Silver alloy bonding wire and method of making same

Abstract

The application discloses a silver alloy bonding wire and a preparation method thereof. The bonding wire comprises 1.1-2.2% of palladium, 4.2-9.6% of gold, 300-800ppm of trace elements and the rest of silver. The preparation method comprises the following steps: S1, proportioning according to the above-mentioned proportion; S2, adding Au, Pd and doping elements into silver raw materials according to the proportion of the materials, and obtaining a wire with a diameter of 6-8mm through a directional continuous drawing process; S3, homogenizing annealing the wire; S4, drawing the wire obtained through the melting and casting step; S5, annealing the silver alloy bonding wire after drawing; S6, surface cleaning and drying; S7, sampling the silver alloy bonding wire, and then putting the silver alloy bonding wire into a tensile testing device to perform tensile testing; and S8, after the testing, rewinding, dividing, packaging the finished silver alloy bonding wire. The silver alloy bonding wire has good oxidation resistance and ball forming property, the preparation method is simple, the tensile testing device is used for tensile testing, and the overall quality of the bonding wire in the warehouse is ensured.

Description

Technical Field

[0001] This invention relates to the field of bonding wire technology, specifically to a silver alloy bonding wire and its preparation method. Background Technology

[0002] Bonding wire is the primary connection method for linking chips to external packaging substrates and / or multilayer printed circuit boards (PCBs). From a product perspective, the development trends of bonding wire mainly focus on miniaturization, increased floor life, and longer spool lengths. Chemically, copper wire (including bare copper wire, palladium-plated copper wire, and gold-plated palladium-plated copper wire) is significantly replacing gold wire in the semiconductor field, while silver wire and silver alloy wire are replacing gold wire in LED and some IC packaging applications. Due to the miniaturization and thinning requirements of electronic products, the semiconductor industry has adopted methods such as wafer thinning, die stacking, flip chip, wafer-level packaging, 2.5D, and 3D packaging to address these challenges. However, traditional wire bonding remains the mainstream packaging method.

[0003] Existing alloy wires have poor oxidation resistance and ball-forming properties. Summary of the Invention

[0004] The problem to be solved by the present invention is to provide a silver alloy bonding wire and its preparation method. The silver alloy bonding wire of the present invention has good oxidation resistance and spherical properties. Its preparation method is simple. By using a tensile testing device to perform tensile testing, bonding wires that fail the test can be removed before entering the warehouse, thereby improving the pass rate of the bonding wires entering the warehouse and ensuring the overall quality of the bonding wires entering the warehouse.

[0005] The technical solution provided by this invention to solve the above problems is: a silver alloy bonding wire, which is prepared from the following materials in weight percentage: palladium 1.1%-2.2%, gold 4.2-9.6%, trace elements 300-800ppm, and the remainder is silver.

[0006] Preferably, the trace element is one or a combination of calcium, iron, iridium, and silicon.

[0007] Preferably, the method includes the following steps:

[0008] S1. Prepare the ingredients according to the above proportions;

[0009] S2. Au, Pd and trace elements are added to silver raw materials according to a predetermined material ratio, and wires with a diameter of 6-8 mm are obtained through a directional continuous drawing process.

[0010] S3. The wire is homogenized and annealed, and a protective gas is continuously introduced during the cooling process to room temperature;

[0011] S4. Draw the wire obtained from the melting and casting step to obtain a coarse silver alloy bonding wire with a diameter of 18-50 μm.

[0012] S5. Anneal the drawn silver alloy bonding wire again;

[0013] S6. Surface cleaning and drying;

[0014] S7. Take a sample of the silver alloy bonding wire and then put it into a tensile testing device for tensile testing;

[0015] S8. After passing the test, the finished silver alloy bonding wire is rewound, slit, and packaged.

[0016] Preferably, in step S3, the annealing temperature is controlled at 650-850℃, the annealing time is 3-6 hours, and the protective atmosphere is nitrogen.

[0017] Preferably, in step S5, the annealing temperature is 450-650℃, the annealing time is 2-6 seconds, and the protective atmosphere is 98% nitrogen plus 2% hydrogen.

