Probe for electrical testing in a defect detection system

Abstract

Fine electrical probes can provide precise pitch applications in devices such as smartwatches and smartphones. A finger is positioned on a substrate. The substrate has recesses that allow the finger to flex. The substrate and the finger are positioned in an assembly. The assembly has recesses that allow the substrate to flex.

Description

Technical Field

[0001] This disclosure relates to probes used for electrical testing. Background Technology

[0002] Multi-electrode probes are typically used to determine one or more electrical parameters of a test sample. When performing these measurements, the multi-electrode probe contacts the sample surface to establish an electrical contact. Liquid crystal display (LCD) panels incorporate liquid crystals that exhibit electric field-dependent light modulation properties. They are frequently used to display images and other information in a variety of devices, including fax machines, laptop computer screens, telephones, tablet computers, watches, and large-screen high-definition televisions. Active-matrix LCD panels have a complex layered structure that may contain several functional layers, including a polarizing film; a thin-film transistor (TFT) glass substrate incorporating thin-film transistors, storage capacitors, pixel electrodes, and interconnects; an alignment film made of polyimide; and the actual liquid crystal material incorporating plastic / glass spacers to maintain the appropriate LCD cell thickness. LCD panels are manufactured under highly controlled conditions in a cleanroom environment to maximize throughput. Nevertheless, many LCDs are discarded due to manufacturing defects.

[0003] To increase the yield of complex electronic devices (such as LCD panels), various inspection stages are performed to identify defects that can occur during different stages of the manufacturing process. These inspection stages can be performed between manufacturing stages or after the entire manufacturing process is completed. An example of an inspection process is testing for electrical defects in TFT arrays used in LCD and OLED displays. Various inspection devices are used to perform these tests.

[0004] Electrical testing systems typically require the device under test (DUT) to be driven by electrical signals or patterns that facilitate defect detection. These signals are transmitted from a pattern generator subsystem to the DUT using a structure that carries probe fingers that physically contact contact pads located around the active area of ​​the DUT.

[0005] Previous electrical testing techniques used spring-loaded pins, which were spring-loaded plungers. These pins could not be reduced to diameters below a few hundred micrometers. This size limitation did not allow for a reduction in probe pitch and size. Furthermore, the spring-loaded pins were mechanically mounted on machined plastic substrates. The machining of plastic substrates limited precision and resolution.

[0006] Therefore, new systems and technologies are needed. Summary of the Invention

[0007] A probe is disclosed in a first embodiment. The probe includes: a substrate defining a contact surface and a substrate recess at a distal end of the substrate; a plurality of fingers disposed on the contact surface; and an assembly configured to hold the substrate and the fingers. The fingers extend beyond the distal end of the substrate and across the substrate recess. As the fingers extend across the substrate recess, they are spaced apart from the substrate. The assembly defines an assembly recess. The substrate is spaced apart from the assembly within the assembly recess.

[0008] The fingers may be made of BeCu. The substrate may be ceramic.

[0009] The assembly defines an aperture. The probe may include a limiter disposed within the aperture. The limiter is configured to extend into a recess in the assembly and limit the deflection of the substrate. The limiter may be made of metal.

[0010] The probe may include an electrical connector that is electrically connected to the plurality of fingers. The electrical connector is disposed in the assembly.

[0011] The probe may include at least one spring disposed in the recess of the assembly between the substrate and the assembly.

[0012] The substrate recess can extend from the contact surface into the substrate by 25 μm to 100 μm.

[0013] The fingers may extend 50 μm to 200 μm beyond the distal end of the substrate.

[0014] Each of the fingers may have a width ranging from 10 μm to 20 μm.

[0015] The fingers may have a thickness of 30 μm to 150 μm extending from the contact surface.

[0016] Each of the fingers may have a conical or truncated conical cross-section, the cross-section having a first outer surface and a second outer surface opposite to the first outer surface. The second outer surface is wider than the first outer surface.

