A circuit board screen printing detection method, system, computer equipment and readable storage medium

Abstract

The present invention relates to the field of PCB technology, and in particular to a circuit board screen printing detection method, system, computer equipment and readable storage medium, including obtaining a screen printing thickness distribution value according to the corrected solder mask area information, the insulating area information, the screen printing material information and the screen printing area surface temperature response value under a preset heat source; obtaining a screen printing adhesion reference value according to the screen printing surface flatness distribution value and the screen printing thickness distribution value; obtaining a screen printing stress distribution uniformity value according to the screen printing material information and the screen printing thickness distribution value; obtaining a screen printing quality evaluation value according to the screen printing adhesion reference value, the screen printing thickness distribution value and the screen printing stress distribution uniformity value. The present invention can quickly detect the thickness inside the screen printing, the adhesion between the screen printing and the substrate, and evaluate the internal stress of the screen printing layer based on the thickness, so as to more accurately evaluate the screen printing quality.

Description

Technical Field

[0001] The present invention relates to the field of PCB technology, and in particular to a circuit board silk screen detection method, system, computer equipment and readable storage medium. Background Art

[0002] As a key basic component of modern electronic equipment, the main function of the circuit board is to provide electrical connections and physical support for electronic components. With the rapid development of electronic technology, electronic equipment continues to evolve towards miniaturization, high performance and multi-functionality, which puts extremely stringent requirements on circuit boards. The silk screen layer plays an indispensable role in the circuit board. It is mainly used to mark important information such as component numbers, models, polarity, etc., to facilitate the assembly, debugging and maintenance of the circuit board. In the large-scale production process, accurate and clear silk screen printing can significantly improve production efficiency and reduce error rates. At the same time, for later maintenance personnel, clear silk screen printing can quickly locate faulty components, greatly shorten maintenance time, reduce equipment downtime, reduce maintenance costs, and effectively ensure the normal operation and service life of electronic equipment.

[0003] At present, most of the silk screen inspections use image recognition technology, and the inspection content is mainly the surface defects of the silk screen. The durability of the silk screen itself is closely related to the internal properties of the silk screen. The existing inspection technology is difficult to quickly detect the internal properties of the silk screen, including the adhesion between the silk screen and the substrate, the thickness of the silk screen and the stress inside the silk screen. Therefore, the durability quality assessment of the silk screen is not accurate enough. Summary of the invention

[0004] The main purpose of the present invention is to provide a circuit board silk screen detection method, system, computer equipment and readable storage medium, aiming to solve the technical problem that it is difficult to quickly detect the internal properties of the silk screen in the prior art, including the adhesion between the silk screen and the substrate, the thickness of the silk screen and the stress inside the silk screen, and therefore the durability quality assessment of the silk screen is not accurate enough.

[0005] The present invention provides a circuit board screen printing detection method, comprising:

[0006] Obtaining substrate material information of the circuit board and a substrate surface temperature response value under a preset heat source, and obtaining corrected solder mask area information according to the substrate material information and the substrate surface temperature response value;

[0007] Acquire insulation area information according to the substrate material information;

[0008] Get the silk screen material information of the circuit board and the silk screen surface temperature response value under the preset heat source;

[0009] Acquire a screen printing thickness distribution value according to the corrected solder resist area information, the insulating area information, the screen printing material information and a screen printing area surface temperature response value under a preset heat source;

[0010] Acquire silk screen image information under different preset angle light sources, acquire silk screen surface flatness distribution values ​​according to the silk screen image information, and acquire silk screen adhesion reference values ​​according to the silk screen surface flatness distribution values ​​and silk screen thickness distribution values;

[0011] Obtain the uniformity value of silk screen stress distribution according to silk screen material information and silk screen thickness distribution value;

[0012] The silk screen quality evaluation value is obtained according to the silk screen adhesion reference value, silk screen thickness distribution value and silk screen stress distribution uniformity value.

[0013] Furthermore, the step of obtaining the modified solder resist area information according to the substrate material information and the substrate surface temperature reaction value under the preset heat source includes:

[0014] Get the power and duration of the preset heat source;

[0015] Obtain solder mask area information according to substrate material information;

[0016] Acquire the temperature distribution information inside the solder resist area according to the power and duration of the preset heat source and the solder resist area information;

[0017] Acquire an estimated value of the surface temperature of the solder resist area under a preset heat source according to the internal temperature distribution information of the solder resist area and the material information of the solder resist area;

[0018] Determine whether the estimated value of the surface temperature of the solder resist area is equal to the surface temperature reaction value of the substrate under a preset heat source; if not, correct the estimated thickness of the solder resist layer in the solder resist area information until the estimated value of the surface temperature of the solder resist area is equal to the surface temperature reaction value of the substrate under a preset heat source; if equal, correct the estimated thickness of the solder resist layer in the solder resist area material information to the actual thickness of the solder resist layer to obtain the corrected solder resist area information.

[0019] Further, the step of obtaining the silk screen thickness distribution value according to the corrected solder mask area information, the insulating area information, the silk screen material information and the silk screen area surface temperature response value under a preset heat source includes:

[0020] Get the power and duration of the preset heat source;

[0021] Get silk screen material information;

[0022] Get the corrected solder mask area information;

[0023] Acquire the silk screen internal temperature distribution information of the solder resist area according to the power and duration of the preset heat source, the silk screen material information and the corrected solder resist area information;

[0024] Obtain an estimated value of the screen printing surface temperature of the solder resist area under a preset heat source according to the screen printing internal temperature distribution information of the solder resist area, the screen printing material information and the corrected solder resist area information;

[0025] Determine whether the estimated value of the screen printing surface temperature of the solder resist area is equal to the screen printing surface temperature reaction value under the preset heat source; if not, correct the estimated thickness of the screen printing layer in the solder resist area in the screen printing material information until the estimated value of the screen printing surface temperature of the solder resist area is equal to the screen printing surface temperature reaction value under the preset heat source; if equal, obtain the actual thickness of the screen printing layer in the solder resist area according to the estimated thickness of the screen printing layer in the screen printing material information;

[0026] Get insulation area information;

[0027] Acquire the internal temperature distribution information of the silk screen in the insulating area according to the power and duration of the preset heat source, the silk screen material information and the insulating area information;

[0028] Acquire an estimated value of the screen printing surface temperature of the insulating area according to the internal temperature distribution information of the screen printing area of ​​the insulating area, the screen printing material information and the insulating area information;

[0029] Determine whether the estimated value of the silk-screen surface temperature of the insulating area is equal to the silk-screen surface temperature response value under a preset heat source; if not, correct the estimated thickness of the silk-screen layer in the insulating area information until the estimated value of the silk-screen surface temperature of the insulating area is equal to the silk-screen surface temperature response value under a preset heat source; if equal, obtain the actual thickness of the silk-screen layer in the insulating area according to the estimated thickness of the silk-screen layer in the insulating area information;

[0030] The silk screen thickness distribution value is obtained according to the actual thickness of the silk screen layer in the insulating area and the actual thickness of the silk screen layer in the solder resist area.

[0031] Furthermore, the step of obtaining a reference value of silk screen adhesion according to the silk screen surface flatness distribution value and the silk screen thickness distribution value includes:

[0032] According to the flat distribution value of the silk-screen surface, the relative height value of each silk-screen pixel area and the average height value of all silk-screen pixel areas are obtained;

[0033] According to the silk screen thickness distribution value, the thickness value of each silk screen pixel area and the average thickness value of all silk screen pixel areas are obtained;

[0034] Obtain an overall correlation value of the silk-screen thickness distribution value and the silk-screen surface flatness distribution value according to the relative height value of each silk-screen pixel area, the average height value of all silk-screen pixel areas, the thickness value of each silk-screen pixel area, and the average thickness value of all silk-screen pixel areas;

[0035] A silk screen adhesion reference value is obtained according to the overall correlation value.

