Preparation equipment and method of palladium-plated bonding wire rod blank

Abstract

The invention provides equipment and a method for preparing a palladium-plated bonding wire rod blank. The equipment comprises a closed smelting system, a vacuumizing system, a shielding gas system, a clamping guide system and a palladium-plated composite assembly, the closed smelting system is used for providing a closed smelting space; the vacuumizing system is used for communicating with the closed smelting system and vacuumizing the smelting space; the protective gas system is used for injecting protective gas into the smelting space; the clamping and guiding system is used for clamping the palladium-plated composite assembly and guiding the lower end of the palladium-plated composite assembly into the smelting containing cavity, a suction pipeline is further arranged in the clamping and guiding system, and molten liquid in the smelting containing cavity can enter the palladium-plated composite assembly under the action of negative pressure so as to form a palladium-plated bonding wire rod blank. Due to the existence of a closed space, vacuum and protective gas, the palladium plating stability is ensured; the oxidation process is avoided through multiple times of vacuumizing operation, so that the palladium-plated bonding wire has excellent mechanical and electrical properties, and the influence on the environment is small due to separation from the environment.

Description

Technical Field

[0001] The invention relates to the technical field of chip packaging, and in particular to a preparation device and method for a palladium-plated bonding wire rod blank. Background Art

[0002] As electronic packaging develops towards miniaturization, multi-function and low cost, the packaging industry has put forward higher requirements on packaging form and packaging materials. Wire bonding is the earliest chip packaging technology, which realizes the interconnection between the device and its package body through metal wires.

[0003] Gold is the traditional type of bonding wire, but its electrical and thermal conductivity make it more challenging to use in high-density and fine-pitch packaging. At the same time, the cost of gold wire continues to increase, leading to the gradual marginalization of gold applications.

[0004] Copper's electrical and thermal conductivity are higher than gold, and its cost is much lower than gold, making copper widely accepted as a new bonding wire material. However, since copper wire is easily oxidized in the environment, oxidation barrier technology is an important way to solve the problem of bare copper wire being easily oxidized.

[0005] Among the numerous oxidation barrier layer (gold, silver, palladium, nickel) technologies, palladium-plated copper wire has become the bonding wire with the greatest potential to replace gold wire due to its good bondability and reliability.

[0006] At present, the production of palladium-plated copper bonding wire generally adopts electroplating and chemical plating technology, which is to continuously cast copper into wire billets, and then electroplate or chemically plate the copper bonding wire online after rough drawing, medium drawing and fine drawing. These two technologies cause serious environmental pollution, and the investment in equipment and factory buildings is also relatively large, and the production efficiency is low. On the one hand, it increases production costs, and on the other hand, it also brings tremendous pressure to the ecological environment.

[0007] In order to develop a green and environmentally friendly palladium-plated copper bonding wire production process, people have been seeking an ideal technical solution. Summary of the invention

[0008] The purpose of the present invention is to address the deficiencies in the prior art and thereby provide a preparation device and method for a palladium-plated bonding wire rod blank which is green, environmentally friendly, low in production cost and excellent in quality.

[0009] In order to achieve the above-mentioned object, the technical solution adopted by the present invention is: a preparation device for palladium-plated bonding wire rod blanks, including a closed melting system, a vacuum system, a protective gas system, a clamping and guiding system and a palladium-plated composite component;

[0010] The closed smelting system is used to provide a closed smelting space, wherein the smelting space has a smelting cavity and a heating component for heating the smelting cavity;

[0011] The vacuuming system is used to connect to the closed smelting system and evacuate the smelting space;

[0012] The protective gas system is used to inject protective gas into the smelting space;

[0013] The clamping and guiding system is used to clamp the palladium-plated composite component and introduce the lower end of the palladium-plated composite component into the smelting chamber. The clamping and guiding system is also provided with a suction pipeline connected to the palladium-copper composite component. The suction pipeline is connected to the vacuum system or an additional negative pressure suction component. The molten liquid in the smelting chamber can enter the palladium-plated composite component under the action of negative pressure to form a palladium-plated bonding wire rod blank.

