A process for manufacturing a vapor chamber

Abstract

This invention provides a heat spreader manufacturing process, relating to the field of laser beam processing technology, including: Step S1: After positioning the copper mesh and the lower cover of the heat spreader, place them into the fixture of the laser machine; Step S2: Determine the laser path of the laser machine, perform laser engraving, and use the laser beam to bond the copper mesh and the lower cover of the heat spreader together; The high temperature emitted by the laser beam changes the roughness of the copper mesh, achieving an oxidation effect. The laser beam firmly bonds the copper mesh and the lower cover of the heat spreader together, preventing them from falling off, thus providing a fixing effect, equivalent to the sintering effect of the original technology; The laser beam sweeps across the capillary mesh, and the emitted high temperature instantly changes the roughness of the capillary mesh, achieving the oxidation effect of the original technology; The laser beam is very fast, with a single product expected to be completed within 1 minute, improving efficiency and reducing production costs; It solves the temperature challenge between oxidation and reduction, reducing the difficulty of reduction.

Description

Technical Field

[0001] This invention relates to the field of laser beam processing technology, specifically to a heat spreader manufacturing process applicable to heat spreaders made of materials such as copper, stainless steel, and copper-steel. Background Technology

[0002] The existing manufacturing process of heat spreaders includes: 1. Capillary mesh sintering: the capillary mesh is passed through a high temperature of 500-700℃ for 2 hours to reach its melting point, causing the capillary mesh to adhere to the heat spreader and generate capillary force, while also ensuring the flatness of the heat spreader meets the requirements; 2. Oxidation: the original method involves baking the copper mesh at a temperature of 200-300℃ for 1-2 hours in a sealed environment, forming a layer of copper oxide on the surface of the copper mesh, which changes the surface wettability and increases the surface roughness; 3. Reduction treatment: the copper oxide on the surface is reduced to restore its original properties and appearance, and improve its corrosion resistance, ensuring that the copper mesh can maintain good working condition in various applications.

[0003] The above process has the following problems: sintering and oxidation are time-consuming, with the two processes taking about 8 hours, resulting in low timeliness. Summary of the Invention

[0004] This invention provides a process for manufacturing a heat spreader to solve the technical problems mentioned in the background section.

[0005] To solve the above-mentioned technical problems, the present invention discloses a process for manufacturing a heat spreader, comprising:

[0006] Step S1: Position the copper mesh and the lower cover of the heat spreader and place them into the fixture of the laser machine;

[0007] Step S2: Determine the laser path of the laser machine and perform laser engraving. The laser beam will bond the copper mesh to the bottom cover of the heat spreader. The high temperature emitted by the laser beam changes the roughness of the copper mesh, achieving the oxidation effect.

[0008] Preferably, the material of the heat spreader is any one of copper, stainless steel, or copper-steel.

[0009] Preferably, before step S1, the method further includes: cleaning the surfaces of the copper mesh and the heat spreader; checking whether the lower cover of the heat spreader is flat; and checking whether the copper mesh and the heat spreader are oxidized.

[0010] Preferably, during the repeated execution of step S2, the laser machine periodically performs a power efficiency evaluation process to determine whether the power efficiency of the laser in the laser machine is normal, and an alarm is triggered when the power efficiency of the laser in the laser machine is abnormal.

[0011] The power efficiency evaluation process includes:

[0012] Step S201: Obtain the power efficiency of the laser machine within the latest preset time period, determine the power efficiency array sorted by time, and determine the latest power efficiency and power efficiency decay rate based on the power efficiency array;

[0013] Step S202: When either the latest power efficiency is less than the preset power efficiency or the power efficiency decay rate is greater than the corresponding preset decay rate, an alarm is triggered to indicate abnormal power efficiency.

[0014] Preferably, a welding test is performed before each batch of the current type of copper mesh and the current type of heat spreader begins to execute step S1.

[0015] Preferably, the welding test process includes:

[0016] Step S21: Obtain the laser output power versus power density correlation line of the laser machine under the standard conditions of the current type of laser machine used initially;

[0017] Step S22: Obtain the target power density range for welding the current type of copper mesh to the current type of heat spreader, and the target output power range corresponding to the target power density range determined by the correlation line between the output power and power density of the laser in the laser machine;

[0018] Preferably, under the standard conditions of the current type of laser machine used initially, when the output power of the laser of the current type of laser machine is the median of the target output power range, the average temperature of the first-level adjacent region, the second-level adjacent region, and the third-level adjacent region corresponding to the selected route segment in the target welding path when laser welding the current type of copper mesh sample and the current type of heat spreader plate sample with the selected route segment in the target welding path.

[0019] Step S24: Obtain the target oxidation temperature range and target oxidation time for each area of ​​the copper mesh during the laser welding process of the current type of copper mesh and the current type of heat spreader;

[0020] Step S25: Control the current laser machine to use the output power of the laser of the current type of laser machine as the median of the target output power range, and perform laser welding on the selected route segment in the target welding path of the current copper mesh sample and the current heat spreader sample, and determine the average temperature of the first-level proximity area, second-level proximity area and third-level proximity area corresponding to the selected route segment through temperature detection.

