Modeling and electrical parameter extraction method based on motion trail of gold bonding wire

Abstract

The invention discloses a gold bonding wire motion trail modeling and electrical parameter extraction method, which comprises the following steps of: simulating gold bonding wire parameters of a full-automatic bonding machine through software programming, and outputting an image containing a gold wire motion trail; establishing a mathematical function expression for the motion trail of the gold wire in the image through a mathematical theory analysis method, and determining numerical values of fitting parameters in the mathematical function expression; importing the mathematical function expression into three-dimensional electromagnetic software to construct a gold wire three-dimensional physical model, simulating the gold wire three-dimensional physical model, and extracting simulation physical parameters and simulation electrical performance parameters of the gold bonding wire; accurately testing the gold bonding wire by using a TRL calibration test fixture to obtain actually measured physical parameters and actually measured electrical parameters of the gold bonding wire; and comparing the simulated physical parameters and the actually measured physical parameters of the gold bonding wire, and comparing the simulated electrical parameters and the actually measured electrical parameters of the gold bonding wire. According to the method, the motion trail and the electrical parameters of the gold wire can be accurately described, and accurate design of the hybrid integrated circuit is facilitated.

Description

Technical Field

[0001] The present invention relates to electronic engineering technology, and in particular to a method for modeling and extracting electrical parameters based on a bonding wire motion trajectory. Background Art

[0002] In microwave RF circuits, gold bonding wires, a crucial component of hybrid integrated circuit technology, connect components such as microstrip lines, chips, ceramic resistors, and capacitors, and transmit electrical performance. Physical parameters such as the length, arc height, and inter-wire spacing of the bonding wires significantly influence microwave RF transmission performance. As the frequency increases, the parasitic parameters of the bonding wires increase, leading to significant discrepancies between the wire model and actual performance, further complicating circuit design. Summary of the Invention

[0003] Purpose of the invention: The purpose of the present invention is to provide a method for modeling the motion trajectory of bonding gold wire and extracting electrical parameters, which can solve the problem that the gold wire model of the simulation software in the hybrid integrated circuit cannot correctly describe the motion curve and electrical characteristics of the actual bonding gold wire, resulting in increased circuit simulation errors, thereby improving the design accuracy of the hybrid integrated circuit.

[0004] Technical solution: The present invention provides a method for modeling the motion trajectory of a gold bonding wire and extracting electrical parameters, comprising:

[0005] The bonding wire parameters of the fully automatic bonding machine are simulated through software programming, and an image containing the movement trajectory of the wire is output;

[0006] Establishing a mathematical function expression for the gold wire motion trajectory in the image through a mathematical theoretical analysis method, and determining the values ​​of the fitting parameters in the mathematical function expression;

[0007] Import the mathematical function expression into the 3D electromagnetic software to construct a 3D physical model of the gold wire, simulate the 3D physical model of the gold wire, and extract the simulated physical parameters and simulated electrical performance parameters of the bonding gold wire;

[0008] Use the TRL calibration test fixture to accurately test the bonding wire and obtain the measured physical and electrical parameters of the bonding wire;

[0009] Compare the simulated physical parameters of the bonding gold wire with the measured physical parameters, and compare the simulated electrical parameters of the bonding gold wire with the measured electrical parameters.

[0010] Furthermore, the bonding wire parameters of the fully automatic bonding machine include smoothing radius, reversal angle, safety radius, horizontal proportion from the highest point of the arc to the first bonding point, horizontal proportion from the wire clamp closing to the second bonding point, and vertical distance from the highest point of the arc to the first bonding point.

[0011] Furthermore, the mathematical function expression is as follows:

[0012] f(x)=p0+p1*x+p2*x 2 +p3*x 3 +…+p n *x n

[0013] Where p n represents the fitting parameter, n=1,2,3…n; x represents the horizontal distance from the second bonding point to the first bonding point of the gold wire; f(x) represents the arc height of the gold wire.

[0014] Furthermore, different gold wire motion trajectories are obtained by changing the values ​​of the fitting parameters within a preset parameter range.

