A flexible chip packaging structure and method

Abstract

A flexible chip packaging structure includes a flexible circuit board, a flexible support film with a microstructure, and a flexible chip, wherein the flexible support film is arranged between the flexible circuit board and the flexible chip, and the flexible circuit board and the flexible chip are electrically interconnected. The present invention also discloses a flexible chip packaging method, including: providing a flexible circuit board and a flexible chip, providing a flexible support film with a microstructure, and bonding and fixing the flexible circuit board and the flexible chip; providing a gold wire bonding line, and electrically interconnecting the flexible chip and the flexible circuit board. The present invention can realize the flexibility of the chip packaging structure and increase its bending and deformation ability.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a flexible chip packaging structure and method. Background Art

[0002] The rapid development of flexible display technology and flexible circuit board technology will bring revolutionary changes to electronic terminal products, and electronic terminal products will show more and more flexible deformation capabilities. The inventor believes that the display screen and circuit board have been partially flexible in the terminal system, but the chip and its package used in the system are rigid devices that cannot be deformed, which greatly limits the overall flexible deformation capability of the terminal system. Therefore, the flexibility of the chip and its package is the key to the overall flexibility of the terminal system. Summary of the invention

[0003] The purpose of the present invention is to provide a flexible chip packaging structure with good bending and deformation ability and a new, bendable and deformable flexible packaging method.

[0004] The present invention provides a flexible chip packaging structure, comprising a flexible circuit board, a flexible supporting film with a microstructure and a flexible chip, wherein the flexible supporting film is arranged between the flexible circuit board and the flexible chip, and the flexible circuit board and the flexible chip are electrically interconnected.

[0005] Furthermore, the microstructure is a porous structure, and the holes of the porous structure are through holes or non-through holes.

[0006] Furthermore, the microstructure is a plurality of protrusions or grooves, and the microstructure is arranged on the surface of the flexible supporting film adjacent to the flexible chip.

[0007] Furthermore, the flexible circuit board and the flexible chip are electrically interconnected via gold wire bonding lines, and protective glue is provided at the gold wire bonding points between the flexible circuit board and the flexible chip.

[0008] Furthermore, it also includes a flexible packaging film, which covers the side of the flexible circuit board having the flexible chip.

[0009] The present invention also provides a flexible chip packaging method, comprising:

[0010] a. Provide flexible circuit boards and flexible chips;

[0011] b. Providing a flexible support film having a microstructure to adhere and fix the flexible circuit board and the flexible chip;

[0012] c. Provide gold bonding wires to electrically interconnect the flexible chip and the flexible circuit board.

[0013] Furthermore, the microstructure is a porous structure, with multiple protrusions or grooves.

[0014] Furthermore, before step b, the method further includes: attaching the flexible circuit board to the rigid carrier board.

[0015] Furthermore, the method further comprises: after the packaging is completed, peeling the flexible circuit board from the rigid carrier board.

[0016] Furthermore, the method further comprises: forming a flexible packaging film on one side of the flexible circuit board, so that the flexible chip and the gold bonding wire are embedded in the flexible packaging film.

[0017] Furthermore, the flexible packaging film is formed by spin coating, spray coating and hot pressing.

[0018] Furthermore, step c includes: applying protective glue at the gold wire bonding points.

[0019] The beneficial effect of the present invention is that the flexible chip packaging structure and method of the present invention provide space for releasing stress and deforming the packaging structure when it is bent by arranging a flexible supporting film with a microstructure between the flexible circuit board and the flexible chip, thereby reducing the possibility of transmitting stress to the flexible chip, thereby realizing the flexibility of the chip packaging structure and enhancing the bending and deformation ability of the chip packaging structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The figure is a schematic diagram of a flexible chip packaging structure according to an embodiment of the present invention.

[0021] Figure 2 It is a schematic diagram of a flexible chip packaging structure in a bent state according to an embodiment of the present invention.

[0022] Figure 3 It is a cross-sectional view of a flexible supporting film with a porous structure according to an embodiment of the present invention.

[0023] Figure 4 It is a schematic diagram of a flexible chip packaging method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0024] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0025] like Figure 1-3As shown, a flexible chip packaging structure includes a flexible circuit board 4, a flexible support film 3 having a microstructure 31, and a flexible chip 2. Opposite surfaces of the flexible support film 3 are fixedly connected to the flexible circuit board 4 and the flexible chip 2, respectively. The flexible circuit board 4 and the flexible chip 2 are electrically interconnected through gold wire bonding wires 5, and protective glue 6 is provided at each gold wire bonding point.

