A flexible, foldable plastic packaging method and structure

Abstract

The application relates to a flexible foldable plastic packaging method and structure, which comprises the following steps: plastic encapsulation and curing of a heterogeneous chip and / or a TSV chip, a rubber connecting belt and surface mounting on a temporary bonding carrier plate by using resin plastic encapsulation material, so as to form a reconfigured resin-based wafer; debonding of the temporary bonding carrier plate, and formation of a rewiring layer on the front surface of the reconfigured resin-based wafer by using a rewiring process; thinning of the back surface of the reconfigured resin-based wafer; POP stacking of a pre-encapsulated multi-chip assembly module and the rewiring layer on the reconfigured resin-based wafer by using a D2W flip chip process, and bottom filling and dicing, so as to form a final single flexible rubber packaging module. The application solves the problems that a traditional hard packaging material lacks flexibility and has weak anti-deformation capacity, and cannot meet the dynamic use requirements of devices.

Description

Technical Field

[0001] This invention relates to the field of integrated circuit packaging technology, and in particular to a flexible foldable plastic packaging method and structure. Background Technology

[0002] Currently, consumer electronics, wearable devices, flexible sensors, and automotive irregularly shaped devices are rapidly upgrading towards thinner, lighter, more flexible, and more portable designs. End products need to operate stably under dynamic conditions such as repeated bending, rolling, and twisting, and adapt to complex environments in multiple scenarios. Traditional rigid packaging materials lack flexibility and have weak deformation resistance, which cannot meet the dynamic usage requirements of devices. At the same time, conventional packaging solutions cannot balance lightweighting, protection, and structural adaptability. Flexible packaging has become a core requirement to break through product form limitations and improve the environmental adaptability and service life of devices. Flexible rubber and bendable plastic packaging have excellent flexibility, easy molding, and controllable cost characteristics, which meet the packaging application requirements of various flexible and irregularly shaped devices. Both the market and technology urgently need high-performance flexible rubber and bendable plastic packaging technology to support industrial upgrading.

[0003] Flexible electronic packaging has overturned the rigid form of traditional electronic systems and is considered one of the areas most likely to achieve disruptive technological innovation. However, existing packaging structures suffer from problems such as insufficient flexibility of pure plastics leading to easy breakage, poor adhesion of traditional rubber packaging interfaces, low substrate matching, delamination and warping of packaging layers after repeated bending, and mismatch of thermal expansion coefficients.

[0004] Therefore, the present invention urgently needs to propose a flexible and foldable plastic packaging method and structure to solve the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of this invention is to provide a flexible and foldable plastic encapsulation method and structure to solve the problems of traditional rigid encapsulation materials lacking flexibility and having weak resistance to deformation, thus failing to meet the dynamic usage requirements of devices.

[0006] To address the aforementioned technical problems, this invention provides a flexible, foldable plastic encapsulation method, comprising: Heterogeneous chips and / or TSV chips, along with rubber connecting tapes, are surface-mounted on a temporary bonding substrate using resin molding compound to form a reconstructed resin-based wafer. By debonding the temporary bonding substrate and forming a redistribution layer on the front side of the reconstructed resin-based wafer using a redistribution process, the redistribution layer only covers the edge area of ​​the rubber connecting strip, so that the other areas of the rubber connecting strip form windows. The back side of the reconstructed resin-based wafer is thinned to remove the silicon wafer on the back side of the resin molding compound and the rubber connector until the pyrolytic bonding film on the back side of the rubber connector is exposed. The film is then removed by a pyrolysis machine to expose the rubber connector. Using the D2W flip-chip process, a pre-encapsulated multi-chip component module is POP-stacked with the redistribution layer on the reconstructed resin-based wafer, and underfilling and dicing are performed to form the final single flexible rubber encapsulation module.

[0007] Preferably, the rubber connecting strip includes: a rubber matrix and an ultra-fine wire; the ultra-fine wire is pre-embedded and positioned inside the rubber matrix, and the rubber matrix includes a rectangular base block and connecting ribs; a plurality of connecting ribs are symmetrically arranged on both sides of the rectangular base block, and the lengths of the plurality of connecting ribs are arranged in an equal or alternating manner.

