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CN-120558109-B - Method for testing chip warpage by using industrial microscope and chip warpage testing tool

CN120558109BCN 120558109 BCN120558109 BCN 120558109BCN-120558109-B

Abstract

The invention discloses a method for testing chip warpage by using an industrial microscope and a chip warpage test tool, wherein the method is that the chip warpage test tool is arranged on an objective table, four support columns are arranged on the chip warpage test tool, during testing, an FCBGA product is supported by the four support columns to enable the product to be in a suspended state, four corner points on a substrate of the product are selected, firstly, any three corner points of the four corner points are leveled by the support columns capable of being adjusted in a telescopic manner, so that the suspended position of the product is adjusted, after leveling, the geometric center of the product is set to be a zero point position, then, the Z-axis numerical value Z1 of any corner point position of any three corner points of the four corner points and the Z-axis numerical value Z2 of the rest corner points of the four corner points are measured by the industrial microscope, and finally, the numerical value Z1 and the numerical value Z2 are evaluated with a warpage value standard, so that whether the warpage value of the product is qualified is judged.

Inventors

  • WEI YAOCHENG

Assignees

  • 湖南越摩先进半导体有限公司

Dates

Publication Date
20260508
Application Date
20250528

Claims (9)

  1. 1. A method for testing chip warpage by utilizing an industrial microscope is characterized in that a chip warpage test fixture is arranged on an objective table, the chip warpage test fixture is provided with four support columns capable of being adjusted in a telescopic mode in the vertical direction, during testing, an FCBGA product is supported by the four support columns to be in a suspended state, four corner points on a substrate of the FCBGA product are selected, firstly, any three corner points of the four corner points are leveled by the support columns capable of being adjusted in a telescopic mode, so that the suspended position of the FCBGA product is adjusted; the device comprises a plurality of support columns, wherein each support column is provided with a side peripheral surface, the side peripheral surface of the top of each support column is also provided with an L-shaped connecting rod, each L-shaped connecting rod comprises a horizontal connecting rod and a vertical connecting rod, one end of each horizontal connecting rod is connected with the side peripheral surface of the top of each support column, and the other end of each horizontal connecting rod is connected with one end of a rotating rod; When the corner points are selected, the substrate is placed on the support columns, the indicating columns are rotated, so that the central axes of the support columns and the central axes of the indicating columns are mutually overlapped with each other and are the corner points, and the corner points A, the corner points B, the corner points C and the corner points D are obtained by rotating the indicating columns corresponding to the four support columns.
  2. 2. The method according to claim 1, wherein the method comprises the following specific steps: 1) During testing, placing the FCBGA product on four support columns in a state that the top surface S of a substrate of the FCBGA product faces upwards, wherein the top surface S is one side surface of the substrate of the unwelded inverted chip, and the FCBGA product is suspended and supported by utilizing the four support columns to be respectively contacted with four corner positions of the bottom surface of the substrate, so that an objective lens of an industrial microscope faces the top surface S of the substrate; 2) The points of the contact points between the four support columns and the bottom surface of the substrate, which correspond to the top surface S of the substrate, are respectively set as a corner A, a corner B, a corner C and a corner D, any three points among the corner A, the corner B, the corner C and the corner D are selected, and the lengths of the three support columns corresponding to the any three points are adjusted through expansion and contraction, so that the any three points are leveled, and the horizontal planes where the any three points are located are mutually overlapped; 3) Moving the objective table to enable the objective lens of the industrial microscope to be aligned with the position of the geometric center point P of the substrate, and performing focusing adjustment until the image of the geometric center point P in the eyepiece becomes clear; 4) Moving the objective table to enable the objective lens of the industrial microscope to be aligned with any one of the three corner points leveled in the step 2), and performing focusing adjustment until the image in the ocular lens becomes clear; 5) Moving the objective table to enable the objective lens of the industrial microscope to be aligned with the rest corner point which is not leveled in the step 2), and performing focusing adjustment until the image in the ocular lens becomes clear, stopping focusing adjustment after the image in the ocular lens becomes clear, and recording the numerical value Z2 of the Z coordinate displayed in the display screen at the moment; 6) Judging whether the numerical value Z1 in the step 4) and the numerical value Z2 in the step 5) are in the warpage value standard, if the numerical value Z1 and the numerical value Z2 are in the warpage value standard, judging that the warpage value of the FCBGA product meets the requirement, otherwise, judging that the warpage value of the FCBGA product is unqualified.
