A chip bridge structure prediction method, device, medium and equipment

Abstract

The application discloses a chip bridge structure prediction method and device, a medium and equipment, and relates to the technical field of semiconductor packaging "finite element numerical simulation". The welding point density and the warping degree of the chip are analyzed to analyze the interval between adjacent welding points when the bridge structure is formed, and a function relationship expression is constructed. The function relationship expression includes the relationship between the chip warping degree, the welding point density and the shortest interval of the adjacent welding points. The welding point density and the warping degree of the chip to be predicted are obtained. The welding point density and the warping degree of the chip to be predicted are substituted into the function relationship expression to determine the shortest interval of the adjacent welding points in the chip to be predicted. If the shortest interval is smaller than a preset interval threshold, it is determined that the chip to be predicted has a bridge structure. The method can accurately predict the bridge structure of the chip.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor package "finite element numerical simulation", and in particular relates to a chip bridge structure prediction method, device, medium and equipment. BACKGROUND

[0002] At present, 2.5D packaging as an advanced packaging technology has been widely used in the electronic industry in recent years. It combines the advantages of two-dimensional planar packaging and three-dimensional stacking technology, and can realize higher integration and better performance.

[0003] In 2.5D packaging, the formation of the bridge (Ball Bridge) structure is a key problem, which can cause the conductivity of the entire package to decrease or even cause a short circuit, which has an important influence on the performance of the entire package. Therefore, accurately predicting whether the chip has a bridge structure can help engineers identify potential risks in the design stage and take measures in advance to avoid the occurrence of bridge problems.

[0004] However, there is a lack of a method for predicting the bridge structure of a chip in the prior art. SUMMARY

[0005] Therefore, it is necessary to provide a chip bridge structure prediction method, device, medium and equipment, which can accurately predict the bridge structure of a chip.

[0006] The present application adopts the following technical solutions:

[0007] The present application provides a chip bridge structure prediction method, comprising:

[0008] The solder point density and warpage degree of the chip are analyzed to analyze the spacing between adjacent solder points when the bridge structure is formed, and a function relationship expression is constructed. The function relationship expression includes the relationship between the chip warpage degree, the solder point density and the shortest distance between adjacent solder points.

[0009] Obtain the solder point density and warpage degree of the chip to be predicted;

[0010] Substitute the solder point density and warpage degree of the chip to be predicted into the function relationship expression to determine the shortest distance between adjacent solder points in the chip to be predicted.

[0011] If the shortest distance is less than the preset distance threshold, it is determined that the chip to be predicted has a bridge structure.

[0012] Optionally, the function relationship expression is:

[0013]

[0014] Wherein, z is the shortest distance, z0, B, C, D, E, F are constant terms, x is the warping degree of the chip, and y is the solder density.

[0015] Optionally, the solder density and the warping degree of the chip are analyzed to analyze the distance between adjacent solder points when forming a bridging structure, and a function relationship expression is constructed, including:

[0016] An initial chip model with different solder densities is established in a finite element numerical simulation software.

[0017] For any initial chip model, stress load is applied to the initial chip model, the warping degree of the initial chip model under different stress loads is determined, and the shortest distance between adjacent solder points of the initial chip model under different stress loads is calculated.

[0018] According to the shortest distance corresponding to the initial chip model with different warping degrees under different solder densities, the function relationship expression is determined.

[0019] Optionally, calculating the shortest distance between adjacent solder points of the initial chip model under different stress loads includes:

[0020] For any stress load, the distance between all adjacent solder points in the initial chip model is obtained.

[0021] The shortest distance is determined from all distances.

[0022] Optionally, calculating the shortest distance between adjacent solder points of the initial chip model under different stress loads includes:

[0023] For any stress load, the distance between the centermost solder point of the chip and the adjacent solder point in the initial chip model under the stress load is obtained.

[0024] The distance between the centermost solder point of the chip and the adjacent solder point is determined as the shortest distance.

[0025] Optionally, the method further includes:

[0026] After the initial chip model is established, the center points of any two adjacent solder points in the initial chip model are marked.

[0027] After the stress load is applied to the initial chip model, the coordinates of the centers of any two adjacent solder points are determined by selecting the marked center points with a probe.

[0028] According to the difference between the coordinates of the centers of any two adjacent solder points, the distance between any two adjacent solder points is determined.

