An online detection device for metal solder tab warping and a detection method thereof

Abstract

The present application belongs to the technical field of warping optical detection, and relates to a metal solder lug warping online detection device and a detection method thereof. The metal solder lug warping online detection device comprises a light source, a collimating optical element, a patterned light modulation element, a light splitting element, an imaging assembly and a processor. Through the cooperative use of various elements, rapid online screening of metal solder lug warping is realized, the minimum curvature that can be sensitively identified is as low as 0.5 mm, and it does not need to set an independent reference grating near the surface of the metal solder lug to be detected. Compared with an interference type or a stripe type optical measurement system, the metal solder lug warping online detection device has a simpler structure and is easy to integrate.

Description

Technical Field

[0001] This invention relates to the field of warpage optical inspection technology, and in particular to an online inspection device and method for metal solder pad warpage, especially an online inspection device and method for metal solder pad warpage in semiconductor packaging. Background Technology

[0002] In the semiconductor packaging field, solder preforms are widely used for interconnects between chips and substrates, heat sinks, or interposers. As packaging technology advances towards higher density, thinner profiles, and 3D integration, indium-based preforms, due to their excellent ductility and thermal conductivity, are often used for thermal interface material connections, while tin-based preforms are widely used for cover sealing and auxiliary interconnects. These thin metal preforms require multiple processes during manufacturing, including rolling, punching, annealing, electroplating, slitting, and heat treatment. However, these plastic deformation and heat treatment processes can easily introduce uneven residual stresses within the preform, causing warping or overall bending after the mechanical constraints are released.

[0003] Then, warped or excessively bent solder preforms can cause a series of quality problems in subsequent semiconductor packaging manufacturing processes, such as pick-up failures, mold tilting, poor thermal contact, assembly position misalignment, or decreased yield. Therefore, conducting 100% online screening of the flatness or warpage of solder preforms before they enter downstream packaging processes is of great value in ensuring packaging yield and product reliability.

[0004] Currently, existing warp measurement techniques, including interferometric or fringe-based optical systems, can perform high-resolution quantitative measurements, but require reference gratings, phase shift mechanisms, precise optical alignment, and complex fringe analysis. These systems are typically expensive and not suitable for high-speed online screening and inspection of discrete solder preforms.

[0005] Chinese invention patent application CN113013050A discloses a wafer warpage measurement device and method. The device adopts a complex hardware architecture including a heating chamber, a heating controller, a temperature detector, multiple sets of reflectors and a protective gas supply system. It has drawbacks such as complex system structure, high hardware cost, and lengthy detection process, and cannot achieve high-speed online detection.

[0006] Chinese invention patent application CN119786369A discloses a wafer warpage detection device, processing equipment, method, and storage medium. The method uses a multi-path interference optical system consisting of a monochromatic light source, at least three half-reflective lenses, at least three mirrors, at least three optical fibers, at least three detectors, and a processor. It has drawbacks such as complex optical system structure and high assembly and maintenance costs. Moreover, the interference measurement principle is sensitive to vibration and airflow, which can easily cause defects such as fringe jitter, counting errors, or phase jumps.

[0007] Therefore, there is an urgent need in this field to develop a simple, low-cost, and fast-response online optical inspection device and method for metal solder pad warpage, which can quickly screen out excessively warped defective metal solder pads while maintaining sufficient optical sensitivity to detect small angle slope changes, thereby improving the efficiency of subsequent semiconductor packaging manufacturing. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides an online detection device and method for metal solder sheet warpage. This not only solves the problem that existing detection systems are typically expensive and unsuitable for online high-speed screening and detection of discrete solder preforms, but also enables sensitive identification of small curvature changes, thereby improving detection efficiency.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides an online detection device for metal solder sheet warpage, the online detection device for metal solder sheet warpage including a light source;

[0011] Collimating optical elements are used to collimate the light beam from the light source.

[0012] A patterned light modulation element is used to modulate the collimated light beam processed by the collimating optical element into collimated patterned structured light;

[0013] An optical beam splitter is used to redirect the collimated patterned structured light to the surface of the metal sheet under test, and to guide the collimated patterned structured light reflected from the surface of the metal sheet under test to the imaging component.

