Slotting method for DDR5 product

Abstract

The invention discloses a slotting method of a DDR5 product, and relates to the technical field of packaging substrates. The method comprises the following steps: obtaining a copper-clad substrate, and drilling the copper-clad substrate; manufacturing a circuit and a lead on the surface of the copper-clad substrate; arranging a solder mask layer on the surface of the copper-clad substrate, and windowing the solder mask layer to expose a bonding pad and a lead; attaching a photosensitive dry film on the surface of the solder mask, exposing and developing the photosensitive dry film, exposing the bonding pad, and covering the lead; electroplating a soft gold layer on the bonding pad; removing the photosensitive dry film, and removing the lead through alkaline etching; carrying out layered groove milling on the copper-clad substrate by adopting a left-handed double-edged cutter to form an open groove; carrying out plate milling on the copper-clad substrate to form a formed small plate; and cleaning, detecting and packaging the formed small plate. According to the method provided by the embodiment of the invention, the grooving quality can be improved, and the problems of burr generation or substrate cracking and the like are avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of packaging substrates, and in particular to a slotting method for DDR5 products. Background Art

[0002] In the production process of DDR5 products, it is necessary to fabricate gold fingers so that the DDR5 products can achieve electrical connection with the motherboard through the gold fingers. At the same time, when fabricating the gold fingers, it is also necessary to fabricate slots as the physical interfaces of the gold fingers. Currently, during the process of fabricating the slots, problems such as copper burrs or substrate cracking may occur. Summary of the Invention

[0003] The present invention aims to at least solve one of the technical problems existing in the prior art. For this purpose, the present invention provides a slotting method for DDR5 products, which can improve the slotting quality and avoid problems such as burr generation or substrate cracking.

[0004] On the one hand, the slotting method for DDR5 products according to an embodiment of the present invention includes the following steps: Obtain a copper-clad substrate and drill the copper-clad substrate; Fabricate circuits and leads on the surface of the copper-clad substrate; Set a solder mask layer on the surface of the copper-clad substrate and open a window in the solder mask layer to expose the pads and the leads; Attach a photosensitive dry film on the surface of the solder mask layer, and expose and develop the photosensitive dry film to expose the pads and cover the leads; Electroplate a soft gold layer on the pads; Remove the photosensitive dry film and remove the leads by alkaline etching; Use a left-handed double-edge cutter to perform layer milling on the copper-clad substrate to form a slot; Mill the copper-clad substrate to form a small formed board; Clean, inspect, and package the small formed board.

[0005] According to some embodiments of the present invention, the obtaining of the copper-clad substrate and drilling the copper-clad substrate includes: Obtain the copper-clad substrate by cutting, baking, and Panel2D on the original substrate; Reduce the copper on the surface of the copper-clad substrate; Perform mechanical drilling on the copper-clad substrate; Remove the glue residue generated after drilling through the Desmear process. According to some embodiments of the present invention, before electroplating the soft gold layer on the pads, it further includes: Perform pre-treatment of soft gold on the copper-clad substrate; Remove the oxide layer on the surface of the pad by micro-etching. According to some embodiments of the present invention, using a left-handed double-edge cutter to perform layer-by-layer milling on the copper-clad substrate to form a grooving, including: Using the left-handed double-edge cutter, perform clockwise layer-by-layer pre-milling on the copper-clad substrate at a first rotational speed and a first milling speed; After completing the layer-by-layer pre-milling, detect the wear of the left-handed double-edge cutter and compensate the parameters of the left-handed double-edge cutter; According to the compensated left-handed double-edge cutter, perform counterclockwise finish-milling on the copper-clad substrate at a second rotational speed and a second milling speed; the second rotational speed is less than the first rotational speed, and the second milling speed is greater than the first milling speed. According to some embodiments of the present invention, during grooving, the feed speed of the left-handed double-edge cutter is less than the retraction speed.

[0006] On the other hand, a grooving method for a DDR5 product according to an embodiment of the present invention includes the following steps: Obtain a copper-clad substrate and drill holes in the copper-clad substrate; Fabricate circuits and leads on the surface of the copper-clad substrate; Set a solder mask on the surface of the copper-clad substrate and open windows in the solder mask to expose the pads and the leads; Attach a first photosensitive dry film on the surface of the solder mask, and perform exposure and development on the first photosensitive dry film to expose some of the pads and cover the remaining pads and the leads; Electroplate a soft gold layer on the exposed part of the pads; Remove the first photosensitive dry film and attach a second photosensitive dry film on the surface of the solder mask; Perform exposure and development on the second photosensitive dry film to expose the leads; Remove the leads by alkaline etching and remove the second photosensitive dry film; Attach a third photosensitive dry film on the surface of the solder mask, and perform exposure and development on the third photosensitive dry film to expose the grooving positions; Use a left-handed double-edge cutter to perform grooving at the grooving positions to form a grooving; Remove the third photosensitive dry film, and perform milling on the copper-clad substrate to form a small formed board; Set an organic protective film on the surface of the pads without electroplated soft gold layer; Clean, detect, and package the small formed board.

[0007] On the other hand, a grooving method for a DDR5 product according to an embodiment of the present invention includes the following steps: Obtain a copper-clad substrate and drill holes in the copper-clad substrate; Fabricate circuits on the surface of the copper-clad substrate; Set a solder mask on the surface of the copper-clad substrate and open windows in the solder mask to expose the pads; Electroplate a soft gold layer on the pads; Attach a photosensitive dry film on the surface of the copper-clad substrate, and expose and develop the photosensitive dry film to expose the milling groove positions; Use a left-handed double-edged tool to perform layered milling in the milling groove positions to form slots; Remove the photosensitive dry film, and mill the copper-clad substrate to form small formed boards; Clean, inspect, and package the small formed boards.

[0008] On the other hand, the slotting method of the DDR5 product according to the embodiment of the present invention includes the following steps: Obtain a copper-clad substrate and drill holes in the copper-clad substrate; Fabricate circuits on the surface of the copper-clad substrate; Set a solder mask on the surface of the copper-clad substrate and open windows in the solder mask to expose the pads; Attach a first photosensitive dry film on the surface of the solder mask, and expose and develop the first photosensitive dry film to expose some of the pads and cover the remaining pads; Electroplate a soft gold layer on the exposed pads; Remove the first photosensitive dry film and attach a second photosensitive dry film on the surface of the solder mask; Expose and develop the second photosensitive dry film to expose the milling groove positions; Use a left-handed double-edged tool to perform layered milling in the milling groove positions to form slots; Remove the second photosensitive dry film, and mill the copper-clad substrate to form small formed boards; Set an organic protective film on the surface of the pads without electroplated soft gold layer; Clean, inspect, and package the small formed boards.

[0009] On the other hand, the slotting method of the DDR5 product according to the embodiment of the present invention includes the following steps: Obtain a copper-clad substrate and drill holes in the copper-clad substrate; Fabricate circuits on the surface of the copper-clad substrate; Set a solder mask on the surface of the copper-clad substrate and open windows in the solder mask to expose the pads; Electroplate a soft gold layer on the pads; Divide the copper-clad substrate into several large boards; Perform grooving on each of the large boards to form grooves. Mill each of the large boards to form a number of formed small boards. Clean, inspect, and package the formed small boards.

[0010] On the other hand, the grooving method for a DDR5 product according to an embodiment of the present invention includes the following steps: Obtain a copper-clad substrate and drill holes in the copper-clad substrate. Fabricate circuits on the surface of the copper-clad substrate. Set a solder mask on the surface of the copper-clad substrate and open windows in the solder mask to expose the pads. Set a photosensitive dry film on the surface of the copper-clad substrate, and expose and develop the photosensitive dry film to expose some of the pads and cover the remaining pads. Electroplate a soft gold layer on the exposed pads. Remove the photosensitive dry film and separate the copper-clad substrate to form a number of large boards. Perform grooving on each of the large boards to form grooves. Mill each of the large boards to form a number of formed small boards. Set an organic protective film on the surface of the pads without electroplated soft gold layer. Clean, inspect, and package the formed small boards.

