WO2020124949A1

WO2020124949A1 - Method for manufacturing thick copper printed board with no pores in solder resist ink and printed board manufactured thereby

Info

Publication number: WO2020124949A1
Application number: PCT/CN2019/087760
Authority: WO
Inventors: 李健伟; 余同德; 周俊; 吴文跃; 江庆华
Original assignee: 汕头凯星印制板有限公司
Priority date: 2018-12-17
Filing date: 2019-05-21
Publication date: 2020-06-25
Also published as: CN109475046A; CN109475046B

Abstract

The present invention relates to the field of printed circuit board production, and in particular, to a method for manufacturing a thick copper printed board with no pores in a solder resist ink, and a thick copper printed board with no pores in a solder resist ink manufactured thereby. By reasonably formulating primary and secondary solder resist inks, performing primary and secondary printing processes on circuits on two sides of a circuit board, and using pre-curing and post-curing methods in both the primary and secondary printing processes, the present invention can effectively solve the problem of insufficient ink feeding caused by a large height difference between a circuit pattern and a base material of the thick copper board, thereby solving problems such as insufficient resist ink filling for edge wires and the occurrence of residual ink and pores between dense wires. In addition, by printing, baking, exposing, developing and curing both sides of the circuit board at the same time, the present invention can ensure that both sides of the circuit board have the same quality, the quality requirements for the existing thick copper board are satisfied, and the quality is stable, improving the feasibility and convenience of a solder resist process.

Description

Method for manufacturing thick copper printed board with no pores of solder resist ink and printed board

Technical field

The invention relates to the field of printed circuit board production, in particular to a method for manufacturing a solder resist ink thick copper printed board without pores, and a solder resist ink thick copper printed board prepared by the method.

Background technique

Generally, the circuit board with a copper thickness of not less than 105 μm is called a thick copper board. This type of printed circuit board (PCB) has good current carrying capacity and satisfactory heat dissipation performance, and is widely used in automotive electronic equipment and transformers. , Power converters and other equipment, and is increasingly concerned by PCB board-related equipment manufacturers and developers.

In the production of this type of PCB board, due to the thick thickness of the copper plate, the conventional green oil soldering process is directly applied to this type of PCB board, which is easy to cause a large drop between the circuit pattern and the substrate, resulting in insufficient oil and edge soldering. Insufficient filling and the possibility of bubbles remaining between dense lines not only affect the appearance of thick copper plates, but also affect their performance in severe cases.

Summary of the invention

The purpose of the present invention is to overcome the above-mentioned defects in the prior art, and to provide a method for manufacturing a solder mask ink thick copper printed board without pores, to eliminate the quality problems of the finished PCB board such as pinholes, bubbles, oil flow, etc., and to improve the green oil The feasibility of the solder mask process to obtain a thick copper printed board with no pores and excellent solder mask ink appearance.

To achieve the above objectives, the present invention is implemented using the following technical means:

A method for manufacturing thick copper printed board with no pores in solder resist ink is characterized by the following steps:

Step (1) Preparation of solder resist ink: the first solder resist ink is prepared by thoroughly mixing the boiling water: liquid photoresist solder ink at a ratio of 100-150 mL/kg; -The second solder resist ink is prepared by thoroughly mixing at a ratio of -75mL/kg;

Preferably, the first solder resist ink can use a matte color ink as a liquid photoresist solder ink, which has large ink characteristic particles, which is more conducive to the evaporation of bubbles in the ink; and the second solder resist ink can use a bright color ink as a liquid light For solder resist ink, the final appearance is uniformly higher;

Step (2) One-time printing: grinding the circuit board and removing surface impurities, 36T screen printing screen made according to the circuit surface of the circuit board, silkscreening the circuit on both sides of the circuit board with the first solder resist ink, and standing 2 After -3.5h, pre-bake at 70-75°C for 30-55min for pre-curing. After cooling, expose and develop the two sides of the circuit board in alignment. After inspection, the initial temperature is 45-55°C, and then gradually heated up At 20-30 ℃, four sections of baking board are carried out, each baking board time is 30-60min, and post-curing is carried out once;

Step (3) Secondary printing: The 36T screen printing screen made according to the circuit surface of the circuit board is screen printed on both sides of the circuit board after the first curing with the second solder resist ink. After standing for 1-1.5h, Pre-bake at 70-75°C for 30-55min for secondary pre-curing. After cooling, expose and develop the two sides of the circuit board for alignment exposure and development, first at 115-125°C for 25-40min, then 140-160°C The 50-70min two-stage bake board is used for secondary post-cure to completely cure the solder resist ink.

