Manufacturing process of mobile air conditioner panels based on multilayer PCB

Abstract

This invention relates to the field of mobile air conditioner panel manufacturing technology, and particularly to a mobile air conditioner panel manufacturing process based on multilayer PCBs. The process includes forming a PCB mounting substrate; attaching component patches to the patch positions to form a pre-fixed PCB board; acquiring several frames of three-dimensional images of the solder on the pads and determining dense and dispersed regions, locating the tear-like surface based on their duration; comparing the texture features of the predicted dense and dispersed regions on both sides of the tear-like surface with the texture features generated by pressure; if the texture features are consistent, determining the pressure of the pick-and-place machine nozzle; determining the heating rate of the mounting area based on the height of the heated solder distribution and actually heating, melting, and cooling the pre-fixed PCB board to form a multilayer PCB assembly board; and bonding the multilayer PCB assembly board to the mobile air conditioner substrate to form the mobile air conditioner panel. This invention improves the manufacturing accuracy of multilayer PCB boards.

Description

Technical Field

[0001] This invention relates to the field of mobile air conditioner panel manufacturing technology, and in particular to a mobile air conditioner panel manufacturing process based on multilayer PCB. Background Technology

[0002] With the rapid development of smart home and Internet of Things technologies, portable air conditioners have become an indispensable device in modern home and office environments. The distribution of solder in the PCB manufacturing process of existing portable air conditioner panels affects the accuracy of component placement.

[0003] In the prior art, Chinese Patent Publication No. CN216897752U discloses a square display panel for a wall-mounted air conditioner, including a substrate, a plastic shell, and electronic components. The substrate is a single-layer PCB board, with circuit patterns formed only on the upper side of the substrate. All electronic components are surface-mount soldered to the upper side of the substrate and are electrically connected to the circuit patterns to construct the display circuit of the wall-mounted air conditioner. The electronic components include surface-mount LEDs, surface-mount receivers, surface-mount capacitors, and surface-mount terminals. The surface-mount LEDs are arranged in a preset dot matrix so that the display circuit status can be constructed by combining surface-mount LEDs from different circuits to emit light. The plastic shell is fixed to the upper side of the substrate and covers the surface-mount LEDs. Multiple reflective cavities are hollowed out on the plastic shell, and the center of the bottom cavity of each reflective cavity corresponds to a surface-mount LED. This utility model eliminates the need for complex processes such as component shaping, insertion, and wave soldering, simplifying the production process, increasing efficiency, and significantly reducing material and labor costs. However, the square display board for the air conditioner wall unit suffers from a problem where the solder on the PCB board pads, during the melting and cooling process, forms dense and dispersed regions with varying solder densities due to temperature gradients and heat dissipation differences, leading to a tendency towards tearing and reduced electrical connectivity. Summary of the Invention

[0004] To address this, the present invention provides a manufacturing process for a mobile air conditioner panel based on a multilayer PCB, which overcomes the problem in the prior art where, during the melting and cooling process of solder on PCB pads, the formation of dense and dispersed regions with different solder density conditions due to temperature gradients and heat dissipation differences leads to the formation of tearing surfaces and reduced electrical connectivity.

[0005] To achieve the above objectives, the present invention provides a manufacturing process for a mobile air conditioner panel based on a multilayer PCB, comprising:

[0006] Solder is spread evenly onto a multilayer PCB board to form a PCB mounting substrate;

[0007] The component chip is attached to the corresponding chip position on the PCB mounting substrate by the nozzle of the chip mounter to form a pre-fixed PCB board;

[0008] The solder on the pre-fixed PCB board is subjected to a melting and cooling test, and several frames of three-dimensional images of the solder on the pre-fixed PCB board are obtained.

[0009] Based on the aforementioned three-dimensional images, dense and dispersed regions are determined;

[0010] The solder tends to tear surface based on the duration of the dense region and the duration of the dispersed region;

[0011] The texture features of the dense and dispersed regions on both sides of the tear surface are compared with the texture features generated during the component patch attachment process.

[0012] If the texture features are consistent, the adhesion pressure generated by the nozzle is determined to be abnormal, and the nozzle pressure is re-determined based on the abnormal condition.

[0013] The heating rates of the outer part of the attachment area and the inner part of the attachment area are determined based on the distribution height of the solder after heating, which has consistent texture characteristics.