[0011] The grooving method for a DDR5 product according to an embodiment of the present invention has at least the following beneficial effects: By using a left-handed double-edged tool to perform layered milling on the copper-clad substrate, the grooving accuracy and quality are improved, and the generation of burrs or the cracking of the substrate is avoided.

[0012] The additional aspects and advantages of the present invention will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of the present invention. Description of the Drawings

[0013] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, where: Figure 1 is a flowchart of the steps of the grooving method for a DDR5 product according to the first embodiment of the present invention; Figure 2 is a flowchart of the steps of the grooving method for a DDR5 product according to the second embodiment of the present invention; Figure 3 is a flowchart of the steps of the grooving method for a DDR5 product according to the third embodiment of the present invention; Figure 4Flowchart of the grooving method for the DDR5 product according to the fourth embodiment of the present invention; Figure 5 Flowchart of the grooving method for the DDR5 product according to the fifth embodiment of the present invention; Figure 6 Flowchart of the grooving method for the DDR5 product according to the sixth embodiment of the present invention. Detailed implementation manners

[0014] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are only used to explain the present application, and should not be construed as a limitation to the present application. For the step numbers in the following embodiments, they are only set for the convenience of description and explanation, and no limitation is imposed on the order between the steps. The execution order of each step in the embodiments can be adaptively adjusted according to the understanding of those skilled in the art.

[0015] In the description of the present invention, it should be understood that for the orientation description, such as the upper, lower, front, rear, left, right, etc., the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention.

[0016] The terms "first", "second", "third", "fourth", etc. in the specification and claims of the present invention and the accompanying drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but optionally further includes steps or units not listed, or optionally further includes other steps or units inherent to these processes, methods, products, or devices.

[0017] Referring to "embodiment" in the present invention means that the specific features, structures, or characteristics described in combination with the embodiment can be included in at least one embodiment of the present invention. The phrase appearing in various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0018] During the production process of DDR5 products, it is necessary to fabricate the gold fingers so that the DDR5 products can achieve electrical connection with the motherboard through the gold fingers. Meanwhile, when fabricating the gold fingers, it is also necessary to fabricate the slots as the physical interfaces for the gold fingers. Currently, during the process of fabricating the slots, problems such as the generation of copper burrs or substrate cracking may occur.

[0019] For this reason, the embodiments of the present invention provide a slotting method for DDR5 products. By using a left-handed double-edge cutter to perform layered milling on the copper-clad substrate, the slotting accuracy and quality are improved, and the generation of burrs or substrate cracking is avoided.

[0020] The following will describe in detail the slotting method for DDR5 products according to the embodiments of the present invention with reference to the accompanying drawings.

[0021] On the one hand, the embodiments of the present invention propose a slotting method for DDR5 products, as Figure 1 shown, the method includes the following steps: Step S100: Obtain a copper-clad substrate and drill holes in the copper-clad substrate; Specifically, the copper-clad substrate is used for subsequent fabrication of the package substrate. By performing mechanical drilling or laser drilling on the copper-clad substrate, through holes are formed on the copper-clad substrate. In this example, step S100 specifically includes the following four steps: Step S110: Obtain a copper-clad substrate by performing blanking, baking, and Panel2D on the original substrate; Step S120: Reduce the copper on the surface of the copper-clad substrate; Step S130: Perform mechanical drilling on the copper-clad substrate; Step S140: Remove the smear residue generated after drilling through the Desmear process.

[0022] First, perform blanking, cutting the original substrate into the required size according to the design specifications. After blanking, it is necessary to bake the copper-clad substrate to remove the moisture and stress inside the copper-clad substrate through high-temperature treatment, preventing deformation (such as board warping, etc.) caused by uneven heating in subsequent processes. The baking temperature is controlled at about 200°C. Then, perform Panel2D on the copper-clad substrate, that is, perform two-dimensional layout design, including paneling rules, tool board edges, and processing path optimization, etc. Subsequently, reduce the copper on the surface of the copper-clad substrate, leaving the copper thickness at 3.5 ± 0.5 μm. Reduce the copper foil thickness through chemical etching or mechanical grinding to make the line impedance and current-carrying capacity meet the design requirements, avoiding impedance mismatch or uneven heat dissipation caused by too thick a copper layer. Then, perform mechanical drilling on the copper-clad substrate to form a number of through holes. Subsequently, remove the smears generated after drilling through the Desmear process to ensure the tight bonding of the copper layer to the substrate when metallizing the hole wall later, avoiding problems such as copper plating voids or delamination in the hole, making the electroplated copper layer more evenly distributed, reducing impedance mutations, and improving signal transmission stability. After removing the smears, metallize the hole wall through the PTH process and copper plating to achieve interlayer conduction.

[0023] Step S200: Fabricate circuits and leads on the surface of the copper-clad substrate; Specifically, in order to fabricate circuits on the surface of the copper-clad substrate, first attach a photosensitive dry film to the surface of the copper-clad substrate. Then, expose and develop the photosensitive dry film to expose the copper layer in the area to be etched. Then, dissolve the exposed copper layer through a chemical solution to form the patterns of the circuits and leads. Finally, remove the photosensitive dry film. In this way, the fabrication of the circuits and leads is achieved. After fabricating the circuits, the copper-clad substrate can be subjected to AOI inspection to detect whether there are problematic circuits and mark and record them.

[0024] Step S300: Set a solder mask layer on the surface of the copper-clad substrate and open windows in the solder mask layer to expose the pads and leads; Specifically, after completing the fabrication of the circuits and leads, remove the copper surface contaminants (such as oxide layers, grease, etc.) through processes such as pickling to increase the surface roughness to enhance the ink adhesion. Then, evenly cover the surface of the copper-clad substrate with solder mask ink using screen printing, spraying, or photoplotting techniques. Remove the ink solvent through low-temperature baking (80 - 100°C) to make the solder mask ink in a semi-cured state; use ultraviolet light passing through a negative film to perform graphic exposure on the solder mask ink, and the unexposed area remains soluble; dissolve the uncured ink with an alkaline solution (such as 1% Na2CO3) to expose the pads and leads; finally, fully harden the solder mask layer through high-temperature baking (150 - 160°C) to form a stable insulating protective film. The solder mask layer can protect the non-welding areas, restrict the flow of molten solder, and at the same time, isolate moisture, dust, and chemical corrosion (such as acid and alkali mists), prevent the copper layer on the surface of the copper-clad substrate from oxidizing or the circuit from breaking, and improve the service life of the copper-clad substrate.

[0025] Step S400: Attach a photosensitive dry film to the surface of the solder mask layer, and expose and develop the photosensitive dry film to expose the pads and cover the leads; Specifically, by attaching a photosensitive dry film to the surface of the solder mask layer and exposing and developing the photosensitive dry film, the leads and other areas are protected by the photosensitive dry film, and only the pads are exposed, facilitating subsequent surface treatment of the pads.

[0026] Step S500: Electroplate a soft gold layer on the pads; By electroplating a soft gold layer on the pads, the welding reliability is improved and high-precision interconnection is supported. In this example, in order to improve the quality of the electroplated soft gold layer, before step S500, the following two steps are also included: Perform pretreatment of soft gold on the copper-clad substrate; Remove the oxide layer on the surface of the pads by micro-etching.

[0027] Specifically, through processes such as pickling and micro-etching, the oxide layer and contaminants on the surface of the pads are removed to ensure the adhesion of the electroplated layer. Then, using the electrochemistry deposition process, a pure gold or gold alloy layer is deposited on the surface of the pads, and the uniformity of the plating layer is adjusted by controlling the current density (0.5 - 2.0 A / dm²) and temperature (40 - 60 °C).‌

[0028] Step S600: Remove the photosensitive dry film and remove the leads by alkaline etching; After the electroplated soft gold layer is completed, remove the photosensitive dry film to expose the leads, and then remove the leads by alkaline etching.