[0008] Preferably, the rubber matrix is ​​made of silicone rubber or fluororubber, and an ultra-fine wire with a diameter of 30μm to 50μm is pre-embedded and positioned inside it. The ultra-fine wire is a wire bundle composed of enameled copper wire core, silver-plated copper wire core or flexible printed circuit micro wire core and an outer high-temperature resistant polyimide insulation layer; and is integrally formed with the rubber matrix through molding and vulcanization processes, and then laser-cut into the required shape.

[0009] Preferably, the substrate material of the heterogeneous chip includes Si, GaAs, GaN, SiC, or diamond.

[0010] Preferably, the redistribution process employs a wafer-level redistribution process with multiple overlaps of metal and passivation layers; the redistribution layer has at least one layer; the thickness of the passivation layer is greater than the thickness of the formed metal layer, and the passivation layer covers the metal layer.

[0011] Preferably, the thickness of the metal layer is ≥2μm and the thickness of the passivation layer is ≥3μm.

[0012] Preferably, the thickness of a single-layer module in the POP stack of the pre-molded multi-chip component module is ≤500μm, and the flip-chip soldering of the D2W flip-chip process adopts reflow soldering or thermocompression soldering.

[0013] Preferably, the solder ball bump material on the redistribution layer and the pre-molded multi-chip component module includes CuNiSnAg, SnPb, or SnAgCu; the underfilling includes filling the gaps between the solder ball bumps of the D2W flip chip process with underfill adhesive, and the filling method includes pressing dry film process or dispensing process.

[0014] Preferably, the single-layer module of the POP stack also includes a pluggable module with an information exchange interface; the molded chip in the multi-chip component module adopts a heterogeneous chip and / or a TSV chip.

[0015] The present invention also provides a flexible foldable plastic packaging structure, which is prepared by means of a flexible foldable plastic packaging method as described above.

[0016] Compared with the prior art, the present invention has the following advantages: This invention utilizes rubber connecting strips that can be cut into any shape as needed, enabling various encapsulation methods with heterogeneous chips and TSV chips. It supports dynamic conditions such as repeated bending, rolling, and twisting, adapting to complex environments in multiple scenarios. Furthermore, it employs mid-stage wafer reconstruction, rewiring, and stacking processes for POP encapsulation, significantly increasing encapsulation density and reducing encapsulation volume. Simultaneously, it solves problems such as poor interface adhesion, low substrate compatibility, delamination and warping of encapsulation layers after repeated bending, and mismatched thermal expansion coefficients in traditional rubber encapsulation. Moreover, the flexible rubber possesses excellent elasticity, sealing properties, and deformation adaptability. Combined with the support of a bendable plastic structure, and utilizing internally embedded ultra-fine wires, it achieves electrical signal interconnection between heterogeneous chips, TSV chips, and multi-chip component modules. It supports cutting into any shape as needed, adapting to different encapsulation designs, and can perfectly meet the precise encapsulation requirements of miniaturized high-density integrated devices, perfectly solving the pain points of encapsulation reliability and adaptability. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of wafer-level packaging provided by the present invention.

[0018] Figure 2 This is a schematic diagram of the wafer-level molding process provided by the present invention.

[0019] Figure 3 This is a schematic diagram of wafer-level redistribution provided by the present invention.

[0020] Figure 4 This is a schematic diagram of resin wafer thinning provided by the present invention.

[0021] Figure 5 This is a schematic diagram of the flip-chip stacking of the packaging modules provided by the present invention.

[0022] Figure 6 This is a schematic diagram of the final single flexible rubber encapsulation module formed by wafer-level underfill according to the present invention.

[0023] Figure 7 This is a schematic diagram of the flexible rubber connecting strip provided by the present invention; wherein (a) is a schematic diagram of the connecting ribs being arranged in an equal length manner; and (b) is a schematic diagram of the connecting ribs being arranged in an alternating long and short manner.

