CN115544936A

CN115544936A - Method and device for determining plate brazing temperature field distribution and computer readable storage medium

Info

Publication number: CN115544936A
Application number: CN202210225694.3A
Authority: CN
Inventors: 郭健强; 刘曰利; 李俊
Original assignee: Shenzhen Glory Intelligent Machine Co ltd
Current assignee: Shenzhen Glory Intelligent Machine Co ltd
Priority date: 2022-03-07
Filing date: 2022-03-07
Publication date: 2022-12-30

Abstract

The present application relates to the field of laser brazing technology, and in particular, to a method and an apparatus for determining distribution of a plate brazing temperature field, and a computer-readable storage medium. The method is used for solving the problems that in the related technology, a large number of groping experiments are needed to obtain the proper laser brazing temperature and time, and the laser brazing temperature and time are not easy to study. A method of determining a temperature field distribution for brazing a sheet, comprising: constructing a plate brazing structure model; according to the parts of the plate brazing structure model corresponding to all the components, relevant physical parameters and specified heat conduction boundary conditions in the laser brazing process, calculating the temperature of each welding point in the specified plate brazing structure corresponding to the specified brazing time in the laser brazing process of the plate brazing structure model, and obtaining the plate brazing temperature field distribution condition of the plate brazing structure model under the specified target temperature, the specified brazing time and the specified heat conduction boundary conditions. The method and the device are used for carrying out data simulation on the distribution of the plate brazing temperature field.

Description

Method and device for determining plate brazing temperature field distribution and computer readable storage medium

Technical Field

The present application relates to the field of laser brazing technology, and in particular, to a method and an apparatus for determining distribution of a plate brazing temperature field, and a computer-readable storage medium.

Background

With the precision and miniaturization of electronic components, the packaging density of the circuit board is higher and higher, and the size of a welding spot is smaller and smaller. Based on this, laser soldering is widely used in the assembly of electronic components and circuit boards because of its advantages of small heat affected zone, local and non-contact heating, rapid heating and rapid cooling, etc.

The temperature and time of laser brazing are critical to the brazing performance of the sheet. In the laser soldering process, if the soldering temperature is too low, the solder is difficult to melt, atomic diffusion and alloying reaction between the solder and the (copper) pad are slow, and if the soldering temperature is too high, thermal breakdown of a substrate of a circuit board can be caused, and even electronic components on a non-soldering area around a soldering point can be burnt. If the laser brazing time is too short, the brazing filler metal is difficult to permeate, and the excessively long brazing time has no great practical significance.

In the related art, the appropriate laser brazing temperature and time need to be obtained through a large number of groping experiments, which is not beneficial to the study of the laser brazing temperature and time.

Disclosure of Invention

The embodiment of the application provides a method and a device for determining plate brazing temperature field distribution and a computer readable storage medium, which are used for solving the problems that in the related art, a large number of groping experiments are needed to obtain proper laser brazing temperature and time, and the laser brazing temperature and time are not beneficial to being researched.

In order to achieve the above purpose, the embodiment of the present application adopts the following technical solutions:

in a first aspect, a method for determining a plate brazing temperature field distribution is provided, the method comprising S10-S20:

and S10, constructing a plate brazing structure model. The plate brazing structure model is a three-dimensional structure model specifying a plate brazing structure. The designated board soldering structure comprises a circuit board, an electronic component arranged on the circuit board, and a solder arranged between the circuit board and the electronic component.

The circuit board may include a plurality of copper pads, the electronic component may include a plurality of pins, and the solder may be disposed between the pins of the electronic component and the copper pads of the circuit board. The electronic components and the circuit board are welded in a soldering process through pins, copper welding pads and solder.

An example of the Circuit Board may be a Printed Circuit Board (PCB), and an example of the electronic component may be a Flexible Printed Circuit Board (FPC). The circuit board can also comprise a first substrate, a copper foil and a solder mask layer, wherein the copper foil and the solder mask layer are arranged on the surface of the first substrate, the solder mask layer covers the copper foil, and the copper pad is formed by the part of the solder mask layer, which is exposed out of the copper foil. The electronic component can further comprise a second substrate, a copper foil and a solder mask layer, wherein the copper foil and the solder mask layer are arranged on the surface of the second substrate, a through hole is formed in the second substrate, and the part, located on the inner wall of the through hole, of the copper foil and the part, located on the upper surface and the lower surface of the second substrate, of the copper foil form the pin. Before welding, the solder can be arranged on the copper pad and corresponding to the position of the through hole, and during welding, the solder is melted, overflows through the through hole and is welded with the copper pad and the pin.

Specifically, the building plate brazing structure model in S10 includes S101 to S102:

s101, constructing a plane layout of a specified plate soldering structure in specified drawing software based on user operation.

For example, a user may draw, in the drawing software, geometric objects corresponding to the structures of the components in the specified board soldering structure according to the structures of the components in the specified board soldering structure, and set the positions of the geometric objects corresponding to the components according to the positions and the connection relationships between the components, so as to obtain a planar layout of the specified board soldering structure.

By way of example, the designated drawing software may be Proe software, CAdent software, or the like.

Specifically, taking the specified drawing software as the Proe software as an example, the geometric objects corresponding to the first base, the copper foil, the solder resist layer included in the circuit board, and the second base, the copper foil, the solder resist layer, the solder, etc. included in the electronic component may be drawn in the Proe software, and the positions and angles of the geometric objects corresponding to the respective component parts may be adjusted according to the positional relationship of the respective component parts, so that the positional relationship between the geometric objects corresponding to the respective component parts corresponds to the actual positional relationship of the respective component parts.

Specifically, taking the mutual contact among the copper pads, the solder and the pins as an example, the geometric bodies corresponding to the copper pads, the solder and the pins are tightly combined and embodied in the board soldering structural model, the edge of the geometric body corresponding to the copper pad and the edge of the geometric body corresponding to the solder are overlapped, and the edge of the geometric body corresponding to the solder and the edge of the geometric body corresponding to the pins are overlapped.

The geometric body corresponding to each component of the above specified plate brazing structure is not particularly limited, and the corresponding geometric body may be constructed for each component according to whether the materials are the same or not.

For example, taking the circuit board as a PCB and the electronic component as an FPC as an example, the first substrate may be a single-layer structure or a multi-layer structure, and in the case that the first substrate is a single-layer structure, the material of the first substrate may be a resin material or a composite material of glass fiber and resin, and at this time, the first substrate may be used as a whole to construct a corresponding geometric body, for example, the geometric body corresponding to the first substrate is a cube. In the case that the first substrate is a multi-layer structure, the material of each layer structure in the first substrate may be a resin material, or a composite material of glass fiber and resin, and in this case, a single layer or multiple layers of copper foil may be disposed between two adjacent layers of structures to implement the wiring of the circuit board, in this case, each layer structure in the first substrate as a whole constructs a corresponding geometric body, for example, a copper foil layer as a whole constructs a corresponding geometric body (for example, a cube), and a structural layer of the resin material as a whole constructs a corresponding geometric body (for example, a cube). The second substrate may be made of a flexible material, such as Polyimide (PI), and in this case, the geometry corresponding to the second substrate may also be a cube.

In addition, the geometric body of the solder corresponding to the plate soldering structure model can also be a cube, and in the soldering process, the solder is melted and overflows from the through hole, so that the finally obtained solder is in an I-shaped structure.

In some embodiments, the first substrate may have a size of 27.5mm × 6.5mm × 0.7mm, the copper foil may have a size of 0.7mm × 0.7mm × 0.1mm, the solder may have a size of 0.7mm × 0.7mm × 0.09mm, the through hole may have a size of R0.025 mm × 0.065mm (R denotes a radius of the through hole and 0.065 denotes a height of the through hole), the copper foil positioned in the through hole may have a size of R0.035 mm × 0.065mm (R may be equal to an outer radius of the circular ring minus an inner radius of the circular ring), the second substrate may have a size of 0.7mm × 0.47mm × 0.02mm, and the copper foils on upper and lower surfaces of the second substrate may have a size of 0.7mm × 0.47mm × 0.02mm.

And S102, carrying out three-dimensional modeling on the plane layout to obtain a plate brazing structure model.

Specifically, the plane layout can be imported into three-dimensional modeling software, and the three-dimensional modeling software is used for carrying out three-dimensional modeling on the plane layout, so that the plate brazing structure model can be obtained.

For example, taking the plane layout of the specified board brazing structure drawn in the pro software as an example, the drawn plane layout may be imported into Hypermesh software for three-dimensional modeling, so as to obtain a board brazing structure model.

Of course, the planar layout of the specified board brazing structure can also be directly drawn in the COMSOL software, and the COMSOL software is utilized to perform three-dimensional modeling on the drawn planar layout to obtain a board brazing structure model.

S20, performing laser brazing simulation on the plate brazing structure model to determine the plate brazing temperature field distribution condition of the plate brazing structure model under the conditions of the specified target temperature, the specified brazing time and the specified heat conduction boundary, so as to determine the plate brazing temperature field distribution condition of the specified plate brazing structure under the conditions of the specified target temperature, the specified brazing time and the specified heat conduction boundary.

Compared with the temperature and time required for obtaining the proper laser brazing through a large number of groping experiments in the related art, the method does not need a large number of groping experiments, and can research the temperature and time of the laser brazing in a numerical simulation mode, thereby saving manpower, reducing cost and providing a theoretical basis for accurately controlling the temperature and time of the laser brazing.

In one implementation manner of the first aspect, the performing laser brazing simulation on the plate brazing structure model to determine the plate brazing temperature field distribution of the plate brazing structure model under the conditions of the specified target temperature, the specified brazing time and the specified thermal conduction boundary in S20 includes S201 to S205:

s201, performing laser heating simulation on the plate brazing structure model by using a specified heat source model so as to simulate a laser brazing process of the specified plate brazing structure, wherein in the laser brazing process, the target heating temperature of each welding spot in the specified plate brazing structure is the specified target temperature.

In one implementation of the first aspect, the heat source model is specified as a gaussian surface heat source model.

If the surface temperature of a circle is the same, the heat source model of the circle is equivalent to the temperature of a circle with a large diameter, and the Gaussian heat source model is qualitatively understood as that: the temperature is in the circle range of equal diameter, the center is higher and the outer edge is lower. The quantitative understanding is: in the circle range with the same diameter, the temperature is distributed according to a Gaussian curve, and the Gaussian distribution is normal distribution. The Gaussian face heat source model is adopted to perform laser heating simulation on the plate brazing structure model, and the laser brazing process can be accurately simulated.

The gaussian surface heat source model can be stored in finite element software (such as COMSOL software), and can be directly called and obtained under an operation instruction of a user when in use.

In one implementation manner of the first aspect, S201 performs laser heating simulation on the plate brazing structure model by using a specified heat source model to simulate a laser brazing process of a specified plate brazing structure, including:

the method comprises the steps of obtaining power densities of heat source items in a first time period and a second time period which are sequential and continuous, increasing the power densities of the heat source items from 0 to a preset threshold value in the first time period so that the temperature of each welding point in a corresponding appointed plate soldering structure in a plate soldering structure model is increased to an appointed target temperature, and adjusting the power densities of the heat source items to be smaller than the preset threshold value in the second time period so that the temperature of each welding point in the corresponding appointed plate soldering structure in the plate soldering structure model is stabilized at the appointed target temperature.

In an example, taking the circuit board as a PCB and the electronic component as an FPC as an example, in the first time period, the temperature of the solder joint may be increased to the specified target temperature by a higher power density, and in the second time period, the power density may be adjusted to be lower, so that the temperature of the solder joint is substantially stabilized at the specified target temperature. In the process, the first time period is a heating process, and the second time period is a constant temperature process, so that the temperature of the welding spot can be effectively controlled to be stabilized at a specified target temperature.

In some examples, the preset threshold may be 1.1 × 10 ⁶ W/m ³ ～1.9×10 ⁶ W/m ³ Any value of (1).

