BGA repair equipment with adjustable air outlet

Abstract

The application discloses a BGA repair equipment with an adjustable air outlet, and relates to the technical field of BGA repair control. The BGA repair equipment comprises an adjusting mechanism, a baffle and a motor, and is used for adjusting the sectional area of the air outlet; a fan is used for providing airflow to the air outlet; a first sensor is used for collecting first temperature data of a first object; a control device is connected with the motor, the fan and the first sensor respectively; the control device is used for: acquiring distance data, wherein the distance data represents the distance between the edge of the first object and a second object; in the case that the first temperature data is in a preset temperature interval and the distance data is less than a first preset threshold, if a first instruction is acquired, the motor is controlled to increase the opening degree of the baffle to increase the sectional area, and a second instruction is sent to the fan; wherein the second instruction is used for indicating to reduce the rotating speed of the fan; and the application reduces the impact of airflow on surrounding elements.

Description

Technical Field

[0001] This invention relates to the technical field of BGA rework control, specifically to a BGA rework device with an adjustable air outlet. Background Technology

[0002] BGA chip soldering technology has become an essential key technology in the assembly of printed circuit boards, and the BGA rework station is an intelligent operation device for visual alignment, soldering, and disassembly of BGA components of different sizes.

[0003] Currently, adjustable air outlet BGA rework stations are standard equipment in the field of electronic manufacturing rework. For example, Chinese patent application CN118748868A discloses a BGA rework station with an air volume adjustment mechanism. It uses a brake motor to drive a baffle to change the air outlet blocking area, and outputs hot air in conjunction with a hot air fan. The conventional electrical control logic is to adjust the baffle opening and fan speed synchronously based on the temperature detection results to track the target temperature curve in a closed loop.

[0004] However, when such equipment is used to rework large-size, high-density PCBs, the substrate warps after crossing the glass transition temperature due to differences in thermal expansion coefficients and uneven wiring density, creating gaps between the BGA chip edges and the air outlet. When the system detects the edge temperature lag and simultaneously increases the baffle opening and fan speed, hot air leaks out through these gaps, resulting in insufficient heat for the edge solder ball area. At the same time, the leaked airflow blows directly onto surrounding heat-sensitive components such as plastic connectors and electrolytic capacitors. When the solder is in a molten state, this high-speed airflow can easily cause solder ball displacement or bridging defects, making it difficult to balance heat replenishment with soldering effect and component safety. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a BGA rework device with an adjustable air outlet.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: This invention provides a BGA rework device with an adjustable air outlet, comprising: The adjustment mechanism, including a baffle and a motor, is used to adjust the cross-sectional area of ​​the air outlet; A fan is used to provide airflow to the air outlet; The first sensor is used to collect the first temperature data of the first object; The control device is connected to the motor, the fan, and the first sensor, respectively. The control device is used for: Acquire distance data, which represents the distance between the edge of the first object and the second object; If the first temperature data is within a preset temperature range and the distance data is less than a first preset threshold, and a first instruction is received, the motor is controlled to increase the opening of the baffle to increase the cross-sectional area, and a second instruction is sent to the fan. The second instruction is used to instruct the fan speed to be reduced.

[0007] As a preferred embodiment of the present invention, the BGA rework equipment further includes a storage device, which is connected to the control device; The storage device stores type data and the corresponding upper limit value of rotational speed; The control device is also used for: If the first temperature data is within the preset temperature range, the maximum operating speed of the fan is determined as the upper limit value of the speed.

[0008] As a preferred embodiment of the present invention, the control device includes a first processing module and a second processing module; The first processing module is used to determine deviation data based on the distance data and the first preset threshold; The second processing module is used to determine a compensation coefficient based on the deviation data, calculate the initial speed of the fan with the compensation coefficient to obtain the target speed, and generate the second instruction based on the target speed.

[0009] As a preferred embodiment of the present invention, the compensation coefficient is positively correlated with the distance data, so that when the distance data decreases, the determined target rotation speed decreases accordingly.

