Probe card for a test apparatus for electronic devices and corresponding
By designing the space converter of the probe card as composed of multiple independent modules and connecting the main board or support in an integral manner through the connection area, the planarity problem of existing probe card under large size and high temperature tests is solved, and the planarity problem of existing probe card is achieved. Stable and simplified assembly process.
Patent Information
- Application Number
- CN202380042484.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-05-25
- Filing Date
- 2023-05-23
- Publication Date
- 2024-12-20
AI Technical Summary
Existing probe cards have flatness problems in large size and high temperature testing environments, resulting in poor connection and test failure, and are complex in assembly and difficult to repair.
A space converter consisting of multiple independent modules, each module has the same thickness and is connected to the motherboard or support in an integral manner through the connection area to ensure planarity and stability.
The correct planarity and stable connections in large-size probe cards and high-temperature testing environments are achieved, simplifying the assembly process and reducing manufacturing costs.
Smart Images
Figure CN119173773A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a probe card for testing equipment of electronic devices.
[0002] The present invention particularly, but not exclusively, relates to a probe card comprising an intermediate board which is a space transformer inserted between a plurality of contact probes and a board for connecting to a test device. The following description is directed to this application field for the purpose of simplifying the explanation only. Background Art
[0003] As is known, a probe card is essentially a device suitable for electrically connecting a plurality of contact pads of a microstructure, in particular an electronic device integrated on a wafer, to corresponding channels of a test device that performs its testing.
[0004] The testing of integrated devices is particularly useful for early detection and isolation of defective devices in the production stage. Typically, probe cards are used to electrically test devices integrated on a wafer or chip before they are cut or singulated and assembled into a containment package.
[0005] The probe card comprises a probe head, which in turn mainly comprises a plurality of movable contact elements or contact probes, which are provided with at least one end or contact tip adapted to abut against a corresponding plurality of contact pads of a device under test. The term end or tip refers here or hereinafter to an end, not necessarily a point.
[0006] It is well known that the validity and reliability of measurement testing, among other factors, depends solely on establishing a good electrical connection between the device under test and the test equipment, thereby establishing optimal probe / pad electrical contact.
[0007] Among the various types of probe heads used in the technical field considered here for testing devices integrated on a wafer, so-called vertical probe heads are very common, in which the contact probes are arranged essentially perpendicular to the device under test.
[0008] In particular, the vertical probe head comprises a plurality of contact probes, which are usually held by a pair of plate-shaped and mutually parallel plates or guides. These guides are kept at a certain distance from each other so as to leave a free space or air gap for the movement and possible deformation of the contact probes, and these guides are provided with appropriate guide holes, which are suitable for slidingly accommodating the contact probes. More specifically, the pair of guides comprises an upper guide (upper die) and a lower guide (lower die), both of which are equipped with guide holes, through which the contact probes slide axially, and these guides are usually made of special alloy wires with good electrical and mechanical properties, and the term lower guide usually 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 under test itself. The contact probes can move in the guide holes of the upper and lower guide members. During the pressing contact process, the contact probes bend in the air gap between the two guide members and slide in the guide holes accommodating the contact probes.
[0010] Furthermore, the bending of the contact probe in the air gap may be assisted and guided by appropriate construction of the probe itself or of the guide, in particular by using a pre-deformed contact probe or by appropriate lateral movement of the guide containing the contact probe.
[0011] In general, a probe head is used which has probes which are not fixed firmly but remain docked with a suitable main board or main circuit board and which in turn is connected to the test equipment: such a probe head is called a non-blocking probe head. The main board is also called the main board or main printed circuit board, since it is usually manufactured using the printed circuit or printed circuit board technology (derived from the English "Printed Circuit Board"), which allows the formation of circuit boards with active areas of very large dimensions, but has great limitations in terms of the minimum achievable distance (pitch) values between the contact pads, and is therefore usually only used as a backup to the main board, the distance restrictions of which are more relaxed than those of the device under test, due to the use of an intermediate board or space transformer, which has contact pads made at different distances on its opposite faces, which are appropriately connected to each other by means of connections formed in the space transformer itself.
[0012] In this case, the other end or contact head of the contact probe is adapted to abut against a plurality of contact pads of the space transformer. By pressing the probe onto the contact pads formed on the space transformer, a good electrical contact between the contact probe and the space transformer is ensured, similar to the contact with the device under test.
[0013] In addition, the motherboard is generally held in place by stiffeners. The assembly of the probe head, motherboard, intermediate board or space transformer and stiffeners forms a probe card. Figure 1 The whole is indicated schematically by 10.
