A method for manufacturing a buried hole cavity of an embedded magnetic material build-up circuit board

Abstract

The application discloses a kind of embedded magnetic material build-up wiring substrate's buried hole cavity manufacturing method, comprising the following steps: via hole layer;Inner layer circuit generation;Dielectric lamination;Inner buried cavity making;Magnetic component placement;Laser;Outer layer circuit generation;The present application is attached to the surface of upper layer circuit and lower layer circuit by hot-pressing process ABF dielectric material, form upper ABF dielectric layer and lower ABF dielectric layer, the good protection effect is played to upper layer circuit and lower layer circuit, simultaneously provide condition for the production of inner buried cavity;The present application is made on ABF dielectric material by Plasma equipment and produces inner buried cavity, can make different size and shape inner buried cavity, and the control of thickness is more accurate than laser or mechanical drilling, solve the problem that traditional drilling operation mode can only make circular inner buried cavity.

Description

Technical Field

[0001] This invention belongs to the field of circuit board technology, specifically relating to a method for fabricating buried via cavities in an embedded magnetic material layered circuit board. Background Technology

[0002] Traditional circuit board wiring methods are gradually moving towards high-density wiring patterns. The demand for multi-functionality and miniaturization has brought new challenges to both packaging and substrates. More 2.5 & 3D packaging technologies have emerged, including embedded packaging technology, and the urgency of demand is increasing day by day.

[0003] Embedded packaging technology embeds passive components such as resistors, capacitors, and inductors, and even active devices such as ICs, into the printed circuit board. However, due to the limitations of current processes, it is more difficult to implement embedded technology by transferring it from the PCB to the substrate, because the circuitry on the substrate is dense, the thickness of the embedded cavity is thinner, and the precision requirements are higher.

[0004] In existing methods for fabricating embedded cavities in the layer-addition stage of embedded circuit boards, the cavities are mostly fabricated by drilling holes in the substrate layer. However, the cavity drilling method is only suitable for fabricating circular cavities and cannot produce other shapes and sizes of cavities. Summary of the Invention

[0005] To address the problems mentioned in the background section, this invention provides a method for fabricating buried via cavities in an embedded magnetic material layered circuit board. This method allows for the fabrication of buried cavities of various shapes, and the size and thickness can be controlled more effectively than with laser or mechanical drilling.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for fabricating a buried via cavity in an embedded magnetic material add-on circuit board, comprising the following steps:

[0007] (I) Via layer: Take a BT substrate as the substrate layer. The substrate layer includes an upper copper layer and a lower copper layer. Via is generated by mechanical or laser processing.

[0008] (II) Inner layer circuit generation: The upper layer circuit and the lower layer circuit are generated by the circuit subtraction method;

[0009] (III) Dielectric lamination: ABF dielectric material is attached to the surface of the upper and lower circuits through a hot pressing process to form an upper ABF dielectric layer and a lower ABF dielectric layer.

[0010] (iv) Internal cavity construction;

[0011] (V) Insertion of magnetic components: Place the magnetic components provided by the customer into the embedded cavity and protect and fix them in place;

[0012] (vi) Laser: Laser laser is performed from the sides of the upper ABF dielectric layer and the lower ABF dielectric layer respectively to form upper laser holes and lower laser holes;

[0013] (vii) Outer layer circuit generation: The upper and lower copper layers of the circuit are generated by the circuit layering method;

[0014] Step (four) includes the following steps:

[0015] (1) A thin copper layer is deposited on the upper ABF dielectric layer using the Sputter chemical gradient plating method;

[0016] (2) The transparent dry film is covered onto the copper layer on which the embedded cavity needs to be made through a hot pressing process, and the location of the cavity needs to be made is exposed by exposure and development processes.

[0017] (3) Use a fast etching copper biting method to clean the exposed copper layer and expose the underlying upper ABF dielectric layer.

[0018] (4) Using Plasma equipment, the inner cavity of the upper ABF dielectric layer without copper layer protection is excavated according to the size and shape of the magnetic components.