[0015] Furthermore, the three-dimensional physical model of the gold wire includes a bonding gold wire, an input bonding gold layer Pad area, an output bonding gold layer Pad area, a ceramic dielectric plate and an underlying grounding gold layer.

[0016] Furthermore, the TRL calibration test fixture includes a calibration piece and a test piece, a gold wire is bonded to the test piece, and the measured physical parameters of the bonded gold wire are measured using a high-power microscope.

[0017] Furthermore, the calibration component is used to accurately test the bonding wire, and combined with the de-embedding method, to extract the measured electrical parameters of the bonding pad and the bonding wire.

[0018] Furthermore, ground ports are introduced on both sides of the Z0 port of the test piece, and the Z1 port of the test piece is extended.

[0019] Furthermore, the physical parameters include the diameter of the gold wire, the height of the gold wire, the distance from the first bonding point to the second bonding point, and the shape of the movement trajectory of the bonding gold wire.

[0020] Furthermore, the medium of the TRL calibration test fixture adopts a ceramic dielectric plate.

[0021] Beneficial effects: Compared with the prior art, the significant technical effects of the present invention are as follows: (1) The key parameters of the fully automatic bonding machine are simulated using Matlab software programming, and the motion trajectory diagram of the gold wire can be intuitively output, so that the fully automatic bonding machine can bond the gold wire according to the design requirements of the programming parameters, which is close to reality. This solves the problem that designers are unclear about the state of the bonding wire of the bonding machine, and can propose the required physical shape of the gold wire for bonding within a reasonable parameter range; (2) The present invention fits the motion trajectory diagram of the bonding wire through mathematical methods, establishes a function equation, substitutes the equation into the electromagnetic simulation software to model the gold wire, and obtains the simulated electrical parameters. At the same time, the electrical parameter test results of the bonding wire after the TRL fixture is de-embedded are compared, and the two are highly consistent, further proving that this method has great engineering applicability and can effectively solve the simulation error problem of the bonding wire in hybrid integrated circuits. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the process of the present invention

[0023] Figure 2 This is the gold wire motion trajectory diagram of the fully automatic bonding machine;

[0024] Figure 3 The motion trajectory of the bonding wire and the mathematical fitting expression curve generated by Matlab software;

[0025] Figure 4 It is a three-dimensional physical model of 1, 3, and 9 gold wires Hfss;

[0026] Figure 5 The bonding diagrams are for 1, 3, and 9 gold wires;

[0027] Figure 6 Comparison of the main views of a modeling gold wire and a bonding gold wire;

[0028] Figure 7 These are the two sets of TRL calibration parts, 1# and 2#;

[0029] Figure 8 The following is a comparison chart of the simulation and test results of the S parameters of a gold wire;

[0030] Figure 9 The following is a comparison chart of the simulation and test results of the S parameters of three gold wires;

[0031] Figure 10 The figure shows the comparison between the simulation results and test results of the S parameters of 9 gold wires. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is described in detail below in conjunction with specific implementation methods and the accompanying drawings.

[0033] like Figure 1 As shown, a method for modeling the motion trajectory of a bonding wire and extracting electrical parameters of the present invention includes the following steps:

[0034] S1. Use software programming to simulate the bonding wire parameters of the fully automatic bonding machine and output an image containing the gold wire movement trajectory.

[0035] In this embodiment, the bonding wire parameters of the Hesse fifth-generation fully automatic bonding machine are simulated by Matlab software programming. The bonding method of the Hesse fifth-generation fully automatic bonding machine is wedge bonding. Figure 2 The gold wire trajectory diagram of the bonding machine shown here mainly sets the parameters for Smoothing radius (um), leaving angle (deg), Safety radius (um), Apex1 (%), Apex2 (%), and Loop height (um). Smoothing radius is the smoothing radius, leaving angle is the reversal angle, and Safety radius is the safety radius. Apex1 is the horizontal distance from the highest point of the arc to the first bonding point, and Apex2 is the horizontal distance from the closed wire clamp to the second bonding point. Loop height is the vertical distance from the highest point of the arc to the first bonding point. Matlab software is used to program and simulate the key physical parameters of the gold wire in the fully automatic bonding machine, and output an image containing the gold wire movement trajectory.

