Flip chip package failure joint location method and grinding method

Abstract

The application discloses a kind of flip-chip package failure solder joint positioning method and grinding method, grinding method includes a. First, according to the electrical test result from test system to determine the name of failure solder joint, according to the design layout of chip to determine the horizontal and vertical distance of the projection of solder joint on substrate to origin, respectively recorded as a and b;B. Fix the substrate of chip;C. Utilize laser scanner to form laser spot at the corresponding position of failure solder joint on silicon base;D. With the vertex of one of the corners of mark block as mark angle, adjust the position of mark angle in longitudinal and transverse direction, so that the projection of mark angle in vertical direction coincides with laser spot;E. Mark block is lowered until the end surface on silicon base of chip is contacted, positioning is completed;F. The sample marked is taken out, and the chip is positioned and ground at failure solder joint on grinding machine from grinding starting point. Efficient positioning and grinding of flip-chip failure solder joint are realized, and the positioning and grinding efficiency is improved.

Description

Technical Field

[0001] This invention relates to a method for locating and grinding failed solder joints in flip chip packaging. Background Technology

[0002] Flip-chip technology has become the mainstream technology in chip packaging, characterized by solder joints located on the bottom of the silicon substrate. Numerous solder joints serve as signal and current transmission carriers, connecting the chip to the substrate. Open-circuit and short-circuit failures of packaged solder joints are the most common failure phenomena. Non-destructive testing methods can perform electrical and contour analysis of failed solder joints; however, to find the true cause of solder joint failure, precise location and cross-sectional analysis are required. Cross-sectional analysis of failed solder joints can identify solder joint failures caused by foreign objects or other factors, providing accurate directions for process improvement, ensuring the yield rate of subsequent products, and improving economic efficiency. Furthermore, with the increase in business volume, the number of packaged solder joint failure cases is also rising continuously; therefore, improving the efficiency of packaged solder joint failure analysis is crucial. Because the solder joints of flip chips are obscured by the silicon substrate, the location of failed solder joints is not clearly indicated on the back of the chip. In the past, in order to determine the location of failed bumps and the grinding location, X-rays were used to compare the grinding location with the location of the failed solder joint multiple times. That is, after grinding a short distance, X-rays were used to detect how far away from the failed solder joint was, and this operation was repeated many times. This positioning and grinding method greatly reduced the grinding efficiency. Therefore, it is extremely urgent to find a new fast and accurate positioning and grinding method, which is crucial for timely improvement of subsequent processes. Summary of the Invention

[0003] The purpose of this invention is to provide a highly efficient and accurate method for locating failed solder joints in flip-chip packaging.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is: a method for locating failed solder joints in flip-chip packaging, which utilizes a positioning device to locate the failed solder joints of the chip. The positioning device includes a laser scanner and marking blocks that can move perpendicularly in the horizontal, vertical, and longitudinal directions. The horizontal and vertical directions are parallel to the upper surface of the chip substrate.

[0005] a. First, determine the name of the failed solder joint from the test system based on the electrical test results. Then, set the vertex of any corner on the upper surface of the chip substrate as the origin (0,0). Determine the horizontal and vertical distances of the solder joint's projection onto the substrate from the origin based on the chip's design layout, and denot them as a and b, respectively.

[0006] b. Fix the substrate of the chip to be analyzed;

[0007] c. Using a laser scanner, the laser is directed downwards onto the vertical substrate, with the initial position of the laser spot at the origin. The laser spot movement distance (A, B) is set such that A = a and B = b, thereby realizing the movement of the laser spot.

[0008] d. Using the vertex of one corner of the marking block as the marking angle, adjust the position of the marking angle in the vertical and horizontal directions so that the vertical projection of the marking angle coincides with the laser spot;

[0009] e. The marking block moves down until it contacts the upper surface of the silicon substrate of the chip, and the marking corner leaves an imprint on the upper surface of the silicon substrate, thus completing the positioning.

[0010] The optimized design features ink on the lower surface of the marking corner, which more clearly indicates the location of the failed solder joint.

[0011] The optimized positioning device includes a sample stage, a lateral positioning mechanism mounted on the sample stage for moving and positioning the marking block laterally, a longitudinal positioning mechanism for moving and positioning the marking block longitudinally, and a vertical moving mechanism for moving and positioning the marking block vertically. The cooperation of the lateral and longitudinal positioning mechanisms allows the marking corner to be accurately moved directly above the failed solder joint.