[0014] Based on the above, the palladium-plated composite assembly includes a high-purity graphite tube and a pure palladium tube;

[0015] The high-purity graphite tube is an outer tube, the pure palladium tube is closely attached to the inner wall of the high-purity graphite tube and fixed to the lower part of the high-purity graphite tube, and a supporting step is arranged inside the high-purity graphite tube for the pure palladium tube.

[0016] Based on the above, an in-place detection sensor is provided on the upper part of the inner wall of the palladium-plated composite component, and the in-place detection sensor is used to detect the rising liquid level of the copper melt. The in-place detection sensor is associated with the vacuum system or additional negative pressure suction component externally connected to the suction pipeline in the clamping and guiding system, so as to stop the suction action after the molten liquid rises to the set liquid level.

[0017] Based on the above, the palladium-plated composite assembly also includes a support tube, which is tightly attached to the inner wall of the high-purity graphite tube and fixed to the top of the high-purity graphite tube. A gap is left between the lower end of the support tube and the top of the pure palladium tube, and the in-place detection sensor is installed at the lower end of the support tube.

[0018] Based on the above, the in-place detection sensor is a thermal sensor or a pressure sensor.

[0019] Based on the above, the clamping and guiding system includes a connecting sleeve, the connecting sleeve is sealed outside and penetrates the top of the closed smelting system and conducts the inside and outside of the smelting space, and the suction pipeline is connected to the outer end of the connecting sleeve.

[0020] Based on the above, the clamping and guiding system further comprises a lifting mechanism and a movable sealing ring, wherein the lifting mechanism is used to drive the connecting sleeve to rise and fall, and the connecting sleeve can be vertically movable through the movable sealing ring to seal with the closed smelting system.

[0021] Based on the above, the closed smelting system includes a closed smelting furnace, a furnace cover is arranged on the top of the smelting furnace, and the connecting sleeve is installed in cooperation with the furnace cover through a movable sealing ring; the smelting space is formed inside the smelting furnace, the smelting cavity is a high-purity graphite crucible, and the heating component is installed in the base of the high-purity graphite crucible, and the heating component adopts a medium frequency heating unit with an operating frequency of 1kHz to 5kHz, and has an electromagnetic stirring function.

[0022] Based on the above, the vacuum system includes a diffusion pump and a mechanical pump group, the diffusion pump is directly connected to the smelting furnace, the mechanical pump group is connected to the connecting sleeve through a suction pipe, and the suction pipe is a vacuum bellows.

[0023] A method for preparing a palladium-plated bonding wire rod blank, comprising the above-mentioned palladium-plated bonding wire rod blank preparation device, is implemented by the following steps:

[0024] Step 1) opening the smelting space of the closed smelting system, and placing a high-quality electrolytic copper plate with a purity of more than 99.99% into the smelting chamber;

[0025] Step 2) Close the smelting space of the closed smelting system and use the vacuum system to evacuate the smelting space to a vacuum degree of 1*10 -2 When the vacuum degree of the smelting space reaches the set value, close the vacuum system; open the protective gas system and introduce the protective gas until the vacuum degree of the smelting space reaches the set value, and then close the protective gas system;

[0026] Step 3) turning on the heating component to heat the smelting chamber until the raw material is completely melted;

[0027] Step 4) increasing the power to electromagnetically stir the molten raw material and keeping it warm at the set temperature;

[0028] Step 5) The smelting space is vacuumed for the second time to 1-10 Pa by using a vacuum system, and then a protective gas is introduced therein to a vacuum degree of ≤0.01 Mpa;

[0029] Step 6) controlling the clamping and guiding system to insert the lower end of the pure palladium tube into the smelting chamber, and maintaining the vacuum degree of the smelting space;

[0030] Step 7) turning off the heating component, extracting the copper melt through the suction pipeline with the aid of the vacuum pumping system or the additional negative pressure suction component, and when the copper melt reaches a set height, turning off the vacuum pumping system or the additional negative pressure suction component, the copper melt solidifies and is compounded with the pure palladium tube;

[0031] Step 8) After the closed smelting system is completely cooled, the pure palladium tube is taken out, and the redundant structure of the pure palladium tube is removed to obtain a palladium-plated bonding wire rod blank.

