A through-hole plate airtightness PCB and a manufacturing method thereof

Abstract

The application provides a kind of for improving the hermeticity PCB board of via board and its preparation method.The preparation method includes the following steps: (1) the substrate drilled with via is sequentially carried out copper plating, oil plug and covered dry film to obtain first substrate;(2) the first nickel gold plating layer is prepared at the via of the first substrate obtained in step (1), to obtain second substrate;(3) the nano plating layer is deposited at the via of the second substrate obtained in step (2), and the second nickel gold plating layer is prepared after removing the dry film, to obtain the PCB board for improving the hermeticity of via board.The PCB board for improving the hermeticity of via board provided by the application improves the hermeticity of high printed wiring board via board by depositing nano plating layer on the via of PCB board, avoids or reduces the malpractice of panel reliability failure caused by insufficient hermeticity and other problems, and further improves the moisture-proof performance of via board.

Description

Technical Field

[0001] This invention belongs to the field of printed circuit board processing technology, and relates to a method for preparing a PCB board, and more particularly to a PCB board for improving the airtightness of through-hole boards and its preparation method. Background Technology

[0002] PCB (Printed Circuit Board), also known as PCB, is a crucial component in the electronics industry. Almost every electronic device, from small items like watches and calculators to large systems like computers, communication devices, and military weaponry, relies on PCBs for the electrical interconnection of integrated circuits and other electronic components. The design and manufacturing quality of PCBs directly impacts the overall product quality and cost, and can even determine the success or failure of a business competition.

[0003] Currently, in order to prevent non-component holes from being oxidized and corroded by acids and alkalis in the natural environment over many years, causing short circuits and poor electrical properties, especially at BGA (Ball Grid Array) locations, it is necessary to take measures to plug the holes.

[0004] Currently, through-hole boards still use solder mask (SMT) for via plugging, which involves the following process: copper plating (depositing a thin layer of copper on the PCB surface and hole walls through a chemical reaction), electroplating (thickening the copper layer on the PCB through electroplating), outer layer circuit fabrication (fabricating the outer layer circuitry using a positive film process, including pattern electroplating and alkaline etching), and the fabrication of the SMT solder mask (including SMT pretreatment, aluminum foil plugging, surface ink printing, pre-baking, baking, exposure, development, low temperature, high temperature, and other normal processes). This process fails to achieve the required fullness of via plugging in densely populated areas. After screen printing, exposure, and development, inspection reveals reddish or copper-colored edges around the holes (primarily in areas with dense BGAs). This method is no longer suitable for future PCB development. With the future development trends of the PCB electronics industry, the design and requirements for BGA pin precision are higher (e.g., BGA pins with half-hole tangency or in-hole designs require opening windows), and the photosensitive ink plugging and printing process cannot meet these requirements. After development, poor hole plugging or light transmission may occur, leading to solder balls trapped in the vias or short circuits during customer assembly due to gold plating.

[0005] CN 102427678A discloses a PCB manufacturing method, which includes copper plating and electroplating steps. After the electroplating step, the method further includes the following steps: polishing the PCB surface with a brush; inserting dried solder mask into the holes of the PCB using a printing press; baking the PCB at 150±5℃ for 40-60 minutes; grinding the surface with a non-woven fabric brush to smooth out any protruding solder mask; fabricating the outer layer circuitry using a negative film process; and fabricating the solder mask layer. This patented method ensures fuller hole filling on the PCB, a smoother surface after printing, and significantly improves the reddish tint around the holes. However, it cannot guarantee complete adhesion between the copper and ink materials in each via. If any via fails, the entire PCB panel faces quality risks.

[0006] Therefore, it is necessary to provide a process for improving the airtightness of through-hole plates in order to reduce panel reliability failures caused by insufficient airtightness and other problems. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a PCB board for improving the airtightness of through-hole panels and its preparation method. This invention improves the airtightness of through-hole PCB boards by depositing a nano-coating on the through-holes, avoiding or reducing the drawbacks of panel reliability failure caused by insufficient airtightness.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing a PCB board with improved airtightness of through-hole plates, the method comprising the following steps:

[0010] (1) The first substrate is obtained by sequentially plating copper, filling with oil, and covering with dry film on the substrate with drilled through holes.

[0011] (2) A first nickel-gold plating layer is prepared at the through-hole of the first substrate obtained in step (1) to obtain a second substrate;

[0012] (3) A nano-coating is deposited at the through-hole of the second substrate obtained in step (2), and a second nickel-gold coating is prepared after removing the dry film to obtain the PCB board used to improve the airtightness of the through-hole board.

