Probe Card for Testing Apparatus of Electronic Device and Corresponding Space Transformer

Abstract

A probe card (20) configured to be mounted on a test apparatus for an electronic device is described. The probe card (20) includes at least one probe head (21) that houses a plurality of contact probes (22), a main board (27), and an intermediate board configured to provide a distance spatial conversion between contact pads formed on opposing surfaces connected to the main board (27). Each contact probe (22) has at least one first end (22A) configured to abut against a contact pad (23A) of a device (23) to be tested. The intermediate board is a space transformer (30), and the space transformer (30) is plate-shaped and includes a plurality of modules (40) that are structurally and functionally independent of each other on the same plane. Each module (40) has a first surface (F1) facing the probe head (21), on which a first plurality of contact pads (40A) are provided, against which respective second ends (22B) of the contact probes (22) abut, and a second surface (F2) facing the main board (27) and opposing the first surface (F1), on which a second plurality of contact pads (40B) are provided, which are connected to the first plurality of contact pads (40A) by electrical connections (40C) formed inside the module (40). The space transformer (30) includes a connection structure (31) formed corresponding to the second surface (F2) of the module (40), and the plurality of modules (40) have the same thickness (S2).

Description

Technical Field

[0001] The present invention relates to a probe card for a test apparatus of an electronic device.

[0002] The present invention particularly relates to a probe card including an intermediate board which is a space transformer disposed between a plurality of contact probes and a board for connection to a test apparatus, but is not limited thereto, and the following description is made only for the purpose of simplifying the explanation with reference to this field of application.

Background Art

[0003] As is well known, a probe card is essentially a device configured to electrically connect a plurality of contact pads of a fine structure, particularly an electronic device integrated on a wafer, to corresponding channels of a test apparatus for testing the device.

[0004] The tests performed on the integrated devices are used particularly to detect and separate defective devices at an early stage of the production phase. Usually, a probe card is thus used for electrical testing of these devices before dicing or singulating the devices integrated on a wafer or chip and assembling them inside a package.

[0005] A probe card essentially includes a probe head including a plurality of movable contact elements or contact probes provided with at least one end or contact tip configured to abut against corresponding plurality of contact pads of a device to be tested. In this paragraph and hereinafter, the terms "end" or "tip" indicate an end that is not necessarily pointed.

[0006] It is well known that the effectiveness and reliability of a measurement test depend exactly on causing a good electrical connection between the device under test and the test apparatus, and thus establishing an optimal probe / pad electrical contact, among other factors.

[0007] Among the types of probe heads used in the technical field considered in this specification for testing devices integrated on a wafer, so-called vertical probe heads, in which contact probes are arranged substantially perpendicular to the device under test, are widely popular.

[0008] In particular, a vertical probe head includes a plurality of contact probes that are formed in a plate shape and are usually held by a pair of plates or guides that are parallel to each other. These guides are arranged at a certain distance from each other so as to leave a free space or gap for the movement and possible deformation of the contact probes, and they are provided with appropriate guide holes configured to slidably accommodate the contact probes. More particularly, the pair of guides includes an upper guide (upper die) and a lower guide (lower die), both having guide holes through which the contact probes slide axially, and are usually made of wires of special alloys having good electrical and mechanical properties. Conventionally, the term "lower" refers to the guide closer 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 pressing the probe head against the device itself. The contact probes are movable inside the guide holes provided in the upper and lower guides, and during this pressing contact, they bend inside the gap between the two guides and slide inside the guide holes that accommodate them.

[0010] Furthermore, the bending of the contact probes inside the gap can be assisted and guided by an appropriate configuration of the probes themselves or the guides, particularly by using pre-deformed contact probes or by appropriately laterally shifting the guides that hold them.

[0011] Generally, a probe head having probes that are interfaced to a suitable main plate or main board, although not firmly fixed, and are connected to a test apparatus while remaining interfaced is used. These are called unblocked probe heads. The above-mentioned main board is usually a technology that enables the formation of a board having a printed circuit or PCB (Printed Circuit Board) technology and an active area even of a large size, and there are significant limitations regarding the minimum achievable value of the distance (pitch) between contact pads. Therefore, an intermediate board or space transformer having contact pads that are appropriately connected to each other by connections made at different distances on opposite surfaces and within the space transformer itself is used. Since it is made using a technology that is usually employed for a main board that is not as severely restricted in terms of distance as the device under test, it is also referred to as the main board or main PCB.

[0012] In this case, the contact probe has additional ends or contact heads configured to abut against a plurality of contact pads of the space transformer. Good electrical contact between the contact probe and the space transformer is ensured in the same way as contact with the device under test, by pressing the probe against the contact pads made on the space transformer.

