Method for testing chip warpage by using industrial microscope and chip warpage testing tooling

Abstract

The application discloses a kind of method for testing chip warping using industrial microscope and chip warping test tooling, wherein method is set on an object table a chip warping test tooling, chip warping test tooling is provided with four support columns;When testing, FCBGA product is supported by four support columns, so that product is in the state of suspension, then select four corner points on the substrate of product, first, the position of any three corner points in four corner points is leveled by telescopic adjusting support column, so as to adjust the suspension position of product;After leveling, the geometric center of product is set to zero position, then the Z axis value Z1 of the position of any one of any three corner points in four corner points and the Z axis value Z2 of the position of the remaining one of four corner points are measured by industrial microscope, finally, the above-mentioned value Z1 and value Z2 are judged with warping value standard, so as to determine whether the warping value of product is qualified.

Description

Technical Field

[0001] This invention relates to a method and testing fixture for testing chip warpage, and more particularly to a method and chip warpage testing fixture for testing chip warpage using an industrial microscope, belonging to the field of chip warpage testing technology. Background Technology

[0002] After encapsulation, FCBGA products may warp to varying degrees due to the mismatch in thermal expansion coefficients between the encapsulation materials, especially after undergoing temperature fluctuations during the encapsulation process. The magnitude and morphology of FCBGA warpage are closely related to the encapsulation structure, size, and materials. Factors contributing to warpage include material thermal expansion coefficient (CTE) mismatch, stress accumulation exacerbated by multi-step thermal cycling during manufacturing, asymmetrical layout and size effects in structural design, and the dual nature of stress release during curing and post-processing. In short, FCBGA product encapsulation warpage is the result of a combination of material, process, design, and manufacturing defects.

[0003] Excessive warpage in FCBGA product packages can lead to the following problems: 1. Package reliability issues, such as solder joint failure, delamination, and loss of hermeticity; 2. Impact on electrical performance, such as signal transmission problems and changes in circuit performance; 3. Manufacturing process issues, such as increased assembly and testing difficulty and decreased production yield. Therefore, warpage testing is necessary after FCBGA product packaging to ensure that the warpage is controlled within the standard value, thereby ensuring the quality of FCBGA products leaving the factory.

[0004] The shape of FCBGA products after warping is quite complex. There is positive (concave) warping, such as a smiley face; negative (convex) warping, such as a sad face; and there are also more complex shapes that have both concave and convex features, roughly presenting asymmetrical deformations such as "W" or "M". All of the above warping deformations are irregular and symmetrical deformations.

[0005] One existing method for measuring warp is using an industrial coordinate measuring machine (CMM), such as the Olympus STM 7 industrial microscope. Figure 1 and Figure 2As shown, the FCBGA product includes a substrate 1 and an inverted chip (not shown) soldered to one side of the substrate 1. The side of the substrate 1 with the inverted chip soldered on is designated as the bottom surface of the substrate 1, and the opposite side of the substrate 1 without the inverted chip soldered on is designated as the top surface S of the substrate 1. During measurement, the FCBGA product is placed on the stage 2 of an industrial microscope, with the side of the substrate 1 with the inverted chip soldered on facing down and the opposite side of the substrate 1 without the inverted chip soldered on facing up, i.e., the top surface S of the substrate 1 is facing up, so that the objective lens 3 of the industrial microscope faces the top surface S of the substrate 1. After placement, the stage 2 is moved so that the objective lens 3 of the industrial microscope is aligned with the geometric center point P of the substrate 1. Then, focusing is adjusted to make the image of the geometric center point P in the eyepiece clear. At this time, the Z coordinate (i.e., the vertical coordinate) displayed on the screen shows a certain value. When the image of the geometric center point P becomes clear, the focusing adjustment is stopped and a zeroing operation is performed. At this time, the position of the geometric center point P is set as the zero point position. Next, move stage 2 again so that the objective lens 3 of the industrial microscope is aligned with corner point A at one corner of substrate 1. Then, adjust the focus to make the image of corner point A in the lens clear. At this point, stop adjusting the focus. The Z coordinate displayed on the screen will show a certain value, which is the value of corner point A relative to the zero point position on the Z axis. Then, record this value. Next, move stage 2 again so that the objective lens 3 of the industrial microscope is aligned with corner point B at another corner of substrate 1. Perform the same operation as before to obtain the value of corner point B relative to the zero point position on the Z axis. Next, repeat the above operation to obtain the values ​​of corner points C and D relative to the zero point position on the Z axis. Corner points A, B, C, and D are located at the four corners of substrate 1, respectively. After the operation is completed, four values ​​of corner points A, B, C, and D relative to the zero point position on the Z-axis can be obtained. Finally, the average of these four values ​​is calculated to obtain the average value. This average value is then compared with the warp value standard. If the average value is within the warp value standard range, the warp value of the FCBGA product is determined to meet the requirements; otherwise, the warp value of the FCBGA product is determined to be unqualified.

[0006] The problem with the existing technology is that, after testing using the existing methods, the test results sometimes do not match the actual warpage, which affects the accuracy of the test results. This leads to some FCBGA products that do not meet the warpage value standard being mistakenly judged as qualified products, thus reducing the quality of FCBGA products leaving the factory.

