Probe head with improved heat dissipation capability

Abstract

A probe head (100) for testing a device under test (DUT) is disclosed, the probe head (100) having a plurality of contact probes (10) with a body (10') extended between a first end portion (10a) and a second end portion (10b), said end portions being adapted to contact respective pads (DUTa, 25a), at least one guide (20) provided with guide holes (20h) for housing the contact probes (10), a housing (30) configured to support the at least one guide, a first portion (L1), which is a heat dissipation structure and is configured to collect and dissipate heat produced by said probe head during the test, and a second portion (L2), which is made of a conductive material and is in contact with the first portion (L1). A related measuring system is also disclosed.

Description

[0001] Title: Probe head with improved heat dissipation capability

[0002] DESCRIPTION

[0003] Field of application

[0004] The present invention relates to a probe head adapted to perform the testing of electronic devices integrated on a semiconductor wafer. The following description is made with reference to this field of application with the only purpose of simplifying the exposition thereof.

[0005] Prior art

[0006] As it is well known, a probe head is essentially a device adapted to electrically connect a plurality of contact pads of a microstructure, in particular an electronic device integrated on a semiconductor wafer, with corresponding channels of a testing apparatus which performs the functionality testing thereof.

[0007] The test performed on integrated circuits is useful to detect and isolate defective circuits as early as in the production phase. Usually, the probe heads are thus used for testing the circuits that are integrated on wafers before cutting and assembling them inside a chip containment package.

[0008] A probe head essentially comprises a plurality of movable contact probes held by at least one pair of supports or guides which are substantially plate-like and parallel to each other. These plate-like supports are provided with suitable guide holes and are arranged at a distance from each other so as to create a free area or air gap for the movement and the possible deformation of the contact probes, which are usually formed by wires of special alloys with good electrical and mechanical properties.

[0009] The contact probes generally extend between a first end portion, intended to contact the pads of the device under test, and a second end portion, intended to contact a space transformer or a printed circuit board (PCB) associated with the probe head.

[0010] The correct operation of a probe head is basically linked to two parameters: the vertical movement (or overtravel) of the contact probes and the horizontal movement (or scrub) of the contact tips of these probes on the pads during the contact with the device under test. All these features are to be evaluated and calibrated in the manufacturing step of a probe head, the good electrical connection between the contact probes and the device under test should always be ensured.

[0011] In the probe heads of the above type, in the case of high- temperature tests, the thermal expansions of the components of the probe head can affect the correct behaviour thereof, because of the different coefficients of thermal expansion of the different materials that form said components. In fact, it is common to fasten the elements that make up a probe head to each other by means of screws, which, in particular during a testing at high temperatures, apply to the different plates a constraint that tends to cause a warping thereof, with subsequent malfunctioning of the probe head as a whole.

[0012] Furthermore, during the testing operations, a large amount of heat is generated by the components of the probe head itself; for example, the contact probes can heat up due to the passage of the different signals, increasing the heat inside the probe head, in particular in the case of a probe head provided with a very large number of contact probes. Similarly, the abutment of said contact probes on the pads and the friction with the walls of the guide holes produce undesirable heat which builds up, and therefore there is the need to limit the heating of the probe head as a whole.

[0013] The technical problem of the present invention is to devise a probe head having such structural and functional features as to allow the limitations and drawbacks still affecting known solutions to be overcome, in particular which is able to effectively dissipate the heat during the operation thereof.

[0014] Summary of the invention

[0015] The solution idea underlying the present invention is to design and create a probe head in which there is a portion having a high thermal conductivity, for example a layer formed on a face of a guide thereof, and also a conductive layer overlapping said portion having a high thermal conductivity with the purpose of increasing heat dissipation.

[0016] Based on this solution idea, the above technical problem is solved by a probe head for testing a device under test, said probe head comprising a plurality of contact probes comprising a body extended between a first end portion and a second and opposite end portion, said end portions being adapted to contact respective pads, at least one guide comprising guide holes for housing the contact probes, a housing configured to support the at least one guide, at least one first portion, which acts as a heat dissipation structure and is configured to collect and dissipate heat produced by said probe head during the test, and at least one second portion, which is made of a conductive material and is in contact with the first portion.

[0017] More particularly, the invention comprises the following additional and optional features, taken individually or in combination if necessary. These features are found for example in the dependent claims.

