Probes for electrical testing in deflection detection systems

Abstract

The precision electrical probe can provide fine pitch applications in devices such as smartwatches and smartphones. Fingers are disposed on a substrate. The substrate has recesses that allow the fingers to flex. The substrate and fingers are disposed in an assembly. The assembly has recesses that allow the substrate to flex.

Description

[Technical Field]

[0001] The present disclosure relates to probes for electrical testing. [Background technology]

[0002] Multi-electrode probes are commonly used to determine one or more electrical parameters of a test sample. When performing such measurements, the multi-electrode probe contacts the sample surface to create electrical contact. Liquid crystal display (LCD) panels incorporate liquid crystals that exhibit electric-field-dependent light-modulating properties. They are frequently used to display images and other information in a wide variety of devices, from fax machines to laptop computer screens, telephones, tablets, watches, and large-screen high-definition televisions. Active-matrix LCD panels are complex layered structures that can contain several functional layers, including a polarizing film; a thin-film transistor (TFT) glass substrate incorporating thin-film transistors (TFTs), storage capacitors, pixel electrodes, and interconnect wiring; an alignment film made from polyimide; and the actual liquid crystal material, incorporating plastic / glass spacers to maintain the proper LCD cell thickness. LCD panels are manufactured in cleanroom environments under highly controlled conditions to maximize yield. Despite this, many LCDs are discarded due to manufacturing defects.

[0003] To improve the production yield of complex electronic devices such as LCD panels, various investigation steps are performed to identify various defects that may occur during various stages of the manufacturing process. These investigation steps can occur between multiple manufacturing stages or after the entire manufacturing process is completed. One example of an investigation process is the testing of TFT arrays used in LCD and OLED displays for electrical defects. Various investigation devices are used to perform the testing.

[0004] Electrical interrogation systems generally require that a device under test (DUT) be driven with electrical signals or patterns that facilitate defect detection. These signals are conveyed from a pattern generator subsystem to the DUT using a structure that carries probe fingers that physically contact contact pads located around the periphery of the DUT's active area.

[0005] Traditional techniques for electrical probing have used pogo pins, which are spring-loaded plungers. These pins cannot be reduced in size below a few hundred microns in diameter. This size does not allow for reduction in probe pitch and size. Additionally, the pogo pins are mechanically mounted on machined plastic carriers. Plastic machining is limited in terms of precision and resolution. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] U.S. Patent Application Publication No. 2015 / 362551 Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, new systems and techniques are needed. [Means for solving the problem]

[0008] In a first embodiment, a probe is disclosed. 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. The fingers are spaced apart from the substrate as they extend across the substrate recess. The assembly defines an assembly recess. The substrate is spaced apart from the assembly at the assembly recess.

[0009] The fingers may be made of BeCu, and the substrate may be ceramic.

[0010] The assembly can define an aperture. The probe can include a limiter disposed within the aperture. The limiter extends into the assembly recess and is configured to constrain bending of the substrate. The limiter can be fabricated from metal.

[0011] The probe may include an electrical connector in electrical communication with the plurality of fingers, the electrical connector being disposed within the assembly.

[0012] The probe may include at least one spring disposed between the substrate and the assembly within the assembly recess.

[0013] The substrate recess can extend from the contact surface into the substrate by 25 μm to 100 μm.

[0014] The fingers can extend 50 μm to 200 μm beyond the distal end of the substrate.

[0015] Each of the fingers may have a width of 10 μm to 20 μm.

[0016] The fingers may have a thickness extending from the contact surface between 30 μm and 150 μm.

[0017] Each of the fingers can have a conical or frusto-conical cross-section having a first outer surface and a second outer surface opposite the first outer surface, the second outer surface being wider than the first outer surface.

[0018] The distance between the fingers in the substrate recess and the substrate may be greater than 0 mm and less than 1 mm.

[0019] In a second embodiment, a method is provided. The method includes contacting an electrical device with a probe including a plurality of fingers (e.g., BeCu) disposed on a substrate. The fingers are bent within a substrate recess of the substrate. The fingers and the substrate are bent within an assembly recess of an assembly configured to hold the fingers and the substrate. Electrical test measurements of the electrical device using the probe are received.

[0020] The method can include applying tension between the substrate and the assembly using at least one spring in an assembly recess disposed between the substrate and the assembly.

[0021] The fingers can be bent 25 μm to 100 μm across the substrate recess.

[0022] The substrate can be bent up to 50 μm over the assembly recess.

[0023] The electrical device may be a screen or a flat panel display.