[0018] Preferably, the tensile testing device in step S7 includes a test frame, a clamping assembly, and a tensile assembly, both of which are mounted on the test frame; the clamping assembly is used to clamp one end of the silver alloy bonding wire, and the tensile assembly is used to clamp the other end of the silver alloy bonding wire and apply tensile force to the silver alloy bonding wire.

[0019] Preferably, the tensile assembly includes a hydraulic cylinder, a digital tensile sensor, a clamping head, a tensile cylinder, and a protective mechanism. The hydraulic cylinder is mounted on the test frame, the tensile cylinder is connected to the output end of the hydraulic cylinder, the clamping head is connected to the digital tensile sensor, and the clamping head is used to clamp the end of the silver alloy bonding wire. The protective mechanism is used to connect the digital tensile sensor and the tensile cylinder. When the tensile force applied by the hydraulic cylinder is greater than the maximum tensile force that the digital tensile sensor can withstand, the protective mechanism disconnects the connection between the digital tensile sensor and the tensile cylinder.

[0020] Preferably, the protection mechanism includes a piston head, a first magnetic block, and a second magnetic block. The tension cylinder is provided with a piston hole that mates with the piston head. The first magnetic block is movably installed in the piston hole, and the second magnetic block is fixedly installed at the bottom of the piston hole. The first magnetic block can be attracted to the second magnetic block. The piston head and the first magnetic block are connected by a first connecting rod. The end of the piston head away from the first connecting rod is connected to a digital display tension sensor by a second connecting rod.

[0021] Preferably, the protection mechanism further includes an annular airbag, a positioning plate, and a connecting tube. The positioning plate is installed inside the piston hole and has a through hole for the connecting rod to move. The annular airbag is installed on the side of the positioning plate near the magnet. One end of the connecting tube is connected to the annular airbag, and the other end is connected to the end of the piston hole near the digital display tension sensor.

[0022] Preferably, the clamping assembly includes a clamping head, a connecting rod three, and a guide seat. The connecting rod three is mounted on the test frame, and the clamping head is mounted on the end of the connecting rod three away from the test frame. The clamping head is used to clamp the end of the silver alloy bonding wire. The guide seat is mounted on the test frame and is provided with a guide hole that mates with the silver alloy bonding wire.

[0023] Compared with the prior art, the advantages of the present invention are: the silver alloy bonding wire of the present invention has good oxidation resistance and spherical properties, its preparation method is simple, and the bonding wire that fails the test can be removed before entering the warehouse by using a tensile testing device, thereby improving the pass rate of the bonding wire entering the warehouse and ensuring the overall quality of the bonding wire entering the warehouse. Attached Figure Description

[0024] The accompanying drawings, which are provided to further illustrate the invention and constitute a part of this invention, are illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention.

[0025] Figure 1 This is a schematic diagram of the tensile testing device of the present invention;

[0026] Figure 2 yes Figure 1 Enlarged view of point A in the middle;

[0027] Figure 3 This is a schematic diagram of the tensile testing device of the present invention after the magnetic block one and magnetic block two are separated;

[0028] Figure 4 yes Figure 3 Enlarged view of point B in the middle;

[0029] Figure 5 This is a schematic diagram showing the L-shaped vent and the air outlet connected together;

[0030] Figure 6 This is a schematic diagram showing the L-shaped vent and outlet no longer connected.

[0031] Attached diagram labels: 1. Test frame, 2. Connecting rod three, 3. Clamping head, 4. Silver alloy bonding wire, 5. Guide seat, 6. Digital display tensile sensor, 7. Hydraulic cylinder, 8. Tension cylinder, 9. Vent hole, 10. Connecting pipe, 11. Positioning plate, 12. Annular airbag, 13. Piston hole, 14. Magnetic block two, 15. Magnetic block one, 16. Connecting rod one, 17. Piston head, 18. L-shaped vent hole, 19. Connecting rod two, 20. Sealing ring. Detailed Implementation

[0032] The following will describe in detail the implementation of the present invention with reference to the accompanying drawings and embodiments, so that the process of how the present invention uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0033] In the description of this invention, it should be noted that the directional terms such as "center", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", and "counterclockwise" indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. They should not be construed as limiting the specific protection scope of this invention.