[0013] Furthermore, the main board is generally maintained in a fixed position by a stiffener. The assembly of the probe head, the main board, the intermediate board or space transformer, and the stiffener forms a probe card, which is generally schematically shown as 10 in FIG. 1.

[0014] In particular, in the example of the figure, the probe card 10 includes a probe head 1 having a plurality of vertical probes 2 configured to abut against the contact pads 3A of the device 3 to be tested integrated on the semiconductor wafer 3'. In this case, the probe head 1 includes at least one upper guide 4 and a lower guide 5 each having an upper guide hole 4A and a lower guide hole 5A through which the contact probe 2 slides.

[0015] Each contact probe 2 has at least one first end or contact tip 2A that abuts against the contact pad 3A of the device 3 to be tested, and makes mechanical and electrical contact between the device to be tested and a test apparatus (not shown) of which the probe head 1 forms its end element.

[0016] Also, each contact probe 2 usually has a second end shown as the contact head 2B between the contact tip 2A and a contact head 2B that extends the probe body 2C along the longitudinal development axis of the contact probe 2.

[0017] The contact head 2B is configured to make contact with a plurality of contact pads 6A formed on an intermediate board 6 which is particularly a space transformer, and is connected to a main board 7 connected to an actual test apparatus.

[0018] The spatial transformation performed by the intermediate board 6 particularly relates the distances between the centers of the contact pads made on the mutually facing surfaces, and in particular, the intermediate board 6 has a first plurality of contact pads 6A made on its first surface FA facing the probe head 1 corresponding to the contact head 2B of the contact probe 2. The first plurality of contact pads 6A are connected by a suitable metallization 6C to a second plurality of contact pads 6B made on its second opposite surface FB facing the main board 7. The second plurality of contact pads 6B have a different spatial distribution with a pitch larger than the pitch of the first plurality of contact pads 6A which are distributed instead in such a way that the centers of the pads are more separated, i.e., substantially corresponding to the contact pads 3A of the device 3 under test. Thereby, the intermediate board 6 performs a spatial transformation, particularly by separating the distance of the contact pads 6B made on its second surface FB with respect to the contact pads 6A made on its first surface FA. The contact pads 6A of the first plurality and the contact pads 6B of the second plurality are generally represented as the probe side, or as the fine pitch pads and the PCB side, or as the large pitch pads, respectively.

[0019] Good electrical contact between the contact probe 2 and the intermediate board 6 is ensured in the same way as the contact with the device 3 under test by pressing the probe against the contact pads 6A made on the first surface FA of the intermediate board 6.

[0020] As already mentioned, the main board 7 is also maintained in a determined position by the stiffener 8.

[0021] In the embodiment shown in FIG. 1, the probe head 1 comprises a further intermediate guide 5' (median guide), which is formed in a plate shape and is parallel to the upper guide 4 and the lower guide 5 and is arranged between them, preferably near the lower guide 5. The intermediate guide 5' is provided with a plurality of intermediate guide holes 5'A in which the contact probes 2 are slidably accommodated.

[0022] Preferably, the upper guide 4, the lower guide 5, and the intermediate guide 5' are shifted from each other so as to ensure the preferred bending direction of the contact probe 2, except for their proper retention inside the probe head 1 completed by the housing 9 that integrally connects the guides to each other.

[0023] In vertical probe technology, therefore, it is particularly important in a space transformer that plays a very important role especially when testing integrated circuits made according to the latest integration technology that necessarily involves contact pads on a test object device that are very close and very small in size, to ensure good connection of the contact probe, especially with the test object device corresponding to its contact chip and especially with the test device corresponding to its contact head, and such constraints do not harmonize well with the PCB technology by which the main board is made.

[0024] Various techniques are known for making a space transformer that generally has a very thin thickness in the range of 0.5 to 3 mm and especially has a planarity problem.

[0025] More particularly, the first known solution is a ceramic-based technology, namely MLC (the acronym for "MultiLayer Ceramic"), which enables the formation of multiple layers of rigid ceramic materials with a high level of planarity and enables the dispersion of conductive layers connecting the contact pads made on the opposing surfaces of the space transformer in these layers of rigid ceramic materials.

[0026] In an MLC type space transformer, the conductive path 6C is made by a suitable configuration in which the conductive layer and the non-conductive layer, for example, a ceramic one, are overlapped and dispersed with each other.

[0027] Alternatively, instead of a ceramic multi-layer MLC, for example, it is also known to make a space transformer by means of an organic multi-layer (MLO, an acronym for "MultiLayer Organic") associated with a rigid support adhered thereto. The above MLO includes layers of a plurality of organic materials forming a plurality of non-conductive layers, and one or more conductive layers are arranged on the above non-conductive layers in a suitable configuration and are configured to form a conductive path 6C. The rigid support is preferably a ceramic support.

