CN214693974U

CN214693974U - Flexible chip bonding film and packaging structure of flexible chip

Info

Publication number: CN214693974U
Application number: CN202023201566.0U
Authority: CN
Inventors: 刘东亮; 王波; 滕乙超; 魏瑀; 刘洋洋; 张鹤然; 姚建
Original assignee: Zhejiang Heqing Flexible Electronic Technology Co ltd
Current assignee: Zhejiang Heqing Flexible Electronic Technology Co ltd
Priority date: 2020-12-25
Filing date: 2020-12-25
Publication date: 2021-11-12
Anticipated expiration: 2030-12-25

Abstract

The utility model provides a packaging structure of flexible chip adhesive film and flexible chip, the adhesive film includes: the adhesive film comprises a release film, a supporting layer, a substrate adhesive layer and a base film; the release film is attached to the first surface of the supporting layer; the first surface of the substrate bonding layer is attached to the second surface of the supporting layer; the base film is attached to the second surface of the substrate bonding layer; the problem of among the prior art appear cracked easily and take place phenomena such as short circuit, open circuit easily in the use in the packaging process of flexible chip is solved, not only realized the supporting role to the flexible chip, had good dimensional stability in the curing process, still reduced the transport repeatedly and the pressfitting to ultra-thin wafer, be favorable to improving the wafer and break, improved machining efficiency.

Description

Flexible chip bonding film and packaging structure of flexible chip

Technical Field

The utility model relates to a flexible circuit technical field, concretely relates to flexible chip adhesive film and flexible chip's packaging structure.

Background

The DAF film is a chip flexible chip bonding film and is a common key material in the chip packaging process; in the process of cutting the wafer, the DAF film is uniformly adhered to the back surface of the wafer to be cut, so that the wafer is adhered to the DAF film when being cut into a plurality of small chips, and the small chips are not scattered and arranged due to cutting; in the die bonding process, the die is fixed on the substrate by the DAF.

The DAF film in the prior art is usually used for rigid chips with the thickness of more than 50 microns, and because the thickness of the rigid chip is far higher than that of the DAF film, the rigid chip is not easily affected by the thimble to break in the process of peeling off the rigid chip, and the rigid chip after plastic package is not bent and deformed in the use process, the rigid chip only has the adhesion function requirement in the mounting process for the DAF film.

For flexible chips, the typical thickness is below 25 μm, close to or below the thickness of the DAF film, with the following problems: 1) the elastic modulus of the DAF film is far lower than that of the flexible chip, so that the bottom of the flexible chip is lack of effective support, back collapse is easy to generate during cutting, and fragments are easy to generate during chip peeling; 2) in the curing process, the thermal expansion coefficient of the DAF film is higher than that of the flexible chip, so that the flexible chip is easy to bend under the tensile stress generated by the contraction of the DAF film, and the yield of the subsequent bonding and other interconnection processes is influenced; 3) the packaged flexible chip needs to be bent and deformed along with a flexible substrate frequently in the use process, large internal stress is generated inside the flexible chip when the flexible chip is bent due to the large difference of elastic modulus of a DAF film and the flexible chip, each dielectric layer in the chip can generate certain strain under the action of the internal stress, and when the strain exceeds a certain value, the phenomena of leakage current, breakdown, short circuit, open circuit and the like are easy to occur, so that the function failure of the chip is caused.

Therefore, the flexible chip adhesive film in the prior art is easy to crack and influence the packaging yield in the packaging process of the flexible chip, and is easy to generate short circuit, open circuit and other phenomena in the use process of the flexible chip, so that the packaging requirement of the flexible chip is not met.

SUMMERY OF THE UTILITY MODEL

Not enough to exist among the prior art, the utility model provides a packaging structure of flexible chip adhesive film and flexible chip, it has solved among the prior art and has appeared cracked easily and take place the problem of phenomena such as short circuit, open circuit in the use easily in the packaging process of flexible chip, has not only realized the supporting role to the flexible chip, has good dimensional stability at the solidification process, has still reduced transport and the pressfitting repeatedly to ultra-thin wafer, is favorable to improving the wafer and breaks, has improved machining efficiency.

In a first aspect, the present invention provides a flexible chip adhesive film, the adhesive film includes: the adhesive film comprises a release film, a supporting layer, a substrate adhesive layer and a base film; the release film is attached to the first surface of the supporting layer; the first surface of the substrate bonding layer is attached to the second surface of the supporting layer; the base film is attached to the second surface of the substrate adhesive layer.

In a second aspect, the present invention provides a flexible chip packaging structure, including flexible chip and flexible substrate, the flexible chip with the flexible substrate passes through the above-mentioned supporting layer and the substrate bonding layer of flexible chip adhesive film are fixed.

Compared with the prior art, the utility model discloses following beneficial effect has:

1. the utility model discloses a subsides of flexible chip and flexible substrate is realized to the base plate bond line, increased the supporting layer between base plate bond line and the flexible chip, the material mechanics nature and the calorifics nature of supporting layer lie in between Si material and base plate bond layer material, have increased the elastic modulus of flexible chip adhesive film, have not only realized the support function to the flexible chip, are convenient for pick up the subsides of flexible chip and paste, avoid appearing cracked problem when the cutting; when the flexible chip is bent, the internal stress of the flexible chip is reduced, and the problems that the flexible chip is easy to short circuit and open circuit in the use process are solved.

