Flip chip height measurement method and system

Abstract

The invention discloses a flip chip height measuring method and system. The flip-chip height measuring method comprises the following steps: providing a flip-chip structure, wherein the flip-chip structure comprises a substrate, a chip and a plurality of solder balls arranged between the substrate and the chip; the method comprises the following steps: acquiring and measuring a flip-chip structure image, shooting the flip-chip structure to obtain a side image of the flip-chip structure, and measuring a chip side image vertical distance of a chip or an image vertical spacing distance between a substrate and the chip based on the side image of the flip-chip structure; calculating a vertical spacing distance in the flip-chip structure, and calculating a vertical spacing distance between the substrate and the chip according to the vertical distance of the side image of the chip or the vertical spacing distance of the image; and calculating a total space volume, and calculating the total space volume between the substrate and the chip according to the vertical spacing distance.

Description

Technical Field

[0001] This invention relates to a measurement method and system, and more particularly to a method and system for measuring flip-chip height. Background Technology

[0002] In the flip chip process, a chip is bonded to a substrate using multiple solder balls, with a vertical gap between the substrate and the chip. Additionally, an underfill is placed between the chip and the substrate to increase the adhesion between them and to act as a buffer against thermal expansion.

[0003] When excessive underfill is applied, it may overflow or even cover the top surface of the chip. Insufficient underfill, on the other hand, fails to improve the adhesion between the chip and the substrate. Therefore, to ensure an appropriate amount of underfill, the distance between the chip and the substrate needs to be determined to accurately calculate the total space between them, and thus the required amount of underfill.

[0004] However, as chip structures become increasingly sophisticated, even micron-level errors can significantly impact the amount of adhesive applied to the bottom.

[0005] Therefore, improving the accuracy of measuring the total volume of space between the chip and the substrate by refining the measurement process, thereby overcoming the defects caused by insufficient or excessive bottom filling, has become one of the important issues to be addressed in this technical field. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method and system for measuring flip-chip height, which addresses the shortcomings of the prior art.

[0007] To address the aforementioned technical problems, one technical solution adopted by this invention is to provide a method for measuring flip-chip height, comprising the following steps: providing a flip-chip structure, the flip-chip structure including a substrate, a chip, and a plurality of solder balls disposed between the substrate and the chip; acquiring and measuring an image of the flip-chip structure by photographing the flip-chip structure to obtain a side image of the flip-chip structure, and measuring a vertical distance between the chip side image and the chip, or a vertical distance between the substrate and the chip, based on the side image of the flip-chip structure; calculating a vertical distance between the substrate and the chip based on the vertical distance between the chip side image and the vertical distance between the images; and calculating a total spatial volume based on the vertical distance between the substrate and the chip.

[0008] To address the aforementioned technical problems, another technical solution adopted by the present invention is to provide a flip-chip height measurement system, comprising: an image acquisition device, a measuring device, and a calibration device. The image acquisition device acquires a side image of a flip-chip structure by taking a side view photograph. The flip-chip structure includes a substrate, a chip, and a plurality of solder balls disposed between the substrate and the chip. Based on the side image of the flip-chip structure, the measuring device acquires a vertical distance from the chip's side image or a vertical distance between the substrate and the chip. The calibration device calculates a vertical distance between the substrate and the chip based on the vertical distance from the chip's side image or the vertical distance between the images, and calculates a total spatial volume between the substrate and the chip based on the vertical distance between the images.

[0009] The beneficial effects of this invention are that the flip-chip height measurement method employs side-view imaging, capturing and obtaining image distances related to the flip-chip structure through a side-view imaging unit. Trigonometric function calculations are used to compensate for errors caused by the shooting angle, resulting in a more accurate vertical spacing distance between the chip and the substrate, thus improving the accuracy of the total spatial volume measurement between the substrate and the chip. Therefore, it can further improve the accuracy of estimated filler amount and increase product yield.

