Method for printing ink on hole wall of PCB board

Abstract

The present invention discloses a method for printing ink on the hole walls of a PCB board, which includes the following steps: a pre-process of manufacturing a PCB board having PTH holes; green ink pre-treatment, green ink plugging, green ink screen printing on the upper and lower surfaces of the PCB board, green ink pre-curing, first exposure, first green ink development, second exposure, first curing, screen printing the hole, third exposure, second green ink development, curing, screen printing the hole walls, fourth exposure, third green ink development, and second curing; and a post-process; wherein the light-exposed area of the first and third exposures is smaller than a single side of the hole on the PCB board, and the light-exposed area of the second and fourth exposures is larger than a single side of the hole on the PCB board. The plugging depth of the present invention is greater than 80%, the ink is evenly printed on the hole walls, and the aperture size of the same through hole is ensured to be consistent, which is beneficial to improving the quality of the PCB board.

Description

Technical Field

[0001] The present invention relates to the field of PCB boards, and more particularly to a method for printing ink on the hole wall of a PCB board. Background Art

[0002] With the development of technology, the requirements for PCB products in different fields have also changed. PCB boards are developing towards high density and multi-functions. PCB boards have developed from traditional single-layer boards to multi-layer boards. The boards are connected through PTH holes. In order to protect the copper in the holes, the holes will be plugged. Usually, plugging is achieved by resin plugging or ink plugging. The plugging depth needs to meet the requirements.

[0003] For ink plugging, conventionally, the plugging is achieved by printing ink with a silk screen printer, which requires a silk screen screen and a pad. The production process includes the following steps: pressing, drilling, copper deposition, electroplating, silk screen printing ink, curing and post-processing. However, during the plugging process, some areas of the hole wall may not be printed with ink, or the ink on the hole wall may be uneven, and the ink thickness may be inconsistent, resulting in the hole diameter being inconsistent with the preset hole diameter. Summary of the Invention

[0004] In order to solve the problem of uneven ink in hole wall printing, the present invention provides a method for printing ink on the hole wall of a PCB board.

[0005] A method for printing ink on the hole wall of a PCB board comprises the following steps in sequence:

[0006] Pre-process, making PCB board with PTH hole;

[0007] Green oil pre-treatment, green oil plugging, green oil screen printing on the upper and lower surfaces of the PCB board, green oil pre-curing, first exposure, first green oil development, second exposure, first curing, screen printing and hole covering, third exposure, second green oil development, curing, screen printing hole wall, fourth exposure, third green oil development, second curing;

[0008] Post-process;

[0009] The first exposure and the third exposure are performed on the single-sided window hole, and the light-exposed area is smaller than the single side of the hole. The second exposure and the fourth exposure are performed on the light-exposed area larger than the single side of the hole on the PCB board.

[0010] In some embodiments, the first exposure is performed on a single-sided windowed hole, and the light-exposed area is 1.5 mil smaller than a single side of the hole on the PCB board;

[0011] The second exposure is performed on the single-sided window hole, and the light-exposed area is 3 mil larger than the single side of the hole on the PCB board. The energy of the second exposure is at least twice that of the first exposure.

[0012] For the third exposure, for a hole with a single-sided window and already plugged, the visible area is 1.5 mil smaller than the single side of the hole on the PCB board;

[0013] In the fourth exposure, the light-exposed area is 3 to 5 mil larger than a single side of the hole on the PCB board. The hole wall is basically covered with ink, the ink is evenly distributed, and the screen printing effect is good.

[0014] In some embodiments, for the third exposure, for the hole after silk-screening, the light-seeing area is 3 mil larger than the single side of the hole ring on the hole, and is at least 1.5 mil away from other windowed holes.

[0015] In some embodiments, the silk screen printing method uses a silk screen to plug all holes that need to be plugged, and the printing ink area is 10 mil larger than the single side of the hole to ensure the effect of the silk screen printing.

[0016] In some embodiments, the screen printing hole cover is performed by printing ink on the holes that need to be screen printed, and the printing ink area is a circular area formed from the hole edge to 10 to 30 mil inside the hole and from the hole edge to 10 to 30 mil outside the hole, so as to ensure the effect of the screen printing hole cover.