[0028] The mutual arrangement of the elements constituting the probe card is a very important parameter for the correct operation of the card itself, and some of the technologies used to make these elements cause flatness problems that complicate the configuration of the card, both as a whole and especially with respect to the mutual arrangement of the intermediate board or space transformer and the main board. Even if there are stiffeners that make the entire assembly stronger and more rigid, it is generally not possible to sufficiently eliminate the flatness defects of the space transformer or ensure its accurate and sufficient contact with the main board.

[0029] This is further complicated by the operating temperature of the card itself, especially when testing at extreme temperatures. In fact, in this case, the thermal expansion of the elements constituting the probe card can affect its correct behavior because the thermal expansion coefficients of the various materials forming these elements are different. In fact, it is common to fix those elements constituting the probe card to each other by screws, but these screws apply constraints that tend to cause buckling, especially during the temperature test, to the various boards, and even if there is a lack of contact with the contact pads of the device under test, it will subsequently be accompanied by a malfunction of the entire probe card up to the limit.

[0030] This problem is particularly affected in the case of large probe cards, such as probe cards for testing memory devices such as DRAMs. In the case of this type of probe card, if the thermal expansion of the components is not controlled, there will actually be major problems during the testing phase.

Summary of the Invention

Problems to be Solved by the Invention

[0031] The technical problem underlying the present invention is to enable the overcoming of limitations and drawbacks that still affect probe cards made with known technologies while having a simple and easy-to-assemble structure, and in particular, to provide a probe card having structural and functional features that can ensure the accurate planarity of all different components of the card even in the case of large cards or tests at high temperatures.

Means for Solving the Problems

[0032] The idea underlying the solution of the present invention is to provide a probe card having an intermediate board or a space transformer structured into a plurality of independent modules that can be tested before being assembled into a space transformer and, in case of failure, can be discarded as much as possible, and these modules are provided with appropriate means for connecting to the main board or an additional support structure.

[0033] Based on the idea of this solution, the technical problem is solved by a probe card configured to be mounted on a test apparatus for an electronic device. The probe card includes at least one probe head that houses a plurality of contact probes, a main board, and an intermediate board connected to the main board and configured to provide a distance spatial conversion between contact pads formed on opposing surfaces. Each contact probe has at least one first end configured to abut against a contact pad of a device under test. The intermediate board is a space transformer and is plate-shaped and in the same plane and includes a plurality of modules that are structurally and functionally independent of each other. Each module has a first surface facing the probe head and provided with a first plurality of contact pads against which respective second ends of the contact probes abut, and a second surface facing the main board and opposed to the first surface and provided with a second plurality of contact pads connected to the first plurality of contact pads by electrical connections formed inside the module. The module is provided with a connection structure formed on the second surface of the module, and these modules have the same thickness, which is characterized.

[0034] More particularly, the present invention includes the following additional and optional features, which may be employed individually or in combination as required.

[0035] According to an aspect of the present invention, the connection structure of the space transformer can include a plurality of connection regions, and each of the connection regions is formed corresponding to the second surface of one of the above-described modules.

[0036] Furthermore, the thickness of each connection region along the z-axis orthogonal to the main board can be less than 10%, preferably less than 1%, of the thickness of each module along the z-axis.

[0037] According to another aspect of the present invention, each connection region can include welding.

[0038] Furthermore, each connection region can preferably include an adhesive film or an adhesive that is conductive.

[0039] According to yet another aspect of the present invention, the connection structure can integrally connect the module of the space transformer to the main board corresponding to the surface facing the probe head.

[0040] In particular, the surface of the main board to which the module is integrally connected can have a surface roughness of less than 5 microns.

[0041] According to another aspect of the present invention, the space transformer can further include a support portion, the connection structure can integrally connect the module of the space transformer to the support portion corresponding to the surface facing the probe head, and the support portion is integrally connected to the main board.

[0042] In particular, the surface of the support portion to which the module is integrally connected can have a surface roughness of less than 5 microns, preferably less than 1 micron.

[0043] According to another aspect of the present invention, the space transformer can further include a plurality of separator elements on the same plane as the module, the separator elements are arranged in a checkerboard configuration and are scattered, and each of the separator elements separates a pair of modules.

[0044] In particular, each of the separator elements can include a connection region formed corresponding to the surface facing the main board, and the connection region of the separator element is included in the connection structure of the space transformer.

[0045] According to another aspect of the present invention, at least one of the separator elements can include active and / or passive elements, preferably capacitors.

[0046] Furthermore, according to another aspect of the present invention, each connection region is formed by a single region or includes a plurality of connection regions different from each other, and can be arranged on the second surface of the module.