[0029] Step S700: Use a left-handed double-edged cutter to perform layered milling on the copper-clad substrate to form a slot; It should be noted that before milling the slot, the cutter parameters need to be optimized to reduce the burrs at the slot opening. In this example, a left-handed double-edged cutter is used for milling the slot to reduce the cutting resistance, improve the quality of the milled slot, and reduce the accumulation of debris in the processing area; at the same time, through layered milling, the overall processing stress is significantly reduced, avoiding delamination or warping deformation of the board, improving the dimensional consistency, reducing the residue of burrs and debris‌, and improving the milling accuracy. In this example, step S700 specifically includes the following three steps: Step S710: Use a left-handed double-edged cutter to perform clockwise layered pre-milling on the copper-clad substrate at a first rotational speed and a first milling speed; Step S720: After completing the layered pre-milling, detect the wear of the left-handed double-edged cutter and compensate the parameters of the left-handed double-edged cutter; Step S730: According to the compensated left-handed double-edged cutter, perform counterclockwise finish milling on the copper-clad substrate at a second rotational speed and a second milling speed; the second rotational speed is less than the first rotational speed, and the second milling speed is greater than the first milling speed.

[0030] Specifically, when performing pre-milling of the groove, the pre-milling of the groove is carried out at the first rotational speed and the first milling speed, so as to remove most of the materials in the groove, reduce the cutting difficulty and the allowance fluctuation in the finish-milling stage, make the force on the finish-milling tool more uniform, and the groove width accuracy more accurate. At the same time, the pre-milling of the groove is carried out in a layered manner. By milling the groove multiple times, the overall machining stress is significantly reduced, avoiding delamination or warping deformation of the plate, improving the dimensional consistency, and avoiding defects such as burrs and cracks. After the pre-milling of the groove is completed, the wear of the left-handed double-edged tool is detected. Then, according to the degree of wear, the radius of the tool is compensated, so that the tool has higher accuracy when finish-milling the groove. It should be noted that when pre-milling the groove, the left-handed double-edged tool mills the groove in a clockwise order, with a relatively high rotational speed (about 42KR / min) and a relatively low milling speed (about 4mm / s); when finish-milling the groove, the left-handed double-edged tool mills the groove in a counterclockwise order, with a relatively low rotational speed (about 32KR / min) and a relatively high milling speed (about 6mm / s). By adjusting the rotational speed and the milling speed in different stages, the groove milling requirements in different stages are realized, thereby improving the groove milling quality. In addition, when pre-milling the groove in layers, the feed speed (about 4mm / s) of the left-handed double-edged tool is less than the retraction speed (about 300mm / s), thereby further improving the groove milling quality.

[0031] Step S800: Milling the copper-clad substrate to form a small formed plate; After the grooving is completed, the copper-clad substrate is milled to form a number of small formed plates, which are used as single products for subsequent shipment.

[0032] Step S900: Cleaning, inspecting and packaging the small formed plate.

[0033] After milling to form the small formed plate, the small formed plate is cleaned, then subjected to OQC inspection (Outgoing Quality Control), and then subjected to AVI inspection, PVS inspection, MVI inspection, etc. Finally, it is packaged and shipped.

[0034] According to the grooving method of the DDR5 product of the embodiment of the present application, first, after making the leads and pads, the leads are covered by a photosensitive dry film, and after plating the pads with soft gold, the photosensitive dry film is removed to expose the leads, thereby etching back the leads to avoid copper burrs during grooving; then, a left-handed double-edged tool is used to perform layered grooving on the copper-clad substrate, improving the grooving accuracy and quality, and avoiding the generation of burrs or the cracking of the substrate.

[0035] On the other hand, as Figure 2 shown, the present application also proposes another grooving method for the DDR5 product, and this method includes the following steps: Step S101: Obtain a copper-clad substrate and drill holes in the copper-clad substrate; Specifically, first, the raw substrate is cut into the required size according to the design specifications; after cutting, the copper-clad substrate needs to be baked to remove the moisture and stress inside the copper-clad substrate through high-temperature treatment, preventing deformation (such as board warping, etc.) caused by uneven heating during subsequent processes. The baking temperature is controlled at about 200 °C. Then, Panel2D is performed on the copper-clad substrate, that is, two-dimensional layout design is carried out, including paneling rules, tool board edges, and processing path optimization, etc. Subsequently, the surface of the copper-clad substrate is copper-reduced, and the copper thickness is retained at 3.5 ± 0.5 μm. The copper foil thickness is reduced through chemical etching or mechanical grinding to make the line impedance and current-carrying capacity meet the design requirements, avoiding impedance mismatch or uneven heat dissipation caused by too thick copper layer. Then, mechanical drilling is performed on the copper-clad substrate to form a number of through holes. Subsequently, the smears generated after drilling are removed through the Desmear process to ensure the tight bonding between the copper layer and the substrate when metallizing the hole wall later, avoiding problems such as copper plating voids or delamination in the holes, making the electroplated copper layer more evenly distributed, reducing impedance mutations, and improving signal transmission stability. After removing the smears, the hole wall is metallized through the PTH process and copper plating to achieve interlayer conduction.

[0036] Step S201: Fabricate circuits and leads on the surface of the copper-clad substrate; Specifically, in order to fabricate circuits on the surface of the copper-clad substrate, a photosensitive dry film is first attached to the surface of the copper-clad substrate. Then, the photosensitive dry film is exposed and developed to expose the copper layer in the area to be etched. Then, the exposed copper layer is dissolved by chemical liquid to form the patterns of circuits and leads. Finally, the photosensitive dry film is removed. In this way, the fabrication of circuits and leads is achieved. After fabricating the circuits, the copper-clad substrate can be subjected to AOI inspection to detect whether there are defective circuits and mark and record them.

[0037] Step S301: Set a solder mask layer on the surface of the copper-clad substrate and open windows in the solder mask layer to expose the pads and leads; Specifically, after the production of the circuit and leads, copper surface contaminants (such as oxide layers, grease, etc.) are removed through processes such as pickling to increase the surface roughness and enhance the ink adhesion. Then, the solder mask ink is evenly coated on the surface of the copper-clad substrate by screen printing, spraying or photoplotting technology. The ink solvent is removed by low-temperature baking (80 - 100 °C) to make the solder mask ink in a semi-cured state; the solder mask ink is pattern-exposed using ultraviolet light through a negative film, and the unexposed areas remain soluble; the uncured ink is dissolved with an alkaline solution (such as 1% Na2CO3) to expose the pads and leads; finally, the solder mask layer is completely hardened by high-temperature baking (150 - 160 °C) to form a stable insulating protective film. The solder mask layer can protect the non-welding areas, restrict the flow of molten solder, and at the same time, isolate moisture, dust and chemical corrosion (such as acid and alkali mists), prevent the copper layer on the surface of the copper-clad substrate from oxidizing or the circuit from being open-circuited, and improve the service life of the copper-clad substrate.

[0038] Step S401: Attach a first photosensitive dry film on the surface of the solder mask layer, and perform exposure and development on the first photosensitive dry film to expose some pads and cover the remaining pads and leads; Specifically, by attaching a first photosensitive dry film on the surface of the solder mask layer and performing exposure and development on the first photosensitive dry film, some pads that need to be electroplated with soft gold are exposed, while the leads and the pads that do not need to be electroplated with soft gold are protected by the first photosensitive dry film.

[0039] Step S501: Electroplate a soft gold layer on the exposed pads; By electroplating a soft gold layer on the pads, the welding reliability is improved and high-precision interconnection is supported. In this example, in order to improve the quality of the electroplated soft gold layer, before electroplating the soft gold layer, the oxide layer and contaminants on the pad surface are removed through processes such as pickling and micro-etching to ensure the adhesion of the electroplated layer. Then, an electrochemical deposition process is used to deposit a pure gold or gold alloy layer on the pad surface, and the uniformity of the coating is adjusted by controlling the current density (0.5 - 2.0 A / dm²) and temperature (40 - 60 °C).

