Probe head for electronic device test equipment

Abstract

The present invention discloses a probe head (21) comprising: at least one guide (24, 25, 25'); and a plurality of contact probes (22) housed in a plurality of guide holes (24A, 25A, 25'A) formed in the at least one guide (24, 25, 25'), the plurality of contact probes (22) being able to abut against a plurality of contact pads (23A) of a device under test (23), and further comprising at least one housing element (29) surrounding the contact probes (22), wherein the probe head (21) and the contact probes (22) further comprise a heat dissipation structure (30) capable of collecting and dissipating heat generated during a test operation of the electronic device (23), the heat dissipation structure (30) including at least one layer (30A, 30B, 30C, 30D) having a thermal conductivity greater than 100 W / (m·K).

Description

[Technical Field]

[0001] The present invention relates to a probe head configured to be attached to a probe card of an electronic device test apparatus.

[0002] The present invention is particularly, but not exclusively, concerned with probe heads having a plurality of contact probes accommodated in guide holes of at least one guide and configured to abut contact pads of a device under test, and the following description will be made in relation to this field of application for the sole purpose of simplifying the disclosure. [Background technology]

[0003] As is well known, a probe card is essentially a device configured to electrically connect a plurality of contact pads of electronic devices integrated on a microstructure, in particular a wafer, with corresponding channels of a test apparatus.

[0004] This testing on integrated devices is particularly useful for detecting and isolating faulty devices early in the manufacturing process, and so probe cards are typically used for electrical testing of devices integrated on wafers, or chips, before they are cut and assembled into chip encapsulation packages.

[0005] The probe card includes a probe head, which essentially includes a plurality of movable contact elements or contact probes with at least one end or contact tip configured to abut a corresponding plurality of contact pads on a device under test. As used herein, the terms "end" or "tip" refer to the end of a probe, which is not necessarily pointed.

[0006] It is well known that the effectiveness and reliability of a test depends, among other factors, precisely on a good electrical connection between the device under test and the test equipment, and therefore on establishing optimal probe / pad electrical contact.

[0007] Among the types of probe heads used in the technical field considered for testing devices integrated on wafers, so-called vertical probe heads are widespread, in which the contact probes are arranged approximately perpendicular to the plane in which the device under test is located.

[0008] In particular, a vertical probe head comprises a plurality of contact probes held by at least one plate or guide, typically a pair of substantially plate-like, parallel plates or guides. The guides are spaced apart from one another at a predetermined distance to allow free space or clearance for movement and possible deformation of the contact probes during testing, and are provided with appropriate guide holes for slidably accommodating the contact probes. More specifically, the pair of guides comprises an upper guide (upper die) and a lower guide (lower die), each of which is provided with guide holes through which the contact probes slide axially. These contact probes are typically made of wire made of a special alloy with excellent electrical and mechanical properties, also known in the art as needles, and the term "lower" conventionally refers to the guide closest to the device under test.

[0009] A good connection between the contact probes of the probe head and the contact pads of the device under test is ensured by the pressure that the probe head applies to the device itself; during this pressure, the contact probes, which are movable within guide holes formed in the upper and lower guides, are bent within the gap between the two guides and slide within the guide holes that accommodate them.

[0010] Bending of the contact probe within the gap can be promoted and induced by appropriate configuration of the contact probe itself or the guide, in particular by using a pre-deformed contact probe or by appropriately shifting the guide containing the contact probe laterally, the laterally being a direction approximately parallel to the plane of the device under test and the guide.

[0011] Typically, probe heads are used in which the probes are not fixedly attached but are held in an interfaced state with an appropriate main plate or main board, which is then connected to the test equipment. Such probe heads are called "unblocked probe heads." The main board, also called a main board or main PCB (printed circuit board), is usually manufactured using printed circuit technology, which is capable of forming substrates with active areas with contact pads, even if they are large in area. However, since there are significant limitations on the center-to-center distance (pitch) of the contact pads compared to the minimum achievable value, the constraints on the distance between pads are usually relaxed compared to the device under test.

[0012] Relaxation of the distance restrictions between contact pads, particularly the spacing between adjacent pads on the main substrate, is made possible by using an intermediate substrate or space transformer, which has contact pads formed on both sides with different center-to-center distances between one side and the opposite side, and which are appropriately connected by wiring, particularly metal wiring, formed inside the space transformer.

[0013] In this case, the contact probes are configured to abut against a plurality of contact pads formed on a first surface of the space transformer, in particular the surface facing the probe head and therefore the surface facing the device under test, and a good electrical connection between the contact probes and the space transformer, as well as contact with the device under test, is ensured by pressing the probes against the contact pads formed on the space transformer.

[0014] Additionally, the main substrate is typically held in place by a stiffener. This assembly of the probe head, main substrate, intermediate substrate or space transformer, and stiffener forms a probe card, generally shown diagrammatically at 10 in FIG.