[0014] In particular, the probe card 10 comprises a probe head 1, which in the example shown in the figure comprises a plurality of vertical probes 2 adapted to abut against contact pads 3A of a device under test 3 integrated on a semiconductor wafer 3'. In this case, the probe head 1 further comprises at least one upper guide 4 and a lower guide 5, which have respective upper guide holes 4A and lower guide holes 5A through which the contact probes 2 slide.
[0015] Each contact probe 2 has at least one first end or contact tip 2A which abuts against a contact pad 3A of a device under test 3, making mechanical and electrical contact between the device under test and a test equipment (not shown), of which the probe head 1 forms an end element.
[0016] Furthermore, each contact probe 2 has a second end, generally indicated as a contact head 2B, between which a probe body 2C extends along a longitudinal development axis of the contact probe 2 .
[0017] The contact head 2B is in turn suitable for performing contact with a plurality of contact pads 6A on an intermediate board 6, in particular a space transformer, connected to a main board 7 which in turn is connected to the actual test equipment.
[0018] The spatial transformation performed by the intermediate board 6 particularly concerns the distances between the centers of the contact pads formed on its opposite faces; in particular, the intermediate board 6 comprises a first plurality of contact pads 6A formed on its first face FA facing the probe head 1, the plurality of first contact pads 6A corresponding to the contact heads 2B of the contact probes 2 and connected by means of appropriate metallization 6C to a second plurality of contact pads 6B formed on its second opposite face FB facing the main board 7, the plurality of second contact pads 6B having a different spatial distribution, in particular a larger distance between the centers of the pads, i.e. a pitch greater than the pitch of the plurality of first contact pads 6A, the plurality of first contact pads 6A being distributed in a manner substantially corresponding to the contact pads 3A of the device under test 3. In this way, the intermediate board 6 performs a spatial transformation, in particular spacing the contact pads 6B formed on its second face FB relative to the contact pads 6A formed on its first face FA. The plurality of first contact pads 6A and the plurality of second contact pads 6B are generally indicated as probe-side or fine-pitch pads and PCB-side or large-pitch pads, respectively.
[0019] By pressing the probes onto contact pads 6A formed on the first face FA of the intermediate board 6 , a good electrical contact is ensured between the contact probes 2 and the intermediate board 6 , similar to the contact with the device under test 3 .
[0020] As mentioned previously, the main plate 7 is also held in place by means of reinforcements 8 .
[0021] exist Figure 1 In the illustrated embodiment, the probe head 1 comprises another intermediate guide 5' (middle guide), which is plate-shaped and parallel to the upper guide 4 and the lower guide 5 and arranged between the two, preferably close to the lower guide 5, and 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] Suitably, the upper guide 4, lower guide 5 and intermediate guide 5' are offset from each other to ensure a preferred bending direction relative to the contact probe 2, yet also to retain it correctly within the probe head 1, which is accomplished by the housing 9 integrally connecting the guides to each other.
[0023] Therefore, in vertical probe technology, it is very important to ensure a good connection between the contact probe and the device under test (especially corresponding to its contact tip) and to the test equipment (especially corresponding to its contact head), and therefore a good connection at the space transformer is also very important. The space transformer plays a very important role in particular when testing integrated circuits manufactured according to the latest integration technology. This integration technology requires that the contact pads on the device under test are very close and of very small size. This limitation is difficult to reconcile with the printed circuit board technology used to manufacture the motherboard.
[0024] Different techniques are known for forming space transformers, which typically have a very small thickness, in the range of 0.5 mm to 3 mm, and in particular have problems with planarity.
[0025] More specifically, a first known solution is a ceramic-based technology or MLC (acronym for “MultiLayerCeramic”) that forms multiple layers of rigid ceramic material with high planarity, interspersed with conductive layers that connect contact pads formed on opposite faces of the space transformer.
[0026] In the MLC type space transformer, the conductive path 6C is formed in particular by means of a suitable construction of conductive layers and non-conductive layers (eg ceramic layers), which overlap and intersect each other.
[0027] Alternatively, instead of a ceramic multilayer MLC, it is also known to form a space transformer by means of an organic multilayer board (MLO, acronym for "MultiLayer Organic") associated with a rigid support, for example bonded to the rigid support, the MLO comprising a plurality of layers of organic material forming a plurality of non-conductive layers on which one or more conductive layers are arranged in a suitable configuration, suitable for forming the conductive paths 6C. The rigid support is preferably a ceramic support.
[0028] The mutual positioning of the elements that make up the probe card is an extremely important parameter for the correct functioning of the probe card itself, and the various technologies used to form these elements introduce flatness problems that complicate the construction of the entire probe card, especially with regard to the mutual positioning of the intermediate board or space transformer with the main board. Even with the presence of reinforcements that make the entire assembly more rigid and strong, it is usually not possible to fully eliminate the flatness defects of the space transformer and ensure its correct and complete contact with the main board.
