WO2023151234A1

WO2023151234A1 - Preparation method for flexible electronic device

Info

Publication number: WO2023151234A1
Application number: PCT/CN2022/107566
Authority: WO
Inventors: 冯雪; 焦阳; 王鹏; 简巍; 马寅佶
Original assignee: 清华大学
Priority date: 2022-02-11
Filing date: 2022-07-25
Publication date: 2023-08-17
Also published as: CN114520080B; CN114520080A

Abstract

The present application provides a preparation method for a flexible electronic device, comprising: forming a conductive layer (1) in a predetermined shape, and forming packaging layers (2) on the front and back surfaces of the conductive layer (1); and etching the packaging layers (2), so that a stress concentration area is generated on each packaging layer (2), transferring the conductive layer (1) and the packaging layers (2) together to a seal (8), applying a load to the stress concentration area of each packaging layer (2), so that part of the packaging layer (2) is subjected to shear failure and peeled off, thereby removing part of the packaging layer (2), and enabling the packaging layers (2) to be formed into a repeatedly bent and coiled linear shape which is the same as that of the conductive layer (1).

Description

Fabrication method of flexible electronic device

References to related applications

This application claims the priority of the prior invention patent application submitted in China with the application date of February 11, 2022, the application number 202210127766.0, and the title of the invention is "Preparation Method of Flexible Electronic Devices", and the entire content of the prior application Incorporated herein by reference.

technical field

The present application belongs to the field of flexible electronic devices, and in particular relates to a preparation method of flexible electronic devices.

Background technique

Flexible electronic devices are extensible and bendable, which greatly expands the application environment of electronic devices. Flexible electronic devices are developing in the direction of high performance and multi-modality, and the integration level is gradually increasing. In order to ensure the reliability of the function of flexible electronic devices, it is necessary to prepare fine wire structures and conduct reasonable packaging. However, the existing photolithography process is more suitable for precision processing of silicon-based materials, metals, etc., and it is difficult to process polymer-based packaging materials. Micro-nano processing technologies such as laser cutting and reactive ion etching are expensive and energy-intensive, and high-precision processing of devices with narrow linewidths is inefficient.

Contents of the invention

The purpose of this application is to propose a method for preparing a flexible electronic device, so that the manufacturing cost of the flexible electronic device is low, and it can be easily mass-produced.

The present application proposes a method for preparing a flexible electronic device, including:

forming a conductive layer with a predetermined shape, and forming an encapsulation layer on both sides of the conductive layer;

Etching the encapsulation layer to generate a stress concentration area in the encapsulation layer, transferring the conductive layer and the encapsulation layer to the stamp, and applying a load to the stress concentration area of the encapsulation layer to make part of the encapsulation layer The encapsulation layer is peeled off due to shear failure, thereby removing a part of the encapsulation layer, so that the encapsulation layer forms the same repeated bending and coiled wire shape as the conductive layer.

Preferably, before the encapsulation layer is peeled off, the thickness of the encapsulation layer is reduced as a whole, so as to increase the stress concentration level and facilitate the peeling of the encapsulation layer due to shear failure.

Preferably, before etching the encapsulation layer, a masking layer is prepared on the encapsulation layer, and according to the structure of the flexible electronic device, part of the masking layer is removed, so that the masking layer forms a Layers have the same or similar shape, and the masking layer is used to protect the conductive layer and the encapsulation layer.

Preferably, the etch depth is measured prior to transfer to said stamp,

If the etching depth does not reach the first critical point, continue etching;

If the etching depth is just at the first critical point or between the first critical point and the second critical point, the expected requirement is met;

If the etching depth reaches the second critical point, the flexible electronic device is scrapped; wherein

The first critical point is to etch the encapsulation layer until the upper edge of the encapsulation layer is flush with the lower edge of the conductive layer,

The second critical point is to etch the encapsulation layer to the sacrificial layer in contact with the encapsulation layer.

Preferably, when the encapsulation layer is peeled off, a load is applied to the stress concentration area by pressurized gas.

Preferably, the conductive layer includes a conductive layer main body and an adhesive layer, and the conductive layer main body is attached to the encapsulation layer through the adhesive layer.

Preferably, after forming the conductive layer with a predetermined shape, substances and/or structures that affect the resistance change sensitivity of the conductive layer are removed.

Preferably, said encapsulation layer is made of polymer.

Preferably, the encapsulation layer is made of polyimide.

By adopting the above technical solution, the present application can obtain at least one of the following beneficial effects.

(1) By forming a stress concentration area and peeling off redundant packaging layers, the manufacturing cost of flexible electronic devices is reduced, the production efficiency is improved, and it is suitable for mass production.

(2) Measuring the relationship between the etching depth and the first critical point and the second critical point during the manufacturing process of flexible electronic devices can improve the success rate of stripping off redundant packaging layers by forming stress concentration areas, thereby improving production efficiency.