[0036] S2. Establish a mathematical function expression for the gold wire motion trajectory in the image through a mathematical theoretical analysis method, and determine the values ​​of the fitting parameters in the mathematical function expression.

[0037] like Figure 3 As shown in the figure, according to the definition of parameters, Matlab software is used to program the parameters, output the motion trajectory, and a polynomial function relationship is established for the motion trajectory of the gold wire in the image through mathematical theoretical analysis methods, namely:

[0038] f(x)=p0+p1*x+p2*x 2 +p3*x 3 +…+p n *x n (1)

[0039] Where p n represents the fitting parameter, n=1,2,3…n; x represents the horizontal distance from the second bonding point to the first bonding point of the gold wire; f(x) represents the arc height of the gold wire.

[0040] In this embodiment, the polynomial degree can be 6, where the fitting parameter values ​​are shown in Table 1.

[0041] Table 1

[0042]

[0043] By changing the parameter values ​​of the program through Matlab, different motion trajectories can be obtained, but the parameters must be within a reasonable range to achieve bonding; that is, by changing the values ​​of the fitting parameters within the preset parameter range, different gold wire motion trajectories can be obtained.

[0044] S3. Import the mathematical function expression into the three-dimensional electromagnetic software to construct a three-dimensional physical model of the gold wire, simulate the three-dimensional physical model of the gold wire, and extract the simulated physical parameters and simulated electrical performance parameters of the bonding gold wire.

[0045] The three-dimensional physical model of the gold wire can accurately characterize the electrical properties of the gold wire, including the bonding gold wire, the input bonding gold layer pad area, the output bonding gold layer pad area, the ceramic dielectric plate and the bottom grounding gold layer.

[0046] like Figure 4 As shown, the mathematical expression f(x) is imported into the electromagnetic simulation software Hfss, and the range of the independent variable x in f(x) is determined (the horizontal distance from the second bonding point to the first bonding point of the gold wire). This generates a two-dimensional trajectory line, and a three-dimensional body is generated from the line. The medium of the body is set to gold, and models of 1 gold wire, 3 gold wires, and 9 gold wires are established. Full-wave simulation is performed and electrical characteristics are output, mainly expressed as S parameters. The overall model includes:

[0047] 1. Bonding wire with a diameter of 25um;

[0048] 2. Input bonding metal layer Pad area (width 1520um, characteristic impedance 10.77ohm, length 200um, height 10um);

[0049] 3. Output bonding metal layer Pad area (width 1520um, characteristic impedance 10.77ohm, length 200um, height 10um);

[0050] 4. Ceramic dielectric plate (dielectric constant 38, width 3000um, length 900um, height 380um);

[0051] 5. Ground gold layer (width 3000um, length 900um, height 380um, height 10um);

[0052] S4. Use the TRL calibration test fixture to accurately test the bonding gold wire to obtain the measured physical parameters and measured electrical parameters of the bonding gold wire.

[0053] TRL calibration test fixture includes test piece and calibration piece, such as Figure 5As shown in the figure, one, three, and nine gold wires were bonded to the test piece, and the physical parameters of the bonded wires were measured using a high-power microscope. Using a calibration component and a de-embedding method, the measured electrical parameters of the bonded wires were extracted.

[0054] Physical parameters include gold wire diameter, gold wire height, distance from the first bonding point to the second bonding point, and shape of the bonding wire motion trajectory. Figure 6 Comparison of the main views of the modeling gold wire and the bonding gold wire.

[0055] Since the parasitic parameters of gold wire increase with the frequency, its influence on high-frequency circuits cannot be ignored. At the same time, considering the size limitation of the gold wire test environment, a TRL calibration test fixture for C and X bands (6GHz to 12GHz) is designed. Figure 7 As shown, the calibration components include: reflector (open circuit component), through component, and delay component.