[0036] Furthermore, the step of obtaining the uniformity value of the silk screen stress distribution according to the silk screen material information and the silk screen thickness distribution value includes:

[0037] Get the screen printing material information of the screen printing thermal shrinkage rate;

[0038] Obtain the silk screen thickness value of each pixel area in the silk screen thermal imaging image information, and extract the maximum silk screen thickness value;

[0039] Acquire the stress value of each pixel area in the silk-screen thermal imaging image according to the thermosetting shrinkage rate, the silk-screen thickness value of each pixel area and the maximum silk-screen thickness value;

[0040] The uniformity value of silk-screen stress distribution is obtained according to the similarity between the silk-screen stress value of each pixel area in the silk-screen thermal imaging image and its adjacent points.

[0041] Furthermore, the step of obtaining the silk screen quality evaluation value according to the silk screen adhesion reference value, the silk screen thickness distribution value and the silk screen stress distribution uniformity value comprises:

[0042] Get the quality influence weight of the screen printing adhesion reference value;

[0043] Get the quality influence weight of the uniformity value of screen printing stress distribution;

[0044] Get the screen printing thickness uniformity value according to the screen printing thickness distribution value;

[0045] Get the quality influence weight of the uniformity value of screen printing thickness;

[0046] Get the reference value of screen printing adhesion and the uniformity value of screen printing stress distribution;

[0047] The silk screen quality evaluation value is obtained according to the quality influence weight of the silk screen adhesion reference value, the quality influence weight of the silk screen thickness uniformity value, the quality influence weight of the silk screen stress distribution uniformity value, the silk screen adhesion reference value, the silk screen thickness uniformity value and the silk screen stress distribution uniformity value, and the calculation formula is:

[0048] ;

[0049] In the formula, Z represents the screen printing quality assessment value, F represents the screen printing adhesion reference value, ω1 represents the quality influence weight of the screen printing adhesion reference value, H represents the screen printing thickness uniformity value, ω2 represents the quality influence weight of the screen printing thickness uniformity value, Y represents the screen printing stress distribution uniformity value, and ω3 represents the quality influence weight of the screen printing stress distribution uniformity value.

[0050] The present invention also provides a circuit board screen printing detection system, comprising:

[0051] A first acquisition module is used to acquire substrate material information of the circuit board and a substrate surface temperature reaction value under a preset heat source, and acquire corrected solder mask area information according to the substrate material information and the substrate surface temperature reaction value;

[0052] A second acquisition module, used to acquire the insulation area information according to the substrate material information;

[0053] The third acquisition module is used to obtain the silk screen material information of the circuit board and the silk screen surface temperature response value under a preset heat source;

[0054] A fourth acquisition module, used for acquiring a silk screen thickness distribution value according to the corrected solder resist area information, the insulating area information, the silk screen material information and a surface temperature response value of the silk screen area under a preset heat source;

[0055] A fifth acquisition module is used to acquire the silk screen image information under different preset angle light sources, and acquire the silk screen surface flatness distribution value according to the silk screen image information;

[0056] A sixth acquisition module, used to obtain a reference value of silk screen adhesion according to a silk screen surface flatness distribution value and a silk screen thickness distribution value;

[0057] A seventh acquisition module is used to obtain a uniformity value of silk screen stress distribution according to silk screen material information and silk screen thickness distribution value;

[0058] The eighth acquisition module is used to obtain the silk screen quality evaluation value according to the silk screen adhesion reference value, the silk screen thickness distribution value and the silk screen stress distribution uniformity value.

[0059] Furthermore, the fourth acquisition module includes:

[0060] A first acquisition unit is used to acquire the power and duration of a preset heat source, silk screen material information and modified solder mask area information;

[0061] A second acquisition unit is used to acquire the internal temperature distribution information of the silk screen in the solder resist area according to the power and duration of the preset heat source, the silk screen material information and the corrected solder resist area information;

[0062] Used to obtain an estimated value of the screen printing surface temperature of the solder resist area under a preset heat source according to the screen printing internal temperature distribution information of the solder resist area, the screen printing material information and the corrected solder resist area information;

[0063] A first value comparison and correction unit is used to determine whether the estimated value of the screen printing surface temperature of the solder resist area is equal to the screen printing surface temperature response value under the preset heat source, and correct the estimated thickness of the screen printing layer in the solder resist area in the screen printing material information to the actual thickness of the screen printing layer in the solder resist area according to the determination result;

[0064] A third acquisition unit, used for acquiring insulation area information;

[0065] A fourth acquisition unit, configured to acquire the internal temperature distribution information of the silk screen in the insulating area according to the power and duration of the preset heat source, the silk screen material information and the insulating area information;

[0066] Used to obtain an estimated value of the screen printing surface temperature of the insulating area according to the internal temperature distribution information of the screen printing area of ​​the insulating area, the screen printing material information and the insulating area information;

[0067] A second value comparison and correction unit is used to determine whether the estimated value of the screen printing surface temperature of the insulating area is equal to the screen printing surface temperature response value under a preset heat source, and correct the estimated thickness of the screen printing layer in the insulating area information to the actual thickness of the screen printing layer in the insulating area according to the determination result;

[0068] The fifth acquisition unit is used to acquire a silk screen thickness distribution value according to the actual thickness of the silk screen layer in the insulating area and the actual thickness of the silk screen layer in the solder resist area.

[0069] The present invention also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above-mentioned circuit board silk screen detection method when executing the computer program.

[0070] The present invention also provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of the above-mentioned circuit board silk screen detection method are implemented.

[0071] The beneficial effects of the present invention are as follows: the present invention can quickly detect the thickness inside the silk screen, the adhesion between the silk screen and the substrate, and evaluate the internal stress of the silk screen layer based on the thickness, so as to more accurately evaluate the silk screen quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 The figure is a schematic diagram of a method flow according to an embodiment of the present invention.

[0073] Figure 2 FIG. 1 is a schematic diagram of a system structure according to an embodiment of the present invention.

[0074] Figure 3 A schematic diagram of the internal structure of a computer device according to an embodiment of the present application.

[0075] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0076] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0077] like Figure 1-Figure 3 As shown, the present application provides a circuit board silk screen detection method, comprising:

[0078] S1, obtaining substrate material information of the circuit board and a substrate surface temperature reaction value under a preset heat source, and obtaining corrected solder mask area information according to the substrate material information and the substrate surface temperature reaction value under the preset heat source;

[0079] S2, obtaining insulation area information according to the substrate material information;

[0080] S3, obtaining the silk screen material information of the circuit board and the silk screen surface temperature response value under the preset heat source;

[0081] S4, obtaining a silk screen thickness distribution value according to the corrected solder resist area information, the insulating area information, the silk screen material information and the internal temperature distribution information of the silk screen area;

[0082] S5, obtaining screen printing image information under different preset angle light sources, obtaining a screen printing surface flatness distribution value according to the screen printing image information, and obtaining a screen printing adhesion reference value according to the screen printing surface flatness distribution value and the screen printing thickness distribution value;

[0083] S6, obtaining a uniformity value of silk screen stress distribution according to silk screen material information and silk screen thickness distribution value;

[0084] S7, comprehensively judge the quality of screen printing based on the reference value of screen printing adhesion, screen printing thickness distribution value and screen printing stress distribution uniformity value.

