Package Structure of Ultra-Thin Chip and Flexible Integrated Packaging Method

Abstract

The present invention provides a packaging structure for an ultra-thin chip and a flexible integrated packaging method. The packaging structure of the ultra-thin chip includes: a wiring layer; a flexible printed circuit board dielectric layer, which is disposed on the surface of the wiring layer and is provided with slots and vias; an ultra-thin chip, which is disposed in the slot, and there is a gap between the edge of the ultra-thin chip and the inner wall of the slot; a polyimide cover film, which is disposed on the surface of the ultra-thin chip away from the wiring layer and fills the gap; and a connection electrode, which electrically connects the ultra-thin chip and the wiring layer through the via. Thus, the interconnection between the ultra-thin chip and the wiring layer of the flexible printed circuit board can be effectively achieved, and the interconnection reliability is relatively high. It can achieve bending and deformation in space, and the overall thickness of the packaging structure is relatively thin. Moreover, the embedded flexible integrated packaging of a single or multiple ultra-thin chips can be realized.

Description

Technical Field

[0001] The present invention relates to the field of packaging technology. Specifically, the present invention relates to a packaging structure for ultra-thin chips and a flexible integrated packaging method. Background Art

[0002] Currently, the mainstream packaging technologies for integrated circuit chips are wire bonding technology (WB) and flip chip technology (FC).

[0003] Wire bonding technology is the most widely used and the earliest interconnection technology. This technology has low cost and simple operation. Metal leads such as copper, gold, and silver are used to connect each stacked chip to the substrate. In order to ensure the accuracy and reliability of the interconnection effect, enough space must be left for the leads. As the chip stacking density increases, the lead space approaches the limit value, which will exacerbate signal congestion and interference, and even cause signal delay. Therefore, this technology is increasingly unable to meet the requirements of the current high-density packaging trend.

[0004] Flip chip connection technology evolves the electrical signal connection between the upper and lower chips from wire bonding to solder ball bonding. Solder ball bonding does not require pulling out long leads, greatly shortening the electrical connection path, which is beneficial to reducing resistance and inductance, enhancing the reliability of the connection, and also being more aesthetically pleasing. In high-density packaging structures, this technology has great advantages. However, the chip size of the flip chip technology is very small, and there are still significant challenges to obtain a good assembly rate.

[0005] Therefore, the interconnection method and packaging method for chips need to be further studied. Summary of the Invention

[0006] The present invention aims to solve at least one of the technical problems in the related art to some extent. For this reason, an object of the present invention is to provide a packaging structure for ultra-thin chips, in which the interconnection method between the ultra-thin chips and the flexible circuit board has high reliability, can achieve bending and deformation in space, or the overall thickness of the packaging structure is relatively thin.

[0007] In one aspect of the present invention, the present invention provides a packaging structure for an ultra-thin chip. According to an embodiment of the present invention, the packaging structure of the ultra-thin chip includes: a wiring layer; a flexible printed circuit board dielectric layer, the flexible printed circuit board dielectric layer is disposed on the surface of the wiring layer and is provided with slots and vias; an ultra-thin chip, the ultra-thin chip is disposed in the slot, and there is a gap between the edge of the ultra-thin chip and the inner wall of the slot; a flexible cover film, the flexible cover film is disposed on the surface of the ultra-thin chip away from the wiring layer and fills the gap; a connection electrode, the connection electrode electrically connects the ultra-thin chip and the wiring layer through the via. Thus, the interconnection between the ultra-thin chip and the wiring layer of the flexible printed circuit board can be effectively realized, and the interconnection reliability is relatively high, the bending and deformation in space can be realized, and the overall thickness of the packaging structure is relatively thin, and the embedded flexible integrated packaging of a single or multiple ultra-thin chips can also be realized.

[0008] According to an embodiment of the present invention, the packaging structure of the ultra-thin chip further includes: at least one copper pillar bump, at least one of the copper pillar bumps is disposed on the surface of the ultra-thin chip away from the wiring layer, and the connection electrode electrically connects the copper pillar bump and the wiring layer through the via.