Further: in the step (2), the circuit board grinding speed is 1.8-2.2 m/min.

Further: in the steps (2) and (3), exposure is performed after alignment with an exposure ruler of 9-11 divisions.

Further: in step (2), the development speed is controlled to 1-1.5 m/min; in step (3), the development speed is controlled to 2-3 m/min.

Further: in the step (2), pre-bake at 70-74°C for 30-45min for one pre-curing, and in the step (3) for 70-74°C for 45-55min for second pre-baking Curing.

As an effective solution, in the step (2), when the first solder resist ink performs screen printing on both sides of the circuit board at the same time, the screen printing pressure is 7.5-8.2 kg/cm ² and the screen pitch is 4-6 mm.

As an effective solution, in the step (3), when the second solder resist ink performs screen printing on both sides of the circuit board at the same time, the screen printing pressure is 7.5-8.2 kg/cm ² , and the screen pitch is 4-6 mm.

As an effective solution, in the step (2), 45-55°C is first performed for 40-60min, then 70-85°C for 40-60min, then 90-105°C for 30-40min, and finally Post-curing is carried out once at 115-125°C for 30-40 minutes in a staged bakeboard manner.

Another object of the present invention is to provide a thick copper printed board with no pores in the solder resist ink produced by the above method, no bubbles appear on the surface of the solder resist ink layer of the printed board, and its solvent resistance and physical properties conform to the IPC-SM840 standard And, the thickness of the solder resist ink on the corner of the circuit area of the printed board is> 4 μm, the thickness of the solder resist ink on the surface of the circuit area> 9 μm, the thickness of the solder resist ink on the substrate> 30 μm, when the solder resist ink thickness is greater than the above value, the printed board It can have good acid and alkali resistance, solvent resistance and voltage resistance.

The technical solution provided by the present invention can effectively solve the problems of insufficient oil removal caused by a large gap between the circuit pattern of the thick copper plate and the substrate, insufficient filling of the edge solder mask, and the possibility of residual air bubbles between dense circuits, and the like. Printing, baking, exposure, development, and curing of the baking board can ensure that the quality of both sides of the circuit board is uniform, meet the quality requirements of the existing thick copper plates, and the quality is stable, which improves the feasibility and convenience of the solder mask process.

BRIEF DESCRIPTION

Figure 1 is a schematic diagram of air bubbles on the solder resist surface of a thick copper circuit board using conventional techniques;

FIG. 2 is a high-magnification schematic diagram of the area of FIG. 1A;

3 is a schematic view of the solder mask surface of the dense line area using the technology of Example 1;

FIG. 4 is a high-magnification schematic diagram of the area of FIG. 3A;

5 is a high-magnification schematic diagram of a wide-width circuit solder mask using the technology of Example 2;

6 is a schematic diagram of a wide-width circuit using the technology of Example 2;

7 is a high-magnification schematic diagram of the solder mask surface in the dense line area using the technology of Example 3;

FIG. 8 is a schematic diagram of a wide-width line section in a line dense area using the technology of Embodiment 3. FIG.

detailed description

The present invention will be further described in detail below in conjunction with specific embodiments:

Example 1

In the specific implementation of this embodiment, the following steps are used:

Step (1) Preparation of solder resist ink:

The liquid photoresist soldering ink of the first solder resist ink adopts Haitian green bright ink GK03M3, and is fully mixed with the ratio of boiled water: liquid photoresist soldering ink at 120mL/kg to prepare the first solder resist ink; the second resist The liquid photoresist soldering ink of the soldering ink also uses the bright-colored Haitian green bright ink GK03M3, and the second solder resist ink is prepared by thoroughly mixing the oil-water: liquid photoresist soldering ink at a ratio of 60mL/kg;

Step (2) One-time printing: In order to ensure the copper surface treatment effect, the walking speed is controlled at 2m/min, the brushing and sandblasting are normally turned on, the circuit board is polished, and the surface impurities are removed, according to the wiring and wiring of the circuit board Copper skin, hole position, making 36T white mesh screen printing screen, under the condition of screen printing pressure of 8kg/cm ² and screen printing screen distance of 4mm, screen printing on both sides of the circuit board with the first solder resist ink;