[0047] According to a further aspect of the present invention, each of the modules has a plate-like shape, in particular a prismatic shape with a rectangular or hexagonal bottom surface.

[0048] Finally, according to another aspect of the present invention, each of the modules can comprise at least one multilayer, preferably an organic multilayer MLO.

[0049] Furthermore, the above technical problem is solved by a space transformer configured to be inserted into a probe card for a test device of an electronic device, the space transformer being plate-shaped and in the same plane and comprising a plurality of modules that are structurally and functionally independent of each other, and a connection structure made corresponding to the second surface of the module, each module having a first surface provided with a first plurality of contact pads and a second surface facing the first surface, the second surface being provided with a second plurality of contact pads connected to the first plurality of contact pads by electrical connections formed inside the module, and these modules being characterized by having the same thickness.

[0050] According to another aspect of the present invention, the connection structure can comprise a plurality of connection regions, and each of the connection regions is formed corresponding to the second surface of one of the above modules.

[0051] According to yet another aspect of the present invention, the thickness of each connection region can be less than 10%, preferably less than 1%, of the thickness of each of the modules along the same z-axis.

[0052] Furthermore, according to another aspect of the present invention, each connection region can preferably include a welding or adhesive film or an adhesive that is conductive.

[0053] The space transformer can further include a support portion, and the connection structure integrally connects these modules to the support portion corresponding to their surfaces.

[0054] In particular, the surface of the support portion to which the modules are integrally connected has a surface roughness of less than 5 microns, preferably less than 1 micron.

[0055] According to another aspect of the present invention, the space transformer can further include a plurality of separator elements on the same plane as the modules. The separator elements are arranged in a checkerboard configuration and are scattered, and each of the separator elements separates a pair of modules.

[0056] According to another aspect of the present invention, each of the separator elements can include a connection region formed corresponding to and aligned with the second surface of the above-mentioned module and corresponding to the surface corresponding to the second surface. The connection region of the separator element is included in the connection structure of the space transformer.

[0057] According to still another aspect of the present invention, at least one of the separator elements can include active and / or passive elements, preferably a capacitor.

[0058] Furthermore, according to another aspect of the present invention, each connection region can be formed by a single region or can include a plurality of connection regions that are different from each other and are arranged on the second surface of the module.

[0059] According to another aspect of the present invention, each of the modules can have a plate-like shape, particularly a prismatic shape having a rectangular or hexagonal bottom surface.

[0060] Finally, according to another aspect of the present invention, each of the modules can include at least one multilayer, preferably an organic multilayer MLO.

[0061] The features and advantages of the probe card and the space transformer according to the present invention will become apparent from the following description of the exemplary embodiments given as non-limiting examples with reference to the accompanying drawings.

Brief Description of the Drawings

[0062]

Figure 1

Figure 2A

Figure 2B

Figure 3A

Figure 3B

Figure 4A

Figure 4B

Figure 5A

Figure 5B

Figure 6A

Figure 6B

[0063] Referring to the figures, particularly FIG. 2A, a probe card 20 is generally shown with numeral 20, which comprises at least one probe head provided with a plurality of contact probes 22 for testing electronic devices, particularly those integrated on a wafer, made in accordance with the present invention.

[0064] It should be noted that the figure represents a schematic view of the card according to the present invention, not drawn to scale, but rather drawn to emphasize the important features of the present invention.

[0065] Also, different aspects of the present invention represented as examples in the figures can clearly be combined with each other and can be exchanged from one embodiment to another.

[0066] In particular, as shown in FIG. 2A, the probe card 20 comprises a probe head 21 that houses a plurality of contact probes 22. In the example shown in the figure, the probe head 21 is of a vertical type, which comprises at least one upper plate or guide 24 and one lower plate or guide 25, and the guides 24 and 25 respectively have upper guide holes 24A and lower guide holes 25A through which the contact probes 22 slide.

[0067] As is customary in the technical field of the present invention, the term "lower guide" refers to a guide located closer to the device to be tested, and the term "upper guide" refers to a guide located closer to the test apparatus connected to the probe card including the probe head.

[0068] The probe head 21 also includes an encapsulating element or housing 29 configured to surround the contact probe 22 and integrally connect the upper guide 24 and the lower guide 25.

[0069] In the example shown in FIG. 2A, the probe head 21 also includes an intermediate plate or guide 26 disposed parallel between the upper guide 24 and the lower guide 25, particularly closer to the lower guide 25. Similarly, an intermediate guide hole 26A through which the contact probe 22 slides is provided in the intermediate guide 26. The above-described embodiments of the three guides are merely given as examples, and the probe head 21 can include any number of one or more guides.

