A method for manufacturing a blind via hole of a metalized hole of a circuit board and a circuit board

Abstract

This invention discloses a method for fabricating metallized holes in a blind slot board and a circuit board. The fabrication method includes: preparing a laminated structure comprising multiple layers and a prepreg placed between the multiple layers, and pressing the laminated structure together; drilling holes in the laminated structure to obtain a first blind slot and an outer layer through-hole; metallizing the surfaces of the first blind slot, the outer layer through-hole, and the laminated structure to form a copper layer; performing controlled-depth milling on the laminated structure to obtain a second blind slot, with the bottom copper layer of the first blind slot exposed at the bottom of the second blind slot; forming an outer layer circuit pattern on the surface of the laminated structure, and plating an etch-resistant protective layer on the copper layer surface of the laminated structure; removing the etch-resistant protective layer at the bottom of the second blind slot to expose the underlying copper layer; performing an etching process to remove the exposed copper layer at the bottom of the second blind slot and remove the etch-resistant protective layer in the remaining areas, so that the first blind slot and the second blind slot are connected; and fabricating a circuit board using this method.

Description

Technical Field

[0001] This invention relates to the technical field of printed circuit boards, and particularly to a method for manufacturing metallized holes in a blind slot board and a circuit board thereof. Background Technology

[0002] Blind slot design is a common type of printed circuit board (PCB) product, primarily used for mounting components, fixing products, or shielding signals to improve product integration. In some applications, metallized vias need to be fabricated at the bottom of the blind slot to enable electrical connections from the bottom to another layer. Currently, the traditional method for fabricating metallized vias in this type of blind slot board mainly employs a multi-step resist bonding process. The specific steps of this method include the following: Step 1: Complete the drilling, hole metallization, and circuit fabrication of the fifth and sixth layers, and then apply gold plating to protect the holes; Step 2: Stack the first layer, second layer, first prepreg, third layer, fourth layer, second prepreg, fifth layer, and sixth layer in sequence, mill off excess material in the blind groove area of ​​the stacked structure, place the adhesive resist sheet, and then press the stacked structure together. Step 3: During the processing of the outer metallized hole, the sidewall of the blind slot is metallized, and a new layer of copper and tin is plated on the inner circuit substrate. Step 4: Before etching the circuit, remove the tin from the metallization layer in the blind trench separately to facilitate the subsequent removal of the copper layer; Step 5: Using an etching process, the copper layer and the outline circuitry within the blind trench are etched away together to form the final blind trench structure. At this point, the stacked structure looks like... Figure 1 As shown; As can be seen from the above, in the traditional method, after the blind slot is formed, the metallized holes inside need to be pre-plated with gold to protect them from damage or contamination in subsequent processing. This pre-plating protection increases the complexity of the process and the difficulty of operation, and the pre-plating operation inevitably leads to higher material costs. Secondly, the traditional method has a complicated process route, involving multiple pressing, separate pre-plating and tin stripping operations, which not only increases the overall processing cycle, but also drives up the comprehensive processing cost due to the complexity of the process. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art. The primary objective is to provide a method for manufacturing metallized holes in a blind slot plate.

[0004] The second objective of this invention is to provide a circuit board manufactured using a method for fabricating metallized holes in a blind slot plate.

[0005] The technical solution adopted in this invention is as follows: the method for manufacturing the metallized holes in the blind slot plate includes the following steps: Step S1: Prepare a laminated structure including multiple layers and a prepreg placed between the multiple layers, and press the laminated structure together. Step S2: Drill holes in the laminated structure to obtain the first blind slot and the outer through hole; Step S3: Metallize the surfaces of the first blind trench, the outer through-hole, and the stacked structure to form a copper layer; Step S4: Perform controlled-depth milling on the stacked structure to obtain the second blind trench, and expose the bottom copper layer of the first blind trench at the bottom of the second blind trench; Step S5: Form an outer layer circuit pattern on the surface of the stacked structure, and plate an anti-etching protective layer on the copper layer surface of the stacked structure. Step S6: Remove the etch-resistant protective layer located at the bottom of the second blind trench and expose the copper layer underneath; Step S7: Perform etching to remove the copper layer exposed at the bottom of the second blind trench and remove the anti-etching protective layer in the remaining area, so that the first blind trench and the second blind trench are connected.

[0006] Furthermore, step S1 includes the following steps: Step 101: Prepare a laminated structure including multiple layers and prepreg placed between adjacent layers, and mark the locations in the laminated structure where metallization holes need to be formed; Step 102: Open a window in the area of ​​the prepreg corresponding to the area where the blind groove is to be formed, and place a resist film in the window; Step 103: Press the laminated structure together so that the resist film is embedded in the laminated structure.

