Laser heating system and method for flip chip welding and repair

Abstract

The present invention discloses a laser heating system and method for flip-chip welding and repair, belonging to the technical field of electronic components. The system includes: a solder paste adjustment module, a chip welding module, and a welding repair module; a solder paste abnormality assessment is performed on the solder pad after solder paste printing based on solder paste quality parameters, and based on the obtained solder paste abnormality assessment results, it is determined whether to perform dynamic printing adjustment; after flip-chip bonding, it is determined whether to perform dynamic bonding compensation based on the bonding offset and rotational deviation between the flip-chip and the solder pad; after flip-chip bonding using a flip-chip welding device, the flip-chip welding effect is quantitatively evaluated based on welding accuracy parameters, and based on the quantitative evaluation results, it is determined whether to use the flip-chip welding device to repair the flip-chip. This system achieves precise control of temperature and heat distribution during the welding process through laser heating, thereby improving the quality of flip-chip bonding and repair.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic components, and in particular to a laser heating system and method for flip chip welding and repair. Background Art

[0002] Existing flip-chip soldering mostly uses a process of applying solder paste and then heating it in a reflow oven. The substrate pads and the openings of the stencil are precisely aligned by stencil printing. The solder paste is piled flat on the top of the stencil. The thixotropy of the solder paste allows it to temporarily maintain its shape in the stencil openings and prevent it from dripping naturally due to gravity. A scraper is used to press over the solder paste. Under the pressure of the scraper, the solder paste becomes thinner and flows into the stencil openings. The solder paste remains on the substrate pads due to adhesion. The stencil needs to be separated vertically upward from the substrate at a separation speed to allow the solder paste to separate from the stencil openings and remain on the pads. , forming uniform solder paste dots, and then the bumps of the flip chip are aligned with the solder paste dots to form components. The components are heated by the reflow oven, and the temperature is slowly increased during the preheating stage to avoid thermal shock. The solder paste begins to melt in the constant temperature stage, and the solder in the solder paste begins to flow, ready for welding. In the reflow stage, the solder paste completely melts to form a liquid molten pool, and the bumps of the solder joints (that is, the solder balls on the chip) and the solder paste on the pads come into contact, forming a liquid welding interface. During the cooling stage, the temperature gradually decreases, and the liquid molten pool will quickly cool and solidify, and the solder forms a solder joint.

[0003] Although reflow soldering is a mature soldering process, it is unsuitable for rapid, small-batch production due to its large footprint, high energy consumption, and long preheating times. This is particularly problematic for temperature-sensitive components. Products requiring localized heating and soldering currently require manual repair, resulting in low efficiency and yield rates. For example, in LED (Light Emitting Diode) production, after chip assembly, reflow soldering is required to heat and melt the tin to solidify the chip. However, reflow soldering is very costly for small-batch production due to the long preheating time and high costs associated with initiating reflow soldering.

[0004] For example, the invention patent announcement with announcement number CN108288591B discloses a flip chip and its welding method, which includes: providing a chip with metal bumps, which can generate an induced current under the action of an alternating magnetic field; flipping the chip onto a substrate; placing the mounted chip and substrate in an alternating magnetic field to generate an induced current in the metal bumps, and utilizing the thermal effect of the induced current to melt the metal bumps to form a weld.

[0005] For example, the invention patent announcement with announcement number: CN116799110B discloses a method for removing and repairing Mini LED chips, which includes: placing the chip so that the chip substrate is located at the upper end of the chip substrate, bombarding the chip substrate with a high-energy pulse laser, and then generating a shock wave through the high-temperature plasma generated only by the action of the laser pulse and the substrate surface material, causing the Mini LED chip to break at the welding position under the action of the shock wave oscillation, fall off the chip substrate, and be instantly detached and ejected. The method includes the steps of emitting a high-energy pulse laser, attenuating the high-energy pulse laser, adjusting the laser beam to a rectangular spot or a linear spot with the same inclination as the chip substrate, focusing the laser, and imaging the laser.

[0006] The above technology has at least the following technical problems:

[0007] In the existing technology, during the welding process, due to the extremely high chip welding precision requirements, when the chip size is too small, the chip position may deviate from the center of the solder paste point, resulting in insufficient solder joint contact area, thereby affecting the welding quality. In the process of repairing solder joints with poor welding effect due to the small chip size, the existing technology uses a reflow soldering station to remove abnormal chips and weld replacement chips. Since manual operation tools are difficult to accurately position and repair, it is easy to cause alignment deviation or uneven thermal stress, which affects the quality of the repaired solder joints and there is a problem of poor flip chip repair effect. Summary of the Invention

[0008] The present invention provides a laser heating system and method for flip-chip welding and repair, thereby solving the problem in the prior art that, during the welding process, due to extremely high chip welding precision requirements, the chip position may deviate from the center of the solder paste point when the chip size is too small, resulting in insufficient solder joint contact area, thereby affecting the welding quality. At the same time, in the process of repairing solder joints with poor welding effect due to the small chip size, the prior art uses a reflow soldering station to remove abnormal chips and weld replacement chips. Since manual operation tools are difficult to accurately position and repair, it is easy to cause alignment deviation or uneven thermal stress, thereby affecting the quality of the repaired solder joints and resulting in poor flip-chip repair effect. The problem is achieved by improving the quality of flip-chip welding and repair.

[0009] The present invention provides a laser heating system for flip-chip welding and repair, comprising: a solder paste adjustment module, a chip welding module, a welding repair module and a chip welding database; wherein the solder paste adjustment module is used to perform solder paste abnormality evaluation on the solder pad after solder paste printing according to solder paste quality parameters, and judge whether to perform dynamic printing adjustment based on the obtained solder paste abnormality evaluation result; the chip welding module is used to judge whether to perform dynamic bonding compensation according to the bonding offset and rotation deviation between the flip chip and the solder pad after the flip-chip is bonded; the welding repair module uses a temperature probe, a temperature controller and a laser to perform flip-chip welding, and after the flip-chip is welded, performs quantitative evaluation of the flip-chip welding effect according to the welding accuracy parameters, and judges whether to use the temperature probe, the temperature controller and the laser to repair the flip-chip based on the quantitative evaluation result.

[0010] The present invention also provides a laser heating method for flip chip welding and repair, which performs solder paste abnormality evaluation on the solder pad after solder paste printing according to solder paste quality parameters, and judges whether to perform dynamic printing adjustment based on the obtained solder paste abnormality evaluation result; judges whether to perform dynamic bonding compensation according to the bonding offset and rotation deviation between the flip chip and the solder pad after the flip chip is bonded; uses a temperature probe, a temperature controller and a laser to perform flip chip welding, and after the flip chip is welded, performs a quantitative evaluation of the flip chip welding effect according to the welding accuracy parameters, and judges whether to use the temperature probe, the temperature controller and the laser to perform flip chip repair based on the quantitative evaluation result.

