Membrane probe card with local wear resistant layer

Abstract

The application discloses a MEMS probe with a local wear-resistant layer and a probe card. The probe comprises a needle head, a needle tail and a probe arm for connecting the needle head and the needle tail, and the probe arm has a wear-prone part, and an outer surface of the wear-prone part is provided with a wear-resistant layer. The scheme can prevent the probe arm from being damaged due to friction with the hole wall of a needle planting hole during needle planting or testing.

Description

Technical Field

[0001] This invention relates to the field of probe card technology, specifically a MEMS probe and probe card with a local wear-resistant layer. Background Technology

[0002] A probe card is an interface instrument used for testing chips. The most crucial component of a probe card is called the probe head (PH). A common probe head structure for a MEMS vertical probe card is as follows: Figure 1 As shown, it is manufactured by machining pin holes on the upper guide plate 1 and the lower guide plate 2 respectively, and then inserting tens of thousands of probes 3 into the pin holes of the upper and lower guide plates in sequence (that is, the tip of a probe 3 is first inserted into the upper guide plate 1, and then into the lower guide plate 2). The upper and lower guide plates are separated by a distance, so that the probes bend in this space (for the sake of simplifying the diagram, ...). Figure 1 Only a few probes and their upper and lower guide plates are drawn.

[0003] MEMS probes can be divided into two major systems according to their manufacturing process: pre-bent probes and straight probes. They all share an unavoidable structural commonality: the probe arm (the part connecting the needle head and the needle tail) must pass through the hole array of the upper guide plate and the lower guide plate in the probe card in sequence during insertion and use, and undergo lateral reciprocating micro-sliding and longitudinal over-drive within the holes.

[0004] The guide plate hole walls are made of ceramic, and after laser drilling / precision grinding, abrasive particles inevitably remain on the hole wall surface. Pre-bent probes typically have an organic insulating layer covering the substrate. When inserting needles into the pre-bent probes, the insulating layer is easily worn and cracked due to friction with the hole walls of the upper and lower guide plates. This can lead to direct contact between adjacent probes and the substrate during use, causing short circuits. Furthermore, insulation fragments can peel off and block the needle holes, potentially causing the probes to become stuck inside the guide plate and lose their normal testing capability. While straight probes, due to their lack of pre-bending design, do not suffer from significant friction with the hole walls during needle insertion, resulting in insulation wear, the contact area between the straight probe and the guide plate is inevitably subject to wear during testing. Even under tens of thousands of cycles of fretting wear, the guide plate hole walls can still inflict micron-deep scratches on the straight probes. Taking a straight probe with a diameter of 30μm as an example: if a 2μm deep groove is ground on one side, the effective diameter is reduced to 26μm, and the cross-sectional area is lost by about 25%; under the same test contact force, the cyclic stress at the probe root jumps by about 33%. If the original design safety margin is 2, the margin drops to below 1.5 after wear, and the probe is very prone to low-cycle fatigue fracture in subsequent use. Summary of the Invention

[0005] To overcome the deficiencies in the prior art, embodiments of the present invention provide a MEMS probe and probe card with a local wear-resistant layer, which are used to solve the above-mentioned problems.

[0006] This application discloses a MEMS probe with a local wear-resistant layer, wherein the probe is simultaneously inserted into an upper guide plate and a lower guide plate that are spaced apart. The probe includes a needle head, a needle tail, and a probe arm for connecting the needle head and the needle tail. The probe arm has a wear-prone part, and the outer surface of the wear-prone part is provided with a wear-resistant layer.

[0007] Specifically, the wear-resistant layer is a nickel-based wear-resistant alloy.

[0008] Specifically, the nickel-based wear-resistant alloy is one of Ni-W alloy or Ni-Co alloy, wherein the W content in the Ni-W alloy is 6–10 wt%, and the Co content in the Ni-Co alloy is 10–20 wt%.

[0009] Specifically, a buffer seed layer is provided between the wear-prone part of the probe arm and the wear-resistant layer.

[0010] Specifically, the probe arm includes a first segment located within the upper guide plate, a second segment located within the lower guide plate, and a connecting segment for connecting the first segment and the second segment.