[0009] According to an embodiment of the present invention, the surface of the copper pillar bump away from the wiring layer is flush with the surface of the flexible cover film away from the wiring layer.

[0010] According to an embodiment of the present invention, the width of the gap is 0.1 to 0.5 mm.

[0011] According to an embodiment of the present invention, only one ultra-thin chip is correspondingly disposed in each slot.

[0012] According to an embodiment of the present invention, the packaging structure of the ultra-thin chip further includes: an adhesive film, the adhesive film is disposed on the surface of the ultra-thin chip close to the wiring layer.

[0013] According to an embodiment of the present invention, the packaging structure of the ultra-thin chip further includes: a first protective layer, the first protective layer covers the connection electrode, the flexible cover film and the surface of the flexible printed circuit board dielectric layer away from the wiring layer; a second protective layer, the second protective layer covers the surface of the wiring layer away from the ultra-thin chip, and the surface of the flexible printed circuit board dielectric layer away from the first protective layer and not covered by the wiring layer.

[0014] According to an embodiment of the present invention, the first protective layer has an opening, the opening exposes at least a part of the surface of the connection electrode, and the packaging structure of the ultra-thin chip further includes: a metal layer, the metal layer is disposed in the opening.

[0015] In another aspect of the present invention, the present invention provides a flexible integrated packaging method for an ultra-thin chip. According to an embodiment of the present invention, the flexible integrated packaging method for the ultra-thin chip includes: providing a flexible printed circuit board, the flexible printed circuit board including a flexible printed circuit board dielectric layer and a wiring layer, and a slot being provided in the flexible printed circuit board dielectric layer; attaching the ultra-thin chip in the slot, and a gap being formed between an edge of the ultra-thin chip and an inner wall of the slot; forming a flexible cover film on a surface of the ultra-thin chip away from the wiring layer, and filling the gap with the flexible cover film; forming a through hole penetrating the flexible printed circuit board dielectric layer in the flexible printed circuit board dielectric layer, and at least a part of the wiring layer being exposed by the through hole; forming an electrode material layer on a surface of the flexible cover film away from the flexible printed circuit board dielectric layer and performing a patterning process to obtain a connection electrode, and the connection electrode electrically connecting the ultra-thin chip and the wiring layer through the through hole. Thus, the above flexible integration method is not only easy to implement and industrially produce, but also can effectively realize the interconnection between the ultra-thin chip and the wiring layer of the flexible printed circuit board, and the interconnection reliability is relatively high, capable of realizing bending and deformation in space, and the overall thickness of the packaging structure is relatively thin, and it can also realize the embedded flexible integrated packaging of a single or multiple ultra-thin chips.

[0016] According to an embodiment of the present invention, the ultra-thin chip is attached in the slot through an adhesive film.

[0017] According to an embodiment of the present invention, the step of forming the flexible cover film includes: coating a liquid flexible material on a surface of the ultra-thin chip away from the wiring layer, filling the gap with the liquid flexible material, and then curing the liquid flexible material by baking to obtain the flexible cover film.

[0018] According to an embodiment of the present invention, the flexible integrated packaging method for the ultra-thin chip further includes: forming a first protective layer on surfaces of the connection electrode, the flexible cover film, and the flexible printed circuit board dielectric layer away from the wiring layer; forming a second protective layer on a surface of the wiring layer away from the ultra-thin chip and on a surface of the flexible printed circuit board dielectric layer away from the first protective layer and not covered by the wiring layer.

[0019] According to an embodiment of the present invention, an opening is formed in the first protective layer, at least a part of a surface of the connection electrode being exposed by the opening, and the method further includes: forming a metal layer in the opening. Description of the Drawings

[0020] Figure 1 is a schematic cross-sectional view of a packaging structure of an ultra-thin chip according to an embodiment of the present invention;

[0021] Figure 2Schematic cross-sectional view of the packaging structure of an ultra-thin chip according to another embodiment of the present invention;

[0022] Figure 3 Schematic cross-sectional view of the packaging structure of an ultra-thin chip according to another embodiment of the present invention;

[0023] Figure 4 Schematic cross-sectional view of the packaging structure of an ultra-thin chip according to another embodiment of the present invention;