[0017] The distance between the finger and the substrate in the substrate recess can be greater than zero and less than 1 mm.

[0018] A second embodiment provides a method. The method includes contacting an electrical device with a probe comprising a plurality of fingers (e.g., BeCu) disposed on a substrate. The fingers are flexed within substrate recesses of the substrate. The fingers and the substrate are flexed within assembly recesses configured to hold an assembly of the fingers and the substrate. Measurements of an electrical test of the electrical device are received using the probe.

[0019] The method may include applying tension between the substrate and the assembly using at least one spring disposed in a recess of the assembly between the substrate and the assembly.

[0020] The fingers can flex 25 μm to 100 μm across the recess in the substrate.

[0021] The substrate can flex up to 50 μm across the recess of the assembly.

[0022] The electrical device may be a screen or a flat panel display. Attached Figure Description

[0023] For a more complete understanding of the nature and purpose of this disclosure, reference should be made to the following detailed description in conjunction with the accompanying drawings, wherein:

[0024] Figure 1A An embodiment of a probe that includes components but not assemblies is shown;

[0025] Figure 1B Showcases components with modular parts;

[0026] Figure 1C exhibit Figure 1B The reverse view of the assembly in the middle;

[0027] Figure 2A This is a side cross-sectional view of an embodiment of the probe;

[0028] Figure 2B yes Figure 2A Front view of the probe in the image;

[0029] Figure 2C yes Figure 2A Top perspective view of the probe;

[0030] Figure 2D yes Figure 2A Cross-sectional view of the probe's fingers and the substrate;

[0031] Figure 3 It is a top view of the fingers extending beyond the substrate;

[0032] Figure 4 This is an example of a finger-shaped object cut from a foil on a substrate;

[0033] Figure 5 Examples of finger-shaped objects;

[0034] Figure 6 Showing the finger-shaped object as magnification increases;

[0035] Figure 7 A top view showing an embodiment of the substrate;

[0036] Figure 8 This is a view of a cavity in a substrate; and

[0037] Figure 9 This is a flowchart of an embodiment of the method according to the present disclosure. Detailed Implementation

[0038] While the claimed subject matter will be described with reference to certain embodiments, other embodiments, including those that do not provide all the benefits and features set forth herein, are also within the scope of this disclosure. Various structural, logical, process, and electronic modifications may be made without departing from the scope of this disclosure. Therefore, the scope of this disclosure is defined only by the appended claims.

[0039] The embodiments disclosed herein provide fine electrical probes (e.g., 20 μm) that enable precise distance electrical measurement applications in devices such as smartwatches and smartphones. Smartwatches, smartphones, and other screens or tablets can benefit from probes with finer tips. Compared to previous designs, the size, shape, and flexibility of the fingers and associated components can improve accuracy and resolution.

[0040] Figures 1A to 1C and Figures 2A to 2D An embodiment of probe 100 is shown. Probe 100 includes a substrate 101, which defines a contact surface 106 and a substrate recess 107 at a distal end 107 of the substrate 101. The substrate 101 may be made of ceramic, such as Al2O3, AlN, BeO, glass, silicon dioxide, or other insulating materials.

[0041] Finger 102 is disposed on contact surface 106 of substrate 101. Finger 102 extends beyond distal end 111 of substrate 101 and crosses substrate recess 107. When finger 102 extends across substrate recess 107, finger 102 is spaced apart from substrate 101.

[0042] In this example, the finger 102 is made of BeCu. BeCu provides improved properties in terms of fatigue resistance, wear resistance, and weldability. The finger 102 can also be made of other materials, such as high-hardness steel coated with electroless nickel plating.

[0043] The fingers 102 can be fabricated using a femtosecond laser or chemically etched. In this example, a 50-100 μm thick BeCu foil is used to form multiple fingers 102, each finger 102 having a width of 10 μm or greater and a length of several hundred micrometers. The fingers 102 can extend into a fan shape, with the width increasing as it extends, such as... Figure 5 As shown in the image.