After standing for 3h, pre-bake at 75°C for 50min to perform a pre-curing. After cooling, the two sides of the circuit board are exposed to alignment with an exposure ruler of 9-11 grids, and the development speed is controlled to 1.1m/min for development. In order to avoid some ink from entering the hole, ensure that there is no oil in the hole;

Cool and check the status of the circuit board according to the IPC standard, and do a copper chloride check to check whether the residual ink in the circuit board hole is not developed, excluding the circuit board with obvious air bubbles, or the ink is not developed clean; and due to the relatively thick copper in the circuit area High, which makes the copper edge ink thicker, so it is not possible to directly cure the remaining standard circuit boards at high temperature. In this embodiment, the temperature is 50°C for 50min, 75°C for 50min, and 100°C for 35min At last, carry out the stage bake board at 120℃ for 35min, after one-time curing, after the above steps, complete one printing process;

Step (3) Secondary printing: 36T white mesh screen printing screen made according to the circuit surface of the circuit board, under the condition of screen printing pressure of 8kg/cm ² and screen printing screen distance of 4mm, the second solder resist ink is used once After the post-curing circuit board, both sides of the circuit are screen printed simultaneously; although there is a printing process as a primer, there may still be tiny bubbles between the circuit gaps, so after standing for 1h, pre-bake at 73 ℃ for 45min Secondary pre-curing;

After cooling, the two sides of the circuit board are exposed after alignment with the exposure ruler 9-11 grids, and the development speed is controlled to 2m/min for development. The relatively slow development speed can effectively avoid the problem of undeveloped development;

Cool and check the status of the circuit board according to the IPC standard, and do a copper chloride check to check whether the residual ink in the hole of the circuit board is not developed, to exclude the circuit board with obvious air bubbles or the ink is not developed (usually the above situation does not occur), Then, the circuit board conforming to the standard is firstly subjected to a two-stage bake board at 125 ℃ for 25 minutes and then at 155 ℃ for 60 minutes. Second post-curing is performed to completely solidify the solder resist ink, and the processing process is completed, as shown in Figure 3- 4 Solder resist ink thick copper printed board without pores, this method is more suitable for solder resist screen printing with line spacing above 500μm and copper thickness between 105-140μm.

Example 2

Step (1) Preparation of solder resist ink:

The liquid photoresist soldering ink of the first solder resist ink adopts Haitian green bright ink GK03M3, and is fully mixed with a ratio of 150mL/kg of boiled water: liquid photoresist soldering ink to prepare the first solder resist ink; the second resist The liquid photoresist soldering ink of the soldering ink also uses the bright-colored Haitian green bright ink GK03M3, and the second solder resist ink is prepared by thoroughly mixing the oil-water: liquid photoresist soldering ink at a ratio of 60mL/kg;

Step (2) One-time printing: In order to ensure the copper surface treatment effect, the walking speed is controlled at 2m/min, the brushing and sandblasting are normally turned on, the circuit board is polished, and the surface impurities are removed, according to the wiring and wiring of the circuit board 36TLineMask screen printing screen made of copper skin and hole position, under the condition of screen printing pressure of 8kg/cm ² and screen printing screen distance of 5mm, screen printing on both sides of the circuit board with the first solder resist ink;

After standing for 2h, pre-bake at 74°C for 30min to perform a pre-curing. After cooling, the two sides of the circuit board are exposed to alignment with the exposure ruler 9-11 grid, and the development speed is controlled to 1.1m/min for development. In order to avoid some ink from entering the hole, ensure that there is no oil in the hole;

Cool and check the status of the circuit board according to the IPC standard, and do copper chloride to check whether the residual ink in the hole of the circuit board is not developed, to exclude the circuit board with obvious bubbles, or the ink is not developed clean; and because the copper thickness of the circuit area is high, In addition, the copper edge ink is thicker, so it is not possible to directly cure the remaining standard circuit boards at high temperature. In this embodiment, the temperature is 55°C for 60min, then 85°C for 55min, and then 105°C for 45min. Carry out a post-curing process at 125°C for 30 minutes in a staged baking sheet, after the above steps, complete a printing process;

Step (3) Secondary printing: 36T white mesh screen printing screen made according to the circuit surface of the circuit board, under the condition of screen printing pressure of 8kg/cm ² and screen printing screen distance of 5mm, the second solder resist ink is used once After the post-curing circuit board, both sides of the circuit are screen printed at the same time; although there is a printing process as a primer, there may still be tiny bubbles between the circuit gaps, so after standing for 1h, pre-bake at 74℃ for 45min Secondary pre-curing;