[0070] Each of the contact probes 22 is particularly provided with at least one first end or contact tip 22A configured to establish a desired contact, particularly an electrical contact, between the contact probe 22 of the probe head 21 and the contact pad 23A of the device 23 under test, and in particular to abut against the corresponding contact pad 23A of the device 23 under test integrated on the semiconductor wafer 23'.

[0071] Each contact probe 22 further includes a second end or contact head 22B configured to establish contact with a main board 27 or a main PCB for connection to a test apparatus (not shown). A rod-shaped probe body 22C is disposed substantially along the longitudinal extension direction of the contact probe 22, which is particularly orthogonal to the plane in which the device 23 under test is disposed, between the contact head 22B and the contact tip 22A.

[0072] The probe card 20 includes an intermediate board that is arranged between the probe head 21 and the main board 27 and is configured to perform a spatial transformation, particularly with respect to the distribution of contact pads on mutually facing surfaces, and is thus represented by the space transformer 30. In proper accordance with the present invention, the space transformer 30 is divided into a plurality of modules 40 that are in the same plane and are structurally and functionally independent of each other. Each of the modules 40 is plate-shaped (referring to a physical product rather than an abstract geometric entity and thus always taking into account process tolerances), is arranged between the probe head 21 and the main board 27, and the modules 40 have the same thickness S2, that is, the same dimension along the z-axis orthogonal to the deployment plane of the device 23 under test, except for the dimensional tolerances related to the process for making the modules 40, which still refer to physical products.

[0073] The probe card 20 further includes a stiffener 28 associated with the main board 27 that is particularly useful in the case of temperature tests to improve the planarity of the main board 27.

[0074] Suitably, each module 40 has a first face F1 facing the probe head 21 (when in the operating state, i.e., when the space transformer 30 comprising the module 40 is inserted into the probe card 20 assembled as an end element of the test apparatus), and the first face F1 comprises a first plurality of contact pads also denoted as probe-side pads 40A against which the contact heads 22B of the contact probes 22 abut. Further, each module 40 has a second face F2 facing the first face F1 and thus (when in the operating state) facing the main board 27 for connection to the test apparatus, and the second face F2 comprises a second plurality of contact pads also called tester-side pads 40B, and the second plurality of contact pads are connected to the plurality of probe-side pads 40A by respective electrical connections 40C formed inside the module 40. The first face F1 and the second face F2 of each module 40 have a larger surface extension, preferably a much larger surface extension, with respect to the other side faces of the module 40 which are substantially tile-shaped, and the module 40 is arranged by the probe card 20 including the space transformer 30 to cover the desired area of the space transformer 30 corresponding to the area of the semiconductor wafer 23' comprising the device 23 under test. All the modules 40 are sized, particularly in terms of thickness, similar to an integrated space transformer made according to the prior art but with a larger overall surface extension, and are configured in the form of a board to test memory devices such as DRAMs in particular.

[0075] According to the invention, advantageously, each module 40 also comprises at least one connection area 41 arranged on its second face F2 and configured to be integrally connected to the main board 27. All the connection areas 41 of the plurality of modules 40 form a connection structure 31 of the space transformer 30 configured to be integrally connected to the main board 27.

[0076] In a preferred embodiment, the connection region 41 is a weld. Alternatively, it is possible to form the connection region 41 by means of an adhesive film or an adhesive, which is preferably conductive.

[0077] Suitably, the connection region 41 is arranged substantially planar, in particular on the second face F2 of the module 40, so as to ensure the correct positioning of the module 40 with respect to the z-axis which is orthogonal to the main board 27, in particular to the face F3 facing the probe head 21. Also, the connection region 41 has a thickness S1 along the z-axis which is negligible with respect to the thickness S2 of each module 40 along the z-axis so as to reduce the overall dimensions of the connection structure 31 which includes the connection regions 41 of all the modules 40 comprised in the space transformer 30, apart from maintaining its planarity with respect to the main board 27. In particular, the thickness S1 of the connection region 41 is less than 10%, preferably less than 1%, of the thickness S2 of the module 40, the thicknesses meaning the dimensions along the z-axis of the connection region 41 and of the module 40 respectively. Also in this case, the ratio between the thicknesses must be understood as excluding the process tolerances and this must always be taken into account when speaking about physical products and not abstract geometric entities.

[0078] According to one embodiment, the face F3 of the main board 27 is suitably made so as to have a planarity with a surface roughness Ra of less than 5 microns in particular, which makes it possible to ensure the correct alignment of the module 40 in the z-direction. It is also provided that the face F3 of the main board 27 undergoes a flattening treatment configured to reduce its surface roughness to the desired value as described above.