[0019] (5) Film removal: Remove the remaining light-transmitting dry film covering the upper ABF dielectric layer;

[0020] (6) Etching: Use the rapid etching copper etching method again to clean the copper layer exposed after the dry film is removed.

[0021] Furthermore, in step (iv), the thickness of the embedded cavity is based on being 10µm thicker than the thickness of the embedded component required by the customer.

[0022] To create the inner layer circuitry, step (two) further includes the following steps:

[0023] (A1) A light-transmitting dry film is applied to the upper and lower copper layers by a hot-pressing process.

[0024] (A2) The circuit pattern is generated on the dry film through a UV exposure machine. After dry film exposure, development and copper etching by the circuit subtraction method, the upper and lower circuits are generated.

[0025] In order to protect the upper and lower layer circuits and to provide conditions for the fabrication of the embedded cavity, step (iii) further includes the following steps:

[0026] (B1) Take two portions of ABF dielectric material;

[0027] (B2) The ABF material is applied to the surfaces of the upper and lower circuits by hot pressing, so that the ABF material fills the space outside the upper and lower circuits, forming the upper ABF dielectric layer and the lower ABF dielectric layer.

[0028] In order to ensure that the thickness of the upper ABF dielectric layer plus the ABF dry film is the same as the thickness of the lower ABF dielectric layer after the circuit board is fabricated, further, in step (iii), the thickness of the upper ABF dielectric layer is less than the thickness of the lower ABF dielectric layer, and the thickness of the upper ABF dielectric layer is greater than the thickness of the magnetic component.

[0029] To secure and protect the magnetic components, step (v) further includes the following steps:

[0030] (C1) Pick up a magnetic component with 3M Tape attached, align it, and place it into the embedded cavity;

[0031] (C2) Take a piece of ABF dry film and attach it to the upper ABF dielectric layer through a hot pressing process to increase the thickness of the upper ABF dielectric layer and fill the space of the embedded cavity. At this time, the thickness of the upper ABF dielectric layer plus the ABF dry film is the same as the thickness of the lower ABF dielectric layer.

[0032] Furthermore, in step (v), the positional offset of the magnetic component is less than + / - 5 μm.

[0033] To achieve the connection between the inner layer circuitry, the outer layer circuitry, and the magnetic components, step (vi) further includes the following steps:

[0034] (D1) First, laser light is applied to the ABF dry film, the upper ABF dielectric layer and the lower ABF dielectric layer. The ABF dry film, the upper ABF dielectric layer and the lower ABF dielectric layer partially absorb the energy of the laser light.

[0035] (D2) Then, the ABF dry film, the upper ABF dielectric layer and the lower ABF dielectric layer are subjected to laser light. After the laser light is absorbed by the ABF dry film, the upper ABF dielectric layer and the lower ABF dielectric layer, the upper laser hole and the lower laser hole are formed.

[0036] (D3) At least one upper laser hole corresponds to the position of the magnetic component inside the embedded cavity.

[0037] To create the outer layer circuitry, step (seven) further includes the following steps:

[0038] (E1) After E-less process, a thin copper layer is formed on the surface of the upper laser hole, ABF dry film, lower laser hole and lower ABF dielectric layer.

[0039] (E2) The transparent dry film is attached to the thin copper layer by a hot pressing process on both sides. The circuit pattern is generated on the dry film by a UV exposure machine. The dry film is then exposed, developed and the circuit layer is added by electroplating to generate the upper and lower circuit copper layers, while filling the upper and lower laser holes.

[0040] (E3) Remove film: Remove the remaining dry film.

[0041] Compared with the prior art, the beneficial effects of the present invention are:

[0042] 1. This invention uses a hot-pressing process to attach ABF dielectric material to the surfaces of the upper and lower layers of circuitry, forming an upper ABF dielectric layer and a lower ABF dielectric layer, which provides excellent protection for the upper and lower layers of circuitry and also provides conditions for the fabrication of the embedded cavity.