[0011] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages:

[0012] 1. The present invention performs solder paste abnormality evaluation on the solder pad after solder paste printing according to the solder paste quality parameters, which can effectively identify the printing quality of the solder paste during the printing process, and dynamically adjusts the scraper pressure and demoulding speed during the solder paste printing process based on the solder paste abnormality evaluation result, which can directly control the printing effect of the solder paste, ensure the uniformity of the solder paste thickness distribution, and avoid the influence of poor printing quality on the welding quality; then, the flip chip position and angle are optimized based on the fitting offset and rotation deviation of the flip chip and the solder pad, thereby improving the mounting accuracy of the flip chip and the solder pad, and reducing the welding defects caused by the mounting position error; finally, the flip chip welding effect is quantitatively evaluated by the welding accuracy parameters, the welding quality of the flip chip can be accurately judged, and repair is performed based on the quantitative evaluation result, so that the welding defects can be discovered and corrected in time, and the flip chip welding and flip chip repair are completed by using the flip chip welding device, which realizes the precise control of the temperature and heat distribution in the welding process by the laser heating method, and improves the reliability and quality of the flip chip welding and repair.

[0013] 2. The present invention obtains a solder paste abnormality quantitative index based on a comprehensive analysis of solder paste quality parameters, which can provide a quantitative evaluation of solder paste quality, and judge whether to perform dynamic printing adjustment based on the solder paste abnormality quantitative index. It can quickly detect excess or insufficient solder paste, and dynamically adjust the scraper pressure according to the solder paste abnormality quantitative index, which can directly control the printing amount of solder paste, avoid welding defects and poor welding caused by excessive solder paste, and ensure the accuracy and uniformity of the solder paste amount; when the solder paste volume is within the standard range, the system improves the uniform distribution and demolding effect of the solder paste by dynamically adjusting the demolding speed, ensures the stable release of the solder paste on the pad, improves the printing quality, and avoids poor contact caused by uneven solder paste during the flip-chip bonding process.

[0014] 3. The present invention can timely detect the deviation between the chip and the pad by real-time monitoring of the fitting offset and rotational deviation, and perform dynamic compensation based on the deviation. When the fitting offset exceeds the corresponding threshold, the system will automatically adjust the chip position to ensure the precise docking of the chip and the pad; when the rotational deviation exceeds the corresponding threshold, the system will dynamically adjust the compensation angle to avoid poor contact or welding defects caused by rotational deviation, which can effectively ensure the precise docking of the chip and the pad, thereby improving the quality and stability of welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic structural diagram of a laser heating system for flip chip welding and repair provided in an embodiment of the present application.

[0016] Figure 2 This is a flow chart of the flip chip welding device provided in an embodiment of the present application.

[0017] Figure 3 This is a diagram of the laser light path combination provided in an embodiment of the present application, in which 1 is a laser, 2 is a collimating lens, 3 is a microlens array, 4 is a focusing lens, 5 is a flip chip and a pad, 6 is a CCD camera, and 7 is a temperature probe.

[0018] Figure 4 This is a structural diagram of the unidirectional uniform spot changing system provided in an embodiment of the present application. In the figure, 8 is a collimating lens, 9 and 10 are two cylindrical microlenses, and 11 and 12 are two focusing lenses.

[0019] Figure 5 This is a uniform spot diagram of the unidirectional uniform variable spot system provided in an embodiment of the present application.

[0020] Figure 6 This is a spot change diagram of the unidirectional uniform spot change system provided in an embodiment of the present application.

[0021] Figure 7 This is a schematic diagram of the unidirectional uniform spot variation system provided in an embodiment of the present application.

[0022] Figure 8 This is a structural diagram of the laser heating head provided in an embodiment of the present application, in which 13 is a collimating lens, 14 is a first cylindrical microlens, 15 is a second cylindrical microlens, 16 is a third cylindrical microlens, 17 is a fourth cylindrical microlens, 18 is a first focusing lens, and 19 is a second focusing lens.

[0023] Figure 9 This is a uniform spot diagram of the laser heating head provided in an embodiment of the present application.

[0024] Figure 10 This is a diagram of the laser heating head spot change provided in an embodiment of the present application.

[0025] Figure 11 A printing dynamic adjustment mind map provided in an embodiment of the present application.

[0026] Figure 12 A flow chart of a laser heating method for flip chip welding and repair provided in an embodiment of the present application. DETAILED DESCRIPTION

[0027] The embodiment of the present application provides a laser heating system and method for flip chip welding and repair, which solves the problem in the prior art that, due to the extremely high chip welding precision requirements, the chip position may deviate from the center of the solder paste point when the chip size is too small, resulting in insufficient solder joint contact area, thereby affecting the welding quality. At the same time, in the process of repairing solder joints with poor welding effect caused by too small chip size, the prior art uses a reflow soldering station to remove abnormal chips and weld replacement chips. Since it is difficult for manual operation tools to accurately position and repair, it is easy to cause alignment deviation or uneven thermal stress, thereby affecting the quality of the repaired solder joints and resulting in poor flip chip repair effect. The solder paste abnormality evaluation is performed on the pad after solder paste printing based on the solder paste quality parameters. The abnormal evaluation results determine whether to perform dynamic printing adjustment; after the flip chip is bonded, it is determined whether to perform dynamic bonding compensation based on the bonding offset and rotation deviation between the flip chip and the pad; flip chip welding is performed using a temperature probe, a temperature controller and a laser, and after the flip chip welding, the flip chip welding effect is quantitatively evaluated based on the welding accuracy parameters, and based on the quantitative evaluation results, it is determined whether to use the temperature probe, the temperature controller and the laser to repair the flip chip. The temperature probe is used to detect the temperature of the flip chip and the pad to feed back to the temperature controller. The temperature controller is used to adjust the laser output power in real time through temperature feedback according to the temperature setting requirements to control the heating temperature of the pad during the flip chip welding process, thereby improving the quality of flip chip welding and repair.

[0028] The technical solution in the embodiment of the present application is to solve the above-mentioned problem that, due to the extremely high chip welding precision requirements during the welding process, when the chip size is too small, the chip position may deviate from the center of the solder paste dot, resulting in insufficient solder joint contact area, thereby affecting the welding quality. At the same time, in the process of repairing solder joints with poor welding effect caused by too small chip size, the existing technology uses a reflow soldering station to remove abnormal chips and weld replacement chips. Since manual operation tools are difficult to accurately position and repair, it is easy to cause alignment deviation or uneven thermal stress, thereby affecting the quality of the repaired solder joints and resulting in poor flip chip repair effect. The overall concept is as follows:

[0029] By dynamically evaluating and adjusting solder paste quality parameters, flip chip bonding accuracy, and welding accuracy parameters, the accuracy of flip chip welding and repair quality is ensured. First, solder paste abnormality evaluation is performed based on solder paste quality parameters to determine whether dynamic adjustment of the printing process is required, and to optimize scraper pressure and demolding speed to improve the uniformity of solder paste thickness distribution. Then, during the flip chip bonding process, dynamic bonding compensation is determined based on the bonding offset and rotational deviation between the chip and the pad to ensure precise docking of chip position and angle, thereby improving bonding accuracy. Finally, after welding is completed using the flip chip welding device, the welding effect is evaluated based on the welding accuracy parameters to determine whether flip chip repair is required and further optimize the welding effect. Thus, efficient and high-precision control of temperature and heat distribution is achieved throughout the entire flip chip welding and repair process based on the laser heating method, thereby improving the quality of flip chip welding and repair.