Cool and check the status of the circuit board according to the IPC standard, and do copper chloride to check whether the residual ink in the hole of the circuit board is not developed, excluding bubbles with obvious bubbles, or the circuit board is not developed with ink (usually the above situation does not occur), and then check The circuit board conforming to the standard is firstly subjected to two-stage baking at 125 ℃ for 25 minutes and then at 155 ℃ for 60 minutes. After two times of post-curing, the solder resist ink is completely cured, and the processing process is completed. The thick copper printed board with no pores in the soldering ink has a thickness of 44.73μm in the corner solder mask of the circuit area, a thickness of 76.02μm in the solder mask ink on the surface of the circuit area, and a thickness of 122.8μm in the substrate solder mask ink. This method is more suitable for The screen pitch width is 300-500μm, and the copper thickness is 140-175μm.

Example 3

Step (1) Preparation of solder resist ink:

The liquid photoresist soldering ink of the first solder resist ink adopts Rongda MG6 matte color ink, and fully mixes with boiled water: liquid photoresist soldering ink at a ratio of 100mL/kg to prepare the first solder resist ink; The liquid photoresist soldering ink of the second solder resist ink adopts bright-colored Haitian green bright ink GK03M3, and the second solder resist ink is prepared by thoroughly mixing oil water: liquid photo solder resist ink at a ratio of 60mL/kg;

Step (2) One-time printing: In order to ensure the copper surface treatment effect, the walking speed is 1.8m/min according to the lower limit of the process requirements. The brushing and sandblasting are normally turned on. The circuit board is polished and the surface impurities are removed. The 36T screen mesh screen made by the wiring and hole positions of the board is screen printed on both sides of the circuit board with the first solder resist ink under the condition that the screen printing pressure is 8kg/cm ² and the screen spacing is 5mm;

After standing for 3h, pre-bake at 73°C for 45min to perform a pre-curing. After cooling, the two sides of the circuit board are exposed to alignment with exposure ruler 9-11 grids, and the development speed is controlled to 1m/min for development. Avoid part of the ink into the hole and ensure that there is no oil in the hole;

Cool and check the status of the circuit board according to the IPC standard, and do copper chloride to check whether the residual ink in the hole of the circuit board is not developed, to exclude the circuit board with obvious bubbles, or the ink is not developed clean; and because the copper thickness of the circuit area is high, In addition, the copper edge ink is thicker, so it is not possible to directly cure the remaining standard circuit boards at high temperature. In this embodiment, the temperature is 50 ℃ for 60 minutes, then 80 ℃ for 60 minutes, then 100 ℃ for 30 minutes, and finally Carry out a post-curing process at 120°C for 30 minutes in a staged baking sheet, after the above steps, complete a printing process;

Step (3) Secondary printing: 36T white mesh screen printing screen made according to the circuit surface of the circuit board, under the condition of screen printing pressure of 8kg/cm ² and screen printing screen distance of 5mm, the second solder resist ink is used once After the post-curing circuit board, both sides of the circuit are screen printed simultaneously; although there is a printing process as a primer, there may still be tiny bubbles between the circuit gaps, so after standing for 1h, pre-bake at 73 ℃ for 45min Secondary pre-curing;

After cooling, the two sides of the circuit board are exposed with the exposure ruler 9-11 grids, and the development speed is controlled to 2.5m/min for development. Based on the above development speed, it can effectively avoid the problem of undeveloped development and at the same time have production. Increased efficiency;

Cool and check the status of the circuit board according to the IPC standard, and do copper chloride to check whether the residual ink in the hole of the circuit board is not developed, excluding bubbles with obvious bubbles, or the circuit board is not developed with ink (usually the above situation does not occur), and then check The circuit board conforming to the standard is firstly carried out at 115-125°C for 25-40min, and then at 140-160°C for 50-70min two-stage bake board. After secondary curing, the solder resist ink is fully cured and the processing process is completed. The thick copper printed board with no pores in the solder mask ink as shown in Figure 7-8 was prepared. The thickness of the solder mask ink at the corners of the circuit area was 68.85 μm, the thickness of the solder mask ink on the surface of the circuit area was 55.55 μm, and the thickness of the solder mask ink on the substrate was 233.91μm, this method can be widely applied to screen printing that is suitable for unequal line spacing width and dense wiring, with a thickness of 175-350μm thick copper.