[0024] Figure 5 Schematic flow chart of a flexible integrated packaging method for an ultra-thin chip according to an embodiment of the present invention;

[0025] Figure 6 Schematic cross-sectional view of the product structure of each step of a flexible integrated packaging method according to an embodiment of the present invention;

[0026] Figure 7 Schematic cross-sectional view of the product structure of each step of a flexible integrated packaging method according to an embodiment of the present invention. Detailed implementation manners

[0027] The embodiments of the present invention will be described in detail below. The described embodiments are exemplary only for explaining the present invention and should not be construed as limiting the present invention. For those not specified in the embodiments regarding specific technologies or conditions, they shall be carried out according to the technologies or conditions described in the literature in this field or according to the product specifications. For those materials not specified regarding the manufacturers, they are all conventional products that can be obtained through commercial purchase.

[0028] In one aspect of the present invention, the present invention provides a packaging structure for an ultra-thin chip. According to an embodiment of the present invention, with reference to Figure 1, the packaging structure of the ultra-thin chip includes: a wiring layer 10; a flexible printed circuit board dielectric layer 20, which is disposed on the surface of the wiring layer 10 and is provided with a slot 21 and a via hole 22; an ultra-thin chip 30, which is disposed in the slot 21 and has a gap 23 between the ultra-thin chip 30 and the inner wall of the slot 21; a flexible cover film 40, which is disposed on the surface of the ultra-thin chip 30 away from the wiring layer 10 and fills the gap 23; a connecting electrode 50, which electrically connects the ultra-thin chip 30 and the wiring layer 10 through the via hole 22. Thus, the interconnection between the ultra-thin chip 30 and the wiring layer of the flexible printed circuit board can be effectively realized, and the interconnection reliability is relatively high, and bending and deformation in space can be achieved; moreover, by providing the slot 21 and embedding the ultra-thin chip 30 in the slot 21 of the flexible printed circuit board dielectric layer 20, the thickness of the packaging structure can be greatly reduced, and an ultra-thin system-in-package product can be realized; furthermore, the embedded flexible integrated packaging of a single or multiple ultra-thin chips 30 can be realized; moreover, the flexible printed circuit board dielectric layer 20 and the flexible cover film 40 used in the packaging structure both have good flexibility, so that flexible packaging can be truly realized, and the ultra-thin chip 30 also has a certain degree of flexibility, so that the flexibility of the entire product can be achieved.

[0029] With the upgrading of electronic products, the flexible printed circuit board (FPC) caters to the development trend of light, thin, short, and small electronic products with its unique advantages and plays an important cornerstone role in the field of the electronic information industry. The flexible printed circuit board is also called a flexible circuit board or a flexible printed circuit board, and has the advantages of high wiring density, light weight, thin thickness, good bendability, and less wiring space limitation, which fully conforms to the development trend of electronic products and is an effective solution to meet the miniaturization of electronic products. The FPC can not only be freely bent, wound, and folded, and can withstand millions of dynamic bends without damaging the wires, but also can be assembled arbitrarily according to the requirements of the spatial layout and move and stretch arbitrarily in three-dimensional space, so as to achieve the effect of integrating component assembly and wire connection.

[0030] Based on the characteristics of the flexible printed circuit board, the present invention combines the manufacturing process of the flexible printed circuit board and the manufacturing process of the chip integrated circuit, uses the flexible printed circuit board dielectric layer 20 as a packaging substrate, embeds the ultra-thin chip 30 in the slot 21 of the packaging substrate, and then performs flexible packaging treatment. The via hole 22 is made on the flexible printed circuit board dielectric layer 20 by laser ablation, and then circuit wiring is performed on the flexible material on the surface of the chip by sputtering electroplating and photolithography, so that the ultra-thin chip 30 is interconnected with the wiring layer 10 on the back surface of the flexible printed circuit board dielectric layer 20, thereby realizing the integrated flexible packaging of a single or multiple ultra-thin chips 30 and further realizing the flexibility of the entire product.