[0007] Furthermore, in step 101, the identifier is a pad, and the diameter of the identifier is larger than the diameter of the inner hole of the first blind slot.

[0008] Furthermore, in step S2, 80%-90% of the medium thickness at the inner hole position of the first blind groove is drilled away by controlled depth drilling, and then the first blind groove is processed by laser drilling.

[0009] Furthermore, in step S2, the first blind groove is processed by laser drilling.

[0010] Furthermore, step S4 includes the following steps: Step S401: Perform controlled-depth milling on the laminated structure to the position of the resist film to obtain the second blind groove; Step S402: Remove the resist film to expose the bottom copper layer of the first blind trench to the bottom of the second blind trench.

[0011] Furthermore, in step S6, the anti-etching protective layer located at the bottom of the second blind trench is removed by laser.

[0012] Furthermore, the etch-resistant protective layer is a tin layer.

[0013] In addition, the present invention also provides a circuit board manufactured using the aforementioned method for fabricating metallized holes in a blind slot plate.

[0014] The beneficial effects of this invention are: Compared to the shortcomings of traditional technologies, this invention first uses a blind via process to fabricate and metallize the first blind trench, and then opens the second blind trench. Subsequently, when fabricating the outer layer circuitry, only one removal of the anti-etching protective layer and etching treatment are needed to complete the connection between the first and second blind trenches and the etching of the outer circuitry, significantly reducing the number of process steps and the waiting time in intermediate stages, thereby shortening the overall product processing cycle. Secondly, by metallizing the first blind trench first and then opening the second blind trench, this invention eliminates the need for complex pre-plating gold protection, improving the reliability and yield of the process, and directly eliminating the cost of using precious metals. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the planar structure of a circuit board manufactured using traditional techniques; Figure 2 This is a flowchart illustrating the present invention; Figure 3 This is a schematic diagram of the planar structure of the stacked structure of the present invention. Figure 1 ; Figure 4 This is a schematic diagram of the planar structure of the stacked structure of the present invention. Figure 2 ; Figure 5 This is a schematic diagram of the planar structure of the stacked structure of the present invention. Figure 3 ; Figure 6 This is a schematic diagram of the planar structure of the stacked structure of the present invention. Figure 4 ; Figure 7 This is a schematic diagram of the planar structure of the stacked structure of the present invention. Figure 5 ; Figure 8 This is a schematic diagram of the planar structure of the stacked structure of the present invention. Figure 6 ; Figure 9 This is a schematic diagram of the planar structure of the stacked structure of the present invention. Figure 7 .

[0017] The attached figures are labeled as follows: 1. Layer; 2. Prepreg; 3. First blind groove; 4. Outer layer through-hole; 5. Copper layer; 6. Second blind groove; 7. Anti-etching protective layer; 8. Resist film.

[0018] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be noted that all directional indications in the embodiments of the present invention, such as up, down, left, right, front, back, clockwise, counterclockwise, etc., are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0021] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0022] like Figure 2 As shown, in this embodiment, the method for fabricating the metallized holes in the blind slot plate includes the following steps: like Figure 3 As shown, step S1 involves preparing a laminated structure comprising multiple layers 1 and prepregs 2 placed between the multiple layers 1, and then pressing the laminated structure together; wherein the number of layers 1 and prepregs 2 can be as follows: Figure 3 The six-layer board 1 and two-layer prepreg 2 shown are stacked in the following order: first layer board, second layer board, first prepreg 2, third layer board, fourth layer board, second prepreg 2, fifth layer board and sixth layer board. like Figure 4As shown, in step S2, a first blind groove 3 and an outer through hole 4 are obtained by drilling holes in the stacked structure; specifically, the outer through hole 4 is directly drilled mechanically. like Figure 5 As shown, in step S3, the surfaces of the first blind slot 3, the outer through hole 4, and the stacked structure are metallized to form a copper layer 5; like Figure 6 As shown, in step S4, the stacked structure is subjected to controlled-depth milling to obtain the second blind groove 6, and the bottom copper layer 5 of the first blind groove 3 is exposed at the bottom of the second blind groove 6. like Figure 7 As shown, in step S5, an outer layer circuit pattern is formed on the surface of the stacked structure, and an anti-etching protective layer 7 is plated on the surface of the copper layer 5 of the stacked structure. like Figure 8 As shown, in step S6, the anti-etching protective layer 7 located at the bottom of the second blind trench 6 is removed, exposing the copper layer 5 underneath; like Figure 9 As shown, in step S7, an etching process is performed to remove the copper layer 5 exposed at the bottom of the second blind trench 6 and remove the anti-etching protective layer 7 in the remaining area, so that the first blind trench 3 and the second blind trench 6 are connected.