[0018] According to an aspect of the present invention, the first portion can be made of a high thermal conductivity material selected from diamond, in particular CVD-D (Chemical Vapor Deposition-Diamond), silicon carbide, or a silver-diamond compound with a diamond percentage between 50 and 99%, preferably diamond.

[0019] According to an aspect of the present invention, the material of the second portion can be gold.

[0020] According to an aspect of the present invention, the second portion can be in contact with the housing.

[0021] According to an aspect of the present invention, the housing can be made of a conductive material.

[0022] According to an aspect of the present invention, the first portion can extend at least into an active zone of said at least one guide where there are the guide holes for housing the contact probes.

[0023] According to an aspect of the present invention, the first portion can also comprise an external part extended outside said active zone.

[0024] According to an aspect of the present invention, the second portion can comprise a part extended in the active zone and an external part extended outside said active zone, for example separated from the part in the active zone (although this is not strictly necessary) . According to an aspect of the present invention, the second portion can comprise only an external part extended outside the active zone (for example in connection with a given part of the first portion) .

[0025] According to an aspect of the present invention, the external part of said second portion can be arranged on said corresponding external part of said first portion.

[0026] According to an aspect of the present invention, the second portion can be in the form of at least one conductive portion that includes at least one group of holes of the guide holes and is adapted to contact and short-circuit a corresponding group of contact probes housed in said group of holes and intended to carry a given type of signal, thereby defining at least one conductive domain.

[0027] According to an aspect of the present invention, the second portion can be structured as a plurality of second portions electrically insulated from each other (for example by non-conductive zones on a face of the guide).

[0028] According to an aspect of the present invention, at least two second portions (generally, some second portions) of said plurality of second portions can correspond to different conductive domains, each of said conductive domains being configured to short-circuit contact probes adapted to carry a different respective signal, for example different power domains, and / or ground domains, and / or domains adapted to carry operative signals, in particular power domains.

[0029] According to an aspect of the present invention, said plurality of second portions can comprise at least two second portions in the active zone and at least one second portion outside said active zone and corresponding to said external part.

[0030] According to an aspect of the present invention, the probe head can also comprise at least one second portion of said plurality of second portions which is electrically insulated from the contact probes (this portion can correspond to the above-mentioned portion outside the active zone and corresponding to said external part) . According to an aspect of the present invention, said electrically insulated second portion can be in contact with the housing.

[0031] According to an aspect of the present invention, the guide can be a lower guide, the probe head comprising at least one further guide which is an upper guide separated from the lower guide and provided with respective guide holes, the lower guide being the guide which is closest to the device under test, wherein the housing is arranged between said lower guide and said further upper guide.

[0032] According to an aspect of the present invention, the probe head can comprise a third portion, which is made of the same material as the first portion and is in contact with the further upper guide, and a fourth portion, which is made of the same conductive material as the second portion and is in contact with said third portion.

[0033] According to an aspect of the present invention, the first portion can be a layer having a thickness between 10 gm and 100 gm, and the second portion can be a layer having a thickness between 1 gm and 10 gm.

[0034] According to an aspect of the present invention, the first portion can be a layer formed on at least part of a face of the guide and the second portion can be a layer arranged on the first portion, so that said first portion is arranged between said guide and said second portion.

[0035] According to an aspect of the present invention, the first portion can at least partially surround the guide, said first portion comprising at least one side part extending along a side wall of said at least one guide, a planar part extending along a face of the guide, and a further planar part extending along a further face of the guide, said faces being substantially orthogonal to said side wall.

[0036] According to an aspect of the present invention, the first portion can be at least an integral part of the guide (i.e. a portion of the guide itself), which is thus at least partially a heat dissipation structure (in particular made of the above-mentioned high thermal conductivity material), wherein the second portion made of said conductive material is a layer in contact with the guide, for example arranged on a face of said guide.

[0037] According to an aspect of the present invention, the first portion can be the entire guide.

[0038] According to an aspect of the present invention, the first portion can be formed at least in the active zone of the guide and the second portion can comprise at least an external part extending outside said active zone.

[0039] According to an aspect of the present invention, the probe head can also comprise a further portion in the form of a layer arranged between the first portion and the second portion, said further portion being made of a high thermal conductivity material selected from diamond, silicon carbide, or a silver-diamond compound with a diamond percentage between 50 and 99%, preferably diamond.