2. The utility model provides a flexible chip adhesive film has strengthened the dimensional stability of flexible chip adhesive film in the curing process to solve the tensile stress that flexible chip receives flexible chip adhesive film shrink to produce easily and take place crooked problem, improved flexible chip's encapsulation yield.

3. In the packaging process of flexible chip, only need paste once the embodiment of the utility model provides a flexible chip adhesive film can realize supporting and adhesion function, has reduced transport and pressfitting repeatedly to the wafer, is favorable to improving the wafer and breaks, and can improve machining efficiency.

Drawings

Fig. 1 is a schematic flow chart illustrating a method for manufacturing a flexible chip adhesive film according to an embodiment of the present invention;

FIG. 2 is a schematic flow chart of step S103 in FIG. 1;

fig. 3 is a schematic structural diagram of a supporting layer according to an embodiment of the present invention;

fig. 4 is a schematic structural diagram of a supporting layer and a release film according to an embodiment of the present invention;

fig. 5 is a schematic structural diagram of another supporting layer and a release film according to an embodiment of the present invention;

fig. 6 is a schematic structural diagram of a release film and a substrate bonding layer according to an embodiment of the present invention;

fig. 7 is a schematic diagram illustrating die cutting of a pre-cut composite film according to an embodiment of the present invention;

fig. 8 is a schematic structural diagram of a base film according to an embodiment of the present invention;

fig. 9 is a schematic structural view of a splicing tape according to an embodiment of the present invention;

fig. 10 is a schematic cross-sectional view illustrating a flexible chip bonding film according to an embodiment of the present invention;

fig. 11 is a schematic plan view illustrating a flexible chip bonding film according to an embodiment of the present invention;

fig. 12 is a schematic flowchart illustrating a method for packaging a flexible chip according to an embodiment of the present invention;

fig. 13 is a schematic view illustrating a mounting of a wafer and a flexible chip bonding film according to an embodiment of the present invention;

fig. 14 is a schematic view illustrating a wafer dicing according to an embodiment of the present invention;

fig. 15 is a schematic view illustrating a curing process performed on a flexible chip bonding film according to an embodiment of the present invention;

fig. 16 is a schematic diagram illustrating a pick-up of a flexible chip according to an embodiment of the present invention;

fig. 17 is a schematic view illustrating a flexible chip and a substrate being mounted according to an embodiment of the present invention;

fig. 18 is a schematic view illustrating an electrical connection between a flexible chip and a substrate according to an embodiment of the present invention;

fig. 19 is a schematic view illustrating a flexible chip and a substrate soft package according to an embodiment of the present invention.

Description of reference numerals: 110. the flexible substrate comprises a supporting layer, 120, a first adhesive layer, 130, a release film, 140, a second adhesive layer, 150, a release film, 160, a substrate adhesive layer, 170, a base film, 180, a third adhesive layer, 210, a wafer, 220, an iron frame, 230, a thimble, 240, a pick-up head, 250, a flexible substrate, 260, a lead, 270 and a flexible dielectric layer.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

In a first aspect, the present invention provides a method for preparing a flexible chip adhesive film, which specifically includes the following embodiments:

fig. 1 is a schematic flow chart illustrating a method for manufacturing a flexible chip adhesive film according to an embodiment of the present invention; as shown in fig. 1, the method for preparing the flexible chip adhesive film specifically comprises the following steps:

step S101, providing a supporting layer and a release film, wherein the first surface of the supporting layer is attached to the release film.

Further, provide a supporting layer and leave the type membrane, the first face of supporting layer with leave the type membrane laminating, include:

providing the supporting layer, and coating a first adhesive on a first surface of the supporting layer to form a first adhesive layer;

providing the release film, and attaching the release film to the first adhesive layer; wherein the mechanical property and the thermal property of the material of the support layer are between the Si material and the material of the substrate bonding layer.

As shown in fig. 3, in this embodiment, a polyimide film is provided as the supporting layer 110, a first adhesive is coated on a first surface of the supporting layer to form a first adhesive layer 120, and the first adhesive layer is dried, the polyimide film 110 may be a finished film or a cured film formed by coating liquid polyimide, and the thickness of the polyimide film may be 10 to 70 μm; in view of cost and process complexity, Kapton, the finished film, is preferred in this embodiment. Kapton is a polyimide film material, and is prepared by adopting 40 percent of para-phenylene diamine and 60 percent of octadecylamine to carry out sequential copolymerization, and the polyimide film material has higher strength and lower thermal expansion coefficient, hygroscopicity and dielectric constant, so the material relatively meets the requirements of high elastic modulus, good dimensional stability, low thermal expansion coefficient and the like in the utility model. In terms of thickness, Kapton generally has specifications of 1/2mil, 1mil, 2mil, 5mil, etc., that is, thicknesses of 12.7 μm, 25.4 μm, 50.8 μm, 63.5 μm, etc., and since this layer is mainly used as a chip support layer in this embodiment, when the thickness is too large, elastic deformation of the polyimide film with respect to the chip will be prominent, and the chip will have poor bonding strength, debonding, etc. during the subsequent gold wire bonding process, a thickness of 1/2mil, 1mil is preferred as the interlayer material. In the aspect of material width, according to the specifications of 8-inch and 12-inch wafers commonly used in the industry at present, the width range adopted by 8 inches is generally 290-300 mm, and the width range adopted by 12 inches is 390-400 mm, considering that cutting needs to be performed after subsequent compounding is completed, a machining allowance of 10mm is generally reserved for the width of polyimide, namely: the 8 inch gauge width was 310mm and the 12 inch gauge width was 410 mm.