[0032] The present invention has outstanding substantive features and significant progress compared to the prior art. Specifically, the present invention has the following advantages:

[0033] 1. From the equipment level, compared with the high solution pollution problem existing in the physical combination of traditional electroplating and chemical palladium plating, the present invention adopts vacuum extraction of the plating molten liquid to metallurgically combine it with the palladium tube under gas protection conditions, and the whole process takes place in a closed, vacuumized smelting space, which minimizes the impact on the environment.

[0034] 2. The copper melt is directly metallurgically bonded to the palladium tube by sucking it under negative pressure, so the coating is more stable and not easy to fall off.

[0035] 3. The present invention uses one vacuuming to obtain a basic vacuum degree, uses a second vacuuming and injection of protective gas to protect the plating material melt, and then uses a three-time suction of the plating material melt to achieve three-time vacuum degassing, so that the plating material gas content in the bonding wire blank is greatly reduced, thereby improving the mechanical and electrical properties of the palladium-plated bonding wire.

[0036] 4. In the design of the palladium tube, a pressure-sensitive or thermal-sensitive sensor is used to sense whether the copper melt has risen to the right position, thereby controlling the degree of vacuuming; the palladium tube is wrapped with an outer layer of high-purity graphite tube to maintain the metallurgical bonding process between the palladium tube and the plating material melt; a support tube is used to improve the structural strength of the palladium tube so that it can be stably connected to the connecting sleeve; the high-purity graphite tube is easy to break and not easy to react with metal to simplify the process of finally removing the high-purity graphite tube, thereby obtaining a palladium-plated bonding wire rod blank with a stable bonding.

[0037] 5. From the perspective of the method, the present invention changes the two processes of continuous casting wire billet and palladium plating in the traditional palladium-plated bonding wire into a single process of palladium tube and pure plating material, which greatly reduces the process complexity;

[0038] Taking palladium-plated copper bonding wire rod blanks as an example, in terms of bonding performance, the crystallization efficiency of pure copper is increased by 120-160%, the overall production efficiency of palladium-plated bonding wire is increased by 60-70%, and the production cost is reduced by 30-40%. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a structural schematic diagram of the equipment for preparing the palladium-plated bonding wire rod blank in the present invention.

[0040] Figure 2 The present invention is a schematic structural diagram of a palladium tube clamping portion in a device for preparing a palladium-plated bonding wire rod blank.

[0041] Figure 3 It is a cross-sectional view of the palladium-plated bonding wire rod blank of the present invention.

[0042] Figure 4 It is an actual product picture of the bonding surface of the palladium-plated bonding wire rod blank in the present invention.

[0043] Figure 5 It is a performance comparison chart of the palladium-plated copper bonding wire in the present invention and the commercially available 20 μm palladium-plated copper bonding wire.

[0044] In the figure: 1. Melting furnace; 2. High-purity graphite crucible; 3. Palladium-copper composite device; 4. Furnace cover; 5. Movable sealing ring; 6. Suction pipeline; 7. Mechanical pump group; 8. Locking ring; 9. Diffusion pump; 10. Argon tank; 11. Connecting sleeve; 12. High-purity graphite tube; 13. Rubber ring; 14. Support steel pipe; 15. Pure palladium tube; 16. Crucible base; 17. Medium-frequency heating unit; 18. Lifting mechanism; 19. Copper. DETAILED DESCRIPTION

[0045] The technical solution of the present invention is further described in detail below through specific implementation methods.

[0046] This embodiment is described by taking the preparation of a palladium-plated copper bonding wire rod blank as an example. In addition to copper, in other embodiments, other materials such as silver may be correspondingly replaced to form a palladium-plated silver bonding wire rod blank.

[0047] like Figure 1 and Figure 2 As shown, a preparation device for a palladium-plated bonding wire rod blank includes a closed melting system, a vacuum system, a protective gas system, a clamping and guiding system and a palladium-copper composite device 3.