[0024] For a fuller understanding of the nature and objects of the present disclosure, reference should be made to the following detailed description taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0025] [Figure 1A] 1 shows an embodiment of a probe including components without assembly. [Figure 1B] The components are shown with the assembly. [Figure 1C] FIG. 1C shows a view of the opposite side of the assembly in FIG. 1B. [Figure 2A] FIG. 1 is a side cross-sectional view of an embodiment of a probe. [Figure 2B] FIG. 2B is a front view of the probe of FIG. 2A. [Figure 2C] FIG. 2B is a top perspective view of the probe of FIG. 2A. [Figure 2D] 2B is a cross-sectional view of the probe finger and substrate in FIG. 2A. [Figure 3] FIG. 10 is a top view of the fingers extending beyond the substrate. [Figure 4] 10 is an embodiment of fingers cut from a foil on a substrate. [Figure 5] 1 is an embodiment of a finger portion. [Figure 6] The fingers are shown at increased magnification. [Figure 7] 1 illustrates a top view of an embodiment of a substrate. [Figure 8] FIG. 1 is a diagram of a pocket in a substrate. [Figure 9] 1 is a flowchart of an embodiment of a method according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0026] Although the claimed subject matter is described in terms of certain embodiments, other embodiments, including embodiments that do not possess all of the advantages and features described herein, are within the scope of this disclosure. Various structural, logical, process step, and electronic changes may be made without departing from the scope of the disclosure. Accordingly, the scope of the disclosure is defined solely by reference to the appended claims.

[0027] The embodiments disclosed herein provide precision electrical probes (e.g., 20 μm) that can enable fine-pitch electrical measurement applications for devices such as smartwatches and smartphones. Smartwatches, smartphones, and other screens or flat panels can benefit from probes with more precise tips. The size, shape, and curvature of the fingers and associated components allow for improved accuracy and resolution compared to previous designs.

[0028] 1A-1C and 2A-2D show an embodiment of a probe 100. The probe 100 comprises a substrate 101 defining a contact surface 106 and a substrate recess 107 at a distal end 107 of the substrate 101. The substrate 101 may be fabricated from a ceramic such as Al2O3, AlN, BeO, glass, silica, or other insulating material.

[0029] The fingers 102 are disposed on a contact surface 106 of the substrate 101. The fingers 102 extend beyond a distal end 111 of the substrate 101 and across a substrate recess 107. The fingers 102 are spaced apart from the substrate 101 as the fingers 102 extend across the substrate recess 107.

[0030] In some cases, the fingers 102 are fabricated from BeCu, which offers improved fatigue performance, wear resistance, and solderability. The fingers 102 can be fabricated from other materials, such as high-hardness steel coated with electroless nickel.

[0031] The fingers 102 can be femtolaser machined or chemically etched. In one example, a 50-100 μm thick BeCu foil is used to form multiple fingers 102, each with a width of 10 μm or more and a length of several hundred μm. As shown in FIG. 5, the fingers 102 can extend in a fan that increases in width as it extends.

[0032] In some cases, the fingers 102 are glued to the substrate 101 before micromachining. Figure 4 shows the fingers 102 as they are formed. Some of the foil has already been removed in Figure 4. The glued and micromachined sandwich, including the fingers 102 and the substrate 101, has protruding thin fingers 102 at one end of the substrate 101 and an equal number of wider pads at the other end. These pads can be used as part of the electrical connections.

[0033] The assembly 103 is configured to hold the substrate 101 and the fingers 102. The assembly 103 defines an assembly recess 108. The substrate 101 is spaced from the assembly 103 in the assembly recess 108. The assembly recess can have a depth configured to allow for an angular deflection of the substrate 101 of 3° to 5° or 3° to 7°. This parting angle, shown in FIG. 2A , allows the substrate 101 to be positioned within the assembly recess 108 in a downward manner from the assembly 103. The distance between the substrate 101 and the assembly 103 in the assembly recess 108 can be near zero or even zero when the fingers 102 are depressed during testing.

[0034] The substrate 101 can be soldered to the electrical connector 105, and the electrical connector 105 can be connected to the assembly. For example, the substrate 101 and the electrical connector 105 can be bolted to the assembly 103. The substrate 101 can include fingers 102 when connected to the assembly 103.

[0035] In some cases, the assembly 103 can be made from anodized aluminum, although other materials are possible. The anodized aluminum can be 6061-T6 aluminum.

[0036] The assembly 103 can define an aperture 109 through its body. The aperture 109 can extend from a top surface of the assembly 103 to the assembly recess 108. The limiter 104 can be disposed within the aperture 109. The limiter 109 extends into the assembly recess 108 and is configured to constrain flexing of the substrate 102. The limiter 109 can prevent excessive deflection of the substrate 101 and fingers 102.

[0037] The limiter 104 can be made from metal, ceramic, or plastic. The limiter 104 is connected to the assembly 103, such as by gluing, soldering, or mechanically fastening the components.