[0085] The silk screen printing of the circuit board will have uneven thickness. For example, uneven pressure distribution during printing due to uneven screen tension, uneven ink distribution due to inappropriate scraper angle and pressure, etc., which leads to uneven thickness of the silk screen layer after molding. For application environments with higher requirements on the quality of silk screen printing, such as in aerospace, harsh automotive electronics and industrial environments, factors such as high temperature, high humidity and high vibration frequency will have a continuous impact on silk screen printing. Therefore, long-term stability of silk screen printing is required. Then, it is necessary to know whether the silk screen printing has a high enough quality. Based on the underlying logic that materials of different thicknesses heat up at different rates under the same heat source, by obtaining the circuit board The screen printing temperature response value under the unified preset heat source, combined with the material properties of the screen printing itself, can be used to calculate the thickness of the screen printing. At the same time, taking into account that the screen printing continuously dissipates heat to the circuit board substrate material at the bottom while absorbing heat energy, the influence of the circuit board substrate material on the screen printing temperature change is taken into account, and finally a more accurate screen printing thickness distribution value is obtained, and the screen printing adhesion reference value is obtained based on the screen printing thickness distribution value. At the same time, based on the screen printing thickness distribution information and combined with the thermal curing shrinkage rate of the screen printing ink, the screen printing stress distribution uniformity value is calculated to further more accurately evaluate the quality of the screen printing.

[0086] The step of obtaining the information of the solder mask repair area according to the substrate material information and the substrate surface temperature response value under the preset heat source comprises:

[0087] S11, obtaining the power of a preset heat source and the duration of the preset heat source; the preset heat source adopts laser heating and has a heating surface with uniformly distributed laser energy;

[0088] S12, obtaining solder resist area information according to substrate material information, the solder resist area information including the heated area of ​​the solder resist layer, selecting the solder resist area close to the silk screen distribution area in the substrate material information as the heated area of ​​the solder resist layer, and obtaining the heated area of ​​the solder resist layer by calculating the area of ​​the heated area of ​​the solder resist layer, wherein the solder resist area close to the silk screen distribution area is obtained by an image recognition method; since the solder resist area under the silk screen layer is blocked, the solder resist thickness is calculated by selecting the solder resist area close to the silk screen layer area, which has the advantage that it can be quickly obtained through thermal imaging image information of the circuit board under a preset heat source;

[0089] The solder mask area information also includes the estimated thickness of the solder mask layer, the thermal conductivity of the solder mask layer, the energy absorption rate of the solder mask layer, the thermal conductivity of the copper foil layer, and the estimated thickness of the copper foil layer;

[0090] S13, obtaining the estimated thermal conductivity spatial step length of the solder resist layer and the estimated thermal conductivity spatial step length of the copper foil layer, and dividing the estimated thickness of the solder resist layer and the estimated thickness of the copper foil layer in the region into a plurality of solder resist layer depth nodes and a plurality of copper foil layer depth nodes according to the estimated thermal conductivity spatial step length of the solder resist layer and the estimated thermal conductivity spatial step length of the copper foil layer, wherein the plurality of solder resist layer depth nodes are represented as i 1 =1,2,3...n 1 , several copper foil layer depth nodes are represented as i 2 =1,2,3...n 2 ;

[0091] The estimated thermal conductivity space step length of the solder mask layer and the estimated thermal conductivity space step length of the copper foil layer are obtained based on the estimated thickness of the solder mask layer and the estimated thickness of the copper foil layer. The calculation formulas for the estimated thermal conductivity space step length of the solder mask layer and the estimated thermal conductivity space step length of the copper foil layer are:

[0092] ;

[0093] ;

[0094] In the formula, Indicates the estimated thermal conductivity space step of the solder mask layer. Indicates the estimated thermal conductivity space step of the copper foil layer, L1 indicates the estimated thickness of the solder mask layer, L2 indicates the estimated thickness of the copper foil layer, m 3 Indicates the total number of solder mask depth nodes, m 4 Indicates the total number of copper foil layer depth nodes;

[0095] S14, obtaining the internal temperature distribution information of the solder resist area under the estimated thickness of the solder resist layer according to the power of the preset heat source, the duration of the preset heat source, the heated area of ​​the solder resist layer, the thermal conductivity of the solder resist layer, the energy absorption rate of the solder resist layer, the thermal conductivity of the copper foil layer, the estimated thermal conductivity spatial step length of the solder resist layer, and the estimated thermal conductivity spatial step length of the copper foil layer;

[0096] The temperature distribution information inside the solder mask area includes the temperature of each solder mask layer depth node and the temperature of each copper foil layer depth node in the area. The temperature calculation formula for each solder mask layer depth node is:

[0097] ;

[0098] In the formula, Indicates the i 1 +1 solder mask layer depth node temperature at time j, Indicates the i 1 The temperature of the solder mask depth node at time j, P represents the power of the preset heat source, t represents the duration of the preset heat source, G represents the energy absorption rate of the solder mask, A represents the heated area of ​​the solder mask, and k represents the energy absorption rate of the solder mask.1 Represents the thermal conductivity of the solder mask layer, Indicates the estimated thermal conductivity space step of the solder mask layer;

[0099] At the interface between the solder mask layer and the copper foil layer, the temperature and heat flux density are continuous, that is, the temperature of the bottom surface of the solder mask layer is equal to the temperature of the top surface of the copper foil layer. It is equal to the temperature of the upper surface of the copper foil layer at time j, so it can be calculated continuously;

[0100] The temperature calculation formula for each copper foil layer depth node is:

[0101] ;

[0102] In the formula, Indicates the i 2 +1 copper foil layer depth node temperature at time j, Indicates the i 2 The temperature of the copper foil layer depth node at time j, Indicates the estimated thermal conductivity space step length of the copper foil layer, k 2 Indicates the thermal conductivity of the copper foil layer;

[0103] S15, obtaining solder mask density, solder mask specific heat capacity, copper foil density and copper foil specific heat capacity of solder mask area information;

[0104] S16, obtaining a preset heat transfer time step according to the duration of the preset heat source; dividing the duration of the preset heat source into a plurality of shorter time periods, each of which is the preset heat transfer time step, and calculating each shorter time period successively to obtain a more accurate calculation result;

[0105] S17, obtaining an estimated value of the surface temperature of the solder resist area at the estimated thickness of the solder resist layer after the preset heat source ends according to the internal temperature distribution information of the solder resist area, the density of the solder resist layer, the specific heat capacity of the solder resist layer, the density of the copper foil layer, the specific heat capacity of the copper foil layer, the preset thermal conductivity time step, the estimated thermal conductivity space step of the solder resist layer, and the estimated thermal conductivity space step of the copper foil layer;

[0106] S18, determine whether the estimated value of the surface temperature of the solder resist area is equal to the surface temperature reaction value of the substrate under the preset heat source; if not, correct the estimated thickness of the solder resist layer in the solder resist area information, specifically, correct the estimated thickness of the solder resist layer by adjusting the estimated thermal conductivity space step of the solder resist layer until the estimated value of the surface temperature of the solder resist area is equal to the surface temperature reaction value of the substrate under the preset heat source; if equal, correct the estimated thickness of the solder resist layer in the solder resist area material information to the actual thickness of the solder resist layer to obtain the corrected solder resist area information.

[0107] The substrate surface temperature response value under the preset heat source is obtained through the thermal imaging images of the silk-screen surface at different times. Therefore, the substrate surface temperature response value includes the temperature value of each pixel point of the thermal imaging image of the silk-screen surface. If the solder mask layer is thin, it will transfer heat to the copper foil layer below more quickly when heated, and the heating rate will be slower. If the solder mask layer is thicker, it will transfer heat to the copper foil layer below more slowly when heated, and the heating rate will be faster. Therefore, when the estimated surface temperature of the solder mask area is greater than the substrate surface temperature response value under the preset heat source, it means that the actual thickness of the solder mask layer may be less than the estimated thickness of the solder mask layer, resulting in the actual substrate surface temperature response value being less than the estimated surface temperature of the solder mask area. At this time, the estimated thermal conductivity spatial step length of the solder resist layer can be reduced and adjusted to reduce the estimated thickness of the solder resist layer. When the estimated surface temperature value of the solder resist area is less than the substrate surface temperature reaction value under the preset heat source, it means that the actual thickness of the solder resist layer may be greater than the estimated thickness of the solder resist layer, resulting in the actual substrate surface temperature reaction value being greater than the estimated surface temperature value of the solder resist area. At this time, the estimated thermal conductivity spatial step length of the solder resist layer can be increased and adjusted to increase the estimated thickness of the solder resist layer. The estimated thermal conductivity spatial step length of the solder resist layer is selectively increased or decreased until the estimated surface temperature value of the solder resist area is equal to the substrate surface temperature reaction value under the preset heat source, and finally the actual thickness of the solder resist layer is obtained.