In some examples, the first time period may be a time period of 0s to 5s, and the second time period may be a time period of 5s to (60 to 90) s. That is, the second period may be a period of 5s to 60s, a period of 5s to 65s, a period of 5s to 70s, a period of 5s to 75s, a period of 5s to 80s, a period of 5s to 85s, or a period of 5s to 90 s.

In some examples, the second time period includes a first sub-time period and a second sub-time period in succession, and the power density of the heat source term is maintained at 5.0 × 10 during the first sub-time period ⁵ W/m ³ ～15.0×10 ⁵ W/m ³ In the second sub-period, the power density of the heat source term is changed from 5.0 × 10 ⁵ W/m ³ ～15.0×10 ⁵ W/m ³ Reduced to 2.4 × 10 ⁵ W/m ³ ～4.22×10 ⁵ W/m ³ To maintain a specified target temperature.

Wherein, in the second sub-period, the power density of the heat source item is controlled to be 5.0 × 10 ⁵ W/m ³ ～15.0×10 ⁵ W/m ³ Reduced to 2.4 × 10 ⁵ W/m ³ ～4.22×10 ⁵ W/m ³ Means heatThe power density of the source term may be from 5.0 × 10 ⁵ W/m ³ ～15.0×10 ⁵ W/m ³ Any value in the range is reduced to 2.4 × 10 ⁵ W/m ³ ～4.22×10 ⁵ W/m ³ Any value within the range. For example, the power density of the heat source term may be 5.0 × 10 ⁵ W/m ³ Reduced to 2.4 × 10 ⁵ W/m ³ Can be made of 10.0 × 10 ⁵ W/m ³ Reduced to 3.0 × 10 ⁵ W/m ³ And can be made of 15.0 × 10 ⁵ W/m ³ Reduced to 4.22 × 10 ⁵ W/m ³ Alternatively, it may be made of 15.0 × 10 ⁵ W/m ³ Reduced to 2.4 × 10 ⁵ W/m ³ 。

By acquiring the power density of the heat source item in the first sub-period as a certain value smaller than the preset threshold, the temperature rise process can be slowed down, the temperature of each welding point X in the brazing structure of the specified plate can be gradually stabilized at the specified target temperature, and by acquiring the power density of the heat source item in the second sub-period as the power density changing with time, the specified target temperature can be accurately maintained in the second sub-period.

In some examples, the first sub-period may be a period of 5s to (10-50) s, and the second sub-period may be a period of (10-50) s to (60-90) s.

Wherein, the first sub-period of time can be a period of time from 5s to 10s, a period of time from 5s to 15s, a period of time from 5s to 20s, a period of time from 5s to 25s, a period of time from 5s to 30s, a period of time from 5s to 35s, a period of time from 5s to 40s, a period of time from 5s to 45s, or a period of time from 5s to 50 s. When the first sub-period is a period of 5s to 10s, the second sub-period is a period of 10s to (60 to 90) s, when the first sub-period is a period of 5s to 15s, the second sub-period is a period of 15s to (60 to 90) s, when the first sub-period is a period of 5s to 20s, the second sub-period is a period of 20s to (60 to 90) s, when the first sub-period is a period of 5s to 25s, the second sub-period is a period of 25s to (60 to 90) s, when the first sub-period is a period of 5s to 30s, the second sub-period is a period of 30s to (60 to 90) s, when the first sub-period is a period of 5s to 35s, the second sub-period is a period of 35s to (60 to 90) s, the second sub-period is a period of 40s to (60 to 90) s when the first sub-period is a period of 5s to 40s, the second sub-period is a period of 45s to (60 to 90) s when the first sub-period is a period of 5s to 45s, the second sub-period is a period of 50s to (60 to 90) s when the first sub-period is a period of 5s to 50s, and the second sub-period may be a period of 10s to 60s, a period of 10s to 65s, a period of 10s to 70s, a period of 10s to 75s, a period of 10s to 80s, a period of 10s to 85s, or a period of 10s to 90s when the second sub-period is a period of 10s to (60 to 90) s; by analogy, when the second sub-period is a period of 50s to (60 to 90) s, the second sub-period may be a period of 50s to 60s, a period of 50s to 65s, a period of 50s to 70s, a period of 50s to 75s, a period of 50s to 80s, a period of 50s to 85s, or a period of 50s to 90 s.

S204, according to the parts, corresponding to all the components, in the plate brazing structure model, in the laser brazing process, relevant physical parameters and specified heat conduction boundary conditions are calculated, the temperature of each welding point, corresponding to the specified plate brazing structure, of the plate brazing structure model in the laser brazing process is calculated in the specified brazing time, and the plate brazing temperature field distribution conditions of the plate brazing structure model under the specified target temperature, the specified brazing time and the specified heat conduction boundary conditions are obtained; wherein the relevant physical parameters include: material, gauge, atmospheric heat capacity, density, and thermal conductivity, the specified thermal conduction boundary condition being indicative of the thermal conductivity of the specified sheet braze structure conducting to the environment during the laser brazing process.

For example, in finite element software (such as COMSOL software), the temperature of each welding point in the plate brazing structure corresponding to the designated plate brazing structure at the designated brazing time in the laser brazing process of the plate brazing structure model can be calculated according to the relevant physical parameters and the designated heat conduction boundary conditions of the part corresponding to each component part in the plate brazing structure model in the laser brazing process, so as to obtain the plate brazing temperature field distribution of the plate brazing structure model at the designated target temperature, the designated brazing time and the designated heat conduction boundary conditions.

In one implementation manner of the first aspect, the S204, according to the relevant physical parameters and the specified heat conduction boundary conditions of the parts corresponding to the components in the plate brazing structure model in the laser brazing process, calculates the temperature of each welding point in the plate brazing structure corresponding to the specified plate brazing structure at the specified brazing time in the laser brazing process of the plate brazing structure model, and obtains the plate brazing temperature field distribution of the plate brazing structure model at the specified target temperature, the specified brazing time and the specified heat conduction boundary conditions, and includes:

and carrying out meshing on the plate brazing structure model, and calculating the temperature of the position corresponding to each mesh after meshing in the appointed brazing time.

The meshing is to divide the model into a plurality of small units as the important part of the finite element analysis pretreatment, and the matching degree of the meshing and the calculation target and the quality of the mesh determine the quality of the finite element calculation in the later period.

The number of grids affects the accuracy of the calculation result and the size of the calculation scale. Generally, the number of grids is increased, the calculation accuracy is improved, but the calculation scale is also increased, so that the number of grids is determined by balancing two factors.

In practical application, a user can select a proper mesh division mode according to the plate brazing structure model and the related data type in the specified heating model.

In an implementation form of the first aspect, the meshing manner is a free tetrahedral meshing manner.

In the embodiments, the mesh division is simple, the retention of the detail characteristics of the model is convenient, and the calculation cost is low under the condition of the same mesh number.

And calculating the temperature of the corresponding position of each grid after grid division in the appointed brazing time.

When the temperature of the position corresponding to each grid after grid division in the specified brazing time is calculated, the temperature of the position corresponding to each grid after grid division in the specified brazing time can be calculated by setting the total calculation time to be 60-90 s and the step length to be 1 s. That is, in these embodiments, one step is calculated once every 1s, and in the case where the total calculation time length is set to 90s, it means that 90 times are calculated in total.

The specified brazing time may be any time point in the total time length, such as any time point in 20s, 22s, 30s, 40s, 42s, 50s, 60s, 90s and the like.

In one implementation form of the first aspect, the plate brazing temperature field distribution determining method further includes: s205, generating a plate brazing temperature field distribution diagram of the plate brazing structure model under the conditions of the specified target temperature, the specified brazing time and the specified heat conduction boundary according to the plate brazing temperature field distribution of the plate brazing structure model under the conditions of the specified target temperature, the specified brazing time and the specified heat conduction boundary. In the plate brazing temperature field pattern, the filling color and/or pattern of the plate brazing structure model in the grids corresponding to different temperatures are different. The data of the plate brazing temperature field distribution conditions of the determined plate brazing structure model under the conditions of the specified target temperature, the specified brazing time and the specified heat conduction boundary can be processed through finite element software, the plate brazing temperature field distribution pattern of the plate brazing structure model under the conditions of the specified target temperature, the specified brazing time and the specified heat conduction boundary is obtained, the plate brazing temperature field distribution pattern of the specified plate brazing structure under the conditions of the specified target temperature, the specified brazing time and the specified heat conduction boundary is obtained, and the temperature distribution patterns of all welding spots in the specified plate brazing structure under the conditions of the specified target temperature, the specified brazing time and the specified heat conduction boundary can be obtained through the position corresponding relation of all welding spots in the specified plate brazing structure and grids.

In one implementation manner of the first aspect, in S204, before calculating, during the laser brazing process, the temperature of each welding spot in the corresponding specified plate brazing structure at the specified brazing time in the plate brazing structure on the basis of the relevant physical parameters and the specified heat conduction boundary conditions of the portion, corresponding to each component, of the plate brazing structure model during the laser brazing process, the method for determining the distribution of the plate brazing temperature field further includes: acquiring relevant physical parameters and specifying thermal conduction boundary conditions.

Wherein the relevant physical parameter and the specified thermal conduction boundary condition are both obtainable by user input.

Specifically, when the relevant physical parameters are obtained, the circuit board is taken as a PCB, the electronic component is an FPC, the circuit board includes a first substrate, and a copper foil and a solder resist layer which are arranged on the first substrate, the electronic component includes a second substrate, and the copper foil and the solder resist layer which are arranged on the second substrate are taken as examples, parts corresponding to the components in the board soldering structure model respectively correspond to corresponding geometric bodies, and the relevant physical parameters of the parts corresponding to the components in the board soldering structure model in the laser soldering process can be obtained by assigning the material, specification, normal pressure heat capacity, density and heat conductivity coefficient of each geometric body in the board soldering structure model.

In actual operation, the materials, specifications, normal pressure heat capacity, density, heat conductivity coefficient and the like of each component part can be assigned in the determined finite element software according to user operation.

Specifically, taking finite element software as COMSOL software as an example, the COMSOL software can store corresponding relations between geometric bodies corresponding to each component and parameters such as corresponding materials, specifications, normal pressure heat capacity (also called specific heat capacity), density and heat conductivity (also called heat conductivity), therefore, by clicking the corresponding geometric bodies by users, parameters such as materials, specifications, normal pressure heat capacity, density and heat conductivity corresponding to the corresponding geometric bodies can be obtained, so as to complete the assignment.

In the case where each component part is of a cubic structure except for copper foils located on inner walls of through holes, specifications of each component part include length, width, and high and so on parameters, and for example, the first substrate, the second substrate, the copper foils located on upper and lower surfaces of the FPC, the solder resist layer, and the solder resist layer are of a cubic structure, and specifications of each component part are expressed in a form of length × width × height, and for example, a specification of the first substrate may be 27.5mm × 6.5mm × 0.7mm, a specification of the copper foils may be 0.7mm × 0.7mm × 0.1mm, a specification of the solder resist layer may be 27.5mm × 6.5mm × 0.03mm, a specification of the second substrate may be 27.5mm × 6.5mm × 0.025mm, a specification of the copper foils located on an upper and lower surface of the second substrate may be 0.7mm × 0.47mm × 0.02mm, and a specification of the solder may be 0.7mm × 0.7mm × 0.09mm.

It should be noted that the copper foil on the inner wall of the through hole has a circular ring structure, and the specification of the copper foil can be expressed by a radius x a thickness, where the radius is equal to the outer circle radius of the circular ring minus the inner circle radius of the circular ring, and for example, the specification of the copper foil on the inner wall of the through hole can be R0.035 mm x 0.065mm.

Of course, in some embodiments, the circuit board may further include a gold plating layer disposed on the surface of the copper pad, and the gold plating layer is used to protect the copper pad.

