Circuit board with special cavity structure and manufacturing method thereof

Abstract

The invention provides a circuit board with a special cavity structure and a manufacturing method thereof. The circuit board with the special cavity structure comprises a core board with a cavity, a stand column is arranged in the middle of the cavity, and the hollow-square-shaped cavity is formed in the periphery of the stand column. The structural design that the stand column is arranged in the middle of the cavity is adopted, the continuous structure without internal blocking parts in a traditional cavity is broken through, conventional simple materials easy to obtain in industrial production are used for processing and manufacturing the interrupted cavity structure with the complex structure, the cavity does not collapse, the interlayer bonding force is good, and the structure is stable. And industrial operations such as PCB lamination, mechanical drilling of through holes, copper plating and the like can be normally carried out in the upright post area in the middle of the cavity.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit boards, and in particular to a circuit board with a special cavity structure and a manufacturing method thereof. Background Art

[0002] At present, various structures of cavity circuit boards have appeared in the market or in the industry, but they are basically the following four types. For example, the cavity structure in Patent 1, "Compression-fitting structure of cavity circuit board" (application number CN201420496366.8) is an embedded continuous type.

[0003] The cavity structure in Patent 2, "Cavity Board Anti-Deformation Structure" (application number CN202022587023.0), is also an embedded continuous type. What is different from Patent 1 is that this scheme has a conductive hole designed from the top or bottom layer of the PCB to the cavity direction, and the pressure inside and outside the cavity is equal, so the structure naturally has the function of preventing dents and deformation.

[0004] The cavity structure in Patent 3, "A printed circuit board with a cavity and its manufacturing method" (application number CN202310748883.3) is externally open. After the PCB main body is completed, a cavity is formed from the outside at a fixed depth using a forming blind scooping machine.

[0005] The cavity structure in Patent 4, "A PCB with Cavity and Its Manufacturing Method" (Application No. CN202310290632.5) appears to be an embedded interrupted type, and there is a tripod column in the middle of the cavity, which makes the cavity discontinuous. But in fact, during the PCB manufacturing process, firstly, the inner side of the upper and lower core boards that contact the cavity are reserved for accommodation holes and pre-grooves, and then before the lamination of each PCB sub-board, the tripod column is physically snapped into the pre-groove, and the copper column contained in the tripod column is plugged and connected with the upper and lower accommodation holes, thereby closing to form an embedded interrupted cavity.

[0006] The cavity structures of all the above technical solutions are mostly embedded continuous type, with relatively simple cavity structures, and their front and top views are both continuous standard rectangles or standard circles without internal blocking parts. Occasionally, the cavity structure is a more complex embedded interrupted type, but the pillars that cause the cavity interruption are not made of PCB itself, but are auxiliary components outside the PCB field, which are difficult to manufacture, and the operation of the pillars when combined with the PCB process is also more complicated. In addition, the cavity with a simple structure is prone to collapse, and the cavity part cannot be pressed, mechanically drilled, or copper plated. Summary of the invention

[0007] The present invention provides a circuit board with a special cavity structure and a method for manufacturing the same, the purpose of which is to solve the technical problems in the background technology that the cavity structure is simple, the cavity is continuous without internal blocking components, the cavity is easy to collapse, the cavity part cannot be pressed together, mechanically drilled through holes, and the manufacturing is difficult.

[0008] In order to achieve the above-mentioned purpose, the present invention provides a circuit board with a special cavity structure, including a core board with a cavity, a column is provided in the middle of the cavity, and a U-shaped cavity is formed around the column.

[0009] Preferably, the column material is copper clad laminate.

[0010] Preferably, the core board containing the cavity comprises a top layer of base copper, an insulating FR4 dielectric layer and a bottom layer of base copper which are stacked in sequence.