[0024] In the figure: 111-Rubber substrate, 112-Ultra-fine wires, 113-Temporary bonding carrier, 114-Rubber connecting strip, 115-Silicon wafer, 116-Heterogeneous chips and / or TSV chips, 117-Resin molding compound, 118-Rewiring layer, 119-Multi-chip module, 120-Underfill. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer from the following description. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0026] like Figures 1 to 7 As shown in the figure, this embodiment of the invention specifically provides a flexible foldable plastic packaging method, which includes the following steps: Provides heterogeneous chips and / or TSV chips 116, rubber connecting strips 114, resin molding compound 117, and temporary bonding carrier 113. The temporary bonding carrier 113 for packaging is formed by attaching a pyrolytic bonding film to a steel carrier. A silicone wafer 115 is attached to the back of the rubber connecting strip 114 to fix its position and facilitate wafer mounting; like Figure 1 As shown, a die-loading machine is used to load heterogeneous chips and / or TSV chips 116 (such as...). Figure 1 The chips Die-1, Die-2, Die-3, and Die-4 are mounted on the surface of the rubber connecting strip 114 on the temporary bonding carrier 113; the back side of the rubber connecting strip 114 also includes a pyrolytic bonding film and a silicon wafer 115 arranged sequentially. like Figure 2 As shown, through a wafer-level molding process, a heterogeneous chip, a TSV chip, and a rubber connecting strip are encapsulated with resin molding compound 117 and cured to form a reconstructed resin-based wafer. like Figure 3 As shown, the reconstructed resin-based wafer is detached from the temporary bonding carrier 113 by a debonding process. The metal redistribution layer 118 of the RDL and UBM multilayer interconnect is realized sequentially using polyimide insulating adhesive and wafer-level multilayer redistribution process. The rubber connecting strip 114 is partially open and does not cover the redistribution layer 118. like Figure 4 As shown, the resin molding compound 117 and silicon wafer 115 on the back of the rubber connector 114 are ground off by a wafer-level thinning process to expose the bonding film. Then, the film is removed by a pyrolysis machine to expose the rubber connector 114. like Figure 5As shown, the pre-encapsulated multi-chip module 119 is stacked in POP using the D2W flip-chip process; like Figure 6 As shown, by performing underfill to form underfill adhesive 120, the reconstructed resin-based wafer is divided into individual pieces to form the final flexible rubber encapsulation module.

[0027] like Figure 7 As shown, the rubber connecting strip 114 includes: a rubber substrate 111 and an ultra-fine wire 112; the ultra-fine wire 112 is pre-embedded and positioned inside the rubber substrate 111, and the rubber substrate 111 includes a rectangular base block and connecting ribs; several connecting ribs are symmetrically arranged on both sides of the rectangular base block, and the lengths of the connecting ribs are arranged in an equal or alternating manner. By distributing the stress generated during bending to multiple independent connecting ribs, the problem of rubber cracking and wire breakage caused by stress concentration is avoided, effectively improving the bending life of the encapsulation structure; the use of connecting ribs of equal length can achieve uniform symmetrical bending; the use of connecting ribs of alternating lengths can achieve asymmetrical torsion at any angle.

[0028] In a preferred embodiment of the present invention, the rubber substrate 111 of the rubber connecting strip 114 is made of silicone rubber or fluororubber, and 30~50μm ultrafine wires 112 are embedded inside. The ultrafine wires 112 include enameled copper wire cores, silver-plated copper wire cores, flexible printed circuit micro wire cores, etc. The wire cores are covered with a high-temperature resistant polyimide insulation layer. They are pre-positioned by mold, vulcanized and integrally formed with the rubber substrate, and then laser-cut into special shapes.

[0029] The rubber connecting strip 114 acts as a flexible load-bearing skeleton to support the encapsulation structure, enabling repeated bending at ±180°, 360° curling, and arbitrary angle twisting to ensure the stability of internal electrical connections. It also utilizes the high elasticity of rubber to absorb deformation stress, solving the problems of poor interface adhesion and mismatch of thermal expansion coefficients in traditional rubber encapsulation, and avoiding failure phenomena such as delamination and edge warping after repeated bending. The internally embedded ultra-fine wires enable electrical signal interconnection between heterogeneous chips, TSV chips, and multi-chip component modules, and can be cut into any shape according to requirements to adapt to different encapsulation designs.

[0030] In a preferred embodiment of the present invention, a silicon wafer 115 is attached to the back of the rubber connecting strip 114 via a pyrolytic bonding film. A special temporary substrate is used to attach the pyrolytic bonding film to the substrate.

[0031] In a preferred embodiment of the present invention, the substrate material of the heterogeneous chip includes substrates such as Si, GaAs, GaN, SiC, and diamond. In a preferred embodiment of the present invention, the wafer-level multilayer redistribution process is a redistribution process in which metal layers and passivation layers overlap multiple times. The redistribution layer 118 has at least one layer; the thickness of the passivation layer is greater than that of the formed metal layer, and the passivation layer covers the metal layer; the thickness of each metal layer is not less than 2 μm, and the thickness of each passivation layer is not less than 3 μm.