[0030] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0031] like Figure 1The figure is a structural schematic diagram of a laser heating system for flip chip welding and repair provided by an embodiment of the present application. The laser heating system for flip chip welding and repair provided by an embodiment of the present application includes: a solder paste adjustment module, a chip welding module, a welding repair module and a chip welding database; wherein the solder paste adjustment module is used to perform solder paste abnormality evaluation on the solder pad after solder paste printing according to the solder paste quality parameters, and judge whether to perform dynamic printing adjustment based on the obtained solder paste abnormality evaluation result, and the dynamic printing adjustment is used to dynamically set the scraper pressure and demoulding speed during the next solder paste printing process to improve the uniformity of solder paste thickness distribution; the chip welding module is used to dynamically set the scraper pressure and demoulding speed during the next solder paste printing process to improve the uniformity of solder paste thickness distribution; the chip welding module is used to adjust the solder paste according to the bonding condition of the flip chip and the solder pad after the flip chip is bonded. The offset and rotation deviation are combined to determine whether dynamic fitting compensation is performed. Dynamic fitting compensation is used to dynamically adjust the position and angle of the flip chip to improve the placement accuracy of the flip chip; the welding repair module uses a temperature probe, a temperature controller and a laser to perform flip chip welding. After the flip chip is welded, the flip chip welding effect is quantitatively evaluated according to the welding accuracy parameters, and based on the quantitative evaluation results, it is determined whether to use the temperature probe, the temperature controller and the laser to repair the flip chip. The temperature probe is used to detect the temperature of the flip chip and the pad to feed back to the temperature controller. The temperature controller is used to adjust the laser output power in real time through temperature feedback according to the temperature setting requirements to control the heating temperature of the pad during the flip chip welding process.

[0032] In this embodiment, the conventional reflow soldering process for flip-chip soldering is replaced with laser-heated soldering using a flip-chip soldering device. This significantly reduces soldering costs, such as the start-up and preheating time required for reflow soldering, in small-batch production. It also addresses the inability to accurately repair individual chips during rework processes due to poor soldering caused by small chip size. The flip-chip soldering device of the present invention enables contactless processing, directional heating, and CCD camera positioning, making it an optimal choice for selective localized heating soldering. It effectively eliminates the impact of soldering on surrounding products and devices. The present invention also utilizes a CCD camera to monitor the soldering process in real time, ensuring visualization of the soldering process.

[0033] In addition, since the chip welding database stores relevant data of the laser heating system for flip-chip welding and repair, including: reference solder paste thickness, allowable deviation of solder paste thickness, reference solder paste coverage, allowable deviation of solder paste coverage, reference solder paste volume, solder paste abnormality threshold and solder paste standard volume range, the data in the chip welding database can be directly queried through public databases such as the Laser Society database, or obtained through cooperation with relevant departments such as packaging foundries and flip-chip manufacturers.

[0034] like Figure 2As shown, it is a flow chart of the flip chip welding device provided in the embodiment of the present application. Flip chip welding is implemented based on the flip chip welding device, which specifically includes a laser heating head, a laser, a temperature probe, a temperature controller and a CCD camera; the CCD camera is used to monitor the flip chip welding process in real time according to the requirements of the upper computer process files such as PCB design files, covering equipment such as lasers and laser heating heads, and is responsible for locating the position of the flip chip and the pad; the laser heating head is used to adjust the spot size to control the heating area of ​​the flip chip and the pad heating process; the temperature probe is used to detect the temperature of the flip chip and the pad to feed back to the temperature controller; the temperature controller is used to adjust the laser output power in real time through temperature feedback according to the temperature setting requirements of the upper computer process file to control the heating temperature of the pad during the flip chip welding process; the temperature controller, the temperature probe and the laser perform real-time signal transmission and feedback with each other. The temperature controller and the CCD camera are coaxial with the laser optical path, and there can be a variety of combinations according to actual needs, such as Figure 3 As shown in the laser optical path combination diagram, 1 is the laser, 2 is the collimating lens, 3 is the microlens array, 4 is the focusing lens, 5 is the flip chip and pad, 6 is the CCD camera, and 7 is the temperature probe. Among them, the first laser optical path combination is suitable for scenarios that require a long optical path within a limited space, such as some spectral analysis instruments with specific requirements for optical path; the second laser optical path combination is suitable for situations where the laser needs to be focused quickly and efficiently on a specific small area, such as fine processing in laser machining, where the conical structure can be used to concentrate the laser energy on a tiny area on the workpiece; the third laser optical path combination is suitable for scenarios where the laser needs to be guided to a specific direction or position, such as in laser communication, guiding the laser from the transmitting source to a specific receiving device.

[0035] Among them, the laser heating head includes a collimator, a focusing lens group and a microlens group; the collimator is used to reduce the divergence angle of the circular light beam output by the fiber laser; the focusing lens group includes a first focusing lens and a second focusing lens; the microlens group includes a first cylindrical microlens array and a second cylindrical microlens array, the first cylindrical microlens array includes a first cylindrical microlens and a second cylindrical microlens, and the second cylindrical microlens array includes a third cylindrical microlens and a fourth cylindrical microlens; the spacing of the first cylindrical microlens array is used to control the length of the output light spot; the first cylindrical microlens array and the first focusing lens constitute a first group of microlens arrays with a first direction; the spacing of the second cylindrical microlens array is used to control the width of the output light spot; the second cylindrical microlens array and the second focusing lens constitute a second group of microlens arrays with a second direction; the directions of the first group of microlens arrays are orthogonal to the second group of microlens arrays, and the working surfaces of the two groups of microlens arrays coincide, forming an imaging microlens array in orthogonal directions. The laser heating head is a bidirectional uniform spot system with adjustable length and width. It is achieved by adding a reverse unidirectional uniform spot system on the basis of the unidirectional uniform spot system, thereby achieving uniform adjustment of the light spot in both the forward and reverse directions.

[0036] like Figure 4 As shown, it is a structural diagram of a unidirectional uniform spot changing system provided by an embodiment of the present application. In the figure, 8 is a collimating lens, 9 and 10 are two cylindrical microlenses, and 11 and 12 are two focusing lenses. In the figure, 9 and 10 form a group of cylindrical microlens arrays. In the present invention, the cylindrical microlenses are of uniform specifications. 11 and 12 form a focusing lens group. The focusing lens group and the cylindrical microlens array constitute a microlens array in this direction. When the microlens array 9 or 10 moves back and forth along the direction indicated by the arrow, the corresponding uniform spot width can be obtained. In the opposite direction, it is a simple collimating and focusing system, which obtains the same spot distribution as the original light source, and the spot width can be changed by defocusing. Figure 5 and Figure 6 They are the uniform spot diagram of the unidirectional uniform variable spot system and the spot change diagram of the unidirectional uniform variable spot system after changing the spacing of the microlens group.

