A heat dissipation structure for HDI boards to improve surface flatness and the HDI board itself.

Abstract

This invention proposes a heat dissipation structure and HDI board for improving surface flatness, including a motherboard. The motherboard has a top heat dissipation layer and a bottom heat dissipation layer on its top and bottom surfaces, respectively. Several intermediate heat dissipation layers are disposed within the motherboard. Several top laser-guided blind vias are formed on the top of the motherboard. The advantages of this invention are: by setting up the top heat dissipation layer, bottom heat dissipation layer, intermediate heat dissipation layer, top laser-guided blind vias, and bottom laser-guided blind vias on the top and bottom surfaces of the circuit board, the flatness problem caused by mechanical through-holes is solved by utilizing the characteristics of laser-guided blind vias. Simultaneously, heat from the circuit board is conducted through either the top laser-guided blind via – mechanical through-hole – bottom laser-guided blind via or the top laser-guided blind via – heat-conducting pillar – bottom laser-guided blind via. Heat conduction is not affected by the lack of connection between the mechanical through-holes and the top / bottom laser-guided blind vias; heat can also be quickly conducted even where mechanical through-holes are not present, resulting in superior heat dissipation.

Description

Technical Field

[0001] This utility model relates to the field of circuit board technology, and in particular to a heat dissipation structure for HDI boards that improves surface flatness and an HDI board. Background Technology

[0002] HDI boards, or high-density interconnect boards, represent cutting-edge technology in the printed circuit board (PCB) field. Their core feature lies in achieving high-density circuitry through micro-blind vias and buried vias, overcoming the physical limitations of traditional PCBs.

[0003] Traditional heat dissipation structures involve laying a large area of ​​copper underneath the chip as a thermally conductive material, followed by mechanical vias to improve the vertical thermal conductivity of the printed circuit board (PCB). Heat from the chip is then conducted to the back of the PCB through these vias, and further dissipated via thermal pads. However, plugging these mechanical vias can lead to protrusions or depressions, affecting the flatness of the PCB. A new type of HDI board uses laser-drilled blind vias on the top and bottom surfaces, with mechanical vias in the middle. The characteristics of laser-drilled blind vias effectively solve the flatness problem associated with mechanical vias. However, to ensure efficient heat dissipation, the number of laser-drilled blind vias must exceed the number of mechanical vias. This results in some laser-drilled blind vias being difficult to align with the mechanical vias, causing heat to escape through the nearest laser-drilled blind via, while the heat dissipation effect of other laser-drilled blind vias is significantly reduced, leading to insufficient utilization of the heat dissipation structure. Although theoretically, rapid heat dissipation is possible, the actual cooling speed is affected by the mismatch between the mechanical vias and laser-drilled blind vias. Utility Model Content

[0004] The purpose of this invention is to at least solve one of the aforementioned technical defects.

[0005] Therefore, one objective of this utility model is to propose an HDI board heat dissipation structure and HDI board that improves surface flatness, so as to solve the problems mentioned in the background art and overcome the shortcomings of the prior art.

[0006] To achieve the above objectives, one embodiment of this utility model provides an HDI board heat dissipation structure and an HDI board for improving surface flatness, including a motherboard. The motherboard has a top heat dissipation layer and a bottom heat dissipation layer on its top and bottom sides, respectively. The motherboard has several middle heat dissipation layers. The top of the motherboard has several top laser blind holes, the bottom of the motherboard has several bottom laser blind holes, and the middle of the motherboard has several mechanical through holes. When no mechanical through holes are provided between the corresponding top laser blind holes and bottom laser blind holes, heat-conducting pillars are provided.

[0007] The above technical solution involves installing top-laser blind vias and bottom-laser blind vias on the top and bottom surfaces of the circuit board. Utilizing the characteristics of laser blind vias, the flatness issue caused by mechanical through-holes is resolved. Simultaneously, heat from the circuit board is conducted via either the top-laser blind via – mechanical through-hole – bottom-laser blind via or the top-laser blind via – heat-conducting pillar – bottom-laser blind via. Heat conduction is not affected by the lack of connection between the mechanical through-hole and the top / bottom laser blind vias; heat can also be quickly conducted even in areas without mechanical through-holes, resulting in superior heat dissipation.

