Method to reduce the ink thickness of solder mask plug hole in SMD area

Abstract

The present invention discloses a method for reducing the ink thickness of solder mask plugging holes in an SMD area, comprising: providing a semi-finished PCB, the semi-finished PCB having a TOP surface, a BOT surface and a plurality of plugging holes, and the BOT surface is used as the plugging hole surface; providing an ink printer, an air guide pad and an aluminum sheet screen for making ink plugging holes; placing the semi-finished PCB with its TOP surface facing the air guide pad and the BOT surface facing the aluminum sheet screen between the air guide pad and the aluminum sheet screen, and then using an ink printer to make ink plugging holes for the semi-finished PCB; after the ink plugging holes are made, first print a solder mask ink layer on the BOT surface of the semi-finished PCB, and then use a nail bed to print a solder mask ink layer on the BOT surface and TOP surface of the semi-finished PCB; that is, completing the solder mask ink printing operation of the PCB board. The method provided by the present invention is simple and easy to operate, and can not only effectively optimize the ink thickness of the solder mask plugging holes in the SMD area, but also does not add additional processing procedures and cost increases, which is conducive to production implementation.

Description

Technical Field

[0001] The invention relates to the technical field of PCB board manufacturing, and in particular to a method for reducing the ink thickness of solder mask plug holes in an SMD area. Background Art

[0002] At present, during the solder mask plugging and printing process in the PCB board manufacturing process, due to the accumulation of ink at the plugging hole mouth and the pressure of the silk screen nail bed printing, the solder mask dense hole plugging area is prone to produce plugging ink connected holes, oil accumulation and other undesirable phenomena, which will cause the customer's mounting on the top of the steel mesh, resulting in many problems such as excessive tin, SPI alarm, and tin beads after reflow soldering. In particular, the current industry's control of the ink thickness at the solder mask printing plugging position to 50um is the limit, and it is impossible to achieve the customer's ideal ink thickness of ≤40um. Therefore, effectively reducing the ink thickness of the solder mask plugging position in the SMD area has become a technical problem that the PCB board manufacturing industry urgently needs to solve.

[0003] In view of this, the present invention is proposed. Summary of the invention

[0004] In order to overcome the above-mentioned defects, the present invention provides a method for reducing the ink thickness of the solder mask plug hole in the SMD area. The method is simple and easy to operate. It can not only effectively optimize the ink thickness of the solder mask plug hole in the SMD area, but also does not add any additional processing flow or cost increase, which is conducive to production implementation.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a method for reducing the ink thickness of the solder mask plug hole in the SMD area, comprising the following steps:

[0006] S1: providing a semi-finished PCB, wherein the semi-finished PCB has a TOP surface and a BOT surface arranged opposite to the TOP surface, and the semi-finished PCB is further provided with a plurality of plug holes respectively penetrating the TOP surface and the BOT surface, wherein the plurality of plug holes are used for filling ink;

[0007] S2: Provide processing equipment and auxiliary jigs for making ink plug holes; wherein, the processing equipment includes an ink printer, and the auxiliary jigs include an air guide pad and an aluminum screen, the air guide pad is used to support the semi-finished PCB, and the aluminum screen is used to press on the BOT surface of the semi-finished PCB, that is, the BOT surface of the semi-finished PCB is used as the plug hole surface;

[0008] S3: placing the semi-finished PCB between the air guide pad and the aluminum screen with its TOP surface facing the air guide pad and its BOT surface facing the aluminum screen, and then performing ink plugging on the semi-finished PCB using the ink printer;

[0009] S4: After the ink plugging hole is completed, a solder resist ink layer is first printed on the BOT surface of the semi-finished PCB, and then a solder resist ink layer is printed on the BOT surface and TOP surface of the semi-finished PCB using a nail bed; that is, the solder resist ink printing operation of the PCB board is completed.

