A printed conductive based PCB motor stator and additive manufacturing method thereof

Abstract

This invention discloses a PCB motor stator based on printed conductivity and its additive manufacturing method, belonging to the field of micro-motor technology. Addressing the problems of existing PCB stator manufacturing processes relying on mechanical drilling and electroplating, which suffer from lengthy procedures, low yield, high cost, and limited substrate material selection, the stator of this invention comprises an insulating substrate, at least two layers of conductive windings, and an interlayer insulating layer. Adjacent conductive windings are electrically connected as a single unit through printed and cured solid conductive pillars filling pre-reserved through-holes in the insulating layer. Its fabrication is completed through a fully printed additive manufacturing process: bottom layer winding printing, insulating layer forming and opening, top layer printing and simultaneous through-hole filling, and low-temperature integrated curing. This invention significantly simplifies the production process, improves product yield and conductivity, reduces production costs and environmental impact, is compatible with flexible, low-cost substrates, and is suitable for various micro-precision drive applications.

Description

Technical Field

[0001] This invention belongs to the field of micro motor technology, specifically relating to a printed winding motor stator and its additive manufacturing method, and more specifically, to a PCB (printed circuit board) motor stator manufactured by a fully printed additive manufacturing process and its preparation method. Background Technology

[0002] In existing technologies, PCB motors (or printed winding motors) are widely used in precision drive fields such as drones and robot joints due to their advantages such as flat structure, high precision, and ease of mass production. The traditional manufacturing method of its core component—the PCB stator—mainly follows the manufacturing process of multilayer printed circuit boards (PCBs).

[0003] This process first forms a winding pattern on a copper-clad substrate using photolithography and etching. Then, vias are formed on an insulating substrate through mechanical drilling. Finally, metallization layers are formed on the via walls using chemical copper plating and electroplating, thereby achieving interlayer electrical connections. This method has the following inherent drawbacks:

[0004] The process is complex and yields low success rates: it involves more than ten steps, including material preparation, drilling, copper plating, electroplating, pattern transfer, and etching, making the process lengthy. Especially for micro motors (e.g., stator outer diameter less than 50mm), mechanical drilling of micro-holes (diameter typically less than 0.3mm) easily leads to micro-cracks in the substrate and rough hole walls, which in turn affects the uniformity and reliability of subsequent hole metallization, resulting in an overall finished product yield typically below 75%.

[0005] Material and cost limitations: The high-temperature lamination process (typically above 180°C) in traditional processes restricts the application of low-cost, highly flexible substrate materials such as polyethylene terephthalate (PET). Meanwhile, processes such as electroplating and hole filling require expensive and time-consuming equipment and generate chemical waste containing heavy metals, resulting in significant production costs and environmental pressures.

[0006] Limited design flexibility: Relying on physical drilling and electroplating filling makes it difficult to achieve high aspect ratio conduction structures or non-vertical conduction, which restricts further optimization of the motor's power density and heat dissipation design.

[0007] Therefore, there is an urgent need for a new PCB motor stator structure and a new manufacturing method that can simplify the process, improve yield, reduce costs, and broaden the range of material choices. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a PCB motor stator based on printed conductivity and its additive manufacturing method, which has a simple structure, simple manufacturing process, is suitable for large-scale automated production and has a high yield.

[0009] To address the aforementioned technical problems, the present invention provides the following technical solution: On one hand, the present invention provides a PCB motor stator based on printed conductivity, comprising an insulating substrate, at least two layers of conductive windings, and an insulating layer disposed between adjacent conductive windings. The electrical connection between the adjacent conductive windings is achieved through solid conductive pillars filled in pre-reserved through-holes in the insulating layer; the solid conductive pillars are formed by printing and curing conductive paste, and are directly connected to the upper and lower conductive windings as a single unit.

[0010] Furthermore, the conductive paste is a low-temperature curing conductive silver paste, with a curing temperature not exceeding 140°C. The insulating substrate is preferably made of polyimide (PI) or polyethylene terephthalate (PET). The conductive winding has a radially tapered spoke pattern.

[0011] On the other hand, the present invention provides an additive manufacturing method for the above-mentioned PCB motor stator based on printed conductivity, comprising the following steps:

[0012] S1. An insulating substrate is provided, on which a first conductive paste layer is printed and cured to form a bottom conductive winding;

[0013] S2. A first insulating layer is formed on the bottom conductive winding, and a through hole is opened on the first insulating layer at a position corresponding to a preset electrical connection point;

[0014] S3. Print a second conductive paste layer on the first insulating layer. The second conductive paste fills the through hole and contacts the bottom conductive winding, while forming a top conductive winding pattern.