In order to improve the adhesion, retention, etc. of the support layer and the adjacent adhesive layer, surface modification treatments, including but not limited to plasma bombardment, ozone oxidation, high voltage treatment, etc., are required; the first adhesive layer 120 is mainly used for subsequent adhesion with the back of a chip, acrylic glue or organic silica gel with strong adhesion with silicon and polyimide can be selected in the aspect of material, coating can be performed by adopting roller coating, silk screen coating, gravure coating and other modes, the thickness is controlled within the range of 10-30 micrometers and is generally lower than that of a polyimide film, and finally, the first adhesive layer is kept stand for a period of time at a certain temperature according to the thickness of an adhesive and the property of the material for drying.

To explain further, as shown in fig. 4, a release film 130 is provided, which mainly serves to protect the first adhesive layer 120 and to provide support for cutting the tape base film and the adhesive composite film during the tape die-cutting process. The materials are generally selected from polyethylene terephthalate (PET), polypropylene, etc., the thickness is generally controlled within a range of 50 to 150 μm, preferably within a range of 80 to 120 μm, the width is consistent with the size of the supporting layer 110, and finally the release film 130 and the first adhesive layer 120 are compounded by a dry compounding method.

As shown in fig. 5, a second adhesive is applied to the second surface of the supporting layer 110 to form a second adhesive layer 140, and the second adhesive layer is dried to form a second adhesive surface of the supporting layer 110; the second adhesive layer 140 is mainly used to improve the adhesion between the supporting layer 110 and a substrate adhesive layer to be subsequently manufactured, and may be made of a material similar to the first adhesive layer 120, and an acrylic adhesive or an organic silicon adhesive is applied to the second surface of the supporting layer 110 by roll coating, screen coating, gravure coating, etc., and is an intermediate layer, so that the thickness of the second adhesive layer is as low as possible compared to that of the first adhesive layer 120, and is controlled within a range of 5 to 10 μm. And finally, standing for a period of time at a certain temperature according to the thickness and material properties of the second adhesive layer 140 for drying, for example, drying at 80-150 ℃ for 1-10 minutes.

Step S102, providing a substrate bonding layer, and attaching the first surface of the substrate bonding layer to the second surface of the supporting layer.

In this embodiment, the providing a substrate bonding layer, and attaching a first surface of the substrate bonding layer to a second surface of the support layer, includes: providing a stripping film, coating a substrate adhesive on the stripping film to form the substrate adhesive layer; and transferring the first surface of the substrate bonding layer to the second bonding layer to form a bonding composite film, wherein the bonding composite film comprises the substrate bonding layer, the second bonding layer, the supporting layer and the first bonding layer, and the first surface of the substrate bonding layer is a surface deviating from the stripping film.

First, as shown in fig. 6, a release film 150 is provided, a substrate adhesive is coated on the release film 150 to form the substrate adhesive layer 160, and the release film 150 mainly functions to provide a supporting function for the substrate adhesive layer 160 and transfer it to the second adhesive layer 140, and the material aspect follows the mature product commonly used in the industry. For substrate adhesive material selection: the epoxy resin may be selected as the main component from bifunctional epoxy resins such as bisphenol A type, bisphenol F type, bisphenol S type, etc., or polyfunctional epoxy resins such as phenol novolak type, o-cresol novolak type, trishydroxyphenylmethane type, tetraphenylolethane type, etc., or epoxy resins such as triglycidyl isocyanurate type, glycidylamine type, etc., and these epoxy resins may be used alone or in combination of two or more; in order to improve the adhesion between the chip and the substrate and the reliability, a curing agent is required to be added, and the curing effect is achieved after heating, and a phenol novolac resin, a phenol aralkyl resin, and the like can be selected, and the mixing ratio of the phenol novolac resin, the phenol aralkyl resin, and the like to the main component is generally 0.5-1.5: 1, preferably 0.8-1.2: 1, and if the mixing ratio exceeds the range, the phenomena of insufficient curing reaction, poor performance of the epoxy resin after curing, and the like are easy to occur. Further: in order to have a certain degree of crosslinking in advance, a proper amount of polyfunctional compounds can be selected to be added as a crosslinking agent to react with functional groups at the molecular chain ends of the polymer, so that the adhesive has improved binding power and heat resistance at high temperature; in order to improve the stability of the substrate adhesive layer 160 under high temperature conditions, an appropriate amount of antimony trioxide, antimony pentoxide, or brominated epoxy resin may be added as a flame retardant, and bismuth hydroxide, hydrotalcite, or the like may be added as an ion scavenger. After the materials are mixed according to a certain proportion, the materials are uniformly coated on the surface of release paper by adopting roller coating, screen coating, gravure coating and other modes, the coating thickness is generally controlled within the range of 10-40 mu m, the thickness of the flexible chip is considered to be less than 25 mu m, preferably 10-20 mu m, so as to reduce the stress influence generated in the curing process, and finally, the flexible chip is kept still for a period of time at a certain temperature according to the thickness of the adhesive and the properties of the materials for drying.