[0044] In this example, the finger 102 is bonded to the substrate 101 prior to microfabrication. Figure 4 Displaying the forming finger-like structure 102. Figure 4 Some foil has been removed. The bonded and micro-machined sandwich structure comprising fingers 102 and substrate 101 has protruding fine fingers 102 at one end and the same number of wider pads at the other end of substrate 101. These pads can be used as portions of electrical connections.

[0045] Assembly 103 is configured to hold substrate 101 and fingers 102. Assembly 103 defines an assembly recess 108. Substrate 101 is spaced apart from assembly 103 in assembly recess 108. Assembly recess may have a depth configured to allow angular deflection of substrate 101 of 3° to 5° or 3° to 7°. Substrate 101 may be positioned downwards from assembly 103 in assembly recess 108 at this downward angle, as shown in… Figure 2A In the middle. When the finger 102 is pressed during the test, the distance between the substrate 101 and the assembly 103 in the assembly recess 108 can be close to zero or even zero.

[0046] The substrate 101 can be soldered to the electrical connector 105, which can be connected to the assembly 103. For example, the substrate 101 and the electrical connector 105 can be bolted to the assembly 103. When the substrate 101 is connected to the assembly 103, it may include fingers 102.

[0047] In this example, assembly 103 can be made of anodized aluminum, but other materials are also feasible. The anodized aluminum can be 6061-T6 aluminum.

[0048] Assembly 103 may define a hole 109 through its body. Hole 109 may extend from the upper surface of assembly 103 to assembly recess 108. Restrictor 104 may be disposed in hole 109. Restrictor 109 is configured to extend into assembly recess 108 and restrict flexure of substrate 102. Restrictor 109 may prevent excessive deflection of substrate 101 and fingers 102.

[0049] The limiter 104 may be made of metal, ceramic, or plastic. The limiter 104 is connected to the assembly 103, for example, by gluing, welding, or mechanically securing the components.

[0050] Electrical connector 105 is electrically connected to finger 102. Electrical connector 105 may be housed in assembly 103. In this example, finger 102 may be soldered to a printed circuit board (PCB) serving as electrical connector 105, which electrically connects the probe sandwich structure (i.e., finger 102 and substrate 101) to the measuring tool. Hot rod technology may be used for soldering.

[0051] The flexural travel can be correlated with the maximum stress in the finger 102. The connection between the finger 102 and the electrical connector 105 can be configured to operate when the finger 102 is under maximum stress. If the extension exceeds the maximum stress, the finger 102 may break or bend.

[0052] The contacts between the PCB and the mezzanine structure (i.e., the fingers 102 and the substrate 101) connected in the electrical connector 105 can also serve as flexible portions, allowing the mezzanine structure to flex in the Z direction (see [reference]). Figure 2A and 2D The deflection is approximately 1000 μm. For example, see [link / reference]. Figure 2A The diving angle α in the diagram.

[0053] At least one spring 110 may be used in the probe 100. In an embodiment, two springs 110 are disposed in the assembly recess 108 between the substrate 102 and the assembly 103. At least one spring 110 generates a preload on the deflected sandwich structure (i.e., the finger 102 and the substrate 101), which ensures a predefined probing force and also provides the desired contact resistance. The spring 110 may have a force from 0.1 to 0.3 N, but other values ​​are also possible.

[0054] In this example, the substrate recess 107 extends from the contact surface 106 into the substrate 101 to a depth of 25 μm to 100 μm. For example, a depth of 50 μm to 100 μm can be used. In this example, the distance between the surface of the finger 102 and the opposite surface of the substrate 101 in the substrate recess 107 is greater than zero and less than 1 mm. This refers to the finger not being flexed.

[0055] Figure 3 This is a top view of the finger 102 extending beyond the substrate 101. The finger 102 may extend beyond the distal end 107 of the substrate 101 by 50 μm to 200 μm. In this example, the finger 102 extends beyond the distal end 107 of the substrate 101 by approximately 100 μm. The final width of the individual finger 102 of the contact device may range from 15 to 50 μm.

