Rapid and high-precision measurement method for assembling micro-gap of soft medium heat dissipation material

Abstract

The invention discloses a rapid and high-precision measurement method for a soft medium heat dissipation material assembly micro-gap, and relates to the field of electronic equipment assembling.The method comprises the steps that linear scanning is conducted on a circuit board to be measured and a heat dissipation box through three-dimensional laser, a three-dimensional point cloud model of a product to be measured is established, and the warping condition of a point cloud around the circuit board is corrected through an algorithm; and the point cloud model is automatically assembled through the reference, and then the gap fluctuation condition is measured for evaluation. According to the measuring method, the problem that the workload of traditional manual measurement is large is greatly solved, the problem of local overpressure or over-looseness caused by single-point laser measurement is solved, and the measuring precision is improved.

Description

Technical Field

[0001] The invention relates to the field of electronic equipment assembly, and in particular to a method for rapid and high-precision measurement of micro-gap in soft dielectric heat dissipation material assembly. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0003] The development trend of electronic information technology is that the complexity of equipment systems is increasing, and electronic products are developing towards high density and high integration. Heat dissipation design often tends to the limit, and heat dissipation problems are gradually becoming prominent. Therefore, temperature control has become a crucial link in design, manufacturing and assembly. Failure of the temperature control link will cause overheating and damage of components, becoming one of the main causes of quality problems in electronic equipment. Studies have shown that the service life of electronic components is closely related to temperature. Usually, if the operating temperature increases by 10 to 15°C, the service life of electronic components will be shortened by two times.

[0004] In recent years, electronic equipment has gradually developed towards high-density integration, and chip power consumption has become increasingly larger. Commonly used thermal interface materials include thermal insulating pads and thermal grease. In particular, thermal insulating pads have caused chip overheating and burning many times during use due to inappropriate specifications and high assembly stress, resulting in the scrapping of high-value devices.

[0005] Manual assembly of thermal interface materials cannot meet the assembly accuracy requirements. As a typical thermal interface material, thermally conductive insulating pads play an important role in the heat dissipation of components. They are installed between components and heat spreaders to fill the air gap between the two and provide heat dissipation channels for components. They have good viscosity, flexibility, good compression performance and excellent thermal conductivity. There is a very small uneven gap between the components and the heat dissipation structure. If the two components are directly installed together, the actual contact area is only about 10% of the area of ​​the heat dissipation component, and the rest is air gap. Air is a poor thermal conductor with a thermal conductivity of only 0.024W / (m·K), which seriously affects heat transfer. Use high thermal conductivity thermal interface materials to fill the air gap, improve the contact between heat-generating components and heat dissipation components, establish an effective heat transfer channel, reduce the interface contact thermal resistance, and maximize the role of the heat dissipation component.

[0006] Since the thermal insulation pad is a soft dielectric material with different shapes and sizes, it mainly relies on manual measurement during the production process, and the measurement process during the assembly process mainly relies on vernier calipers, which has low measurement accuracy, large workload, and no record of measurement data. With the uncertainty of production capacity, the complexity of products, and the increase in the number of chips, the workload of thermal insulation pad measurement has increased sharply, the manual work is cumbersome, and the work quality is difficult to guarantee, which can easily lead to thermal insulation pad assembly tolerance and product quality problems. The current manual operation method uses a vernier caliper to measure the height of the upper surface of the component and the heat-spreading boss, and then converts the thermal gap. This method has low efficiency, large errors, and ignores the influence of flatness fluctuations; many current automated equipment uses laser single-point measurement of thermal gaps, ignoring the influence of flatness fluctuations, and is not suitable for multi-variety, small-batch product production models. For example, in patent CN110160456A, a device for realizing rapid measurement of tiny assembly gaps is proposed. Its principle is single-point laser ranging, and the movable magnetic tooling used on the base may cause product components to fail, which cannot meet the measurement needs of multiple varieties.

[0007] In order to reduce the measurement workload of soft dielectric heat dissipation materials, improve measurement accuracy, and reduce the fluctuation degree of thermal conductive gap corresponding to a single chip for evaluation, rapid and accurate measurement of thermal conductive gap is a prerequisite for efficient and precise assembly of thermal conductive insulation pads. Therefore, it is necessary to study the rapid and high-precision measurement method of micro-gap in the assembly of soft dielectric heat dissipation materials. Summary of the invention

[0008] The purpose of the present invention is to address the problems that the current manual measurement method has low efficiency and large errors, and the single-point measurement method is not suitable for multi-variety and small-batch products due to the limitations of automatic recognition of the thermal gap position and program entry. On the basis of traditional vernier calipers and single-point laser measurement, a method for rapid and high-precision measurement of micro-gaps in the assembly of soft dielectric heat dissipation materials is provided. A high-precision sensor and data analysis algorithm are used to quickly and accurately measure the thermal gap, and the fluctuation degree of the thermal gap is evaluated, so that the assembly efficiency and accuracy are improved through this method.