[0014] The pre-fixed PCB board is actually heated and cooled according to the heating rate to fix the components to the corresponding patch positions on the pre-fixed PCB board, forming a multilayer PCB assembly board;

[0015] The multilayer PCB assembly board is bonded to the portable air conditioner substrate to form a portable air conditioner panel;

[0016] The heating parameters on both sides of the tearing surface are related to the duration.

[0017] Further, determining the dense and dispersed regions based on the plurality of three-dimensional images includes:

[0018] Extract the solder density from several equally spaced density sampling points in the aforementioned three-dimensional images;

[0019] The largest closed three-dimensional region formed by connecting the first corresponding density sampling points that meet the solder density condition is defined as the dense region.

[0020] The entire three-dimensional space of the solder occupied by the second corresponding density sampling point that does not meet the solder density condition is defined as the dispersion region.

[0021] Furthermore, the solder density condition is that the solder density at the density sampling point is greater than a preset density.

[0022] Furthermore, the dense region and the dispersed region are positioned towards the tear surface based on the duration of their exposure at the melting temperature, wherein,

[0023] The tending tear surface is formed during the solder cooling process due to temperature gradient and heat dissipation differences, resulting in dense and dispersed regions. The interface between the largest closed three-dimensional regions of the dense and dispersed regions is the tending tear surface.

[0024] Furthermore, the melting temperature is the temperature at which the solder on the pre-fixed PCB board is melted and cooled during the test.

[0025] Furthermore, the texture features of the predicted dense and dispersed regions on both sides of the tearing surface are compared with the texture features generated by the downward vertical torque transmitted by the pick-and-place machine nozzle. This includes extracting the first texture features of the predicted dense and dispersed regions from the three-dimensional image of the pre-fixed PCB board; and obtaining the second texture features generated by the simulated downward vertical torque transmitted by the pick-and-place machine nozzle.

[0026] If the similarity between the first texture feature and the second texture feature is greater than or equal to 90%, then the first texture feature and the second texture feature are determined to be consistent.

[0027] Furthermore, based on the specific criteria for determining pressure anomalies according to texture feature similarity, the pressure anomaly is determined when the downward vertical torque transmitted by the pick-and-place machine nozzle is greater than a preset torque, indicating that the state of the pick-and-place machine nozzle is abnormal at this time. Based on the second texture feature, the first pressure value of the pick-and-place machine nozzle is extracted, and the first pressure value is adjusted to the preset pressure value.

[0028] Furthermore, when the vertical distribution height of the solder calculated from the Z-axis coordinate of the three-dimensional image is greater than a preset distribution height, the heating rate of the outer portion of the attachment area is increased to a first heating rate, and the heating rate of the inner portion of the attachment area is decreased to a second heating rate to guide the solder to flow outward through a temperature gradient.

[0029] The attachment area is the three-dimensional space area of ​​the solder of a single solder point corresponding to the component patch, which is identified by the contact boundary between the solder and the PCB substrate in the three-dimensional image;

[0030] Furthermore, the first heating rate is greater than the second heating rate.

[0031] Furthermore, based on the inconsistency between the first texture feature and the second texture feature, i.e., the similarity between the first texture feature and the second texture feature is less than 90%, the heating temperature of the dense region is increased and the heating temperature of the dispersed region is decreased according to the tendency towards the tear surface.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention performs melting and cooling tests on the solder on the pre-fixed PCB board in sequence and obtains several frames of three-dimensional images of the solder on the pads to determine the dense and dispersed areas of the solder on the pads. Based on the duration of the dense and dispersed areas, the tendency to tear is located, thus understanding the distribution state of the solder during the heating and cooling processes and predicting the risk of solder splitting due to uneven thermal stress or pressure distribution in advance. By comparing the texture features of the predicted dense and dispersed areas on both sides of the tendency to tear with the texture features generated by pressure pressing, it is determined whether the tendency to tear is generated by pressure pressing. This allows for further targeted adjustment of process parameters such as heating temperature, heating rate, and nozzle pressure to avoid uneven solder distribution or tearing defects, thereby improving welding quality and reliability.

[0033] Furthermore, by acquiring a three-dimensional image of a pre-fixed PCB board, the present invention determines the dense and dispersed regions of the solder at the melting temperature, locates the tearing surface, and thus determines the areas where the solder may tear during the heating process.

[0034] Furthermore, the present invention determines whether the tendency to tear will transform into an actual tear by detecting the duration of the dense region and the dispersed region. If the predicted dense region and dispersed region merge during the heating process, an actual tear will not be generated.

[0035] Furthermore, this invention addresses the issue of the predicted dense and dispersed regions not fusing during the heating process.