[0014] An imaging component is used to image the collimated patterned structured light reflected from the surface of the metal sheet under test and to communicate the imaging pattern to the processor;

[0015] The processor, which is communicatively connected to the imaging component, is used to analyze the distortion index of the imaging pattern to determine whether the warping of the metal sheet under test is qualified.

[0016] The online detection device for metal weld sheet warpage described in this invention employs collimating optical elements, patterned light modulation elements, light beam splitting elements, imaging elements, and a processor in synergy to achieve rapid online screening of metal weld sheet warpage. Because it uses collimated light, the angular deflection caused by changes in surface slope leads to spatial displacement and other distortions in the imaging pattern of the reflected collimated patterned structured light, thereby improving the sensitivity to small curvature changes and enhancing the detection capability for absorption and assembly risks caused by weld sheet curvature. Furthermore, it eliminates the need for an independent reference grating near the surface of the metal weld sheet under test. Compared to interferometric or fringe-type optical metrology systems, the online detection device for metal weld sheet warpage described in this invention has a simpler structure and is easier to integrate.

[0017] The metal sheet to be tested in this invention is a radial metal sheet, that is, its surface has high light reflectivity and can be used as a reflective surface in optical detection.

[0018] Preferably, the collimating optical element includes an aperture-type collimating element or a wavefront-controlled collimating element.

[0019] Preferably, the aperture-type collimating element includes any one of an aperture stop, a pinhole, or an aperture array.

[0020] Preferably, the wavefront-controlled collimating element includes any one of a collimating lens, a Fresnel collimator, a microlens array, or a reflective collimating mirror.

[0021] Preferably, the patterned light modulation element includes a grating film.

[0022] Preferably, the pitch of the grating film is 0.1~2mm, for example, it can be 0.1mm, 0.3mm, 0.5mm, 0.8mm, 1.0mm, 1.2mm, 1.5mm, 1.8mm or 2mm.

[0023] The patterned light modulation element described in this invention can also be any one of a transparent film printed with opaque grid lines, a patterned glass plate, an etched substrate, or a replaceable insert component.

[0024] Preferably, the optical beam splitter is tilted relative to the direction of the light beam, and the tilt angle α is 40~50°, for example, it can be 40°, 42°, 45°, 48° or 50°.

[0025] It is worth noting that the optical beam splitter in this invention is tilted relative to the direction of the beam, and the tilt angle α is preferably 45°, which is beneficial to forming the optimal optical path geometry. If 40°≤tilt angle α<45°, the lateral space of the device needs to be increased, and attention should be paid to polarization loss. If 45°<tilt angle α≤50°, the longitudinal height needs to be increased to correct for aberrations. If the tilt angle α<35° or the tilt angle α>55°, aberrations, losses and structural problems are difficult to compensate for.

[0026] Preferably, the imaging component is arranged perpendicular to the direction of the light beam.

[0027] In this invention, the imaging component is disposed on the upper side of the optical beam splitter, and the metal sheet to be tested is placed on the bottom of the optical beam splitter and is on the same center line as the imaging component.

[0028] Preferably, the online detection device for metal sheet warpage further includes a light homogenization element disposed between the light source and the collimating optical element.

[0029] Preferably, the light homogenizing element is used to spatially homogenize the light beam from the light source and maintain the angular collimation of the light beam within a preset range.

[0030] Preferably, the light homogenizing element includes any one of a diffuser plate, a light guide plate, a light mixing cavity, or an integrating element.

[0031] Preferably, the processor internally stores the target pattern for comparison and analysis with the imaging pattern obtained by the imaging component to obtain a distortion index.

[0032] Secondly, the present invention provides an online detection method for metal solder sheet warpage, wherein the online detection method for metal solder sheet warpage employs the online detection device for metal solder sheet warpage described in the first aspect.

[0033] The online detection method for metal solder sheet warpage described in this invention uses the aforementioned online detection device for metal solder sheet warpage, eliminating the need to calculate the absolute surface height, thus enabling rapid online screening of discrete metal solder sheets in a high-throughput manufacturing environment.

