Multi-level HDI rigid-flex board and manufacturing method thereof

Abstract

The invention discloses a multi-level HDI rigid-flex board and a manufacturing method thereof, the multi-level HDI rigid-flex board comprises a combination board body, the combination board body comprises a first board piece and a second board piece, and two sides of the inner wall of the first board piece are fixedly connected with two sides of the second board piece respectively; the first plate piece comprises a first green oil plate, a first Planting Copper plate, a first Copper plate, a first PP plate, a second Planting Copper plate, a second Copper plate, a second PP plate, a third Copper plate, a first Base FR plate, a third PP plate, a first base material copper Copper plate, a first Polyimide plate, a second base material copper Copper plate and a fourth PP plate. According to the preparation process, the problems of flatness of the plate surface and steps at the rigid-flex joint are solved; the reject ratio of finished products is reduced; the production efficiency is improved; a high-level plate surface and steps in a soft and hard combined area and a flat area are added, so that the reject ratio during production is reduced, and the production qualification rate and the working efficiency are improved; a standardized press-fit structure is made, production efficiency is improved, meanwhile, production operation is facilitated, and the rejection rate of the board is reduced.

Description

Technical Field

[0001] This invention relates to the field of rigid-flex PCB technology, specifically to a multi-layer HDI rigid-flex PCB and its manufacturing method. Background Technology

[0002] Rigid-flex boards combine rigid and flexible areas to adapt to complex internal spatial layouts, making them particularly suitable for devices requiring bending or folding, such as foldable phones and smartwatches. High-speed signal components, such as CPUs and DDR memory, are concentrated in the rigid areas, while low-speed signal or power components are placed in the flexible areas. This avoids high-frequency signals traversing the bending area, reducing signal interference. The flexible areas employ special wiring, such as routing perpendicular to the bending axis, and process designs, such as reinforcing plates and impedance matching corrections, to improve bending and impact resistance, making them suitable for high-reliability scenarios such as 5G communication equipment.

[0003] However, traditional rigid-flex PCBs have the following drawbacks:

[0004] When producing high-level rigid-flex PCBs, operators need to add another layer of structure on top of the second-level blind and buried vias, and add PP adhesive between the structures. If the PP adhesive is not added on the second-level layer, a step phenomenon will appear at the joint position of the rigid-flex PCB after lamination. This will increase the defect rate and may also cause poor bonding between the stepped pads and the dry film of the circuit during the production process, resulting in scrap. Summary of the Invention

[0005] The purpose of this invention is to provide a multi-layer HDI rigid-flex board and its manufacturing method, in order to solve the problem mentioned in the background art that when producing high-layer rigid-flex boards, operators need to add another layer of structure on top of the second-layer blind and buried vias, and add PP adhesive between the structures. When producing without adding PP adhesive on the second-layer layer, a stepped phenomenon appears at the joint position of the rigid-flex board after lamination. This not only increases the defect rate, but may also cause poor bonding between the stepped pads and the dry film of the circuit during the production process, resulting in scrap.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a multi-layer HDI rigid-flex board, comprising a board body, wherein the board body comprises a first board and a second board, the two sides of the inner wall of the first board are respectively fixedly connected to the two sides of the second board, and the first board comprises a first varnish board, a first plating copper board, a first copper board, a first PP board, a second plating copper board, a second copper board, a second PP board, a third copper board, a first base FR board, a third PP board, a first base copper copper board, a first polyimide board, a second base copper copper board, a fourth PP board, a second base FR board, a fourth copper board, a fifth PP board, a fifth copper board, a third plating copper board, a sixth PP board, a sixth copper board, a fourth plating copper board, and a second varnish board.

[0007] In a preferred embodiment of the present invention, the bottom end of the first green oil board is fixedly connected to the top end of the first Plating Copper board; the bottom end of the first Plating Copper board is fixedly connected to the top end of the first Copper board; the bottom end of the first Copper board is fixedly connected to the top end of the first PP board; the bottom end of the first PP board is fixedly connected to the top end of the second Plating Copper board; the bottom end of the second Plating Copper board is fixedly connected to the top end of the second Copper board; the bottom end of the second Copper board is fixedly connected to the top end of the second PP board; the bottom end of the second PP board is fixedly connected to the top end of the third Copper board; and the bottom end of the third Copper board is fixedly connected to the top end of the first Base FR board. The bottom end of the FR board is fixedly connected to the top end of the third PP board. The bottom end of the third PP board is fixedly connected to the top end of the first base copper copper board. The bottom end of the first base copper copper board is fixedly connected to the top end of the first polyimide board. The bottom end of the first polyimide board is fixedly connected to the top end of the second base copper copper board. The bottom end of the second base copper copper board is fixedly connected to the top end of the fourth PP board. The bottom end of the fourth PP board is fixedly connected to the top end of the second base FR board. The bottom end of the second base FR board is fixedly connected to the top end of the fourth copper board. The bottom end of the fourth copper board is fixedly connected to the top end of the fifth PP board. The bottom end of the fifth copper board is fixedly connected to the top end of the fifth copper board. The bottom end of the fifth copper board is fixedly connected to the top end of the third plating copper board. The bottom end of the third plating copper board is fixedly connected to the top end of the sixth PP board. The bottom end of the sixth PP board is fixedly connected to the top end of the sixth copper board. The bottom end of the sixth copper board is fixedly connected to the top end of the fourth plating copper board. The bottom of the copper board is fixedly connected to the top of the second green oil board.

