Palladium-based radio frequency probe and preparation method thereof

Abstract

The invention provides a palladium-based radio frequency probe and a preparation method thereof, and the method comprises the steps: (1) drying and uniformly mixing palladium powder, silver powder, copper powder and other metal mixed powder to obtain a premix; (2) smelting, forging, rolling and quenching the premix in sequence to obtain a palladium-based sheet material; (3) carrying out laser cutting and polishing on the palladium substrate material to obtain a needle tip elastic assembly; and (4) connecting the needle tip elastic assembly to one end of the probe main body, connecting the radio frequency connector to the other end of the probe main body, and then placing the radio frequency connector into the inclined insertion through hole of the probe support to obtain the palladium-based radio frequency probe. According to the scheme, the palladium-based radio frequency probe is high in precision, high in universality, low in cost and easy to maintain.

Description

Technical Field

[0001] The present invention relates to the technical field of radio frequency probes, and particularly to a palladium-based radio frequency probe and a preparation method thereof. Background Art

[0002] In the process of chip manufacturing, after the wafer is fabricated, it enters the packaging and testing process, and the performance of the chip needs to be tested first. In-chip testing must use special probes or probers, and the difference between radio frequency in-chip testing and general DC in-chip testing is that it requires the use of special radio frequency probes. Radio frequency probes play an important role in every stage of the product life cycle. It is precisely because of the use of radio frequency probes that the true characteristics of radio frequency devices can be measured at the wafer level, which helps to shorten the research and design cycle and significantly reduce the development cost. Facing the rapid development of current semiconductor technology and the continuous emergence of new types of chips, current various radio frequency probes are difficult to meet various measurement requirements. Frequent replacement of radio frequency probes will lead to frequent calibration of the test system, complex system operation and poor measurement accuracy.

[0003] Current various radio frequency probe tips and elastomers have the following problems:

[0004] 1) For probes made by metal cutting process, the tip consistency is poor, and the tip causes great damage to the chip pads, which will lead to a decrease in the yield of subsequent process steps such as microscopy and bonding;

[0005] 2) Currently, the bottom surface of the laser processed air coplanar probe has poor encapsulation of radio frequency signals, insufficient ability to confine the electromagnetic field in space, and is prone to resonance;

[0006] 3) Probes made by MEMS process have poor repairability and high usage costs;

[0007] 4) Probes made by semiconductor thin film process have high manufacturing costs. The tip is too thin, resulting in small power capacity and high requirements for the flatness of the chip pads;

[0008] 5) Beryllium copper tips are too soft and have poor adaptability to aluminum and copper pads, resulting in poor test stability. (Rhenium) tungsten is too hard and causes excessive damage to gold pads and has poor self-cleaning performance. Although nickel alloy has good adaptability to aluminum, copper and gold, due to the high hardness of nickel-palladium-gold pads, its life is very poor in this application scenario;

[0009] 6) For high-power microwave devices represented by gallium nitride, the current probes have small power capacity and poor heat dissipation ability.

[0010] Therefore, there is an urgent need to develop a radio frequency probe that solves the above problems. Summary of the Invention

[0011] The present invention provides a palladium-based radio frequency probe and a preparation method thereof. The prepared palladium-based radio frequency probe has high precision, strong versatility, low cost and easy maintenance.

[0012] In a first aspect, the present invention provides a preparation method of a palladium-based radio frequency probe, comprising:

[0013] (1) Drying and mixing palladium powder, silver powder, copper powder and the remaining metal mixed powder to obtain a premix;

[0014] (2) Successively melting, forging, rolling and quenching the premix to obtain a palladium-based sheet;

[0015] (3) Laser cutting and polishing the palladium-based sheet to obtain a tip elastic component;

[0016] (4) Connecting the tip elastic component to one end of the probe body, connecting the radio frequency connector to the other end of the probe body, and then placing the radio frequency connector into the inclined insertion through hole of the probe holder to obtain the palladium-based radio frequency probe.

[0017] Preferably, in step (1): the mass ratio of the palladium powder, silver powder, copper powder and the remaining metal mixed powder is (55 - 60%):(34 - 38%):(4 - 6%):(0.8 - 1.5%).

[0018] Preferably, in step (1): the remaining metal mixed powder is at least two of nickel powder, iron powder, aluminum powder and titanium powder.

[0019] Preferably, in step (1): the drying temperature is 30 - 100 °C and the drying time is 3 - 20 h.

[0020] Preferably, in step (1): when dry mixing is carried out by a planetary ball mill, the mixing time is 2 - 8 h, the ball-to-material ratio is (4 - 30):1, and the rotation speed is 60 - 1000 rpm.

[0021] More preferably, in step (1): both the drying and the mixing are carried out under a protective atmosphere.

[0022] Preferably, in step (2): the melting temperature is 1400 - 2000 °C and the time is 5 - 10 min; preferably, the melting is carried out in a protective atmosphere.

[0023] Preferably, in step (2): the forging temperature is 900 - 1100 °C, the single forging deformation amount is 20 - 30%, and the total forging deformation amount is 50 - 70%.

[0024] Preferably, in step (2): the rolling successively includes hot rolling and cold rolling;

[0025] The temperature of the hot rolling is 700 - 900 °C, the single - pass deformation is 20 - 30%, and the total deformation is 50 - 60%; the temperature of the cold rolling is 20 - 25 °C, the single - pass deformation is 10 - 15%, and the total deformation is 50 - 60%.