[0021] Step S26: Based on steps S25 and S23, determine the temperature difference values ​​of the first-level adjacent area, the second-level adjacent area, and the third-level adjacent area;

[0022] Step S27: Determine the first correction coefficient based on the temperature difference value obtained in step S26;

[0023] Step S28: An alarm is triggered if any of the following occurs: the first correction coefficient is greater than the preset correction coefficient, or the average temperature of the first-level adjacent area obtained in step S25 is not within the corresponding target oxidation requirement temperature range.

[0024] Preferably, the welding test process also includes:

[0025] Step 29: Determine the second correction factor based on the latest obtained power efficiency and power efficiency decay rate;

[0026] Step S210: Determine the first welding input power range corresponding to the current batch and current type of copper mesh and the current type of heat spreader based on the first correction coefficient and the second correction coefficient. If the first welding input power range corresponding to the current batch and current type of copper mesh and the current type of heat spreader is not within the allowable input power range of the laser of the current laser machine, an alarm is triggered.

[0027] When the first welding input power range corresponding to the current batch of the current type of copper mesh and the current type of heat spreader has a target welding input power range that overlaps with the allowable input power range of the laser of the current laser machine, when step S2 is started to be executed in batches for the current batch of the current type of copper mesh and the current type of heat spreader, the actual input power of the laser of the current laser machine is controlled to be the minimum value of the target welding input power range.

[0028] Preferably, the method further includes: step S3: dissipating heat on the product obtained in step S2; in step S3, the product obtained in step S2 is placed in a heat dissipation rack, and all the cooling nozzles on the heat dissipation rack spray cooling medium to dissipate heat on the entire surface of the product obtained in step S2.

[0029] Preferably, before each batch of the current type of copper mesh and the current type of heat spreader begins to execute step S3, a heat dissipation test step is performed on the sample of the current batch of the current type of copper mesh and the current type of heat spreader that has been welded according to the welding requirements.

[0030] Preferably, the heat dissipation test steps include:

[0031] Step S31: Before cooling, perform temperature detection on the surface of the second sample after welding the current batch of copper mesh and the current type of heat spreader according to the welding requirements at the temperature detection point.

[0032] Based on the temperature detection results, the surface of the second sample is divided into several different sub-regions. Each sub-region is composed of adjacent surfaces, and the standard deviation of the temperature detection values ​​of all temperature detection points in each sub-region is less than the preset standard deviation.

[0033] Step S32: Based on the required cooling rate range for each temperature stage corresponding to each surface of each sub-region of the product obtained in step S2, determine the required cooling flow rate range for the cooling medium for each temperature stage corresponding to each surface of each sub-region, and determine the first cooling flow rate of the cooling medium for each temperature stage corresponding to each sub-region; the surface categories include: heat spreader, copper mesh, and weld; the end temperature of each temperature stage of each surface is a preset temperature range.

[0034] The first cooling flow rate of the cooling medium in the current temperature stage of the current sub-region is: the minimum standard deviation of the median cooling flow rate requirement range of the cooling medium corresponding to all surfaces in the current temperature stage of the current sub-region, compared with the median cooling flow rate requirement range of the cooling medium of other surfaces.

[0035] Step S33: Obtain the third sample after welding the current type of copper mesh and the current type of heat spreader according to the welding requirements. When performing a cooling test at the first flow rate of the cooling medium at each temperature stage of each cooling nozzle, obtain the actual cooling rate of each surface of each sub-region at each temperature stage, and determine the target flow rate of the cooling medium for each temperature stage corresponding to each cooling nozzle.

[0036] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1. The copper mesh is firmly bonded to the bottom cover of the heat spreader by a laser beam, preventing it from falling off and thus achieving a fixing effect, which is equivalent to the sintering effect of the original technology;

[0039] 2. The laser beam sweeps across the capillary mesh, and the high temperature emitted instantly changes the roughness of the capillary mesh, achieving the oxidation effect of the original technology;

[0040] 3. The laser beam has a very fast time, and the time for a single product is expected to be completed within 1 minute. The original technology of sintering + oxidation takes 8-10 hours, while laser engraving can be completed within 1 minute, which improves efficiency and reduces production costs.

[0041] 4. Solve the temperature challenge between oxidation and reduction, reduce the difficulty of reduction, and prevent excessive reduction from thinning the capillary action of oxidation, leading to poor performance;

[0042] 5. Reduce the production cycle of a single vapor chamber product. The current oxidation process takes 2-2.5 hours, while laser engraving is completed in an instant. Currently, the processing time for a single vapor chamber product for mobile phones is 10 seconds.

[0043] 6. The capillary action of the copper mesh engraved by the laser beam does not change with temperature, thus reducing the difficulty of restoration. Attached Figure Description

[0044] 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:

[0045] Figure 1 This is a partial flow chart of the process of the present invention;

[0046] Figure 2 This is an overall process flow diagram of the present invention;

[0047] Figure 3 A simplified overall flow chart of the existing process;

[0048] Figure 4 Parameters for existing processes Figure 1 ;

[0049] Figure 5 Parameters for existing processes Figure 2 ;

[0050] Figure 6 A parameter diagram of the process of the present invention.