[0034] Preferably, the online detection method for metal solder sheet warpage includes the following steps:

[0035] When the light source is turned on, the light beam passes sequentially through a collimating optical element and a patterned light modulation element to form a collimated patterned structured light. Then, the collimated patterned structured light is redirected by a beam splitter to the surface of the metal sheet under test for reflection. The reflected collimated patterned structured light is then guided by a beam splitter to an imaging component for imaging. The resulting imaging pattern is analyzed by a processor to obtain a distortion index. Finally, the distortion index is used to determine whether the warping of the metal sheet under test is acceptable.

[0036] Preferably, the distortion index includes any one or a combination of at least two of geometric displacement, line curvature, or frequency offset, wherein typical but non-limiting combinations include combinations of geometric displacement and line curvature, combinations of line curvature and frequency offset, or combinations of geometric displacement and frequency offset, etc.

[0037] In this invention, when the surface of the metal sheet under test is basically flat, the imaging pattern formed by the collimated patterned structured light reflected from it is basically uniform and geometrically consistent. However, when the surface of the metal sheet under test has curvature or warping, the imaging pattern formed by the collimated patterned structured light reflected from it will undergo changes such as spatial displacement or geometric distortion according to the local surface slope. The processor compares and analyzes these changes to determine whether the warping of the metal sheet is acceptable.

[0038] Preferably, the metal sheet to be tested includes an indium-based sheet, a tin-based sheet, or an alloy-type thermally conductive interface sheet.

[0039] Preferably, the thickness of the metal sheet to be tested is <2mm, for example, it can be 1.8mm, 1.6mm, 1.4mm, 1.2mm or 1.0mm, etc.

[0040] Compared with the prior art, the present invention has at least the following beneficial effects:

[0041] The online detection device and method for metal solder sheet warpage provided by this invention achieves rapid online screening of metal solder sheet warpage by using collimating optical elements, patterned light modulation elements, light beam splitting elements, imaging elements and processor in a coordinated manner, and by rationally designing the layout of each element. The minimum curvature that can be sensitively identified is as low as 0.5 mm. Moreover, the detection device has a simple structure, low cost and is easy to integrate. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the structural layout of the online detection device for metal weld sheet warpage provided in Embodiment 1 of the present invention.

[0043] Figure 2 It is the pattern of collimated patterned structured light reflected from the surface of the indium-based solder sheet to be tested as described in Embodiment 1 of the present invention.

[0044] Figure 3 It is the pattern of collimated patterned structured light reflected from the surface of the tin-based solder sheet to be tested as described in Embodiment 2 of the present invention.

[0045] In the figure: 1. Light source; 2. Collimating optical element; 3. Patterned light modulation element; 4. Light beam splitter; 5. Imaging assembly; 6. Processor; 7. Light homogenizing element; 8. Indium-based solder sheet under test. Detailed Implementation

[0046] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0047] In the following embodiments, the light homogenization element can maintain the angular collimation of the light beam within a preset range, i.e., within 10°.

[0048] I. Implementation Examples

[0049] Example 1

[0050] This embodiment provides an online detection device for metal solder sheet warpage, such as... Figure 1 As shown, the online detection device for metal weld sheet warpage includes a light source 1;

[0051] Collimating optical element 2 is used to collimate the light beam of the light source 1;

[0052] The light homogenizing element 7 is disposed between the light source 1 and the collimating optical element 2, and is used to spatially homogenize the light beam of the light source 1 and keep the angular collimation of the light beam within a preset range.

[0053] The patterned light modulation element 3 is used to modulate the collimated light beam processed by the collimating optical element 2 into collimated patterned structured light.

[0054] The optical beam splitter 4 is used to redirect the collimated patterned structured light to the surface of the indium-based solder sheet 8 (1.8 mm thick) under test, and to guide the collimated patterned structured light reflected from the surface of the indium-based solder sheet 8 under test to the imaging component 5.

