Composite PCB, preparation method and application thereof

Abstract

The application provides a composite PCB, a preparation method and application thereof, and the method comprises the following steps: cutting ceramic raw materials into ceramic blanks, arranging a copper plating layer on the surface of the ceramic blank to obtain a ceramic substrate; obtaining a resin core plate, opening an embedding groove penetrating through the resin core plate in the length direction on the top surface of the resin core plate, embedding the ceramic substrate into the embedding groove, and making the opposite two end surfaces of the ceramic substrate flush with the opposite two side surfaces of the resin core plate to form an initial PCB; arranging an interconnection structure on the side surface of the initial PCB to form a composite PCB. The heat generated by the LED chip is conducted to the ceramic substrate, and the heat is quickly conducted to the whole plate body through the interconnection structure, so that high-efficiency heat dissipation is realized; the thermal expansion coefficients of the ceramic and the metal are matched, the thermal stress is greatly reduced, and the influence of the excessively high thermal stress on product quality can be reduced; the resin core plate serves as a carrier of the driving circuit integration function, the cost is significantly reduced compared with the full ceramic plate, and the balance between performance and cost is realized.

Description

Technical Field

[0001] This invention relates to the field of printed circuit board technology, and in particular to a composite PCB, its preparation method, and its application. Background Technology

[0002] In the current automotive lighting field, the widespread adoption of advanced technologies such as LED, Micro-LED, and ADB has led to a continuous increase in the power density of automotive lights. As a result, the requirements for the heat dissipation performance of PCB boards are becoming increasingly stringent.

[0003] Traditional PCBs are typically made of metal substrates (such as aluminum substrates), with a thermal conductivity of only 1W / mK to 3W / mK. Their limited heat dissipation capacity becomes a performance bottleneck for high-power, high-density automotive lighting designs. Furthermore, they are prone to thermal stress at high temperatures, which can lead to solder joint cracking and premature LED failure, affecting driving safety and product lifespan. While all-ceramic boards can provide excellent thermal conductivity, they are more expensive and lack design flexibility, making it difficult to meet the needs of complex circuit wiring and mechanical support. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a composite PCB, a preparation method and its application, which aims to solve the technical problems of limited heat dissipation capacity and insufficient reliability of metal substrates, and high cost and insufficient design flexibility of ceramic substrates in the prior art.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a method for preparing a composite PCB, comprising the following steps: Ceramic raw materials are cut into ceramic blanks, and a copper plating layer is applied to the surface of the ceramic blanks to obtain a ceramic substrate. A resin core board is obtained, and a groove is made on the top surface of the resin core board. The groove extends through the resin core board in the length direction. The ceramic substrate is aligned with the groove, and the ceramic substrate is embedded into the groove using a preset pressing process. The two opposite ends of the ceramic substrate are flush with the two opposite sides of the resin core board to form an initial PCB. An interconnection structure is provided on the side of the initial PCB to electrically interconnect the ceramic substrate and the resin core board, thereby forming a composite PCB.

[0006] Furthermore, the step of forming a copper plating layer on the surface of the ceramic blank includes: A titanium-tungsten transition layer is formed on the surface of the ceramic blank by a first sputtering process, and a copper seed layer is formed on the surface of the titanium-tungsten transition layer by a second sputtering process; A copper layer is electroplated onto the surface of the copper seed layer.

[0007] Furthermore, the thickness of the titanium-tungsten transition layer is 0.04μm~0.06μm, the thickness of the copper seed layer is 0.08μm~0.12μm, and the thickness of the copper plating layer is 0.3μm~0.6μm.

[0008] Furthermore, the preset pressing process includes pressing temperature, pressing pressure and pressing time, wherein the pressing temperature is 170℃~190℃, the pressing pressure is 2.5MPa~3.5MPa and the pressing time is 80min~100min.

[0009] Furthermore, the interconnect structure includes a copper interconnect layer and a buffer adhesive layer.

[0010] Furthermore, the step of setting the interconnect structure on the side of the initial PCB includes: A copper plating process is performed on the side of the initial PCB to form an initial copper layer, which covers the end face of the ceramic substrate and the side face of the resin core board. A thickened copper layer is electroplated on the initial copper layer, and the initial copper layer and the thickened copper layer constitute the copper interconnect layer; A polyimide adhesive is coated on the side of the initial PCB to form the buffer adhesive layer, which covers the end face of the ceramic substrate and the side face of the resin core board.

