HDI circuit board

Abstract

This utility model discloses an HDI circuit board. The HDI circuit board of this utility model includes a motherboard and HDI circuit layers, the HDI circuit layers being disposed on two opposite surfaces of the motherboard. The motherboard includes an insulating substrate of organic material and conductive lines disposed on the surface and inside the insulating substrate. A ceramic sheet with a thickness of 0.1mm to 0.5mm is disposed within the motherboard, extending to the outer edge of the motherboard in the direction of the HDI circuit board surface. By incorporating a ceramic sheet within the motherboard, this utility model not only effectively suppresses warping deformation of the circuit board but also enhances its heat dissipation performance.

Description

Technical Field

[0001] This utility model relates to an HDI circuit board. Background Technology

[0002] HDI (High-Density Interconnect) circuit boards consist of a motherboard and multilayer circuitry disposed on the surface of the motherboard. Compared to traditional circuit boards, HDI circuit boards offer numerous advantages, including increased circuit density, reduced product size and weight, and improved signal transmission speed and reliability between electronic components. In existing HDI circuit boards, the motherboard typically uses conventional organic materials (such as FR-4 circuit boards). The coefficient of thermal expansion in the thickness direction of such HDI circuit boards is much greater than that in the surface direction, making them prone to undesirable warping deformation during the high-temperature soldering of electronic components.

[0003] Because HDI circuit boards have a denser circuit layout, they not only require better heat dissipation performance, but also have higher requirements for the positional accuracy of the pads on the circuit board surface. This means that even if the warping deformation of the circuit board is small during the soldering process of electronic components, the positional deviation of the pads on the circuit board surface can easily exceed the allowable design range, leading to soldering defects of electronic components. Utility Model Content

[0004] The main purpose of this invention is to provide an HDI circuit board that helps to suppress warping and enhance heat dissipation.

[0005] To achieve the aforementioned main objectives, this utility model discloses an HDI circuit board, comprising a motherboard and an HDI circuit stack, wherein the HDI circuit stack is disposed on two opposite surface sides of the motherboard; wherein the motherboard comprises an insulating substrate of organic material and conductive lines disposed on the surface and inside of the insulating substrate, and a ceramic sheet with a thickness of 0.1mm to 0.5mm is disposed inside the motherboard, the ceramic sheet extending to the outer edge of the motherboard in the board surface direction of the HDI circuit board.

[0006] Furthermore, the thickness of the ceramic sheet is 0.15mm to 0.3mm.

[0007] According to a specific embodiment of the present invention, the ceramic sheet is disposed between the outermost layer circuit and the second outermost layer circuit on the two surfaces of the mother plate.

[0008] According to another specific embodiment of the present invention, the ceramic sheet is disposed between the inner core plates of the mother plate.

[0009] Furthermore, the ceramic sheet is positioned at the middle of the mother plate in the thickness direction.

[0010] Furthermore, there are multiple ceramic sheets, and the multiple ceramic sheets are symmetrically arranged with respect to the center plane of the mother plate in the thickness direction (including the arrangement of one ceramic sheet located on the center plane).

[0011] Furthermore, the ceramic sheet is a silicon nitride, aluminum nitride, boron nitride, silicon carbide, aluminum oxide, or beryllium oxide ceramic sheet.

[0012] Furthermore, the ceramic sheet is a bare ceramic sheet with no metal on its surface.

[0013] Furthermore, the ceramic sheet is a metallized ceramic sheet with conductive lines on its surface.

[0014] Furthermore, the HDI circuit board has conductive holes passing through the ceramic sheet.

[0015] The technical solution of this utility model has at least the following beneficial effects:

[0016] In this invention, a ceramic sheet is provided inside the motherboard of the HDI circuit board. The ceramic sheet extends to the outer edge of the motherboard in the direction of the HDI circuit board surface. This can effectively suppress the warping and deformation of the HDI circuit board at the soldering temperature, thereby improving the soldering quality of electronic components and improving the heat dissipation performance of the HDI circuit board.

