Method for machining glass substrate through hole through array integrated electrode electrochemical discharge

Abstract

The invention relates to the technical field of non-traditional machining, and discloses an array integrated electrode electrochemical discharge machining method for a glass substrate through hole, and the method comprises the following steps: immersing a glass workpiece in a non-Newtonian fluid electrolyte with a shear thinning characteristic; an adjustable positive and negative bipolar pulse power supply is used for applying voltage to the array integrated electrode, so that the two electrodes are alternately gassed to form a gas layer and generate electrochemical discharge; a damping environment is constructed by utilizing rheological characteristics of an electrolyte, bubble resistance is increased to inhibit fluctuation of a gas layer, and discrete bubbles are restrained to backfill and repair the gas layer; and controlling electrode feeding, and removing the material through high-temperature melting and chemical etching to form the through hole. The gas layer stability is improved through non-Newtonian fluid damping constraint, and equal-loss and equal-energy electrochemical discharge of the electrode is realized in cooperation with a polarity alternating mechanism, so that the high-aspect-ratio and high-precision glass through hole is obtained, and the machining continuity and stability are improved.

Description

Technical Field

[0001] This invention relates to the field of special processing technology, specifically a method for electrochemical discharge processing of through holes in a glass substrate using an array of integrated electrodes. Background Technology

[0002] Currently, with the rapid development of 5G communication, artificial intelligence, and high-performance computing technologies, the demand for high-frequency signal transmission, low power consumption, and high-density integration in chips is becoming increasingly urgent. In the post-Moore's Law era, 3D packaging technologies, represented by through-glass vias (TWs), have gradually become a crucial choice surpassing through-silicon vias (TSVs) in the packaging of radio frequency chips and microelectromechanical systems (MEMS) due to the excellent high-frequency electrical properties of glass materials, the elimination of the need for additional insulating layers, and low cost. How to achieve high aspect ratio and high-quality glass via array processing at low cost has become a key link in promoting the development of advanced electronic packaging technologies.

[0003] To address the manufacturing requirements for through-holes in glass substrates, electrochemical discharge machining (EDM), a non-contact composite processing technology, is widely used for micro-hole machining of hard and brittle insulating materials such as glass and ceramics due to its lack of limitations in material hardness and strength and its excellent process flexibility. This process typically utilizes a tool electrode and an auxiliary electrode immersed in an electrolyte to construct a conductive circuit. When the voltage applied between the two electrodes exceeds a critical value, bubbles generated by electrolysis on the electrode surface converge and form a gas layer. This gas layer is broken down under high voltage, generating a discharge spark. The high-temperature melting effect released by the discharge, combined with a chemical corrosion effect, removes the workpiece material, thereby forming a microporous structure on the insulating substrate.

[0004] However, existing electrochemical discharge machining (EDM) technologies still face numerous technical bottlenecks in fabricating high-precision array vias. Conventional electrolyte environments lack damping constraints on the fluid, and the shock waves generated by discharge can easily cause severe disturbances or even ruptures in the gas layer, resulting in random dispersion of the discharge point and reduced geometric accuracy and processing controllability of the vias. Simultaneously, the traditional discrete electrode layout causes most electrolytic bubbles to escape due to buoyancy, failing to effectively participate in gas layer construction. This not only leads to low energy utilization but also easily causes bubble accumulation and microcrack propagation at the entry point of the processing zone. Furthermore, with increasing processing depth, electrolyte exchange and gas layer replenishment at the bottom of deep holes become extremely difficult, often leading to discharge interruption or instability. In addition, the uneven electrode wear in fixed polarity processing modes makes it difficult to ensure the consistency of micro-hole dimensions during array processing, failing to meet the precision manufacturing requirements of high-end packaging fields.