[0108] The estimated value of the surface temperature of the solder resist area is calculated based on the estimated temperature of the internal nodes of the solder resist area. The estimated temperature of the internal nodes of the solder resist area includes the estimated temperature of each solder resist layer depth node and the estimated temperature of each copper foil layer depth node in the area.

[0109] The estimated temperature calculation formula for each solder mask depth node is:

[0110] ;

[0111] In the formula, Indicates the i 1 The temperature of the solder mask depth node at time j+1, Indicates the i 2 The temperature of the solder mask depth node at time j, Indicates the estimated thermal conductivity space step of the solder mask layer, k 1 Represents the thermal conductivity of the solder mask, ρ 1 is the solder mask density, c 1 is the specific heat capacity of the solder mask layer, Δt represents the preset time step of thermal conduction, Indicates the i 1 +1 solder mask layer depth node temperature at time j, Indicates the i 1 -1 Temperature of solder mask depth node at time j;

[0112] The estimated temperature calculation formula for each copper foil layer depth node is:

[0113] ;

[0114] In the formula, Indicates the i 2 The temperature of the copper foil layer depth node at time j+1, Indicates the i 2 The temperature of the copper foil layer depth node at time j, Indicates the estimated thermal conductivity space step length of the copper foil layer, k 2 represents the thermal conductivity of the copper foil layer, ρ 2 is the density of the copper foil layer, c 2 is the specific heat capacity of the copper foil layer, Δt represents the preset time step of thermal conduction, Indicates the i 2 +1 copper foil layer depth node temperature at time j, Indicates the i 2 -The temperature of a copper foil layer depth node at time j;

[0115] According to the above calculation method, an estimated value of the surface temperature of the solder resist area can be obtained.

[0116] When the silk screen of the circuit board is printed on the substrate of the circuit board, it will overlap with the solder mask area and the insulating area. When the silk screen is heated under a preset heat source, the temperature surface reaction value of the silk screen under the preset heat source is actually related to the solder mask area and the insulating area below the silk screen. Since the solder mask layer is thin, in order for the heat of the preset heat source to penetrate the silk screen layer, sufficient heating time needs to be guaranteed. Then the heat of the preset heat source may also be conducted to the solder mask layer passing through the solder mask area and reach the copper foil layer in the solder mask area. Therefore, the actual thickness of the solder mask layer in the solder mask area will affect the silk screen surface temperature reaction value under the preset heat source. The material properties in the solder mask area information are known and generally do not change. However, due to the error factors of the manufacturing process, the thickness of the solder mask layer is not completely uniform, and the actual thickness of the solder mask layer in the solder mask area information may be uneven. Therefore, before calculating the silk screen thickness, this scheme adopts a method of pre-correcting the thickness of the solder mask layer, and then obtaining the actual thickness of the silk screen layer based on the corrected actual thickness of the solder mask layer, so that the value of the actual thickness of the silk screen layer is more accurate.

[0117] The step of obtaining the silk screen thickness distribution value according to the corrected solder mask area information, the insulating area information, the silk screen material information and the silk screen surface temperature response value under the preset heat source comprises:

[0118] S41, obtaining the power and duration of a preset heat source;

[0119] S42, obtaining silk screen material information of the silk screen area of ​​the solder mask region, the estimated thickness of the silk screen layer in the solder mask region, the thermal conductivity of the silk screen layer, and the silk screen energy absorption rate;

[0120] S43, obtaining the estimated thermal conductivity spatial step length of the silk screen layer in the solder resist area, and dividing the estimated thickness of the silk screen layer in the solder resist area into a plurality of silk screen layer depth nodes according to the estimated thermal conductivity spatial step length of the silk screen layer in the solder resist area; the plurality of silk screen layer depth nodes are represented as i 3 =1,2,3...n 3 ;

[0121] The calculation formula for the estimated thermal conductivity space step length of the silk screen layer in the solder mask area is:

[0122] ;

[0123] In the formula, It indicates the estimated thermal conductivity space step length of the silk screen layer in the solder mask area, L3 indicates the estimated thickness of the silk screen layer, m 5 Indicates the total number of silkscreen layer depth nodes;

[0124] S44, obtaining the actual thickness of the solder resist layer, the thermal conductivity of the solder resist layer, the energy absorption rate of the solder resist layer, the thermal conductivity of the copper foil layer, and the estimated thickness of the copper foil layer of the corrected solder resist area information;

[0125] S45, obtaining an estimated thermal conductivity spatial step length of the solder resist layer and an estimated thermal conductivity spatial step length of the copper foil layer, and dividing the estimated thickness of the solder resist layer and the estimated thickness of the copper foil layer into a plurality of solder resist layer depth nodes and a plurality of copper foil layer depth nodes according to the estimated thermal conductivity spatial step length of the solder resist layer and the estimated thermal conductivity spatial step length of the copper foil layer;

[0126] S46, obtaining the internal temperature distribution information of the silk screen in the solder resist area under the estimated thickness of the silk screen layer in the solder resist area according to the power and duration of the preset heat source, the silk screen area of ​​the solder resist area, the estimated thickness of the silk screen layer in the solder resist area, the thermal conductivity of the silk screen layer, the energy absorption rate of the silk screen, the estimated thermal conductivity spatial step length of the silk screen layer in the solder resist area, the heated area of ​​the solder resist layer, the actual thickness of the solder resist layer, the thermal conductivity of the solder resist layer, the energy absorption rate of the solder resist layer, the thermal conductivity of the copper foil layer, the estimated thermal conductivity spatial step length of the solder resist layer, and the estimated thermal conductivity spatial step length of the copper foil layer;

[0127] The internal temperature distribution information of the silk screen in the solder resist area includes the temperature of each silk screen layer depth node, the temperature of each solder resist layer depth node and the temperature of each copper foil layer depth node in the area;

[0128] The temperature calculation formula for each silk screen layer depth node is:

[0129] ;

[0130] In the formula, Indicates the i 3 +1 temperature of the silk screen layer depth node at time j, Indicates the i 3 The temperature of the silk-screen layer depth node at time j, P represents the power of the preset heat source, t represents the duration of the preset heat source, G represents the energy absorption rate of the silk-screen layer, A represents the silk-screen area, k 3 Indicates the thermal conductivity of the silk-screen layer, Indicates the estimated thermal conductivity space step length of the silk screen layer in the solder mask area;

[0131] At the interface between the silk screen layer and the solder mask layer, the temperature and heat flux density are continuous, that is, the bottom surface temperature of the silk screen layer is equal to the top surface temperature of the solder mask layer. It is equal to the temperature of the upper surface of the solder mask at time j, so it can be calculated continuously;

[0132] The temperature of each silk screen layer depth node and the temperature of each copper foil layer depth node are calculated and obtained using the formula described in steps S11-S18;

[0133] S47, obtaining the silk screen layer density and the silk screen layer specific heat capacity of the silk screen material information;

[0134] S48, obtaining the solder mask layer density, solder mask layer specific heat capacity, copper foil layer density and copper foil layer specific heat capacity of the corrected solder mask area information;

[0135] S49, obtaining a preset heat conduction time step;

