Partition type PCB glue filling heat dissipation system and method for high-end chip package

Abstract

This invention relates to the field of electronic component packaging and heat dissipation technology, specifically disclosing a partition-type PCB potting heat dissipation system and method for high-end chip packaging. The system includes a partition-type potting cavity, a multi-zone independent temperature control unit, a colloid flow monitoring unit, and a closed-loop feedback control unit. This invention constructs a closed-loop intelligent control system that deeply integrates real-time monitoring, model prediction, and actuator regulation. The system not only relies on a preset colloid rheology model but also utilizes real-time data such as ultrasonic viscosity monitoring and laser thickness measurement verification, and employs an online parameter identification algorithm to continuously correct the model. This enables the system to adapt to performance fluctuations in different batches of materials and dynamic changes in the process, transforming the potting process from an open-loop, passive physical filling into a closed-loop, predictable, and optimizable intelligent manufacturing process, thereby stably producing high-end chip heat dissipation packages with high consistency and high reliability.

Description

Technical Field

[0001] This invention belongs to the field of electronic component packaging and heat dissipation technology, specifically relating to a partition-type PCB potting heat dissipation system and method for high-end chip packaging. Background Technology

[0002] In the field of microelectronic packaging technology, efficient heat dissipation is one of the core challenges in ensuring the stable operation of high-performance chips. As chip power density continues to rise, traditional heat dissipation methods such as air cooling and heat pipes are no longer sufficient to meet the heat dissipation requirements of high-end chips. Using potting compounds with high thermal conductivity to fill and encapsulate printed circuit boards has become a key technical path to improve system-level heat dissipation capabilities.

[0003] The potting heat dissipation technology for PCBs aims to inject liquid thermally conductive adhesive into the microchannels or cavities formed by the PCB board and the heat dissipation structure. After curing, it forms a uniform thermally conductive medium layer, thereby establishing an efficient heat conduction path to quickly conduct the heat generated by the chip to the external heat sink.

[0004] Existing technologies typically employ passive dispensing methods with pre-set injection and venting ports, relying on the self-leveling properties of the adhesive to complete the filling. However, this method lacks real-time thermal management and feedback control of the dispensing process. Due to the uneven distribution of heat sources on the PCB board surface, the temperature field at the flow front of the adhesive within the microchannels varies, leading to localized changes in its viscosity and curing rate. This, in turn, causes uneven distribution of the adhesive within the channels, particularly in areas with high heat flux density, where problems such as excessively thin adhesive layers or incomplete filling can easily occur.

[0005] This thickness deviation directly increases local thermal resistance, making the overall heat dissipation efficiency of the package unstable and highly volatile, failing to precisely match the stringent temperature uniformity and reliability requirements of high-end chips. Therefore, achieving precise thermal control during the potting process to ensure uniform distribution of the adhesive under complex thermal fields has become an urgent technical challenge. Summary of the Invention

[0006] The purpose of this invention is to provide a partition-type PCB potting heat dissipation system and method for high-end chip packaging, so as to solve the technical contradiction in the prior art where uneven heat source distribution on the PCB surface leads to temperature field differences at the flow front of the potting adhesive in the microchannel, which in turn causes local changes in adhesive viscosity and curing rate, ultimately resulting in uneven adhesive layer distribution and increased local thermal resistance.

[0007] To achieve the above objectives, this invention provides a partition-type PCB potting and heat dissipation system for high-end chip packaging. The system includes a partition-type potting cavity, a multi-zone independent temperature control unit, a colloid flow monitoring unit, and a closed-loop feedback control unit.

[0008] The partition-type potting cavity is used to accommodate the PCB assembly to be potted and to create a controlled potting environment. The cavity consists of a bottom base, a top cover, and a set of liftable thermally conductive partitions located inside the cavity. The bottom base integrates positioning grooves and a vacuum suction hole array that match the contour of the back of the PCB board for precise fixation of the PCB board.

[0009] The top cover has a micro piezoelectric ceramic array encapsulated on its inner side, corresponding to the chip layout on the front of the PCB. The liftable thermally conductive partition is made of a highly thermally conductive metal material, with a thickness of 0.5 mm to 2 mm, and there are more than two of them.

[0010] These partitions are initially arranged at equal intervals parallel to the long side of the PCB board, dividing the internal space of the cavity into multiple independent sub-potting areas.

[0011] Each partition has a height-adjustable gap between its lower edge and the PCB surface. This gap serves as the only channel for the colloid to flow between adjacent sub-regions. Its height is precisely adjusted by miniature linear motors integrated at both ends of the partition, with an adjustment range of 50 micrometers to 500 micrometers.

[0012] The multi-zone independent temperature control unit is used to implement independent and precise temperature control for each sub-area of ​​the partition-type glue-filling cavity.

[0013] The unit includes multiple thin-film heaters embedded below the positioning groove of the bottom base, a multi-channel microfluidic system integrated inside the liftable thermally conductive partition, and an external precision circulating liquid cooler.

[0014] The thin-film heaters are arranged in zones based on sub-potting areas, and the heating power of each zone is independently adjustable.

[0015] The microchannels integrated inside the heat-conducting partitions are connected to a precision circulating liquid cooler. By adjusting the temperature and flow rate of the coolant flowing through each partition, the temperature of the partition itself can be independently controlled.

[0016] The thin-film heater and the partition microchannel work together to create an independent and controllable temperature field in each sub-potting area.

[0017] The colloidal flow monitoring unit is used to acquire the flow state and physical parameters of the colloidal substance in each sub-dose area during the dispensing process in real time.

[0018] The unit includes a distributed infrared thermal imager array arranged inside the top cover plate, a miniature ultrasonic probe array integrated into the airflow surface of the liftable heat-conducting baffle, and a laser triangulation thickness sensor set on the side wall of the cavity.