[0048] In this embodiment, the closed smelting system is used to provide a closed smelting space, specifically including a closed smelting furnace 1, a furnace cover 4 is arranged at the top of the smelting furnace 1, the furnace cover 4 and the smelting furnace 1 are sealed by a locking ring 8 and a sealing ring, a smelting space is formed in the smelting furnace 1, and a smelting cavity and a heating component for heating the smelting cavity are arranged inside. In this embodiment, the smelting cavity adopts a high-purity graphite crucible 2, and the heating component adopts a medium frequency heating unit 17. Since the principle of the medium frequency heating unit 17 is electromagnetic heating, electromagnetic stirring of the copper melt can also be achieved under the drive of electromagnetic force.

[0049] In other embodiments, the closed smelting system may also use other types of closed smelting spaces, such as other types of kilns, etc., the smelting cavity may use other types of crucibles, the heating component may use electric heating, and the stirring component may use an ordinary stirring structure or an independent electromagnetic stirring mechanism.

[0050] The vacuum system is used to connect the closed smelting system and evacuate the smelting space. In this embodiment, the vacuum system mainly includes a diffusion pump 9 and a mechanical pump group 7. The diffusion pump 9 is directly connected to the smelting furnace 1, and the mechanical pump group 7 is connected to the smelting furnace 1 through a vacuum bellows, a clamping guide system and a palladium-copper composite device 3.

[0051] In the mechanical pump group, a rotary vane pump is designed. The rotary vane pump is used to extract the molten copper and obtain vacuum. The rotary vane pump can maintain the vacuum degree when it stops, thereby ensuring the stability of the molten copper in the pure palladium tube.

[0052] In other embodiments, the vacuum system can also use other types of vacuum pump combinations.

[0053] The protective gas system is used to inject protective gas into the smelting space. In this embodiment, the protective gas is argon gas, which is externally connected to an argon gas tank 10. In other embodiments, the protective gas may also be other types of inert gases.

[0054] The clamping and guiding system is used to clamp the pure palladium tube and introduce the lower end of the pure palladium tube into the smelting chamber. The clamping and guiding system is also provided with a suction pipeline 6 connected to the inner tube of the pure palladium tube. In this embodiment, a vacuum bellows is selected. The suction pipeline 6 is connected to the mechanical pump group 7.

[0055] In this embodiment, the end of the clamping and guiding system is a connecting sleeve 11. In this embodiment, the connecting sleeve 11 is made of a steel sleeve. The connecting sleeve 11 is externally sealed and penetrates the top of the closed smelting system and conducts the inside and outside of the smelting space. The suction pipeline 6 is connected to the outer end of the connecting sleeve 11.

[0056] In this embodiment, the palladium-copper composite device 3 is kept vertical in the smelting furnace 1, with its lower end facing the high-purity graphite crucible 2 and its upper end connected to the connecting sleeve 11, and the copper melt is attracted into the palladium-copper composite device 3 by the suction force.

[0057] Specifically, in a preferred embodiment, an in-place detection sensor (not shown in the figure) is provided on the upper part of the inner wall of the palladium-copper composite device 3, and the in-place detection sensor is used to detect the rising liquid level of the copper melt. The in-place detection sensor is associated with the vacuum system or additional negative pressure suction component externally connected to the suction pipeline 6 in the clamping and guiding system, so as to stop the suction action after the copper 19 melt rises to the set liquid level. In this embodiment, the in-place detection sensor can select a thermal or pressure-sensitive sensor. In other embodiments, contact or optical in-place detection sensors can also be selected.

[0058] In order to protect the safety of the palladium tube and maintain the vertical state of the palladium tube, the palladium-copper composite device 3 includes a high-purity graphite tube 12 and a pure palladium tube 15; the high-purity graphite tube 12 is an outer tube, and the pure palladium tube 15 is close to the inner wall of the high-purity graphite tube 12 and fixed to the lower part of the high-purity graphite tube 12. A supporting step is provided in the high-purity graphite tube for the pure palladium tube, the purpose of which is to lock the position of the pure palladium tube 15, while preventing the pure copper melt from directly contacting the pure palladium tube and damaging the pure palladium tube 15, providing a channel for the copper melt to rise, and combining with the pure palladium tube as the copper melt cools during the rising process.