[0040] Step S601: Remove the first photosensitive dry film, attach a second photosensitive dry film on the surface of the solder mask layer, and perform exposure and development on the second photosensitive dry film to expose the leads; Step S701: Remove the leads by alkaline etching and remove the second photosensitive dry film; The remaining pads that are not electroplated with soft gold are protected by the second photosensitive dry film. Then, the second photosensitive dry film is exposed and developed to expose the leads. Then, the leads are removed by alkaline etching and the second photosensitive dry film is removed.

[0041] Step S801: attaching a third photosensitive dry film on the surface of the solder resist layer, and exposing and developing the third photosensitive dry film to expose the milling groove position; The third photosensitive dry film is used to protect the positions where grooves are not required, and then the third photosensitive dry film is exposed and developed to expose the positions where grooves are required, so as to facilitate the subsequent groove milling. This method can effectively reduce the generation of burrs on the wire bonding fingers and avoid burrs or product scratches during the groove milling process.

[0042] Step S901: using a left-handed double-edged knife to perform layered milling at the milling position to form a slot; It should be noted that before slot milling, the milling cutter parameters need to be optimized to reduce slot burrs. In this example, a left-handed double-edged cutter is used for slot milling to reduce cutting resistance, improve slot milling quality, and reduce chip accumulation in the processing area; at the same time, through layered slot milling, the overall processing stress is significantly reduced, the plate is prevented from being delaminated or warped, the dimensional consistency is improved, the burrs and chips are reduced, and the slot milling accuracy is improved.

[0043] When milling grooves, a left-handed double-edged knife is used to perform clockwise layered pre-grooving of the copper-clad substrate at a first rotation speed and a first milling speed; after completing the layered pre-grooving, the wear of the left-handed double-edged knife is detected and the parameters of the left-handed double-edged knife are compensated; according to the compensated left-handed double-edged knife, the copper-clad substrate is finely milled counterclockwise at a second rotation speed and a second milling speed; the second rotation speed is less than the first rotation speed, and the second milling speed is greater than the first milling speed.

[0044] Specifically, when pre-grooving, the pre-grooving is performed at the first rotation speed and the first milling speed, thereby removing most of the material in the groove, reducing the cutting difficulty and allowance fluctuation in the fine milling stage, making the fine milling tool more uniformly stressed, and the groove width accuracy more accurate. At the same time, the pre-grooving is performed in a layered manner, which significantly reduces the overall processing stress, avoids the delamination or warping of the plate, improves the dimensional consistency, and avoids defects such as burrs and cracks. After the pre-grooving is completed, the wear of the left-handed double-edged knife is detected, and then, according to the degree of wear, the radius of the tool is compensated, so that the tool has higher accuracy when fine milling the groove. It should be noted that when pre-grooving, the left-handed double-edged knife mills the groove in a clockwise order, with a high rotation speed (about 42KR / min) and a low milling speed (about 4mm / s); when fine milling, the left-handed double-edged knife mills the groove in a counterclockwise order, with a low rotation speed (about 32KR / min) and a high milling speed (about 6mm / s). By adjusting the rotation speed and milling speed at different stages, the milling requirements at different stages are achieved, thereby improving the quality of the milling. In addition, during the layered pre-grooving, the feed speed of the left-handed double-edged tool (about 4 mm / s) is less than the retracting speed (about 300 mm / s), thereby further improving the quality of the milling groove.

[0045] Step S1001: Remove the third photosensitive dry film, mill the copper-clad substrate to form small formed boards. After completing the slot milling, remove the third photosensitive dry film, and mill the copper-clad substrate to form several small formed boards as individual products for subsequent shipping.

[0046] Step S1011: Set an organic protective film on the surface of the pads without electroplated soft gold layer. Specifically, after plating some high-frequency / high-power pads with soft gold, the contact resistance can be reduced, and at the same time, the signal attenuation caused by oxidation can be inhibited; for the remaining pads, an organic protective film is set as a protective layer for the pads to prevent oxidation, maintain solderability, and reduce costs at the same time.

[0047] Step S1021: Clean, inspect, and package the small formed boards.

[0048] After milling the copper-clad substrate to form small formed boards and setting the organic protective film, clean the small formed boards, and then perform OQC inspection (Outgoing Quality Control), AVI inspection (Automated Visual Inspection), PVS inspection (Product Verification Test), and MVI inspection (Machine Vision Inspection), etc. Finally, package and ship them.

[0049] According to the slotting method of the DDR5 product in the embodiment of the present application, first, make leads and pads, electroplate soft gold on some pads, and set an organic protective film on some pads, so as to protect the pads and reduce costs at the same time; after electroplating soft gold on the pads, remove the second photosensitive dry film to expose the leads, thereby etching back the leads to avoid copper burrs during slotting; then, use the third photosensitive dry film to protect the positions that do not need to be milled, only expose the positions that need to be milled, to avoid problems such as burrs or product scratches during slotting; then, use a left-handed double-edge cutter to perform layer-by-layer slot milling on the copper-clad substrate to improve the slotting accuracy and quality and avoid burrs or substrate cracking.

[0050] On the other hand, the present application also proposes another slotting method for the DDR5 product, as Figure 3 shown, and this method includes the following steps: Step S102: Obtain a copper-clad substrate and drill holes in the copper-clad substrate. Specifically, first, the raw substrate is cut into the required size according to the design specifications; after cutting, the copper-clad substrate needs to be baked to remove the moisture and stress inside the copper-clad substrate through high-temperature treatment, preventing deformation (such as board warping, etc.) caused by uneven heating during subsequent processes. The baking temperature is controlled at about 200°C. Then, Panel 2D is performed on the copper-clad substrate, that is, two-dimensional layout design is carried out, including paneling rules, tool board edges, and processing path optimization, etc. Subsequently, copper is removed from the surface of the copper-clad substrate, and the copper thickness is reserved at 3.5 ± 0.5 μm. The copper foil thickness is reduced through chemical etching or mechanical grinding to make the line impedance and current-carrying capacity meet the design requirements, avoiding impedance mismatch or uneven heat dissipation caused by too thick a copper layer. Then, mechanical drilling is performed on the copper-clad substrate to form a number of through holes. Subsequently, the smear is removed through the Desmear process to ensure the tight bonding of the copper layer to the substrate when metallizing the hole wall later, avoiding problems such as copper plating voids or delamination in the hole, making the distribution of the electroplated copper layer more uniform, reducing impedance mutation, and improving signal transmission stability. After removing the smear, the hole wall is metallized through the PTH process and copper plating to achieve interlayer conduction.

[0051] Step S202: Fabricate a circuit on the surface of the copper-clad substrate; Specifically, to fabricate a circuit on the surface of the copper-clad substrate, a photosensitive dry film is first attached to the surface of the copper-clad substrate. Then, the photosensitive dry film is exposed and developed to expose the copper layer in the area to be etched. Then, the exposed copper layer is dissolved by a chemical solution to form a circuit pattern. Finally, the photosensitive dry film is removed. In this way, the fabrication of the circuit is achieved. After fabricating the circuit, the copper-clad substrate can be subjected to AOI inspection to detect whether there are defective circuits and mark and record them.

[0052] Step S302: Set a solder mask layer on the surface of the copper-clad substrate and open a window in the solder mask layer to expose the pads; Specifically, after the fabrication of the circuit is completed, copper surface contaminants (such as oxide layers, grease, etc.) are removed through processes such as pickling to increase the surface roughness to enhance the ink adhesion. Then, the solder mask ink is evenly covered on the surface of the copper-clad substrate by screen printing, spraying, or photoplotting technology. The ink solvent is removed by low-temperature baking (80 - 100°C) to make the solder mask ink in a semi-cured state; the solder mask ink is pattern-exposed using ultraviolet light through a negative film, and the unexposed area remains soluble; the uncured ink is dissolved with an alkaline solution (such as 1% Na2CO3) to expose the pads; finally, the solder mask layer is completely hardened through high-temperature baking (150 - 160°C) to form a stable insulating protective film. The solder mask layer can protect the non-welding area, restrict the flow of molten solder, and at the same time, isolate moisture, dust, and chemical corrosion (such as acid and alkali mists), prevent the copper layer on the surface of the copper-clad substrate from oxidizing or the circuit from opening, and improve the service life of the copper-clad substrate.