[0029] This situation is further complicated by the operating temperature of the probe card itself, especially when tests are carried out at extreme temperatures. In fact, in this case, the thermal expansion of these elements that make up the probe card can affect its correct performance, due to the different coefficients of thermal expansion of the different materials that form these said elements. In fact, the elements that make up the probe card are usually fixed to each other with the help of screws, which, especially during temperature tests, can impose constraints on the different plates, causing the probe card to bend and, in turn, to fail as a whole, even reaching the limit of having no contact with the contact pads of the device under test.
[0030] This problem is particularly acute in large probe cards, such as those used to test memory devices such as DRAM, for which the lack of control over the thermal expansion of components can actually cause considerable problems during the testing phase.
[0031] The technical problem to be solved by the present invention is to provide a probe card whose structural and functional characteristics can overcome the limitations and shortcomings of probe cards manufactured by known technologies, especially in the case of large-size probe cards and high-temperature testing, and can ensure the correct flatness of all different probe card components while having a simple and easy-to-assemble structure. Summary of the invention
[0032] The solution idea of the present invention is to provide a probe card, the intermediate board or space transformer of the probe card is composed of multiple independent modules, which can be tested before being assembled into the space transformer and can be discarded in case of failure. The modules are provided with appropriate devices for connecting to the main board or additional supporting structures.
[0033] According to this solution idea, the technical problem is solved by a probe card, which is suitable for being installed in a test device of an electronic device. The probe card includes at least one probe head, which accommodates a plurality of contact probes, each contact probe having at least one first end suitable for abutting against a contact pad of a device under test, as well as a main board and an intermediate board, the intermediate board being connected to the main board and suitable for providing distance space transformation between contact pads formed on opposite surfaces thereof, the intermediate board being a space transformer, characterized in that the space transformer includes a plurality of modules which are plate-shaped and coplanar and structurally and functionally independent of each other, each module having a first side and a second side, the first side facing the probe head and provided with a plurality of first contact pads, with the corresponding second ends of the contact probes abutting against the first side; the second side is opposite to the first side and faces the main board, the second side is provided with a plurality of second contact pads, the plurality of second contact pads are connected to the plurality of first contact pads through electrical connectors formed in the module, and the space transformer includes a connection structure formed at the second side of the module, and the modules have the same thickness.
[0034] More specifically, the present invention includes the following additional and optional features, which may be used alone or in combination as necessary.
[0035] According to one aspect of the present invention, the connection structure of the space transformer may include a plurality of connection regions, each of which is formed corresponding to the second surface of one of the modules.
[0036] Furthermore, the thickness of each connection region along the z-axis orthogonal to the main board may 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 invention, each connection region may comprise a weld.
[0038] Furthermore, each connection region can comprise an adhesive film or glue, which is preferably electrically conductive.
[0039] According to yet another aspect of the present invention, the connection structure may integrally connect the module of the space transformer to the main board at a surface of the main board that faces the probe head.
[0040] In particular, the surface roughness of the face of the main board integrally connected to the module is less than 5 microns.
[0041] According to another aspect of the present invention, the space transformer may further include a support, and the connection structure may integrally connect the module of the space transformer to the support at a surface of the support facing the probe head, and the support is integrally connected to the main board.
[0042] In particular, the surface roughness of the face of the support integrally connected to the module may be less than 5 micrometers, preferably less than 1 micrometer.
[0043] According to another aspect of the present invention, the space transformer may further include a plurality of partition elements coplanar with the modules, the partition elements being inserted and interspersed in the modules in a checkerboard configuration, each partition element separating a pair of modules.
[0044] In particular, each partition element may include a connection region formed corresponding to a surface thereof facing the main board, the connection region of the partition element being included in the connection structure of the space transformer.
[0045] According to another aspect of the invention, at least one of the separation elements may comprise an active and / or passive component, preferably a capacitor.
[0046] Furthermore, according to another aspect of the present invention, each connection region may be formed by means of a single region, or may include a plurality of connection regions that are separate from each other and arranged on the second face of the module.
[0047] According to another aspect of the invention, each of the modules has a plate-like shape, in particular a prism shape with a rectangular or hexagonal base.
[0048] Finally, according to another aspect of the invention, each of the modules may comprise at least one multilayer, preferably an organic multilayer MLO.
[0049] In addition, the technical problem is solved by a space transformer, which is suitable for being inserted into a probe card of a test equipment for electronic devices, and is characterized in that the space transformer includes a plurality of plate-shaped and coplanar modules that are structurally and functionally independent of each other, each module having a first side provided with a plurality of first contact pads and a second side opposite to the first side, the second side being provided with a plurality of second contact pads connected to the plurality of first contact pads through electrical connectors formed in the module, and the space transformer includes a connection structure formed corresponding to the second side of the module, and the modules have the same thickness.