[0007] Chinese invention patent application CN106910694A, published on June 30, 2017, discloses a method for automatically detecting the warpage of an integrated circuit device. The method includes the following sequential steps: (1) acquiring a surface feature image Fig0 of the device, and cropping the test area F0 on the surface feature image Fig0 as a standard area image FigF0 for warpage comparison; (2) extracting the surface feature images Fig1, Fig2, ... FigN of the device under test, and identifying the test areas F1, F2, ... Fn one by one; (3) scanning the warpage of the identified test areas and calculating the warpage value γ; (4) comparing the calculated warpage value γ with the set warpage standard value L, and calculating the tolerance; if the tolerance calculated for the device under test is within the range of the set tolerance difference value S, the device under test or integrated circuit product is deemed qualified; otherwise, it is deemed unqualified.

[0008] Chinese invention patent application CN115763288A, published on March 7, 2023, discloses a method for evaluating the degree of warpage of a substrate after a thermal process. The method includes the following steps: S1: Selecting a substrate to be measured; S2: Performing a thermal process on the substrate selected in step S1; S3: The substrate to be measured includes a long side and a short side. A point is selected at the front, middle, and rear positions of the long side edge of the substrate after the thermal process in step S2. Similarly, a point is selected at the top, middle, and bottom of the short side edge of the substrate. The selected points include the highest and lowest points of substrate warpage. The height of each selected point is measured using a tool. The maximum overall warpage of the substrate is calculated by subtracting the lowest point of downward warpage from the maximum upward warpage of the substrate. That is, the maximum warpage of the substrate = the highest positive warpage - the lowest negative warpage.

[0009] The methods described in the aforementioned patent documents are all different from the methods in this application.

[0010] In summary, improving existing warp measurement methods to enhance the accuracy of test results and ensure the quality of FCBGA products leaving the factory is an urgent technical problem that needs to be solved. Summary of the Invention

[0011] The technical problem to be solved by the present invention is to address the deficiencies in the existing technology by providing a method and a chip warpage testing fixture for testing chip warpage using an industrial microscope. This method can improve the accuracy of test results, avoid the phenomenon that some FCBGA products that do not meet the warpage value standard are mistakenly judged as qualified products, and improve the quality of FCBGA products leaving the factory.

[0012] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a method for testing chip warpage using an industrial microscope. A chip warpage testing fixture is set on a stage, and the chip warpage testing fixture is equipped with four support columns that can be extended and retracted vertically. During testing, the FCBGA product is supported by the four support columns, so that the FCBGA product is in a suspended state. Then, four corner points on the substrate of the FCBGA product are selected, and the positions of any three of the four corner points are first leveled by using the extendable and retractable support columns, thereby adjusting the suspended position of the FCBGA product. After leveling, the geometric center of the FCBGA product is set as the zero point position. Then, the Z-axis value Z1 of any one of the three corner points and the Z-axis value Z2 of the remaining corner point are measured by an industrial microscope. Finally, the above values ​​Z1 and Z2 are compared with the warpage value standard to determine whether the warpage value of the FCBGA product is qualified.

[0013] Preferably, the specific steps of the method are as follows:

[0014] 1) During testing, the FCBGA product is placed on four support pillars with the top surface S of the FCBGA product substrate facing upwards. The top surface S is one side of the substrate without the inverted chip soldered. The four support pillars are in contact with the four corners of the bottom surface of the substrate to suspend and support the FCBGA product, so that the objective lens of the industrial microscope faces the top surface S of the substrate.

[0015] 2) The contact points between the four support columns and the bottom surface of the substrate are respectively designated as corner points A, B, C and D on the top surface S of the substrate. Any three of these corner points are selected, and the lengths of the three support columns corresponding to these three points are adjusted by stretching and extending to level the three points so that the horizontal planes at these three points coincide with each other.

[0016] 3) Move the stage so that the objective lens of the industrial microscope is aligned with the geometric center point P of the substrate, and adjust the focus until the image of the geometric center point P in the eyepiece becomes clear; when the image of the geometric center point P becomes clear, stop the focus adjustment and perform a zeroing operation. At this time, the position of the geometric center point P is set as the zero point position.

[0017] 4) Move the stage so that the objective lens of the industrial microscope is aligned with any one of the three corner points that were leveled in step 2), and adjust the focus until the image in the eyepiece becomes clear; once the image in the eyepiece is clear, stop adjusting the focus and record the Z coordinate value Z1 displayed on the screen at this time;

[0018] 5) Move the stage so that the objective lens 3 of the industrial microscope is aligned with the remaining corner point that was not leveled in step 2), and adjust the focus until the image in the eyepiece becomes clear; once the image in the eyepiece becomes clear, stop adjusting the focus and record the Z coordinate value Z2 displayed on the screen at this time;

[0019] 6) Determine whether the values ​​Z1 in step 4) and Z2 in step 5) are both within the warp value standard; if both Z1 and Z2 are within the warp value standard, the warp value of the FCBGA product is deemed to meet the requirements; otherwise, the warp value of the FCBGA product is deemed to be unqualified.

[0020] Preferably, each support column is further provided with an L-shaped connecting rod on its side surface at the top. The L-shaped connecting rod includes a horizontal connecting rod and a vertical connecting rod. One end of the horizontal connecting rod is connected to the side surface of the top of the support column, and the other end of the horizontal connecting rod is connected to one end of the vertical connecting rod. An indicator column is provided above each support column. The side surface of the indicator column is connected to one end of a rotating rod, and the other end of the rotating rod is rotatably connected to the other end of the vertical connecting rod, so that the indicator column is rotatably connected above the support column. A limit block is also provided on the horizontal connecting rod. When the indicator column rotates to contact the limit block, the central axis of the support column and the central axis of the indicator column coincide with axis L.