[0053] Step S402: Electroplate a soft gold layer on the pad; By electroplating a soft gold layer on the pad, the soldering reliability is improved to support high-precision interconnection. In this example, to improve the quality of the electroplated soft gold layer, before electroplating the soft gold layer, the oxide layer and contaminants on the pad surface are removed through processes such as pickling and micro-etching to ensure the adhesion of the electroplated layer. Then, an electrochemical deposition process is used to deposit a pure gold or gold alloy layer on the pad surface, and the uniformity of the coating is adjusted by controlling the current density (0.5 - 2.0 A / dm²) and temperature (40 - 60 °C).

[0054] Step S502: Attach a photosensitive dry film to the surface of the copper-clad substrate, and expose and develop the photosensitive dry film to expose the grooving positions; The photosensitive dry film is used to protect the positions that do not need to be grooved. Then, the photosensitive dry film is exposed and developed to expose the positions that need to be grooved, which is convenient for subsequent grooving. This method can effectively reduce the generation of burrs on the wire bonding fingers and avoid problems such as burrs or product scratches during the grooving process.

[0055] Step S602: Use a left-handed double-edge cutter to perform layered grooving at the grooving positions to form slots; It should be noted that before grooving, the milling cutter parameters need to be optimized to reduce the burrs at the slot openings. In this example, a left-handed double-edge cutter is used for grooving to reduce the cutting resistance, improve the grooving quality, and reduce the accumulation of debris in the processing area. At the same time, through layered grooving, the overall processing stress is significantly reduced, avoiding delamination or warping deformation of the board, improving the dimensional consistency, reducing the residue of burrs and debris, and improving the grooving accuracy.

[0056] During grooving, a left-handed double-edge cutter is used to perform clockwise layered pre-grooving on the copper-clad substrate at the first rotation speed and the first milling speed. After completing the layered pre-grooving, the wear of the left-handed double-edge cutter is detected, and the parameters of the left-handed double-edge cutter are compensated. According to the compensated left-handed double-edge cutter, counterclockwise finish grooving is performed on the copper-clad substrate at the second rotation speed and the second milling speed. The second rotation speed is less than the first rotation speed, and the second milling speed is greater than the first milling speed.

[0057] Specifically, when performing pre-milling of the groove, pre-mill the groove at the first rotational speed and the first milling speed, so as to remove most of the material in the groove, reduce the cutting difficulty and the margin fluctuation in the finish milling stage, make the force on the finish milling tool more uniform, and make the groove width accuracy more accurate. At the same time, adopt a layered method for pre-milling the groove, significantly reduce the overall machining stress, avoid delamination or warping deformation of the plate, improve the dimensional consistency, and avoid defects such as burrs and cracks. After completing the pre-milling of the groove, detect the wear of the left-handed double-edged tool, and then, according to the degree of wear, compensate the radius of the tool, so that the tool has higher accuracy when finish-milling the groove. It should be noted that when pre-milling the groove, the left-handed double-edged tool mills the groove in a clockwise order, with a relatively high rotational speed (about 42KR / min) and a relatively low milling speed (about 4mm / s); when finish-milling the groove, the left-handed double-edged tool mills the groove in a counterclockwise order, with a relatively low rotational speed (about 32KR / min) and a relatively high milling speed (about 6mm / s). By adjusting the rotational speed and the milling speed in different stages, the groove milling requirements in different stages are realized, thereby improving the groove milling quality. In addition, when pre-milling the groove in layers, the feed speed (about 4mm / s) of the left-handed double-edged tool is less than the retraction speed (about 300mm / s), thereby further improving the groove milling quality.

[0058] Step S702: Remove the photosensitive dry film, mill the copper-clad substrate to form a formed small board; After completing the groove milling, remove the photosensitive dry film, and mill the copper-clad substrate to form a number of formed small boards, which are used as individual products for subsequent shipping.

[0059] Step S802: Clean, inspect and package the formed small board.

[0060] After milling the board to form a formed small board and setting an organic protective film, clean the formed small board, and then perform OQC inspection (Outgoing Quality Control, outgoing quality inspection), and then perform AVI inspection (Automated Visual Inspection, automated visual inspection), PVS inspection (Product Verification Test, product verification test) and MVI inspection (Machine Vision Inspection, machine vision inspection), etc. Finally, perform packaging and shipping.

[0061] According to the grooving method of the DDR5 product in the embodiment of the present application, use a photosensitive dry film to protect the positions that do not need to be grooved, and only expose the positions that need to be grooved, so as to avoid problems such as burrs or product scratches during grooving; then use a left-handed double-edged tool to perform layered grooving on the copper-clad substrate, improve the grooving accuracy and quality, and avoid the generation of burrs or substrate cracking. This method does not require etch-back of the leads, which can improve production efficiency, but stricter control of the tool life of the milling cutter is required.

[0062] On the other hand, the present application also proposes another method for grooving a DDR5 product, as Figure 4 shown. This method includes the following steps: Step S103: Obtain a copper-clad substrate and drill holes in the copper-clad substrate; Specifically, first, perform blanking, cutting the original substrate into the required size according to the design specifications; after blanking, it is necessary to bake the copper-clad substrate to remove the moisture and stress inside the copper-clad substrate through high-temperature treatment to prevent deformation (such as board warping, etc.) caused by uneven heating during subsequent processes. The baking temperature is controlled at about 200 °C. Then, perform Panel2D on the copper-clad substrate, that is, perform two-dimensional layout design, including panel splicing rules, tool board edges, and processing path optimization, etc. Subsequently, reduce the copper on the surface of the copper-clad substrate, and retain a copper thickness of 3.5 ± 0.5 μm. Reduce the copper foil thickness through chemical etching or mechanical grinding to make the line impedance and current-carrying capacity meet the design requirements, and avoid impedance mismatch or uneven heat dissipation caused by too thick a copper layer. Then, perform mechanical drilling on the copper-clad substrate to form a number of through holes. Subsequently, remove the slag generated after drilling through the Desmear process to ensure the tight bonding between the copper layer and the substrate when metallizing the hole wall later, avoid copper plating voids or delamination problems in the hole, make the distribution of the electroplated copper layer more uniform, reduce impedance mutation, and improve signal transmission stability. After removing the slag, metallize the hole wall through the PTH process and copper plating to achieve interlayer conduction.

[0063] Step S203: Fabricate circuits on the surface of the copper-clad substrate; Specifically, in order to fabricate circuits on the surface of the copper-clad substrate, first attach a photosensitive dry film to the surface of the copper-clad substrate, then expose and develop the photosensitive dry film to expose the copper layer in the area to be etched, and then dissolve the exposed copper layer through chemical liquid to form a circuit pattern. Finally, remove the photosensitive dry film. In this way, the fabrication of the circuit is achieved. After fabricating the circuit, the copper-clad substrate can be subjected to AOI inspection to detect whether there are problematic circuits and mark and record them.