[0019] A distributed infrared thermal imager array is used to acquire two-dimensional temperature distribution maps of the front side of a PCB board and the flow front of colloids at a sampling rate of more than 10 frames per second.

[0020] A miniature ultrasonic probe array is used to transmit and receive ultrasonic signals. By analyzing the propagation speed and attenuation characteristics of ultrasonic waves in colloids, the viscosity and degree of curing of the colloid in the current region can be inverted in real time.

[0021] Laser triangulation thickness sensors are used to measure the real-time thickness of the adhesive layer at different locations on a PCB board before curing, along a preset scanning path during the colloid filling process.

[0022] The closed-loop feedback control unit is used to dynamically adjust the multi-zone independent temperature control unit and the actuator of the partition-type dispensing cavity based on the data collected in real time by the colloid flow monitoring unit, so as to achieve precise thermal management of the dispensing process.

[0023] The core of this unit is a multiple-input multiple-output controller.

[0024] The controller has a pre-stored rheological model of the target potting compound, which describes the quantitative relationship between the compound viscosity, curing rate and temperature.

[0025] During the dispensing process, the controller continuously receives temperature distribution data from the infrared thermal imager array, viscosity and curing degree data from the ultrasonic probe array, and adhesive layer thickness data from the laser thickness sensor.

[0026] Based on this real-time data, the controller's control logic is as follows:

[0027] First, the controller compares the PCB surface temperature distribution obtained by the infrared thermal imager with the preset chip heat source distribution map to identify high heat flux density sub-regions where the current temperature is greater than the preset threshold.

[0028] Next, the controller retrieves the ultrasonic viscosity data corresponding to these high heat flux density sub-regions.

[0029] If the controller detects that the viscosity of the colloid in a certain sub-region falls below the set lower limit due to temperature rise, it immediately sends a command to the multi-zone independent temperature control unit to reduce the power of the bottom film heater acting on that sub-region, while increasing the flow rate of the coolant flowing through the adjacent thermally conductive partition in that region, thereby implementing local cooling of that sub-region and causing the viscosity of the colloid to rise back to the target range.

[0030] Conversely, if the controller detects that a certain sub-region has excessively high colloid viscosity and slow flow due to low temperature, it will instruct to increase the heating power at the bottom of that region and reduce the cooling intensity of the partition to promote colloid flow.

[0031] Furthermore, the controller's regulation logic also includes coordinated control of the gaps between the liftable thermally conductive baffles. During the initial dispensing stage, all baffle gaps are set to a maximum value of 500 micrometers to allow the adhesive to quickly fill the main channel.

[0032] When the flow front of the colloid approaches a certain baffle, the controller dynamically calculates the optimal gap height based on the real-time viscosity difference and temperature difference between the sub-regions on both sides of the baffle.

[0033] If the viscosity of the colloid is low and the flow rate is fast in the upstream region, while the viscosity tends to increase in the downstream region due to its proximity to the heat source, the controller will instruct the gap between the baffles to increase the flow resistance, balance the colloid flow rate and filling pressure in the upstream and downstream regions, and prevent the colloid from flowing too fast in the low viscosity region, resulting in insufficient filling at the far end.

[0034] The adhesive layer thickness data fed back by the laser triangulation thickness sensor is used for final verification. When the adhesive layer thickness at any location is detected to deviate from the target thickness by more than the specified value, i.e. ±5%, the controller will trace the historical temperature control and partition gap adjustment records of the sub-region to which that location belongs, perform self-correction on the control parameters, and update the corrected parameters into the rheological model.

[0035] In one embodiment of the present invention, the partition layout of the thin-film heaters in the multi-zone independent temperature control unit is positively correlated with the chip power density distribution on the PCB board. That is, for areas where the total chip power density is greater than a specified value of 2 watts per square centimeter, the corresponding bottom heater partition is subdivided into smaller control units, each control unit having an area of ​​1 / 2 that of a standard partition, in order to achieve finer temperature gradient control.

[0036] In one embodiment of the present invention, the internal microchannels of the liftable heat-conducting baffle adopt a double-helix counter-flow design. The coolant flows in from the upper helical channel at one end of the baffle and flows out from the lower helical channel at the other end. This design can ensure the temperature uniformity of the baffle along its length, with the temperature difference controlled within 0.5 degrees Celsius, thus preventing the baffle itself from becoming a new source of heat disturbance due to uneven temperature.

[0037] As one embodiment of the present invention, the controller of the closed-loop feedback control unit adopts an online parameter identification algorithm based on recursive least squares method.

[0038] The algorithm uses 10 sets of newly collected temperature, viscosity and thickness data in a 2-second cycle to identify and update key parameters in the pre-stored colloidal rheology model in real time, enabling the model to dynamically adapt to the slight performance differences between different batches of potting compound and the aging effect of the colloid itself during the potting process.

[0039] The present invention also provides a partition-type PCB potting heat dissipation method applied to the above-mentioned system, the method comprising the following steps:

[0040] Step S1: Assembly and Initialization. Precisely install the PCB board with chip mounting completed into the bottom base positioning groove of the partition-type potting cavity, and fix it using the vacuum suction hole array. Lower all the liftable thermally conductive partitions to their initial positions, forming multiple sub-potting areas. Set the initial gap between each partition to its maximum value. The closed-loop feedback control unit loads the initial rheological model parameters of the target potting compound.

[0041] Step S2: Preheating and Temperature Field Presetting. The multi-zone independent temperature control unit is activated, and preheating is performed differently for each sub-potting area based on the preset power distribution diagram of the chips on the PCB board. A lower preheating temperature is used for areas with expected high heat flux density; a higher preheating temperature is used for areas with low heat flux density, aiming to establish an inverse temperature gradient negatively correlated with the heat source distribution on the PCB board before potting begins.