[0040] According to an aspect of the present invention, the second portion can be a layer having a thickness between 1 gm and 10 gm.

[0041] The present invention also relates to a measuring system or measurement system comprising a probe head as disclosed above, a support structure (such as for example, but not limited to, a backer), and at least one thermal pipe configured to thermally connect the probe head (in particular the housing thereof) with the support structure to promote the heat dissipation of said probe head.

[0042] The features and advantages of the probe head according to the invention will be apparent from the following description of an exemplary embodiment thereof given by way of non-limiting example with reference to the attached drawings.

[0043] Brief description of the drawings

[0044] In the drawings:

[0045] - figure 1 schematically shows a probe head according to embodiments of the present invention;

[0046] - figure 2 shows a top schematic view of a guide of the probe head according to embodiments of the present invention;

[0047] - figure 3 schematically shows a probe head according to further embodiments of the present invention;

[0048] - figures 4A-4D show further exemplary embodiments of the present invention; - figure 5 shows a probe head according to an alternative embodiment of the present invention; and

[0049] - figure 6 shows a measuring system according to an embodiment of the present invention.

[0050] Detailed description

[0051] With reference to the figures, a probe head according to the present invention for testing a device under test (indicated with the reference DUT, acronym for “Device Under Test”) is globally and schematically indicated with 100.

[0052] It should be noted that the figures represent schematic views and are not drawn to scale, but instead they are drawn so as to emphasize the important features of the invention. Furthermore, in the figures, the different elements are schematically depicted, the shape thereof being changeable depending on the desired application. Furthermore, it should be noted that, in the figures, identical reference numbers refer to identical elements in terms of shape or function. Finally, special arrangements described in relation to an embodiment illustrated in a figure can also be used for the other embodiments illustrated in the other figures.

[0053] Furthermore, it is noted that, unless it is expressly stated to the contrary, process steps can also be inverted if necessary.

[0054] The probe head 100 is adapted to connect (directly or indirectly by means of a space transformer and / or a PCB) with an apparatus (not illustrated in the figures) to perform the testing operation of electronic devices integrated on a semiconductor wafer (reference WS).

[0055] It is noted that, in the context of the present invention, the term “probe head” is used to indicate a test device without being limited by the presence or absence of particular components. In general, this term thus indicates a set of components which can be associated to further components for testing devices integrated on a semiconductor wafer WS, and thus it generally may be or may be part of a measuring system of electronic devices.

[0056] With reference to the sectional view of figure 1, the probe head 100 comprises a plurality of contact probes 10 intended to connect the device under test DUT integrated in the semiconductor wafer WS with the testing apparatus.

[0057] In order to house the contact probes 10, the probe head 100 comprises at least one guide 20 provided with guide holes 20h through which said contact probes 10 are able to slide. The guide 20 thus allows, together with the guide holes 20h thereof, the contact probes 10 to be slidingly housed.

[0058] In an embodiment, each contact probe 10 comprises a probe body 10’ which extends along a longitudinal axis H-H between a first end portion 10a and a second and opposite end portion 10b, which are adapted to contact respective pads or contact pads. By way of example, the first end portion 10a (also called contact tip) is adapted to contact pads DUTa of the device under test DUT integrated on the semiconductor wafer WS, while the second and opposite end portion 10b (also called contact head) is adapted to contact pads 25a of a space transformer or of a printed circuit board (PCB) which can be associated to the probe head 100, this component being generically identified with the numeral reference 25. Although the end portions 10a and 10b in the attached figures end with a pointed shape, they are not limited thereto, and they can have any shape which is suited to the needs and / or circumstances.

[0059] In the example of the figures, the guide 20 is a lower guide of the probe head 100 and thus, as it is known in the art, it is close to the first end portion 10a intended to contact the test device, i.e. it is closest to the device under test during the test with respect to an upper guide or an intermediate guide. Therefore, the guide 20 will be also identified herein as lower guide of the probe head 100.

[0060] In an embodiment, the probe head 100 can also comprise further guides, such as for example an upper guide (indicated with the reference 40) separated from the lower guide 20 and provided with respective guide holes 40h.