[0050] According to another aspect of the present invention, the connection structure may include a plurality of connection areas, each connection area corresponding to the second surface of one of the modules.
[0051] According to yet another aspect of the invention, the thickness of each connection region may 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 may include a soldering or adhesive film or glue, which is preferably electrically conductive.
[0053] The space transformer may further include a support member, and the connection structure connects the module as a whole to a corresponding surface of the support member.
[0054] In particular, the face of the support element integrally connected to the module has a surface roughness of less than 5 micrometers, preferably less than 1 micrometer.
[0055] According to another aspect of the present invention, the space transformer may further include a plurality of partition elements coplanar with the modules, the partition elements being inserted and interspersed in the modules in a checkerboard configuration, each partition element separating a pair of modules.
[0056] According to another aspect of the present invention, each partition element may include a connection region aligned with and correspondingly formed on the second face of the module, the connection region of the partition element being included in the connection structure of the space transformer.
[0057] According to a further aspect of the invention, at least one of the separation elements may comprise an active and / or passive component, preferably a capacitor.
[0058] Furthermore, according to another aspect of the present invention, each connection region may be formed by a single region, or may include a plurality of connection regions that are separate from each other and arranged on the second face of the module.
[0059] According to another aspect of the invention, each of the modules may have a plate-like shape, in particular a prism shape with a rectangular or hexagonal base.
[0060] Finally, according to another aspect of the invention, each of the modules may comprise at least one multilayer, preferably an organic multilayer MLO.
[0061] Features and advantages of the probe card and the space transformer according to the invention will become apparent from the following description of exemplary embodiments given by way of non-limiting examples with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0062] In the attached picture: Figure 1 shows a schematic cross-sectional view of a probe card including vertical probe heads formed according to the prior art; Figure 2A shows a schematic cross-sectional view of a probe card according to one embodiment of the present invention; Figure 2B shows a schematic cross-sectional view of a probe card according to an alternative embodiment of the present invention; Figure 3A A top perspective view of the middle plate is shown. Figure 2A or Figure 2B A space transformer included in the probe card; Figure 3B A top perspective view of an alternative embodiment of an intermediate plate is shown. Figure 2A or Figure 2B A space transformer included in the probe card; FIG. 4A to FIG. 4B and FIG. 5A to FIG. 5B The corresponding cross-sectional views of alternative embodiments of the intermediate plate are shown respectively. Figure 2A and Figure 2B A spatial transformer included in a probe card; and Fig. 6A and Figure 6B A corresponding top axonometric view showing an alternative embodiment of a module contained in an intermediate plate, the intermediate plate being Figure 2A or Figure 2B The probe card has a spatial transformer. DETAILED DESCRIPTION
[0063] With reference to the accompanying drawings, in particular Figure 2AThe probe card includes at least one probe head provided with a plurality of contact probes for testing electronic devices, especially electronic devices integrated on a wafer. The probe card is formed according to the present invention and is generally indicated by 20.
[0064] It should be noted that these drawings represent schematic diagrams of a card according to the invention and are not drawn to scale but rather are drawn in order to emphasize the important features of the invention.
[0065] Furthermore, the different aspects of the invention shown by way of example in the drawings may obviously be combined with one another and interchanged from one embodiment to another.
[0066] Specifically, if Figure 2A As shown, the probe card 20 includes a probe head 21 that accommodates a plurality of contact probes 22. In the example shown in the drawings, the probe head 21 is of a vertical type, and it includes at least one upper plate or upper guide 24 and a lower plate or lower guide 25, which have respective upper guide holes 24A and lower guide holes 25A through which the contact probes 22 slide.
[0067] As conventional in the technical field of the present invention, the term “lower guide” refers to a guide arranged closer to a device under test, and the term “upper guide” refers to a guide arranged closer to a test equipment connected to a probe card including a probe head.
[0068] The probe head 21 further includes a receiving member or housing 29 adapted to receive the contact probe 22 and integrally connect the upper guide 24 and the lower guide 25 .
[0069] exist Figure 2A In the example shown, the probe head 21 also includes an intermediate plate or intermediate guide 26, which is arranged in parallel between the upper guide 24 and the lower guide 25, in particular closer to the latter, and the intermediate guide 26 is also provided with intermediate guide holes 26A, through which the contact probe 22 slides. The three guide embodiments are given only as examples, and the probe head 21 can include any number of guides greater than or equal to 1.
