Multilayer super-thick printed circuit board with blind hole structure
By setting diversion grooves and convex points on the inner wall of the blind hole, combined with inverted conical structure and staggered arrangement, the problems of poor flow and accumulation of electroplating are solved, and the uniformity of electroplating and the reliability of electrical connection are improved.
Patent Information
- Application Number
- CN202423009962.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-06
- Publication Date
- 2025-09-02
- Estimated Expiration
- 2034-12-06
AI Technical Summary
During the electroplating process of existing multi-layer super-thick printed circuit boards, the electroplating solution flows poorly inside the blind hole and is prone to accumulate at the bottom, resulting in uneven electroplating affecting conductivity and reliability.
The convex points are distributed in the inner wall of the blind hole. The convex points guide the flow direction of the plating solution. The convex points promote the uniform distribution of metal ions and additives. Combined with the inverted conical blind hole structure and staggered arrangement method, the uniformity and flowability of the plating solution are improved.
Through the design of diversion grooves and bumps, the electroplating solution is ensured to be evenly distributed, the uniformity and reliability of electroplating are improved, the accumulation of electroplating solution at the bottom of the blind hole is reduced, and the stability and signal integrity of the electrical connection are enhanced.
Smart Images
Figure CN223297770U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of circuit boards, in particular to a multi-layer ultra-thick printed circuit board with a blind hole structure. Background Art
[0002] Multilayer circuit boards are important electronic components, possessing multiple signal layers, including top, bottom, and middle layers. The top signal layer is primarily used for placing components, but can also house wires or copper. The bottom signal layer is primarily used for wiring and soldering, but can also house components. The middle signal layer is used for signal lines. Blind vias are a special hole structure within printed circuit boards (PCBs). They connect different layers within a PCB but do not penetrate the entire thickness of the board. Blind vias enable vertical connections between multilayer PCBs, reducing circuit length and signal transmission delay, thereby improving circuit performance.
[0003] However, in existing multi-layer, ultra-thick printed circuit boards with blind via structures, a uniform, continuous, and highly conductive metal plating layer needs to be deposited on the inner wall of the blind via during the production process to achieve electrical connection between different circuit layers. However, during the electroplating process, due to factors such as gravity and surface tension, the plating solution may not flow smoothly in certain areas and easily accumulate at the bottom of the blind via. This uneven electroplating can affect the conductivity and reliability of the blind via. Utility Model Content
[0004] In response to the deficiencies of the prior art, the utility model provides a multi-layer ultra-thick printed circuit board with a blind hole structure, which can solve the problem that, during the electroplating process, the plating liquid does not flow smoothly in certain areas inside the blind hole and easily accumulates at the bottom of the blind hole, and the uneven electroplating affects the conductivity and reliability of the blind hole. By setting a guide groove on the inner wall of the blind hole, the flow direction of the plating liquid can be guided to make the electroplating more uniform, and at the same time, the stirring of the plating liquid can be enhanced to promote the uniform distribution of metal ions and additives in the plating solution.
[0005] To achieve the above objectives, the present invention provides the following technical solution: a multi-layer, ultra-thick printed circuit board with a blind via structure, comprising an inner power layer, wherein a first wiring layer and a second wiring layer are respectively provided on the upper and lower sides of the inner power layer, a top signal layer is provided on the other side of the first wiring layer, and a bottom signal layer is provided on the other side of the second wiring layer;
[0006] A blind hole is opened inside the top signal layer, the upper end of the blind hole is connected to a copper ring, the copper ring is located on the upper surface of the top signal layer, a guide groove is opened inside the blind hole, and bumps are distributed inside the guide groove.
[0007] Through the above technical solution, a guide groove is set on the inner wall of the blind hole to guide the flow direction of the electroplating solution and avoid local poor flow. The depth and width of the guide groove should be moderate to ensure that the electroplating solution can flow smoothly without affecting the electrical performance of the blind hole.