[0037] like Figure 7 The figure shows the principle diagram of the unidirectional uniform spot system provided by an embodiment of the present application. In the unidirectional uniform spot system, the light beam emitted by the light source forms a light beam with a small divergence angle after passing through the collimating lens. The first microlens array divides the collimated light beam into multiple sub-beams. The second microlens array is combined with the focusing lens to act as a set of objective lenses, superimposing the image of each light beam in the first array on the uniform light plane to form a uniform flat-top beam. The size of the uniform light spot formed after focusing depends on the focal length of the sub-lenses in the array and the focal length of the focusing lens. The diameter of a single light beam on the second microlens array must be smaller than the sub-lens spacing to avoid overfilling of the lens aperture and light loss.

[0038] like Figure 8 As shown, this is a structural diagram of a laser heating head provided by an embodiment of the present application, in which 13 is a collimating lens, 14 is a first cylindrical microlens, 15 is a second cylindrical microlens, 16 is a third cylindrical microlens, 17 is a fourth cylindrical microlens, 18 is a first focusing lens, 19 is a second focusing lens, 18 and 19 form a focusing lens group, 14 and 15 form a first cylindrical microlens array, which together with the focusing lens group constitutes a first group of microlens arrays in the first direction, 16 and 17 form a second cylindrical microlens array, which together with the focusing lens group constitutes a second group of microlens arrays in the second direction, the second group of microlens arrays is orthogonal to the direction of the first group of microlens arrays, and the two groups of microlens arrays constitute an imaging type microlens array in the orthogonal direction. The light spots in both directions of the laser heating head are evenly distributed, and the length and width of the output rectangular light spots can be adjusted separately, and both directions constitute a microlens array homogenization system.

[0039] The uniform spot of the laser heating head is as follows Figure 9 As shown in the figure, the spot size of the rectangular spot heating head is in the range of 0.05-12mm, and the two groups of micro lenses form uniform spots in the corresponding directions, thus forming a rectangular uniform light. When the spacing of one group of micro lenses is changed, the spot length in the corresponding direction changes separately. The laser heating head spot change diagram is shown in the figure below. Figure 10 shown.

[0040] Furthermore, the step of performing solder paste abnormality evaluation on the solder pad after solder paste printing according to the solder paste quality parameters includes: obtaining solder paste quality parameter reference data from a preset chip welding database, specifically including: reference solder paste thickness, solder paste thickness allowable deviation, reference solder paste coverage, solder paste coverage allowable deviation, reference solder paste volume and solder paste volume allowable deviation; based on the reference solder paste thickness and the solder paste thickness, obtaining the actual deviation of the solder paste thickness, and comparing it with the allowable deviation of the solder paste thickness to obtain the solder paste thickness influencing parameter; based on the reference solder paste coverage and the solder paste coverage, obtaining the actual deviation of the solder paste coverage, and comparing it with the allowable deviation of the solder paste coverage to obtain the solder paste coverage. Influencing parameters; based on the reference solder paste volume and the solder paste volume, the actual deviation of the solder paste volume is obtained, and compared with the allowable deviation of the solder paste volume to obtain the solder paste volume influencing parameters; the solder paste quality parameter contribution data is used to perform weighted coupling processing on the solder paste thickness influencing parameters, the solder paste coverage influencing parameters and the solder paste volume influencing parameters to obtain the solder paste anomaly quantitative index; the solder paste anomaly quantitative index represents the quantitative data of the degree of influence of the solder paste quality parameters on the solder paste state on the pad, and the solder paste quality parameters include solder paste thickness, solder paste coverage and solder paste volume; the solder paste quality parameter contribution data includes solder paste thickness contribution, solder paste coverage contribution and solder paste volume contribution.

[0041] The method for obtaining the solder paste abnormality quantitative index is as follows:

[0042] ;

[0043] Where a represents the solder paste anomaly quantitative index, γ1 represents the solder paste thickness contribution, γ2 represents the solder paste coverage contribution, and γ3 represents the solder paste volume contribution.

[0044] t represents the solder paste thickness, which is the average value of the solder paste thickness at each preset measuring point on the solder paste surface. It can be obtained by non-contactly measuring the height difference between each measuring point on the solder paste surface and the pad reference plane using equipment such as a laser displacement sensor. t1 represents the reference solder paste thickness, and t2 represents the allowable deviation of the solder paste thickness.

[0045] c represents the solder paste coverage, which can be obtained by using a CCD camera to capture the pad area, using a binary segmentation algorithm to separate the solder paste and background areas in the pad area image, and calculating the ratio of solder paste pixels to pad area pixels. c1 represents the reference solder paste coverage, and c2 represents the allowable deviation of the solder paste coverage.

[0046] v represents the volume of solder paste, which can be obtained by scanning the solder paste height profile using a volume measuring instrument such as a laser displacement sensor and cumulatively calculating the solder paste height and solder paste pixel area. v1 represents the reference solder paste volume, and v2 represents the allowable deviation of the solder paste volume.

[0047] In the chip soldering database, γ1, γ2, and γ3 represent the contributions of solder paste thickness, solder paste coverage, and solder paste volume, respectively. These contributions quantitatively measure the degree to which these solder paste quality parameters contribute to the lens film's impact index. Specifically, separate mapping tables are configured for solder paste thickness, solder paste coverage, and solder paste volume, each with a one-to-one or many-to-one correspondence. The table records each possible solder paste quality parameter value and its corresponding contribution. In practice, the real-time measured solder paste thickness, solder paste coverage, and solder paste volume are entered into their respective mapping tables to automatically match their corresponding contribution values, with contribution values ​​ranging from 0 to 1.

[0048] In this embodiment, solder paste thickness, solder paste coverage, and solder paste volume are interrelated. For example, when the solder paste thickness is consistent, the greater the solder paste coverage, the greater the solder paste volume. Uneven solder paste height, such as edge collapse, may result in high solder paste coverage but low solder paste volume. Central protrusions, such as printed apex, may result in normal solder paste coverage but excessive solder paste volume. When the solder paste coverage remains constant, the greater the solder paste thickness, the greater the solder paste volume. Excessively thick solder paste tends to spread laterally during reflow, resulting in excessive solder paste coverage, while excessively thin solder paste may result in insufficient solder paste coverage.