[0034] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features. Thus, the use of "first" and "second" to define a feature may explicitly or implicitly include one or more of that feature, and in the description of this invention, "a number" means two or more, unless otherwise explicitly specified.

[0035] In this invention, unless otherwise explicitly specified and limited, the terms "assembly," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can also refer to a mechanical connection; they can refer to a direct connection or a connection through an intermediate medium; or they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0036] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0037] It should also be understood that the terminology used in this specification of embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of the invention. As used in this specification of embodiments of the invention and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0038] Example 1

[0039] This embodiment discloses a silver alloy bonding wire, which is prepared from the following materials in weight percentage: palladium 1.1%-2.2%, gold 4.2-9.6%, trace elements 300-800ppm, and the remainder being silver.

[0040] In this embodiment, specifically, the trace element is one or a combination of calcium, iron, iridium, and silicon.

[0041] Example 2

[0042] A method for preparing a silver alloy bonding wire, the method comprising the following steps:

[0043] S1. Prepare the ingredients according to the above proportions;

[0044] S2. Au, Pd and doping elements are added to silver raw materials according to a predetermined material ratio, and wires with a diameter of 6-8 mm are obtained through a directional continuous drawing process.

[0045] S3. The wire is homogenized and annealed. During the cooling process to room temperature, a protective gas is continuously introduced. The annealing temperature is controlled at 650-850℃, the annealing time is 3-6 hours, and the protective atmosphere is nitrogen.

[0046] S4. Draw the wire obtained from the melting and casting step to obtain a coarse silver alloy bonding wire with a diameter of 18-50 μm.

[0047] S5. Anneal the drawn silver alloy bonding wire again at a temperature of 450-650℃ for 2-6 seconds under a protective atmosphere of 98% nitrogen and 2% hydrogen.

[0048] S6. Surface cleaning and drying;

[0049] S7. Take a sample of the silver alloy bonding wire and then put it into a tensile testing device for tensile testing;

[0050] S8. After passing the test, the finished silver alloy bonding wire is rewound, slit, and packaged.

[0051] In this embodiment, the tensile testing device in step S7 includes a test frame 1, a clamping assembly, and a tensile assembly. Both the clamping assembly and the tensile assembly are mounted on the test frame 1. The clamping assembly is used to clamp one end of the silver alloy bonding wire 4, and the tensile assembly is used to clamp the other end of the silver alloy bonding wire 4 and generate tensile force on the silver alloy bonding wire 4.

[0052] Specifically, the tensile assembly includes a hydraulic cylinder 7, a digital display tensile sensor 6, a clamping head 3, a tensile cylinder 8, and a protective mechanism. The hydraulic cylinder 7 is mounted on the test frame 1. The tensile cylinder 8 is connected to the output end of the hydraulic cylinder 7. The clamping head 3 is connected to the digital display tensile sensor 6 and is used to clamp the end of the silver alloy bonding wire 4. The protective mechanism is used to connect the digital display tensile sensor 6 and the tensile cylinder 8. When the tensile force applied by the hydraulic cylinder 7 is greater than the maximum tensile force that the digital display tensile sensor 6 can withstand, the protective mechanism disconnects the connection between the digital display tensile sensor 6 and the tensile cylinder 8.

[0053] Furthermore, the protection mechanism includes a piston head 17, a first magnetic block 15, and a second magnetic block 14. The tension cylinder 8 is provided with a piston hole 13 that mates with the piston head 17. The first magnetic block 15 is movably installed in the piston hole 13, and the second magnetic block 14 is fixedly installed at the bottom of the piston hole 13. The first magnetic block 15 can be attracted to the second magnetic block 14. The piston head 17 and the first magnetic block 15 are connected by a connecting rod 16. The end of the piston head 17 away from the connecting rod 16 is connected to the digital display tension sensor 6 by a connecting rod 29. It should be noted that in order to ensure the sealing of the connection between the second connecting rod and the tension cylinder, a sealing ring 20 is installed at the connection between the second connecting rod and the tension cylinder.