[0056] TRL calibration determines the 10-term error model or the 8-term error model by measuring two transmission standards and one reflection standard. The general design requirements are as follows:

[0057] ① Reflector design: The phase of the reflection coefficient must be within ±90° and the reflection coefficient must be close to 1.

[0058] ②Through component design: When the electrical length is 0, there is no reflection and loss, and the transmission coefficient is 1; otherwise, the through component port and the delay component port must have the same characteristic impedance.

[0059] ③ Delay Component Design: The phase difference between the delay component and the through component must be between +20° and +160° (or -20° and -160°). The phase difference is generally set at 1 / 4 wavelength, or 90°. When the operating frequency range is greater than 8:1 (i.e., the ratio of the frequency span to the starting frequency is greater than 8), at least one extension cable must be used to cover the entire frequency range (this test frequency range is 6 GHz to 12 GHz, so one extension cable was used).

[0060] Due to the size constraints of the test environment, the TRL calibration test fixture uses a ceramic dielectric plate. Its dielectric constant is 38, the dielectric height is 380µm, and the gold layer thickness is 10µm. The port characteristic impedance is transformed from Z0 = 50Ω to Z1 = 10.77Ω. Furthermore, in addition to the reflector, the test fixture requires ground ports on both sides of the Z0 port to facilitate testing and calibration using a GSG150 probe. The Z1 port is extended by 200µm to serve as a bonding pad.

[0061] The physical dimensions of the gold wire were measured using an Olympus STM6 microscope. The specific physical parameters include the wire diameter, wire height, the distance between the first bonding point and the second bonding point, and the distance between adjacent gold wires. The results were compared with the Hfss model simulation results, as shown in Table 2.

[0062] Table 2

[0063]

[0064] S5. Compare the simulated physical parameters of the bonding gold wire with the measured physical parameters, and compare the simulated electrical parameters of the bonding gold wire with the measured electrical parameters.

[0065] The present invention uses the TRL calibration test fixture to test the electrical parameters of the gold wire, which is mainly reflected by the S parameters, and uses the calibration piece to calibrate the vector network analyzer so that the vector network calibration port is located at the Z1 port of the fixture, and extracts the S parameter test data after de-embedding (including the parameters of the bonding pad and the bonding wire). The S parameter frequency range is 6GHz to 12GHz, and the step size is 0.1GHz. The present invention uses Hfss electromagnetic software to establish a gold wire model and performs a 6GHz to 12GHz full-wave simulation on it to obtain S parameter simulation data (including the parameters of the bonding pad and the bonding wire). The simulation data is compared with the test data, and the comparison results are as follows. Figures 8-10 As shown, Figure 8 Figure (a) shows the comparison between the S11 and S12 parameters of a gold wire and the actual measurement. Figure 8 Figure (b) shows the comparison between the simulation and actual measurement of the S21 and S22 parameters of a gold wire.

[0066] Figure 9 Figure (a) shows the comparison between the S11 and S12 parameters of three gold wires, Figure 9 Figure (b) shows the comparison between the simulation and measured S21 and S22 parameters of three gold wires. Figure 10 Figure (a) shows the comparison between the simulated and measured S11 and S12 parameters of 9 gold wires; Figure 10 Figure (b) shows the comparison between the simulation and actual measurement of the S21 and S22 parameters of 9 gold wires.

[0067] As can be seen from the figure, the simulation data of the 1 gold wire, 3 gold wire, and 9 gold wire models are basically consistent with the test data, and their trends are basically the same. The fitting errors of the physical parameters and electrical performance parameters are small, indicating that the modeling method based on the motion trajectory of the bonding gold wire accurately describes the motion trajectory of the bonding gold wire and accurately characterizes the electrical properties of the bonding gold wire, which helps to improve the accuracy of circuit design and has engineering application value.

[0068] This method accurately characterizes the motion trajectory and electrical performance parameters of gold bonding wires. Using the TRL calibration test fixture de-embedding method, the gold wire S-parameters and electromagnetic software simulation S-parameters were extracted. The gold wire height, the distance from the first bond point to the second bond point, and the shape of the bond wire motion trajectory were measured under a high-power microscope. Comparison of the measured and simulated data revealed substantial agreement, further demonstrating the feasibility of this method, which can be used in hybrid integrated circuit design simulations and has engineering application value.