[0029] Optionally, the calculation formula of the solder density is:

[0030]

[0031] The application provides a bridge structure prediction device of a chip, comprising:

[0032] A construction module is configured to analyze the interval between adjacent solder joints when a bridge structure is formed according to the solder joint density and the warping degree of the chip, and to construct a function relationship expression; the function relationship expression comprises the relationship between the warping degree of the chip, the solder joint density and the shortest interval of the adjacent solder joints;

[0033] An acquisition module is configured to acquire the solder joint density and the warping degree of a chip to be predicted;

[0034] A calculation module is configured to substitute the solder joint density and the warping degree of the chip to be predicted into the function relationship expression, and to determine the shortest interval of the adjacent solder joints in the chip to be predicted;

[0035] A prediction module is configured to determine that the chip to be predicted has a bridge structure if the shortest interval is smaller than a preset interval threshold.

[0036] The application provides a computer readable storage medium, wherein the storage medium stores a computer program, and the computer program is executed by a processor to realize the bridge structure prediction method of the chip.

[0037] The application provides a computer device, comprising a memory, a processor and a computer program stored in the memory and executable on the processor, and the processor realizes the bridge structure prediction method of the chip when executing the program.

[0038] The above at least one technical scheme adopted by the application can achieve the following beneficial effects:

[0039] In the application, the function relationship expression is constructed by analyzing the influence of the solder joint density and the warping degree of the chip on the formation of the bridge structure; the function relationship expression comprises the relationship between the warping degree of the chip, the solder joint density and the shortest interval of the adjacent solder joints, and therefore, the function relationship expression represents the function relationship between the solder joint density and the warping degree of the chip and the formation of the bridge structure, so that whether the chip to be predicted has a bridge structure can be determined accurately according to the function relationship expression. BRIEF DESCRIPTION OF DRAWINGS

[0040] The accompanying drawings, which are included to provide a further understanding of the application, constitute a part of the application and serve to explain the application together with the specification. The schematic embodiments of the application and their descriptions serve to explain the application and do not constitute an improper limitation on the application. In the drawings:

[0041] Figure 1 The application provides a bridge structure prediction method of a chip, and a flowchart is shown in the figure;

[0042] Figure 2A C4bump geometry diagram provided by the present application;

[0043] Figure 3 A model one geometry diagram provided by the present application;

[0044] Figure 4 A model two geometry diagram provided by the present application;

[0045] Figure 5 A model three geometry diagram provided by the present application;

[0046] Figure 6 A C4bump spacing diagram provided by the present application;

[0047] Figure 7 A C4bump center point marking diagram provided by the present application;

[0048] Figure 8 A diagram of adding a probe after deformation provided by the present application;

[0049] Figure 9 An initial condition setting display diagram provided by the present application;

[0050] Figure 10 A deformation diagram of model one provided by the present application;

[0051] Figure 11 A deformation diagram of model two provided by the present application;

[0052] Figure 12 A deformation diagram of model two provided by the present application;

[0053] Figure 13 A simulation data scatter plot provided by the present application;

[0054] Figure 14 A sample point fitting effect diagram provided by the present application;

[0055] Figure 15 A chip bridge structure prediction device diagram provided by the present application;

[0056] Figure 16 A computer device diagram for implementing a chip bridge structure prediction method provided by the present application. DETAILED DESCRIPTION

[0057] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described below in connection with the embodiments of the present application and the corresponding drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work belong to the scope of protection of the present application.

[0058] In modern electronic devices such as smart phones, tablet computers, servers, etc., any failure or malfunction can cause damage to the device or loss of data, causing inconvenience and loss to the user. Therefore, in 2.5D packaging, the formation of BallBridge must be avoided to ensure the long-term stable operation of electronic products.

[0059] In the 2.5D packaging process, the warpage of the chip is a common problem. The warpage of the chip can cause poor connection between the C4 bump (solder joint) and the chip pin, and then cause the formation of Ball Bridge. In addition, the change of C4 bump density on the chip can affect the size of stress on the chip and then form Ball Bridge.

[0060] The present application aims to find a functional relationship between chip warpage and C4 bump density on the formation of Ball Bridge, so that the formation of Ball Bridge can be controlled to avoid circuit failure caused by Ball Bridge problem.

[0061] Based on this, the present application provides a chip bridge structure prediction method, which can accurately predict whether the chip has a bridge structure.

[0062] The technical solutions provided by the embodiments of the present application will be described in detail below in connection with the drawings.

[0063] Figure 1 The chip bridge structure prediction method of the present application is shown in the flowchart, which specifically includes the following steps:

[0064] S101, analyze the distance between adjacent solder joints when the solder joint density and warpage degree of the chip form a bridge structure, and construct a functional relationship expression; the functional relationship expression includes the relationship between the warpage degree of the chip, the solder joint density and the shortest distance between adjacent solder joints.