[0010] As a preferred embodiment of the present invention, the BGA rework equipment further includes a second sensor, which is disposed around the air outlet and connected to the control device; The second sensor is used to acquire the distance data between the edge of the first object and the second object during device operation.

[0011] In a preferred embodiment of the present invention, the motor is connected to a plurality of baffles via a transmission assembly, and the plurality of baffles are distributed around the air outlet. The control device is also used for: By sending a control signal to the motor, multiple baffles are controlled to move synchronously to adjust the cross-sectional area.

[0012] As a preferred embodiment of the present invention, the control device is further used for: If the distance data is greater than or equal to the first preset threshold, and the first instruction is received, the motor is controlled to increase the opening of the baffle and the speed of the fan is increased.

[0013] As a preferred embodiment of the present invention, the BGA rework equipment further includes a heating device located below the support mechanism and connected to the control device; The control device is also used to: determine compensation data while controlling the reduction of the fan speed, and increase the operating parameters of the heating device based on the compensation data.

[0014] As a preferred embodiment of the present invention, the BGA rework equipment further includes a temperature acquisition component, which includes the first sensor and at least one third sensor, wherein the third sensor is disposed at the edge of the first object; The control device is also used for: Acquire the first temperature data collected by the first sensor, and acquire the second temperature data collected by the third sensor; Based on the first temperature data and the second temperature data, the difference data is obtained; If the difference data is greater than a second preset threshold, the first instruction is generated.

[0015] As a preferred embodiment of the present invention, the control device further includes a third processing module; The third processing module is used to control the fan speed to recover in an incremental manner within a preset time period when the first temperature data is detected to be greater than the upper limit of the preset temperature range.

[0016] The beneficial effects of this invention are: This invention, by setting up an adjustment mechanism, a fan, a first sensor, and a control device, allows the control device to selectively control the motor to increase the baffle opening and instruct the fan to reduce its speed when it receives a first instruction, based on the preset temperature range where the first temperature data is located and the comparison result between the distance data and the first preset threshold. This enables the air outlet parameters to be adjusted differently according to the size of the gap formed by substrate warping. When the gap is small, by increasing the air outlet cross-sectional area and reducing the wind speed, the heat supply to the chip edge is maintained while the leakage speed of the airflow at the gap is suppressed, reducing the impact of the airflow on surrounding components. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0018] Figure 1 This is a schematic diagram of the control signals for the BGA rework equipment with adjustable air outlet of the present invention.

[0019] Figure 2 This is a logic flowchart of the control device of the present invention performing adjustment actions.

[0020] Figure 3 This is a block diagram showing the internal module connection of the control device of the present invention.

[0021] Figure 4 This is a schematic diagram showing the gap formed by substrate warping during the BGA rework process of this invention. Detailed Implementation

[0022] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments. The components of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0023] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this application, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0024] like Figures 1-4 As shown, this embodiment provides a BGA rework device with an adjustable air outlet. The device includes an adjustment mechanism, a fan, a first sensor, and a control device.

[0025] The regulating mechanism, as the actuator for changing the physical cross-sectional area of ​​the air outlet, includes a baffle and a motor that drives the baffle. The baffle is set in the air duct of the air outlet. The motor drives the baffle to move by receiving control signals from the control equipment, thereby changing the cross-sectional area of ​​the air outlet that can be used for hot air to pass through. The fan is connected to the air passage of the air outlet and is used to provide a hot airflow with a certain velocity and dynamic pressure to the air outlet at an adjustable speed under the command of the control equipment.

[0026] The first sensor is used to collect the first temperature data of the first object, which is the target body that needs to be heated in the rework operation, such as a BGA chip. The first temperature data represents the real-time process temperature of the target body during the rework heating process. The first sensor can be arranged inside the air outlet, directly above or near the BGA chip, and can be implemented using a thermocouple or an infrared temperature probe.

[0027] The control device is connected to the aforementioned motor, fan, and first sensor to receive the first temperature data and issue control commands to the motor and fan accordingly.