[0010] As a further improvement of the present invention, the air guide pad is provided with a plurality of air guide holes, and the plurality of air guide holes are all through-hole structures, and can be respectively connected to the plurality of plug holes on the PCB semi-finished product in a one-to-one correspondence;

[0011] A plurality of lower oil holes are arranged on the aluminum sheet mesh, and the plurality of lower oil holes are also through-hole structures, and can be respectively connected with the plurality of plug holes one by one; in addition, when making the lower oil holes, the aperture data of the aluminum sheet is compensated, that is: the drilling coefficient in the aperture data of the aluminum sheet is controlled to be reduced by 2 ten-thousandths, so that the plurality of lower oil holes can be respectively arranged concentrically with the plurality of plug holes.

[0012] As a further improvement of the present invention, when the semi-finished PCB is placed on the air guide pad, the downward projections of the plurality of plug holes fall into the plurality of air guide holes in a one-to-one correspondence.

[0013] As a further improvement of the present invention, when the ink printer performs ink plugging on the semi-finished PCB product, the processing parameters of the ink printer are controlled as follows: scraper angle 0-25°; plugging speed 2-4 m / min; plugging pressure 4-8 kg / cm 2 .

[0014] As a further improvement of the present invention, the processing parameters of the ink printing machine are controlled as follows: scraper angle 25°; plugging speed 2m / min; plugging pressure 8kg / cm 2 ;

[0015] Alternatively, the processing parameters of the ink printer are controlled as follows: scraper angle 15°; plugging speed 3m / min; plugging pressure 8kg / cm 2 .

[0016] As a further improvement of the present invention, the solder resist ink layer is printed on the BOT surface and the TOP surface of the semi-finished PCB by using screen printing technology, and the T number of the mesh used in the screen printing is 40-43T.

[0017] The beneficial effects of the present invention are: 1) Compared with the prior art, the present invention can effectively optimize the ink thickness of the solder mask plug hole position in the SMD area by adjusting the plug hole surface, the solder mask ink printing sequence, the number of T mesh of screen printing and other technical factors, so that the ink thickness can reach ≤40um, which well meets the needs of customers and the market. 2) The present invention optimizes and adjusts the drilling coefficient of the aluminum sheet screen and optimizes the processing parameters of the ink printer to achieve that the several lower oil holes on the aluminum sheet screen are always arranged concentrically with the several plug holes during the entire ink plug hole production process, thereby effectively avoiding the many defects caused by the offset of the lower oil holes and the plug holes in the prior art, and well ensuring that the ink filling in the plug hole reaches the ideal fullness, thereby well improving and enhancing the ink plug hole yield of the PCB board, which also provides support and guarantee for the precise printing of solder mask ink. 3) The ink plug hole and solder mask ink printing method provided by the present invention are simple and easy to operate, without adding additional processing procedures and cost increases, which is conducive to production implementation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A flow chart of the method for reducing the ink thickness of the solder mask plug hole in the SMD area according to the present invention;

[0019] Figure 2 It is a schematic cross-sectional view of the assembly structure when the PCB semi-finished product is placed between the air guide pad and the aluminum sheet mesh.

[0020] Combined with the attached drawings, the following description is given:

[0021] 1. PCB semi-finished product; 10. Plug hole; 2. Air guide pad; 20. Air guide hole;

[0022] 3. Aluminum mesh; 30. Oil hole. DETAILED DESCRIPTION

[0023] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0024] Embodiment 1:

[0025] Please refer to the attached Figure 1 As shown, it is a flow chart of the method for reducing the ink thickness of the solder resist plug hole in the SMD area according to the present invention.

[0026] The present invention provides a method for reducing the ink thickness of the solder mask plug hole in the SMD area, comprising the following steps:

[0027] S1: Provide a PCB semi-finished product 1, wherein the PCB semi-finished product 1 has a TOP surface and a BOT surface arranged opposite to the TOP surface, and a plurality of plug holes 10 respectively penetrating the TOP surface and the BOT surface are formed on the PCB semi-finished product 1, and the plurality of plug holes 10 are used for filling ink.

[0028] In addition, the above-mentioned semi-finished PCB products refer to PCB boards that have completed circuit production and copper plating in via holes. They are semi-finished products in the PCB board processing flow, so they are called PCB semi-finished products.