[0036] The texture features of the predicted dense and predicted dispersed regions on both sides of the tearing surface are compared with the texture features generated by the downward vertical torque transmitted by the pick-and-place machine nozzle to determine whether the tearing surface is generated by the downward vertical torque transmitted by the pick-and-place machine nozzle. If the two are consistent, the pressure value of the pick-and-place machine nozzle is adjusted accordingly to improve the electrical connectivity of the PCB board.

[0037] Furthermore, the present invention adjusts the heating temperature on both sides of the tear surface in a targeted manner based on the inconsistency between the first texture feature and the second texture feature, so that the dense region and the dispersed region around the tear surface can be effectively fused.

[0038] Furthermore, the present invention adjusts the heating rate by calculating the vertical distribution height of the solder from the Z-axis coordinate of the three-dimensional image to be greater than the preset distribution height, thereby guiding the solder to flow outward by the temperature gradient to compensate for the excessive vertical torque of the pick-and-place machine nozzle, which causes solder to accumulate on the outside. Attached Figure Description

[0039] Figure 1This is an overall flowchart of the manufacturing process of a mobile air conditioner panel based on a multilayer PCB according to an embodiment of the present invention;

[0040] Figure 2-1 This is a schematic diagram illustrating the connection between component pads, solder, and solder pads, as well as the tendency of the solder to tear, in the manufacturing process of a mobile air conditioner panel based on a multilayer PCB according to an embodiment of the present invention.

[0041] Figure 2-2 This is a schematic diagram showing the connection between the outer part of the component patch and pad, and the inner part of the solder attachment area in the manufacturing process of a mobile air conditioner panel based on a multilayer PCB according to an embodiment of the present invention.

[0042] Figure 3 This is a flowchart illustrating the determination of dense and dispersed regions in the manufacturing process of a mobile air conditioner panel based on a multilayer PCB according to an embodiment of the present invention.

[0043] The following are the symbols in the attached diagram: 1-Component patch, 2-Solder, 3-Pad, 4-Tear-like surface, 5-Outer part of the mounting area, 6-Inner part of the mounting area. Detailed Implementation

[0044] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0045] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0046] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0047] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0048] Please see Figure 1, Figure 2-1 , Figure 2-2 as well as Figure 3 The diagrams shown are, respectively, an overall flowchart of the manufacturing process of a mobile air conditioner panel based on a multilayer PCB according to an embodiment of the present invention; a schematic diagram of the connection between component pads and solder and pads, and the solder tending towards the tear surface; a schematic diagram of the connection between the outer part and the inner part of the attachment area of ​​the component pads and pads and solder; and a flowchart of determining dense and dispersed regions. The manufacturing process of a mobile air conditioner panel based on a multilayer PCB according to an embodiment of the present invention includes:

[0049] Solder 2 is spread evenly on the multilayer PCB board to form a PCB mounting substrate;

[0050] The component patch 1 is attached to the corresponding patch position on the PCB mounting substrate by the nozzle of the pick-and-place machine to form a pre-fixed PCB board;

[0051] A melting and cooling test was performed on the solder 2 on the pre-fixed PCB board, and several frames of three-dimensional images of the solder 2 on the pre-fixed PCB board were obtained.

[0052] Based on the aforementioned three-dimensional images, dense and dispersed regions are determined;

[0053] The solder 2 is positioned towards the tear surface 4 based on the duration of the dense region and the duration of the dispersed region;

[0054] The texture features of the dense and dispersed regions on both sides of the tear surface 4 are compared with the texture features generated during the attachment process of the component patch 1.

[0055] If the texture features are consistent, the adhesion pressure generated by the nozzle is determined to be abnormal, and the nozzle pressure is re-determined based on the abnormal condition.

[0056] The heating rates of the outer part of the attachment area and the inner part of the attachment area are determined based on the distribution height of the solder 2 after heating, which has consistent texture characteristics.

[0057] The pre-fixed PCB board is actually heated and cooled according to the heating rate to fix the components to the corresponding patch positions on the pre-fixed PCB board, forming a multilayer PCB assembly board;

[0058] The multilayer PCB assembly board is bonded to the portable air conditioner substrate to form a portable air conditioner panel;

[0059] The heating parameters on both sides of the tearing surface 4 are related to the duration.

[0060] Specifically, a multilayer PCB is a complex circuit board composed of multiple conductive and insulating layers stacked alternately, including conductive layers, insulating layers, vias, solder mask layers, silkscreen layers, power and ground layers, signal layers, core layers and prepreg layers, as well as pads located on the PCB surface layer 3.

