High-precision circuit board processing technology

Abstract

The invention discloses a high-precision circuit board processing technology. The high-precision circuit board processing technology comprises the following steps: S1, manufacturing an inner layer core; s2, laminating and drilling are carried out; s3, outer layer manufacturing and surface treatment; s4, performing final detection and verification; the step S1 comprises the following steps: S11, adopting a copper-clad plate with a preset size; s12, carrying out chemical cleaning and plasma treatment on the copper-clad plate; s13, coating a high-resolution dry film, directly receiving CAD (Computer Aided Design) data, and directly scanning and exposing on the substrate by using an ultraviolet laser beam; s14, exposing a copper circuit needing to be thickened after developing, performing micro-etching coarsening, then performing pattern electroplating, and increasing the copper thickness of the circuit to a target value; and S15, after the thin copper substrate is etched off, the high-resolution AOI equipment is immediately used for 100% scanning. According to the processing technology of the high-precision circuit board, the ultra-thin copper foil is adopted, the amount of copper needing to be etched in the subsequent mSAP process is extremely small, and lateral erosion can be reduced to the maximum extent.

Description

Technical Field

[0001] This invention relates to the field of circuit board processing technology, and in particular to a high-precision circuit board processing technology. Background Technology

[0002] Printed circuit boards (PCBs), as the core carrier of electronic products, are a crucial basic component of the modern electronic information industry, playing a key role in connecting circuits. As electronic devices develop towards higher density and performance, the precision requirements for PCBs are constantly increasing. Currently, PCBs can be divided into two main categories based on their manufacturing processes: subtractive and additive methods. Traditional PCB production mainly uses subtractive processes, which are not only complex but also generate large amounts of wastewater, causing serious pollution. Furthermore, with increasingly higher levels of circuit integration, subtractive methods can no longer meet the requirements. Even using ultra-thin copper foil substrates, side etching remains a significant problem when fabricating fine circuits, and linewidth reduction is difficult. To address these issues, the semi-additive process (mSAP) has emerged and is widely used in fine circuit fabrication. However, in this process, electroplating copper deposition can easily lead to uneven plating thickness; differential etching removes the alloy layer slowly, resulting in side etching and circuit deformation; and incomplete removal of the alloy layer can cause short circuits. In the field of high-precision circuit board pattern transfer, laser direct imaging (LDI) technology has become the mainstream technology. Compared with traditional exposure technology, LDI technology does not require the use of physical masks. It directly receives CAD data and uses an ultraviolet laser beam to scan and expose the substrate, eliminating the mask diffraction problem and significantly improving resolution and alignment accuracy.

[0003] However, existing high-precision circuit board manufacturing technologies still have several limitations. First, thermal accumulation is the primary challenge in laser processing, especially in PI film and thin FPC cutting. Second, in the mSAP process, a slight step difference exists between the electroplated layer and the dry film, which can easily lead to secondary defects such as uneven solder wetting and blind via misalignment. Third, current process control mainly relies on offline sampling inspection, making real-time process adjustment impossible, which hinders further yield improvement. Regarding the integration of laser microvia and mSAP processes, existing technologies have not yet formed a complete process chain and closed-loop control system, resulting in high-precision circuit board production still facing problems such as poor consistency, unstable yield, and high costs.

[0004] Therefore, there is an urgent need to develop a new high-precision circuit board manufacturing method that can integrate laser microvia technology, mSAP process and intelligent closed-loop control system to fundamentally solve the limitations of existing technologies and meet the growing demand of high-end electronic devices for high-precision circuit boards. Summary of the Invention

[0005] Therefore, it is necessary to provide a high-precision circuit board processing technology to address the technical problem of insufficient integration between laser micro-via technology and mSAP process in existing high-precision circuit board processing technology.

[0006] A high-precision circuit board processing technology includes the following steps: S1, Inner Core Construction; S2, Lamination and Drilling; S3. Outer layer fabrication and surface treatment; S4. Final testing and verification.

[0007] In one embodiment, step S1 above includes the following steps: S11. Substrate preparation: Use copper-clad laminate of preset size with copper thickness ≤12μm; S12. Surface cleaning and activation: Chemical cleaning and plasma treatment are used on the copper-clad laminate to thoroughly remove organic matter and oxide layer from the surface of the copper-clad laminate and enhance subsequent adhesion. S13, LDI laser direct imaging: High-resolution dry film is coated, CAD data is directly received, and ultraviolet laser beam is used to scan and expose directly on the substrate, thereby avoiding mask diffraction problems, effectively improving resolution and alignment accuracy, and can automatically compensate for board warpage. S14. Development and Pattern Plating: After development, the copper lines that need to be thickened are exposed. Micro-etching is performed to roughen the lines, and then pattern plating is performed to increase the copper thickness of the lines to the target value. S15, AOI Intelligent Inspection and Compensation: After etching away the thin copper substrate, a high-resolution AOI device is immediately used for 100% scanning to detect defects such as open circuits and short circuits, while accurately measuring the line width and line spacing.