[0008] Preferably, in any of the above schemes, the number of top laser blind holes and bottom laser blind holes is the same, and the top laser blind holes and bottom laser blind holes are set in a one-to-one correspondence.

[0009] The above technical solution employs a one-to-one correspondence between top-laser blind vias and bottom-laser blind vias, facilitating rapid heat conduction. Laser blind vias can achieve a minimum aperture of 0.05mm (2 mils), far exceeding the limit of mechanical through-holes (approximately 0.15mm), meeting the high-density requirements of HDI boards and chip packaging, demonstrating outstanding micro-hole processing capabilities. Non-contact processing avoids mechanical stress damage, making it suitable for easily deformable materials such as flexible printed circuit boards (FPCs), ceramic substrates, and ultra-thin boards (<0.1mm). Laser-controlled depth avoids depth errors inherent in mechanical drilling, supporting advanced HDI board designs.

[0010] Preferably, in any of the above schemes, the number of top laser blind holes and bottom laser blind holes is twice the number of mechanical through holes.

[0011] Preferably, in any of the above schemes, the mechanical through-hole is arranged in an upper and lower correspondence with the top laser blind hole and the bottom laser blind hole.

[0012] The above technical solution involves corresponding mechanical through-holes with top and bottom laser blind holes, facilitating heat conduction through the top laser blind hole – mechanical through-hole – bottom laser blind hole. Controlling the ratio of laser blind holes to mechanical through-holes helps ensure effective heat dissipation (for specific calculations, refer to the patent document CN222170073U, "An HDI Board Heat Dissipation Structure for Improving Surface Flatness and an HDI Board").

[0013] Preferably, in any of the above solutions, the top heat dissipation layer, the bottom heat dissipation layer, the middle heat dissipation layer, and the heat-conducting pillars are all made of copper.

[0014] The above technical solution employs a top heat dissipation layer, a bottom heat dissipation layer, and a middle heat dissipation layer to facilitate heat transfer between the laser blind holes and mechanical through holes. Heat-conducting pillars are used to conduct heat between the top and bottom laser blind holes. Copper material has excellent thermal conductivity, making it well-suited to the application requirements of related structures.

[0015] Preferably, in any of the above schemes, the mechanical through holes and the top laser blind holes and bottom laser blind holes are arranged alternately.

[0016] By adopting the above technical solution, mechanical through holes and laser blind holes are staggered, which can reduce the weakening of the circuit board caused by the opening, and ensure the overall strength of the circuit board.

[0017] An HDI board using the above-mentioned HDI board heat dissipation structure to improve surface flatness.

[0018] By adopting the above technical solution: the HDI board with the above heat dissipation structure ensures heat dissipation while avoiding flatness problems caused by mechanical through holes.

[0019] Compared with the prior art, the advantages and beneficial effects of this utility model are as follows: 1. This HDI board heat dissipation structure, which improves surface flatness, incorporates a top heat dissipation layer, a bottom heat dissipation layer, a middle heat dissipation layer, top laser-drilled blind vias, bottom laser-drilled blind vias, mechanical through-holes, and heat-conducting pillars. Top and bottom laser-drilled blind vias are placed on the top and bottom surfaces of the circuit board. The characteristics of laser-drilled blind vias solve the flatness problem caused by mechanical through-holes. Simultaneously, heat from the circuit board is conducted through either the top laser-drilled blind via – mechanical through-hole – bottom laser-drilled blind via or the top laser-drilled blind via – heat-conducting pillar – bottom laser-drilled blind via. Heat conduction is not affected by the lack of connection between the mechanical through-holes and the top / bottom laser-drilled blind vias; heat can also be quickly conducted even in areas without mechanical through-holes, resulting in superior heat dissipation.

[0020] 2. This HDI board heat dissipation structure, which improves surface flatness, features mechanical through-holes corresponding to top and bottom laser-drilled blind vias, facilitating heat conduction through the top laser-drilled blind vias – mechanical through-holes – bottom laser-drilled blind vias. Controlling the ratio of laser-drilled blind vias to mechanical through-holes helps ensure effective heat dissipation. Copper material has excellent thermal conductivity, making it well-suited for the needs of the top, bottom, and middle heat dissipation layers and heat-conducting pillars.