[0012] The optimized lateral positioning mechanism includes a lateral moving component and a lateral support block mounted on the upper surface of the sample stage. The lateral moving component includes a fixed block, a lateral slider that can slide laterally on a plane parallel to the upper surface of the sample stage, and a lateral telescopic component connecting the fixed block and the lateral slider for driving the lateral slider to move laterally. Using a fixed lateral support block can save on the manufacturing cost of the lateral moving component.

[0013] The optimized longitudinal positioning mechanism includes a first longitudinal slider and a second longitudinal slider, a print base suspended between the first and second longitudinal sliders, and longitudinal telescopic members respectively connected between the print base and the first longitudinal slider and between the print base and the second longitudinal slider. The first and second longitudinal sliders slide longitudinally along a plane parallel to the upper surface of the sample stage and perpendicular to the transverse direction. The first and second longitudinal sliders are slidably connected to the transverse slider and the transverse support block, respectively. The longitudinal telescopic members fix the longitudinal positions of the first and second longitudinal sliders on the transverse slider and the transverse support block, preventing displacement of the longitudinal position of the print mark.

[0014] The optimized vertical movement mechanism includes a marker block, a helical rod whose lower end is rotatably connected to the marker block and threadedly connected to the block base, and a guide rod connected between the marker block and the block base. The helical rod drives the marker block to move in directions perpendicular to the horizontal and vertical directions. The guide rod ensures that the marker block can only move vertically, preventing any displacement of the marker block in the horizontal and vertical directions.

[0015] The optimized lateral positioning mechanism includes at least two lateral moving components mounted on the upper surface of the sample stage. Each lateral moving component includes a fixed block, a lateral slider that can slide laterally in a plane parallel to the upper surface of the sample stage, and a lateral telescopic member connected between the fixed block and the lateral slider for driving the lateral slider to move laterally. With two lateral positioning mechanisms, the position of the marking block can be adjusted more flexibly over a wider range.

[0016] An optimized longitudinal positioning mechanism includes a first longitudinal slider and a second longitudinal slider, a print base suspended between the first and second longitudinal sliders, and longitudinal telescopic members respectively connected between the print base and the first longitudinal slider and between the print base and the second longitudinal slider. The first and second longitudinal sliders slide longitudinally along a plane parallel to the upper surface of the sample stage and perpendicular to the transverse direction. The first and second longitudinal sliders are slidably connected to the transverse slider. The longitudinal telescopic members fix the longitudinal positions of the first and second longitudinal sliders on the transverse slider and the transverse support block, preventing displacement of the longitudinal position of the print mark.

[0017] The present invention also provides a grinding method based on the above positioning method, which includes the following steps:

[0018] a. First, determine the name of the failed solder joint from the test system based on the electrical test results. Then, set the vertex of any corner on the upper surface of the chip substrate as the origin (0,0). Determine the horizontal and vertical distances of the solder joint's projection onto the substrate from the origin based on the chip's design layout, and denot them as a and b, respectively.

[0019] b. Fix the substrate of the chip to be analyzed;

[0020] c. Using a laser scanner, the laser is directed downwards onto the vertical substrate, with the initial position of the laser spot at the origin. The laser spot movement distance (A, B) is set such that A = a and B = b, thereby realizing the movement of the laser spot.

[0021] d. Using the vertex of one corner of the marking block as the marking angle, adjust the position of the marking angle in the vertical and horizontal directions so that the vertical projection of the marking angle coincides with the laser spot;

[0022] e. The marking block moves down until it contacts the upper surface of the silicon substrate of the chip, and the marking corner leaves an imprint on the upper surface of the silicon substrate, thus completing the positioning;

[0023] f. Take out the marked sample and grind the chip on the grinding machine from the grinding starting point until the failure solder joint is located.

[0024] 10. The grinding method according to claim 9, characterized in that: when grinding approaches the marked position, the distance between the ground position and the failed solder joint is determined by X-ray, and grinding continues according to the distance.