[0011] Furthermore, the temperature of the copper plating process is 38℃~42℃, the thickness of the initial copper layer is 0.02μm, and the thickness of the copper interconnect layer is 0.3μm.

[0012] Furthermore, the ceramic raw material is aluminum nitride.

[0013] Secondly, the present invention provides a composite PCB, which is prepared by the composite PCB preparation method described in the first aspect above.

[0014] Thirdly, the present invention provides the application of the composite PCB as described in the second aspect above in the fabrication of display modules for automotive lights.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: when the LED chip is working, the heat generated by it is directly conducted to the ceramic substrate, and the heat is quickly conducted to the entire board of the composite PCB through the interconnection structure, thereby achieving efficient heat dissipation; the thermal expansion coefficients of ceramic and metal are matched, which greatly reduces thermal stress and can reduce the impact of excessive thermal stress on product quality; the resin core board serves as the carrier for the integrated function of the driving circuit, and its cost is significantly reduced compared with the all-ceramic board, achieving a balance between performance and cost. Attached Figure Description

[0016] Figure 1 This is a flowchart of the composite PCB fabrication method in Embodiment 1 of the present invention; Figure 2 The diagram shows the structure of the composite PCB prepared by the method described in Embodiment 1 of the present invention. The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0017] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of the invention are illustrated in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0018] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0019] 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 specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0020] Please see Figure 1 and Figure 2 In a first aspect, Embodiment 1 of the present invention provides a method for preparing a composite PCB, comprising the following steps: S10: Cut the ceramic raw material into a ceramic blank, and deposit a copper plating layer on the surface of the ceramic blank to obtain a ceramic substrate; In this embodiment, ultraviolet laser technology is used to cut ceramic raw materials. Preferably, the ceramic raw materials are aluminum nitride or aluminum oxide. In this embodiment, the ceramic raw materials are aluminum nitride.

[0021] Step S10 includes: S110: A titanium-tungsten transition layer is formed on the surface of the ceramic blank by a first sputtering process, and a copper seed layer is formed on the surface of the titanium-tungsten transition layer by a second sputtering process; The vacuum degree of the first sputtering process and the second sputtering process is less than or equal to 5 × 10⁻⁶. -³Pa.

[0022] S120: Electroplating a copper layer onto the surface of the copper seed layer; The thickness of the titanium-tungsten transition layer is 0.04 μm to 0.06 μm, the thickness of the copper seed layer is 0.08 μm to 0.12 μm, and the thickness of the copper plating layer is 0.3 μm to 0.6 μm. In this embodiment, the thickness of the titanium-tungsten transition layer is 0.05 μm, the thickness of the copper seed layer is 0.1 μm, and the thickness of the copper plating layer is 0.5 μm. The copper plating layer is electroplated using an acidic copper sulfate electroplating process. By setting the titanium-tungsten transition layer and the copper seed layer, the copper plating layer can cover the ceramic substrate, thereby achieving subsequent electrical interconnection with the resin core board.

[0023] After obtaining the ceramic substrate, a circuit pattern is formed on the surface of the ceramic substrate by photolithography. The etching solution is a copper chloride solution, and the etching temperature is 45°C.

[0024] S20: Obtain a resin core board, open a groove on the top surface of the resin core board, the groove penetrates the resin core board in the length direction, align the ceramic substrate to the groove, and embed the ceramic substrate into the groove using a preset pressing process, the opposite two end faces of the ceramic substrate are flush with the opposite two side faces of the resin core board to form an initial PCB. In this embodiment, the resin core board is an FR-4 core board. Understandably, the resin material is cut into the resin core board. After obtaining the resin core board, the peripheral circuit pattern is fabricated using a dry film photolithography process, and then etched using an alkaline etching solution at a temperature of 35°C. The linewidth accuracy after etching is ±0.03mm to form the inner layer circuit.

[0025] Using a CNC milling machine, the groove is milled into the top surface of the resin core board, and the verticality of the groove wall is ≤0.01mm.

