High-density package internal flip-chip and filler structure equivalent model construction method

Abstract

The application discloses a high-density package internal flip-chip welding and filler structure equivalent model construction method, which comprises the following steps: selecting a suitable electronic package device, obtaining device structure and material parameters, establishing a pre-simplified model of the electronic package device, calculating equivalent parameters of the simplified model, and determining a final simplified model of the electronic device. The application selects an electronic component to establish a corresponding finite element model, simplifies the flip-chip welding and the bottom filler glue structure in the finite element modeling, establishes a pre-simplified model, simplifies part of the solder ball layer and the bottom filler glue into a uniform layer, and retains the detailed structure of the outer ring several solder ball layers. Representative volume units are established, material parameters of the homogenization layer are calculated, the influence of the number of outer solder ball rings on the stress of the dangerous point of the solder ball layer is simulated and calculated, it is determined that the detailed structure of the outer ring two solder ball layers can obtain more accurate results, and the final simplified model of the flip-chip welding and the bottom filler glue in the high-density package is obtained.

Description

Technical Field

[0001] This invention belongs to the technical field of microelectronics, specifically relating to a method for constructing an equivalent model of flip-chip bonding and filler structure inside a high-density package. Background Technology

[0002] Currently, reliability research on high-density packaged flip-chip soldering mainly focuses on the critical locations and fatigue life prediction of solder balls under temperature cycling and vibration shock.

[0003] Because the experiments are quite complex and time-consuming, the research mainly focuses on finite element simulation. It should be noted that the small size and large number of solder balls in high-density packaging lead to complex modeling. Therefore, an equivalent model of the flip-chip bonding area is needed to simplify the solder ball layer structure.

[0004] There are various methods for simplifying solder balls, including sub-modeling, material homogenization, and global-local simplification. However, sub-modeling and global-local simplification methods cannot simplify the solder ball array structure of flip-chip bonding and underfill, and the modeling is relatively cumbersome. Material homogenization is more attractive for simplifying the underfill and solder ball structure. However, since it completely simplifies all solder balls and underfill, it leads to a large error between simulation and experimental results. This is because the failure location of solder balls is mainly in the outermost layer, and simplifying the outermost solder balls introduces calculation errors. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for constructing an equivalent model of the internal flip-chip bonding and filler structure of high-density packaging, which can simplify complex finite element models while ensuring simulation accuracy.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for constructing an equivalent model of the internal flip-chip bonding and filler structure of high-density packages, including:

[0008] Step S1: Select electronic packaging devices and obtain device structure parameters and material parameters;

[0009] Step S2: Establish a pre-simplified finite element model of the electronic packaging device;

[0010] Step S3: Obtain the equivalent parameters of the simplified part of the model;

[0011] Step S4: Determine the final simplified finite element model of the electronic device.

[0012] Preferably, in step S1, the flip-chip bonding spacing inside the electronic packaging device is kept consistent.

[0013] Preferably, in step S1, the device structural parameters include the length, width, and height of the structure, and the material parameters include density, elastic modulus, Poisson's ratio, coefficient of thermal expansion, heat transfer coefficient, and specific heat capacity.

[0014] Preferably, in step S2, the electronic packaging device is modeled using a SolidWorks model, and the selected parameters of the model are heat sink, thermal interface material, chip, flip chip, filler and ceramic substrate.

[0015] Preferred options also include:

[0016] Multiple high-density packaging models were established, gradually transitioning to retaining the number of outer flip-chip solder rings.

[0017] Preferably, in step S3, the equivalent parameters of the simplified high-density packaging are obtained by simulating tensile and shear experiments using the finite element method Abaqus.

[0018] Preferably, in step S4, the same sinusoidal impact load and constraints are applied to the established pre-simplified model using AnsysWorkbench, and the stress simulation results of the flip-chip soldering and filler are extracted. If the stress value of one of the pre-simplified models differs from that of the previous model by no more than 1%, the final simplified model of the high-density package is determined.