[0070] Each of the contact probes 22 includes, in particular, at least one first end or contact tip 22A, which is suitable for abutting against a corresponding contact pad 23A of a device under test 23, in particular a device under test integrated on a semiconductor chip 23', so as to establish the required contact, in particular electrical contact, between the contact probe 22 of the probe head 21 and the contact pad 23A of the device under test 23.
[0071] Each contact probe 22 also includes a second end or contact head 22B, which is suitable for establishing contact with the main board 27 or main printed circuit board to connect with the test equipment (not shown). The rod-shaped probe body 22C is arranged between the contact head 22B and the contact tip 22A, substantially along the longitudinal development direction of the contact probe 22, which is particularly orthogonal to the plane in which the device under test 23 is arranged.
[0072] The probe card 20 comprises an intermediate plate arranged between the probe head 21 and the main board 27 and adapted to perform spatial transformations, in particular with respect to the distribution of contact pads on its opposite faces and thus represented by a spatial transformer 30. Suitably, according to the invention, said spatial transformer 30 is divided into a plurality of modules 40, which are coplanar, structurally and functionally independent of each other, each of said modules 40 being plate-shaped (referring to physical products rather than abstract geometric entities, so that process tolerances are always taken into account) and arranged between the probe head 21 and the main board 27, the modules 40 having the same thickness S2, i.e. the same dimension along the z-axis orthogonal to the development plane of the device under test 23, except for the dimensional tolerances associated with the process of forming said modules 40, which still refers to physical products.
[0073] The probe card 20 also includes a stiffener 28 associated with the main board 27 to improve its planarity, which is particularly useful in the case of temperature testing.
[0074] Suitably, each module 40 has a first face F1 facing the probe head 21 (under working conditions, 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 equipment) and comprising a plurality of first contact pads, also indicated as probe side pads 40A, against which the contact heads 22B of the contact probes 22 abut. Furthermore, each module 40 has a second face F2, opposite to the first face F1 and therefore (under working conditions) facing the main board 27, for connection with the test equipment, said second face F2 in turn comprising a plurality of second contact pads, also indicated as tester side pads 40B, which are connected to the plurality of probe side pads 40A by means of corresponding electrical connections 40C formed in the module 40. The first face F1 and the second face F2 of each module 40 have a larger surface extension, preferably much larger, relative to the other sides of the module 40, and the module 40 is substantially tile-shaped, and the modules 40 are arranged to cover a required area of the space transformer 30 through the probe card 20 including the space transformer 30, and the area corresponds to the area of the semiconductor wafer 23' including the device under test 23. All modules 40 form a plate-shaped space transformer 30, which is similar in size (especially thickness) to a one-piece space transformer formed according to the prior art, but has a larger overall surface extension, and is particularly suitable for testing memory devices such as DRAM.
[0075] Advantageously, according to the invention, each module 40 further comprises at least one connection area 41, which is arranged on the second face F2 of the module 40 and is suitable for connecting the module 40 as a whole to the main board 27. All the connection areas 41 of a plurality of modules 40 form a connection structure 31 of the space transformer 30, which connection structure 31 is suitable for connecting the module 40 as a whole to the main board 27.
[0076] In a preferred embodiment, the connection region 41 is welded. Alternatively, the connection region 41 can be formed by means of an adhesive film or glue, preferably an electrically conductive adhesive film or glue.
[0077] Suitably, the connection area 41 is arranged, in particular in a substantially planar manner, on the second face F2 of the module 40, so as to ensure the correct positioning of the module 40 relative to the z-axis, which is orthogonal to the main board 27 and in particular to its face F3 facing the probe head 21. Furthermore, the connection area 41 has a thickness S1 along the z-axis which is negligible compared to the thickness S2 of each module 40 along the same axis, so as to reduce the overall size of the connection structure 31, which includes the connection areas 41 of all the modules 40 included in the space transformer 30, and moreover maintains its planarity relative to the main board 27. In particular, the thickness S1 of the connection area 41 is less than 10%, preferably less than 1%, of the thickness S2 of the module 40, the thickness being the dimension of the connection area 41 and of the module 40, respectively, along the z-axis. In this case, the ratio between the thicknesses should also be understood as net of the machining tolerances, which should always be taken into account when discussing physical products rather than abstract geometric entities.
[0078] According to one embodiment, the face F3 of the main board 27 is suitably formed with a flatness that ensures the correct alignment of the modules 40 in the z direction, in particular with a surface roughness Ra less than 5 microns. It can also be provided that the face F3 of the main board 27 is subjected to a planarization treatment suitable for reducing its surface roughness to the above-mentioned desired value.
