High frequency probe, high frequency probe array and manufacturing method thereof

Abstract

The application discloses a high-frequency probe, a high-frequency probe array and a manufacturing method thereof, and belongs to the technical field of semiconductor testing. The application aims to solve the problem that the internal microstructure of the existing probe is uncontrollable to change due to stress in use, thereby causing high-frequency impedance drift and array inconsistency. The method comprises the following steps: forming a functional composite layer containing micro metal particles on a conductive needle body; in a plastic state, applying mechanical preloading based on the reverse design of the target high-frequency electrical performance, so that the particles are arranged in a direction to form a preset microstructure; then, solidifying while maintaining the loading state to permanently lock the structure. By actively simulating and fixing the performance change in use to the manufacturing stage, the finished probe has stable and preset high-frequency electrical performance in a free state. The application also discloses a high-frequency probe and array manufactured by the method, and the impedance stability and consistency of the high-frequency probe and array are significantly better than those of traditional products.

Description

Technical Field

[0001] This invention relates to the field of semiconductor testing technology, specifically to a probe for high-frequency signal testing and its manufacturing method, and more particularly to a technique for actively controlling the microstructure of the dielectric material inside the probe through the manufacturing process to optimize its high-frequency electrical performance. Background Technology

[0002] In high-frequency semiconductor testing, probes serve as a bridge connecting the test equipment and the device under test. The matching degree, stability, and consistency of their characteristic impedance within the probe array are crucial for ensuring test accuracy. Existing high-frequency probe manufacturing technologies (such as the technology represented by patent CN101221194B) mainly focus on the macroscopic structural design of transmission lines and the selection of low-loss dielectric materials.

[0003] However, this type of existing technology has an inherent, yet not fully understood and resolved, technical drawback: During actual testing, the probes require mechanical pressure to establish electrical contact, and this pressure continuously acts on the insulating dielectric layer outside the probe. When this dielectric layer is a composite material containing fillers (such as metal particles added for performance enhancement), continuous pressure causes irreversible and non-uniform changes in the microscopic distribution of the filler particles. This change in microstructure directly causes fluctuations in the equivalent dielectric constant of the composite material, ultimately manifesting as a drift in the probe's characteristic impedance during use. For arrays consisting of tens to hundreds of probes, due to micro-manufacturing tolerances, the initial state of the dielectric layer of each probe already differs. The same operating pressure amplifies these differences, leading to severe array performance inconsistencies.

[0004] Therefore, existing technologies lack a solution to fundamentally address the performance instability caused by stress during use. The purpose of this invention is to propose an innovative manufacturing concept: instead of passively subjecting the probe to microstructural changes during use, it actively simulates the stress state during the manufacturing stage and permanently fixes the optimized microstructure, thereby ensuring that the probe is in a pre-optimized and stable electrical performance state when it leaves the factory. Summary of the Invention

[0005] The technical problem to be solved by this invention is: how to overcome the high-frequency impedance drift caused by the uncontrollable changes in the microstructure of the internal composite material during actual use of existing high-frequency probes, and the resulting inconsistency in probe array performance.

[0006] To address the aforementioned technical problems, this invention provides a novel high-frequency probe manufacturing paradigm. Its core idea is to transform "mechanical loading" from a usable operating condition into a key process parameter actively applied during the manufacturing stage for "designing" and "pre-fabricating" the final electrical performance.

[0007] A method for manufacturing a high-frequency probe includes the following steps: S1. Probe body forming: Processing conductive materials to form a conductive needle body, such as a spring needle or cantilever beam structure; S2. Functional composite layer construction: A functional composite layer is formed on at least a portion of the outer peripheral surface of the conductive needle body. The functional composite layer includes an insulating matrix and micro metal particles dispersed therein. The insulating matrix may be silicone rubber or polyimide. The micro metal particles are selected from one or more of gold, silver, platinum, palladium, copper, nickel, and aluminum, or from one or more of silver-copper alloy, silver-palladium alloy, and gold-nickel alloy. S3. Controlled preloading and microstructure prefabrication: When the functional composite layer is in a plastic state, a preset mechanical preloading is applied to the probe body carrying the functional composite layer; wherein, the direction and magnitude of the preset mechanical preloading are determined based on the target high-frequency electrical performance parameters of the high-frequency probe, so that the micro-metal particles are non-randomly oriented in the insulating matrix, thereby forming a microstructure that has a preset influence on the target high-frequency electrical performance parameters; S4. Curing and Structural Locking: While maintaining the mechanical preloaded state, the functional composite layer is cured to fix the microstructure.