[0055] Imaging component 5 is used to image the collimated patterned structured light reflected from the surface of the indium-based solder sheet 8 under test and to communicate the imaging pattern to the processor 6;

[0056] The processor 6 is communicatively connected to the imaging component 5 and is used to analyze the distortion index of the imaging pattern to determine whether the warping of the indium-based solder sheet 8 under test is qualified.

[0057] The collimating optical element 2 is a collimating lens; the patterned light modulation element 3 is a grating film with a pitch of 1 mm; the light beam splitting element 4 is tilted relative to the beam direction with an tilt angle α of 45°; the imaging component 5 is perpendicular to the beam direction; the light homogenizing element 7 is an integrating element; the processor 6 internally stores the target pattern for comparison and analysis with the imaging pattern obtained by the imaging component 5 to obtain distortion index.

[0058] This embodiment also provides an online detection method for metal solder sheet warpage. The detection method uses the online detection device described in this embodiment and includes the following steps:

[0059] When light source 1 is turned on, the light beam passes sequentially through collimating optical element 2, light homogenizing element 7, and patterned light modulation element 3 to form collimated patterned structured light. Then, the collimated patterned structured light is redirected by light beam splitter 4 to the surface of the indium-based solder sheet 8 to be tested for reflection. The reflected collimated patterned structured light is then guided by light beam splitter 4 to the imaging component 5 for imaging. The resulting imaging pattern is analyzed by processor 6 to obtain the line curvature, and compared with the preset line curvature to determine whether the warping of the indium-based solder sheet 8 to be tested is qualified.

[0060] The warpage of the indium-based solder sheet 8 to be tested in this embodiment is qualified, such as... Figure 2 As shown, the pattern of the collimated patterned structured light reflected by the structured light is almost distortion-free.

[0061] Example 2

[0062] This embodiment provides an online detection device for metal solder sheet warpage, the online detection device for metal solder sheet warpage includes a light source;

[0063] Collimating optical elements are used to collimate the light beam from the light source.

[0064] A patterned light modulation element is used to modulate the collimated light beam processed by the collimating optical element into collimated patterned structured light;

[0065] An optical beam splitter is used to redirect the collimated patterned structured light to the surface of the tin-based solder sheet under test (thickness is 1.2 mm), and guide the collimated patterned structured light reflected from the surface of the tin-based solder sheet under test to the imaging component;

[0066] An imaging component is used to image the collimated patterned structured light reflected from the surface of the tin-based solder sheet under test and to communicate the imaging pattern to the processor.

[0067] The processor is communicatively connected to the imaging component and is used to analyze the distortion index of the imaging pattern to determine whether the warpage of the tin-based solder sheet under test is qualified.

[0068] The collimating optical element is a Fresnel collimator, the patterned light modulation element is a grating film with a pitch of 0.1 mm; the beam splitter is tilted relative to the beam direction with an tilt angle α of 45°; the imaging assembly is perpendicular to the beam direction; the light homogenizing element is a light guide; the processor stores the target pattern for comparison and analysis with the imaging pattern obtained by the imaging assembly to obtain distortion indices.

[0069] This embodiment also provides an online detection method for metal solder sheet warpage. The detection method uses the online detection device described in this embodiment and includes the following steps:

[0070] When the light source is turned on, the light beam passes sequentially through a collimating optical element and a patterned light modulation element to form a collimated patterned structured light. The collimated patterned structured light is then redirected by a beam splitter to the surface of the tin-based solder sheet under test for reflection. The reflected collimated patterned structured light is then guided by a beam splitter to an imaging component for imaging. The resulting imaging pattern is analyzed by a processor to obtain the frequency shift, and finally compared with a preset frequency to determine whether the warpage of the tin-based solder sheet under test is acceptable.

[0071] The warpage of the tin-based solder sheet to be tested in this embodiment is unqualified, such as... Figure 3 As shown, it exhibits severe distortion.

[0072] Example 3

[0073] This embodiment provides an online detection device for metal solder sheet warpage, the online detection device for metal solder sheet warpage includes a light source;

[0074] Collimating optical elements are used to collimate the light beam from the light source.