[0025] Due to the application of the above technical solutions, this invention has the following advantages compared with the prior art: it achieves efficient positioning and grinding of failed solder joints in flip-chip packaging, avoids the need to use X-rays to determine the position of solder joints multiple times during the grinding process, and greatly improves the positioning and grinding efficiency; this invention can also be applied to the positioning and grinding of failed solder joints in advanced flip-chip packaging, and has broad application prospects and value. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the positioning device in Embodiment 1 of the present invention;

[0027] Figure 2 This is a schematic diagram of the positioning device in Embodiment 2 of the present invention;

[0028] Figure 3 This is a top view of the chip to be polished;

[0029] Figure 4 This is a cross-sectional view of the polished chip;

[0030] Figure 5 A schematic diagram showing the design location of solder joints on the board.

[0031] Figure 6 This is a schematic diagram showing the displacement position of the laser spot;

[0032] Figure 7 This is a schematic diagram indicating the location of solder joints after the marking on the printing block (arrows indicate solder joint locations). Detailed Implementation

[0033] The present invention will be further described below with reference to the embodiments shown in the accompanying drawings.

[0034] Example 1

[0035] The flip-chip package failure solder joint location grinding method utilizes a positioning device to locate the failure solder joint, such as... Figure 1 As shown, the positioning device for the failed solder joint of the flip chip package includes: a sample stage 5, a laser scanner 4, a horizontal positioning mechanism 3, a vertical positioning mechanism 2, and a vertical moving mechanism 1.

[0036] The lateral positioning mechanism 3 includes a lateral moving component 31 and a lateral support block 32 mounted on the upper surface of the sample stage 5. The lateral moving component 31 includes a fixed block 33, a lateral slider 34 that can slide laterally on a plane parallel to the upper surface of the sample stage 5, and a lateral telescopic component 35 connected between the fixed block 33 and the lateral slider 34 for driving the lateral slider 34 to move laterally.

[0037] The longitudinal positioning mechanism 2 includes a first longitudinal slider 21 and a second longitudinal slider 22, a print base 23 suspended between the first longitudinal slider 21 and the second longitudinal slider 22, and longitudinal telescopic members 24 connected between the print base 23 and the first longitudinal slider 21, and between the print base 23 and the second longitudinal slider 22. The first longitudinal slider 21 and the second longitudinal slider 22 slide longitudinally along a plane parallel to the upper surface of the sample stage 5 and perpendicular to the transverse direction. The first longitudinal slider 21 and the second longitudinal slider 22 are slidably connected to the transverse slider 34 and the transverse support block 32, respectively. The transverse telescopic member 35 is a cylinder, a hydraulic cylinder, or an inner sleeve and an outer sleeve that are fitted together and can slide relative to each other. The longitudinal telescopic member 24 is a cylinder, a hydraulic cylinder, or an inner sleeve and an outer sleeve that are fitted together and can slide relative to each other. The fitted inner sleeve and outer sleeve can be used to manually and quickly complete the transverse positioning, and the cylinder or hydraulic cylinder can be used to achieve automated transverse positioning. Both the horizontal slider 34 and the horizontal support block 32 have longitudinally arranged guide blocks 36 on their upper surfaces. The lower surface of the first longitudinal slider 21 has a first groove 25, and the lower surface of the second longitudinal slider 22 has a second groove 26. The guide blocks 36 are respectively disposed in the first groove 25 and the second groove 26, allowing the first longitudinal slider 21 and the second longitudinal slider 22 to slide along the guide blocks 36. After the longitudinal position is determined, the longitudinal telescopic member 24 extends to fix the position of the first longitudinal slider 21 and the second longitudinal slider 22 in the guide block 36, ensuring that the position of the marking block in the longitudinal direction will not shift. The width of the guide block 36 is smaller than the width of the upper surfaces of the transverse slider 34 and the transverse support block 32. When the first longitudinal slider 21 and the second longitudinal slider 22 are respectively engaged on the guide block 36, the lower surface of the first longitudinal slider 21 is located on the upper surface of the transverse slider 34, and the lower surface of the second longitudinal slider 22 is located on the upper surface of the transverse support block 32; or the lower surface of the second longitudinal slider 22 is located on the upper surface of the transverse slider 34, and the lower surface of the first longitudinal slider 21 is located on the upper surface of the transverse support block 32. The upper surfaces of the transverse slider 34 and the transverse support block 32 respectively support the lower surfaces of the first longitudinal slider 21 and the second longitudinal slider 22, making the sliding of the first longitudinal slider 21 and the second longitudinal slider 22 more stable in the longitudinal direction.