(3) The packaging material that is difficult to achieve fine processing using the existing technology is processed by peeling off the redundant packaging layer by forming a stress concentration area. The stress concentration area is originally a part of the structure on the packaging layer of the flexible electronic device. The formation of the stress concentration area has low requirements for equipment processing accuracy, and is especially suitable for the processing of narrow line width (linear) flexible electronic devices.

Description of drawings

FIG. 1 shows a flowchart of a method for fabricating a flexible electronic device according to an embodiment of the present application.

Fig. 2 shows a schematic diagram of the steps of the method for manufacturing a flexible electronic device according to an embodiment of the present application.

Fig. 3 shows a schematic diagram of applying pressure to a flexible electronic device in step S9 of the manufacturing method according to an embodiment of the present application.

Fig. 4 shows a schematic diagram of the scanning of the etching depth reaching the first critical point in step S6 of the manufacturing method of the flexible electronic device according to the embodiment of the present application.

Fig. 5 shows a schematic diagram of the scanning of the etching depth reaching the second critical point in step S6 of the manufacturing method of the flexible electronic device according to the embodiment of the present application.

FIG. 6 shows a schematic structural view of a flexible electronic device in step S1 of the manufacturing method according to an embodiment of the present application.

Fig. 7 shows a schematic structural view of a flexible electronic device in step S2 of the manufacturing method according to an embodiment of the present application.

Fig. 8 shows a schematic structural view of a flexible electronic device in step S3 of the manufacturing method according to an embodiment of the present application.

FIG. 9 shows a schematic structural view of a flexible electronic device in step S4 of the manufacturing method according to an embodiment of the present application.

Fig. 10 shows a schematic structural view of a flexible electronic device in step S5 of the manufacturing method according to an embodiment of the present application.

11A to 11C show schematic structural views of a flexible electronic device in step S6 of the manufacturing method according to an embodiment of the present application.

12A and 12B show a schematic structural view of a flexible electronic device according to an embodiment of the present application in step S7 of the manufacturing method.

13A and 13B show a schematic structural view of a flexible electronic device in step S8 of the manufacturing method according to an embodiment of the present application.

14A and 14B show a schematic structural view of a flexible electronic device in step S9 of the manufacturing method according to an embodiment of the present application.

15A and 15B show a schematic structural view of a flexible electronic device in step S10 of the manufacturing method according to an embodiment of the present application.

Explanation of reference signs

1 Conductive layer 11 Conductive layer main body 12 Adhesive layer

2 encapsulation layer 3 base layer 4 sacrificial layer 5 substrate 6 photoresist 7 masking layer 8 seal.

Detailed ways

In order to more clearly illustrate the above purpose, features and advantages of the present application, specific implementation methods of the present application will be described in detail in this part with reference to the accompanying drawings. In addition to the various implementations described in this section, the present application can also be implemented in other different ways. Without departing from the spirit of the present application, those skilled in the art can make corresponding improvements, deformations and replacements. Therefore, the present application Do not be bound by the specific embodiments disclosed in this section. The scope of protection of this application should be based on the claims.

As shown in Figures 1 to 15B, the present application proposes a method for preparing a flexible electronic device, such as a flexible temperature sensor, which includes a conductive layer 1 (made of gold Au and/or chromium Cr for example), a package A layer 2 (made of a polymer, eg PI, ie polyimide) and a base layer 3 (eg made of PLA, ie polylactic acid). The flexible electronic device may also be a flexible antenna.

The conductive layer 1 is connected with electrodes, and the encapsulation layer 2 wraps the front and back sides of the conductive layer 1 and exposes the electrodes. The electrodes enable the conductive layer 1 to be electrically connected to external devices. The function of the encapsulation layer 2 is to prevent the short circuit of the conductive layer 1, and the encapsulation layer can be made of other materials with poor electrical conductivity and good thermal conductivity except polyimide. The electrodes can be extended longer, so as to facilitate the connection of external devices that are far away from the detection site with flexible electronic devices.

The conductive layer 1 includes a thermosensitive material, the resistivity of the thermosensitive material can change with temperature, and the temperature measurement can be realized by the resistivity of the conductive layer 1 changing with temperature.

It can be understood that in the flexible temperature sensor of the above embodiment, the conductive layer 1 includes a thermosensitive material, but the application is not limited thereto, the flexible electronic device may be other types of sensors, and the corresponding conductive layer may also be other conductive materials. For example, in other embodiments, the flexible electronic device may be a flexible pressure sensor, and the conductive layer may include a pressure-sensitive material.