[0054] Furthermore, the protection mechanism also includes an annular airbag 12, a positioning plate 11, and a connecting pipe 10. The positioning plate 11 is installed inside the piston hole 13 and has a through hole for the connecting rod 16 to move. The annular airbag 12 is installed on the positioning plate 11 on the side near the magnetic block 15. One end of the connecting pipe 10 is connected to the annular airbag 12, and the other end is connected to the end of the piston hole 13 near the digital display tension sensor 6.

[0055] The clamping assembly includes a clamping head 3, a connecting rod 3 2, and a guide seat 5. The connecting rod 3 2 is mounted on the test frame 1. The clamping head 3 is mounted on the connecting rod 3 2 at the end away from the test frame 1. The clamping head 3 is used to clamp the end of the silver alloy bonding wire 4. The guide seat 5 is mounted on the test frame 1 and is provided with a guide hole that cooperates with the silver alloy bonding wire 4.

[0056] Specifically, due to the different specifications of the silver alloy bonding wires, some silver alloy bonding wires are thicker, and the required tensile force is greater than the maximum tensile force that the digital display tensile sensor can withstand. Without protective measures, this will affect the accuracy of the digital display tensile sensor's test, and in severe cases, it may damage the digital display tensile sensor. In this invention, during the specific test, when the tensile force exceeds the attraction force between magnetic block one and electromagnetic block two, magnetic block one separates from magnetic block two. Magnetic block one moves to the left in the piston hole. During this process, the movement of magnetic block one drives the piston head to move to the left. The piston head compresses the air in the piston hole to buffer the movement of magnetic block one, preventing magnetic block one from generating huge vibrations and damage under the action of inertial force when magnetic block one separates from magnetic block two. At the same time, the force generated by magnetic block one moving to the left forces the air in the piston hole into the annular airbag to form a second buffer for magnetic block one, preventing damage to magnetic block two.

[0057] It should be noted that if inflatable components such as annular airbags are always fully inflated, they are prone to leakage due to internal air pressure, leading to airbag failure. In the solution of this invention, a piston head is used for compression inflation. When the piston head moves to the left, it compresses the air in the piston hole to inflate the annular airbag. After the magnetic block is reset, the piston head moves to the right, and the gas in the annular airbag is extracted. The annular airbag is no longer fully inflated, which improves the service life of the annular airbag. Moreover, compared with some commonly used cushioning components such as soft pads, the annular airbag can undergo greater deformation during cushioning, thus providing a better cushioning effect.

[0058] If the hydraulic cylinder outputs a large pulling force due to operational error, the inertial force of magnetic block one will be large when magnetic block one separates from magnetic block two, resulting in a large squeezing force of magnetic block two on the annular airbag, which can easily damage the annular airbag.

[0059] like Figure 2 and Figure 4 As shown, the piston head is provided with an L-shaped vent hole, and the tensioning cylinder is provided with an outlet hole. When the magnetic block compresses the annular air bladder, causing a large deformation of the annular air bladder, the L-shaped vent hole and the outlet hole are connected. Figure 5 As shown, some of the air in the annular airbag and piston hole enters through the L-shaped vent and flows out through the outlet. The reduced gas pressure inside the annular airbag prevents damage from the large impact of the second magnetic block. Here, the deformation of the annular airbag provides the first layer of buffering for the second magnetic block, offsetting most of the piston's inertial force. As the piston head continues to move to the left, the L-shaped vent and outlet are no longer connected. Figure 6 As shown, the piston head compresses the air in the piston hole, causing the air pressure in the piston hole and the annular air bladder to reach a balance, forming a second buffer for the magnetic block.

[0060] The above description only illustrates the preferred embodiments of the present invention and should not be construed as limiting the scope of the claims. The present invention is not limited to the above embodiments, and variations in its specific structure are permitted. All modifications made within the scope of the independent claims of this invention are also within the scope of protection of this invention.