[0010] To further understand the features and technical content of the present invention, please refer to the following detailed description and drawings of the present invention. However, the drawings provided are for reference and illustration only and are not intended to limit the present invention. Attached Figure Description

[0011] Figure 1 This is a flowchart of the flip-chip height measurement method of the present invention.

[0012] Figure 2 This is a side view of the flip-chip structure of the present invention.

[0013] Figure 3 This is a block diagram of the flip-chip height measurement system of the present invention.

[0014] Figure 4 This is a side view schematic diagram of the first embodiment of the flip-chip height measurement system of the present invention.

[0015] Figure 5 for Figure 4 A partially enlarged schematic diagram.

[0016] Figure 6 This is a side view schematic diagram of a second embodiment of the flip-chip height measurement method of the present invention.

[0017] Figure 7 for Figure 6 A partially enlarged schematic diagram.

[0018] Reference numerals: 1: Substrate; 10: Top surface; 2: Chip; 20: Bottom surface; 21: Top surface; 22: Side surface; 3: Solder ball; 4: Flip-chip height measurement system; 5: Image acquisition device; 51: First ranging unit; 51': Second ranging unit; 52: Side-viewing unit; 53: Positioning unit; 6: Measuring device; 7: Calibration device; F: Flip-chip structure; A1: Vertical distance of chip side image; A2: Vertical interval distance of image; B: Bottom edge; D1: First measurement distance; D2: Second measurement distance; D3: Vertical distance of side; ρD: Top surface spacing; H: Vertical interval distance; θ: Shooting angle; S1-S4: Steps. Detailed Implementation

[0019] The following specific embodiments illustrate the implementation of the "Flip Chip Height Measurement Method and System" disclosed in this invention. Those skilled in the art can understand the advantages and effects of this invention from the content disclosed in this specification. This invention can be implemented or applied through other different specific embodiments, and various details in this specification can also be modified and changed based on different viewpoints and applications without departing from the concept of this invention. Furthermore, the accompanying drawings of this invention are for simple illustrative purposes only and are not depictions of actual dimensions, as stated in advance. The following embodiments will further describe the relevant technical content of this invention in detail, but the disclosed content is not intended to limit the scope of protection of this invention. In addition, the term "or" used herein should be interpreted to include, depending on the actual situation, any combination of any one or more of the associated listed items.

[0020] Please see Figure 1 This is a flowchart illustrating the steps of the flip-chip height measurement method of the present invention. Figure 1 As shown, the first embodiment of the present invention provides a method for measuring flip-chip height, which includes the following steps: providing a flip-chip structure (step S1), acquiring and measuring an image of the flip-chip structure (step S2), calculating a vertical spacing distance in the flip-chip structure (step S3), and calculating a total spatial volume (step S4).

[0021] Please see Figure 2 This is a side view schematic diagram of the flip-chip structure of the present invention. Figure 2 As shown, the flip-chip structure F in step S1 includes: a substrate 1, a chip 2, and a plurality of solder balls 3. The substrate 1 has a top surface 10, and the chip 2 has a bottom surface 20, a top surface 21, and at least one side surface 22. The solder balls 3 are disposed between the chip 2 and the substrate 1, such that the substrate 1 and the chip 2 are separated by a distance. In other words, the top surface 10 of the substrate 1 and the bottom surface 20 of the chip 2 are separated by a vertical spacing distance H.

[0022] In step S2, top-view and side-view images of the flip-chip structure F are first taken, and then image measurements are performed based on the obtained top-view and side-view images. The side-view image is obtained by taking a picture of the flip-chip structure F at a certain shooting angle. In this invention, the shooting angle is 0 degrees to less than 90 degrees. That is, a side-view image is obtained by taking a side-view picture.

[0023] In step S3, since the image distance obtained by shooting the chip structure F from the side will have parallax compared to the actual distance, image correction is performed to compensate for the parallax. In the image correction step, the image distance is corrected according to the shooting angle to obtain the vertical distance H between the top surface 10 of the substrate 1 and the bottom surface 20 of the chip 2 in the flip-chip structure F.