[0015] In particular, the probe card 10 in the illustrated example comprises a probe head 1 having a plurality of vertical probes 2 and at least one upper guide 4 and at least one lower guide 5, each having an upper guide hole and a lower guide hole within which the contact probes 2 slide.

[0016] Each contact probe 2 has at least one first end or contact tip 2A that abuts against a contact pad 3A of a device under test 3 integrated on a semiconductor wafer 3', thereby realizing a mechanical and electrical connection between the device under test and a test apparatus (not shown), and the above-mentioned probe head 1 is the end element.

[0017] Furthermore, each contact probe 2 has a second end, referred to in the art as a contact head 2B, and between the contact tip 2A and the contact head 2B is the main body 2C of the contact probe 2, which extends along the longitudinal extension axis of the contact probe 2, which is approximately perpendicular to the face of the device under test and therefore to the guide.

[0018] On the other hand, the contact head 2B is configured to make contact with a plurality of contact pads 6A formed on an intermediate substrate, which functions in particular as a space transformer 6 and is connected to a main plate or main substrate 7, which is further connected to a test device.

[0019] The spatial transformation achieved by the space transformer 6 is particularly related to the center-to-center distance of the contact pads formed on its opposite surface. The space transformer 6 has a plurality of first contact pads 6A formed on its first surface FA facing the probe head 1 and arranged at the positions of the contact heads 2B of the contact pads 2. The contact pads 6A are connected by appropriate metal wiring 6C to a plurality of second contact pads 6B formed on its opposite second surface FB facing the main substrate 7. The second contact pads 6B have a different spatial distribution, in particular a larger center-to-center distance, i.e., a larger pitch, than the first contact pads 6A arranged to substantially correspond to the distribution of the contact pads 3A of the device under test 3. In this way, the space transformer 6 achieves the spatial transformation by separating the contact pads 6B formed on the second surface FB from the contact pads 6A formed on the first surface FA. These are generally referred to as probe-side pads or fine pitch to refer to the plurality of first contact pads 6A, and as PCB-side pads or large pitch to refer to the plurality of second contact pads 6B.

[0020] A good electrical connection between the contact probes 2 and the space transformer 6, as well as contact with the device under test 3, is ensured by pressing the probes against contact pads 6A formed on the first face FA of the space transformer 6.

[0021] As already mentioned, the main substrate 7 is also held in place by stiffeners 8, which make the whole assembly a more rigid and durable structure, making it possible to reduce flatness defects, especially with respect to the space transformer 6, which is often made very thin and therefore has significant flatness issues.

[0022] 1, the probe head 1 further includes an intermediate guide 5′ (medium guide), which is plate-shaped and disposed parallel to the upper guide 4 and the lower guide 5, and is disposed between them, preferably close to the lower guide 5. The intermediate guide 5′ is also provided with a plurality of intermediate guide holes 5′A in which the contact probes 2 are slidably housed.

[0023] Suitably, the upper guide 4, lower guide 5 and intermediate guide 5' are offset from one another in a lateral direction corresponding to the x-axis in the local coordinate system of Figure 1 so as to give them a preferential deflection direction in addition to properly retaining the contact probes 2 within the probe head 1, which is completed by a container (housing) 9 that integrates the guides.

[0024] Therefore, in vertical probe technology, it is important to ensure good connection between the contact probe and the device under test, particularly at its contact tip, as well as good connection with the test equipment, particularly at its contact head, i.e., space transformer, which plays a very important role, especially in the testing operation of integrated circuits manufactured according to modern integration technology, where the contact pads on the device under test are arranged very closely and are extremely small in size, and which are poorly compatible with PCB technology from which the main substrate of the probe card is formed.

[0025] The relative positioning of the components that make up the probe card is a crucial parameter for the proper operation of the card itself, and the multiple techniques used to manufacture these components create flatness issues and complicate the overall card configuration, particularly with regard to the positioning of the intermediate substrate or space transformer relative to the main substrate. Even with the presence of stiffeners to make the whole more rigid and durable, it is generally difficult to sufficiently eliminate flatness defects in the space transformer and ensure proper and complete contact with the main substrate.

[0026] This situation is further complicated by the operating temperature of the probe card itself, especially when testing is performed at extreme temperatures. In such cases, the thermal expansion of the components of the probe card can affect their behavior due to the different thermal expansion coefficients of the different materials that make up those components. In fact, the components of the probe card are typically fastened together with screws, but this fastening can constrain the different substrates, especially during testing at high temperatures, which can cause warping and lead to failure of the entire probe card, or in extreme cases, the loss of contact between the contact probes of the probe head and the contact pads of the device under test.

[0027] This problem is particularly pronounced in the case of large probe cards, such as those used for testing memory devices such as DRAMs, where the uncontrolled thermal expansion of components in these types of probe cards causes significant problems in the testing process.