[0064] Step S303: Set a solder mask layer on the surface of the copper-clad substrate and open windows in the solder mask layer to expose the pads; Specifically, after the production of the circuit is completed, contaminants on the copper surface (such as oxide layers, grease, etc.) are removed through processes such as pickling to increase the surface roughness and enhance the ink adhesion. Then, the solder mask ink is evenly coated on the surface of the copper-clad substrate by screen printing, spraying or photolithography techniques. The ink solvent is removed by low-temperature baking (80 - 100 °C) to make the solder mask ink in a semi-cured state; the solder mask ink is pattern-exposed using ultraviolet light through a negative film, and the unexposed areas remain soluble; the uncured ink is dissolved with an alkaline solution (such as 1% Na2CO3) to expose the pads; finally, the solder mask layer is completely hardened by high-temperature baking (150 - 160 °C) to form a stable insulating protective film. The solder mask layer can protect the non-welding areas, restrict the flow of molten solder, and at the same time, isolate moisture, dust and chemical corrosion (such as acid and alkali mists), prevent the copper layer on the surface of the copper-clad substrate from oxidizing or the circuit from breaking, and improve the service life of the copper-clad substrate.

[0065] Step S403: Attach a first photosensitive dry film to the surface of the solder mask layer, and perform exposure and development on the first photosensitive dry film to expose some pads and cover the rest of the pads; Specifically, by attaching a first photosensitive dry film to the surface of the solder mask layer and performing exposure and development on the first photosensitive dry film, some pads that need to be electroplated with soft gold are exposed, while the pads that do not need to be electroplated with soft gold are protected by the first photosensitive dry film.

[0066] Step S503: Electroplate a soft gold layer on the exposed pads; By electroplating a soft gold layer on the pads, the welding reliability is improved and high-precision interconnection is supported. In this example, to improve the quality of the electroplated soft gold layer, before electroplating the soft gold layer, the oxide layer and contaminants on the pad surface are also removed through processes such as pickling and micro-etching to ensure the adhesion of the electroplated layer. Then, an electrochemical deposition process is used to deposit a pure gold or gold alloy layer on the pad surface, and the coating uniformity is adjusted by controlling the current density (0.5 - 2.0 A / dm²) and temperature (40 - 60 °C).

[0067] Step S603: Remove the first photosensitive dry film and attach a second photosensitive dry film to the surface of the solder mask layer; Step S703: Perform exposure and development on the second photosensitive dry film to expose the grooving positions; The positions that do not need to be grooved are protected by the second photosensitive dry film, and then the second photosensitive dry film is exposed and developed to expose the positions that need to be grooved, which is convenient for subsequent grooving. This method can effectively reduce the generation of burrs on the wire bonding fingers and avoid problems such as burrs or product scratches during the grooving process.

[0068] Step S803: Use a left-handed double-edged cutter to perform grooving at the grooving positions to form slots; It should be noted that before slot milling, the milling cutter parameters need to be optimized to reduce slot burrs. In this example, a left-handed double-edged cutter is used for slot milling to reduce cutting resistance, improve slot milling quality, and reduce chip accumulation in the processing area; at the same time, through layered slot milling, the overall processing stress is significantly reduced, the plate is prevented from being delaminated or warped, the dimensional consistency is improved, the burrs and chips are reduced, and the slot milling accuracy is improved.

[0069] When milling grooves, a left-handed double-edged knife is used to perform clockwise layered pre-grooving of the copper-clad substrate at a first rotation speed and a first milling speed; after completing the layered pre-grooving, the wear of the left-handed double-edged knife is detected and the parameters of the left-handed double-edged knife are compensated; according to the compensated left-handed double-edged knife, the copper-clad substrate is finely milled counterclockwise at a second rotation speed and a second milling speed; the second rotation speed is less than the first rotation speed, and the second milling speed is greater than the first milling speed.

[0070] Specifically, when pre-grooving, the pre-grooving is performed at the first rotation speed and the first milling speed, thereby removing most of the material in the groove, reducing the cutting difficulty and allowance fluctuation in the fine milling stage, making the fine milling tool more uniformly stressed, and the groove width accuracy more accurate. At the same time, the pre-grooving is performed in a layered manner, which significantly reduces the overall processing stress, avoids the delamination or warping of the plate, improves the dimensional consistency, and avoids defects such as burrs and cracks. After the pre-grooving is completed, the wear of the left-handed double-edged knife is detected, and then, according to the degree of wear, the radius of the tool is compensated, so that the tool has higher accuracy when fine milling the groove. It should be noted that when pre-grooving, the left-handed double-edged knife mills the groove in a clockwise order, with a high rotation speed (about 42KR / min) and a low milling speed (about 4mm / s); when fine milling, the left-handed double-edged knife mills the groove in a counterclockwise order, with a low rotation speed (about 32KR / min) and a high milling speed (about 6mm / s). By adjusting the rotation speed and milling speed at different stages, the milling requirements at different stages are achieved, thereby improving the quality of the milling. In addition, during the layered pre-grooving, the feed speed of the left-handed double-edged tool (about 4 mm / s) is less than the retracting speed (about 300 mm / s), thereby further improving the quality of the milling groove.

[0071] Step S903: removing the second photosensitive dry film, and milling the copper-clad substrate to form a molded small board; After the milling is completed, the second photosensitive dry film is removed, and the copper-clad substrate is milled to form several small molded boards as a single product for subsequent shipment.

[0072] Step S1003: providing an organic protective film on the surface of the pad that is not electroplated with the soft gold layer; Specifically, after some high-frequency / high-power pads are treated with soft gold plating, the contact resistance can be reduced, and at the same time, the signal attenuation caused by oxidation can be suppressed; for the remaining pads, an organic protective film is provided as a protective layer for the pads to prevent oxidation while maintaining solderability and reducing costs at the same time.

[0073] Step S1013: Clean, inspect, and package the formed small board.

[0074] After milling the board to form the formed small board and setting the organic protective film, the formed small board is cleaned, and then subjected to OQC inspection (Outgoing Quality Control), AVI inspection (Automated Visual Inspection), PVS inspection (Product Verification Test), and MVI inspection (Machine Vision Inspection), etc. Finally, it is packaged and shipped.

[0075] According to the slotting method of the DDR5 product in the embodiment of the present application, first, after the pads are made, some pads are electroplated with soft gold, and some pads are provided with an organic protective film, so as to protect the pads while reducing costs; the second photosensitive dry film is used to protect the positions that do not need to be slotted, and only the positions that need to be slotted are exposed to avoid problems such as burrs or product scratches during slotting; then a left-handed double-edge cutter is used to perform layered slotting on the copper-clad substrate to improve the slotting accuracy and quality, and avoid the generation of burrs or substrate cracking. This method does not require etching the leads, which can improve production efficiency, but stricter control of the tool life of the milling cutter is required.

[0076] On the other hand, the present application also proposes another slotting method for the DDR5 product, as Figure 5 shown, this method includes the following steps: Step S104: Obtain a copper-clad substrate and drill holes in the copper-clad substrate; Specifically, first, the raw substrate is cut into the required size according to the design specifications; after cutting, the copper-clad substrate needs to be baked to remove the moisture and stress inside the copper-clad substrate through high-temperature treatment, preventing deformation (such as board warping, etc.) caused by uneven heating during subsequent processes. The baking temperature is controlled at about 200 °C. Then, the copper-clad substrate is subjected to Panel2D, that is, two-dimensional layout design, including panel splicing rules, tool board edges, and processing path optimization. Subsequently, the surface of the copper-clad substrate is copper-reduced, with the remaining copper thickness being 3.5 ± 0.5 μm. The copper foil thickness is reduced through chemical etching or mechanical grinding to make the line impedance and current-carrying capacity meet the design requirements, avoiding impedance mismatch or uneven heat dissipation caused by too thick a copper layer. Then, mechanical drilling is performed on the copper-clad substrate to form a number of through holes. Subsequently, the smear is removed through the Desmear process to ensure the tight bonding of the copper layer to the substrate when metallizing the hole wall later, avoiding problems such as copper plating voids or delamination in the holes, making the distribution of the electroplated copper layer more uniform, reducing impedance mutations, and improving signal transmission stability. After removing the smear, the hole wall is metallized through the PTH process and copper plating to achieve interlayer conduction.