[0005] Therefore, the present invention provides a method for electrochemical discharge processing of through holes in glass substrates using an array of integrated electrodes, in order to overcome the shortcomings of the prior art. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for electrochemical discharge machining of through-holes in glass substrates using an integrated array of electrodes. This method solves the problems of low machining accuracy, limited aspect ratio, and poor array consistency in existing electrochemical discharge machining technologies, which are caused by poor gas layer stability, low energy utilization, and uneven electrode wear.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for electrochemically discharging an array of integrated electrodes to process through-holes in a glass substrate, comprising the following steps: A shear-thinning non-Newtonian fluid electrolyte is injected into an electrolyte tank, and the glass workpiece is fixedly immersed in it. The integrated electrode array is moved to the initial processing position above the glass workpiece; An adjustable positive and negative bipolar pulse power supply is used to apply a bipolar pulse voltage to the integrated array electrodes, so that the two poles of the integrated electrodes alternate polarity, gas is generated in the electrolyte to form a gas layer and break down to produce electrochemical discharge, and the discharge is damped by rheological properties. The integrated electrode of the control array is fed, and the material is removed by high-temperature discharge melting and chemical etching to form a glass through hole.

[0008] Preferably, the integrated array electrode includes an insulated integrated electrode retaining handle and two array electrode plates; the retaining handle clamps the two array electrode plates to keep them physically parallel and electrically isolated.

[0009] Preferably, each of the array electrode sheets has an array electrode end processed at its lower end; the step of moving to the initial processing position includes aligning the array electrode end with the area to be processed on the glass workpiece.

[0010] Preferably, in the step of applying bipolar pulse voltage, the current is transmitted through two independent paths: one array electrode sheet is connected to the integrated electrode clamp via the upper conductive block of the fixed handle; the other sheet is connected to the current-carrying bearing via the lower conductive block.

[0011] Preferably, the step of applying bipolar pulse voltage is achieved by a rotating conductive system, which includes a lead bearing fixing bracket on the spindle, on which one pole and the other pole lead bearing, which are insulated from each other, are respectively connected to the two output terminals of the power supply.

[0012] Preferably, the step of applying damping constraint includes: increasing the fluid resistance of bubble movement by utilizing the viscosity characteristics of the non-Newtonian fluid electrolyte to suppress random fluctuations in the gas layer.

[0013] Preferably, the non-Newtonian fluid electrolyte can be prepared by mixing a polymeric electrolyte (such as polyacrylamide) with an electrolyte such as KOH or NaOH in deionized water at different ratios (polymeric electrolyte 0.1wt%-1wt%, KOH, etc. 10wt%-40wt%). Preferably, the step of applying damping constraint further includes: using electrolyte to constrain the escaping discrete bubbles, causing them to aggregate and remain at the electrode end and integrate into the gas layer, thereby repairing the gas layer damage caused by the discharge impact.

[0014] Preferably, the step of applying a bipolar pulse voltage includes: controlling the power supply to periodically change the polarity, so that hydrogen and oxygen are alternately released on both sides of the electrode, thereby achieving the removal of electrode wear and other materials.

[0015] Preferably, the control electrode movement step is achieved by an XYZ three-axis motion platform equipped with an electrolyte tank; the glass workpiece is fixed by a fixture, and the immersion depth meets the processing coverage requirements.

[0016] Preferably, after forming the glass through-hole, the method further includes: controlling the electrode to retract and starting the electrolyte circulation system to circulate and refresh the electrolyte, maintaining its temperature, level and cleanliness.

[0017] This invention provides a method for electrochemically discharging through-holes in a glass substrate using an array of integrated electrodes. It offers the following advantages: 1. This invention improves energy utilization and processing efficiency by using an integrated array of electrodes with an insulating layer in conjunction with a bipolar pulse power supply and utilizing the bubbles generated by the auxiliary electrode to participate in the discharge. At the same time, the integrated structure maintains a constant electrode gap, and with the continuous polarity changing mechanism, equal wear of the electrodes and equal probability removal of materials are achieved, thereby ensuring high precision and consistency in glass through-hole processing.

