A method for manufacturing a PCB half-plugged hole

Abstract

The application discloses a kind of production methods of PCB solder mask half plug hole, comprising the following steps: using volcanic ash grinder to carry out surface roughening pretreatment to PCB;C face plug hole, adopt plug hole after leveling, or secondary plug hole process, the ink used is 85% high viscosity plug hole ink of solid content;S face oil and C face oil are printed in turn, pre-baking: the air draft speed of oven is greater than or equal to 10m / s, pre-baking time is 45min;Exposure and development: exposure energy is 500mJ;When developing, the C face of PCB is placed upwards, and development pressure is set to 1.5 kg / cm², speed is 4.0 m / min;When washing, the water temperature of washing tank after development is controlled to be 18-27 DEG C, hot air blow drying pressure after washing is less than or equal to 2kpa;High temperature curing.The production method of PCB solder mask half plug hole of the application, through the process parameter optimization and process control of systematization, effectively solve the quality problems such as light transmission, pore ink accumulation and oil spill of 0.5mm and above large aperture solder mask half plug hole.

Description

Technical Field

[0001] This invention relates to the field of circuit board manufacturing technology, specifically to a method for manufacturing a PCB solder mask half-plug hole. Background Technology

[0002] In PCB manufacturing, solder mask filling is divided into full filling and partial filling. Partial filling requires one side to be completely filled to ensure reliability and sealing, while the other side is left open to ensure solderability. Its fullness is usually required to be controlled between 30% and 90%.

[0003] Currently, the industry standard for semi-plugging solder resist ink in conventional processes typically has a maximum aperture diameter of 0.4mm. When the aperture increases to 0.5mm, traditional processes face significant challenges, primarily due to the following issues:

[0004] 1. Poor light transmission: Due to the corrosive effect of the developing solution, the larger the pore size, the more difficult it is to ensure the fullness of the pore filling, which can easily lead to light transmission due to insufficient fullness (less than 30%).

[0005] 2. Ink accumulation at the orifice: To ensure the fullness of the plugging of small orifices with a high aspect ratio (such as 0.2mm), a high plugging pressure is required. However, this will cause a large amount of ink to overflow from the orifice of large-diameter semi-plugged orifices (such as 0.5mm), forming ink accumulation at the orifice and affecting the welding.

[0006] 3. Oil seepage problem: During the development process, improper control of ink solvent content, water washing temperature and drying pressure can easily cause incompletely cured ink to flow out of the holes, resulting in oil seepage at the hole openings.

[0007] Therefore, traditional half-hole manufacturing processes cannot meet the stringent requirements of high-end electronic products (such as game console motherboards) for the solderability and oil thickness of half-holes.

[0008] Therefore, it is necessary to provide a new process to solve the problems of light transmission, ink accumulation, and oil seepage in large-diameter solder resist semi-plugged holes. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to provide a method for manufacturing solder mask semi-plugs on PCBs. Through systematic optimization of process parameters and process control, the method effectively solves quality problems such as light transmission, ink accumulation at the orifice, and oil leakage in solder mask semi-plugs with a diameter of 0.5mm and above.

[0010] The technical solution of this invention is:

[0011] A method for fabricating a solder mask half-plug via on a PCB includes the following steps:

[0012] Step S1: Use a volcanic ash grinder to perform surface roughening pretreatment on the PCB;

[0013] Step S2, C-side hole plugging, followed by leveling, or a secondary hole plugging process, using differentiated screen apertures to control the amount of ink, the ink used is a high viscosity hole plugging ink with a solid content of 85%;

[0014] The process of leveling after plugging the holes involves different aluminum mesh screens used for plugging depending on the diameter of the through holes: when the through hole diameter is 0.45-0.5mm, the aluminum mesh screen diameter is 0.225mm; when the through hole diameter is 0.3mm, the aluminum mesh screen diameter is 0.3mm; and when the through hole diameter is 0.2-0.25mm, the aluminum mesh screen diameter is 0.4mm.

[0015] Secondary plugging process: First, all through holes with a diameter ≤ 0.3mm are fully plugged and allowed to settle and level. The aluminum screen printing plate used has a diameter of 0.15-0.2 mm. Then, all through holes that require partial plugging are plugged a second time to correct the flatness of the hole openings and ensure that the ink state of all hole openings is consistent. The aluminum screen printing plate used for the second plugging is adjusted differently according to the diameter of the through hole: when the through hole diameter is 0.45-0.5mm, the aluminum screen printing plate diameter is 0.225mm; when the through hole diameter is 0.3mm, the aluminum screen printing plate diameter is 0.3mm; when the through hole diameter is 0.2-0.25mm, the aluminum screen printing plate diameter is 0.4mm.