[0026] Preferably, in step (2): the quenching temperature is 800 - 900 °C and the time is 1 - 2 h.

[0027] Preferably, in step (3): the laser cutting is performed using femtosecond laser; the polishing is performed using magnetorheological polishing; wherein, the palladium - based sheet is subjected to the laser cutting and the polishing to obtain a tip elastic component with a preset pattern and a preset shape.

[0028] Preferably, the tip elastic component includes a signal tip elastic component and a ground tip elastic component arranged in parallel, and the tip elastic component includes a tip part and a non - tip part.

[0029] Preferably, the tip elastic component includes GSG type, GS / SG type, GSSG type and GSGSG type.

[0030] Preferably, the leading - edge angle of the tip part of the tip elastic component is 60° ± 1°, and the trailing - edge angle is 30° ± 1°.

[0031] The width of the tip part of the tip elastic component is 15 μm - 50 μm.

[0032] In a second aspect, the present invention also provides a palladium - based radio - frequency probe prepared by any of the preparation methods in the first aspect above.

[0033] Preferably, a gap band is provided between the signal tip elastic component and the ground tip elastic component; the non - tip part of the signal tip elastic component is coated with a shielding layer; the shielding layer is connected to the ground tip elastic component, and a dielectric layer is filled between the signal tip elastic component and the shielding layer.

[0034] Preferably, the palladium - based radio - frequency probe further includes: a heat - dissipation component;

[0035] Two adjacent sides of the heat - dissipation component are respectively connected to the probe bracket and the probe body with an absorbing layer coated on the surface; preferably, the heat - dissipation component is of flat sheet type or corrugated plate type; the thickness of the heat - dissipation component is less than the diameter of the probe body, and the highest point position of the heat - dissipation component is lower than the highest point position of the front - end part of the probe bracket.

[0036] The present invention has at least the following beneficial effects compared with the prior art:

[0037] The present invention provides a method for preparing a palladium-based radio frequency probe. A palladium-based alloy formed by mixing palladium, silver, copper and other small amounts of metal elements in a specific proportion is used as the base material. After a series of processing, a tip elastic component is obtained, and then the palladium-based radio frequency probe is obtained from the tip elastic component. Thus, due to the significant decrease in the resistivity coefficient of the palladium-based alloy, its hardness and strength are also significantly increased, and it has good surface lubricity, oxidation resistance and corrosion resistance. Therefore, the problem of poor versatility of the current common beryllium copper, (rhenium) tungsten, and nickel alloy as the tip elastic component of the radio frequency probe is solved, making the palladium-based radio frequency probe prepared by the present invention applicable to different types of pads and having higher general adaptability. At the same time, by optimizing the tip shape with the electromagnetic simulation software for the palladium-based radio frequency probe prepared by the present invention, the test accuracy can be effectively improved, and the power capacity is large and the service life is longer.

[0038] In the present invention, by using a coaxial-like structure to wrap the non-tip part of the signal tip elastic component and filling a dielectric layer between the two, the resonance problem caused by the over-long exposure of the signal line and insufficient confinement of the electromagnetic field in the traditional air coplanar probe is further effectively solved. Further, by coating an absorbing layer on the surface of the probe body, the radio frequency performance of the probe is improved. At the same time, for high-power and high-current probes, a heat dissipation component is added to the micro coaxial line, and the heat dissipation component is connected to the probe bracket and the absorbing layer to improve the heat dissipation ability to further increase the power capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0040] Figure 1 is a flowchart of a method for preparing a palladium-based radio frequency probe provided by an embodiment of the present invention;

[0041] Figure 2 is a schematic diagram of the femtosecond laser cutting route of the signal tip elastic component provided by an embodiment of the present invention;

[0042] Figure 3 is a schematic diagram of the femtosecond laser cutting route of the ground tip elastic component provided by an embodiment of the present invention;

[0043] Figure 4 is a schematic structural diagram of a tip elastic component provided by an embodiment of the present invention;

[0044] Figure 5 is a side sectional view of the tip part of a tip elastic component provided by an embodiment of the present invention;

[0045] Figure 6 is a schematic structural diagram of a palladium alloy radio frequency probe provided by an embodiment of the present invention;

[0046] Figure 7 is a schematic structural diagram of another palladium alloy radio frequency probe provided by an embodiment of the present invention;

[0047] Figure 8 is a schematic diagram of a common commercial probe provided by Comparative Example 1 of the present invention;

[0048] Figure 9 and Figure 10 are both microscopic images of the tip of a common commercial probe before and after testing provided by Comparative Example 1;

[0049] Figure 11 and Figure 12 are both microscopic images of the tip of the palladium alloy radio frequency probe before and after testing provided by Example 1;

[0050] Reference numerals: 10 - tip elastic component; 101 - signal tip elastic component; 102 - ground tip elastic component; 103 - shielding layer; 20 - probe body; 30 - radio frequency connector; 40 - probe support; 50 - heat dissipation component; 60 - wave absorbing layer; 70 - limit bolt. Detailed implementation manners

[0051] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0052] With the development of radio frequency probe technology, the basic principles of radio frequency probe design have gradually emerged:

[0053] 1) The 50Ω planar transmission line of the radio frequency probe should be directly in contact with the pad of the device under test without contacting the connecting wire. For microstrip line and coplanar probe designs, the contact surface of the radio frequency probe tip should be large enough to ensure reliable and repeatable contact.