[0042] Step S3: Dynamic Potting and Real-time Control. Begin injecting the potting compound. The colloid flow monitoring unit starts simultaneously, acquiring real-time temperature, viscosity, and flow image data and transmitting them to the closed-loop feedback control unit. The controller executes the aforementioned control logic, dynamically adjusting the temperature of each sub-region and the gap height of each thermally conductive partition to ensure that the viscosity and flow velocity of the colloid remain relatively balanced as it flows through sub-regions with different thermal environments.

[0043] Step S4: Filling Verification and Parameter Self-Calibration. When the colloid fills to the exhaust port at the end of the cavity, the laser triangulation thickness sensor initiates a full-plate scan. The closed-loop feedback control unit compares the colloid thickness distribution obtained from the scan with the target thickness distribution. If uneven thickness areas are found, the parameter self-calibration program is initiated to optimize the temperature control and partition gap control parameters of the relevant sub-regions, and the optimization results are updated to the rheological model to guide subsequent production batches.

[0044] Step S5: Curing and Cooling. After potting, adjust all partition gaps to a uniform minimum value to ensure relative isolation between sub-regions. Then, control the multi-zone independent temperature control unit to synchronously heat and cure all areas according to the preset curing temperature curve. After curing, initiate the full-area cooling program.

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0046] 1. This invention introduces a liftable thermally conductive partition to physically divide the potting cavity into multiple independent and controllable sub-regions, and combines this with a multi-zone independent temperature control unit to achieve active and precise control of the local thermal environment during the potting process. This system can directly respond to uneven surface temperature detected by an infrared thermal imager. By dynamically adjusting the heating and cooling intensity of specific sub-regions, it effectively suppresses local variations in adhesive viscosity caused by uneven heat source distribution, fundamentally ensuring the rheological consistency of the adhesive under complex thermal fields. This results in a highly uniform distribution of adhesive layer thickness, reduces local thermal resistance, and improves the overall heat dissipation efficiency and temperature uniformity of the encapsulation.

[0047] 2. The dynamic adjustment mechanism for the partition gap proposed in this invention creatively uses the partition as a flow resistance regulating valve. The closed-loop feedback control unit dynamically calculates and adjusts the gap height based on the real-time viscosity and temperature differences between the sub-regions on both sides of the partition. This proactively balances the colloid flow rate and filling pressure between different sub-regions. This real-time feedback-based flow balance control prevents insufficient filling at remote or corner areas caused by excessively rapid colloid flow in low-viscosity regions, ensuring complete encapsulation of the potting compound on the PCB microchannels, especially the complex three-dimensional structures around high heat flux density chips, greatly improving the reliability of potting filling.

[0048] 3. This invention constructs a closed-loop intelligent control system that deeply integrates real-time monitoring, model prediction, and actuator control. This system not only relies on a preset colloidal rheology model but also utilizes real-time data such as ultrasonic viscosity monitoring and laser thickness measurement verification, and employs an online parameter identification algorithm to continuously correct the model. This enables the system to adapt to performance fluctuations in different batches of materials and dynamic changes in the process, transforming the potting process from an open-loop, passive physical filling into a closed-loop, predictable, and optimizable intelligent manufacturing process, thereby stably producing high-end chip heat dissipation packages with high consistency and high reliability. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of the overall technical solution architecture of the partition-type PCB potting heat dissipation system for high-end chip packaging proposed in this invention.

[0050] Figure 2 This is a schematic diagram of the core principle framework of the closed-loop intelligent control logic based on real-time feedback in this invention.

[0051] Figure 3 This is a logical framework diagram of the local thermal environment constructed collaboratively by the partition-type potting cavity and the multi-zone independent temperature control unit in this invention;

[0052] Figure 4 This is a schematic diagram of the principle framework for the colloidal flow monitoring unit in this invention to perform multi-physics field data fusion and acquisition.

[0053] Figure 5 This is a logical flow diagram of the dynamic dispensing and real-time control stage in this invention. Detailed Implementation

[0054] This embodiment details the specific implementation of a partition-type PCB potting heat dissipation system for high-end chip packaging. Please refer to the appendix. Figures 1 to 5 This system is a comprehensive engineering platform that deeply integrates precision mechanical structure, real-time monitoring of multiple physical fields and adaptive closed-loop control. Its core objective is to solve the problem of uncontrolled flow and curing of potting adhesive caused by uneven heat source distribution on the surface of printed circuit boards, and ultimately achieve high uniformity of adhesive layer thickness to ensure the heat dissipation performance and long-term reliability of high-end chip packages.

[0055] The main structure of the system is a partition-type glue-filling cavity.

[0056] This cavity forms a highly controlled, sealed environment for containing and handling printed circuit board assemblies with chip mounting completed.

[0057] The cavity consists of a bottom base, a top cover, and a set of liftable heat-conducting baffles.

[0058] The base is made of a high-rigidity alloy material and machined as a whole. Its surface is precisely milled with positioning grooves that perfectly match the contour of the back of the target printed circuit board.

[0059] The depth of the positioning groove is usually 2 / 3 of the thickness of the printed circuit board, with a tolerance controlled within ±10 micrometers, to ensure that the plane on the front of the printed circuit board where the chip is located maintains a strict parallel relationship with the surface of the base after the printed circuit board is embedded.

[0060] Vacuum adsorption holes are arranged in a grid pattern of 5 mm × 5 mm at the bottom of the positioning groove.

[0061] Each vacuum adsorption pore is connected to an external multi-channel vacuum generator via an independent micro gas path.

[0062] Once the printed circuit board is placed in the positioning slot, the vacuum generator activates, simultaneously applying negative pressure through all the suction holes to evenly and firmly adhere the printed circuit board to the base, eliminating any warping or localized stress that might be caused by mechanical clamping. The top cover is made of transparent, high-strength engineering plastic for easy optical observation.