Secondly, transferring the first surface of the substrate bonding layer 160 to the second adhesive surface of the support layer 110 to form a bonding composite film, wherein the bonding composite film comprises the substrate bonding layer 160 and the support layer 110; in this embodiment, the substrate adhesive layer 160 on the release film 150 may be transferred to the support layer 110 by a transfer method commonly used in the industry.

In this embodiment, after the first side of the substrate adhesive layer 160 is transferred to the second side of the support layer 110 to form an adhesive composite film, the method further includes: stripping the stripping film 150 on the bonding composite film to obtain a precut composite film; and die cutting the pre-cut composite film according to a first preset size to form a plurality of bonding areas and non-bonding areas on the pre-cut composite film, wherein the bonding areas comprise the bonded composite film and the release film, and the non-bonding areas comprise the release film.

Further, after the substrate adhesive layer 160 is transferred, the release film 150 on the surface is removed to obtain a pre-cut composite film, and fig. 7a is a schematic structural diagram of the pre-cut composite film; then referring to DISCO DTF2-8-1 standard (diameter of the 12 inch precut adhesive tape on chip bonding composite film is 320mm, diameter of the 8 inch precut adhesive tape on chip bonding composite film is 220mm) commonly adopted in the industry, the pre-cut composite film is cut into circular sheets with corresponding diameters by a die cutting mode of a plurality of layers of laminating materials, the release film 130 is kept unchanged, to serve as a strength support, and finally, the excess leftover materials except the wafer are peeled off and removed from the release film 130, namely after die cutting, forming a plurality of adhesive regions and non-adhesive regions on the pre-cut composite film, as shown in fig. 7b, the adhesive regions including the adhesive composite film and the release film 130, the non-adhesive regions including only the region of the release film 130, the wafers cut into the corresponding diameters are the bonding areas which are used for bonding the wafers, and each bonding area is independent.

Step S103, providing a base film, and attaching the base film to the second surface of the substrate bonding layer to form the flexible chip bonding film.

As shown in fig. 2, step S103 provided in this embodiment specifically includes the following steps:

step S201, providing a base film, and performing antistatic treatment on a first surface of the base film and surface modification treatment on a second surface of the base film;

step S202, coating a third adhesive on the second surface of the base film to form a third adhesive layer;

step S203, compounding the second surface of the substrate bonding layer with the third bonding layer to obtain a bonding tape, wherein the second surface of the substrate bonding layer is the opposite surface of the first surface of the substrate bonding layer;

step S204, cutting the base film on the adhesive tape according to a second preset size to obtain a first die-cut film, and enabling the first base film and a second base film on the first die-cut film to be independent from each other, wherein the first base film is the base film attached to the bonding areas, and the second base film is the base film attached to the non-bonding areas;

and S205, cutting the non-bonding area of the first die-cut film according to a third preset size to obtain the flexible chip bonding film.

It should be noted that, as shown in fig. 8, a base film 170 is provided, mainly serving as a strength carrier of the flexible chip adhesive film, and provides a supporting function in the processes before and after dicing, and a third adhesive is applied on the surface of the base film 170 to form a third adhesive layer 180, where the third adhesive is an ultraviolet-sensitive adhesive. In order to facilitate the subsequent peeling of the flexible chip, the ultraviolet-sensitive adhesive coated on the surface needs to have ultraviolet permeability, so that the ultraviolet-sensitive adhesive is cured under the irradiation of ultraviolet rays, and the viscosity of the interface between the ultraviolet-sensitive adhesive and the substrate is reduced. The base film 170 may be made of polyolefin such as polyethylene, polypropylene, polybutene, and polymethylpentene, or polymer resin, cellulose resin, and silicone resin, and the thickness of the base film 170 may be controlled to be 50 to 150 μm, preferably 100 to 120 μm, and the width of the base film may be equal to the width of the polyimide film 110, that is, the 8-inch width may be 310mm, and the 12-inch width may be 410 mm. The prepared base film 170 is first vapor deposited on a first surface of the base film 170