[0011] Preferably, the core board containing the cavity is an L4-5 layer core board, and also includes an L2-3 layer core board, the L2-3 layer core board includes a top layer of base copper, an insulating FR4 dielectric layer and a bottom layer of base copper stacked in sequence, and a low-flow glue semi-cured sheet is provided between the L2-3 layer core board and the L4-5 layer core board.

[0012] Preferably, it also includes an L1 layer of copper foil and an L6 layer of copper foil, wherein the L1 layer of copper foil is connected to the L2-3 layer core board via a common flow glue semi-cured sheet, and the L4-5 layer core board is connected to the L6 layer of copper foil via a common flow glue semi-cured sheet.

[0013] Preferably, it also includes L2-5 core board mechanical through holes, L1-6 mechanical through holes, L1-2 laser blind holes and L5-6 laser blind holes;

[0014] The mechanical through holes of the L2-5 core plate pass through the L2-3 core plate and the L4-5 core plate; the distribution area is the outer general area and the column area;

[0015] The L1-6 layer mechanical through holes pass through the L1 layer copper foil, the L2-3 layer core board, the L4-5 layer core board and the L6 layer copper foil; the distribution area is the outer general area and the column area;

[0016] The L1-2 layer laser blind holes pass through the L1 layer copper foil and the top layer base copper of the L2-3 layer core board; the distribution areas are the outer general area, the upper and lower areas of the cavity, and the column area;

[0017] The L5-6 layer laser blind holes pass through the L6 layer copper foil and the bottom base copper of the L4-5 layer core board; the distribution areas are the outer general area, the upper and lower areas of the cavity, and the column area.

[0018] The present invention provides a method for manufacturing a circuit board with a special cavity structure, comprising the following steps: preparing an L4-5 layer core board: after the basic core board is manufactured, controlled depth milling is performed to form a U-shaped cavity with a column; preparing a cavity built-in gasket: the shape of the cavity built-in gasket is adapted to the U-shaped cavity, and the cavity built-in gasket includes at least two separable and removable gaskets.

[0019] Preferably, the preparation of the L4-5 layer core board specifically includes the following steps:

[0020] Cutting, mechanical drilling, pre-treatment brushing, inner layer lamination, inner layer exposure, acid etching, leg film, controlled depth milling, X-ray drilling riveting holes, browning, to form the stacked plates to be pressed;

[0021] The preparation of the cavity built-in gasket specifically comprises the following steps:

[0022] Cutting, copper reduction, pre-treatment brushing, sticking high temperature resistant tape, mechanical drilling, milling gasket shape, quality inspection, forming the stacked plates to be pressed.

[0023] Preferably, the method further comprises the following steps:

[0024] Prepare L2-3 core board;

[0025] Preparation of low-flow prepreg;

[0026] Preparation of common flow-cured prepreg;

[0027] preparing an outer copper foil;

[0028] The first lamination forms the L2-5 layers;

[0029] The second pressing forms the L1-6 layers.

[0030] Preferably, the preparation of the L2-3 layer core board specifically includes the following steps:

[0031] Cutting, pre-treatment brushing, inner layer lamination, inner layer exposure, acid etching, leg film, CCD drilling riveting holes, browning, forming the stacked boards to be pressed;

[0032] The preparation of the low-flow prepreg specifically comprises the following steps:

[0033] Cut the material, drill the riveting holes, and form the stacked plates to be pressed together;

[0034] The preparation of the common flow-resist prepreg and the preparation of the outer copper foil specifically include the following steps:

[0035] Cutting the material to form a stacked plate to be pressed;

[0036] The first lamination to form the L2-5 layer specifically includes the following steps:

[0037] Stacking, placing gaskets, pressing, X-ray drilling positioning holes, milling edges, horizontal debonding, mechanical drilling, brushing, chemical copper deposition, whole board electroplating, resin plugging, final curing, ceramic brushing, chemical copper deposition, whole board electroplating, pre-treatment brushing, inner layer circuit, inner layer AOI inspection, browning, to form a stacked board to be pressed;

[0038] The second lamination to form the L1-6 layers specifically comprises the following steps:

[0039] Stacking, lamination, X-ray drilling of positioning holes, milling, browning, laser drilling, mechanical drilling, brushing, horizontal debonding, horizontal PTH, flash plating, hole filling plating, outer layer circuit, outer layer AOI inspection, solder mask, gold plating, milling shape, gasket extraction, four-wire test, and final inspection.