[0008] As a preferred embodiment of the present invention, one end of the third PP plate, one end of the first substrate copper copper plate, one end of the first polyimide plate, one end of the second substrate copper copper plate, and one end of the fourth PP plate are all fixedly connected to the second plate.

[0009] As a preferred embodiment of the present invention, the surface of the second plating copper plate is provided with a first blind hole extending into the interior of the first copper plate, the surface of the third copper plate is provided with a second blind hole extending into the interior of the second copper plate, the surface of the sixth copper plate is provided with a third blind hole extending into the interior of the third plating copper plate, the surface of the fifth copper plate is provided with a fourth blind hole extending into the interior of the fourth copper plate, and the middle portion of the sixth copper plate is provided with a through hole extending into the interior of the first copper plate.

[0010] As a preferred embodiment of the present invention, the thickness of the first green oil board is 18-20 μm, the thickness of the first plating copper board is 25-30 μm, the thickness of the first copper board is 9 μm, the thickness of the first PP board is 85 μm, the thickness of the second plating copper board is 15-20 μm, the thickness of the second copper board is 9 μm, the thickness of the second PP board is 85 μm, the thickness of the third copper board is 18 μm, the thickness of the first base FR4 board is 50 μm, the thickness of the third PP board is 50 μm, the thickness of the first base copper copper copper board is 18 μm, the thickness of the first polyimide board is 100 μm, the thickness of the second base copper copper copper copper board is 18 μm, the thickness of the fourth PP board is 50 μm, and the thickness of the second base copper copper copper copper board is 18 μm. The thickness of the FR4 board is 50μm, the thickness of the fourth copper board is 18μm, the thickness of the fifth PP board is 85μm, the thickness of the fifth copper board is 9μm, the thickness of the third plating copper board is 15-20μm, the thickness of the sixth PP board is 85μm, the thickness of the sixth copper board is 9μm, the thickness of the fourth plating copper board is 25-30μm, and the thickness of the second green oil board is 18-20μm.

[0011] As a preferred embodiment of the present invention, the second plate includes a first cover plate, a third base copper coating plate, a second polyimide plate, a fourth base copper coating plate, and a second cover plate. The bottom end of the first cover plate is fixedly connected to the top end of the third base copper coating plate, the top end of the third base copper coating plate is fixedly connected to the top end of the second polyimide plate, the bottom end of the second polyimide plate is fixedly connected to the top end of the fourth base copper coating plate, and the bottom end of the fourth base copper coating plate is fixedly connected to the top end of the second cover plate.

[0012] As a preferred embodiment of the present invention, both ends of the first cover plate, both ends of the third base copper coating plate, both ends of the second polyimide plate, both ends of the fourth base copper coating plate, and both ends of the second cover plate are fixedly connected to the side of the first plate and the side of the rigid-flexible bonding member. The thickness of the first cover plate is 27.5 μm, the thickness of the third base copper coating plate is 16 μm, the thickness of the second polyimide plate is 100 μm, the thickness of the fourth base copper coating plate is 16 μm, and the thickness of the second cover plate is 27.5 μm.

[0013] In a preferred embodiment of the present invention, the second plate comprises a third cover plate, a fifth plating copper plate, a fifth base copper copper plate, a third polyimide plate, a sixth base copper copper plate, a sixth plating copper plate, and a fourth cover plate. The bottom end of the third cover plate is fixedly connected to the top end of the fifth plating copper plate, the bottom end of the fifth plating copper plate is fixedly connected to the top end of the fifth base copper copper plate, the bottom end of the fifth base copper copper plate is fixedly connected to the top end of the third polyimide plate, the bottom end of the third polyimide plate is fixedly connected to the top end of the sixth base copper copper plate, the bottom end of the sixth base copper copper plate is fixedly connected to the top end of the sixth plating copper plate, and the bottom end of the sixth plating copper plate is fixedly connected to the top end of the fourth cover plate.

[0014] As a preferred embodiment of the present invention, the two ends of the third cover plate, the two ends of the fifth plating copper plate, the two ends of the fifth base copper copper plate, the two ends of the third polyimide plate, the two ends of the sixth base copper copper plate, the two ends of the sixth plating copper plate, and the two ends of the fourth cover plate are all fixedly connected to the side opposite to the first plate and the side opposite to the second rigid-flexible bonding member. The thickness of the third cover plate is 38 μm, the thickness of the fifth plating copper plate is 8-12 μm, the thickness of the fifth base copper copper plate is 18 μm, the thickness of the third polyimide plate is 100 μm, the thickness of the sixth base copper copper plate is 18 μm, the thickness of the sixth plating copper plate is 8-12 μm, and the thickness of the fourth cover plate is 38 μm.