[0079] Using the connection area 41 formed on the second face F2 of the module 40, the module 40 can be easily arranged on the face F3 of the main board 27, for example, by a spatial positioning method, particularly an optical alignment method, and it should be emphasized that the position of the module 40 on the face F3 of the main board 27 can be accurately determined in this way. Appropriately, the module 40 is configured to be arranged side by side in the space transformer 30 so as not to leave gaps or empty areas except for process tolerances.

[0080] In a preferred alternative embodiment of the invention schematically shown in FIG. 2B, the space transformer 30 also includes a support portion 32 to which the module 40 is integrally connected by respective connection areas 41, particularly corresponding to the face F4 of the support portion 32 facing the probe head 21 (in the operating state).

[0081] Appropriately, it is possible to make the support portion 32 using techniques and materials that can ensure an appropriate flatness, particularly a surface roughness Ra of less than 5 microns, on the face F4 on which the module 40 is assembled. The support portion 32 cannot be made according to PCB technology, and thus, it should be emphasized that the support portion 32 can include materials configured to easily reach the desired value of roughness, and the value of the surface roughness Ra is less than 1 micron and no further planarization treatment is required.

[0082] Therefore, the support portion 32 is connected to the main board 27 according to any technique well known in the art, such as by welding, particularly by using a conductive adhesive film or adhesive, or by a mechanical screw system, and the correct arrangement of the module 40 is ensured by its integral connection to the support portion 32 by the connection structure 31.

[0083] According to the present invention, advantageously, a space transformer 30 is constituted by a plurality of modules 40 that are structurally and functionally independent of each other and are correctly arranged in the space xyz by a connection structure 31 that integrally connects them to the main board 27 or the support part 32. It should be emphasized that this simplifies the manufacture of individual modules that can be manufactured and tested before being assembled into the space transformer 30, and reduces the final manufacturing cost of the space transformer 30. Further, a space transformer 30 having a fairly large size such as for testing a memory device such as a DRAM can be made without causing a planarity problem of an integrated space transformer made according to the prior art while reducing the thickness of the space transformer 30, particularly while keeping the thickness of the space transformer 30 substantially equal to the thickness S2 of each module 40.

[0084] Advantageously, each module 40 can be manufactured by one of the techniques used in the art for making a space transformer. Preferably, each module 40 is manufactured by a multilayer, preferably an organic multilayer MLO.

[0085] FIG. 3A is a simplified top view showing the arrangement of the space transformer 30 and its modules 40 when testing a semiconductor wafer 23' having a plurality of devices 23 to be tested using a probe card 20. In the example shown in the figure, contact pads 23A are arranged corresponding to two opposite sides of each device 23 to be tested. In the figure, the probe card 20 is shown without the main board 27 or the stiffener 28.

[0086] A cross-sectional view of such a space transformer 30 is shown in FIGS. 4A and 4B respectively according to the embodiments of FIGS. 2A and 2B, for example. In particular, the space transformer 30 in FIG. 4A includes a plurality of modules 40 that are directly and integrally connected to the main board 27 by a plurality of connection regions 41 forming a connection structure 31, particularly corresponding to the plane F3.

[0087] As described above, the space transformer 30 includes a plurality of adjacent modules 40 provided with a first plurality of probe-side pads 40A made corresponding to its first plane F1 facing the probe head 21 (in the operating state) and a second plurality of tester-side pads 40B made corresponding to the second plane F2 facing the main board 27 (always in the operating state). The first plurality of probe-side pads 40A and the second plurality of tester-side pads 40B are connected to each other by appropriate electrical connections 40C. The space transformer 30 also includes a plurality of connection regions 41 made corresponding to the second plane F2 of the module 40 and configured to form the connection structure 31 of the space transformer 30.

[0088] More particularly, in the embodiment of FIG. 4A, each module 40 includes a connection region 41 for integrally connecting to the main board 27 corresponding to the plane F3 facing the probe head 21 (in the operating state), while in the embodiment of FIG. 4B, each module 40 includes a connection region 41 for integrally connecting to the support portion 32 corresponding to the plane F4 facing the probe head 21 (in the operating state), and the support portion 32 is integrally connected to the main board 27 corresponding to the plane F3.

[0089] It is also possible to make a probe card 20 (in a so-called full array configuration) that can test a device 23 under test having contact pads 23A arranged along all four of its sides using a space transformer 30. In this case, the space transformer 30 has dimensions corresponding to, in particular the thickness of, the module 40, in particular the thickness, and is in the same plane as them, and comprises a plurality of separator elements 42 scattered in a checkerboard configuration. In fact, in this case, in order to test the contact pads 23A of the device 23 under test in a full array configuration and at the same time ensure that the contact probes 22 do not mechanically or electrically interfere with each other, the contact probes 22 of the probe head 21 associated with the space transformer 30 can be appropriately scattered and spaced apart, thereby performing correct routing of the signals provided to the contact probes 22. In a preferred embodiment, the separator elements 42 are also integrally connected to the main board 27 or the support 32 by respective connection regions 41 arranged on the surface F2 facing the main board 27 (in the operating state).