It should be noted that, in the soldering structure of the designated board, regarding each component in the circuit board, such as the copper pad, the gold plating layer, the first substrate, and each component in the electronic component, such as the second substrate (e.g., PI) and the pin, the relevant physical parameters, such as the density of the material, the normal pressure heat capacity (i.e., specific heat capacity), the thermal conductivity (i.e., thermal conductivity), and the like, do not substantially change during the laser soldering process. The physical parameters of solder and the like directly acted by laser vary with the temperature during the laser soldering process.

Based on this, in order to improve the simulation accuracy, in one implementation manner of the first aspect, the relevant physical parameters of the part, corresponding to the circuit board and the electronic component, in the board soldering structure model in the laser soldering process are constants, and the relevant physical parameters of the part, corresponding to the solder, in the board soldering structure model in the laser soldering process are variables which at least partially change with the temperature.

In an implementation manner of the first aspect, when the specified heat conduction boundary condition is obtained, taking the circuit board as a PCB, the electronic component as an FPC, the circuit board including a first substrate, a copper foil and a solder resist layer disposed on the first substrate, the electronic component including a second substrate, and the copper foil and the solder resist layer disposed on the second substrate as examples, when laser is directly irradiated, solid heat transfer is performed between the electronic component and the circuit board, heat conduction at a solder surface with a higher temperature and at a surface of the circuit board close to the electronic component is heat radiation and heat convection, and heat conduction at a side of the circuit board and at a side of the electronic component with a lower temperature is almost no heat conduction and can be approximated to heat insulation. Subsequent calculation accuracy can be improved by setting the surface of the corresponding circuit board close to the electronic component, the surface of the electronic component close to the circuit board and the thermal radiation and thermal convection boundary conditions of the solder surface in the board soldering structure model.

In one implementation manner of the first aspect, the emissivity of the solder surface is 0.2 to 0.5, the emissivity of the surface of the circuit board close to the electronic component and the emissivity of the surface of the electronic component close to the circuit board are both 0.8 to 0.95, and the thermal convection may be natural convection.

In a second aspect, there is provided a plate brazing temperature field distribution determining apparatus comprising: a processor and a memory configured to store computer program instructions. The computer program instructions, when executed by the processor, cause the board brazing temperature field distribution determining apparatus to implement the board brazing temperature field distribution determining method according to the first aspect.

In a third aspect, there is provided a plate brazing temperature field distribution determining apparatus comprising: the device comprises a model building module and a laser brazing simulation module, wherein the model building module is used for building a plate brazing structure model, and the plate brazing structure model is a three-dimensional structure model for specifying a plate brazing structure. The designated board soldering structure includes a circuit board, an electronic component disposed on the circuit board, and a solder disposed between the circuit board and the electronic component. And the laser brazing simulation module is used for carrying out laser brazing simulation on the plate brazing structure model so as to determine the plate brazing temperature field distribution condition of the plate brazing structure model under the conditions of specified target temperature, specified brazing time and specified heat conduction boundary.

The model building module may be any module capable of building a structural model, and may include one software or multiple kinds of software, which is not limited specifically herein.

In an implementation manner of the third aspect, the model building module is specifically configured to build a plane layout of the specified plate brazing structure, and perform three-dimensional modeling on the plane layout to obtain the plate brazing structure model. The model building module can comprise a plane layout building module and a three-dimensional modeling module, wherein the plane layout building module is used for building a plane layout of a specified plate brazing structure, and the three-dimensional modeling module is used for carrying out three-dimensional modeling on the plane layout.

The planar layout construction module and the three-dimensional modeling module can be located in the same software, such as COMSOL software, or the planar layout construction module and the three-dimensional modeling module can be located in different software, such as Proe software and Hypermesh software.

Under the condition that the plane layout building module and the three-dimensional modeling module are located in different software, the model building module further comprises an importing module, and the importing module is used for importing the plane layout into the three-dimensional modeling module.

In one implementation of the third aspect, the laser brazing simulation module includes: the device comprises a laser heating simulation module and a calculation module. And the laser heating simulation module is used for performing laser heating simulation on the plate brazing structure model by utilizing the specified heat source model so as to simulate the laser brazing process of the specified plate brazing structure, and the target heating temperature of each welding spot in the specified plate brazing structure is the specified target temperature in the laser brazing process. The calculation module is used for calculating the temperature of each welding point in the corresponding specified plate brazing structure in the specified brazing time in the laser brazing process of the plate brazing structure model according to relevant physical parameters and specified heat conduction boundary conditions of each component in the specified plate brazing structure in the laser brazing process, so as to obtain the plate brazing temperature field distribution conditions of the plate brazing structure model under the specified target temperature, the specified brazing time and the specified heat conduction boundary conditions; wherein the relevant physical parameters include: material, gauge, atmospheric heat capacity, density and thermal conductivity, specifying thermal conduction boundary conditions for indicating the thermal conductivity of a specified sheet braze structure conducted to the environment during laser brazing.

The laser brazing simulation module can be located in COMSOL software, numerical simulation can be carried out on the distribution of the plate brazing temperature field through COMSOL finite element simulation, so that the distribution conditions of the temperature field under the conditions of specified target temperature, specified brazing time and specified heat conduction boundary can be obtained, the temperature change condition of each welding spot can be predicted, and theoretical basis and technical support are provided for the research on the laser brazing temperature and time.

In one implementation manner of the third aspect, the laser heating simulation module is specifically configured to perform laser heating simulation on the plate brazing structure model by using a gaussian surface heat source model. For example, a gaussian surface heat source model can be directly invoked on a COMSOL software interface to perform laser heating simulation on a plate brazing structure model.

In an implementation manner of the third aspect, the calculation module may include a meshing module and a simulation calculation module, the meshing module is configured to perform meshing on the plate brazing structure model, and the simulation calculation module is configured to calculate a temperature of a position corresponding to each meshed grid at a specified brazing time.

Specifically, a user selects a unit type and an order on the COMSOL software interface according to data types of the plate brazing structure model, a specified heat source model and the like, for example, the plate brazing structure model is divided into free tetrahedral meshes. The simulation calculation module can calculate the temperature of the position corresponding to each grid after grid division in the specified brazing time according to the total calculation time (namely equal to the specified brazing time) and the step length set by the user.

Wherein, the related physical parameters and the specified heat conduction boundary conditions can be obtained by user setting according to the calculation requirements.

In one implementation manner of the third aspect, the laser brazing simulation module further includes: the first acquisition module is used for acquiring relevant physical parameters of each corresponding component in the plate brazing structure model in the laser brazing process.

Specifically, the first obtaining module may include a correspondence between a geometric body corresponding to each component stored in the COMSOL software and the relevant physical parameter, and the relevant physical parameter may be assigned by clicking the geometric body corresponding to each component by a user.

If the geometric body corresponding to the Copper bonding pad is clicked, the material of the Copper bonding pad can be selected, and if the 'hopper' is selected, the physical parameters such as specification, normal-pressure heat capacity, density and heat conductivity coefficient of the 'hopper' can be assigned according to the corresponding relation between the 'hopper' and the physical parameters.

In the designated board soldering structure, relevant physical parameters such as material density, atmospheric pressure heat capacity, thermal conductivity and the like of each component in the circuit board, such as the copper pad and the first substrate, and each component in the electronic component, such as the second substrate and the pin are not basically changed in the laser soldering process. The physical parameters of the solder directly acted by the laser and the like are changed along with the temperature change in the laser brazing process.

Based on this, in order to improve the simulation accuracy, in one implementation manner of the third aspect, the part of the board soldering structure model corresponding to the circuit board and the electronic component is a constant in the related physical parameters in the laser soldering process, and the part of the board soldering structure model corresponding to the solder is a variable that changes with temperature at least in part in the related physical parameters in the laser soldering process.

In one implementation manner of the third aspect, the laser brazing simulation module further includes: and the second acquisition module is used for acquiring the heat conduction boundary conditions of the components in the plate brazing structure model in the laser brazing process.

Specifically, the second obtaining module may include a data input port of a thermal conduction boundary condition corresponding to each component stored in the COMSOL software, and the thermal conduction boundary condition may be set through user input, so as to obtain the thermal conduction boundary condition corresponding to each component in the board soldering structure model in the laser soldering process.

Wherein, when laser direct irradiation, be solid heat transfer between electronic components and the circuit board, on the higher solder surface of temperature, the surface that the circuit board is close to electronic components, and the heat conduction that electronic components is close to the surface of circuit board 1 is heat radiation and thermal convection, there is not heat conduction at the lower side of circuit board and electronic components of temperature nearly, can be approximate for thermal insulation, consequently, in an implementation of third aspect, the second acquires the module, specifically be used for acquireing the surface that the corresponding circuit board is close to electronic components in the board brazing structure model, electronic components is close to the surface of circuit board, and the heat radiation and the thermal convection boundary condition on solder surface, can improve subsequent computational accuracy.

In one implementation form of the third aspect, the plate brazing temperature field distribution determining apparatus further includes: the device comprises a temperature field distribution diagram generating module and a temperature field distribution diagram generating module, wherein the temperature field distribution diagram generating module is used for generating a plate brazing temperature field distribution diagram of the plate brazing structure model under the conditions of specified target temperature, specified brazing time and specified heat conduction according to the plate brazing temperature field distribution conditions of the plate brazing structure model under the conditions of specified target temperature, specified brazing time and specified heat conduction. In the plate brazing temperature field profile, the plate brazing structure model is different in filling color and/or pattern corresponding to different temperatures and grids. The method comprises the steps of determining the distribution conditions of the plate brazing temperature field of a plate brazing structure model under the conditions of specified target temperature, specified brazing time and specified heat conduction boundary, processing the data of the distribution conditions of the plate brazing temperature field of the determined plate brazing structure model under the conditions of the specified target temperature, the specified brazing time and the specified heat conduction boundary through finite element software to obtain the distribution patterns of the plate brazing temperature field of the plate brazing structure model under the conditions of the specified target temperature, the specified brazing time and the specified heat conduction boundary, and obtaining the temperature distribution patterns of all welding spots in the specified plate brazing structure under the conditions of the specified target temperature, the specified brazing time and the specified heat conduction boundary through the corresponding position relation of all the welding spots in the specified plate brazing structure and grids.

In a fourth aspect, a computer-readable storage medium is provided, having stored thereon computer program instructions which, when run on a board brazing temperature field distribution determining apparatus, cause the board brazing temperature field distribution determining apparatus to carry out the board brazing temperature field distribution determining method according to the first aspect.

The technical effects brought by any one of the design manners in the second aspect to the fourth aspect may refer to the technical effects brought by different design manners in the first aspect, and are not described herein again.