[0021] In step 2), when setting the corner points, the substrate is first placed on the support pillar, and then the indicator pillar is rotated so that the central axis of the support pillar and the central axis of the indicator pillar coincide with axis L. At this time, the intersection of axis L and the top surface of the substrate is the corner point. By rotating the indicator pillars corresponding to the four support pillars, corner points A, B, C and D are obtained.

[0022] Preferably, in step 2), leveling any three points involves first moving the stage so that the objective lens of the industrial microscope is aligned with the indicator post corresponding to one of the three corner points. After alignment, the indicator post corresponding to one of the corner points is rotated to move the indicator post away so that the indicator post does not block the objective lens, thereby allowing the objective lens to be aligned with one of the corner points on the top surface of the substrate. Then, focusing is adjusted until the image at one of the corner points in the eyepiece becomes clear. At this time, the Z coordinate displayed on the screen shows a certain value M.

[0023] Then move the stage so that the objective lens of the industrial microscope is aligned with the indicator post corresponding to the second corner point among any three points. After alignment, rotate the indicator post corresponding to the second corner point to move the indicator post away so that the indicator post does not block the objective lens, so that the objective lens can be aligned with the second corner point on the top surface of the substrate. Then adjust the height of the support post corresponding to the second corner point to adjust the position of the second corner point until the image at the second corner point in the eyepiece becomes clear. During the adjustment process, the Z coordinate value M displayed on the screen remains unchanged. When the image at the second corner point in the eyepiece becomes clear, the second corner point has been leveled.

[0024] Then move the stage so that the objective lens of the industrial microscope is aligned with the indicator post corresponding to the third triangular point among any three points. After alignment, rotate the indicator post corresponding to the third triangular point to move it away so that the indicator post does not block the objective lens, thus allowing the objective lens to be aligned with the third triangular point on the top surface of the substrate. Then, adjust the height of the support post corresponding to the third triangular point to adjust the position of the third triangular point until the image at the third triangular point in the eyepiece becomes clear. During the adjustment process, the Z coordinate value M displayed on the screen remains unchanged. When the image at the third triangular point in the eyepiece becomes clear, the third triangular point has been leveled.

[0025] Preferably, in step 4), when adjusting the focus for any one of the three leveled corner points, the process involves first selecting any one of the three corner points, then rotating the indicator post corresponding to that corner point so that the central axis of the indicator post coincides with the central axis of the support post corresponding to that corner point at axis L. Next, the stage is moved so that the objective lens of the industrial microscope is aligned with the indicator post. Then, the indicator post is rotated to move it away so that it does not obstruct the objective lens, allowing the objective lens to be aligned with the corner point. Focusing is then performed until the image at that corner point in the eyepiece becomes clear. At this point, the Z-coordinate value Z1 is displayed on the screen.

[0026] Preferably, in step 5), adjusting the focus on the remaining corner point that has not been leveled means moving the stage so that the objective lens of the industrial microscope is aligned with the indicator post corresponding to the remaining corner point, and then rotating the indicator post to move it away so that the indicator post does not block the objective lens, thereby allowing the objective lens to be aligned with the remaining corner point. Then, the focus is adjusted until the image at the remaining corner point in the eyepiece becomes clear. At this time, the Z coordinate value Z2 is displayed on the screen.

[0027] This invention also discloses a chip warpage testing fixture, which includes a base plate and four support columns disposed on the base plate. Each support column includes an outer sleeve fixed on the base plate and a support column body disposed in the inner cavity of the outer sleeve. A spherical top is provided on the top of the support column body. An internal thread is provided on the circumferential surface of the inner cavity of the outer sleeve, and an external thread is provided on the outer circumferential surface of the support column body. Through the cooperation of the internal thread and the external thread, the support column body is threadedly connected to the inner cavity of the outer sleeve. When adjusting, the support column body can be moved up and down simply by rotating it.

[0028] Each support column has an L-shaped connecting rod on its top side surface. The L-shaped connecting rod includes a horizontal connecting rod and a vertical connecting rod. One end of the horizontal connecting rod is connected to the top side surface of the support column via a bearing, and the other end of the horizontal connecting rod is connected to one end of the vertical connecting rod. An indicator column is positioned above each support column. The side surface of the indicator column is connected to one end of a rotating rod, and the other end of the rotating rod is rotatably connected to the other end of the vertical connecting rod, thus allowing the indicator column to be rotatably connected above the support column. A limit block is also provided on the horizontal connecting rod. When the indicator column rotates to contact the limit block, the central axis of the support column and the central axis of the indicator column coincide at axis L.

[0029] Preferably, the support column is fixed to the base plate.

[0030] Preferably, the support column is movably connected to the base plate, that is: four support modules are also provided on the base plate, each support module includes a mold base plate provided on the base plate, a sliding plate one provided on the mold base plate and a sliding plate two provided on the sliding plate one, and each support column is fixed on the sliding plate two of a support module.

[0031] The first sliding plate is slidably connected to the first slider mechanism via a guide rail on the mold base plate. A screw and nut transmission mechanism is also provided between the first sliding plate and the mold base plate, thereby enabling the first sliding plate to move back and forth along the X-axis. The second sliding plate is slidably connected to the first sliding plate via a guide rail and a second slider mechanism. A screw and nut transmission mechanism is also provided between the second sliding plate and the first sliding plate, thereby enabling the second sliding plate to move back and forth along the Y-axis.