[0024] In step S4, after obtaining the vertical spacing distance H, the product of the vertical spacing distance H and the bottom area of ​​chip 2 is taken to obtain the total space volume V between substrate 1 and chip 2.

[0025] Furthermore, the flip-chip height measurement method of the present invention can also be performed by an external filler device in the following steps: calculating the estimated filler amount for bottom filling; in this step, the estimated filler amount for bottom filling can be calculated based on the total space volume between the substrate and the chip and the total volume of the multiple solder balls 3. For example, the total volume of the multiple solder balls 3 is a known default value before flip-chip processing. After subtracting the total volume of the multiple solder balls 3 from the total space volume V, the estimated filler amount can be obtained. This allows for individual control of the bottom filler amount for each flip-chip structure F, thereby improving the structural strength of the flip-chip structure F and reducing the deformation caused by the difference in the coefficient of thermal expansion of the flip-chip structure F. Due to the influence of process operation, the estimated filler amount can also be adjusted by other correction models, and the present invention is not limited thereto.

[0026] Next, please refer to Figure 3 The diagram shown is a block illustration of the flip-chip height measurement system of the present invention. Figure 2 and Figure 3As shown, the flip-chip height measurement system 4 includes an image acquisition device 5, a measuring device 6, and a calibration device 7. The image acquisition device 5 takes a side view image of the flip-chip structure F at a shooting angle. The measuring device 6 is connected to the image acquisition device 5 and acquires the side view image of the flip-chip structure F from the image acquisition device 5. Finally, it performs a measurement operation based on the side view image of the flip-chip structure F to obtain the image distance of the flip-chip structure F on the side view image. The calibration device 7 is connected to the measuring device 6 and acquires the image distance of the flip-chip structure F on the side view image from the measuring device 6. Finally, it corrects the image distance according to the shooting angle to obtain the vertical distance H between the top surface 10 of the substrate 1 and the bottom surface 20 of the chip 2 in the flip-chip structure F, and calculates the total space volume V between the substrate 1 and the chip 2. The calibration device 7 can then transmit the total space volume V to an external filler device (not shown). The external filler device then obtains the estimated filler amount for the bottom filler based on the total space volume V and the total volume of multiple solder balls 3. It is worth mentioning that the data on the total volume of multiple solder balls 3 can be pre-stored in the calibration device 7 or the external filling device.

[0027] Please see Figure 4 and Figure 5 , Figure 4 This is a side view schematic diagram of the first embodiment of the flip-chip height measurement system of the present invention. Figure 5 for Figure 4 A partially enlarged schematic diagram. In the first embodiment, the image acquisition device 5 includes a first ranging unit 51, a second ranging unit 51', and a side-facing imaging unit 52. The first ranging unit 51 is used to capture images of the top surface 10 of the substrate 1, the second ranging unit 51' is used to capture images of the top surface 21 of the chip 2, and the side-facing imaging unit 52 is used to capture side images of the flip-chip structure F.

[0028] In the first embodiment, the measuring device 6 obtains a top surface distance ρD (i.e., the total thickness of the chip 2 and the plurality of solder balls 3) between the top surface 21 of the chip 2 and the top surface 10 of the substrate 1 from the images captured by the first ranging unit 51 and the second ranging unit 51'. Specifically, the measuring device 6 obtains a first measuring distance D1 and a second measuring distance D2 from the images captured by the first ranging unit 51 and the second ranging unit 51', respectively. The first measuring distance D1 is the vertical measuring distance from the first ranging unit 51 to the top surface 10 of the substrate 1, and the second measuring distance D2 is the vertical measuring distance from the second ranging unit 51' to the top surface 21 of the chip 2. The first ranging unit 51 and the second ranging unit 51' are set at the same height, so the difference between the first measuring distance D1 and the second measuring distance D2 is the top surface distance ρD between the top surface 21 of the chip 2 and the top surface 10 of the substrate 1 (i.e., ρD = D1 - D2).