[0008] Furthermore, the height of the blind via is greater than the thickness of the first wiring layer.
[0009] With the above technical solution, since the depth of the blind hole is greater than the thickness of the first wiring layer, the purpose of connecting different layers inside the multi-layer circuit board through the blind hole and realizing vertical connection between the multi-layer circuit boards is met.
[0010] Furthermore, the inner diameter of the copper ring is equal to the outer diameter of the blind hole, and the center of the copper ring and the center of the blind hole are located at the same point.
[0011] Through the above technical solution, the copper ring plays the role of connecting the blind via with other circuits on the circuit board. The copper ring provides a larger contact area, ensuring a good electrical connection between the blind via and other circuit components. The copper ring can also disperse the stress at the blind via, reducing the direct impact on the blind via, thereby improving the reliability of the blind via.
[0012] Furthermore, the cross-section of the blind hole presents an inverted cone-shaped structure, and the diameter of the upper end of the blind hole is larger than the diameter of the lower end of the blind hole.
[0013] Through the above technical solution, the larger inverted tapered blind hole at the opening is conducive to smoother flow of the electroplating solution. Compared with traditional straight holes or positive tapered blind holes, the larger opening can provide a larger entry channel, reducing the resistance of the electroplating solution flowing into the blind hole. As the blind hole gradually narrows, the flow rate of the electroplating solution will increase accordingly. This increase in flow rate helps to overcome the influence of gravity and surface tension. The higher flow rate forms a stronger scouring effect on the bottom of the blind hole, which can prevent the electroplating solution from accumulating at the bottom. In addition, the fast-flowing electroplating solution can carry away the metal ions and additives deposited at the bottom, keeping the electroplating solution in the bottom area in a dynamically updated state, thereby improving the uniformity of electroplating.
[0014] Furthermore, the guide grooves are distributed at equal angles with respect to the center of the blind hole, and the inclination slope of the guide grooves is equal to the side slope of the blind hole.
[0015] Through the above technical solution, the guide groove can guide the electroplating liquid to flow more evenly in the blind hole. Due to factors such as gravity and surface tension, the electroplating liquid may easily accumulate at the bottom of the blind hole or flow poorly in certain areas. By setting up the guide groove, this unbalanced flow state can be broken, allowing the electroplating liquid to reach various parts of the blind hole, thereby improving the uniformity of electroplating.
[0016] Furthermore, the blind vias are staggeredly distributed inside the top signal layer.
[0017] Through the above technical solution, the traditional straight-line arrangement of blind vias is changed to a staggered arrangement, which can increase the distance between the blind vias and adjacent signal lines, thereby reducing the mutual influence of electromagnetic fields and improving signal integrity.
[0018] Furthermore, the edge of the guide groove is in an arc-shaped structure.
[0019] Through the above technical solution, the edge of the guide groove is designed into an arc structure to reduce right angles and sharp edges. This can reduce eddy currents and dead corners in the flow of the electroplating solution, allowing the electroplating solution to flow more smoothly in the guide groove and improve the uniformity of electroplating.
[0020] Furthermore, the thickness of the protrusions is smaller than the thickness of the guide groove, and the protrusions are evenly distributed inside the guide groove.
[0021] Through the above technical solution, the protrusions inside the guide groove can produce a certain stirring effect, which can promote the uniform distribution of metal ions and additives in the electroplating solution, improve the rate and uniformity of the electroplating reaction, and at the same time, the stirring effect can also reduce the retention of bubbles in the blind hole and reduce the porosity, thereby improving the density and corrosion resistance of the electroplating layer.