[0032] Preferably, the support column is movably connected to the base plate, that is: the support column is a magnetic column, the base plate is made of a material that can be attracted by the magnetic column, and the support column is attracted and connected to the base plate.

[0033] The beneficial effects of this invention are as follows: By suspending the FCBGA product and first leveling any three corners of the FCBGA substrate, then testing the warp values ​​of the three corners and the remaining corner, and finally making a judgment, the dispersion of the values ​​at the four corners is reduced, ensuring the overall stability of the data. This allows the test results to accurately reflect the actual warp situation, thereby improving the accuracy of the test results and preventing some FCBGA products that do not meet the warp value standards from being mistakenly judged as qualified products, thus improving the quality of FCBGA products leaving the factory. By designing the above specific test steps, the testing operation process can be further simplified, and the testing efficiency can be improved while ensuring the accuracy of the test results. Attached Figure Description

[0034] Figure 1 This is a top view of the substrate located on the side of the unsoldered inverted chip.

[0035] Figure 2 A schematic diagram illustrating the principle and structure of the existing technology during testing;

[0036] Figure 3 This is a micron-scale magnified diagram of the substrate and stage during testing in the prior art.

[0037] Figure 4 This is a schematic diagram of the principle structure during testing in Embodiment 1 of the present invention;

[0038] Figure 5 This is a magnified micron-scale structural diagram of the substrate and stage during testing in Embodiment 1 of the present invention.

[0039] Figure 6 for Figure 4 A magnified schematic diagram of the structure located at corner point C, in which the central axis of the support column and the central axis of the indicator column coincide at axis L;

[0040] Figure 7 This is a partially enlarged three-dimensional structural diagram of the top of the support column in Embodiment 1 of the present invention;

[0041] Figure 8 for Figure 4 The diagram shows a partially enlarged view of the structure located at corner point C. The central axis of the support column and the central axis of the indicator column do not coincide.

[0042] Figure 9 This is a partial axial cross-sectional view of the support rod in Embodiment 1 of the present invention;

[0043] Figure 10 This is a top view schematic diagram of the chip warpage testing fixture in Embodiment 2 of the present invention.

[0044] Figure 11 This is a top view schematic diagram of the principle structure of a support module in the chip warp testing fixture of Embodiment 2 of the present invention;

[0045] In the diagram: 1. Substrate; 2. Stage; 3. Objective lens; 4. Chip warpage test fixture; 5. Support column; 511. Outer casing; 512. Support column body; 513. Spherical top; 6. Connecting rod; 611. Horizontal connecting rod; 612. Vertical connecting rod; 7. Indicator column; 8. Rotating rod; 9. Limiting block; 10. Support module; 101. Mold base plate; 102. Sliding plate one; 103. Sliding plate two; 104. Guide rail and slider mechanism one; 105. Screw and nut transmission mechanism one; 106. Guide rail and slider mechanism two; 107. Screw and nut transmission mechanism two; 11. Bearing; 12. Base plate. Detailed Implementation

[0046] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0047] The applicant discovered through research that, because FCBGA products are not regularly symmetrical deformed objects after warping, such as... Figure 3As shown, for example, when an FCBGA product with a "W" warped deformation is placed on stage 2 during testing, the measured corner points A, B, C, and D are not on the same horizontal plane. Therefore, on the Z-axis, the distances between the positions of corner points A, B, C, and D and the zero point position of the geometric center point P are different. That is, the four measured values ​​of corner points A, B, C, and D relative to the zero point position on the Z-axis are different, resulting in a large dispersion of the data. Suppose the measured values ​​of corner points A, B, C, and D relative to the zero point on the Z-axis are A1, B1, C1, and D1, respectively (as shown in the figure for corner points C and D; the value of corner point C relative to the zero point on the Z-axis is C1, and the value of corner point D relative to the zero point on the Z-axis is D1, where C1 > D1). Since current technology uses an averaging method, which calculates the average of the four corner point values, the dispersion of these values ​​is relatively large. In this case, suppose value C1 exceeds the standard range for warpage, while the values ​​of the other three corner points are within the standard range. The average of the four values ​​might be within the standard range for warpage, but in reality, value C1 exceeds the standard range. Therefore, the warpage of this FCBGA product does not actually meet the requirements. The problem is that value C1 is averaged with the other three values, causing the calculated average to be within the standard range for warpage, thus leading to the judgment that the warpage of the FCBGA product meets the requirements. This results in a discrepancy between the test results and the actual warpage, affecting the accuracy of the test results. Consequently, some FCBGA products that do not meet the warpage value standards are mistakenly judged as qualified products, thus reducing the quality of FCBGA products leaving the factory.

[0048] Therefore, such as Figure 4 As shown, this embodiment discloses a method for testing chip warpage using an industrial microscope. The method involves setting a chip warpage testing fixture 4 on a stage 2. The chip warpage testing fixture 4 is equipped with four support columns 5 that can be extended and retracted along the vertical direction (Z-axis direction). The steps of the method are as follows:

[0049] 1) During testing, the FCBGA product is placed on four support pillars 5 with the top surface S (one side of the substrate 1 without the inverted chip soldered) of the substrate 1 facing upwards. The four support pillars 5 are in contact with the four corners of the bottom surface of the substrate 1 respectively, so that the FCBGA product is suspended and supported, and the objective lens 3 of the industrial microscope faces the top surface S of the substrate 1.