[0054] 2) In order to simultaneously contact the signal pad and the ground pad of the device under test, the radio frequency probe needs to be tilted, and this process is "probe planarization".

[0055] 3) The RF probe has a very high contact repeatability, which is better than that of coaxial connectors, ensuring that the system can be accurately calibrated and the measurement reference plane can be translated to the tip of the RF probe. This also facilitates the development of probe tips, on-chip calibration components, and dedicated calibration algorithms.

[0056] 4) Since the geometric size of the tip of the RF probe is very small, it can be assumed that the equivalent circuit of the on-chip calibration component model satisfies the "zero-order" lumped parameter model. Moreover, after knowing the geometric size of the calibration component, the calibration parameter model values can be easily obtained through methods such as three-dimensional electromagnetic field simulation software.

[0057] The current manufacturing processes of the tip elastomers of the probes can be divided into metal cutting processes represented by GGB probes, laser processing air coplanar probe processes represented by ACP probes, MEMS (Micro-Electro-Mechanical System) processes represented by Z-probe probes, and semiconductor thin film processes represented by Infinity probes, etc. However, these manufacturing processes all have their deficiencies. Facing the rapid development of current semiconductor technologies and the continuous emergence of new types of chips, it is difficult to cope with these situations. Therefore, more general RF probe technologies need to be developed to address these challenges.

[0058] The following describes the specific implementation manners of the concept of this application.

[0059] As Figure 1 shown, an embodiment of the present invention provides a preparation method of a palladium-based RF probe, including:

[0060] (1) Drying and mixing palladium powder, silver powder, copper powder, and the remaining metal mixed powder to obtain a premix;

[0061] (2) Sequentially melting, forging, rolling, and quenching the premix to obtain a palladium-based sheet;

[0062] (3) Laser cutting and polishing the palladium-based sheet to obtain a tip elastic component;

[0063] (4) Connecting the tip elastic component to one end of the probe body, connecting the RF connector to the other end of the probe body, and then placing the RF connector into the inclined insertion through hole of the probe holder to obtain a palladium-based RF probe.

[0064] In the present invention, a palladium-based alloy formed by mixing palladium, silver, copper and other minor metal elements in a specific proportion is used as the base material. After a series of processing treatments, a tip elastic component is obtained, and then a palladium-based RF probe is obtained from the tip elastic component. Thus, due to the significant decrease in the resistivity of the palladium-based alloy, its hardness and strength are also significantly increased, and it has good surface lubricity, oxidation resistance and corrosion resistance. Therefore, the problem of poor versatility of the current common beryllium copper, (rhenium) tungsten, and nickel alloy as the tip elastic component of the RF probe is solved, making the palladium-based RF probe prepared by the present invention applicable to different types of pads and having higher general adaptability. At the same time, by optimizing the tip shape with the palladium-based RF probe prepared by the present invention in combination with electromagnetic simulation software, the test accuracy can be effectively improved, and it has a large power capacity and a longer service life.

[0065] It should be noted that the tip elastic component can be arranged at one end of the probe body by means of fixed connection such as welding, or can be arranged at one end of the probe body by means of movable connection such as detachable connection.

[0066] According to some preferred embodiments, in step (1): the mass ratio of palladium powder, silver powder, copper powder and the remaining metal mixed powder is (55-60%):(34-38%):(4-6%):(0.8-1.5%) (for example, it can be 55%:38%:6%:1%, 55%:38%:5.5%:1.5%, 56%:37%:6%:1%, 57%:37%:5%:1%, 58%:35%:6%:1%, 59%:35%:5.2%:0.8% or 60%:34%:4.5%:1.5%, etc.). It should be noted that the sum of the mass percentages of palladium powder, silver powder, copper powder and the remaining metal mixed powder is 100%.

[0067] In the present invention, on the premise that the mass percentages of other components remain unchanged, if the amount of palladium powder is higher than 60%, the ductility of the prepared palladium-based sheet is poor and the cost is higher. If the amount of palladium powder is lower than 55%, the hardness of the palladium-based sheet is low, which will lead to poor wear resistance and shorten the service life of the radio frequency probe. On the premise that the mass percentages of other components remain unchanged, if the amount of silver powder is higher than 38%, the hardness of the palladium-based sheet will also decrease, resulting in easy deformation of the radio frequency tip. If the amount of silver powder is lower than 34%, the contact resistance of the palladium-based sheet increases, which will affect the fidelity of the test signal. On the premise that the mass percentages of other components remain unchanged, if the amount of copper powder is higher than 6%, it will affect the conductivity of the palladium-based sheet, and the PdCu order direction will further increase the risk of cracking. If the amount of copper powder is lower than 4%, the strength of the palladium-based sheet is low and the fatigue resistance is weak, and the radio frequency probe is prone to bending failure. Therefore, by defining the mass ratios of palladium, silver, copper and the remaining metal elements, a radio frequency probe material with high hardness, high elastic modulus, low resistivity and corrosion resistance is prepared, thereby synergistically ensuring high reliability of the radio frequency probe in the test. Among them, the palladium matrix and silver act synergistically, making the radio frequency probe suitable for complex working environments.