[0028] Furthermore, during testing operations, the contact probes heat up due to the multiple signals passing through them, which increases the heat inside the probe head, especially in probe heads with a large number of contact probes.

[0029] The technical problem of the present invention is to provide a probe head having functional and structural features that make it possible to overcome the limitations and drawbacks still present in probe heads constructed based on known technology, and that facilitates the removal of heat generated during test operations and suppresses the increase in the operating temperature of the probe head itself and the probe card that includes it. Summary of the Invention

[0030] The solution concept underlying the present invention is to provide the probe head with a structure that dissipates heat generated by the test operation, preferably in the air, thereby suppressing an increase in the operating temperature of the probe head, thereby avoiding deformation of the probe head itself and the probe card containing it and preventing failure.

[0031] Based on this solution idea, the technical problem is solved by a probe head including at least one guide and a plurality of contact probes housed in a plurality of guide holes formed in the at least one guide, the plurality of contact probes being able to abut against a plurality of contact pads of a device under test, and further including at least one housing element surrounding the contact probes. Preferably, the probe head further includes a heat dissipation structure capable of collecting and dissipating heat generated by the probe head and the contact probes housed therein during a test operation of the electronic device. Furthermore, the heat dissipation structure includes at least one layer having a thermal conductivity greater than 100 W / (m·K).

[0032] More particularly, the present invention includes the following additional and optional features which may be taken alone or in combination as appropriate:

[0033] According to one aspect of the present invention, the layer can be selected from a coating layer arranged along at least one surface of the at least one guide, a side coating layer of the housing element, a covering layer of the at least one guide including at least one side portion extending along a side wall of the at least one guide and at least one flat portion (30CL) extending along another surface of the at least one guide perpendicular to the side wall, and a full covering layer of the housing element.

[0034] According to another aspect of the invention, the layer may include at least one portion in contact with air.

[0035] According to yet another aspect of the present invention, the layer may be formed from a material having a thermal conductivity greater than 500 W / (m·K).

[0036] Also, the layer is 10 4 greater than Ω·m, preferably 10 16 It may be formed from a material having an electrical resistivity greater than Ω·m.

[0037] More particularly, according to another aspect of the invention, the layer may be formed from a material selected from silicon nitride, silicon carbide and CVD-D (chemical vapor deposition diamond), preferably from CVD-D.

[0038] According to another aspect of the present invention, the layer may be formed on a surface of the at least one guide, preferably outside an active zone of the at least one guide provided with a guide hole for accommodating a contact probe.

[0039] According to a further aspect of the invention, the layer may have a thickness of at least 50 micrometers and at most 500 micrometers, preferably 150 micrometers.

[0040] Furthermore, the layer may also be formed on a surface corresponding to the active zone of at least one guide in which a guide hole for accommodating the contact probe is provided. In this case, the probe head may include an electrical decoupling structure between the contact probe and the layer. Preferably, the electrical decoupling structure may be selected from a dielectric coating covering a portion of the contact probe that contacts the layer, and a clipping region in which no layer is provided along an edge of the guide hole for accommodating the contact probe.

[0041] According to another aspect of the invention, the heat dissipation structure may further comprise an external heat sink thermally connected to the layer.

[0042] More particularly, the heat sink may surround the periphery of the probe head.

[0043] According to another aspect of the invention, the heat dissipation structure may further comprise a forced air supply structure configured to introduce air into the probe head. Preferably, the air may be introduced towards the layer.

[0044] Finally, according to yet another aspect of the present invention, the forced air supply structure may generate a forced air flow in a portion of the layer outside the active zone of at least one guide, where a guide hole for accommodating a contact probe is provided.

[0045] The technical problem is also solved by a probe card configured to be mounted in an electronic device test apparatus, the probe card comprising at least one probe head configured as described above.

[0046] According to another aspect of the invention, the probe card may further comprise a heat dissipation device comprising at least one active or passive thermal pipe in thermal contact with the space transformer of the probe card to increase the dissipation of heat generated within the probe head during operation of the probe head.