Drawings

FIG. 1 is a schematic diagram of a plate brazing structure model provided in an embodiment of the present application;

FIG. 2 is a sectional structural view of a brazing structure of a designated plate according to an embodiment of the present application;

FIG. 3 is a cross-sectional structural view of a circuit board and an electronic component soldered by solder overflow in a designated board soldering structure according to an embodiment of the present application;

FIG. 4 is a flowchart of a method for determining a temperature field distribution of a plate brazing according to an embodiment of the present application;

FIG. 5 is a flow chart of a method for constructing a plate brazing structure model according to an embodiment of the present disclosure;

FIG. 6 is a flowchart illustrating a laser brazing simulation performed on a plate brazing structure model to determine a distribution of a plate brazing temperature field of the plate brazing structure model under a specified target temperature, a specified brazing time, and a specified thermal conduction boundary condition according to an embodiment of the present disclosure;

FIG. 7 is a partial cross-sectional structural view of a plate brazing structural model provided in an embodiment of the present application;

FIG. 8 is a graph of power density of a heat source term over time during a laser heating simulation provided by an embodiment of the present application;

FIG. 9A is a graph of thermal conductivity of a solder material as a function of temperature according to an embodiment of the present application;

FIG. 9B is a graph of specific heat capacity of a solder as a function of temperature according to an embodiment of the present application;

FIG. 10 is a block diagram of a system for determining a plate brazing temperature field distribution according to an embodiment of the present application;

FIG. 11 is a block diagram of a plate brazing temperature field distribution determining apparatus according to an embodiment of the present disclosure;

FIG. 12 is a partial cross-sectional structural view of another plate brazing structural model provided in an embodiment of the present application;

FIG. 13A is a graph of a plate brazing temperature field profile at a specified brazing time of 32s according to an embodiment of the present application;

FIG. 13B is a graph of a plate brazing temperature field profile at a specified brazing time of 42s according to an embodiment of the present application;

FIG. 13C is a graph of a plate brazing temperature field profile at a specified brazing time of 52s according to an embodiment of the present application;

FIG. 14A is a graph of a plate brazing temperature field profile at a specified brazing time of 40s according to an embodiment of the present application;

FIG. 14B is a graph of a plate brazing temperature field profile at a specified brazing time of 50s according to an embodiment of the present application;

FIG. 14C is a graph of a plate brazing temperature field profile at a given brazing time of 60s according to an embodiment of the present application;

FIG. 15A is another plate brazing temperature field profile provided by an embodiment of the present application at a designated brazing time of 40 s;

FIG. 15B is another plate brazing temperature field profile provided by an embodiment of the present application at a specified brazing time of 50 s;

FIG. 15C is a graph of the plate brazing temperature field profile at a given brazing time of 70s, as provided by an example of the present application.

Detailed Description

The embodiment of the present application provides a method for determining a distribution of a plate brazing temperature field, which is used for performing a laser brazing simulation on a plate brazing structure model 10 shown in fig. 1, so as to determine a distribution of the plate brazing temperature field of a specified plate brazing structure 20 shown in fig. 2 or fig. 3 under specified target temperature, specified brazing time and specified heat conduction boundary conditions. As shown in fig. 4, the method may include S10-S20:

and S10, constructing a plate brazing structure model 10. The sheet brazed structure model 10 is a three-dimensional structure model that specifies the sheet brazed structure 20. As shown in fig. 2, the designated board soldering structure 20 includes a circuit board 1, an electronic component 2 disposed on the circuit board 1, and a solder 3 disposed between the circuit board 1 and the electronic component 2.

As shown in fig. 1 and 2, the designated board soldering structure 20 is any structure that requires soldering of the circuit board 1 and the electronic component 2 by a soldering process.

In some embodiments, as shown in fig. 2, the circuit board 1 may include a plurality of copper pads 121, the electronic component 2 may include a plurality of leads 221, and the solder 3 may be disposed between the leads 221 of the electronic component 2 and the copper pads 121 of the circuit board 1. The electronic component 2 and the circuit board 1 are soldered in a soldering process by the pins 221, the copper pads 121 and the solder 3.

In some embodiments, with continued reference to fig. 2, the Circuit Board 1 may be exemplified by a Printed Circuit Board (PCB), and the electronic component 2 may be exemplified by a Flexible Printed Circuit Board (FPC). The circuit board 1 may include a first substrate 11, a copper foil 12 and a solder resist layer 13 disposed on a surface of the first substrate 11, in addition to the plurality of copper pads 121, the solder resist layer 13 covers the copper foil 12, and a portion of the solder resist layer 13 exposed from the copper foil 12 constitutes the copper pads 121. The electronic component 2 may further include a second substrate 21, and a copper foil 22 and a solder resist 23 disposed on a surface of the second substrate 21, in addition to the above-mentioned leads 221, the second substrate 21 is formed with a through hole, and portions of the copper foil 22 located on an inner wall of the through hole and upper and lower surfaces of the second substrate 21 constitute the leads 221. Before soldering, solder 3 may be disposed on copper pad 121 at a position corresponding to the through hole, and at the time of soldering, the solder melts, overflows through the through hole, and is soldered to copper pad 121 and pin 221, resulting in the structure shown in fig. 3.

In these embodiments, the plate brazed structure model 10 may be constructed in accordance with the structures of the respective constituent members in the specified plate brazed structure 20, and the positions and connection relationships therebetween.

Specifically, the building plate brazing structure model 10 described in S10, as shown in fig. 5, includes S101 to S102:

s101, constructing a plane layout of the specified plate soldering structure 20 in specified drawing software based on the operation of a user.

For example, the user may draw, in the drawing software, geometric objects corresponding to the structures of the components in the specified board soldering structure 20 according to the structures of the components in the specified board soldering structure 20, and set the positions of the geometric objects corresponding to the components according to the positions and connection relationships between the components, so as to obtain the planar layout of the specified board soldering structure 20.

By way of example, the designated drawing software may be Proe software, CAdence software, etc.

Specifically, as shown in fig. 2, taking the specified drawing software as the prose software as an example, geometric objects corresponding to the first base 11, the copper foil 12, the solder resist layer 13 included in the circuit board 1, the second base 21, the copper foil 22, the solder resist layer 23, the solder 3 included in the electronic component 2, and the like may be drawn in the prose software, and the positions and angles of the geometric objects corresponding to the respective component parts may be adjusted according to the positional relationship of the respective component parts, so that the positional relationship between the geometric objects corresponding to the respective component parts corresponds to the actual positional relationship of the respective component parts.

Specifically, taking the above-mentioned mutual contact among the copper pad 121, the solder 3 and the lead 221 as an example, the geometric bodies corresponding to the copper pad 121, the solder 3 and the lead 221 are tightly combined and embodied in the board soldering structural model 20, as shown in fig. 2, an overlap is provided between the edge of the geometric body corresponding to the copper pad 121 and the edge of the geometric body corresponding to the solder 3, and an overlap is provided between the edge of the geometric body corresponding to the solder 3 and the edge of the geometric body corresponding to the lead 221.

The geometric body corresponding to each component of the above-mentioned specified plate brazing structure 20 is not particularly limited, and the geometric body can be constructed for each component according to whether the material is the same or not.

For example, taking the circuit board 1 as a PCB and the electronic component 2 as an FPC as an example, the first substrate 11 may have a single-layer structure or a multi-layer structure, as shown in fig. 7, in the case that the first substrate 11 has a single-layer structure, the material of the first substrate 11 may be a resin material or a composite material of glass fiber and resin, and in this case, the first substrate 11 may be used as a whole to construct a corresponding geometric body, for example, the geometric body corresponding to the first substrate 11 is a cube. In the case that the first substrate 11 is a multi-layer structure, the material of each layer structure in the first substrate 11 may be a resin material, or a composite material of glass fiber and resin, and at this time, a single layer or multiple layers of copper foil 12 may be disposed between two adjacent layers of structures to realize the wiring of the circuit board 1, at this time, each layer structure in the first substrate 11 as a whole constructs a corresponding geometric body, for example, one layer of copper foil 12 as a whole constructs a corresponding geometric body (for example, may be a cube), and the structural layer of the resin material as a whole constructs a corresponding geometric body (for example, may be a cube). As shown in fig. 7, the material of the second substrate 21 may be a flexible material, such as Polyimide (PI), and in this case, the geometric body corresponding to the second substrate 21 may also be a cube.

In addition, as shown in fig. 7, the geometric body of the plate soldering structural model 10 corresponding to the solder 3 may be a cube, and in the soldering process, as the solder 3 melts and overflows from the through hole, the finally obtained solder has an i-shaped structure.

In some embodiments, as shown in fig. 7, the first substrate 11 may have a size of 27.5mm × 6.5mm × 0.7mm, the copper foil 12 may have a size of 0.7mm × 0.7mm × 0.1mm, the solder 3 may have a size of 0.7mm × 0.7mm × 0.09mm, the through hole may have a size of R0.025 mm × 0.065mm (R represents a radius of the through hole, and 0.065 represents a height of the through hole), the copper foil 22 positioned in the through hole may have a size of R0.035 mm × 0.065mm (R may be equal to an outer radius of the circular ring shape minus an inner radius of the circular ring shape), the second substrate 21 may have a size of 0.7mm × 0.47mm × 0.02mm, and the copper foils 22 on upper and lower surfaces of the second substrate 21 may have a size of 0.7mm × 0.47mm × 0.02mm.

And S102, performing three-dimensional modeling on the plane layout to obtain a plate brazing structure model 10.

Specifically, the plane layout may be imported into three-dimensional modeling software, and the three-dimensional modeling software may be used to perform three-dimensional modeling on the plane layout, so as to obtain the board brazing structure model 10.

For example, taking the plane layout of the specified board brazing structure 20 drawn in the pro software as an example, the drawn plane layout may be imported into Hypermesh software for three-dimensional modeling, so as to obtain the board brazing structure model 10 shown in fig. 1.

Of course, the planar layout of the specified board brazing structure 20 may also be directly drawn in the COMSOL software, and the COMSOL software is used to perform three-dimensional modeling on the drawn planar layout, so as to obtain the board brazing structure model 10 shown in fig. 1.

S20, performing laser brazing simulation on the plate brazing structure model 10 to determine the plate brazing temperature field distribution condition of the plate brazing structure model 10 under the conditions of the specified target temperature, the specified brazing time and the specified heat conduction boundary, and accordingly determining the plate brazing temperature field distribution condition of the specified plate brazing structure 20 under the conditions of the specified target temperature, the specified brazing time and the specified heat conduction boundary.

Compared with the temperature and time of the laser brazing which are required to be obtained through a large amount of groping experiments in the related technology, the temperature and time of the laser brazing can be researched in a numerical simulation mode without a large amount of groping experiments, so that the labor can be saved, the cost is reduced, and the theoretical basis can be provided for accurately controlling the temperature and time of the laser brazing.

Specifically, the sheet braze structural model 10 may be simulated by laser brazing using finite element software (e.g., COMSOL software) to determine the sheet braze temperature field distribution of the sheet braze structural model 10 at a specified target temperature, a specified braze time, and specified thermal conduction boundary conditions.

In some embodiments, S20 performs a laser brazing simulation on the plate brazing structure model 10 to determine a plate brazing temperature field distribution of the plate brazing structure model 10 under specified target temperature, specified brazing time and specified thermal conduction boundary conditions, as shown in fig. 6, including S201-S205:

s201, performing laser heating simulation on the plate brazing structure model 10 by using a specified heat source model to simulate a laser brazing process of the specified plate brazing structure 20, wherein in the laser brazing process, the target heating temperature of each welding point X in the specified plate brazing structure 20 is a specified target temperature.

In some embodiments, the heat source model is specified as a gaussian surface heat source model.

If the surface temperature of a circle is the same, the heat source model of the circle is equivalent to the temperature of a circle with a large diameter, and the Gaussian heat source model is qualitatively understood as that: the temperature is in the circle range of equal diameter, the center is higher and the outer edge is lower. The quantitative understanding is: in the circle range with the same diameter, the temperature is distributed according to a Gaussian curve, and the Gaussian distribution is normal distribution.

In these embodiments, the laser brazing process can be accurately simulated by laser heating simulation of the plate brazing structure model 10 using a gaussian surface heat source model.

In some embodiments, S201 performs laser heating simulation on the plate brazed structure model 10 using the specified heat source model to simulate a laser brazing process of the specified plate brazed structure 20, including:

as shown in fig. 8, the power density of the heat source item is obtained in a first time period T1 and a second time period T2 which are consecutive and consecutive, the power density of the heat source item is increased from 0 to a preset threshold value in the first time period T1 so that the temperature of each welding point in the corresponding specified plate brazing structure 20 in the plate brazing structure model 10 is increased to a specified target temperature, and the power density of the heat source item is adjusted to be smaller than the preset threshold value in the second time period T2 so that the temperature of each welding point in the corresponding specified plate brazing structure 20 in the plate brazing structure model 10 is stabilized at the specified target temperature.