[0018] 2. This invention employs a non-Newtonian fluid electrolyte with shear-thinning properties, utilizing the damping confinement effect of the fluid to effectively increase gas layer stability and reduce disturbances, concentrating discharge energy at the electrode tip. This not only limits the discharge processing range and improves the controllability of the processing, but also improves the shape accuracy of the through-hole, which is particularly beneficial for the precision machining of small-pitch TGV glass array through-holes.

[0019] 3. The method of this invention is not only applicable to glass materials, but also covers the precision machining of insulating or semiconductor materials such as ceramics and semiconductor silicon wafers. Furthermore, the device design is highly compatible, requiring only simple upgrades to traditional milling or drilling machine tools, offering advantages such as low equipment cost and high upgrade potential, providing an economical and efficient technical option for the electronic packaging field. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the novel integrated electrode electrochemical discharge processing device according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the electrochemical discharge processing principle of the integrated array electrode according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the integrated array electrode structure and the power supply method according to an embodiment of the present invention; Figure 4 This is a schematic diagram of a novel method for electrochemical discharge processing of glass through-hole TGV using an integrated array electrode according to an embodiment of the present invention. Figure 5 This is a schematic flowchart of a method for electrochemically discharging a glass substrate through-hole using an integrated array electrode, according to an embodiment of the present invention.

[0021] The components include: 1. Adjustable bipolar pulse power supply; 2. Motion control system; 3. Electrolyte tank; 4. Workpiece fixture; 5. XYZ three-axis motion platform; 6. Platform base; 7. Rotary spindle; 8. Spindle holder; 9. Electrostatic bearing fixing bracket; 10. One-pole electrostatic bearing; 11. Electrode chuck; 12. The other-pole electrostatic bearing; 13. Integrated electrode; 14. Insulating workpiece; 15. Electrolyte; 16. Electrolyte circulation system; 21. Integrated electrode chuck; 22. Conductive block; 23. Integrated electrode fixing handle; 24. Array of electrodes. 25. Electrode end; 26. Electrostatic bearing; 31. Adjustable positive and negative bipolar pulse power supply; 32. Glass workpiece; 33. Glass through-hole; 34. Glass array through-hole TGV; 101. Adjustable bipolar pulse power supply; 102. Integrated array electrode; 103. Non-Newtonian fluid electrolyte; 104. Gas layer; 105. Electrochemical discharge; 106. Glass workpiece; 107. Machined hole; 108. Glass through-hole TGV; 110. Insulating layer; 301. Integrated array electrode; 302. Electrochemical discharge. Detailed Implementation

[0022] See attached document Figure 1 This invention provides a method for electrochemical discharge machining of through holes in glass substrates using an array of integrated electrodes. This method is achieved through a novel integrated electrode electrochemical discharge machining device, which mainly consists of a motion and support system, a machining environment circulation system, and a rotating conductive system. The subsystems work together to ensure the precision and stability of the micromachining.

[0023] The device is based on a platform base 6, which is made of high-rigidity marble or cast iron and has excellent shock absorption performance. An XYZ three-axis motion platform 5, electrically connected to the motion control system 2, is mounted on it. The XYZ three-axis motion platform 5 is driven by a high-precision linear motor or servo motor, and with closed-loop feedback from a linear encoder, it can achieve micron-level positioning accuracy. The motion control system 2 controls the displacement of the XYZ three-axis motion platform 5 in three axes through an interpolation algorithm, realizing relative motion during the machining process.