[0051] Figure 7 This is a schematic diagram illustrating the division of the primary, secondary, and tertiary proximity regions according to the present invention.

[0052] Figure 8 This is a schematic diagram of the heat sink of the present invention.

[0053] In the figure: 1. Heat sink; 2. Cooling nozzle; 3. Telescopic rod; 4. Product obtained in step S2. Detailed Implementation

[0054] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0055] Furthermore, in this invention, the use of terms such as "first" and "second" is for descriptive purposes only and does not specifically refer to any order or sequence, nor is it intended to limit the invention. They are merely used to distinguish components or operations described using the same technical terms and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions and features of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If a combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0056] The present invention provides the following embodiments:

[0057] The existing manufacturing process of heat spreaders is as follows: Figure 3 As shown, the process includes, in sequence: etching (VC heat spreader etching) → fixing copper mesh → capillary mesh sintering → dispensing and positioning (copper solder paste) → brazing → oxidation → reduction → pipe injection → first and second removal → sealing and welding → cutting and leveling → high temperature aging → surface treatment → nitrogen testing → performance testing → full appearance inspection.

[0058] The capillary mesh sintering process includes: placing the capillary mesh on a graphite fixture, covering it with a heat spreader, and then performing high-temperature sintering to bond the capillary mesh and the heat spreader together; the capillary mesh sintering parameters are as follows: Figure 4 As shown;

[0059] The oxidation process includes: placing the product on a fixture and subjecting it to high-temperature baking to increase surface roughness; oxidation parameters such as... Figure 5 As shown;

[0060] In summary, sintering and oxidation are time-consuming, with the two processes taking approximately 8 hours. This results in low timeliness, a high risk factor, and many uncontrollable factors.

[0061] Example 1: This embodiment of the invention provides a process for manufacturing a heat spreader, such as... Figure 1 , Figure 2 , Figure 4 , Figure 6 As shown, it includes:

[0062] Step S1: Position the copper mesh (capillary mesh) and the lower cover of the heat spreader, and then place it into the fixture of the laser machine;

[0063] Step S2: Determine the laser path of the laser machine (adjust the scanning path, laser time, and laser power), and perform laser engraving. The laser beam bonds the copper mesh to the lower cover of the heat spreader (achieving the sintering effect of the original technology). The laser beam sweeps across the capillary mesh of the copper mesh, and the high temperature instantly changes the roughness of the capillary mesh, achieving an oxidation effect. Step 2 can achieve the sintering and oxidation effects of the original technology; laser parameters are as follows... Figure 6 As shown;

[0064] The copper mesh is fixed in the center of the lower cover of the heat spreader, and then the entire surface of the copper mesh is laser-engraved to fix the copper mesh to the surface of the lower cover of the heat spreader.

[0065] 1. Before welding (as described above for laser engraving), check that the bottom cover of the heat spreader is flat and free from oxidation, dirt, etc.

[0066] 2. Place the bottom cover of the heat spreader into the conformal welding fixture (the fixture of the laser machine mentioned above), then place the copper mesh on the bottom cover of the heat spreader, and start the welding process.

[0067] Combinatorial principle:

[0068] The copper mesh is fixed in the center of the lower cover of the heat spreader, and then the entire copper mesh surface is laser-engraved to fix the copper mesh to the surface of the lower cover.

[0069] A vapor chamber is a vacuum cavity with a finely structured inner wall, and the capillary mesh is the key internal structure for achieving heat conduction circulation. Through processes such as copper powder sintering or copper mesh weaving, a copper mesh with fine pores is manufactured, thus forming the capillary mesh structure within the vapor chamber. This capillary mesh structure resembles a network of tiny pipes, providing channels for coolant return.

[0070] The working principle and beneficial effects of the above technical solution are as follows:

[0071] 1. The copper mesh is firmly bonded to the bottom cover of the heat spreader by a laser beam, preventing it from falling off and thus achieving a fixing effect, which is equivalent to the sintering effect of the original technology;

[0072] 2. The laser beam sweeps across the capillary mesh, and the high temperature emitted instantly changes the roughness of the capillary mesh, achieving the oxidation effect of the original technology;

[0073] 3. The laser beam has a very fast time, and the time for a single product is expected to be completed within 1 minute. The original technology of sintering + oxidation takes 8-10 hours, while laser engraving can be completed within 1 minute, which improves efficiency and reduces production costs.

[0074] 4. Solve the temperature challenge between oxidation and reduction, reduce the difficulty of reduction, and prevent excessive reduction from thinning the capillary action of oxidation, leading to poor performance;

[0075] 5. Reduce the production cycle of a single vapor chamber product. The current oxidation process takes 2-2.5 hours, while laser engraving is completed in an instant. Currently, the processing time for a single vapor chamber product for mobile phones is 10 seconds.

[0076] 6. The capillary action of the copper mesh engraved by the laser beam does not change with temperature, thus reducing the difficulty of restoration.

[0077] Example 2: Based on Example 1, during the repeated execution of step S2, the laser machine periodically performs a power efficiency evaluation process to determine whether the power efficiency of the laser in the laser machine is normal, and an alarm is triggered when the power efficiency of the laser in the laser machine is abnormal.