[0028] During the rework heating process, the control device is also configured to acquire distance data, which represents the distance between the edge of the first object and the second object. The second object is a structure that is spatially adjacent to the first object, such as a metal shield around a BGA chip, a plastic connector socket, or an aluminum electrolytic capacitor. The specific method of acquiring the distance data can be pre-entered by offline parsing of PCB board design files, or it can be collected online by the second sensor mounted on the device. This embodiment does not specifically limit this.

[0029] If the control device receives a first instruction when the first temperature data is within a preset temperature range and the distance data is less than a first preset threshold, it will perform an adjustment action. The preset temperature range corresponds to the process temperature window where the solder used for the current rework is in a solid-liquid coexistence state. The first preset threshold is a pre-calibrated physical gap critical value. When the actual distance data is less than this value, it indicates that the airflow velocity of the wedge-shaped gap formed by substrate warping may exceed the limit when the baffle is opened. The first instruction is an instruction to increase the hot air supply, which can be generated by the control device based on the deviation between the first temperature data and the target process temperature.

[0030] When both of the above conditions are met, the control equipment no longer performs the conventional linkage operation of increasing the baffle opening and the fan speed synchronously. Instead, it controls the motor to increase the opening of the baffle to increase the cross-sectional area of ​​the air outlet, and at the same time sends a second command to the fan to instruct it to reduce the fan speed.

[0031] By increasing the cross-sectional area and reducing the rotation speed, the heat exchange coverage area gain brought about by the increase in the outlet cross-sectional area, combined with the airflow impact suppression brought about by the reduction in outlet airflow velocity, not only transfers heat to the solder balls at the chip edge, but also suppresses the tendency of airflow to accelerate side leakage in the warped gap from the airflow path.

[0032] Furthermore, the BGA rework equipment in this embodiment also includes a storage device. This storage device is connected to the control device and is used to provide the control device with pre-stored process parameter data.

[0033] The storage device stores type data and the corresponding maximum rotational speed value. The type data indicates the specific type of solder used in the current rework operation, such as SAC305 lead-free solder, SnPb eutectic solder, etc.

[0034] The upper limit of the rotational speed is a fan speed limit that has been calibrated through pre-testing. At this speed, the outflow dynamic pressure generated at the air outlet will not cause the corresponding type of solder to shift or bridge when it is in a molten state in the solid-liquid coexistence zone.

[0035] Different types of solders have different molten viscosity and surface tension within the solid-liquid coexistence temperature range, and therefore the upper limit of safe exhaust dynamic pressure they can withstand is also different.

[0036] Taking SAC305 lead-free solder as an example, its solid-liquid coexistence range is 183℃ to 217℃. Within this temperature range, the solder is in a paste or liquid state, and its shear resistance decreases. During the calibration phase of the rework equipment, for this type of solder, air outlet tests are conducted at different fan speeds under the condition of an outlet air temperature of approximately 230℃ to 250℃. The displacement of the solder balls is observed at the corresponding speed, and the maximum speed at which the solder balls do not displace is recorded as the upper limit of the speed corresponding to this type of solder.

[0037] After the upper limit of rotation speed corresponding to each type of solder is pre-calibrated, a mapping relationship is formed by using the type data as an index and the upper limit of rotation speed as the corresponding value and stored in the storage device.

[0038] During the rework heating process, the control equipment continuously acquires the first temperature data collected by the first sensor.

[0039] When the first temperature data enters the preset temperature range, that is, the solid-liquid coexistence temperature range of the current solder type, the control device retrieves the upper limit value of the rotation speed corresponding to the current type of data from the storage device, and determines the maximum operating speed of the fan as the upper limit value of the rotation speed. Thereafter, regardless of whether the conventional temperature difference compensation logic requires a higher rotation speed to accelerate the heating rate, the actual rotation speed of the fan is limited to the upper limit value of the rotation speed.

[0040] Furthermore, the control device includes a first processing module and a second processing module. The first processing module is used to receive distance data and a first preset threshold, and process the two to determine deviation data.