[0136] S410, obtaining an estimated value of the surface temperature of the solder resist area silk screen at the estimated thickness of the solder resist area silk screen after the preset heat source ends based on the internal temperature distribution information of the solder resist area silk screen, the silk screen layer density, the silk screen layer specific heat capacity, the solder resist layer density, the solder resist layer specific heat capacity, the copper foil layer density, the copper foil layer specific heat capacity, the preset thermal conductivity time step, the estimated thermal conductivity space step of the solder resist area silk screen layer, the estimated thermal conductivity space step of the solder resist layer, and the estimated thermal conductivity space step of the copper foil layer;

[0137] S411, judging whether the estimated value of the silk-screen surface temperature of the solder resist area is equal to the silk-screen surface temperature reaction value under the preset heat source; if not, correcting the estimated thickness of the silk-screen layer in the solder resist area in the silk-screen material information, specifically, correcting the estimated thickness of the silk-screen layer in the solder resist area by adjusting the estimated thermal conductivity space step of the silk-screen layer in the solder resist area, until the estimated value of the silk-screen surface temperature of the solder resist area is equal to the silk-screen surface temperature reaction value under the preset heat source; if equal, obtaining the actual thickness of the silk-screen layer in the solder resist area according to the estimated thickness of the silk-screen layer in the solder resist area, that is, the actual thickness of the silk-screen layer in the solder resist area is equal to the estimated thickness of the silk-screen layer in the solder resist area;

[0138] The estimated value of the screen printing surface temperature of the solder resist area is calculated based on the estimated temperature of the internal nodes of the screen printing area. The estimated temperature of the internal nodes of the screen printing area of ​​the solder resist area includes the estimated temperature of each screen printing layer depth node, the estimated temperature of each solder resist layer depth node and the estimated temperature of each copper foil layer depth node in the area.

[0139] The estimated temperature calculation formula for each silk screen layer depth node is:

[0140] ;

[0141] In the formula, Indicates the i 3 The temperature of the solder mask depth node at time j+1, Indicates the i 3 The temperature of the solder mask depth node at time j, Indicates the estimated thermal conductivity space step of the solder mask layer, k 3 Thermal conductivity of solder mask, ρ 3 is the solder mask density, c 3 is the specific heat capacity of the solder mask layer, Δt represents the preset time step of thermal conduction, Indicates the i 3 +1 solder mask layer depth node temperature at time j, Indicates the i 3 -1 Temperature of solder mask depth node at time j;

[0142] The estimated temperature of each solder resist layer depth node and the estimated temperature of each copper foil layer depth node are calculated and obtained using the formula described in steps S11-S18;

[0143] According to the above calculation method, an estimated value of the screen printing surface temperature of the solder resist area can be obtained;

[0144] S412, obtaining the silk-screen printing area of ​​the insulating region and the estimated thickness of the silk-screen printing layer in the insulating region from the silk-screen printing material information;

[0145] S413, obtaining insulation area information according to the substrate material information, the insulation area information including the estimated thickness of the insulation layer, the thermal conductivity of the insulation layer and the heating area of ​​the insulation layer; the heating area of ​​the insulation layer is equal to the screen printing area of ​​the insulation area;

[0146] S414, obtaining the estimated thermal conductivity space step length of the silk-screen layer in the insulation area;

[0147] S415, obtaining the estimated thermal conductivity space step length of the insulation layer of the insulation region material information;

[0148] S416, obtaining the internal temperature distribution information of the silk screen in the insulating area according to the power and duration of the preset heat source, the silk screen area of ​​the insulating area, the estimated thickness of the silk screen layer in the insulating area, the thermal conductivity of the silk screen layer, the silk screen energy absorption rate, the estimated thermal conductivity space step of the silk screen layer in the insulating area, the estimated thickness of the insulating layer, the thermal conductivity of the insulating layer, the heated area of ​​the insulating layer, and the estimated thermal conductivity space step of the insulating layer; the calculation formula refers to the temperature calculation formula of each silk screen layer depth node mentioned above;

[0149] S417, obtaining the insulation layer density and insulation layer specific heat capacity of the insulation region material information;

[0150] S418, obtaining an estimated value of the surface temperature of the silk-screen printing in the insulating area according to the internal temperature distribution information of the silk-screen printing in the insulating area, the density of the silk-screen printing layer, the specific heat capacity of the silk-screen printing layer, the density of the insulating layer, the specific heat capacity of the insulating layer, the preset thermal conductivity time step, the estimated thermal conductivity space step of the silk-screen printing layer in the insulating area, and the estimated thermal conductivity space step of the insulating layer; the calculation formula refers to the estimated temperature calculation formula of each silk-screen printing layer depth node mentioned above;

[0151] S419, determining whether the estimated value of the silk-screen surface temperature of the insulating region is equal to the silk-screen surface temperature reaction value under the preset heat source; if not, correcting the estimated thickness of the silk-screen layer in the insulating region information, specifically by adjusting the estimated thermal conductivity space step of the silk-screen layer in the insulating region to correct the estimated thickness of the silk-screen layer in the insulating region until the estimated value of the silk-screen surface temperature of the insulating region is equal to the silk-screen surface temperature reaction value under the preset heat source; if equal, obtaining the actual thickness of the silk-screen layer in the insulating region according to the estimated thickness of the silk-screen layer in the insulating region, that is, the actual thickness of the silk-screen layer in the insulating region is equal to the estimated thickness of the silk-screen layer in the insulating region;

[0152] S420, obtaining a silk screen thickness distribution value according to the actual thickness of the silk screen layer in the insulating area and the actual thickness of the silk screen layer in the solder resist area.

[0153] The silk screen surface temperature response value under the preset heat source is obtained by extracting the silk screen thermal imaging images at different times under the preset heat source. According to whether the distribution position of the silk screen on the circuit board is in the solder resist area or the insulating area, the silk screen thermal imaging image is divided into the silk screen thermal imaging image of the solder resist area and the silk screen thermal imaging image of the insulating area. The silk screen surface temperature response value includes the surface temperature value of the silk screen layer in the solder resist area and the surface temperature value of the silk screen layer in the insulating area. Therefore, the actual thickness of the silk screen layer in the solder resist area and the actual thickness of the silk screen layer in the insulating area actually include the thickness value of each silk screen pixel area in the silk screen thermal imaging image of the solder resist area and the silk screen thermal imaging image of the insulating area. The set of thickness values ​​of all silk screen pixel areas is the silk screen thickness distribution value.

[0154] The distribution value of silk screen thickness is the premise for evaluating the uniformity of silk screen thickness of circuit boards. Uneven silk screen thickness of circuit boards will lead to many negative effects. In some high-precision and high-density circuit boards, such as mobile phone motherboards, chip packaging substrates, etc., in order to achieve higher integration, silk screens with good thickness uniformity are more conducive to fine processing. Uneven silk screen thickness will make it difficult to arrange more components and circuits in a limited space. Silk screens with good thickness uniformity can ensure that the functions of each chip and circuit are accurately marked in a small space, and will not occupy too much space or interfere with the layout of other components due to too thick silk screen. In terms of appearance quality, uneven silk screen thickness will make the color and gloss of the circuit board surface inconsistent, with obvious color difference and unevenness, resulting in decreased clarity and readability of characters, bringing inconvenience to production, debugging and maintenance personnel, and increasing the risk of misjudgment and operational errors. At the same time, in some designs, the silk screen layer also has a protective effect on the circuit board. Uneven silk screen thickness will make the protective performance of the circuit board surface inconsistent, and the thinner area will be easily eroded by moisture, chemicals, etc., accelerating the aging and damage of the circuit board, reducing the service life and reliability of the product. In some application scenarios that require plugging, unplugging, bending or vibration, uneven silk screen thickness may cause thinner areas to be prone to cracks, peeling and other damage when subjected to external forces. Due to all the above problems, manufacturers may encounter higher rework and scrap rates, increasing production costs and reducing production line efficiency. This solution can better evaluate the silk screen quality by obtaining the silk screen thickness distribution value, prevent the above silk screen quality problems from affecting the circuit board, and in order to ensure the accuracy of the silk screen thickness detection results, consider that the heating energy of the preset heat source will penetrate the silk screen layer, Since the solder mask layer is thin, the heat will be conducted to the copper foil layer under the solder mask layer. Therefore, the heat dissipation effect of the solder mask layer and the copper foil layer on the silk screen layer is taken into consideration and calculated together to obtain a more accurate silk screen thickness distribution value. In order to achieve rapid detection, this solution only requires heat to be conducted from the silk screen layer to the solder mask layer and the copper foil layer or from the silk screen layer to the insulating layer. The heat of the preset heat source does not need to completely reach the other side of the circuit board before detection can be performed. That is, during the entire detection process, detection can be performed even when the heat distribution is in an unstable state, thereby achieving a faster detection speed.

