Processing method of 5G high-frequency LCP material embedded fine line

Abstract

The application belongs to the technical field of line forming, and provides a processing method of 5G high-frequency LCP material embedded fine line, which comprises the following steps: S1, vacuum magnetron sputtering is carried out on a medium surface to deposit a seed layer on the medium surface; S2, line electroplating is carried out on the seed layer to obtain a fine line layer; S3, the medium with the fine line layer is laminated with an LCP substrate, and high-temperature pressing is carried out, so that the LCP substrate is filled into the gap of the fine line layer; S4, the medium is removed; then, the seed layer is removed to obtain a semi-embedded line LCP; S5, the steps S1-S4 are repeated to obtain two semi-embedded line LCPs, which are respectively a first semi-embedded line LCP and a second semi-embedded line LCP; S6, the first semi-embedded line LCP and the second semi-embedded line LCP are laminated, and high-temperature pressing treatment is carried out, so that a fine line structure embedded in the LCP material is obtained. The application is beneficial to reducing the transmission loss of the fine line structure.

Description

A fabrication method for embedding fine circuits in 5G high-frequency LCP material Technical Field

[0001] This invention belongs to the field of circuit forming technology, specifically relating to a processing method for embedding fine circuits in 5G high-frequency LCP material. Background Technology

[0002] The density and real-time nature of information transmission have led to a rapid shift towards higher frequency signal transmission. As a fundamental component of electronic products, printed circuit boards (PCBs) must also rapidly evolve towards higher density, finer detail, and greater integration. Therefore, improving the fineness and high-frequency performance of circuits in high-frequency products is particularly important.

[0003] For fabricating fine circuits smaller than 10μm, the conventional mSAP process currently used is difficult to achieve. Furthermore, the magnetron sputtering seed layer fabrication method leads to increased losses at the metal interfaces of the circuit, and the interface between the dielectrics created by adhesive bonding also contributes to high-frequency losses. Therefore, it is necessary to propose a new method for fabricating fine circuit structures to reduce high-frequency losses. Summary of the Invention

[0004] In order to overcome the above-mentioned shortcomings of the prior art, the purpose of this invention is to provide a processing method for embedding fine circuits in 5G high-frequency LCP materials, which is beneficial to reducing the transmission loss of fine circuit structures.

[0005] The technical solution adopted by this invention to solve its technical problem is:

[0006] A method for fabricating fine circuits embedded in 5G high-frequency LCP material includes the following steps:

[0007] S1. Vacuum magnetron sputtering is performed on the surface of the dielectric to deposit a conductive seed layer on the surface of the dielectric.

[0008] S2. Perform circuit electroplating on the seed layer to obtain a fine circuit layer on the seed layer;

[0009] S3. The dielectric with the fine circuit layer is laminated with the LCP substrate and subjected to high temperature pressing treatment, so that the LCP substrate fills the gap of the fine circuit layer.

[0010] S4. Remove the dielectric material to expose the side of the fine circuit layer containing the seed layer; then remove the seed layer to obtain a semi-buried circuit LCP.

[0011] S5. By repeating steps S1 to S4, two semi-embedded line LCPs are obtained, namely the first semi-embedded line LCP and the second semi-embedded line LCP.

[0012] S6. The first semi-embedded circuit LCP and the second semi-embedded circuit LCP are stacked and subjected to high-temperature pressing to obtain a fine circuit structure embedded in the LCP material.

[0013] Preferably, in step S1, vacuum magnetron sputtering is performed on the dielectric surface, including:

[0014] (1) A nickel layer is sputtered on the surface of the medium, followed by the introduction of argon gas;

[0015] (2) The surface of the medium after step (1) is sputtered a second time, and then argon gas is introduced to form a seed layer containing a nickel layer and a titanium layer.

[0016] Preferably, in step S2, electroplating of the circuit on the seed layer on the surface of the dielectric includes:

[0017] (a) A high-resolution dry film or photoresist is used to cover the seed layer, and exposure and development processes are performed.

[0018] (b) Using a seed layer formed by sputtering as a conductive layer, pattern electroplating and circuit addition are performed to form an electroplated circuit on the seed layer.

[0019] (c) The dielectric with seed layer and electroplated lines is stripped and flash-etched to remove the dry film or photoresist and the seed layer in the dry film or photoresist-covered area, thereby forming a fine line layer on the dielectric.

[0020] Preferably, in step (a), after the development process is completed, plasma is used to remove the residue of the dry film or photoresist.

[0021] Preferably, in step (c), during the flash etching process, a solution that has an etching effect on titanium and nickel is selected.

[0022] Preferably, in step S3, before laminating the dielectric with the fine circuit layer to the LCP substrate, the fine circuit layer on the dielectric is subjected to a medium-coarsening treatment to improve the reliability after high-temperature lamination.