[0078] The power efficiency evaluation process includes:

[0079] Step S201: Obtain the power efficiency of the laser machine within the latest preset time period, determine the power efficiency array sorted by time, and determine the latest power efficiency and power efficiency decay rate based on the power efficiency array;

[0080] Step S202: When either the latest power efficiency is less than the preset power efficiency or the power efficiency decay rate is greater than the corresponding preset decay rate, an alarm is triggered to indicate abnormal power efficiency.

[0081] Power efficiency is defined as the ratio of the output power of the laser in the laser machine to the input power of the laser in the laser machine.

[0082] The power efficiency array is: {A1, A2, A3...A4} i... A n}, A1, A2, A3...A i... A n These represent the power efficiency determined for the 1st, 2nd, 3rd...i...nth time within the latest preset time period; n is the total number of power efficiency determinations (based on detection) within the latest preset time period; A1, A2, A3...A i... A n The corresponding times are sequentially from smallest to largest (i.e., after A1 is determined, the next time it is determined is A2).

[0083] The power efficiency decay rate is: ;

[0084] The latest power efficiency is: A n ;

[0085] The beneficial effects of the above technical solution are as follows:

[0086] Periodic power efficiency evaluations can monitor the laser machine multiple times (or in real time) during repeated operation, grasp the power efficiency status of the laser, detect abnormal trends in a timely manner, and avoid operating in an abnormal efficiency state for a long time.

[0087] An alarm will be triggered when either the latest power efficiency is lower than the preset power efficiency or the power efficiency decay rate is greater than the corresponding preset decay rate. This can provide a warning before the laser power efficiency deteriorates significantly but before a complete failure occurs, allowing for early intervention and reducing production interruption losses caused by sudden failures.

[0088] Timely detection and handling of power efficiency anomalies can keep the laser in a relatively stable and efficient working state, ensuring the overall operational stability of the laser machine and the consistency of processing quality. This is especially important for processing tasks that require high laser power precision.

[0089] Example 3: Based on Example 1 or 2, a welding test is performed before each batch of the current type of copper mesh and the current type of heat spreader begins to execute step S1.

[0090] The welding test process includes:

[0091] Step S21: Obtain the laser output power versus power density correlation line of the laser machine under the standard conditions of the current type of laser machine used initially;

[0092] The standard conditions include: the temperature of the key components of the laser machine meets the corresponding standard temperature range; all performance characteristics of the laser machine are qualified; the laser machine is usually equipped with a heat dissipation system to ensure that the temperature meets the requirements.

[0093] Step S21 is a performance test conducted before the entire type of laser machine is put into mass use. The output power and power density correlation line of the laser machine is obtained (the output power and power density correlation line of the laser machine is represented by a coordinate system, with the horizontal axis being the output power of the laser machine and the vertical axis being the power density of the output laser). Based on memory storage, this invention retrieves the data from the memory during the process of putting any laser machine of this type into use.

[0094] Step S22: Obtain the target power density range for welding the current type of copper mesh to the current type of heat spreader, and the target output power range corresponding to the target power density range determined by the correlation line between the output power and power density of the laser in the laser machine;

[0095] The target power density range can be the power density range that meets the welding requirements (quality and performance requirements) of the current type of copper mesh and the current type of heat spreader, obtained through testing / experimentation.

[0096] Step S23: Under the standard conditions of the current type of laser machine used initially, when the output power of the laser of the current type of laser machine is the median of the target output power range (actually, the input power of the laser of the current type of laser machine is the median of the target output power range ÷ the power efficiency of the current type of laser machine used initially under the standard conditions), when laser welding the current type of copper mesh sample and the current type of heat spreader plate sample with the selected route segment in the target welding route, the average temperature of the first-level adjacent area, the second-level adjacent area, and the third-level adjacent area of ​​the selected route segment of the current type of copper mesh sample and the current type of heat spreader plate sample is performed.

[0097] In this invention, the copper mesh sample is divided into multiple regions by horizontal and vertical dividing lines (e.g., Figure 7 As shown, Figure 7 (A represents the selected route segment). Among them, the area directly adjacent to the area where the selected route segment is located is the first-level adjacent area, the area directly adjacent to the first-level adjacent area is the second-level adjacent area, and the others are the third-level adjacent areas.

[0098] The standard conditions are the same as above. Step S23 is to test / experiment to determine the average temperature of the first-level, second-level, and third-level adjacent areas (the appropriate temperature can meet the oxidation requirements) before the current type of copper mesh sample and the current type of heat spreader are batch welded by the current type of laser machine.

[0099] Step S24: Obtain the target oxidation temperature range and target oxidation time for each area of ​​the copper mesh during the laser welding process of the current type of copper mesh and the current type of heat spreader;

[0100] Step S25: Control the current laser machine to use the output power of the laser of the current type of laser machine as the median of the target output power range (actually, the input power of the current laser machine is the median of the target output power range ÷ the current power efficiency of the current laser machine), and perform laser welding on the selected route segment (the selected route segment is any route segment in the target welding route) of the current copper mesh sample and the current heat spreader sample. Determine the average temperature of the first-level proximity area, second-level proximity area, and third-level proximity area corresponding to the selected route segment through temperature detection. The current copper mesh sample belongs to the current type of copper mesh sample; the current heat spreader sample belongs to the current type of heat spreader; the current laser machine belongs to the current type of laser machine.