[0024] The electrolyte tank 3 is fixedly mounted on the horizontal axis of the platform and moves with the platform. It is made of transparent acrylic or polytetrafluoroethylene material resistant to acid and alkali corrosion, facilitating observation of the internal processing status. The tank contains a non-Newtonian fluid electrolyte 15 with shear-thinning properties, such as an alkaline solution with added polyacrylamide or xanthan gum. The insulated workpiece 14 is fixedly clamped by a workpiece clamp 4, which has a leveling function to ensure the workpiece surface is parallel to the horizontal plane and that the workpiece is completely immersed in the electrolyte 15, meeting the processing area coverage requirements. An electrolyte circulation system 16, connected to the electrolyte tank 3, is responsible for circulating and refreshing the electrolyte 15. The system integrates a microporous filter and a temperature control unit, capable of filtering out glass particles and electrolytic products generated during processing, and controlling the liquid temperature within ±1℃ to maintain its temperature, liquid level, and cleanliness, ensuring the stability of the electrolyte conductivity.

[0025] A spindle holder 8 is fixed on the Z-axis of the XYZ three-axis motion platform 5, within which a high-precision rotary spindle 7 is installed, with spindle runout controlled within 2μm. The output end of the rotary spindle 7 is coaxially clamped to an integrated electrode 13 via an electrode chuck 11, and its feed or retraction in the vertical direction is controlled by the system. To achieve stable power supply during rotation, the rotary spindle 7 is equipped with a current-carrying bearing fixing bracket 9, on which are mounted mutually insulated single-pole current-carrying bearing 10 and another-pole current-carrying bearing 12. These two bearings use copper alloy or gold-plated contact surfaces with excellent conductivity, respectively contacting the conductive parts of the rotary spindle 7 and connecting to the two output ends of the adjustable bipolar pulse power supply 1, providing bipolar pulse current to the integrated electrode 13 during rotation, effectively avoiding the spark interference problem of traditional carbon brushes under high-speed rotation.

[0026] See attached document Figure 2 This paper elucidates the physicochemical mechanism of this embodiment. The system mainly involves an adjustable bipolar pulse power supply 101, an integrated array electrode 102, a non-Newtonian fluid electrolyte 103, and a glass workpiece 106. The integrated array electrode 102 consists of two electrode structures physically separated by an insulating layer 110. The insulating layer 110 is typically made of polyimide or ceramic film with a thickness controlled at the tens of micrometer level. After the power supply is turned on, hydrogen and oxygen are alternately generated on both sides of the electrode in the non-Newtonian fluid electrolyte 103, acting as anode and cathode. Due to the extremely close distance between the two electrodes, the dissimilar gases rapidly converge to form a gas layer 104 enveloping the electrode. When the applied voltage exceeds the critical breakdown voltage, the gas layer 104 is broken down, generating an electrochemical discharge 105.

[0027] The rheological properties of the non-Newtonian fluid electrolyte 103 create a damping constraint effect in the processing zone: in the near-wall region where the electrode rotates at high speed, the fluid viscosity decreases due to high shear force, which is conducive to bubble generation and aggregation; while in a slightly farther region, the fluid viscosity increases rapidly, forming a high-viscosity liquid wall, increasing the resistance to bubble movement and suppressing the random fluctuations of the gas layer 104. Simultaneously, this high viscosity characteristic constrains the escaping discrete bubbles, causing them to aggregate and remain at the end of the integrated array electrode 102, replenishing and integrating into the gas layer 104 to repair the gas layer damage caused by the discharge impact, maintaining the continuity of the discharge and reducing energy consumption. Under the synergistic effect of high-temperature plasma melting generated by electrochemical discharge 105 and high-temperature chemical etching of the fluid, the material of the glass workpiece 106 is removed to form the processing hole 107, and with the electrode feed, a high aspect ratio glass through-hole TGV108 is finally formed. The adjustable bipolar pulse power supply 101, through alternating polarity changes, prevents passivation of the electrode surface, achieving equal-loss wear of the integrated array electrode 102 and equal-probability removal of material.