[0019] The beneficial effects of this invention are as follows: By selecting a specific electronic component and establishing a corresponding finite element model, the flip-chip soldering and underfill structures in the finite element modeling are simplified; a pre-simplified model is established, simplifying some solder ball layers and underfill into uniform layers, while retaining the detailed structure of the outer few solder ball layers; by establishing representative volume elements, the material parameters of the uniformized layer are calculated; by simulating the influence of the number of outer solder ball rings on the stress at critical points of the solder ball layer, it is determined that retaining the detailed structure of the outer two solder ball layers can obtain more accurate results, thus obtaining the final simplified model of flip-chip soldering and underfill in high-density packaging. This model not only greatly simplifies the computational complexity of flip-chip soldering and filler but also ensures extremely high simulation accuracy. This invention simplifies the finite element model of flip-chip soldering and filler in high-density packaging, simplifying the model complexity while maintaining computational accuracy. Attached Figure Description

[0020] The features, advantages, and technical effects of exemplary embodiments of the present invention will now be described with reference to the accompanying drawings.

[0021] Figure 1 This is a flowchart of the method for constructing the finite element equivalent model of the internal flip-chip soldering and filler structure of the high-density package of the present invention.

[0022] Figure 2 This is a high-density packaging structure diagram of the present invention.

[0023] Figure 3 This is a simplified model diagram of the high-density packaging structure of the present invention, featuring flip-chip bonding and underfill.

[0024] Figure 4 This is a structural diagram of the flip-chip welding and underfill adhesive unit of the present invention.

[0025] Figure 5 This is a calculation model diagram of the equivalent heat transfer coefficient of inverted welding and bottom filling according to the present invention.

[0026] Figure 6 This is the simulation model and boundary condition diagram of the present invention.

[0027] Figure 7 This is a graph showing the application of simulated load and time variation according to the present invention.

[0028] Figure 8 This is a comparison chart of the simulation stress results of the dangerous points of the solder ball layer of the present invention over time. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In the description of this specification, the reference to the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., means that the specific feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and combine the different embodiments or examples and the features of different embodiments or examples described in this specification.

[0030] The following is in conjunction with the appendix Figures 1-8 The present invention will be described in further detail, but this is not intended to limit the invention.

[0031] A method for constructing an equivalent model of the internal flip-chip bonding and filler structure of high-density packages, including:

[0032] Step S1: Select electronic packaging devices and obtain device structure parameters and material parameters;

[0033] Step S2: Establish a pre-simplified finite element model of the electronic packaging device;

[0034] Step S3: Obtain the equivalent parameters of the simplified part of the model;

[0035] Step S4: Determine the final simplified finite element model of the electronic device.

[0036] It should be noted that this invention simplifies the flip-chip soldering and underfill structure in finite element modeling by selecting a specific electronic component and establishing a corresponding finite element model. A pre-simplified model is established, simplifying some solder ball layers and underfill into uniform layers, while retaining the detailed structure of the outer few solder ball layers. Representative volume elements are established to calculate the material parameters of the uniformized layer. Simulation calculations determine the impact of the number of outer solder ball rings on the stress at critical points in the solder ball layer, confirming that retaining the detailed structure of the outer two solder ball layers yields more accurate results. This results in the final simplified model of flip-chip soldering and underfill in high-density packaging. This model not only greatly simplifies the computational complexity of flip-chip soldering and filler but also ensures extremely high simulation accuracy.

[0037] In the method for constructing an equivalent model of internal flip-chip bonding and filler structure of high-density packaging according to the present invention, in step S1, the internal flip-chip bonding spacing of the electronic packaging device is kept consistent.

[0038] In the method for constructing an equivalent model of flip-chip bonding and filler structure inside a high-density package according to the present invention, in step S1, the device structural parameters include the length, width and height of the structure, and the material parameters include density, elastic modulus and Poisson's ratio.