[0075] A light homogenizing element is disposed between the light source and the collimating optical element to spatially homogenize the light beam from the light source and maintain the angular collimation of the light beam within a preset range.

[0076] A patterned light modulation element is used to modulate the collimated light beam processed by the collimating optical element into collimated patterned structured light;

[0077] An optical beam splitter is used to redirect the collimated patterned structured light to the surface of the indium-based solder sheet under test (1.5 mm thick), and to guide the collimated patterned structured light reflected from the surface of the indium-based solder sheet under test to the imaging component.

[0078] An imaging component is used to image the collimated patterned structured light reflected from the surface of the indium-based solder sheet under test and to communicate the imaging pattern to the processor.

[0079] The processor is communicatively connected to the imaging component and is used to analyze the distortion index of the imaging pattern to determine whether the warping of the indium-based solder sheet under test is qualified.

[0080] The collimating optical element is a collimating lens, the patterned light modulation element is a grating film with a pitch of 2 mm; the light beam splitting element is tilted relative to the beam direction with an tilt angle α of 45°; the imaging component is perpendicular to the beam direction; the light homogenizing element is an integrating element; the processor stores the target pattern for comparison and analysis with the imaging pattern obtained by the imaging component to obtain distortion index.

[0081] This embodiment also provides an online detection method for metal solder sheet warpage. The detection method uses the online detection device described in this embodiment and includes the following steps:

[0082] When the light source is turned on, the light beam passes sequentially through a collimating optical element, a light homogenizing element, and a patterned light modulation element to form a collimated patterned structured light. The collimated patterned structured light is then redirected by a light beam splitter to the surface of the indium-based solder sheet under test for reflection. The reflected collimated patterned structured light is then guided by a light beam splitter to an imaging component for imaging. The resulting imaging pattern is analyzed by a processor to obtain the line curvature, which is compared with a preset line curvature to determine whether the warpage of the indium-based solder sheet under test is acceptable.

[0083] Example 4

[0084] This embodiment provides an online detection device for metal solder sheet warpage. In the online detection device for metal solder sheet warpage, the optical beam splitter is tilted relative to the direction of the light beam, and the tilt angle α is 35°. All other aspects are the same as in Embodiment 1.

[0085] This embodiment also provides an online detection method for metal solder sheet warpage. Except for the metal solder sheet warpage online detection device described in this embodiment, the method is the same as in Embodiment 1.

[0086] The tilt angle α described in this embodiment is too small, which may cause changes in the optical path geometry, thereby affecting the imaging effect and the processor analysis results.

[0087] Example 5

[0088] This embodiment provides an online detection device for metal solder sheet warpage. In the online detection device for metal solder sheet warpage, the optical beam splitter is tilted relative to the direction of the light beam, and the tilt angle α is 55°. All other aspects are the same as in Embodiment 1.

[0089] This embodiment also provides an online detection method for metal solder sheet warpage. Except for the metal solder sheet warpage online detection device described in this embodiment, the method is the same as in Embodiment 1.

[0090] In this embodiment, the tilt angle α is relatively large, which may require raising the position of the imaging component, thereby increasing the longitudinal space requirement of the device and having a certain impact on the optical path layout and imaging effect.

[0091] II. Comparative Example

[0092] Comparative Example 1

[0093] This comparative example provides an online detection device for metal solder sheet warpage, which is the same as that in Example 1 except that it does not have a collimating optical element.

[0094] This comparative example also provides an online detection method for metal solder sheet warpage, wherein the online detection method for metal solder sheet warpage is performed using the online detection device for metal solder sheet warpage described in this comparative example.

[0095] Because the online detection device for metal solder sheet warpage described in this comparative example does not have a collimating optical element, the light emitted by the light source will not be collimated, which will result in the inability to form an effective patterned structured light. Consequently, the subsequent beam splitting element and imaging optical path will fail, and the received image distortion will include multiple noises such as light source divergence, pattern blurring, and optical path offset. As a result, the processor will not be able to extract distortion information caused solely by the curvature of the indium-based metal solder sheet, leading to unreliable judgment results.