[0050] 2) The contact points between the four support pillars 5 and the bottom surface of the substrate 1, corresponding to points on the top surface S of the substrate 1, are respectively designated as corner points A, B, C, and D. Any three of these corner points are selected, and the lengths of the three support pillars 5 corresponding to these three points are adjusted by extending or retracting the pillars to level the points, ensuring that the horizontal planes at these three points coincide. Figure 5 As shown, in this embodiment, corner points B (not shown in the figure), C and D are leveled so that corner points B, C and D are on the same horizontal plane E.

[0051] 3) Move the stage 2 so that the objective lens 3 of the industrial microscope is aligned with the geometric center point P of the substrate 1 and adjust the focus until the image of the geometric center point P in the eyepiece becomes clear; when the image of the geometric center point P becomes clear, stop the focus adjustment and perform a zeroing operation. At this time, the position of the geometric center point P is set as the zero point position.

[0052] 4) Move the stage 2 so that the objective lens 3 of the industrial microscope is aligned with any one of the three corner points leveled in step 2), and adjust the focus until the image in the eyepiece becomes clear. Once the image in the eyepiece is clear, stop adjusting the focus and record the Z-coordinate value Z1 displayed on the screen. Since the three corner points leveled in step 2) are all on the same horizontal plane, this value Z1 = the value of any one of the three corner points relative to the zero point position on the Z-axis, that is, the distance between the horizontal plane E and the horizontal plane G on the Z-axis (vertical). Figure 5 As shown, in this embodiment, the value Z1 = the value of corner point B relative to the zero point position on the Z-axis = the value of corner point C relative to the zero point position on the Z-axis = the value of corner point D relative to the zero point position on the Z-axis;

[0053] 5) Move the stage 2 so that the objective lens 3 of the industrial microscope is aligned with the remaining corner point that was not leveled in step 2), and adjust the focus until the image in the eyepiece becomes clear; when the image in the eyepiece becomes clear, stop adjusting the focus and record the Z coordinate value Z2 displayed on the screen at this time. This value Z2 = the value of the remaining corner point relative to the zero point position on the Z axis;

[0054] 6) Determine whether the values ​​Z1 in step 4) and Z2 in step 5) are both within the warp value standard; if both Z1 and Z2 are within the warp value standard, the warp value of the FCBGA product is deemed to meet the requirements; otherwise, the warp value of the FCBGA product is deemed to be unqualified.

[0055] This embodiment suspends the FCBGA product and first levels any three corners of the FCBGA product substrate. Then, it tests the warpage values ​​of the three corners and the remaining corner, and finally makes a judgment. This reduces the dispersion of the values ​​at the four corners, ensures the overall stability of the data, and allows the test results to accurately reflect the actual warpage. This improves the accuracy of the test results and avoids the phenomenon that some FCBGA products that do not meet the warpage value standard are mistakenly judged as qualified products, thus improving the quality of FCBGA products leaving the factory.

[0056] like Figure 6 and Figure 7 As shown, an L-shaped connecting rod 6 is also provided on the side circumferential surface of the top of each support column 5. The L-shaped connecting rod 6 includes a horizontal connecting rod 611 and a vertical connecting rod 612. One end of the horizontal connecting rod 611 is connected to the side circumferential surface of the top of the support column 5, and the other end of the horizontal connecting rod 611 is connected to one end of the vertical connecting rod 612. An indicator column 7 is provided above each support column 5. The side circumferential surface of the indicator column 7 is connected to one end of a rotating rod 8, and the other end of the rotating rod 8 is rotatably connected to the other end of the vertical connecting rod 612, so that the indicator column 7 is rotatably connected above the support column 5. A limit block 9 is also provided on the horizontal connecting rod 611. When the indicator column 7 rotates to contact the limit block 9, the central axis of the support column 5 and the central axis of the indicator column 7 coincide with axis L.

[0057] like Figure 6 and Figure 8 As shown, in step 2), when setting the corner point, the substrate 1 is first placed on the support post 5, and then the indicator post 7 is rotated so that the central axis of the support post 5 and the central axis of the indicator post 7 coincide at axis L. At this time, the intersection of axis L and the top surface of the substrate 1 is the corner point. Figure 6 Corner point C is located in the middle. By rotating the indicator posts corresponding to the four support posts, corner points A, B, C, and D can be obtained.

[0058] In step 2), leveling any three points involves first moving the stage 2 so that the objective lens of the industrial microscope is aligned with the indicator post 7 corresponding to one of the three corner points. Figure 6 First, level the corner point C, then align the objective lens with the indicator post 7 corresponding to corner point C. Here, objective lens alignment means aligning the center point of the objective lens with the center point of indicator post 7. After alignment, as shown... Figure 8 As shown, rotating the indicator post 7 corresponding to corner point C moves the indicator post 7 away, so that the indicator post 7 will not block the objective lens, thereby allowing the objective lens to be aligned with the corner point of the top surface of the substrate 1. Figure 7The objective lens is aligned with corner point C, and then the focus is adjusted until the image at corner point C in the eyepiece becomes clear. At this time, the Z coordinate displayed on the screen shows a certain value M.