[0022] Compared with the prior art, the present invention provides a multi-layer ultra-thick printed circuit board with a blind hole structure, which has the following beneficial effects:
[0023] In the utility model, the larger inverted tapered blind hole at the opening is conducive to smoother inflow of the electroplating solution, reducing the resistance of the electroplating solution to the flow of the blind hole. As the blind hole gradually narrows, the flow rate of the electroplating solution will increase accordingly. This increase in flow rate helps to overcome the influence of gravity and surface tension, and forms a stronger scouring effect on the bottom of the blind hole, which can prevent the electroplating solution from accumulating at the bottom. In addition, the guide groove opened on the inner wall of the blind hole can guide the flow direction of the electroplating solution, break the unbalanced flow state of the electroplating solution, and enable the electroplating solution to reach all parts of the blind hole, thereby improving the uniformity of electroplating. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 It is a schematic diagram of the overall structure of the utility model;
[0025] Figure 2 For the utility model Figure 1 A in the middle is an enlarged structural diagram;
[0026] Figure 3 It is a schematic diagram of the overall cross-sectional structure of the present utility model.
[0027] Among them: 1. Top signal layer; 2. First wiring layer; 3. Inner power layer; 4. Second wiring layer; 5. Bottom signal layer; 6. Blind via; 7. Copper ring; 8. Guide groove; 9. Bump. DETAILED DESCRIPTION
[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.
[0029] See also Figure 1-Figure 3 The utility model provides a technical solution: a multi-layer ultra-thick printed circuit board with a blind hole structure, comprising an inner power supply layer 3, a first wiring layer 2 and a second wiring layer 4 are respectively provided on the upper and lower sides of the inner power supply layer 3, a top signal layer 1 is provided on the other side of the first wiring layer 2, and a bottom signal layer 5 is provided on the other side of the second wiring layer 4; a blind hole 6 is opened inside the top signal layer 1, the height of the blind hole 6 is greater than the thickness of the first wiring layer 2, the upper end of the blind hole 6 is connected to a copper ring 7, the copper ring 7 is located on the upper surface of the top signal layer 1, the inner diameter of the copper ring 7 is equal to the outer diameter of the blind hole 6, and the center of the copper ring 7 and the center of the blind hole 6 are located at the same point.
[0030] It is worth mentioning that the copper ring 7 serves to connect the blind via 6 with other circuits on the circuit board. The copper ring 7 provides a larger contact area, ensuring a good electrical connection between the blind via 6 and other circuit components. In addition, the copper ring 7 can disperse the stress at the blind via 6, reducing the direct impact on the blind via 6, thereby improving the reliability of the blind via 6.
[0031] See also Figure 1-Figure 3 The cross-section of the blind hole 6 is an inverted cone-shaped structure, and the upper end diameter of the blind hole 6 is larger than the lower end diameter of the blind hole 6.
[0032] It should be noted that: since the blind hole 6 is designed to have a gradually decreasing aperture from top to bottom, the larger inverted tapered blind hole 6 at the opening is conducive to a smoother flow of the electroplating solution. Compared with the traditional straight hole or positive tapered blind hole 6, the larger opening can provide a larger entry channel, reducing the resistance of the electroplating solution to the flow of the blind hole 6. As the blind hole 6 gradually narrows, the flow rate of the electroplating solution will increase accordingly. This increase in flow rate helps to overcome the influence of gravity and surface tension. The higher flow rate forms a stronger scouring effect on the bottom of the blind hole 6, which can prevent the electroplating solution from accumulating at the bottom. In addition, the fast-flowing electroplating solution can carry away the metal ions and additives deposited at the bottom, keeping the electroplating solution in the bottom area in a dynamically updated state, thereby improving the uniformity of electroplating.
[0033] See also Figure 1-Figure 3A guide groove 8 is opened inside the blind hole 6. The guide grooves 8 are distributed at equal angles with respect to the center of the blind hole 6. The inclination slope of the guide grooves 8 is equal to the side slope of the blind hole 6.
[0034] The function of the guide groove 8 is to provide the guide groove 8 on the inner wall of the blind hole 6 to guide the flow direction of the electroplating solution. Due to factors such as gravity and surface tension, the electroplating solution may easily accumulate at the bottom of the blind hole 6 or flow poorly in certain areas. By providing the guide groove 8, this unbalanced flow state can be broken, so that the electroplating solution can reach all parts of the blind hole 6, avoiding the accumulation of the electroplating solution at the bottom of the blind hole 6, thereby improving the uniformity of electroplating.
