrane (30) and is adapted to contact a miniature contact probe (25) for transmitting a high-frequency power signal, i.e. a signal with a frequency exceeding 1 GHz and a power exceeding 35 dBm. The first conductive track (33A) is made in the crossbar (35).

16. The flexible membrane (30) according to claim 15, characterized in that, The flexible membrane includes a grounding wire made by grounding conductive rails (33G), the grounding conductive rails including a first portion formed by traces made in the second conductive layer (ML2) and a second portion formed by traces made in the first conductive layer (ML1), the first portion and the second portion being interconnected by a first conductive structure (TH1), each grounding conductive rail (33G) being connected to a grounding pad (31G) made in the central portion (30A) of the flexible membrane (30), the grounding conductive rails (33G) being made in the crossbar (35) corresponding to the first conductive rails (33A).

17. The flexible membrane (30) according to claim 14, characterized in that, The flexible membrane includes second conductive tracks (33B) made of conductive traces of the second conductive layer (ML2), the second conductive tracks being arranged to correspond to areas of the second elastic layer (PL2) that do not have crossbars (35) forming the third elastic layer (PL3), each second conductive track (33B) being connected to a second contact pad (31B) made in the central portion (30A) of the flexible membrane (30) and adapted to contact a miniature contact probe (25) for transmitting high-frequency non-power signals, i.e. signals with a frequency exceeding 1 GHz and a power less than 35 dBm.

18. The flexible membrane (30) according to claim 16, characterized in that, The first conductive track (33A) and the ground conductive track (33G) are also connected to a contact structure (31C) formed in the peripheral portion (30C) of the flexible membrane (30).

19. The flexible membrane (30) according to claim 17, characterized in that, The second conductive track (33B) is also connected to a contact structure (31C) formed in the peripheral portion (30C) of the flexible membrane (30).

20. The flexible membrane (30) according to claim 1, characterized in that, The central portion (30A) includes a plurality of strips (31), on which the contact pads (31A, 31B) of the micro contact probe (25) are formed.

21. The flexible membrane (30) according to claim 1, characterized in that, The flexible membrane is made of a dielectric material, and is characterized in that the flexible membrane includes conductive tracks made of a conductive material.

22. The flexible membrane (30) according to claim 21, characterized in that, The dielectric material is polyamide, and the conductive material is copper.

23. A probe card (30) for testing electronic devices, comprising at least one support plate (24), at least one flexible film (30), and a plurality of micro-contact probes (25) associated with a first surface (F1) of the flexible film (30), the micro-contact probes (25) being adapted to abut against a plurality of contact pads (22A) of a device under test (22) and electrically coupled to a plurality of conductive tracks (33A, 33B), the conductive tracks being formed in the flexible film (30) and electrically connected to the contact pads (24A) of the support plate (24), characterized in that, The flexible membrane (30) is manufactured according to any one of the preceding claims.

24. The probe card (30) according to claim 23, characterized in that, The probe card includes a damping structure (27) inserted between the flexible membrane (30) and the support plate (24), the damping structure (27) including a plurality of pre-mounted probes (29) adapted to abut against the flexible membrane (30) at the central portion (30A).

25. The probe card (30) according to claim 23, characterized in that, The probe card includes multiple miniature contact probes (25) with a height of less than 200 μm.

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