[0031] According to an embodiment of the present invention, there is no restrictive requirement for the specific manner in which the connecting electrode 50 is electrically connected to the wiring layer 10, and those skilled in the art can flexibly select according to the actual situation. In some embodiments, the connecting electrode 50 is electrically connected to the wiring layer 10 by direct contact; in other embodiments, the connecting electrode 50 is electrically connected to the wiring layer 10 through a pad (not shown in the figure), that is, a pad is provided on the surface of the wiring layer 10 that is electrically connected to the connecting electrode 50, and the connecting electrode 50 is in contact connection with the pad through the via hole 22 to achieve the electrical connection between the connecting electrode 50 and the wiring layer 10.

[0032] In some specific examples of the present invention, the encapsulation structure may include a plurality of ultra-thin chips 30, and the plurality of ultra-thin chips 30 are arranged in the slotted opening 21 in a non-stacked manner, and preferably only one ultra-thin chip 30 is provided corresponding to one slotted opening 21, that is, the plurality of ultra-thin chips 30 correspond to a plurality of slotted openings 21 (that is, a plurality of slotted openings 21 are spaced apart in the flexible circuit board dielectric layer), and one ultra-thin chip 30 is provided in each slotted opening 21. In this way, a plurality of ultra-thin chips 30 are arranged in the horizontal direction of the flexible circuit board dielectric layer 20, so that the thickness of the more complex integrated encapsulation structure can still be below 100 microns.

[0033] According to another embodiment of the present invention, referring to Figure 2 , the encapsulation structure of the ultra-thin chip 30 further includes: at least one copper pillar bump 31, at least one copper pillar bump 31 is provided on the surface of the ultra-thin chip 30 away from the wiring layer 10, and the connecting electrode 50 electrically connects the copper pillar bump 31 and the wiring layer 10 through the via hole 22. Thus, the ultra-thin chip 30 is mounted upright in the slotted opening 12, and the interconnection between the ultra-thin chip 30 and the flexible circuit board is realized through the copper pillar bump 31, opening up a new interconnection method, thereby realizing the design of the integrated circuit. Compared with the wire bonding and flip-chip soldering technologies, the reliability of this interconnection method is better, and it can effectively realize bending and deformation in space.

[0034] According to an embodiment of the present invention, referring to Figure 2 , the surface of the copper pillar bump 31 away from the wiring layer 10 is flush with the surface of the flexible cover film 40 away from the wiring layer 10. Thus, it is convenient for the contact connection between the copper pillar bump 31 and the connecting electrode 50, and the process difficulty can be reduced in the manufacturing process.

[0035] According to an embodiment of the present invention, referring to Figure 2, the width D of the gap 23 is 0.1 - 0.5 mm, such as 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm (i.e., the length and width dimensions of the slotted opening 21, specifically for example the length or width, etc., are both larger than twice the width D of the gap compared to the length and width dimensions of the ultra-thin chip 30). Thus, it is beneficial for the ultra-thin chip 30 to be fitted into the slotted opening 21, and it is also beneficial to fill the gap 23 with a flexible covering film 40 of an appropriate width to improve the bendability of the packaging structure.

[0036] According to an embodiment of the present invention, there is no special requirement for the thickness of the flexible printed circuit board dielectric layer 20, and those skilled in the art can flexibly set it according to the thickness of the ultra-thin chip 30 and the copper pillar bumps 31. In some embodiments, the thickness of the flexible printed circuit board dielectric layer is equivalent to the total thickness of the ultra-thin chip and the copper pillar bumps, which is beneficial for realizing the ultra-thinness of the packaging structure. In some embodiments, the thickness of the ultra-thin chip is within 50 microns, and the thickness of the copper pillar bumps 31 is 5 - 10 microns. Thus, it is beneficial for realizing the ultra-thin design of the packaging structure.

[0037] According to an embodiment of the present invention, the thickness of the connection electrode 50 is 1 - 10 microns, such as 1 micron, 3 microns, 4 microns, 5 microns, 6 microns, 7 microns, 8 microns or 10 microns. Thus, the connection electrode 50 with the above thickness can not only ensure the stability and reliability of the circuit connection, but also have little impact on the overall flexibility of the packaging structure of the ultra-thin chip 30, ensuring the effective bending and deformation of the packaging structure in space. It should be noted that the thickness of the connection electrode 50 here refers to the thickness of the connection electrode 50 on the surface of the flexible printed circuit board dielectric layer 20 and the surface of the flexible covering film 40, rather than the thickness of the connection electrode 50 in the through hole 22.