[0017] To more clearly illustrate the purpose, technical solution, and advantages of this utility model, the following detailed description is provided in conjunction with the accompanying drawings and specific embodiments. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the HDI circuit board in Embodiment 1 of this utility model;

[0019] Figure 2 This is a schematic diagram of the HDI circuit board in Embodiment 2 of this utility model;

[0020] Figure 3 This is a schematic diagram of the structure of the HDI circuit board in Embodiment 3 of this utility model. Detailed Implementation

[0021] Many specific details are set forth in the following description in conjunction with embodiments in order to provide a full understanding of the present invention. However, it should be understood that the following embodiments and detailed description are for illustrative purposes only and do not limit the scope of protection of the present invention.

[0022] Example 1

[0023] like Figure 1As shown, the HDI circuit board disclosed in the embodiment includes a motherboard 100 and an HDI circuit stack 200, the HDI circuit stack 200 being disposed on two opposite surface sides of the motherboard 100. Preferably, the HDI circuit stack 200 located on the two opposite surface sides of the motherboard 100 has the same number of circuit layers and thickness, which helps to reduce the warping deformation of the circuit board.

[0024] The motherboard 100 includes an organic insulating substrate and conductive lines disposed on and inside the insulating substrate. A ceramic sheet 130 is provided within the motherboard 100, extending to the outer edge of the motherboard 100 in the direction of the HDI circuit board's surface. Compared to the organic insulating substrate, the ceramic sheet 130 has a higher thermal conductivity and a lower coefficient of thermal expansion, with its coefficients of thermal expansion in the thickness and surface directions being essentially the same or close. This effectively suppresses warping deformation of the HDI circuit board and enhances its heat dissipation performance.

[0025] The ceramic sheet 130 can be a silicon nitride, aluminum nitride, boron nitride, silicon carbide, alumina, or beryllium oxide ceramic sheet, with silicon nitride being preferred. The ceramic sheet 130 can be a bare ceramic sheet without metal on its surface, eliminating the need for surface metallization treatment and reducing manufacturing costs. The thickness of the ceramic sheet 130 can be 0.1mm to 0.5mm, preferably 0.15mm to 0.3mm, to facilitate laser drilling and reduce the cost of the ceramic sheet (smaller thicknesses are more difficult and costly to produce, while thicker thicknesses are more expensive to laser drill).

[0026] In Example 1, the motherboard 100 is provided with two ceramic sheets 130. The two ceramic sheets 130 are respectively disposed between the outermost layer circuit and the second outermost layer circuit on the two surfaces of the motherboard 100. This allows the ceramic sheets 130 to be as close as possible to the surface of the HDI circuit board, thereby achieving better warping suppression and heat dissipation performance.

[0027] For example, the motherboard 100 has 18 conductive lines from L3 to L20, and one of the two HDI circuit stacks 200 has conductive lines L1 and L2, while the other has conductive lines L21 and L22. It is easy to understand that the number of lines in the motherboard 100 and the HDI circuit stack 200 can be set as needed; for example, the HDI circuit stack 200 can have one or more lines, and this invention does not impose any limitations on this.

[0028] In Example 1, L3 and L20 are the outermost circuit layers of the motherboard 100, and L4 and L19 are the next outermost circuit layers of the motherboard 100. A ceramic sheet 130 is disposed between the L3 and L4 circuit layers and between the L19 and L20 circuit layers. During fabrication, a core board with L4-L19 circuit layers can be fabricated first using conventional circuit board lamination methods. Then, a resin-containing adhesive sheet 120 (e.g., a prepreg), a ceramic sheet 130, an adhesive sheet 120, and copper foil for forming the L3 circuit layer are laminated on one side of the L4 circuit layer of this core board. Simultaneously, an adhesive sheet 120, a ceramic sheet 130, an adhesive sheet 120, and copper foil for forming the L20 circuit layer are laminated on the other side of the L19 circuit layer. After etching the copper foil, the HDI circuit stack 200 can be fabricated.

[0029] The core board adopts a stacked structure with alternating inner core boards 110 and adhesive sheets 120. The L4 and L19 circuit layers can be directly mounted on their respective adhesive sheets 120, while other circuit layers are mounted in pairs on corresponding inner core boards 110 (for example, L5 and L6 circuit layers are mounted on the same inner core board 110, resulting in a double-sided circuit board structure). Adjacent inner core boards 110 are bonded together using adhesive sheets 120. In this invention, the organic inner core boards 110 and adhesive sheets 120 constitute the insulating substrate of the motherboard 100.