[0061] Specifically, the duration is the time from when the solder 2 begins to melt at the melting temperature to when it begins to cool.

[0062] In this invention, the component patch 1 is a 0603 package resistor, the solder 2 is laid with a thickness of 0.2mm, and the solder 2 is laid with a temperature of 180℃.

[0063] Specifically, a 3D scanner is used to obtain a 3D image of the pre-fixed PCB board.

[0064] In practice, this invention performs melting and cooling tests on the solder 2 on the pre-fixed PCB board sequentially and acquires several frames of three-dimensional images of the solder 2 on the pads 3 to determine the dense and dispersed regions of the solder 2 on the pads 3. Based on the duration of the dense and dispersed regions, the tendency to tear surface 4 is located, thus understanding the distribution state of the solder 2 during the heating and cooling processes and predicting the risk of breakage that may be caused by uneven distribution of thermal stress or pressure. By comparing the texture features of the predicted dense and dispersed regions on both sides of the tendency to tear surface 4 with the texture features generated by pressure pressing, it is determined whether the tendency to tear surface 4 is generated by pressure pressing. This allows for further targeted adjustment of process parameters such as heating temperature, heating rate, and nozzle pressure to avoid uneven distribution or tearing defects of the solder 2, thereby improving welding quality and reliability.

[0065] Please see Figure 3 As shown, determining the dense and dispersed regions based on the plurality of frames of three-dimensional images includes:

[0066] Extract the solder density from several equally spaced density sampling points in the aforementioned three-dimensional images;

[0067] The largest closed three-dimensional region formed by connecting the first corresponding density sampling points that meet the solder density condition is defined as the dense region.

[0068] The entire three-dimensional space of solder 2 occupied by the second corresponding density sampling point that does not meet the solder density condition is defined as the dispersion region.

[0069] Specifically, the several frames of three-dimensional images are several frames of three-dimensional ultrasound images generated through ultrasound detection.

[0070] Specifically, the solder density condition is that the solder density at the density sampling point is greater than a preset density.

[0071] In one specific embodiment, under standard pad 3 conditions, the average solder density is 8.0 g / L. The preset density is set to 90% of the average solder density, i.e., the preset density is 7.2 g / L. .

[0072] In practice, the present invention obtains a three-dimensional image of a pre-fixed PCB board, determines the dense and dispersed regions of the solder 2 at the melting temperature, locates the tearing surface 4, and thus determines the area where the solder 2 may tear during the heating process.

[0073] Specifically, the dense region and the dispersed region are positioned towards the tear surface 4 based on the duration of their exposure to the melting temperature, wherein...

[0074] The tending tear surface 4 is formed during the cooling process of solder 2 due to temperature gradient and heat dissipation differences, resulting in dense and dispersed regions. The interface between the dense and dispersed regions and the largest closed three-dimensional regions is the tending tear surface 4.

[0075] In a specific embodiment, under the condition of standard pad 3, if the dense area and the dispersed area are completely fused within 10 to 20 seconds, it indicates that the solder 2 is evenly distributed and no actual tear surface will be generated.

[0076] In practice, the present invention determines whether the tending tear surface 4 will transform into an actual tear surface by detecting the duration of the dense region and the dispersed region. If the predicted dense region and dispersed region merge during the heating process, the actual tear surface will not be generated.

[0077] Specifically, the melting temperature is the temperature at which the solder 2 on the pre-fixed PCB board is melted and cooled during the test.

[0078] Optionally, the melting temperature range is [210℃, 230℃].

[0079] Preferably, in this embodiment, the component patch 1 is a 0603 package resistor with a melting temperature set to 220°C to ensure that the solder 2 is fully melted and forms a good solder joint, while avoiding damage to the component or PCB substrate due to excessive temperature. The PCB substrate is easily damaged at ambient temperatures above 260°C.

[0080] Specifically, the heating parameters include the location of the dense and dispersed regions, as well as the heating temperature.

[0081] After locating the heating area, the heating temperature is gradually increased to no more than 255°C, based on the longer the duration of the dispersed and dense regions. The formula for calculating the heating temperature and duration is as follows:

[0082]

[0083] Where T is the heating temperature. t is the melting temperature, k is the temperature gradient coefficient, and t is the duration of the dispersed / dense region, where the durations of the dispersed and dense regions are equal.