[0079] It is emphasized that the use of the connection area 41 formed on the second face F2 of the module 40 allows the module 40 to be easily positioned on the face F3 of the main board 27, for example by means of a spatial positioning method, in particular an optical alignment method, which makes it possible to accurately determine the position of the module 40 on the face F3 of the main board 27. Suitably, the modules 40 are configured to be placed side by side so as not to leave gaps or empty areas in the space transformer 30, always without affecting any process tolerances.
[0080] exist Figure 2B In another preferred alternative embodiment of the invention shown, the space transformer 30 also comprises a support 32 to which the module 40 is integrally connected by means of respective connection areas 41 (in particular the face F4 of the support 32 facing the probe head 21 in operating conditions).
[0081] Suitably, the support 32 can be formed using techniques and materials that ensure adequate planarity on the face F4 where the module 40 is assembled, in particular a surface roughness Ra less than 5 microns. It should be emphasized that the support 32 cannot be formed according to printed circuit board technology and can therefore comprise materials suitable for more easily reaching the required roughness values, and a surface roughness RA value less than 1 micron, without requiring further planarization processes.
[0082] Thus, the support 32 is connected to the mainboard 27 according to any technique known in the art, such as welding, using an adhesive film or glue, in particular a conductive adhesive film or glue, or even by means of a mechanical screw system, the correct positioning of the module 40 being ensured by connecting the module 40 as a whole to the support 32 itself by means of the connecting structure 31.
[0083] It is to be emphasized that, advantageously, according to the invention, the space transformer 30 is formed by means of a plurality of modules 40, structurally and functionally independent of one another, correctly positioned in the space xyz by means of a connection structure 31 which integrally connects these modules 40 to the main board 27 or to the support 32. Thus, the production of the individual modules, which can be manufactured and tested before being assembled in the space transformer 30, is simplified, thus reducing the final manufacturing costs of the space transformer 30. Furthermore, it is possible to form the space transformer 30 of considerable dimensions, for example for testing memory devices such as DRAMs, while keeping the thickness of the space transformer 30 reduced, in particular substantially equal to the thickness S2 of each module 40, without generating the problems of planarity of the monolithic space transformers formed according to the prior art.
[0084] Advantageously, each module 40 can be formed by one of the techniques used in the field for forming space transformers. Preferably, each module 40 is formed by means of a multilayer, preferably an organic multilayer MLO.
[0085] Figure 3A The positioning of the space transformer 30 and its modules 40 is shown in simplified top view when the probe card 20 is used to test a semiconductor wafer 23' including a plurality of devices under test 23, and in the example shown in the figure, the contact pads 23A are arranged corresponding to two opposite sides of each device under test 23. In this figure, the probe card 20 is shown without the main board 27 and the stiffener 28.
[0086] according to Figure 2A and Figure 2B In the embodiment, the cross-sectional views of the space transformer 30 are respectively as shown in Figure 4A and Figure 4B In particular, Figure 4A The space transformer 30 comprises a plurality of modules 40 which are respectively integrally connected to the main board 27 by means of a plurality of connection areas 41 forming a connection structure 31 , in particular on the face F3 of the main board 27 .
[0087] As described above, the space transformer 30 includes a plurality of modules 40, which are adjacent to each other and are provided with a plurality of first probe side pads 40A formed corresponding to the first face F1 of the module 40 (under working conditions) facing the probe head 21 and a plurality of second tester side pads 40B formed corresponding to the second face F2 of the module 40 (always under working conditions) facing the main board 27, the plurality of first probe side pads 40A and the plurality of second tester side pads 40B being connected to each other by means of suitable electrical connectors 40C. The space transformer 30 also includes a plurality of connection areas 41, which are formed corresponding to the second face F2 of the module 40 and are suitable for forming the connection structure 31 of the space transformer 30.
[0088] More specifically, in Figure 4A In the embodiment of the present invention, each module 40 comprises a connection area 41 which integrally connects the module 40 to the main board 27 corresponding to the face F3 of the main board 27 (under working conditions) facing the probe head 21, while Figure 4B In the embodiment of the present invention, each module 40 includes a connection area 41, which integrally connects the module to the support 32 corresponding to the face F4 of the support 32 facing the probe head 21 (under working conditions), and the support 32 is integrally connected to the main board 27 corresponding to the face F3 of the main board 27.
[0089] It is also possible to use the space transformer 30 to form a probe card 20 that can test a device under test 23 having contact pads 23A arranged along all four sides thereof (i.e., a so-called full array configuration); in this case, the space transformer 30 includes a plurality of spacer elements 42 whose dimensions (especially thickness) correspond to the dimensions (especially thickness) of the module 40, and are coplanar with the module 40 and interspersed together in a checkerboard configuration, such as Figure 3B As shown in the schematic diagram in . In fact, in this case, the contact probes 22 of the probe head 21 associated with the space transformer 30 can be appropriately interspersed and spaced so as to test the contact pads 23A of the device under test 23 in a full array configuration, and at the same time ensure that the contact probes 22 do not interfere with each other mechanically or electrically, so that the signals provided to the contact probes 22 are correctly routed. In a preferred embodiment, the partition element 42 is also integrally connected to the main board 27 or the support 32 by means of a corresponding connection area 41 arranged on the surface F2 of the support 32 (in the working state) facing the main board 27.