[0061] According to embodiments of the present invention, the probe head 10 further comprises a housing or containment element (indicated with the reference 30) configured to at least partially house the contact probes 10. The housing 30 is also configured to provide a support structure for the at least one guide 20 and, in case of several guides, also a structure for connecting and separating them. In the embodiment of figure 1, the housing 30 is arranged between the lower guide 20 and the further upper guide 40 and it supports both said guides; it is suitably shaped to house the contact probes 10 therein. The housing 30 is also defined as a “spacer” since in an embodiment it is configured to keep the guides separated from each other (i.e., not in direct contact).

[0062] Furthermore, in an embodiment, the lower guide 20 can be in the form of a pair of lower guides 20’ and 20” and the further upper guide 40 can be in the form of a pair of upper guides 40’ and 40”.

[0063] In order to effectively dissipate the heat generated inside the probe head 100, it comprises a first portion (indicated with the reference LI) made of a high thermal conductivity material; thereby, the first portion LI is configured to collect and dissipate the heat produced by the probe head 100 during the test. In other words, the first portion LI is thus a heat dissipation structure configured to dissipate the heat generated by the various components of the probe head 100.

[0064] In a preferred embodiment, the first portion LI is a layer in contact with the guide 20, for example a surface layer thereof (for this reason it will be indicated below also as first layer) .

[0065] The first portion LI is not limited by a particular material. For example, in an embodiment, the material of the first portion LI can be selected from diamond (in particular CVD-D, acronym for “Chemical Vapor Deposition-Diamond”), silicon carbide, silicon nitride, or a silver- diamond compound with a diamond percentage between 50 and 99%. In a preferred embodiment, the material of the first portion is diamond, in particular CVD-D.

[0066] By way of example, the material of the first portion LI can have a thermal conductivity which is higher than 100 W / (m«K), more preferably higher than 500 W / (m«K). Furthermore, it can have an electrical resistivity which is higher than 104□•m, preferably higher than 1016Q-m.

[0067] This high thermal conductivity allows in particular to achieve an optimum collection and subsequent dispersion of the heat produced by the probe head 100 during the testing operations, for example of the heat produced by the contact probes 10.

[0068] As mentioned above, in a preferred embodiment of the present invention, the first portion LI is a layer formed on at least part of a face (the FB of the example of figure 1) of the guide 20, for example deposited through suitable deposition processes. The first portion LI can also completely cover the face FB of the guide 20 or even only a portion of said face, without limiting the scope of the present invention.

[0069] It is further noted that, although figure 1 shows the first layer LI formed on the face FB, which is an upper face according to the reference of the figures, additionally or alternatively it can be formed also on an opposite face FA, i.e. on a lower face which is closest to the device under test DUT, without limiting in any way the scope of the present invention.

[0070] It is further noted that, in a preferred embodiment, the first portion LI is formed so that it directly contacts the contact probes 10, i.e. there are no material cut-outs or removals at the guide holes 20h, thereby maximizing the heat exchange with said contact probes 10.

[0071] Furthermore, in an embodiment not illustrated in the figures, the first layer LI can at least partially surround the guide 20. In this example, the first layer LI can thus comprise at least one side part extending along a side wall 20s of the guide 20, a planar part extending along a first face (for example the upper face FB) of the guide 20, as well as a further planar part extending along a further face of the guide 20 (for example the face FA opposite the face FB), said faces FA and FB being substantially orthogonal to said side wall 20s.

[0072] Advantageously according to the present invention, in order to increase the heat dissipation capability of the probe head 100, it further comprises a second portion L2 in contact with the first portion LI and made of a conductive material. By way of example, the material of the second portion L2 can be gold. Moreover, the second portion L2 is in the form of at least one layer, as it will be discussed below.

[0073] As illustrated in the figures, the second portion L2 is arranged on the first portion LI (for example a layer deposited on the first portion through suitable deposition processes), so that said first portion LI is arranged between the guide 20 and said second portion L2.

[0074] In an embodiment, the second portion L2 is a layer in contact with the housing 30, which is made of a conductive material (such as invar for example, but without being limited by a specific be material).

[0075] The guide holes 20h for housing the contact probes 10 are formed in a zone of the guide 20 defined as “active zone” (herein indicated with the reference ZA) and which thus corresponds to the probe head zone in which the signals pass. In this regard, in an embodiment, the first portion LI can possibly also comprise, in addition to a part extending in the active zone ZA (in particular in contact with the probes), an external part extending outside the active zone ZA (connected or in line / in continuity with the part in the active zone), where there are neither guide holes nor contact probes 10. Similarly, the second portion L2 can comprise a part in the active zone ZA and / or an external part extended outside said active zone ZA, said external part of said second portion L2 being arranged on said corresponding external part of said first portion LI (if any), ensuring an effective heat dissipation.