  3. 3. The method of claim 2, wherein the leveling of any three points in step 2) is performed by moving the stage first to align the objective lens of the industrial microscope with the indication column corresponding to one of the corner points in any three points, and after the alignment, rotating the indication column corresponding to one of the corner points to move the indication column away, so that the indication column does not shield the objective lens, thereby enabling the objective lens to align with the one of the corner points of the top surface of the substrate, and performing focusing adjustment until the image at the one of the corner points in the eyepiece becomes clear, wherein the Z coordinate displayed in the display screen displays a certain value M; Then moving the objective table to enable the objective lens of the industrial microscope to be aligned with an indication column corresponding to a second angular point in any three points, after alignment, rotating the indication column corresponding to the second angular point to remove the indication column, so that the indication column does not shield the objective lens, and therefore the objective lens can be aligned with the second angular point of the top surface of the substrate, then performing telescopic adjustment on the height of a support column corresponding to the second angular point, and therefore adjusting the position of the second angular point until an image at the second angular point in the ocular lens becomes clear, and in the telescopic adjustment process, a Z coordinate value M displayed in a display screen is unchanged all the time, and therefore when the image at the second angular point in the ocular lens becomes clear, the second angular point is leveled; then, the objective lens of the industrial microscope is aligned with the indication column corresponding to the third corner point in any three points, after the alignment, the indication column corresponding to the third corner point is rotated to move away the indication column, so that the indication column does not shield the objective lens, the objective lens can be aligned with the third corner point of the top surface of the substrate, then the height of the support column corresponding to the third corner point is subjected to telescopic adjustment, the position of the third corner point is adjusted, until an image at the third corner point in the eyepiece becomes clear, the Z coordinate value M displayed in the display screen is unchanged all the time in the telescopic adjustment process, and therefore when the image at the third corner point in the eyepiece becomes clear, the third corner point is leveled.
  4. 4. The method of claim 3, wherein in the step 4), any one of the three corner points to be leveled is selected first, then the indication column corresponding to the any one corner point is rotated so that the central axis of the indication column and the central axis of the support column corresponding to the any one corner point are overlapped with each other at the axis L, the objective table is moved so that the objective lens of the industrial microscope is aligned with the indication column, then the indication column is rotated so that the indication column is moved away, so that the objective lens is not blocked, thereby the objective lens can be aligned with the any one corner point, and then the focusing adjustment is performed until the image at the any one corner point in the eyepiece becomes clear, at this time, the value Z1 of the Z coordinate displayed in the display screen.
  5. 5. The method of claim 4, wherein the focusing adjustment of the remaining corner points not leveled in the step 5) is performed by moving the stage so that the objective lens of the industrial microscope is aligned with the indication column corresponding to the remaining corner points, and then rotating the indication column to move the indication column away so that the indication column does not block the objective lens, thereby enabling the objective lens to be aligned with the remaining corner points, and focusing adjustment is performed until the image at the remaining corner points in the eyepiece becomes clear, wherein the Z coordinate value Z2 displayed in the display screen is displayed.
  6. 6. The chip warpage test fixture is characterized by comprising a bottom plate, wherein four support columns are arranged on the bottom plate; the support column comprises an outer sleeve fixedly arranged on the bottom plate and a support column body arranged in the inner cavity of the outer sleeve, wherein the top of the support column body is provided with a spherical top, the peripheral surface of the inner cavity of the outer sleeve is provided with an internal thread, the peripheral surface of the support column body is provided with an external thread, and the support column body is in threaded connection with the inner cavity of the outer sleeve through the matching of the internal thread and the external thread, so that the support column body can move up and down only by rotating the support column body when the support column body is adjusted; The upper position of each support column is provided with an indication column, the lateral peripheral surface of the indication column is connected with one end of a rotating rod, the other end of the rotating rod is rotationally connected with the other end of the vertical connecting rod, so that the indication column is rotationally connected to the upper position of the support column, a limiting block is further arranged on the horizontal connecting rod, and when the indication column rotates to be in contact with the limiting block, the central axis of the support column and the central axis of the indication column coincide with each other on the axis L.
  7. 7. The chip warpage test fixture of claim 6, wherein the support posts are fixedly arranged on the bottom plate.
  8. 8. The chip warpage test fixture according to claim 6, wherein the support columns are movably connected to the bottom plate, namely four support modules are further arranged on the bottom plate, each support module comprises a die bottom plate arranged on the bottom plate, a first sliding plate arranged on the die bottom plate and a second sliding plate arranged on the first sliding plate, and each support column is fixedly arranged on the second sliding plate of one support module; The first sliding plate is connected to the first die bottom plate in a sliding way through a guide rail and a first sliding block mechanism, a first screw-nut transmission mechanism is further arranged between the first sliding plate and the first die bottom plate, so that the first sliding plate can be driven to move back and forth along the X-axis direction through the first screw-nut transmission mechanism, the second sliding plate is connected to the first sliding plate in a sliding way through a guide rail and a second sliding block mechanism, and a second screw-nut transmission mechanism is further arranged between the second sliding plate and the first sliding plate, so that the second sliding plate can be driven to move back and forth along the Y-axis direction through the second screw-nut transmission mechanism.
  9. 9. The chip warpage test fixture of claim 6, wherein the support columns are movably connected to the bottom plate, namely, the support columns are magnetic columns, the bottom plate is made of a material capable of being adsorbed by the magnetic columns, and the support columns are adsorbed and connected to the bottom plate.