[0023] It should be noted that the traditional processing method involves first fabricating a complete blind trench, then metallizing it, and pre-plating gold onto its copper layer 5 to prevent the sidewalls of the blind trench from being damaged during subsequent processing of the outer layer circuitry. In this invention, the first blind trench 3 is fabricated and metallized using a blind via process, followed by the creation of the second blind trench 6. Since the sidewalls of the second blind trench 6 are not metallized, pre-plating gold is not required during the outer layer circuitry process. At this point, a conventional, low-cost etch-resistant protective layer 7 (which can be a tin layer) is sufficient for pattern protection. Subsequently, the etch-resistant protective layer 7 is removed locally, and etching is performed immediately. Therefore, this invention eliminates the need for expensive gold as a protective layer, unlike the traditional process which requires a lengthy and complex multi-step process.

[0024] Compared to the shortcomings of traditional technologies, in this invention, the first blind trench 3 is first fabricated and metallized using a blind via process, and then the second blind trench 6 is opened. Subsequently, when fabricating the outer layer circuitry, only one removal of the anti-etching protective layer 7 and etching treatment are required to complete the connection between the first blind trench 3 and the second blind trench 6 and the etching of the outer circuitry, significantly reducing the number of process steps and the waiting time in intermediate stages, thereby shortening the overall product processing cycle. Secondly, by metallizing the first blind trench 3 first and then opening the second blind trench 6, this invention eliminates the need for complex pre-plating gold protection, improving the reliability and yield of the process, and directly eliminating the cost of using precious metals.

[0025] In some embodiments, step S1 includes the following steps: Step 101: Prepare a laminated structure including multiple layers 1 and prepreg 2 placed between adjacent layers 1, and mark the positions in the laminated structure where metallization holes need to be formed; Step 102: Open a window in the area of ​​the prepreg 2 corresponding to the area where the blind groove is to be formed, and place the resist sheet 8 in the window; Step 103: Press the laminated structure together so that the resist film 8 is embedded in the laminated structure.

[0026] As can be seen from the above, before pressing the laminated structure, a window is opened in the area of ​​the prepreg 2 corresponding to the area where the second blind groove 6 is to be formed, and a resist sheet 8 is placed in the window; during pressing, the resist sheet 8 can effectively prevent the resin of the prepreg 2 from flowing into the area, thereby forming a preset, resin-free cavity in the laminated structure, which facilitates the subsequent milling to form the second blind groove 6 and ensures the cleanliness of the groove wall.

[0027] In some embodiments, in step 101, the marker is a pad, and the diameter of the marker is larger than the diameter of the inner hole of the first blind slot 3. Specifically, at the location where the first blind slot 3 will be drilled in the future, a pad 8 mil (4 mil on each side) larger than the hole diameter is pre-designed to provide sufficient alignment allowance so that the pad can serve as an alignment target for subsequent laser drilling.

[0028] In some embodiments, in step S2, 80%-90% of the medium thickness at the inner hole position of the first blind groove 3 is drilled away using controlled depth drilling, and then the first blind groove 3 is processed by laser drilling. Specifically, when the thickness of the layer plate 1 is large, the remaining medium can be drilled through using laser drilling on the basis of controlled depth drilling to form the first blind groove 3, thereby reducing laser costs; or, in step S2, the first blind groove 3 can be processed by laser drilling. Specifically, when the thickness of the layer plate 1 is small, laser drilling can be used directly for processing.

[0029] In some embodiments, step S4 includes the following steps: Step S401: Perform controlled-depth milling on the laminated structure to the position of the resist film 8 to obtain the second blind groove 6; Step S402: Remove the resist film 8, so that the bottom copper layer 5 of the first blind trench 3 is exposed to the bottom of the second blind trench 6.

[0030] In some embodiments, in step S6, the etch-resistant protective layer 7 located at the bottom of the second blind trench 6 is removed by laser; the etch-resistant protective layer 7 is a tin layer. Specifically, during laser ablation, the scanning path or size of the laser spot is controlled so that its effective area is slightly smaller than the diameter of the opening of the first blind trench 3 below it. For example, the laser processing size can be 2 to 3 mil smaller than the diameter of the first blind trench 3 as compensation for the etching process, ensuring that in subsequent etching steps, the wall of the first blind trench 3 can still be protected by the surrounding etch-resistant protective layer 7, exposing only the copper layer 5 at the bottom of the trench that needs to be removed.