[0101] Step S26: Based on steps S25 and S23, determine the temperature difference values ​​of the first-level adjacent area, the second-level adjacent area, and the third-level adjacent area;

[0102] Step S27: Determine the first correction coefficient based on the temperature difference value obtained in step S26;

[0103] Step S28: An alarm is triggered if any of the following occurs: the first correction coefficient is greater than the preset correction coefficient, or the average temperature of the first-level adjacent area obtained in step S25 is not within the corresponding target oxidation requirement temperature range.

[0104] The first correction factor K is calculated based on the following formula:

[0105] ; The average temperature of the j-th level neighboring region obtained in step S23; The average temperature of the j-th level neighboring region obtained in step S25; The weight of the j-th level neighbor region (values ​​are greater than 0 and less than 1); + + =1, and can take values ​​of 0.6, 0.25, and 0.15 respectively.

[0106] The beneficial effects of the above technical solution are as follows:

[0107] By obtaining the correlation line between the laser output power and power density of the laser machine (which can be a straight line or a curve), and combining it with the target power density range for welding the current type of copper mesh and the current type of heat spreader, the corresponding target output power range can be determined. This allows for precise matching of the welding test power and ensures the reliability of the welding test.

[0108] The current laser welding machine is used to perform laser welding on selected segments of the target welding path for the current copper mesh sample and the current heat spreader sample. Temperature detection is used to determine the average temperature of the primary, secondary, and tertiary proximity regions corresponding to the selected segment. Comparing the average temperature of the primary proximity region with the target oxidation temperature range effectively monitors the temperature during the welding process. Maintaining a suitable temperature meets the oxidation requirements, preventing abnormal temperatures from affecting the oxidation effect and the performance of the welded parts, thus further ensuring welding quality.

[0109] The first correction coefficient is determined based on the temperature difference value obtained from the test, which provides a basis for laser power adjustment in the subsequent welding process. This helps to continuously optimize welding process parameters and make the welding process more scientific and efficient.

[0110] Welding tests are conducted before mass production to identify potential problems in advance. If an anomaly is detected and an alarm is triggered during the test based on the first correction factor and the average temperature of the primary adjacent area, process parameters or equipment status can be adjusted in a timely manner to avoid scrap in mass production, reduce production losses, and improve production efficiency.

[0111] Performance testing of laser machines under standard conditions allows for monitoring of the equipment's status. This facilitates data retrieval and comparison during equipment use, enabling timely detection of performance changes and providing data support for equipment maintenance and calibration.

[0112] Example 4, based on Example 3, further includes the following welding test process:

[0113] Step 29: Determine the second correction coefficient based on the latest obtained power efficiency and power efficiency decay rate; specifically: obtain the power efficiency of the laser of the laser machine within the latest preset time period, determine the power efficiency array sorted by time, and determine the latest power efficiency and power efficiency decay rate based on the power efficiency array;

[0114] Step S210: Determine the first welding input power range corresponding to the current batch and current type of copper mesh and the current type of heat spreader based on the first correction coefficient and the second correction coefficient. If the first welding input power range corresponding to the current batch and current type of copper mesh and the current type of heat spreader is not within the allowable input power range of the laser of the current laser machine, an alarm is triggered.

[0115] When the first welding input power range corresponding to the current batch of the current type of copper mesh and the current type of heat spreader has a target welding input power range that overlaps with the allowable input power range of the laser of the current laser machine, when step S2 is started to be executed in batches for the current batch of the current type of copper mesh and the current type of heat spreader, the actual input power of the laser of the current laser machine is controlled to be the minimum value of the target welding input power range.

[0116] The second correction factor W is calculated as follows:

[0117] ;

[0118] For the latest power efficiency, To obtain the latest power efficiency degradation rate; This represents the theoretical total welding time for the current batch of copper mesh of the current type and the current type of heat spreader.

[0119] The first welding input power range corresponding to the current batch and type of copper mesh and the current type of heat spreader. ; The maximum value of the target output power range determined in step S22; The median of the target output power range determined in step S22;

[0120] Using embodiments of the present invention, the cooling pass rate for batch cooling is greater than 99.2%;

[0121] The beneficial effects of the above technical solution are as follows:

[0122] The first correction coefficient is determined based on the temperature difference value obtained from the test, and the second correction coefficient is determined based on the latest power efficiency and power efficiency decay rate. This allows the welding power to be adapted to the actual situation of the laser and the welding requirements, thereby improving the accuracy of power control and ensuring stable welding quality.

[0123] Based on the first correction coefficient and the second correction coefficient, the first welding input power range corresponding to the current batch and current type of copper mesh and current type of heat spreader is determined. Based on the first welding input power range corresponding to the current batch and current type of copper mesh and current type of heat spreader, an alarm coefficient is determined. When the alarm coefficient is less than a preset value (such as 0 or 0.1), an alarm is triggered. When an alarm is triggered, it can remind the user to replace other laser machines of the current type of laser machine, and remind the user to repair or replace the relevant parts of the laser of the current laser machine. This ensures the stability of the quality of the current batch and current type of copper mesh and current type of heat spreader in mass production.

