A kind of HDI soft and hard board's step windowing laser slot processing structure

Abstract

The application relates to the technical field of HDI soft and hard boards, in particular to a hierarchical windowing laser slot processing structure of an HDI soft and hard board, which comprises an outer copper foil, a PP1 prepreg, a deslagging area and a filling assembly. The PP1 prepreg is arranged at the bonding position on the outer copper foil. The deslagging area is arranged at the assembling position on the PP1 prepreg. The outer copper foil and the PP1 prepreg are fixed at the bonding position on the filling assembly. In the application, the PP2 reverse-pasted cover film is provided with a positioning alignment mark film, so that the CCD precise optical alignment positioning can be realized before the laminated plate is pressed, the PP2 reverse-pasted cover film is effectively prevented from slipping and deviating during the high-temperature pressing process, the relative position precision of the PP2 reverse-pasted cover film and the 0.15mm glue-blocking groove of the PP2 soft and hard combination area is ensured, the glue-blocking isolation interface of the PP2 reverse-pasted cover film is ensured to be complete and without dislocation and gap, the PP2 resin is stably blocked from climbing to the soft area, and the two-stage glue-blocking groove structure is cooperated to improve the glue overflow blocking capability of the soft and hard combination area.

Description

Technical Field

[0001] This invention relates to the technical field of HDI rigid-flex PCBs, specifically a stepped windowed laser groove processing structure for HDI rigid-flex PCBs. Background Technology

[0002] HDI (Hardware-Definition) rigid-flex boards combine the structural assembly capabilities of rigid areas with the bending performance of flexible areas, making them widely used in the internal interconnection of high-end electronic devices. They often employ stepped windowed laser grooves to form stepped blind cavities in the rigid areas for component embedding. The inner copper layer acts as a stop-pad to control the laser depth. Through innovative processes such as laser drilling and layer addition, HDI circuit boards achieve more refined circuit layouts and higher signal integrity, leading to the combination of rigid-flex boards and HDI products.

[0003] Existing HDI rigid-flex PCBs require prepregs to be windowed in the soft areas. After windowing, a depression is formed in the soft area, which can easily create tiny gaps due to mechanical action. During lamination, the boards are prone to misalignment, and chemicals can seep into the soft area through the gaps, corroding the PI substrate and the flexible circuit board. Summary of the Invention

[0004] The purpose of this invention is to provide a stepped windowed laser groove processing structure for HDI rigid-flex PCBs to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A stepped, windowed laser groove processing structure for HDI rigid-flex PCBs includes an outer copper foil, a PP1 prepreg, a descaling area, and a filling assembly. The PP1 prepreg is attached to the bonding areas of the outer copper foil, and a descaling area is provided at the assembly areas of the PP1 prepreg. The outer copper foil and the PP1 prepreg are fixed to the bonding areas of the filling assembly. The structure also includes... A tongue-and-groove interlocking assembly is mounted on the outer copper foil; An anti-overflow component is disposed on the outer copper foil; The PP1 prepreg has an L2 inner copper layer at the bonding point, and a PP2 No-flow prepreg is bonded to the bottom of the L2 inner copper layer. The PP2 No-flow prepreg is connected to a reverse-adhesive cover film facing the bonding point, and a 0.15mm adhesive resistance groove for the PP2 soft-hard bonding area is opened on the PP2 No-flow prepreg.

[0006] The HDI rigid-flex board with stepped windowed laser groove processing structure as described above: an L3 inner copper layer is provided at the lower bonding area of ​​the 0.15mm adhesive resistance groove in the PP2 rigid-flex bonding area, and a PP3 No-flow prepreg is bonded at the lower connection of the L3 inner copper layer.

[0007] The HDI rigid-flex PCB with stepped windowed laser groove processing structure as described above: the bottom end of the PP3 No-flow prepreg is bonded with a PP5 ordinary flow prepreg, and the inner side of the PP1 prepreg is provided with a stepped laser groove.