[0155] The step of obtaining the reference value of the silk screen adhesion according to the silk screen surface flatness distribution value and the silk screen thickness distribution value comprises:

[0156] S51, obtaining the relative height value of each screen-printed pixel area and the average height value of all screen-printed pixel areas according to the flat distribution value of the screen-printed surface;

[0157] The step of obtaining the flatness distribution value of the silk screen surface according to the silk screen image information comprises:

[0158] According to the silk-screen image information under different preset angle light sources, the brightness value of each pixel point under different preset angle light sources is obtained, and the maximum brightness value is extracted;

[0159] Calculate the relative brightness value of each pixel compared with the maximum brightness value at each light source angle;

[0160] Get the relative height value conversion coefficient;

[0161] The relative height value of each screen-printed pixel area is obtained according to each relative brightness value and relative height value conversion coefficient, and the average of the relative height values ​​of all screen-printed pixel areas is the average height value of the screen-printed pixel area; the screen-printed surface will present different light and dark states under different preset angle light sources, the more concave the area, the lower the relative brightness value, and the more convex the area, the higher the relative brightness value, so the relative brightness value and the relative height value are proportional to each other, and the flatness distribution value of the screen-printed surface can be obtained through this relationship;

[0162] S52, obtaining the thickness value of each screen-printed pixel area and the average thickness value of all screen-printed pixel areas according to the screen-printed thickness distribution value; the screen-printed thickness distribution value is obtained based on the screen-printed temperature response value under the preset heat source, and the screen-printed temperature response value is obtained by extracting the screen-printed thermal imaging images at different times under the preset heat source, so the screen-printed thickness distribution value includes the thickness value of each screen-printed pixel area in the screen-printed thermal imaging image;

[0163] S53, obtaining an overall correlation value of the silk-screen thickness distribution value and the silk-screen surface flatness distribution value according to the relative height value of each silk-screen pixel area, the average height value of all silk-screen pixel areas, the thickness value of each silk-screen pixel area, and the average thickness value of all silk-screen pixel areas;

[0164] The overall correlation value is calculated based on a single correlation value between the relative height value and the thickness value of each screen printing pixel area, and the single correlation value calculation formula is:

[0165] ;

[0166] In the formula, i-th 9 A single correlation value for a screen-printed pixel area, Indicates the i 5 The relative height value of the screen printing pixel area, Indicates the average height value of all screen-printed pixel areas. Indicates the i 6 and the thickness value of the screen printing pixel area, Indicates the average thickness value of all screen-printed pixel areas;

[0167] The sum of the correlations between the height values ​​and thickness values ​​of all screen-printed pixel areas is the overall correlation value between the screen-printed thickness distribution value and the screen-printed surface flatness distribution value;

[0168] S54, obtaining a screen printing adhesion reference value according to the overall correlation value;

[0169] ;

[0170] In the formula, F represents the reference value of screen printing adhesion, Represents the overall correlation value, m 1 Represents the sum of all silk-screen pixel areas.

[0171] The size of the silk screen adhesion is related to the size of the connection surface between the silk screen layer and the substrate material. When the silk screen thickness distribution value is highly correlated with the silk screen surface flatness distribution value, it means that the uneven silk screen thickness is mainly due to the unevenness of the silk screen upper surface. When the silk screen thickness distribution value is less correlated with the silk screen surface flatness distribution value, it means that the uneven silk screen thickness is mainly due to the unevenness of the silk screen lower surface. According to the flatness of the silk screen lower surface, the size of the connection surface between the silk screen layer and the substrate material can be judged, and then the size of the silk screen adhesion can be judged.

[0172] The step of obtaining the uniformity value of the silk screen stress distribution according to the silk screen material information and the silk screen thickness distribution value comprises:

[0173] S61, obtaining the screen printing thermal shrinkage rate of the screen printing material information;

[0174] S62, obtaining the silk screen thickness value of each pixel area in the silk screen thermal imaging image information, and extracting the maximum silk screen thickness value;

[0175] S63, obtaining the stress value of each pixel area in the silk-screen thermal imaging image according to the thermosetting shrinkage rate, the silk-screen thickness value of each pixel area and the maximum silk-screen thickness value, and the calculation formula is:

[0176] ;

[0177] In the formula, It represents the silk screen stress value of the i11th pixel area in the silk screen thermal imaging image. Indicates the thickness value of the i12th pixel area in the screen printing thermal imaging image. It represents the maximum screen printing thickness value, and E represents the screen printing thermal shrinkage rate;

[0178] S64, obtaining a uniformity value of the silk-screen stress distribution according to the similarity between the silk-screen stress value of each pixel point area in the silk-screen thermal imaging image and its neighboring points.

[0179] According to the spatial statistical method, the similarity between the silk-screen stress value of each pixel area in the silk-screen thermal imaging image and its neighboring points is calculated, and the Moran's I or Geary's C index is used for calculation to determine the value of the index. When Moran's I is close to 0, it means that the data is evenly distributed. When it exceeds a certain preset value, it means that the data is not evenly distributed. Finally, the uniformity value of the silk-screen stress distribution is obtained.

[0180] When the silk-screen layer is solidified, the solidification time will be different due to its own different thickness. Different solidification times will produce different internal stresses. From the appearance: uneven internal stress will cause deformation of the silk-screen pattern, causing the printed pattern to stretch, twist or change in size, etc., and may change the gloss and surface flatness of the silk-screen ink layer, causing tiny wrinkles or deformation, which will affect the optical properties of the ink layer and reduce the appearance quality of the printed product; from the durability point of view: uneven internal stress may cause the bonding force between the silk-screen layer and the surface to be affected, and its internal structure is relatively loose, chemical substances can more easily penetrate into the ink layer, causing the ink to react with chemical reagents, and the shedding phenomenon will be more obvious. The present application evaluates the internal stress of the silk-screen layer based on the thickness, which can more accurately evaluate the silk-screen quality.

[0181] The step of obtaining the silk screen quality evaluation value according to the silk screen adhesion reference value, the silk screen thickness distribution value and the silk screen stress distribution uniformity value comprises:

[0182] S71, obtaining the quality influence weight of the screen printing adhesion reference value;

[0183] S72, obtaining the quality influence weight of the uniformity value of the screen printing stress distribution;

[0184] S73, obtain the screen printing thickness uniformity value according to the screen printing thickness distribution value, and the calculation formula is:

[0185] ;

[0186] In the formula, H represents the uniformity value of screen printing thickness, Indicates the i-th 14 The screen printing thickness value of the pixel area, Represents the average value of the silk screen thickness of all pixel areas in the silk screen thermal imaging image, m 2 Indicates the total number of all pixel areas in the silk-screen thermal imaging image;

[0187] The above formula can be used to calculate the difference in the silk screen thickness values ​​of all pixel areas in the silk screen thermal imaging image. The smaller the value of H, the smaller the difference and the more uniform the silk screen thickness distribution.