[0059] Then move the stage 2 so that the objective lens of the industrial microscope is aligned with the indicator post 7 corresponding to the second corner point among any three points. After alignment, assuming the second corner point is corner point D, rotate the indicator post 7 corresponding to corner point D to move the indicator post 7 away so that the indicator post 7 will not block the objective lens, so that the objective lens can be aligned with corner point D on the top surface of the substrate 1. Then adjust the height of the support post 5 corresponding to the second corner point (corner point D) to adjust the position of the second corner point (corner point D) until the image at corner point D in the eyepiece becomes clear. During the adjustment process, the Z coordinate value M displayed on the screen remains unchanged, thus proving that when the image at corner point D in the eyepiece becomes clear, corner point D has been leveled, that is, corner point C and corner point D are on the same horizontal plane.

[0060] Then move the stage 2 so that the objective lens of the industrial microscope is aligned with the indicator post 7 corresponding to the third triangular point among any three points. After alignment, assuming the third triangular point is corner point B, rotate the indicator post 7 corresponding to corner point B to move the indicator post 7 away so that the indicator post 7 does not block the objective lens, so that the objective lens can be aligned with corner point B on the top surface of the substrate 1. Then, adjust the height of the support post 5 corresponding to the third triangular point (corner point B) to adjust the position of the third triangular point (corner point B) until the image at corner point B in the eyepiece becomes clear. During the adjustment process, the Z coordinate value M displayed on the screen remains unchanged, thus proving that when the image at corner point B in the eyepiece becomes clear, corner point B has been leveled, that is, corner points C, D and B are on the same horizontal plane. At this time, corner points B, C and D are all leveled.

[0061] In step 4), when adjusting the focus for any one of the three leveled corner points, first select any one of the three corner points, such as corner point B. Then rotate the indicator post 7 corresponding to corner point B so that the central axis of the indicator post 7 and the central axis of the support post 5 corresponding to corner point B coincide at axis L. Then move the stage 2 so that the objective lens of the industrial microscope is aligned with the indicator post 7. Then rotate the indicator post 7 to move it away so that the indicator post 7 does not block the objective lens, so that the objective lens can be aligned with corner point B. Then adjust the focus until the image at corner point B in the eyepiece becomes clear. At this time, the Z coordinate value Z1 is displayed on the screen.

[0062] In step 5), adjusting the focus on the remaining unleveled corner point (such as corner point A) means moving the stage 2 so that the objective lens of the industrial microscope is aligned with the indicator post 7 corresponding to corner point A. Then, the indicator post 7 is rotated to move it away so that it does not block the objective lens, allowing the objective lens to be aligned with corner point A. The focus is then adjusted until the image at corner point A in the eyepiece becomes clear. At this point, the Z coordinate value Z2 is displayed on the screen.

[0063] By designing the specific test steps described above, the test operation process can be further simplified, and the test efficiency can be improved while ensuring the accuracy of the test results.

[0064] like Figure 9 As shown, the chip warpage testing fixture 4 includes a base plate 12 and four support columns 5 disposed on the base plate 12. In this embodiment, the support columns 5 are fixedly disposed on the base plate 12. Each support column 5 includes an outer sleeve 511 fixed on the base plate 12 and a support column body 512 disposed in the inner cavity of the outer sleeve 511. A spherical top 513 is provided on the top of the support column body 512. During support, the spherical top 513 is in contact with the bottom surface of the substrate for support. The spherical top 513 can be made of silicone or rubber to achieve soft contact with the substrate. One end of the horizontal connecting rod 611 is connected to the side circumferential surface of the top of the support column body 512 through a bearing 11. The inner ring of the bearing 11 is interference-fitted onto the support column body 512, and the outer ring of the bearing 11 is connected to one end of the horizontal connecting rod 611. This design ensures that the horizontal connecting rod 611 will not rotate when the support column body 512 rotates and rises. An internal thread is provided on the inner circumferential surface of the outer sleeve 511, and an external thread is provided on the outer circumferential surface of the support column 512. Through the engagement of the internal and external threads, the support column 512 is threadedly connected to the inner cavity of the outer sleeve 511. For adjustment, simply rotating the support column 512 allows it to move up and down. Here, to achieve precise up and down movement of the support column 512, the threaded engagement structure between the support column 512 and the outer sleeve 511 can adopt the threaded engagement structure between the micrometer screw and the threaded bushing in a micrometer.

[0065] Example 2: Compared with Example 1, the difference is that the support column 5 in Example 1 is fixed on the base plate 12, while the support column 5 in this example is movably connected to the base plate 12. This is because when it is necessary to test FCBGA products of different specifications and models, the position of the support column 5 can be flexibly adjusted according to the different sizes of FCBGA products, which improves the versatility of this example.

[0066] like Figure 10 and Figure 11As shown, the chip warpage testing fixture 4 includes a base plate 12 and four support modules 10 disposed on the base plate 12. Each support module 10 includes a mold base plate 101 disposed on the base plate 12, a sliding plate 102 disposed on the mold base plate 101, and a sliding plate 103 disposed on the sliding plate 102. A support column 5 is fixed to the sliding plate 103. The sliding plate 102 is slidably connected to the mold base plate 101 via a guide rail and a slider mechanism 104. A support column 5 is also provided between the sliding plate 102 and the mold base plate 101. A lead screw and nut transmission mechanism 105 is provided, which drives a sliding plate 102 to move back and forth along the X-axis. A second sliding plate 103 is slidably connected to a slider mechanism 106 via a guide rail on the first sliding plate 102. A second lead screw and nut transmission mechanism 107 is also provided between the second sliding plate 103 and the first sliding plate 102, which drives the second sliding plate 103 to move back and forth along the Y-axis. The X-axis and Y-axis are perpendicular to each other on the horizontal plane. In this embodiment, rotating the lead screw of the first lead screw and nut transmission mechanism 105 and the lead screw and nut transmission mechanism 107 can adjust the position of the support column 5 on the horizontal plane. By adjusting the position of the four support columns 5, support for FCBGA products of different sizes and specifications can be achieved, improving the versatility of this embodiment.