[0008] The HDI rigid-flex board stepped windowed laser groove processing structure as described above: the concave-convex interlocking component includes micro-concaves bonded to the stepped laser groove, and micro-convexes bonded to the inner side of the micro-concaves.

[0009] The HDI rigid-flex board stepped window laser groove processing structure as described above: stepped window laser grooves are provided on both sides of the stepped laser groove, and a narrow trapezoidal groove is opened at the bottom of the stepped window laser groove.

[0010] The HDI rigid-flex board with stepped windowed laser groove processing structure as described above: the anti-overflow component includes a PP2 reverse-adhesive cover film bonded to the 0.15mm adhesive-resistant groove of the PP2 rigid-flex board bonding area, and a positioning and alignment mark film is connected to the adhesive joint of the PP2 reverse-adhesive cover film.

[0011] The HDI rigid-flex board with stepped windowed laser groove processing structure as described above: The anti-overflow component also includes a 0.15mm adhesive resistance groove for the PP3 rigid-flex bonding area opened on the inner copper layer of L3.

[0012] Compared with the prior art, the beneficial effects of the present invention are: the resin flow rate is small during the pressing of PP2No-flow prepreg, reducing the risk of glue overflow from the source; a reverse cover film is bonded to the surface of the PP2No-flow prepreg facing the inner copper layer of L3, forming the first physical barrier layer to prevent resin from creeping into the soft area, and at the same time, the edge alignment marks can prevent pressing slippage; a 0.15mm glue-blocking groove is opened at the soft and hard bonding area of ​​the PP2No-flow prepreg, which cuts through both the PP2No-flow prepreg and the reverse cover film to contain the glue overflow during pressing, prevent the glue from flowing into the soft area, and facilitate the discharge of laser residue.

[0013] The PP2 reverse-adhesive cover film, by setting a positioning and alignment mark film, can achieve precise CCD optical alignment and positioning before lamination, effectively preventing slippage and displacement of the PP2 reverse-adhesive cover film during high-temperature lamination. This ensures the relative positional accuracy of the PP2 reverse-adhesive cover film and the 0.15mm adhesive barrier groove in the PP2 soft-hard bonding area, ensuring the integrity of the adhesive barrier interface of the PP2 reverse-adhesive cover film without misalignment or gaps, and stably blocking the creep of PP2 resin into the soft area. Together with the two-stage adhesive barrier groove structure, it enhances the adhesive overflow barrier capability of the soft-hard bonding area.

[0014] When the amount of adhesive overflow during lamination is too large, the upper 0.15mm adhesive barrier groove and the outer adhesive overflow buffer zone are already saturated. After a small amount of adhesive leaks downwards and crosses the PP2 structure, the 0.15mm adhesive barrier groove in the PP3 soft-hard bonding area will again contain and intercept the leaked resin, further preventing the adhesive from continuing to flow into the soft area and avoiding adhesive overflow contamination of the FPC soft area circuit and pads. Attached Figure Description

[0015] Figure 1 This is a three-dimensional structural diagram of the present invention; Figure 2 This is a schematic diagram of the structure of the interlocking component of the present invention; Figure 3 This is a schematic diagram of the stepped windowed laser groove structure of the present invention; Figure 4 This is a schematic diagram of the anti-overflow component of the present invention; Figure 5 This is a schematic diagram of the structure of the inner copper layer L3 of the present invention.

[0016] In the diagram: 1. Outer copper foil; 2. PP1 prepreg; 3. L2 inner copper layer; 4. PP2 No-flow prepreg; 5. Reverse-attached cover film; 6. PP2 0.15mm adhesive barrier groove in the soft-hard bonding area; 7. L3 inner copper layer; 8. PP3 No-flow prepreg; 9. PP5 ordinary flow prepreg; 10. Stepped laser groove; 11. Adhesive residue removal area; 12. Micro-concave; 13. Micro-convex; 14. Stepped windowed laser groove; 15. Narrow trapezoidal groove; 16. PP2 reverse-attached cover film; 17. Positioning and alignment mark film; 18. PP3 0.15mm adhesive barrier groove in the soft-hard bonding area. Detailed Implementation

[0017] Various exemplary embodiments, features, and aspects of this application will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0018] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0019] Furthermore, to better illustrate this application, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that this application can be implemented even without certain specific details. In some instances, methods, means, and elements well-known to those skilled in the art have not been described in detail in order to highlight the main points of this application.