[0038] The vertical moving mechanism 1 includes a marker block 11, a screw rod 12 whose lower end is rotatably connected to the marker block 11 and threadedly connected to the block base 23, and a guide rod 13 connected between the marker block 11 and the block base 23. The screw rod 12 drives the marker block 11 to move in directions perpendicular to the horizontal and vertical directions.

[0039] like Figure 3-7 As shown, the positioning grinding method includes the following steps:

[0040] a. First, determine the name of the failed solder joint 8 from the test system based on the electrical test results. Then, set the vertex of any corner of the chip package substrate 9 as the origin (0,0), the horizontal direction as the horizontal direction, and the vertical direction as the vertical direction. Determine the horizontal distance from the solder joint 8 to the origin based on the chip package design layout and record it as a and b.

[0041] b. Fix the failed chip package to be analyzed on the sample stage 5, and clamp and position the substrate 9 of the chip package by adjusting the horizontal slider 34.

[0042] c. Using laser scanner 4, the initial position of the laser spot is located at the origin, and the spot movement distance (A, B) is set such that the distance satisfies A = a; B = b, thereby realizing the movement of the laser spot;

[0043] d. Using the vertex of one corner of the marking block as the marking point, move the first vertical slider 21 and the second vertical slider 22 to adjust the position of the marking point in the vertical direction, and move the marking block base 23 to adjust the position of the marking point in the horizontal direction, so that the vertical projection of the marking point coincides with the laser spot.

[0044] e. Rotate the screw rod 12 to drive the marking block down until it contacts the upper surface of the silicon substrate of the chip package and leaves a mark on the upper surface of the silicon substrate. At this time, the vertex of the upper surface of the silicon substrate corresponding to the origin is the grinding starting point.

[0045] f. Take out the marked sample and grind the chip package from the grinding start point on the grinder to locate the failed solder joint 8 until the failed solder joint 8 is reached.

[0046] Ink is applied to the lower surface of the marking corner. This facilitates the identification of the projection position of the failed solder joint 8 onto the upper surface of the silicon substrate. When grinding approaches the marking position, X-rays are used to determine the distance between the ground position and the failed solder joint 8, and grinding continues according to this distance. This prevents over-grinding.

[0047] Example 2

[0048] The flip-chip package failure solder joint location grinding method utilizes a positioning device to locate the failure solder joint, such as... Figure 2As shown, the positioning device for the failed solder joint of the flip chip package includes: a sample stage 5, a laser scanner 4, a horizontal positioning mechanism 3, a vertical positioning mechanism 2, and a vertical moving mechanism 1.

[0049] The lateral positioning mechanism 3 includes at least two lateral moving components 31 mounted on the upper surface of the sample stage 5. Each lateral moving component 31 includes a fixed block 33, a lateral slider 34 that can slide laterally on a plane parallel to the upper surface of the sample stage 5, and a lateral telescopic member 35 connected between the fixed block 33 and the lateral slider 34 for driving the lateral slider 34 to move laterally.