[0040] The circuit board with a special cavity structure and the manufacturing method thereof of the present invention have the following beneficial effects:

[0041] The structural design of setting a column in the middle of the cavity breaks through the continuous structure without internal blocking components in the traditional cavity, and uses conventional simple materials that are easily obtained in industrial production to process and manufacture a more complex interrupted cavity structure. The cavity does not collapse and has good interlayer adhesion. The column area in the middle of the cavity can be used for industrial operations such as PCB pressing, mechanical drilling, copper plating, etc.

[0042] From the processing flow of L4-5 layer, it can be seen that the cavity is not prefabricated by the traditional core plate window opening process, but by the thick core plate plus controlled deep milling process to prefabricate the cavity before pressing. Therefore, the outer shape of the cavity and the "support column", that is, the shape of the column can be changed arbitrarily in theory, and there is no need to worry about the "support column" falling off or shifting.

[0043] From the matching design of the gasket and the cavity, it can be seen that after the gasket is combined, the overall volume of the cavity is almost the same, which is equivalent to almost squeezing out all the gas in the cavity and filling the cavity. Therefore, when pressing at high temperature, a large amount of resin glue will not melt from the prepreg and flow into the cavity to cause uneven dielectric thickness and serious concavity above the cavity, which provides good conditions for making high-precision laser blind holes in the L1-6 layers;

[0044] As long as the gasket is not designed to be naturally obstructed, that is, the built-in gasket in the cavity contains at least two separable and removable gaskets, the gasket removal method is universal and effective. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 A front view of a preferred embodiment of a circuit board with a special cavity structure according to the present invention;

[0046] Figure 2 for Figure 1 A top view of a preferred embodiment of a circuit board with a special cavity structure is shown;

[0047] Figure 3 for Figure 1 A side view of a preferred embodiment of a circuit board having a special cavity structure;

[0048] Figure 4 It is a structural schematic diagram of another preferred embodiment of a circuit board with a special cavity structure of the present invention;

[0049] Figure 5 It is a structural schematic diagram of a preferred embodiment of a gasket of a circuit board with a special cavity structure of the present invention;

[0050] Figure 6 It is a structural schematic diagram of another preferred embodiment of a gasket of a circuit board with a special cavity structure of the present invention;

[0051] Figure 7 It is a structural schematic diagram of another preferred embodiment of a gasket of a circuit board with a special cavity structure of the present invention;

[0052] Figure 8 It is a schematic diagram of forming L2-5 layers by the first lamination in a method for manufacturing a circuit board with a special cavity structure of the present invention;

[0053] Fig. 9 It is a schematic diagram of forming L1-6 layers by the second lamination in a method for manufacturing a circuit board with a special cavity structure of the present invention. DETAILED DESCRIPTION

[0054] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0055] In view of the existing problems, the present invention provides a circuit board with a special cavity structure and a manufacturing method thereof.

[0056] In one embodiment, a circuit board having a special cavity structure, such as Figures 1 to 3 As shown, it includes a core plate containing a cavity, a column 32 is provided in the middle of the cavity, and a U-shaped cavity is formed around the column 32.

[0057] The material of the pillar 32 is copper clad laminate.

[0058] In another preferred embodiment, Figure 4 As shown, the core board containing the cavity includes a top layer base copper 20, an insulating FR4 dielectric layer 21 and a bottom layer base copper 22 which are stacked in sequence.