[0090] Furthermore, one or more of the separation elements 42 may include additional active or passive components, such as capacitors, which may add additional performance to the space transformer 30, such as signal filtering.
[0091] As described above, the space transformer 30 includes a plurality of modules 40, which are provided with a plurality of first probe side pads 40A and a plurality of second tester side pads 40B, wherein the plurality of first probe side pads 40A are formed on the first face F1 of the module facing the probe head 21 (under working conditions), and the plurality of second tester side pads 40B are formed on the second face F2 facing the main board 27 (always under working conditions). The plurality of first probe side pads 40A and the plurality of second tester side pads 40B are connected to each other by means of suitable electrical connectors 40C. The space transformer 30 also includes a plurality of partition elements 42, which are coplanar with the modules 40 and interspersed in a checkerboard configuration, and each partition element 42 is inserted between two modules 40 and partitions the two modules 40.
[0092] The connection structure 31 of the space transformer 30 is formed corresponding to the plurality of connection regions 41 formed on the second face F2 of the module 40 .
[0093] More specifically, in Figure 5A In the embodiment of the present invention, each module 40 comprises a connection area 41 which connects the module integrally to the main board 27 at the face F3 of the main board 27 (under working conditions) facing the probe head 21, and Figure 5B In the embodiment, each module 40 includes a connection area 41, which connects the module 40 to the support member 32 as a whole at the surface F4 of the support member 32 (under working conditions) facing the probe head 21, and the support member 32 is correspondingly connected to the main board 27 as a whole, especially at the surface F3 of the main board 27.
[0094] Preferably, each partition element 42 also comprises a connection zone 41 corresponding to the second face F2 facing the main board 27 (in operating conditions).
[0095] It is possible to form a connection region 41 having a single region, such as Fig. 6A Schematically shown in FIG. 4 , where for simplicity, only one module 40 is shown. Alternatively, the connection area 41 may include a plurality of connection areas 41 a that are separate from each other and arranged on the second face F2 of the module 40 .
[0096] Furthermore, it should be emphasized that, in addition to Fig. 6A and Figure 6B In addition to the prism shape with a rectangular base shown, a single module 40 can also be made into other shapes (such as a prism shape with a hexagonal base), as well as multiple modules with a hexagonal base, and multiple modules with a hexagonal base can be placed side by side to effectively cover the required area of the space transformer 30.
[0097] In summary, advantageously, according to the invention, a probe card is obtained which is provided with a space transformer formed by means of a plurality of modules which are structurally and functionally independent of one another.
[0098] Each module is clearly easier to manufacture than a large space transformer, and simplified and advantageously testable (and therefore potentially disposable) wiring is performed via internal electrical connections before it is assembled into the final space transformer, which has clear advantages from a cost and production yield perspective. In addition, individual modules can be formed to be identical to each other, thereby improving the overall performance of the space transformer.
[0099] Furthermore, advantageously, according to the invention, each module can be integrally connected to a main board in a simple manner thanks to a connection structure formed by a plurality of connection areas, preferably welding areas, which allow the planarity of the space transformer thus obtained to be ensured.
[0100] In an advantageous alternative embodiment, the space transformer further comprises a support member, which can be formed by means of a technique and material that can improve the flatness of its surface, so as to ensure a more precise positioning of the modules forming the space transformer in the z direction.
[0101] Therefore, the probe card according to the present invention is suitable for applications requiring testing of large wafers and devices having a large number of pads.
[0102] Furthermore, according to another advantageous alternative embodiment, the modules are arranged interspersed with separation elements so as to allow correct routing of contact probes adapted to abut on contact pads arranged on all four sides of the device under test, as in the case of full array testing.
[0103] Obviously, in order to meet accidental and specific requirements, those skilled in the art may make various modifications and substitutions to the above-mentioned probe card and space transformer, all of which belong to the protection scope of the present invention as defined by the following claims.