[0063] The inside of the cover, that is, the side facing the printed circuit board, is encapsulated with a micro piezoelectric ceramic array.

[0064] The array is arranged in a way that the projected position of each piezoelectric ceramic unit precisely corresponds to the geometric center of a specific chip on the front of the printed circuit board.

[0065] The piezoelectric ceramic unit is connected to an external driving circuit via a flexible circuit, and can be excited to generate high-frequency micro-amplitude vibrations when necessary. This function is mainly used to assist in degassing or to disturb the colloid at specific process stages, but it is not used as a core temperature control method in this basic embodiment. The most core innovative component of the cavity is the liftable heat-conducting partition.

[0066] These partitions are made of copper alloy or aluminum silicon carbide composite material with a thermal conductivity greater than 200 watts per meter Kelvin. They are 1 mm thick, the length is the same as the width of the inner wall of the cavity, and the height is sufficient to contact the top cover when fully raised.

[0067] The number of partitions depends on the size of the printed circuit board to be potted and the complexity of the heat source, with a minimum of 2 and up to 8 or more for large boards.

[0068] In the initial preparation stage, all partitions are driven by linear motors at both ends to descend to a preset height and are arranged at equal intervals in a direction parallel to the long side of the printed circuit board.

[0069] Thus, the partition physically divides the originally interconnected space inside the cavity into multiple independent sub-pouring regions arranged sequentially along the direction of colloid flow.

[0070] Each partition has a height-adjustable gap between its lower edge and the surface of the printed circuit board below. This gap is the only channel through which the adhesive flows from the sub-potting area to the next sub-potting area.

[0071] The gap height adjustment mechanism is integrated at both ends of the partition, and each end is equipped with a micro linear motor with a resolution of 1 micrometer.

[0072] The linear motor's push rod is rigidly connected to the end of the partition through a high-temperature resistant ceramic connector. By controlling the synchronous displacement of the two motors, the entire partition can be raised and lowered in parallel relative to the surface of the printed circuit board.

[0073] The gap height adjustment range is set from 50 micrometers to 500 micrometers.

[0074] The lower limit of 50 micrometers ensures that even under high-viscosity colloid conditions, a minimum flow capacity can be maintained to prevent complete blockage; the upper limit of 500 micrometers provides a large flow cross-section for rapid filling of the colloid in the initial stage of dispensing.

[0075] The real-time value of the gap height is fed back by a grating encoder integrated in the linear motor, with an accuracy of ±2 micrometers.

[0076] Please refer to the attached document. Figure 3 Working closely with the partition-type glue-filling cavity is a multi-zone independent temperature control unit.

[0077] The task of this unit is to establish and maintain an independent and controllable temperature field in each sub-pouring area separated by partitions, so as to precisely regulate the temperature history of the colloid flowing through the area.

[0078] The unit consists of three subsystems: a bottom thin-film heating system, an internal liquid cooling system within the partition, and an external precision circulating liquid cooler.

[0079] The bottom thin-film heating system is directly integrated into the base at the bottom of the cavity, located below the positioning groove.

[0080] The heating element is a platinum thin-film heater manufactured using thick-film printing technology.

[0081] These heaters are not evenly distributed across the entire base surface, but are designed in zones according to the chip layout and power density distribution of the printed circuit board above.

[0082] Specifically, during the potting process preparation stage, the system loads the chip layout diagram of the printed circuit board of this model and the typical power consumption data of each chip.

[0083] Based on this data, the control software divides the projected area of ​​the printed circuit board into several temperature-controlled zones, each corresponding to an independent thin-film heater circuit. The principle of zoning is to make the total power density of the chips within each zone as uniform as possible.

[0084] For high heat flux density areas where the total power density of the chips exceeds the specified value of 2 watts per square centimeter, the corresponding heater zones will be further subdivided, for example, the standard zone area will be reduced to 1 / 2 or even 1 / 4 to form a more refined control unit.

[0085] Each individual thin-film heater zone is driven by a digital power controller that receives instructions from a closed-loop feedback control unit and can adjust the output power in 0.1-watt steps with a response time of 0.1 seconds, with a power adjustment range from 0 watts to 5 watts per square centimeter.

[0086] The liquid cooling system inside the partition is directly integrated into the liftable heat-conducting partition.

[0087] During manufacturing, each heat-conducting baffle is precision-machined to form a double-helix counter-flow microchannel inside. The cross-section of the microchannel is a semi-circle with a diameter of 1 mm, and the total length of the channel is optimized to ensure that the coolant can fully exchange heat with the baffle metal.

[0088] The specific manifestation of the double-helix counterflow design is as follows: the coolant flows in from the upper helical channel inlet at one end of the baffle, flows along the helical path to the other end, then turns into the lower helical channel, and then flows back along the helical path to the outlet near the inlet end.

[0089] This design places the high-temperature coolant inlet and the low-temperature coolant outlet at the same end of the baffle. The temperature gradient of the coolant flowing through the entire length of the baffle is compensated by the countercurrent flow of the upper and lower layers, thus ensuring the temperature uniformity of the entire baffle along its length. The measured temperature difference can be controlled within 0.5 degrees Celsius.

[0090] All the microchannel inlets and outlets of the baffles are connected to external piping via rotary sealing joints, which allow the baffles to be raised and lowered without affecting the continuous supply of coolant.

[0091] An external precision circulating liquid cooler provides power and temperature reference for the entire liquid cooling system.

[0092] This liquid chiller has multi-channel independent temperature control capability, with each channel corresponding to one or a group of heat-conducting baffles.

[0093] Each channel can be independently set to a target temperature, adjustable from 5°C to 80°C, with temperature stability better than ±0.1°C. Simultaneously, the flow rate of each channel can also be independently adjusted via a proportional valve, ranging from 10 ml to 200 ml per minute.