[0047] The features and advantages of a probe head and a probe card according to the invention will become apparent from the following description of embodiments thereof, given by way of example and not limitation, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0048] [Figure 1] FIG. 1 is a schematic cross-sectional view of a probe card with a vertical probe head according to the prior art. [Figure 2A] FIG. 2A is a schematic cross-sectional view of a probe card with a vertical probe head according to one embodiment of the present invention. [Figure 2B] FIG. 2B is a schematic cross-sectional view of a probe card with a vertical probe head according to another embodiment of the present invention. [Figure 2C]FIG. 2C is a schematic cross-sectional view of a probe card with a vertical probe head according to another embodiment of the present invention. [Figure 2D] FIG. 2D is a schematic cross-sectional view of a probe card with a vertical probe head according to another embodiment of the present invention. [Figure 3A] FIG. 3A is a cross-sectional view of a probe card with a vertical probe head according to yet another embodiment of the present invention. [Figure 3B] FIG. 3B is a cross-sectional view of a probe card with a vertical probe head according to yet another embodiment of the present invention. [Figure 4A] FIG. 4A is a cross-sectional view of a probe card with a vertical probe head according to yet another embodiment of the present invention. [Figure 4B] FIG. 4B is a plan view of a probe card with a vertical probe head according to yet another embodiment of the present invention. [Figure 4C] FIG. 4C is a side view of a probe card with a vertical probe head according to yet another embodiment of the present invention. [Figure 5A] FIG. 5A is a cross-sectional view of a probe card with a vertical probe head according to yet another embodiment of the present invention. [Figure 5B] FIG. 5B is a plan view of a probe card with a vertical probe head according to yet another embodiment of the present invention. [Figure 5C] FIG. 5C is a side view of a probe card with a vertical probe head according to yet another embodiment of the present invention. [Figure 6] FIG. 6 is a cross-sectional view of a probe card with a vertical probe head according to yet another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0049] Referring to these figures, and particularly to FIG. 2A, the numeral 20 generally designates a probe card constructed in accordance with the present invention, particularly integrated on a wafer, including at least one probe head with a plurality of contact probes for testing electronic devices.

[0050] It should be noted that the figures are schematic representations of probe cards and are not drawn to scale, but rather to highlight important features of the invention.

[0051] Furthermore, the multiple aspects of the present invention illustrated in the drawings can of course be combined with one another and can be interchanged from one embodiment to another.

[0052] Furthermore, structurally and functionally identical components are designated with the same alphanumeric reference numerals in the figures and in the embodiments described below.

[0053] In the following description, relative terms such as "on," "under," "upward," "downward," "upper," and "lower" are used based on the illustration of the solutions shown in the figures and are intended solely for ease of description.

[0054] Finally, statements about specific shapes (circular, rectangular) or arrangements of components (parallel, orthogonal, tangent) and the term "substantially" always relate to physical components and not to geometric abstractions, and therefore always take into account the tolerances introduced by the transition from the mathematical / geometric ideal world to the real world.

[0055] 2A, the probe card 20 includes a probe head 21 that houses a plurality of contact probes 22. The illustrated probe head 21 is an unblocked vertical probe head that includes at least one upper plate or guide 24 and one lower plate or guide 25, each of which defines an upper guide hole 24A and a lower guide hole 25A through which the contact probes 22 slide.

[0056] As is common in the technical field of the present invention, the term "lower guide" means the guide positioned closest to the device under test, and the term "upper guide" means the guide positioned closest to the test equipment connected to the probe card 20 when the probe card 20, and therefore the probe head 21, is mounted as an end element of the test equipment and in an operational state.

[0057] The probe head 21 also includes a receiving element or housing 29 configured to enclose the contact probe 22 and to unite the upper guide 24 and the lower guide 25 .

[0058] 2A, the probe head 21 further includes an intermediate plate or guide 25', which is arranged parallel to the upper guide 24 and the lower guide 25, particularly close to the lower guide 25, and the intermediate guide 25' also includes an intermediate guide hole 25'A through which the contact probe 22 slides. This three-guide embodiment is merely exemplary, and the probe head 21 may optionally include one guide or two or more guides.

[0059] Each contact probe 22 has at least a first end, i.e., a contact tip 22A, configured to abut against a contact pad 23A integrated on the device under test 23, in particular a semiconductor wafer 23', so as to establish the desired contact, in particular electrical contact, between the contact probe 22 of the probe head 21 and the contact pad 23A of the device under test 23.

[0060] Each contact probe 22 further includes a second end, i.e., a contact head 22B, for making contact with a main plate 27 or a main PCB connected to a test apparatus (not shown). Between the contact head 22B and the contact tip 22A, a rod-shaped probe body 22C is arranged along the longitudinal extension direction of the contact probe 22, particularly perpendicular to the plane π of the semiconductor wafer 23′ on which the devices under test 23 are integrated, i.e., along the z-axis of the local coordinate system in FIG. 2A.

[0061] The upper guide 24, the lower guide 25, and the middle guide 25' are plate-like elements arranged parallel to one another and parallel to the plane π of the semiconductor wafer 23', and therefore the device under test 23. Suitably, as in the prior art, the upper guide 24, the lower guide 25, and the middle guide 25' are shifted relative to one another in a direction tangent to the plane π of the semiconductor wafer 23', i.e., the x-axis direction in the local coordinate system of FIG. 2A, so as to impart a preferential bending direction to the contact probe 22. Due to this shifting of the guides, the guide holes formed therein and accommodating identical contact probes are no longer aligned relative to one another in a direction perpendicular to the plane π of the semiconductor wafer 23', i.e., the z-axis direction in the local coordinate system of FIG. 2A, which forces the probe body 22C of the contact probe 22 to bend and determines the preferential bending direction mentioned above.