[0035] There are convex points 9 distributed inside the guide groove 8 . The thickness of the convex points 9 is smaller than the thickness of the guide groove 8 . The convex points 9 are evenly distributed inside the guide groove 8 .
[0036] The function of the protrusions 9 is that the protrusions 9 inside the guide groove 8 can produce a certain stirring effect, which can promote the uniform distribution of metal ions and additives in the electroplating solution, improve the rate and uniformity of the electroplating reaction, and at the same time, the stirring effect can also reduce the retention of bubbles in the blind hole 6, reduce the porosity, and thus improve the density and corrosion resistance of the electroplating layer.
[0037] See also Figure 1-Figure 3 , the blind vias 6 are staggeredly distributed inside the top signal layer 1 .
[0038] It is worth mentioning that changing the traditional straight-line arrangement of the blind vias 6 to a staggered arrangement can increase the distance between the blind vias 6 and adjacent signal lines, thereby reducing the mutual influence of electromagnetic fields and improving signal integrity.
[0039] See also Figure 1-Figure 3 , the edge of the guide groove 8 is an arc-shaped structure.
[0040] It should be noted that: since the edge of the guide groove 8 is designed to be an arc structure, right angles and sharp edges are reduced, this can reduce eddy currents and dead corners in the flow of the electroplating solution, allowing the electroplating solution to flow more smoothly in the guide groove 8, thereby improving the uniformity of electroplating.
[0041] Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A multi-layer ultra-thick printed circuit board with a blind hole structure, comprising an inner power layer (3), characterized in that: A first wiring layer (2) and a second wiring layer (4) are respectively provided on the upper and lower sides of the inner power supply layer (3); a top signal layer (1) is provided on the other side of the first wiring layer (2); and a bottom signal layer (5) is provided on the other side of the second wiring layer (4); A blind hole (6) is provided inside the top signal layer (1), a copper ring (7) is connected to the upper end of the blind hole (6), and the copper ring (7) is located on the upper surface of the top signal layer (1). A guide groove (8) is provided inside the blind hole (6), and bumps (9) are distributed inside the guide groove (8).
2. The multi-layer ultra-thick printed circuit board with a blind hole structure according to claim 1, characterized in that: The height of the blind hole (6) is greater than the thickness of the first wiring layer (2).
3. The multi-layer ultra-thick printed circuit board with a blind hole structure according to claim 1, characterized in that: The inner diameter of the copper ring (7) is equal to the outer diameter of the blind hole (6), and the center of the copper ring (7) and the center of the blind hole (6) are located at the same point.
4. The multi-layer ultra-thick printed circuit board with a blind hole structure according to claim 1, characterized in that: The blind hole (6) has an inverted cone-shaped structure in cross-section, and the diameter of the upper end of the blind hole (6) is larger than the diameter of the lower end of the blind hole (6).
5. The multi-layer ultra-thick printed circuit board with a blind hole structure according to claim 1, characterized in that: The guide grooves (8) are distributed at equal angles with respect to the center of the blind hole (6), and the inclination slope of the guide grooves (8) is equal to the side slope of the blind hole (6).
6. The multi-layer ultra-thick printed circuit board with a blind hole structure according to claim 1, characterized in that: The blind holes (6) are staggeredly distributed inside the top signal layer (1).
7. The multi-layer ultra-thick printed circuit board with a blind hole structure according to claim 1, characterized in that: The edge of the guide groove (8) is in an arc-shaped structure.
8. The multi-layer ultra-thick printed circuit board with a blind hole structure according to claim 1, characterized in that: The thickness of the convex points (9) is smaller than the thickness of the guide groove (8), and the convex points (9) are evenly distributed inside the guide groove (8).