[0013] This invention improves the moisture resistance and airtightness of through-hole boards by preparing the coating in steps on the PCB board and by adding a separate nano-coating at the through-holes.

[0014] In the preparation process described in this invention, the second gold plating layer is used for LED chip electrical connection bonding wires or reflow soldering materials.

[0015] As a preferred technical solution of the present invention, the oil filling in step (1) includes: using a printing machine to fill the through hole with dry green oil.

[0016] Preferably, step (1) includes drying after oil plugging.

[0017] Preferably, the drying temperature is 115-135°C, for example, 115°C, 120°C, 125°C, 130°C or 135°C, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0018] Preferably, the drying time is 30 to 60 minutes, for example, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes or 60 minutes, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0019] Preferably, step (1) includes the step of opening holes in the dry film after covering it.

[0020] Preferably, the position of the opening in the dry film corresponds to the position of the through hole.

[0021] Preferably, step (2) the first nickel-gold plating layer includes a nickel layer and a gold layer stacked sequentially.

[0022] Preferably, the thickness of the nickel layer is ≥3.8μm, for example, it can be 3.8μm, 4.0μm, 4.2μm, 4.4μm, 4.6μm, 4.8μm or 5μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0023] Preferably, the thickness of the gold layer is ≥0.05μm, for example, it can be 0.05μm, 0.06μm, 0.07μm, 0.08μm, 0.09μm or 0.10μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0024] Preferably, the preparation process of the first nickel-gold plating layer in step (2) includes an electroplating process or a chemical gold plating process.

[0025] Preferably, the nano-coating in step (3) includes a silicon dioxide coating and / or an aluminum oxide coating.

[0026] The nano-coating described in this invention can prevent moisture and oxygen from entering the encapsulated PCB board through the through-holes and damaging the chip.

[0027] Preferably, the thickness of the nano-coating in step (3) is 0.05 to 0.1 μm, for example, it can be 0.05 μm, 0.06 μm, 0.07 μm, 0.08 μm, 0.09 μm or 0.10 μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0028] Preferably, the preparation process of the nano-coating in step (3) includes a vapor deposition process.

[0029] Preferably, the vacuum degree in the vapor deposition process is greater than 1×10⁻⁶. 3 mbar, for example, could be 1×10 3 mbar, 1.4×10 3 mbar, 1.8×10 3 mbar, 2.2×10 3 mbar or 2.5×10 3 mbar, but not limited to the listed values, applies to other unlisted values ​​within the range as well.

[0030] Preferably, the growth temperature of the nano-coating in the vapor deposition process is 130-160°C, for example, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C or 160°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0031] Preferably, step (3) after removing the dry film further includes sequential acid washing, water washing, and drying.

[0032] Preferably, the cleaning solution in the pickling process includes sulfuric acid and / or hydrochloric acid.

[0033] Preferably, the acidity of the cleaning solution is 2-8%, for example, it can be 2%, 3%, 4%, 5%, 6%, 7% or 8%, but is not limited to the listed values. Other values ​​not listed within the range are also applicable.

[0034] Preferably, the pickling time is 10 to 30 seconds, for example, 10 seconds, 14 seconds, 18 seconds, 22 seconds, 26 seconds or 30 seconds, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0035] Preferably, the washing time is 20 to 60 seconds, for example, 20 seconds, 30 seconds, 40 seconds, 50 seconds or 60 seconds, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0036] Preferably, the drying temperature is 80-90°C, for example, 80°C, 82°C, 84°C, 86°C, 88°C or 90°C, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0037] Preferably, the drying time is 15 to 40 seconds, for example, 15 seconds, 20 seconds, 25 seconds, 30 seconds, 35 seconds or 40 seconds, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0038] As a preferred embodiment of the present invention, the method for preparing a PCB board with improved airtightness of through-hole plates provided by the first aspect of the present invention includes the following steps:

[0039] (1) The substrate with through holes is subjected to copper plating, oil filling, drying at 115-135℃ for 30-60 minutes and covered with dry film to obtain the first substrate.

[0040] The process of covering the dry film includes the step of opening holes in the dry film, wherein the position of the opening holes in the dry film corresponds to the position of the through holes.

[0041] (2) A first nickel-gold plating layer is prepared at the through-hole of the first substrate obtained in step (1) by electroplating or chemical gold plating process to obtain a second substrate;

[0042] The first nickel-gold plating layer comprises a nickel layer with a thickness ≥3.8μm and a gold layer with a thickness ≥0.05μm, which are stacked sequentially.