[0056] Figure 6The finger 102 is shown at increased magnification. Each of the fingers 102 may have a width from 10 μm to 300 μm. For example, the width may be from 10 μm to 20 μm. Each of the fingers may have a height from 30 μm to 150 μm (e.g., the thickness extending from the contact surface 106). The geometry of the finger 102 may be adjusted depending on the height and width to accommodate the stress, deflection, and lifespan of the finger. This reduces the likelihood of breakage.

[0057] Two deflection regions may exist for the finger 102. First, the fine finger 102 can be deflected to 50 μm to 100 μm by its position in the substrate recess 107. Second, the portion of the finger 102 connected to the electrical connector 105 can be deflected using the assembly 103 and the limiter 104. The portion of the finger 102 connected to the electrical connector 105 can move 500 μm to 1000 μm. The portion of the finger 102 extending beyond the distal end 111 of the substrate 101 can be deflected by approximately 200 μm.

[0058] like Figure 6 As shown, each of the fingers 102 has a conical or truncated conical cross-section, a first outer surface, and a second outer surface opposite to the first outer surface. The second outer surface (i.e., Figure 6 The bottom of the middle) is larger than the first outer surface (i.e., Figure 6 (Top width)

[0059] Laser processing typically produces a conical shape in the finger 102 due to its optical numerical aperture (N / A). The tip width of the finger 102 can be small enough to touch the pad of the device. The entire finger 102 can be as wide as possible within the permissible pitch to avoid lateral movement, which is at least partially provided by the conical shape.

[0060] Figure 7 A top view showing an embodiment of substrate 101. The angle with the rectangular portion of substrate 101 can be approximately 45°. The width of the distal end of the substrate from which the fingers extend can be from 2 mm to 5 mm. Substrate 101 can have a shape similar to a fan-out foil, which can reduce weight.

[0061] Figure 8 This is a view of the recesses in the substrate. Each finger can be positioned opposite a recess machined into the substrate. One or more micro-machined (“engraved”) recesses in the substrate 101 can limit localized deflection of the finger 102. The recesses act as a barrier, preventing the finger 102 from deflecting after contact with the inspected glass. For a 1000 μm protruding finger 102, the engraved recesses can limit deflection to a maximum of 50 μm.

[0062] Although Figure 8 Individual recesses can be shown, but a single recess spanning the width of the finger can also be used.

[0063] The embodiments disclosed herein provide improved finger sizes for probes. Geometry different from existing spring-loaded needles is feasible. Lifespan and contact resistance can be configured by controlling the contact force. In examples, the probe embodiments disclosed herein may be field-replaceable consumable parts.

[0064] Microfabricated precision finger probes offer advantages over previous designs. A single foil can be used to form the fingers, providing a patterned distribution from the finger itself to the flexed portion and / or the PCB contact. The fingers can also provide both flexed and PCB contact. Under preload, the entire ceramic movement on the flexed portion can be mechanically (adjustably) limited to 500 μm, which determines the contact resistance. Further reductions in probe block do not apply additional force to the fingers.

[0065] Figure 9 This is a flowchart of an embodiment of method 200, which may use an embodiment of probe 100. At 201, an electrical device is contacted with a probe comprising a plurality of fingers disposed on a substrate. The electrical device may be, for example, a screen or flat panel display. The fingers may be BeCu. At least one probe is mounted on a tool platform. The tool platform may include a beam that travels over the electrical device and is movable to move further and closer to the surface of the electrical device to establish contact. When lowered, the fingers of the probe contact conductors on the electrical device, which provides an electric field for inspection.