[0077] Step S204: Fabricate a circuit on the surface of the copper-clad substrate; Specifically, to fabricate a circuit on the surface of the copper-clad substrate, a photosensitive dry film is first attached to the surface of the copper-clad substrate. Then, the photosensitive dry film is exposed and developed to expose the copper layer in the area to be etched. Then, the exposed copper layer is dissolved by chemical liquid to form a circuit pattern. Finally, the photosensitive dry film is removed. In this way, the fabrication of the circuit is achieved. After fabricating the circuit, the copper-clad substrate can be subjected to AOI inspection to detect whether there are defective circuits and mark and record them.

[0078] Step S304: Set a solder mask layer on the surface of the copper-clad substrate and open a window in the solder mask layer to expose the pads; Specifically, after completing the fabrication of the circuit, contaminants on the copper surface (such as oxide layers, grease, etc.) are removed through processes such as pickling to increase the surface roughness to enhance the ink adhesion. Then, the solder mask ink is evenly covered on the surface of the copper-clad substrate using screen printing, spraying, or photoplotting techniques. The ink solvent is removed through low-temperature baking (80 - 100 °C) to make the solder mask ink in a semi-cured state; the solder mask ink is pattern-exposed using ultraviolet light through a negative film, and the unexposed area remains soluble; the uncured ink is dissolved with an alkaline solution (such as 1% Na2CO3) to expose the pads; finally, the solder mask layer is completely hardened through high-temperature baking (150 - 160 °C) to form a stable insulating protective film. The solder mask layer can protect non-welding areas, restrict the flow of molten solder, and at the same time, isolate moisture, dust, and chemical corrosion (such as acid and alkali mists), prevent the oxidation of the copper layer on the surface of the copper-clad substrate or circuit open circuits, and improve the service life of the copper-clad substrate.

[0079] Step S404: Electroplate a soft gold layer on the pad; By electroplating a soft gold layer on the pad, the welding reliability can be improved to support high-precision interconnection. In this example, in order to improve the quality of the electroplated soft gold layer, before electroplating the soft gold layer, processes such as pickling and micro-etching are also used to remove the oxide layer and contaminants on the pad surface to ensure the adhesion of the electroplated layer. Then, an electrochemical deposition process is used to deposit a pure gold or gold alloy layer on the pad surface, and the uniformity of the coating is adjusted by controlling the current density (0.5 - 2.0 A / dm²) and temperature (40 - 60 °C).

[0080] Step S504: Divide the copper-clad substrate into several large boards; The copper-clad substrate is divided into two large boards in half, which is convenient for subsequent grooving of the two large boards respectively, thereby reducing the occupied area of the copper-clad substrate and facilitating subsequent processing.

[0081] Step S604: Groove each large board respectively to form grooves; Use a numerical control grooving machine or CNC equipment, etc., to groove each large board respectively to form the required grooves.

[0082] Step S704: Mill each large board to form several formed small boards; After grooving is completed, mill the large board to form several formed small boards, which are used as individual products for subsequent shipment.

[0083] Step S804: Clean, inspect and package the formed small boards.

[0084] Mill the board to form formed small boards, clean the formed small boards, and then conduct OQC inspection (Outgoing Quality Control), and then conduct AVI inspection (Automated Visual Inspection), PVS inspection (Product Verification Test), and MVI inspection (Machine Vision Inspection), etc. Finally, conduct packaging and shipment.

[0085] According to the grooving method of the DDR5 product in the embodiment of the present application, first divide the copper-clad substrate into large boards, and then directly groove each large board to form the required grooves, thereby improving the grooving efficiency and reducing the cost.

[0086] On the other hand, the present application also proposes another grooving method for the DDR5 product, as Figure 6 shown, this method includes the following steps: Step S105: Obtain a copper-clad substrate and drill holes in the copper-clad substrate; Specifically, first perform blanking, cutting the original substrate into the required size according to the design specifications; after blanking, the copper-clad substrate needs to be baked to remove moisture and stress inside the copper-clad substrate through high-temperature treatment, preventing deformation (such as board warping, etc.) caused by uneven heating during subsequent processes. The baking temperature is controlled at about 200°C. Then, perform Panel2D on the copper-clad substrate, that is, perform two-dimensional layout design, including paneling rules, tool board edges, and machining path optimization, etc. Subsequently, reduce the copper on the surface of the copper-clad substrate, leaving a copper thickness of 3.5 ± 0.5 μm. Reduce the copper foil thickness through chemical etching or mechanical grinding to make the line impedance and current-carrying capacity meet the design requirements, avoiding impedance mismatch or uneven heat dissipation caused by too thick copper layer. Then, perform mechanical drilling on the copper-clad substrate to form a number of through holes. Subsequently, remove the smears generated after drilling through the Desmear process to ensure the tight bonding of the copper layer and the substrate when metallizing the hole wall later, avoiding problems such as copper plating voids or delamination in the holes, making the electroplated copper layer more evenly distributed, reducing impedance mutations, and improving signal transmission stability. After removing the smears, metallize the hole wall through the PTH process and copper plating to achieve interlayer conduction.

[0087] Step S205: Fabricate circuits on the surface of the copper-clad substrate; Specifically, in order to fabricate circuits on the surface of the copper-clad substrate, first attach a photosensitive dry film to the surface of the copper-clad substrate. Then, expose and develop the photosensitive dry film to expose the copper layer in the area to be etched. Then, dissolve the exposed copper layer through chemical liquid to form a circuit pattern. Finally, remove the photosensitive dry film. In this way, the fabrication of the circuit is achieved. After fabricating the circuit, the copper-clad substrate can be subjected to AOI inspection to detect whether there are defective circuits and mark and record them.

[0088] Step S305: Set a solder mask layer on the surface of the copper-clad substrate and open windows in the solder mask layer to expose the pads; Specifically, after the production of the circuit, contaminants on the copper surface (such as oxide layers, grease, etc.) are removed through processes such as pickling to increase the surface roughness and enhance the ink adhesion. Then, the solder mask ink is evenly coated on the surface of the copper-clad substrate by screen printing, spraying or photolithography techniques. The ink solvent is removed by low-temperature baking (80 - 100 °C) to make the solder mask ink in a semi-cured state; the solder mask ink is pattern-exposed using ultraviolet light through a negative film, and the unexposed area remains soluble; the uncured ink is dissolved with an alkaline solution (such as 1% Na2CO3) to expose the pads; finally, the solder mask layer is completely hardened by high-temperature baking (150 - 160 °C) to form a stable insulating protective film. The solder mask layer can protect the non-welding areas, restrict the flow of molten solder, and at the same time, isolate moisture, dust and chemical corrosion (such as acid and alkali mists), prevent the oxidation of the copper layer on the surface of the copper-clad substrate or the open circuit of the circuit, and improve the service life of the copper-clad substrate.

[0089] Step S405: Set a photosensitive dry film on the surface of the copper-clad substrate, and expose and develop the photosensitive dry film to expose some pads and cover the remaining pads; Specifically, by attaching a photosensitive dry film on the surface of the solder mask layer and exposing and developing the photosensitive dry film, some pads that need to be electroplated with soft gold are exposed, while the pads that do not need to be electroplated with soft gold are protected by the photosensitive dry film.

[0090] Step S505: Electroplate a soft gold layer on the exposed pads; By electroplating a soft gold layer on the pads, the welding reliability is improved and high-precision interconnection is supported. In this example, in order to improve the quality of the electroplated soft gold layer, before electroplating the soft gold layer, the oxide layer and contaminants on the pad surface are removed through processes such as pickling and micro-etching to ensure the adhesion of the electroplated layer. Then, an electrochemical deposition process is used to deposit a pure gold or gold alloy layer on the pad surface, and the uniformity of the coating is adjusted by controlling the current density (0.5 - 2.0 A / dm²) and temperature (40 - 60 °C).

[0091] Step S605: Remove the photosensitive dry film and divide the copper-clad substrate into several large boards; The copper-clad substrate is divided into two large boards in half, which is convenient for subsequent grooving of the two large boards respectively, thereby reducing the occupied area of the copper-clad substrate and facilitating subsequent processing.