[0043] (3) A nano-coating with a thickness of 0.05 to 0.1 μm is deposited at the through hole of the second substrate obtained in step (2) by vapor deposition. After removing the dry film, a second nickel-gold coating is prepared to obtain the PCB board used to improve the airtightness of the through hole plate.

[0044] The process includes pickling, rinsing, and drying after removing the dry film. The pickling solution includes sulfuric acid and / or hydrochloric acid with an acidity of 2-8%. The pickling time is 10-30 seconds, the rinsing time is 20-60 seconds, and the drying temperature is 80-90°C for 15-40 seconds.

[0045] In a second aspect, the present invention provides a PCB board for improving the airtightness of through-hole plates, wherein the PCB board for improving the airtightness of through-hole plates is obtained by the preparation method provided in the first aspect.

[0046] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0047] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0048] (1) The PCB board provided by the present invention for improving the airtightness of through-hole plates reduces or avoids the drawback of panel failure caused by insufficient airtightness.

[0049] (2) The PCB board for improving the airtightness of the through-hole plate provided by the present invention improves the moisture resistance of the PCB board. Detailed Implementation

[0050] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0051] Example 1

[0052] This embodiment provides a PCB board for improving the airtightness of through-hole plates. The preparation method of the PCB board for improving the airtightness of through-hole plates includes the following steps:

[0053] (1) The substrate with through holes was subjected to copper plating, oil filling, drying at 120°C for 45 min and covered with dry film in sequence to obtain the first substrate.

[0054] The process of covering the dry film includes the step of opening holes in the dry film, wherein the position of the opening holes in the dry film corresponds to the position of the through holes.

[0055] (2) A first nickel-gold plating layer is prepared at the through-hole of the first substrate obtained in step (1) by electroplating or chemical gold plating process to obtain a second substrate;

[0056] The first nickel-gold plating layer comprises a nickel layer with a thickness of 4.2 μm and a gold layer with a thickness of 0.08 μm, which are stacked sequentially.

[0057] (3) A silicon dioxide coating with a thickness of 0.08 μm is deposited at the through hole of the second substrate obtained in step (2) by vapor deposition. After removing the dry film, a second nickel-gold coating is prepared to obtain the PCB board used to improve the airtightness of the through hole board.

[0058] The process includes pickling, rinsing, and drying after removing the dry film. The pickling solution contains sulfuric acid with an acidity of 5%. The pickling time is 20 seconds, the rinsing time is 50 seconds, and the drying temperature is 85°C for 30 seconds.

[0059] Example 2

[0060] This embodiment provides a PCB board for improving the airtightness of through-hole plates. The preparation method of the PCB board for improving the airtightness of through-hole plates includes the following steps:

[0061] (1) The substrate with through holes was subjected to copper plating, oil filling, drying at 115°C for 60 min and covered with dry film in sequence to obtain the first substrate.

[0062] The process of covering the dry film includes the step of opening holes in the dry film, wherein the position of the opening holes in the dry film corresponds to the position of the through holes.

[0063] (2) A first nickel-gold plating layer is prepared at the through-hole of the first substrate obtained in step (1) by electroplating or chemical gold plating process to obtain a second substrate;

[0064] The first nickel-gold plating layer comprises a nickel layer with a thickness of 5.2 μm and a gold layer with a thickness of 0.05 μm, which are stacked sequentially.

[0065] (3) A silicon dioxide coating with a thickness of 0.05 to 0.1 μm is deposited at the through hole of the second substrate obtained in step (2) by vapor deposition. After removing the dry film, a second nickel-gold coating is prepared to obtain the PCB board used to improve the airtightness of the through hole board.

[0066] The process includes pickling, rinsing, and drying after removing the dry film. The pickling solution contains sulfuric acid with an acidity of 2%. The pickling time is 30 seconds, the rinsing time is 20 seconds, and the drying temperature is 80°C for 40 seconds.

[0067] Example 3

[0068] This embodiment provides a PCB board for improving the airtightness of through-hole plates. The preparation method of the PCB board for improving the airtightness of through-hole plates includes the following steps:

[0069] (1) The substrate with through holes was subjected to copper plating, oil filling, drying at 135°C for 30 min and covered with dry film in sequence to obtain the first substrate.

[0070] The process of covering the dry film includes the step of opening holes in the dry film, wherein the position of the opening holes in the dry film corresponds to the position of the through holes.

