Processing method of third-order special blind slot printed board and PCB binding plate thereof
Patent Information
- Application Number
- CN202611054152.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-15
- Publication Date
- 2026-10-20
AI Technical Summary
这种复杂的叠层结构对加工工艺提出了极高的要求，针对此类含有复杂盲槽结构的PCB板，传统的主流制作工艺一种是在目标层先开槽后压合，另一种是先压合后开槽，这两种传统工艺易出现压合溢胶、分层等质量问题
采用“控深+激光刻蚀介质成槽工艺+激光烧锡”的组合工艺，在母板压合后制作金属化的三阶盲槽，镀铜锡后通过激光烧锡制作三阶盲槽底部的线路，三阶盲槽内的阻焊层在外层使用盲槽内的mark点定位喷印制作，然后，在外层线路后加工一阶盲槽和二阶盲槽，利用大盲槽控深和激光复合成型技术，实现多阶盲槽差异化加工工艺组合，实现激光烧锡在大尺寸盲槽底部的线路制作应用，有效实现通过工艺改进来提高加工效率及加工质量，避免盲槽溢胶和分层的质量问题，无需考虑溢胶及大尺寸盲槽使用PI胶带来的分层爆板问题，有效提升良品率和加工质量。
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Abstract
Description
Technical Field
[0001] This invention relates to PCB board processing technology, and in particular to a processing method for a three-stage special blind slot printed circuit board and its PCB bonding board. Background Technology
[0002] With the rapid development of electronic technology, electronic products are rapidly evolving towards miniaturization, high-density wiring, high flatness, high integration, and multifunctionality. These products are becoming increasingly thinner, lighter, and smaller, placing increasingly higher demands on printed circuit boards (PCBs). To meet the requirements of embedded component mounting, precise positioning, and signal shielding, blind slot structures are widely used in PCB design. A blind slot is a recessed structure that extends inward from only one surface of the circuit board without penetrating the entire board thickness, effectively improving space utilization.
[0003] As electronic products trend towards miniaturization and high-density wiring, the need to achieve complex circuit connections within a limited area is becoming increasingly urgent, rendering conventional first-order blind slot technology inadequate. Consequently, a complex "second-order special blind slot" printed circuit board has emerged in some highly integrated products. This type of PCB typically contains blind slot structures at varying depths. For example, a first-order blind slot is formed on the substrate surface, while a second-order blind slot with a depth less than the first-order blind slot is formed in the edge region. The bottom of the first-order blind slot also incorporates metallized vias for interlayer connections. This complex stacked structure places extremely high demands on the manufacturing process. For PCBs with such complex blind slot structures, the traditional mainstream manufacturing processes are either slotting the target layer before lamination or lamination before slotting. Both of these traditional processes are prone to quality issues such as adhesive overflow and delamination during lamination.
[0004] In summary, the existing blind slot processing methods for printed circuit boards have made it difficult to improve the processing yield of stepped blind slots for a long time. Moreover, the existing processing technology is relatively complex and difficult to control, which can no longer meet the needs of modern electronic products. There is an urgent need to further research and improve the existing processing technology to improve processing efficiency and processing quality. Summary of the Invention
[0005] This invention provides a method for processing a three-stage special blind slot printed circuit board and its PCB bonding board. By combining depth control, laser etching medium slotting process and laser soldering process, the processing efficiency and quality are effectively improved through process improvement, avoiding the quality problems of blind slot overflow and delamination. It eliminates the need to consider the problems of overflow and delamination caused by using PI glue in large-size blind slots, effectively improving yield and processing quality.