[0092] Step S705: Groove each large board respectively to form slots; Use a numerical control grooving machine or CNC equipment, etc., to groove each large board respectively to form the required slots.

[0093] Step S805: Mill each large board to form several formed small boards; After the grooving is completed, the large board is milled to form a number of small formed boards, which are used as individual products for subsequent shipping.

[0094] Step S905: Set an organic protective film on the surface of the pad without electroplated soft gold layer. Specifically, after plating some high-frequency / high-power pads with soft gold, the contact resistance can be reduced, and at the same time, signal attenuation caused by oxidation can be suppressed; for the remaining pads, an organic protective film is set as the protective layer of the pads, which can prevent oxidation, maintain solderability, and reduce costs at the same time.

[0095] Step S1005: Clean, inspect and package the small formed boards.

[0096] The large board is milled to form small formed boards, the small formed boards are cleaned, and then subjected to OQC inspection (Outgoing Quality Control, outgoing quality inspection), then AVI inspection (Automated Visual Inspection, automatic visual inspection), PVS inspection (Product Verification Test, product verification test) and MVI inspection (Machine Vision Inspection, machine vision inspection), etc. Finally, they are packaged and shipped.

[0097] According to the grooving method of the DDR5 product in the embodiment of the present application, after the copper-clad substrate is divided into large boards, each large board is directly grooved to form the required grooves, thereby improving the grooving efficiency and reducing costs. Some pads are electroplated with soft gold, and some pads are provided with an organic protective film, so as to protect the pads and reduce costs at the same time.

[0098] The embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the scope of knowledge possessed by those of ordinary skill in the art.

Claims

1. A grooving method for a DDR5 product, characterized in that, It includes the following steps: Obtain a copper-clad substrate and drill the copper-clad substrate; Fabricate circuits and leads on the surface of the copper-clad substrate; Set a solder mask layer on the surface of the copper-clad substrate and open windows in the solder mask layer to expose the pads and the leads; Attach a photosensitive dry film on the surface of the solder mask layer, and expose and develop the photosensitive dry film to expose the pads and cover the leads; Electroplate a soft gold layer on the pads; Remove the photosensitive dry film and remove the leads by alkaline etching; Use a left-handed double-edged cutter to perform layered milling on the copper-clad substrate to form a slot; Mill the copper-clad substrate to form a small formed board; Clean, inspect, and package the small formed board.

2. The grooving method of the DDR5 product according to claim 1, wherein, The step of obtaining a copper-clad substrate and drilling the copper-clad substrate includes: Obtain the copper-clad substrate by cutting, baking, and Panel2D of the original substrate; Reduce the copper on the surface of the copper-clad substrate; Perform mechanical drilling on the copper-clad substrate; Remove the smears generated after drilling through the Desmear process.

3. The grooving method of the DDR5 product according to claim 1, characterized in that Before electroplating the soft gold layer on the pads, it further includes: Perform pre-treatment for soft gold on the copper-clad substrate; Remove the oxide layer on the surface of the pads by micro-etching.

4. The grooving method of the DDR5 product according to claim 1, wherein The step of using a left-handed double-edged cutter to perform layered milling on the copper-clad substrate to form a slot includes: Use the left-handed double-edged cutter to perform clockwise layered pre-milling on the copper-clad substrate at a first rotational speed and a first milling speed; After completing the layered pre-milling, detect the wear of the left-handed double-edged cutter and compensate the parameters of the left-handed double-edged cutter; According to the compensated left-handed double-edged cutter, perform counterclockwise fine milling on the copper-clad substrate at a second rotational speed and a second milling speed; the second rotational speed is less than the first rotational speed, and the second milling speed is greater than the first milling speed.

5. The grooving method of the DDR5 product according to claim 4, wherein During milling, the feed speed of the left-handed double-edged cutter is less than the retraction speed.

6. A grooving method for a DDR5 product, characterized in that, It includes the following steps: Obtain a copper-clad substrate and drill the copper-clad substrate; Fabricate circuits and leads on the surface of the copper-clad substrate; Set a solder mask layer on the surface of the copper-clad substrate and open windows in the solder mask layer to expose the pads and the leads; Attach a first photosensitive dry film on the surface of the solder mask layer, and expose and develop the first photosensitive dry film to expose some of the pads and cover the remaining pads and the leads; Electroplate a soft gold layer on the exposed pads; Remove the first photosensitive dry film, attach a second photosensitive dry film on the surface of the solder mask layer, and expose and develop the second photosensitive dry film to expose the leads; Remove the leads by alkaline etching and remove the second photosensitive dry film; Attach a third photosensitive dry film on the surface of the solder mask layer, and expose and develop the third photosensitive dry film to expose the milling slot position; Use a left-handed double-edged cutter to mill a slot at the milling slot position to form a slot; Remove the third photosensitive dry film, mill the copper-clad substrate to form a small formed board; Set an organic protective film on the surface of the pads without electroplated soft gold layer; Clean, inspect, and package the small formed board.

7. A grooving method for a DDR5 product, characterized in that, It includes the following steps: Obtain a copper-clad substrate and drill the copper-clad substrate; Fabricate circuits on the surface of the copper-clad substrate; Set a solder mask layer on the surface of the copper-clad substrate and open windows in the solder mask layer to expose the pads; Electroplate a soft gold layer on the pads; Attach a photosensitive dry film on the surface of the copper-clad substrate and expose and develop the photosensitive dry film to expose the milling groove positions; Use a left-handed double-edge cutter to perform layered milling in the milling groove positions to form slots; Remove the photosensitive dry film and mill the copper-clad substrate to form small formed plates; Clean, inspect, and package the small formed plates.

8. A grooving method for a DDR5 product, characterized in that The steps include: Obtain a copper-clad substrate and drill holes in the copper-clad substrate; Fabricate circuits on the surface of the copper-clad substrate; Set a solder mask layer on the surface of the copper-clad substrate and open windows in the solder mask layer to expose the pads; Attach a first photosensitive dry film on the surface of the solder mask layer and expose and develop the first photosensitive dry film to expose some of the pads and cover the rest of the pads; Electroplate a soft gold layer on the exposed pads; Remove the first photosensitive dry film and attach a second photosensitive dry film on the surface of the solder mask layer; Expose and develop the second photosensitive dry film to expose the milling groove positions; Use a left-handed double-edge cutter to perform layered milling in the milling groove positions to form slots; Remove the second photosensitive dry film and mill the copper-clad substrate to form small formed plates; Set an organic protective film on the surface of the pads without electroplated soft gold layer; Clean, inspect, and package the small formed plates.

9. A grooving method for a DDR5 product, characterized in that The steps include: Obtain a copper-clad substrate and drill holes in the copper-clad substrate; Fabricate circuits on the surface of the copper-clad substrate; Set a solder mask layer on the surface of the copper-clad substrate and open windows in the solder mask layer to expose the pads; Electroplate a soft gold layer on the pads; Separate the copper-clad substrate into several large plates; Perform slot punching on each large plate to form slots; Mill each large plate to form small formed plates; Clean, inspect, and package the small formed plates.

10. A slotting method for a DDR5 product, characterized in that The steps include: Obtain a copper-clad substrate and drill holes in the copper-clad substrate; Fabricate circuits on the surface of the copper-clad substrate; Set a solder mask layer on the surface of the copper-clad substrate and open windows in the solder mask layer to expose the pads; Set a photosensitive dry film on the surface of the copper-clad substrate and expose and develop the photosensitive dry film to expose some of the pads and cover the rest of the pads; Electroplate a soft gold layer on the exposed pads; Remove the photosensitive dry film and separate the copper-clad substrate into several large plates; Perform slot punching on each large plate to form slots; Mill each large plate to form small formed plates; Set an organic protective film on the surface of the pads without electroplated soft gold layer; Clean, inspect, and package the small formed plates.

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