[0039] In the method for constructing an equivalent model of flip-chip bonding and filler structure inside a high-density package according to the present invention, in step S2, the electronic packaging device is modeled using SolidWorks software. The selected parameters of the model are heat sink, thermal interface material (TIM), chip, flip-chip bonding, filler and ceramic substrate.

[0040] The method for constructing an equivalent model of flip-chip bonding and filler structure inside a high-density package according to the present invention further includes:

[0041] Multiple high-density packaging models were established, gradually transitioning to retaining the number of outer flip-chip solder rings.

[0042] In the method for constructing an equivalent model of the flip-chip bonding and filler structure inside the high-density package according to the present invention, in step S3, the equivalent parameters of the simplified part of the high-density package are obtained by simulating tensile and shear experiments using finite element Abaqus simulation software.

[0043] In the method for constructing an equivalent model of the internal flip-chip solder and filler structure of a high-density package according to the present invention, in step S4, the same sinusoidal impact load and constraints are applied to the established pre-simplified model using Ansys Workbench, and the stress simulation results of the flip-chip solder and filler are extracted. If the stress value of one of the pre-simplified models differs from that of the previous model by no more than 1%, the final simplified model of the high-density package is determined. The equivalent parameters of the simplified part are calculated using Abaqus and Ansys Workbench simulation software.

[0044] For details, please refer to Figures 1 to 8 This invention provides a specific embodiment based on a high-density packaging finite element model:

[0045] like Figure 2 As shown, Solidworks is used to model the high-density package. Due to the complexity of the internal flip-chip bonding, while directly creating a complete model could greatly improve the accuracy of the simulation calculation, the mesh generation would be complex. Therefore, it is necessary to simplify the modeling of the flip-chip bonding part. The main structural components of the complete model are: heat sink, TIM, chip, flip-chip bonding, underfill, and ceramic substrate.

[0046] Table 1 Geometric parameters of the complete model of high-density packaging structure

[0047]

[0048] like Figure 3 As shown, a pre-simplified model of the high-density package was built using Solidworks, including a fully simplified model of flip-chip bonding and underfill, a simplified model retaining one outer ring of flip-chip bonding, and a simplified model retaining two outer rings of flip-chip bonding, with the rest remaining unchanged. The four models were imported into Ansys Workbench, and the material parameters were entered (as shown in Table 2). The substrate was a ceramic substrate, the chip was a typical silicon material, and the solder balls were Pb90Sn10.

[0049] Table 2 Material Parameters

[0050]

[0051]

[0052] Since the simplified part requires recalculation of material parameters, the finite element simulation method is used. A representative volume element for the solder ball and underfill is established. The volume element has symmetry, such as... Figure 4As shown. The homogenized material properties are transversely isotropic. Finite element simulation tensile and shear tests were performed on the volume element using Abaqus software. Tensile loads were applied in the X and Y directions of the volume element, and tangential loads were applied in the XY and XZ planes to obtain some equivalent material parameters Ey, Ex, Ez, and ν of the solder ball and underfill volume element. xz ,ν yx ,ν yz , Gxz, Gxy, Gzy, where Ex = Ez, ν yx =ν yz , Gxy = Gzy.

[0053] In this model, when the temperature T is less than 139℃, the coefficients of thermal expansion of the solder ball and the underfill are equal (α). x =α y =α z = 2.8 × 10⁻⁵ / ℃. When the temperature T is greater than 139℃, the coefficients of thermal expansion of the solder ball and the underfill are different. A temperature load needs to be applied to the volume element to obtain the elongation of the volume element in each direction. The calculated coefficient of thermal expansion is α. x =α z =6.03×10 -5 / ℃ and α y =8.52×10 -5 / ℃.