[0059] In a preferred embodiment, in order to protect the clamping stability of the high-purity graphite tube 12, the palladium-copper composite device 3 also includes a support tube 14, which is close to the inner wall of the high-purity graphite tube 12 and fixed to the top of the high-purity graphite tube 12. A gap is left between the lower end of the support tube 14 and the top of the pure palladium tube 15, and the in-place detection sensor is installed at the lower end of the support tube 14. In this embodiment, in order to ensure the stability of the support tube, its material is selected to form a support steel tube.

[0060] The support tube 14 is located in cooperation with the connecting sleeve 11 as the end structure of the clamping and guiding system. The cooperation between the two can be filled with a rubber ring 13 to ensure the sealing performance on the one hand and protect the high-purity graphite tube 12 from damage on the other hand.

[0061] In a preferred embodiment, in order to keep the palladium-copper composite device 3 away from the molten copper during the heating process of the molten copper, and immerse the palladium-copper composite device 3 in the molten copper again after the molten copper is heated, a lifting mechanism 18 and a movable sealing ring 5 are added to the clamping and guiding system. The lifting mechanism 18 is used to drive the connecting sleeve 11 to rise and fall. The connecting sleeve 11 can be vertically movable through the movable sealing ring 5 to seal with the closed smelting system. The movable sealing ring 5 can be a threaded ring, and the locking and sealing of the connecting sleeve can be achieved by loosening and tightening.

[0062] The method for preparing a palladium-plated bonding wire rod blank by using the above-mentioned palladium-plated bonding wire rod blank preparation equipment comprises the following steps:

[0063] Step 1) Open the furnace cover and place a high-quality electrolytic copper plate with a purity of more than 99.99% into a high-purity graphite crucible;

[0064] Step 2) Close the furnace cover and turn on the mechanical pump and diffusion pump in sequence until the vacuum reaches 1*10 -2 Pa, then turn off the vacuum system in turn, open the argon valve of the protective gas system, introduce high-purity argon gas until the vacuum degree in the furnace is 0.05Mpa, and close the argon valve;

[0065] Step 3) Turn on the medium frequency heating, preheat with a power of 5 to 10 kW for 5 to 10 minutes, then increase the power to 15 to 20 kW until the raw material is completely melted;

[0066] Step 4) increasing the power to 30-35 kW to stir the copper melt using electromagnetic force and keeping the temperature at 1100-1150° C.;

[0067] Step 5) Turn on the mechanical pump group to evacuate to 1-10 Pa, then introduce high-purity argon gas into the furnace until the vacuum degree in the furnace is 0.01 MPa, and then close the argon valve;

[0068] Step 6) Unscrew the sealing nut above the furnace cover, start the lifting mechanism, insert the graphite tube 10 to 20 mm from the bottom of the high-purity graphite crucible, and tighten the sealing nut above the furnace cover;

[0069] Step 7) turn off the medium frequency induction heating, turn on the rotary vane pump in the mechanical pump group to extract the molten copper, and when the molten copper contacts the pressure-sensitive or thermistor sensor at the bottom of the supporting steel tube, turn off the rotary vane pump, and the molten copper solidifies and compounds with the pure palladium tube on the inner wall of the high-purity graphite tube;

[0070] Step 8) After the crucible is completely cooled, the sealing nut on the furnace cover is unscrewed, and the high-purity graphite tube is lifted by a lifting mechanism. The graphite tube is removed and broken, and the head and tail are sawed off along the edge of the palladium tube to obtain the palladium-plated bonding wire rod blank, as shown in FIG. Figure 3 shown.

[0071] Comparison of impurity content in palladium-copper composite rod blanks:

[0072] Oxygen, nitrogen and hydrogen analyzers were used to analyze the oxygen, nitrogen and hydrogen contents of the conventional vacuum gas-protected continuous casting copper rod and the copper core of the palladium-copper composite rod blank of the present invention. The oxygen, nitrogen and hydrogen contents of the method of the present invention were much lower than those of the conventional method. The method of the present invention improved the cleanliness of the palladium-copper composite rod blank.

[0073]

[0074] Interface bonding: Figure 4 As shown, the interface of the palladium-copper composite rod is well bonded.