[0026] In this embodiment, the thickness of the flexible chip 2 does not exceed 50 μm. When the thickness of the flexible chip 2 is reduced to less than 50 μm, it will show a certain degree of flexible bending and deformation ability. The thinner the thickness, the stronger the bending and deformation ability of the chip. However, the ultra-thin flexible chip 2 is more easily damaged than conventional chips during the packaging process. In this embodiment, a flexible support film 3 is fixedly connected to the back of the flexible chip 2. The purpose of pasting the flexible support film 3 is twofold: first, to protect the fragile flexible chip 2 so that it will not break due to its own gravity or other mechanical forces when bending; second, to improve the rigidity of the flexible chip 2 to prevent the flexible chip 2 from bending and breaking when the nozzle of the placement machine picks it up. Among them, the flexible support film 3 can be hexamethyldisilazane, polyimide (PI), polydimethylsiloxane (PDMS), polyolefin copolymer (PO), polytetrafluoroethylene (PTFE), silicone rubber, shape memory polymer, hydrosol and other related flexible materials.

[0027] In this embodiment, the flexible support film 3 is bonded to the flexible circuit board 4 and the flexible chip 2 through an adhesive layer. The adhesive layer may be a DAF film (Die Attach Film), and the flexible circuit board 4 is an FPC flexible high-density circuit board, but is not limited thereto. Specifically, the flexible support film 3 includes a first surface and a second surface relative to each other, the first surface is attached to the back of the flexible chip 2 through an adhesive layer, and the second surface is attached to the front of the flexible circuit board 4 through an adhesive layer. The flexible support film 3 may be one layer or more layers, as long as the overall thickness of the formed flexible support film 3 and the adhesive layer does not exceed 70μm. The size of the flexible support film 3 should not be less than the size of the flexible chip 2, so that the flexible chip 2 can be completely attached to the flexible support film 3. Figure 2As shown, the flexible support film 3 has a microstructure 31, and the microstructure 31 can be a porous structure, or a plurality of protrusions or grooves provided on the first surface of the flexible support film 3. Among them, the pore size of the porous structure is in the order of micrometers. In this embodiment, the microstructure 31 is a porous structure, and the porous structure is a plurality of through holes penetrating along the thickness direction of the flexible support film 3. In other embodiments, the porous structure can be a non-through hole structure, and the holes can be connected, semi-connected or not connected to each other. Specifically, the flexible support film 3 forms a porous structure by a porous treatment in the area bonded to the flexible chip 2, and the porous treatment includes but is not limited to laser drilling, mechanical drilling or the use of porogens and other related pore-forming methods. When the flexible chip packaging structure is bent downward, the flexible support film 3 will give a certain tensile stress to the upper surface of the flexible chip 2. After this tensile stress exceeds a certain specific value, the transistor will crack, causing the flexible chip 2 to fail. The presence of the porous structure can give the flexible support film 3 space to release stress and deform, avoiding the stress from being transmitted to the flexible chip 2, thereby enhancing the bending deformation ability of the packaging structure.

[0028] In this embodiment, a gold wire bonding machine is used to electrically interconnect the flexible chip 2 and the flexible circuit board 4 through the gold wire bonding wire 5, and a protective glue 6 is added at the gold wire bonding point for curing. When the flexible chip packaging structure is bent and deformed, the gold wire bonding point will be subjected to the action of external force, generating a certain tensile stress or shear stress, which may cause desoldering failure at the bonding point. In order to avoid desoldering of the bonding point and improve the reliability of bonding, the flexible chip packaging structure is protected by glue at the gold wire bonding point, and the gold wire bonding point and the pad of the flexible chip 2 or the gold wire bonding point and the pad of the flexible circuit board 4 are coated together, and then cured to form a hard protective point. The amount of glue dispensed at each bonding point covers part of the gold wire bonding line 5 and the pad, and is not connected to the protective glue 6 of the adjacent bonding point. Since the glue is dispensed at the bonding solder joint and is not connected to the protective glue 6 of the adjacent bonding point, even after the protective glue 6 is cured and hardened, the volume of the glue dispensed is very small, and it will not limit the flexible deformation of the flexible chip packaging structure.

[0029] In this embodiment, the flexible chip packaging structure also includes a flexible packaging film 1, which covers the side of the flexible circuit board 4 with the flexible chip 2 to form a package for the flexible chip 2. In other words, after the gold wire bonding and glue protection of the flexible chip 2 and the flexible circuit board 4 are completed, the flexible film is plastic-sealed, and a flexible plastic-sealed film 1 is formed on the side of the flexible circuit board 4 with the flexible chip 2, so that it covers the interconnected flexible chip 2 and the flexible circuit board 4. The flexible plastic-sealed film 1 can be a polymer material, a polymer composite material or a modified polymer material, and can be in powder, film or liquid form. The types of polymer materials include but are not limited to the following: epoxy resins, polyimides, benzocyclobutenes, etc. The method of forming the flexible packaging film 1 can be spin coating, spray coating, hot pressing, etc. The thickness of the flexible packaging film 1 is greater than the thickness of the flexible chip 2 and the arc height of the gold wire bonding wire 5 interconnected therebetween. Through the above materials and processes, the flexible packaging film 1 is formed, which can effectively protect the flexible chip packaging structure from physical and chemical interferences such as water, light, and heat during subsequent processing and use, and the performance is more stable and reliable. In other embodiments, flexible film packaging may not be performed.