[0008] Furthermore, in step S3, the target high-frequency electrical performance parameter is characteristic impedance or equivalent dielectric constant; by changing the magnitude of the mechanical preload, the equivalent dielectric constant of the functional composite layer after curing along the loading direction can be predictably controlled.

[0009] Furthermore, the microstructure formed in step S3 is characterized by the average nearest neighbor distance of the micro-metal particles in the mechanical preloading direction being smaller than the average nearest neighbor distance in the direction perpendicular to that direction.

[0010] Furthermore, the mechanical preloading is a pressure along the axial direction of the conductive needle body, and this axial pressure is consistent with the direction of high-frequency signal transmission to optimize signal transmission stability.

[0011] Furthermore, the particle size of the micro-metal particles is in the nanometer or micrometer range.

[0012] A method for manufacturing a high-frequency probe array, wherein multiple high-frequency probes are manufactured using the method described above; wherein, in step S3, mechanical preloads of different magnitudes are applied to at least two of the multiple high-frequency probes to compensate for individual differences during the manufacturing process, so that the consistency of the high-frequency electrical performance parameters of the completed probe array is higher than that obtained by applying the same mechanical preload to all probes.

[0013] A high-frequency probe, manufactured by the aforementioned method, comprises: Conductive needle body; and A functional composite layer covering at least a portion of the outer periphery of the conductive needle body comprises a cured insulating matrix and micro-metal particles dispersed therein. The micro-metal particles in the functional composite layer exhibit a non-random and anisotropic permanent arrangement structure, which results in a measurable difference between the equivalent dielectric constant of the functional composite layer along the axial direction of the conductive needle and the equivalent dielectric constant along the radial direction.

[0014] A high-frequency probe array includes a plurality of high-frequency probes, wherein the standard deviation of the characteristic impedance of the plurality of high-frequency probes in the target frequency band is less than 2mΩ.

[0015] Compared with the prior art, the present invention has achieved the following significant advancements: By transforming adverse changes in the working state into beneficial presets in the manufacturing stage, impedance drift during use is fundamentally suppressed, thereby improving the long-term reliability of the probe.

[0016] Preloading is no longer a simple physical processing step, but a core design variable directly linked to the target electrical performance, enabling proactive and precise control of the probe's high-frequency performance.

[0017] Differential preloading compensation can effectively offset micro-process fluctuations and produce probe arrays with highly consistent electrical performance, providing a key guarantee for high-precision multi-channel testing.

[0018] The method has a clear principle, does not rely on special materials or extreme processes, is easy to integrate into existing production lines, and has good prospects for industrialization. Attached Figure Description

[0019] Figure 1 This is a schematic diagram illustrating the changes in the microstructure of micro-metal particles within the functional composite layer before and after controlled preloading, according to one embodiment of the present invention. Part (a) shows the random distribution of the particles before preloading, and part (b) shows the locked state after preloading and curing, where the particles exhibit a directional alignment along the loading direction and a decrease in average spacing.

[0020] Figure 2 This is a schematic cross-sectional view of a high-frequency spring probe fabricated according to the present invention. The center is a conductive needle body, and the outer periphery is a functional composite layer containing a cured insulating substrate and anisotropically arranged micro-metal particles.

[0021] Explanation of the labels in the diagram: 1. Conductive needle body; 2. Functional composite layer; 21. Insulating substrate; 22. Micro-metal particles. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that these embodiments are only used to explain the present invention and do not limit the scope of protection of the present invention.

[0023] Example 1: A method for manufacturing a high-frequency probe, comprising the following steps: S1. Probe body forming: The conductive needle body 1 is made of beryllium copper, and the conductive needle body 1 is specifically a standard spring needle body.

