Circuit board structure and manufacturing method thereof

Abstract

A circuit board structure includes a substrate, a circuit layer, a solder resisting layer and a metal connection post. The substrate includes a through hole penetrating through the substrate. The circuit layer includes a metal pillar formed in the through hole. The solder resisting layer is on a surface of the substrate, and the solder resisting layer contains a solder resisting opening exposing the metal pillars. The metal connecting post is connected to the metal post and in the solder resisting opening, and the metal connecting post protrudes from the solder resisting layer. The metal connecting post protruding from the solder resisting layer can be used as positioning targets and solder ball alignment positions. There is no need to install additional steel plates for solder balls, and the overall timeliness and cost can be effectively improved.

Description

Technical Field

[0001] This invention relates to the field of electronics, and in particular to a circuit board structure and its manufacturing method. Prior Technology

[0002] As chip size shrinks and electronic component performance improves, chip density per unit area on circuit boards also increases, resulting in a greater number and density of solder pads for connections. Modern circuit boards utilize embedded circuitry, through vias and metal fillers, to supply power to both sides of the board. Components can be placed on the top and bottom surfaces of the board, or even embedded within it, further increasing chip density.

[0003] However, embedded circuitry is located inside the solder mask layer and typically requires a ball-mounting stencil to distribute flux and solder balls. However, the inherent material properties of the circuit board itself still present some expansion and contraction issues. With increasing component density and finer linewidths, these expansion and contraction issues directly affect the molding and positioning of the stencil, potentially leading to multiple reflows, increasing time and costs. Summary of the Invention

[0004] To address the aforementioned problems, a circuit board structure is provided herein. The circuit board structure includes a substrate, a circuit layer, a solder mask, and metal interconnects. The substrate includes through-holes penetrating the substrate. The circuit layer includes metal interconnects formed within the through-holes. The solder mask is located on the surface of the substrate and includes openings that expose the metal interconnects. The metal interconnects are connected to the metal interconnects and located within the openings of the solder mask, protruding beyond the solder mask.

[0005] In some embodiments, the substrate includes a core plate and at least one additional insulating layer, with through holes penetrating the core plate and at least one additional insulating layer.

[0006] More specifically, in some embodiments, the circuit layer comprises multiple layers of circuitry and includes a plurality of circuit patterns located on the core board and the added insulating layer.

[0007] In some embodiments, the circuit board structure further includes solder balls located on the solder resist layer and covering metal connecting posts.

[0008] In some embodiments, a metal membrane is further included between the hole wall of the solder resist opening and the metal connecting post.

[0009] Here, a method for manufacturing a circuit board structure is also provided. The method includes providing a circuit board substrate, the circuit board substrate including a substrate and a circuit layer, the substrate including vias penetrating the substrate, the circuit layer including metal pillars formed in the vias; forming a solder resist layer on the surface of the circuit board, the solder resist layer including solder resist openings exposing the vias and metal pillars; forming a dry film on the solder resist layer; exposing and developing the dry film to form dry film openings, the dry film openings exposing the vias and metal pillars; electroplating to form metal connectors on the metal pillars, the metal connectors being connected to the metal pillars and located in the solder resist openings and the dry film openings; and removing the dry film, the metal connectors protruding from the solder resist layer.

[0010] In some embodiments, a metal film is formed on the solder resist layer before the dry film is formed, and the metal film on the surface of the solder resist layer is removed after the dry film is removed.

[0011] In some embodiments, the method further includes forming solder balls located on the solder resist layer and covering the metal connecting posts.

[0012] In some embodiments, the substrate includes a core plate and at least one additional insulating layer, with through holes penetrating the core plate and at least one additional insulating layer.

[0013] More specifically, in some embodiments, the circuit layer comprises multiple layers of circuitry and includes a plurality of circuit patterns located on the core board and the added insulating layer.