As shown in Figure 3-8, the finished products of Examples 1-3 are subjected to high magnification verification, which is directly applied to the solder mask of thick copper circuit boards (ie, as shown in Figure 1-2) compared to the conventional technology. There is no uneven board thickness and bubbles in the board, and there are no problems such as insufficient solder mask filling between the pattern of the thick copper plate and the edge of the substrate, and the possibility of blistering between dense circuits.

The basic principles and main features of the present invention and the advantages of the present invention have been shown and described above. Those skilled in the art should understand that the present invention is not limited by the above-mentioned embodiments. The above-mentioned embodiments and the description only describe the invention. Principle, without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, these changes and improvements fall within the scope of the claimed invention, and the scope of the claimed invention is defined by the appended rights Definition of requirements and their equivalents.

Claims

A method for manufacturing thick copper printed board with no pores in solder resist ink is characterized by the following steps:

Step (1) Preparation of solder resist ink: the first solder resist ink is prepared by thoroughly mixing the boiling water: liquid photoresist solder ink at a ratio of 100-150 mL/kg; -The second solder resist ink is prepared by thoroughly mixing at a ratio of -75mL/kg;

Step (2) One-time printing: grinding the circuit board and removing surface impurities, 36T screen printing screen made according to the circuit surface of the circuit board, silkscreening the circuit on both sides of the circuit board with the first solder resist ink, and standing 2 After -3.5h, pre-bake at 70-75℃ for 30-55min for pre-curing. After cooling, expose and develop the two sides of the circuit board for exposure and development and inspection, with an initial temperature of 45-55℃, and then gradually increase the temperature At 20-30 ℃, four sections of baking board are carried out, each baking board time is 30-60min, and post-curing is carried out once;

Step (3) Secondary printing: The 36T screen printing screen made according to the circuit surface of the circuit board is screen printed on both sides of the circuit board after the first curing with the second solder resist ink. After standing for 1-1.5h, Pre-bake at 70-75℃ for 30-55min for secondary pre-curing. After cooling, expose and develop the two sides of the circuit board in alignment. After cooling and inspection, carry out 25-40min at 115-125℃ first, then 140- Carry out two stages of 50-70min bakeboards at 160°C for secondary post-cure to completely cure the solder resist ink.
The method for manufacturing a thick copper printed board with no pores of solder resist ink according to claim 1, wherein in the step (2), the speed of the circuit board grinding board is 1.8-2.2m/min.
The method for manufacturing a thick copper printed board with no pores of solder resist ink according to claim 1, characterized in that: in the steps (2) and (3), the exposure ruler is used for alignment of 9-11 grids After exposure.
The method for manufacturing a thick copper printed board with no pores of solder resist ink as claimed in claim 3, characterized in that: the development speed in the step (2) is controlled to 1-1.5m/min; in the step (3) , The development speed is controlled to 2-3m/min.
The manufacturing method of thick copper printed board with no pores of solder resist ink as claimed in claim 1, characterized in that: in said step (2), pre-baking is carried out at 70-74°C for 30-45min for pre-curing In the step (3), pre-bake at 70-74°C for 45-55min for secondary pre-curing.
A solder resist ink thick copper printed board with no pores according to any one of claims 1-5, characterized in that: in the step (2), the first solder resist ink is on both sides of the circuit board When performing screen printing, the screen printing pressure is 7.5-8.2 kg/cm 2 and the screen pitch is 4-6 mm.
A solder resist ink thick copper printed board without pores according to any one of claims 1 to 5, characterized in that: in said step (3), the second solder resist ink is simultaneously applied to both sides of the circuit board When performing screen printing, the screen printing pressure is 7.5-8.2 kg/cm 2 and the screen pitch is 4-6 mm.
A solder resist ink thick copper printed board with no pores according to any one of claims 1-5, characterized in that: in said step (2), it is first performed at 45-55°C for 40-60min, Then at 70-85 ℃ for 40-60min, then at 90-105 ℃ for 30-40min, and finally at 115-125 ℃ for 30-40min to carry out a staged baking plate, and post-cure.
A thick copper printed board with no pores and solder resist ink produced by the method according to any one of claims 1-8.
The thick copper printed board with no pores of solder resist ink according to claim 9, characterized in that: the thickness of the solder resist ink at the corner of the circuit area of the printed board is greater than 4 μm, and the thickness of the solder resist ink on the surface of the circuit area is greater than 9 μm. The thickness of the material solder resist ink thickness> 30μm.