[0084] A specific embodiment is that the solder density of the density sampling points is extracted from several frames of three-dimensional ultrasonic images generated by ultrasonic detection, and the dispersed area and dense area are determined and used as the heating area. Under the condition of standard solder pad 3, if the dispersed area and dense area are completely fused within 5 seconds, then according to the calculation formula of heating temperature and duration: T=220+2×5=230℃, that is, the heating temperature is 230℃.

[0085] If the duration of the dispersed and dense regions exceeds 20 seconds, then according to the formula for calculating heating temperature and duration: T = 220 + 0.5 × t, for example, if fusion does not occur within 25 seconds, then the heating temperature is T = 220 + 0.5 × 25 = 232.5℃.

[0086] When the duration is short, it indicates that the fusion of dispersed and dense regions is fast and easy. In this case, it is necessary to rapidly increase the temperature by a large k and use the temperature gradient in a short period of time to accelerate the fusion.

[0087] When the duration is long, it indicates that the fusion is difficult. If k is too large, the temperature will rise rapidly and continuously, which may cause problems such as overheating of the pads and oxidation of the solder. Therefore, a smaller k is needed to slowly increase the temperature while ensuring fusion and controlling the upper limit of the temperature. For example, when t≤5s, k=2.

[0088] When 5s < t ≤ 10s, k = 1.5;

[0089] When 10s < t ≤ 20s, k = 1;

[0090] When t > 20s, k = 0.5.

[0091] Specifically, the texture features of the predicted dense and dispersed regions on both sides of the tear-prone surface 4 are compared with the texture features generated by the downward vertical torque transmitted by the pick-and-place machine nozzle. This includes extracting the first texture features of the predicted dense and dispersed regions from the 3D image of the pre-fixed PCB board; and obtaining the second texture features generated by the simulated downward vertical torque transmitted by the pick-and-place machine nozzle.

[0092] If the similarity between the first texture feature and the second texture feature is greater than or equal to 90%, then the first texture feature and the second texture feature are determined to be consistent.

[0093] Specifically, the first texture feature and the second texture feature are acquired by a 3D scanner. The gray-level co-occurrence matrix algorithm is used to extract the texture directionality and micro-morphological features. The extracted texture features are quantized into numerical values ​​or vectors and compared with the second texture feature. If the similarity between the first texture feature and the second texture feature exceeds 90%, it is determined that the first texture feature and the second texture feature are consistent.

[0094] Specifically, the feature parameters of the extracted first texture feature include contrast, which reflects the clarity of the texture; energy, which reflects the uniformity of the texture; entropy, which reflects the complexity of the texture; and correlation, which reflects the directionality of the texture. Among these, uniformity describes the regularity or consistency of the gray-level distribution in the texture.

[0095] Complexity describes the degree of disorder or irregularity of grayscale changes in a texture;

[0096] Directionality describes whether there is a clear dominant direction in the texture.

[0097] In a specific embodiment, the first texture feature parameters corresponding to the solder in the 3D image are extracted using the gray-level co-occurrence matrix algorithm: contrast is 0.80, energy is 0.90, entropy is 0.50, and correlation is 0.75.

[0098]

[0099] In this embodiment, the detected second texture feature vector is [0.85, 0.92, 0.45, 0.78]. The Euclidean distance is then calculated using the Euclidean distance formula:

[0100] + + + =0.0063;

[0101] ≈0.0794

[0102] Similarity is:

[0103] Similarity

[0104] The similarity between the first texture feature and the second texture feature is 92.6%.

[0105] In practice, this invention addresses the issue of predicted dense and dispersed regions not fusing during the heating process.

[0106] The texture features of the predicted dense and predicted dispersed regions on both sides of the tearing surface 4 are analyzed and compared with the texture features generated by the downward vertical torque transmitted by the pick-and-place machine nozzle to determine whether the tearing surface 4 is generated by the downward vertical torque transmitted by the pick-and-place machine nozzle. If the two are consistent, the pressure value of the pick-and-place machine nozzle is adjusted accordingly to improve the electrical connectivity of the PCB board.

[0107] Specifically, the criteria for determining pressure anomalies based on texture feature similarity are as follows: the pressure anomaly is determined when the downward vertical torque transmitted by the pick-and-place machine nozzle is greater than a preset torque. The first pressure value of the pick-and-place machine nozzle is extracted based on the second texture feature, and the first pressure value is adjusted to the preset pressure value.

[0108] The preset pressure value is 0.032 MPa. When the first pressure value exceeds the preset pressure value within 0.0032 MPa, the upward movement speed of the pick-and-place machine nozzle is adjusted to 90% of the current speed. For every 0.0016 MPa exceeding 0.0032 MPa, the upward movement speed of the pick-and-place machine nozzle is reduced by 10%.