[0041] Deviation data indicates the degree to which the physical gap between the edge of the first object and the second object deviates from the critical value.

[0042] The second processing module is connected to the first processing module and is used to receive deviation data and determine the compensation coefficient based on the deviation data. The compensation coefficient is used to represent the proportion by which the fan speed needs to be reduced.

[0043] The second processing module calculates the initial rotational speed of the fan with the compensation coefficient to obtain the target rotational speed, and generates a second instruction based on the target rotational speed.

[0044] The first processing module, after acquiring the distance data d and the first preset threshold d th , calculates the deviation ratio R of the two to quantify the degree to which the current physical gap deviates from the critical value, and the deviation ratio R is calculated as follows: ; where d is the distance data, representing the actual physical gap value between the edge of the first object and the second object; d th is the first preset threshold, that is, the critical physical gap value for jet risk pre-calibrated through engineering tests or fluid dynamics simulations. When the actual gap is less than this value, opening the baffle at the conventional fan rotational speed will generate a high-speed jet that exceeds the withstand limit of surrounding sensitive components; R is the deviation ratio.

[0045] When the distance data d is less than the first preset threshold d th , the smaller d is, the narrower the wedge-shaped gap formed by substrate warpage, the more significant the Venturi acceleration effect generated when the airflow passes through the gap, and the higher the jet risk. At this time, the value of (d th -d) increases, and the deviation ratio R increases accordingly.

[0046] When d approaches 0, R approaches 1; when d approaches d th , R approaches 0. When d is greater than or equal to d th , R is set to 0, indicating no deviation, and the above reverse adjustment action is not triggered.

[0047] After the first processing module determines the deviation ratio R, the second processing module calculates the speed reduction compensation coefficient K based on R, and K is calculated as follows: ; where K is the compensation coefficient, with a value range of 0<K≤1; α is a preset adjustment factor, with a value range of 0<α≤1; R is the deviation ratio output by the first processing module.

[0048] As the adjustment factor, α functions to map the deviation ratio R to a reasonable speed reduction range. The reason for introducing α is that in actual engineering, it is not appropriate to reduce the fan rotational speed to an extremely low value just because the physical gap is slightly reduced, and excessive speed reduction may lead to a serious insufficient heating rate.

[0049] Therefore, when d decreases, (d thAs -d) increases, R increases, meaning the deviation ratio R is negatively correlated with the distance data d. When R increases, K decreases, meaning the compensation coefficient K is negatively correlated with the deviation ratio R. Through the above two transmissions: d decreases → R increases → K decreases, the compensation coefficient K is positively correlated with the distance data d.

[0050] The specific value of α needs to be determined through a limited number of tests, taking into account the fan characteristics of the target equipment to be repaired, the common outlet air temperature range, and the temperature resistance rating of surrounding sensitive components.

[0051] For a typical BGA rework station with an outlet air temperature of 230℃ to 250℃ and a fan rated speed of approximately 3000 to 5000 rpm, the recommended value for α is 0.5 to 0.8.

[0052] Taking α as 0.7 as an example, when the actual physical gap is only 10% of the critical threshold (i.e., R=0.9), the compensation coefficient K=1-0.7×0.9=0.37; When the physical gap approaches the critical threshold (i.e., R approaches 0), K approaches 1, and the fan speed hardly needs to be reduced further; it only needs to maintain the upper limit of the speed.

[0053] After obtaining the compensation coefficient K, the second processing module calculates the initial speed n0 of the fan using K to obtain the target speed n. target : ; Where n0 is the initial speed of the fan, and the specific method for determining the initial speed is as follows: before the above-mentioned reverse adjustment action is triggered, the fan speed has been limited to the upper limit value of the speed corresponding to the current type of data, and n0 is this upper limit value of the speed. target The target rotational speed is the fan speed value required to generate the second command.

[0054] Furthermore, the BGA rework device in this embodiment also includes a second sensor, which is located on the periphery of the air outlet and connected to the control device.

[0055] The second sensor is used to acquire distance data during device operation, which represents the actual physical gap value between the edge of the first object and the second object.