[0068] According to some preferred embodiments, in step (1): the remaining metal mixed powder is at least two of nickel powder, iron powder, aluminum powder, and titanium powder.

[0069] It should be noted that at least two means any two or any mixture of two or more in any proportion.

[0070] In the present invention, by adding other metals such as nickel, iron, aluminum, and titanium, the mechanical properties, corrosion resistance, high-temperature stability, etc. of the palladium-based sheet are further optimized.

[0071] According to some preferred embodiments, in step (1): the drying temperature of the drying is 30 to 100 °C (for example, it can be 30 °C, 35 °C, 40 °C, 45 °C, 50 °C, 55 °C, 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, 85 °C, 90 °C, 95 °C or 100 °C), and the drying time is 3 to 20 h (for example, it can be 3 h, 5 h, 6 h, 8 h, 10 h, 12 h, 15 h, 18 h or 20 h).

[0072] According to some preferred embodiments, in step (1): when dry mixing is carried out using a planetary ball mill, the mixing time is 2 to 8 h (for example, it can be 2 h, 3 h, 4 h, 5 h, 6 h or 8 h), the ball-to-material ratio is (4 to 30):1 (for example, it can be 4:1, 5:1, 6:1, 8:1, 10:1, 15:1, 18:1, 20:1, 25:1 or 30:1), and the rotation speed is 60 to 1000 rpm (for example, it can be 60 rpm, 100 rpm, 200 rpm, 300 rpm, 500 rpm, 600 rpm, 800 rpm or 1000 rpm).

[0073] According to some more preferred embodiments, in step (1): both drying and mixing are carried out under a protective atmosphere.

[0074] It should be noted that the protective atmosphere includes but is not limited to an argon atmosphere, a nitrogen atmosphere, a helium atmosphere, etc.

[0075] According to some preferred embodiments, in step (2): the melting temperature is 1400 to 2000 °C (for example, it can be 1400 °C, 1450 °C, 1500 °C, 1550 °C, 1600 °C, 1650 °C, 1700 °C, 1750 °C, 1800 °C, 1850 °C, 1900 °C, 1950 °C or 2000 °C), and the time is 5 to 10 min (for example, it can be 5 min, 6 min, 7 min, 8 min, 9 min or 10 min).

[0076] In the present invention, through melting, it is ensured that each metal can be fully melted and form a uniform solid solution, avoiding segregation, thereby ensuring that the finally prepared palladium-based sheet has a uniform microstructure, reducing the conductivity difference existing locally, and improving the stability of radio frequency signal transmission.

[0077] It should be noted that after melting, it is preferably held for 0.5 to 1 h and then cooled to solid state at room temperature to form an alloy ingot, and then subsequent processing is carried out. Before forging treatment, the alloy ingot needs to be heated to 900 to 1100 °C to improve the plasticity of the material and refine the grain structure.

[0078] According to some preferred embodiments, in step (2): the forging temperature is 900 to 1100 °C (for example, it can be 900 °C, 950 °C, 1000 °C, 1050 °C or 1100 °C), the single forging deformation amount is 20 to 30% (for example, it can be 20%, 22%, 24%, 25%, 26%, 28% or 30%), and the total forging deformation amount is 50 to 70% (for example, it can be 50%, 55%, 60%, 65% or 70%). It is preferably multi-directional forging, and after forging, it is held for 1 to 2 h.

[0079] According to some preferred embodiments, melting and forging are both carried out in a protective atmosphere.

[0080] In the present invention, the grains are refined by high-temperature plastic deformation, casting defects such as pores are eliminated, internal defects are reduced, thereby improving the density, enhancing the strength and toughness of the prepared palladium-based sheet, and enhancing the fatigue resistance and creep resistance of the radio frequency probe, so that the radio frequency probe is not easily deformed or broken during repeated contact tests.

[0081] According to some preferred embodiments, in step (2): rolling sequentially includes hot rolling and cold rolling;

[0082] The temperature of hot rolling is 700-900 °C (for example, it can be 700 °C, 750 °C, 800 °C, 850 °C or 900 °C), the single-pass deformation amount is 20-30% (for example, it can be 20%, 22%, 24%, 25%, 26%, 28% or 30%), and the total deformation amount is 50-60% (for example, it can be 50%, 52%, 55%, 56%, 58% or 60%); the temperature of cold rolling is 20-25 °C (for example, it can be 20 °C, 21 °C, 22 °C, 23 °C, 24 °C or 25 °C), the single-pass deformation amount is 10-15% (for example, it can be 10 °C, 11 °C, 12 °C, 13 °C, 14 °C or 15 °C), and the total deformation amount is 50-60% (for example, it can be, for example, 50%, 52%, 55%, 56%, 58% or 60%).

[0083] It should be noted that heat preservation is carried out for 0.5-1 h before each hot rolling.

[0084] In the present invention, during hot rolling, at high temperature, the alloy is a single-phase solid solution, and the plasticity is significantly improved, enabling large-deformation rolling; at the same time, the coarse grains and microcracks remaining after forging are eliminated by dynamic recrystallization. Then, during cold rolling, the hardness and surface roughness of the material are improved through work hardening and grain refinement, avoiding the risk of phase transformation. After achieving rough forming and plasticity optimization through hot rolling, the strength and dimensional accuracy of the material are further enhanced through cold rolling, avoiding the problem of cracking caused by work hardening when directly cold rolling large-size billets. It should be noted that rapid cooling after hot rolling needs to be avoided to prevent internal stress concentration. It should be noted that the thickness of the palladium-based sheet is preferably 150 μm.