[0029] In the first embodiment, although two ranging units, namely the first ranging unit 51 and the second ranging unit 51', are illustrated, in actual operation, other embodiments may selectively use two ranging units or use the same ranging unit for measurement, and the present invention is not limited thereto. In the first embodiment, the first ranging unit 51 and the second ranging unit 51' are respectively implemented as stereo cameras, but the present invention is not limited thereto. In other embodiments, the device for performing distance measurement may be used directly, without needing to first acquire an image and then measure the distance on the image.

[0030] In the first embodiment, the side-viewing unit 52 captures the side surface 22 of the flip-chip structure F at a shooting angle θ to obtain a vertical distance A1 of the chip side image on the image. Since the side-viewing unit 52 uses side-viewing, the vertical distance A1 of the chip side image is not equivalent to the actual vertical distance D3 of the chip 2 (also known as the thickness of the chip 2). Therefore, the correction device 7 corrects the vertical distance A1 of the chip side image according to the shooting angle θ to obtain the vertical distance D3 of the side image.

[0031] like Figure 5 As shown, the side-facing shooting unit 52 is within the shooting field of view ( Figure 5 (Represented by dashed lines) In the image, the two imaginary lines for image capture are formed by the intersection of the bottom surface 20 and the top surface 21 of chip 2 with one of its side edges, extending towards the side-facing imaging unit 52 at an angle θ. Figure 5 (Represented by the imaginary lines in the image), the vertical distance A1 of the chip side image is the vertical distance between the two imaginary lines. In the first embodiment, the vertical distance A1 of the chip side image can be corrected using the geometric concepts of alternate interior angle and supplementary angle to obtain the side vertical distance D3. Specifically, the side vertical distance D3 (i.e., the vertical distance A1 of the chip side image is calculated with respect to the shooting angle θ using the inverse cosine) can be obtained. ).

[0032] Please return Figure 4 As shown, after obtaining the side vertical distance D3, subtracting the side vertical distance D3 from the top surface spacing ρD yields the vertical interval distance H (i.e., ).

[0033] After obtaining the vertical spacing distance H, the total space volume V between the substrate 1 and the chip 2 can be accurately calculated. Then, the estimated amount of bottom filler is calculated based on the total volume of multiple solder balls 3 by the external filler device. Finally, an appropriate amount of bottom filler is filled between the chip 2 and the substrate 1.

[0034] Please see Figure 6 and Figure 7 As shown, Figure 6 This is a second embodiment of the flip-chip height measurement system of the present invention. Figure 7 for Figure 6 Please refer to the enlarged diagram below. Figures 1 to 5 In the second embodiment, the flip-chip height measurement system is largely the same as in the first embodiment, except that the image acquisition device 5 further includes a positioning unit 53. The positioning unit 53 is configured to define a reference point R projected onto the substrate 1 along the side 22 of the chip 2. The side-viewing unit 52 is configured to capture images at a shooting angle θ to obtain an image vertical spacing distance A2 of the reference point R relative to a bottom edge B of the chip 2. Since the side-viewing unit 52 uses side-viewing, the obtained image vertical spacing distance A2 is not equivalent to the actual vertical spacing distance H. The correction device 7 then corrects the image vertical spacing distance A2 according to the shooting angle θ to obtain the vertical spacing distance H.

[0035] In the second embodiment, a positioning unit 53 (e.g., a directional light source) is used to vertically generate a straight beam above the flip-chip structure F. The straight beam is projected along the side 22 of the chip 2 onto the top surface 10 of the substrate 1 and forms a reference point R.

[0036] When the positioning unit 53 is a directional light source, the positioning unit 53 can be a laser light emitter or an LED emitter, but the present invention is not limited thereto. Any device that can project along the side 22 of the chip 2 onto the top surface 10 of the substrate 1 to form a reference point R can be used as the positioning unit 53.