[0015] The fabrication method of a multi-layer HDI rigid-flex PCB includes the following steps:

[0016] Step 1: Assemble a three-tier structure: Make a board with a tier of two or more, apply PP adhesive to the tier two board and stack the boards, and then press the copper foil together to assemble a three-tier structure.

[0017] 1.1 Fabrication of the first-order board: Through holes are manufactured using mechanical drilling, and the inner walls of the through holes are plated with copper and filled with resin; the circuit pattern of the outermost layer of the eight-layer circuit board is etched to obtain the inner layer circuit board; a second conductive layer and a second prepreg are laminated on the upper surface of the inner layer circuit board, and a third prepreg and a third conductive layer are laminated on the lower surface of the inner layer circuit board; a second blind via and a third blind via are respectively formed on the second and third conductive layers using laser drilling; a copper layer is coated on the inner walls of the second and third blind vias, and the circuit patterns of the second and third conductive layers are etched to obtain the first-order HDI board;

[0018] 1.2 Fabrication of the second-order board: A first conductive layer and a first prepreg are laminated onto the upper surface of the first-order HDI board, and a fourth prepreg and a fourth conductive layer are laminated onto its lower surface. A first blind via and a fourth blind via are formed in the first and fourth conductive layers using laser drilling. A copper layer is coated on the inner wall of the first and fourth blind vias, and the circuit patterns of the first and fourth conductive layers are etched to obtain the second-order HDI board. Solder resist ink is coated on the outer side of the first and fourth conductive layers.

[0019] Step 2, Panel Pressing: Press the three-tier structure onto two other two-tier plates to ensure that the three-tier structure has a flat surface and that there are no steps in the soft-hard bonding area.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1. This manufacturing process solves the problems of flatness of the board surface and step at the junction of soft and hard surfaces, reducing the defect rate of finished products and improving production efficiency;

[0022] 2. Increase the steps in the high-level board surface and the soft-hard combination area to reduce the defect rate during production, improve the production qualification rate, and increase work efficiency.

[0023] 3. By creating a standardized pressing structure, production efficiency is increased, production operations are facilitated, and the scrap rate of boards is reduced. Attached Figure Description

[0024] Figure 1 This is a perspective view of the present invention;

[0025] Figure 2 This is a cross-sectional view of the first plate of the present invention;

[0026] Figure 3 This is a first cross-sectional view of the second plate of the present invention;

[0027] Figure 4 This is a second cross-sectional view of the second plate of the present invention;

[0028] Figure 5 This is a flowchart of the present invention;

[0029] Figure 6 This is a structural diagram of Embodiment 1 of the present invention;

[0030] Figure 7 This is a structural diagram of Embodiment 2 of the present invention;

[0031] Figure 8 This is a structural diagram of Embodiment 3 of the present invention.

[0032] In the diagram: 1. Composite board body; 2. First board component; 201. First green oil board; 202. First plating copper board; 203. First copper board; 204. First PP board; 205. Second plating copper board; 206. Second copper board; 207. Second PP board; 208. Third copper board; 209. First base FR4 board; 210. Third PP board; 211. First base copper copper copper board; 212. First polyimide board; 213. Second base copper copper copper board; 214. Fourth PP board; 215. Second base FR4 board; 216. Fourth copper board; 217. Fifth PP board; 218. Fifth copper board; 219. Third plating copper board; 220. Sixth PP board; 221. Sixth copper board; 222. Fourth plating copper copper board; Copper board; 223, Second green oil board; 224, First blind hole; 225, Second blind hole; 226, Through hole; 227, Third blind hole; 228, Fourth blind hole; 3, Second board; 31, First cover board; 32, Third substrate copper copper copper copper board; 33, Second polyimide board; 34, Fourth substrate copper copper copper copper board; 35, Second cover board; 301, Third cover board; 302, Fifth plating copper copper board; 303, Fifth substrate copper copper copper copper board; 304, Third polyimide board; 305, Sixth substrate copper copper copper copper board; 306, Sixth plating copper copper board; 307, Fourth cover board. Detailed Implementation

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0034] Please see Figure 1-8This invention provides a multi-layer HDI rigid-flex board, including a board body 1. The board body 1 includes a first board 2 and a second board 3. The two sides of the inner wall of the first board 2 are fixedly connected to the two sides of the second board 3. The first board 2 includes a first green oil board 201, a first plating copper board 202, a first copper board 203, a first PP board 204, a second plating copper board 205, a second copper board 206, a second PP board 207, a third copper board 208, a first base FR4 board 209, a third PP board 210, a first base copper copper copper board 211, a first polyimide board 212, a second base copper copper copper copper board 213, a fourth PP board 214, a second base FR4 board 215, a fourth copper board 216, a fifth PP board 217, a fifth copper copper board 218, and a third plating copper copper copper board 219. Copper board 219, sixth PP board 220, sixth Copper board 221, fourth Plating Copper board 222, and second green oil board 223.