[0021] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0022] The above and / or additional aspects and advantages of this utility model will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the structure of one embodiment of the present utility model; Figure 2 This is a schematic diagram of another embodiment of the present invention.

[0023] In the diagram: 1-Motherboard, 2-Top heat dissipation layer, 3-Bottom heat dissipation layer, 4-Middle heat dissipation layer, 5-Top laser blind hole, 6-Bottom laser blind hole, 7-Mechanical through hole, 8-Heat conduction pillar. Detailed Implementation

[0024] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this utility model, and should not be construed as limiting this utility model.

[0025] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0026] like Figures 1-2 As shown, this utility model includes a motherboard 1. The top and bottom surfaces of the motherboard 1 are respectively provided with a top heat dissipation layer 2 and a bottom heat dissipation layer 3. Several middle heat dissipation layers 4 are provided inside the motherboard 1. Several top laser blind holes 5 are opened on the top of the motherboard 1. Several bottom laser blind holes 6 are opened on the bottom of the motherboard 1. Several mechanical through holes 7 are opened in the middle of the motherboard 1. When no mechanical through holes 7 are opened between the corresponding top laser blind holes 5 and bottom laser blind holes 6, heat conduction pillars 8 are provided.

[0027] Top laser-guided blind vias 5 and 6 are installed on the top and bottom surfaces of the circuit board. Utilizing the characteristics of laser-guided blind vias, the flatness issue caused by mechanical through-holes is resolved. Simultaneously, heat from the circuit board is conducted via either top laser-guided blind via 5 – mechanical through-hole 7 – bottom laser-guided blind via 6 or top laser-guided blind via 5 – heat-conducting pillar 8 – bottom laser-guided blind via 6. Heat conduction is not affected by the lack of connection between mechanical through-hole 7 and top laser-guided blind vias 5 and 6; heat can also be quickly conducted even where mechanical through-hole 7 is not present, resulting in superior heat dissipation.

[0028] Example 1: The number of top laser blind holes 5 and bottom laser blind holes 6 is the same, and the top laser blind holes 5 and bottom laser blind holes 6 are set in a one-to-one correspondence.

[0029] Specifically, the top laser blind via 5 and the bottom laser blind via 6 are configured one-to-one to facilitate rapid heat conduction. Laser blind vias can achieve a minimum aperture of 0.05mm (2 mils), far exceeding the limit of mechanical through-holes (approximately 0.15mm), meeting the high-density requirements of HDI boards and chip packaging, demonstrating outstanding micro-hole processing capabilities. Non-contact processing avoids mechanical stress damage and is suitable for easily deformable materials such as flexible printed circuit boards (FPCs), ceramic substrates, and ultra-thin boards (<0.1mm). Laser-assisted depth control avoids depth errors inherent in mechanical drilling, supporting advanced HDI board designs.

[0030] Example 2: The number of top laser blind holes 5 and bottom laser blind holes 6 is twice the number of mechanical through holes 7. The mechanical through holes 7 are arranged in an upper and lower correspondence with the top laser blind holes 5 and bottom laser blind holes 6.

[0031] Specifically, the mechanical through-hole 7 is correspondingly set with the top laser blind hole 5 and the bottom laser blind hole 6, facilitating heat conduction through the top laser blind hole 5 – mechanical through-hole 7 – bottom laser blind hole 6. By controlling the ratio of laser blind holes to mechanical through-holes, heat dissipation is better ensured.

[0032] Example 3: The top heat dissipation layer 2, bottom heat dissipation layer 3, middle heat dissipation layer 4, and heat-conducting pillar 8 are all made of copper. Mechanical through holes 7 and top laser blind holes 5 and bottom laser blind holes 6 are arranged alternately on top and bottom.

[0033] Specifically, the top heat dissipation layer 2, bottom heat dissipation layer 3, and middle heat dissipation layer 4 facilitate heat transfer between the laser blind vias and mechanical through-holes 7. The heat-conducting pillars 8 are used for heat conduction between the top laser blind vias 5 and bottom laser blind vias 6. Copper has excellent thermal conductivity, making it well-suited to the requirements of the relevant structures. The mechanical through-holes 7 are staggered from the laser blind vias, reducing the weakening of the circuit board caused by the openings and ensuring the overall strength of the circuit board.