[0094] By coordinating the power of the bottom thin-film heater and the temperature and flow rate of the coolant flowing through the partition, the multi-zone independent temperature control unit can achieve precise heating or cooling of local areas of the printed circuit board and the adhesive flowing through each sub-potting area, thereby actively shaping the required temperature field.

[0095] Please refer to the attached document. Figure 4 The colloidal flow monitoring unit is responsible for non-contact, real-time, and online measurement and sensing of key physical quantities throughout the entire dispensing process.

[0096] This unit is a multi-sensor data fusion system, which mainly includes a distributed infrared thermal imager array, a miniature ultrasonic probe array, and a laser triangulation thickness sensor.

[0097] The distributed infrared thermal imager array is mounted on a specific frame inside the top cover, and its layout ensures that the entire front area of ​​the printed circuit board can be covered without any blind spots.

[0098] The array consists of multiple mid-wave infrared thermal imager modules. The field of view of each module is precisely calculated, and the fields of view of adjacent modules overlap by 10%. Through image stitching algorithms, a complete and high-resolution temperature distribution map of the plate surface can be synthesized.

[0099] The infrared thermal imager has a sampling rate of 15 frames per second, a temperature measurement accuracy of 0.5 degrees Celsius, and a spatial resolution of up to 0.5 millimeters.

[0100] It primarily monitors two targets:

[0101] First, the actual temperature distribution of each chip and substrate on the surface of the printed circuit board before and during potting;

[0102] Secondly, the temperature distribution at the flow front of the potting compound during the spreading process is important, as the temperature of the colloid at the flow front directly affects its rheological properties.

[0103] The miniature ultrasonic probe array is integrated on the flow-facing surface of the liftable thermally conductive partition, that is, the surface facing the direction of the colloidal flow. At least three miniature ultrasonic transducers are embedded on the flow-facing surface of each partition, and these transducers are arranged at a certain interval along the length of the partition.

[0104] Each transducer can both emit high-frequency ultrasonic pulses and receive echo signals reflected or transmitted back from inside the colloid.

[0105] The frequency of the ultrasound is selected between 5 MHz and 10 MHz to achieve a balance between penetration depth and signal sensitivity.

[0106] The speed of sound can be accurately calculated by measuring the propagation time of an ultrasonic pulse within a fixed sound path.

[0107] The sound velocity of a colloid is related to its density and elastic modulus, and thus has a definite functional relationship with its viscosity and degree of curing.

[0108] Meanwhile, the amplitude attenuation of the received echo is also related to the internal friction of the colloid, i.e., its viscosity.

[0109] The dedicated signal processing board in the monitoring unit analyzes the signals received by each ultrasonic transducer in real time. Through a pre-calibrated algorithm model, it inversely calculates the real-time viscosity value and curing percentage of the local colloid in front of the probe, with a data update rate of up to 10 times per second.

[0110] The laser triangulation thickness sensor is installed on the side wall of the glue-filling cavity, and the laser beam emitted by it can be scanned in two dimensions by a high-speed galvanometer system.

[0111] The sensor is in standby mode during the glue filling stage. When the system determines that the glue has completely filled the cavity and reached the end vent, the laser triangular thickness sensor is activated.

[0112] It measures the height of the adhesive layer surface before curing point by point according to the preset grid scanning path, and then calculates the absolute thickness of the adhesive layer at each measurement point by combining the known height reference of the printed circuit board surface.

[0113] Its measurement accuracy can reach ±2 micrometers, and the time required to scan and cover the entire plate surface is usually less than 30 seconds.

[0114] The data acquisition network composed of these three types of sensors provides a comprehensive, real-time data stream for closed-loop control regarding the temperature field, colloidal rheological state, and final filling morphology.

[0115] Please refer to the attached document. Figure 2 With appendix Figure 5 The closed-loop feedback control unit is the intelligent hub of the entire system, responsible for processing monitoring data, executing control algorithms, and driving all actuators.

[0116] The core hardware of this unit is an industrial-grade multi-core real-time controller, while its core software is a multi-input multi-output adaptive predictive control algorithm.

[0117] The controller contains a pre-stored rheological mathematical model of the target potting compound.

[0118] This model was obtained by fitting a large amount of previous experimental data and describes the dynamic relationship between colloidal viscosity, curing reaction rate and temperature using mathematical formulas.

[0119] The basic model expression may include the Arrhenius equation to describe the exponential dependence of the curing rate on temperature, and a cross model to describe the viscosity as a function of shear rate and temperature.

[0120] During the dispensing process, the controller continuously receives three types of data streams from the colloid flow monitoring unit via a high-speed data bus:

[0121] Two-dimensional temperature distribution map of the entire plate surface from an infrared thermal imager array, local viscosity and curing degree data from each ultrasonic probe array, and final adhesive layer thickness distribution data from a laser triangulation thickness sensor.

[0122] The controller's control logic is a continuously running dynamic loop.

[0123] First, the controller processes the infrared thermal imager data in real time.

[0124] It performs a pixel-level comparison between the currently acquired temperature distribution map and the pre-stored heat source distribution map of the printed circuit board chip.

[0125] Using image processing algorithms such as thresholding and region growing, the controller automatically identifies high heat flux density sub-regions where the current temperature exceeds a preset threshold. The preset threshold is calculated based on the chip's rated power consumption and the allowable junction temperature rise.

[0126] For example, for a region where the expected temperature rise is 30 degrees Celsius, the threshold might be set at the base preheating temperature plus 25 degrees Celsius.

[0127] Once a sub-region is identified as having an excessive temperature, the controller immediately queries the ultrasonic viscosity monitoring data corresponding to the spatial location of that sub-region.

[0128] Viscosity data is updated 10 times per second, and the controller takes the average value of the most recent 0.5 seconds as the basis for the current judgment.