In an example, taking the circuit board 1 as a PCB and the electronic component 2 as an FPC as an example, in the first time period T1, the temperature of the solder joint may be increased to a specified target temperature by a larger power density, and in the second time period T2, the power density is adjusted to be smaller, so that the solder joint temperature is substantially stabilized at the specified target temperature. In the process, the first time period T1 is a heating process, and the second time period T2 is a constant temperature process, so that the temperature of the welding spot can be effectively controlled to be stabilized at a specified target temperature.

In some embodiments, the preset threshold may be 1.1 × 10 ⁶ W/m ³ ～1.9×10 ⁶ W/m ³ Any value of (1).

In some examples, the first period of time T1 may be a period of 0s to 5s, and the second period of time T2 may be a period of 5s to (60 to 90) s. That is, the second period T2 may be a period of 5s to 60s, a period of 5s to 65s, a period of 5s to 70s, a period of 5s to 75s, a period of 5s to 80s, a period of 5s to 85s, or a period of 5s to 90 s.

In the second time period T2, the power density of the heat source item may be directly obtained as a certain value smaller than the preset threshold, or the power density of the heat source item may also be obtained as a power density that changes with time, which is not specifically limited herein.

In some embodiments, as shown in fig. 8, the second time period T2 includes a first sub-time period T21 and a second sub-time period T22 which are consecutive, and the power density of the heat source term is maintained at 5.0 × 10 during the first sub-time period T21 ⁵ W/m ³ ～15.0×10 ⁵ W/m ³ In the second sub-period T22, the power density of the heat source term is controlled to be 5.0 × 10 ⁵ W/m ³ ～15.0×10 ⁵ W/m ³ Reduced to 2.4 × 10 ⁵ W/m ³ ～4.22×10 ⁵ W/m ³ To maintain a specified target temperature.

Wherein, in the second sub-period, the power density of the heat source item is controlled to be 5.0 × 10 ⁵ W/m ³ ～15.0×10 ⁵ W/m ³ Reduced to 2.4 × 10 ⁵ W/m ³ ～4.22×10 ⁵ W/m ³ It means that the power density of the heat source item can be controlled from 5.0 x 10 ⁵ W/m ³ ～15.0×10 ⁵ W/m ³ Any value in the range is reduced to 2.4 × 10 ⁵ W/m ³ ～4.22×10 ⁵ W/m ³ Any value within the range. For example, the power density of the heat source term may be 5.0 × 10 ⁵ W/m ³ Reduced to 2.4 × 10 ⁵ W/m ³ Can be made of 10.0 × 10 ⁵ W/m ³ Reduced to 3.0 × 10 ⁵ W/m ³ Can be made of 15.0 × 10 ⁵ W/m ³ Reduced to 4.22 × 10 ⁵ W/m ³ Alternatively, it may be made of 15.0 × 10 ⁵ W/m ³ Reduced to 2.4 × 10 ⁵ W/m ³ 。

In these embodiments, by acquiring the power density of the heat source item in the first sub-period T21 as a value smaller than the preset threshold, the temperature rise process can be slowed down, so as to gradually stabilize the temperature of each welding point X in the brazing structure of the specified plate at the specified target temperature, and by acquiring the power density of the heat source item in the second sub-period T22 as the power density that changes with time, the specified target temperature can be accurately maintained in the second sub-period T22.

In some examples, the first sub-period T21 may be a period of 5s to (10-50) s, and the second sub-period T22 may be a period of (10-50) s to (60-90) s.

The first sub-period T21 may be a period of 5s to 10s, a period of 5s to 15s, a period of 5s to 20s, a period of 5s to 25s, a period of 5s to 30s, a period of 5s to 35s, a period of 5s to 40s, a period of 5s to 45s, or a period of 5s to 50 s. In the case where the first sub-period T21 is a period of 5s to 10s, the second sub-period T22 is a period of 10s to (60 to 90) s, in the case where the first sub-period T21 is a period of 5s to 15s, the second sub-period T22 is a period of 15s to (60 to 90) s, in the case where the first sub-period T21 is a period of 5s to 20s, the second sub-period T22 is a period of 20s to (60 to 90) s, in the case where the first sub-period T21 is a period of 5s to 25s, the second sub-period T22 is a period of 25s to (60 to 90) s, in the case where the first sub-period T21 is a period of 5s to 30s, the second sub-period T22 is a period of 30s to (60 to 90) s, in the case where the first sub-period T21 is a period of 5s to 35s, the second sub-period T22 is a period of 35s to (60 to 90) s, in the case where the first sub-period T21 is a period of 5s to 40s, the second sub-period T22 is a period of 40s to (60 to 90) s, in the case where the first sub-period T21 is a period of 5s to 45s, the second sub-period T22 is a period of 45s to (60 to 90) s, in the case where the first sub-period T21 is a period of 5s to 50s, the second sub-period T22 is a period of 50s to (60 to 90) s, when the second sub-period T22 is a period of 10s to (60 to 90) s, the second sub-period T22 may be a period of 10s to 60s, a period of 10s to 65s, a period of 10s to 70s, a period of 10s to 75s, a period of 10s to 80s, a period of 10s to 85s, or a period of 10s to 90 s; by analogy, when the second sub-period is a period of 50s to (60 to 90) s, the second sub-period may be a period of 50s to 60s, a period of 50s to 65s, a period of 50s to 70s, a period of 50s to 75s, a period of 50s to 80s, a period of 50s to 85s, or a period of 50s to 90 s.

S204, according to the parts corresponding to all the components in the plate brazing structure model 10, relevant physical parameters and specified heat conduction boundary conditions in the laser brazing process, calculating the temperature of each welding point in the corresponding specified plate brazing structure 20 in the specified brazing time of the plate brazing structure model 10 in the laser brazing process, and obtaining the plate brazing temperature field distribution conditions of the plate brazing structure model 10 under the specified target temperature, the specified brazing time and the specified heat conduction boundary conditions; wherein the relevant physical parameters include: material, gauge, atmospheric heat capacity (i.e., specific heat capacity), density, and thermal conductivity (i.e., thermal conductivity), specifying thermal conduction boundary conditions for indicating the thermal conductivity of the specified plate brazed structure 20 to the environment during laser brazing.

As an example, the temperature of each spot X in the sheet braze structure 20 at a given brazing time during the laser brazing process of the sheet braze structure model 10 may be calculated in a finite element software (e.g., COMSOL software) based on the associated physical parameters and the specified thermal conduction boundary conditions of the portion of the sheet braze structure model 10 corresponding to each component part during the laser brazing process to obtain the sheet braze temperature field distribution of the sheet braze structure model 10 at the specified target temperature, the specified brazing time, and the specified thermal conduction boundary conditions.

Specifically, in some embodiments, the S204 is to calculate the temperature of each welding point X corresponding to the designated plate brazing structure 20 in the designated brazing time during the laser brazing process of the plate brazing structure model 10 according to the relevant physical parameters and the designated heat conduction boundary conditions of the parts corresponding to the component parts in the plate brazing structure model 10 during the laser brazing process, so as to obtain the distribution of the plate brazing temperature field of the plate brazing structure model 10 under the designated target temperature, the designated brazing time and the designated heat conduction boundary conditions, and includes:

and meshing the plate brazing structure model 10, and calculating the temperature of the position corresponding to each meshed grid in the appointed brazing time.

The mesh division is to divide the model into a plurality of small units, which are used as the important factor in the pretreatment of finite element analysis, and the matching degree of the mesh division and the calculation target and the quality of the mesh determine the quality of the later finite element calculation.

The number of grids affects the accuracy of the calculation result and the size of the calculation scale. Generally, the number of grids is increased, the calculation accuracy is improved, but the calculation scale is also increased, so that the two factors are balanced and considered comprehensively when the number of grids is determined.

In practical applications, the user may select a suitable meshing scheme based on the associated data type in the sheet braze structural model 10 and the specified heating model.

In some embodiments, the way of meshing is free tetrahedral meshing.

In some embodiments, the plate brazing temperature field distribution determining method further comprises: s205, generating a plate brazing temperature field distribution pattern of the plate brazing structure model 10 under the specified target temperature, the specified brazing time and the specified heat conduction boundary conditions according to the plate brazing temperature field distribution condition of the plate brazing structure model 10 under the specified target temperature, the specified brazing time and the specified heat conduction boundary conditions. In the plate brazing temperature field pattern, the plate brazing structure model 10 differs in filling color and/or pattern in the grid corresponding to different temperatures.

In these embodiments, the data of the determined plate brazing temperature field distribution of the plate brazing structure model 10 at the specified target temperature, the specified brazing time and the specified heat conduction boundary conditions may be processed by the finite element software to obtain a plate brazing temperature field distribution of the plate brazing structure model 10 at the specified target temperature, the specified brazing time and the specified heat conduction boundary conditions, so as to obtain a plate brazing temperature field distribution of the specified plate brazing structure 20 at the specified target temperature, the specified brazing time and the specified heat conduction boundary conditions, and the temperature distribution maps of the respective welding spots of the specified plate brazing structure 20 at the specified target temperature, the specified brazing time and the specified heat conduction boundary conditions may be obtained by specifying the position corresponding relationship between the respective welding spots of the plate brazing structure 20 and the grid.

In some embodiments, in S204, before calculating the temperature of each welding spot corresponding to each welding spot in the designated plate brazing structure 20 during the laser brazing process of the plate brazing structure model 10 at the designated brazing time according to the relevant physical parameters and the designated heat conduction boundary conditions of the portion corresponding to each component part in the plate brazing structure model 10 during the laser brazing process, the plate brazing temperature field distribution determining method further includes:

s202, acquiring related physical parameters; and S203, acquiring specified heat conduction boundary conditions.

Specifically, when the relevant physical parameters are obtained, the circuit board 1 is taken as a PCB, the electronic component 2 is taken as an FPC, the circuit board 1 includes a first substrate 11, a copper foil 12 and a solder resist layer 13 which are arranged on the first substrate 11, the electronic component 2 includes a second substrate 21, a copper foil 22 and a solder resist layer 23 which are arranged on the second substrate 21, for example, parts of the board soldering structure model 10 corresponding to the components respectively correspond to the corresponding geometric bodies, and the relevant physical parameters of the parts of the board soldering structure model 10 corresponding to the components in the laser soldering process can be obtained by assigning values to the material, specification, normal pressure heat capacity, density and thermal conductivity of each geometric body of the board soldering structure model 10.

Specifically, taking finite element software as COMSOL software as an example, the COMSOL software can store corresponding relations between geometric bodies corresponding to each component and corresponding parameters such as materials, specifications, normal pressure heat capacity (that is, specific heat capacity), density and heat conductivity (that is, heat conductivity), so that by clicking the corresponding geometric bodies by users, the parameters such as the materials, specifications, normal pressure heat capacity, density and heat conductivity corresponding to the corresponding geometric bodies can be obtained, thereby completing the assignment.

In the case where the components are cubic except for the copper foil 12 located on the inner wall of the through hole, and the specification of each component includes parameters such as length, width, and height, as shown in fig. 7, the first substrate 11, the second substrate 21, the copper foil 12, the copper foil 22 located on the upper and lower surfaces of the FPC, the solder resist layer 13, and the solder resist layer 23 are cubic, and the specification of each is expressed in a form of length × width × height, and as an example, the specification of the first substrate 11 may be 27.5mm × 6.5mm × 0.7mm, the specification of the copper foil 12 may be 0.7mm × 0.7mm × 0.1mm, the specification of the solder resist layer 13 may be 27.5mm × 6.5mm × 0.03mm, the specification of the second substrate 21 may be 27.5mm × 6.5mm × 0.025mm, and the specification of the copper foil on the upper and lower surfaces of the second substrate 21 may be 0.7mm × 0.47mm × 0.02mm, and the specification of the solder resist layer 3 may be 0.7 × 0.09mm.

It should be noted that the copper foil 12 on the inner wall of the through hole has a circular ring structure, and the specification of the copper foil can be expressed by a radius x a thickness, where the radius is equal to the outer circle radius of the circular ring minus the inner circle radius of the circular ring, and for example, as shown in fig. 7, the specification of the copper foil 12 on the inner wall of the through hole can be R0.035 mm x 0.065mm.