The metal oxide layer having a thickness for antistatic treatment and then the second side is subjected to surface modification treatment to improve adhesion with the adjacent third adhesive layer 180, and plasma bombardment, ozone oxidation, high voltage treatment, chromic acid treatment, primer coating, and the like can be used. The third adhesive layer 180 is internally providedThe ultraviolet-curable pressure-sensitive adhesive uses a polymer having a radically reactive carbon-carbon double bond at a side chain or a main chain end of the polymer as a base polymer, and does not contain an oligomer of a low-molecular-weight component, thereby forming a stable pressure-sensitive adhesive layer. In the scheme, acrylic polymer with acrylic ester (such as alkyl acrylate, alkyl acrylate and the like) as a main monomer component is adopted, and hydroxyl-containing monomer (such as (methyl) acrylic acid-2-hydroxyethyl ester and the like) capable of carrying out copolymerization reaction with the acrylic ester is added, wherein the mixing ratio of the acrylic polymer to the main component is 0.1-0.4: 1, preferably 0.25: 1; in order to improve the cohesion and heat resistance of the material, a component copolymerizable with the main monomer component, such as methyl methacrylate, may be added in a compounding ratio of 0 to 0.03:1, preferably 0.02:1, to the main component; in order to adjust the viscosity of the adhesive, an isocyanate compound with a free radical reactive carbon-carbon double bond, such as methacryloyl isocyanate and the like, is added, and the mixing ratio of the isocyanate compound to the main component is 0.07-0.3: 1, preferably 0.2: 1; in order to adjust the poor adhesion before and after ultraviolet irradiation, an external crosslinking agent such as a polyisocyanate compound, an epoxy compound or the like may be added in a compounding ratio of 0.01 to 0.2:1, preferably 0.1:1, to the main component; and optionally ultraviolet-curable oligomer (such as carbamate and polycarbonate) at a ratio of 0.2-0.5: 1 (preferably 0.3: 1); finally, a photopolymerization initiator (such as a-hydroxy-a, 2-methyl-2-hydroxy propiophenone) is added, and the mixing ratio of the photopolymerization initiator to the main component is 0.05-0.2: 1, preferably 0.1: 1. After the materials are mixed according to a certain proportion, the materials are uniformly coated on the second surface of the base film 170 by adopting roller coating, screen coating, gravure coating and other modes, the coating thickness is generally controlled within the range of 5-20 μm, the thickness of the flexible chip is considered to be below 25 μm, preferably 5-10 μm, and finally the flexible chip is kept still for a period of time at a certain temperature according to the thickness of the adhesive and the material property for drying.

As shown in fig. 9, the second surface of the substrate adhesive layer 160 in the disk-shaped adhesive composite film is combined with the adhesive surface of the base film 170 to form a dicing-ready adhesive tape. In a conventional manner in the conventional industry, such as a dry lamination method or a co-extrusion lamination method, the adhesive composite film is laminated with the base film to obtain an adhesive tape having a multi-layer structure, and the widths of the adhesive composite film and the base film are the same, so that the base film 170 is directly connected with the release film 130 through the third adhesive layer 180 in a region outside the adhesive composite film, and the release film 130 can also serve as a strength support carrier of the base film 170 in the following.

As shown in fig. 10 and 11, the base film 170 is die-cut according to a packaging standard to obtain a first die-cut film, and the non-adhesive region of the first die-cut film is cut according to a third preset size to obtain the flexible chip adhesive film. The second predetermined size and the third predetermined size may be based on the DISCO DTF2-8-1 standard commonly used in the industry: the diameter of the 12-inch precut adhesive tape wafer is 370mm, and the overall width is generally 390-400 mm; the diameter of the 8-inch precut adhesive tape wafer is 270mm, and the overall width is generally 290-300 mm.

And cutting the base film into a ring according to the standard by adopting a half-cutting process commonly used for coiled materials, and stripping and removing the base film, wherein the release film 130 and the adhesive for mounting the wafer flexible chip are kept unchanged. Finally, the sheets/roll are uniformly rolled on an antistatic cylinder with the diameter of 10mm according to the packaging specification of 100 sheets/roll, and the sheets/roll are sealed and stored by a shading bag.

In a second aspect, the present invention provides a flexible chip bonding film, as can be seen in fig. 3 to 11, the flexible chip bonding film comprising:

a release film 130, a support layer 110, a substrate adhesive layer 160, and a base film 170;

the release film 130 is attached to the first surface of the support layer 110;

the first side of the substrate adhesive layer 160 is attached to the second side of the support layer 110;

the base film 170 is attached to the second surface of the substrate adhesive layer 160.

In this embodiment, the elastic modulus of the support layer is between the elastic modulus of the substrate bonding layer and the elastic modulus of the flexible chip, and the expansion coefficient and the heat-resistant temperature of the support layer are also between the substrate bonding layer and the flexible chip.

In an embodiment of the present invention, the flexible chip adhesive film further includes:

a first adhesive layer 120 for attaching the release film 130 to the first surface of the support layer 110;

a second adhesive layer 140 for bonding a first surface of the substrate adhesive layer 160 to a second surface of the support layer 110, and forming an adhesive composite film by the substrate adhesive layer 160, the support layer 110, the first adhesive layer 120, and the second adhesive layer 140;

and a third adhesive layer 180 for attaching the base film 170 to the second surface of the substrate adhesive layer 160.

In an embodiment of the present invention, the adhesive film includes a plurality of adhesive regions and a non-adhesive region, the plurality of adhesive regions include the adhesive composite film and the release film 130, the non-adhesive region includes the release film 130, and the base film on the plurality of adhesive regions is independent of the base film on the non-adhesive region.

In one embodiment of the present invention, the support layer 110 is a polyimide film.

In an embodiment of the present invention, the thickness of the supporting layer 110 is 10 to 70 μm; and/or the thickness of the substrate bonding layer 160 is 10-40 μm; and/or the thickness of the release film 130 is 50-150 μm; and/or the thickness of the base film 170 is 50 to 150 μm; and/or the first adhesive layer 120 comprises acrylic glue or organic silica gel, and the thickness of the first adhesive layer is 10-30 μm; and/or the second adhesive layer 140 comprises acrylic glue or organic silica gel, and the thickness of the second adhesive layer is 5-10 μm; and/or the third bonding layer 180 is an ultraviolet sensitive adhesive, and the thickness of the adhesive is 5-20 μm.