[0085] According to some preferred embodiments, in step (2): the quenching temperature is 800-900 °C (for example, it can be 800 °C, 810 °C, 820 °C, 830 °C, 840 °C, 850 °C, 860 °C, 870 °C, 880 °C, 890 °C or 900 °C), and the time is 1-2 h (for example, it can be 1 h, 1.2 h, 1.4 h, 1.5 h, 1.6 h, 1.8 h or 2 h).

[0086] In the present invention, a supersaturated solid solution is obtained by rapid cooling to inhibit the precipitation of brittle phases, fix the fine crystal structure, improve hardness and wear resistance, and retain the solution strengthening effect at high temperatures.

[0087] According to some preferred embodiments, in step (3): femtosecond laser is used for laser cutting; magnetorheological polishing is used for polishing; wherein, the palladium substrate is laser cut and polished to obtain a tip elastic component with a preset pattern and a preset shape.

[0088] In the present invention, femtosecond laser is used for processing. Compared with traditional laser processing techniques, femtosecond laser processing has the advantages of high peak power, small dissociation heat effect of materials, high processing accuracy, etc. To make the cutting edge smoother, the present invention sets a specific laser energy value (for example, laser wavelength is 1030 nm, spatial spacing of ablation points is 0.1 μm, energy density is 2.18 J / cm 2 , pulse width is 290 fs, and the number of scanning passes is 100), and then uses a multi-line parallel scanning cutting method. The scanning cutting method is as Figure 2 、 Figure 3 shown. This cutting method has a smoother edge than the direct contour cutting method, with a flatness better than 1 μm and more precise characteristic impedance control. To further reduce the thermal effect of laser processing, the present invention also simultaneously uses water-guided laser, which can not only ensure precise processing accuracy, but also ensure that the processing area remains cooled and clean; at the same time, there is no need for laser focusing and distance control during the processing. The high-power pulsed laser beam is coupled into the water jet and then acts on the workpiece surface to achieve the processing process. After cutting, the obtained workpiece is polished by magnetorheological polishing (processing gap is 0.4 mm, magnetic composite fluid slurry dosage is 1 mL, rotational speed of the carrier liquid disk is 500 rpm, polishing time is 40 min). Compared with traditional polishing methods, this method has the advantages of high polishing accuracy, no tool wear and blockage phenomena, high removal rate, and no introduction of subsurface damage, etc., and can achieve near-zero subsurface damage and nano-level precision polishing. It should be noted that before laser cutting, the palladium substrate also needs to be cut.

[0089] According to some more preferred embodiments, after that, it further includes tempering treatment by standing at 200 °C for 48 h to further eliminate stress deformation.

[0090] According to some preferred embodiments, the tip elastic component includes GSG type, GS / SG type, GSSG type, and GSGSG type.

[0091] According to some preferred embodiments, as Figure 4As shown, taking the GSG type tip elastic component as an example, the tip elastic component 10 includes a signal tip elastic component 101 and a ground tip elastic component 102 arranged in parallel. The tip elastic component includes a tip part and a non-tip part.

[0092] According to some preferred embodiments, such as Figure 5 As shown, the leading edge angle of the tip part of the tip elastic component is 60° ± 1° (for example, it can be 59°, 60°, or 61°), and the trailing edge angle is 30° ± 1° (for example, it can be 29°, 30°, or 31°).

[0093] In the present invention, since all chip pads are windowed on their surface passivation layers for test contact, but there will be passivation layer steps left at the pad edges. Therefore, by designing the leading edge angle of the tip part to be 60° ± 1° and the trailing edge angle to be 30° ± 1°, the passivation layer steps can be avoided.

[0094] According to some preferred embodiments, the width of the tip part of the tip elastic component is 15μm - 50μm (for example, it can be 15μm, 16μm, 18μm, 20μm, 22μm, 25μm, 28μm, 30μm, 32μm, 35μm, 36μm, 38μm, 40μm, 42μm, 45μm, 48μm, or 50μm).

[0095] In the present invention, in order to avoid the passivation layer steps, for small pad applications, the planar morphology of the tip is designed as 15μm × 15μm, that is, the width of the tip is 15μm; while for high-power and high-current applications, the planar morphology of the tip is designed as 50μm × 20μm, that is, the width of the tip is 50μm.

[0096] The present invention also provides a palladium-based RF probe, which is obtained by using the preparation method of the palladium-based RF probe provided by the present invention.

[0097] According to some preferred embodiments, such as Figure 6 and Figure 7 As shown, the tip elastic component 10 is connected to one end of the probe body 20, and the RF connector 30 is connected to the other end of the probe body 20. The RF connector 30 is placed in the inclined insertion through hole of the probe holder 40;

[0098] There is a gap between the signal tip elastic component 101 and the ground tip elastic component 102; the non-tip part of the signal tip elastic component 101 is covered by a shielding layer 103; the shielding layer 03 is connected to the ground tip elastic component 102, and a dielectric layer is filled between the signal tip elastic component 101 and the shielding layer 103.