[0096] The online detection device and method for metal weld sheet warpage provided by this invention, by employing collimating optical elements, patterned light modulation elements, light beam splitting elements, imaging elements, and a processor, and by rationally designing their layout, not only achieves rapid online screening of metal weld sheet warpage, but also solves the problem that existing detection systems are unable to sensitively identify small curvature changes. Furthermore, its structure is simple, without complex optical structures, and is easy to integrate, thus solving the problem of high cost of existing detection systems.

[0097] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. An online detection device for warpage of metal weld sheets, characterized in that, The online detection device for metal weld sheet warpage includes a light source; Collimating optical elements are used to collimate the light beam from the light source. A patterned light modulation element is used to modulate the collimated light beam after collimation by the collimating optical element into collimated patterned structured light; the patterned light modulation element includes any one of a grating film, a transparent film printed with opaque grid lines, a patterned glass plate, an etched substrate, or a replaceable insert component. An optical beam splitter is used to redirect the collimated patterned structured light to the surface of the metal sheet under test, and to guide the collimated patterned structured light reflected from the surface of the metal sheet under test to the imaging component. An imaging component is used to image the collimated patterned structured light reflected from the surface of the metal sheet under test and to communicate the imaging pattern to the processor; the surface of the metal sheet under test has high light reflectivity and a thickness of <2mm. The processor internally stores the target pattern and communicates with the imaging component to compare it with the imaging pattern obtained by the imaging component, analyzes the distortion index of the imaging pattern to determine whether the warping of the metal sheet under test is qualified, without calculating the absolute height. The distortion index includes any one or a combination of at least two of geometric displacement, line curvature, or frequency offset.

2. The online detection device for metal weld sheet warpage according to claim 1, characterized in that, The collimating optical element includes an aperture-type collimating element or a wavefront-controlled collimating element; The aperture-type collimating element includes any one of an aperture stop, a pinhole, or an aperture array; The wavefront-controlled collimating element includes any one of a collimating lens, a Fresnel collimator, a microlens array, or a reflective collimating mirror.

3. The online detection device for metal weld sheet warpage according to claim 1, characterized in that, The grating film has a pitch of 0.1~2mm.

4. The online detection device for metal weld sheet warpage according to claim 1, characterized in that, The optical beam splitter is tilted relative to the direction of the beam, and the tilt angle α is 40~50°; The imaging component is positioned perpendicular to the direction of the light beam.

5. The online detection device for metal weld sheet warpage according to claim 1, characterized in that, The online detection device for metal sheet warpage also includes a light homogenization element disposed between the light source and the collimating optical element.

6. The online detection device for metal weld sheet warpage according to claim 5, characterized in that, The light homogenization element includes any one of a diffuser plate, a light guide plate, a light mixing cavity, or an integrating element.

7. A method for online detection of warpage of metal solder sheets, characterized in that, The online detection method for metal weld sheet warpage is performed using the online detection device for metal weld sheet warpage as described in any one of claims 1 to 6.

8. The online detection method for warpage of metal weld sheets according to claim 7, characterized in that, The online detection method for metal solder sheet warpage includes the following steps: When the light source is turned on, the light beam passes sequentially through a collimating optical element and a patterned light modulation element to form a collimated patterned structured light. This collimated patterned structured light is then redirected by a beam splitter to the surface of the metal sheet under test for reflection. The reflected collimated patterned structured light is then guided by a beam splitter to an imaging assembly for imaging. The resulting image pattern is analyzed by a processor to obtain distortion indices. Finally, based on these distortion indices, it is determined whether the warpage of the metal sheet under test is acceptable, without needing to calculate the absolute height. The distortion indices include any one or a combination of at least two of geometric displacement, line curvature, or frequency shift. The surface of the metal sheet to be tested has high light reflectivity and a thickness of <2mm.

9. The online detection method for metal weld sheet warpage according to claim 8, characterized in that, The metal sheet to be tested includes indium-based sheet, tin-based sheet, or alloy-type thermally conductive interface sheet.

Images