Printing method of printed substrate

Abstract

The invention discloses a printing method of a printed substrate, which comprises the following steps of: dividing a to-be-printed area into a plurality of printing areas according to the distribution of the sizes of element openings on the to-be-printed substrate; the printing method comprises the following steps: selecting a set printing speed, respectively assigning a set printing pressure for different printing areas on a substrate, or respectively assigning a set printing speed and a set printing pressure for different printing areas on the substrate, and sequentially finishing printing of each printing area at the set printing speed and the set printing pressure, and the set printing speed and the set printing pressure take the qualified printing quality as the standard. A plurality of areas are divided according to the distribution of the sizes of the element openings in the substrate, and each area adopts the set printing pressure and / or printing speed, so that stepped adjustment can be realized, all the printing areas can reach the printing quality, meanwhile, the printing efficiency is improved, and the problem that the solder paste amount of large-size opening parts is insufficient in an existing printing method is solved.

Description

Technical Field

[0001] This invention belongs to the field of SMT technology, specifically relating to a printing method for a printed circuit board. Background Technology

[0002] SMT (Surface Mount Technology), also known as surface mount technology, is a board-level assembly technology that mounts surface mount components (SMD) onto printed circuit boards (PCBs). It is currently the most common technology and process in the electronics assembly industry and is the core of modern electronic assembly technology.

[0003] Printed circuit boards (PCBs) are one of the most important components in the electronics industry; almost every electronic device uses PCBs. Solder paste printers are often used when applying solder paste to PCBs. Solder paste, also called solder paste, is a new type of soldering material that emerged with SMT (Surface Mount Technology). It is mainly used in the SMT industry for soldering electronic components such as resistors, capacitors, and ICs (integrated circuits) on PCBs. SMT refers to printing and applying solder paste to the pads of a printed circuit board and accurately placing surface mount components onto the solder paste-coated pads.

[0004] In existing technologies, the squeegee uses the same pressure to print across the entire substrate based on the size distribution of the openings of components on the PCB board. This results in insufficient solder paste filling in the large openings of the printed substrate. To address this insufficient filling in large openings, existing technologies typically reduce the printing speed in these areas to increase solder paste filling. While this improves print quality, it reduces tact time, leading to lower production efficiency and longer production cycles. To solve these technical problems, this invention is proposed. Summary of the Invention

[0005] In view of at least one of the above-mentioned technical problems, the present invention aims to provide a printing method for a printed substrate.

[0006] The technical solution of this invention is:

[0007] The purpose of this invention is to provide a printing method for a printed circuit board, comprising the following steps:

[0008] Based on the distribution of component opening sizes on the substrate to be printed, the area to be printed is divided into multiple printing areas;

[0009] Select a printing speed, and then specify the printing pressure for different printing areas on the substrate, or specify the printing speed and printing pressure for different printing areas on the substrate, and print each printing area sequentially with the set printing speed and printing pressure until all printing areas on the entire substrate are printed. The set printing speed and printing pressure are based on the standard of qualified printing quality.

[0010] Preferably, the set printing speed and set printing pressure can be edited and saved in the control program of the solder paste printer. The control program has multiple selection modules for different types of substrates. Each selection module includes multiple printing adjustment levels. Each printing adjustment level has set printing pressure and printing speed, and at least one of the printing pressure and printing speed is different between different printing adjustment levels.

[0011] Preferably, the printing pressure and printing speed set in any printing adjustment level are adjusted after trial production on the corresponding printing area of ​​the substrate of that type to ensure that the printing quality is qualified.

[0012] Preferably, the printing pressure and printing speed are different between different printing adjustment levels.

[0013] Preferably, the number of printing adjustment levels in the selection module is equal for all types of substrates.

[0014] Preferably, the standard for acceptable printing quality is based on the ratio of the printed solder paste to the opening area of ​​the printed area on the substrate reaching a set standard, and the error of the printed solder paste in the length or width direction of the opening being within a set standard.

[0015] The ratio of the printed solder paste to the opening area of ​​the printed area on the substrate includes the following indicators: lower limit of allowable area error, lower limit warning of allowable area error, upper limit of allowable area error, upper limit warning of allowable area error, and bridging.

[0016] Preferably, for different types of substrates, the lower limit of allowable area error, the warning of the lower limit of allowable area error, the upper limit of allowable area error, the warning of the upper limit of allowable area error and the error in the length or width direction are the same but differ in the bridging index.

[0017] The lower limit of the allowable area error is defined as the area of ​​the printed solder paste being 50% of the opening area. When it is below 50%, the quality is unqualified.