[0016] Step S3: Print S-side oil and pre-bake; During the pre-bake process, the exhaust speed of the oven is ≥10m / s and the pre-bake time is 45min to ensure uniform solvent evaporation and prevent oil seepage caused by uneven pre-bake.

[0017] Step S4: Print C-side oil and pre-bake; During the pre-bake process, the exhaust speed of the oven is 10-15m / s, and the pre-bake time is 45min to ensure uniform solvent evaporation and prevent oil seepage caused by uneven pre-bake.

[0018] Step S5, Exposure and Development: Exposure energy 500mJ; During development, place the PCB with the C side facing up, set the development pressure to 1.5 kg / cm², and the speed to 4.0 m / min; During water washing, control the water temperature in the water washing tank after development to 18-27℃, and the hot air drying pressure after water washing ≤2kpa to prevent strong winds from blowing out uncured ink in the holes and causing oil leakage.

[0019] Step S6: High-temperature curing.

[0020] Furthermore, in step S2, the viscosity of the ink used is 120-180 dPa•s.

[0021] Furthermore, in step S2, the plugging pressure is 70-90 kg / cm². 2 .

[0022] Compared with the prior art, the method for manufacturing PCB solder mask half-plug holes provided by the present invention has the following advantages:

[0023] The PCB solder mask half-plugging via manufacturing method provided by this invention optimizes the process from multiple dimensions, including ink selection, plugging method, pre-baking process control, and developing process, so that the fullness of the half-plugging via is stable and meets the standard, and there is no ink accumulation or oil leakage at the hole opening. It systematically solves the core problems of light transmission, ink accumulation, and oil leakage of 0.5mm large-diameter half-plugging via, and significantly improves the first pass yield and the reliability of the final product.

[0024] II. The PCB solder mask half-plugging method provided by the present invention can solve the problem of ink accumulation at the hole opening by plugging process. It can adopt two methods: leveling after plugging or secondary plugging. It is adaptable to production lines with different hardware conditions, has strong universality, and is easy to promote and apply.

[0025] Third, the PCB solder mask semi-plugging method provided by the present invention improves process stability and repeatability by quantitatively managing key parameters such as ink solid content, water washing temperature and drying pressure after development, and exhaust speed when printing surface oil. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the effect of the half-plugging hole produced in Embodiment 1 of the present invention. Detailed Implementation

[0028] To enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, and to make the above-mentioned objectives, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be further described below.

[0029] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0030] Taking the production of the A57 model product as an example, its board thickness is 1.5mm, containing 0.45mm and 0.5mm half-plug holes. The following detailed description of the PCB solder mask half-plug hole manufacturing method of the present invention is provided through specific embodiments.

[0031] Example 1

[0032] A method for fabricating a solder mask half-plug via on a PCB includes the following steps:

[0033] Step S1: Use a volcanic ash grinder to perform surface roughening pretreatment on the PCB;

[0034] Step S2, plugging holes on surface C, followed by a leveling process. The ink used is a high-viscosity plugging ink with a solid content of 85% and a viscosity of 140 dPa·s.

[0035] Specifically, the hole-plugging process is as follows: the aluminum mesh used for plugging is adjusted according to the diameter of the through-hole: when the through-hole diameter is 0.45-0.5mm, the aluminum mesh diameter is 0.225mm; when the through-hole diameter is 0.3mm, the aluminum mesh diameter is 0.3mm; when the through-hole diameter is 0.2-0.25mm, the aluminum mesh diameter is 0.4mm; the plugging pressure is 80 kg / cm². 2 ;

[0036] In this embodiment, the selected ink achieves the best balance between ensuring 0.5mm half-hole fullness (>30%) and avoiding incomplete development.

[0037] Step S3: Print S-side oil and pre-bake; During the pre-bake process, the exhaust speed of the oven is 10-15m / s, and the pre-bake time is 45min.

[0038] Step S4: Print C-side oil and pre-bake; During the pre-bake process, the exhaust speed of the oven is 10-15m / s, and the pre-bake time is 45min.