[0090] Also, one or more of the separator elements 42 can comprise additional components of an active or passive type, such as capacitors, thereby adding additional performance, such as signal filtering, to the space transformer 30.

[0091] As described above, the space transformer 30 includes a plurality of modules 40 provided with a first plurality of probe-side pads 40A formed corresponding to its first surface F1 facing the probe head 21 (in the operating state) and a second plurality of tester-side pads 40B formed corresponding to its second surface F2 facing the main board 27 (always in the operating state). The first plurality of probe-side pads 40A and the second plurality of tester-side pads 40B are connected to each other by appropriate electrical connections 40C. The space transformer 30 also includes a plurality of separator elements 42 that are on the same plane and in which the modules 40 are scattered in a checkerboard structure. Each separator element 42 is disposed between two modules 40 and separates these modules 40.

[0092] A plurality of connection regions 41 formed corresponding to the second surface F2 of the module 40 form the connection structure 31 of the space transformer 30.

[0093] More particularly, in the embodiment of FIG. 5A, each module 40 includes a connection region 41 that is integrally connected to the main board 27 corresponding to a surface F3 facing the probe head 21 (in the operating state). On the other hand, in the embodiment of FIG. 5B, each module 40 includes a connection region 41 that is integrally connected to the support portion 32 corresponding to a surface F4 facing the probe head 21 (in the operating state). The support portion 32 is integrally connected to the main board 27, particularly corresponding to the surface F3.

[0094] Preferably, each separator element 42 also includes a connection region 41 corresponding to its second surface F2 facing the main board 27 (in the operating state).

[0095] As schematically shown in FIG. 6A, it is possible to configure a connection region 41 having a single region. Here, only one module 40 is illustrated for simplicity. Alternatively, the connection region 41 can include a plurality of different connection regions 41a disposed on the second surface F2 of the module 40.

[0096] Furthermore, it should be emphasized that it is possible to fabricate individual modules 40 having a shape other than a prism shape with a rectangular bottom surface shown in FIGS. 6A and 6B, for example, a prism shape with a hexagonal bottom surface, and a plurality of modules with a hexagonal bottom surface can be arranged to efficiently cover a desired area of the space transformer 30.

[0097] In conclusion, according to the present invention, advantageously, a probe card is provided with a space transformer composed of a plurality of modules that are structurally and functionally independent of each other.

[0098] Each module is clearly easier to fabricate than a large space transformer by means of a simplified and advantageously testable (and thus disposable) routing that is performed by internal electrical connections before being assembled into the final space transformer, and has obvious advantages from the viewpoints of cost and production efficiency. Also, the individual modules can be made equal to each other, improving the performance of the space transformer as a whole.

[0099] Furthermore, according to the present invention, advantageously, each module can be integrally connected in a simple manner on the main board by a plurality of connection regions, preferably a connection structure formed by welding, thereby ensuring the planarity of the space transformer thus obtained.

[0100] In an advantageous alternative embodiment, the space transformer also comprises a support that can be fabricated by technologies and materials capable of improving the flatness of its surface so as to ensure a more accurate arrangement of the modules forming the space transformer in the z direction.

[0101] Thereby, the probe card according to the present invention is suitable for applications where large wafers and devices with a large number of pads need to be tested.

[0102] Furthermore, according to another advantageous alternative embodiment, the module is interspersed with separator elements to enable correct routing of contact probes configured to abut contact pads disposed on all four sides of the device under test, as in the case of a full array test.

[0103] Obviously, to meet certain possible requirements, those skilled in the art are allowed to make various changes and alternatives to the probe card and space transformer described above, all of which fall within the scope of protection of the present invention as defined by the following claims.

Claims

1. A probe card (20) configured to be mounted on a test apparatus for electronic devices, The probe card (20) comprises at least one probe head (21) housing a plurality of contact probes (22), a main board (27), and an intermediate board connected to the main board (27) and configured to provide a spatial transformation of distance between contact pads made on opposing surfaces, Each contact probe (22) has at least one first end (22A) configured to contact a contact pad (23A) of the device under test (23), The aforementioned intermediate board is a space transformer (30), The space transformer (30) is plate-shaped and comprises a plurality of structurally and functionally independent modules (40) on the same plane, each module (40) having a first surface (F1) facing the probe head (21) and provided with a plurality of first contact pads (40A) to which the second ends (22B) of each of the contact probes (22) abut, and a second surface (F2) facing the main board (27) opposite the first surface (F1). A probe card (20) having a second surface (F2) on which a second plurality of contact pads (40B) are provided, which are connected to the first plurality of contact pads (40A) by an electrical connection (40C) formed inside the module (40), and the space transformer (30) comprises a connection structure (31) made corresponding to the second surface (F2) of the module (40), and the plurality of modules (40) have the same thickness (S2).