[0023] Preferably, in step S4, the medium is removed by plasma etching or chemical etching; and the seed layer is removed by micro-etching.

[0024] Preferably, in step S6, a middle layer LCP substrate is laminated between the first semi-embedded circuit LCP and the second semi-embedded circuit LCP. The first semi-embedded circuit LCP, the second semi-embedded circuit LCP and the middle layer LCP substrate are subjected to high-temperature pressing treatment to obtain a fine circuit structure embedded in the LCP material.

[0025] The Tg point of the middle layer LCP substrate is lower than that of the first semi-embedded circuit LCP and the second semi-embedded circuit LCP.

[0026] The temperature required for high-temperature pressing in step S6 is lower than the temperature required for high-temperature pressing in step S3.

[0027] Preferably, the medium is a pure dielectric material.

[0028] Preferably, the medium is a copper foil substrate;

[0029] In step (c), after stripping and flash etching of the dielectric with seed layer and electroplated lines, the copper layer on the dielectric also needs to be etched.

[0030] Compared with the prior art, the beneficial effects of the present invention are:

[0031] This invention uses magnetron sputtering of a seed layer and electroplating to create finer circuits, and includes a process for removing the seed layer, which helps reduce the loss caused by the skin effect in fine circuits at high frequencies. At the same time, this invention uses high-frequency material LCP and employs a high-temperature pressing method to utilize the fluidity of LCP to bond the circuits between layers and fill the gaps between the circuits, achieving consistency of the dielectric material, which helps reduce the loss caused by the dielectric interface, thereby helping to reduce the transmission loss of the fine circuit structure. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 is a schematic diagram of steps S1-S2 of the first embodiment of the processing method for embedding fine circuits in 5G high-frequency LCP material according to the present invention.

[0034] Figure 2 is a schematic diagram of steps S3-S4 of the first embodiment of the processing method for embedding fine circuits in 5G high-frequency LCP material according to the present invention.

[0035] Figure 3 is a schematic diagram of step S6 of the first embodiment of the processing method for embedding fine circuits in 5G high-frequency LCP material according to the present invention.

[0036] Figure 4 is a schematic diagram of steps S1-S2 of the second embodiment of the processing method for embedding fine circuits in 5G high-frequency LCP material according to the present invention.

[0037] Figure 5 is a schematic diagram of steps S3-S4 of the second embodiment of the processing method for embedding fine circuits in 5G high-frequency LCP material according to the present invention.

[0038] Figure 6 is a schematic diagram of step S6 of the second embodiment of the processing method for embedding fine circuits in 5G high-frequency LCP material according to the present invention.

[0039] in:

[0040] 1-Dielectric, 2-Seed layer, 3-Dry film, 4-Fine circuit layer, 5-LCP substrate, 6-First semi-embedded circuit LCP, 7-Second semi-embedded circuit LCP, 8-Middle layer LCP substrate, 9-Fine circuit structure. Detailed Implementation

[0041] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. Many specific details are set forth in the following description to provide a thorough understanding of the present invention; the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0042] 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 be limiting of the invention.

[0043] Example 1

[0044] Referring to Figures 1-3, this embodiment discloses a processing method for embedding fine circuits in 5G high-frequency LCP material, including the following steps:

[0045] S1. As shown in Figure 1, a pure dielectric material is selected as dielectric 1, with a thickness of approximately 12 μm. The surface of dielectric 1 is first roughened, and then vacuum magnetron sputtering is performed on the surface of dielectric 1 to deposit a conductive seed layer 2 with a thickness of approximately 60 nm. Specifically, the vacuum magnetron sputtering on the surface of dielectric 1 includes:

[0046] (1) A nickel layer is sputtered on the surface of the medium 1 under the sputtering conditions of a vacuum degree of 5*10. -4Pa; then argon gas was introduced at a flow rate of 25 ml / min, working pressure of 0.5 Pa, vacuum chamber temperature of 120–180 °C, sputtering time of 60–120 s, sputtering power of 40–80 W, and the thickness of seed layer 2 (nickel layer) after sputtering was between 0.2 and 0.5 μm.

[0047] (2) Perform a second sputtering on the surface of the medium 1 obtained in step (1), with a vacuum degree of 5*10⁻⁶ during sputtering. - 4 Pa; then argon gas was introduced at a flow rate of 20 ml / min, working pressure of 0.5 Pa, vacuum chamber temperature of 120–180 °C, sputtering time of 60–120 s, sputtering power of 60–80 W, and the thickness of seed layer 2 (nickel + titanium layer) after secondary sputtering was 0.7–1.0 μm.

