Reverse waste discharge method for flexible circuit board of integrated semiconductor IC chip

Abstract

The invention discloses a reverse waste discharge method for a flexible circuit board of an integrated semiconductor IC chip, and relates to the technical field of flexible circuit board manufacturing, and the method comprises the steps: compositing a whole-surface inner film on a bearing film; performing die cutting on the inner film, discharging waste to remove the inner film outside the target area, and only reserving part of the inner film at the position corresponding to the subsequent waste discharging guide block as a glue covering lining; a conductive base material layer is attached to the bearing film and the glue covering lining, die cutting is conducted on the conductive base material layer, a circuit line and waste are formed, the waste comprises a waste discharge guide block and a reverse waste discharge section which are connected, and the length D of the reverse waste discharge section is smaller than or equal to 20 mm; an upper waste discharge film is attached to the upper surfaces of the conductive base material layer and the glue covering lining after die cutting; carrying out waste discharge operation; the upper waste discharge film grabs the waste discharge guide block and is stripped upwards, and the waste discharge guide block exerts pulling force on the reverse waste discharge section to overcome the bonding force between the reverse waste discharge section and the bottom-layer bearing film, so that the reverse waste discharge section is driven to be separated from the bearing film, and reverse waste discharge without starting waste is achieved.

Description

Technical Field

[0001] This invention relates to the field of flexible circuit board manufacturing technology, and in particular to a reverse waste removal method for flexible circuit boards used to integrate semiconductor IC chips. Background Technology

[0002] Flexible printed circuit boards (FPCs), as key interconnect carriers in modern high-density electronic packaging, are widely used in smartphones, wearable devices, and semiconductor packaging. Traditional FPC manufacturing mainly relies on chemical etching processes, which include multiple steps such as material preparation, dry film lamination, exposure, development, etching, film removal, cover film lamination, and lamination. This process is not only cumbersome, time-consuming, and costly, but also generates large amounts of industrial wastewater containing copper, acids, and alkalis during etching, placing a heavy burden on environmental treatment and making it difficult to meet the development trend of green manufacturing.

[0003] To simplify processes and improve environmental friendliness, flexible die-cut circuit (FDC) technology has gradually emerged in recent years. FDC completes patterning in one step through circular die-cutting, without the need for chemical agents, and has significant advantages such as short process, no wastewater, and recyclable waste. However, when FDC technology is applied to high-density interconnection scenarios of integrated semiconductor IC chips, it faces severe challenges: the IC pin pitch is very small, and the line width is often less than 0.25mm, resulting in long, narrow, closed or nested structures of waste copper areas, forming typical "no-start waste"—that is, the waste is surrounded by effective lines and lacks free edges for waste tape to grab.

[0004] In conventional waste removal processes, if the waste material lacks a starting point for stripping, it cannot be effectively carried away by the upper waste removal film. Forcibly increasing the adhesion or tension can easily cause adjacent effective copper wires to be lifted, displaced, or even broken, severely affecting product yield and reliability. Although the industry has attempted to improve waste removal efficiency by optimizing the waste removal path or adding auxiliary waste materials, it remains difficult to reliably remove fine, non-starting-point waste copper without sacrificing circuit precision.

[0005] Furthermore, existing die-cutting waste removal processes generally use uniformly viscous carrier films without differentiated adhesion control between the waste copper area and the effective circuit area, resulting in poor waste removal selectivity. At the same time, ordinary waste removal films lack elasticity and are prone to breaking due to stress concentration when pulling slender waste materials in the reverse direction, further increasing the risk of waste removal failure.

[0006] Therefore, there is an urgent need for a new FDC manufacturing method suitable for integrated semiconductor IC chips, which can accurately solve the waste disposal problem of no starting waste through structural design and material synergy without relying on chemical etching, thereby achieving multiple goals of high-density wiring, high yield and environmentally friendly manufacturing. Summary of the Invention

[0007] This invention proposes a reverse waste removal method for flexible circuit boards used to integrate semiconductor IC chips, aiming to solve the problem of waste removal without starting material.

[0008] To achieve the above objectives, the present invention proposes a reverse waste removal method for flexible circuit boards used to integrate semiconductor IC chips, comprising:

[0009] A full-surface inner membrane is laminated onto the carrier membrane; The inner membrane is die-cut, and the inner membrane outside the target area is removed by waste removal. Only a portion of the inner membrane is retained as an adhesive masking liner at the position corresponding to the subsequent waste removal guide block, so that the adhesiveness in that area is blocked, while the adhesiveness in the remaining areas remains exposed. A conductive substrate layer is attached to the carrier film and the masking liner, and the conductive substrate layer is die-cut to form circuit lines and waste. The waste includes a waste discharge guide block and a reverse waste discharge section connected to each other, wherein the length D of the reverse waste discharge section is ≤20mm, and the waste discharge guide block is located directly above the masking liner. The waste film is attached to the upper surface of the die-cut conductive substrate layer and the masking liner. In the waste discharge operation, the upper waste discharge membrane grabs the waste discharge guide block and peels it upward. The waste discharge guide block applies a pulling force to the reverse waste discharge section to overcome the adhesion between it and the bottom supporting membrane, thereby causing the reverse waste discharge section to detach from the supporting membrane together, thus realizing reverse waste discharge without starting waste.