[0026] The preset pressing process includes pressing temperature, pressing pressure, and pressing time. The pressing temperature is 180°C, and the pressing pressure is 3 MPa. Preferably, the pressing time is 80 min to 100 min; in this embodiment, the pressing time is 90 min. Specifically, after the ceramic substrate is placed in the groove, a prepreg and a copper foil are sequentially covered on its upper surface, and then it is placed in a pressing machine for pressing using the preset pressing process, so that the ceramic substrate is embedded in the groove. It can be understood that because the groove is through-hole, the opposite two ends of the ceramic substrate are connected to the outside.

[0027] S30: An interconnection structure is provided on the side of the initial PCB to electrically interconnect the ceramic substrate and the resin core board, thereby forming a composite PCB; The interconnect structure includes a copper interconnect layer and a buffer bonding layer.

[0028] Specifically, step S30 includes: S310: A copper plating process is performed on the side of the initial PCB to form an initial copper layer, the initial copper layer covering the end face of the ceramic substrate and the side face of the resin core board. In this embodiment, the copper plating treatment uses a formaldehyde system. Preferably, the temperature of the copper plating treatment is 38℃~42℃; in this embodiment, the temperature of the copper plating treatment is 40℃.

[0029] S320: A thickened copper layer is electroplated on the initial copper layer, wherein the initial copper layer and the thickened copper layer constitute the copper interconnect layer; The initial copper layer has a thickness of 0.02 μm, and the copper interconnect layer has a thickness of 0.3 μm. Electrical interconnection between the ceramic substrate and the resin core board is achieved through simultaneous contact between the copper-plated layer and the copper interconnect layer.

[0030] S330: A polyimide adhesive is coated on the side of the initial PCB to form the buffer adhesive layer, which covers the end face of the ceramic substrate and the side face of the resin core board.

[0031] By providing the buffer adhesive layer, a stable connection between the ceramic substrate and the resin core board can be ensured.

[0032] After completing the interconnect structure and forming the composite PCB, the inner layer circuit fabrication process is repeated to complete the outer layer circuit setup. Further, photosensitive solder resist ink is coated, exposed, developed, and cured to complete the solder resist process. Chemical nickel-gold plating is then used to complete the surface treatment of the composite PCB, with a nickel layer thickness of 0.05 μm and a gold layer thickness of 0.01 μm. Understandably, LED chips for light emission are disposed on the composite PCB, and the positions of the LED chips correspond to those of the ceramic substrate.

[0033] When the LED chip is working, the heat it generates is directly conducted to the ceramic substrate, and then quickly conducted to the entire composite PCB through the interconnection structure, achieving efficient heat dissipation. The matching thermal expansion coefficients of ceramic and metal significantly reduce thermal stress, which can reduce the impact of excessive thermal stress on product quality. The resin core board serves as the carrier for the integrated function of the driving circuit, and its cost is significantly lower than that of the all-ceramic board, achieving a balance between performance and cost.

[0034] Embodiment 2 of the present invention provides a method for preparing a composite PCB, which differs from the method for preparing a composite PCB described in Embodiment 1 in that... The pressing temperature is 170°C.

[0035] Embodiment 3 of the present invention provides a method for preparing a composite PCB, which differs from the method for preparing a composite PCB described in Embodiment 1 in that... The pressing temperature is 190°C.

[0036] Embodiment 4 of the present invention provides a method for preparing a composite PCB, which differs from the method for preparing a composite PCB described in Embodiment 1 in that... The pressing pressure is 2.5 MPa.

[0037] Embodiment 5 of the present invention provides a method for preparing a composite PCB, which differs from the method for preparing a composite PCB described in Embodiment 1 in that... The pressing pressure is 3.5 MPa.

[0038] Comparative Example 1 of this invention provides a method for preparing a composite PCB, which differs from the method for preparing a composite PCB described in Example 1 in that... The pressing temperature is 140°C.

[0039] Comparative Example 2 of this invention provides a method for preparing a composite PCB, which differs from the method for preparing a composite PCB described in Example 1 in that... The pressing temperature is 220°C.

[0040] Comparative Example 3 of this invention provides a method for preparing a composite PCB, which differs from the method for preparing a composite PCB described in Example 1 in that... The pressing pressure is 1 MPa.

[0041] Comparative Example 4 of this invention provides a method for preparing a composite PCB, which differs from the method for preparing a composite PCB described in Example 1 in that... The pressing pressure is 5 MPa.