[0075] Bonding wire performance comparison 1:

[0076] 20 μm palladium-plated copper bonding wire ( Figure 5 a and b) and commercially available 20μm palladium-plated copper bonding wire ( Figure 5 By comparing c and d), the surface of the coating of the palladium-plated copper bonding wire prepared by the present invention is flat, smooth, uniform, and has no obvious defects, while the commercially available palladium-plated copper bonding wire has slight unevenness, and even has coating peeling, copper exposure or pore defects, which will seriously affect the performance of the palladium-plated copper bonding wire.

[0077] Bonding wire performance comparison example 2:

[0078] During the wire bonding process, the working conditions of the bonding wire are very complex, especially for the bonding wire on the high-speed automatic bonding machine, which requires the bonding wire to have a higher breaking force and elongation. For the bonding wire, its breaking force and elongation play a key role in the quality of wire bonding, and the bonding wire with high breaking force and elongation is more conducive to bonding.

[0079] The YG001 B single fiber electronic strength meter was used to measure the breaking force and elongation of the 20μm palladium-plated copper bonding wire prepared by the method of the present invention and the commercially available 20μm palladium-plated copper bonding wire. The average value of 10 samples was taken. The breaking force of the palladium-plated bonding wire prepared by the method of the present invention was 6.8cN, while the breaking force of the commercially available palladium-plated copper bonding wire was 5.4cN; the elongation of the palladium-plated bonding wire prepared by the method of the present invention was 10.6%, while the elongation of the commercially available palladium-plated copper bonding wire was 9.3%. The breaking force and elongation of the palladium-plated copper bonding wire prepared by the present invention are higher than those of the commercially available palladium-plated copper bonding wire.

[0080] Bonding wire performance comparison example 3:

[0081] According to the metal conductivity theory, the resistance of metals is caused by the scattering of electron waves. However, the scattering of electron waves often occurs where the integrity of the crystal lattice is destroyed. Based on this principle, Matthiessen Rule expresses the resistivity (ρ) of metals as: ρ = ρ r +ρ t ,ρ r is the resistivity related to impurities and lattice defects (point defects, line defects and surface defects), ρ t The resistivity is temperature-dependent. Take 10 samples and take the average value. The resistivity of the palladium-plated bonding wire prepared by the method of the present invention is 0.01716Ω*mm 2 / m, while the resistivity of commercially available palladium-plated copper bonding wire is 0.01717Ω*mm 2 / m, the resistivity of the palladium-plated bonding wire prepared by the method of the present invention is slightly lower than that of the commercially available palladium-plated copper bonding wire.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the present invention, which should be included in the scope of the technical solution for protection of the present invention.

Claims

1. A preparation device for palladium-plated bonding wire rod blanks, characterized in that: It includes a closed melting system, a vacuum system, a protective gas system, a clamping and guiding system, and a palladium-plated composite component; The closed smelting system is used to provide a closed smelting space, wherein the smelting space has a smelting cavity and a heating component for heating the smelting cavity; The vacuuming system is used to connect to the closed smelting system and evacuate the smelting space; The protective gas system is used to inject protective gas into the smelting space; The clamping and guiding system is used to clamp the palladium-plated composite component and introduce the lower end of the palladium-plated composite component into the smelting chamber. The clamping and guiding system is also provided with a suction pipeline connected to the palladium-copper composite component. The suction pipeline is connected to the vacuum system or an additional negative pressure suction component. The molten liquid in the smelting chamber can enter the palladium-plated composite component under the action of negative pressure to form a palladium-plated bonding wire rod blank.

2. The preparation equipment for palladium-plated bonding wire rod blank according to claim 1, characterized in that: The palladium-plated composite assembly comprises a high-purity graphite tube and a pure palladium tube; The high-purity graphite tube is an outer tube, the pure palladium tube is closely attached to the inner wall of the high-purity graphite tube and fixed to the lower part of the high-purity graphite tube, and a supporting step is arranged inside the high-purity graphite tube for the pure palladium tube.