[0018] The lower limit warning for permissible area error is defined as the area of ​​the printed solder paste being 70% of the opening area. A quality warning will be issued when the area of ​​the printed solder paste is 50%-70% of the opening area.

[0019] The upper limit of the allowable area error is defined as the area of ​​the printed solder paste being 180% of the opening area. When the area of ​​the printed solder paste is 180% or more of the opening area, the quality is unqualified.

[0020] The maximum allowable area error warning is defined as the printed solder paste area being 150% of the opening area. A quality warning will be issued when the printed solder paste area is between 150% and 180% of the opening area.

[0021] Bridging is defined as the error between the area of ​​the printed solder paste and the area of ​​the opening being no greater than 0.2mm or 1mm. If the error is greater than 0.2mm or 1mm, the quality is unqualified.

[0022] The error in the length or width direction is defined as not exceeding 0.2mm. When the error is greater than 0.2mm, the quality is unqualified.

[0023] Preferably, the printing speeds set for all printing areas are equal or unequal.

[0024] Preferably, after printing is completed, the process further includes cleaning the substrate and removing the substrate after cleaning.

[0025] Compared with the prior art, the advantages of the present invention are:

[0026] The printing method of the printed circuit board of the present invention divides the substrate into multiple regions according to the distribution of the size of the openings of the components on the substrate. Each region adopts a set printing pressure and / or printing speed, which can achieve step adjustment so that all printing areas achieve printing quality, while improving printing efficiency and solving the problem of insufficient solder paste in large openings in the existing printing methods. Attached Figure Description

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0028] Figure 1 This is a schematic diagram of the production stage of the printing method for a printed substrate according to an embodiment of the present invention.

[0029] Figure 2 This table provides recommendations for printing adjustment levels and corresponding printing pressures and speeds for different types of substrates in the printing method of the printed substrate according to embodiments of the present invention.

[0030] Figure 3 A schematic diagram showing the area division of a mobile phone / camera substrate with dimensions of 250mm*510mm;

[0031] Figure 4 for Figure 3 A schematic diagram of the printing process after the substrate is divided into regions. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0033] See Figures 1 to 4 The printing method for a printed circuit board provided in this embodiment of the invention includes the following steps:

[0034] Based on the distribution of component opening sizes on the substrate to be printed, the area to be printed is divided into multiple printing areas;

[0035] Select a set printing speed, and then specify a set printing pressure for different printing areas on the substrate, or specify a set printing speed and printing pressure for different printing areas on the substrate, and print each printing area sequentially with the set printing speed and printing pressure until all printing areas on the entire substrate are printed. The set printing speed and set printing pressure are based on the standard of qualified printing quality.

[0036] Regarding the substrate to be printed, in the embodiments of the present invention, such as Figure 2As shown, five main types are exemplified: mobile phones / cameras, computers / peripherals, televisions / home appliances, automotive, and unspecified. For mobile phone / camera type substrates, the components in the printing area are mainly 0402 (0.4mm × 0.2mm, hereinafter referred to as 0402), 0603 (0.6mm × 0.3mm, hereinafter referred to as 0603), and 1005 (1.0mm × 0.5mm, hereinafter referred to as 1005), with 0402 accounting for 35%-40%, 0603 accounting for 30%-35%, and 1005 accounting for 20%-25%. For computer / peripheral type substrates, the components in the printing area are mainly 1005 and 1608 (1.6mm × 0.8mm, hereinafter referred to as 1608), with a small amount of 0603, and 1005 accounting for 25%-30%. For TV / home appliance type substrates, the printed components are mainly 1608 and 2012 (2.0mm × 1.2mm, hereinafter referred to as 2012), with a small amount of 1005, of which 1608 accounts for 85-90%. For automotive type substrates, the printed components are mainly 1005 and 3216 (3.2mm × 1.6mm, hereinafter referred to as 3216), with a small amount of 0603, of which 1005 accounts for 25%-28%. Substrates without a specified type refer to substrates other than those for mobile phones / cameras, computers / peripherals, TVs / home appliances, and automotive applications. The idea of ​​this invention is to divide the opening area of ​​the corresponding component on the printed stencil into multiple printing areas along the length of the stencil, based on the opening size of the components on different types of substrates. For example... Figure 4 As shown, the steel mesh is divided into three regions from top to bottom, and the large substrate is also divided into three corresponding regions. Each region on the large substrate corresponds to a different type of substrate component. For example, the components in region 1 are 0402 and 0603, and the corresponding substrate type is mobile phone / camera; the components in region 2 are 1005 and 1608, and the corresponding substrate type is computer / peripheral device; the components in region 3 are 1608 and 2012, and the corresponding substrate type is television / home appliance. Of course, it can also be divided into four regions. The first three regions are the same as above, and there is also a region 4. The components in region 4 are 2012 and above, and the corresponding substrate type is automotive.