[0029] S2: Provide processing equipment and auxiliary jigs for making ink plugging holes; wherein, the processing equipment includes an ink printing machine, and the auxiliary jigs include an air guide pad 2 and an aluminum mesh 3, the air guide pad 2 is used to support the PCB semi-finished product 1, and the aluminum mesh 3 is used to press on the BOT surface of the PCB semi-finished product 1, that is, the BOT surface of the PCB semi-finished product 1 is used as the plugging surface, so as to avoid ink accumulation and oil accumulation in the holes at the bottom of the aluminum mesh.

[0030] The specific structures of the ink printer, the air guide pad 2 and the aluminum screen 3 are described below:

[0031] First of all, the ink printing machine used in this patent comes from conventional equipment on the market and is not the focus of protection of this patent, so it will not be described in detail here.

[0032] Secondly, the air guide pad 2 is made of a FR-4 substrate with a copper clad layer removed, and a plurality of air guide holes 20 are arranged on the air guide pad 2. The plurality of air guide holes 20 are through-hole structures and can be connected to the plurality of plug holes 10 on the PCB semi-finished product 1 one by one, that is, the layout of the plurality of air guide holes 20 is consistent with the layout of the plurality of plug holes 10; in addition, when the PCB semi-finished product 1 is placed on the air guide pad 2, the downward projections of the plurality of plug holes 10 fall into the plurality of air guide holes 20 one by one (see the attached figure). Figure 2 Generally, the diameter of the air guide hole 20 is larger than that of the plug hole 10 by more than 2 mm, so that when the ink plugging operation is performed, the air guide hole 20 plays a role in ventilation and preventing the ink from getting on the machine, which is beneficial to the plugging quality.

[0033] Again, the aluminum sheet mesh 3 is provided with a plurality of lower oil holes 30, and the plurality of lower oil holes 30 are also through-hole structures, and can be respectively connected to the plurality of plug holes 10 in a one-to-one correspondence (see the attached Figure 2as shown); in addition, when making the lower oil hole 30, the aluminum sheet aperture data will be compensated, that is: the drilling coefficient in the aluminum sheet aperture data is controlled to be reduced by two ten-thousandths (such as: compared with the currently commonly used drilling coefficient of 1, the drilling coefficient is optimized to 0.9998 in this patent); in this way, during the ink plug hole production process, the lower oil hole 30 obtained based on the optimization of the aluminum sheet aperture data can well cope with the aluminum sheet mesh offset phenomenon caused by the overall deformation and expansion of the aluminum sheet mesh 3, and then a plurality of the lower oil holes 30 can be respectively arranged concentrically with a plurality of the plug holes 10, thereby effectively solving the problem of relative offset of the plug holes.

[0034] In addition, when manufacturing the aluminum sheet mesh 3, the present patent will frequently replace the pulp board used as the supporting member / reinforcement member of the aluminum sheet mesh 3 to avoid the unevenness caused by the repeated use of the pulp board, which will have an adverse effect on the flatness of the aluminum sheet mesh 3. That is, by frequently replacing the pulp board, the flatness of the aluminum sheet mesh 3 can be well ensured, thereby avoiding clogging of holes, oil accumulation and ink accumulation.

[0035] S3: The PCB semi-finished product 1 is placed between the air guide pad 2 and the aluminum sheet mesh 3 with its TOP surface facing the air guide pad 2 and its BOT surface facing the aluminum sheet mesh 3, and then the ink printer is used to perform ink plugging on the PCB semi-finished product 1, and the processing parameters of the ink printer are controlled as follows: scraper angle 0-25°; plugging speed 2-4m / min; plugging pressure 4-8kg / cm 2 .

[0036] Further preferably, the processing parameters of the ink printing machine can be preferably controlled as follows: scraper angle 25°; plugging speed 2m / min; plugging pressure 8kg / cm 2 Through testing on semi-finished PCB products, it was found that under this processing parameter, the ink filling fullness in the plug hole can reach 90%, which well meets customer requirements.