[0043] 2. This invention uses a Plasma device to create an embedded cavity on an ABF dielectric material, which can produce embedded cavities of different sizes and shapes. The thickness control is more precise than that of laser or mechanical drilling, solving the problem that traditional drilling methods can only produce circular embedded cavities.

[0044] 3. This invention achieves the connection of inner layer circuitry, outer layer circuitry, and magnetic components through upper and lower laser holes;

[0045] 4. This invention uses ABF dry film to fix and protect magnetic components, and increases the thickness of the upper ABF dielectric layer so that after the circuit board is fabricated, the thickness of the upper ABF dielectric layer plus the ABF dry film is the same as the thickness of the lower ABF dielectric layer.

[0046] 5. In this invention, the front side of the circuit board contains two ABF dielectric layers, while the back side has only one ABF dielectric layer. This can shorten the information transmission path of the system-in-package, thereby improving the transmission speed. It can also meet the development requirements of advanced 2.5D and 3D packaging technologies and provide greater flexibility in the substrate manufacturing process. Attached Figure Description

[0047] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0048] Figure 1 and 2 This is a structural schematic diagram of step (one) of the present invention;

[0049] Figure 3 This is a schematic diagram of the structure of step (ii) of the present invention;

[0050] Figure 4 This is a structural schematic diagram of step (iii) of the present invention;

[0051] Figure 5 This is a structural schematic diagram of step (four) of the present invention;

[0052] Figure 6 This is a structural schematic diagram of step (v) of the present invention;

[0053] Figure 7 This is a structural schematic diagram of step (six) of the present invention;

[0054] Figure 8 This is a structural schematic diagram of step (vii) of the present invention;

[0055] In the diagram: 1. Substrate layer; 101. Upper copper layer; 102. Lower copper layer; 2. Upper circuitry; 3. Lower circuitry; 4. Via; 5. Upper ABF dielectric layer; 6. Lower ABF dielectric layer; 7. Embedded cavity; 8. Magnetic component; 9. 3M Tape; 10. Upper laser aperture; 11. Lower laser aperture; 12. ABF dry film; 13. Upper copper layer; 14. Lower copper layer. Detailed Implementation

[0056] 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 some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] Example 1

[0058] Please see Figure 1-8 The present invention provides the following technical solution: a method for fabricating a buried via cavity in an embedded magnetic material add-on circuit board, comprising the following steps:

[0059] (I) Via layer: A BT substrate is used as substrate layer 1. Substrate layer 1 includes an upper copper layer 101 and a lower copper layer 102. Via 4 is generated by mechanical or laser processing.

[0060] (II) Inner layer circuit generation: The upper layer circuit 2 and the lower layer circuit 3 are generated by the circuit subtraction method;

[0061] (III) Dielectric lamination: ABF dielectric material is attached to the surface of the upper circuit 2 and the lower circuit 3 through hot pressing process to form upper ABF dielectric layer 5 and lower ABF dielectric layer 6.

[0062] (iv) Internal cavity construction;

[0063] (V) Insertion of magnetic components: Place the magnetic components 8 provided by the customer into the embedded cavity 7 and protect and fix them;

[0064] (vi) Laser: Laser laser is performed from the sides of the upper ABF dielectric layer 5 and the lower ABF dielectric layer 6 respectively to form upper laser hole 10 and lower laser hole 11;

[0065] (VII) Outer layer circuit generation: The upper copper layer 13 and the lower copper layer 14 are generated by the circuit layering method;

[0066] Specifically, step (four) includes the following steps:

[0067] (1) A thin copper layer is deposited on the upper ABF dielectric layer 5 using the Sputter chemical gradient plating method;

[0068] (2) The transparent dry film is covered onto the copper layer on which the embedded cavity needs to be made through a hot pressing process, and the location of the cavity needs to be made is exposed by exposure and development processes.

[0069] (3) Use a fast etching copper biting method to bite off the exposed copper layer cleanly, revealing the upper ABF dielectric layer 5 underneath;

[0070] (4) Using a Plasma device, according to the size and shape of the magnetic component 8, the inner cavity 7 of the upper ABF dielectric layer 5 without copper layer protection is excavated.