[0034] The working principle of this utility model is as follows: S1. Set top laser blind vias 5 and bottom laser blind vias 6 on the top and bottom surfaces of the circuit board to solve the flatness problem caused by mechanical through holes by utilizing the characteristics of laser blind vias. S2. The heat of the circuit board is conducted through the top laser blind hole 5 - mechanical through hole 7 - bottom laser blind hole 6 or the top laser blind hole 5 - heat conduction pillar 8 - bottom laser blind hole 6 to ensure the heat dissipation effect of the circuit board.

[0035] Compared with the prior art, the present invention has the following advantages: 1. This HDI board heat dissipation structure, which improves surface flatness, incorporates a top heat dissipation layer 2, a bottom heat dissipation layer 3, a middle heat dissipation layer 4, a top laser blind via 5, a bottom laser blind via 6, a mechanical through-hole 7, and heat-conducting pillars 8. Top laser blind vias 5 and 6 are placed on the top and bottom surfaces of the circuit board. The characteristics of laser blind vias solve the flatness problem caused by mechanical through-holes. Simultaneously, heat from the circuit board is conducted through either the top laser blind via 5 – mechanical through-hole 7 – bottom laser blind via 6 or the top laser blind via 5 – heat-conducting pillar 8 – bottom laser blind via 6. Heat conduction is not affected by the lack of connection between the mechanical through-hole 7 and the top and bottom laser blind vias 5 and 6; heat can also be quickly conducted even where mechanical through-hole 7 is not present, resulting in superior heat dissipation.

[0036] 2. This HDI board heat dissipation structure, which improves surface flatness, features mechanical through-holes 7 corresponding to top laser blind vias 5 and bottom laser blind vias 6, facilitating heat conduction through the top laser blind via 5 – mechanical through-hole 7 – bottom laser blind via 6. Controlling the ratio of laser blind vias to mechanical through-holes helps ensure effective heat dissipation. Copper material has excellent thermal conductivity, perfectly suited to the needs of the top heat dissipation layer 2, bottom heat dissipation layer 3, middle heat dissipation layer 4, and heat-conducting pillars 8.

Claims

1. An HDI board heat dissipation structure for improving surface flatness, characterized in that, The motherboard (1) is provided with a top heat dissipation layer (2) and a bottom heat dissipation layer (3) on its top and bottom sides respectively. Several heat dissipation layers (4) are provided inside the motherboard (1). Several top laser blind holes (5) are opened on the top of the motherboard (1). Several bottom laser blind holes (6) are opened on the bottom of the motherboard (1). Several mechanical through holes (7) are opened in the middle of the motherboard (1). When no mechanical through holes (7) are opened between the corresponding top laser blind holes (5) and bottom laser blind holes (6), heat conduction pillars (8) are provided.

2. The HDI board heat dissipation structure for improving surface flatness according to claim 1, wherein: The number of top laser blind holes (5) and bottom laser blind holes (6) is the same, and the top laser blind holes (5) and bottom laser blind holes (6) are set in a one-to-one correspondence.

3. The HDI board heat dissipation structure for improving surface flatness according to claim 2, characterized in that: The number of top laser blind holes (5) and bottom laser blind holes (6) is twice the number of mechanical through holes (7).

4. The HDI board heat dissipation structure for improving surface flatness according to claim 3, characterized in that: The mechanical through hole (7) is set up in an upper and lower correspondence with the top laser blind hole (5) and the bottom laser blind hole (6).

5. The HDI board heat dissipation structure for improving surface flatness according to claim 4, wherein: The top heat dissipation layer (2), bottom heat dissipation layer (3), middle heat dissipation layer (4), and heat conduction pillar (8) are all made of copper.

6. The HDI board heat dissipation structure for improving surface flatness as described in claim 3, characterized in that: The mechanical through-hole (7) is arranged alternately with the top laser blind hole (5) and the bottom laser blind hole (6).

7. An HDI board characterized by, The application includes the HDI board heat dissipation structure for improving surface flatness as described in any one of claims 1 to 6.

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