[0071] (2) A first nickel-gold plating layer is prepared at the through-hole of the first substrate obtained in step (1) by electroplating or chemical gold plating process to obtain a second substrate;

[0072] The first nickel-gold plating layer comprises a nickel layer with a thickness of 3.8 μm and a gold layer with a thickness of 0.05 μm, which are stacked sequentially.

[0073] (3) A 0.1 μm thick aluminum oxide coating is deposited at the through hole of the second substrate obtained in step (2) by vapor deposition. After removing the dry film, a second nickel-gold coating is prepared to obtain the PCB board used to improve the airtightness of the through hole board.

[0074] The process includes pickling, rinsing, and drying after removing the dry film. The pickling solution includes sulfuric acid and / or hydrochloric acid with an acidity of 8%. The pickling time is 10 seconds, the rinsing time is 60 seconds, and the drying temperature is 90°C for 15 seconds.

[0075] Example 4

[0076] This embodiment provides a PCB board for improving the airtightness of through-hole plates. The preparation method of the PCB board for improving the airtightness of through-hole plates includes the following steps:

[0077] (1) The substrate with through holes was successively subjected to copper plating, oil filling, drying at 130°C for 50 min and covered with dry film to obtain the first substrate.

[0078] The process of covering the dry film includes the step of opening holes in the dry film, wherein the position of the opening holes in the dry film corresponds to the position of the through holes.

[0079] (2) A first nickel-gold plating layer is prepared at the through-hole of the first substrate obtained in step (1) by electroplating or chemical gold plating process to obtain a second substrate;

[0080] The first nickel-gold plating layer comprises a nickel layer with a thickness of 4.5 μm and a gold layer with a thickness of 1.5 μm, which are stacked sequentially.

[0081] (3) A 0.09 μm thick aluminum oxide coating is deposited at the through hole of the second substrate obtained in step (2) by vapor deposition. After removing the dry film, a second nickel-gold coating is prepared to obtain the PCB board used to improve the airtightness of the through hole board.

[0082] The process includes pickling, rinsing, and drying after removing the dry film. The pickling solution contains sulfuric acid with an acidity of 5.5%. The pickling time is 25 seconds, the rinsing time is 50 seconds, and the drying temperature is 85°C for 40 seconds.

[0083] Example 5

[0084] This embodiment provides a PCB board for improving the airtightness of through-hole plates. The only difference between the preparation method of the PCB board for improving the airtightness of through-hole plates and Embodiment 1 is that:

[0085] In this embodiment, the thickness of the nickel layer in step (2) is changed to 3.2 μm, and the thickness of the gold layer is changed to 0.02 μm.

[0086] Example 6

[0087] This embodiment provides a PCB board for improving the airtightness of through-hole plates. The only difference between the preparation method of the PCB board for improving the airtightness of through-hole plates and Embodiment 1 is that:

[0088] In this embodiment, the thickness of the silicon dioxide coating in step (3) is changed to 0.03 μm.

[0089] Example 7

[0090] This embodiment provides a PCB board for improving the airtightness of through-hole plates. The only difference between the preparation method of the PCB board for improving the airtightness of through-hole plates and Embodiment 1 is that:

[0091] In this embodiment, the thickness of the silicon dioxide coating in step (3) is changed to 0.15 μm.

[0092] Comparative Example 1

[0093] This comparative example provides a PCB board for improving the airtightness of through-hole plates. The only difference between the preparation method of the PCB board for improving the airtightness of through-hole plates and Example 1 is that:

[0094] In this comparative example, the nickel-gold plating layer described in step (2) is replaced with a nickel layer with a thickness of 4.2 μm.

[0095] Comparative Example 2

[0096] This comparative example provides a PCB board for improving the airtightness of through-hole plates. The only difference between the preparation method of the PCB board for improving the airtightness of through-hole plates and Example 1 is that:

[0097] In this comparative example, the nickel-gold plating layer described in step (2) is replaced with a gold layer with a thickness of 0.08 μm.

[0098] Comparative Example 3

[0099] This comparative example provides a PCB board for improving the airtightness of through-hole plates. The only difference between the preparation method of the PCB board for improving the airtightness of through-hole plates and Example 1 is that:

[0100] This comparative example omits the first nickel-gold plating layer described in step (2).