[0042] Comparative Example 5 of this invention provides a method for preparing a composite PCB, which differs from the method for preparing a composite PCB described in Example 1 in that... PCBs are manufactured using traditional processes, namely, by fabricating PCBs using metal substrates.

[0043] Composite PCBs were prepared based on the methods described in Examples 1-5 and Comparative Examples 1-5 of this invention. The core hot spot temperature was measured, and the luminous flux maintenance rate was continuously tested. The test results are shown in Table 1 below. Table 1 , Among them, the luminous flux maintenance test, after obtaining the initial luminous efficacy (lm / W), continuously emits light and detects the ratio between the final luminous efficacy and the initial luminous efficacy after 3000h. As can be seen from the table, by controlling the preset lamination process, it can be ensured that the prepared composite PCB has excellent thermal conductivity and reduce the decline in product quality caused by thermal stress.

[0044] Secondly, Embodiment 6 of the present invention provides a composite PCB, which is prepared by the composite PCB preparation method described in the above embodiments.

[0045] Thirdly, Embodiment 7 of the present invention provides the application of the composite PCB as described in Embodiment 6 in the fabrication of a display module for a vehicle lamp, wherein the vehicle lamp is an ADB adaptive high beam, a matrix LED headlight, or a Micro-LED pixel lamp.

[0046] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0047] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for fabricating a composite PCB, characterized in that, Includes the following steps: Ceramic raw materials are cut into ceramic blanks, and a copper plating layer is applied to the surface of the ceramic blanks to obtain a ceramic substrate. A resin core board is obtained, and a groove is made on the top surface of the resin core board. The groove extends through the resin core board in the length direction. The ceramic substrate is aligned with the groove, and the ceramic substrate is embedded into the groove using a preset pressing process. The two opposite ends of the ceramic substrate are flush with the two opposite sides of the resin core board to form an initial PCB. An interconnection structure is provided on the side of the initial PCB to electrically interconnect the ceramic substrate and the resin core board, thereby forming a composite PCB.

2. The method for preparing a composite PCB according to claim 1, characterized in that, The step of forming a copper plating layer on the surface of the ceramic blank includes: A titanium-tungsten transition layer is formed on the surface of the ceramic blank by a first sputtering process, and a copper seed layer is formed on the surface of the titanium-tungsten transition layer by a second sputtering process; A copper layer is electroplated onto the surface of the copper seed layer.

3. The method for preparing a composite PCB according to claim 2, characterized in that, The thickness of the titanium-tungsten transition layer is 0.04μm~0.06μm, the thickness of the copper seed layer is 0.08μm~0.12μm, and the thickness of the copper plating layer is 0.3μm~0.6μm.

4. The method for preparing a composite PCB according to claim 3, characterized in that, The preset pressing process includes pressing temperature, pressing pressure and pressing time. The pressing temperature is 170℃~190℃, the pressing pressure is 2.5MPa~3.5MPa and the pressing time is 80min~100min.

5. The method for preparing a composite PCB according to claim 1, characterized in that, The interconnect structure includes a copper interconnect layer and a buffer bonding layer.

6. The method for preparing a composite PCB according to claim 5, characterized in that, The step of setting the interconnect structure on the side of the initial PCB includes: A copper plating process is performed on the side of the initial PCB to form an initial copper layer, which covers the end face of the ceramic substrate and the side face of the resin core board. A thickened copper layer is electroplated on the initial copper layer, and the initial copper layer and the thickened copper layer constitute the copper interconnect layer; A polyimide adhesive is coated on the side of the initial PCB to form the buffer adhesive layer, which covers the end face of the ceramic substrate and the side face of the resin core board.

7. The method for preparing a composite PCB according to claim 6, characterized in that, The copper plating process is performed at a temperature of 38°C to 42°C, the initial copper layer has a thickness of 0.02 μm, and the copper interconnect layer has a thickness of 0.3 μm.

8. The method for preparing a composite PCB according to claim 1, characterized in that, The ceramic raw material is aluminum nitride or aluminum oxide.

9. A composite PCB, characterized in that, The composite PCB is prepared according to the composite PCB preparation method according to any one of claims 1 to 8.

10. The application of the composite PCB as described in claim 9 in the fabrication of a display module for automotive lights.

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