[0020] Please see Figures 1-5A stepped windowed laser groove processing structure for HDI rigid-flex PCBs is proposed, including an outer copper foil 1, a PP1 prepreg 2, a descaling zone 11, and a filling component.

[0021] A PP1 semi-cured sheet 2 is provided at the bonding joint on the outer copper foil 1. A descaling area 11 is provided at the assembly joint on the PP1 semi-cured sheet 2. The outer copper foil 1 and the PP1 semi-cured sheet 2 are fixed at the bonding joint on the filling component. A concave-convex interlocking component is installed on the outer copper foil 1. An anti-overflow component is provided on the outer copper foil 1. The adhesive removal area 11 has windows on the outer copper foil 1 and PP1 semi-cured sheet 2, so that the outer copper foil 1 and PP1 semi-cured sheet 2 have windows together to form the adhesive removal area 11. The windows are located in the rigid area, do not overlap with the soft area filler, and maintain a safe distance from the adhesive barrier groove in the soft-hard bonding area. Among them, the bonding area on the PP1 prepreg 2 is provided with an L2 inner copper layer 3, the bottom of the L2 inner copper layer 3 is bonded with a PP2 No-flow prepreg 4, the PP2 No-flow prepreg 4 is connected to a reverse cover film 5 facing the bonding area, and the PP2 No-flow prepreg 4 is provided with a PP2 soft and hard bonding area 0.15mm adhesive resistance groove 6.

[0022] In this embodiment, the inner copper layer 3 of L2 serves as both an inner conductive circuit and the first-stage stop layer of the stepped windowed laser groove, enabling laser depth control. A PP2 No-flow prepreg 4 is bonded to the bottom of the inner copper layer 3 of L2. The resin flow of the PP2 No-flow prepreg 4 is small during pressing, reducing the risk of glue overflow from the source. A reverse cover film 5 is bonded to the surface of the PP2 No-flow prepreg 4 facing the inner copper layer of L3. The reverse cover film 5 forms the first physical barrier layer, preventing resin from creeping into the soft area. At the same time, the edge alignment mark can prevent pressing slippage. A 0.15mm glue-blocking groove 6 is opened at the soft and hard bonding area of ​​the PP2 No-flow prepreg 4. The glue-blocking groove cuts through the PP2 No-flow prepreg 4 and the reverse cover film 5 to contain the glue overflow during pressing, prevent the glue from flowing into the soft area, and facilitate the discharge of laser residue.

[0023] Preferably, an inner copper layer 7 of L3 is provided at the lower bonding area of ​​the 0.15mm adhesive barrier groove 6 in the PP2 soft and hard bonding area, and a PP3 No-flow prepreg 8 is bonded at the lower connection area of ​​the inner copper layer 7 of L3.

[0024] The 0.15mm adhesive barrier groove 6 in the PP2 soft-hard bonding area is a hollow cavity and is not bonded to the inner copper layer 7 of L3. The PP3 No-flow semi-cured sheet 8 is bonded to the lower side of the inner copper layer 7 of L3. When the PP3 No-flow semi-cured sheet 8 is pressed, the resin flow is small. The adhesive barrier groove on it and the upper PP2 adhesive barrier groove 6 form a two-stage overflow adhesive containment structure, which intercepts the overflow adhesive from the upper layer for a second time.

[0025] Preferably, a PP5 ordinary flow semi-cured sheet 9 is bonded to the bottom of the PP3 No-flow semi-cured sheet 8, and a stepped laser groove 10 is opened on the inner side of the PP1 semi-cured sheet 2.

[0026] PP5 ordinary flow semi-cured sheet 9 and PP3 No-flow semi-cured sheet 8 are ordinary flow semi-cured sheets. They no longer use expensive No-flow materials. No-flow PP is only used in the PP2 and PP3 layers, which are at risk of glue overflow in the soft and hard bonding area, which greatly reduces the material cost of the board.