[0071] (5) Film removal: Remove the remaining light-transmitting dry film covering the upper ABF dielectric layer 5;

[0072] (6) Etching: Use the rapid etching copper etching method again to clean the copper layer exposed after the dry film is removed.

[0073] By adopting the above technical solution, this invention uses a hot-pressing process to attach ABF dielectric material to the surfaces of the upper layer circuit 2 and the lower layer circuit 3, forming an upper ABF dielectric layer 5 and a lower ABF dielectric layer 6, which provides excellent protection for the upper layer circuit 2 and the lower layer circuit 3, while also providing conditions for the fabrication of the embedded cavity 7. This invention uses a Plasma device to act on the ABF dielectric material to fabricate the embedded cavity 7, which can produce embedded cavities 7 of different sizes and shapes, and the thickness control is more precise than laser or mechanical drilling, solving the problem that traditional drilling methods can only produce circular embedded cavities.

[0074] Specifically, in step (four), the thickness of the embedded cavity 7 is based on being 10µm thicker than the thickness of the embedded component required by the customer.

[0075] Specifically, step (two) includes the following steps:

[0076] (A1) A light-transmitting dry film is applied to the upper copper layer 101 and the lower copper layer 102 by a hot-pressing process.

[0077] (A2) The circuit pattern is generated on the dry film through a UV exposure machine. After dry film exposure, development and copper etching by the circuit subtraction method, the upper circuit 2 and the lower circuit 3 are generated.

[0078] By adopting the above technical solution, the inner layer circuitry was fabricated.

[0079] Specifically, step (three) includes the following steps:

[0080] (B1) Take two portions of ABF dielectric material;

[0081] (B2) The ABF material is applied to the surfaces of the upper circuit 2 and the lower circuit 3 by hot pressing, so that the ABF material fills the space outside the upper circuit 2 and the lower circuit 3, forming the upper ABF dielectric layer 5 and the lower ABF dielectric layer 6.

[0082] By adopting the above technical solution, an upper ABF dielectric layer 5 and a lower ABF dielectric layer 6 are fabricated, which protect the upper circuit 2 and the lower circuit 3, and at the same time provide conditions for the fabrication of the embedded cavity 7.

[0083] Specifically, step (six) includes the following steps:

[0084] (D1) First, the ABF dry film 12, the upper ABF dielectric layer 5 and the lower ABF dielectric layer 6 are subjected to laser light, and the ABF dry film 12, the upper ABF dielectric layer 5 and the lower ABF dielectric layer 6 partially absorb the energy of the laser light.

[0085] (D2) Then, the laser is applied to the ABF dry film 12, the upper ABF dielectric layer 5 and the lower ABF dielectric layer 6. After the laser is absorbed by the ABF dry film 12, the upper ABF dielectric layer 5 and the lower ABF dielectric layer 6, the upper laser hole 10 and the lower laser hole 11 are formed.

[0086] (D3) At least one upper laser hole 10 corresponds to the position of the magnetic component 8 inside the embedded cavity 7.

[0087] By adopting the above technical solution, the connection of the inner layer circuit, the outer layer circuit, and the magnetic component 8 is achieved through the upper laser hole 10 and the lower laser hole 11.

[0088] Specifically, step (seven) includes the following steps:

[0089] (E1) After E-less process, a thin copper layer is formed on the surface of the upper laser hole 10, ABF dry film 12, lower laser hole 11 and lower ABF dielectric layer 6.

[0090] (E2) A light-transmitting dry film is attached to a thin copper layer on both sides by a hot pressing process. The circuit pattern is generated on the dry film by a UV exposure machine. The dry film is then exposed, developed and electroplated to generate the upper copper layer 13 and the lower copper layer 14, while filling the upper laser hole 10 and the lower laser hole 11.

[0091] (E3) Remove film: Remove the remaining dry film.

[0092] The outer layer circuitry was fabricated using the aforementioned technical solution.