[0008] In one embodiment, in step S11 above, the copper clad laminate uses one of ultra-low profile copper foil and very low profile copper foil as a base; in another embodiment, the surface roughness (Rz) of the copper clad laminate is <1.5μm to provide a base for fine lines.

[0009] In one embodiment, in step S13 above, the high-resolution dry film can be replaced with liquid photosensitive ink.

[0010] In one embodiment, in step S14 above, the target value for the copper thickness of the line is set to 15-20 μm.

[0011] In one embodiment, step S15 above further includes the step of: uploading AOI data to the manufacturing execution system in real time, the manufacturing execution system analyzing linewidth deviation through algorithms, automatically adjusting the LDI exposure energy and focal length of subsequent boards, and sending fine-tuning parameter instructions to the etching machine to achieve closed-loop control and compensate for process fluctuations.

[0012] In one embodiment, step S2 above includes the following steps: S21. Pre-lamination positioning hole treatment: High-precision alignment holes are made by combining mechanical drilling and CO2 laser drilling of target holes on the substrate to avoid the influence of material expansion and contraction on subsequent alignment. S22. Lamination: A high-precision alignment press is used with a built-in CCD vision system to capture the target on the inner core board in real time, and then perform precise alignment before lamination. S23. Laser drilling: For blind buried holes, ultraviolet laser drilling machines are used for drilling. They have small spot size and small heat-affected zone, and can process even smaller micro-holes.

[0013] In one embodiment, in step S22 above, the lamination process uses a low-expansion-shrinkage prepreg and pre-baking to reduce thermal expansion during the lamination process.

[0014] In one embodiment, in step S23 above, the laser drilling process employs multi-wavelength composite laser technology, using UV laser to process the copper window and CO2 laser to process the dielectric layer, thereby improving efficiency and hole quality.

[0015] In one embodiment, step S3 above includes the following steps: S31, Hole Metallization: The circuit board is de-drilled, chemically deposited copper, and electroplated throughout the board to ensure uniform deposition on the hole walls; S32, Outer layer pattern transfer: Repeat the inner layer mSAP process (coating, LDI, development, pattern plating, etching, AOI inspection and feedback). S33. Solder mask and surface treatment: LDI technology is used to create a solder mask layer on the circuit board to achieve precise pad opening and avoid pad contamination caused by traditional mask alignment deviation. Then, a planarization surface treatment process is carried out to facilitate the soldering of ultra-fine pitch components.

[0016] In one embodiment, in step S33 above, the planarization surface treatment process employs either electroplating of nickel-palladium-gold or chemical tin plating.

[0017] In one embodiment, step S4 above includes the following steps: S41. Automated Optical Shape Inspection (AOI): Performs 100% outer layer circuitry inspection on the circuit board; S42. Electrical Testing (E-Test): Employs a flying probe tester to adapt to the high-precision board production mode of multiple varieties and small batches.

[0018] S43. Two-dimensional measuring instrument (CMM): Performs spot checks on the line width and hole spacing dimensions of key locations on the circuit board, and re-verifies AOI and process capabilities.

[0019] The aforementioned high-precision circuit board processing technology utilizes ultra-thin copper foil, requiring minimal copper etching during subsequent mSAP processes. This minimizes side etching and ensures the final linewidth is highly consistent with the LDI exposure design. Furthermore, LDI laser direct imaging avoids the light diffraction problems caused by the gap between the mask and substrate in traditional contact exposure, clearly projecting the edges of the circuit pattern onto the photosensitive film, directly improving the ultimate resolution. Simultaneously, imaging directly from CAD data eliminates deformation, contamination, and alignment errors caused by mask manufacturing, handling, and use, resolving alignment difficulties due to warping in large-size boards and effectively improving interlayer alignment accuracy. Chemical cleaning removes grease and contaminants, while plasma treatment provides deeper activation. It micro-etches the copper surface, creating uniform micro-roughness and altering surface chemical bond energies, significantly enhancing the adhesion between the dry film and the copper surface. Detailed Implementation

[0020] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0021] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0022] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0023] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0024] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0025] This invention discloses a high-precision circuit board processing technology, which includes the following steps: S1, Inner Core Construction; S2, Lamination and Drilling; S3. Outer layer fabrication and surface treatment; S4. Final testing and verification.