[0010] In one embodiment, the width of the waste discharge guide block is M. When M ≥ 3.5 mm, the waste discharge guide block connects two reverse waste discharge sections, and the far ends of the two reverse waste discharge sections are connected as one unit.

[0011] In one embodiment, when the width of the waste discharge guide block is M, and 3.0mm≤M≤3.3mm, the waste discharge guide block is connected to a reverse waste discharge section.

[0012] In one embodiment, the distal ends of the reverse waste discharge sections extending from two adjacent waste discharge guide blocks are connected as one unit.

[0013] In one embodiment, the area of ​​the waste discharge guide block is not less than 9 mm². 2 Furthermore, the length and width of the waste discharge guide block are both not less than 3mm.

[0014] In one embodiment, the adhesive-masking liner is an impermeable polymer release film that covers only the area corresponding to the waste discharge guide block, thereby blocking the bonding between the adhesive and the conductive substrate layer in that area, so that the waste discharge guide block can be controlled to peel off only through the upper waste discharge film.

[0015] In one embodiment, the waste discharge membrane is a stretchable polyethylene (PE) membrane that can undergo elastic deformation along the waste copper path during the waste discharge process.

[0016] In one embodiment, the reverse waste discharge section is a fine waste copper line connecting the pins of a semiconductor IC chip, with a width ≤0.25mm, used to achieve physical die-cutting of a high-density interconnect structure.

[0017] In one embodiment, the viscosity of the upper waste discharge film is lower than that of the carrier film, so that during the waste discharge process, the waste discharge guide block preferentially detaches from the bottom carrier film and adheres to the upper waste discharge film, while the copper foil in the effective circuit area remains stably bonded to the bottom carrier film.

[0018] In one embodiment, the viscosity of the carrier membrane is 650g / 25mm-750g / 25mm; the viscosity of the waste membrane discharged above is 400g / 25mm-600g / 25mm.

[0019] The technical solution of this invention can solve the problem of waste disposal without starting material, thereby achieving multiple goals of high-density wiring, high yield and environmentally friendly manufacturing. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0021] Figure 1 A schematic block diagram illustrating the reverse waste removal method for a flexible circuit board for integrating semiconductor IC chips provided by the present invention; Figure 2 This is a partial structural diagram of the waste generated in step 3 of the reverse waste discharge method provided by the present invention. Figure 3 This is a schematic diagram of the waste discharge process of the reverse waste discharge method provided by the present invention. Figure 4 for Figure 3 A magnified view of a portion of the image; Figure 5 This is a schematic diagram of the second waste discharge process of the reverse waste discharge method provided by the present invention; Figure 6 for Figure 5 A magnified view of a portion of the image.

[0022] Explanation of icon numbers: 10. Conductive substrate layer; 11. Waste discharge guide block; 12. Reverse waste discharge section; 20. Carrier film; 30. Masking liner; 40. Upper waste discharge film.

[0023] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0026] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0027] This invention proposes a reverse waste removal method for flexible circuit boards used to integrate semiconductor IC chips.

[0028] Please see Figures 1 to 6 In one embodiment of the present invention, the reverse waste removal method for flexible circuit boards used to integrate semiconductor IC chips is applicable to the reliable removal of "starting-end waste" formed in high-density interconnect structures due to fine lines and enclosed waste materials. This method achieves efficient and stable waste removal under physical die-cutting processes through the synergistic effect of structural design and adhesive control. Specifically, it includes the following steps: Step 1: Lay an entire inner film onto the carrier film 20.

[0029] Specifically, a carrier film 20 (such as transparent tape) with an adhesive surface is provided, and a full-surface inner film is continuously laminated on its upper surface.

[0030] Step 2: Die-cut the inner membrane and remove waste to form a partially adhesive-masking inner liner 30.

[0031] Specifically, a die-cutting process (such as rotary die-cutting) is used to remove all inner films except those corresponding to the waste discharge guide block 11, leaving only the area directly below the waste discharge guide block 11 to form an adhesive masking liner 30. This results in the following difference in adhesion: the adhesive masking liner 30 below the waste discharge guide block 11 blocks the contact between the adhesive of the carrier film 20 and the copper foil, preventing adhesion between them. The inner film below the reverse waste discharge section 12 has been removed, allowing the copper foil to directly contact the adhesive layer of the carrier film 20, maintaining normal adhesion. This achieves a difference in adhesion within the waste area; the waste discharge guide block 11 easily detaches from the substrate, while the reverse waste discharge section 12 remains firmly attached, laying the foundation for a strong-to-weak reverse waste discharge mechanism.

[0032] Step 3: Apply conductive substrate layer 10 and perform die cutting to form circuits and waste materials.