[0049] like Figure 11As shown, it is a mind map of dynamic printing adjustment provided by an embodiment of the present application, wherein the quantitative index is the solder paste abnormality quantitative index, the threshold value is the solder paste abnormality threshold value, the maximum value is the maximum value of the solder paste standard volume range, the minimum value is the minimum value of the solder paste standard volume range, and the range is the solder paste standard volume range. The solder paste abnormality quantitative index is obtained based on the printing quality parameters obtained by real-time monitoring, and a judgment is made based on the solder paste abnormality quantitative index and the solder paste abnormality threshold value. If the solder paste abnormality quantitative index is less than or equal to the solder paste abnormality threshold value, a flip chip bonding prompt is issued. If the solder paste abnormality quantitative index is greater than the solder paste abnormality threshold value, a judgment is made based on the solder paste volume. When the solder paste volume is greater than the maximum value of the solder paste standard volume range, an excessive solder paste prompt is issued and the scraper pressure is increased. When the solder paste volume is less than the minimum value of the solder paste standard volume range, an insufficient solder paste prompt is issued and the scraper pressure is reduced. When the solder paste volume is within the solder paste standard volume range, a demoulding abnormality prompt is issued and the demoulding speed is adjusted.

[0050] Specifically, the step of determining whether to perform dynamic printing adjustment based on the obtained solder paste abnormality evaluation result includes:

[0051] The solder paste abnormality threshold and solder paste standard volume range are obtained from the preset chip welding database; the solder paste abnormality quantification index is compared with the solder paste abnormality threshold; if the solder paste abnormality quantification index is greater than the solder paste abnormality threshold and the solder paste volume is greater than the maximum value of the solder paste standard volume range, a solder paste excess prompt is issued, and flip-chip bonding cannot be performed directly; the solder paste abnormality deviation index is matched with the scraper pressure adjustment value corresponding to each solder paste abnormality deviation index range preset in the chip welding database; the scraper pressure in the next solder paste printing process is increased according to the matched scraper pressure adjustment value, which can avoid solder paste overflow and unevenness and reduce solder paste waste. The solder paste abnormality deviation index represents the difference between the solder paste abnormality quantification index and the solder paste abnormality threshold. In the chip welding database, each solder paste abnormal deviation index range and the scraper pressure adjustment value correspond one-to-one to form a mapping relationship table. The table records each solder paste abnormal deviation index range and its corresponding scraper pressure adjustment value. These relationships can be one-to-one or many-to-one. When obtaining the scraper pressure adjustment value, you only need to input the solder paste abnormal deviation index into the mapping relationship table. The chip welding database can quickly locate and return the scraper pressure adjustment value corresponding to the solder paste abnormal deviation index. The same applies to the demolding speed adjustment value.

[0052] If the solder paste abnormality quantitative index is greater than the solder paste abnormality threshold and the solder paste volume is less than the minimum value of the solder paste standard volume range, a solder paste insufficient prompt is issued, and the flip chip bonding cannot be performed directly. According to the scraper pressure adjustment value, the scraper pressure in the next solder paste printing process is reduced to ensure that each pad gets enough solder paste to avoid poor welding; if the solder paste abnormality quantitative index is greater than the solder paste abnormality threshold and the solder paste volume is within the solder paste standard volume range, a solder paste demoulding abnormality prompt is issued, and the flip chip bonding cannot be performed directly. Since the demoulding speed directly affects the separation of the solder paste from the steel network, thereby affecting the quality and distribution of the solder paste on the pad, if the demoulding speed is too high, the solder paste will not be directly removed. If the demoulding speed is too slow, the solder paste will be in contact with the side wall of the steel mesh opening for too long, and the adhesion force may cause the solder paste to be lifted up by the steel mesh, forming a "pull tip"; if the demoulding speed is too fast, the solder paste will not have time to completely separate from the steel mesh opening and may be "torn", resulting in some solder paste remaining in the opening and insufficient solder paste on the pad. Match the solder paste abnormality quantitative index with the demoulding speed adjustment value corresponding to each solder paste abnormality quantitative index preset in the chip welding database, and dynamically adjust the demoulding speed in the next solder paste printing process according to the matched demoulding speed adjustment value. This can solve the solder paste residue or pull tip problem caused by too fast or too slow speed, thereby improving the uniformity and distribution of solder paste on the pad.

[0053] If the solder paste abnormality quantitative index is less than or equal to the solder paste abnormality threshold, a flip chip bonding prompt is issued.

[0054] In this embodiment, when the solder paste abnormality quantitative index is greater than the solder paste abnormality threshold, it means that the solder paste printed on the pad does not meet the standard. If the solder paste is not oxidized, the preset personnel can be prompted to wipe the pad with anhydrous ethanol or a special cleaning agent to remove the residual solder paste. Under the premise that the solder paste is not contaminated, the unoxidized solder paste can be collected with a stainless steel spatula, put back into the original tank, and the solder paste can be re-printed on the pad. If the solder paste has been oxidized, the solder paste cannot be returned to the tank for use, and an ultrasonic cleaning machine is required to remove the oxidation residue and clean the pad. The present invention dynamically adjusts the scraper pressure and demolding speed during the solder paste printing process based on the solder paste abnormality quantitative index, which can ensure that the solder paste quantity and quality are within the optimal range, thereby improving the subsequent flip-chip welding quality and production efficiency. The scraper pressure and demoulding speed directly affect the printing accuracy of the solder paste. The present invention can dynamically optimize the solder paste printing effect by accurately controlling the scraper pressure and demoulding speed during the solder paste printing process, thereby ensuring that the thickness of the solder paste on the pad is evenly distributed, avoiding excessive or insufficient solder paste accumulation, reducing printing defects, and improving the reliability of subsequent flip-chip welding. This makes the solder paste printing process precise and significantly improves the quality and stability of flip-chip welding.

[0055] Furthermore, after the flip chip is bonded, the step of determining whether to perform dynamic bonding compensation based on the bonding offset and rotational deviation between the flip chip and the pad includes: obtaining a bonding offset threshold and a rotational deviation threshold from a preset chip bonding database; if the bonding offset exceeds the bonding offset threshold and the flip chip cannot be directly bonded, the placement machine is used to drive the flip chip to move to the pad bonding center coordinates. The pad bonding center coordinates can be directly calculated by extracting the pad contour from the pad image obtained by the CCD camera and using the geometric center of gravity method to calculate the pad contour. The placement machine is responsible for bonding the bumps of the flip chip to the target coordinates, where the target coordinates default to the PCB (Printed Circuit Board). The pad center coordinates set in the board (printed circuit board) design file. When the fit offset exceeds the fit offset threshold, it indicates that the pad center coordinates are not the pad fit center coordinates. The pad fit center coordinates need to be used as the target coordinates of the placement machine to re-move the chip. This can ensure that the flip chip is accurately aligned with the pad, thereby improving the accuracy of flip chip placement. If the fit offset does not exceed the fit offset threshold, it is determined whether the rotation offset exceeds the rotation offset threshold. If so, flip chip soldering cannot be performed directly. A compensation angle is generated based on the fit offset. The placement machine drives the flip chip's spindle angle to the compensation angle to ensure the correct angle positioning of the flip chip on the pad. Otherwise, a flip chip soldering prompt is issued. The compensation angle is the inverse correction value of the rotation offset. The chip center coordinates and chip spindle angle can be obtained by positioning the chip with a CCD camera. The deviation value is calculated based on the chip center coordinates and the preset solder paste point position coordinates to obtain the fit offset. The rotation offset is obtained by taking the absolute value of the difference between the chip spindle angle and the preset pad spindle angle.