[0059] The core board containing the cavity 8 is an L4-5 layer core board, and also includes an L1 layer copper foil 14, an L2-3 layer core board, an L6 layer copper foil 24, an L2-5 layer core board mechanical through holes 1, 3, an L1-6 layer mechanical through holes 2, 4, an L1-2 layer laser blind holes 4, 5, 6 and an L5-6 layer laser blind holes 10, 11, 13.

[0060] The L2-3 layer core board includes a top layer base copper 16, an insulating FR4 dielectric layer 17 and a bottom layer base copper 18 which are stacked in sequence, and a low-flow adhesive prepreg 19 is provided between the L2-3 layer core board and the L4-5 layer core board.

[0061] The L1 layer copper foil 14 is connected to the L2-3 layer core board via a common flow adhesive prepreg 15 , and the L4-5 layer core board is connected to the L6 layer copper foil 24 via a common flow adhesive prepreg 23 .

[0062] The mechanical through holes 1 and 3 of the L2-5 core plate pass through the L2-3 core plate and the L4-5 core plate; the distribution area is the outer general area and the column 32 area;

[0063] The L1-6 layer mechanical through holes 2, 4 pass through the L1 layer copper foil 14, the L2-3 layer core board, the L4-5 layer core board and the L6 layer copper foil 24; the distribution area is the outer general area and the column 32 area;

[0064] The L1-2 layer laser blind holes 5, 6, 7 pass through the L1 layer copper foil 14 and the top layer base copper 16 of the L2-3 layer core board; the distribution areas are the outer general area, the upper and lower areas of the cavity 8 and the column 32 area;

[0065] The L5-6 layer laser blind holes 10, 11, 13 pass through the L6 layer copper foil 24 and the bottom base copper 22 of the L4-5 layer core board; the distribution areas are the outer general area, the upper and lower areas of the cavity 8 and the column 32 area.

[0066] The present invention provides a method for manufacturing a circuit board with a special cavity structure, comprising the following steps: preparing an L4-5 layer core board: performing controlled depth milling after manufacturing a basic core board to form a U-shaped cavity 8 with a column 32;

[0067] Prepare the cavity built-in gasket 9: the shape of the cavity built-in gasket 9 is adapted to the U-shaped cavity 8. Figures 5 to 7 As shown, the cavity built-in gasket 9 includes at least two separable and removable gaskets.

[0068] Prepare L2-3 core board;

[0069] Preparation of low-flow prepreg 19;

[0070] Preparation of common flow glue prepreg15,23;

[0071] preparing an outer copper foil;

[0072] The first lamination forms the L2-5 layers, such as Figure 8 As shown;

[0073] The second lamination forms the L1-6 layers, such as Fig. 9 shown.

[0074] The preparation of the L4-5 layer core board specifically includes the following steps:

[0075] Cutting, mechanical drilling, pre-treatment brushing, inner layer lamination, inner layer exposure, acid etching, leg film, controlled depth milling, X-ray drilling riveting holes, browning, to form the stacked plates to be pressed;

[0076] The preparation of the cavity built-in gasket specifically comprises the following steps:

[0077] Cutting, copper reduction, pre-treatment brushing, sticking high temperature resistant tape, mechanical drilling, milling gasket shape, quality inspection, forming the stacked plates to be pressed.

[0078] The preparation of the L2-3 layer core board specifically includes the following steps:

[0079] Cutting, pre-treatment brushing, inner layer lamination, inner layer exposure, acid etching, leg film, CCD drilling riveting holes, browning, forming the stacked boards to be pressed;

[0080] The preparation of the low-flow prepreg 19 specifically includes the following steps:

[0081] Cut the material, drill the riveting holes, and form the stacked plates to be pressed together;

[0082] The preparation of the common flow-resist prepreg 15, 23 and the preparation of the outer copper foil specifically include the following steps:

[0083] Cutting the material to form a stacked plate to be pressed;

[0084] The first lamination to form the L2-5 layer specifically includes the following steps:

[0085] Stacking, placing gaskets, pressing, X-ray drilling positioning holes, milling edges, horizontal debonding, mechanical drilling, brushing, chemical copper deposition, whole board electroplating, resin plugging, final curing, ceramic brushing, chemical copper deposition, whole board electroplating, pre-treatment brushing, inner layer circuit, inner layer AOI inspection, browning, to form a stacked board to be pressed;

[0086] The second lamination to form the L1-6 layers specifically comprises the following steps:

[0087] Stacking, lamination, X-ray drilling of positioning holes, milling, browning, laser drilling, mechanical drilling, brushing, horizontal debonding, horizontal PTH, flash plating, hole filling plating, outer layer circuit, outer layer AOI inspection, solder mask, gold plating, milling shape, gasket extraction, four-wire test, and final inspection.

[0088] The circuit board with a special cavity structure and the manufacturing method thereof of the present invention have the following beneficial effects:

[0089] A structural design in which a column 32 is provided in the middle of the cavity 8 breaks through the continuous structure without internal blocking components in the traditional cavity 8, and uses conventional simple materials that are easily obtained in industrial production to process and manufacture a more complex interrupted cavity structure. The cavity does not collapse and has good interlayer adhesion. The column area in the middle of the cavity can normally carry out industrial operations such as PCB pressing, mechanical drilling, and copper plating.

[0090] From the processing flow of L4-5 layer, it can be seen that the cavity is not prefabricated by the traditional core plate window opening process, but by the thick core plate plus controlled deep milling process to prefabricate the cavity before pressing. Therefore, the outer shape of the cavity and the "support column", that is, the shape of the column can be changed arbitrarily in theory, and there is no need to worry about the "support column" falling off or shifting.

[0091] From the matching design of gasket 9 and cavity 8, it can be seen that after gasket 9 is combined, the overall volume of cavity 8 is almost the same, which is equivalent to almost squeezing out all the gas in cavity 8 and filling cavity 8. Therefore, when pressing at high temperature, a large amount of resin glue will not melt from the prepreg and flow into cavity 8 to cause uneven dielectric thickness and serious concavity above the cavity, which provides good conditions for making high-precision laser blind holes in L1-6 layers;

[0092] As long as the gasket 9 is not designed to be naturally obstructed, that is, the built-in gasket in the cavity 8 contains at least two separable and removable gaskets 9, the gasket 9 removal method is universal and effective.

[0093] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A circuit board with a special cavity structure, characterized in that: The invention comprises a core plate containing a cavity, wherein a column (32) is arranged in the middle of the cavity, and a U-shaped cavity is formed around the column (32).

2. A circuit board with a special cavity structure according to claim 1, characterized in that: The material of the column (32) is a copper-clad plate.

3. A circuit board with a special cavity structure according to claim 1, characterized in that: The core board containing the cavity comprises a top layer base copper (20), an insulating FR4 dielectric layer (21) and a bottom layer base copper (22) which are stacked in sequence.

4. A circuit board with a special cavity structure according to claim 3, characterized in that: The core board containing the cavity is an L4-5 layer core board, and also includes an L2-3 layer core board, wherein the L2-3 layer core board includes a top layer base copper (16), an insulating FR4 dielectric layer (17) and a bottom layer base copper (18) which are stacked in sequence, and a low-flow adhesive prepreg (19) is provided between the L2-3 layer core board and the L4-5 layer core board.

5. A circuit board with a special cavity structure according to claim 4, characterized in that: It also includes an L1 layer copper foil (14) and an L6 layer copper foil (24), wherein the L1 layer copper foil (14) is connected to the L2-3 layer core board via a common flow glue semi-cured sheet (15), and the L4-5 layer core board is connected to the L6 layer copper foil (24) via a common flow glue semi-cured sheet (23).