[0011] Specifically, the probe is a pre-bent probe, and the easily worn part of the pre-bent probe is the connecting section.

[0012] Specifically, the probe is a straight probe, and the wear-prone part of the straight probe includes the first segment and the second segment.

[0013] Specifically, the ratio of the thickness of the wear-resistant layer to the thickness of the probe arm is ≤5%.

[0014] Specifically, the wear-resistant layer has conical surfaces at both ends with an angle of 5 to 25 degrees.

[0015] This application also discloses a probe card, which includes an upper guide plate, a lower guide plate, and a MEMS probe with a local wear-resistant layer as described in this embodiment, which is simultaneously disposed on the upper guide plate and the lower guide plate.

[0016] The present invention has at least the following beneficial effects:

[0017] 1. By providing a wear-resistant layer on the easily worn part of the probe arm, the probe arm can be prevented from being damaged by friction from the pin hole wall during pin insertion or testing. In addition, since the wear-resistant layer is only provided on the easily worn part of the probe arm of the present invention, the rigidity of the rest of the probe is not significantly affected, and the probe arm can still smoothly achieve elastic bending within the designed overdrive stroke.

[0018] 2. By setting a buffer seed layer between the insulating layer and the wear-resistant layer of the probe arm, the insulating layer can be prevented from being damaged during the electroplating of the wear-resistant layer, thus affecting the insulation function.

[0019] 3. The ratio of the thickness of the wear-resistant layer to the overall thickness of the probe arm is no more than 5%. At this thickness, the stiffness increment introduced by the wear-resistant layer is controlled within the engineering tolerance range, and the probe arm can still smoothly achieve elastic bending within the designed overdrive stroke.

[0020] To make the above and other objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the probe head structure in the prior art;

[0023] Figure 2 This is a schematic diagram of the structure in Embodiment 1 of the present invention, showing the connection between the pre-bent probe and the upper and lower guide plates.

[0024] Figure 3 This is a schematic diagram of the pre-bent probe in Embodiment 1 of the present invention;

[0025] Figure 4 This is a schematic diagram of the connection between the straight probe and the upper and lower guide plates in Embodiment 2 of the present invention;

[0026] Figure 5 This is a schematic diagram of the straight probe structure in Embodiment 2 of the present invention.

[0027] The reference numerals in the above figures are as follows: 1. Upper guide plate; 2. Lower guide plate; 3. Probe; 41. Needle tip; 42. Needle tail; 43. Probe arm; 431. First segment; 432. Second segment; 433. Connecting segment; 5. Wear-resistant layer; 6. Buffer seed layer. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "fixing," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this application based on the specific circumstances.

[0030] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "below," and "over" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0031] In the description of this embodiment, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this application.

[0032] Furthermore, the terms "first" and "second" are used only to distinguish between different terms in description and do not have any special meaning.

[0033] Example 1

[0034] Combination Figure 2 and Figure 3As shown, the MEMS probe with a local wear-resistant layer 5 in this embodiment is a pre-bent probe, which includes a needle head 41, a needle tail 42, and a probe arm 43 for connecting the needle head 41 and the needle tail 42. The probe arm 43 is bent. The needle head 41 of the pre-bent probe passes through the upper guide plate 1 and the lower guide plate 2, which are spaced apart, in sequence for needle implantation. During the needle implantation process, the probe arm 43 also passes through the upper guide plate 1. Since the probe arm 43 is bent, it inevitably comes into contact with the needle implantation hole wall of the upper guide plate 1 during the process of passing through the upper guide plate 1, resulting in sliding friction. This causes the outer wall of the bent probe arm 43 to be easily worn, that is, the probe arm 43 has a wear-prone part. To change this situation, a wear-resistant layer 5 is provided on the outer surface of the wear-prone part of the probe arm 43 in this embodiment. The wear-resistant layer 5 has a Vickers hardness > 400 HV (typically, the Vickers hardness of SiC or diamond microparticles on the hole wall of the guide plate is around 250 HV), preferably a Vickers hardness ≥ 600 HV.