[0065] The function relationship expression is determined according to the shortest distances corresponding to the initial chip models of different solder point densities and different warping degrees.

[0066] Alternatively, the shortest distance of the adjacent solder points of the initial chip model under different stress loads is calculated by: for any stress load, the distance between all adjacent solder points in the initial chip model is obtained; and the shortest distance is determined from all the distances. Alternatively, since the middle part of the chip warps to the maximum, the distance between the C4 bump at the center of the chip and the adjacent C4 bump is calculated by the probe after deformation, and therefore, the way of calculating the shortest distance of the adjacent solder points of the initial chip model under different stress loads can also be: for any stress load, the distance between the solder point at the center of the chip and the adjacent solder point in the initial chip model under the stress load is obtained; and the distance between the solder point at the center of the chip and the adjacent solder point is determined as the shortest distance.

[0067] After the initial chip model is established, the center points of any two adjacent solder points in the initial chip model are marked; after the stress load is applied to the initial chip model, the coordinates of the centers of any two adjacent solder points are determined by selecting the marked center points by the probe; and the distance between any two adjacent solder points is determined according to the difference between the coordinates of the centers of any two adjacent solder points. It should be noted that the coordinates of the solder points are the coordinates in the x, y and z axes, wherein the y axis represents the height of the solder points, and the x and z axes represent the position distribution of the solder points, and therefore, the distance between adjacent solder points can be the difference between the x axes of the adjacent solder points on the same z axis, or the difference between the z axes of the adjacent solder points on the same x axis. The distance can represent the absolute value of the difference.

[0068] The calculation formula of the solder point density is:

[0069]

[0070] The function relationship expression is determined according to the shortest distances corresponding to the initial chip models of different solder point densities and different warping degrees.

[0071]

[0072] Wherein, z is the shortest distance, z0, B, C, D, E, F are constant terms, x is the warping degree of the chip, and y is the solder density. Different chip types correspond to different values of the constant terms in the function expression.

[0073] S102, obtaining the solder density and warping degree of the chip to be predicted.

[0074] The chip to be predicted can be a chip after packaging on the simulation software, and the solder density and warping degree of the chip to be predicted are directly obtained from the simulation software.

[0075] S103, substituting the solder density and warping degree of the chip to be predicted into the function expression to determine the shortest distance between adjacent solders in the chip to be predicted.

[0076] Substituting the solder density and warping degree of the chip to be predicted into the function expression, the shortest distance between adjacent solders in the chip to be predicted is obtained, wherein the shortest distance is the shortest distance between all solders in the chip to be predicted.

[0077] S104, if the shortest distance is less than a preset distance threshold, it is determined that the chip to be predicted has a bridge structure.

[0078] The preset distance threshold can be a safe distance between solders, and the preset distance threshold can be 0.3 mm.

[0079] If the shortest distance is less than the preset distance threshold, it means that there is a distance between all solders in the chip to be predicted that exceeds the preset distance threshold, and it is determined that the chip to be predicted has a bridge structure. If the shortest distance is greater than or equal to the preset distance threshold, it means that the distance between all solders in the chip to be predicted is not less than the preset distance threshold, and it is determined that the chip to be predicted does not have a bridge structure.

[0080] In an exemplary embodiment, an initial model is established: initial chip models with different C4bump densities are established in the simulation software ANSYS, the geometric model of the C4bump is drum-shaped, the upper and lower planes are circles with a diameter of 0.2 mm, and the maximum diameter of the middle circle is 0.3 mm, as shown in Figure 2 Model one includes a main chip (5 mm x 5 mm x 3 mm) and 225 C4bumps, the distance between two adjacent C4bumps is 0.02 mm, as shown in Figure 3 Model two includes a main chip and 169 C4bumps, the distance between two adjacent C4bumps is 0.05 mm, as shown in Figure 4 Model three includes a main chip and 121 C4bumps, the distance between two adjacent C4bumps is 0.1 mm, as shown in Figure 5 Different models correspond to different C4bump densities.

[0081] Definition of C4bump spacing: The spacing of C4bump is the distance between the centers of two adjacent C4bumps. Take the C4bump spacing diagram of Model One as an example, as shown in Figure 6 .

[0082] Method for calculating the C4bump spacing after model deformation: The distance between the centers of C4bumps can be measured in the sketch for the initial model, and the probe is used in ANSYS to calculate the spacing between C4bumps after deformation. Take Model One as an example, first mark the center points of two adjacent C4bumps, as shown in Figure 7 . After the model is deformed by applying stress, select the probe to select the two centers, and the coordinate values of the two centers can be obtained. The spacing between the two C4bumps after deformation can be obtained by subtracting the x-axis coordinate values, as shown in Figure 8 .