It should be noted that the present invention provides a flexible chip adhesive film, which is a product embodiment obtained by the above preparation method embodiment, and therefore, the flexible chip adhesive film is based on the same explanation process as the above preparation method embodiment, and is not repeated here.

In a third aspect, an embodiment of the present invention provides a method for packaging a flexible chip, in which the flexible chip adhesive film provided in the above embodiment is used, as shown in fig. 12, the method specifically includes the following steps:

step S301, providing a wafer, and attaching the first surface of the wafer to the supporting layer of the flexible chip adhesive film.

Specifically, as shown in fig. 13, an ultra-thin wafer 210 is provided, and the bonding film provided in the above embodiment is attached to the back surface of the ultra-thin wafer after polishing. The flexible chip bonding film prepared in the scheme is consistent with the common precut DAF adhesive tape, so that a conventional precut film sticking machine can be used for sticking the film, the back surface of the ultrathin wafer 210, namely the first surface grinding and stress relief polishing, is completed, the wafer 210 is transferred to a film sticking machine workbench which is online with thinning equipment, after the release film 130 of the flexible chip bonding film is peeled off, the flexible chip bonding film is uniformly stuck to the first surface of the wafer 210, and the standard iron frame 220 is used for supporting.

Step S302, the wafer is cut to obtain a plurality of flexible chips, and the flexible chips are connected with each other through a base film.

As shown in fig. 14, the ultra-thin wafer 210 is cut by a diamond grinding wheel to obtain a plurality of flexible chips separated from each other. For the flexible wafer 210 that has been ground to a set thickness, each flexible chip is separated from the third adhesive layer 180 at the bottom by dicing along a pre-designed dicing lane. Because the polyimide film is adopted as the chip supporting layer in the scheme, a diamond grinding wheel is preferably selected in the cutting mode for mechanical cutting, and the cutter height needs to be controlled to be 1/3-1/2 of the thickness of the base film 170 in the cutting process, namely the supporting layer 110, the substrate bonding layer 160 and the third bonding layer 180 are separated together along with the flexible chip. As shown in fig. 15, the ultra-thin wafer is irradiated with ultraviolet rays on its back surface, that is, directly on the base film 170 of the flexible chip adhesive film. After the cutting of the flexible chip is completed, in order to facilitate the subsequent peeling, ultraviolet irradiation treatment is needed, and after ultraviolet light is absorbed by the ultraviolet sensitive adhesive on the base film 170 of the flexible chip adhesive film, active free radicals or cations are generated to initiate monomer polymerization, crosslinking and chemical reaction, so that the adhesive surface in contact with the base plate adhesive layer 160 is cured, the viscosity is reduced, and the cut chip is easy to peel.

Step S303, providing a flexible substrate, picking up and attaching the flexible chip on the flexible substrate, and attaching the flexible chip to the flexible substrate through the supporting layer of the flexible chip adhesive film and the substrate adhesive layer.

Further, before providing a flexible substrate to pick up and mount the flexible chip on the flexible substrate, the method further includes: curing the adhesive between the substrate adhesive layer and the base film; and expanding the membrane of the base membrane to expand the distance between the flexible chips.

Further, providing a flexible substrate, picking up and attaching the flexible chip on the flexible substrate, comprising: peeling the flexible chip from the base film through a thimble; providing the flexible substrate, sucking the flexible chip through a pick-up head and pre-attaching the flexible chip to a target position of the flexible substrate; and heating and curing the flexible substrate to fix the substrate bonding layer on the target position.

As shown in fig. 16, the cut ultrathin wafer 210 is first placed on a chip mounter for film spreading, and then transferred to a pick-up platform for peeling and picking up a flexible chip. The distance between the cut chips is within the range of 20-40 mu m, and collision or adhesion between the chips is easy to occur when the chips are directly picked up. In order to facilitate the subsequent stripping and picking, the film needs to be expanded, and the distance between the chips is enlarged to 50-70 μm. And then, placing the wafer after film expansion on a pick-up platform of a chip mounter, adopting a special ejector pin 230 customized for the flexible chip to gradually peel the chip from the base film 170, sucking the flexible chip away by a pick-up head 240, transferring the chip to the upper part of the specified position of a flexible substrate 250, and pressing downwards for 5-15 seconds to complete pre-mounting of the chip.

As shown in fig. 17, the flexible substrate 250 to which the flexible chip is attached is heated and cured. And (3) placing the bonded chip into a nitrogen oven to be baked for a period of time at a certain temperature, so that the thermosetting resin in the substrate bonding layer 160 is subjected to a crosslinking reaction and cured, and the flexible chip is firmly fixed at the corresponding position on the flexible substrate 250.

And step S304, electrically connecting the flexible chip with the flexible substrate to obtain a packaging structure of the flexible chip.

Specifically, electrically connecting the flexible chip to the flexible substrate to obtain the package structure of the flexible chip includes: connecting a bonding pad on the flexible chip with a bonding pad on the flexible substrate through wire bonding; providing a flexible medium layer; and the flexible dielectric layer electrically protects the flexible chip, the lead and the lead bonding point to obtain the packaging structure of the flexible chip.