[0017] In some embodiments, the first curing step includes the following steps: curing at 60 degrees Celsius for 2 hours, curing at 75 degrees Celsius for 1 hour, curing at 100 degrees Celsius for 0.5 hours, and curing at 150 degrees Celsius for 1 hour. A good first curing effect leads to a good ink curing effect.

[0018] In some embodiments, the screen printing of the hole wall uses a 61T screen if the PCB board thickness is less than 0.6mm; a 43T screen if the PCB board thickness is 0.6-1.6mm; and a 36T screen if the PCB board thickness is greater than 1.6mm. This provides a good screen printing effect on the hole wall.

[0019] In some embodiments, the viscosity of the green oil used is 20-40 dPa.s, which is beneficial to improving the uniformity of the ink on the hole wall.

[0020] In some embodiments, the front process includes the following steps in sequence: cutting, inner layer patterning, lamination, drilling, copper plating to form PTH holes, full board electroplating, outer layer circuits, pattern plating, outer layer etching and AOI inspection.

[0021] In some embodiments, the post-process includes the following steps in sequence: text, surface treatment, molding, electrical testing, FQC, PSA and packaging.

[0022] Compared with the prior art, the present invention has the following beneficial effects: the present invention discloses a method for printing ink on the hole wall of a PCB board, wherein ink is coated on the hole through green ink plugging, green oil silk screen printing, silk screen printing covering the hole, and silk screen printing the hole wall; in the first and third exposures, the visible area is smaller than a single side of the hole on the PCB board; in the second and fourth exposures, the visible area is larger than a single side of the hole on the PCB board; the plugging depth is more than 80%; the ink is printed evenly on the hole wall, ensuring that the aperture size of the same through hole is consistent, which is beneficial to improving the quality of the PCB board. DETAILED DESCRIPTION

[0023] To illustrate the technical solution of the present invention in detail, the following is a clear and complete description of the technical solution of the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Example 1:

[0025] This embodiment provides a method for printing ink on a hole wall of a PCB board, comprising the following steps in sequence:

[0026] Pre-process, making PCB board with PTH hole;

[0027] Green oil pre-treatment, green oil plugging, green oil screen printing on the upper and lower surfaces of the PCB board, green oil pre-curing, first exposure, first green oil development, second exposure, first curing, screen printing and hole covering, third exposure, second green oil development, curing, screen printing hole wall, fourth exposure, third green oil development, second curing;

[0028] Post-process;

[0029] The first and third exposures are for exposing the single-sided window hole, and the light-visible area is smaller than the single side of the hole. The second and fourth exposures are for exposing the light-visible area larger than the single side of the hole on the PCB board.

[0030] In this embodiment, the front process and the back process are conventional processes for the production of existing PCB boards. The green oil screen printing, screen printing hole cover, and screen printing hole wall all include operations from the top and bottom of the board. Through green oil pre-treatment, foreign matter on the surface of the PCB board is removed. According to the requirements of plugging the hole, the depth of the hole covered by green oil is controlled, and green oil screen printing is performed to print ink on the hole wall. The visible area is smaller than a single side of the hole on the PCB board. In the second exposure and the fourth exposure, the visible area is larger than a single side of the hole on the PCB board. The visible area refers to the area that can be illuminated by light. The green oil used is a photosensitive ink with a viscosity of 20 to 40 dPa.s.

[0031] Photosensitive inks have the property of selectively absorbing UV light. This is affected by the total energy of the UV light source and the energy distribution of light of different wavelengths. Under UV light irradiation, the photopolymerization initiator in the photosensitive ink absorbs photons of a certain wavelength, excites it to an excited state, and forms free radicals or ions.

[0032] Then, through intermolecular energy transfer, the polymerized prepolymer and the photosensitive monomer and polymer become excited, generating charge transfer complexes. These complex particles are continuously cross-linked and polymerized to solidify into a film.

[0033] Through multiple screen printing, first exposure, second exposure, third exposure and fourth exposure, the ink in the hole is evenly distributed. Specifically:

[0034] The first exposure is for the hole with single-sided window, and the light-seeing area is 1.5 mil smaller than the single side of the hole on the PCB board.

[0035] The second exposure is performed on a single-sided hole. The visible area is 3 mils larger than the single side of the hole on the PCB board. The energy of the second exposure is at least twice that of the first exposure. This second exposure only exposes one end of the hole.