[0032] In a preferred embodiment of the present invention, the D2W flip chip has an upper POP stack module thickness ≤ 500μm, the upper POP stack module has a pluggable module with an information exchange interface, and the plastic-encapsulated chip in the multi-chip component module adopts heterogeneous chips and / or TSV chips (such as...). Figure 6 The materials for the solder bumps on the redistribution layer 118 and the wiring layer on the POP stack module include CuNiSnAg, SnPb, SnAgCu, etc.; the flip-chip bonding method with the reconstructed wafer is reflow soldering or thermoforming; the gaps between the solder bumps of the flip-chip bonding are filled by underfill 120, and the underfilling method includes pressing dry film process and dispensing process.

[0033] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A flexible, foldable plastic encapsulation method, characterized in that, include: Heterogeneous chips and / or TSV chips, along with rubber connecting tapes, are surface-mounted on a temporary bonding substrate using resin molding compound to form a reconstructed resin-based wafer. By debonding the temporary bonding substrate and forming a redistribution layer on the front side of the reconstructed resin-based wafer using a redistribution process, the redistribution layer only covers the edge area of ​​the rubber connecting strip, so that the other areas of the rubber connecting strip form windows. The back side of the reconstructed resin-based wafer is thinned to remove the silicon wafer on the back side of the resin molding compound and the rubber connector until the pyrolytic bonding film on the back side of the rubber connector is exposed. The film is then removed by a pyrolysis machine to expose the rubber connector. Using the D2W flip-chip process, a pre-encapsulated multi-chip component module is POP-stacked with the redistribution layer on the reconstructed resin-based wafer, and underfilling and dicing are performed to form the final single flexible rubber encapsulation module.

2. The flexible foldable plastic packaging method as described in claim 1, characterized in that, The rubber connecting strip includes: a rubber substrate and an ultra-fine wire; the ultra-fine wire is pre-embedded and positioned inside the rubber substrate, and the rubber substrate includes a rectangular base block and connecting ribs; a plurality of connecting ribs are symmetrically arranged on both sides of the rectangular base block, and the lengths of the plurality of connecting ribs are arranged in an equal or alternating manner.

3. The flexible foldable plastic packaging method as described in claim 2, characterized in that, The rubber matrix is ​​made of silicone rubber or fluororubber, and ultra-fine wires with a diameter of 30μm to 50μm are pre-embedded and positioned inside it. The ultra-fine wires are wire bundles composed of enameled copper wire cores, silver-plated copper wire cores or flexible printed circuit micro wire cores and an outer high-temperature resistant polyimide insulation layer. They are integrally formed with the rubber matrix through molding and vulcanization processes, and then laser-cut into the required shape.

4. The flexible foldable plastic packaging method as described in claim 1, characterized in that, The substrate material of the heterogeneous chip includes Si, GaAs, GaN, SiC, or diamond.

5. The flexible foldable plastic packaging method as described in claim 1, characterized in that, The redistribution process employs a wafer-level redistribution process with multiple overlapping of metal and passivation layers; the redistribution layer has at least one layer; the thickness of the passivation layer is greater than the thickness of the formed metal layer, and the passivation layer covers the metal layer.

6. The flexible foldable plastic packaging method as described in claim 5, characterized in that, The thickness of each metal layer is ≥2μm, and the thickness of each passivation layer is ≥3μm.

7. The flexible foldable plastic packaging method as described in claim 1, characterized in that, The thickness of a single-layer module in the pre-molded multi-chip component module POP stack is ≤500μm, and the flip-chip soldering of the D2W flip-chip process adopts reflow soldering or thermocompression soldering.

8. A flexible foldable plastic packaging method as described in claim 1, characterized in that, The solder ball bump material on the redistribution layer and the pre-molded multi-chip component module includes CuNiSnAg, SnPb or SnAgCu; the underfilling includes filling the gaps between the solder ball bumps of the D2W flip chip process with underfill adhesive, and the filling method includes pressing dry film process or dispensing process.

9. A flexible foldable plastic packaging method as described in claim 1, characterized in that, The single-layer module of the POP stack also includes a pluggable module with an information exchange interface; the plastic-encapsulated chip in the multi-chip component module adopts heterogeneous chips and / or TSV chips.

10. A flexible, foldable plastic encapsulation structure, characterized in that, It is prepared by using a flexible foldable plastic encapsulation method as described in any one of claims 1 to 9.

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