[0037] Specifically, such as Figure 3 and Figure 4As shown, the substrate in this embodiment of the invention has multiple openings of different sizes on the area to be printed. Based on the distribution of these openings, the substrate is divided into three regions along its length. Each region has a different component opening size, and therefore uses different printing pressures and / or printing speeds. However, the printing pressure and speed used within the same region are the same. This design ensures that all openings within the same region can be printed using the same printing pressure and speed, guaranteeing acceptable printing quality.

[0038] Regarding the set printing speed and pressure, this application achieves the following: the solder paste printer of this application has a control program with an editable control interface. This interface includes selection modules for printing operations on different types of substrates (as mentioned above, including conventional mobile phone / camera, computer / peripheral, television / home appliance, automotive, and several unspecified substrate categories). Each selection module's interface has multiple printing adjustment level buttons, such as... Figure 2 As shown, each printing adjustment level has a corresponding recommended printing pressure and printing speed. There is no particular limitation on the number of printing adjustment levels, but the number shall not be less than the number of printing areas divided on the printed circuit board. Furthermore, the number of printing adjustment levels may be equal or unequal for different types of substrates. In an exemplary embodiment of the present invention, as... Figure 2 As shown, the number of printing adjustment levels for the selection module is nine for all types of substrates. At least one of the printing pressure and printing speed is different for each printing adjustment level; that is, both can be different, the printing pressure can be different but the printing speed can be the same, or the printing pressure can be the same but the printing speed can be the same. For example, taking a mobile phone / camera substrate type as an example, levels 1, 5, and 9 correspond to the same printing pressure but different printing speeds; levels 1, 4, and 7 correspond to the same printing speed but different printing pressures; and level 1 differs from level 2 in both printing speed and printing pressure. First, there is a data editing stage, which, according to the substrate type, during trial production in the area where the corresponding component openings are located on that type of substrate, is first determined according to production requirements through methods such as... Figure 2The table shown determines the substrate type based on the component aperture coefficient of the printing area. Then, a suggested value for the printing adjustment level corresponding to that substrate type (obtained from production experience) is selected. This suggested value defaults to printing adjustment level 5 for each substrate type. Trial production is then conducted, maintaining a constant printing speed. The printing pressure is adjusted based on the printing quality. Once the required printing quality is achieved, a standardized printing pressure and speed value is obtained. This set of values ​​is set as the printing parameters corresponding to that substrate type and stored in the control program for subsequent production. Each substrate type is processed in the same way to obtain printing parameter data for multiple substrate types. Then, during subsequent substrate printing, only the corresponding printing parameter data for the substrate type needs to be directly called, eliminating the need for trial production and pressure adjustment. It should be noted that... Figure 2 The differences between the different printing adjustment levels for the same type of substrate shown in the table lie in the printing time or the amount of solder paste. In other words, there can be multiple printing parameter data for each type of substrate, and they are not unique. Based on the set printing speed and printing quality, the printing pressure data for that printing area can be obtained.

[0039] The standard for acceptable printing quality is based on the ratio of the printed solder paste to the opening area of ​​the printed area on the substrate reaching the set standard, and the error of the printed solder paste in the length or width direction of the opening being within the set standard. The ratio of the printed solder paste to the opening area of ​​the printed area on the substrate includes the following indicators: lower limit of allowable area error, lower limit warning of allowable area error, upper limit of allowable area error, upper limit warning of allowable area error, and bridging. More specifically, for different types of substrates, the allowable area error lower limit, allowable area error lower limit warning, allowable area error upper limit, allowable area error upper limit warning, and errors in the length or width direction are consistent but differ in bridging indicators. The allowable area error lower limit is defined as the printed solder paste area being 50% of the opening area; if it is below 50%, the quality is unacceptable. The allowable area error lower limit warning is defined as the printed solder paste area being 70% of the opening area; a quality warning will be issued when the printed solder paste area is between 50% and 70% of the opening area. The allowable area error upper limit is defined as the printed solder paste area being 180% of the opening area; if the printed solder paste area is 180% or more of the opening area, the quality is unacceptable. The maximum allowable area error warning is defined as the printed solder paste area being 150% of the opening area. A quality warning will be issued when the printed solder paste area is between 150% and 180% of the opening area. Bridging is defined as the error between the printed solder paste area and the opening area not exceeding 0.2mm or 1mm. If it exceeds 0.2mm or 1mm, the quality is unacceptable. Specifically, when the substrate is a standard component or a QFP / SOP component, bridging is defined as not exceeding 1mm; when the substrate is a BGA / CSP component or a component smaller than 1.0mm*0.5mm, bridging is defined as not exceeding 0.2mm. The error in the length direction (X direction) or width direction (Y direction) is defined as not exceeding 0.2mm. If the error exceeds 0.2mm, the quality is unacceptable. This design can greatly improve the printing quality of the substrate.