[0066] At 202, the fingers are flexed within a substrate recess of the substrate. At 203, the fingers and the substrate are flexed within an assembly recess configured to hold the assembly of the fingers and the substrate. Steps 202 and 203 may occur in any order or at least partially simultaneously. The fingers may flex across the substrate recess by 25 μm to 100 μm. The substrate may flex across the assembly recess by a maximum of 50 μm.

[0067] In this example, the finger 102 can be deflected by up to 100 μm (all or individually to adapt to reduced pressure). The substrate 102 can be deflected as a whole from 500 μm to 1000 μm to allow for tooling inaccuracies.

[0068] At position 204, a probe is used to receive measurements of the electrical test of the electrical device. These measurements can be received by a processor for analysis. The processor can be a computer or part of another system.

[0069] Tension can be applied between the substrate and the assembly using at least one spring disposed in the recess of the assembly between the substrate and the assembly.

[0070] Although this disclosure has been described with respect to one or more specific embodiments, it should be understood that other embodiments of this disclosure may be made without departing from the scope of this disclosure. Therefore, this disclosure is considered to be limited only by the appended claims and their reasonable interpretation.

Claims

1. A probe comprising: a substrate defining a contact surface and a substrate recess at a distal end of the substrate; a plurality of fingers disposed on the contact surface, wherein the fingers extend beyond the distal end of the substrate and across the substrate recess, and wherein the fingers are spaced apart from the substrate when the fingers extend across the substrate recess; and an assembly configured to hold the substrate and the fingers, wherein the assembly defines an assembly recess, and wherein the substrate is positioned in the assembly recess from the assembly in a downward manner by a dive angle of 3° to 7° such that the substrate is spaced apart from the assembly in the assembly recess.

2. The probe of claim 1, wherein the fingers are made of BeCu.

3. The probe of claim 1, wherein the substrate is ceramic.

4. The probe of claim 1, wherein the assembly defines a hole and further comprises a limiter disposed in the hole, wherein the limiter is configured to extend into the assembly recess and limit flexing of the substrate by contacting the substrate.

5. The probe of claim 4, wherein the limiter is made of metal.

6. The probe of claim 1, further comprising an electrical connector in electrical communication with the plurality of fingers, wherein the electrical connector is disposed in the assembly.

7. The probe of claim 1, further comprising at least one spring disposed between the substrate and the assembly in the assembly recess.

8. The probe of claim 1, wherein the substrate recess extends into the substrate from the contact surface by 25 pm to 100 pm.

9. The probe of claim 1, wherein the fingers extend beyond the distal end of the substrate by 50 pm to 200 pm.

10. The probe of claim 1, wherein each of the fingers has a width of from 10 pm to 20 pm.

11. The probe of claim 1, wherein the fingers each have a thickness extending from the contact surface by 30 pm to 150 pm.

12. The probe of claim 1, wherein each of the fingers has a conical or frustoconical cross-section having a first outer surface and a second outer surface opposite the first outer surface, wherein the second outer surface is wider than the first outer surface.

13. The probe of claim 1, wherein a distance between the fingers and the substrate in the substrate recess is greater than zero and less than 1 mm.

14. A method comprising: contacting an electrical device with a probe, the probe including a plurality of fingers disposed on a substrate; flexing the fingers within a substrate recess of the substrate; flexing the fingers and the substrate within an assembly recess of an assembly configured to hold the fingers and the substrate, wherein the substrate is positioned in the assembly recess from the assembly in a downward manner by a dive angle of 3° to 7°; and receiving a measurement of an electrical test of the electrical device using the probe.

15. The method of claim 14, wherein the fingers are made of BeCu.

16. The method of claim 14, further comprising applying tension between the substrate and the assembly using at least one spring disposed in the assembly recess between the substrate and the assembly.

17. The method of claim 14, wherein the fingers flex 25 µm to 100 µm across the substrate recess.

18. The method of claim 14, wherein the substrate flexes at most 50 µm across the assembly recess.

19. The method of claim 14, wherein the electrical device is a screen.

20. The method of claim 14, wherein the electrical device is a flat panel display.

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