[0050] The longitudinal positioning mechanism 2 includes a first longitudinal slider 21 and a second longitudinal slider 22, a print base 23 suspended between the first longitudinal slider 21 and the second longitudinal slider 22, and longitudinal telescopic members 24 respectively connected between the print base 23 and the first longitudinal slider 21 and between the print base 23 and the second longitudinal slider 22. The first longitudinal slider 21 and the second longitudinal slider 22 slide longitudinally along a plane parallel to the upper surface of the sample stage 5 and perpendicular to the transverse direction. The first longitudinal slider 21 and the second longitudinal slider 22 are slidably connected to the transverse slider 34. The transverse telescopic member 35 is a cylinder, a hydraulic cylinder, or an inner sleeve and an outer sleeve that are fitted together and can slide relative to each other. The longitudinal telescopic member 24 is a cylinder, a hydraulic cylinder, or an inner sleeve and an outer sleeve that are fitted together and can slide relative to each other. The fitted inner sleeve and outer sleeve can be used to manually and quickly complete the transverse positioning, and the cylinder or hydraulic cylinder can be used to achieve automated transverse positioning. Each horizontal slider 34 has a guide block 36 arranged longitudinally on its upper surface. The first vertical slider 21 has a first groove 25 on its lower surface, and the second vertical slider 22 has a second groove 26 on its lower surface. The guide blocks 36 are respectively positioned within the first groove 25 and the second groove 26, allowing the first and second vertical sliders 21 and 22 to slide along the guide blocks 36. After the longitudinal position is determined, the longitudinal telescopic member 24 extends, fixing the positions of the first and second vertical sliders 21 and 22 on the guide blocks 36, ensuring that the marking block's position does not shift in the longitudinal direction. The width of the guide block 36 is less than the width of the upper surfaces of the horizontal slider 34 and the horizontal support block 32. When the first and second vertical sliders 21 and 22 are respectively engaged with the guide blocks, the lower surface of the first vertical slider 21 is located on the upper surface of the horizontal slider 34. The upper surfaces of the horizontal slider 34 and the horizontal support block 32 support the lower surfaces of the first and second vertical sliders 21 and 22, respectively, making the longitudinal sliding of the first and second vertical sliders 21 and 22 more stable.

[0051] The vertical moving mechanism 1 includes a marker block, a screw rod 12 whose lower end is rotatably connected to the marker block and threadedly connected to the block base 23, and a guide rod 13 connected between the marker block and the block base 23. The screw rod 12 drives the marker block to move in directions perpendicular to the horizontal and vertical directions.

[0052] like Figure 3-7 As shown, the positioning grinding method includes the following steps:

[0053] a. First, determine the name of the failed solder joint 8 from the test system based on the electrical test results. Then, set the vertex of any corner of the chip package substrate 9 as the origin (0,0), the horizontal direction as the horizontal direction, and the vertical direction as the vertical direction. Determine the horizontal distance from the solder joint 8 to the origin based on the chip package design layout and record it as a and b.

[0054] b. Fix the failed chip package to be analyzed on the sample stage 5, and clamp and position the substrate 9 of the chip package by adjusting the horizontal slider 34.

[0055] c. Using laser scanner 4, the initial position of the laser spot is located at the origin, and the spot movement distance (A, B) is set such that the distance satisfies A = a; B = b, thereby realizing the movement of the laser spot;

[0056] d. Using the vertex of one corner of the marking block as the marking point, move the first vertical slider 21 and the second vertical slider 22 to adjust the position of the marking point in the vertical direction, and move the marking block base 23 to adjust the position of the marking point in the horizontal direction, so that the vertical projection of the marking point coincides with the laser spot.

[0057] e. Rotate the screw rod 12 to drive the marking block down until it contacts the upper surface of the silicon substrate of the chip package and leaves a mark on the upper surface of the silicon substrate. At this time, the vertex of the upper surface of the silicon substrate corresponding to the origin is the grinding starting point.

[0058] f. Take out the marked sample and grind the chip package from the grinding start point on the grinder to locate the failed solder joint 8 until the failed solder joint 8 is reached.

[0059] Ink is applied to the lower surface of the marking corner. This facilitates the identification of the projection position of the failed solder joint 8 onto the upper surface of the silicon substrate. When grinding approaches the marking position, X-rays are used to determine the distance between the ground position and the failed solder joint 8, and grinding continues according to this distance. This prevents over-grinding.

[0060] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for locating failed solder joints in a flip-chip package, comprising a positioning device for locating the failed solder joints of the chip, the positioning device including a laser scanner and marking blocks capable of moving perpendicularly in the horizontal, vertical, and transverse directions, the horizontal and vertical directions being parallel to the upper surface of the chip substrate. a. First, determine the name of the failed solder joint from the test system based on the electrical test results. Then, set the vertex of any corner on the upper surface of the chip substrate as the origin (0,0). Determine the horizontal and vertical distances of the solder joint's projection onto the substrate from the origin based on the chip's design layout, and denot them as a and b, respectively. b. Fix the substrate of the chip to be analyzed; c. Using a laser scanner, the laser is directed downwards onto the vertical substrate, with the initial position of the laser spot at the origin. The laser spot movement distance (A, B) is set such that A = a and B = b, thereby realizing the movement of the laser spot. d. Using the vertex of one corner of the marking block as the marking angle, adjust the position of the marking angle in the vertical and horizontal directions so that the vertical projection of the marking angle coincides with the laser spot; e. The marking block moves down until it contacts the upper surface of the silicon substrate of the chip, and the marking corner leaves an imprint on the upper surface of the silicon substrate, thus completing the positioning.