[0062] The probe card 20 further comprises an intermediate substrate arranged between the probe head 21 and the main substrate 27 and configured to perform spatial transformations, particularly relating to the distribution of contact pads on both sides thereof, and for the reasons mentioned above is denoted as space transformer 26.

[0063] The space transformer 26 has a first surface FA facing the probe head 21 (in operation, i.e., when the space transformer 26 is inserted into the probe card 20 equipped with the probe head 21 and attached as an end element of a test apparatus), and a plurality of first contact pads, designated as probe-side pads 26A, are formed on the first surface FA, onto which the contact heads 22B of the contact probes 22 abut. The space transformer 26 also has a second surface FB, located opposite the first surface FA and facing the main board 27 for connection to the test apparatus (in operation), and which has a plurality of second contact pads, designated as tester-side pads 26B, connected to the plurality of probe-side pads 26A by respective electrical connections 26C formed inside the space transformer 26. Suitably, the tester-side pads 26B may be larger in size and more widely spaced apart from each other relative to the probe-side pads 26A, thereby allowing the space transformer 26 to achieve the desired space transformation.

[0064] Finally, the probe card 20 includes a stiffener 28 associated with the main substrate 27 and configured to improve the flatness of the main substrate 27 and prevent warping of the substrate, particularly when temperatures rise during operation of the probe card 20, i.e., during testing operations.

[0065] Advantageously, according to the present invention, the probe head 21 comprises at least one heat dissipation structure 30, which is capable of collecting and dissipating, preferably by dissipation into the air, heat generated by the device under test 23 during test operations, as well as heat generated by the contact probes 22 contained within the probe head 21.

[0066] In particular, the heat dissipation structure 30 collects heat generated, for example, by friction of the contact probes 22 sliding within at least one guide hole of a guide included in the probe head 21, or by signals such as so-called power signals that traverse these contact probes 22 and may cause the temperature to rise, and dissipates it into the ambient environment of the probe card 20 including the probe head 21, preferably into the air.

[0067] In a preferred embodiment, the heat dissipating structure 30 comprises at least one portion in contact with air, in particular the environment surrounding the probe head 21 .

[0068] 2A, the heat dissipation structure 30 comprises a coating layer 30A formed from a material with high thermal conductivity λ, i.e., a material with high thermal conductivity λ greater than 100 W / (m·K), preferably greater than 500 W / (m·K). In particular, this high thermal conductivity λ allows optimal collection and subsequent dissipation of the heat generated in the probe head 21 during test operation, thus limiting the operating temperature rise of said head and minimizing the risk of deformation, in particular bending, of the elements constituting said probe head 21 and the probe card 20 containing it.

[0069] In other words, the coating layer 30A made of high thermal conductivity material λ that forms the heat dissipation structure 30 ensures proper operation of the probe head 21 and the entire probe card 20 even when heat is generated within the probe head 21 during test operations.

[0070] Preferably, the coating layer 30A is formed so as to be in at least partial contact with the environment surrounding the probe head 21 in an operating state.

[0071] Preferably, the high thermal conductivity material λ constituting the coating layer 30A has a high electrical resistivity ρ, i.e., 10 4 Greater than Ω·m, preferably 10 16The coating layer 30A forming the heat dissipation structure 30 has an electrical resistivity ρ greater than Ω·m. As a result, the presence of the coating layer 30A does not affect the electrical behavior of the probe head 21, and therefore the electrical behavior of the probe card 20, and in particular does not interfere with the operation of the contact probes 22.

[0072] In preferred embodiments, coating layer 30A is comprised of silicon nitride, silicon carbide and CVD-D (chemical vapor deposited diamond), more preferably CVD-D.

[0073] The preferred materials are particularly capable of forming structures having reduced thicknesses of less than 500 micrometers, more preferably less than 250 micrometers, while maintaining high heat dissipation properties of the resulting diffusion structure.

[0074] 2A, the coating layer 30A is formed on a surface of at least one guide, in particular the lower guide 25, preferably on a first surface F1 facing the device under test 23 when the probe head 21 is in an operational state, which is also referred to as the lower surface F1 according to the local coordinate system in the figure and the terminology commonly used in the art. This allows the entire coating layer 30A to be exposed to the environment surrounding the probe head 21, facilitating the dissipation of heat generated therein into the air.

[0075] The coating layer 30A has a thickness H1 in the direction perpendicular to the z axis of the local coordinate system in the figure, i.e., the extension plane π of the device under test 23 and the guide, and the thickness H1 is not less than 50 micrometers and not more than 500 micrometers, preferably 150 micrometers.

[0076] The coating layer 30A is preferably arranged outside the active zone ZA where the guide holes for accommodating the contact probes 22 are arranged in each guide, particularly in the peripheral area where such guide holes are not present, such as the area where the lower guide holes 25A are not provided in the lower guide 25 in the example of Fig. 2A. In this way, even if the coating layer 30A is made of a conductive material, it does not interfere with the normal operation of the contact probes 22.