[0038] An electrical connector 105 can be in electrical communication with the fingers 102. The electrical connector 105 can be disposed on the assembly 103. In some cases, the fingers 102 can be soldered to a printed circuit board (PCB) that serves as the electrical connector 105, electrically connecting the probe sandwich (i.e., the fingers 102 and the substrate 101) to a measurement instrument. A hot bar technique can be used for the soldering.

[0039] The bending movement can be correlated to a maximum stress in the finger 102. The connection between the finger 102 and the electrical connector 105 can be configured to operate during the maximum stress of the finger 102. If the finger 102 is stretched beyond the maximum stress, it may break or bend.

[0040] The contacts connecting between the PCB and the sandwich (i.e., fingers 102 and substrate 101) in electrical connector 105 can also function as flexures that allow deflection of the sandwich in the Z direction (see Figures 2A and 2D) of approximately 1000 μm. See, for example, parting angle α in Figure 2A.

[0041] At least one spring 110 can 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. The at least one spring 110 creates a preload on the biased sandwich (i.e., the fingers 102 and the substrate 101), which can ensure a predefined probe force and also provide a desired contact resistance. The spring 110 can have a force of 0.1-0.3 N, although other values ​​are possible.

[0042] In some cases, 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 some cases, the distance between the surface of the finger 102 and the opposite surface of the substrate 101 at the substrate recess 107 is greater than zero and less than 1 mm. This can refer to the case where the finger does not bend.

[0043] 3 is a top view of fingers 102 extending beyond substrate 101. Fingers 102 can extend 50 μm to 200 μm beyond distal end 107 of substrate 101. In some cases, fingers 102 extend about 100 μm beyond distal end 107 of substrate 101. The final width of an individual finger 102 that contacts an electrical device can be 15 to 50 μm.

[0044] FIG. 6 shows the fingers 102 at increased magnification. Each of the fingers 102 can have a width between 10 μm and 300 μm. For example, the width can be between 10 μm and 20 μm. Each of the fingers can have a height (e.g., the thickness extending from the contact surface 106) between 30 μm and 150 μm. The shape of the fingers 102 can be tailored based on the height and width to accommodate stress, deflection, and finger lifespan, thereby reducing the likelihood of breakage.

[0045] There may be two areas of deflection for the fingers 102. First, the thin fingers 102 may be limited to a deflection of 50 μm to 100 μm, depending on their location in the substrate recess 107. Second, the portion of the fingers 102 connected to the electrical connector 105 may have its deflection limited using assembly 103 and limiter 104. The portion of the fingers 102 connected to the electrical connector 105 may move between 500 μm and 1000 μm. The portion of the fingers 102 that extends beyond the distal end 111 of the substrate 101 may deflect by approximately 200 μm.

[0046] As shown in Figure 6, each of the fingers 102 has a conical or frusto-conical cross-section having a first outer surface and a second outer surface opposite the first outer surface, where the second outer surface (i.e., the bottom in Figure 6) is wider than the first outer surface (i.e., the top in Figure 6).

[0047] Laser machining typically produces a conical shape in the fingers 102 due to the optical numerical aperture (N / A). The tip width of the fingers 102 can be made small enough to touch the pads of the device. The entire fingers 102 can be made as wide as possible within an allowable pitch to avoid, at least in part, lateral movement caused by the tapered shape.

[0048] 7 shows a top view of an embodiment of substrate 101. The angle of substrate 101 from the rectangular portion can be approximately 45°. The width of the distal end of the substrate from which the fingers extend can be 2 mm to 5 mm. Substrate 101 can have a shape similar to a fan foil, which can reduce weight.

[0049] FIG. 8 is a diagram of a pocket in a substrate. Each finger can be located on the opposite side of a pocket machined into the substrate. One or more micromachined (“carved”) pockets in the substrate 101 can limit the local deflection of the fingers 102. The pockets can act like a barrier that prevents the fingers 102 from deflecting after contacting the glass being investigated. The carved pockets can limit the deflection to a maximum of 50 μm for a finger 102 protruding 1000 μm.

[0050] Although FIG. 8 shows individual pockets, a single recess spanning the width of the finger could also be used.

[0051] The embodiments disclosed herein provide improved finger sizes for the probe. Different shapes than existing pogo pins are possible. Lifespan and contact resistance can be configured by controlling contact force. In some cases, the probe embodiments disclosed herein can be replaceable consumable parts in the art.

[0052] Micromachined thin finger probes offer advantages over conventional designs. A single piece of foil can be used to form the fingers, providing thin fingers with a distributed pattern from finger to flexure and / or contact with the PCB. The fingers can also provide flexure and PCB contact. The total ceramic movement at the flexure can be mechanically (adjustably) limited to 500 μm, with a preload force that determines the contact tolerance. Lowering the probe block does not apply additional force to the fingers.