[0124] Example 5, based on any one of Examples 1-4,

[0125] It also includes: Step S3: dissipating heat from the product 4 obtained in step S2; in step S3, the product 4 obtained in step S2 is placed inside the heat dissipation frame 1, and all the cooling nozzles 2 on the heat dissipation frame 1 spray cooling medium to dissipate heat from the entire surface of the product 4 obtained in step S2. The cooling nozzles 2 can be installed on the telescopic end of the telescopic rod 3, and the fixed end of the telescopic rod 3 is installed on the heat dissipation frame 1; specifically as follows... Figure 8 As shown;

[0126] Before each batch of the current type of copper mesh and the current type of heat spreader begins to execute step S3, select the sample of the current batch of the current type of copper mesh and the current type of heat spreader that has been welded according to the welding requirements (including the second and third samples below. Because the second sample requires temperature detection, the cooling time may be delayed and the cooling effect cannot be accurately tested, so another sample is selected for testing) to carry out the heat dissipation test step.

[0127] Among them, the target flow rate of the same batch of products, such as the current type of copper mesh and the current type of heat spreader, which are welded according to the welding requirements, can also be determined based on only one heat dissipation test step.

[0128] The heat dissipation test steps include:

[0129] Step S31: Before cooling, perform temperature detection on the surface of the second sample after welding the current batch and current type of copper mesh and current type of heat spreader according to the welding requirements; existing temperature detection methods can be used.

[0130] Based on the temperature detection results, the surface of the second sample (the surface that can be directly swept by the cooling medium) is divided into several different sub-regions. Each sub-region is composed of adjacent surfaces, and the standard deviation of the temperature detection values ​​of all temperature detection points in each sub-region (which is the existing technology) is less than the preset standard deviation (preset according to the product accuracy requirements).

[0131] Step S32: Based on the required cooling rate range for each temperature stage corresponding to each surface of each sub-region of product 4 obtained in step S2, determine the required cooling flow rate range of the cooling medium for each temperature stage corresponding to each surface of each sub-region (combining the required cooling rate range for each temperature stage corresponding to each surface of each sub-region and the heat dissipation model to determine the required cooling flow rate range of the cooling medium for each temperature stage corresponding to each surface of each sub-region, which can be based on the existing heat dissipation model), and determine the first cooling flow rate of the cooling medium for each temperature stage corresponding to each sub-region; the surface categories include: heat spreader, copper mesh and weld; the end temperature of each temperature stage of each surface is a preset temperature range;

[0132] The first cooling flow rate of the cooling medium in the current temperature stage of the current sub-region is: the minimum standard deviation of the median cooling flow rate requirement range of the cooling medium for all surfaces in the current temperature stage of the current sub-region, compared with the maximum cooling flow rate requirement range of the cooling medium for other surfaces (other surfaces in the current sub-region besides the maximum cooling flow rate requirement range of the cooling medium).

[0133] ;

[0134] ;

[0135] These are the surface area of ​​the c-th surface of the current sub-region, the specific heat capacity of the c-th surface of the current sub-region, and the mass of the c-th surface of the current sub-region (for example, if the c-th surface of the current sub-region is the exposed surface of the heat spreader, then the mass is the area of ​​the heat spreader corresponding to the exposed surface multiplied by the mass corresponding to the thickness). , These are the initial temperature of the current temperature stage of the c-th surface in the current sub-region (the first temperature stage is detected based on step S31; the other temperature stages are the median of the preset temperature range corresponding to the end temperature of the previous temperature stage) and the temperature of the cooling medium (which is fixed). The minimum required cooling rate range for the cooling medium at the current temperature stage of the c-th surface in the current sub-region. The maximum required cooling rate range for the cooling medium at the current temperature stage of the c-th surface in the current sub-region. The dynamic viscosity of the cooling medium; The Prandtl number of the cooling medium; The thermal conductivity of the cooling medium; Where L is the Reynolds number (L is the characteristic length, which can be the outlet diameter of the cooling nozzle 2). , The minimum and maximum values ​​of the required cooling flow rate of the cooling medium for the current temperature stage of the c-th surface in the current sub-region.

[0136] Step S33: Obtain the third sample of the current type of copper mesh and the current type of heat spreader plate welded according to the welding requirements. When performing a cooling test at the first flow rate of the cooling medium at each temperature stage of each cooling nozzle 2, obtain the actual cooling rate of each surface of each sub-region at each temperature stage (the first difference between the average temperature detected at the beginning of the temperature stage and the average temperature detected at the end of the temperature stage, divided by the cooling time of the temperature stage to obtain the corresponding actual cooling rate), and determine the target flow rate of the cooling medium for each temperature stage corresponding to each cooling nozzle 2.

[0137] If the actual cooling rate of each surface in all sub-regions corresponding to the current cooling nozzle 2 at the current temperature stage is within the corresponding cooling rate requirement range, then the first flow rate of the cooling medium at the current temperature stage of the current cooling nozzle 2 is determined as the target flow rate of the cooling medium at the current temperature stage of the current cooling nozzle 2.