[0039] During the pre-baking process, the exhaust volume of the oven is monitored online in real time to ensure that the exhaust speed is stable and not less than 10m / s. This ensures uniform evaporation of the ink solvent and avoids subsequent oil leakage caused by uneven pre-baking.

[0040] Step S5, Exposure and Development: Exposure energy 500mJ; During development, place the PCB with the C side facing up, set the development pressure to 1.5 kg / cm², and the speed to 4.0 m / min; During water washing, control the water temperature in the water washing tank after development to 25℃, and the hot air drying pressure after water washing to 1.5 kPa.

[0041] Strict control of the water washing temperature can prevent the ink inside the hole from dissolving and overflowing due to high temperature; by strictly controlling the drying pressure, it can be avoided that strong wind will blow out the uncured ink inside the hole, causing oil leakage.

[0042] Step S6: High-temperature curing.

[0043] Statistical testing showed that among the 2500 boards produced using Example 1, the pass rate for partial hole plugging fullness was greater than 99.8%, the pass rate for orifice ink thickness was greater than 99.5%, and the incidence of major defects (light transmission, ink accumulation, and oil seepage) was less than 0.1%, resulting in a significant improvement in yield. A schematic diagram of the partial hole plugging effect is shown below. Figure 1 As shown.

[0044] It should be noted that in this invention, the C-side refers to the hole-filling side, and the S-side refers to the other side of the circuit board.

[0045] Example 2

[0046] The method for fabricating the PCB solder mask half-plug via in this embodiment is basically the same as in Embodiment 1, except that the plugging process is different. This embodiment uses a two-stage plugging process, as detailed below:

[0047] First, all through holes with a diameter ≤ 0.3 mm are fully plugged and allowed to settle and level. The aluminum mesh used has a hole diameter of 0.15-0.2 mm.

[0048] Then, all through holes requiring partial plugging are plugged a second time to correct the flatness of the hole openings and ensure consistent ink condition across all openings. The aluminum screen used for the second plugging is adjusted according to the hole diameter: 0.225mm for a hole diameter of 0.45-0.5mm; 0.3mm for a hole diameter of 0.3mm; and 0.4mm for a hole diameter of 0.2-0.25mm. This second plugging ensures that ink does not overflow from the hole openings.

[0049] The plugging pressure is 80 kg / cm². 2 .

[0050] The semi-plugged holes made using Example 2 also showed no defects such as light transmission, ink accumulation, or oil seepage, achieving a 100% yield.

[0051] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations made to these embodiments without departing from the principles and spirit of the present invention still fall within the protection scope of the present invention.

Claims

1. A method for manufacturing a PCB solder mask half-plug hole, characterized in that, Includes the following steps: Step S1: Use a volcanic ash grinder to perform surface roughening pretreatment on the PCB; Step S2, C-side hole plugging, adopts a two-stage hole plugging process, controls the ink amount by different screen apertures, and uses high-viscosity hole plugging ink with a solid content of 85%; the viscosity of the high-viscosity hole plugging ink is 120-180 dPa•s; Secondary plugging process: First, all through holes with a diameter ≤ 0.3mm are fully plugged and allowed to settle and level. The aluminum screen used has an aperture of 0.15-0.2 mm. Then, all through holes requiring partial plugging are plugged a second time to correct the flatness of the hole openings and ensure consistent ink condition across all openings. The aluminum screen used for the second plugging is adjusted according to the through hole diameter: when the through hole diameter is 0.45-0.5mm, the aluminum screen aperture is 0.225mm; when the through hole diameter is 0.3mm, the aluminum screen aperture is 0.3mm; when the through hole diameter is 0.2-0.25mm, the aluminum screen aperture is 0.4mm. Step S3: Print S-side oil and pre-bake; During the pre-bake process, the exhaust speed of the oven is 10-15m / s, and the pre-bake time is 45min. Step S4: Print C-side oil and pre-bake; During the pre-bake process, the exhaust speed of the oven is 10-15m / s, and the pre-bake time is 45min. Step S5, Exposure and Development: Exposure energy 500mJ; During development, place the PCB with the C side facing up, set the development pressure to 1.5 kg / cm², and the speed to 4.0 m / min; During water washing, control the water temperature in the water washing tank after development to 18-27℃, and the hot air drying pressure after water washing to ≤2kpa. Step S6: High-temperature curing.

2. The method for manufacturing a PCB solder mask half-plug hole according to claim 1, characterized in that, In step S2, the plugging pressure is 70-90 kg / cm². 2 .

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