[0099] In the present invention, a coaxial-like structure is adopted, where a shielding layer is used to wrap the non-tip part of the signal tip elastic component, and a dielectric layer with a low dielectric constant is filled between the two. The dielectric constant is 3.4 - 3.5 (for example, it can be 3.4 or 3.5), which further effectively solves the resonance problem of traditional air coplanar probes due to the overly long exposure of the signal line and insufficient confinement of the electromagnetic field.

[0100] Specifically, a coaxial first conductor core and a second conductor core are arranged inside the probe body, and the first conductor core is located inside the second conductor core; the signal tip elastic component is connected to the first conductor core, and the ground tip elastic component is connected to the second conductor core. Among them, the probe body is a radio frequency semi-rigid cable, which successively includes a first conductor core, an insulating layer, a second conductor core, and a sheath from the inside to the outside. The first conductor core is used to transmit signals; the second conductor core is used to shield external interference signals.

[0101] In some preferred embodiments, the gap band makes the characteristic impedance 50Ω. Specifically, as Figure 4 shown, the distance d3 between the signal tip elastic component 201 and the ground tip elastic component 202, that is, the width of the gap band, is obtained through simulation, so as to ensure that the characteristic impedance is close to 50Ω by precisely controlling d3. Among them, the width of the tip is d2, and for different pad spacings, the distance d1 between the central axes of adjacent tips is mainly controlled.

[0102] According to some preferred embodiments, as Figure 7 shown, the palladium-based radio frequency probe further includes: a heat dissipation component 50;

[0103] Two adjacent sides of the heat dissipation component 50 are respectively connected to the probe support 40 and the probe body 20 with an absorbing layer 60 coated on its surface.

[0104] According to some preferred embodiments, the heat dissipation component 50 is in the shape of a flat plate or a corrugated plate; the thickness of the heat dissipation component 50 is less than the diameter of the probe body 20, and the highest point position of the heat dissipation component 50 is lower than the highest point position of the front part of the probe support 40.

[0105] According to some preferred embodiments, the heat dissipation component 50 is in the shape of a triangle, a sector, a parallelogram, or a trapezoid. The heat dissipation component 50 is made of aluminum alloy or gold-plated aluminum alloy.

[0106] Specifically, the lower end of the probe support is made of ferrite absorbing ceramic; as Figure 7 shown, a limiting bolt 70 is also provided on the probe support 20 for further fixing the radio frequency connector.

[0107] It should be noted that the absorbing layer can also only cover the part of the probe body where the second conductor core is exposed.

[0108] In the invention, by coating an electromagnetic wave absorbing layer on the outer surface of the probe body and using ferrite electromagnetic wave absorbing ceramics at the lower end of the probe holder, the radio frequency performance of the probe is improved. At the same time, for high-power and high-current probes, a heat dissipation component can also be added to the micro coaxial line, and the heat dissipation component is connected to the probe holder and the electromagnetic wave absorbing layer to improve the heat dissipation capacity and further increase the power capacity. It should be noted that the size of the heat dissipation component should not affect the line of sight, and no specific limitation is made here.

[0109] In order to more clearly illustrate the technical solutions and advantages of the present invention, a palladium-based radio frequency probe and its preparation method will be described in detail through several embodiments below.

[0110] Embodiment 1

[0111] (1) Mix palladium powder, silver powder, copper powder and the remaining metal mixed powder according to a mass ratio of 55%: 38%: 6%: 1% and dry them in an argon atmosphere at 60 °C for 10 h. Then, use a planetary ball mill to perform dry mixing for 5 h under the conditions of a ball-to-material ratio of 4:1 and a rotation speed of 500 rpm to obtain a premix; among them, the remaining metal mixed powder is composed of nickel powder, iron powder, aluminum powder and titanium powder mixed according to a mass ratio of 1:1:1:1;

[0112] (2) Place the premix in a melting furnace and melt it at 2000 °C for 5 min in an argon atmosphere. After holding for 0.5 h, cool it to room temperature to a solid state to obtain an alloy ingot; then heat the alloy ingot to 1000 °C in an argon atmosphere, forge it 3 times, with a single forging deformation of 20%, and then hold for 1 h;

[0113] Then perform hot rolling. Before each hot rolling, heat it to 900 °C and hold for 0.5 h. Perform hot rolling 3 times, with a single-pass deformation of 20% and a total deformation of 60%; then gradually cool it to room temperature of 25 °C, perform cold rolling 5 times, with a single-pass deformation of 10% and a total deformation of 50%. Finally, quench it at 800 °C for 1 h to obtain a palladium-based sheet;

[0114] (3) Use femtosecond laser to perform laser cutting on the palladium-based sheet, then perform magnetorheological polishing, and then place it at 200 °C and let it stand for 48 h for tempering treatment to obtain a tip elastic component with a preset pattern and shape, as Figure 4 shown; among them, for different pad spacings d1, for small pad applications, the planar morphology of the tip is designed to be 15 μm × 15 μm, that is, d2 is 15 μm, and the characteristic impedance is ensured to be close to 50 Ω by precisely controlling d3;

[0115] (4) As Figure 6 (GSG type) and Figure 7As shown, the tip elastic component 10 is connected to one end of the probe body 20, and the RF connector 30 is connected to the other end of the probe body 20. The RF connector 30 is placed in the inclined insertion through-hole of the probe bracket 40. There is a gap between the signal tip elastic component 101 and the ground tip elastic component 102; the leading edge angle of the tip part of the tip elastic component is 60°, and the trailing edge angle is 30°; the non-tip part of the signal tip elastic component 101 is covered by a shielding layer 103; the shielding layer 03 is connected to the ground tip elastic component 102, and a dielectric layer (dielectric constant is 3.4) is filled between the signal tip elastic component 101 and the shielding layer 103; a coaxial first conductor core and a second conductor core are arranged in the probe body, and the first conductor core is located inside the second conductor core; the signal tip elastic component is connected to the first conductor core, and the ground tip elastic component is connected to the second conductor core; the surface of the probe body 20 is covered with an absorbing layer 60; finally, a palladium-based RF probe is obtained through combination. It should be noted that in Embodiment 1, Figure 7 a heat dissipation component is not provided.