[0069] This invention effectively simulates the motion trajectory of a gold wire bonded by a fully automated machine. By establishing a mathematical function expression and building a three-dimensional physical model using electromagnetic simulation software, it can accurately characterize the electrical performance parameters of the gold wire. Furthermore, a TRL calibration test fixture is designed to precisely extract the electrical performance parameters of the bonded gold wire and measure its physical parameters.

Claims

1. A method for modeling the motion trajectory of a bonding wire and extracting electrical parameters, characterized in that: include: The bonding wire parameters of the fully automatic bonding machine are simulated through software programming, and an image containing the movement trajectory of the wire is output; Establishing a mathematical function expression for the gold wire motion trajectory in the image through a mathematical theoretical analysis method, and determining the values ​​of the fitting parameters in the mathematical function expression; Import the mathematical function expression into the 3D electromagnetic software to construct a 3D physical model of the gold wire, simulate the 3D physical model of the gold wire, and extract the simulated physical parameters and simulated electrical performance parameters of the bonding gold wire; Use the TRL calibration test fixture to accurately test the bonding wire and obtain the measured physical and electrical parameters of the bonding wire; Compare the simulated physical parameters of the bonding gold wire with the measured physical parameters, and compare the simulated electrical parameters of the bonding gold wire with the measured electrical parameters.

2. The method for modeling and extracting electrical parameters based on the motion trajectory of the bonding wire according to claim 1, characterized in that: The bonding wire parameters of the fully automatic bonding machine include smoothing radius, reversal angle, safety radius, horizontal ratio from the highest point of the arc to the first bonding point, horizontal ratio from the closing of the wire clamp to the second bonding point, and vertical distance from the highest point of the arc to the first bonding point.

3. The method for modeling and extracting electrical parameters based on the motion trajectory of the bonding wire according to claim 1, characterized in that: The mathematical function expression is as follows: f(x)=p0+p1*x+p2*x 2 +p3*x 3 +…+p n *x n Where p n represents the fitting parameter, n=1,2,3…n; x represents the horizontal distance from the second bonding point to the first bonding point of the gold wire; f(x) represents the arc height of the gold wire.

4. The method for modeling and extracting electrical parameters based on the motion trajectory of the bonding wire according to claim 3, characterized in that: By changing the values ​​of the fitting parameters within a preset parameter range, different gold wire motion trajectories are obtained.

5. The method for modeling and extracting electrical parameters based on the motion trajectory of the bonding wire according to claim 1, characterized in that: The three-dimensional physical model of the gold wire includes a bonding gold wire, an input bonding gold layer Pad area, an output bonding gold layer Pad area, a ceramic dielectric plate and an underlying grounding gold layer.

6. The method for modeling and extracting electrical parameters based on the motion trajectory of the bonding wire according to claim 1, characterized in that: The TRL calibration test fixture includes a calibration piece and a test piece. A gold wire is bonded to the test piece, and the actual physical parameters of the bonded gold wire are measured using a high-power microscope.

7. The method for modeling and extracting electrical parameters based on the motion trajectory of the bonding wire according to claim 6, characterized in that: The calibration piece is used to accurately test the bonding gold wire and extract the measured electrical parameters of the bonding gold wire in combination with the de-embedding method.

8. The method for modeling and extracting electrical parameters based on the motion trajectory of the bonding wire according to claim 6, characterized in that: Ground ports are introduced on both sides of the Z0 port of the test piece, and the Z1 port of the test piece is extended.

9. The method for modeling and extracting electrical parameters based on the motion trajectory of the bonding wire according to claim 1, characterized in that: The physical parameters include the diameter of the gold wire, the height of the gold wire, the distance from the first bonding point to the second bonding point, and the shape of the movement trajectory of the bonding gold wire.

10. The method for modeling and extracting electrical parameters based on the motion trajectory of the bonding wire according to claim 1, characterized in that: The dielectric of the TRL calibration test fixture adopts a ceramic dielectric plate.

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