Description

Method for testing chip warpage by using industrial microscope and chip warpage testing tool Technical Field The invention relates to a method and a test fixture for testing chip warpage, in particular to a method and a chip warpage test fixture for testing chip warpage by using an industrial microscope, and belongs to the technical field of chip warpage testing. Background After the FCBGA product is packaged, due to mismatch of thermal expansion coefficients among packaging materials, warpage of different degrees can be generated after the FCBGA product is subjected to temperature rise and fall of a packaging process. The magnitude and shape of warpage of FCBGA products are closely related to package structure, package dimensions, package materials, etc., such as material Coefficient of Thermal Expansion (CTE) mismatch, multi-step thermal cycling during the manufacturing process exacerbates stress build-up, asymmetric layout and dimensional effects in structural design, dual nature of stress relief in curing and post-processing, etc. In summary, FCBGA product package warpage is a result of material, process, design, and manufacturing imperfections acting together. The excessive warpage of the FCBGA product may cause problems of firstly, packaging reliability problems such as solder joint failure, layering cracking, air tightness damage and the like, secondly, electrical property influences such as signal transmission problems and circuit performance changes, thirdly, manufacturing process problems such as increased assembly and test difficulty, reduced production qualification rate and the like. Therefore, after the FCBGA product is packaged, a warpage test is required to ensure that the warpage of the FCBGA product is controlled within a standard value, so that the quality of the shipped FCBGA product is ensured. The FCBGA product has complex shape after being packaged, has forward (concave) warpage such as laugh face shape, reverse (convex) warpage such as crying face shape, and more complex shape, has concave and convex characteristics, and approximately presents asymmetric deformation such as W shape or M shape, and the warpage deformation is irregular symmetric deformation. One existing warp measurement method is to measure using an industrial three-coordinate microscope, such as the Olympic STM 7 industrial microscope. As shown in fig. 1 and 2, the FCBGA product includes a substrate 1 and an inverted chip (not shown) bonded to one side of the substrate 1, one side of the substrate 1 to which the inverted chip is bonded is set as a bottom surface of the substrate 1, the opposite other side of the substrate 1 to which the inverted chip is not bonded is set as a top surface S of the substrate 1, and the FCBGA product is placed on a stage 2 of an industrial microscope at the time of measurement, with the side of the substrate 1 to which the inverted chip is bonded facing downward, and the other side of the substrate 1 to which the inverted chip is not bonded facing upward, i.e., the top surface S of the substrate 1 faces upward, so that an objective lens 3 of the industrial microscope faces the top surface S of the substrate 1. After the placement, the objective table 2 is moved to align the objective lens 3 of the industrial microscope with the geometric center point P of the substrate 1, then focusing adjustment is performed to make the image of the geometric center point P in the eyepiece clear, at this time, the Z coordinate (i.e., vertical coordinate) displayed in the display screen displays a certain value, and when the image of the geometric center point P becomes clear, the focusing adjustment is stopped to perform the zeroing operation, at this time, the position of the geometric center point P is set as the zero position. Next, the stage 2 is moved again so that the objective 3 of the industrial microscope is aligned with the corner a at one corner position of the substrate 1, then focus adjustment is performed so that the corner a point image in the lens becomes clear, at this time, focus adjustment is stopped, the Z coordinate displayed in the display screen shows a certain value, that is, the value of the corner a on the Z axis with respect to the zero position, and then the value is recorded, next, the stage 2 is moved again so that the objective 3 of the industrial microscope is aligned with the corner B at the other corner position of the substrate 1, and the same operation as before is performed, thereby obtaining the value of the corner B on the Z axis with respect to the zero position, next, the operations are repeated so that the values of the corner C and the corner D on the Z axis with respect to the zero position are respectively obtained, and the corner a, the corner B, the corner C and the corner D are respectively taken at the four corner positions of the substrate 1. After the operation is finished, four values of the corner A, the corner B, the corner C and the corner D on the