[0076] It is noted that the term “active zone” does not necessarily indicate a central zone of the guide, even if this can be possible, but it generally indicates the guide zone (or zones) in which the contact probes are arranged.

[0077] By way of example, in an embodiment, the first portion LI extends slightly outside the active zone ZA to connect to a second portion L2 extending only outside said active zone ZA, or the second portion L2 can also extend in the active zone ZA, as described above, without limiting the scope of the present invention.

[0078] The first portion LI can be a layer having a thickness between 10 gm and 100 gm, while the second portion L2 can be a layer having a thickness between 1 gm and 10 gm, but without the present invention being limited by these dimensional values.

[0079] In an embodiment of the present invention, the second portion L2 is in the form of at least one conductive portion or conductive layer (also indicated below as metallization) that encloses at least one group of holes of the guide holes 20h and is adapted to contact, and thus to short- circuit, a corresponding group of contact probes housed in said group of holes and intended to carry a same given type of signal, in particular intended to carry a given ground or power signal or operating signal. At least one conductive domain is thereby formed on the guide 20 by means of the second portion L2, with subsequent increase in the probe head performances. For example, the contact probes 10 that are short- circuited with each other by the second portion L2 can be contact probes intended to carry ground signals, as well as they can be contact probes intended to carry power supplies.

[0080] There can be several metallizations, each one dedicated to a given domain. In other words, there can be different power domains, and / or ground domains, and / or domains adapted to carry operative signals short-circuited by a respective conductive portion.

[0081] All this is advantageous since it is known in the art that the fixed position of the power supply and ground signals (due to the layout of the pads of the device under test) and the probe shape limit the control of the impedance of the signals inside the probe head, as well as they limit the control of the noise caused on the signal probes by other close signals, which limits the frequency performances of the probe head. For this reason, in particular in high-frequency applications, the ground and power probes are short-circuited by a metallization on the guide (i.e. by the above second portion L2), short-circuiting probes of a same domain and possibly making the ground signal available inside the probe head to connect possible shields. Furthermore, in the case of devices with different ground / power domains on the device which are then joined on the PCB, the metallization allows the loop inductance between a power supply and the related ground to be reduced. Furthermore, in the case of power supply domains, this contributes for example to reduce the probe burning phenomenon. By way of example, consider the case in which a given power supply of a device under test is contacted by a single contact probe of the probe head, which is short-circuited with other probes which carry power supply signals sharing the same power supply. Then, when the current of this power supply meets the metallization which short- circuits all the probes of this domain, it splits among all the short- circuited probes thereby allowing the equivalent resistance and inductance to be reduced compared to the case in which this current is confined in a single probe up to the PCB. All this contributes to increase the performances of the probe head 100.

[0082] In any case, it is noted that the present invention is not limited by the number and arrangement of the conductive portions, which can be set based on the needs and / or circumstances.

[0083] As mentioned above and as illustrated in figure 2, in an embodiment, the second portion is structured (divided) in a plurality of second conductive portions (called below “plurality of conductive layers”, these layers being indicated in figure 2 with L2a, L2b, L2c, L2d and L2e by way of example); these conductive layers can be separated from each other.

[0084] Some of the above conductive layers can correspond to different conductive domains, each one of said conductive domains being configured to short-circuit probes adapted to carry a different respective signal, for example different power domains, and / or ground domains, and / or domains adapted to carry operative signals, in particular power domains.

[0085] Again with reference to figure 2, suitably, in addition to the at least one conductive layer which forms a corresponding conductive domain (i.e. in contact with contact probes), a further conductive layer can also be provided (this further conductive layer being indicated below as “conductive layer L2e”, which is thus a conductive layer of the above plurality of conductive layers into which the second portion is divided), said further conductive layer is insulated from the contact probes, for example is outside said active zone ZA of the guide 20, and thus may correspond to the above-mentioned external part of the second portion L2 as defined above, in which there are no contact probes (it is generally a layer which is not electrically connected with contact probes). In this case, the conductive layer L2e is thus a floating layer in which no signal circulates. In an embodiment, as mentioned above, the external conductive layer L2e can be in contact with the housing 30, with further improvements in the dissipation capacity of the probe head 100.