[0037] Alternatively, the processing parameters of the ink printer can be preferably controlled as follows: scraper angle 15°; plugging speed 3m / min; plugging pressure 8kg / cm 2 Through testing on semi-finished PCB products, it was found that under this processing parameter, the ink filling fullness in the plug hole could reach 83%, which also met the customer's requirements very well.

[0038] In combination with the above steps S2 and S3, this patent optimizes and adjusts the drilling coefficient of the aluminum sheet mesh and optimizes the processing parameters of the ink printer to achieve that the multiple oil holes on the aluminum sheet mesh are always arranged concentrically with the multiple plug holes during the entire ink plug hole production process, thereby effectively avoiding many defects in the prior art caused by the offset of the oil holes and the plug holes, and ensuring that the ink filling in the plug holes reaches the ideal fullness, thereby greatly improving and enhancing the ink plug hole yield of the PCB board, which also provides support and guarantee for the subsequent precise printing of solder mask ink.

[0039] S4: After the ink plugging hole is completed, first print the solder resist ink layer on the BOT surface of the semi-finished PCB 1, and then use the nail bed to print the solder resist ink layer on the BOT surface and TOP surface of the semi-finished PCB 1; that is, the solder resist ink printing operation of the PCB board is completed. By setting the BOT surface as the first printing surface, setting the TOP surface as the second printing surface, and using the nail bed printing on the TOP surface (that is, the TOP surface is used as the printing knife surface), the ink that appears at the plug hole position can be scraped flat.

[0040] Further preferably, the first printing of the BOT surface of the semi-finished PCB 1 is performed on the air guide pad 2 , that is, the ink plugging and the first printing operation of the BOT surface of the semi-finished PCB 1 are completed on the air guide pad 2 .

[0041] Further preferably, when the BOT surface and TOP surface of the PCB semi-finished product 1 are printed using the nail bed and the ink printer (usually, 2 to 3 ink printers are generally configured when performing solder mask ink plugging and printing operations), the procedure is performed according to "printing the BOT surface first, then printing the TOP surface".

[0042] Further preferably, the present patent adopts screen printing technology to print the solder mask ink layer on the BOT surface and TOP surface of the semi-finished PCB product 1, and the T number of the mesh used in screen printing is 40 to 43T. The T number of the mesh refers to the number of mesh holes within 1 square inch. For example, 40T means that there are 40 mesh holes in an area of ​​1 square inch. The higher the T number, the finer the mesh and the more mesh holes; conversely, the lower the T number, the coarser the mesh and the larger the mesh holes. By optimizing the T number of the mesh, the present patent can effectively reduce the thickness of the ink during printing to avoid oil accumulation and ink plugging.

[0043] In summary, compared with the prior art, the present invention can effectively optimize the ink thickness of the solder mask plug hole position in the SMD area by adjusting the plug hole surface, the solder mask ink printing sequence, the number of T mesh of screen printing and other technical factors, so that the ink thickness can reach ≤40um, which well meets customer and market needs. In addition, the present invention also optimizes and adjusts the drilling coefficient of the aluminum sheet screen and optimizes the processing parameters of the ink printer to achieve that the several lower oil holes on the aluminum sheet screen are always arranged concentrically with the several plug holes during the entire ink plug hole production process, thereby effectively avoiding the many defects caused by the offset of the lower oil holes and the plug holes in the prior art, and well ensuring that the ink filling in the plug hole reaches the ideal fullness, thereby well improving and enhancing the ink plug hole yield of the PCB board, which also provides support and guarantee for the precise printing of solder mask ink. In addition, the ink plug hole and solder mask ink printing method provided by the present invention are simple and easy to operate, without adding additional processing procedures and cost increases, which is conducive to production implementation.