[0083] Definition of C4bump density of the model: The C4bump density is defined as the total area of C4bumps divided by the area of the main chip.

[0084] Definition of Ball Bridge: If the three values obtained by subtracting the coordinate components of the center points of adjacent C4bumps are less than 0.3 mm (the maximum diameter of C4bump) after adding the absolute values, it is in the state of Ball Bridge.

[0085] First, fixed constraints are applied to the main chip to ensure the stability of the simulation results. Then, the working environment of the chip is simulated, and stress load is applied for simulation deformation. The stress load is constantly changed, and the warping degree of the chip under different stress loads is extracted. Since the middle part of the chip warps to the maximum, the C4bump at the center of the deformed chip and its adjacent C4bumps are calculated by the probe, and the data of each group of warping and C4bump spacing are recorded.

[0086] Establishing a functional relationship: The present application predicts the formation of Ball Bridge based on the warping of the chip in 2.5D packaging and the C4bump density, and the functional relationship is: z = f(x, y). Where z is the shortest spacing of C4bumps after model deformation, x is the warping degree of the chip, and y is the C4bump density. Table 1 shows the values of the material parameters of the model.

[0087] Table 1

[0088]

[0089] Simulation results: The simulation deformation environment temperature is set to 60℃, the displacement is the bottom of the chip, the fixed support is the bottom surface of the C4bump at the center of the chip, and the condition setting Figure 9The simulation results of each model are obtained, as shown in Figure 10 - Figure 12 Figure 10 Fig. 1 is a schematic diagram of the deformation of a model one, Figure 11 Fig. 2 is a schematic diagram of the deformation of a model two, Figure 12 Fig. 3 is a schematic diagram of the deformation of a model three.

[0090] Simulation data display: three groups of models are respectively applied with different stresses, and each obtains 8 simulation data, a total of 24 simulation data, as shown in Table 2.

[0091] Table 2

[0092]

[0093]

[0094] Function fitting: the simulation data is imported into origin, and the sample points are fitted, and the results are as shown in Figure 13 and Figure 14 .

[0095] The functional relationship expression of the chip warping and the C4 bump density to the formation of the Ball Bridge is: Wherein the values of each constant term are shown in Table 3.

[0096] Table 3

[0097] Constant term Value Z0 59.4 B -213 C 1463 D 1529 E -0.56 F 0.11

[0098] From Figure 14 , it can be seen that R2=0.9963, which indicates that the difference between the predicted value of the surface fitting model and the simulation value is relatively small, and the model can well predict the rule of the formation of the Ball Bridge.

[0099] In the application of the chip bridge structure prediction method provided by the application, each step shown in Figure 1 may not be executed according to the order, and the execution order of each step can be determined according to the needs, and the application does not limit this.

[0100] The above is the chip bridge structure prediction method provided by one or more embodiments of the application, based on the same idea, the application also provides a corresponding chip bridge structure prediction device, as shown in Figure 15 .

[0101] Figure 15 Fig. 4 is a schematic diagram of a chip bridge structure prediction device provided by the application, the device 1500 comprises:

[0102] ​The construction module 1501 is configured to analyze the interval between adjacent solder joints when a bridge structure is formed according to the solder joint density and the warping degree of a chip, and to construct a function relationship expression; the function relationship expression includes the relationship between the warping degree of the chip, the solder joint density and the shortest interval of adjacent solder joints.

[0103] The acquisition module 1502 is configured to acquire the solder joint density and the warping degree of a chip to be predicted.

[0104] The calculation module 1503 is configured to substitute the solder joint density and the warping degree of the chip to be predicted into the function relationship expression, and to determine the shortest interval of adjacent solder joints in the chip to be predicted.

[0105] The prediction module 1504 is configured to determine that the chip to be predicted has a bridge structure if the shortest interval is less than a preset interval threshold.

[0106] The specific limitation of the chip bridge structure prediction device can refer to the limitation of the chip bridge structure prediction method, which will not be repeated here. The above-mentioned various modules of the chip bridge structure prediction device can be realized by software, hardware and their combination. The above-mentioned various modules can be embedded in or independent of the processor in the computer device in hardware form, or can be stored in the memory in the computer device in software form, so as to call and execute the operation corresponding to the above-mentioned various modules by the processor.