[0101] Comparative Example 4

[0102] This comparative example provides a PCB board for improving the airtightness of through-hole plates. The only difference between the preparation method of the PCB board for improving the airtightness of through-hole plates and Example 1 is that:

[0103] This comparative example omits the silicon dioxide coating described in step (3).

[0104] Performance testing:

[0105] The PCBs provided in Examples 1-7 and Comparative Examples 1-4 for improving the airtightness of through-hole boards were subjected to airtightness testing. The test results are shown in Table 1. The testing methods are as follows:

[0106] The PCBs provided in Examples 1-7 and Comparative Examples 1-4 for improving the airtightness of through-hole plates were boiled in hot water at 2 atmospheres and 100°C for 24 hours, and the number of failed pixels of the PCBs before and after boiling was compared.

[0107] The airtightness calculation method in Table 1 is: number of failed pixels ÷ total number of pixels × 1,000,000. The lower the airtightness value in the table, the better the airtightness of the PCB board.

[0108] Table 1

[0109] Hermeticity (based on the percentage of device failures in ppm after packaging) Example 1 ≤20ppm Example 2 ≤20ppm Example 3 ≤20ppm Example 4 ≤20ppm Example 5 ≤40ppm Example 6 ≤50ppm Example 7 ≤5ppm Comparative Example 1 ≤20ppm Comparative Example 2 ≤20ppm Comparative Example 3 ≤600ppm Comparative Example 4 ≤1000ppm

[0110] In summary, the PCB board for improving the airtightness of through-hole boards provided by the present invention improves the airtightness of the through-hole boards by depositing a nano-coating on the through-holes of the printed circuit board (PCB), avoiding or reducing the drawbacks of panel reliability failure caused by insufficient airtightness and other problems. In addition, it also improves the moisture resistance of the through-hole board.

[0111] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for manufacturing a via plated gas-tight (PCB) board, characterized in that, The preparation method comprises the following steps: (1) sequentially performing copper plating, oil plugging, dry film covering and dry film hole opening on a substrate with a through hole to obtain a first substrate; The position of the dry film hole opening corresponds to the position of the through hole; (2) preparing a first nickel-gold plating layer at the through hole of the first substrate obtained in step (1) to obtain a second substrate; (3) depositing a nano plating layer at the through hole of the second substrate obtained in step (2), and then removing the dry film and preparing a second nickel-gold plating layer to obtain the PCB plate for improving the air tightness of the through hole plate; The preparation process of the nano coating comprises a vapor deposition process; a vacuum degree in the vapor deposition process is greater than 1×10 3 mbar; and a growth temperature of the nano coating in the vapor deposition process is 130-160℃.

2. The production method according to claim 1, characterized by, The oil plugging in step (1) comprises plugging dry green oil into the through hole by using a printing machine.

3. The preparation method according to claim 2, characterized in that, The oil plugging in step (1) comprises drying.

4. The production method according to claim 3, characterized by, The drying temperature is 115-135°C.

5. The preparation method according to claim 3, characterized in that, The drying time is 30-60 min.

6. The method of claim 1, wherein, The first nickel-gold plating layer in step (2) comprises a nickel layer and a gold layer arranged in sequence.

7. The preparation method according to claim 6, characterized in that, The thickness of the nickel layer is ≥3.8 μm.

8. The preparation method according to claim 6, characterized in that, The thickness of the gold layer is ≥0.05 μm.

9. The method of claim 1, wherein, The preparation process of the first nickel-gold plating layer in step (2) comprises an electroplating process or a gold plating process.

10. The method of claim 1, wherein, The nano plating layer in step (3) comprises a silicon dioxide plating layer and / or an aluminum trioxide plating layer.

11. The method of claim 10, wherein, The thickness of the nano plating layer in step (3) is 0.05-0.1 μm.

12. The method of claim 1, wherein, After removing the dry film in step (3), the process further comprises sequentially performing pickling, water washing and drying.

13. The method of claim 12, wherein, The cleaning solution in the pickling comprises sulfuric acid and / or hydrochloric acid.

14. The method of claim 13, wherein, The acidity of the cleaning solution is 2-8%.

15. The preparation method according to claim 12, characterized in that, The pickling time is 10-30 s.

16. The method of claim 12, wherein, The water washing time is 20-60 s.

17. The method of claim 12, wherein, The drying temperature is 80-90°C.

18. The method of claim 12, wherein, The drying time is 15-40 s.

19. A via-in-ply (VIP) PCB board for improved gas tightness, the board comprising: The PCB plate for improving the air tightness of the through hole plate is obtained by using the preparation method in any one of claims 1-18.