As shown in fig. 18, the cured flexible chip and the flexible substrate 250 are interconnected by a wire 260. In order to realize the function of the flexible chip, it is necessary to interconnect the pads on the surface thereof with the pads on the flexible substrate 250. In the present scheme, because a front surface mounting manner is adopted, a wire bonding method may be considered for interconnection, and a fan-out type interconnection manner for a flexible chip may also be adopted, where the wire 260 includes but is not limited to a gold wire.

As shown in fig. 19, the flexible chip and the interconnection lines are encapsulated by dispensing with a flexible dielectric layer 270. The flexible dielectric layer 270 mainly serves to electrically protect the chip and the interconnection metal line or metal layer from being damaged in the using process, and a single-component or double-component heat-cured epoxy adhesive is generally adopted in the material aspect, and is uniformly coated on the surface of the whole system after being heated, and the thickness aspect ensures that the flexible chip on the surface can be completely coated.

In a fourth aspect, an embodiment of the present invention provides a package structure of a flexible chip, including a flexible chip and a flexible substrate, which is characterized in that the flexible chip and the flexible substrate are fixed by the supporting layer and the substrate bonding layer of the flexible chip bonding film, and the specific structure is described with reference to the above embodiments and shown in fig. 19, which is not repeated here.

In another embodiment of the present invention, the preparation method and the using method of the flexible chip bonding film provided by the present invention mainly include the following steps:

(1) a polyimide film with the model of Kapton 120FN616, the width of 410mm and the thickness of 1mil is selected as a supporting layer. The first surface of the polyimide film is bombarded (Ar 100sccm, 120W-8 min) by plasma for modification treatment, the surface is coated with a layer of organic silica gel with the thickness of 20 mu m by a roller coating mode, and finally, the polyimide film is dried for 5 min at 80 ℃.

(2) A PET film is selected as a release film, the width of the PET film is 410mm, the thickness of the PET film is 100 mu m, and the release film and the first surface of the polyimide film with the adhesive are compounded by a dry compounding method.

(3) And (3) coating a layer of acrylic glue on the second surface of the polyimide film by adopting a roller coating mode, wherein the thickness of the acrylic glue is 5 mu m, and finally drying the acrylic glue for 3 minutes at 100 ℃.

(4) First, a release paper (model: shin-Etsu KS-835) was selected, and then a substrate adhesive was prepared: adding 100 parts of phenol novolac epoxy resin as a main component, and adding 60 parts of phenol aralkyl resin as a curing agent; 35 parts of a certain polyfunctional compound as a crosslinking agent, 70 parts of a brominated epoxy resin as a flame retardant, and 20 parts of hydrotalcite as an ion trapping agent were added. The above materials were dissolved in methyl ethyl ketone to prepare a substrate adhesive mixture, which was uniformly coated on the surface of a releasable film of release paper to a thickness of 20 μm, and then dried at 120 ℃ for 3 minutes.

(5) Firstly, transferring the substrate adhesive on the release paper to the second surface with the adhesive of the polyimide film in a transfer printing mode, then cutting the substrate adhesive and the polyimide with the adhesive into a wafer with the diameter of 320mm in a multi-layer laminating material die cutting mode, keeping the release film unchanged, and stripping and removing the redundant leftover materials except the wafer from the release film.

(6) Firstly, a layer of polyolefin heat-shrinkable film with the thickness of 100 mu m is prepared by adopting a multi-layer co-extrusion mode, and then a layer is evaporated on the first surface

Thickness of TiO₂And then modifying the second surface of the silicon wafer by adopting plasma bombardment (Ar 100sccm, 120W-8 minutes). Preparation of UV-sensitive adhesive: adding 100 parts of alkyl acrylate as a main component, adding 30 parts of hydroxyl-containing 2-hydroxyethyl (meth) acrylate as a copolymerization reactant, and adding 2 parts of methyl methacrylate to improve cohesion and heat resistance of the material; adding 20 parts of methacryloyl isocyanate to adjust viscosity, adding 10 parts of polyisocyanate compound as an external cross-linking agent, adding 30 parts of urethane oligomer as an ultraviolet curing agent, and adding 10 parts of 2-methyl-2-2 hydroxy propiophenone as a photopolymerization initiator. The solution obtained by uniformly mixing the above materials is uniformly coated on the second surface of the polyolefin heat-shrinkable film, baked at 90 ℃ for 3 minutes to form an ultraviolet-sensitive adhesive with a thickness of 10 μm, and finally stored in a dark place at 50 ℃ for 24 hours.

(7) And compounding the polyolefin heat-shrinkable film and the polyimide film with the adhesive at normal temperature.

(8) According to DISCO DTF2-8-1 standard, cutting a base film into a ring according to the standard by adopting a half-cutting process commonly used for coiled materials, peeling and removing, keeping a bonding agent for mounting a release film and a wafer flexible chip unchanged to obtain a pre-cut adhesive tape with the diameter of 370mm, uniformly rolling the pre-cut adhesive tape onto an anti-static cylinder with the diameter of 10mm according to the packaging specification of 100 sheets/roll, and sealing and storing by using a shading bag.

(9) A certain 12-inch wafer is ground to 25 micrometers by a grinding and polishing integrated machine (model: Disco DGP8761+ DFM2800inline system), after the grinding and polishing integrated machine is completed, the ultrathin wafer is transferred to a worktable of a film sticking machine through a mechanical arm, the precut adhesive tape is automatically stuck at normal temperature and supported by a standard iron frame, and after the grinding and polishing integrated machine is completed, the front protective film of the wafer is removed.