[0067] Example 3: Compared to Example 1, the difference lies in that the support pillars in this example are also movably connected to the base plate. In this example, the chip warpage testing fixture includes a base plate and four support pillars disposed on the base plate. The support pillars are magnetic pillars, and the base plate is made of a material that can be attracted by the magnetic pillars. When it is necessary to adjust the position of the support pillars, simply move the support pillars to the appropriate position and then attach them to the base plate.

[0068] In summary, this invention reduces the dispersion of the four corner values ​​by suspending the FCBGA product, leveling any three corners of the FCBGA substrate, testing the warpage values ​​of the three corners and the remaining corner, and then making a final judgment. This ensures the overall stability of the data and allows the test results to accurately reflect the actual warpage, thereby improving the accuracy of the test results. It also prevents some FCBGA products that do not meet the warpage value standards from being mistakenly judged as qualified products, thus improving the quality of FCBGA products leaving the factory. By designing the above specific test steps, the testing operation process can be further simplified, improving testing efficiency while ensuring the accuracy of the test results.

[0069] In the embodiments, "multiple" refers to "two or more". The above embodiments are for illustrative purposes only and are not intended to limit the invention. Those skilled in the art can make various changes or modifications without departing from the spirit and scope of the invention. Therefore, all equivalent technical solutions should also fall within the protection scope of the invention, which is defined by the claims.

Claims

1. A method for testing chip warpage using an industrial microscope, characterized in that: A chip warpage testing fixture is set on a stage. The fixture has four vertically adjustable support columns. During testing, the FCBGA product is supported by the four support columns, making it suspended. Four corner points on the FCBGA product's substrate are selected. The adjustable support columns are used to level any three of the four corner points, thus adjusting the suspended position of the FCBGA product. After leveling, the geometric center of the FCBGA product is set as the zero point. The Z-axis value Z1 of any one of the three corner points and the Z-axis value Z2 of the remaining corner point are measured using an industrial microscope. Finally, the values ​​Z1 and Z2 are compared with the warpage value standard to determine whether the warpage value of the FCBGA product is qualified. Each support column has an L-shaped connecting rod on its top side surface, comprising a horizontal connecting rod and a vertical connecting rod. One end of the horizontal connecting rod is connected to the top side surface of the support column, and the other end is connected to one end of the vertical connecting rod. An indicator column is positioned above each support column, with its side surface connected to one end of a rotating rod, and the other end of the rotating rod rotatably connected to the other end of the vertical connecting rod, thus positioning the indicator column rotatably above the support column. A limit block is also provided on the horizontal connecting rod. When the indicator column rotates to contact the limit block, the central axis of the support column and the central axis of the indicator column coincide at axis L. When selecting corner points, the substrate is first placed on the support pillars, and then the indicator pillars are rotated so that the central axis of the support pillars and the central axis of the indicator pillars coincide with axis L. At this time, the intersection of axis L and the top surface of the substrate is the corner point. By rotating the indicator pillars corresponding to the four support pillars, corner points A, B, C and D are obtained.

2. The method according to claim 1, characterized in that: The specific steps of the method are as follows: 1) During testing, the FCBGA product is placed on four support pillars with the top surface S of the FCBGA product substrate facing upwards. The top surface S is one side of the substrate without the inverted chip soldered. The four support pillars are in contact with the four corners of the bottom surface of the substrate to suspend and support the FCBGA product, so that the objective lens of the industrial microscope faces the top surface S of the substrate. 2) The contact points between the four support columns and the bottom surface of the substrate are respectively designated as corner points A, B, C and D on the top surface S of the substrate. Any three of these corner points are selected, and the lengths of the three support columns corresponding to these three points are adjusted by stretching and extending to level the three points so that the horizontal planes at these three points coincide with each other. 3) Move the stage so that the objective lens of the industrial microscope is aligned with the geometric center point P of the substrate, and adjust the focus until the image of the geometric center point P in the eyepiece becomes clear; when the image of the geometric center point P becomes clear, stop the focus adjustment and perform a zeroing operation. At this time, the position of the geometric center point P is set as the zero point position. 4) Move the stage so that the objective lens of the industrial microscope is aligned with any one of the three corner points that were leveled in step 2), and adjust the focus until the image in the eyepiece becomes clear; once the image in the eyepiece is clear, stop adjusting the focus and record the Z coordinate value Z1 displayed on the screen at this time; 5) Move the stage so that the objective lens of the industrial microscope is aligned with the remaining corner point that was not leveled in step 2), and adjust the focus until the image in the eyepiece becomes clear; once the image in the eyepiece is clear, stop adjusting the focus and record the Z coordinate value Z2 displayed on the screen at this time; 6) Determine whether the values ​​Z1 in step 4) and Z2 in step 5) are both within the warp value standard; if both Z1 and Z2 are within the warp value standard, the warp value of the FCBGA product is deemed to meet the requirements; otherwise, the warp value of the FCBGA product is deemed to be unqualified.