[0116] Embodiment 2

[0117] (1) Mix palladium powder, silver powder, copper powder and the remaining metal mixed powder according to the mass ratio of 60%: 34%: 4.5%: 1.5% and dry them in an argon atmosphere at 100 °C for 3 h. Then, use a planetary ball mill to perform dry mixing for 5 h under the conditions of a ball-to-material ratio of 4:1 and a rotation speed of 500 rpm to obtain a premix; among them, the remaining metal mixed powder is composed of nickel powder, iron powder, aluminum powder and titanium powder mixed according to a mass ratio of 1:1:1:1;

[0118] (2) Place the premix in a melting furnace and melt it at 1500 °C for 10 min in an argon atmosphere. After holding for 0.5 h, cool it to room temperature to a solid state to obtain an alloy ingot; then heat the alloy ingot to 1100 °C in an argon atmosphere, forge it 3 times, the single forging deformation amount of the previous time is 30%, and the single forging deformation amounts of the latter two times are 20%, and then hold for 1 h;

[0119] Then perform hot rolling. Heat it to 700 °C and hold for 0.5 h before each hot rolling. Perform hot rolling 2 times. The single-pass deformation amount of the first time is 30%, and the single-pass deformation amount of the second time is 20%, and the total deformation amount is 50%; then gradually cool it to room temperature of 25 °C, perform cold rolling 4 times, the single-pass deformation amount is 15%, and the total deformation amount is 60%. Finally, quench it at 900 °C for 1 h to obtain a palladium-based sheet;

[0120] (3) Use femtosecond laser to perform laser cutting on the palladium-based sheet, then perform magnetorheological polishing, and then place it at 200 °C and let it stand for 48 h for tempering treatment to obtain a tip elastic component with a preset pattern and a preset shape, such as Figure 4As shown; among them, for different pad spacings controlled by d1, for high-power and high-current applications, the planar morphology of the tip is designed to be 50μm×20μm, that is, d2 is 50μm, and the characteristic impedance is ensured to be close to 50Ω by precisely controlling d3;

[0121] (4) As Figure 6 (GSG type) and Figure 7 As shown, connect the tip elastic component 10 to one end of the probe body 20, connect the RF connector 30 to the other end of the probe body 20, place the RF connector 30 in the inclined insertion through hole of the probe bracket 40, and there is a gap between the signal tip elastic component 101 and the ground tip elastic component 102; the leading edge angle of the tip part of the tip elastic component is 59°, and the trailing edge angle is 31°; the non-tip part of the signal tip elastic component 101 is covered by a shielding layer 103; the shielding layer 03 is connected to the ground tip elastic component 102, and a dielectric layer (dielectric constant is 3.4) is filled between the signal tip elastic component 101 and the shielding layer 103; a coaxial first conductor core and a second conductor core are arranged in the probe body, and the first conductor core is located inside the second conductor core; the signal tip elastic component is connected to the first conductor core, and the ground tip elastic component is connected to the second conductor core; the surface of the probe body 20 is covered with an absorbing layer 60;

[0122] Two adjacent sides of the heat dissipation component 50 are respectively connected to the probe bracket 40 and the probe body 20 with an absorbing layer 60 on its surface; the heat dissipation component 50 is a triangular flat plate type, and the highest point position of it is lower than the highest point position of the front end part of the probe bracket 40, and its thickness is less than the diameter of the probe body 20; finally, the palladium-based RF probe is obtained through combination.

[0123] Comparative Example 1

[0124] A common commercial probe, which is the TITAN-RC probe of MPI Company, and its bottom view is as Figure 8 shown, and the tip of the RF probe is upward.

[0125] Comparative Example 2

[0126] Comparative Example 2 is basically the same as Example 1, and the difference is that:

[0127] In step (1), the mass ratio of palladium powder, silver powder, copper powder and the remaining metal mixed powder is 45%:38%:6%:1%.

[0128] Comparative Example 3

[0129] Comparative Example 3 is basically the same as Example 1, and the difference is that:

[0130] In step (1), the mass ratio of palladium powder, silver powder, copper powder and the remaining metal mixed powder is 55%:45%:6%:1%.

[0131] Comparative Example 4

[0132] Comparative Example 4 is basically the same as Example 1, and the difference lies in that:

[0133] In step (1), the mass ratio of palladium powder, silver powder, copper powder and the remaining metal mixed powder is 55%: 38%: 0%: 1%.