2. The positioning method according to claim 1, characterized in that: The lower surface of the marking corner is covered with ink.

3. The positioning method according to claim 1, characterized in that: The positioning device includes a sample stage, a lateral positioning mechanism mounted on the sample stage for moving and positioning the marking block in the lateral direction, a longitudinal positioning mechanism for moving and positioning the marking block in the longitudinal direction, and a vertical moving mechanism for moving and positioning the marking block in the vertical direction.

4. The positioning method according to claim 3, characterized in that: The lateral positioning mechanism includes a lateral moving component and a lateral support block mounted on the upper surface of the sample stage. The lateral moving component includes a fixed block, a lateral slider that can slide laterally on a plane parallel to the upper surface of the sample stage, and a lateral telescopic component connected between the fixed block and the lateral slider for driving the lateral slider to move laterally.

5. The positioning method according to claim 4, characterized in that: The longitudinal positioning mechanism includes a first longitudinal slider and a second longitudinal slider, a print base suspended between the first longitudinal slider and the second longitudinal slider, and longitudinal telescopic members respectively connected between the print base and the first longitudinal slider and between the print base and the second longitudinal slider. The first longitudinal slider and the second longitudinal slider slide along a longitudinal direction parallel to the upper surface of the sample stage and perpendicular to the transverse direction. The first longitudinal slider and the second longitudinal slider are slidably connected to the transverse slider and the transverse support block, respectively.

6. The positioning method according to claim 3, characterized in that: The vertical moving mechanism includes a marker block, a spiral rod whose lower end is rotatably connected to the marker block and threadedly connected to the block base, and a guide rod connected between the marker block and the block base. The spiral rod drives the marker block to move in directions perpendicular to the horizontal and vertical directions.

7. The positioning method according to claim 3, characterized in that: A lateral positioning mechanism includes at least two lateral moving components mounted on the upper surface of the sample stage. Each lateral moving component includes a fixed block, a lateral slider that can slide laterally on a plane parallel to the upper surface of the sample stage, and a lateral telescopic member connected between the fixed block and the lateral slider for driving the lateral slider to move laterally.

8. The positioning method according to claim 7, characterized in that: The longitudinal positioning mechanism includes a first longitudinal slider and a second longitudinal slider, a print base suspended between the first longitudinal slider and the second longitudinal slider, and longitudinal telescopic members respectively connected between the print base and the first longitudinal slider and between the print base and the second longitudinal slider. The first longitudinal slider and the second longitudinal slider slide along a longitudinal direction parallel to the upper surface of the sample stage and perpendicular to the transverse direction. The first longitudinal slider and the second longitudinal slider are slidably connected to the transverse slider.

9. A grinding method based on the positioning method according to any one of claims 1-8, characterized in that, It includes the following steps: a. First, determine the name of the failed solder joint from the test system based on the electrical test results. Then, set the vertex of any corner on the upper surface of the chip substrate as the origin (0,0). Determine the horizontal and vertical distances of the solder joint's projection onto the substrate from the origin based on the chip's design layout, and denot them as a and b, respectively. b. Fix the substrate of the chip to be analyzed; c. Using a laser scanner, the laser is directed downwards onto the vertical substrate, with the initial position of the laser spot at the origin. The laser spot movement distance (A, B) is set such that A = a and B = b, thereby realizing the movement of the laser spot. d. Using the vertex of one corner of the marking block as the marking angle, adjust the position of the marking angle in the vertical and horizontal directions so that the vertical projection of the marking angle coincides with the laser spot; e. The marking block moves down until it contacts the upper surface of the silicon substrate of the chip, and the marking corner leaves an imprint on the upper surface of the silicon substrate, thus completing the positioning; f. Take out the marked sample and grind the chip on the grinding machine from the grinding starting point until the failure solder joint is located.

10. The grinding method according to claim 9, characterized in that: When grinding approaches the marked position, X-rays are used to determine the distance between the ground position and the failed solder joint, and grinding continues according to the distance.

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