[0093] Example 2

[0094] The difference between this embodiment and embodiment 1 is that, specifically, in step (iii), the thickness of the upper ABF dielectric layer 5 is less than the thickness of the lower ABF dielectric layer 6, and the thickness of the upper ABF dielectric layer 5 is greater than the thickness of the magnetic component 8.

[0095] By adopting the above technical solution, after the circuit board is manufactured, the thickness of the upper ABF dielectric layer 5 plus the ABF dry film 12 is the same as the thickness of the lower ABF dielectric layer 6.

[0096] Example 3

[0097] The difference between this embodiment and embodiment 1 is that, specifically, step (v) includes the following steps:

[0098] (C1) Pick up a magnetic component 8 with 3M Tape 9 attached, align it, and put it into the embedded cavity 7.

[0099] (C2) Take a portion of ABF dry film 12 and attach it to the upper ABF dielectric layer 5 through a hot pressing process to increase the thickness of the upper ABF dielectric layer 5 and fill the space of the embedded cavity 7. At this time, the thickness of the upper ABF dielectric layer 5 plus the ABF dry film 12 is the same as the thickness of the lower ABF dielectric layer 6.

[0100] By adopting the above technical solution, the magnetic component 8 can be fixed and protected.

[0101] Specifically, in step (v), the position offset of the magnetic component 8 is less than + / - 5um.

[0102] In summary, this invention uses a hot-pressing process to attach ABF dielectric material to the surfaces of the upper layer circuit 2 and the lower layer circuit 3, forming an upper ABF dielectric layer 5 and a lower ABF dielectric layer 6. This provides excellent protection for the upper layer circuit 2 and the lower layer circuit 3, while also providing conditions for the fabrication of the embedded cavity 7. This invention uses a Plasma device to fabricate the embedded cavity 7 on the ABF dielectric material, allowing for the production of embedded cavities 7 of different sizes and shapes. Furthermore, the thickness control is more precise than laser or mechanical drilling, solving the problems associated with traditional drilling methods. The present invention addresses the limitation of only being able to fabricate circular embedded cavities. It achieves the connection of inner layer circuitry, outer layer circuitry, and magnetic component 8 through upper laser aperture 10 and lower laser aperture 11. Furthermore, the present invention uses ABF dry film 12 to fix and protect the magnetic component 8, and increases the thickness of the upper ABF dielectric layer 5, so that after the circuit board is fabricated, the thickness of the upper ABF dielectric layer 5 plus the ABF dry film 12 is the same as the thickness of the lower ABF dielectric layer 6. In the present invention, the front side of the circuit board contains two ABF dielectric layers, while the back side has only one ABF dielectric layer.

[0103] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for fabricating a buried via cavity in an embedded magnetic material add-on circuit board, characterized in that, Includes the following steps: (I) Via layer: Take a BT substrate as the substrate layer. The substrate layer includes an upper copper layer and a lower copper layer. Via is generated by mechanical or laser processing. (II) Inner layer circuit generation: The upper layer circuit and the lower layer circuit are generated by the circuit subtraction method; (III) Dielectric lamination: The ABF dielectric material is attached to the surface of the upper and lower circuits through a hot pressing process to form an upper ABF dielectric layer and a lower ABF dielectric layer. (iv) Internal cavity construction; (V) Insertion of magnetic components: Place the magnetic components provided by the customer into the embedded cavity and protect and fix them in place; (vi) Laser: Laser laser is performed from the sides of the upper ABF dielectric layer and the lower ABF dielectric layer respectively to form upper laser holes and lower laser holes; (vii) Outer layer circuit generation: The upper and lower copper layers of the circuit are generated by the circuit layering method; Step (four) includes the following steps: (1) A thin copper layer is deposited on the upper ABF dielectric layer using the Sputter chemical gradient plating method; (2) The transparent dry film is covered onto the copper layer on which the embedded cavity needs to be made through a hot pressing process, and the location of the cavity needs to be made is exposed by exposure and development processes. (3) Use a fast etching copper biting method to clean the exposed copper layer and expose the underlying upper ABF dielectric layer. (4) Using Plasma equipment, the inner cavity of the upper ABF dielectric layer without copper layer protection is excavated according to the size and shape of the magnetic components. (5) Film removal: Remove the remaining light-transmitting dry film covering the upper ABF dielectric layer; (6) Etching: Use the rapid etching copper etching method again to clean the copper layer exposed after the dry film is removed.