[0040] In a preferred embodiment, the substrate printing of this invention further includes, during the production stage, steps of cleaning the substrate and removing the substrate after cleaning, following the completion of printing. The specific steps for cleaning and removing the substrate are not specifically described or limited, as they are existing conventional methods and not innovative aspects of this invention.

[0041] like Figure 1 As shown, the printing method of the printed substrate in this embodiment of the invention, more specifically, involves the printed substrate being printed according to the following... Figure 3 or Figure 4 As shown, the surface is divided into three areas from top to bottom based on the component opening size. Each area has a different opening size, and the stencil is correspondingly divided into three areas from top to bottom. During production, the squeegee moves across the stencil surface from top to bottom to perform printing (of course, printing can also start from bottom to top). Figure 4 (Example: Top-down) First, the selected printing level data (printing speed and printing pressure) is read. The substrate to be printed is then moved into the solder paste printer and positioned. Printing of the areas to be printed begins. During printing, the squeegee starts moving, controlled to execute the following logic: The squeegee starts printing from the topmost printing area (n=1) from top to bottom. The squeegee is controlled to move to the starting position of the first printing area, i.e., ... Figure 4 The upper end of the first printing area is shown, and then the opening size of the element within that printing area is determined from... Figure 2 Select the appropriate substrate type for the printing area from the table shown, then select a printing adjustment level and execute the printing operation with the corresponding printing pressure and speed until the squeegee moves to the end position of the first printing area, i.e. Figure 4 The lower end of the first printing area is shown. If there are other areas, i.e., (n+1) areas, such as the second and / or third and / or fourth printing areas, the control program will replace the printing data of area n with the data corresponding to that printing area (similarly based on the component opening of that printing area from...). Figure 2 The table shown indicates the substrate type. Then, a printing adjustment level is selected, and printing is performed at the set printing pressure and speed. This process is repeated for all printing areas of the entire substrate. Printing is then stopped, and the substrate cleaning process begins. If no other areas are available, printing is stopped directly, and the substrate cleaning process begins. It should be noted that the start and end positions of the areas can also be set in the control program, for example... Figure 3 or Figure 4 The substrate of a certain type (mobile phone / camera) shown is divided into region 1, region 2 and region 3 from top to bottom, that is, along the length of the substrate. The length of region 1 is set to 100mm. When printing begins, the length of all areas to be printed on the substrate and the corresponding printing pressure and printing speed are set in advance on the control panel of the solder paste printer. When region 1 needs to be printed, the data of region 1 is called, including the start position, end position and length, as well as the aforementioned printing data, including printing speed and printing pressure.

[0042] It should be noted that for the same substrate, the printing speed may or may not be the same for different printing areas. For example, a printing speed can be specified for a particular substrate during production, and then different printing speeds can be applied to different printing areas. Figure 2 The table query shown provides a printing pressure. Alternatively, a different printing speed can be set for each printing area. For example, when printing begins, a single printing speed is set for all printing areas, and then adjusted based on the element opening size within each printing area. Figure 2The table shows the printing pressure corresponding to different printing areas. Depending on the distribution of different component opening sizes, the printing pressure for each area may be a range or a fixed value. For example, when the printing speed for all printing areas is set to 75mm / s, if the components in printing area 1 are 0402 and 0603, then the set printing pressure corresponds to 30~35N / mm for a "mobile phone / camera" substrate type; if the components in printing area 2 are 1005 and 1608, the set printing pressure corresponds to 35~45N / mm for a "computer / peripheral device" substrate type; if the components in printing area 3 are 1608 and 2012, the set printing pressure corresponds to 40N / mm for a "television / home appliance" substrate type; and if the components in printing area 4 are 2012 or larger, then the set printing pressure corresponds to 35N / mm for a "vehicle-mounted" substrate type.