[0009] The technical solution of the present invention is as follows:

[0010] A method for rapid and high-precision measurement of micro-gap in soft dielectric heat dissipation material assembly, comprising:

[0011] Step S1: Scan the circuit board and the heat dissipation box to be tested by a 3D laser to establish a 3D point cloud model of the product to be tested;

[0012] Step S2: Correct the warping of the point cloud of the bypassed circuit board through an algorithm, and automatically assemble the point cloud model through a benchmark;

[0013] Step S3: Measure the gap fluctuation for evaluation.

[0014] Furthermore, the step S1 comprises:

[0015] The 3D laser line scanning device is installed on the servo motion mechanism to perform 3D laser scanning on the circuit board and the heat sink box. The return data of the 3D laser line scanning device is decoded, and combined with the real-time positioning information of the servo motion mechanism, the time stamps of the two data are aligned and the difference is matched to calculate a high-precision 3D point cloud model reflecting the surface contours of the circuit board and the heat sink box.

[0016] Furthermore, the step S2 comprises:

[0017] Step S21: using the PCL point cloud library-based geometric surface recognition technology to obtain the planarity quantitative evaluation result of the circuit board, and on this basis, performing a three-dimensional space rigid body transformation on each point in the circuit board point cloud to correct the warping deformation of the circuit board point cloud and simulate the effect of the circuit board being flattened after the screw is tightened and installed;

[0018] Step S22: Identify the three-dimensional geometric contour features of the circuit board and the heat dissipation box point cloud, and distinguish the assembly surfaces of the two; place the two point clouds in the same three-dimensional coordinate system, perform three-dimensional rigid body transformation according to the relative position relationship of the assembly surfaces of the two, and realize automatic assembly of the point clouds of the two.

[0019] Furthermore, the step S3 comprises:

[0020] Step S31: Rapidly identify the thermal gap;

[0021] Step S32: thermal gap fluctuation assessment;

[0022] Step S33: Output the result based on the quantitative evaluation of the gap fluctuation.

[0023] Furthermore, the step S31 includes:

[0024] Develop a rapid identification and program entry technology for the location of thermal gaps based on three-dimensional point clouds to achieve rapid identification of thermal gaps.

[0025] Furthermore, the three-dimensional point cloud-based rapid identification and program entry technology for heat transfer gap positions includes:

[0026] By integrating the point cloud data obtained by 3D laser line scanning and the color texture information obtained by monocular camera photography, a realistic and detailed virtual 3D model is obtained; through the human-computer interaction interface and operation logic, staff can click on the upper surface of components where thermal conductive insulation pads need to be mounted on the virtual 3D model.

[0027] Furthermore, the step S32 includes:

[0028] After identifying the thermal gap, a quantitative analysis is performed on the surfaces on both sides of the gap to calculate their respective flatness, parallelism, and relative position and posture, thereby quantitatively evaluating the gap fluctuation.

[0029] Furthermore, the output result includes: a thermal gap value and alarm information.

[0030] Furthermore, the step S33 includes:

[0031] Based on the quantitative evaluation of the gap fluctuation, the following two results are output:

[0032] a. If the gap fluctuation is within the tolerance, the thermal gap value is output;

[0033] b. If the gap fluctuation exceeds the tolerance, an alarm message and a detailed alarm report will be output.

[0034] Furthermore, the thermal conductive gap value includes a maximum value, a minimum value, and an average value of the corresponding gap.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The present invention proposes a method for fast and high-precision measurement of micro-gaps in the assembly of soft dielectric heat dissipation materials based on three-dimensional laser line scanning. The circuit board to be measured and the heat dissipation box are scanned by three-dimensional laser to establish a three-dimensional point cloud model of the product to be measured. The warping of the point cloud of the bypassed circuit board is corrected by an algorithm, and the point cloud model is automatically assembled through a benchmark, and then the gap fluctuation is measured for evaluation. Through the above-mentioned measurement method, the problem of large workload in traditional manual measurement is greatly reduced, and the problem of local overpressure or looseness caused by single-point laser measurement is solved, thereby improving the measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is the technical roadmap for rapid and high-precision measurement of thermal gaps of the present invention;

[0038] Figure 2 It is the technical roadmap for rapid identification of the heat transfer gap position and program entry of the present invention;

[0039] Figure 3 It is a technical roadmap for rapid and automatic identification and program entry of thermal gap positions based on relative position coordinates of three-dimensional point clouds. DETAILED DESCRIPTION

[0040] It should be noted that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0041] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0042] Embodiment 1

[0043] See also Figure 1-3 , a method for rapid and high-precision measurement of micro-gap in soft dielectric heat dissipation material assembly, specifically comprising the following steps:

[0044] Step S1: Scan the circuit board and the heat dissipation box to be tested by a 3D laser to establish a 3D point cloud model of the product to be tested;

[0045] Step S2: Correct the warping of the point cloud of the bypassed circuit board through an algorithm, and automatically assemble the point cloud model through a benchmark;

[0046] Step S3: measuring the gap fluctuation for evaluation;

[0047] The above measurement method greatly reduces the heavy workload of traditional manual measurement, solves the problem of local overpressure or looseness caused by single-point laser measurement, and improves the measurement accuracy.