[0044] Many specific details are described in the above description to facilitate a full understanding of the present invention. However, the above description is only a preferred embodiment of the present invention. The present invention can be implemented in many other ways different from those described herein, so the present invention is not limited to the specific implementation disclosed above. At the same time, any person familiar with the art can make many possible changes and modifications to the technical solution of the present invention using the methods and technical contents disclosed above without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

Claims

1. A method for reducing the ink thickness of solder mask plug holes in SMD areas, characterized in that: The steps include: S1: providing a PCB semi-finished product (1), wherein the PCB semi-finished product (1) comprises a TOP surface and a BOT surface arranged opposite to the TOP surface, and the PCB semi-finished product (1) is further provided with a plurality of plug holes (10) respectively penetrating the TOP surface and the BOT surface, wherein the plurality of plug holes (10) are used for filling ink; S2: Processing equipment and auxiliary jigs for making ink plug holes are provided; wherein the processing equipment comprises an ink printing machine, and the auxiliary jigs comprise an air guide pad (2) and an aluminum sheet screen (3); the air guide pad (2) is used to support the PCB semi-finished product (1); a plurality of air guide holes (20) are provided on the air guide pad (2); the plurality of air guide holes (20) are all through-hole structures and can be respectively connected to a plurality of plug holes (10) on the PCB semi-finished product (1) in a one-to-one correspondence; the aluminum sheet screen (3) is used to be pressed onto the BOT surface of the PCB semi-finished product (1), that is, the BOT surface of the PCB semi-finished product (1) is used as the plug hole surface; the aluminum sheet screen (3) ) is provided with a plurality of lower oil holes (30), and the plurality of lower oil holes (30) are also through-hole structures and can be connected to the plurality of plug holes (10) in a one-to-one correspondence; in addition, when manufacturing the lower oil holes (30), the aluminum sheet aperture data is compensated, that is: the drilling coefficient in the aluminum sheet aperture data is controlled to be 0.9998, so that the manufactured lower oil holes (30) can cope with the displacement phenomenon of the aluminum sheet mesh (3) caused by the overall deformation and expansion of the aluminum sheet mesh (3), thereby enabling the plurality of lower oil holes (30) to be arranged concentrically with the plurality of plug holes (10); when manufacturing the aluminum sheet mesh (3), the pulp board of the aluminum sheet mesh (3) is frequently replaced; S3: placing the PCB semi-finished product (1) between the air guide pad (2) and the aluminum sheet mesh (3) with its TOP surface facing the air guide pad (2) and its BOT surface facing the aluminum sheet mesh (3), and then performing ink plugging on the PCB semi-finished product (1) using the ink printer; S4: After the above-mentioned ink plugging holes are completed, a solder resist ink layer is first printed on the BOT surface of the PCB semi-finished product (1), that is, the first printing of the BOT surface of the PCB semi-finished product (1) is performed on the air guide pad (2); then, a nail bed and the ink printer using screen printing technology are used to print the solder resist ink layer on the BOT surface and TOP surface of the PCB semi-finished product (1) according to the steps of first printing the BOT surface and then printing the TOP surface, and the T number of the mesh used in the screen printing is 40 to 43T; that is, the solder resist ink printing operation of the PCB board is completed, and the solder resist plug hole ink thickness is ≤40um.

2. The method for reducing ink thickness of solder mask plug holes in SMD area according to claim 1, characterized in that: When the PCB semi-finished product (1) is placed on the air guide pad (2), the downward projections of the plurality of plug holes (10) fall into the plurality of air guide holes (20) one by one.

3. The method for reducing ink thickness of solder mask plug holes in SMD areas according to claim 1, characterized in that: When the ink printer performs ink plugging on the PCB semi-finished product (1), the processing parameters of the ink printer are controlled as follows: scraper angle 0-25°; plugging speed 2-4 m / min; plugging pressure 4-8 kg / cm 2 .

4. The method for reducing ink thickness of solder mask plug holes in SMD areas according to claim 3, characterized in that: The processing parameters of the ink printing machine are controlled as follows: scraper angle 25°; plugging speed 2m / min; plugging pressure 8kg / cm 2 ; Alternatively, the processing parameters of the ink printer are controlled as follows: scraper angle 15°; plugging speed 3m / min; plugging pressure 8kg / cm 2 .

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