[0138] When it is impossible to determine the first flow rate of the cooling medium at the current temperature stage of the current cooling nozzle 2 as the target flow rate of the cooling medium at the current temperature stage of the current cooling nozzle 2, the second flow rate of the cooling medium at the current temperature stage of the current cooling nozzle 2 is determined based on the actual cooling rate of each surface of each sub-region of the current cooling nozzle 2 at the current temperature stage and the required range of the cooling rate of each surface of each sub-region at the current temperature stage. The second flow rate of the cooling medium at the current temperature stage of the current cooling nozzle 2 is then determined as the target flow rate of the cooling medium at the current temperature stage of the current cooling nozzle 2.

[0139] ;

[0140] Where Z is the first flow rate of the cooling medium at the current temperature stage of the current cooling nozzle 2; Y is the second flow rate of the cooling medium at the current temperature stage of the current cooling nozzle 2; and Q is the total number of corresponding sub-regions of the current cooling nozzle 2. This is the average of the correction factors for all surfaces in the g-th sub-region corresponding to the current cooling nozzle 2 at the current temperature stage;

[0141] The correction factor for the current temperature segment of the current surface of the current sub-region is: the actual cooling rate of the current temperature segment of the current surface of the current sub-region ÷ (the average of the median and maximum values ​​of the required range of the current temperature segment of the current surface of the current sub-region).

[0142] When the current batch of copper mesh and vapor chamber of the current type begins to be processed in step S3, each cooling nozzle 2 is controlled to cool the product 4 obtained in step S2 of each current batch of copper mesh and vapor chamber of the current type at the target flow rate of the cooling medium corresponding to each temperature stage.

[0143] The beneficial effects of the above technical solution are as follows:

[0144] By detecting the surface temperature of product 4 obtained in step S2, different sub-regions are divided according to the temperature standard deviation. Based on the cooling rate requirements of each surface and temperature stage in each sub-region, the required range of cooling medium flow rate and the first cooling flow rate are determined. This allows for precise control of the cooling medium flow rate according to the heat dissipation needs of different parts of the product, avoiding localized overheating or undercooling, ensuring uniform heat dissipation, guaranteeing the quality of the welded product, and reducing problems such as deformation and stress concentration caused by uneven heat dissipation.

[0145] By conducting cooling tests on the samples, the rationality of the initial cooling flow rate is determined, and the target flow rate is determined by comparing the actual cooling rate with the required range. This method, based on actual testing and data comparison, makes the flow rate setting of the cooling nozzle 2 more scientific and reasonable, better meeting the product's heat dissipation process requirements, improving the reliability of heat dissipation effect, and ensuring the high quality and stability of each batch of products.

[0146] Conducting heat dissipation tests on prototypes before mass production can identify potential problems during the heat dissipation process, such as insufficient cooling rate. Timely adjustment of the cooling nozzle flow rate parameters can prevent heat dissipation defects in batch products, reduce scrap rates, improve production efficiency, and lower production costs.

[0147] This solution allows for flexible adjustment of heat dissipation parameters based on the welding requirements of different types of copper mesh and heat spreaders, as well as the characteristics of various parts of the product (such as different surfaces of the heat spreader, copper mesh, and weld seams). It can adapt to the heat dissipation requirements of various products, improving the versatility and flexibility of the process.

[0148] Using step S3 of the present invention, the cooling qualification rate of batch cooling is greater than 99.3%.

[0149] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Thus, if these modifications and variations of this invention fall under the claims of this invention and their equivalents...

Claims

1. A process for manufacturing a heat spreader, characterized in that: include: Step S1: Position the copper mesh and the lower cover of the heat spreader and place them into the fixture of the laser machine; Step S2: Determine the laser path of the laser machine and perform laser engraving. The laser beam will bond the copper mesh to the bottom cover of the heat spreader. The high temperature emitted by the laser beam changes the roughness of the copper mesh, achieving the oxidation effect. During the repeated execution of step S2, the laser machine periodically performs a power efficiency evaluation process to determine whether the power efficiency of the laser is normal. An alarm is triggered when the power efficiency of the laser is abnormal. The power efficiency evaluation process includes: Step S201: Obtain the power efficiency of the laser machine within the latest preset time period, determine the power efficiency array sorted by time, and determine the latest power efficiency and power efficiency decay rate based on the power efficiency array; Step S202: When either the latest power efficiency is less than the preset power efficiency or the power efficiency decay rate is greater than the corresponding preset decay rate, an alarm is triggered to indicate abnormal power efficiency. Power efficiency is: the output power of the laser in the laser machine / the input power of the laser in the laser machine.

2. The process for manufacturing a heat spreader according to claim 1, characterized in that: The material of the heat spreader is any one of copper, stainless steel, or copper-steel.

3. The process for manufacturing a heat spreader according to claim 1, characterized in that: Before step S1, the steps include: cleaning the surfaces of the copper mesh and the heat spreader; checking whether the bottom cover of the heat spreader is flat; and checking whether the copper mesh and the heat spreader are oxidized.