[0006] The technical solution adopted by this invention to solve its technical problem is: The technical solution adopted in at least one embodiment of the present invention is as follows: In a first aspect, the present invention provides a method for processing a three-tier special blind slot printed circuit board. The three-tier special blind slot printed circuit board has a first-tier blind slot located at the bottom of a second-tier blind slot on the substrate surface. The first-tier and second-tier blind slots are small in size and have uniformly distributed circuitry inside. The third-tier blind slot on the substrate surface of the three-tier special blind slot printed circuit board has a different depth than the first-tier and second-tier blind slots, and the sidewalls of the third-tier blind slot are metallized. The processing method includes the following steps: S1, Lamination: The inner core board and the prepreg are stacked and pressed together to form a multilayer printed circuit board substrate; S2, Depth Control and Laser Milling of Blind Grooves: The third-order blind groove was machined by mechanical depth-controlled milling followed by laser milling. S3, Plating Copper: The sidewalls of the three-stage blind slot are subjected to copper plating after milling. S4, External Light Imaging and Pattern Electroplating Copper-Tin: External light imaging is performed on the substrate surface of the printed circuit board to create outer layer circuit patterns on the surface; Then, patterned copper-tin plating is performed on the substrate surface of the printed circuit board after external light imaging and the sidewalls and bottom surface of the three-level blind trench after copper plating. S5, Laser Soldering: The bottom circuitry of the third-order blind slot is fabricated using laser soldering. S6, alkaline etching The bottom of the three-stage blind trench and the substrate surface of the printed circuit board are subjected to alkaline etching to remove excess copper layer and form outer layer circuitry. S7, Laser milling of blind grooves After processing the outer layer circuitry on the substrate surface of the printed circuit board, the second-order blind trench and the first-order blind trench are processed by laser milling, with the first-order blind trench located at the bottom of the second-order blind trench. S8, Printed Solder Mask The solder resist layer inside the three-stage blind groove is left to be printed on the outer layer using the mark points inside the blind groove after the outer layer solder resist process is completed, thus realizing the processing of the three-stage blind groove.
[0007] Furthermore, the third-order blind groove occupies no less than 2 / 3 of the entire plate surface.
[0008] Furthermore, the depth of the third-order blind groove is greater than the depth of the first-order blind groove.
[0009] Furthermore, the first-order blind groove and the second-order blind groove are interconnected and together form a stepped blind groove.
[0010] Furthermore, the sidewalls of both the first-order blind groove and the second-order blind groove are in a non-metallic state.
[0011] Furthermore, the horizontal distance between the inner wall of the first-order blind groove and the inner wall of the second-order blind groove is not less than 75 μm.
[0012] Furthermore, the depth ratio of the three-order blind groove is not less than 1:1, that is, the depth of the blind groove is equal to or greater than its opening width.
[0013] Furthermore, in steps S2 and S7, the processing parameters for laser milling of blind grooves are as follows: mask thickness is 1.8~2.1mm, laser pulse width is 5~8μs, laser energy is 3.2~8.5MJ, number of laser shots is 2~8, laser groove wall slope is ≤15μm, and groove wall roughness is ≤15μm.
[0014] Furthermore, the number of layers in the third-order special blind slot printed circuit board is 4 to 20.
[0015] Secondly, the present invention provides a PCB bonding board, which is manufactured using the above-mentioned processing method for a three-stage special blind slot printed circuit board.
[0016] The beneficial effects of this invention are: A combined process of "depth control + laser etching medium trenching + laser soldering" is adopted to create metallized three-tier blind trenches after the motherboard is laminated. After copper-tin plating, the circuitry at the bottom of the three-tier blind trenches is created by laser soldering. The solder mask layer inside the three-tier blind trenches is positioned and printed on the outer layer using the mark points inside the blind trenches. Then, first-tier and second-tier blind trenches are processed after the outer layer circuitry. By utilizing the depth control of large blind trenches and laser composite forming technology, a multi-tier blind trench differentiated processing process combination is realized. This enables the application of laser soldering in the circuitry at the bottom of large-size blind trenches. It effectively improves processing efficiency and quality through process improvement, avoids quality issues such as glue overflow and delamination in blind trenches, and eliminates the need to consider glue overflow and delamination / explosion issues caused by using PI glue in large-size blind trenches. This effectively improves yield and processing quality.