[0036] In the third exposure, for holes with single-sided windowing and plugged holes, the visible area is 1.5 mil smaller than the single side of the hole on the PCB board. In some embodiments, in the third exposure, for holes covered by silk screen printing, the visible area is 3 mil larger than the single side of the hole ring on the hole, and the distance from other holes with windowing is at least 1.5 mil.

[0037] During the fourth exposure, the visible area is 3-5 mils larger than the single side of the hole on the PCB board. A traditional exposure machine is used to ensure that light can reach the hole wall.

[0038] The first curing includes the following steps in sequence: curing at a temperature of 60 degrees Celsius for 2 hours, curing at a temperature of 75 degrees Celsius for 1 hour, curing at a temperature of 100 degrees Celsius for 0.5 hours, and curing at a temperature of 150 degrees Celsius for 1 hour.

[0039] For screen printing of hole walls, if the PCB thickness is less than 0.6mm, use a 61T screen; if the PCB thickness is between 0.6 and 1.6mm, use a 43T screen; if the PCB thickness is greater than 1.6mm, use a 36T screen. Depending on the thickness of the PCB board, screens with different mesh sizes are used to ensure the screen printing effect on the hole walls and improve the uniformity of the printing ink.

[0040] The test results show that this method can achieve a depth of more than 80% for plugging holes with single-sided windows, and there is no problem of thin ink at the hole edge; it can ensure that the hole walls are printed with ink and the ink is uniform.

[0041]

[0042] This embodiment discloses a method for printing ink on the hole walls of a PCB board. Ink is applied to the holes by plugging the holes with green ink, silk-screening the holes with green ink, covering the holes with silk-screen printing, and then silk-screening the hole walls. During the first and third exposures, the visible area is smaller than a single side of the hole on the PCB board. During the second and fourth exposures, the visible area is larger than a single side of the hole on the PCB board. The plugging depth is greater than 80%, and the ink is evenly printed on the hole walls, ensuring that the aperture size of the same through-hole is consistent, which is beneficial to improving the quality of the PCB board.

[0043] Example 2

[0044] This embodiment provides a method for printing ink on a hole wall of a PCB board, comprising the following steps in sequence:

[0045] The pre-process involves producing a PCB with PTH holes. The process includes green ink pre-treatment, green ink plugging, green ink screen printing on both the top and bottom surfaces of the PCB, green ink pre-curing, first exposure, first green ink development, second exposure, first curing, screen printing for hole cover, third exposure, second green ink development, curing, screen printing for hole walls, fourth exposure, third green ink development, and second curing. The post-process involves the first and third exposures for single-sided windowed holes. The visible area is smaller than the hole's single edge. The second and fourth exposures are larger than the hole's single edge. The visible area refers to the area that can be illuminated. The green ink used is a photosensitive ink with a viscosity of 20-40 dPa.s. For screen printing of the hole walls, a 61T screen is used for PCB thicknesses less than 0.6mm; a 43T screen is used for PCB thicknesses between 0.6mm and 1.6mm; and a 36T screen is used for PCB thicknesses greater than 1.6mm. According to the different thickness of PCB boards, screens with different mesh sizes are used to ensure the screen printing effect of the hole wall and improve the uniformity of the printing ink.

[0046] For all holes that need to be plugged, a screen is used to plug the holes. The printing area is 10 mil larger than the hole side to ensure the effect of the screen printing ink on the hole wall. Depending on the actual situation, the number of screen printing times is 2 to 5.

[0047] For screen printing, ink is applied to the holes that need to be covered. The ink area is a circular area from the hole edge to 10-30 mil inside the hole, and from the hole edge to 10-30 mil outside the hole. This ensures the effect of the screen printing ink on the hole wall.

[0048] This embodiment discloses a method for printing ink on the hole walls of a PCB board. Ink is applied to the holes by plugging the holes with green ink, silk-screening the holes with green ink, covering the holes with silk-screen printing, and then silk-screening the hole walls. During the first and third exposures, the visible area is smaller than a single side of the hole on the PCB board. During the second and fourth exposures, the visible area is larger than a single side of the hole on the PCB board. The plugging depth is greater than 80%, and the ink is evenly printed on the hole walls, ensuring that the aperture size of the same through-hole is consistent, which is beneficial to improving the quality of the PCB board.