[0033] Specifically, the conductive substrate layer 10 is integrally pressed onto the upper surface of the carrier film 20, covering the masking liner 30 area and the exposed adhesive area. Subsequently, the conductive substrate layer 10 is precision die-cut (e.g., rotary die-cutting) to form the required circuit lines and waste patterns. The waste includes a connected waste discharge guide block 11 and a reverse waste discharge section 12. The waste discharge guide block 11 has a larger area and is located directly above the masking liner 30; the reverse waste discharge section 12 is a thin, elongated micro-line connecting the waste discharge guide block 11 to the area between the IC chip pins, with a length D ≤ 20mm. Figure 2 As shown, D is the unidirectional length of the reverse waste discharge section. Through structural design, the enclosed waste that is difficult to discharge is physically connected to the grabbable waste discharge guide block 11 to construct a traction and following waste discharge path.

[0034] Step 4: Apply the waste discharge membrane 40.

[0035] Specifically, an upper waste removal film 40 is attached to the upper surface of the conductive substrate layer 10 and the masking liner 30 after die cutting, in preparation for subsequent waste removal operations. The conductive substrate layer can be made of conductive materials such as copper, aluminum, copper alloy, or aluminum alloy.

[0036] Step 5: Perform reverse waste discharge operation.

[0037] Specifically, the waste removal process is initiated, and the upper waste removal film 40 is peeled upwards under the action of the waste removal roller. Since the waste removal guide block 11 has no adhesive force to the bottom layer, it is preferentially grabbed and lifted completely by the upper waste removal film 40. Although the reverse waste removal section 12 has adhesive force to the bottom layer, it is rigidly connected to the waste removal guide block 11 and is subjected to continuous tension from the waste removal guide block 11. When this tension exceeds the adhesive force between the reverse waste removal section 12 and the bottom supporting film 20, the reverse waste removal section 12 is forcibly peeled off from the substrate and carried away by the upper waste removal film 40 along with the waste removal guide block 11, thus completing the removal of the entire waste. This successfully achieves reliable discharge of "waste without a starting point," avoiding problems such as waste removal failure, residual short circuits, or damage to effective circuits caused by the inability to grab the starting end in traditional methods, significantly improving product yield and reliability.

[0038] This method solves the waste removal problem of high-density micro-circuits in FDC integrated IC chips through a multi-dimensional collaborative design of local masking and lead-head traction, without the use of chemical etching. The entire process is purely physical, generating no wastewater, and the waste copper is recyclable, combining environmental friendliness, economy, and high yield, making it suitable for advanced packaging, flexible electronics, and other high-end manufacturing fields. Limiting the length D of the reverse waste removal section 12 to ≤20mm is not arbitrary but a key technical parameter determined comprehensively based on material mechanics, waste removal process feasibility, and actual production experience. It is backed by clear engineering basis and physical limitations. The effectiveness of tensile force transmission decreases with length. In the reverse waste removal mechanism of this invention: the waste removal guide block 11 is grasped and peeled upwards by the upper waste removal film 40; this action applies tensile force to the reverse waste removal section 12 through a rigid connection; the reverse waste removal section 12 must overcome the adhesive force between itself and the underlying carrier film 20 to be pulled off. However, although copper foil itself has a certain strength, as a micro-circuit (width often ≤0.25mm), its tensile strength is limited. When the reverse waste discharge section 12 is too long, the tensile force is significantly attenuated during transmission due to factors such as material elastic deformation, frictional resistance, and path bending. One end near the waste discharge guide block 11 may have been pulled up, but the far end remains firmly adhered to the bottom layer. This ultimately leads to breakage in the middle of the waste or residue at the far end, resulting in waste discharge failure. Experiments and simulations show that when D>20mm, the waste discharge success rate drops sharply; while when D≤20mm, the tensile force is sufficient to penetrate the entire waste section, achieving complete stripping.

[0039]

[0040] As shown in the table above, when D ≤ 20mm, the waste removal integrity rate remains stable at over 98%, meeting the yield requirements of high-end FDC manufacturing (typically requiring ≥95%). When D > 20mm, the waste removal integrity rate drops sharply: at D = 22mm, the integrity rate drops to 92%; at D = 25mm, obvious waste material breakage and residue appear, and the yield fails to meet the standard. As D increases, the tensile force transmission attenuates more rapidly in the slender copper wire, and the copper foil itself lacks sufficient rigidity, resulting in plastic deformation or local buckling under the traction of the waste removal film, ultimately leading to breakage at stress concentration points. Therefore, to ensure that the reverse waste removal section 12 is completely and reliably discharged without a starting point, its length D must be controlled within 20mm.

[0041] It should be noted that "no starting point" refers to scrap material that is completely surrounded by effective circuitry, embedded within the pattern, or in the form of a long, closed loop, connected to the substrate or other structure on all sides, with no free edges available for initial stripping. "No starting point scrap" refers to non-functional metal areas (usually scrap copper) that need to be removed after die-cutting (such as rotary die-cutting), whose geometry or location results in the absence of a "starting point" or "starting edge" for a waste removal mechanism (such as waste removal tape) to grab and initiate stripping.