3. The preparation equipment of the palladium-plated bonding wire rod blank according to claim 1 or 2, characterized in that: An in-place detection sensor is provided on the upper part of the inner wall of the palladium-plated composite component. The in-place detection sensor is used to detect the rising liquid level of the copper melt. The in-place detection sensor is associated with the vacuum system or additional negative pressure suction component externally connected to the suction pipeline in the clamping and guiding system, so as to stop the suction action after the melt rises to the set liquid level.

4. The preparation equipment for palladium-plated bonding wire rod blank according to claim 3, characterized in that: The palladium-plated composite assembly also includes a support tube, which is tightly attached to the inner wall of the high-purity graphite tube and fixed to the top of the high-purity graphite tube. A gap is left between the lower end of the support tube and the top of the pure palladium tube, and the in-place detection sensor is installed at the lower end of the support tube.

5. The preparation equipment of the palladium-plated bonding wire rod blank according to any one of claims 2 to 4, characterized in that: The in-position detection sensor is a thermal sensor or a pressure sensor.

6. The preparation equipment for palladium-plated bonding wire rod blank according to claim 1, characterized in that: The clamping and guiding system comprises a connecting sleeve, the connecting sleeve is sealed outside and penetrates the top of the closed smelting system and conducts the inside and outside of the smelting space, and the suction pipeline is connected to the outer end of the connecting sleeve.

7. The preparation equipment for palladium-plated bonding wire rod blank according to claim 6, characterized in that: The clamping and guiding system further comprises a lifting mechanism and a movable sealing ring. The lifting mechanism is used to drive the connection sleeve to rise and fall. The connection sleeve can be vertically movable through the movable sealing ring to seal with the closed smelting system.

8. The preparation equipment for palladium-plated bonding wire rod blank according to claim 1, 6 or 7, characterized in that: The closed smelting system includes a closed smelting furnace, a furnace cover is arranged on the top of the smelting furnace, and the connecting sleeve is installed in cooperation with the furnace cover through a movable sealing ring; the smelting space is formed inside the smelting furnace, the smelting cavity is a high-purity graphite crucible, and the heating component is installed in the base of the high-purity graphite crucible. The heating component adopts a medium frequency heating unit with an operating frequency of 1kHz to 5kHz and has an electromagnetic stirring function.

9. The preparation equipment for palladium-plated bonding wire rod blank according to claim 8, characterized in that: The vacuum pumping system comprises a diffusion pump and a mechanical pump group, wherein the diffusion pump is directly connected to the smelting furnace, and the mechanical pump group is connected to the connecting sleeve through a suction pipe, and the suction pipe is a vacuum bellows.

10. A method for preparing a palladium-plated bonding wire rod blank, characterized in that: The preparation device of the palladium-plated bonding wire rod blank according to any one of claims 1 to 9 is implemented by the following steps: Step 1) Open the smelting space of the closed smelting system and place a high-quality electrolytic copper plate with a purity of more than 99.99% into the smelting chamber; Step 2) Close the smelting space of the closed smelting system and use the vacuum system to evacuate the smelting space to a vacuum degree of 1*10 -2 When the vacuum degree of the smelting space reaches the set value, close the vacuum system; open the protective gas system and introduce the protective gas until the vacuum degree of the smelting space reaches the set value, and then close the protective gas system; Step 3) Turn on the heating component to heat the smelting chamber until the raw material is completely melted; Step 4) Increase the power to electromagnetically stir the molten raw materials and keep them warm at the set temperature; Step 5) The smelting space is vacuumed for the second time to 1-10 Pa by using a vacuum system, and then protective gas is introduced into the smelting space to a vacuum degree of ≤0.01 MPa; Step 6) Controlling the clamping and guiding system to insert the lower end of the pure palladium tube into the smelting chamber, and maintaining the vacuum degree of the smelting space; Step 7) Turn off the heating component, extract the copper melt through the suction pipeline with the help of the vacuum system or the additional negative pressure suction component, and when the copper melt reaches the set height, turn off the vacuum system or the additional negative pressure suction component, and the copper melt solidifies and is compounded with the pure palladium tube; Step 8) After the closed smelting system is completely cooled, the pure palladium tube is taken out, and the redundant structure of the pure palladium tube is removed to obtain a palladium-plated bonding wire rod blank.

Images