Claims
1. A probe card (20) suitable for installation in a test device of an electronic device, the probe card (20) comprising: At least one probe head (21) accommodating a plurality of contact probes (22), each contact probe (22) having at least one first end (22A) adapted to abut against a contact pad (23A) of a device under test (23); and a main board (27) and an intermediate board, the intermediate board being connected to the main board (27) and adapted to provide distance space transformation between contact pads formed on opposite surfaces thereof, the intermediate board being a space transformer (30), characterized in that the space transformer (30) comprises a plurality of modules (40) which are plate-shaped and coplanar and are structurally and functionally independent of each other, each module (40) having a first surface (F1) and a second surface (F2), the first surface (F1) facing the probe head (21) and having a A plurality of first contact pads (40A) are arranged, and the corresponding second end portions (22B) of the contact probes (22) abut against the plurality of first contact pads (40A); the second surface (F2) is opposite to the first surface (F1) and faces the main board (27), and the second surface (F2) is provided with a plurality of second contact pads (40B), and the plurality of second contact pads (40B) are connected to the plurality of first contact pads (40A) through electrical connectors (40C) formed in the module (40), and the space transformer (30) includes a connection structure (31) formed corresponding to the second surface (F2) of the module (40), and the module (40) has 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), each of the connection regions (41) being formed corresponding to a second face (F2) of one of the modules (40).
3. The probe card (20) according to claim 2, characterized in that: Each connection region (41) includes one selected from welding, adhesive film, adhesive glue, conductive adhesive film or conductive adhesive glue.
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) at a surface (F3) of the main board (27) that faces the probe head (21).
5. The probe card (20) according to claim 4, characterized in that: The surface (F3) of the main board (27) integrally connected to the module (40) has a surface roughness of less than 5 micrometers.
6. The probe card (20) according to claim 1, characterized in that: The space transformer (30) further comprises a support member (32), and the connection structure (31) integrally connects the module (40) of the space transformer (30) to the support member (32) at a surface (F4) corresponding to the support member (32) facing the probe head (21), and the support member (32) is integrally connected to the main board (27).
7. The probe card (20) according to claim 6, characterized in that: The surface (F4) of the support (32) integrally connected to the module (40) has a surface roughness of less than 5 microns.
8. The probe card (20) according to claim 1, characterized in that: The space transformer (30) further comprises a plurality of partition elements (42) coplanar with the modules (40), the partition elements (42) and the modules (40) being arranged in a checkerboard configuration and interlaced with each other, and each of the partition elements (42) separates a pair of the modules (40).
9. The probe card (20) according to claim 8, characterized in that: Each of the partition elements (42) includes a connection region (41) formed corresponding to its surface (F2) facing the main board (27), and the connection region (41) of the partition element (42) is included in the connection structure (31) of the space transformer (30).
10. The probe card (20) according to claim 9, characterized in that: At least one of the separation elements (42) comprises active components and / or passive components.
11. The probe card (20) according to claim 2, characterized in that Each connection region (41) is formed by means of a single region, or it comprises a plurality of connection regions (41a) which are separated from one another and arranged on the second face (F2) of the module (40).
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, preferably an organic multilayer MLO.
14. A space transformer (30) suitable for being inserted into a probe card (20) of a test equipment for an electronic device, characterized in that: The space transformer (30) comprises a plurality of modules (40) which are plate-shaped and coplanar and are independent of each other in structure and function, each module (40) having a first surface (F1) provided with a plurality of first contact pads (40A) and a second surface (F2) opposite to the first surface (F1), the second surface (F2) being provided with a plurality of second contact pads (40B) connected to the plurality of first contact pads (40A) by means of electrical connectors (40C) formed in the module (40), and the space transformer (30) comprising a connection structure (31) formed corresponding to the second surface (F2) of the module (40), and the module (40) having the same thickness (S2).
15. The space transformer (30) according to claim 14, characterized in that The connection structure (31) comprises a plurality of connection areas (41), each of the connection areas (41) being formed at the second face (F2) of one of the modules (40).
16. The space transformer (30) according to claim 15, characterized in that Each connection region (41) includes one selected from soldering, adhesive film, adhesive glue, conductive adhesive film or conductive adhesive glue.
17. The space transformer (30) according to claim 14, characterized in that It also includes a support member (32), wherein the connection structure (31) integrally connects the module (40) to the support member (32) at a surface (F4) corresponding to the support member (32).
18. The space transformer (30) according to claim 17, characterized in that The surface roughness of the face (F4) of the support (32) integrally connected to the module (40) has a value selected from less than 5 microns or less than 1 micron.
19. The space transformer (30) according to claim 14, characterized in that It also includes a plurality of partition elements (42) coplanar with the modules (40), the partition elements (42) and the modules (40) being arranged in a checkerboard configuration and interlaced with each other, and each of the partition elements (42) separates a pair of the modules (40).
20. The space transformer (30) according to claim 19, characterized in that Each of the partition elements (42) comprises a connection region (41) aligned with the second face (F2) of the module (40) and formed correspondingly thereon, the connection region (41) of the partition element (42) being included in the connection structure (31) of the space transformer (30).