[0035] The bottom end of the first green oil board 201 is fixedly connected to the top end of the first plating copper board 202; the bottom end of the first plating copper board 202 is fixedly connected to the top end of the first copper board 203; the bottom end of the first copper board 203 is fixedly connected to the top end of the first PP board 204; the bottom end of the first PP board 204 is fixedly connected to the top end of the second plating copper board 205; the bottom end of the second plating copper board 205 is fixedly connected to the top end of the second copper board 206; the bottom end of the second copper board 206 is fixedly connected to the top end of the second PP board 207; the bottom end of the second PP board 207 is fixedly connected to the top end of the third copper board 208; and the bottom end of the third copper board 208 is fixedly connected to the top end of the first base FR4 board 209. The bottom end of FR4 board 209 is fixedly connected to the top end of third PP board 210. The bottom end of third PP board 210 is fixedly connected to the top end of first substrate copper copper copper board 211. The bottom end of first substrate copper copper copper board 211 is fixedly connected to the top end of first polyimide board 212. The bottom end of first polyimide board 212 is fixedly connected to the top end of second substrate copper copper copper board 213. The bottom end of second substrate copper copper copper board 213 is fixedly connected to the top end of fourth PP board 214. The bottom end of fourth PP board 214 is fixedly connected to the top end of second base FR4 board 215. The bottom end of second base FR4 board 215 is fixedly connected to the top end of fourth copper board 216. The bottom end of fourth copper board 216 is fixedly connected to the top end of fifth PP board 217. The bottom end of fifth PP board 217 is fixedly connected to the top end of fifth copper board 218. The bottom end of fifth copper board 218 is fixedly connected to the top end of third plating copper board 219. The bottom end of the Copper board 219 is fixedly connected to the top end of the sixth PP board 220, the bottom end of the sixth PP board 220 is fixedly connected to the top end of the sixth Copper board 221, the bottom end of the sixth Copper board 221 is fixedly connected to the top end of the fourth Plating Copper board 222, and the bottom end of the fourth Plating Copper board 222 is fixedly connected to the top end of the second green oil board 223.

[0036] One end of the third PP plate 210, one end of the first substrate copper copper plate 211, one end of the first polyimide plate 212, one end of the second substrate copper copper plate 213, and one end of the fourth PP plate 214 are all fixedly connected to the second plate 3.

[0037] The surface of the second plating copper plate 205 has a first blind hole 224 extending into the interior of the first copper plate 203; the surface of the third copper plate 208 has a second blind hole 225 extending into the interior of the second copper plate 206; the surface of the sixth copper plate 221 has a third blind hole 227 extending into the interior of the third plating copper plate 219; the surface of the fifth copper plate 218 has a fourth blind hole 228 extending into the interior of the fourth copper plate 216; and the middle part of the sixth copper plate 221 has a through hole 226 extending into the interior of the first copper plate 203.

[0038] The thickness of the first green oil board 201 is 18-20μm, the thickness of the first plating copper board 202 is 25-30μm, the thickness of the first copper board 203 is 9μm, the thickness of the first PP board 204 is 85μm, the thickness of the second plating copper board 205 is 15-20μm, the thickness of the second copper board 206 is 9μm, the thickness of the second PP board 207 is 85μm, the thickness of the third copper board 208 is 18μm, the thickness of the first base FR4 board 209 is 50μm, the thickness of the third PP board 210 is 50μm, the thickness of the first base copper copper copper board 211 is 18μm, the thickness of the first polyimide board 212 is 100μm, the thickness of the second base copper copper copper board 213 is 18μm, the thickness of the fourth PP board 214 is 50μm, and the thickness of the second base copper copper copper board 213 is 18μm. The thickness of FR4 board 215 is 50μm, the thickness of the fourth Copper board 216 is 18μm, the thickness of the fifth PP board 217 is 85μm, the thickness of the fifth Copper board 218 is 9μm, the thickness of the third Plating Copper board 219 is 15-20μm, the thickness of the sixth PP board 220 is 85μm, the thickness of the sixth Copper board 221 is 9μm, the thickness of the fourth Plating Copper board 222 is 25-30μm, and the thickness of the second green oil board 223 is 18-20μm.

[0039] The second plate 3 includes a first cover plate 31, a third base copper copper plate 32, a second polyimide plate 33, a fourth base copper copper plate 34, and a second cover plate 35. The bottom end of the first cover plate 31 is fixedly connected to the top end of the third base copper copper plate 32, the top end of the third base copper copper plate 32 is fixedly connected to the top end of the second polyimide plate 33, the bottom end of the second polyimide plate 33 is fixedly connected to the top end of the fourth base copper copper plate 34, and the bottom end of the fourth base copper copper plate 34 is fixedly connected to the top end of the second cover plate 35.

[0040] Both ends of the first cover plate 31, both ends of the third base copper copper plate 32, both ends of the second polyimide plate 33, both ends of the fourth base copper copper plate 34, and both ends of the second cover plate 35 are fixedly connected to the side of the first plate 2 and the side of the second rigid-soft bonding member 4. The thickness of the first cover plate 31 is 27.5 μm, the thickness of the third base copper copper plate 32 is 16 μm, the thickness of the second polyimide plate 33 is 100 μm, the thickness of the fourth base copper copper plate 34 is 16 μm, and the thickness of the second cover plate 35 is 27.5 μm.