[0077] Furthermore, the coating layer 30A forming the heat dissipation structure 30 can be formed to completely cover the entire surface of the lower guide 25 shown in Figure 2B, for example, and the coating layer 30A can also extend to the active zone ZA in which a guide hole for accommodating the contact probe 22 is formed.

[0078] If the coating layer 30A covering the entire guide is made of a material that is slightly conductive, it is possible to provide an appropriate electrical decoupling structure between the contact probes 22 and the conductive coating layer 30A, such as a dielectric coating that covers the portions of the contact probes 22 that may come into contact with the coating layer 30A of the heat dissipating structure 30, thereby ensuring proper operation of the entire probe head 21. Alternatively, a so-called clipping region of the guide holes may be provided, i.e., the coating layer 30A is formed so as not to reach the edges of the guide holes that accommodate the contact probes 22, particularly the lower guide holes 25A of the lower guide 25 on which the coating layer 30A is formed, and the guide holes have areas around their edges free of the coating layer 30A to avoid any electrical interference with the contact probes 22.

[0079] In the embodiment shown in FIG. 2C , the coating layer 30A can also be provided on another surface of the guide, for example, on the second surface F2 (also referred to as the upper surface F2 in the local coordinate system of FIG. 2C ) of the lower guide 25, which faces the test device during normal operation of the probe head 21. In this case, the coating layer 30A can extend only outside the active zone ZA, as shown in FIG. 2C , or it can completely cover the relevant guide, in particular the lower guide 25, with an insulating coating for the probe at least in the portion received in the lower guide hole 25A or with a clipping region around the guide hole. Preferably, the coating layer 30A extends to the outer side PL of the probe head 21 and is formed to have at least one side 30AH in contact with the air in the environment surrounding the probe head 21. Furthermore, the coating layer 30A preferably extends outside the housing element 29 on the lower guide 25 to the active zone ZA, in this case having at least one portion 30A1 exposed to the air inside the probe head 21.

[0080] Although not shown, the heat dissipating structure 30 can be configured to include multiple coating layers 30A formed on one or more surfaces of one or more of the guides of the probe head 21 (e.g., the upper guide 24, the lower guide 25, and the middle guide 25′). Thus, the heat dissipating structure 30 can include one to six coating layers 30A corresponding to one or more of the three guides. Generally, the probe head 21 can be configured with any number of guides greater than two, which may or may not have coating layers 30A on both or one side of the guide. Furthermore, the coating layers 30A may extend only outside the active zone of each guide, or may extend into the active zone to completely cover the entire guide. In this case, if one or more coating layers 30A are formed of a conductive material, additional means for clipping the guide holes or for electrical decoupling from the contact probes 22 may be used.

[0081] Preferably, in a preferred embodiment, all layers of the heat dissipation structure 30 are formed to have at least one portion exposed to air within the probe head 21 or in the environment surrounding the probe head 21, thereby ensuring that heat generated within the probe head 21 is collected and then dissipated into the air.

[0082] According to another embodiment, the heat dissipating structure 30 may comprise a covering layer 30C on at least one of the guides included in the probe head 21, the covering layer 30C having a side portion 30CH extending along the side wall FL of the guide, i.e., along a wall perpendicular to the extension plane π of the device under test 23, and this side portion is exposed to air. Furthermore, the covering layer 30C has a planar portion 30CL extending along at least one of the surfaces of the guide parallel to the plane π, and preferably extending along both surfaces, i.e., a first or bottom surface F1 and an opposite second or top surface F2 in the local coordinate system, as shown in FIG. 2D . In a preferred embodiment, the covering layer 30C includes a portion 30C1 on the top surface F2 of the guide that is exposed to air inside the probe head 21.

[0083] In the example of Figure 2D, the covering layer 30C extends only outside the active zone ZA of the lower guide 25, but if the covering layer 20C is made of a conductive material, it is possible to form the covering layer so as to completely cover the entire guide by using insulating means for the probe.

[0084] In another embodiment, the heat dissipation structure 30 may be associated with a housing element or housing 29 of the probe head 21 .

[0085] In this case, the heat dissipation structure 30 comprises one side coating layer 30B provided on the outer side PL of the probe head 21, in particular on the side wall of the housing element 29 opposite the contact probes 22, i.e. on the outer side wall of the housing element 29, as shown schematically in Figure 3A. In this way, the side coating layer 30B forming the heat dissipation structure 30 is exposed to the air of the environment surrounding the probe head 21.

[0086] The side coating layer 30B is made of a high thermal conductivity material λ having a thermal conductivity of more than 100 W / (m·K), preferably more than 500 W / (m·K), and more preferably an electrical resistivity ρ of 10 4 Greater than Ω·m, preferably 10 16 It is made from silicon nitride, silicon carbide and CVD-D (chemical vapor deposition diamond) with a high resistivity of greater than Ω·m.