[0188] S74, obtaining the quality influence weight of the uniformity value of the screen printing thickness;

[0189] S75, obtaining a reference value of screen printing adhesion and a value of uniformity of screen printing stress distribution;

[0190] S76, obtaining a screen printing quality assessment value according to the quality influence weight of the screen printing adhesion reference value, the quality influence weight of the screen printing thickness uniformity value, the quality influence weight of the screen printing stress distribution uniformity value, the screen printing adhesion reference value, the screen printing thickness uniformity value and the screen printing stress distribution uniformity value, and the calculation formula is: ;

[0191] In the formula, Z represents the screen printing quality assessment value, F represents the screen printing adhesion reference value, ω1 represents the quality influence weight of the screen printing adhesion reference value, H represents the screen printing thickness uniformity value, ω2 represents the quality influence weight of the screen printing thickness uniformity value, Y represents the screen printing stress distribution uniformity value, and ω3 represents the quality influence weight of the screen printing stress distribution uniformity value.

[0192] The quality influence weight of the silk screen adhesion reference value, the quality influence weight of the silk screen thickness uniformity value and the quality influence weight of the silk screen stress distribution uniformity value will have different sizes in different usage environments. For example, in an environment where high temperature is the main circumstance, the quality influence weight of the silk screen stress distribution uniformity value should be relatively adjusted higher; in an environment where vibration is the main circumstance, the quality influence weight of the silk screen adhesion reference value should be relatively adjusted higher; in the case of high-precision electronic components installation, the quality influence weight of the silk screen thickness uniformity value should be relatively adjusted higher. By adjusting the weights, it can better adapt to actual needs.

[0193] like Figure 2 As shown, the present invention also provides a circuit board screen printing detection system, comprising:

[0194] The first acquisition module 1 is used to acquire the substrate material information of the circuit board and the substrate surface temperature reaction value under a preset heat source, and acquire the modified solder mask area information according to the substrate material information and the substrate surface temperature reaction value;

[0195] A second acquisition module 2, used to acquire the insulation area information according to the substrate material information;

[0196] The third acquisition module 3 is used to obtain the silk screen material information of the circuit board and the silk screen surface temperature response value under a preset heat source;

[0197] A fourth acquisition module 4 is used to obtain a silk screen thickness distribution value according to the corrected solder resist area information, the insulating area information, the silk screen material information and a surface temperature response value of the silk screen area under a preset heat source;

[0198] A fifth acquisition module 5 is used to acquire the silk screen image information under different preset angle light sources, and acquire the silk screen surface flatness distribution value according to the silk screen image information;

[0199] A sixth acquisition module 6, used to obtain a reference value of silk screen adhesion according to a silk screen surface flatness distribution value and a silk screen thickness distribution value;

[0200] A seventh acquisition module 7 is used to obtain a uniformity value of silk screen stress distribution according to silk screen material information and silk screen thickness distribution value;

[0201] The eighth acquisition module 8 is used to acquire the silk screen quality evaluation value according to the silk screen adhesion reference value, the silk screen thickness distribution value and the silk screen stress distribution uniformity value.

[0202] The fourth acquisition module 4 includes:

[0203] A first acquisition unit is used to acquire the power and duration of a preset heat source, silk screen material information and modified solder mask area information;

[0204] A second acquisition unit is used to acquire the internal temperature distribution information of the silk screen in the solder resist area according to the power and duration of the preset heat source, the silk screen material information and the corrected solder resist area information;

[0205] Used to obtain an estimated value of the screen printing surface temperature of the solder resist area under a preset heat source according to the screen printing internal temperature distribution information of the solder resist area, the screen printing material information and the corrected solder resist area information;

[0206] A first value comparison and correction unit is used to determine whether the estimated value of the screen printing surface temperature of the solder resist area is equal to the screen printing surface temperature response value under the preset heat source, and correct the estimated thickness of the screen printing layer in the solder resist area in the screen printing material information to the actual thickness of the screen printing layer in the solder resist area according to the determination result;

[0207] A third acquisition unit, used for acquiring insulation area information;

[0208] A fourth acquisition unit, configured to acquire the internal temperature distribution information of the silk screen in the insulating area according to the power and duration of the preset heat source, the silk screen material information and the insulating area information;

[0209] Used to obtain an estimated value of the screen printing surface temperature of the insulating area according to the internal temperature distribution information of the screen printing area of ​​the insulating area, the screen printing material information and the insulating area information;

[0210] A second value comparison and correction unit is used to determine whether the estimated value of the screen printing surface temperature of the insulating area is equal to the screen printing surface temperature response value under a preset heat source, and correct the estimated thickness of the screen printing layer in the insulating area information to the actual thickness of the screen printing layer in the insulating area according to the determination result;

[0211] The fifth acquisition unit is used to acquire a silk screen thickness distribution value according to the actual thickness of the silk screen layer in the insulating area and the actual thickness of the silk screen layer in the solder resist area.

[0212] The present invention also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above-mentioned circuit board silk screen detection method when executing the computer program.

[0213] The present invention also provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of the above-mentioned circuit board silk screen detection method are implemented.

[0214] Those of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media provided in this application and used in the embodiments may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (SSRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0215] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, device, article or method including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, device, article or method. In the absence of further restrictions, an element defined by the sentence "includes a ..." does not exclude the presence of other identical elements in the process, device, article or method including the element.

[0216] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A circuit board screen printing detection method, characterized in that: include: Obtaining substrate material information of the circuit board and a substrate surface temperature reaction value under a preset heat source, and obtaining corrected solder resist area information according to the substrate material information and the substrate surface temperature reaction value, wherein the corrected solder resist area information includes an actual thickness of the solder resist layer; Acquire insulation area information according to the substrate material information; Get the silk screen material information of the circuit board and the silk screen surface temperature response value under the preset heat source; Acquire a screen printing thickness distribution value according to the corrected solder resist area information, the insulating area information, the screen printing material information and a screen printing area surface temperature response value under a preset heat source; Acquire silk screen image information under different preset angle light sources, acquire silk screen surface flatness distribution values ​​according to the silk screen image information, and acquire silk screen adhesion reference values ​​according to the silk screen surface flatness distribution values ​​and silk screen thickness distribution values; Obtain the uniformity value of silk screen stress distribution according to silk screen material information and silk screen thickness distribution value; The silk screen quality evaluation value is obtained according to the silk screen adhesion reference value, silk screen thickness distribution value and silk screen stress distribution uniformity value.

2. The circuit board screen printing detection method according to claim 1, characterized in that: The step of obtaining the corrected solder mask area information according to the substrate material information and the substrate surface temperature response value under the preset heat source comprises: Get the power and duration of the preset heat source; Obtain solder mask area information according to substrate material information; Acquire the temperature distribution information inside the solder resist area according to the power and duration of the preset heat source and the solder resist area information; Acquire an estimated value of the surface temperature of the solder resist area under a preset heat source according to the internal temperature distribution information of the solder resist area and the material information of the solder resist area; Determine whether the estimated value of the surface temperature of the solder resist area is equal to the surface temperature reaction value of the substrate under a preset heat source; if not, correct the estimated thickness of the solder resist layer in the solder resist area information until the estimated value of the surface temperature of the solder resist area is equal to the surface temperature reaction value of the substrate under a preset heat source; if equal, correct the estimated thickness of the solder resist layer in the solder resist area material information to the actual thickness of the solder resist layer to obtain the corrected solder resist area information.