[0041] The second component 3 includes a third cover plate 301, a fifth plating copper plate 302, a fifth base copper copper plate 303, a third polyimide plate 304, a sixth base copper copper plate 305, a sixth plating copper plate 306, and a fourth cover plate 307. The bottom end of the third cover plate 301 is fixedly connected to the top end of the fifth plating copper plate 302. The bottom end of the fifth plating copper plate 302 is fixedly connected to the top end of the fifth base copper copper plate 303. The bottom end of the fifth base copper copper plate 303 is fixedly connected to the top end of the third polyimide plate 304. The bottom end of the third polyimide plate 304 is fixedly connected to the top end of the sixth base copper copper plate 305. The bottom end of the sixth base copper copper plate 305 is fixedly connected to the top end of the sixth plating copper plate 306. The bottom end of the sixth plating copper plate 306 is fixedly connected to the top end of the fourth cover plate 307.

[0042] Both ends of the third cover plate 301, both ends of the fifth plating copper plate 302, both ends of the fifth base copper copper plate 303, both ends of the third polyimide plate 304, both ends of the sixth base copper copper plate 305, both ends of the sixth plating copper plate 306, and both ends of the fourth cover plate 307 are fixedly connected to the side directly opposite the first plate 2 and the side directly opposite the second rigid-soft bonding member 4. The thickness of the third cover plate 301 is 38μm, the thickness of the fifth plating copper plate 302 is 8-12μm, the thickness of the fifth base copper copper plate 303 is 18μm, the thickness of the third polyimide plate 304 is 100μm, the thickness of the sixth base copper copper plate 305 is 18μm, the thickness of the sixth plating copper plate 306 is 8-12μm, and the thickness of the fourth cover plate 307 is 38μm.

[0043] The fabrication method of a multi-layer HDI rigid-flex PCB includes the following steps:

[0044] Step 1: Assemble a three-tier structure: Make a board with a tier of two or more, apply PP adhesive to the tier two board and stack the boards, and then press the copper foil together to assemble a three-tier structure.

[0045] 1.1 Fabrication of the first-order board: Through-holes 226 are manufactured by mechanical drilling, and the inner walls of the through-holes 226 are plated with copper and filled with resin; the circuit pattern of the outermost layer of the eight-layer circuit board is etched to obtain the inner layer circuit board; a second conductive layer and a second prepreg are laminated on the upper surface of the inner layer circuit board, and a third prepreg and a third conductive layer are laminated on the lower surface of the inner layer circuit board; a second blind via 225 and a third blind via 227 are respectively formed on the second and third conductive layers by laser drilling; a copper layer is coated on the inner walls of the second blind via 225 and the third blind via 227, and the circuit patterns of the second and third conductive layers are etched to obtain the first-order HDI board;

[0046] 1.2 Fabrication of the second-order board: A first conductive layer and a first prepreg are laminated onto the upper surface of the first-order HDI board, and a fourth prepreg and a fourth conductive layer are laminated onto its lower surface. A first blind via 224 and a fourth blind via 228 are formed in the first and fourth conductive layers using laser drilling. A copper layer is coated on the inner wall of the first blind via 224 and the fourth blind via 228. The circuit patterns of the first and fourth conductive layers are etched to obtain the second-order HDI board. Solder resist ink is coated on the outer side of the first and fourth conductive layers.

[0047] Step 2, Panel Pressing: Press the three-tier structure onto two other two-tier plates to ensure that the three-tier structure has a flat surface and that there are no steps in the soft-hard bonding area.

[0048] Example 1:

[0049] In this invention, the prepreg is model 1067 with a glue content of 86%. This does not guarantee the thickness of the semi-flexible region, but the high glue content of the prepreg can compensate for insufficient glue filling during lamination, preventing copper leakage in the semi-flexible region. Furthermore, it satisfies the breakdown resistance of the inner conductive layer to prevent short circuits caused by electron conduction along the glass fiber during PCB use. The thickness of the first green solder mask 201 is 18-20 μm, the thickness of the first plating copper board 202 is 25-30 μm, the thickness of the first copper board 203 is 9 μm, the thickness of the first PP board 204 is 85 μm, the thickness of the second plating copper board 205 is 15-20 μm, the thickness of the second copper board 206 is 9 μm, the thickness of the second PP board 207 is 85 μm, the thickness of the third copper board 208 is 18 μm, and the thickness of the first base... The thickness of the FR4 board 209 is 50μm, the thickness of the third PP board 210 is 50μm, the thickness of the first substrate copper copper copper board 211 is 18μm, the thickness of the first polyimide board 212 is 100μm, the thickness of the second substrate copper copper copper copper board 213 is 18μm, the thickness of the fourth PP board 214 is 50μm, the thickness of the second Base FR4 board 215 is 50μm, the thickness of the fourth copper copper board 216 is 18μm, the thickness of the fifth PP board 217 is 85μm, the thickness of the fifth copper copper board 218 is 9μm, the thickness of the third plating copper board 219 is 15-20μm, the thickness of the sixth PP board 220 is 85μm, the thickness of the sixth copper copper board 221 is 9μm, and the thickness of the fourth plating copper copper board 219 is 15-20μm. The thickness of the copper board 222 is 25-30μm, the thickness of the second green oil board 223 is 18-20μm, the thickness of the first cover board 31 is 27.5μm, the thickness of the third substrate copper copper copper board 32 is 16μm, the thickness of the second polyimide board 33 is 100μm, the thickness of the fourth substrate copper copper copper copper board 34 is 16μm, and the thickness of the second cover board 35 is 27.5μm. Through-holes 226 are manufactured using mechanical drilling, and the inner walls of the through-holes 226 are copper-plated and etched with resin plugs to create the outermost circuit pattern of the eight-layer circuit board, resulting in the inner layer circuit board. A conductive layer and a prepreg are laminated onto the upper surface of the inner layer circuit board, and a prepreg and a conductive layer are laminated onto the lower surface of the inner layer circuit board. Blind holes are drilled on the corresponding conductive layers using laser drilling, and a copper layer is coated on the inner walls of the blind holes. The circuit pattern of the conductive layer is then etched to obtain the second-order HDI board.