Of course, in some embodiments, the circuit board 1 may further include a gold plating layer disposed on the surface of the copper pad 121, and the gold plating layer is used to protect the copper pad.

It should be further noted that, in the designated board soldering structure 20, for each component in the circuit board 1, such as the copper pad 121, the gold plating layer, and the first substrate 11, and each component in the electronic component 2, such as the second substrate 21 (e.g., PI) and the pin 221, relevant physical parameters, such as the density of the material, the normal pressure heat capacity (i.e., specific heat capacity), the thermal conductivity (i.e., thermal conductivity), and the like, do not substantially change during the laser soldering process. The physical parameters of the solder 3 and the like directly acted by the laser vary with the temperature during the laser brazing process.

Based on this, in order to improve the simulation accuracy, in some embodiments, the relevant physical parameters of the parts of the board soldering structure model 10 corresponding to the circuit board 1 and the electronic component 2 during the laser soldering process are constant, and the relevant physical parameters of the parts of the board soldering structure model 10 corresponding to the solder 3 during the laser soldering process are at least partially variable with temperature.

As shown in table 1, the relevant physical parameters of the parts of the board soldering structure model 10 corresponding to the circuit board 1 and the electronic component 2 during the laser welding process, and the specific values of the relevant physical parameters of the parts of the board soldering structure model 10 corresponding to the solder 3 during the laser soldering process are shown.

TABLE 1

Component (Material)	Density (Kg/m) ³ )	Thermal conductivity W/(m.K)	Specific heat capacity J/(kg. K)
				First base (PCB substrate)	1900	0.3	1369
Copper pad (copper)	8960	400	385
				Gold plating layer (gold)	19300	318	120
Second substrate (PI)	1480	0.15	1100
				Solder mask (printing ink)	1450	0.23	300
Solder (SnBiAg)	7.41	FIG. 9A	FIG. 9B

As can be seen from table 1, the relevant physical parameters of the parts (such as the PCB substrate, copper, gold, PI, ink, etc. in table 1) corresponding to the circuit board 1 and the electronic component 2 in the board soldering structure model 10 during the laser soldering process are all constants, the density of the parts corresponding to the solder 3 in the board soldering structure model during the laser soldering process is a constant, the thermal conductivity is a variable varying with temperature as shown in fig. 9A, and the specific heat capacity is a variable varying with temperature as shown in fig. 9B.

In some embodiments, when the specified thermal conduction boundary condition is obtained, taking the circuit board 1 as a PCB, the electronic component 2 as an FPC, the circuit board 1 including the first substrate 11, and the copper foil 12 and the solder resist layer 13 disposed on the first substrate 11, the electronic component 2 including the second substrate 21, and the copper foil 22 and the solder resist layer 23 disposed on the second substrate 21 as examples, when laser light is directly irradiated, solid heat transfer is performed between the electronic component 2 and the circuit board 1, and heat conduction at the surface of the solder 3 with a higher temperature, the surface of the circuit board 1 close to the electronic component 2, and the surface of the electronic component 2 close to the circuit board 1 is heat radiation and heat convection, and there is almost no heat conduction at the side of the circuit board 1 and the side of the electronic component 2 with a lower temperature, and thermal insulation can be approximated, therefore, when the specified thermal conduction boundary condition is obtained, the thermal radiation and heat convection boundary condition corresponding to the surface of the circuit board 1 close to the electronic component 2, the surface of the electronic component 2 close to the circuit board 1, and the surface of the solder 3 in the board soldering structure model 10.

In these embodiments, the subsequent calculation accuracy can be improved by setting the boundary conditions of the heat radiation and the heat convection corresponding to the surface of the circuit board 1 close to the electronic component 2, the surface of the electronic component 2 close to the circuit board 1, and the surface of the solder 3 in the board soldering structure model 10.

In some embodiments, the emissivity of the surface of the solder 3 is 0.2-0.5, the emissivity of the surface of the circuit board 1 close to the electronic component 2 and the emissivity of the surface of the electronic component 2 close to the circuit board 1 are both 0.8-0.95, and the thermal convection may be natural convection.

Some embodiments of the present application provide a plate brazing temperature field distribution determining system, as shown in fig. 10, comprising: a plate brazing temperature field distribution determining device 30.

The plate brazing temperature field distribution determining device 30 may be an electronic device such as a Personal Computer (PC), a notebook computer, and a server. As shown in fig. 10, the plate brazing temperature field distribution determining apparatus 30 may include: a processor 301 and a memory 302, the memory 302 being configured to store computer program instructions. The computer program instructions, when executed by the processor 301, cause the board brazing temperature field distribution determining apparatus 30 to implement the board brazing temperature field distribution determining method as described above.

Illustratively, as shown in FIG. 10, the above-described plate brazing temperature field distribution determining system may further include a display 40 or the like in addition to the plate brazing temperature field distribution determining means 30.

As shown in fig. 10, the above-described board brazing temperature field distribution determining apparatus 30 may include a processor 301, a memory 302, a communication interface, and the like, which are connected via a bus.

The memory may store computer programs and data, which may include high speed random access memory, and may also include non-volatile memory, such as magnetic disk storage devices, flash memory devices, or other volatile solid state storage devices.

Processor 301 may be coupled to memory 302 to cause plate brazing temperature field distribution determining device 30 to perform its own various functions by running or executing a computer program stored in memory 302. Processor 301 may be one or more general-purpose Central Processing Units (CPUs), microprocessors, application-specific integrated circuits (ASICs), or integrated circuits for controlling the execution of programs in accordance with some embodiments of the present disclosure; the CPU may be a single-core processor (single-CPU) or a multi-core processor (multi-CPU). A processor 301 herein may refer to one or more devices, circuits, or processing cores that process data, such as computer program instructions.

The communication interface is configured to communicate with various types of external devices in various communication methods. And is connected to the processor 301 to transmit data or commands to an external device or receive data or commands transmitted from an external device under the control of the processor 301. The communication interface may be a transceiver, transceiving circuitry, transmitter, receiver, etc.; for example, the communication device may be a Wireless communication device such as a Wi-Fi (Wireless-Fidelity) chip or a bluetooth chip, or may be a wired communication device such as a Universal Serial Bus (USB) interface.

For example, processor 301 may be communicatively coupled to board brazing temperature field distribution determining device 30 via a communication interface, and send control instructions to board brazing temperature field distribution determining device 30 to control board brazing temperature field distribution determining device 30 to perform the above-described board brazing temperature field distribution determining method. The processor 301 may also be connected to the display 40, and controls the display to display images, and in particular, may display a software interface, and the plate brazing structure model 10 and the finally obtained plate brazing temperature field profile, etc. presented on the software interface.

The communication interface may include only a transmitting interface and a receiving interface, or may be a bidirectional communication interface, and when the communication interface is a bidirectional communication interface, the communication interface may serve as both the transmitting interface and the receiving interface, and has a dual function of transmitting and receiving signals.

Some embodiments of the present application provide a plate brazing temperature field distribution determining apparatus 30, as shown in fig. 11, which is a block diagram of the structure of the plate brazing temperature field distribution determining apparatus 30, including: a model building module 31 and a laser brazing simulation module 32. The model building module 31 is configured to build a plate brazing structure model, where the plate brazing structure model is a three-dimensional structure model of a specified plate brazing structure. The designated board soldering structure 20 includes a circuit board 1, an electronic component 2 disposed on the circuit board 1, and solder 3 disposed between the circuit board 1 and the electronic component 2. And the laser brazing simulation module 32 is used for performing laser brazing simulation on the plate brazing structure model 10 so as to determine the plate brazing temperature field distribution condition of the plate brazing structure model 10 under the conditions of the specified target temperature, the specified brazing time and the specified heat conduction boundary.

The model building module 31 may be any module capable of building a structural model, and may include one or more types of software, which is not limited herein.

In some embodiments, the model building module 31 is specifically configured to build a planar layout of the designated board brazing structure 20, and perform three-dimensional modeling on the planar layout to obtain the board brazing structure model 10.

In these embodiments, model building module 31 may include a floorplan building module 311 and a three-dimensional modeling module 312, floorplan building module 311 being configured to build a floorplan for a given board brazed structure 20, and three-dimensional modeling module 312 being configured to model the floorplan in three dimensions.

The planar layout building module 311 and the three-dimensional modeling module 312 may be located in the same software, such as COMSOL software, or the planar layout building module 311 and the three-dimensional modeling module 312 are located in different software, such as pro software and Hypermesh software.

In case the planar layout building block 311 and the three-dimensional modeling block 312 are located in different software, the model building block further comprises an importing block 313, and the importing block 313 is configured to import the planar layout into the three-dimensional modeling block 312.

In some embodiments, the laser brazing simulation module 32 includes: a laser heating simulation module 321 and a calculation module 322. The laser heating simulation module 321 is configured to perform laser heating simulation on the plate brazing structure model 10 by using a specified heat source model, so as to simulate a laser brazing process of the specified plate brazing structure 20, where in the laser brazing process, a target heating temperature of each welding point in the specified plate brazing structure 20 is a specified target temperature. The calculation module 322 is configured to calculate, according to the relevant physical parameters and the specified heat conduction boundary conditions of the components in the specified plate brazing structure 20 in the laser brazing process, the temperatures of the welding spots in the corresponding specified plate brazing structure 20 at the specified brazing time in the laser brazing process of the plate brazing structure model 10, and obtain the plate brazing temperature field distribution conditions of the plate brazing structure model 10 at the specified target temperature, the specified brazing time and the specified heat conduction boundary conditions; wherein the relevant physical parameters include: material, gauge, atmospheric heat capacity, density, and thermal conductivity, specifying thermal conduction boundary conditions for indicating the thermal conductivity of the specified sheet braze structure 20 to the environment during laser brazing. .

In these embodiments, the laser brazing simulation module 32 may be located in the COMSOL software, and the numerical simulation may be performed on the board brazing temperature field distribution through the COMSOL finite element simulation, so that the temperature field distribution under the specified target temperature, the specified brazing time, and the specified heat conduction boundary condition may be obtained, the temperature change condition of each welding spot may be predicted, and a theoretical basis and a technical support may be provided for the research on the laser brazing temperature and time.

In some embodiments, the laser heating simulation module 321 is specifically used for laser heating simulation of the plate brazing structure model 10 using a gaussian surface heat source model. For example, the gaussian surface heat source model can be invoked directly on the COMSOL software interface to perform laser heating simulation on the plate soldering structural model 10.

In some embodiments, the calculating module 322 may include a meshing module 3221 and a simulation calculating module 3222, where the meshing module 3221 is configured to mesh the plate brazing structure model 10, and the simulation calculating module 3222 is configured to calculate a temperature of a position corresponding to each meshed grid at a specified brazing time.

Specifically, a user selects a unit type and an order on the COMSOL software interface according to data types of the plate brazing structure model 10, a specified heat source model and the like, for example, the plate brazing structure model 10 is divided into free tetrahedral meshes. The simulation calculating module 3222 may calculate the temperature of the position corresponding to each grid after the grid division at the specified brazing time according to the total calculation time and the step length set by the user. The designated brazing time can be any time point in the total time length, and the distribution condition of the plate brazing temperature field of the plate brazing structure model under the conditions of the designated target temperature, the designated brazing time and the designated heat conduction boundary can be obtained by directly calling the calculation result of the designated brazing time, such as inputting the designated brazing time by a user.

For example, taking the total calculation time length of 50s as an example, the plate brazing temperature field distribution of the plate brazing structure model at any one or more time points in the time period of 0s to 50s, such as 5s, 10s, 20s, 25s, 30s, 40s, 45s, 50s and the like, can be obtained.

Wherein, the related physical parameters and the specified heat conduction boundary conditions can be obtained through user setting according to the calculation requirements.