[0043] A specific embodiment, as follows Figure 3 or Figure 4 Taking region 1 of the substrate as an example, and the size of the opening in region 1 is larger than that in regions 2 and 3, when using the existing method (the length of region 1 is 100mm, the printing speed is set to 80mm / s according to production needs, and the printing pressure is 30×10), -2 N, To ensure printing quality, the printing pressure is kept constant while the printing speed is changed. Specifically, since the opening size of region 1 is larger than that of regions 2 and 3, the printing speed of this printing region (i.e., printing region 1) should be reduced, more specifically, the printing speed is adjusted to 40mm / s. Testing showed that the printing time was 7.625s. However, after adopting the method of this embodiment, based on the component opening size of printing region 1, the following... Figure 2 The table showing the correspondence between substrate type and printing adjustment level indicates that the substrate type corresponds to mobile phone / camera. Printing adjustment level 3 is used as the printing adjustment level for area 1, meaning the printing speed remains unchanged at 80mm / s, but the printing pressure is increased from the original 30×10. -2 N is adjusted to 40×10 -2 N, the final printing time was tested to be 6.375s, which is 1.25s faster than existing methods, resulting in a 16% improvement in printing efficiency. This efficiency will be significant when printing large batches of substrates. Simultaneously, printing quality has also been improved, specifically addressing the problem of insufficient solder paste at large openings in existing printing methods. In summary, the printing method for the printed circuit board of this invention divides the substrate into multiple regions based on the distribution of component opening sizes. Each region uses a set printing pressure and / or printing speed, allowing for stepped adjustments to ensure consistent printing quality across all printing areas. This improves printing efficiency and solves the problem of insufficient solder paste at large openings in existing printing methods.

[0044] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A printing method for a printed circuit board, characterized in that, Includes the following steps: Based on the distribution of component opening sizes on the substrate to be printed, the area to be printed is divided into multiple printing areas; Select a printing speed, and then specify the printing pressure for different printing areas on the substrate, or specify the printing speed and printing pressure for different printing areas on the substrate, and print each printing area sequentially with the set printing speed and printing pressure until all printing areas on the entire substrate are printed. The set printing speed and printing pressure are based on the standard of qualified printing quality.

2. The printing method according to claim 1, characterized in that, The set printing speed and set printing pressure can be edited and saved in the control program of the solder paste printer. The control program has multiple selection modules for different types of substrates. Each selection module includes multiple printing adjustment levels. Each printing adjustment level has set printing pressure and printing speed, and at least one of the printing pressure and printing speed is different between different printing adjustment levels.

3. The printing method according to claim 2, characterized in that, The printing pressure and printing speed set in any printing adjustment level are adjusted after trial production of the corresponding printing area of ​​the substrate of that type to ensure that the printing quality is qualified.

4. The printing method according to claim 2, characterized in that, The printing pressure and printing speed differ between different printing adjustment levels.

5. The printing method according to claim 1, characterized in that, The standard for acceptable printing quality is based on the ratio of the printed solder paste to the opening area of ​​the printed area on the substrate reaching a set standard, and the error of the printed solder paste in the length or width direction of the opening being within a set standard. The ratio of the printed solder paste to the opening area of ​​the printed area on the substrate includes the following indicators: lower limit of allowable area error, lower limit warning of allowable area error, upper limit of allowable area error, upper limit warning of allowable area error, and bridging.

6. The printing method according to claim 5, characterized in that, For different types of substrates, the allowable area error lower limit, allowable area error lower limit warning, allowable area error upper limit, allowable area error upper limit warning and the error in the length or width direction are the same, but there are differences in the bridging index; The lower limit of the allowable area error is defined as the area of ​​the printed solder paste being 50% of the opening area. When it is below 50%, the quality is unqualified. The lower limit warning for permissible area error is defined as the area of ​​the printed solder paste being 70% of the opening area. A quality warning will be issued when the area of ​​the printed solder paste is 50%-70% of the opening area. The upper limit of the allowable area error is defined as the area of ​​the printed solder paste being 180% of the opening area. When the area of ​​the printed solder paste is 180% or more of the opening area, the quality is unqualified. The maximum allowable area error warning is defined as the printed solder paste area being 150% of the opening area. A quality warning will be issued when the printed solder paste area is between 150% and 180% of the opening area. Bridging is defined as the error between the area of ​​the printed solder paste and the area of ​​the opening being no greater than 0.2mm or 1mm. If the error is greater than 0.2mm or 1mm, the quality is unqualified. The error in the length or width direction is defined as not exceeding 0.2mm. When the error is greater than 0.2mm, the quality is unqualified.

7. The printing method according to claim 1, characterized in that, The printing speeds set for all printing areas may be equal or unequal.

8. The printing method according to any one of claims 1-7, characterized in that, After printing is completed, the process also includes cleaning the substrate and removing the substrate after cleaning.

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