4. The process for manufacturing a heat spreader according to claim 1, characterized in that: Before each batch of the current type of copper mesh and the current type of heat spreader begins to execute step S1, a welding test process is performed.

5. The process for manufacturing a heat spreader according to claim 4, characterized in that: The welding test process includes: Step S21: Obtain the laser output power versus power density correlation line of the laser machine under the standard conditions of the current type of laser machine used initially; Step S22: Obtain the target power density range for welding the current type of copper mesh to the current type of heat spreader, and the target output power range corresponding to the target power density range determined by the correlation line between the output power and power density of the laser in the laser machine; Step S23: Under the standard conditions of the current type of laser machine used initially, when the output power of the laser of the current type of laser machine is the median of the target output power range, when laser welding the current type of copper mesh sample and the current type of heat spreader plate sample with the selected route segment in the target welding route, the average temperature of the first-level adjacent area, the second-level adjacent area, and the third-level adjacent area of ​​the selected route segment of the current type of copper mesh sample and the current type of heat spreader plate sample is carried out. Step S24: Obtain the target oxidation temperature range and target oxidation time for each area of ​​the copper mesh during the laser welding process of the current type of copper mesh and the current type of heat spreader; Step S25: Control the current laser machine to use the output power of the laser of the current type of laser machine as the median of the target output power range, and perform laser welding on the selected route segment in the target welding path of the current copper mesh sample and the current heat spreader sample, and determine the average temperature of the first-level proximity area, second-level proximity area and third-level proximity area corresponding to the selected route segment through temperature detection. Step S26: Based on steps S25 and S23, determine the temperature difference values ​​of the first-level adjacent area, the second-level adjacent area, and the third-level adjacent area; Step S27: Determine the first correction coefficient based on the temperature difference value obtained in step S26; Step S28: An alarm is triggered if any of the following occurs: the first correction coefficient is greater than the preset correction coefficient, or the average temperature of the first-level adjacent area obtained in step S25 is not within the corresponding target oxidation requirement temperature range.

6. The process for manufacturing a heat spreader according to claim 5, characterized in that: The welding test process also includes: Step 29: Determine the second correction factor based on the latest obtained power efficiency and power efficiency decay rate; Step S210: Determine the first welding input power range corresponding to the current batch and current type of copper mesh and the current type of heat spreader based on the first correction coefficient and the second correction coefficient. If the first welding input power range corresponding to the current batch and current type of copper mesh and the current type of heat spreader is not within the allowable input power range of the laser of the current laser machine, an alarm is triggered. When the first welding input power range corresponding to the current batch of the current type of copper mesh and the current type of heat spreader has a target welding input power range that overlaps with the allowable input power range of the laser of the current laser machine, when step S2 is started to be executed in batches for the current batch of the current type of copper mesh and the current type of heat spreader, the actual input power of the laser of the current laser machine is controlled to be the minimum value of the target welding input power range.

7. The process for manufacturing a heat spreader according to claim 1, characterized in that: Also includes: Step S3: Heat the product (4) obtained in step S2; in step S3, the product (4) obtained in step S2 is placed in the heat dissipation rack (1), and all the cooling nozzles (2) on the heat dissipation rack (1) spray cooling medium to achieve heat dissipation on the entire surface of the product (4) obtained in step S2.

8. The process for manufacturing a heat spreader according to claim 7, characterized in that: Before each batch of the current type of copper mesh and the current type of heat spreader begins to execute step S3, select the samples of the current batch of the current type of copper mesh and the current type of heat spreader that have been welded according to the welding requirements and perform the heat dissipation test step.

9. The process for manufacturing a heat spreader according to claim 8, characterized in that: The heat dissipation test steps include: Step S31: Before cooling, perform temperature detection on the surface of the second sample after welding the current batch of copper mesh and the current type of heat spreader according to the welding requirements at the temperature detection point. Based on the temperature detection results, the surface of the second sample is divided into several different sub-regions. Each sub-region is composed of adjacent surfaces, and the standard deviation of the temperature detection values ​​of all temperature detection points in each sub-region is less than the preset standard deviation. Step S32: Determine the cooling flow rate requirement range of the cooling medium for each temperature stage corresponding to each surface of each sub-region of the product (4) obtained in step S2, and determine the first cooling flow rate of the cooling medium for each temperature stage corresponding to each sub-region; the surface categories include: heat spreader, copper mesh and weld; the end temperature of each temperature stage of each surface is a preset temperature range. The first cooling flow rate of the cooling medium in the current temperature stage of the current sub-region is: the minimum standard deviation of the median cooling flow rate requirement range of the cooling medium corresponding to all surfaces in the current temperature stage of the current sub-region, compared with the median cooling flow rate requirement range of the cooling medium of other surfaces. Step S33: Obtain the third sample of the current type of copper mesh and the current type of heat spreader plate welded according to the welding requirements. When performing a cooling test at the first flow rate of the cooling medium at each temperature stage of each cooling nozzle (2), obtain the actual cooling rate of each surface of each sub-region at each temperature stage, and determine the target flow rate of the cooling medium corresponding to each temperature stage of each cooling nozzle (2).

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