[0107] The present application also provides a computer readable storage medium, which stores a computer program, and the computer program can be used to execute the above-mentioned Figure 1 The chip bridge structure prediction method.

[0108] The present application also provides a chip bridge structure prediction device. Figure 16 The structure diagram of the computer device is shown in FIG. 1. Figure 16 As shown in FIG. 1, at the hardware level, the computer device includes a processor, an internal bus, a network interface, a memory and a non-volatile memory, and of course, other hardware required by the business. The processor reads the corresponding computer program from the non-volatile memory into the memory and then runs to realize the above-mentioned Figure 1 The chip bridge structure prediction method.

[0109] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer readable storage medium, and when executed, can include the processes of the above-mentioned embodiments of the methods. In the embodiments of the present application, any reference to memory, storage, database or other medium can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory, etc. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration but not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc.

[0110] The technical features of the above embodiments can be combined in any way. In order to make the description simple, all possible combinations of the technical features in the above embodiments are not described, but as long as the combination of the technical features does not exist, it should be considered as the scope of the present application.

Claims

1. A method for predicting the bridge structure of a chip, characterized in that: include: Establish initial chip models with different solder joint densities in finite element numerical simulation software; For any initial chip model, applying stress loads to the initial chip model, determining the warping degree of the initial chip model under different stress loads, and calculating the shortest distance between adjacent solder joints of the initial chip model under different stress loads; A functional relationship expression is determined based on the shortest spacing corresponding to the initial chip model with different warpage degrees under different solder joint densities; the functional relationship expression includes the relationship between the chip warpage degree, solder joint density and the shortest spacing between adjacent solder joints; the functional relationship expression is: Among them, z is the shortest spacing, z0, B, C, D, E, and F are constant terms, x is the chip warpage degree, and y is the solder joint density; Obtain the solder joint density and warpage degree of the chip to be predicted; Substituting the solder joint density and warpage degree of the chip to be predicted into the functional relationship expression to determine the shortest distance between adjacent solder joints in the chip to be predicted; If the shortest distance is less than a preset distance threshold, it is determined that a bridge structure exists in the chip to be predicted.

2. The method according to claim 1, characterized in that Calculating the shortest distance between adjacent solder joints of the initial chip model under different stress loads includes: For any stress load, obtaining the spacing between all adjacent solder joints in the initial chip model; The shortest distance is determined from all the distances.

3. The method according to claim 1, characterized in that Calculating the shortest distance between adjacent solder joints of the initial chip model under different stress loads includes: For any stress load, obtaining the distance between the centermost solder joint of the chip and the adjacent solder joints in the initial chip model under the stress load; The distance between the solder joint at the center of the chip and the adjacent solder joints is determined as the shortest distance.

4. The method according to claim 1, wherein The method further comprises: After establishing the initial chip model, marking the center points of any two adjacent solder joints in the initial chip model; After applying stress load to the initial chip model, the coordinates of the centers of any two adjacent solder joints are determined by selecting the center points of the marks through a probe; The distance between the two adjacent welding spots is determined according to the difference between the coordinates of the centers of the two adjacent welding spots.

5. The method according to claim 1, wherein The calculation formula of the solder joint density is:

6. A chip bridge structure prediction device, characterized in that: include: A building module for establishing an initial chip model with different solder joint densities in finite element numerical simulation software; For any initial chip model, a stress load is applied to the initial chip model, the warping degree of the initial chip model under different stress loads is determined, and the shortest spacing between adjacent solder joints of the initial chip model under different stress loads is calculated; a functional relationship expression is determined based on the shortest spacing corresponding to the initial chip model with different warping degrees under different solder joint densities; the functional relationship expression includes the relationship between the chip warping degree, solder joint density, and the shortest spacing between adjacent solder joints; the functional relationship expression is: Among them, z is the shortest spacing, z0, B, C, D, E, and F are constant terms, x is the chip warpage degree, and y is the solder joint density; An acquisition module is used to obtain the solder joint density and warpage degree of the chip to be predicted; a calculation module, configured to substitute the solder joint density and warpage degree of the chip to be predicted into the functional relationship expression to determine the shortest distance between adjacent solder joints in the chip to be predicted; The prediction module is configured to determine that a bridge structure exists in the chip to be predicted if the shortest distance is less than a preset distance threshold.

7. A computer-readable storage medium, characterized in that The storage medium stores a computer program, and when the computer program is executed by a processor, the method according to any one of claims 1 to 5 is implemented.

8. A computer device, characterized in that: The method comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method according to any one of claims 1 to 5 when executing the program.

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