[0048] S2. As shown in Figure 1, electroplating is performed on the seed layer 2 to obtain a fine circuit layer 4. Specifically, the fine circuit layer 4 can be fabricated using the mSAP process; for example, it includes:

[0049] (a) A high-resolution dry film 3 or photoresist is used to cover the seed layer 2. In this embodiment, a dry film 3 is used to cover the seed layer 2, and exposure and development are performed. An LDI exposure machine can be used for exposure. After development, plasma is used to remove the residue of the dry film 3. The plasma gas ratio is O2:N2:CF4=7:3:1, the temperature is 70℃, the power is 6~8KW, and the time is 15~30min.

[0050] (b) Using the seed layer 2 formed by sputtering as a conductive layer, pattern electroplating and circuit addition are performed to form an electroplated circuit on the seed layer 2.

[0051] (c) The dielectric 1 having the seed layer 2 and the electroplated lines is stripped and flash-etched to remove the dry film 3 or photoresist and the seed layer 2 at the dry film 3 or photoresist-covered areas, thereby obtaining a fine line layer 4 on the dielectric 1.

[0052] During the flash etching process in step (c), a solution with etching properties for titanium and nickel is selected. During the electroplating process in step (b), the electroplating parameters are 10–15 ASF, the electroplating time is 45–60 min, and a low current is used to obtain better line uniformity.

[0053] Furthermore, for a detailed implementation of step S2 in this embodiment, please refer to the existing mSAP process.

[0054] S3. As shown in Figure 2, the dielectric 1 with the fine circuit layer 4 is stacked with the LCP substrate 5, and then high-temperature pressing is performed with pressing auxiliary materials. The fluidity of the LCP substrate 5 at high temperature is used to fill the gaps in the fine circuit layer 4.

[0055] Furthermore, before laminating the dielectric 1 with the fine circuit layer 4 to the LCP substrate 5, the fine circuit layer 4 on the dielectric 1 is subjected to a medium-roughening treatment to improve the reliability after high-temperature lamination. In addition, alignment target points can be made on the dielectric 1, followed by the fabrication of positioning holes to improve the lamination accuracy of the dielectric 1 and the LCP substrate 5. After lamination, high-temperature lamination is performed, with auxiliary materials including HDPE, PTFE, aluminum foil, etc. The lamination temperature is 290-330℃, the pressure is 300-350psi, and the lamination time is 2.5h.

[0056] S4. As shown in Figure 2, the dielectric 1 is removed by plasma etching or chemical etching, exposing the side of the fine circuit layer 4 containing the seed layer 2. Subsequently, the seed layer 2 is removed by micro-etching to obtain the semi-buried circuit LCP. This step of removing the seed layer 2 helps to reduce the loss caused by the skin effect of the fine circuit at high frequencies.

[0057] S5. By repeating steps S1 to S4, two semi-embedded line LCPs are obtained, namely the first semi-embedded line LCP6 ​​and the second semi-embedded line LCP7.

[0058] S6. As shown in Figure 3, the first semi-embedded circuit LCP6 ​​and the second semi-embedded circuit LCP7 are stacked and subjected to high-temperature pressing. During high-temperature pressing, a middle layer LCP substrate 8 is stacked between the first semi-embedded circuit LCP6 ​​and the second semi-embedded circuit LCP7. After high-temperature stacking, a fine circuit structure 9 embedded in the LCP material is finally obtained.

[0059] Furthermore, in step S6, the Tg point of the intermediate LCP substrate 8 is lower than that of the first semi-embedded circuit LCP6 ​​and the second semi-embedded circuit LCP7; and the temperature required for high-temperature pressing in step S6 is lower than that required for high-temperature pressing in step S3. By using the intermediate LCP substrate 8 with a lower Tg point, the required temperature for high-temperature pressing is lower than the Tg points of the first semi-embedded circuit LCP6 ​​and the second semi-embedded circuit LCP7. This prevents the already cured first semi-embedded circuit LCP6 ​​and the second semi-embedded circuit LCP7 from melting, while still allowing for pressing with the intermediate LCP substrate 8, which is beneficial for improving the overall quality of the product. In this embodiment, the Tg point refers to the critical temperature at which the substrate melts from a solid state to a rubbery fluid, i.e., the melting point; a higher Tg point indicates a higher temperature requirement for high-temperature pressing of the substrate.