(10) And cutting along a pre-designed scribing channel by using a full-automatic wafer cutting machine (model: Accertech AD3000T plus) to separate the flexible chips with the adhesive at the bottom one by one. The type of the diamond grinding wheel for cutting is FTBQ132051#2, the rotation speed of the grinding wheel is 40000RPM, the moving speed of the blade is 5mm/s, and the height of the blade is set to be 165 mu m.

(11) The ultra-thin wafer backside tape was irradiated with ultraviolet rays using an ultraviolet irradiation machine (model: Lintec RAD-2010M) to cure the adhesive surface in contact with the substrate adhesive layer. The ultraviolet irradiation conditions were: strength of>120mW/cm²Dosage is 150mJ/cm²。

(12) Placing the cut wafer on a full-automatic chip mounter (model: Datacon EVO2200) to perform chip expansion, and controlling the deformation of a film expansion film within the range of 0.8-1.0 mm according to the chip channel size of a chip design; selecting a spherical thimble head according to the size of the chip, lifting the thimble head to touch the bottom of the cutting adhesive tape and slightly jacking (the speed is 0.5mm/s, the lifting distance is 1.5-2.5 mm), and stripping the chip from the pre-cutting adhesive tape; and a vacuum pick-up head matched with the size of the chip is selected above the chip to adsorb the front surface of the chip, the chip is moved to a corresponding position on the flexible substrate, and the chip is pressed for 10 seconds under the pressure of 2-4 MPa to finish mounting.

(13) And (3) putting the chip after the bonding into a nitrogen oven, and baking for 30 minutes at 150 ℃ to cure the substrate bonding layer.

(14) The bonding pads on the chip surface and the bonding pads on the substrate were interconnected using a gold wire bonder (model: ASM Eagle AERO), the diameter of the gold wire being selected to be 0.8mil (. about.20 μm).

(15) Coating a flexible dielectric layer single-component heating curing epoxy resin adhesive (model: Darbond 6206) on the surface of a mounted passive device, heating a substrate to 80 ℃ on a dispensing machine (model: PVA Delta6), uniformly coating the adhesive on the surface to the thickness of 400 mu m, and curing for 45 minutes at 130 ℃.

The embodiment has the following beneficial effects: firstly, the structure that a layer of polyimide intermediate film is added to the flexible chip bonding film prepared according to the embodiment can realize the support of the flexible chip and the enhancement of the dimensional stability, and is convenient for picking and mounting the chip; secondly, only one layer of the bonding film is pasted in the flexible chip packaging process, so that repeated carrying and pressing of the ultrathin wafer are reduced, the wafer breakage is favorably improved, and the processing efficiency can be improved; finally, the adhesive material on the back of the wafer is acrylic adhesive or organic silica gel, so that the adhesive material has good adhesion at normal temperature, and the workbench does not need to be heated in advance, so that the heating time of the workbench is saved, and the production efficiency is improved.

It is noted that, in this document, relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Claims

1. A flexible chip adhesive film, comprising:

the adhesive film comprises a release film, a supporting layer, a substrate adhesive layer and a base film;

the release film is attached to the first surface of the supporting layer;

the first surface of the substrate bonding layer is attached to the second surface of the supporting layer;

the base film is attached to the second surface of the substrate adhesive layer.

2. The flexible die attach film of claim 1, wherein the adhesive film further comprises:

the first adhesive layer is used for enabling the release film to be attached to the first surface of the supporting layer;

a second adhesive layer for bonding the first surface of the substrate adhesive layer to the second surface of the support layer to form an adhesive composite film by the substrate adhesive layer, the support layer, the first adhesive layer, and the second adhesive layer;

and the third adhesive layer is used for attaching the base film to the second surface of the substrate adhesive layer.

3. The flexible die attach film of claim 2 wherein the adhesive film comprises an adhesive area comprising the adhesive composite film and the release film and a non-adhesive area comprising the release film.

4. The flexible chip attach film of claim 3, wherein the base film on the adhesive region is independent of the base film on the non-adhesive region.

5. The flexible die attach film of any one of claims 1 to 4 wherein the support layer is a polyimide film having a thickness of 10 to 70 μm.

6. The flexible die attach film of any one of claims 1-4, wherein the substrate bonding layer comprises: and (3) epoxy resin.

7. The flexible die attach film of any one of claims 2-4, wherein the first adhesive layer comprises acrylic glue or silicone glue; and/or the second adhesive layer comprises acrylic adhesive or organic silica gel.

8. The flexible die attach film according to any one of claims 2 to 4,

the thickness of the substrate bonding layer is 10-40 mu m;

and/or the thickness of the release film is 50-150 μm;

and/or the thickness of the base film is 50-150 μm;

and/or the thickness of the first bonding layer is 10-30 μm;

and/or the thickness of the second bonding layer is 5-10 mu m;

and/or the thickness of the third bonding layer is 5-20 mu m.

9. A flexible chip packaging structure, comprising a flexible chip and a flexible substrate, wherein the flexible chip and the flexible substrate are fixed by the supporting layer and the substrate bonding layer of the flexible chip bonding film according to any one of claims 1 to 8.