In some embodiments, the laser brazing simulation module 32 further comprises: the first obtaining module 323 is used for obtaining relevant physical parameters of each corresponding component part in the plate brazing structure model 10 in the laser brazing process.

Specifically, the first obtaining module 323 may include a correspondence between a geometric body corresponding to each component stored in the COMSOL software and the relevant physical parameter, and may assign the relevant physical parameter by clicking the geometric body corresponding to each component by a user.

If the geometry corresponding to the Copper pad 121 is clicked, the material of the Copper pad 121 can be selected, and if "hopper" is selected, the physical parameters, such as specification, normal pressure heat capacity, density, thermal conductivity and the like, of the Copper pad can be assigned according to the corresponding relationship between the "hopper" and the physical parameters.

In the designated board soldering structure 20, for each component part in the circuit board 1, such as the copper pad 121 and the first substrate 11, and each component part in the electronic component 2, such as the second substrate 21 and the lead 221, relevant physical parameters, such as the density of the material, the atmospheric pressure heat capacity, the thermal conductivity and the like, are not substantially changed during the laser soldering process. The physical parameters of the solder directly acted by the laser and the like are changed along with the temperature change in the laser brazing process.

Based on this, in order to improve the simulation accuracy, in some embodiments, the portion of the board soldering structure model 10 corresponding to the circuit board 1 and the electronic component 2 is constant in the related physical parameters during the laser soldering process, and the portion of the board soldering structure model 10 corresponding to the solder is variable at least partially with temperature change in the related physical parameters during the laser soldering process. Specific values are shown in table 1 above.

In some embodiments, the laser brazing simulation module 32 further comprises: the second obtaining module 324 is configured to obtain boundary conditions of thermal conduction during the laser brazing process of the corresponding components in the plate-brazed structure model 10.

Specifically, the second obtaining module 324 may include a data input port for the thermal conduction boundary conditions corresponding to each component stored in the COMSOL software, and the thermal conduction boundary conditions may be set through user input, so as to obtain the thermal conduction boundary conditions corresponding to each component in the plate brazing structure model 10 during the laser brazing process.

During laser direct irradiation, solid heat transfer is performed between the electronic component 2 and the circuit board 1, the surface of the solder 3 with a higher temperature and the surface of the circuit board 1 close to the electronic component 2 are subjected to heat radiation and heat convection, and the heat conduction of the surface of the electronic component 2 close to the circuit board 1 is almost heat conduction and can be approximated to heat insulation, so in some embodiments, the second obtaining module 324 is specifically configured to obtain the heat radiation and heat convection boundary conditions of the circuit board 1 close to the surface of the electronic component 2, the electronic component 2 close to the surface of the circuit board 1, and the surface of the solder 3 in the board soldering structure model 10, and can improve subsequent calculation accuracy.

In some embodiments, the plate brazing temperature field distribution determining apparatus 30 further comprises: the temperature field distribution generating module 33 and the temperature field distribution generating module 33 are used for generating a plate brazing temperature field distribution of the plate brazing structure model 10 under the specified target temperature, the specified brazing time and the specified heat conduction condition according to the plate brazing temperature field distribution of the plate brazing structure model 10 under the specified target temperature, the specified brazing time and the specified heat conduction condition. In the plate brazing temperature field profile, the plate brazing structure model 10 differs in filling color and/or pattern corresponding to different temperatures and grids.

In these embodiments, the determined data of the plate brazing temperature field distribution of the plate brazing structure model 10 at the specified target temperature, the specified brazing time and the specified heat conduction boundary conditions may be processed by finite element software to obtain a plate brazing temperature field distribution of the plate brazing structure model 10 at the specified target temperature, the specified brazing time and the specified heat conduction boundary conditions, so as to obtain a plate brazing temperature field distribution of the specified plate brazing structure 20 at the specified target temperature, the specified brazing time and the specified heat conduction boundary conditions, and the temperature distribution map of each welding spot X in the specified plate brazing structure 20 at the specified target temperature, the specified brazing time and the specified heat conduction boundary conditions may be obtained by specifying the corresponding position relationship between each welding spot X in the plate brazing structure 20 and the grid.

The apparatus embodiment depicted in fig. 11 is merely illustrative, and for example, the division of the above modules is only one logical functional division, and other divisions may be realized in practice, for example, multiple modules or components may be combined or integrated into another system, or some features may be omitted, or not executed. Each functional module in the embodiments of the present application may be integrated into one processing module, or each module may exist alone physically, or two or more modules are integrated into one module. The above modules in fig. 11 may be implemented in the form of hardware, or may be implemented in the form of software functional units. For example, when implemented in software, the laser heating simulation module 321 and the calculation module 322 may be implemented by software functional modules generated by at least one processor 301 in fig. 10 after reading program codes stored in the memory 302. The above modules in fig. 11 may also be implemented by different hardware in the board soldering temperature field distribution determining apparatus 30, for example, the laser heating simulation module 321 and the calculation module 322 are implemented by a part of processing resources (e.g., one core or two cores in a multi-core processor) in at least one processor 301 in fig. 10, and the model building module 31 is implemented by the rest of processing resources (e.g., other cores in the multi-core processor) in at least one processor 301 in fig. 10, or by a programmable device such as a field-programmable gate array (FPGA) or a coprocessor. Obviously, the above functional modules may also be implemented by combining software and hardware, for example, the model building module is implemented by a hardware programmable device, and the laser heating simulation module and the calculation module are software functional modules generated by the CPU reading the program code stored in the memory 302.

For more details of the above functions of the model building module 31, the laser heating simulation module 321 and the calculation module 322 in fig. 11, reference is made to the related descriptions in the previous embodiments, which are not repeated here, and the plate brazing temperature field distribution determining apparatus 30 also has the same technical effects as the above-described plate brazing temperature field distribution determining method.

An embodiment of the present application further provides a computer storage medium storing computer program instructions that, when run on a board brazing temperature field distribution determining apparatus, cause the board brazing temperature field distribution determining apparatus to execute the board brazing temperature field distribution determining method as described above.

The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments.

In the above embodiments, the implementation may be wholly or partially realized by software, hardware, firmware, or any combination thereof. When implemented using a software program, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer program instructions. The procedures or functions according to the embodiments of the present application are wholly or partially generated when the computer program instructions are loaded and executed on a computer. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer program instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center by wire (e.g., coaxial cable, fiber optic, digital Subscriber Line (DSL)), or wirelessly (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device including one or more available media integrated servers, data centers, and the like. The usable medium may be a magnetic medium (e.g., floppy disk, magnetic tape), an optical medium (e.g., digital Video Disk (DVD)), or a semiconductor medium (e.g., solid State Drive (SSD)), among others.

In order to more clearly describe the flow of the overall plate brazing temperature field distribution determining method, the following description will be given by way of specific examples.

Example 1

(1) Establishing a plate brazing structure model 10:

as shown in fig. 12, the specifications of the board soldering structure model 10 were set to 27.5mm × 6.5mm × 0.7mm (geometry 1 (corresponding to PCB substrate)), 0.7mm × 0.7mm × 0.1mm (geometry 2 (corresponding to PCB Cu)), 27.5mm × 6.5mm × 0.03mm (geometry 3 (corresponding to PCB ink)), 27.5mm × 6.5mm × 0.06mm (geometry 4 (corresponding to FPC ink)), 0.7mm × 0.7mm × 0.09mm (geometry 5 (corresponding to solder)), R0.035 mm × 0.065mm (geometry 6 (corresponding to FPC copper)), 0.7mm × 0.47mm × 0.02mm (geometry 7 (corresponding to FPC copper)), and 0.7mm × 0.47mm × 0.02mm (geometry 8 (corresponding to FPC copper)), 27.5mm × 6.5mm × 0.025mm (geometry 9mm (corresponding to FPC copper)), and 0.19 mm × 0.03mm (corresponding to FPC ink (geometry 2 mm)). The angle positions of the 10 geometric bodies are adjusted, so that the upper and the lower parts are tightly combined.

(2) Establishing a Gaussian heat source model:

the laser brazing process is divided into a heating process and a constant temperature process. First, a higher power density is set to increase the solder joint to a specified target temperature. The power density is then adjusted to substantially stabilize the solder joint temperature at the specified target temperature. The power density of the heat source is increased from 0 to 1.1 multiplied by 10 within 0s-5s ⁶ W/m ³ ～1.9×10 ⁶ W/m ³ And kept at 5.0X 10 within 5s to (10 to 50) s ⁵ W/m ³ ～15.0×10 ⁵ W/m ³ From (10-50) s to (60-90) s, by 5.0X 10 ⁵ W/m ³ ～15.0×10 ⁵ W/m ³ Reduced to 2.4 × 10 ⁵ W/m ³ ～4.22×10 ⁵ W/m ³ 。

(3) Giving different material parameters to each part of the plate brazing structure model, and setting heat conduction boundary conditions:

clicking geometry 1, searching 'FR 4' in a COMSOL database, and giving the geometry 1; clicking the geometry 2, 6, 7, 8, searching the 'hopper' in the COMSOL database, and assigning the geometry 2, 6, 7, 8; clicking the geometric body 3, and setting the normal-pressure heat capacity, density and heat conductivity coefficient of the geometric body; clicking the

geometric bodies

4, 5 and 10, and setting the normal-pressure heat capacity, density and heat conductivity coefficient of the geometric bodies; click on geometry 9, search for "PI" in the COMSOL database, and assign to geometry 9. A united body formed by the FPC, the PCB and the solder is set, and solid heat transfer is carried out between the upper part and the lower part of a workpiece (a board soldering structural model) when laser is directly irradiated. And setting boundary conditions of heat radiation and heat convection on the surface of the solder with higher temperature, the lower surface of the FPC and the upper surface of the PCB, wherein the radiation rate of the solder to the environment is 0.2-0.5, the radiation rate of the lower surface of the FPC and the upper surface of the PCB to the environment is 0.8-0.95, and the type of convection heat transfer is set to be natural convection, so that the side surfaces of the PCB and the FPC with lower temperature are approximately thermally insulated.

(4) Dividing free tetrahedral meshes and setting appointed brazing time for calculation:

the way of meshing is chosen to be a free tetrahedral mesh. Study entry, at "step 1: setting the calculation step length to be 1s and the total time to be 52s in the transient state setting, checking whether parameter setting is wrong, and clicking "= calculating" to enter calculation if no parameter setting is wrong. And after the calculation is finished, analyzing and processing the calculated data in the result to obtain a plate brazing temperature field distribution diagram.

In the brazing temperature field pattern of the plate obtained in this example, as shown in fig. 13A, the maximum surface temperature of the nugget (shown by the small square in fig. 13A) was designated 240 ℃ when the brazing time was 32s, as shown in fig. 13B, the maximum surface temperature of the nugget (shown by the small square in fig. 13B) was designated 239 ℃ when the brazing time was 42s, and as shown in fig. 13C, the maximum surface temperature of the nugget (shown by the small square in fig. 13C) was designated 239 ℃ when the brazing time was 52 s.

Example 2

(1) Establishing a plate brazing structure model:

as shown in fig. 12, the specifications of the board soldering structure model 10 were set to 27.5mm × 6.5mm × 0.7mm (geometry 1 (corresponding to PCB substrate)), 0.7mm × 0.7mm × 0.1mm (geometry 2 (corresponding to PCB Cu)), 27.5mm × 6.5mm × 0.03mm (geometry 3 (corresponding to PCB ink)), 27.5mm × 6.5mm × 0.06mm (geometry 4 (corresponding to FPC ink)), 0.7mm × 0.7mm × 0.09mm (geometry 5 (corresponding to solder)), R0.035 mm × 0.065mm (geometry 6 (corresponding to FPC copper)), 0.7mm × 0.47mm × 0.02mm (geometry 7 (corresponding to FPC copper)), and 0.7mm × 0.47mm × 0.02mm (geometry 8 (corresponding to FPC copper)), 27.5mm × 6.5mm × 0.025mm (geometry 9mm (corresponding to FPC copper)), and 0.19 mm × 0.03mm (corresponding to FPC ink (geometry 2 mm)). The angular positions of the 10 geometric bodies are adjusted, so that the geometric bodies are tightly combined up and down.