[0028] See attached document Figure 3 This describes the structure and electrical connections of the integrated array electrode. The electrode consists of an insulated integrated electrode holder 23, two array electrode plates 24, and a current-leading assembly. The array electrode plates 24 are made of high-temperature resistant and corrosion-resistant tungsten or hard alloy material. The integrated electrode holder 23 clamps the two array electrode plates 24, keeping them physically parallel and electrically isolated. Each electrode plate has an array electrode end 25 machined at its lower end, with the array spacing matching the spacing of the chip pads to be processed. To achieve independent bipolar power supply, the device is equipped with two conductive blocks 22. One array electrode plate 24 is connected to the upper conductive block 22 and the integrated electrode chuck 21, receiving current from one pole; the other array electrode plate 24 is connected to the lower conductive block 22 and the current-leading bearing 26, receiving current from the other pole. This structure, together with the integrated electrode chuck 21 and the current-leading bearing 26, forms two independent rotary power supply circuits, ensuring stable bipolar power supply even under high-speed rotation.

[0029] See attached document Figure 4 and attached Figure 5 The method mainly includes the following steps: Step S1: Prepare a non-Newtonian fluid electrolyte, adjust its rheological index to match the electrode rotation speed, and inject it into the tank. Fix the glass workpiece 32 with a clamp and immerse it in the liquid, with the liquid level 5-10 mm above the workpiece surface, to create a damping environment using the fluid properties.

[0030] Step S2: Control the motion axis to drive the integrated array electrode 301 to move, use the tool setting device to determine the zero point, and accurately align its end with the initial processing position above the glass workpiece 32, usually maintaining an initial gap of 10-50μm.

[0031] Step S3: Turn on the adjustable positive and negative bipolar pulse power supply 31, set the pulse frequency and duty cycle, and apply alternating pulse voltages to the integrated array electrode 301. Gas is alternately released at both electrodes to form a gas layer, generating a stable electrochemical discharge 302 under the damping constraint effect. The polarity reversal mechanism achieves equal electrode losses and uniform material removal.

[0032] Step S4: Control the integrated array electrode 301 to feed vertically downwards at a constant speed or constant load, in conjunction with the horizontal movement of the glass workpiece 32. Under the action of high-temperature melting and chemical etching, material is removed to form glass through-holes 33, and finally, glass array through-holes TGV34 are machined. After processing, the electrode is retracted and the circulation system is started to update the electrolyte. Finally, the workpiece is ultrasonically cleaned to remove residues.

Claims

1. A method for electrochemically discharging an array of integrated electrodes to process through-holes in a glass substrate, characterized in that, Includes the following steps: A non-Newtonian fluid electrolyte (15) with shear-thinning properties is injected into an electrolyte tank (3), and a glass workpiece (32) is fixedly immersed in the non-Newtonian fluid electrolyte (15); The control array integrated electrode (301) is moved to the initial processing position above the glass workpiece (32); A bipolar pulse voltage is applied to the integrated array electrode (301) using an adjustable positive and negative bipolar pulse power supply (31), so that the two electrodes integrated in the integrated array electrode (301) alternately serve as cathode and anode, gas is generated in the non-Newtonian fluid electrolyte (15) and a gas layer (104) is formed. The gas layer (104) is broken down to generate an electrochemical discharge (302). The rheological properties of the non-Newtonian fluid electrolyte (15) are used to apply damping constraint to the electrochemical discharge (302). The array of integrated electrodes (301) is fed to remove the material from the glass workpiece (32) by high-temperature melting and chemical etching, forming a glass through hole (33).

2. The method for electrochemical discharge processing of through-holes in a glass substrate using an integrated array of electrodes according to claim 1, characterized in that, The array integrated electrode (301) includes an insulated integrated electrode fixing handle (23) and two array electrode plates (24). The integrated electrode fixing handle (23) clamps and fixes the two array electrode plates (24), so that the two array electrode plates (24) remain physically parallel and electrically isolated.