[0109] For example, if the first pressure value of the pick-and-place machine nozzle extracted by the second texture feature is 0.035MPa and the current upward movement speed is 10mm / s, which exceeds the preset pressure value of 0.003MPa, the adjusted upward movement speed of the pick-and-place machine nozzle is 10mm / s × 90% = 9mm / s;

[0110] For example, if the first pressure value of the pick-and-place machine nozzle extracted by the second texture feature is 0.038MPa and the current upward movement speed is 10mm / s, which exceeds the preset pressure value of 0.004MPa, the adjusted upward movement speed of the pick-and-place machine nozzle is 10mm / s × 80% = 8mm / s.

[0111] Specifically, when the vertical distribution height of the solder calculated from the Z-axis coordinate of the three-dimensional image is greater than the preset distribution height, the heating rate of the outer portion 5 of the attachment area is increased to a first heating rate, and the heating rate of the inner portion of the attachment area is decreased to a second heating rate, so as to guide the solder 2 to flow outward through the temperature gradient.

[0112] The attachment area is the three-dimensional space area of ​​the solder 2 of a single solder point corresponding to the component patch 1, which is identified by the contact boundary between the solder 2 and the PCB substrate in the three-dimensional image.

[0113] In practice, the first heating rate is positively correlated with the vertical distribution height of the solder, while the second heating rate is negatively correlated with the vertical distribution height of the solder.

[0114] The method for calculating the vertical distribution height is as follows:

[0115] Threshold segmentation is performed on solder pixels in the Z-axis direction of the 3D image to extract pixels with a height greater than 0.1 mm above the substrate surface, and their average Z-axis coordinate is calculated.

[0116] Specifically, the solder area within the range of the circumcircle drawn with the center point of the resistor as the center and the line segment formed by the line connecting the center point of the resistor to any projection endpoint as the radius is the inner part 6 of the attachment area; the solder area from the edge of the resistor to the boundary of the PCB pad 3 is the outer part 5 of the attachment area.

[0117] The definition of the attachment area, and what exactly are the outer and inner parts of the attachment area?

[0118] In a specific embodiment, the average Z-axis coordinate of 1000 effective pixels in the corresponding solder area is 0.32mm. The preset distribution height = tiling thickness × 1.5, i.e., 0.2mm × 1.5 = 0.3mm. Based on the fact that the measured vertical distribution height of 0.32mm is greater than the preset distribution height of 0.3mm, it is determined that there is a risk of solder 2 accumulation on the outer side. The first heating rate = first proportional coefficient × measured vertical distribution height, therefore the first heating rate = 10 × 0.32 = 3.2℃ / s; the first heating rate = second proportional coefficient / measured vertical distribution height, therefore the second heating rate = 1 / 0.32 = 3.125℃ / s.

[0119] The heating rate of the outer portion of the attachment area was increased to 3.2℃ / s;

[0120] The heating rate of the inner part of the attachment area was reduced to 3.125℃ / s, where,

[0121] The first and second proportional coefficients are determined based on the experimental variables set in the experiment. By selecting different measured vertical distribution heights (such as 0.2mm, 0.3mm, 0.4mm, etc. to cover the possible accumulation risk range), the outer heating rate corresponding to different proportional coefficients (such as 5, 8, 10, 12, etc.) is tested.

[0122] Specifically, the first heating rate is greater than the second heating rate.

[0123] In practice, the present invention adjusts the heating rate by calculating the vertical distribution height of solder 2 from the Z-axis coordinate of the three-dimensional image to be greater than the preset distribution height. This temperature gradient guides the solder 2 to flow outward, thereby compensating for the excessive vertical torque of the pick-and-place machine nozzle, which causes the solder 2 to accumulate on the outside.

[0124] Specifically, based on the inconsistency between the first texture feature and the second texture feature, that is, the similarity between the first texture feature and the second texture feature is less than 90%, the heating temperature of the dense region is increased and the heating temperature of the dispersed region is decreased.

[0125] In one specific embodiment, after the solder 2 has been actually heated, the solder 2 is cooled by air circulation until the temperature of the solder 2 drops below 50°C.

[0126] Specifically, after the multilayer PCB assembly board is formed, if the connection stability or power consumption of the IoT communication module does not meet the requirements, it is determined to be a defective situation, and the communication parameters are calibrated and the RF circuit design is optimized.