[0038] According to an embodiment of the present invention, there is no special requirement for the specific material of the flexible covering film, as long as it has good flexibility. Those skilled in the art can flexibly select according to the actual situation. For example, the material of the flexible covering film includes but is not limited to polyimide (PI), which not only has better flexibility, but also has good properties such as stability and moisture resistance.

[0039] According to an embodiment of the present invention, referring to Figure 3 , the packaging structure of the ultra-thin chip 30 further includes: an adhesive film 60, and the adhesive film 60 is disposed on the surface of the ultra-thin chip 30 close to the wiring layer 10. Thus, the stability of the ultra-thin chip 30 can be strengthened. In some embodiments, the ultra-thin chip 30 with copper pillar bumps 31 can be attached to the slotted opening 21 of the flexible printed circuit board dielectric layer 20 by a mounter, where the fitting accuracy of the mounter is ±10 microns. Thus, the integration of the fabricated flexible packaging structure is higher.

[0040] According to an embodiment of the present invention, referring to Figure 4, the packaging structure of the ultra-thin chip further includes: a first protective layer 70 covering the connecting electrodes 50, the flexible covering film 40, and the surface of the flexible printed circuit board dielectric layer 20 away from the wiring layer 10; a second protective layer 80 covering the surface of the wiring layer 10 away from the ultra-thin chip 30, and the surface of the flexible printed circuit board dielectric layer 20 away from the first protective layer 70 and not covered by the wiring layer 10. In this way, the packaging structure can obtain better physical properties, that is, it can effectively improve the flexibility of the packaging structure, prevent the connecting electrodes 50 and the wiring layer 10 from being scratched during the packaging process, and is moisture-proof and moisture-resistant.

[0041] According to an embodiment of the present invention, referring to Figure 4 , the first protective layer 70 has an opening exposing at least a part of the surface of the connecting electrode 50. The packaging structure of the ultra-thin chip further includes: a metal layer 90 disposed in the opening. Thus, the metal layer 90 serves as the pad of the entire packaging structure, enabling the packaging structure to obtain better electrical performance.

[0042] According to an embodiment of the present invention, there are no special requirements for the specific materials of the above-mentioned wiring layer 10, flexible printed circuit board dielectric layer 20, connecting electrodes 50, bonding film 60, first protective layer 70, second protective layer 80, metal layer 90, etc. Those skilled in the art can flexibly select according to the actual situation. For example, the material of the wiring layer 10 includes but is not limited to copper, the material of the flexible printed circuit board dielectric layer 20 includes but is not limited to polyimide, the material of the connecting electrodes 50 includes but is not limited to copper, the material of the bonding film 60 includes but is not limited to die attach materials (DAF), the materials of the first protective layer 70 and the second protective layer 80 include but are not limited to polyimide (CVL, Coverlay), and the material of the metal layer 90 includes but is not limited to copper.

[0043] In another aspect of the present invention, the present invention provides a flexible integrated packaging method for an ultra-thin chip. According to an embodiment of the present invention, referring to Figure 5 , the flexible integrated packaging method for the ultra-thin chip includes:

[0044] S100: Provide a flexible printed circuit board, which includes a flexible printed circuit board dielectric layer 20 and a wiring layer 10, and a slot 21 is provided in the flexible printed circuit board dielectric layer 20. The structural schematic diagram refers to 6 and Figure 7 .

[0045] In this step, provide a flexible printed circuit board, on one side surface of the flexible printed circuit board dielectric layer 20 of the flexible printed circuit board, a wiring layer 10 is formed, and the flexible printed circuit board dielectric layer 20 is formed with a slot 21. And the product structural schematic diagram of this step refers to Figure 6 (b) of. In some embodiments of the present invention, referring to Figure 6For (a), common flexible substrate materials can be directly used, or a whole layer of metal material layer 100 can be sputtered on the back of the flexible printed circuit board dielectric layer 20 first, and then patterned to form the design shape of the wiring layer 10. Among them, the patterning step can be set after step S500 or carried out in step S100.