[0035] Specifically, in this embodiment, the wear-resistant layer 5 can be a nickel-based wear-resistant alloy with a Vickers hardness of 500-700 HV and a Young's modulus E of 190-210 GPa. Further, the nickel-based wear-resistant alloy is either a Ni-W alloy or a Ni-Co alloy, wherein the W content in the Ni-W alloy is 6-10 wt%, and the Co content in the Ni-Co alloy is 10-20 wt%. The nickel-based wear-resistant alloy can be formed on the easily worn outer surface of the probe arm 43 by electroplating.

[0036] In this embodiment, the probe arm 43 may also be provided with an insulating layer made of organic material. When the probe arm 43 is electroplated with a Ni-W alloy solution, the Ni-W plating solution is highly acidic (pH 4.0–5.5, containing aminosulfonate and tungstate). This highly acidic plating solution can penetrate through the inherent micropores or interface gaps of the insulating layer and dissolve the underlying metal probe arm 43. The generated bubbles can lift the insulating layer, resulting in an uneven outer surface of the finished probe. In addition, the electroplating current is concentrated at the defects on the surface of the insulating layer, and the local electric field strength exceeds the dielectric strength of the insulating layer, triggering electrochemical corrosion, which may lead to the risk of perforation of the insulating layer and micro-short circuits between the probe arms 43.

[0037] To solve the above problems, such as Figure 3As shown, before electroplating the wear-resistant layer 5 on the easily worn part of the probe arm 43 in this embodiment, a buffer seed layer 6 is first set on the insulating layer of the probe arm 43, and then the wear-resistant layer 5 is set on the buffer seed layer 6. The buffer seed layer 6 is a soft conductive layer. For example, it can be formed by electroless Ni-P plating (phosphorus content of 8 wt%-12 wt%) or sputtering pure Ni to form a buffer seed layer 6 with HV<300 and a thickness of 0.1–0.5 μm. The deposition solution (alkaline sodium hypophosphite system) of the electroless Ni-P plating layer does not corrode the insulating layer, and the Ni-P layer itself is dense and without pinholes, sealing the micro-defects on the surface of the insulating layer. The subsequent strongly acidic Ni-W plating solution no longer directly contacts the insulating layer. As a continuous conductive surface, the Ni-P layer makes the current density distribution of the subsequent electroplating uniform, avoiding the breakdown of current peaks directly at the defects in the insulating layer.

[0038] Specifically, the process of electroplating the wear-resistant layer 5 on the buffer seed layer 6 is as follows: a bidirectional pulse process is adopted, with a forward current density of 1.5 A / dm²-3.0 A / dm², a forward duty cycle of 20%-35%, a reverse duty cycle of 5%-10%, a plating solution pH of 4.8-5.5, and a plating solution temperature of 45-55℃.

[0039] Combination Figure 2 and Figure 3 As shown, the probe arm 43 of this embodiment includes a first segment 431 located within the needle insertion hole of the upper guide plate 1, a second segment 432 located within the needle insertion hole of the lower guide plate 2, and a connecting segment 433 for connecting the first segment 431 and the second segment 432. The curved connecting segment 433 is prone to friction with the wall of the needle insertion hole of the upper guide plate 1 during needle insertion; therefore, the easily worn part of the probe arm 43 in this embodiment is the connecting segment 433. The ratio of the thickness of the wear-resistant layer 5 to the thickness of the probe arm 43 is ≤5%. Preferably, both ends of the wear-resistant layer 5 have a conical surface with an angle of 5~25°; in other words, the cone angle of the conical surface is 5~25°.

[0040] When preparing the probe in this embodiment, the probe can first be chemically plated with a buffer seed layer 6, then the probe can be electroplated with a wear-resistant layer 5, and then the probe can be etched according to the part that needs to be exposed. The wear-resistant layer 5 and the buffer seed layer 6 on the surface of the part that needs to be exposed on the probe can be etched away by the etching process, leaving only the buffer seed layer 6 and the wear-resistant layer 5 on the easily worn part.