[0037] exist Figure 6 and Figure 7 In the image, due to the viewing angle, the bottom edge B is only shown as a point, actually extending along the normal vector of the paper. In the field of view of the side-facing imaging unit 52, the bottom edge B of chip 2 is located at the junction of the bottom surface 20 and the side surface 22 (the boundary between the bottom surface 20 and the side surface 22), so the bottom edge B of chip 2 is clearly visible. The reference point R is formed by the projection of a directional light source, so the position of the reference point R is also clearly visible. Furthermore, the reference point R is formed by the vertical projection of the directional light source along the side surface 22 of chip 2, thus ensuring that the reference point R and the side surface 22 of chip 2 are coplanar. Therefore, the vertical distance A2 of the image can be obtained by measuring the vertical distance between the bottom edge B and the reference point R in the side image of chip 2.

[0038] like Figure 7 As shown, the side-facing shooting unit 52 is within the shooting field of view ( Figure 7 In the image (represented by dashed lines), the reference point R and the bottom edge B of chip 2 are perpendicular to the position of the reference point B, and extend towards the side-facing imaging unit 52 at the shooting angle θ to form a two-image imaginary line (…). Figure 7(Represented by a line in the image), the vertical distance A2 is the vertical distance between the two imaginary lines used for image capture. In the second embodiment, the vertical distance A2 can be further corrected using the geometric concepts of interior angles and complementary angles to obtain the vertical distance H. Specifically, the vertical distance H (i.e., H0) can be obtained by calculating the inverse cosine of the vertical distance A2 with respect to the shooting angle θ. ).

[0039] After obtaining the vertical spacing distance H, which is equivalent to obtaining the height of the solder balls 3, the calibration device 7 can accurately calculate the total space volume V between the substrate 1 and the chip 2. Based on the total space volume V and the total volume of multiple solder balls 3, the external filling device can calculate the estimated amount of bottom filling adhesive. Finally, an appropriate amount of bottom filling adhesive is filled between the chip 2 and the substrate 1.

[0040] However, the examples given above are merely one possible embodiment and are not intended to limit the invention.

[0041] Beneficial effects of the embodiments

[0042] The beneficial effects of this invention are that the flip-chip height measurement method employs side-view imaging. An image distance involving the flip-chip structure is captured by a side-view imaging unit, and errors caused by the shooting angle are compensated for through trigonometric function calculations. This results in a more accurate vertical spacing distance between the chip and the substrate, improving the accuracy of the total spatial volume measurement between the chip and the substrate. Therefore, it can further improve the accuracy of the estimated filler amount and increase the product yield.

[0043] The content disclosed above is only a preferred and feasible embodiment of the present invention, and is not intended to limit the scope of protection of the claims of the present invention. Therefore, all equivalent technical changes made based on the content of the present invention specification and drawings are included within the scope of protection of the claims of the present invention.

Claims

1. A method for measuring flip-chip height, characterized in that, The method for measuring flip-chip height includes the following steps: A flip-chip structure is provided, the flip-chip structure including a substrate, a chip, and a plurality of solder balls disposed between the substrate and the chip; The flip-chip structure image is captured and measured by taking a picture of the flip-chip structure to obtain a side image of the flip-chip structure, and the vertical distance of a chip side image or the vertical distance of an image between the substrate and the chip is measured based on the side image of the flip-chip structure. Calculate a vertical spacing distance in the flip-chip structure, and calculate the vertical spacing distance between the substrate and the chip based on the vertical distance of the chip side image or the vertical spacing distance of the image; and A total space volume calculation is performed, and the total space volume between the substrate and the chip is calculated based on the vertical spacing distance.

2. The method for measuring flip-chip height according to claim 1, characterized in that, In the step of cropping and measuring the flip-chip structure image, a side view image of the flip-chip structure is obtained by taking a side view image at a shooting angle. In the step of calculating the vertical spacing distance in the flip-chip structure, the vertical distance of the chip side image or the vertical spacing distance of the image is corrected according to the shooting angle to obtain the vertical spacing distance.