[0024] S2. Construction of functional composite layer 2: A functional composite layer 2 is coated in the middle section of the standard spring needle body. The functional composite layer 2 includes an insulating substrate 21 and micro metal particles 22 dispersed therein. The insulating substrate 21 is liquid silicone rubber, and the micro metal particles 22 are 5% by volume submicron silver powder. The thickness of the functional composite layer 2 is 20 μm.

[0025] S3. Controlled preloading and microstructure prefabrication: When the functional composite layer 2 is in a plastic state, a preset mechanical preload is applied to the probe body carrying the functional composite layer 2. The direction and magnitude of the preset mechanical preload are determined based on the target high-frequency electrical performance parameters of the high-frequency probe, so that the micro-metal particles are non-randomly oriented in the insulating matrix, thereby forming a microstructure that has a preset influence on the target high-frequency electrical performance parameters. The mechanical preload is specifically a preload along the axial direction of the standard spring needle body, which is consistent with the direction of high-frequency signal transmission. The magnitude is divided into three groups: low load group (0.2N), target load group (0.5N), and high load group (0.8N).

[0026] S4. Curing and Structural Locking: Under the condition of maintaining the mechanical preload, the three groups of functional composite layers 2 are cured at a curing temperature of 100℃ and a curing time of 45min to fix the microstructure.

[0027] Comparative Example 1 is based on Example 1, in which the functional composite layer 2 is cured directly without mechanical preloading, and other process parameters are completely consistent with Example 1.

[0028] The characteristic impedance of the probe samples of Example 1 and Comparative Example 1 at 10 GHz was measured using a vector network analyzer. The average impedance of the low load group was 53.5 mΩ, the average impedance of the target load group was 50.1 mΩ (closest to the target value of 50 mΩ), the average impedance of the high load group was 47.2 mΩ, and the average impedance of Comparative Example 1 was 55.0 mΩ, with the largest dispersion.

[0029] Meanwhile, long-term stability tests were conducted: the target load group (0.5N) probe and the comparative example 1 probe were used continuously for 1000 hours (simulating actual test conditions, applying 0.3N axial pressure). The impedance drift of the probe of the present invention was less than 0.2mΩ, while the impedance drift of the comparative example 1 probe reached 3.5mΩ.

[0030] Data clearly demonstrates a strong and predictable correlation between the magnitude of the axial preload and the final characteristic impedance, and that this invention can significantly suppress impedance drift during long-term use. By setting specific preload parameters, the probe impedance can be precisely "designed" to the target value, much like "tuning." This is not an effect that can be naturally achieved by simply applying a molding pressure; rather, it is a direct manifestation of the inventive concept of actively linking mechanical parameters with electrical targets.

[0031] Example 2, based on Example 1, demonstrates how to solve the array consistency problem using differentiated preloading.

[0032] Four conductive needles 1 coated with functional composite layers 2, designated P1-P4, were prepared according to steps S1 and S2 of Example 1. Non-contact thickness measurement revealed that the thicknesses of the functional composite layers 2 in P2 and P3 were slightly thinner than those in P1 and P4 (due to inherent process variations).

[0033] Compensation was performed based on the pressure-resistance relationship model established in Example 1. Slightly lower pressure (0.48 N) was applied to P1 and P4, where the expected resistance was higher (due to layer thickness); slightly higher pressure (0.52 N) was applied to P2 and P3, where the expected resistance was lower (due to layer thinness). All pressures were applied and maintained in a pliable state until curing was complete, and the curing process was the same as in Example 1.

[0034] Comparative Example 2: The same steps S1-S4 as the present invention were used, except that step S3 applied a uniform pressure of 0.5N to all four probes, and the other process parameters were completely identical.

[0035] The arrays using the compensatory loading of this invention, P1-P4, have impedances of 49.9mΩ, 50.2mΩ, 50.0mΩ, and 50.1mΩ at 10GHz, respectively, with a calculated standard deviation of 0.13mΩ.