[0050] Example 2:

[0051] In this invention, unlike Example 1, an eight-layer three-tier HDI board is prepared. The two-tier HDI board serves as the base, providing mechanical support. A prepreg (PP) material is used to bond the two-tier HDI board to the copper foil; this prepreg needs to be cut to the appropriate size. The copper foil is used for the outer layer circuitry and must have good conductivity. After cutting, the PP material is placed in designated positions on the two-tier board, such as between the core board and the copper foil. Heating softens and flows the resin in the PP, filling the gaps between the core boards. The two-tier HDI board, PP material, and copper foil are stacked sequentially according to design requirements, using hot-melt or riveting methods for precise positioning to ensure alignment of each layer. The stacked components are then placed in a vacuum hot press, where the PP resin is cured under high temperature and pressure, achieving a strong bond between the core board and the copper foil. After the resin cools, the bonding of each layer is checked to ensure there are no misalignments or gaps. Residual photosensitive film is cleaned, and outer layer etching and electroplating are performed to finally form a complete three-tier PCB structure. The specific composition of the board is: solder mask (18-20µm), plating copper (25-30µm), and copper (L1). PP1, Plating Copper (15-20um), Copper (L2), PP2, Plating Copper (15-20um), Copper (L3), Base FR4, PP3, Base Copper (L4), Polyimide (PI), Base Copper (L5), PP4, Base FR4, Copper (L6), Plating Copper (15-20um), PP5, Copper (L7), Plating Copper (15-20um), PP6, Copper (L8), Plating Copper (25-30um) and Green Oil (18-20um).

[0052] Example 3:

[0053] In this invention, unlike Example 1, an eight-layer, four-stage HDI board is prepared. The thickness of the third cover board 301 is 38 μm, the thickness of the fifth plating copper board 302 is 8-12 μm, the thickness of the fifth substrate copper copper copper board 303 is 18 μm, the thickness of the third polyimide board 304 is 100 μm, the thickness of the sixth substrate copper copper copper copper board 305 is 18 μm, the thickness of the sixth plating copper board 306 is 8-12 μm, and the thickness of the fourth cover board 307 is 38 μm. First, under the protection of photoresist, the inner layer circuit pattern is fabricated on the copper foil through exposure, development, and other processes. This step requires a high-precision photolithography machine and a fine photolithography process to ensure the accuracy and precision of the circuit. Typically, the line width and line spacing can reach 50 μm. Even finer, the copper foil not protected by photoresist is etched away using a chemical etching solution to form the required inner layer circuitry. The fabricated inner layer core boards and prepregs are stacked in a specific order and laminated under high temperature and pressure. During lamination, the prepreg melts and flows, bonding the core boards together while maintaining the integrity of the circuitry. To achieve electrical connections between the layers, precise vias need to be drilled on the laminated circuit board. This is typically done using a high-speed drilling machine with a drill bit, and the drilling diameter is between 0.2mm and 1.0mm. The specific composition of the board is: solder mask (18-20um), plating copper (25-30um), copper (L1), PP1, plating copper (15-20um), copper (L2), PP2, plating copper (15-20um), copper (L3), base FR4, PP3, plating copper (8-12um), substrate copper (L4), and polyimide. (PI), substrate copper (L5), plating copper (8-12um), PP4, Base FR4, copper (L6), plating copper (15-20um), PP5, copper (L7), plating copper (15-20um), PP6, copper (L8), plating copper (25-30um) and green oil (18-20um).

[0054] 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 multi-layer HDI rigid-flex board, comprising a board body (1), characterized in that: The combined plate body (1) includes a first plate (2) and a second plate (3). The two sides of the inner wall of the first plate (2) are respectively fixedly connected to the two sides of the second plate (3). The first plate (2) includes a first green oil plate (201), a first plating copper plate (202), a first copper plate (203), a first PP plate (204), a second plating copper plate (205), a second copper plate (206), a second PP plate (207), a third copper plate (208), and a first base plate. FR4 board (209), third PP board (210), first substrate copper Copper board (211), first Polyimide board (212), second substrate copper Copper board (213), fourth PP board (214), second BaseFR4 board (215), fourth Copper board (216), fifth PP board (217), fifth Copper board (218), third Plating Copper board (219), sixth PP board (220), sixth Copper board (221), fourth Plating Copper board (222), and second green oil board (223).