[0017] Moreover, compared with existing conventional blind slot processing technology, the first-order blind slot is located at the bottom of the second-order blind slot and is interconnected to form a stepped blind slot structure with a stacked design. Since the first-order and second-order blind slots are smaller in size and have circuits inside, the laser etching process can effectively avoid the problem of adhesive residue overflowing to the pads in the traditional process. In addition, the internal circuits of the first-order and second-order blind slots are better than those of the core board layer which are prefabricated.
[0018] Meanwhile, the size of the three-tier blind trench occupies approximately 2 / 3 of the total board size. If processed using conventional PI resist technology, it is highly susceptible to delamination or board breakage. In this invention, the three-tier blind trench is formed using a "controlled depth milling + laser etching trenching process," eliminating the need to consider resist overflow and the delamination and breakage issues caused by using PI adhesive in large-size blind trenches. Furthermore, the fine lines at the bottom of the three-tier blind trench are processed using a laser soldering process, while the solder resist layer inside the trench is created using inkjet printing technology after the outer solder resist process is completed.
[0019] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of the structure after the lamination step in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure after the third-order blind slot depth control + laser milling step in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure after the three-stage blind trench copper plating step in an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure after the copper-tin plating step in the three-stage blind trench in an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure after the laser tin burning step in the third-order blind slot in an embodiment of the present invention; Figure 6 This is a schematic diagram of the structure after the alkaline etching step of the three-stage blind trench in an embodiment of the present invention; Figure 7 This is a schematic diagram of the structure after the laser blind slotting steps in the first-order and second-order blind slotting embodiments of the present invention; Figure 8 This is a schematic diagram of the structure after the three-stage blind slot solder resist printing step in an embodiment of the present invention.
[0021] The reference numerals are as follows: 10 for first-order blind slot, 20 for second-order blind slot, 30 for third-order blind slot, and 40 for solder mask. Detailed Implementation
[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0023] In the description of this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. Terms such as "center," "upper," "lower," "left," "right," "front," "rear," "vertical," "horizontal," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention.
[0024] Furthermore, if the terms "first," "second," "first-order," "second-order," "third-order," etc. are used only to distinguish technical features, they should not be interpreted as indicating or implying relative importance, or implicitly indicating the number of technical features indicated, or implicitly indicating the order of the technical features indicated.
[0025] Furthermore, in the description of this invention, unless otherwise explicitly defined, terms such as "set," "install," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of two components. For those skilled in the art, the specific meaning of the above terms in this invention can be reasonably determined in conjunction with the specific content of the technical solution.
[0026] A method for processing a third-order special blind slot printed circuit board, such as... Figure 8 As shown, the first-order blind groove 10 on the substrate surface of the three-order special blind groove printed circuit board is located at the bottom of the second-order blind groove 20. The first-order blind groove 10 and the second-order blind groove 20 are small in size and have lines evenly distributed inside. The sidewalls of the first-order blind groove 10 and the second-order blind groove 20 are non-metallized. The third-order blind groove 30 on the substrate surface of the three-order special blind groove printed circuit board has a different depth than the first-order blind groove 10 and the second-order blind groove 20. The sidewalls of the third-order blind groove 30 are metallized. The depth of the third-order blind groove 30 is greater than the depth of the first-order blind groove 10 and the third-order blind groove 30 occupies 2 / 3 of the entire board surface size. In this embodiment, the depth ratio of the third-order blind groove 30 is 1:1, that is, the depth of the blind groove is equal to its opening