[0086] It is further noted that, although generally the conductive layer L2e is an external layer outside the active zone ZA, this is not necessary; what matters is that it is a layer which is electrically insulated from the contact probes 10.

[0087] In general, the first portion LI and the second portion L2 can also extend outside the active zone ZA of the guide (on the entire face of the guide or even only on portions thereof) promoting the heat exchange with air, and / or the heat exchange with the housing 30 through the part of the second portion L2 (for example the conductive layer L2e, or, in the case of a single portion L2 which does not contact the probes, the most peripheral part thereof) which extends in this active zone ZA (even more particularly through the floating layer L2e). Referring now to figure 3, there can be dissipation layers also on the further upper guide 40. More particularly, in a non-limiting example, the probe head 100 also comprises a third portion L3 made of the same material as the first portion LI and in contact with the further upper guide 40, as well as there is a fourth portion L4 made of the same conductive material as the second portion L2 and in contact with said third portion L3.

[0088] In an embodiment not illustrated in the figures, only the portions L3 and L4 can be formed on the further upper guide 40 with no layers on the lower guide 20, without limiting in any way the scope of the present invention. In fact, it is noted that the portions L3 and L4 are analogous to the portions LI and L2, only differing for the numeral references and all the considerations made for the guide 20 can similarly apply to all the possible further guides of the probe head 100.

[0089] Furthermore, as illustrated in figures 4A-4D, in the particular embodiment in which there is the pair of lower guides 20’ and 20” and / or the pair of upper guides 40’ and 40”, it is possible to provide, for one or for both pairs of guides, the presence of the portion having a high thermal conductivity and of the conductive layer (and thus the presence of the first portion LI and of the second portion L2 for the pair of lower guides 20’ and 20”, and / or the presence of the third portion L3 and of the fourth portion L4 for the pair of upper guides 40’ and 40”), these portions being arranged on the guide which is closest to the housing 30 and in contact therewith, as well as it is possible to optionally provide, for each pair, one or both portions between the two guides forming the pair, without limiting in any way the present invention.

[0090] Furthermore, in an alternative embodiment of the present invention illustrated in figure 5, the guide 20 is at least partially made of a high thermal conductivity material. More particularly, in this embodiment, the first portion LI corresponds to at least part of the guide 20, which is thus at least partially a heat dissipator and is thus at least partially made of said high thermal conductivity material, while the second portion L2 made of conductive material is a layer in contact with the guide 20 (as also seen above).

[0091] In an embodiment, the first portion LI corresponds to the entire guide 20, although this is not strictly necessary.

[0092] In general, the first portion LI is formed at least in the active zone ZA of the guide 20; in an embodiment, the second portion L2 comprises at least one external part extending outside said active zone ZA, as also seen above.

[0093] A mixed embodiment is further possible, not illustrated in the figures, in which there is also a further portion in the form of a layer arranged between the first portion LI and the second portion L2, said further portion being made of a high thermal conductivity material selected from diamond, silicon carbide, a silver-diamond compound with a diamond percentage between 50 and 99%, preferably diamond.

[0094] In any case, it is noted that everything has been seen for the above embodiments (such as the materials, the thicknesses, the various spatial configurations) is also applicable in this embodiment.

[0095] Furthermore, in an embodiment, the housing 30 can be connected below (i.e. at the face thereof facing towards the device under test) with a shield, which is adapted to exchange heat with air.

[0096] Finally, in an embodiment shown in figure 6, the probe head 100 is used in a testing or measuring system 1000 (also indicated in the art and below as probe card) provided with further features for further improving the heat dissipation capacity.

[0097] As it is known, the probe card 1000 comprises an interface board 70 (such as a PCB for example) adapted to interface it with the testing apparatus (not shown in the figures).

[0098] In particular, in order to achieve an even more optimum heat dissipation, the embodiment of figure 6 provides a system for removing heat from the probe head 100 towards the probe card 1000, in particular towards the upper part thereof (i.e. towards the portion thereof which is furthest from the device under test DUT).