[0056] Unlike the method of obtaining distance data by offline parsing of PCB board design files before the heating process starts, the second sensor provides a means of obtaining distance data online in real time.

[0057] The warping of the substrate during the heating process is a dynamic evolution process. The degree of warping and the width of the resulting wedge-shaped gap change in real time with the temperature. By acquiring distance data online through a second sensor set around the air outlet, the distance data obtained by the control device can reflect the real physical state of the substrate warping at the current moment, rather than the static prediction before the heating starts.

[0058] In practical engineering implementation, the second sensor can be a laser displacement sensor, installed on the side wall or bottom edge of the air outlet nozzle. Its detection spot is projected onto the gap area between the edge of the first object and the second object, and the physical width of the gap is calculated in real time by triangulation or time-of-flight method.

[0059] The second sensor can also be a non-contact eddy current displacement sensor or an ultrasonic ranging sensor, as long as it can withstand the high temperature environment near the air outlet and continuously output the gap value during the rework heating process.

[0060] Furthermore, the motor is connected to multiple baffles via a transmission assembly, which are distributed around the air outlet. The transmission assembly is used to convert the rotational motion of the motor output shaft into the translational or oscillating motion of the multiple baffles.

[0061] In one implementation, the transmission component can be a gear and rack pair, a cam linkage mechanism, or a synchronous belt pulley system, as long as it can transmit the power of a single motor to each baffle. Multiple baffles are circumferentially distributed around the cross-section of the air duct at the air outlet, and part or all of the surface of each baffle forms a variable shielding area within the air duct.

[0062] The control device sends a control signal to the motor to control multiple baffles to move synchronously to adjust the cross-sectional area of ​​the air outlet. The multiple baffles move simultaneously under the action of the same control signal, increasing or decreasing their respective degree of obstruction to the air duct at the same time, rather than moving independently in different directions or with different amplitudes.

[0063] When the control device triggers the above-mentioned reverse adjustment action and instructs the motor to increase the opening of the baffle, the motor drives multiple baffles distributed around the air outlet to open synchronously through the transmission component, thereby increasing the overall flow cross-sectional area of ​​the air outlet. Hot air flows out evenly or nearly evenly from the synchronously expanded air duct cross-section around the outlet, increasing the heat exchange coverage area with the chip surface.

[0064] At the same time, the control equipment sends a second command to the fan to reduce the speed, which reduces the overall airflow velocity. The increased cross-sectional area, combined with the reduced velocity, maintains the coverage of hot air on the chip edge solder balls and the heat exchange efficiency, while suppressing the acceleration effect of airflow in the warped wedge-shaped gap.

[0065] Furthermore, when the control device receives the first instruction that it needs to increase the supply of hot air, the control device first compares the distance data with the first preset threshold.

[0066] When the distance data is greater than or equal to the first preset threshold, it indicates that the actual physical gap between the edge of the first object and the second object is large enough. At this time, the wedge gap caused by the warping of the substrate is not enough to form a high-speed airflow at the normal fan speed. The flow rate of the side leakage airflow does not reach the level of exceeding the temperature-wind speed combined damage threshold of the surrounding sensitive components. Therefore, the second judgment condition is not met.

[0067] If the second condition is not met, the control equipment will not perform the reverse adjustment action, but will instead follow the conventional logic of forward linkage between the damper opening and the fan speed: The motor is controlled to increase the opening of the baffle to increase the cross-sectional area of ​​the air outlet, while simultaneously increasing the fan speed.

[0068] Increasing the cross-sectional area expands the heat exchange coverage area between the hot air and the chip surface, while increasing the fan speed increases the airflow velocity. The two work together to provide a larger volume of hot air to compensate for the heat in the solder ball area at the chip edge.

[0069] It should be noted that if the second determination condition is not met but the first determination condition is met (i.e., the first temperature data is within the preset temperature range), the increase in fan speed is still constrained by the upper limit of the speed.