[0026] Specifically, step S1 above includes the following steps: S11. Substrate preparation: Use copper-clad laminate of preset size with copper thickness ≤12μm; S12. Surface cleaning and activation: Chemical cleaning and plasma treatment are used on the copper-clad laminate to thoroughly remove organic matter and oxide layer from the surface of the copper-clad laminate and enhance subsequent adhesion. S13, LDI laser direct imaging: High-resolution dry film is coated, CAD data is directly received, and ultraviolet laser beam is used to scan and expose directly on the substrate, thereby avoiding mask diffraction problems, effectively improving resolution and alignment accuracy, and can automatically compensate for board warpage. S14. Development and Pattern Plating: After development, the copper lines that need to be thickened are exposed. Micro-etching is performed to roughen the lines, and then pattern plating is performed to increase the copper thickness of the lines to the target value. S15, AOI Intelligent Inspection and Compensation: After etching away the thin copper substrate, a high-resolution AOI device is immediately used for 100% scanning to detect defects such as open circuits and short circuits, while accurately measuring the line width and line spacing.

[0027] Specifically, in one embodiment, in step S11 above, the copper clad laminate uses one of ultra-low profile copper foil and very low profile copper foil as a base; in another embodiment, the surface roughness (Rz) of the copper clad laminate is <1.5μm to provide a base for fine lines.

[0028] Specifically, in one embodiment, in step S13 above, the high-resolution dry film can be replaced with liquid photosensitive ink.

[0029] Specifically, in one embodiment, in step S14 above, the target value for the copper thickness of the line is set to 15-20 μm.

[0030] Specifically, in one embodiment, step S15 above further includes the step of: uploading AOI data to the manufacturing execution system in real time, the manufacturing execution system analyzing linewidth deviation through algorithms, automatically adjusting the LDI exposure energy and focal length of subsequent boards, and sending fine-tuning parameter instructions to the etching machine to achieve closed-loop control and compensate for process fluctuations.

[0031] Furthermore, step S2 above includes the following steps: S21. Pre-lamination positioning hole treatment: High-precision alignment holes are made by combining mechanical drilling and CO2 laser drilling of target holes on the substrate to avoid the influence of material expansion and contraction on subsequent alignment. S22. Lamination: A high-precision alignment press is used with a built-in CCD vision system to capture the target on the inner core board in real time, and then perform precise alignment before lamination. S23. Laser drilling: For blind buried holes, ultraviolet laser drilling machines are used for drilling. They have small spot size and small heat-affected zone, and can process even smaller micro-holes.

[0032] Specifically, in one embodiment, in step S22 above, the lamination process uses a low-expansion-shrinkage prepreg and pre-baking to reduce thermal expansion during the lamination process.

[0033] Specifically, in one embodiment, in step S23 above, the laser drilling process uses multi-wavelength composite laser technology, with UV laser processing of the copper window and CO2 laser processing of the dielectric layer, to improve efficiency and hole quality.

[0034] Furthermore, step S3 above includes the following steps: S31, Hole Metallization: The circuit board is de-drilled, chemically deposited copper, and electroplated throughout the board to ensure uniform deposition on the hole walls; S32, Outer layer pattern transfer: Repeat the inner layer mSAP process (coating, LDI, development, pattern plating, etching, AOI inspection and feedback). S33. Solder mask and surface treatment: LDI technology is used to create a solder mask layer on the circuit board to achieve precise pad opening and avoid pad contamination caused by traditional mask alignment deviation. Then, a planarization surface treatment process is carried out to facilitate the soldering of ultra-fine pitch components.

[0035] Specifically, in one embodiment, in step S33 above, the planarization surface treatment process uses either electroplating of nickel, palladium, and gold or chemical tin plating.

[0036] Furthermore, step S4 above includes the following steps: S41. Automated Optical Shape Inspection (AOI): Performs 100% outer layer circuitry inspection on the circuit board; S42. Electrical Testing (E-Test): Employs a flying probe tester to adapt to the high-precision board production mode of multiple varieties and small batches.

[0037] S43. Two-dimensional measuring instrument (CMM): Performs spot checks on the line width and hole spacing dimensions of key locations on the circuit board, and re-verifies AOI and process capabilities.