[0031] It should be noted that, with Figure 3 The illustrated stacked structure is used as an example. This stacked structure is arranged in the following order: first layer, second layer, first prepreg, third layer, fourth layer, second prepreg, fifth layer, and sixth layer. The specific operation is as follows: 1. Before laminating the laminated structure, a window is opened in the area of ​​the second semi-cured sheet corresponding to the area where the blind groove is to be formed, and a resist film 8 is pre-embedded in the window; 2. After pressing the laminated structure, drill holes in the fifth and sixth layers to obtain the first blind groove 3, and drill holes in the laminated structure to obtain the outer layer through hole 4; 3. Metallize the surfaces of the first blind groove 3, the outer through hole 4, and the stacked structure; 4. Starting from the first layer, control the depth of the blind groove to the position of the resist sheet 8 to obtain the second blind groove 6, and remove the resist sheet 8. 5. Apply a film to the outer layer to create the circuitry, and then tin-plat the necessary patterns and holes for protection; 6. Use a laser to remove the solder at the bottom of the second blind trench 6. The laser size is 2-3 mil smaller than the hole size. 7. Etch away the copper exposed at the second blind trench 6 position due to the removal of solder, together with the outline circuitry, and then remove the solder to achieve the connection between the first blind trench 3 and the second blind trench 6. 8. Perform subsequent standard procedures such as outer layer AOI inspection, surface treatment, and electrical testing to complete the blind slot plate fabrication.

[0032] Furthermore, the present invention also provides a circuit board manufactured using the aforementioned method for fabricating metallized holes in a blind slot plate. Specifically, the manufacturing method refers to the above embodiments. Since the circuit board adopts all the technical solutions of all the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated upon here.

[0033] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for fabricating a via in a blind-microvia board, the method comprising: It includes the following steps: ​ Step S1: Prepare a laminated structure including multiple layers and a prepreg placed between the multiple layers, and press the laminated structure together. Step S2: Drill holes in the laminated structure to obtain the first blind slot and the outer through hole; Step S3: Metallize the surfaces of the first blind trench, the outer through-hole, and the stacked structure to form a copper layer; Step S4: Perform controlled-depth milling on the stacked structure to obtain the second blind trench, and expose the bottom copper layer of the first blind trench at the bottom of the second blind trench; Step S5: Form an outer layer circuit pattern on the surface of the stacked structure, and plate an anti-etching protective layer on the copper layer surface of the stacked structure. Step S6: Remove the etch-resistant protective layer located at the bottom of the second blind trench and expose the copper layer underneath; Step S7: Perform etching to remove the copper layer exposed at the bottom of the second blind trench and remove the anti-etching protective layer in the remaining area, so that the first blind trench and the second blind trench are connected.

2. The method of claim 1, wherein: Step S1 includes the following steps: Step 101: Prepare a laminated structure including multiple layers and prepreg placed between adjacent layers, and mark the locations in the laminated structure where metallization holes need to be formed; Step 102: Open a window in the area of ​​the prepreg corresponding to the area where the blind groove is to be formed, and place a resist film in the window; Step 103: Press the laminated structure together so that the resist film is embedded in the laminated structure.

3. The method for manufacturing a metallized hole in a blind slot plate according to claim 2, characterized in that: In step 101, the identifier is a pad, and the diameter of the identifier is larger than the diameter of the inner hole of the first blind slot.

4. The method of claim 1, wherein: In step S2, 80%-90% of the medium thickness at the inner hole position of the first blind groove is removed by controlled depth drilling, and then the first blind groove is processed by laser drilling.

5. The method of claim 1, wherein: In step S2, the first blind groove is machined by laser drilling.

6. The method of claim 1, wherein: Step S4 includes the following steps: Step S401: Perform controlled-depth milling on the laminated structure to the position of the resist film to obtain the second blind groove; Step S402: Remove the resist film to expose the bottom copper layer of the first blind trench to the bottom of the second blind trench.

7. The method of claim 1, wherein: In step S6, the anti-etching protective layer located at the bottom of the second blind trench is removed by laser.

8. The method of claim 1, wherein: The etch-resistant protective layer is a tin layer.

9. A circuit board, characterized by: It is manufactured using the method for fabricating metallized holes in a blind slot plate as described in any one of claims 1-8.

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