15A and 15B, in this embodiment, the conductive layer 1 may include a conductive layer body 11 and an adhesive layer 12, the conductive layer body 11 may include gold (Au), and the adhesive layer 12 may include chromium (Cr). The conductive layer 1 may include other materials other than gold whose resistivity changes under the influence of temperature. The conductive layer 1 may be formed in a bent coil shape to have ductility.

The base layer 3 is used to carry the conductive layer 1 and the encapsulation layer 2 , and the base layer 3 may have a curved shape similar to that of the conductive layer 1 and the encapsulation layer 2 , so as to have ductility. The base layer 3 can be made of other materials with good thermal conductivity except polylactic acid, and the base layer 3 can have properties such as degradability, shape memory, and light transmission.

As shown in FIG. 1 to FIG. 15B , the method for fabricating a flexible electronic device is described by taking a flexible temperature sensor as an example, which includes the following steps.

S1: Prepare the first encapsulation layer, referring to Figure 1 and Figure 6, prepare the sacrificial layer 4 on the substrate 5, and prepare the encapsulation layer 2 on the sacrificial layer 4, that is to say, the sacrificial layer 4 is sandwiched between the substrate 5 and the encapsulation layer between 2. The substrate 5 can be made of silicon (Si), the sacrificial layer 4 can be made of polymethyl methacrylate (PMMA), and the packaging layer 2 can be made of polyimide (PI). The role of the sacrificial layer 4 is to facilitate the peeling of other structures from the substrate 5 in the subsequent transfer step.

S2: prepare conductive layer 1, with reference to Fig. 1 and Fig. 7, prepare conductive layer 1, conductive layer 1 can comprise the conductive layer main body 11 of such as gold (Au) layer and the pasting layer 12 such as chromium (Cr) layer, pasting layer 12 It is helpful to stick the encapsulation layer 2 and the conductive layer main body 11 together.

S3: Structure the conductive layer 1. Referring to FIG. 1 and FIG. 8, structure the conductive layer 1, and form the originally sheet-shaped conductive layer 1 into a predetermined shape by using a method such as photolithography. Photoresist 6 remains on the surface of conductive layer 1 after photolithography.

S4: prepare the second encapsulation layer, with reference to Fig. 1 and Fig. 9, remove the photoresist 6 formed in step S3 and prepare encapsulation layer 2 on conductive layer 1, encapsulation layer 2 can select polyimide (PI) for use, like this, Both front and back sides of the conductive layer 1 cover the encapsulation layer 2 .

It can be understood that removing the photoresist 6 can avoid the influence of the photoresist 6 on the temperature sensitivity of the resistance of the conductive layer 1. If the step S3 adopts other methods except photolithography to structure the conductive layer 1, the influence should also be eliminated. Substances and/or structures that are sensitive to the change in electrical resistance of the conductive layer 1 with temperature are removed.

S5: Prepare the masking layer 7, referring to Figure 1 and Figure 10, prepare the masking layer 7, prepare the masking layer 7 on the encapsulation layer 2, and perform photolithography to the masking layer 7 to form a predetermined shape, after photolithography, on the surface of the masking layer 7 Photoresist 6 remains. The masking layer 7 can be selected from copper (Cu), and the masking layer 7 is a masking material for subsequent steps. The masking layer 7 is designed according to the structure of the conductive layer 1 of the flexible electronic device, and the masking layer 7 is used to protect the necessary conductive layer 1 and the encapsulation layer. 2 will not be damaged in subsequent etching steps. The structure of the shielding layer 7 is the same as that of the conductive layer 1, or the shielding layer 7 is slightly shorter than the conductive layer 1, so as to expose the electrodes of the conductive layer 1 and facilitate the connection of the electrodes to external devices.

S6: Remove part of the encapsulation layer material to form a stress concentration area. Referring to Figure 1, Figure 4, Figure 5 and Figure 11A to Figure 11C, the values of the first critical point and the second critical point are calculated according to the thickness of each layer, and according to the measured values Etching depth, choose to execute the corresponding step. The etched encapsulation layer 2 can be formed into the same predetermined shape as the conductive layer 1, and the etching depth can be measured by scanning the etched surface by means such as a profilometer, an atomic force microscope, etc., to obtain a height profile. FIG. 4 corresponds to the scanning schematic diagram in which the etching depth is the first critical point shown in FIG. 11A , and FIG. 5 corresponds to the scanning schematic diagram in which the etching depth is the second critical point shown in FIG. 11C .

The first critical point is to etch the encapsulation layer until its upper edge is flush with the lower edge of the conductive layer 1 . The second critical point is to etch the encapsulation layer 2 to the sacrificial layer 4 .

If the measured etching depth does not reach the first critical point, continue etching.

If the measured etching depth is just at the first critical point, execute S7.

If the measured etching depth is between the first critical point and the second critical point (excluding the second critical point), S7 is executed.