[0070] In other words, even if the speed reduction action in the reverse adjustment is not required at this time, the maximum operating speed of the fan must not exceed the upper limit of the speed corresponding to the current type of data.

[0071] This constraint ensures that during the solid-liquid coexistence phase of the solder, the exhaust pressure is always limited to the range that the solder can withstand in its molten state, regardless of whether a reverse adjustment action is triggered.

[0072] Furthermore, when the control device performs the action of increasing the cross-sectional area and reducing the speed, that is, controlling the motor to increase the baffle opening to increase the cross-sectional area of ​​the air outlet, and at the same time sending a second command to the fan to reduce the fan speed, the total amount of heat transferred by the top hot air to the chip solder ball area may be reduced due to the fan speed reduction.

[0073] In certain operating conditions, such as when the PCB board to be repaired has a large area of ​​grounded copper foil, strong bottom heat dissipation, or the chip itself has a large heat capacity, simply relying on increasing the heat exchange area expanded by increasing the baffle opening is not enough to fully compensate for the convective heat transfer efficiency lost due to the fan speed reduction. In this case, within the safety constraints of the solder being in the molten and fragile stage, it is necessary to introduce an additional heat source to supplement the heat of the chip solder ball area.

[0074] Therefore, the BGA rework equipment in this embodiment also includes a heating device, which is located below the support mechanism and connected to the control device. The support mechanism is a platform or fixture used to support and fix the PCB board to be reworked during the rework operation.

[0075] The heating device is located below the support structure, with its heat output direction facing the bottom surface of the PCB board. It preheats or compensates for the heat of the PCB board and its BGA chips from the bottom through heat radiation or heat conduction. The heating device can be an infrared heating tube array, a resistance heating plate, or other bottom heat source with controllable and adjustable output power.

[0076] When the reverse adjustment action is triggered and the control equipment sends a second command to the fan to reduce the fan speed, the control equipment simultaneously determines the compensation data.

[0077] The compensation data is the bottom heating compensation amount corresponding to the reduction in heat input to the target chip solder ball area caused by the reduction in the speed of the top fan.

[0078] The specific method for determining the compensation data can be as follows: The control equipment is based on the reduction in fan speed (i.e., the initial speed n0 and the target speed n calculated from the compensation coefficient K). target The difference between the two values ​​is used to estimate the reduction in top heat input by combining the preset mapping relationship between fan speed and top convection heat transfer power. This reduction is then converted into the increment of the operating parameters required to be improved by the heating equipment.

[0079] The mapping relationship between fan speed and top convection heat transfer power can be obtained by querying the factory performance parameters of the selected fan, or by pre-testing the outlet air parameters at different speeds and calculating them.

[0080] The compensation data can also be obtained by the control equipment through real-time monitoring of the first temperature data of the BGA chip solder ball area. When it is detected that the heating rate drops below the preset compensation trigger threshold due to the fan speed reduction, the deviation of the heating rate is calculated in a closed loop.

[0081] The control device generates adjustment commands for the heating device based on the compensation data, and increases the operating parameters of the heating device. The operating parameters can be the output power, duty cycle or operating current of the heating device. The bottom heating device supplements heat to the BGA chip solder ball area through the PCB substrate by means of infrared radiation or contact heat conduction.

[0082] Since the heat transfer path of bottom heating is through the PCB substrate from bottom to top, its heat flow direction is not affected by the wedge-shaped gap formed by the warping of the upper surface of the substrate, and will not aggravate the side leakage jet. The heat input reduced by the speed reduction of the top fan during the reverse adjustment action is compensated by the power increase of the bottom heating equipment. While maintaining the safe limit of the air dynamic pressure during the solder melting vulnerable period, the total heat input is maintained to meet the process requirements of solder ball melting.

[0083] Furthermore, the BGA rework equipment also includes a temperature acquisition component, which comprises a first sensor and at least one third sensor.

[0084] The first sensor is used to collect the first temperature data of the first object, and its setting position corresponds to the central area of ​​the first object or a position that can reflect the overall process temperature of the chip.

[0085] The third sensor is positioned at the edge of the first object to collect temperature data of the edge region of the first object.