2. The method for fabricating a buried via cavity in an embedded magnetic material add-on circuit board according to claim 1, characterized in that: In step (iv), the thickness of the embedded cavity is based on being 10µm thicker than the thickness of the embedded component required by the customer.

3. The method for fabricating a buried via cavity in an embedded magnetic material add-on circuit board according to claim 1, characterized in that: Step (II) includes the following steps: (A1) A light-transmitting dry film is applied to the upper and lower copper layers by a hot-pressing process. (A2) The circuit pattern is generated on the dry film through a UV exposure machine. After dry film exposure, development and copper etching by the circuit subtraction method, the upper and lower circuits are generated.

4. The method for fabricating a buried via cavity in an embedded magnetic material add-on circuit board according to claim 1, characterized in that: Step (3) includes the following steps: (B1) Take two portions of ABF dielectric material; (B2) The ABF material is applied to the surfaces of the upper and lower circuits by hot pressing, so that the ABF material fills the space outside the upper and lower circuits, forming the upper ABF dielectric layer and the lower ABF dielectric layer.

5. The method for fabricating a buried via cavity in an embedded magnetic material add-on circuit board according to claim 4, characterized in that: In step (iii), the thickness of the upper ABF dielectric layer is less than the thickness of the lower ABF dielectric layer, and the thickness of the upper ABF dielectric layer is greater than the thickness of the magnetic component.

6. The method for fabricating a buried via cavity in an embedded magnetic material add-on circuit board according to claim 1, characterized in that: Step (5) includes the following steps: (C1) Pick up a magnetic component with 3M Tape attached, align it, and place it into the embedded cavity; (C2) Take a portion of ABF dry film and attach it to the upper ABF dielectric layer through a hot pressing process to increase the thickness of the upper ABF dielectric layer and fill the space of the embedded cavity. At this time, the thickness of the upper ABF dielectric layer plus the ABF dry film is the same as the thickness of the lower ABF dielectric layer.

7. The method for fabricating a buried via cavity in an embedded magnetic material add-on circuit board according to claim 1, characterized in that: In step (5), the positional offset of the magnetic component is less than + / - 5 μm.

8. The method for fabricating a buried via cavity in an embedded magnetic material add-on circuit board according to claim 1, characterized in that: Step (six) includes the following steps: (D1) First, laser light is applied to the ABF dry film, the upper ABF dielectric layer and the lower ABF dielectric layer. The ABF dry film, the upper ABF dielectric layer and the lower ABF dielectric layer partially absorb the energy of the laser light. (D2) Then, the ABF dry film, the upper ABF dielectric layer and the lower ABF dielectric layer are subjected to laser light. After the laser light is absorbed by the ABF dry film, the upper ABF dielectric layer and the lower ABF dielectric layer, the upper laser hole and the lower laser hole are formed. (D3) At least one upper laser hole corresponds to the position of the magnetic component inside the embedded cavity.

9. The method for fabricating a buried via cavity in an embedded magnetic material add-on circuit board according to claim 1, characterized in that: Step (seven) includes the following steps: (E1) After E-less process, a thin copper layer is formed on the surface of the upper laser hole, ABF dry film, lower laser hole and lower ABF dielectric layer. (E2) The transparent dry film is attached to the thin copper layer by a hot pressing process on both sides. The circuit pattern is generated on the dry film by a UV exposure machine. The dry film is then exposed, developed and the circuit layer is added by electroplating to generate the upper and lower circuit copper layers, while filling the upper and lower laser holes. (E3) Remove film: Remove the remaining dry film.

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