[0129] The system presets a target range for the viscosity of the colloid, such as 1000 mPa second to 2500 mPa second, which corresponds to the optimal flow filling and bubble removal capabilities.

[0130] If monitoring data shows that the real-time viscosity of the colloid in this high-temperature sub-region has dropped below 1000 mPa·s, it indicates that the excessively high temperature has caused the colloid to become overly thinned and has excessive fluidity.

[0131] At this point, the controller immediately generates and issues control commands to the multi-zone independent temperature control units.

[0132] The instruction contains two parts:

[0133] First, reduce the output power of the thin-film heater zone below the high-temperature sub-region. The reduction amount is calculated using a proportional-integral-differential algorithm based on the temperature exceedance value and viscosity deviation value.

[0134] Second, increase the flow rate of coolant flowing through the adjacent heat-conducting baffles on both sides of the high-temperature sub-region.

[0135] Because the thermally conductive partition not only separates areas, its temperature also directly affects the heat exchange of adjacent colloids.

[0136] Increasing the coolant flow rate can lower the temperature of the baffle plate, thereby enhancing its cooling capacity for the colloids in the adjacent high-temperature area.

[0137] These two measures work together to quickly and precisely cool the overheated area, causing the colloid viscosity to return to the target range.

[0138] Conversely, if the temperature of a certain sub-region is detected to be too low and the viscosity data fed back by the ultrasonic probe is greater than 2500 mPa·s, it indicates that the colloid is too viscous and flows slowly, posing a risk of insufficient filling.

[0139] The controller then issues a reverse instruction:

[0140] Increase the heating power at the bottom of the area and moderately reduce or maintain the coolant flow rate of the baffles on both sides to gently heat the area, thereby reducing viscosity and promoting flow.

[0141] In addition to directly regulating the temperature field, another core function of the controller is to dynamically and collaboratively control the gap height of the liftable heat-conducting baffle.

[0142] In the initial stage of glue filling, all partition gaps are uniformly set to a maximum value of 500 micrometers to form a wide flow channel, allowing the glue to quickly fill the main area of ​​the cavity with low resistance.

[0143] As the colloid flow front advances, when the infrared thermal imager or an algorithm based on injection pressure determines that the colloid front is about to reach a specific septum, the gap adjustment logic for that septum is activated.

[0144] The controller first retrieves real-time monitoring data from the upstream and downstream sub-regions of the partition, including average temperature, average viscosity, and viscosity change trends.

[0145] Based on this data, the controller executes a dedicated gap calculation algorithm. The core objective of this algorithm is to balance the colloid flow on both sides of the partition, ensuring the synchronous filling of the entire plate surface.

[0146] Specifically, if calculations reveal that the colloid in the upstream sub-region has lower viscosity and faster flow rate due to higher temperature, while the downstream sub-region, being closer to the high-heat-source chip, has a tendency for the colloid temperature to rise and the viscosity to decrease accordingly, then if a large gap is maintained, the low-viscosity colloid in the upstream will quickly flow into the downstream, which may lead to insufficient pressure accumulation in the downstream region, making it unable to properly fill the fine structure inside, and the far end of the cavity may be insufficiently filled due to premature loss of colloid.

[0147] To prevent this, the controller will instruct the gap height of the partition to be reduced, for example, gradually from 500 micrometers to 200 micrometers.

[0148] A smaller gap means increased flow resistance, which can effectively suppress the excessively rapid flow of upstream colloids, allowing the upstream pressure to rise appropriately, thus ensuring sufficient pressure to drive the colloids to fill every corner of the downstream area.

[0149] Conversely, if the viscosity in the downstream region is high and the flow resistance is large, the controller may maintain or appropriately increase the gap to facilitate the passage of the colloid.

[0150] The adjustment of the gap height is continuous and dynamic. Its set value is calculated and updated several times per second based on the real-time viscosity difference and temperature difference on both sides of the baffle through a simplified model based on fluid dynamics equations.

[0151] Once the glue dispensing process is complete, the laser triangulation thickness sensor finishes scanning the entire board and sends the glue layer thickness distribution data it provides to the controller for final verification.

[0152] The controller compares the measured thickness distribution with the target thickness distribution required by the process point by point.

[0153] The target thickness is typically a constant, such as 300 micrometers, and allows for a tolerance of ±5%.

[0154] If the thickness of the adhesive layer in certain local areas deviates from the tolerance zone, for example, the thickness at a certain point is only 270 micrometers, the controller will initiate a parameter self-calibration program.

[0155] The program first traces the historical data records of the sub-region where the thickness is insufficient throughout the entire glue-pouring process, including the average temperature control curve of the region, the history of gap adjustment between adjacent partitions, and the viscosity change curve monitored by ultrasound.

[0156] By analyzing this historical data, the controller can deduce possible causes of uneven thickness, such as whether the temperature control was too high at a certain stage, resulting in low colloid viscosity and excessive loss, or whether improper adjustment of the baffle gap led to insufficient local flow.

[0157] Based on the analysis results, the controller optimizes and adjusts the relevant control parameters, such as fine-tuning the bias of the temperature control setpoint for the area, or modifying a gain coefficient of the partition gap adjustment algorithm near the area.

[0158] These optimized parameters are not only used to correct for potential subsequent process steps in the current batch, but more importantly, they are used to update the pre-stored colloidal rheology model.

[0159] In this embodiment, the closed-loop feedback control unit uses an online parameter identification algorithm based on recursive least squares to achieve adaptive model updates.

[0160] The algorithm operates on a 2-second execution cycle. Within each cycle, it collects the 10 most recently acquired valid data sets from the past 20 seconds, including temperature, viscosity, and corresponding spatial location information.

[0161] The algorithm compares these new data with the model predictions and uses the principle of recursive least squares to dynamically adjust key parameters in the rheological model, such as activation energy or pre-exponential factor, so that the model output is more in line with the behavior of the actual colloid under real process conditions.