[0056] In this embodiment, the present invention ensures mounting accuracy and reliability by dynamically adjusting the mounting position and angle of the compensation chip, thereby reducing poor welding caused by offset or angle errors. By judging whether the mounting offset exceeds the mounting offset threshold, the position error of the flip chip can be accurately identified and processed, thereby avoiding flip chip misalignment or welding quality problems caused by offset; by judging whether the rotational deviation exceeds the rotational deviation threshold, the angle deviation of the flip chip can be accurately identified and processed, thereby effectively reducing welding failures caused by rotational deviation. The present invention optimizes the flip chip bonding process by dynamically adjusting the mounting position and angle of the compensation flip chip, significantly improves the accuracy of the flip chip bonding, reduces the possibility of chip misalignment, effectively reduces the risk of welding defects caused by chip misalignment, and ensures the stability and accuracy of the final welding quality.

[0057] Furthermore, after the flip chip is welded, the step of quantitatively evaluating the flip chip welding effect according to the welding precision parameters includes: obtaining welding precision parameter reference data from a preset chip welding database, specifically including: critical solder joint position deviation, reference solder ball size, solder ball size allowable deviation and critical fitting offset; performing a proportion approximation operation on the critical solder joint position deviation and the critical fitting offset with the solder joint position deviation and the fitting offset respectively, to obtain solder joint position deviation influencing parameters and fitting offset influencing parameters; obtaining the actual solder ball size deviation based on the solder ball size allowable deviation and the solder ball size, and comparing it with the reference solder ball size. The solder ball size is compared to obtain the solder ball size influencing parameters; the solder point position deviation influencing parameters, solder ball size influencing parameters and fitting offset influencing parameters are weighted using the welding accuracy parameter contribution data, and the weighted calculation results are coupled to obtain the welding effect quantitative index; the welding effect quantitative index represents the quantitative data of the degree of influence of the welding accuracy parameters on the welding effect, and the welding accuracy parameters include solder point position deviation, solder ball size and fitting offset; the welding accuracy parameter contribution data includes solder point position deviation contribution, solder ball size contribution and fitting offset contribution.

[0058] The method for obtaining the welding effect quantitative index is as follows:

[0059] ;

[0060] Where w represents the quantitative index of welding effect, γ4 represents the contribution of solder joint position deviation, γ5 represents the contribution of solder ball size, and γ6 represents the contribution of fitting offset.

[0061] d represents the solder joint position deviation, which is the offset between the actual solder joint position and the designed position in the PCB design file. It can be obtained by aligning the actual solder joint image with the design template and calculating the center point offset. d1 represents the critical solder joint position deviation.

[0062] s represents the solder ball size. The solder ball is placed at the contact point between the flip chip and the pad, serving as a bridge connecting the flip chip and the pad. It can be calculated by measuring the solder ball projection diameter in the image obtained by the CCD camera. s1 represents the reference solder ball size, and s2 represents the allowable deviation of the solder ball size.

[0063] b represents the fitting offset, and b1 represents the critical fitting offset.

[0064] In the chip welding database, γ4, γ5, and γ6 are the corresponding contributions of solder joint position deviation, solder ball size, and fitting offset, respectively. These contributions are quantitative representations of the contribution of the above welding accuracy parameters to the quantitative index of welding effect. Specifically, solder joint position deviation, solder ball size, and fitting offset are each configured with an independent mapping relationship table, which contains a one-to-one or many-to-one correspondence. The table records each possible welding accuracy parameter value and its corresponding contribution. In actual applications, the real-time measured solder joint position deviation, solder ball size, and fitting offset are respectively input into their corresponding mapping relationship tables to automatically match their corresponding contributions, where the contribution value ranges from 0 to 1.

[0065] In this embodiment, the solder joint position deviation, solder ball size and fitting offset are interrelated. For example, the larger the chip fitting offset, the farther the center of the solder ball deviates from the pad, resulting in a synchronous increase in the solder joint position deviation. When the fitting offset exceeds the pad radius, the solder ball may be completely misaligned, causing an open circuit. The smaller the solder ball size, the less likely the solder ball strength is to be sufficient, and self-alignment cannot be achieved due to surface tension during reflow soldering, exacerbating the solder joint position deviation. Excessive fitting offset will cause the solder paste to be unevenly squeezed by the chip, causing solder paste to flow out of some solder joints and accumulate on the other side, resulting in abnormal solder ball size distribution.

[0066] Furthermore, the step of determining whether to use a temperature measuring probe, a temperature controller, and a laser to perform flip chip repair based on the quantitative evaluation result includes: obtaining a welding effect threshold from a preset chip welding database; comparing a welding effect quantification index with the welding effect threshold; if the welding effect quantification index is greater than or equal to the welding effect threshold, issuing a welding effect compliance prompt without performing additional processing; if the welding effect quantification index is less than the welding effect threshold, issuing a welding effect non-compliance prompt; recording the difference between the welding effect threshold and the welding effect quantification index as a welding effect deviation value; matching the welding effect deviation value with a chip adjustment ratio corresponding to each welding effect deviation range preset in the chip welding database; forming a mapping relationship table in which each welding effect deviation range corresponds to the chip adjustment ratio in a one-to-one manner in the chip welding database; and recording each welding effect deviation range and the chip adjustment ratio corresponding to the chip adjustment ratio in the table. The table records each welding effect deviation range and its corresponding chip adjustment ratio. These relationships can be one-to-one or many-to-one. When obtaining the chip adjustment ratio, it is only necessary to input the welding effect deviation value into the mapping relationship table. The chip welding database can quickly locate and return the chip adjustment ratio corresponding to the welding effect deviation range, prompting the flip chip welding device to perform flip chip repair according to the matched chip adjustment ratio.

[0067] Among them, flip chip repair includes abnormal chip removal and replacement flip chip welding; during the abnormal chip removal process, the CCD camera is first used to locate the abnormal chip position and monitor the abnormal chip removal process, and the abnormal chip size is adjusted in combination with the chip adjustment ratio. Then, the laser heating head is used to align the center of the light spot with the abnormal solder joint and adjust it to the target chip size. At the same time, the temperature of the flip chip and the pad is detected by the temperature probe and fed back to the temperature controller. The temperature controller controls the laser output power in real time to remove the abnormal chip; replacement flip chip welding means using a flip chip welding device to weld the replacement flip chip, and replacing the flip chip with a brand new flip chip that meets quality standards, which can be accurately welded to the pad on the substrate at the original welding position.