[0042] Furthermore, the width of the waste discharge guide block is M. When M≥3.5mm, the waste discharge guide block connects two reverse waste discharge sections, and the far ends of the two reverse waste discharge sections are connected as one unit.

[0043] Specifically, in this embodiment, when M ≥ 3.5 mm, the waste discharge guide block connects two reverse waste discharge sections, and the distal ends of the two reverse waste discharge sections are connected to each other to form a closed or semi-closed annular waste structure. The width M of the waste discharge guide block is not less than 3.5 mm to ensure sufficient area for stable gripping by the upper waste discharge membrane and to provide sufficient traction force; the waste discharge guide block acts as a node and is connected to the two reverse waste discharge sections, forming a one-to-two waste discharge topology; the two reverse waste discharge sections are connected to each other at the end away from the waste discharge guide block to form an integrally connected waste frame, avoiding isolated and closed areas without a starting point. Because the two reverse waste removal sections form a continuous loop through a remote connection, even if one section is difficult to peel off due to excessive local adhesion, the other section can still transfer the pulling force through the overall structure to achieve synchronous detachment, effectively preventing material breakage or residue; the integrated waste frame maintains geometric stability during the waste removal process, reducing the risk of twisting, buckling or breaking of slender waste copper lines under tension; in semiconductor packaging, pins are often symmetrically distributed on both sides of the chip, and this structure can simultaneously remove the fine waste copper lines on both sides, improving waste removal efficiency; by integrating multiple potentially dispersed closed waste areas into a single tractable waste, the waste removal path is simplified, and the consumption of waste removal membranes and equipment complexity are reduced.

[0044] In summary, when the width M of the waste discharge guide block is greater than or equal to 3.5 mm, and is combined with the structural design of the far-end connection of the double reverse waste discharge section, it not only meets the basic requirements of the gripping area, but also achieves efficient, complete and residue-free discharge of complex and high-density FDC waste through mechanical linkage and structural closed loop, which significantly improves the manufacturing yield and process robustness of flexible copper clad laminates in advanced semiconductor integration applications.

[0045] Furthermore, when the width of the waste discharge guide block is M, and 3.0mm≤M≤3.3mm, the waste discharge guide block connects to a reverse waste discharge section. The distal ends of the reverse waste discharge sections extending from two adjacent waste discharge guide blocks are connected as a single unit.

[0046] Specifically, in this embodiment, the width M of the waste discharge guide block is between 3.0mm and 3.3mm. Within this size range, each waste discharge guide block connects to a reverse waste discharge section. The reverse waste discharge sections led out by two adjacent waste discharge guide blocks are connected at their far ends to form a transversely connected bridging waste structure. Each waste discharge guide block connects only one reverse waste discharge section, resulting in a simple structure that is easy to arrange as needed in the IC chip pin array. The reverse waste discharge sections of two adjacent waste discharge units are connected at the ends away from the waste discharge guide blocks, forming a closed or semi-closed annular waste area. Since the two reverse waste discharge sections form a continuous conductive path through the far-end bridging, when any waste discharge guide block is grabbed by the upper waste discharge membrane and peeled upwards, the pulling force can be transmitted to the adjacent waste through the bridging section, causing the other side of the reverse waste discharge section to detach synchronously, effectively avoiding single-sided residue or breakage. The reverse waste discharge section is usually ≤0.25mm wide and has extremely weak rigidity when it exists alone, making it easy to bend or tear under waste discharge tension. The "U"-shaped structure formed by the remote connection significantly improves the overall tensile strength and deformation resistance. In QFN, BGA, and other packages, the IC chip often has pins symmetrically distributed on both sides. This structure naturally matches this layout, enabling coordinated removal of waste from both sides without the need for additional waste removal leads. The width of the waste removal guide block is strictly controlled between 3.0 and 3.3 mm to ensure safe placement even in high-density areas with pin spacing ≤ 0.5 mm. Furthermore, the bridging section is located away from the waste area of ​​functional circuitry, without interfering with the adhesion of effective circuitry.

[0047] In summary, by combining the size-constrained waste removal guide block (3.0mm≤M≤3.3mm) with the integrated design of the far end of the adjacent reverse waste removal section, this invention constructs a waste removal structure with high reliability, high integration and strong mechanical synergy within a limited space. It is particularly suitable for the efficient removal of complex, enclosed waste without a starting point in advanced semiconductor packaging, and significantly improves the yield and process robustness of flexible copper clad laminate manufacturing.

[0048] It should be noted that, in addition to being connected to the waste discharge guide block, the reverse waste discharge section is further connected to multiple small, headless waste materials. When the reverse waste discharge section is pulled upward by the upper waste discharge membrane through the waste discharge guide block during the waste discharge process, the multiple small, headless waste materials connected to it are simultaneously driven and detached from the supporting membrane, thereby achieving indirect removal of closed micro-waste materials that could not be directly grasped.