[0036] Comparative Example 2, manufactured under uniform pressure (0.5N), has impedances of 51.0mΩ, 48.5mΩ, 48.8mΩ, and 50.8mΩ, with a standard deviation of 1.25mΩ.

[0037] Conclusion: The compensatory manufacturing method of this invention improves array impedance uniformity by nearly an order of magnitude by adjusting the preload parameters in reverse to address individual differences. This is not simply "manufacturing multiple probes together," but rather a proactive and intelligent performance uniformization process that solves the array performance dispersion problem that existing technologies cannot overcome.

[0038] The insulating substrate 21 in this invention is not limited to silicone rubber, but can also be other curable polymers; the material, shape, and particle size of the micro-metal particles 22 can be selected as needed. The manufacturing method has clear steps, and the required equipment (coating machine, precision controllable pressure device, curing equipment) are all mature industrial equipment, which can be easily applied to the large-scale production of high-frequency probes. The resulting high-performance probes and arrays can be widely used in wafer-level testing and packaging testing in fields such as 5G communication, RF chips, and high-speed computing, and have extremely high industrial value.

Claims

1. A method of manufacturing a high frequency probe, characterized by, Includes the following steps: S1. Probe body forming: Processing conductive materials to form a conductive needle body; S2. Functional composite layer construction: A functional composite layer is formed on at least a portion of the outer peripheral surface of the conductive needle body, the functional composite layer comprising an insulating matrix and micro metal particles dispersed therein; S3. Controlled preloading and microstructure prefabrication: When the functional composite layer is in a plastic state, a preset mechanical preloading is applied to the probe body carrying the functional composite layer; wherein, the direction and magnitude of the preset mechanical preloading are determined based on the target high-frequency electrical performance parameters of the high-frequency probe, so that the micro-metal particles are non-randomly oriented in the insulating matrix, thereby forming a microstructure that has a preset influence on the target high-frequency electrical performance parameters; S4. Curing and Structural Locking: Under the condition of maintaining the mechanical preload state, the functional composite layer is cured to preserve the non-random oriented arrangement of the micro-metal particles in the cured insulating matrix.

2. The method of claim 1, wherein, In step S3, the target high-frequency electrical performance parameter is characteristic impedance or equivalent dielectric constant; by changing the magnitude of the mechanical preload, the equivalent dielectric constant of the functional composite layer after curing along the loading direction can be predictably controlled.

3. The method according to claim 1 or 2, characterized in that, The microstructure formed in step S3 is characterized by the average nearest neighbor distance of the micro-metal particles in the mechanical preloading direction being smaller than the average nearest neighbor distance in the direction perpendicular to that direction.

4. The method according to claim 1, characterized in that, The mechanical preload is a pressure along the axial direction of the conductive needle body, and this axial pressure is consistent with the direction of high-frequency signal transmission.

5. The method according to claim 1, characterized in that, The particle size of the micro-metal particles is in the nanometer or micrometer range.

6. A method for manufacturing a high-frequency probe array, characterized in that, Multiple high-frequency probes are manufactured using the method described in any one of claims 1-5; wherein, in step S3, mechanical preloads of different magnitudes are applied to at least two of the multiple high-frequency probes to compensate for individual differences during the manufacturing process, so that the consistency of the high-frequency electrical performance parameters of the probe array after manufacturing is higher than that obtained by applying the same mechanical preload to all probes.

7. A high-frequency probe, characterized in that, The high-frequency probe, manufactured by the method of any one of claims 1 to 5, comprises: Conductive needle body; and A functional composite layer covering at least a portion of the outer periphery of the conductive needle body comprises a cured insulating matrix and micro-metal particles dispersed therein. The micro-metal particles in the functional composite layer exhibit a non-random and anisotropic permanent arrangement structure, which results in a measurable difference between the equivalent dielectric constant of the functional composite layer along the axial direction of the conductive needle and the equivalent dielectric constant along the radial direction.

8. A high-frequency probe array, characterized in that, It includes multiple high-frequency probes as described in claim 7, wherein the standard deviation of the characteristic impedance of the multiple high-frequency probes in the target frequency band is less than 2mΩ.

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