[0054] The solder ball layer exhibits transverse anisotropy. The equivalent heat transfer coefficient of the solder ball layer can be solved using methods such as [example code missing in original text]. Figure 5 The complete solder ball layer model is shown. A uniform heat flow q is applied to the A and B surfaces of the solder ball layer, while the corresponding bottom surfaces of the A and B surfaces are kept at a constant temperature (20℃), and the remaining boundaries are adiabatic. The temperature difference is obtained through simulation, and its equivalent heat transfer coefficient can be derived as Equation (1).

[0055]

[0056] The equivalent parameter for specific heat capacity can be obtained by averaging the volume of solder balls and underfill, as shown in equation (2).

[0057]

[0058] The obtained equivalent material parameters are shown in Table 3.

[0059] Table 3 Equivalent Material Parameters

[0060]

[0061] like Figure 6 and Figure 7As shown, the same load constraints were applied to both the pre-simplified model and the complete model. The calculations were performed using a quarter-model, and the stress results at the inverted weld and bottom filler locations were extracted and compared. The comparison results are shown below. Figure 8 As shown.

[0062] The comparison revealed that the error between the fully simplified model and the complete model was 2%. As the number of inverted welding rings increased, the error gradually decreased to 0.32%. Therefore, the two-ring inverted welding simplified model can be selected as the final finite element calculation model.

[0063] Based on the disclosure and teachings of the foregoing specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments described above, and any obvious improvements, substitutions, or modifications made by those skilled in the art based on the present invention are within the scope of protection of the present invention. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on the present invention.

Claims

1. A method for constructing an equivalent model of the internal flip-chip soldering and filler structure of a high-density package, characterized in that, include: Step S1: Select electronic packaging devices and obtain device structure parameters and material parameters; Step S2: Establish a pre-simplified finite element model of the electronic packaging device; Step S3: Obtain the equivalent parameters of the simplified part of the model; Step S4: Determine the final simplified finite element model of the electronic device; In step S1, the flip-chip bonding spacing inside the electronic packaging device is kept consistent. In step S2, the electronic packaging device is modeled using a SolidWorks model, and the selected parameters for the model are heat sink, thermal interface material, chip, flip chip, filler and ceramic substrate. Use Solidworks to build pre-simplified models of high-density packages, including fully simplified models of flip-chip soldering and underfill, simplified models with one outer ring of flip-chip soldering, and simplified models with two outer rings of flip-chip soldering, with the rest remaining unchanged; In step S3, tensile and shear experiments are simulated using the finite element method (Abaqus) to obtain the equivalent parameters of the simplified high-density packaging. Tensile loads are applied in the X and Y directions of the volume element, and tangential loads are applied in the XY and XZ planes to obtain the partial equivalent material parameters Ey, Ex, Ez, and ν of the solder ball and underfill volume element. xz ,ν yx ,ν yz , Gxz, Gxy, Gzy, where Ex = Ez, ν yx =ν yz G xy = Gzy; To solve the equivalent heat transfer coefficient of the solder ball layer, a uniform heat flow q is applied to the A and B surfaces of the solder ball layer, while the corresponding bottom surfaces of the A and B surfaces are kept at a constant temperature (20℃), and the other boundaries are adiabatic; the temperature difference is obtained through simulation, and its equivalent heat transfer coefficient can be derived as Equation (1). The equivalent parameter for specific heat capacity can be obtained by the volume average of solder balls and underfill, as shown in equation (2). In step S4, AnsysWorkbench is used to apply the same sinusoidal impact load and constraints to the established pre-simplified model, and the stress simulation results of flip-chip soldering and filler are extracted. If the stress value of one of the pre-simplified models is no more than 1% different from the previous model, the final simplified model of high-density packaging is determined. Also includes: Multiple high-density packaging models were established, gradually transitioning to retaining the number of outer flip-chip solder rings.

2. The method for constructing an equivalent model of the internal flip-chip soldering and filler structure of a high-density package as described in claim 1, characterized in that: In step S1, the device structural parameters include the length, width, and height of the structure, and the material parameters include density, elastic modulus, Poisson's ratio, coefficient of thermal expansion, heat transfer coefficient, and specific heat capacity.

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