3. The method according to claim 2, characterized in that: In step 2), leveling any three points involves first moving the stage so that the objective lens of the industrial microscope is aligned with the indicator post corresponding to one of the three corner points. After alignment, the indicator post corresponding to one of the corner points is rotated to move the indicator post away so that it does not block the objective lens. This allows the objective lens to be aligned with one of the corner points on the top surface of the substrate. Then, focus adjustment is performed until the image at one of the corner points in the eyepiece becomes clear. At this point, the Z coordinate displayed on the screen shows a certain value M. Then move the stage so that the objective lens of the industrial microscope is aligned with the indicator post corresponding to the second corner point among any three points. After alignment, rotate the indicator post corresponding to the second corner point to move the indicator post away so that the indicator post does not block the objective lens, so that the objective lens can be aligned with the second corner point on the top surface of the substrate. Then adjust the height of the support post corresponding to the second corner point to adjust the position of the second corner point until the image at the second corner point in the eyepiece becomes clear. During the adjustment process, the Z coordinate value M displayed on the screen remains unchanged. When the image at the second corner point in the eyepiece becomes clear, the second corner point has been leveled. Then move the stage so that the objective lens of the industrial microscope is aligned with the indicator post corresponding to the third triangular point among any three points. After alignment, rotate the indicator post corresponding to the third triangular point to move it away so that the indicator post does not block the objective lens, thus allowing the objective lens to be aligned with the third triangular point on the top surface of the substrate. Then, adjust the height of the support post corresponding to the third triangular point to adjust the position of the third triangular point until the image at the third triangular point in the eyepiece becomes clear. During the adjustment process, the Z coordinate value M displayed on the screen remains unchanged. When the image at the third triangular point in the eyepiece becomes clear, the third triangular point has been leveled.

4. The method according to claim 3, characterized in that: In step 4), when adjusting the focus for any one of the three corner points that have been leveled, first select any one of the three corner points, then rotate the indicator post corresponding to that corner point so that the central axis of the indicator post and the central axis of the support post corresponding to that corner point coincide again at axis L. Then move the stage so that the objective lens of the industrial microscope is aligned with the indicator post. Then rotate the indicator post to move it away so that the indicator post does not block the objective lens, thus allowing the objective lens to be aligned with the corner point. Then adjust the focus until the image at the corner point in the eyepiece becomes clear. At this time, the Z coordinate value Z1 is displayed on the screen.

5. The method according to claim 4, characterized in that: In step 5), adjusting the focus on the remaining corner point that has not been leveled means moving the stage so that the objective lens of the industrial microscope is aligned with the indicator post corresponding to the remaining corner point, and then rotating the indicator post to move it away so that the indicator post does not block the objective lens, thereby allowing the objective lens to be aligned with the remaining corner point. Then, the focus is adjusted until the image at the remaining corner point in the eyepiece becomes clear. At this time, the Z coordinate value Z2 is displayed on the screen.

6. A chip warpage testing fixture, characterized in that: The device includes a base plate and four support columns mounted on the base plate. Each support column includes an outer sleeve fixed to the base plate and a support column body disposed within the inner cavity of the outer sleeve. A spherical top is provided on the top of each support column body. An internal thread is provided on the circumferential surface of the inner cavity of the outer sleeve, and an external thread is provided on the outer circumferential surface of the support column body. Through the cooperation of the internal and external threads, the support column body is threadedly connected to the inner cavity of the outer sleeve. When adjusting, the support column body can be moved up and down simply by rotating it. Each support column has an L-shaped connecting rod on its top side surface. The L-shaped connecting rod includes a horizontal connecting rod and a vertical connecting rod. One end of the horizontal connecting rod is connected to the top side surface of the support column via a bearing, and the other end of the horizontal connecting rod is connected to one end of the vertical connecting rod. An indicator column is positioned above each support column. The side surface of the indicator column is connected to one end of a rotating rod, and the other end of the rotating rod is rotatably connected to the other end of the vertical connecting rod, thus allowing the indicator column to be rotatably connected above the support column. A limit block is also provided on the horizontal connecting rod. When the indicator column rotates to contact the limit block, the central axis of the support column and the central axis of the indicator column coincide at axis L.

7. The chip warpage testing fixture according to claim 6, characterized in that: The support column is fixed to the base plate.

8. The chip warpage testing fixture according to claim 6, characterized in that: The support column is movably connected to the base plate, that is: four support modules are also provided on the base plate, each support module includes a mold base plate provided on the base plate, a sliding plate one provided on the mold base plate and a sliding plate two provided on the sliding plate one, and each support column is fixed on the sliding plate two of a support module. The first sliding plate is slidably connected to the first slider mechanism via a guide rail on the mold base plate. A screw and nut transmission mechanism is also provided between the first sliding plate and the mold base plate, thereby enabling the first sliding plate to move back and forth along the X-axis. The second sliding plate is slidably connected to the first sliding plate via a guide rail and a second slider mechanism. A screw and nut transmission mechanism is also provided between the second sliding plate and the first sliding plate, thereby enabling the second sliding plate to move back and forth along the Y-axis.

9. The chip warpage testing fixture according to claim 6, characterized in that: The support column is movably connected to the base plate, that is: the support column is a magnetic column, the base plate is made of a material that can be attracted by the magnetic column, and the support column is attracted and connected to the base plate.

Images