width. The processing method includes the following steps: S1, Lamination: like Figure 1 As shown, the inner core board and the prepreg are stacked and pressed together to form a multilayer printed circuit board substrate; S2, Depth Control and Laser Milling of Blind Grooves: like Figure 2 As shown, a third-order blind groove 30 was machined by mechanically controlling the depth of the blind groove and then laser milling the blind groove. In laser milling of blind grooves, the processing parameters for laser burning grooves are: mask thickness of 1.8~2.1mm, laser pulse width of 5~8μs, laser energy of 3.2~8.5MJ, number of laser shots of 2~8, groove wall slope of ≤15μm, and groove wall roughness of ≤15μm. S3, Plating Copper: like Figure 3 As shown, the sidewall of the three-stage blind groove 30 after milling is subjected to copper plating. S4, External Light Imaging and Pattern Electroplating Copper-Tin: like Figure 4 As shown, external light imaging is performed on the substrate surface of the printed circuit board to create outer layer circuit patterns on the surface. Then, patterned copper-tin plating is performed on the substrate surface of the printed circuit board after external light imaging and the sidewalls and bottom of the three-stage blind trench 30 after copper plating. S5, Laser Soldering: like Figure 5 As shown, the bottom circuit of the third-order blind slot 30 is fabricated using laser soldering. S6, alkaline etching like Figure 6 As shown, alkaline etching is performed on the bottom of the third-order blind trench 30 and the substrate surface of the printed circuit board to remove excess copper layer and form outer layer circuitry. S7, Laser milling of blind grooves like Figure 7 As shown, after processing the outer layer circuitry on the substrate surface of the printed circuit board, a second-order blind trench 20 and a first-order blind trench 10 are processed by laser milling. The first-order blind trench 10 is located at the bottom of the second-order blind trench 20, and the first-order blind trench 10 and the second-order blind trench 20 are interconnected and together form a stepped blind trench. The horizontal distance between the inner sidewall of the first-order blind trench 10 and the inner sidewall of the second-order blind trench 20 is not less than 75μm. In this way, when the second laser milling is performed, the copper foil at the bottom of the second-order blind trench 20 can effectively prevent the insulating substrate below from being damaged, thus ensuring the quality of the non-metallic first-order blind trench 10 obtained in the subsequent process.
[0027] Furthermore, in laser milling of blind grooves, the processing parameters for laser burning grooves are as follows: mask thickness is 1.8~2.1mm, laser pulse width is 5~8μs, laser energy is 3.2~8.5MJ, number of laser shots is 2~8, laser groove wall slope is ≤15μm, and groove wall roughness is ≤15μm.
[0028] S8, Printed Solder Mask like Figure 8 As shown, the solder resist layer 40 inside the three-stage blind groove 30 is left to be manufactured by marking the mark points inside the blind groove after the outer layer solder resist process is completed, thus realizing the processing of the three-stage blind groove 30.
[0029] In this embodiment, the first-order blind trench 10 is located at the bottom of the second-order blind trench 20 and they are interconnected to form a stepped blind trench structure with a stacked design. The internal circuitry of the first-order blind trench 10 and the second-order blind trench 20 is prefabricated before the core board layer. Since the first-order blind trench 10 and the second-order blind trench 20 are small in size and have circuitry inside, they are processed by laser etching trenching process, which can effectively avoid the problem of adhesive residue overflowing to the solder pads in the traditional process.
[0030] Meanwhile, the size of the three-tier blind slot 30 accounts for approximately 2 / 3 of the total board size. If processed using the existing conventional PI resist process, it is highly susceptible to delamination or board breakage. In this invention, the three-tier blind slot 30 is formed using a "controlled depth milling + laser etching slot forming process," eliminating the need to consider the issues of adhesive overflow and delamination / breakage caused by using PI adhesive in large-size blind slots. Furthermore, the fine lines at the bottom of the three-tier blind slot 30 are processed using a laser soldering process, while the solder resist layer inside the slot is left to be fabricated using inkjet printing technology after the outer solder resist process is completed. This effectively improves processing efficiency and quality through process improvement, avoids quality issues such as adhesive overflow and delamination in blind slots, and effectively improves yield and processing quality.