3. The method for measuring flip-chip height according to claim 2, characterized in that, The vertical distance of the chip's side image is calculated by applying an inverse cosine to the shooting angle to obtain a side vertical distance, or the vertical interval distance of the image is calculated by applying an inverse cosine to the shooting angle to obtain the vertical interval distance.

4. The method for measuring flip-chip height according to claim 3, characterized in that, The step of cropping and measuring the flip-chip structure image also includes obtaining a top surface distance between a top surface of the chip and a top surface of the substrate; wherein, in the step of calculating the vertical spacing distance in the flip-chip structure, the vertical spacing distance is calculated based on the difference between the side vertical distance and the top surface distance.

5. The method for measuring flip-chip height according to claim 1, characterized in that, In the step of capturing and measuring the flip-chip structure image, a reference point is defined by projecting along one side of the chip onto the substrate, and a side view is taken at a shooting angle to obtain the vertical distance of the reference point relative to one bottom edge of the chip. The bottom edge of the chip is the junction between the bottom surface and the side surface of the chip.

6. The method for measuring flip-chip height according to claim 5, characterized in that, The method for measuring flip-chip height also includes the following steps: The estimated amount of adhesive to be filled at the bottom is calculated based on the total space volume and the total volume of the multiple solder balls. Specifically, the product of the vertical spacing distance and the bottom area of ​​the chip is taken to obtain the total space volume between the substrate and the chip. Then, the difference between the total space volume and the total volume of the multiple solder balls is taken to obtain the estimated amount of adhesive filling for the bottom.

7. A flip-chip height measurement system, characterized in that, The flip-chip height measurement system includes: An image acquisition device acquires a side image of a flip-chip structure by taking a side-view image. The flip-chip structure includes a substrate, a chip, and a plurality of solder balls disposed between the substrate and the chip. A measuring device, based on a side image of the flip-chip structure, obtains a vertical distance from the chip's side image, or a vertical distance between the substrate and the chip; and A calibration device calculates a vertical distance between the substrate and the chip based on the vertical distance of the chip side image or the vertical spacing distance of the image, and calculates a total space volume based on the vertical spacing distance.

8. The flip-chip height measurement system according to claim 7, characterized in that, The image acquisition device includes a side-facing shooting unit, which takes a side-facing shot at a shooting angle to obtain a side image of the flip-chip structure of the chip. The correction device corrects the vertical distance of the chip side image or the vertical interval distance of the image according to the shooting angle to obtain the vertical interval distance.

9. The flip-chip height measurement system according to claim 8, characterized in that, The correction device calculates the vertical distance of the chip side image with respect to the shooting angle using the inverse cosine of the distance, to obtain a side vertical distance, or calculates the vertical interval distance of the image with respect to the shooting angle using the inverse cosine of the distance, to obtain the vertical interval distance.

10. The flip-chip height measurement system according to claim 9, characterized in that, The image acquisition device further includes at least one ranging unit, which is used to obtain a top surface distance between a top surface of the chip and a top surface of the substrate. The correction device calculates the vertical interval distance based on the difference between the side vertical distance and the top surface distance.

11. The flip-chip height measurement system according to claim 7, characterized in that, The image acquisition device includes: A positioning unit, configured to define a reference point projected onto the substrate along one side of the chip; and A side-facing imaging unit is configured to take a side-facing image at a shooting angle to obtain the vertical distance of the image relative to a bottom edge of the chip from the reference point; The bottom edge of the chip is the junction between the bottom surface and the side surface of the chip.

12. The flip-chip height measurement system according to claim 11, characterized in that, The correction device provides the total space volume to an external filling device, which is configured to calculate the estimated amount of bottom filling adhesive based on the total space volume and the total volume of the plurality of solder balls. The external filler device takes the product of the vertical spacing distance and the bottom area of ​​the chip to obtain the total space volume between the substrate and the chip, and then takes the difference between the total space volume and the total volume of the multiple solder balls to obtain the estimated filler amount for bottom filling.

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