[0048] In this embodiment, specifically, step S1 is contour acquisition: obtaining the precise surface contours of the circuit board and the heat dissipation box;

[0049] The 3D laser line scanning device is installed on the servo motion mechanism to perform 3D laser scanning on the circuit board and the heat dissipation box. The return data of the 3D laser line scanning device is decoded, and combined with the real-time positioning information of the servo motion mechanism, the time stamps of the two data are aligned and the difference is matched to calculate a high-precision 3D point cloud model reflecting the surface contours of the circuit board and the heat dissipation box.

[0050] In this embodiment, specifically, step S2 is circuit board point cloud warping correction, including:

[0051] Step S21: using the PCL point cloud library-based geometric surface recognition technology to obtain the planarity quantitative evaluation result of the circuit board, and on this basis, performing a three-dimensional space rigid body transformation on each point in the circuit board point cloud to correct the warping deformation of the circuit board point cloud and simulate the effect of the circuit board being flattened after the screw is tightened and installed;

[0052] Step S22: Identify the three-dimensional geometric contour features of the circuit board and the heat dissipation box point cloud, and distinguish the assembly surfaces of the two; place the two point clouds in the same three-dimensional coordinate system, perform three-dimensional rigid body transformation according to the relative position relationship of the assembly surfaces of the two, and realize automatic assembly of the point clouds of the two.

[0053] In this embodiment, specifically, step S3 includes:

[0054] Step S31: Rapidly identify the thermal gap;

[0055] Step S32: thermal gap fluctuation assessment;

[0056] Step S33: Output the result based on the quantitative evaluation of the gap fluctuation.

[0057] In this embodiment, specifically, step S31 includes:

[0058] Develop a technology for rapid identification of thermal gap locations and program entry based on three-dimensional point clouds to achieve rapid identification of thermal gaps;

[0059] That is, by integrating the point cloud data obtained by the three-dimensional laser line scanning and the color texture information obtained by the monocular camera, a realistic and detailed virtual three-dimensional model is obtained; through the human-computer interaction interface and operation logic, the staff can click on the upper surface of the component where the thermal insulating pad is to be mounted on the virtual three-dimensional model; in view of the fact that the method of automatically identifying the thermal conductive gap requires unified drawing design specifications and the recognition rate is difficult to guarantee, etc., in this embodiment, it is intended to realize rapid and accurate recognition of the thermal conductive gap through friendly and efficient human-computer interaction to ensure the recognition rate.

[0060] In this embodiment, specifically, step S32 includes:

[0061] After identifying the thermal gap, a quantitative analysis is performed on the surfaces on both sides of the gap to calculate their respective flatness, parallelism, and relative position and posture, thereby quantitatively evaluating the gap fluctuation.

[0062] In this embodiment, specifically, step S33 includes:

[0063] Based on the quantitative evaluation of the gap fluctuation, the following two results are output:

[0064] a. If the gap fluctuation is within the tolerance, the thermal gap value is output for the subsequent automatic selection, cutting, and mounting of thermal insulation pads. The gap value here includes the maximum, minimum, and average values ​​of the gap. Compared with only feeding back the average value, feeding back the above three values ​​at the same time can provide a more comprehensive quantitative description of the gap;

[0065] b. If the gap fluctuation exceeds the tolerance, an alarm message and a detailed alarm report will be output to guide rework and repair. Different from the previous single-point measurement, the thermal gap measurement method based on three-dimensional contour helps to check the gap fluctuation and promptly detect the gap deviation, so as to avoid the poor contact of the thermal insulation pad in a part of the thermal gap, resulting in poor heat dissipation, and the excessive pressure in a part of the gap, resulting in stress and strain, affecting the life of the PCB and solder joints. In short, the evaluation of the gap fluctuation can further analyze the assembly performance of the product and effectively avoid the delivery of products with hidden dangers.

[0066] That is, after obtaining the three-dimensional point cloud data of the circuit board and the heat dissipation box, this embodiment needs to use the rapid identification and program entry technology of the thermal gap position to clarify the thermal gap position (that is, the thermal gap position) and quantify it with X, Y coordinate values, clarify the regional range of each thermal gap and quantify it with X, Y coordinate ranges. Through the above steps, the area corresponding to the thermal gap can be locked in the three-dimensional point cloud data of the circuit board and the heat dissipation box, which is convenient for further data processing of the point cloud of the area to obtain key information such as the gap size and fluctuation of the thermal gap.