6. A circuit board with a special cavity structure according to claim 5, characterized in that: It also includes L2-5 layer core board mechanical through holes (1, 3), L1-6 layer mechanical through holes (2, 4), L1-2 layer laser blind holes (5, 6, 7) and L5-6 layer laser blind holes (10, 11, 13); The mechanical through holes (1, 3) of the L2-5 core plate pass through the L2-3 core plate and the L4-5 core plate; the distribution area is the outer general area and the column 32 area; The L1-6 layer mechanical through holes (2, 4) pass through the L1 layer copper foil (14), the L2-3 layer core board, the L4-5 layer core board and the L6 layer copper foil (24); the distribution area is the outer general area and the column 32 area; The L1-2 layer laser blind holes (5, 6, 7) pass through the L1 layer copper foil (14) and the top layer base copper (16) of the L2-3 layer core board; the distribution areas are the outer general area, the upper and lower areas of the cavity and the column 32 area; The L5-6 layer laser blind holes (10, 11, 13) pass through the L6 layer copper foil (24) and the bottom base copper (22) of the L4-5 layer core board; the distribution areas are the outer general area, the upper and lower areas of the cavity and the column 32 area.

7. A method for manufacturing a circuit board with a special cavity structure, characterized in that: The steps include: Prepare L4-5 layer core board: after the basic core board is made, control depth milling is performed to form a U-shaped cavity with a column 32; prepare a cavity built-in gasket 9: the shape of the cavity built-in gasket 9 is adapted to the U-shaped cavity 8, and the cavity built-in gasket 9 includes at least two separable and removable gaskets.

8. The method for manufacturing a circuit board with a special cavity structure according to claim 7, characterized in that: The preparation of the L4-5 layer core board specifically includes the following steps: Cutting, mechanical drilling, pre-treatment brushing, inner layer lamination, inner layer exposure, acid etching, leg film, controlled depth milling, X-ray drilling riveting holes, browning, to form the stacked plates to be pressed; The preparation of the cavity built-in gasket specifically comprises the following steps: Cutting, copper reduction, pre-treatment brushing, sticking high temperature resistant tape, mechanical drilling, milling gasket shape, quality inspection, forming the stacked plates to be pressed.

9. The method for manufacturing a circuit board with a special cavity structure according to claim 7, characterized in that: The following steps are also included: Prepare L2-3 core board; Preparing a low-flow prepreg (19); Preparation of common flow-cured prepregs (15, 23); preparing an outer copper foil; The first lamination forms the L2-5 layers; The second pressing forms the L1-6 layers.

10. The method for manufacturing a circuit board with a special cavity structure according to claim 7, characterized in that: The preparation of the L2-3 layer core board specifically includes the following steps: Cutting, pre-treatment brushing, inner layer lamination, inner layer exposure, acid etching, leg film, CCD drilling riveting holes, browning, forming the stacked boards to be pressed; The preparation of the low-flow prepreg (19) specifically comprises the following steps: Cut the material, drill the riveting holes, and form the stacked plates to be pressed together; The preparation of the common flow-resin prepreg (15, 23) and the preparation of the outer copper foil specifically include the following steps: cutting the material to form a laminate to be pressed; The first lamination to form the L2-5 layer specifically includes the following steps: Stacking, placing gaskets, pressing, X-ray drilling positioning holes, milling edges, horizontal debonding, mechanical drilling, brushing, chemical copper deposition, whole board electroplating, resin plugging, final curing, ceramic brushing, chemical copper deposition, whole board electroplating, pre-treatment brushing, inner layer circuit, inner layer AOI inspection, browning, to form a stacked board to be pressed; The second lamination to form the L1-6 layers specifically comprises the following steps: Stacking, lamination, X-ray drilling of positioning holes, milling, browning, laser drilling, mechanical drilling, brushing, horizontal debonding, horizontal PTH, flash plating, hole filling plating, outer layer circuit, outer layer AOI inspection, solder mask, gold plating, milling shape, gasket extraction, four-wire test, and final inspection.

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