[0027] Please refer to Figure 2 and Figure 3 In this embodiment, the interlocking component includes a micro-concave 12 bonded to the stepped laser groove 10, and a micro-convex 13 bonded to the inner side of the micro-concave 12.

[0028] Micro-recess 12 is a pit machined into the stepped plane, and micro-convex 13 is a protrusion formed by subsequent electroplating and resin filling. The two are interlocked.

[0029] Preferably, the stepped laser groove 10 is provided with stepped windowed laser grooves 14 on both sides, and the bottom end of the stepped windowed laser groove 14 is provided with a narrow trapezoidal groove 15.

[0030] The micro-convex 13 and micro-concave 12 increase the surface roughness of the substrate, which is conducive to the full wetting of the surface of the tank steps by the chemical solution, reducing the retention of bubbles in the dead corners of the steps, reducing the voids in the electroplating layer. The descaling chemical solution flows through the descaling zone 11 into the interior of the stepped laser tank to rinse the interior of the micro-concave 12, avoiding laser residue remaining in the pits of the micro-concave 12 and preventing the residue from causing poor plating.

[0031] Please refer to Figure 4 and Figure 5 In this embodiment, the anti-overflow component includes a PP2 reverse-adhesive cover film 16 bonded to the 0.15mm adhesive barrier groove 6 of the PP2 soft and hard bonding area, and a positioning and alignment mark film 17 is connected to the adhesive portion of the PP2 reverse-adhesive cover film 16.

[0032] The PP2 reverse-adhesive cover film 16, by setting the positioning and alignment mark film 17, can achieve precise CCD optical alignment and positioning before the laminated plates are pressed together. This effectively prevents the PP2 reverse-adhesive cover film 16 from slipping or shifting during the high-temperature pressing process, ensuring the relative positional accuracy between the PP2 reverse-adhesive cover film 16 and the 0.15mm adhesive barrier groove 6 in the PP2 soft and hard bonding area. This ensures that the adhesive barrier interface of the PP2 reverse-adhesive cover film 16 is intact and without misalignment gaps, stably blocking the PP2 resin from creeping into the soft area. Together with the two-stage adhesive barrier groove structure, it enhances the adhesive overflow barrier capability in the soft and hard bonding area.

[0033] Preferably, the anti-overflow component also includes a 0.15mm adhesive barrier groove 18 of PP3 soft and hard bonding area formed on the inner copper layer 7 of L3.

[0034] If a small amount of adhesive overflows from the PP2 side and passes through the upper 0.15mm adhesive barrier 6, it will first reach the inner copper layer 7 of L3, and then enter the lower upper 0.15mm adhesive barrier 6. When the amount of adhesive overflow during pressing is too large, the upper 0.15mm adhesive barrier 6, together with the outer adhesive overflow buffer zone, is already saturated. After a small amount of adhesive seeps downwards and crosses the PP2 structure, the 0.15mm adhesive barrier 18 in the PP3 soft-hard bonding area will again contain and intercept the leaked resin, further preventing the adhesive from continuing to flow into the soft area and avoiding adhesive overflow contamination of the FPC soft area circuit and pads.

[0035] As can be seen from the above, during use, a PP2 No-flow prepreg 4 is bonded to the bottom of the inner copper layer 3 of L2. The PP2 No-flow prepreg 4 results in a small resin flow during lamination, reducing the risk of adhesive overflow from the source. A reverse-adhesive cover film 5 is bonded to the surface of the PP2 No-flow prepreg 4 facing the inner copper layer of L3. The reverse-adhesive cover film 5 forms the first physical barrier layer, preventing resin from creeping into soft areas. Simultaneously, edge alignment marks can prevent lamination slippage. The PP2 No-flow prepreg... A 0.15mm adhesive barrier groove 6 is provided at the soft-hard bonding area of ​​sheet 4. The adhesive barrier groove cuts through both the PP2 No-flow semi-cured sheet 4 and the reverse cover film 5 to contain the adhesive overflow during pressing. The relative positional accuracy between the PP2 reverse cover film 16 and the 0.15mm adhesive barrier groove 6 in the soft-hard bonding area of ​​PP2 ensures that the adhesive barrier interface of the PP2 reverse cover film 16 is intact and without misalignment or gaps, stably blocking the PP2 resin from creeping into the soft area. Together with the two-stage adhesive barrier groove structure, it enhances the adhesive overflow barrier capability of the soft-hard bonding area.