[0060] In this embodiment, the processing method involves forming a seed layer 2 (approximately 0.2 μm) on a dielectric 1 using vacuum magnetron sputtering. Fine circuitry is then fabricated using mSAP technology. Since the seed layer 2 on the surface of dielectric 1 is thinner than the base copper layer (approximately 2-3 μm) in modified mSAP, the impact of base copper side etching on the circuitry is reduced. Simultaneously, the fabricated fine circuitry is embedded into an LCP substrate 5 through high-temperature lamination. Under high temperature and pressure, the LCP substrate 5 becomes a viscous flow state to fill the circuitry, achieving semi-embedded circuitry. Furthermore, this embodiment removes dielectric 1 using plasma etching or chemical etching to expose the seed layer 2. The exposed seed layer 2 is then removed through micro-etching or flash etching, eliminating losses caused by metal interfaces. Finally, the first semi-embedded circuit LCP6 ​​and the second semi-embedded circuit LCP7, containing the semi-embedded fine circuitry layer 4, are subjected to high-temperature lamination to achieve a PCB structure with fine circuitry embedded in LCP material. This structure is a pure LCP high-temperature lamination, eliminating signal transmission losses caused by dielectric 1 interfaces.

[0061] Example 2

[0062] Referring to Figures 4-6, the difference between this embodiment and Embodiment 1 is that the medium 1 is a copper foil substrate, which can be a single-sided copper-clad laminate or a double-sided copper-clad laminate.

[0063] As shown in Figure 4, in this embodiment, when performing step (c) of step S2, after stripping and flash etching of the dielectric 1 with seed layer 2 and electroplated lines, the copper metal layer on the dielectric 1 also needs to be etched.

[0064] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for fabricating fine circuits embedded in 5G high-frequency LCP material, characterized in that, Includes the following steps: S1. Vacuum magnetron sputtering is performed on the surface of the dielectric to deposit a conductive seed layer on the surface of the dielectric. Vacuum magnetron sputtering on a dielectric surface includes: (1) sputtering a nickel layer on the dielectric surface, followed by introducing argon gas; (2) performing a second sputtering on the dielectric surface after step (1), followed by introducing argon gas to form a seed layer containing a nickel layer and a titanium layer; S2) performing circuit electroplating on the seed layer to obtain a fine circuit layer on the seed layer; S3) stacking the dielectric with the fine circuit layer with an LCP substrate and performing high-temperature pressing treatment to fill the gaps in the fine circuit layer with the LCP substrate; S4) removing the dielectric to expose the side of the fine circuit layer containing the seed layer; then removing the seed layer to obtain a semi-buried circuit LCP; S5) obtaining two semi-buried circuit LCPs by repeating steps S1-S4, namely the first semi-buried circuit LCP. S6. The first and second semi-embedded circuit LCPs are stacked and subjected to high-temperature pressing to obtain a fine circuit structure embedded in the LCP material. In step S6, a middle layer LCP substrate is stacked between the first and second semi-embedded circuit LCPs. The first, second, and middle layer LCP substrates are subjected to high-temperature pressing to obtain a fine circuit structure embedded in the LCP material. The Tg point of the middle layer LCP substrate is lower than that of the first and second semi-embedded circuit LCPs. The temperature required for high-temperature pressing in step S6 is lower than that required for high-temperature pressing in step S3.

2. The processing method for embedding fine circuits in 5G high-frequency LCP material according to claim 1, characterized in that, In step S2, electroplating of circuits is performed on the seed layer on the surface of the dielectric, including: (a) covering the seed layer with a high-resolution dry film or photoresist and performing exposure and development treatments; (b) using the sputtered seed layer as a conductive layer for pattern electroplating and circuit addition, thereby obtaining electroplated circuits on the seed layer; (c) performing stripping and flash etching treatments on the dielectric with the seed layer and electroplated circuits to remove the dry film or photoresist and the seed layer at the locations covered by the dry film or photoresist, thereby obtaining a fine circuit layer on the dielectric.

3. The processing method for embedding fine circuits in 5G high-frequency LCP material according to claim 2, characterized in that, In step (a), after the development process is completed, plasma is used to remove the residue of dry film or photoresist.

4. The processing method for embedding fine circuits in 5G high-frequency LCP material according to claim 2, characterized in that, In step (c), during the flash etching process, a solution with etching properties for titanium and nickel is selected.

5. The processing method for embedding fine circuits in 5G high-frequency LCP material according to claim 1, characterized in that, In step S3, before the dielectric with fine circuit layer is laminated with the LCP substrate, the fine circuit layer on the dielectric is roughened to improve the reliability after high-temperature lamination.

6. The processing method for embedding fine circuits in 5G high-frequency LCP material according to claim 1, characterized in that, In step S4, the medium is removed by plasma etching or chemical etching; the seed layer is removed by micro-etching.

7. A processing method for embedding fine circuits in 5G high-frequency LCP material according to any one of claims 1-6, characterized in that, The medium is a pure dielectric material.

8. A processing method for embedding fine circuits in 5G high-frequency LCP material according to any one of claims 1-6, characterized in that, The medium is a copper foil substrate.

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