[0049] Furthermore, the area of ​​the waste discharge guide block 11 is not less than 9 mm². 2 Furthermore, the length and width of the waste discharge guide block 11 are both not less than 3mm, to ensure that the upper waste discharge membrane 40 can effectively grasp and provide sufficient traction.

[0050] Specifically, in this embodiment, the waste discharge guide block 11 serves as the traction head in the waste discharge process. Its area design provides sufficient contact interface, enabling the upper waste discharge membrane 40 to form a sufficiently strong and effective adhesive force on its surface. The reverse waste discharge section 12, due to its small area and closed edges, is difficult for the waste discharge membrane to grasp independently. By connecting the two and ensuring that the waste discharge guide block 11 has sufficient "grasping redundancy," a stable and continuous traction force can be generated during the waste discharge process. This force is transmitted to the reverse waste discharge section 12 via the connecting part, sufficient to overcome the adhesive force between it and the underlying carrier membrane 20. This significantly improves the waste discharge success rate and avoids residue, breakage, or interruption of the reverse waste discharge section 12 due to insufficient traction force. Simultaneously, since the traction force originates from a reliably grasped large area rather than forcibly peeling off fine structures, it effectively prevents adjacent effective lines from being mistakenly pulled up or deformed, thereby ensuring the structural integrity and product yield of the high-density interconnect area.

[0051] Furthermore, the inner membrane is an adhesive-impermeable polymer release membrane that only covers the area corresponding to the waste discharge guide block 11, thereby blocking the bonding between the adhesive and the conductive substrate layer 10 in that area, so that the waste discharge guide block 11 can be controlled to peel off only through the upper waste discharge membrane 40.

[0052] Specifically, in this embodiment, the inner membrane is composed of a non-adhesive polymer substrate (such as polyethylene terephthalate PET or polyethylene PE) coated with a silicone-based release agent, exhibiting excellent adhesive barrier properties and low surface energy. It is only located in a localized area directly below the waste discharge guide block 11; this structure is absent below the reverse waste discharge section 12 and other effective circuit areas. After the carrier film 20 is coated with adhesive, this release film effectively prevents the adhesive from penetrating or adhering to the bottom of the copper foil in the corresponding area, thus ensuring no substantial adhesion between the waste discharge guide block 11 and the underlying carrier film 20 after die-cutting. Because the waste discharge guide block 11 is isolated by the masking liner 30, it maintains its position solely through the adhesion of the upper waste discharge film 40; while the reverse waste discharge section 12, connected to it, remains normally bonded to the carrier film 20 due to the absence of the masking liner 30. This localized adhesion difference constitutes a "selective peelable" structure, which allows the upper waste discharge membrane 40 to easily take away the waste discharge guide block 11 during peeling and apply tension to the subsequent reverse waste discharge section 12 through a mechanical connection.

[0053] Furthermore, the upper waste discharge membrane 40 is a stretchable polyethylene (PE) membrane, which can undergo elastic deformation along the waste copper path during the waste discharge process, preventing the slender reverse waste discharge section 12 from being torn apart during reverse peeling.

[0054] Specifically, in this embodiment, the upper waste discharge membrane 40 is made of polyethylene (PE), preferably linear low-density polyethylene (LLDPE) or low-density polyethylene (LDPE), which has good flexibility and ductility. Its elongation at break is usually not less than 200%, and it can undergo significant elastic deformation without breaking under stress. By using a stretchable PE membrane as the upper waste discharge membrane 40, it can locally stretch and deform in accordance with the direction of the waste copper path during the traction process, effectively buffering the tensile impact, making the stress distribution on the reverse waste discharge section 12 more uniform and the dynamic response smoother. The introduction of the stretchable PE upper waste discharge membrane 40 is a key material innovation to ensure the complete peeling of slender, headless waste during the reverse traction process, and it forms a high degree of synergy with the overall waste discharge mechanism of this invention. Even in complex waste discharge paths or microstructures, it can completely remove the reverse waste discharge section 12, significantly reducing the risk of waste breakage; avoiding reliability problems such as subsequent short circuits and poor pressing caused by waste residue, and improving waste discharge consistency and yield.

[0055] Furthermore, the reverse waste discharge section 12 is a fine waste copper line connecting the pins of the semiconductor IC chip, with a width of ≤0.25mm, used to achieve physical die-cutting of high-density interconnect structure.