[0099] In this case, the probe card 1000 comprises a thermal pipe (reference 50, in general a plurality of thermal pipes) adapted to thermally connect the probe head 100, in particular the housing or spacer 30 thereof, with further components, in general with a support structure 60 thereof (such as a backer for example, but without limiting the scope of the present invention) to which the PCB 70 is connected, in order to achieve a further heat dispersion. It is generally noted that the support structure 60 can be any component of the testing system, which then exchanges heat with air, such as an upper backer for example, or even a set of components such as the assembly formed by backer and stiffener.

[0100] In the path thereof, the thermal pipes may pass through various components, such as for example a mounting ring or jig / (reference 80) and the PCT 70 itself.

[0101] By way of example, the thermal pipe 50 can be of the passive type and can be made of a material having a thermal conductivity which is higher than 100 W / (m*K), preferably higher than 500 W / (m*K), for example made of a material selected from copper, aluminium, aluminium nitride, silicon nitride, silicon carbide and CVD-D (Chemical Vapor Deposition-Diamond), as well as it can also be of the active type.

[0102] In conclusion, in short, the present invention thus allows the technical problem to be successfully overcome, providing the above probe head and solving all the drawbacks of the prior art.

[0103] Advantageously according to the present invention, a heat dissipation structure is formed, which is able to collect and dissipate the heat generated during the testing operations of the probe head; this structure collects the heat which is generated, for example due to the friction of the contact probes which slide in the guide holes or due to the signals which pass through said contact probes and which can increase the temperature thereof (for example power signals), and promotes the dispersion of said heat in the environment; the combination of this structure with a conductive layer considerably increases performances.

[0104] There is in particular a flow of dispersed heat starting from the contact probes, passing (directly and / or indirectly) through the first portion having a high thermal conductivity, through the second portion (in particular the floating portion thereof, i.e. the part in which no signal circulates and which generally extends where there are no contact probes, although the latter aspect is not necessary) and finally the housing (in particular through the floating portion of the second portion).

[0105] More particularly, it is envisaged to create a heat flow, generated in the probes due to the Joule effect, from the active zone (for example from a substantially central zone in which there are the probes which generate said heat) to an external zone, for example a peripheral one, in contact with the housing, to then have an exchange with the housing which can in turn directly or indirectly exchange heat with air. It is then possible to optionally provide further dissipation means connected to the housing, such as thermal pipes for example, in connection with components of a probe card, said component in turn exchanging heat with air.

[0106] Suitably, as discussed above, in addition to a high thermal conductivity layer, the overlapping of also a conductive layer is provided, which allows a considerable increase in heat dissipation; conveniently, this conductive layer can be for example in the form of a metallization which short-circuits groups of probes, as well as there can be also at least one floating layer in which no signal circulates. Thereby, it is thus provided to also use the metallization on the guide to dissipate heat, with an increase in efficiency.

[0107] Obviously, in order to meet contingent and specific requirements, a person skilled in the art will be allowed to bring several modifications and alternatives to the above-described probe head, all falling within the scope of protection of the invention as defined by the following claims.

Claims

CLAIMS1. A probe head (100) for testing a device under test (DUT), said probe head (100) comprising: a plurality of contact probes (10) comprising a body (10’) extended between a first end portion (10a) and a second end portion (10b), said end portions being adapted to contact respective pads (DUTa, 25a); at least one guide (20) comprising guide holes (20h) for housing the contact probes (10); a housing (30) configured to support the at least one guide (20); a first portion (LI), which is a heat dissipation structure and is configured to collect and dissipate heat produced by said probe head (100) during the test; and a second portion (L2), which is made of a conductive material and is in contact with the first portion (LI).

2. The probe head (100) according to claim 1, wherein the first portion (LI) is made of a high thermal conductivity material selected from diamond, silicon carbide, a silver-diamond compound with a diamond percentage between 50 and 99%.

3. The probe head (100) according to claim 1 or 2, wherein the material of the second portion (L2) is gold.

4. The probe head (100) according to any one of the precedingclaims, wherein the second portion (L2) is in contact with the housing (30), which is made of a conductive material.

5. The probe head (100) according to any one of the preceding claims, wherein the first portion (LI) extends at least in an active zone (ZA) of said at least one guide (20), wherein in said active zone there are the guide holes (20h) housing the contact probes (10).

6. The probe head (100) according to claim 5, wherein the first portion (LI) also comprises an external part extended outside said active zone (ZA).

7. The probe head (100) according to claim 5 or 6, wherein the second portion (L2) comprises a part extended in the active zone (ZA) and an external part extended outside said active zone (ZA).