[0046] Among them, there are no restrictive requirements for the specific method of the slot 21. Those skilled in the art can flexibly select according to the actual situation. In some embodiments, the flexible printed circuit board dielectric layer 20 is laser-radiated to obtain a slot 21 with appropriate dimensions. Among them, the intensity of the laser radiation can be flexibly set by those skilled in the art according to the actual situation such as the thickness and forming material of the dielectric layer, and will not be elaborated here too much.

[0047] S200: Bond the ultra-thin chip 30 in the slot 21, and there is a gap 23 between the edge of the ultra-thin chip 30 and the inner wall of the slot 21. Refer to the structural schematic diagram in Figure 6 (c).

[0048] In this step, the ultra-thin chip 30 can be bonded in the slot 21 of the flexible printed circuit board dielectric layer 20 by a bonding machine with high bonding accuracy, so that the ultra-thin chip 30 is pasted on the metal material layer 100 through the bonding film 60 (as shown in Figure 6 (c)). Among them, the bonding accuracy of the bonding machine is ±10 microns. Thus, the integration of the fabricated flexible packaging structure is higher.

[0049] Among them, referring to (c) in the figure, copper pillar bumps 31 are arranged on the surface of the ultra-thin chip far from the metal material layer 100 for subsequent interconnection with the wiring layer 10 of the flexible printed circuit board. And the ultra-thin chip 30 is mounted upright in the slot 12, and the interconnection between the ultra-thin chip 30 and the flexible printed circuit board is realized through the copper pillar bumps 31, opening up a new interconnection method, thereby realizing the design of the integrated circuit. Compared with the wire bonding and flip-chip soldering technologies, the reliability of this interconnection method is better, and it can effectively realize bending and deformation in space.

[0050] S300: Form a flexible cover film 40 on the surface of the ultra-thin chip 30 far from the wiring layer 10 (which can be the metal material layer 100 at this time), and make the flexible cover film 40 fill the gap 23. Refer to the structural schematic diagram in Figure 6 (d) and (e).

[0051] In this step, a liquid flexible material is coated on the surface of the ultra-thin chip 30 away from the wiring layer 10 (which can be the metal material layer 100 at this time), and the liquid flexible material fills the gap 23. Then, a solid flexible material 400 is obtained through baking and curing. Due to process reasons, it is difficult to make the surface of the copper pillar bump 31 away from the metal material layer 100 flush with the surface of the solid flexible material 400 away from the wiring layer 10. Therefore, when coating, the solid flexible material 400 usually protrudes above the surface of the copper pillar bump 31 away from the metal material layer 100 (as shown in (d) of Figure 6 ). Therefore, after curing the liquid flexible material, the solid flexible material 400 will be further etched to remove a certain thickness of the solid flexible material 400 to obtain the flexible cover film 40, and the flexible cover film 40 exposes the surface of the copper pillar bump 31.

[0052] The above flexible material can be polyimide (PI). This material not only has better flexibility but also has good properties such as stability and moisture resistance. Among them, there are no restrictive requirements for the specific conditions (such as curing temperature) for curing the liquid PI. Those skilled in the art can flexibly select the conventional curing conditions in the art according to the actual situation, and details will not be elaborated here. Among them, the step of exposing the surface of the copper pillar bump 31 through etching can be carried out directly after curing (that is, before forming the through hole 22), or can be carried out after forming the through hole 22 (such as shown in (e) and (f) of Figure 6 ), and there are no restrictive requirements here.

[0053] According to an embodiment of the present invention, referring to (f) of Figure 6 , after exposing the surface of the copper pillar bump 31 through etching, the surface of the copper pillar bump 31 away from the wiring layer 10 is flush with the surface of the flexible cover film 40 away from the wiring layer 10. Thus, it is convenient for the contact connection between the copper pillar bump 31 and the connection electrode 50, and the process difficulty can be reduced in the manufacturing process.