[0049] Example 3

[0050] This embodiment provides a method for printing ink on a hole wall of a PCB board, comprising the following steps in sequence:

[0051] The pre-process involves producing a PCB with PTH holes. The process includes green ink pre-treatment, green ink plugging, green ink screen printing on both the top and bottom surfaces of the PCB, green ink pre-curing, first exposure, first green ink development, second exposure, first curing, screen printing for hole cover, third exposure, second green ink development, curing, screen printing for hole walls, fourth exposure, third green ink development, and second curing. The post-process involves the first and third exposures for single-sided windowed holes. The visible area is smaller than the hole's single edge. The second and fourth exposures are larger than the hole's single edge. The visible area refers to the area that can be illuminated. The green ink used is a photosensitive ink with a viscosity of 20-40 dPa.s. For screen printing of the hole walls, a 61T screen is used for PCB thicknesses less than 0.6mm; a 43T screen is used for PCB thicknesses between 0.6mm and 1.6mm; and a 36T screen is used for PCB thicknesses greater than 1.6mm. According to the different thickness of PCB boards, screens with different mesh sizes are used to ensure the screen printing effect of the hole wall and improve the uniformity of the printing ink.

[0052] The pre-process includes the following steps: cutting, inner layer patterning, lamination, drilling, copper deposition to form PTH holes, full-board electroplating, outer layer circuitry, pattern plating, outer layer etching, and AOI inspection. Cutting begins with cutting the substrate to a predetermined size, followed by inner layer patterning. Two or more substrates are laminated to form a PCB. Through holes are drilled, copper is deposited to form PTH holes, and full-board electroplating thickens the PCB surface and copper in the holes. Finally, outer layer patterning, pattern plating, outer layer etching, and AOI inspection are performed. AOI inspection ensures PCB quality.

[0053] This embodiment discloses a method for printing ink on the hole walls of a PCB board. Ink is applied to the holes by plugging the holes with green ink, silk-screening the holes with green ink, covering the holes with silk-screen printing, and then silk-screening the hole walls. During the first and third exposures, the visible area is smaller than a single side of the hole on the PCB board. During the second and fourth exposures, the visible area is larger than a single side of the hole on the PCB board. The plugging depth is greater than 80%, and the ink is evenly printed on the hole walls, ensuring that the aperture size of the same through-hole is consistent, which is beneficial to improving the quality of the PCB board.

[0054] Example 4

[0055] This embodiment provides a method for printing ink on a hole wall of a PCB board, comprising the following steps in sequence:

[0056] The pre-process involves producing a PCB with PTH holes. The process includes green ink pre-treatment, green ink plugging, green ink screen printing on both the top and bottom surfaces of the PCB, green ink pre-curing, first exposure, first green ink development, second exposure, first curing, screen printing for hole cover, third exposure, second green ink development, curing, screen printing for hole walls, fourth exposure, third green ink development, and second curing. The post-process involves the first and third exposures for single-sided windowed holes. The visible area is smaller than the hole's single edge. The second and fourth exposures are larger than the hole's single edge. The visible area refers to the area that can be illuminated. The green ink used is a photosensitive ink with a viscosity of 20-40 dPa.s. For screen printing of the hole walls, a 61T screen is used for PCB thicknesses less than 0.6mm; a 43T screen is used for PCB thicknesses between 0.6mm and 1.6mm; and a 36T screen is used for PCB thicknesses greater than 1.6mm. According to the different thickness of PCB boards, screens with different mesh sizes are used to ensure the screen printing effect of the hole wall and improve the uniformity of the printing ink.

[0057] The post-process includes the following steps in sequence: text, surface treatment, molding, electrical testing, FQC, PSA and packaging.

[0058] This embodiment discloses a method for printing ink on the hole walls of a PCB board. Ink is applied to the holes by plugging the holes with green ink, silk-screening the holes with green ink, covering the holes with silk-screen printing, and then silk-screening the hole walls. During the first and third exposures, the visible area is smaller than a single side of the hole on the PCB board. During the second and fourth exposures, the visible area is larger than a single side of the hole on the PCB board. The plugging depth is greater than 80%, and the ink is evenly printed on the hole walls, ensuring that the aperture size of the same through-hole is consistent, which is beneficial to improving the quality of the PCB board.