[0127] The calibration of communication parameters includes adjusting the transmission power of the communication module and optimizing the operating frequency of the communication module; the optimization of radio frequency circuit design includes adjusting the impedance matching of the radio frequency circuit and adding a shield or ground plane on the PCB board.

[0128] In practice, this invention verifies whether the button function of the portable air conditioner panel is normal by conducting button response tests, display driver tests, and connection stability tests of the IoT communication module, ensuring that the button response is sensitive, without delay or failure; verifies whether the display function of the portable air conditioner panel is normal, ensuring that the displayed content is clear, without flickering or misalignment; and verifies whether the IoT communication module of the portable air conditioner panel can stably connect to the network, ensuring the reliability and real-time performance of data transmission.

[0129] Working process: Solder 2 is evenly spread onto a multilayer PCB board to form a PCB mounting substrate. The PCB mounting substrate is heated at the spreading temperature of solder 2 to initially activate the solder 2. Component pads 1 are attached to the corresponding positions of pads 3 on the PCB mounting substrate using a pick-and-place machine nozzle. The pressure of the pick-and-place machine nozzle is adjusted according to process requirements to ensure stable component attachment. The solder 2 on the pre-fixed PCB board is sequentially heated to melt and then cooled to simulate the actual soldering process. A 3D scanner is used to acquire several frames of 3D images of solder 2 on pad 3. Based on the 3D images, dense regions where the solder density is greater than a first preset density and dispersed regions where the solder density is less than the first preset density are determined at the melting temperature of solder 2. Based on the duration of the dense and dispersed regions, the potential tear surface 4 that may occur during the heating process of solder 2 is located. The texture features of the predicted dense and dispersed regions on both sides of the potential tear surface 4 are extracted through the 3D images to simulate the texture features generated by the downward vertical torque transmitted by the pick-and-place machine nozzle. The first texture feature is compared with the second texture feature. If they match, it indicates that the downward vertical torque transmitted by the pick-and-place machine nozzle is too large. According to the first... The first pressure value of the pick-and-place machine nozzle is extracted based on the texture features and adjusted to a preset pressure value. Based on the consistent solder 2 distribution area with consistent texture features, the height of the heated solder 2 distribution is detected. The solder area within the range of the circumcircle drawn with the center point of the resistor as the center and the line segment connecting the center point of the resistor to any projected endpoint as the radius is the inner portion 6 of the mounting area; the solder area from the resistor edge to the boundary of the PCB pad 3 is the outer portion 5 of the mounting area. The heating rate of the outer portion 5 of the mounting area is increased to a first heating rate, and the heating rate of the inner portion 6 of the mounting area is decreased to a second heating rate, where the first heating rate is greater than the second heating rate. The heating rate is adjusted based on the vertical distribution height of the solder 2 calculated using the Z-axis coordinates of the 3D image, which is greater than the preset distribution height. This temperature gradient guides the solder 2 to flow outwards, compensating for the excessive vertical torque of the pick-and-place machine nozzle causing solder 2 accumulation on the outer side. The pre-fixed PCB board is heated, melted, and cooled according to a determined heating rate to ensure uniform distribution of solder 2. Components are securely fixed to their corresponding positions on the pre-fixed PCB board using optimized heating rates and nozzle pressure, forming a multi-layer PCB assembly. The multi-layer PCB assembly is then bonded to the portable air conditioner substrate to form a complete portable air conditioner panel. The button functions of the portable air conditioner panel are tested to ensure sensitive button response without delay or malfunction. The brightness, contrast, and refresh rate of the display screen are tested to ensure clear display content without flickering or misalignment. The connection stability and power consumption of the IoT communication module are tested; if requirements are not met, communication parameters are calibrated and the RF circuit design is optimized.