[0038] In summary, the high-precision circuit board processing technology disclosed in this invention utilizes ultra-thin copper foil, requiring minimal copper etching during subsequent mSAP processes. This minimizes side etching and ensures the final linewidth is highly consistent with the LDI exposure design. Furthermore, direct LDI laser imaging avoids the light diffraction problems caused by the gap between the mask and substrate in traditional contact exposure, clearly projecting the edges of the circuit pattern onto the photosensitive film, directly improving the ultimate resolution. Simultaneously, imaging directly from CAD data eliminates deformation, contamination, and alignment errors caused by mask manufacturing, handling, and use, solving the alignment difficulties caused by warping in large-size boards and effectively improving interlayer alignment accuracy. Chemical cleaning removes grease and contaminants, while plasma treatment provides deeper activation. It micro-etches the copper surface, creating uniform micro-roughness and altering surface chemical bond energies, significantly enhancing the adhesion between the dry film and the copper surface.

[0039] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0040] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A high-precision circuit board processing technology, characterized in that, It comprises the following steps: S1, inner layer core making; S2, laminating and drilling; S3, outer layer making and surface treatment; S4, final detection and verification; The step S1 comprises the following steps: S11, substrate preparation: using copper-clad plate with preset size, copper thickness ≤12μm; S12, surface cleaning and activation: using chemical cleaning and plasma treatment on the copper-clad plate; S13, LDI laser direct imaging: coating high-resolution dry film, directly receiving CAD data, and directly scanning and exposing on the substrate with ultraviolet laser beam; S14, development and pattern plating: after development, the copper circuit that needs to be thickened is exposed, micro-etching roughening is carried out, and then pattern plating is carried out, so that the circuit copper thickness is added to the target value; S15, AOI intelligent detection and compensation: after etching away the thin copper substrate, immediately use high-resolution AOI equipment for 100% scanning, while detecting defects such as short circuit, accurately measure line width and spacing value.

2. The high-precision circuit board processing process according to claim 1, wherein, In the step S11, the copper-clad plate uses one of ultra-low profile copper foil and extremely low profile copper foil; in another embodiment, the surface roughness (Rz) of the copper-clad plate is <1.5μm, so as to provide a base for fine circuits.

3. The high-precision circuit board processing process of claim 1, wherein, In the step S13, the high-resolution dry film can be replaced by liquid photosensitive ink.

4. The high-precision circuit board processing process of claim 1, wherein, In the step S14, the target value of the circuit copper thickness is set to 15-20μm.

5. The high-precision circuit board processing process according to claim 1, wherein, In the step S15, it also includes the step of uploading AOI data to the manufacturing execution system in real time, the manufacturing execution system analyzes the line width deviation through algorithm, automatically adjusts the LDI exposure energy and focal length of the subsequent plate, sends fine tuning parameter instructions to the etching machine, realizes closed-loop control, and compensates for process fluctuations.

6. The high-precision circuit board processing process according to claim 1, wherein, The step S2 comprises the following steps: S21, positioning hole treatment before laminating: using mechanical drilling and CO2 laser drilling target hole combination on the substrate to make high-precision positioning hole, avoiding the influence of material expansion and contraction on subsequent positioning; S22, laminating: using high-precision positioning press, built-in CCD vision system, real-time capturing target on the inner layer core plate, precise positioning, and then implementing compression; S23, laser drilling: for blind buried hole, using ultraviolet laser drilling machine for drilling work, which has small spot and small heat affected zone, and can process smaller micro holes.

7. The high-precision circuit board processing process according to claim 6, wherein, In the step S22, the laminating process uses low-swelling prepreg, which is pre-treated by baking to reduce thermal expansion during compression.

8. The high-precision circuit board processing process according to claim 6, wherein, In the step S23, the laser drilling process uses multi-wavelength composite laser technology, UV laser processes copper window, and CO2 laser processes medium layer, which improves efficiency and hole quality.

9. The high-precision circuit board processing process of claim 1, wherein, The step S3 comprises the following steps: S31, hole metallization: removing drill dirt, chemical copper deposition and full-plate plating on the circuit board to ensure uniform deposition of hole wall; S32, outer layer pattern transfer: repeating the mSAP process of the inner layer (coating film, LDI, development, pattern plating, etching, AOI detection and feedback); S33, solder resist and surface treatment: using LDI technology to make solder resist layer on the circuit board to realize precise pad windowing, avoid pad contamination caused by traditional mask alignment deviation, and then carry out planarization surface treatment process, which is beneficial to the welding of ultra-fine pitch components.

10. The high-precision circuit board processing process of claim 1, wherein, The step S4 includes the following steps: S41, automatic optical shape detection (AOI): 100% outer circuit detection is performed on the circuit board; S42, electrical test (E-Test): a flying probe tester is used, which is suitable for the production mode of multiple varieties and small batches of high-precision boards; S43, two-dimensional measuring instrument (CMM): the line width and hole distance size of the key position of the circuit board are sampled and inspected, and the AOI and process capability are re-verified.