[0059] The method of the present invention can be used to realize hole wall printing ink, can also be used as a method for realizing hole plugging with photosensitive ink, and can also be used as a method for realizing hole wall printing ink and hole plugging with photosensitive ink at the same time.

[0060] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention pertains. The terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the present invention.

[0061] In the description of the present invention, it should be understood that the terms indicating orientation or positional relationships are only used to facilitate the description of the present invention and simplify the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, it should not be understood as a limitation on the present invention.

[0062] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art may still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this embodiment are included within the scope of protection of the present invention.

Claims

1. A method for printing ink on the hole wall of a PCB board, characterized by: The following steps are included in sequence: Pre-process, making PCB board with PTH hole; Green oil pre-treatment, green oil plugging, green oil screen printing on the upper and lower surfaces of the PCB board, green oil pre-curing, first exposure, first green oil development, second exposure, first curing, screen printing and hole covering, third exposure, second green oil development, curing, screen printing hole wall, fourth exposure, third green oil development, second curing; Post-process; The first exposure and the third exposure are performed on the single-sided window hole, and the light-exposed area is smaller than the single side of the hole. The second exposure and the fourth exposure are performed on the light-exposed area larger than the single side of the hole on the PCB board.

2. The method for printing ink on a hole wall of a PCB board according to claim 1, wherein: The first exposure is performed on a single-sided windowed hole, and the light-exposed area is 1.5 mil smaller than a single side of the hole on the PCB board; The second exposure is performed on the single-sided window hole, and the light-exposed area is 3 mil larger than the single side of the hole on the PCB board. The energy of the second exposure is at least twice that of the first exposure. For the third exposure, for a hole with a single-sided window and already plugged, the visible area is 1.5 mil smaller than the single side of the hole on the PCB board; In the fourth exposure, the light-seeing area is 3 to 5 mil larger than a single side of the hole on the PCB board.

3. The method for printing ink on a hole wall of a PCB board according to claim 1, wherein: For the third exposure, for the hole after silk screen printing, the light-seeing area is 3 mil larger than the single side of the hole ring on the hole, and the distance from other windowed holes is at least 1.5 mil.

4. The method for printing ink on a hole wall of a PCB board according to claim 1, wherein: The silk screen printing cover hole uses a silk screen to plug all holes that need to be plugged, and the printing ink area is 10 mil larger than one side of the hole.

5. The method for printing ink on a hole wall of a PCB board according to claim 1, wherein: The silk screen printing hole covering is to print ink on the hole that needs silk screen printing, and the printing ink area is a circular area formed from the hole edge to 10 to 30 mil inside the hole and from the hole edge to 10 to 30 mil outside the hole.

6. The method for printing ink on a hole wall of a PCB board according to claim 1, wherein: The first curing includes the following steps in sequence: curing at a temperature of 60 degrees Celsius for 2 hours, curing at a temperature of 75 degrees Celsius for 1 hour, curing at a temperature of 100 degrees Celsius for 0.5 hours, and curing at a temperature of 150 degrees Celsius for 1 hour.

7. The method for printing ink on a hole wall of a PCB board according to claim 1, wherein: For the screen printing hole wall, if the thickness of the PCB board is less than 0.6mm, a 61T screen is used; if the thickness of the PCB board is 0.6-1.6mm, a 43T screen is used; if the thickness of the PCB board is greater than 1.6mm, a 36T screen is used.

8. The method for printing ink on a hole wall of a PCB board according to claim 1, wherein: The viscosity of the green oil used is 20-40 dPa.S.

9. The method for printing ink on a hole wall of a PCB board according to claim 1, wherein: The front process includes the following steps in sequence: cutting, inner layer patterning, lamination, drilling, copper plating to form PTH holes, full board electroplating, outer layer circuits, pattern electroplating, outer layer etching and AOI inspection.

10. The method for printing ink on a hole wall of a PCB board according to claim 1, characterized in that: The post-process includes the following steps in sequence: text, surface treatment, molding, electrical testing, FQC, PSA and packaging.

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