[0054] S400: A through hole 22 penetrating the flexible circuit board dielectric layer 20 is formed in the flexible circuit board dielectric layer 20, and the through hole 22 exposes at least a part of the wiring layer 10 (which can be the metal material layer 100 at this time). The structural schematic diagram refers to (e) and (f) of Figure 6 . The interconnection with the copper pillar bump 31 of the ultra-thin chip 30 is realized through the through hole 22, so that the ultra-thin chip 30 and the flexible circuit board form a complete integrated circuit.

[0055] In this step, the through hole 22 can be obtained by laser drilling. In this way, the process is mature and the manufacturing accuracy is relatively high. After forming the through hole 22, a plasma device is used to etch the solid polyimide 400, so that the surface of the copper pillar bump 31 is exposed, as shown in (f) of Figure 6 .

[0056] S500: An electrode material layer 500 is formed on the surface of the flexible cover film 40 away from the flexible circuit board dielectric layer 20 and patterned to obtain connection electrodes 50. The connection electrodes 50 electrically connect the ultra-thin chip 30 and the wiring layer 10 (which can be the metal material layer 100 at this time) through through-holes 22. For the structural schematic diagram, refer to Figure 7 Figures (a) and (b) in

[0057] In this step, the electrode material layer 500 fills the through-holes 22, and an electrode material layer 500 with a thickness of 1 - 10 microns is formed on the surface of the flexible circuit board. One end of the connection electrode 50 formed after patterning is connected to the wiring layer 10 through the through-hole 22, and the other end is electrically connected to the exposed surface of the copper pillar bump 31, thereby realizing the interconnection between the ultra-thin chip 30 and the flexible circuit board.

[0058] Among them, sputtering electroplating and photolithography can be used to form the electrode material layer 500. Those skilled in the art can make corresponding selections according to the specific material type of the electrode material layer 500, which will not be elaborated here.

[0059] According to an embodiment of the present invention, refer to Figure 7 , after obtaining the connection electrodes 50, the metal material layer 100 is patterned to obtain the wiring layer 10. There is no special requirement for the specific patterning method, for example, patterning can be performed by the method of exposure and development.

[0060] According to an embodiment of the present invention, refer to Figure 7 Figure (d) in

[0061] The flexible integrated packaging method for the ultra-thin chip further includes: forming a first protective layer 70 on the surfaces of the connection electrodes 50, the flexible cover film 40, and the flexible circuit board dielectric layer 20 away from the wiring layer 10; forming a second protective layer 80 on the surface of the wiring layer 10 away from the ultra-thin chip 30 and on the surface of the flexible circuit board dielectric layer 20 away from the first protective layer 70 and not covered by the wiring layer 10. In this way, the packaging structure can obtain better physical properties, that is, it can effectively improve the flexibility of the packaging structure, prevent the connection electrodes 50 and the wiring layer 10 from being scratched during the packaging process, and is moisture-proof and moisture-resistant. Figure 7 Figure 4 According to an embodiment of the present invention, refer to

[0062] Figure (d) in China andTherefore, the above flexible integration method is not only easy to implement and suitable for industrial production, but also can effectively realize the interconnection between the ultra-thin chip 30 and the wiring layer 10 of the flexible printed circuit board. Moreover, the interconnection reliability is relatively high, and it can achieve bending and deformation in space. By providing the slot 21 and embedding the ultra-thin chip 30 in the slot 21 of the flexible printed circuit board dielectric layer 20, the thickness of the packaging structure can be greatly reduced, and an ultra-thin system-in-package product can be realized. In addition, the embedded flexible integration packaging of a single or multiple ultra-thin chips 30 can be achieved. Furthermore, both the flexible printed circuit board dielectric layer 20 and the flexible cover film 40 used in this packaging method have good flexibility, so that true flexible packaging can be realized. Moreover, the ultra-thin chip 30 also has a certain degree of flexibility, thus enabling the flexibility of the entire product.