2. The multi-layer HDI rigid-flex board according to claim 1, characterized in that: The bottom end of the first green oil board (201) is fixedly connected to the top end of the first plating copper board (202), the bottom end of the first plating copper board (202) is fixedly connected to the top end of the first copper board (203), the bottom end of the first copper board (203) is fixedly connected to the top end of the first PP board (204), the bottom end of the first PP board (204) is fixedly connected to the top end of the second plating copper board (205), the bottom end of the second plating copper board (205) is fixedly connected to the top end of the second copper board (206), the bottom end of the second copper board (206) is fixedly connected to the top end of the second PP board (207), the bottom end of the second PP board (207) is fixedly connected to the top end of the third copper board (208), and the bottom end of the third copper board (208) is fixedly connected to the top end of the first BaseFR4 board (209). The bottom end of the FR4 board (209) is fixedly connected to the top end of the third PP board (210), the bottom end of the third PP board (210) is fixedly connected to the top end of the first substrate copper copper board (211), the bottom end of the first substrate copper copper board (211) is fixedly connected to the top end of the first polyimide board (212), the bottom end of the first polyimide board (212) is fixedly connected to the top end of the second substrate copper copper board (213), the bottom end of the second substrate copper copper board (213) is fixedly connected to the top end of the fourth PP board (214), the bottom end of the fourth PP board (214) is fixedly connected to the top end of the second Base FR4 board (215), and the second Base The bottom end of the FR4 board (215) is fixedly connected to the top end of the fourth Copper board (216), the bottom end of the fourth Copper board (216) is fixedly connected to the top end of the fifth PP board (217), the bottom end of the fifth PP board (217) is fixedly connected to the top end of the fifth Copper board (218), the bottom end of the fifth Copper board (218) is fixedly connected to the top end of the third Plating Copper board (219), the bottom end of the third Plating Copper board (219) is fixedly connected to the top end of the sixth PP board (220), the bottom end of the sixth PP board (220) is fixedly connected to the top end of the sixth Copper board (221), the bottom end of the sixth Copper board (221) is fixedly connected to the top end of the fourth Plating Copper board (222), and the bottom end of the fourth Plating Copper board (222) is fixedly connected to the top end of the second green oil board (223).

3. The multi-layer HDI rigid-flex board according to claim 1, characterized in that: One end of the third PP plate (210), one end of the first substrate copper copper plate (211), one end of the first polyimide plate (212), one end of the second substrate copper copper plate (213), and one end of the fourth PP plate (214) are all fixedly connected to the second plate (3).

4. The multi-layer HDI rigid-flex board according to claim 1, characterized in that: The surface of the second Plating Copper plate (205) is provided with a first blind hole (224) extending into the interior of the first Copper plate (203), the surface of the third Copper plate (208) is provided with a second blind hole (225) extending into the interior of the second Copper plate (206), the surface of the sixth Copper plate (221) is provided with a third blind hole (227) extending into the interior of the third Plating Copper plate (219), the surface of the fifth Copper plate (218) is provided with a fourth blind hole (228) extending into the interior of the fourth Copper plate (216), and the middle part of the sixth Copper plate (221) is provided with a through hole (226) extending into the interior of the first Copper plate (203).

5. The multi-layer HDI rigid-flex board according to claim 1, characterized in that: The thickness of the first green oil board (201) is 18-20 μm, the thickness of the first plating copper board (202) is 25-30 μm, the thickness of the first copper board (203) is 9 μm, the thickness of the first PP board (204) is 85 μm, the thickness of the second plating copper board (205) is 15-20 μm, the thickness of the second copper board (206) is 9 μm, the thickness of the second PP board (207) is 85 μm, the thickness of the third copper board (208) is 18 μm, and the thickness of the first base... The thickness of the FR4 board (209) is 50 μm, the thickness of the third PP board (210) is 50 μm, the thickness of the first substrate copper copper copper board (211) is 18 μm, the thickness of the first polyimide board (212) is 100 μm, the thickness of the second substrate copper copper copper board (213) is 18 μm, the thickness of the fourth PP board (214) is 50 μm, the thickness of the second Base FR4 board (215) is 50 μm, the thickness of the fourth copper copper board (216) is 18 μm, the thickness of the fifth PP board (217) is 85 μm, the thickness of the fifth copper copper board (218) is 9 μm, the thickness of the third plating copper board (219) is 15-20 μm, the thickness of the sixth PP board (220) is 85 μm, the thickness of the sixth copper copper board (221) is 9 μm, and the thickness of the fourth plating copper copper board (219) is 15-20 μm. The thickness of the Copper board (222) is 25-30 μm, and the thickness of the second green oil board (223) is 18-20 μm.