Claims

1. A method of making a silver alloy bonding wire, characterized by: Prepared from the following materials in the following weight percentages: 1.1-2.2% palladium, 4.2-9.6% gold, 300-800 ppm trace elements, and the remainder silver; The method Comprises the following steps, S1, ingredients are prepared according to the above proportions; S2, Au, Pd and trace elements are added to the silver raw material in a predetermined material ratio, and a directional continuous drawing process is performed to obtain a wire with a diameter of 6-8 mm; S3, the wire is homogenized and annealed, and protection gas is supplied during cooling to room temperature; S4, the wire obtained in the melting and casting step is drawn to obtain a silver alloy bonding wire with a diameter of 18-50 um; S5, the drawn silver alloy bonding wire is annealed again; S6, surface cleaning and drying; S7, the silver alloy bonding wire is sampled and then placed in a tensile testing device for tensile testing; S8, after testing, the finished silver alloy bonding wire is rewound, divided, and packaged; The tensile testing device in step S7 comprises a test frame (1), a clamping assembly and a stretching assembly, both of which are installed on the test frame (1); the clamping assembly is used to clamp one end of the silver alloy bonding wire (4), and the stretching assembly is used to clamp the other end of the silver alloy bonding wire (4) and generate tension on the silver alloy bonding wire (4); The stretching assembly comprises a hydraulic cylinder (7), a digital tensile force sensor (6), a clamping head (3), a stretching cylinder (8) and a protection mechanism, the hydraulic cylinder (7) is installed on the test frame (1), the stretching cylinder (8) is connected with the output end of the hydraulic cylinder (7), the clamping head (3) is connected with the digital tensile force sensor (6), the clamping head (3) is used to clamp the end of the silver alloy bonding wire (4), and the protection mechanism is used to connect the digital tensile force sensor (6) and the stretching cylinder (8), when the tension applied by the hydraulic cylinder (7) is greater than the maximum tension that the digital tensile force sensor (6) can withstand, the protection mechanism disconnects the connection between the digital tensile force sensor (6) and the stretching cylinder (8); The protection mechanism comprises a piston head (17), a magnetic block one (15) and a magnetic block two (14), the stretching cylinder (8) is provided with a piston hole (13) matched with the piston head (17), the magnetic block one (15) is movably installed in the piston hole (13), the magnetic block two (14) is fixedly installed at the bottom of the piston hole (13), the magnetic block one (15) can be attracted to the magnetic block two (14), the piston head (17) is connected with the magnetic block one (15) through a connecting rod one (16), and the end of the piston head (17) away from the connecting rod one (16) is connected with the digital tensile force sensor (6) through a connecting rod two (19); The protection mechanism further comprises a ring-shaped air bag (12), a positioning plate (11) and a connecting pipe (10), the positioning plate (11) is installed in the piston hole (13), the positioning plate (11) is provided with a through hole for the movable connecting rod (16), the ring-shaped air bag (12) is installed on the positioning plate (11) and close to one side of the magnetic block (15), one end of the connecting pipe (10) is communicated with the ring-shaped air bag (12), and the other end is connected with one end of the piston hole (13) close to the digital display tension sensor (6). The clamping assembly comprises a clamping head (3), a connecting rod three (2) and a guide seat (5), the connecting rod three (2) is installed on the test frame (1), the clamping head (3) is installed on the connecting rod three (2) and away from one end of the test frame (1), the clamping head (3) is used for clamping the end of the silver alloy bonding wire (4), and the guide seat (5) is installed on the test frame (1), the guide seat (5) is provided with a guide hole matched with the silver alloy bonding wire (4).

2. A method of making a silver alloy bonding wire according to claim 1, characterized in that: The microelement is one or a combination of multiple of calcium, iron, iridium and silicon.

3. A method of making a silver alloy bonding wire according to claim 1, characterized in that: In the step S3, the annealing temperature is 650-850 ℃, the annealing time is 3-6 hours, and the protective atmosphere is nitrogen.

4. The method of claim 1, wherein the silver alloy bonding wire is prepared by the steps of: In the step S5, the annealing temperature is 450-650 ℃, the annealing time is 2-6 seconds, and the protective atmosphere is 98% nitrogen and 2% hydrogen. ​

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