[0014] As described in the previous embodiments, by setting metal connecting posts protruding from the solder resist layer and connecting the embedded circuit layer, the metal connecting posts protruding from the solder resist layer can be used as positioning targets and solder ball alignment positions, eliminating the need for additional steel plates for solder ball placement, and effectively improving overall efficiency and cost. Simple Explanation of the Diagram

[0015] Figure 1 is a cross-sectional view of the circuit board structure. Figure 2 is a flowchart of the manufacturing method of the circuit board structure. Figures 3 to 10 are step-by-step cross-sectional schematic diagrams of the flowchart of the manufacturing method of the circuit board structure. Implementation

[0016] Figure 1 is a cross-sectional view of the circuit board structure. As shown in Figure 1, the circuit board structure 1 includes a substrate 10, a circuit layer 20, a solder resist layer 30, and metal connector pillars 40. The substrate 10 includes through-holes 15 that penetrate the substrate 10. The circuit layer 20 includes metal pillars 25 formed in the through-holes 15. The solder resist layer 30 is located on the surface of the substrate 10 and includes solder resist openings 35 that expose the metal pillars 25. The metal connector pillars 40 are connected to the metal pillars 25 and are located at the solder resist openings 35, protruding from the solder resist layer 30.

[0017] Here, the circuit layer 20 can be disposed on the upper and lower surfaces of the substrate 10. The circuit layer 20 on the upper and lower surfaces of the substrate 10 is connected by through-holes 15 and metal pillars 25. In other words, this is a circuit substrate with embedded circuitry. Furthermore, in some embodiments, the substrate 10 includes a core board 11 and at least one additional insulating layer 13, with the through-holes 15 penetrating the core board 11 and the at least one additional insulating layer 13. Furthermore, in some embodiments, the circuit layer 20 includes multiple layers of circuitry and includes a plurality of circuit patterns 23 located on the core board 11 and the additional insulating layer 13.

[0018] More specifically, referring again to Figure 1, the circuit board structure 1 further includes solder balls 50, which are located on the solder resist layer 30 and cover the metal connecting posts 40. The metal connecting posts 40 are connected to the metal posts 25 and protrude from the solder resist layer 30. Through conductivity detection, they can serve as positioning targets when placing the solder balls 50, eliminating the need for additional solder ball placement plates and eliminating the need to consider the expansion and contraction of the substrate 10. This significantly improves manufacturing control, cost, and time.

[0019] More specifically, a metal film 45 is also included between the hole wall of the solder resist opening 35 and the metal connecting post 40. The metal film 45 can be a chemically formed film, a deposited film, or a directly imprinted metal foil, as a seed layer for forming the metal connecting post 40.

[0020] Figure 2 is a flowchart of the manufacturing method of the circuit board structure. Figures 3 to 10 are step-by-step cross-sectional views of the flowchart of the manufacturing method of the circuit board structure. As shown in Figures 2 to 10, the manufacturing method S1 of the circuit board structure first includes step S10: providing a circuit board substrate 100. As shown in Figure 3, the circuit board substrate 100 includes a substrate 10 and a circuit layer 20. The substrate 10 includes through-holes 15 that penetrate the substrate 10. The circuit layer 20 includes metal pillars 25 that are formed in the through-holes 15.

[0021] Next, as shown in Figure 4, step S20 involves forming a solder resist layer 30. The solder resist layer 30 is on the surface of the circuit board 100 and includes solder resist openings 35 that expose metal pillars 25. As shown in Figure 6, step S30 involves setting a dry film 500. The dry film 500 is set on the solder resist layer 30, and the dry film 500 is exposed and developed, forming dry film openings 510 on the dry film 500. The dry film openings 510 connect to the solder resist layer openings 35 and expose the metal pillars 25.

[0022] In some embodiments, referring to FIG5, step S25 is further included before step S40: forming a metal film 45. The metal film 45 is formed on the solder resist layer 30, and the metal film 45 covers the surface of the solder resist layer 30 and the hole walls of the solder resist layer opening 35, serving as a subsequent seed layer. Here, the metal film 45 can be formed by imprinting, electroless plating (chemical plating), or vapor deposition, which are only examples and not intended to limit the scope.

[0023] As shown in Figure 7, step S40 involves electroplating to form a metal connecting post 40. The metal connecting post 40 is formed on the metal post 25 through electroplating, connecting the metal connecting post 40 to the metal post 25, and the metal connecting post 40 is located in the solder resist opening 35 and the dry film opening 510. As shown in Figure 8, step S50 involves removing the dry film 500, thereby causing the metal connecting post 40 to protrude from the solder resist layer 30.