3. The circuit board screen printing detection method according to claim 2, characterized in that: The step of obtaining the screen printing thickness distribution value according to the corrected solder mask area information, the insulating area information, the screen printing material information and the screen printing area surface temperature response value under the preset heat source comprises: Get the power and duration of the preset heat source; Get silk screen material information; Get the corrected solder mask area information; Acquire the silk screen internal temperature distribution information of the solder resist area according to the power and duration of the preset heat source, the silk screen material information and the corrected solder resist area information; Obtain an estimated value of the screen printing surface temperature of the solder resist area under a preset heat source according to the screen printing internal temperature distribution information of the solder resist area, the screen printing material information and the corrected solder resist area information; Determine whether the estimated value of the screen printing surface temperature of the solder resist area is equal to the screen printing surface temperature reaction value under the preset heat source; if not, correct the estimated thickness of the screen printing layer in the solder resist area in the screen printing material information until the estimated value of the screen printing surface temperature of the solder resist area is equal to the screen printing surface temperature reaction value under the preset heat source; if equal, obtain the actual thickness of the screen printing layer in the solder resist area according to the estimated thickness of the screen printing layer in the screen printing material information; Get insulation area information; Acquire the internal temperature distribution information of the silk screen in the insulating area according to the power and duration of the preset heat source, the silk screen material information and the insulating area information; Acquire an estimated value of the screen printing surface temperature of the insulating area according to the internal temperature distribution information of the screen printing area of ​​the insulating area, the screen printing material information and the insulating area information; Determine whether the estimated value of the silk-screen surface temperature of the insulating area is equal to the silk-screen surface temperature response value under a preset heat source; if not, correct the estimated thickness of the silk-screen layer in the insulating area information until the estimated value of the silk-screen surface temperature of the insulating area is equal to the silk-screen surface temperature response value under a preset heat source; if equal, obtain the actual thickness of the silk-screen layer in the insulating area according to the estimated thickness of the silk-screen layer in the insulating area information; The silk screen thickness distribution value is obtained according to the actual thickness of the silk screen layer in the insulating area and the actual thickness of the silk screen layer in the solder resist area.

4. The circuit board screen printing detection method according to claim 3, characterized in that: The step of obtaining the reference value of the silk screen adhesion according to the silk screen surface flatness distribution value and the silk screen thickness distribution value comprises: According to the flat distribution value of the silk-screen surface, the relative height value of each silk-screen pixel area and the average height value of all silk-screen pixel areas are obtained; According to the silk screen thickness distribution value, the thickness value of each silk screen pixel area and the average thickness value of all silk screen pixel areas are obtained; Obtain an overall correlation value of the silk-screen thickness distribution value and the silk-screen surface flatness distribution value according to the relative height value of each silk-screen pixel area, the average height value of all silk-screen pixel areas, the thickness value of each silk-screen pixel area, and the average thickness value of all silk-screen pixel areas; A silk screen adhesion reference value is obtained according to the overall correlation value.

5. The circuit board screen printing detection method according to claim 4, characterized in that: The step of obtaining the uniformity value of the silk screen stress distribution according to the silk screen material information and the silk screen thickness distribution value comprises: Get the screen printing material information of the screen printing thermal shrinkage rate; Obtain the silk screen thickness value of each pixel area in the silk screen thermal imaging image information, and extract the maximum silk screen thickness value; Acquire the stress value of each pixel area in the silk-screen thermal imaging image according to the thermosetting shrinkage rate, the silk-screen thickness value of each pixel area and the maximum silk-screen thickness value; The uniformity value of silk-screen stress distribution is obtained according to the similarity between the silk-screen stress value of each pixel area in the silk-screen thermal imaging image and its adjacent points.

6. The circuit board screen printing detection method according to claim 5, characterized in that: The step of obtaining the silk screen quality evaluation value according to the silk screen adhesion reference value, the silk screen thickness distribution value and the silk screen stress distribution uniformity value comprises: Get the quality influence weight of the screen printing adhesion reference value; Get the quality influence weight of the uniformity value of screen printing stress distribution; Get the screen printing thickness uniformity value according to the screen printing thickness distribution value; Get the quality influence weight of the uniformity value of screen printing thickness; Get the reference value of screen printing adhesion and the uniformity value of screen printing stress distribution; The silk screen quality evaluation value is obtained according to the quality influence weight of the silk screen adhesion reference value, the quality influence weight of the silk screen thickness uniformity value, the quality influence weight of the silk screen stress distribution uniformity value, the silk screen adhesion reference value, the silk screen thickness uniformity value and the silk screen stress distribution uniformity value, and the calculation formula is: ； In the formula, Z represents the screen printing quality assessment value, F represents the screen printing adhesion reference value, ω1 represents the quality influence weight of the screen printing adhesion reference value, H represents the screen printing thickness uniformity value, ω2 represents the quality influence weight of the screen printing thickness uniformity value, Y represents the screen printing stress distribution uniformity value, and ω3 represents the quality influence weight of the screen printing stress distribution uniformity value.

7. A circuit board screen printing detection system, characterized in that: include: A first acquisition module is used to acquire substrate material information of the circuit board and a substrate surface temperature reaction value under a preset heat source, and acquire corrected solder resist area information according to the substrate material information and the substrate surface temperature reaction value, wherein the corrected solder resist area information includes an actual thickness of the solder resist layer; A second acquisition module, used to acquire the insulation area information according to the substrate material information; The third acquisition module is used to obtain the silk screen material information of the circuit board and the silk screen surface temperature response value under a preset heat source; A fourth acquisition module, used for acquiring a silk screen thickness distribution value according to the corrected solder resist area information, the insulating area information, the silk screen material information and a surface temperature response value of the silk screen area under a preset heat source; A fifth acquisition module is used to acquire the silk screen image information under different preset angle light sources, and acquire the silk screen surface flatness distribution value according to the silk screen image information; A sixth acquisition module, used to obtain a reference value of silk screen adhesion according to a silk screen surface flatness distribution value and a silk screen thickness distribution value; A seventh acquisition module is used to obtain a uniformity value of silk screen stress distribution according to silk screen material information and silk screen thickness distribution value; The eighth acquisition module is used to obtain the silk screen quality evaluation value according to the silk screen adhesion reference value, the silk screen thickness distribution value and the silk screen stress distribution uniformity value.

8. A circuit board screen printing detection system according to claim 7, characterized in that: The fourth acquisition module includes: A first acquisition unit is used to acquire the power and duration of a preset heat source, silk screen material information and modified solder mask area information; A second acquisition unit is used to acquire the internal temperature distribution information of the silk screen in the solder resist area according to the power and duration of the preset heat source, the silk screen material information and the corrected solder resist area information; Used to obtain an estimated value of the screen printing surface temperature of the solder resist area under a preset heat source according to the screen printing internal temperature distribution information of the solder resist area, the screen printing material information and the corrected solder resist area information; A first value comparison and correction unit is used to determine whether the estimated value of the screen printing surface temperature of the solder resist area is equal to the screen printing surface temperature response value under the preset heat source, and correct the estimated thickness of the screen printing layer in the solder resist area in the screen printing material information to the actual thickness of the screen printing layer in the solder resist area according to the determination result; A third acquisition unit, used for acquiring insulation area information; A fourth acquisition unit, configured to acquire the internal temperature distribution information of the silk screen in the insulating area according to the power and duration of the preset heat source, the silk screen material information and the insulating area information; Used to obtain an estimated value of the screen printing surface temperature of the insulating area according to the internal temperature distribution information of the screen printing area of ​​the insulating area, the screen printing material information and the insulating area information; A second value comparison and correction unit is used to determine whether the estimated value of the screen printing surface temperature of the insulating area is equal to the screen printing surface temperature response value under a preset heat source, and correct the estimated thickness of the screen printing layer in the insulating area information to the actual thickness of the screen printing layer in the insulating area according to the determination result; The fifth acquisition unit is used to acquire a silk screen thickness distribution value according to the actual thickness of the silk screen layer in the insulating area and the actual thickness of the silk screen layer in the solder resist area.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 6 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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