[0056] Specifically, in this embodiment, the reverse waste removal section 12 is located between the pins of the integrated semiconductor IC chip and belongs to the key non-functional copper structure in the high-density interconnect area. Its line width does not exceed 0.25mm, and it is typically a long, thin strip or a closed ring, surrounded by effective signal lines or pads, with no free edges, making it a typical "no-start waste". Because this type of fine waste copper line has a small area, closed edges, and cannot be directly grasped by the waste removal film, it is very easy to leave residue if traditional waste removal methods are used. However, this invention transforms it into "tractionable auxiliary waste" by physically connecting it to the adjacent waste removal guide block 11 and combining it with the partial masking liner 30 and the stretchable upper waste removal film 40. When the waste removal guide block 11, acting as the waste removal lead, is peeled off by the upper waste removal film 40, a continuous pulling force is applied to the fine reverse waste removal section 12 through a rigid connection, thereby achieving its forced detachment. This implementation solves the core waste removal problem in high-density FDC manufacturing, successfully removing sub-0.25mm level scrap copper without a starting point, which is difficult to handle with traditional processes; ensuring IC packaging reliability and completely avoiding pin-to-pin short circuits, impedance abnormalities, or thermo-pressure failures caused by tiny scrap copper residues; supporting advanced packaging requirements and meeting the mass production feasibility of fine lines (≤0.25mm) for high I / O density packages such as CSP and Fan-Out; expanding the applicability of physical die-cutting processes, enabling FDC technology to replace some chemical etching scenarios, achieving green, efficient, and high-yield manufacturing. In summary, defining the reverse waste removal section 12 as the micro-fine scrap copper line (width ≤0.25mm) between IC pins not only reflects the technical targeting of this invention for high-end applications but also highlights its key value in the physical forming of high-density flexible circuits. Furthermore, the viscosity fluctuation range of the underlying carrier film 20 is controlled within ±50g / 25mm to ensure that the copper foil in the effective circuit area remains stably attached during the waste discharge process, thereby improving product yield.

[0057] Specifically, in this embodiment, the key process control indicators for the consistency of adhesion of the bottom carrier film 20 are defined. The fluctuation range refers to the maximum deviation of the peel force (under standard test conditions, such as 180° peel, 25mm width) measured at different positions within the same roll or batch of carrier film 20, not exceeding ±50g / 25mm; for example, if the target adhesion is set to 700g / 25mm, the actual adhesion is strictly controlled within a narrow range of 650g / 25mm to 750g / 25mm. During the reverse waste removal process, the waste removal guide block 11, due to the presence of the adhesive-masking liner 30 below, has no adhesion to the carrier film 20 and can be smoothly carried away by the upper waste removal film 40; while the effective circuit area and the reverse waste removal section 12 remain fixed by the adhesion of the carrier film 20. If the viscosity of the carrier film 20 fluctuates too much (e.g., locally too low), the effective copper lines may shift, lift, or even be mistakenly carried away from the substrate under the waste removal tension. If the viscosity is too high locally, the pulling force required for the reverse waste removal section 12 may exceed the bearing limit of the upper waste removal film 40 or the connecting part, resulting in waste removal failure or waste material breakage. By strictly controlling the viscosity fluctuation within ±50g / 25mm, a high degree of uniformity in the adhesion performance of the entire board can be achieved, ensuring that all non-waste removal guide block areas (especially the effective lines around high-density IC pins) maintain reliable adhesion throughout the waste removal process. The adhesive force on the reverse waste removal section 12 is predictable and consistent, facilitating the application of a matching traction force through the waste removal guide block 11. The resulting technical benefits include: significantly improving waste discharge stability and repeatability, avoiding waste discharge anomalies caused by material batch or location differences; preventing damage or misalignment of effective circuits, ensuring the geometric accuracy and electrical integrity of micro-circuits (≤0.25mm); improving overall product yield, reducing short circuits, open circuits, or appearance defects caused by uneven viscosity; supporting the feasibility of high-precision FDC mass production, and providing a reliable material basis for physical die-cutting to replace chemical etching.

[0058] In summary, precise control of the viscosity fluctuation range of the bottom carrier membrane 20 is an indispensable process guarantee for achieving highly reliable reverse waste discharge, and it forms a synergistic effect with the core technologies of differentiated bonding + lead-head traction in this invention.

[0059] Furthermore, the viscosity of the upper waste discharge film 40 is lower than that of the bottom carrier film 20, so that during the waste discharge process, the waste discharge guide block 11 preferentially detaches from the bottom carrier film 20 and adheres to the upper waste discharge film 40, while the copper foil in the effective circuit area remains stably bonded to the bottom carrier film 20.

[0060] In this embodiment, there is a gradient relationship in the adhesion between the upper waste discharge film 40 and the bottom carrier film 20. The viscosity of the upper waste discharge film 40 (i.e., its peeling force on the copper foil) is set at a lower level, while the viscosity of the bottom carrier film 20 is relatively higher. This viscosity gradient design works closely with the selective waste discharge mechanism of the present invention: for the waste discharge guide block 11, there is an adhesive liner 30 below it, and there is no actual adhesive force between it and the bottom carrier film 20. Therefore, even if the upper waste discharge film 40 has low adhesion, it can be completely grabbed and carried away. For the effective circuit area and the reverse waste discharge section 12 (the latter needs to be pulled out, but is initially still adhered to the bottom layer), it has complete adhesion to the bottom carrier film 20. Since the adhesion of the bottom layer is significantly higher than that of the upper waste discharge film 40, when the upper waste discharge film 40 passes through these areas, it is insufficient to overcome its bonding force with the bottom layer, thereby ensuring that the effective circuit is not mistakenly carried away. During the reverse waste discharge process, after the waste discharge guide block 11 is peeled off by the upper waste discharge film 40, a pulling force is applied to the reverse waste discharge section 12 through the connecting part. The pulling force originates from mechanical traction rather than adhesive competition. Therefore, even if the upper waste membrane 40 itself has low viscosity, waste removal can still be achieved through structural transmission without interfering with the stability of surrounding high-value lines. By constructing a viscosity gradient system where the viscosity of the upper waste membrane 40 is lower than that of the bottom supporting membrane 20, this invention achieves intelligent guidance of waste removal behavior at the material level. This is one of the core technological supports for ensuring efficient removal of waste without starting points and high product yield.