[0030] like Figure 4 As shown, in this embodiment, a flexible chip packaging method includes:

[0031] a. Providing a flexible circuit board 4, providing a rigid carrier board 8, and fixing the flexible circuit board 4 on the rigid carrier board 8;

[0032] b. Providing a flexible chip 2;

[0033] c. Providing a flexible support film 3 with a microstructure to adhere and fix the flexible circuit board 4 and the flexible chip 2;

[0034] d. Providing a gold wire bonding wire 5 to electrically interconnect the flexible circuit board 4 and the flexible chip 2;

[0035] e. A flexible packaging film 1 is formed on one side of the flexible circuit board 4, so that the flexible chip 2 and the gold bonding wire 5 are embedded in the flexible packaging film;

[0036] f. Peel the flexible circuit board off the rigid carrier board 8.

[0037] In this embodiment, in step a, the flexible circuit board 4 is attached to the rigid carrier 8 in a removable manner, which can improve the reliability of subsequent gold wire bonding. This is because when the flexible circuit board 4 is subjected to gold wire thermal ultrasonic wedge bonding, the rigid carrier can be used as a support plate, which can ensure the connection strength of the gold wire bonding and improve the reliability of the gold wire bonding. In this embodiment, the flexible circuit board 4 is temporarily bonded to the rigid carrier by a temporary bonding glue 7. The temporary bonding glue 7 can be a bonding glue for UV debonding, thermal debonding or laser debonding. The rigid carrier can be a rigid carrier made of glass or stainless steel, or other rigid carriers with a flat and smooth surface. Of course, in other embodiments, as needed, a rigid carrier 8 may not be provided, and the flexible circuit board 4 may not be removably fixed to the rigid carrier 8.

[0038] In this embodiment, in steps b and c, a flexible support film 3 and a flexible chip 2 having a microstructure 31 are provided, and the flexible circuit board 4 and the flexible chip 2 are bonded and fixed by the flexible support film 3. Specifically, the surface of the flexible support film 3 having the microstructure 31 is bonded to the back of the flexible chip 2 by an adhesive, and the other opposite surface is bonded to the flexible circuit board 4 by an adhesive, so as to realize the physical interconnection between the flexible chip 2 and the flexible circuit board 4. The microstructure 31 can be a porous structure, or a plurality of protrusions or grooves provided on the first surface of the flexible support film 3. Among them, the pore size of the porous structure is in the micron order, and it can be a through-hole structure or a non-through-hole structure, and the holes can be connected, semi-connected or non-connected to each other. In this embodiment, the thickness of the flexible chip 2 does not exceed 50μm, and the flexible support film 3 has a plurality of through holes in the area bonded to the flexible chip 2. The size of the flexible support film 3 should not be less than the size of the flexible chip 2, so that the flexible chip 2 can be completely attached to the flexible support film 3. When bending occurs, the through hole can allow the flexible support film 3 to have space to release stress and deform, avoiding the stress from being transmitted to the side of the flexible chip 2, thereby enhancing the bending and deformation ability of the package. The flexible support film 3 can be hexamethyldisilazane, polyimide (PI), polydimethylsiloxane (PDMS), polyolefin copolymer (PO), polytetrafluoroethylene (PTFE), silicone rubber, shape memory polymer, hydrosol and other related flexible materials. The flexible support film 3 can be one layer or multiple layers, as long as the overall thickness of the formed flexible support film 3 and the adhesive layer does not exceed 70μm.

[0039] In this embodiment, in step d, electrically interconnecting the flexible circuit board 4 and the flexible chip 2 includes: using a gold wire bonding machine to electrically connect the flexible chip 2 and the flexible circuit board 4 through the gold wire bonding wire 5. When the flexible chip packaging structure is bent and deformed, in order to avoid desoldering of the bonding point and improve the reliability of bonding, glue protection is performed at the gold wire bonding point, and the gold wire bonding point and the chip pad or the gold wire bonding point and the substrate pad are coated together, and then cured to form a hard protection point. The amount of glue dispensed at each bonding point covers part of the gold wire bonding line 5 and the pad, and is not connected to the protective glue 6 adjacent to the bonding point.