[0086] When a finer-grained sensing of temperature distribution at different edges of the chip is required, the temperature acquisition component can include multiple third sensors, each positioned at a different edge of the first object.

[0087] During the rework heating process, the control equipment acquires the first temperature data collected by the first sensor and the second temperature data collected by the third sensor.

[0088] The first temperature data represents the real-time process temperature of the chip's center or main area, while the second temperature data represents the real-time process temperature of the chip's edge area.

[0089] The control device calculates the difference between the first temperature data and the second temperature data to obtain the difference data, which reflects the degree of temperature non-uniformity between the center and the edge of the chip.

[0090] The control device compares the difference data with a second preset threshold. The second preset threshold is a preset temperature difference judgment limit. When the center-edge temperature difference exceeds this threshold, it indicates that the temperature lag in the edge solder ball area has reached a level that requires additional hot air reheating.

[0091] The specific value of the second preset threshold can be determined according to the rework process requirements. For example, for the reflow process of SAC305 solder, the second preset threshold can be set to a value between 5°C and 10°C to trigger the heat replenishment action before the temperature difference becomes too large.

[0092] When the difference data is greater than the second preset threshold, the control device generates a first instruction, which is an instruction to increase the supply of hot air.

[0093] Before entering the reverse adjustment action logic, the first instruction is used to trigger the synchronous increase of the baffle opening and the fan speed. After entering the reverse adjustment action logic, the first instruction needs to be judged by two conditions, namely whether the first temperature data is within the preset temperature range and whether the distance data is less than the first preset threshold. When both conditions are met, the control device executes the reverse adjustment action of increasing the baffle opening and decreasing the fan speed, rather than the synchronous increase action.

[0094] Furthermore, the control device also includes a third processing module, which is used to perform a gradual recovery of the fan speed after the first temperature data deviates from the preset temperature range.

[0095] One of the prerequisites for triggering the reverse adjustment action is that the first temperature data is within the preset temperature range, that is, the solder is in a state of solid-liquid coexistence and weak shear resistance.

[0096] When the first temperature data is greater than the upper limit of the preset temperature range, it indicates that the current process temperature has exceeded the solid-liquid coexistence termination temperature threshold of the solder (e.g., 217℃ for SAC305 solder). The solder has basically completed melting and collapse, and its shear resistance will recover as the temperature continues to rise or enters the peak heat preservation stage.

[0097] After detecting that the first temperature data is greater than the upper limit of the preset temperature range, the third processing module controls the fan speed to recover in an incremental manner within a preset time period.

[0098] The preset time period is the transition window from exiting the reverse adjustment action state to fully restoring normal control.

[0099] If the fan speed is instantly changed from the speed reduction compensation value under reverse regulation to the target speed value calculated by the conventional PID algorithm using a step method, the sudden change in the outlet airflow velocity will create a transient airflow impact on the BGA chip solder joint area, which may cause micro-cracks in the already cured or curing solder joints, and may also cause instantaneous oscillations in the temperature field, affecting the stability of temperature control.

[0100] The incremental method refers to gradually increasing the fan speed from the current value (i.e., the target speed n calculated by the compensation coefficient K in the reverse adjustment action) within a preset time period. target The speed is gradually increased in multiple steps until the target speed value after exiting is reached.

[0101] The incremental increase can be implemented linearly, meaning the speed is increased at equal intervals and magnitudes within the transition time window; or it can be an S-shaped curve increase, starting with a smaller slope in the initial transition phase, accelerating in the middle, and then approaching the target value with a smaller slope at the end, making the speed change smoother. The duration of the preset time period can be set according to the fan response characteristics and process requirements, typically ranging from 5 to 10 seconds.

[0102] As the fan speed recovers incrementally, the control equipment simultaneously transitions the damper opening from the opening value in the reverse adjustment mode to the target opening value under the conventional control algorithm. This maintains the coordination and matching between the damper opening and the fan speed during the exit process, preventing temporary mismatch of hot air parameters due to asynchronous recovery of the two.