[0061] Furthermore, the viscosity of the carrier membrane 20 is 650g-750g. The viscosity of the upper waste membrane 40 is 400g-600g.

[0062] Specifically, in this embodiment, the bottom carrier film 20 serves as the basic support layer of the flexible circuit board, with its viscosity controlled at 650–750 g / 25 mm (tested according to the 180° peel standard) to provide sufficiently strong adhesion and ensure that the copper foil remains stable during die-cutting and waste removal. The upper waste removal film 40 is used to grab and carry away the waste copper, with its viscosity set in a relatively low range of 400–600 g / 25 mm, which can effectively adhere to the surface of the waste copper while avoiding excessive traction on non-target areas. There is a clear hierarchical relationship and functional division between the two viscosity ranges mentioned above. The high viscosity (≥650 g / 25 mm) of the bottom carrier film 20 ensures firm adhesion of the effective circuit area and the reverse waste removal section 12 in the initial state, preventing displacement or lifting under the action of waste removal tension; the lower viscosity (≤600 g / 25 mm) of the upper waste removal film 40 ensures that it can only carry away the waste removal guide block 11 that is no longer bonded to the bottom layer, and cannot overcome the stronger bonding force between the effective circuit and the bottom layer, thereby achieving selective waste removal. More importantly, the two together form a controlled viscosity gradient window (the viscosity of the bottom layer is always higher than that of the upper waste discharge membrane 40), making the waste discharge behavior dominated by structural design and mechanical transmission, rather than simply relying on viscosity competition. The waste discharge guide block 11 has no adhesion to the bottom layer due to the adhesive-masking liner 30 underneath, allowing it to be completely gripped even if the upper waste discharge membrane 40 has low viscosity. Subsequently, through its physical connection with the slender reverse waste discharge section 12, the pulling force is transferred to the latter, causing it to overcome the bottom layer's adhesive force (650–750g / 25mm) and be forcibly peeled off. If the viscosity of the upper waste discharge membrane 40 is too high (e.g., ≥750g / 25mm), there may be a risk of mis-adhesion when passing through the effective circuit area; if the viscosity of the bottom layer is too low (e.g., ≤600g / 25mm), the effective circuit is prone to loosening during waste discharge, affecting product reliability. The table below shows the experimental data on the effect of viscosity matching between the carrier membrane and the upper waste discharge membrane on waste discharge performance. The data in each cell is the waste discharge integrity rate / line mis-carrying rate (unit: %). The waste discharge integrity rate refers to the yield rate of completely discharging waste from the reverse waste discharge section, and the line mis-carrying rate refers to the defect rate of the line being mis-carrying.

[0063]

[0064] The table above shows that when the viscosity of the bottom carrier film is controlled at 650–750 g / 25 mm and the viscosity of the top waste discharge film is controlled at 400–600 g / 25 mm, a high waste discharge integrity rate (≥97%) and a low line miscarriage rate (≤0.4%) can be achieved.

[0065] It should be noted that the viscosity mentioned above refers to peel strength. g / 25mm is the industry standard for expressing peel strength, used to quantify the adhesive strength of an adhesive to a specific substrate (such as copper foil). For example, 700g / 25mm means that under standard test conditions, when peeling the tape from the surface of the substrate at a specified angle and speed, the force required to peel off every 25mm of width is 700 grams of force.

[0066] Furthermore, the outline of the adhesive-masking liner 30 is larger than the outline of the waste discharge guide block 11. The outline of the adhesive-masking liner 30 extends beyond the outline of the waste discharge guide block 11 by 0.1 mm to 0.3 mm in each direction.