2. The probe card (20) according to claim 1, characterized in that the connection structure (31) of the space transformer (30) comprises a plurality of connection regions (41), and each of the connection regions (41) is formed corresponding to a second surface (F2) of one of the plurality of modules (40).

3. The probe card (20) according to claim 2, characterized in that each connection region (41) includes an element selected from welding, adhesive film, adhesive, conductive adhesive film, or conductive adhesive.

4. The probe card (20) according to claim 1, characterized in that the connection structure (31) integrally connects the module (40) of the space transformer (30) to the main board (27) corresponding to the surface (F3) facing the probe head (21).

5. The probe card (20) according to claim 4, characterized in that the surface (F3) of the main board (27) to which the module (40) is integrally connected has a surface roughness of less than 5 microns.

6. The space transformer (30) further comprises a support portion (32), The connection structure (31) integrally connects the module (40) of the space transformer (30) to the support portion (32) in a manner corresponding to the surface (F4) facing the probe head (21). The support portion (32) is integrally connected to the main board (27). The probe card (20) according to claim 1, characterized in that...

7. The probe card (20) according to claim 6, characterized in that the surface (F4) of the support portion (32) to which the module (40) is integrally connected has a surface roughness of less than 5 microns.

8. The probe card (20) according to claim 1, wherein the space transformer (30) further comprises a plurality of separator elements (42) that are coplanar with the module (40), the separator elements (42) are arranged in a checkerboard configuration and are scattered, and each of the separator elements (42) separates a pair of modules (40).

9. Each of the separator elements (42) is provided with a connection region (41) formed in correspondence with the surface (F2) facing the main board (27), The connection region (41) of the separator element (42) is included in the connection structure (31) of the space transformer (30). The probe card (20) according to claim 8, characterized in that...

10. The probe card (20) according to claim 9, characterized in that at least one of the separator elements (42) comprises an active and / or passive element.

11. The probe card (20) according to claim 2, characterized in that each connection region (41) is formed by a single region or comprises a plurality of connection regions (41a) of the module (40) that are different from each other and arranged on the second surface (F2).

12. The probe card (20) according to claim 1, characterized in that each of the modules (40) has a plate-like shape selected from a prism shape having a rectangular base and a prism shape having a hexagonal base.

13. The probe card (20) according to claim 1, characterized in that each of the modules (40) comprises at least one multilayer.

14. The probe card (20) according to claim 13, wherein the multilayer is an organic multilayer MLO.

15. A space transformer (30) configured to be inserted into a probe card (20) for a test apparatus for electronic devices, The invention comprises a plurality of plate-shaped modules (40) that are on the same plane and are structurally and functionally independent, and a connecting structure (31) made corresponding to the second surface (F2) of the module (40), Each module (40) has a first surface (F1) on which a plurality of first contact pads (40A) are provided, and a second surface (F2) opposite to the first surface (F1) on which a plurality of second contact pads (40B) are provided, which are connected to the plurality of first contact pads (40A) by an electrical connection (40C) formed inside the module (40). The plurality of modules (40) have the same thickness (S2), A space transformer (30) characterized by the following.

16. The space transformer (30) according to claim 15, characterized in that the connection structure (31) comprises a plurality of connection regions (41), each of which is formed on a second surface (F2) of one of the modules (40).

17. The space transformer (30) according to claim 16, characterized in that each connection region (41) includes an element selected from welding, adhesive film, adhesive, conductive adhesive film, or conductive adhesive.

18. The space transformer (30) according to claim 15, further comprising a support portion (32), wherein the connection structure (31) integrally connects the module (40) to the support portion (32) corresponding to a surface (F4).

19. The space transformer (30) according to claim 18, characterized in that the surface (F4) of the support portion (32) to which the module (40) is integrally connected has a surface roughness of a value selected from less than 5 microns or less than 1 micron.

20. The space transformer (30) according to claim 15, further comprising a plurality of separator elements (42) on the same plane as the module (40), wherein the separator elements (42) are arranged in a checkerboard configuration and scattered, and each of the separator elements (42) separates a pair of the modules (40).

21. The space transformer (30) according to claim 20, characterized in that each of the separator elements (42) is aligned with the second surface (F2) of the module (40) and has a connection region (41) formed corresponding to the surface (F2) corresponding to the second surface (F2), and the connection region (41) of the separator element (42) is included in the connection structure (31) of the space transformer (30).

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