3. The method for electrochemical discharge processing of through-holes in a glass substrate using an integrated array of electrodes according to claim 2, characterized in that, Each of the array electrode sheets (24) has an array electrode end (25) machined at its lower end. The step of moving the integrated control array electrode (301) to the initial processing position above the glass workpiece (32) includes aligning the end (25) of the array electrode with the area to be processed on the glass workpiece (32).

4. The method for electrochemical discharge processing of through-holes in a glass substrate using an integrated array of electrodes according to claim 2, characterized in that, In the step of applying the bipolar pulse voltage, the current is transmitted to the two array electrode plates (24) through two independent conductive paths: One of the array electrode plates (24) is connected to the integrated electrode clamp (21) via a conductive block (22) located on the upper part of the integrated electrode fixing handle (23), and receives current from the integrated electrode clamp (21); Another of the array electrode plates (24) is connected to the electric bearing (26) via a conductive block (22) located at the lower part of the integrated electrode fixing handle (23) and receives current from the electric bearing (26).

5. The method for electrochemical discharge processing of through-holes in a glass substrate using an integrated array of electrodes according to claim 1, characterized in that, The step of applying bipolar pulse voltage is achieved by a rotating conductive system, which includes an electric bearing fixing bracket (9) fixed on a rotating spindle (7). The electric bearing fixing bracket (9) is equipped with a one-pole electric bearing (10) and a other-pole electric bearing (12) that are insulated from each other. The one-pole electric bearing (10) and the other-pole electric bearing (12) are respectively connected to the two output terminals of the adjustable positive and negative bipolar pulse power supply (31).

6. The method for electrochemical discharge processing of through-holes in a glass substrate using an integrated array of electrodes according to claim 1, characterized in that, The step of applying damping constraint to the electrochemical discharge (302) using the rheological properties of the non-Newtonian fluid electrolyte (15) includes: The viscosity characteristics of the non-Newtonian fluid electrolyte (15) are used to increase the fluid resistance of bubble movement and suppress the random fluctuations of the gas layer (104).

7. The method for electrochemical discharge processing of through-holes in a glass substrate using an integrated array of electrodes according to claim 6, characterized in that, The step of applying damping constraint to the electrochemical discharge (302) using the rheological properties of the non-Newtonian fluid electrolyte (15) further includes: The non-Newtonian fluid electrolyte (15) is used to apply a constraint force to the escaping discrete bubbles, causing the discrete bubbles to gather and remain in the end region of the integrated array electrode (301), so that the discrete bubbles can be integrated into the gas layer (104) to repair the gas layer damage caused by the discharge impact.

8. The method for electrochemical discharge processing of through-holes in a glass substrate using an integrated array of electrodes according to claim 1, characterized in that, The step of applying the bipolar pulse voltage includes: The adjustable positive and negative bipolar pulse power supply (31) is controlled to periodically change the output polarity, so that hydrogen bubbles and oxygen bubbles are alternately released on both sides of the integrated array electrode (301), thereby achieving equal wear of the integrated array electrode (301) itself and removing the material in the glass through hole (33) area with equal probability.

9. The method for electrochemical discharge processing of through-holes in a glass substrate using an integrated array of electrodes according to claim 1, characterized in that, The step of moving the integrated control array electrode (301) is achieved by the XYZ three-axis motion platform (5), and the electrolyte tank (3) is fixedly installed on the XYZ three-axis motion platform (5); The glass workpiece (32) is fixedly clamped by the workpiece clamp (4), and the immersion depth of the insulating workpiece (14) meets the requirement that the processing area is covered by the non-Newtonian fluid electrolyte (15).

10. The method for electrochemical discharge processing of through-holes in a glass substrate using an integrated array of electrodes according to claim 1, characterized in that, The process further includes, after the step of forming the glass through-hole (33): Control the retraction of the integrated array electrode (301); Start the electrolyte circulation system (16) connected to the electrolyte tank (3) to circulate and refresh the non-Newtonian fluid electrolyte (15) and maintain the temperature, liquid level and cleanliness of the non-Newtonian fluid electrolyte (15).

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