[0041] Example 2

[0042] The probe and its preparation method in this embodiment are largely the same as in Example 1, except that, in combination with... Figure 4 and Figure 5As shown, the probe in this embodiment is a straight probe, meaning that the first segment 431, the second segment 432, and the connecting segment 433 of the probe arm 43 are connected in a straight line. Since the straight probe has no pre-bending setting, the friction between the probe arm 43 and the pin hole wall of the guide plate is minimal during pin insertion, and there is almost no problem of wear on the insulation layer. However, to prevent the straight probe from detaching from the guide plate, the upper guide plate 1 and the lower guide plate 2 are usually misaligned so that the probe arm 43 slightly interferes with the upper and lower guide plates respectively. This can cause the portion of the probe located inside the pin hole to be worn by the hole wall during probe card testing. Therefore, in this embodiment, the easily worn parts on the probe arm 43 are the first segment 431 located in the upper guide plate 1 and the second segment 432 located in the lower guide plate 2.

[0043] In summary, the MEMS probe and probe card with a localized wear-resistant layer of the present invention have at least the following advantages:

[0044] 1. By providing a wear-resistant layer 5 on the easily worn part of the probe arm 43, the probe arm 43 can be prevented from being damaged by friction from the pin hole wall during pin insertion or testing. In addition, since the wear-resistant layer 5 is only provided on the easily worn part of the probe arm 43 of the present invention, the rigidity of the rest of the probe is not significantly affected, and the probe arm 43 can still smoothly achieve elastic bending within the designed overdrive stroke.

[0045] 2. By setting a buffer seed layer 6 between the insulating layer and the wear-resistant layer 5 of the probe arm 43, the insulating layer can be prevented from being damaged during the electroplating of the wear-resistant layer 5, thus affecting the insulation function.

[0046] 3. The ratio of the thickness of the wear-resistant layer 5 to the overall thickness of the probe arm 43 is no more than 5%. At this thickness, the stiffness increment introduced by the wear-resistant layer 5 is controlled within the engineering tolerance range, and the probe arm 43 can still smoothly achieve elastic bending within the designed overdrive stroke.

[0047] Specific embodiments have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A MEMS probe with a localized wear-resistant layer, wherein the probe is simultaneously disposed within an upper guide plate and a lower guide plate spaced apart, characterized in that, The probe includes a needle tip, a needle tail, and a probe arm for connecting the needle tip and the needle tail. The probe arm has a wear-prone part, and the outer surface of the wear-prone part is provided with a wear-resistant layer.

2. The MEMS probe with a localized wear-resistant layer according to claim 1, characterized in that, The wear-resistant layer is a nickel-based wear-resistant alloy.

3. The MEMS probe with a localized wear-resistant layer according to claim 2, characterized in that, The nickel-based wear-resistant alloy is one of Ni-W alloy or Ni-Co alloy, wherein the W content in the Ni-W alloy is 6–10 wt%, and the Co content in the Ni-Co alloy is 10–20 wt%.

4. The MEMS probe with a localized wear-resistant layer according to claim 3, characterized in that, A buffer seed layer is also provided between the wear-prone part of the probe arm and the wear-resistant layer.

5. The MEMS probe with a localized wear-resistant layer according to claim 1, characterized in that, The probe arm includes a first segment located within the upper guide plate, a second segment located within the lower guide plate, and a connecting segment for connecting the first segment and the second segment.

6. The MEMS probe with a localized wear-resistant layer according to claim 5, characterized in that, The probe is a pre-bent probe, and the easily worn part of the pre-bent probe is the connecting section.

7. The MEMS probe with a localized wear-resistant layer according to claim 5, characterized in that, The probe is a straight probe, and the wear-prone part of the straight probe includes the first segment and the second segment.

8. The MEMS probe with a localized wear-resistant layer according to claim 1, characterized in that, The ratio of the thickness of the wear-resistant layer to the thickness of the probe arm is ≤5%.

9. The MEMS probe with a localized wear-resistant layer according to claim 1, characterized in that, The wear-resistant layer has conical surfaces at both ends with an angle of 5 to 25 degrees.

10. A probe card, characterized in that, It includes an upper guide plate, a lower guide plate, and a MEMS probe with a local wear-resistant layer as described in any one of claims 1-9, which is simultaneously disposed on the upper guide plate and the lower guide plate.

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