[0130] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A manufacturing process for a mobile air conditioner panel based on a multilayer PCB, characterized in that, include: Solder is spread evenly onto a multilayer PCB board to form a PCB mounting substrate; The component chip is attached to the corresponding chip position on the PCB mounting substrate by the nozzle of the chip mounter to form a pre-fixed PCB board; The solder on the pre-fixed PCB board is subjected to a melting and cooling test, and several frames of three-dimensional images of the solder on the pre-fixed PCB board are obtained. Based on the aforementioned three-dimensional images, dense and dispersed regions are determined; The solder tends to tear surface based on the duration of the dense region and the duration of the dispersed region; The texture features of the dense and dispersed regions on both sides of the tear surface are compared with the texture features generated during the component patch attachment process. If the texture features are consistent, the adhesion pressure generated by the nozzle is determined to be abnormal, and the nozzle pressure is re-determined based on the abnormal condition. The heating rates of the outer part of the attachment area and the inner part of the attachment area are determined based on the distribution height of the solder after heating, which has consistent texture characteristics. The pre-fixed PCB board is actually heated and cooled according to the heating rate to fix the components to the corresponding patch positions on the pre-fixed PCB board, forming a multilayer PCB assembly board; The multilayer PCB assembly board is bonded to the portable air conditioner substrate to form a portable air conditioner panel; The heating parameters on both sides of the tear surface are related to the duration. The duration is the time period from the start of the solder melting process at the melting temperature to the start of the cooling process. Heating parameters include the location of dense and dispersed regions and the heating temperature. As the duration of heating in both dispersed and dense regions increases, the heating temperature is gradually increased up to no more than 255℃. The formula for calculating the heating temperature and duration is as follows: Where T is the heating temperature. Let be the melting temperature, k be the temperature gradient coefficient, and t be the duration of the dispersed / dense region, where the durations of the dispersed and dense regions are equal. The melting temperature is the temperature at which the solder on the pre-fixed PCB board is melted and cooled during the test.

2. The manufacturing process for a mobile air conditioner panel based on a multilayer PCB according to claim 1, characterized in that, The step of determining the dense and dispersed regions based on the plurality of three-dimensional images includes: Extract the solder density from several equally spaced density sampling points in the aforementioned three-dimensional images; The largest closed three-dimensional region formed by connecting the first corresponding density sampling points that meet the solder density condition is defined as the dense region. The entire three-dimensional space of the solder occupied by the second corresponding density sampling point that does not meet the solder density condition is defined as the dispersion region.

3. The manufacturing process for a mobile air conditioner panel based on a multilayer PCB according to claim 2, characterized in that, The solder density condition is that the solder density at the density sampling point is greater than the preset density.

4. The manufacturing process for a mobile air conditioner panel based on a multilayer PCB according to claim 3, characterized in that, The tending tear surface is formed during the solder cooling process due to temperature gradient and heat dissipation differences, resulting in dense and dispersed regions. The interface between the largest closed three-dimensional regions of the dense and dispersed regions is the tending tear surface.

5. The manufacturing process for a mobile air conditioner panel based on a multilayer PCB according to claim 4, characterized in that, The comparison of the texture features of the dense and dispersed regions on both sides of the tear surface with the texture features generated during the component patch attachment process includes: First texture features of the predicted dense region and predicted dispersed region are extracted from the three-dimensional image of the pre-fixed PCB board; Acquire the second texture feature generated by the downward vertical torque transmitted by the simulated pick-and-place machine nozzle; The texture features of the predicted dense and predicted dispersed regions on both sides of the tearing surface are compared with the texture features generated by the downward vertical torque transmitted by the pick-and-place machine nozzle. If the similarity between the first texture feature and the second texture feature is greater than or equal to 90%, then the first texture feature and the second texture feature are determined to be consistent.

6. The manufacturing process for a mobile air conditioner panel based on a multilayer PCB according to claim 5, characterized in that, The specific criteria for determining pressure anomalies based on texture feature similarity are as follows: the pressure anomaly is determined when the downward vertical torque transmitted by the pick-and-place machine nozzle is greater than a preset torque. The first pressure value of the pick-and-place machine nozzle is extracted based on the second texture feature, and the first pressure value is adjusted to the preset pressure value.

7. The manufacturing process for a mobile air conditioner panel based on a multilayer PCB according to claim 6, characterized in that, When the vertical distribution height of the solder, calculated from the Z-axis coordinate of the 3D image, is greater than a preset distribution height, the heating rate of the outer portion of the attachment area is increased to a first heating rate, and the heating rate of the inner portion of the attachment area is decreased to a second heating rate. This is to guide the solder to flow outward through a temperature gradient. The attachment area is the three-dimensional space area of ​​the solder corresponding to a single solder joint of the component patch, which is identified by the contact boundary between the solder and the PCB substrate in the three-dimensional image.

8. The manufacturing process for a mobile air conditioner panel based on a multilayer PCB according to claim 7, characterized in that, The first heating rate is greater than the second heating rate.

9. The manufacturing process for a mobile air conditioner panel based on a multilayer PCB according to claim 5, characterized in that, If the similarity between the first texture feature and the second texture feature is less than 90%, then the heating temperature of the dense region is increased and the heating temperature of the dispersed region is decreased.

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