[0024] Referring to Figure 9, in some embodiments, step S55 is further included after step S50: removing the surface metal film 45. The metal film 45 on the surface of the solder resist layer 30 can be removed by etching, and the metal film 45 is only retained between the hole wall of the solder resist layer opening 35 and the metal connecting post 40.

[0025] Finally, as shown in Figure 10, step S60 involves forming solder balls 50. Solder balls 50 are located on the solder resist layer 30 and are covered by metal connecting posts 40. Here, the metal-covered connecting posts 40 protruding from the solder resist layer 30 can serve as positioning targets and alignment points for the solder balls 50, eliminating the need for additional steel plates for implanting the solder balls 50 to locate their implantation positions.

[0026] In summary, by setting the metal connecting post 40 to protrude from the solder resist layer 30 and connect it to the embedded circuit layer 20, the metal connecting post 40 protruding from the solder resist layer 30 can be used as a positioning target and the position for aligning the solder ball 50. There is no need to set an additional steel plate for planting the solder ball 50, which can effectively improve the overall efficiency and cost.

[0027] Although the technical content of the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any modifications and refinements made by those skilled in the art without departing from the spirit of the present invention should be included within the scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

[0028] 1: Circuit board structure 10:Substrate 11: Core Board 13: Add an insulation layer 15: Through-hole 20: Line Layer 23: Circuit Diagram 25: Metal Column 30: Solder resist layer 35: Opening of the solder resist layer 40: Metal connecting post 45:Metal film 50: Tin Ball 100: Circuit board 500: Dry film 510: Dry film opening S1: Circuit board structure fabrication method S10: Provides circuit board S20: Forming a solder resist layer S25: Forming a metal film S30: Set dry film S40: Electroplating forms metal connecting pillars S50: Remove dry film S55: Remove the metal film from the surface. S60: Forming solder balls

Claims

1. A circuit board structure comprising: a substrate including a through-hole extending through the substrate; a circuit layer including a metal pillar formed in the through-hole; a solder resist layer located on a surface of the substrate, the solder resist layer including a solder resist opening exposing the metal pillar; and a metal connection post connected to the metal pillar and located in the solder resist opening, the metal connection post protruding from the solder resist layer.

2. The circuit board structure as described in claim 1, wherein the substrate includes a core board and at least one additional insulating layer, and the through-hole penetrates the core board and the at least one additional insulating layer.

3. The circuit board structure as described in claim 2, wherein the circuit layer comprises multiple layers of circuitry and includes a plurality of circuit patterns located on the core board and the additional insulating layer.

4. The circuit board structure as described in claim 1 further includes a solder ball located on the solder resist layer and covering the metal connector post.

5. The circuit board structure as described in claim 1, wherein a metal film is further included between the hole wall of the solder resist opening and the metal connecting post.

6. A method for manufacturing a circuit board structure, comprising: providing a circuit substrate, the circuit substrate including a substrate and a circuit layer, the substrate including a through-hole penetrating the substrate, the circuit layer including a metal pillar formed in the through-hole; forming a solder resist layer on a surface of the circuit substrate, the solder resist layer including a solder resist opening exposing the metal pillar; disposing a dry film on the solder resist layer; exposing and developing the dry film to form a dry film opening exposing the metal pillar; electroplating to form a metal connector on the metal pillar, the metal connector being connected to the metal pillar and located in the solder resist opening and the dry film opening; and removing the dry film, the metal connector protruding from the solder resist layer.

7. A method for manufacturing a circuit board structure as described in claim 6, wherein a metal film is formed on the solder resist layer before the dry film is formed, and the metal film on the surface of the solder resist layer is removed after the dry film is removed.

8. The method of manufacturing a circuit board structure as described in claim 6 further includes forming a solder ball located on the solder resist layer and covering the metal connecting post.

9. A method for manufacturing a circuit board structure as described in claim 6, wherein the substrate includes a core board and at least one reinforcement insulating layer, and the through-hole penetrates the core board and the at least one reinforcement insulating layer.

10. A method for manufacturing a circuit board structure as described in claim 9, wherein the circuit layer is a multilayer circuit and includes a plurality of circuit patterns located on the core board and the added insulating layer.

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