[0063] According to an embodiment of the present invention, the flexible integration packaging method for the ultra-thin chip can be used to prepare the packaging structure of the ultra-thin chip described above. Among them, the requirements for the materials, gap sizes, etc. of the structures such as the wiring layer, the flexible printed circuit board dielectric layer, the flexible cover film, the connection electrodes, the first protective layer, and the second protective layer are the same as those described above, and will not be elaborated here one by one.

[0064] In the present invention, unless otherwise clearly defined and limited, the terms "mounted", "connected", "connected to", "fixed", etc. shall be construed in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0065] In the present invention, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "below" and "beneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0066] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples", etc., mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0067] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A packaging structure for an ultra-thin chip, characterized in that, Comprising: A wiring layer; A flexible printed circuit board dielectric layer, which is disposed on the surface of the wiring layer and is provided with slits and vias; An ultra-thin chip, which is disposed in the slit, and there is a gap between the edge of the ultra-thin chip and the inner wall of the slit; A flexible cover film, which is disposed on the surface of the ultra-thin chip away from the wiring layer and fills the gap; A connection electrode, which electrically connects the ultra-thin chip and the wiring layer through the via; Further comprising: At least one copper pillar bump, at least one of the copper pillar bumps is disposed on the surface of the ultra-thin chip away from the wiring layer, and the connection electrode electrically connects the copper pillar bump and the wiring layer through the via; The surface of the copper pillar bump away from the wiring layer is flush with the surface of the flexible cover film away from the wiring layer; A first protective layer, which covers the connection electrode, the flexible cover film, and the surface of the flexible printed circuit board dielectric layer away from the wiring layer; A second protective layer, which covers the surface of the wiring layer away from the ultra-thin chip, and the surface of the flexible printed circuit board dielectric layer away from the first protective layer and not covered by the wiring layer; The first protective layer has an opening, and at least a part of the surface of the connection electrode is exposed by the opening. The packaging structure of the ultra-thin chip further comprises: A metal layer, which is disposed in the opening.

2. The encapsulation structure according to claim 1, wherein The width of the gap is 0.1 - 0.5 mm.

3. The encapsulation structure according to claim 1, wherein Only one ultra-thin chip is disposed corresponding to each slit.

4. The encapsulation structure according to claim 1, characterized in that Further comprising: An adhesive film, which is disposed on the surface of the ultra-thin chip close to the wiring layer.

5. A flexible integrated packaging method for an ultra-thin chip, characterized in that, Comprising: Providing a flexible printed circuit board, which includes a flexible printed circuit board dielectric layer and a wiring layer, and slits are provided in the flexible printed circuit board dielectric layer; Fitting an ultra-thin chip in the slit, and there is a gap between the edge of the ultra-thin chip and the inner wall of the slit, and a copper pillar bump is disposed on the surface of the ultra-thin chip away from the wiring layer; Forming a flexible cover film on the surface of the ultra-thin chip away from the wiring layer, and making the flexible cover film fill the gap, and the surface of the copper pillar bump away from the wiring layer is flush with the surface of the flexible cover film away from the wiring layer; Forming a via penetrating the flexible printed circuit board dielectric layer in the flexible printed circuit board dielectric layer, and at least a part of the wiring layer is exposed by the via; Forming an electrode material layer on the surface of the flexible cover film away from the flexible printed circuit board dielectric layer and performing patterning treatment to obtain a connection electrode, and the connection electrode electrically connects the ultra-thin chip and the wiring layer through the via; Forming a first protective layer on the connection electrode, the flexible cover film, and the surface of the flexible printed circuit board dielectric layer away from the wiring layer; Forming a second protective layer on the surface of the wiring layer away from the ultra-thin chip and the surface of the flexible printed circuit board dielectric layer away from the first protective layer and not covered by the wiring layer; An opening is formed in the first protective layer, and at least a part of the surface of the connection electrode is exposed through the opening. The method further includes: forming a metal layer in the opening; 6. The method according to claim 5, wherein bonding the ultra-thin chip in the slotted groove through a bonding film; 7. The method according to claim 5, wherein The step of forming the flexible cover film includes: coating a liquid flexible material on the surface of the ultra-thin chip away from the wiring layer, filling the gap with the liquid flexible material, and then curing the liquid flexible material by baking to obtain the flexible cover film.

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