8. The probe head (100) according to claim 5 or 6, wherein the second portion (L2) comprises only an external part extended outside the active zone (ZA).

9. The probe head (100) according to claims 6 and 7, or according to claims 6 and 8, wherein said external part of said second portion (L2) is arranged on said corresponding external part of said first portion (LI).

10. The probe head (100) according to any one of the preceding claims, wherein the second portion (L2) is in the form of at least one conductive portion that encloses at least one group of holes of the guide holes (20h) and is adapted to contact and short-circuit a corresponding group of contact probes housed in said group of holes and are intendedto carry a given type of signal, thereby defining at least one conductive domain.

11. The probe head (100) according to claim 10, wherein the second portion is structured in a plurality of second portions (L2a, L2b, L2c, L2d, L2e) separated from each other.

12. The probe head (100) according to claim 11, wherein at least two portions (L2a, L2b, L2c, L2d) of said plurality of second portions correspond to different conductive domains, each of said conductive domains being configured to short-circuit contact probes adapted to carry a different respective signal, for example different power domains, and / or ground domains, and / or domains adapted to carry operative signals.

13. The probe head (100) according to claims 7 and 12, wherein said plurality of second portions (L2a, L2b, L2c, L2d, L2e) comprises at least two portions (L2a, L2b, L2c, L2d) in the active zone (ZA) and at least one portion (L2e) that is arranged outside said active zone (ZA) and that corresponds to said external part.

14. The probe head (100) according to claim 11, comprising at least one portion (L2e) of said plurality of second portions which is electrically insulated from the contact probes (10), said portion (L2e) being for example in contact with the housing (30).

15. The probe head (100) according to any one of the preceding claims, wherein the guide (20) is a lower guide, said probe head (100) comprising at least one further guide (40) which is an upper guideseparated from the lower guide (20) and includes respective guide holes (40h), the lower guide (20) being the guide which is closest to the device under test, wherein the housing (30) is arranged between said lower guide (20) and said further upper guide (40).

16. The probe head (100) according to claim 15, comprising a third portion (L3), which is made of the same material as the first portion (LI) and is in contact with the further upper guide (40), and a fourth portion (L4), which is made of the same conductive material as the second portion (L2) and is in contact with said third portion (L3).

17. The probe head (100) according to any one of the preceding claims, wherein the first portion (LI) is a layer having a thickness between 10 gm and 100 gm, and wherein the second portion (L2) is a layer having a thickness between 1 gm and 10 gm.

18. The probe head (100) according to any one of the preceding claims, wherein the first portion (LI) is a layer formed on at least part of a face (FB) of the guide (20), and wherein the second portion (L2) is a layer arranged on the first portion (LI), so that said first portion (LI) is arranged between said guide (20) and said second portion (L2).

19. The probe head (100) according to claim 18, wherein the first portion (LI) at least partially surrounds the guide (20), said first portion (LI) comprising at least one side part extending along a side wall (20s) of said at least one guide (20), a planar part extending along a face (FB) of the guide (20), and a further planar part extending along a further face (FA) of the guide (20), said faces (FA, FB) being orthogonal to saidside wall (20 s).

20. The probe head (100) according to any one of claims 1 to 16, wherein the first portion (LI) is at least a part of the guide (20), which is thereby at least partially a heat dissipation structure, and wherein the second portion (L2) made of said conductive material is a layer in contact with the guide (20).

21. The probe head (100) according to claim 20, wherein the first portion (LI) corresponds to the entire guide (20).

22. The probe head (100) according to claim 20 when dependent on claim 5, wherein the first portion (LI) is formed at least in the active zone (ZA), and wherein the second portion (L2) comprises at least one external part extending outside said active zone (ZA) .

23. The probe head (100) according to any one of claims 20 to22, comprising a further portion in the form of a layer arranged between the first portion (LI) and the second portion (L2), said further portion being made of a high thermal conductivity material selected from diamond, silicon carbide, a silver-diamond compound with a diamond percentage between 50 and 99%.

24. The probe head (100) according to any one of claims 20 to23, wherein the second portion (L2) is a layer having a thickness between 1 gm and 10 gm.

25. A measuring system (1000) comprising: a probe head (100) according to any one of the precedingclaims; a support structure (60); and at least one thermal pipe (50) configured to thermally connect the probe head (100) and the support structure (60).

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