[0015] S4. Perform a heat curing process to cure the first conductive slurry layer, the second conductive slurry layer, and the slurry filling the through hole as a whole, wherein the slurry filling the through hole forms a solid conductive column connecting the upper and lower conductive windings.

[0016] Furthermore, in step S2, the through-hole can be formed by laser ablation or by pre-reserving during printing. The printing methods in steps S1 and S3 are screen printing or stencil printing. The curing temperature in step S4 is 110°C to 130°C, and the curing time is 30 to 60 minutes.

[0017] One or more technical solutions provided in this application embodiment have at least the following technical effects or advantages compared with the prior art:

[0018] 1. Revolutionary Simplification of Process: Completely eliminates complex and highly polluting processes such as mechanical drilling, chemical copper plating, and electroplating, streamlining the traditional 10+ steps into a few printing passes and a single curing step, achieving "all-printing additive manufacturing." Production cycles can be shortened from several days to several hours, significantly improving production efficiency.

[0019] 2. Significantly improved product yield: The elimination of major failure modes such as micro-hole drilling cracks and uneven electroplating on the hole walls has improved the manufacturing yield of PCB motor stators.

[0020] 3. Superior electrical performance: Compared with traditional thin-walled electroplated holes, solid silver paste conductive pillars have a larger effective conductive cross-sectional area and a more uniform current density, lower and more consistent conduction resistance, reduced heat loss, and improved motor output efficiency and stability.

[0021] 4. Significant cost and environmental advantages: No expensive drilling and electroplating equipment is required, and the production process generates no etching waste acid or electroplating heavy metal wastewater, meeting green manufacturing standards. Furthermore, the low-temperature process allows the use of lower-cost or more flexible substrate materials (such as PET), broadening application scenarios.

[0022] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0023] Figure 1 A schematic diagram of the conventional PCB motor stator interlayer conduction structure (showing the drilled holes and the copper layer on the hole walls).

[0024] Figure 2 This is a schematic diagram of the interlayer conduction structure of the PCB motor stator of the present invention (showing the overlapping columns with no drilling holes and direct stacking of paste).

[0025] Figure 3 This is a flowchart of the preparation process of the present invention;

[0026] Figure 4 This is a plan view of the "radial tapered spoke winding" of the present invention. Detailed Implementation

[0027] 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.

[0028] It should be noted that the terms "vertical," "horizontal," "up," "down," "left," "right," and similar expressions used in this article are for illustrative purposes only and do not represent the only possible implementation.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to limit the invention; the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0030] like Figure 1 As shown, traditional PCB motor stators use a laminated structure of the stator core as the load-bearing substrate. Through holes are machined into the laminates by mechanical drilling, and then a copper layer is deposited on the hole walls through chemical copper plating and electroplating processes. Ultimately, the interlayer conduction between the upper and lower windings is achieved by the copper layer on the hole walls. This structure relies on mechanical drilling and wet electroplating processes, which have inherent defects such as micro-hole drilling cracks, uneven hole wall plating, lengthy processes, and significant pollution.

[0031] like Figure 2 and Figure 4 As shown, the present invention is a flat stator structure manufactured by full-printing additive manufacturing, which includes, from bottom to top, an insulating substrate, a bottom conductive winding, a first insulating layer, and a top conductive winding; the first insulating layer has through holes, and solid conductive pillars are filled in the through holes to form solid conductive pillars, thereby realizing a reliable interlayer electrical connection between the bottom conductive winding and the top conductive winding.

[0032] The insulating substrate serves as the load-bearing base for the stator and is made of a flexible insulating film material, such as polyimide (PI) or polyethylene terephthalate (PET). The thickness can be selected within the range of 50μm to 200μm according to the motor power requirements, providing a flat load-bearing base for the upper windings and insulation layer, and is also suitable for flexible motor applications.

[0033] The bottom conductive winding is formed by printing and curing a low-temperature curing conductive paste, and is then bonded to the upper surface of an insulating substrate. Figure 4 As shown, the winding pattern is radially tapered spokes. Centered on the stator center point, multiple sets of spoke windings are evenly distributed along the circumference. Each set of spoke windings extends from the central area to the outer edge. The width of the trace changes gradually along the radial direction. This optimizes the winding space utilization while ensuring current carrying capacity, and adapts to the magnetic field design requirements of micro flat motors.