[0067] The above-mentioned embodiments only express the specific implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the protection scope of the present application. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the technical solution concept of the present application, and these all belong to the protection scope of the present application.

[0068] This background section is provided to generally present the context of the invention, and the work of the presently named inventors, the work to the extent described in this background section, and aspects of this section that did not constitute prior art at the time of application are neither explicitly nor implicitly admitted to be prior art to the present invention.

Claims

1. A method for rapid and high-precision measurement of micro-gap in soft dielectric heat dissipation material assembly, characterized in that: include: Step S1: Scan the circuit board and the heat dissipation box to be tested by a 3D laser to establish a 3D point cloud model of the product to be tested; Step S2: Correct the warping of the point cloud of the bypassed circuit board through an algorithm, and automatically assemble the point cloud model through a benchmark; Step S3: Measure the gap fluctuation for evaluation.

2. A method for rapid and high-precision measurement of micro-gap in soft dielectric heat dissipation material assembly according to claim 1, characterized in that: The step S1 comprises: The 3D laser line scanning device is installed on the servo motion mechanism to perform 3D laser scanning on the circuit board and the heat sink box. The return data of the 3D laser line scanning device is decoded, and combined with the real-time positioning information of the servo motion mechanism, the time stamps of the two data are aligned and the difference is matched to calculate a high-precision 3D point cloud model reflecting the surface contours of the circuit board and the heat sink box.

3. The method for rapid and high-precision measurement of micro-gap in soft dielectric heat dissipation material assembly according to claim 1 is characterized in that: The step S2 comprises: Step S21: using the PCL point cloud library-based geometric surface recognition technology to obtain the planarity quantitative evaluation result of the circuit board, and on this basis, performing a three-dimensional space rigid body transformation on each point in the circuit board point cloud to correct the warping deformation of the circuit board point cloud and simulate the effect of the circuit board being flattened after the screw is tightened and installed; Step S22: Identify the three-dimensional geometric contour features of the circuit board and the heat dissipation box point cloud, and distinguish the assembly surfaces of the two; place the two point clouds in the same three-dimensional coordinate system, perform three-dimensional rigid body transformation according to the relative position relationship of the assembly surfaces of the two, and realize automatic assembly of the point clouds of the two.

4. The method for rapid and high-precision measurement of micro-gap in soft dielectric heat dissipation material assembly according to claim 1 is characterized in that: The step S3 comprises: Step S31: Rapidly identify the thermal gap; Step S32: thermal gap fluctuation assessment; Step S33: Output the result based on the quantitative evaluation of the gap fluctuation.

5. The method for rapid and high-precision measurement of micro-gap in soft dielectric heat dissipation material assembly according to claim 4 is characterized in that: The step S31 comprises: Develop a rapid identification and program entry technology for the location of thermal gaps based on three-dimensional point clouds to achieve rapid identification of thermal gaps.

6. The method for rapid and high-precision measurement of micro-gap in soft dielectric heat dissipation material assembly according to claim 5 is characterized in that: The three-dimensional point cloud-based rapid identification and program entry technology for heat transfer gap positions includes: By integrating the point cloud data obtained by 3D laser line scanning and the color texture information obtained by monocular camera photography, a realistic and detailed virtual 3D model is obtained; through the human-computer interaction interface and operation logic, staff can click on the upper surface of components where thermal conductive insulation pads need to be mounted on the virtual 3D model.

7. The method for rapid and high-precision measurement of micro-gap in soft dielectric heat dissipation material assembly according to claim 4 is characterized in that: The step S32 comprises: After identifying the thermal gap, a quantitative analysis is performed on the surfaces on both sides of the gap to calculate their respective flatness, parallelism, and relative position and posture, thereby quantitatively evaluating the gap fluctuation.

8. The method for rapid and high-precision measurement of micro-gap in soft dielectric heat dissipation material assembly according to claim 4 is characterized in that: The output result includes: thermal gap value and alarm information.

9. A method for rapid and high-precision measurement of micro-gap in soft dielectric heat dissipation material assembly according to claim 8, characterized in that: The step S33 comprises: Based on the quantitative evaluation of the gap fluctuation, the following two results are output: a. If the gap fluctuation is within the tolerance, the thermal gap value is output; b. If the gap fluctuation exceeds the tolerance, an alarm message and a detailed alarm report will be output.

10. A method for rapid and high-precision measurement of micro-gap in soft dielectric heat dissipation material assembly according to claim 9, characterized in that: The thermal conductive gap value includes the maximum value, minimum value and average value of the corresponding gap.

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