(2) Establishing a Gaussian heat source model:

the laser brazing process is divided into a heating process and a constant temperature process. First, a higher power density is set to increase the solder joint to a specified target temperature. The power density is then adjusted to substantially stabilize the solder joint temperature at the specified target temperature. The power density of the heat source is increased from 0 to 1.1 multiplied by 10 within 0s-0.5s ⁶ W/m ³ ～1.9×10 ⁶ W/m ³ And kept at 5.0X 10 within 5s to (10 to 50) s ⁵ W/m ³ ～15.0×10 ⁵ W/m ³ From 5.0X 10 in (10-50) s to (60-90) s ⁵ W/m ³ ～15.0×10 ⁵ W/m ³ Reduced to 2.4 × 10 ⁵ W/m ³ ～4.22×10 ⁵ W/m ³ 。

geometric bodies

4, 5 and 10, and setting the normal-pressure heat capacity, density and heat conductivity coefficient of the geometric bodies; click on geometry 9, search the COMSOL database for "PI" and assign to geometry 9. A united body formed by the FPC, the PCB and the solder is set, and solid heat transfer is carried out between the upper part and the lower part of a workpiece (a board soldering structural model) when laser is directly irradiated. And setting boundary conditions of heat radiation and heat convection on the surface of the solder with higher temperature, the lower surface of the FPC and the upper surface of the PCB, wherein the radiation rate of the solder to the environment is 0.2-0.5, the radiation rate of the lower surface of the FPC and the upper surface of the PCB to the environment is 0.8-0.95, and the type of convection heat transfer is set to be natural convection, so that the side surfaces of the PCB and the FPC with lower temperature are approximately thermally insulated.

the way of meshing is chosen to be a free tetrahedral mesh. Study entry, at "step 1: setting the calculation step length to be 1s and the total time to be 60s in the transient state setting, checking whether parameter setting is wrong, and clicking "= calculating" to enter calculation if no parameter setting is wrong. And after the calculation is finished, analyzing and processing the calculated data in the result to obtain a plate brazing temperature field distribution diagram.

In the plate brazing temperature field pattern obtained in this example, as shown in fig. 14A, the maximum surface temperature of the spot weld (shown by the small square in fig. 14A) was 250 ℃ when the brazing time was designated 40s, as shown in fig. 14B, the maximum surface temperature of the spot weld (shown by the small square in fig. 14B) was 245 ℃ when the brazing time was 50s, as shown in fig. 14C, and the maximum surface temperature of the spot weld (shown by the small square in fig. 14C) was 246 ℃ when the brazing time was 60 s.

Example 3

(1) Establishing a plate brazing structure model:

as shown in fig. 12, the specifications of the board soldering structure model 10 were set to 27.5mm × 6.5mm × 0.7mm (geometry 1 (corresponding to PCB substrate)), 0.7mm × 0.7mm × 0.1mm (geometry 2 (corresponding to PCB Cu)), 27.5mm × 6.5mm × 0.03mm (geometry 3 (corresponding to PCB ink)), 27.5mm × 6.5mm × 0.06mm (geometry 4 (corresponding to FPC ink)), 0.7mm × 0.7mm × 0.09mm (geometry 5 (corresponding to solder)), R0.035 mm × 0.065mm (geometry 6 (corresponding to FPC copper)), 0.7mm × 0.47mm × 0.02mm (geometry 7 (corresponding to FPC copper)), and 0.7mm × 0.47mm × 0.02mm (geometry 8 (corresponding to FPC copper)), 27.5mm × 6.5mm × 0.025mm (geometry 9.9 mm (corresponding to FPC copper)), and 0.19 mm × 0.03mm (corresponding to FPC ink (geometry 2.03 mm)). The angular positions of the 10 geometric bodies are adjusted, so that the geometric bodies are tightly combined up and down.

(2) Establishing a Gaussian heat source model:

the laser brazing process is divided into a heating process and a constant temperature process. First, a higher power density is set to increase the solder joint to a specified target temperature. The power density is then adjusted to substantially stabilize the solder joint temperature at the specified target temperature. The power density of the heat source is within 0s-0.5sFrom 0 to 1.1X 10 ⁶ W/m ³ ～1.9×10 ⁶ W/m ³ And kept at 5.0X 10 within 5s to (10 to 50) s ⁵ W/m ³ ～15.0×10 ⁵ W/m ³ From (10-50) s to (60-90) s, by 5.0X 10 ⁵ W/m ³ ～15.0×10 ⁵ W/m ³ Reduced to 2.4 × 10 ⁵ W/m ³ ～4.22×10 ⁵ W/m ³ 。

geometric bodies

the way of meshing is chosen to be a free tetrahedral mesh. Study entry, at "step 1: setting the calculation step length to be 1s and the total time to be 70s in the transient state, checking whether parameter setting is wrong, and clicking "= calculating" to enter calculation if no parameter setting is wrong. And after the calculation is finished, analyzing and processing the calculated data in the result to obtain a plate brazing temperature field distribution diagram.

In the brazing temperature field pattern of the plate obtained in this example, as shown in fig. 15A, the maximum surface temperature of the nugget (shown by the small square in fig. 15A) was set to 300 ℃ when the brazing time was 40s, as shown in fig. 15B, the maximum surface temperature of the nugget (shown by the small square in fig. 15B) was set to 303 ℃ when the brazing time was 50s, as shown in fig. 15C, and the maximum surface temperature of the nugget (shown by the small square in fig. 15C) was set to 302 ℃.

The scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of changes or substitutions within the technical scope of the present application, and all such changes or substitutions are intended to be included within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A method for determining a temperature field distribution for brazing a sheet, comprising:

constructing a plate brazing structure model, wherein the plate brazing structure model is a three-dimensional structure model of a specified plate brazing structure; the designated board soldering structure comprises a circuit board, an electronic component arranged on the circuit board and a solder arranged between the circuit board and the electronic component;

and carrying out laser brazing simulation on the plate brazing structure model to determine the plate brazing temperature field distribution condition of the plate brazing structure model under the conditions of specified target temperature, specified brazing time and specified heat conduction boundary.

2. The method of determining a plate brazing temperature field distribution according to claim 1,

the laser brazing simulation of the plate brazing structure model is carried out to determine the plate brazing temperature field distribution condition of the plate brazing structure model under the conditions of the specified target temperature, the specified brazing time and the specified heat conduction boundary, and the method comprises the following steps:

performing laser heating simulation on the plate brazing structure model by using a specified heat source model so as to simulate a laser brazing process of the specified plate brazing structure, wherein in the laser brazing process, the target heating temperature of each welding spot in the specified plate brazing structure is the specified target temperature;

according to the parts, corresponding to all the components, in the plate brazing structure model, relevant physical parameters and specified heat conduction boundary conditions in the laser brazing process, calculating the temperature of each welding point, corresponding to the specified plate brazing structure, of the plate brazing structure model in the specified brazing time in the laser brazing process, and obtaining the plate brazing temperature field distribution conditions of the plate brazing structure model under the specified target temperature, the specified brazing time and the specified heat conduction boundary conditions;

wherein the relevant physical parameters include: material, gauge, atmospheric heat capacity, density, and thermal conductivity, the specified thermal conduction boundary condition being indicative of the thermal conductivity of the specified plate braze structure to conduct into the environment during the laser brazing process.

3. The method of determining a plate brazing temperature field distribution according to claim 2,

the specified heat source model is a Gaussian surface heat source model.

4. The method of determining a plate brazing temperature field distribution according to claim 2,

the laser heating simulation of the plate brazing structure model by using the specified heat source model to simulate the laser brazing process of the specified plate brazing structure comprises the following steps:

acquiring power densities of heat source items in a first time period and a second time period which are sequential and continuous, wherein in the first time period, the functional density of the heat source items is increased from 0 to a preset threshold value so as to increase the temperature of each welding point in the specified plate brazing structure in the plate brazing structure model to the specified target temperature, and in the second time period, the power density of the heat source items is adjusted to be smaller than the preset threshold value so as to stabilize the temperature of each welding point in the specified plate brazing structure in the plate brazing structure model to the specified target temperature.

5. The plate brazing temperature field distribution determining method according to any one of claims 2 to 4,

the plate soldering structure model is characterized in that relevant physical parameters of parts corresponding to the circuit board and the electronic component in the plate soldering structure model in the laser soldering process are constants, and parts corresponding to the solder in the plate soldering structure model are variables which change along with temperature at least in part of the relevant physical parameters in the laser soldering process.

6. The plate brazing temperature field distribution determining method according to any one of claims 2 to 4,

before calculating the temperatures of the plate brazing structure model corresponding to the respective welding spots in the specified plate brazing structure at the specified brazing time in the laser brazing process according to the relevant physical parameters and the specified heat conduction boundary conditions in the laser brazing process in the parts corresponding to the respective component parts in the plate brazing structure model, the determining method further comprises: acquiring the relevant physical parameter and the specified thermal conduction boundary condition.

7. The method of determining a plate brazing temperature field distribution according to claim 5,

obtaining the specified thermal conduction boundary conditions, including:

and acquiring the heat radiation and heat convection boundary conditions of the board soldering structure model corresponding to the surfaces of the circuit board close to the electronic components, the surfaces of the electronic components close to the circuit board and the surfaces of the solder.

8. The method of determining a plate brazing temperature field distribution according to claim 7,

the thermal emissivity of the surface of the solder is 0.2-0.5, and the thermal emissivity of the surface of the circuit board close to the electronic component and the thermal emissivity of the surface of the electronic component close to the circuit board are both 0.8-0.95.

9. The method of determining a plate brazing temperature field distribution according to any one of claims 2 to 4,

the method for calculating the temperature of each welding point in the specified plate brazing structure of the plate brazing structure model in the specified brazing time in the laser brazing process according to the relevant physical parameters and the specified heat conduction boundary conditions of the parts, corresponding to the components, of the plate brazing structure model in the laser brazing process to obtain the plate brazing temperature field distribution condition of the plate brazing structure model under the specified target temperature, the specified brazing time and the specified heat conduction boundary conditions comprises the following steps:

meshing the plate brazing structure model;

and calculating the temperature of the position corresponding to each grid after the grid division in the specified brazing time.

10. The method of determining a plate brazing temperature field distribution according to claim 9,

the mesh division mode is a free tetrahedron mesh division mode.

11. The method of determining a plate brazing temperature field distribution according to claim 9,

the determination method further comprises: generating a plate brazing temperature field distribution map of the plate brazing structure model under the specified target temperature, the specified brazing time and the specified heat conduction boundary condition according to the plate brazing temperature field distribution of the plate brazing structure model under the specified target temperature, the specified brazing time and the specified heat conduction boundary condition;

in the plate brazing temperature field pattern, the filling color and/or pattern of the plate brazing structure model in the grids corresponding to different temperatures are different.

12. The method for determining a plate brazing temperature field distribution according to any one of claims 1 to 4,

the build plate braze structural model comprising:

constructing a plane layout of the specified plate brazing structure;

and carrying out three-dimensional modeling on the plane layout to obtain the plate brazing structure model.

13. A plate brazing temperature field distribution determining apparatus, comprising: a processor and a memory configured to store computer program instructions;

the computer program instructions, when executed by the processor, cause the board brazing temperature field distribution determining apparatus to implement the board brazing temperature field distribution determining method according to any one of claims 1 to 12.

14. A computer-readable storage medium, characterized in that the computer-readable storage medium stores computer program instructions which, when run on a board brazing temperature field distribution determining apparatus, cause the board brazing temperature field distribution determining apparatus to implement the board brazing temperature field distribution determining method according to any one of claims 1 to 12.