[0087] The side coating layer 30B has a thickness H2 in the direction parallel to the x-axis of the local coordinate system in FIG. 3A, i.e., the extension plane π of the device under test 23 and the guide, and the thickness H2 is not less than 50 micrometers and not more than 1000 micrometers, preferably 500 micrometers.

[0088] According to another embodiment, as schematically shown in FIG. 3B, the heat dissipating structure 30 includes at least one full covering layer 30D covering the entire housing element 29, specifically a first covering layer 30D1 for a first portion 29A of the housing element 29 arranged between the intermediate guide 25′ and the lower guide 25, and a second covering layer 30D2 for a second portion 29B of the housing element 29 arranged between the intermediate guide 25′ and the upper guide 24, the covering layers 30D1 and 30D2 extending along the entire wall surfaces of each portion of the housing element 29 to completely cover them, so that the outer side PL is exposed to the air in the environment surrounding the probe head 21 and also exposed to the air inside the probe head 21 at the inner side PL1 of the housing element 29.

[0089] In another advantageous embodiment, as shown in Fig. 4A based on the embodiment of Fig. 2A, the heat dissipation structure 30 may include an external heat sink 32, i.e., the heat dissipation structure 30 has a coating layer 30A disposed on the lower surface F1 of the lower guide 25. In this case, it is noted that the coating layer 30A essentially serves to collect heat generated inside the probe head 21, while the heat sink 32 mainly serves to dissipate the heat, preferably into the air. It is clear that the external heat sink 32 can also be used in the probe head 21 configured according to the embodiment of Figs. 2B to 2D.

[0090] Preferably, as shown in the plan and side views of Figures 4B and 4C, the heat sink 32 may be comb-shaped, i.e., have multiple wings that can increase heat dissipation, and may be positioned below the probe head 21, for example at its periphery, such as at the periphery of the active zone of the lower guide 25 that is provided with the coating layer 30A.

[0091] In this way, the heat sink 32 can be made of metal such as aluminum or copper, i.e. materials which are low cost and ensure good heat dissipation, and which can be used to advantage thanks to the comb-shaped shape of the heat sink 32 .

[0092] In this way, the heat sink 32 is very effective at dissipating heat generated within the probe head 21 and collected by the coating layer 30A, particularly into the air in the environment surrounding the probe head 21.

[0093] 5A-5D, a probe card 20 includes a probe head 21 according to the embodiment of FIG. 3B, i.e., a probe head 21 having a heat dissipation structure 30 associated with a housing element 29 and including a full covering layer 30D including covering layers 30D1 and 30D2 for a first portion 29A and a second portion 29B of the housing element 29. The heat dissipation structure 30 further includes a heat sink 32 thermally coupled to the full covering layer 30D. Of course, the heat sink 32 associated with the housing element 29 can also be used in a probe head 21 configured according to the embodiment of FIG. 3A.

[0094] In particular, the heat sink 32 can be formed to surround the periphery of the housing element 29 and to be in thermal contact with both portions thereof and thus with both coating layers 30D1 and 30D2.

[0095] 6 based on the embodiment of FIG. 2C, the heat dissipation structure 30 of the probe head 21 further comprises a forced air supply structure 35 configured to introduce air into the probe head 21, in particular to the position of the coating layer 30A of the heat dissipation structure 30, thereby improving the dissipation of heat generated in the probe head 21 and collected by the coating layer 30A into the air already inside the probe head 21. Even in this case, the forced air supply structure 35 can be used in the probe head 21 configured according to each embodiment of FIGS. 2B to 2D.

[0096] Preferably, the forced air supply structure 35 generates a forced air flow FL inside the probe head 21 .

[0097] In particular, the forced air flow FL is directed to the portion 30A1 of the coating layer 30A that is exposed to air inside the probe head 21, but does not extend to the active zone ZA, so as not to interfere with the operation of the contact probe 22.

[0098] In another embodiment not shown, the probe card 20 including the probe head 21 may further include an additional heat dissipation device having at least one active or passive thermal pipe in thermal contact with the space transformer 26 to assist in dissipating heat generated internally during operation of the probe head.

[0099] In conclusion, the present invention advantageously provides a probe head with a structure that dissipates heat that may be generated during testing operations, particularly with power signals.

[0100] Thus, a probe card equipped with a probe head according to the present invention is suitable for applications in which the entire probe card is significantly heated by test operations, and thanks to the heat dissipation provided by the heat dissipation structure associated with the probe head, deformation of the elements constituting the card is avoided, thereby ensuring proper operation of the probe card while preventing deformation that could affect the accurate results of the test operations.

[0101] Heat dissipation is further improved if the heat dissipation structure is associated with an external heat sink or forced air supply structure.