[0103] It should be noted that during the heating process after exiting, if the first temperature data falls back to the preset temperature range due to process adjustments or temperature fluctuations, the control device will re-enter the judgment cycle of the first judgment condition. All the aforementioned reverse adjustment action logic, including the speed limit lock of the first judgment condition, the airflow impact risk prediction of the second judgment condition, and the execution of the reverse adjustment action when the dual judgment conditions are met, can be triggered again, forming a re-entrant closed loop of the reverse adjustment action.

[0104] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A BGA rework device with an adjustable air outlet, characterized in that, include: The adjustment mechanism, including a baffle and a motor, is used to adjust the cross-sectional area of ​​the air outlet; A fan is used to provide airflow to the air outlet; The first sensor is used to collect the first temperature data of the first object; The control device is connected to the motor, the fan, and the first sensor, respectively. The control device is used for: Acquire distance data, which represents the distance between the edge of the first object and the second object; If the first temperature data is within a preset temperature range and the distance data is less than a first preset threshold, and a first instruction is received, the motor is controlled to increase the opening of the baffle to increase the cross-sectional area, and a second instruction is sent to the fan. The second instruction is used to instruct the fan speed to be reduced.

2. The BGA rework equipment with adjustable air outlet according to claim 1, characterized in that, The BGA rework equipment also includes a storage device, which is connected to the control device. The storage device stores type data and the corresponding upper limit value of rotational speed; The control device is also used for: If the first temperature data is within the preset temperature range, the maximum operating speed of the fan is determined as the upper limit value of the speed.

3. The BGA rework equipment with adjustable air outlet according to claim 1, characterized in that, The control device includes a first processing module and a second processing module; The first processing module is used to determine deviation data based on the distance data and the first preset threshold; The second processing module is used to determine a compensation coefficient based on the deviation data, calculate the initial speed of the fan with the compensation coefficient to obtain the target speed, and generate the second instruction based on the target speed.

4. The BGA rework equipment with adjustable air outlet according to claim 3, characterized in that, The compensation coefficient is positively correlated with the distance data, so that when the distance data decreases, the determined target rotational speed decreases accordingly.

5. The BGA rework equipment with adjustable air outlet according to claim 1, characterized in that, The BGA rework equipment also includes a second sensor, which is located around the air outlet and connected to the control device. The second sensor is used to acquire the distance data between the edge of the first object and the second object during device operation.

6. The BGA rework equipment with adjustable air outlet according to claim 1, characterized in that, The motor is connected to multiple baffles via a transmission assembly, and the multiple baffles are distributed around the air outlet; The control device is also used for: By sending a control signal to the motor, multiple baffles are controlled to move synchronously to adjust the cross-sectional area.

7. A BGA rework device with an adjustable air outlet according to claim 1, characterized in that, The control device is also used for: If the distance data is greater than or equal to the first preset threshold, and the first instruction is received, the motor is controlled to increase the opening of the baffle and the speed of the fan is increased.

8. The BGA rework equipment with adjustable air outlet according to claim 1, characterized in that, The BGA rework equipment also includes a heating device located below the support mechanism and connected to the control device; The control device is also used to: determine compensation data while controlling the reduction of the fan speed, and increase the operating parameters of the heating device based on the compensation data.

9. A BGA rework device with an adjustable air outlet according to claim 1, characterized in that, The BGA rework equipment also includes a temperature acquisition component, which includes the first sensor and at least one third sensor, wherein the third sensor is disposed at the edge of the first object; The control device is also used for: Acquire the first temperature data collected by the first sensor, and acquire the second temperature data collected by the third sensor; Based on the first temperature data and the second temperature data, the difference data is obtained; If the difference data is greater than a second preset threshold, the first instruction is generated.

10. A BGA rework device with an adjustable air outlet according to claim 1, characterized in that, The control device also includes a third processing module; The third processing module is used to control the fan speed to recover in an incremental manner within a preset time period when the first temperature data is detected to be greater than the upper limit of the preset temperature range.

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