[0030] Furthermore, the ceramic sheet 130 has resin-filled vias filled by the adhesive sheet 120, and the HDI circuit board has conductive vias passing through the resin-filled vias on the ceramic sheet 130, such as conductive buried vias 302 disposed inside the circuit board and conductive through-holes 301 penetrating the circuit board. The conductive buried vias 302 enable electrical connection between the L2 and L21 circuit layers and the corresponding conductive lines within the motherboard 100, while the conductive through-holes 301 enable electrical connection between the L1 and L22 circuit layers and the corresponding conductive lines within the motherboard 100.

[0031] Example 2

[0032] In Example 2, the ceramic sheet 130 is disposed between the inner core plates 110 of the mother plate 100, and is located at the middle position of the mother plate 100 in the thickness direction of the mother plate 100 (e.g., Figure 2 (As shown).

[0033] Example 3

[0034] In embodiment 3, ceramic sheets 130 are disposed between the inner core plates 110 of the mother plate 100. There are multiple ceramic sheets 130, and preferably, these multiple ceramic sheets 130 are symmetrically arranged with respect to the center plane of the mother plate 100 in the thickness direction (e.g., ...). Figure 3(As shown). Furthermore, in embodiment 3, a ceramic sheet 130 can also be provided on the center surface of the motherboard 100 in the thickness direction. By symmetrically arranging multiple ceramic sheets 130, the warping deformation of the circuit board can be better suppressed and the heat dissipation effect can be improved.

[0035] As a variation of the above embodiments, the ceramic sheet 130 can also be a metallized ceramic sheet with conductive lines on its surface, which is beneficial for reducing the thickness of the circuit board. It is easy to understand that embodiments 1-3 can also be combined, that is, the ceramic sheet 130 can be provided between the outermost and second outermost lines of the motherboard 100 and between the inner core board 110.

[0036] Although the present invention has been disclosed above with reference to specific embodiments, these specific embodiments are not intended to limit the scope of the present invention. Any person skilled in the art may make some changes / substitutions without departing from the scope of the present invention; that is, all equivalent changes made in accordance with the present invention should be covered by the protection scope of the present invention.

Claims

1. An HDI circuit board, comprising a motherboard and HDI circuit stacks, wherein the HDI circuit stacks are disposed on two opposite surfaces of the motherboard; characterized in that: The motherboard includes an insulating substrate made of organic material and conductive lines disposed on the surface and inside the insulating substrate. The motherboard contains a ceramic sheet with a thickness of 0.1 mm to 0.5 mm, which extends to the outer edge of the motherboard in the direction of the HDI circuit board.

2. The HDI circuit board according to claim 1, characterized in that: The thickness of the ceramic sheet is 0.15mm to 0.3mm.

3. The HDI circuit board according to claim 1, characterized in that: The ceramic sheet is disposed between the outermost and second outermost layers of circuitry on the two surfaces of the motherboard.

4. The HDI circuit board according to claim 1, characterized in that: The ceramic sheet is disposed between the inner core plates of the mother plate.

5. The HDI circuit board according to claim 4, characterized in that: The ceramic sheet is positioned at the middle of the mother plate in the thickness direction.

6. The HDI circuit board according to claim 4, characterized in that: The number of ceramic sheets is multiple, and the multiple ceramic sheets are symmetrically arranged with respect to the center plane of the mother plate in the thickness direction.

7. The HDI circuit board according to claim 1, characterized in that: The ceramic sheet is a silicon nitride, aluminum nitride, boron nitride, silicon carbide, aluminum oxide, or beryllium oxide ceramic sheet.

8. The HDI circuit board according to claim 1, characterized in that: The ceramic sheet is a bare ceramic sheet without metal on its surface.

9. The HDI circuit board according to claim 1, characterized in that: The ceramic sheet is a metallized ceramic sheet with conductive lines on its surface.

10. The HDI circuit board according to claim 1, characterized in that: The HDI circuit board has conductive holes that pass through the resin-filled holes of the ceramic sheet.

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