[0036] The micro-convex 13 and micro-concave 12 increase the surface roughness of the substrate, which is conducive to the full wetting of the surface of the tank steps by the chemical solution, reducing the retention of bubbles in the dead corners of the steps, reducing the voids in the electroplating layer. The descaling chemical solution flows through the descaling zone 11 into the interior of the stepped laser tank to rinse the interior of the micro-concave 12, avoiding laser residue remaining in the pits of the micro-concave 12 and preventing the residue from causing poor plating.

[0037] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0038] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A stepped windowed laser groove processing structure for HDI rigid-flex PCBs, comprising an outer copper foil (1), a PP1 prepreg (2), a descaling area (11), and a filling assembly, wherein the PP1 prepreg (2) is provided at the bonding joint on the outer copper foil (1), the descaling area (11) is provided at the assembly joint on the PP1 prepreg (2), and the outer copper foil (1) and the PP1 prepreg (2) are fixed at the bonding joint on the filling assembly, characterized in that: It also includes settings, The interlocking assembly is mounted on the outer copper foil (1); An anti-overflow component is disposed on the outer copper foil (1); Among them, the bonding area of ​​the PP1 semi-cured sheet (2) is provided with an L2 inner copper layer (3), the bottom end of the L2 inner copper layer (3) is bonded with a PP2 No-flow semi-cured sheet (4), the PP2 No-flow semi-cured sheet (4) is connected with a reverse cover film (5) facing the bonding area, and the PP2 No-flow semi-cured sheet (4) is provided with a PP2 soft and hard bonding area 0.15mm adhesive resistance groove (6).

2. The stepped windowed laser groove processing structure for HDI rigid-flex boards according to claim 1, characterized in that, An L3 inner copper layer (7) is provided at the lower bonding area of ​​the 0.15mm adhesive barrier groove (6) of the PP2 soft and hard bonding area, and a PP3 No-flow semi-cured sheet (8) is bonded at the lower connection of the L3 inner copper layer (7).

3. The stepped windowed laser groove processing structure for HDI rigid-flex boards according to claim 2, characterized in that, The bottom end of the PP3 No-flow semi-cured sheet (8) is bonded with a PP5 ordinary flow semi-cured sheet (9), and the inner side of the PP1 semi-cured sheet (2) is provided with a stepped laser groove (10).

4. The stepped windowed laser groove processing structure for HDI rigid-flex boards according to claim 3, characterized in that, The interlocking component includes a micro-concave (12) bonded to a stepped laser groove (10), and a micro-convex (13) bonded to the inner side of the micro-concave (12).

5. The stepped windowed laser groove processing structure for HDI rigid-flex boards according to claim 4, characterized in that, The stepped laser groove (10) is provided with stepped windowed laser grooves (14) on both sides, and a narrow trapezoidal groove (15) is provided at the bottom of the stepped windowed laser groove (14).

6. The stepped windowed laser groove processing structure for HDI rigid-flex boards according to claim 1, characterized in that, The anti-overflow component includes a PP2 reverse-adhesive cover film (16) bonded to the 0.15mm adhesive barrier groove (6) of the PP2 soft and hard bonding area, and a positioning and alignment mark film (17) is connected to the adhesive joint of the PP2 reverse-adhesive cover film (16).

7. The stepped windowed laser groove processing structure for HDI rigid-flex boards according to claim 6, characterized in that, The spill prevention component also includes a 0.15mm adhesive barrier groove (18) for the PP3 soft and hard bonding area on the inner copper layer (7) of L3.

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