[0068] In this embodiment, in a flip chip image after soldering obtained by a CCD camera, an edge detection algorithm such as Canny edge detection is used to extract the edge of the chip outline, and a contour extraction algorithm is used to extract the closed area in the image, i.e., the outline of the abnormal chip, to obtain a set of closed boundaries. These boundaries represent the outer contour of the abnormal chip. Based on these extracted contour pixels and the actual size corresponding to the pixels, the abnormal chip size can be obtained. The target chip size can be obtained by multiplying the chip size adjustment ratio by the abnormal chip size. The present invention can accurately determine whether the flip chip soldering effect meets the standard by comparing the soldering effect quantification index with the soldering effect threshold value, and automatically perform flip chip repair based on the chip adjustment ratio obtained from the soldering effect deviation value. This not only improves the accuracy of soldering quality control, but also effectively reduces manual intervention, automatically guides the flip chip repair process, reduces the defect rate of solder joints, and reduces the cost of the flip chip soldering and repair process, thereby improving the quality of flip chip soldering and repair.

[0069] As an embodiment of the second aspect, Figure 12The figure shows a flow chart of a laser heating method for flip chip welding and repair provided by an embodiment of the present application. The specific steps of the laser heating method for flip chip welding and repair provided by the present application include: performing solder paste abnormality evaluation on the pad after solder paste printing according to the solder paste quality parameters, judging whether to perform dynamic printing adjustment based on the obtained solder paste abnormality evaluation result, and the dynamic printing adjustment is used to dynamically set the scraper pressure and demolding speed in the next solder paste printing process to improve the uniformity of solder paste thickness distribution; after the flip chip is bonded, judging whether to perform dynamic bonding compensation according to the bonding offset and rotation deviation between the flip chip and the pad, and the dynamic bonding compensation is used to adjust the position and angle of the flip chip Dynamic adjustment is performed to improve the placement accuracy of the flip chip; flip chip welding is performed using a temperature probe, a temperature controller, and a laser. After the flip chip welding, the flip chip welding effect is quantitatively evaluated according to the welding accuracy parameters, and based on the quantitative evaluation results, it is determined whether to use the temperature probe, the temperature controller, and the laser to repair the flip chip. The temperature probe is used to detect the temperature of the flip chip and the pad and feed it back to the temperature controller. The temperature controller is used to adjust the laser output power in real time through temperature feedback according to the temperature setting requirements to control the heating temperature of the pad during the flip chip welding process.

[0070] To summarize, this embodiment ensures the accuracy of flip chip welding and repair quality by dynamically evaluating and adjusting solder paste quality parameters, flip chip bonding accuracy and welding accuracy parameters. First, solder paste abnormality evaluation is performed based on solder paste quality parameters to determine whether dynamic adjustment of the printing process is required, and the scraper pressure and demolding speed are optimized to improve the uniformity of solder paste thickness distribution; then, during the flip chip bonding process, dynamic bonding compensation is determined based on the bonding offset and rotational deviation between the chip and the pad to ensure precise docking of the chip position and angle, thereby improving the bonding accuracy; finally, after the flip chip welding device is used to complete the welding, the welding effect is evaluated based on the welding accuracy parameters to determine whether flip chip repair is required, and the welding effect is further optimized. Based on the laser heating method, efficient and high-precision control of temperature and heat distribution in the entire flip chip welding and repair process is achieved, thereby improving the quality of flip chip welding and repair.

[0071] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems and methods, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0072] The present invention is described with reference to flowcharts and / or block diagrams of systems and methods, devices (systems and methods), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0073] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0074] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0075] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0076] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A laser heating system for flip chip welding and repair, characterized in that: include: Solder paste adjustment module, chip welding module, welding repair module and chip welding database; The solder paste adjustment module is used to evaluate solder paste abnormalities on the pads after solder paste printing based on the solder paste quality parameters, and determine whether to perform dynamic printing adjustment based on the obtained solder paste abnormality evaluation results. The dynamic printing adjustment is used to dynamically set the scraper pressure and demoulding speed in the next solder paste printing process to improve the uniformity of solder paste thickness distribution; The chip welding module is used to determine whether to perform dynamic bonding compensation based on the bonding offset and rotation deviation between the flip chip and the pad after the flip chip is bonded. The dynamic bonding compensation is used to dynamically adjust the position and angle of the flip chip to improve the bonding accuracy of the flip chip; The welding repair module uses a temperature probe, a temperature controller, and a laser to perform flip-chip welding. After the flip-chip welding, the flip-chip welding effect is quantitatively evaluated according to the welding accuracy parameters. Based on the quantitative evaluation results, it is determined whether to use the temperature probe, temperature controller, and laser to repair the flip-chip. The temperature probe is used to detect the temperature of the flip-chip and the pad and feed it back to the temperature controller. The temperature controller is used to adjust the laser output power in real time through temperature feedback according to the temperature setting requirements to control the heating temperature of the pad during the flip-chip welding process. The step of performing solder paste abnormality evaluation on the solder pad after solder paste printing according to the solder paste quality parameters includes: Obtain solder paste quality parameter reference data from a preset chip soldering database, specifically including: reference solder paste thickness, solder paste thickness tolerance, reference solder paste coverage, solder paste coverage tolerance, reference solder paste volume, and solder paste volume tolerance; The actual deviation of solder paste thickness is obtained based on the reference solder paste thickness and the solder paste thickness, and compared with the allowable deviation of solder paste thickness to obtain the influencing parameter of solder paste thickness; Based on the reference solder paste coverage and the solder paste coverage, the actual deviation of the solder paste coverage is obtained, and compared with the allowable deviation of the solder paste coverage to obtain the parameters affecting the solder paste coverage; The actual deviation of the solder paste volume is obtained based on the reference solder paste volume and the solder paste volume, and compared with the allowable deviation of the solder paste volume to obtain the solder paste volume influencing parameter; The solder paste quality parameter contribution data is used to perform weighted coupling processing on the parameters affecting solder paste thickness, solder paste coverage, and solder paste volume, respectively, to obtain the solder paste abnormality quantitative index. The solder paste abnormality quantitative index represents quantitative data of the degree of influence of solder paste quality parameters on the solder paste state on the pad, wherein the solder paste quality parameters include solder paste thickness, solder paste coverage and solder paste volume; The solder paste quality parameter contribution data includes solder paste thickness contribution, solder paste coverage contribution and solder paste volume contribution.

2. A laser heating system for flip chip welding and repair according to claim 1, characterized in that: The step of determining whether to perform dynamic printing adjustment based on the obtained solder paste abnormality evaluation result includes: Obtain solder paste abnormality threshold and solder paste standard volume range from a preset chip soldering database; If the solder paste abnormality quantitative index is greater than the solder paste abnormality threshold and the solder paste volume is greater than the maximum value of the solder paste standard volume range, a solder paste excess prompt is issued, and the solder paste abnormality deviation index is matched with the scraper pressure adjustment value corresponding to each solder paste abnormality deviation index range preset in the chip welding database. The scraper pressure in the next solder paste printing process is increased according to the matched scraper pressure adjustment value. The solder paste abnormality deviation index represents the difference between the solder paste abnormality quantitative index and the solder paste abnormality threshold; If the solder paste abnormality quantitative index is greater than the solder paste abnormality threshold and the solder paste volume is less than the minimum value of the solder paste standard volume range, a solder paste insufficient prompt is issued and the scraper pressure is reduced in the next solder paste printing process according to the scraper pressure adjustment value; If the solder paste abnormality quantitative index is greater than the solder paste abnormality threshold and the solder paste volume is within the solder paste standard volume range, a solder paste demoulding abnormality prompt is issued, and the solder paste abnormality quantitative index is matched with the demoulding speed adjustment value corresponding to each solder paste abnormality quantitative index preset in the chip welding database. The demoulding speed of the next solder paste printing process is dynamically adjusted according to the matched demoulding speed adjustment value; If the solder paste abnormality quantitative index is less than or equal to the solder paste abnormality threshold, a flip chip bonding prompt is issued.