[0040] In this embodiment, in step e, the electrically interconnected flexible circuit board 4 and the flexible chip 2 are plastic-sealed with a flexible film, so that the flexible packaging film 1 covers the side of the flexible circuit board 4 with the flexible chip 2 and the gold wire bonding wire 5, and the flexible chip 2 and the gold wire bonding wire 5 are packaged. Specifically, a powder, film or liquid packaging material is used to form a flexible packaging film 1 by spin coating, spraying, and hot pressing, and covers the surface of the flexible circuit board 4 with the flexible chip 2. The thickness of the flexible packaging film 1 is greater than the thickness of the flexible chip 2 and the arc height of the gold wire bonding wire 5 interconnected therewith, so that the flexible chip 2 and the gold wire bonding wire 5 are embedded in the flexible packaging film. The packaging material can be a polymer material, a polymer composite material or a modified polymer material, including but not limited to the following: epoxy resin, polyimide, benzocyclobutene, etc.

[0041] In this embodiment, in step f, after the packaging is completed, the formed flexible chip packaging structure is peeled off from the rigid carrier 8. The viscosity of the bonding adhesive is changed by UV radiation, heating, laser, etc., so that the flexible chip packaging structure is peeled off from the rigid carrier 8. Of course, if in step a, no rigid carrier 8 is provided, and the flexible circuit board 4 is not releasably connected to the rigid carrier 8, then step f should be cancelled.

[0042] The flexible circuit board 4, flexible support film 3, flexible chip 2 and flexible packaging film 1 used in the present invention all have flexible deformation capabilities, and the flexible support film 3 has a microstructure. The existence of the microstructure can make the flexible support film 3 have space to release stress and deform. When the flexible chip packaging structure is bent, it can avoid the stress from being transmitted to the flexible chip 2, thereby enhancing the bending deformation capability of the packaging structure; at the same time, the gold wire bonding solder joints of the chip are protected by glue curing, avoiding desoldering of the bonding joints due to bending, and improving the reliability of bonding. Therefore, the entire package can withstand a certain degree of bending deformation and presents a flexible feature.

[0043] In this document, the directions or positional relationships indicated by terms such as "up", "down", "front", "back", "left", "right", "top", "bottom", "inside", "outside", "vertical", and "horizontal" are based on the directions or positional relationships shown in the accompanying drawings and are only for the clarity of expressing the technical solutions and the convenience of description, and therefore should not be understood as limitations of the present invention.

[0044] In this document, the terms "comprises," "comprising," or any other variations thereof, are intended to cover a non-exclusive inclusion of elements other than those listed and may also include additional elements not expressly listed.

[0045] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A flexible chip packaging structure, characterized in that: It includes a flexible circuit board, a flexible support film with a microstructure and a flexible chip, wherein the flexible support film is arranged between the flexible circuit board and the flexible chip, the flexible circuit board and the flexible chip are electrically interconnected, and the size of the flexible support film is not less than the size of the flexible chip; the flexible circuit board and the flexible chip are electrically interconnected by gold wire bonding lines, and protective glue is provided at the gold wire bonding points between the flexible circuit board and the flexible chip; the microstructure is a porous structure, the holes of the porous structure are through holes or non-through holes, or the microstructure is a plurality of protrusions or grooves, and the microstructure is arranged on the surface of the flexible support film adjacent to the flexible chip.

2. The flexible chip packaging structure according to claim 1, characterized in that: It also includes a flexible packaging film, which covers the side of the flexible circuit board with the flexible chip.

3. A flexible chip packaging method, characterized in that: include: a. Provide flexible circuit boards and flexible chips; b. Providing a flexible support film with a microstructure to adhere and fix the flexible circuit board and the flexible chip, wherein the microstructure is a porous structure with multiple protrusions or grooves, and the size of the flexible support film is not less than the size of the flexible chip; c. Provide gold wire bonding lines to electrically interconnect the flexible chip and the flexible circuit board, and provide protective glue at the gold wire bonding points between the flexible circuit board and the flexible chip.

4. The flexible chip packaging method according to claim 3, characterized in that: Before step b, the method further includes: attaching the flexible circuit board to a rigid carrier board.

5. The flexible chip packaging method according to claim 4, characterized in that: Also includes: After packaging is completed, the flexible circuit board is peeled off from the rigid carrier.

6. The flexible chip packaging method according to claim 3, characterized in that: Also includes: A flexible packaging film is formed on one side of the flexible circuit board, so that the flexible chip and the gold bonding wire are embedded in the flexible packaging film.

7. The flexible chip packaging method according to claim 6, characterized in that: The flexible packaging film is formed by spin coating, spray coating and hot pressing.

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