[0031] The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Except for the cases listed in the specific embodiments, all equivalent changes made in accordance with the methods and principles of the present invention should be covered within the protection scope of the present invention.
Claims
1. A method for processing a three-stage special blind slot printed circuit board, characterized in that, The first-order blind trench on the substrate surface of the three-order special blind trench printed circuit board is located at the bottom of the second-order blind trench. The first-order and second-order blind trenches are small in size and have lines evenly distributed inside. The third-order blind trench on the substrate surface of the three-order special blind trench printed circuit board has a different depth than the first-order and second-order blind trenches. The sidewalls of the third-order blind trench are metallized. The processing method includes the following steps: S1, Lamination: The inner core board and the prepreg are stacked and pressed together to form a multilayer printed circuit board substrate; S2, Depth Control and Laser Milling of Blind Grooves: The third-order blind groove was machined by mechanical depth-controlled milling followed by laser milling. S3, Plating Copper: The sidewalls of the three-stage blind slot are subjected to copper plating after milling. S4, External Light Imaging and Pattern Electroplating with Copper and Tin: External light imaging is performed on the substrate surface of the printed circuit board to create outer layer circuit patterns on the surface; Then, patterned copper-tin plating is performed on the substrate surface of the printed circuit board after external light imaging and the sidewalls and bottom surface of the three-level blind trench after copper plating. S5, Laser Soldering: The bottom circuitry of the third-order blind slot is fabricated using laser soldering. S6, alkaline etching The bottom of the three-stage blind trench and the substrate surface of the printed circuit board are subjected to alkaline etching to remove excess copper layer and form outer layer circuitry. S7, Laser milling of blind grooves After processing the outer layer circuitry on the substrate surface of the printed circuit board, the second-order blind trench and the first-order blind trench are processed by laser milling, with the first-order blind trench located at the bottom of the second-order blind trench. S8, Printed Solder Mask The solder resist layer inside the three-stage blind groove is left to be printed on the outer layer using the mark points inside the blind groove after the outer layer solder resist process is completed, thus realizing the processing of the three-stage blind groove.
2. The processing method of a three-stage special blind slot printed circuit board according to claim 1, characterized in that, The third-order blind groove occupies no less than 2 / 3 of the entire plate surface.
3. A processing method for a three-stage special blind slot printed circuit board according to claim 1 or 2, characterized in that, The depth of the third-order blind groove is greater than the depth of the first-order blind groove.
4. The processing method of a three-stage special blind slot printed circuit board according to claim 1, characterized in that, The first-order blind groove and the second-order blind groove are connected and together form a stepped blind groove.
5. A method for processing a three-stage special blind slot printed circuit board according to claim 1 or 4, characterized in that, The sidewalls of both the first-order blind groove and the second-order blind groove are in a non-metallic state.
6. The processing method of a three-stage special blind slot printed circuit board according to claim 4, characterized in that, The horizontal distance between the inner wall of the first-order blind groove and the inner wall of the second-order blind groove is not less than 75 μm.
7. The processing method of a three-stage special blind slot printed circuit board according to claim 1, characterized in that, The depth ratio of the three-dimensional blind groove is not less than 1:1, that is, the depth of the blind groove is equal to or greater than its opening width.
8. The processing method of a three-stage special blind slot printed circuit board according to claim 1, characterized in that, In steps S2 and S7, the processing parameters for laser milling of blind grooves are as follows: mask thickness is 1.8~2.1mm, laser pulse width is 5~8μs, laser energy is 3.2~8.5MJ, number of laser shots is 2~8, laser groove wall slope is ≤15μm, and groove wall roughness is ≤15μm.
9. The processing method of a three-stage special blind slot printed circuit board according to claim 1, characterized in that, The number of layers in the third-order special blind slot printed circuit board is 4 to 20.
10. A PCB bonding board, characterized in that, The PCB bonding board is manufactured using the processing method of any one of claims 1 to 8 for a three-stage special blind slot printed circuit board.