[0034] The first insulating layer is applied to the upper surface of the bottom conductive winding and is cured with insulating ink. It serves to achieve interlayer electrical insulation between the bottom and top conductive windings. The first insulating layer has through-holes at predetermined electrical connection points, which penetrate vertically through the first insulating layer, allowing the connection points of the bottom conductive winding to be fully exposed through the through-holes, providing a contact interface for interlayer conductivity.

[0035] The top conductive winding is formed by printing and curing the same low-temperature curing conductive paste as the bottom conductive winding, and is set on the upper surface of the first insulating layer. The winding pattern is also radially tapered spokes, corresponding to and matching the pattern of the bottom conductive winding, together forming a complete winding circuit of the motor stator.

[0036] Solid conductive pillars are integrally formed by curing conductive paste filled into through-holes during the printing of the top conductive winding. They are dense, solid columnar structures, with their top and bottom ends sintered and connected to the top and bottom conductive windings respectively, forming a continuous whole. This eliminates the risk of interface delamination and achieves reliable low-resistance conduction between the two winding layers. Compared to traditional thin-walled electroplated holes, solid conductive pillars have a larger effective conductive cross-sectional area, more uniform current density distribution, and lower and more consistent conduction resistance.

[0037] The PCB motor stator of this invention is manufactured using a fully printed additive manufacturing process, and the overall process flow is as follows: Figure 3 As shown, the four core processes are, in sequence, bottom layer printing, insulation layer forming, top layer printing and conductivity, and low-temperature co-firing. The entire production process can be completed using screen printing equipment, ultraviolet laser processing equipment, and precision hot air ovens. The specific operation process is detailed below with reference to an example: Example 1

[0038] This embodiment uses a PI substrate and laser aperture technology to fabricate a double-layer PCB motor stator. The specific steps are as follows:

[0039] Substrate pretreatment: A 100μm thick polyimide (PI) film is cut as the insulating substrate. The film surface is then subjected to plasma cleaning treatment to remove surface oil and particulate impurities, thereby improving the adhesion performance of the conductive paste.

[0040] Bottom Printing Process S1: Using a 400-mesh stainless steel screen and a screen printing machine, low-temperature curing conductive silver paste (volume resistivity ≤ 5×10⁻⁶) is applied. -5 The slurry (Ω・cm, nominal curing conditions 130℃ / 30min) is printed onto the surface of the insulating substrate to form a preset radially gradient spoke winding pattern. After printing, the workpiece is placed in a 120℃ hot air circulating oven for pre-curing for 10 minutes to allow the slurry to initially set and form the bottom conductive winding.

[0041] Insulation layer forming process S2: On the surface of the pre-cured bottom conductive winding, a layer of polyimide-based photocurable insulating ink is coated by screen printing, and after curing by ultraviolet light, the first insulation layer is formed; then, using ultraviolet laser processing equipment, through holes with a diameter of 300μm are ablated at six preset electrical connection points. The through holes penetrate the first insulation layer and completely expose the connection surface of the bottom conductive winding.

[0042] Top layer printing and conductive process S3: The same low-temperature curing conductive silver paste is printed again using a 400-mesh stainless steel screen. During the printing process, the conductive silver paste relies on its own fluidity to fill the through holes synchronously, fully wetting and contacting the exposed surface of the bottom conductive winding, and at the same time forming a complete pattern of the top layer conductive winding on the surface of the first insulating layer.

[0043] Low-temperature co-firing process S4: The printed workpiece is placed in a precision oven and kept at 130℃ for 30 minutes for final curing; during the curing process, the bottom conductive winding, the top conductive winding, and the conductive silver paste in the through holes are sintered and cured simultaneously to form an integrated conductive structure. The paste in the through holes forms a solid conductive column after curing, and finally a complete PCB motor stator is obtained.

[0044] The performance of the sample prepared in this embodiment was tested: the average interlayer conduction resistance was less than 2mΩ, and after 100 cycles of temperature cycling from -40℃ to 85℃, the resistance change rate was less than 5%, and the yield of batch trial production could reach 97%. Example 2

[0045] This embodiment uses a PET substrate and a pre-printed through-hole process to prepare a double-layer PCB motor stator. The core difference from Embodiment 1 lies in the substrate material and the through-hole forming method, as detailed below:

[0046] The substrate is made of polyethylene terephthalate (PET) film with a thickness of 125 μm as the insulating substrate to reduce material costs and improve stator flexibility.

[0047] In the insulation layer forming process S2, the through holes are formed by printing pre-reservation: when printing the insulating ink, blank windows are reserved directly at the connection points through the screen graphic design. After the insulating ink is cured by ultraviolet light, the through holes are formed directly, omitting the laser ablation process and further simplifying the process.