[0053] FIG. 9 is a flowchart of an embodiment of a method 200 in which embodiments of the probe 100 can be used. At 201, an electrical device is contacted with a probe including multiple fingers disposed on a substrate. The electrical device can be, for example, a screen or flat panel display. The fingers can be BeCu. At least one probe is mounted to a tooling platform. The tooling platform can include a beam that moves over the electrical device and can move closer and farther from the surface of the electrical device to create contact. When lowered, the probe fingers contact conductors on the electrical device, thereby providing an electric field for interrogation.

[0054] At 202, the fingers are bent into a substrate recess of a substrate. At 203, the fingers and substrate are bent into an assembly recess of an assembly configured to hold the fingers and substrate. Steps 202 and 203 can be performed sequentially or at least partially simultaneously. The fingers can be bent 25 μm to 100 μm over the substrate recess. The substrate can be bent up to 50 μm over the assembly recess.

[0055] In some cases, the fingers 102 can deflect up to 100 μm (all together or individually to fit contours), and the substrate 102 can deflect 500 μm to 1000 μm as one piece to allow for tool precision.

[0056] At 204, measurements from an electrical test of an electrical device using a probe are received. The measurements may be received by a processor for analysis. The processor may be part of a computer or another system.

[0057] At least one spring disposed between the substrate and the assembly in the assembly recess can be used to apply tension between the substrate and the assembly.

[0058] While the present disclosure has been described with respect to one or more particular embodiments, it will be understood that other embodiments of the present disclosure can be made without departing from the scope of the present disclosure, and therefore the present disclosure is deemed to be limited only by the appended claims and their reasonable interpretation.

Claims

1. A substrate defining a contact surface and a substrate recess at the distal end of the substrate, wherein the substrate is planar between the distal end and the proximal end opposite to the distal end, A plurality of finger portions disposed on the contact surface, wherein each finger portion extends beyond the distal end of the substrate into the substrate recess, and each finger portion is separated from the substrate as it extends into the substrate recess, An assembly configured to hold the substrate and the finger portion, wherein the assembly defines an assembly recess surrounding less than the entire substrate, and the substrate is positioned in the assembly recess at an angle downward from the proximal end of the substrate, thereby separating the substrate from the assembly within the assembly recess, and A probe characterized by comprising the following features.

2. A probe according to claim 1, characterized in that the finger portion is manufactured from BeCu.

3. A probe according to claim 1, characterized in that the substrate is ceramic.

4. A probe according to claim 1, wherein the assembly defines an aperture and further comprises a limiter disposed within the aperture, the limiter extending into a recess in the assembly and configured to restrict the bending of the substrate through contact with the substrate.

5. A probe according to claim 4, wherein the limiter is made of metal.

6. A probe according to claim 1, further comprising an electrical connector that electrically communicates with the plurality of finger portions, wherein the electrical connector is disposed within the assembly.

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

8. A probe according to claim 1, characterized in that the substrate recess extends 25 μm to 100 μm into the substrate from the contact surface.

9. A probe according to claim 1, characterized in that the finger portion extends 50 μm to 200 μm beyond the distal end of the substrate.

10. A probe according to claim 1, characterized in that each of the finger portions has a width of 10 μm to 20 μm.

11. A probe according to claim 1, characterized in that each of the finger portions has a thickness extending from the contact surface by 30 μm to 150 μm.

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

13. A probe according to claim 1, characterized in that the distance between the finger portion and the substrate in the substrate recess is greater than 0 mm and less than 1 mm.

14. The electrical device is brought into contact with a probe that includes multiple finger-like parts arranged on a circuit board, Bending the finger portion within the recess of the substrate, The method involves bending the finger portion and the substrate within an assembly recess configured to hold the finger portion and the substrate, wherein the assembly encloses less than the entire substrate, the substrate is positioned within the assembly recess at an angle downward from the end of the substrate opposite to the finger portion, and the substrate is planar between the end having the finger portion and the end opposite to the finger portion before the bending. To receive measurement values ​​from the electrical test of the electrical device using the probe. A method characterized by including

15. A method according to claim 14, characterized in that the finger portion is manufactured from BeCu.

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

17. A method according to claim 14, characterized in that the finger portion is bent by 25 μm to 100 μm across the recess of the substrate.

18. A method according to claim 14, characterized in that the substrate is bent by a maximum of 50 μm across the assembly recess.

19. A method according to claim 14, characterized in that the electrical device is a screen.

20. A method according to claim 14, characterized in that the electrical device is a flat panel display.

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