[0102] Of course, those skilled in the art can make numerous modifications and variations to the above-described probe head and probe card to meet their own particular requirements, all of which fall within the scope of protection of the present invention as defined by the following claims.

Claims

1. A probe head (21) comprising: at least one guide (24, 25, 25'); and a plurality of contact probes (22) housed in a plurality of guide holes (24A, 25A, 25'A) formed in the at least one guide (24, 25, 25'), the plurality of contact probes (22) being able to abut against a plurality of contact pads (23A) of a device under test (23), and further comprising at least one housing element (29) surrounding the contact probes (22), The probe head (21) further comprises a heat dissipation structure (30) capable of collecting and dissipating heat generated in the probe head (21) and the contact probes (22) during a test operation; The heat dissipation structure (30) is characterized in that it includes at least one layer (30A, 30B, 30C, 30D) having a thermal conductivity greater than 100 W / (m·K). Probe head (21).

2. The layers (30A, 30B, 30C, 30D) a coating layer (30A) disposed along at least one face (F1, F2) of said at least one guide (24, 25, 25'); a lateral coating layer (30B) of said housing element (29); a covering layer (30C) of the at least one guide (24, 25, 25'), comprising at least one side portion (30CH) extending along the side wall (FL) of the at least one guide (24, 25, 25') and at least one flat portion (30CL) extending along another plane (F1, F2) of the at least one guide (24, 25, 25') perpendicular to the side wall (FL); and A full covering layer (30D) of the housing element (29) A probe head (21) characterized in that it is selected from:

3. 2. The probe head (21) of claim 1, wherein the layer (30A, 30B, 30C, 30D) has at least one portion in contact with air.

4. 2. The probe head (21) of claim 1, wherein the layers (30A, 30B, 30C, 30D) are formed from a material having a thermal conductivity greater than 500 W / (m·K).

5. The layers (30A, 30B, 30C, 30D) are 10 4 greater than Ω·m, preferably 10 16 2. The probe head (21) of claim 1, wherein the probe head is made of a material having an electrical resistivity greater than Ω·m.

6. 2. The probe head (21) of claim 1, wherein the layers (30A, 30B, 30C, 30D) are formed from a material selected from silicon nitride, silicon carbide and CVD-D (chemical vapor deposition diamond), preferably from CVD-D.

7. 2. The probe head (21) according to claim 1, characterized in that the layers (30A, 30B, 30C, 30D) are formed corresponding to a surface of the at least one guide (24, 25, 25') outside an active zone (ZA) of the at least one guide (24, 25, 25'), in which a guide hole (24A, 25A, 25'A) for accommodating the contact probe (22) is provided.

8. Probe head (21) according to claim 1, characterized in that said layer (30A, 30B, 30C, 30D) has a thickness (H1) of between 50 micrometers and 500 micrometers, preferably 150 micrometers.

9. the layers (30A, 30B, 30C, 30D) are formed corresponding to a surface of the at least one guide (24, 25, 25'), and are also formed corresponding to an active zone (ZA) of the at least one guide (24, 25, 25'), in which a guide hole (24A, 25A, 25'A) for accommodating the contact probe (22) is provided; Between the contact probe (22) and the layer (30A, 30B, 30C, 30D), a dielectric coating covering the portion of the contact probe (22) that contacts the layer (30A, 30B, 30C, 30D); and A clipping area in which the layers (30A, 30B, 30C, 30D) are not provided along the edges of the guide holes (24A, 25A, 25'A) for accommodating the contact probes (22).

2. The probe head (21) of claim 1, further comprising an electrical decoupling structure selected from the group consisting of:

10. The probe head (21) of claim 1, wherein the heat dissipation structure (30) further comprises an external heat sink (32) thermally connected to the layers (30A, 30B, 30C, 30D).

11. The probe head (21) of claim 10, wherein the heat sink (32) surrounds the periphery of the probe head (21).

12. The probe head (21) of claim 1, wherein the heat dissipation structure (30) further comprises a forced air supply structure (35) configured to introduce air into the probe head (21).

13. 13. The probe head (21) according to claim 12, characterized in that the forced air supply structure (35) generates a forced air flow (FL) corresponding to the layer (30A, 30B, 30C, 30D).

14. 13. The probe head (21) according to claim 12, characterized in that the forced air supply structure (35) generates a forced air flow (FL) corresponding to a portion of the layer (30A, 30B, 30C, 30D) outside an active zone (ZA) of the at least one guide (24, 25, 25') in which a guide hole (24A, 25A, 25'A) for accommodating the contact probe (22) is provided.

15. A probe card (20) configured to be mounted in an electronic device testing apparatus, the probe card (20) comprising at least one probe head (21) according to any one of claims 1 to 14.

16. The probe card (20) of claim 15 further comprising a heat dissipation device having at least one active or passive thermal pipe in thermal contact with a space transformer (26) of the probe card to increase the dissipation of heat generated inside the probe head (21) during operation of the probe head (21).

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