6. The multi-layer HDI rigid-flex board according to claim 1, characterized in that: The second plate (3) includes a first cover plate (31), a third base copper copper plate (32), a second polyimide plate (33), a fourth base copper copper plate (34), and a second cover plate (35). The bottom end of the first cover plate (31) is fixedly connected to the top end of the third base copper copper plate (32). The top end of the third base copper copper plate (32) is fixedly connected to the top end of the second polyimide plate (33). The bottom end of the second polyimide plate (33) is fixedly connected to the top end of the fourth base copper copper plate (34). The bottom end of the fourth base copper copper plate (34) is fixedly connected to the top end of the second cover plate (35).

7. The multi-layer HDI rigid-flex board according to claim 6, characterized in that: Both ends of the first COVER plate (31), both ends of the third base copper Copper plate (32), both ends of the second Polyimide plate (33), both ends of the fourth base copper Copper plate (34), and both ends of the second COVER plate (35) are fixedly connected to the side opposite to the first plate (2) and the side opposite to the second rigid-soft bonding member (4). The thickness of the first COVER plate (31) is 27.5 μm, the thickness of the third base copper Copper plate (32) is 16 μm, the thickness of the second Polyimide plate (33) is 100 μm, the thickness of the fourth base copper Copper plate (34) is 16 μm, and the thickness of the second COVER plate (35) is 27.5 μm.

8. The multi-layer HDI rigid-flex board according to claim 1, characterized in that: The second plate (3) includes a third cover plate (301), a fifth plating copper plate (302), a fifth base copper copper plate (303), a third polyimide plate (304), a sixth base copper copper plate (305), a sixth plating copper plate (306), and a fourth cover plate (307). The bottom end of the third cover plate (301) is fixedly connected to the top end of the fifth plating copper plate (302). The bottom end of the fifth plating copper plate (302) is fixedly connected to the top end of the fifth base copper copper plate (303). The bottom end of the fifth base copper copper plate (303) is fixedly connected to the top end of the third polyimide plate (304). The bottom end of the third polyimide plate (304) is fixedly connected to the top end of the sixth base copper copper plate (305). The bottom end of the sixth base copper copper plate (305) is fixedly connected to the top end of the sixth plating copper plate (306). The bottom end of the Copper board (306) is fixedly connected to the top end of the fourth COVER board (307).

9. The multi-layer HDI rigid-flex board according to claim 8, characterized in that: The two ends of the third cover plate (301), the two ends of the fifth plating copper plate (302), the two ends of the fifth base copper copper plate (303), the two ends of the third polyimide plate (304), the two ends of the sixth base copper copper plate (305), the two ends of the sixth plating copper plate (306), and the two ends of the fourth cover plate (307) are all fixedly connected to the side opposite to the first plate (2) and the side opposite to the second rigid-soft bonding member (4). The thickness of the third cover plate (301) is 38μm, the thickness of the fifth plating copper plate (302) is 8-12μm, the thickness of the fifth base copper copper plate (303) is 18μm, the thickness of the third polyimide plate (304) is 100μm, the thickness of the sixth base copper copper plate (305) is 18μm, and the thickness of the sixth plating copper plate (307) is... The thickness of the copper plate (306) is 8-12 μm, and the thickness of the fourth cover plate (307) is 38 μm.

10. The method for manufacturing a multi-layer HDI rigid-flex board according to any one of claims 1-9, characterized in that, Includes the following steps: Step 1: Assemble a three-tier structure: Make a board with a tier of two or more, apply PP adhesive to the tier two board and stack the boards, and then press the copper foil together to assemble a three-tier structure. 1.1 Fabrication of the first-order board: Through holes (226) are manufactured by mechanical drilling, and the inner walls of the through holes (226) are plated with copper and filled with resin; the circuit pattern of the outermost layer of the eight-layer circuit board is etched to obtain the inner layer circuit board; the second conductive layer and the second prepreg are laminated on the upper surface of the inner layer circuit board, and the third prepreg and the third conductive layer are laminated on the lower surface of the inner layer circuit board; the second blind hole (225) and the third blind hole (227) are respectively opened on the second conductive layer and the third conductive layer by laser drilling; the inner walls of the second blind hole (225) and the third blind hole (227) are coated with copper, and the circuit patterns of the second conductive layer and the third conductive layer are etched to obtain the first-order HDI board; 1.2 Fabrication of a second-order HDI board: A first conductive layer and a first prepreg are laminated onto the upper surface of a first-order HDI board, and a fourth prepreg and a fourth conductive layer are laminated onto its lower surface. A first blind via (224) and a fourth blind via (228) are formed in the first and fourth conductive layers using laser drilling. A copper layer is coated on the inner wall of the first blind via (224) and the fourth blind via (228). The circuit patterns of the first and fourth conductive layers are etched to obtain a second-order HDI board. Solder resist ink is coated on the outer side of the first and fourth conductive layers. Step 2, Panel Pressing: Press the three-tier structure onto two other two-tier plates to ensure that the three-tier structure has a flat surface and that there are no steps in the soft-hard bonding area.

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