[0048] To adapt to the temperature resistance characteristics of PET substrates, a special low-temperature conductive silver paste with a curing temperature of 110℃ was selected. The final curing process was adjusted to keep the substrate at 110℃ for 60 minutes to complete the curing of the overall structure.

[0049] The product prepared in this embodiment also has stable interlayer conductivity, verifying the good compatibility of this process with low-cost flexible substrates.

[0050] This invention is based on the technical concept of additive manufacturing through printing. It replaces the traditional drilling and electroplating process with conductive paste printing and filling to achieve interlayer conductivity in the PCB motor stator. Its core working principle is as follows:

[0051] Interlayer conduction principle: Utilizing the flow and filling characteristics of conductive paste, during the printing of the top layer winding, the paste naturally fills the through holes of the insulating layer and fully wets and contacts the surface of the bottom layer winding; after low-temperature integral curing, the paste in the through holes forms a dense solid conductive pillar, which is sintered with the upper and lower layers of winding into a continuous integral conductive structure. There is no risk of thin-walled structure, plating voids and interface delamination of traditional electroplated holes. The effective conduction cross-sectional area is larger, the current density distribution is more uniform, the conduction resistance is lower, and the reliability against temperature shock and mechanical vibration is higher.

[0052] The principle of all-printed additive manufacturing: The stator structure is constructed by printing and stacking throughout the process. First, the bottom winding is printed on the substrate, then the insulating layer is printed and the conduction window is reserved. Finally, the top winding is printed and the through hole is filled at the same time. All functional structures are formed layer by layer through the additive manufacturing method of "printing-curing". This completely eliminates the subtractive etching, mechanical drilling, chemical copper plating and electroplating processes in traditional PCB processes. More than ten processes are simplified into four core processes, and the production cycle is shortened from several days to several hours. At the same time, the generation of etching waste acid and electroplating heavy metal wastewater is avoided.

[0053] Low-temperature material compatibility principle: Low-temperature curing conductive silver paste with a curing temperature not exceeding 140℃ is used in conjunction with light-curing low-temperature insulating ink. The highest temperature of the entire preparation process does not exceed 130℃, which is far lower than the high-temperature lamination temperature of 180℃ or more in traditional PCB processes. Therefore, it is compatible with low-cost, highly flexible, and temperature-sensitive substrate materials such as PET, which broadens the range of materials to be selected for the stator and flexible application scenarios.

[0054] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A PCB motor stator based on printed circuitry, comprising an insulating substrate, at least two layers of conductive windings, and an insulating layer disposed between adjacent conductive windings, characterized in that, The electrical connection between adjacent conductive windings is achieved by solid conductive pillars filled in the reserved through holes of the insulating layer; the solid conductive pillars are formed by printing and curing conductive paste, and are directly connected to the upper and lower conductive windings as a whole.

2. The PCB motor stator based on printed conductivity according to claim 1, characterized in that, The conductive paste is a low-temperature curing conductive silver paste, and its curing temperature is not higher than 140℃.

3. The PCB motor stator based on printed conductivity according to claim 1, characterized in that, The insulating substrate is made of polyimide or polyethylene terephthalate.

4. The PCB motor stator based on printed conductivity according to claim 1, characterized in that, The conductive winding has a radially tapered spoke pattern.

5. An additive manufacturing method for a PCB motor stator based on printed conductivity as described in any one of claims 1 to 4, characterized in that, Includes the following steps: S1. An insulating substrate is provided, on which a first conductive paste layer is printed and cured to form a bottom conductive winding; S2. A first insulating layer is formed on the bottom conductive winding, and a through hole is opened on the first insulating layer at a position corresponding to a preset electrical connection point; S3. Print a second conductive paste layer on the first insulating layer. The second conductive paste fills the through hole and contacts the bottom conductive winding, while forming a top conductive winding pattern. S4. Perform a heat curing process to cure the first conductive slurry layer, the second conductive slurry layer, and the slurry filling the through hole as a whole, wherein the slurry filling the through hole forms a solid conductive column connecting the upper and lower conductive windings.

6. The additive manufacturing method according to claim 5, characterized in that, In step S2, the through hole is formed by laser ablation or by leaving a pre-existing hole during printing.

7. The additive manufacturing method according to claim 5, characterized in that, The printing methods in steps S1 and S3 are screen printing or stencil printing.

8. The additive manufacturing method according to claim 5, characterized in that, The curing temperature in step S4 is 110°C to 130°C, and the curing time is 30 to 60 minutes.

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