[0067] Specifically, in this embodiment, the masking liner 30 is not aligned with the waste removal guide block 11, but rather surrounds the waste removal guide block 11 entirely, forming a concentric or identical layout with a smaller inner side and a larger outer side. In length, width, and any edge direction, the masking liner 30 extends 0.1mm to 0.3mm beyond the edge of the waste removal guide block 11 on one side, ensuring that the waste removal guide block 11 falls completely within the unbonded area. In actual roll-to-roll manufacturing, due to limitations in the registration accuracy of the die-cutting equipment (typically ±0.05mm to ±0.1mm), there may be slight alignment deviations between the waste removal guide block 11 and the masking liner 30. If the outlines of the two are strictly equal or the masking liner 30 does not extend beyond the outline, once a misalignment occurs, the edge of the waste removal guide block 11 may partially cover the exposed adhesive area, causing this area to still maintain adhesion to the underlying carrier film. During waste removal, this residual adhesion will hinder the overall peeling of the waste removal guide block 11, resulting in incomplete waste removal or, in severe cases, the reverse waste removal section being torn apart. By setting a safety margin of 0.1–0.3 mm, process alignment errors can be effectively absorbed, ensuring that even under the most unfavorable misalignment conditions, the waste discharge guide block 11 remains completely within the coverage area of ​​the masking liner 30, thus achieving a true zero-adhesion state. This avoids local adhesion of the waste discharge guide block 11 due to alignment deviations, ensuring that it is completely grasped by the upper waste discharge film; it relaxes the stringent requirements for die-cutting registration accuracy, adapting to the capabilities of mainstream FDC production line equipment; the upper limit of the margin is controlled within 0.3 mm, preventing the masking liner 30 from excessively extending into the effective circuit area, affecting its adhesion; In summary, the appropriate coverage of the waste discharge guide block 11 by the contour of the masking liner 30 (0.1–0.3 mm excess) is a key structural design for balancing alignment tolerance and functional isolation, providing an indispensable geometric guarantee for the present invention to achieve stable, efficient, and residue-free reverse waste discharge.

[0068] The above description is merely an exemplary embodiment of the present invention and does not limit the scope of protection of the present invention. Any equivalent structural transformations made based on the technical concept of the present invention and the contents of the specification and drawings of the present invention, or direct / indirect applications in other related technical fields, are included within the scope of protection of the present invention.

Claims

1. A reverse waste removal method for flexible circuit boards used to integrate semiconductor IC chips, characterized in that, include: A full-surface inner membrane is laminated onto the carrier membrane; The inner membrane is die-cut, and the inner membrane outside the target area is removed by waste removal. Only a portion of the inner membrane is retained as an adhesive masking liner at the position corresponding to the subsequent waste removal guide block, so that the adhesiveness in that area is blocked, while the adhesiveness in the remaining areas remains exposed. A conductive substrate layer is attached to the carrier film and the masking liner, and the conductive substrate layer is die-cut to form circuit lines and waste. The waste includes a waste discharge guide block and a reverse waste discharge section connected to each other, wherein the length D of the reverse waste discharge section is ≤20mm, and the waste discharge guide block is located directly above the masking liner. The waste film is attached to the upper surface of the die-cut conductive substrate layer and the masking liner. In the waste discharge operation, the upper waste discharge membrane grabs the waste discharge guide block and peels it upward. The waste discharge guide block applies a pulling force to the reverse waste discharge section to overcome the adhesion between it and the bottom supporting membrane, thereby causing the reverse waste discharge section to detach from the supporting membrane together, thus realizing reverse waste discharge without starting waste.

2. The reverse waste discharge method as described in claim 1, characterized in that, The width of the waste discharge guide block is M. When M≥3.5mm, the waste discharge guide block connects two reverse waste discharge sections, and the far ends of the two reverse waste discharge sections are connected as one unit.

3. The reverse waste discharge method as described in claim 1, characterized in that, When the width of the waste discharge guide block is M, and 3.0mm≤M≤3.3mm, the waste discharge guide block is connected to a reverse waste discharge section.

4. The reverse waste discharge method as described in claim 3, characterized in that, The far ends of the reverse waste discharge sections extending from two adjacent waste discharge guide blocks are connected as one unit.

5. The reverse waste discharge method as described in claim 1, characterized in that, The area of ​​the waste discharge guide block is not less than 9mm². 2 Furthermore, the length and width of the waste discharge guide block are both not less than 3mm.

6. The reverse waste discharge method as described in claim 1, characterized in that, The inner membrane is an adhesive-impermeable polymer release membrane that covers only the area corresponding to the waste discharge guide block. It is used to block the bonding between the adhesive and the conductive substrate layer in this area, so that the waste discharge guide block can be controlled to peel off only through the upper waste discharge membrane.

7. The reverse waste discharge method as described in claim 1, characterized in that, The waste discharge membrane is a stretchable polyethylene membrane that can undergo elastic deformation along the waste copper path during the waste discharge process.

8. The reverse waste discharge method as described in claim 1, characterized in that, The reverse waste discharge section is a fine waste copper line connecting the pins of a semiconductor IC chip, with a width of ≤0.25mm, used to achieve physical die-cutting of a high-density interconnect structure.

9. The reverse waste discharge method as described in claim 1, characterized in that, The viscosity of the upper waste discharge film is lower than that of the carrier film, so that during the waste discharge process, the waste discharge guide block preferentially detaches from the bottom carrier film and adheres to the upper waste discharge film, while the copper foil in the effective circuit area remains stably bonded to the bottom carrier film.

10. The reverse waste discharge method as described in claim 9, characterized in that, The viscosity of the carrier membrane is 650-750 g / 25 mm; the viscosity of the waste membrane discharged above is 400-600 g / 25 mm.

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