[0162] This online identification mechanism enables the system to automatically adapt to minor formula differences between different batches of potting compound, as well as changes in the rheological properties of the compound itself caused by the progress of the curing reaction during the potting process, thereby maintaining long-term control accuracy.

[0163] The system operates according to a rigorous process flow. Assembly and initialization begin first. The operator precisely places the printed circuit board with the chip mounted into the positioning slot of the bottom base and activates the vacuum adsorption system to secure it.

[0164] All liftable heat-conducting baffles descend to the working position, forming a preset number of sub-potting areas, and initializing all baffle gaps to 500 micrometers.

[0165] The closed-loop feedback control unit loads the basic rheological model parameters of this type of potting compound and the current printed circuit board chip layout thermal diagram.

[0166] Next, we proceed to the preheating and temperature field preset stage.

[0167] The multi-zone independent temperature control unit is activated. Based on the chip's thermal map, the controller executes a reverse temperature gradient preset strategy:

[0168] For chip areas that are expected to generate high heat during potting, the corresponding sub-potting areas are set with a relatively low target temperature during the preheating stage, for example, less than 5 degrees Celsius below the optimal potting temperature of the adhesive; while for areas with low heat flux density or no chip, a higher preheating temperature is set, for example, more than 5 degrees Celsius above the optimal potting temperature.

[0169] The purpose of this is to proactively establish a temperature field on the printed circuit board surface that is negatively correlated with the distribution of future heat sources before the potting process begins, in order to pre-compensate for any temperature unevenness that may occur during potting due to the activation of the heat sources. The preheating process continues until the temperature of all areas stabilizes at the set value.

[0170] Then, the dynamic dispensing and real-time control stage begins. The dispensing pump starts injecting potting compound into the cavity inlet at a constant pressure or flow rate.

[0171] At the same time, all sensors in the colloidal flow monitoring unit are activated synchronously, and data begins to flow continuously to the closed-loop feedback control unit.

[0172] The controller enters a real-time control cycle, as described above, dynamically and in parallel adjusting the power of the film heaters in each sub-potting area, the coolant conditions of each thermally conductive partition, and the gap height of each partition.

[0173] The entire dispensing process is carried out under this intelligent closed-loop control, ensuring that the viscosity and flow front velocity of the adhesive remain relatively balanced when it flows through areas with different thermal environments.

[0174] Once the system detects that the colloid has filled the cavity and reached the end vent, the dispensing process stops. The filling verification and parameter self-calibration phase then begins.

[0175] A laser triangulation thickness sensor performs a full scan of the adhesive layer, the controller analyzes the thickness uniformity, and performs necessary parameter self-calibration and model updates. Finally, the process proceeds to the curing and cooling stage.

[0176] The controller adjusts the gap between all the liftable heat-conducting baffles to a uniform minimum of 50 micrometers. This is intended to relatively isolate the sub-regions during the curing stage and reduce convection interference that may be caused by slight temperature differences.

[0177] Then, the multi-zone independent temperature control unit synchronously heats all zones according to the preset curing temperature curve, triggering and controlling the cross-linking and curing reaction of the colloid. After curing, a full-zone cooling program is initiated to reduce the temperature to a level suitable for safe demolding.

[0178] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0179] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A partition-type PCB potting heat dissipation system for high-end chip packaging, characterized in that, include: A partition-type potting chamber is used to accommodate PCB components to be potted and to create a controlled potting environment. A multi-zone independent temperature control unit is used to implement independent temperature control for each sub-potting area within the partition-type potting cavity; The partition-type potting cavity consists of a bottom base, a top cover, and a set of liftable heat-conducting partitions located inside the cavity. The colloidal flow monitoring unit is used to acquire the flow state and physical parameters of the colloidal material in each sub-dispensing area during the dispensing process in real time. The closed-loop feedback control unit is used to dynamically adjust the multi-zone independent temperature control unit and the actuator of the partition-type dispensing cavity based on the data collected in real time by the colloidal flow monitoring unit. The core of the closed-loop feedback control unit is a multi-input multi-output controller. The colloidal flow monitoring unit includes a distributed infrared thermal imager array arranged inside the top cover plate, a miniature ultrasonic probe array integrated into the flow-facing surface of the liftable heat-conducting partition, and a laser triangulation thickness sensor set on the side wall of the cavity. The controller has a pre-stored rheological model of the target potting compound, which describes the quantitative relationship between the compound viscosity, curing rate and temperature. During the dispensing process, the controller continuously receives temperature distribution data from the infrared thermal imager array, viscosity and curing degree data from the ultrasonic probe array, and adhesive layer thickness data from the laser triangulation thickness sensor. The control logic of the controller includes: The PCB surface temperature distribution obtained by the infrared thermal imager is compared with the preset chip heat source distribution map to identify high heat flux density sub-regions where the current temperature is greater than the preset threshold. Retrieve the ultrasonic viscosity data corresponding to these high heat flux density sub-regions; If the viscosity of the colloid in a certain sub-region is found to be lower than the set lower limit due to the increase in temperature, the multi-zone independent temperature control unit is instructed to reduce the power of the bottom thin film heater acting on that sub-region, while increasing the flow rate of the coolant flowing through the adjacent thermally conductive partition in that region. If it is detected that the viscosity of the colloid is too high due to low temperature in a certain sub-region, the heating power at the bottom of that region will be increased and the cooling intensity of the partition will be reduced.