3. A laser heating system for flip chip welding and repair according to claim 1, characterized in that: The step of determining whether to perform dynamic bonding compensation according to the bonding offset and rotation deviation between the flip chip and the pad after the flip chip is bonded comprises: Obtaining a fit offset threshold and a rotation deviation threshold from a preset die bonding database; If the bonding offset exceeds the bonding offset threshold, the placement machine is used to drive the flip chip to move to the pad bonding center coordinates; If the fitting offset does not exceed the fitting offset threshold, it is determined whether the rotational offset exceeds the rotational offset threshold. If so, a compensation angle is generated based on the fitting offset, and the spindle angle of the flip chip is driven to the compensation angle by the placement machine. Otherwise, a flip chip welding prompt is issued.

4. A laser heating system for flip chip welding and repair according to claim 1, characterized in that: The flip chip welding is realized based on a flip chip welding device, which specifically includes a laser heating head, a laser, a temperature measuring probe, a temperature controller and a CCD camera; The CCD camera is used to locate the chip position and monitor the flip chip welding process in real time; The laser heating head is used to adjust the spot size to control the heating area of ​​the pad heating process; The temperature controller, temperature measuring probe and laser perform real-time signal transmission and feedback with each other.

5. A laser heating system for flip chip welding and repair as claimed in claim 4, characterized in that: The laser heating head includes a collimating lens, a focusing lens group and a micro lens group; The collimator is used to reduce the divergence angle of the circular light beam output by the fiber laser; The focusing lens group includes a first focusing lens and a second focusing lens; The microlens group includes a first cylindrical microlens array and a second cylindrical microlens array, the first cylindrical microlens array includes a first cylindrical microlens and a second cylindrical microlens, and the second cylindrical microlens array includes a third cylindrical microlens and a fourth cylindrical microlens; The spacing of the first cylindrical microlens array is used to control the length of the output light spot; The first cylindrical microlens array and the first focusing lens form a first group of microlens arrays oriented in a first direction; The spacing of the second cylindrical microlens array is used to control the width of the output light spot; The second cylindrical microlens array and the second focusing lens form a second group of microlens arrays oriented in a second direction; The first group of microlens arrays and the second group of microlens arrays are orthogonal in direction, and the working surfaces of the two groups of microlens arrays overlap, forming an imaging type microlens array in orthogonal directions.

6. A laser heating system for flip chip welding and repair as claimed in claim 1, characterized in that: The step of quantitatively evaluating the flip chip welding effect according to the welding accuracy parameters after the flip chip welding comprises: Obtain welding accuracy parameter reference data from a preset chip welding database, including: critical solder joint position deviation, reference solder ball size, solder ball size tolerance, and critical fitting offset; The critical solder joint position deviation and the critical fitting offset are respectively subjected to a proportion approximation operation with the solder joint position deviation and the fitting offset to obtain the solder joint position deviation influencing parameters and the fitting offset influencing parameters; The actual deviation of the solder ball size is obtained based on the allowable deviation of the solder ball size and the solder ball size, and compared with the reference solder ball size to obtain the solder ball size influencing parameter; The contribution data of welding accuracy parameters are used to perform weighted operations on the parameters affecting solder joint position deviation, solder ball size and fitting offset respectively. The weighted operation results are then coupled to obtain a quantitative index of welding effect. The welding effect quantitative index represents the quantitative data of the degree of influence of welding precision parameters on welding effect, wherein the welding precision parameters include solder point position deviation, solder ball size and fitting offset; The welding accuracy parameter contribution data includes the solder point position deviation contribution, the solder ball size contribution and the fitting offset contribution.

7. A laser heating system for flip chip welding and repair as claimed in claim 6, characterized in that: The step of determining whether to use a temperature probe, a temperature controller, and a laser to perform flip chip repair based on the quantitative evaluation result includes: Obtaining a welding effect threshold from a preset chip welding database; If the welding effect quantitative index is greater than or equal to the welding effect threshold, a welding effect reaching standard prompt is issued without additional processing; If the welding effect quantitative index is less than the welding effect threshold, a prompt indicating that the welding effect does not meet the standard is issued, and the difference between the welding effect threshold and the welding effect quantitative index is recorded as the welding effect deviation value. The welding effect deviation value is matched with the chip adjustment ratio corresponding to each welding effect deviation range preset in the chip welding database, and the flip chip welding device is prompted to perform flip chip repair according to the matched chip adjustment ratio.

8. A laser heating system for flip chip welding and repair as claimed in claim 7, characterized in that: The flip chip repair includes abnormal chip removal and replacement flip chip welding; Abnormal chip removal means first locating the abnormal chip position and monitoring the abnormal chip removal process through a CCD camera, adjusting the abnormal chip size in combination with the chip adjustment ratio, then aligning the center of the laser spot with the abnormal solder joint through a laser heating head and adjusting it to the target chip size. At the same time, the temperature of the flip chip and the solder pad is detected by a temperature probe and fed back to the temperature controller. The temperature controller then controls the laser output power in real time to remove the abnormal chip. The replacement flip chip bonding refers to bonding the replacement flip chip using a flip chip bonding device.

9. A laser heating method for flip chip welding and repair, applied to the laser heating system for flip chip welding and repair according to any one of claims 1 to 8, characterized in that: The following steps are involved: Perform solder paste abnormality assessment on the pads after solder paste printing based on the solder paste quality parameters, and determine whether to perform dynamic printing adjustment based on the obtained solder paste abnormality assessment results. The dynamic printing adjustment is used to dynamically set the scraper pressure and demoulding speed in the next solder paste printing process to improve the uniformity of solder paste thickness distribution; After the flip chip is attached, it is determined whether dynamic attachment compensation should be performed according to the attachment offset and rotation deviation between the flip chip and the pad. The dynamic attachment compensation is used to dynamically adjust the position and angle of the flip chip to improve the attachment accuracy of the flip chip. Flip chip welding is performed using a temperature probe, a temperature controller, and a laser. After flip chip welding, the flip chip welding effect is quantitatively evaluated according to the welding accuracy parameters. Based on the quantitative evaluation results, it is determined whether to use the temperature probe, temperature controller, and laser to repair the flip chip. The temperature probe is used to detect the temperature of the flip chip and the pad and feed it back to the temperature controller. The temperature controller is used to adjust the laser output power in real time through temperature feedback according to the temperature setting requirements to control the heating temperature of the pad during the flip chip welding process.

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