[0134] It has been experimentally confirmed that the conductivity of the palladium-based RF probes prepared in the above Example 1 and Example 2 is 25-35×106 S / m, which is close to the conductivity of silver, so it can effectively reduce the signal transmission loss; the tensile strength is 450-650 MPa, and the elongation is 12-20%, which can meet the precision structure requirements of the RF probe. Under the same test conditions, the same wafer was tested. Figure 9 、 Figure 10 shows the tip morphology of Comparative Example 1 before testing and after N tests. Figure 11 、 Figure 12 shows the tip morphology of Example 1 before testing and after 5N tests. Therefore, the service life of the palladium-based RF probe prepared in the embodiment of the present invention is much higher than that of the traditional RF probe of Comparative Example 1, and from Figure 11 and 12 shown tip morphology, the service life of the palladium-based RF probe is much higher than the number of tests. Compared with Example 1, due to the too low amount of palladium powder in Comparative Example 2, the wear resistance of the palladium-based RF probe is poor, resulting in a short service life of the RF probe; in Comparative Example 3, due to the too high amount of silver powder, the tip of the palladium-based RF is prone to deformation, resulting in a short service life of the RF probe; in Comparative Example 4, due to the lack of copper powder, the strength of the palladium-based RF probe is low and the fatigue resistance is weak, also resulting in a short service life of the RF probe.

[0135] It should be noted that Figure 9 and Figure 11 are both side views of the RF probe with the tip facing up. The upper figure is before testing and the lower figure is after testing. Among them, N is about 1000, but when it is less than 1000 times, the RF probe of Comparative Example 1 is as shown in Figure 9 and Figure 10 shown. Figure 10 and Figure 12 are both bottom views of the RF probe with the tip facing up. The upper figure is before testing and the lower figure is after testing.

[0136] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0137] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of a palladium-based radio frequency probe, characterized in that, The preparation method includes: (1) Drying and mixing palladium powder, silver powder, copper powder and the remaining metal mixed powder to obtain a premix; (2) Successively melting, forging, rolling and quenching the premix to obtain a palladium-based sheet; (3) Laser cutting and polishing the palladium-based sheet to obtain a tip elastic component; (4) Connecting the tip elastic component to one end of the probe body, connecting the RF connector to the other end of the probe body, and then placing the RF connector into the inclined insertion through hole of the probe holder to obtain the palladium-based RF probe.

2. The preparation method according to claim 1, characterized in that, In step (1): The mass ratio of the palladium powder, silver powder, copper powder and the remaining metal mixed powder is (55 - 60%):(34 - 38%):(4 - 6%):(0.8 - 1.5%); and / or, The remaining metal mixed powder is at least two of nickel powder, iron powder, aluminum powder and titanium powder.

3. The preparation method according to claim 1, wherein In step (1): The drying temperature is 30 - 100 °C and the drying time is 3 - 20 h; and / or, When dry mixing is carried out using a planetary ball mill, the mixing time is 2 - 8 h, the ball-to-material ratio is (4 - 30):1, and the rotation speed is 60 - 1000 rpm; preferably, both the drying and the mixing are carried out under a protective atmosphere.

4. The preparation method according to claim 1, characterized in that, In step (2): The melting temperature is 1400 - 2000 °C and the time is 5 - 10 min; preferably, the melting is carried out in a protective atmosphere; and / or, The forging temperature is 900 - 1100 °C, the single forging deformation amount is 20 - 30%, and the total forging deformation amount is 50 - 70%.

5. The preparation method according to claim 1, characterized in that, In step (2): The rolling successively includes hot rolling and cold rolling; The hot rolling temperature is 700 - 900 °C, the single-pass deformation amount is 20 - 30%, and the total deformation amount is 50 - 60%; the cold rolling temperature is 20 - 25 °C, the single-pass deformation amount is 10 - 15%, and the total deformation amount is 50 - 60%; and / or, The quenching temperature is 800 - 900 °C and the time is 1 - 2 h.

6. The preparation method according to claim 1, wherein In step (3): The laser cutting is carried out using femtosecond laser; the polishing is carried out using magnetorheological polishing; wherein, the laser cutting and the polishing are carried out on the palladium-based sheet to obtain a tip elastic component with a preset pattern and a preset shape.

7. The preparation method according to claim 1, wherein: The tip elastic component includes a signal tip elastic component and a ground tip elastic component arranged in parallel, and the tip elastic component includes a tip part and a non-tip part; and / or, The tip elastic component includes GSG type, GS / SG type, GSSG type and GSGSG type.

8. The preparation method according to claim 1, wherein: The leading edge angle of the tip part of the tip elastic component is 60° ± 1°, and the trailing edge angle is 30° ± 1°; and / or, The width of the tip part of the tip elastic component is 15 μm - 50 μm.

9. A palladium-based RF probe prepared by the preparation method according to any one of claims 1 to 8.

10. The palladium-based RF probe according to claim 9, wherein: A gap is provided between the signal tip elastic component and the ground tip elastic component; the non-tip part of the signal tip elastic component is covered by a shielding layer; the shielding layer is connected to the ground tip elastic component, and a dielectric layer is filled between the signal tip elastic component and the shielding layer; and / or, The palladium-based radio frequency probe further includes: a heat dissipation component; Two adjacent sides of the heat dissipation component are respectively connected to the probe bracket and the probe body covered with an electromagnetic wave absorbing layer on the surface; preferably, the heat dissipation component is in the form of a flat plate or a corrugated plate; the thickness of the heat dissipation component is less than the diameter of the probe body, and the highest point of the heat dissipation component is lower than the highest point of the front part of the probe bracket.

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