2. The partition-type PCB potting and heat dissipation system for high-end chip packaging according to claim 1, characterized in that, The bottom base integrates a positioning groove and a vacuum adsorption hole array that match the contour of the back of the PCB board; the inner side of the top cover is encapsulated with a micro piezoelectric ceramic array that corresponds to the chip layout on the front of the PCB board. The liftable heat-conducting partition is made of a high thermal conductivity metal material; The partitions are arranged at equal intervals parallel to the long side of the PCB board in the initial state, and divide the internal space of the cavity into multiple independent sub-potting areas. Each partition has a height-adjustable gap between its lower edge and the PCB surface. This gap serves as the only channel for the colloid to flow between adjacent sub-regions, and its height is adjusted by miniature linear motors integrated at both ends of the partition.

3. A partition-type PCB potting and heat dissipation system for high-end chip packaging according to claim 2, characterized in that, The multi-zone independent temperature control unit includes multiple sets of thin-film heaters embedded below the positioning groove of the bottom base, a multi-channel microfluidic channel integrated inside the liftable heat-conducting partition, and an external precision circulating liquid cooler. The thin-film heaters are arranged in sections based on sub-pouring areas, and the heating power of each section is independently adjustable. The microchannels integrated inside the heat-conducting partitions are connected to the precision circulating liquid cooler, and the temperature of the partitions themselves can be independently controlled by adjusting the temperature and flow rate of the coolant flowing through each partition.

4. A partition-type PCB potting and heat dissipation system for high-end chip packaging according to claim 3, characterized in that, The distributed infrared thermal imager array is used to acquire two-dimensional temperature distribution maps of the front side of the PCB board and the front edge of the colloid flow. The miniature ultrasonic probe array is used to transmit and receive ultrasonic signals. By analyzing the propagation speed and attenuation characteristics of ultrasonic waves in the colloid, the viscosity and degree of curing of the colloid in the current region can be inverted in real time. The laser triangulation thickness sensor is used to measure the real-time thickness of the adhesive layer at different positions on the PCB board before curing, along a preset scanning path during the colloid filling process.

5. A partition-type PCB potting and heat dissipation system for high-end chip packaging according to claim 4, characterized in that, The controller's control logic also includes coordinated control of the gap between the liftable heat-conducting baffles: During the initial stage of glue application, all partition gaps are set to their maximum values; When the colloidal flow front approaches a certain baffle, the optimal gap height is dynamically calculated based on the real-time viscosity difference and temperature difference between the sub-regions on both sides of the baffle. If the viscosity of the colloid in the upstream region is low while the viscosity in the downstream region tends to increase, then the instruction is to reduce the gap between the partitions. The adhesive layer thickness data fed back by the laser triangulation thickness sensor is used for final verification. When the adhesive layer thickness at any position is detected to deviate from the target thickness by more than the specified value, the controller will trace the historical temperature control and partition gap adjustment records of the sub-region to which the position belongs, perform self-correction on the control parameters, and update the corrected parameters into the rheological model.

6. A partition-type PCB potting and heat dissipation system for high-end chip packaging according to claim 5, characterized in that, In the multi-zone independent temperature control unit, the partition layout of the thin-film heater is positively correlated with the power density distribution of the chips on the PCB board. For regions where the total chip power density exceeds a specified value, the corresponding bottom heater zone is subdivided into smaller control units.

7. A partition-type PCB potting and heat dissipation system for high-end chip packaging according to claim 6, characterized in that, The internal microchannels of the liftable heat-conducting baffle adopt a double-helix counter-flow design. Coolant flows in from the upper spiral channel at one end of the baffle and flows out from the lower spiral channel at the other end.

8. A partition-type PCB potting and heat dissipation system for high-end chip packaging according to claim 7, characterized in that, The controller of the closed-loop feedback control unit adopts an online parameter identification algorithm based on recursive least squares.

9. A partition-type PCB potting and heat dissipation system for high-end chip packaging according to claim 8, characterized in that, The dynamic calculation process for the partition gap in the control logic of the closed-loop feedback control unit is as follows: Obtain real-time average temperature and average viscosity data for the upstream and downstream sub-regions of the partition; Based on the real-time data, the optimal gap height is calculated using a model simplified from fluid dynamics equations to balance the colloid flow rate and filling pressure on both sides of the partition.

10. A partition-type PCB potting heat dissipation method applied to the system according to any one of claims 1 to 9, characterized in that, Includes the following steps: Step S1, Assembly and Initialization: Install the PCB board with chip mounting completed into the bottom base positioning groove of the partition-type potting cavity and fix it through the vacuum adsorption hole array; lower all the liftable thermally conductive partitions to the initial position to form multiple sub-potting areas; set the initial gap of each partition to the maximum value; load the initial rheological model parameters of the target potting compound into the closed-loop feedback control unit. Step S2, Preheating and Temperature Field Presetting: Activate the multi-zone independent temperature control unit and perform differentiated preheating on each sub-potting area according to the preset power distribution diagram of the chips on the PCB board; for areas with high expected heat flux density, use a lower preheating temperature; for areas with low heat flux density, use a higher preheating temperature. Step S3, Dynamic Potting and Real-time Control: Start injecting potting compound; the colloidal flow monitoring unit starts simultaneously, collecting temperature, viscosity and flow image data in real time and transmitting them to the closed-loop feedback control unit; the controller executes the control logic to dynamically adjust the temperature of each sub-region and the gap height of each thermally conductive partition. Step S4, Filling Verification and Parameter Self-Calibration: When the colloid fills to the exhaust port at the end of the cavity, the laser triangulation thickness sensor starts full-plate scanning; the closed-loop feedback control unit compares the colloid thickness distribution obtained from the scan with the target thickness distribution; if an area with uneven thickness is found, the parameter self-calibration program is started to optimize the temperature control and partition gap control parameters of the relevant sub-regions, and the optimization results are updated to the rheological model; Step S5, Curing and Cooling: After the potting is completed, adjust all the gaps between the partitions to a uniform minimum value; then, control the multi-zone independent temperature control unit to synchronously heat and cure all areas according to the preset curing temperature curve; after curing is completed, start the full-area cooling program.

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