If the measured etching depth reaches the second critical point, the product is discarded and no subsequent steps are performed.

S7: transfer to the stamp 8, with reference to Figure 1, Figure 12A and Figure 12B, the above structure is peeled off from the substrate 5, and transferred to the stamp 8, the stamp 8 can be made of flexible materials, for example, the stamp 8 can be made of polydimethyl Made of silicone (PDMS).

FIG. 12A and FIG. 12B respectively correspond to the form in which the structures shown in FIG. 11A and FIG. 11B in the previous step are transferred to the stamp 8 .

S8: Reduce the thickness of the encapsulation layer 2. Referring to FIG. 1, FIG. 13A and FIG. 13B, reduce the thickness of the encapsulation layer 2 (but the encapsulation layer should not be completely removed), so as to increase the stress concentration level and facilitate the execution of step S9.

FIG. 13A and FIG. 13B respectively correspond to the morphology of the structure shown in FIG. 12A and FIG. 12B in the previous step after reducing the thickness of the encapsulation layer 2 .

S9: Peel off the excess encapsulation layer, refer to Figure 3, Figure 1, Figure 14A and Figure 14B, apply a load to the encapsulation layer 2, peel off the excess encapsulation layer from the edge of the stress concentration area, if the stress concentration level is sufficient to peel off the excess encapsulation layer, Step S8 can be skipped, and step S9 is directly executed after step S7. It will be appreciated that the adequacy of the stress concentration level can be related to the applied load. The load on the stress concentration area can be applied by pressurized gas, and the excess packaging layer will be peeled off due to the stress concentration, resulting in shear failure.

Referring to FIG. 14A, step S8 can be skipped and the load can be applied directly, and the excess packaging layer can be peeled off from the edge of the stress concentration area. As shown in FIG. 14B, the load can be applied after step S8, and the excess packaging layer can be peeled off from the edge of the stress concentration area. layer.

S10: transfer to the base layer, referring to FIG. 1 , FIG. 15A and FIG. 15B , the above structure is transferred to the base layer 3 to obtain a flexible temperature sensor.

Fig. 15A is the flexible temperature sensor obtained by skipping step S8. The thickness of the encapsulation layer 2 on the conductive layer 1 side (lower side) is thicker. Fig. 15B is the flexible temperature sensor obtained through step S8. The conductive layer 1 side (lower side) ) encapsulation layer 2 is thinner.

The flexible temperature sensor needs to be calibrated before use to determine the corresponding relationship between resistance change and temperature change, specifically, to measure resistance at different temperatures.

In addition to flexible temperature sensors used in the body, this patent can also be used for flexible temperature sensors in vitro and flexible temperature sensors for non-human applications.

Advantages of the present invention include:

(1) By forming a stress concentration area and peeling off redundant packaging layers, the manufacturing cost of the flexible temperature sensor is reduced, the production efficiency is improved, and it is suitable for mass production.

(2) Measuring the relationship between the etching depth and the first critical point and the second critical point during the manufacturing process of the flexible temperature sensor can improve the success rate of peeling off the redundant packaging layer by forming a stress concentration area, thereby improving production efficiency.

(3) The encapsulation material which is difficult to achieve fine processing by using the existing technology is processed by peeling off the excess encapsulation layer by forming a stress concentration area. The stress concentration area is originally a part of the structure on the packaging layer of the flexible electronic device. The formation of the stress concentration area has low requirements for equipment processing accuracy, and is especially suitable for the processing of narrow line width (linear) flexible electronic devices.

Although the present application has been described in detail using the above-mentioned embodiments, it is obvious to those skilled in the art that the present application is not limited to the embodiments described in this specification. The present application can be modified and implemented as modified embodiments without departing from the spirit and scope of the present application defined by the claims. Therefore, the description in this specification is for the purpose of illustration and does not have any restrictive meaning to this application.

Claims

A method for preparing a flexible electronic device, characterized in that it comprises:

forming a conductive layer (1) of a predetermined shape, and forming an encapsulation layer (2) on both sides of the conductive layer (1);

Etching the encapsulation layer (2), causing the encapsulation layer (2) to produce a stress concentration area, transferring the conductive layer (1) and the encapsulation layer (2) to the stamp (8) together, by The stress concentration area of the packaging layer (2) applies a load, causing a part of the packaging layer (2) to be sheared and peeled off, thereby removing part of the packaging layer (2), and making the packaging layer (2) It is formed in the same shape as the conductive layer (1) which is repeatedly bent and coiled.
The method for preparing a flexible electronic device according to claim 1, characterized in that, before peeling off the packaging layer (2), the thickness of the packaging layer (2) is reduced as a whole, so as to increase the stress concentration level to facilitate the packaging The layer (2) was sheared and peeled off.
The method for preparing a flexible electronic device according to claim 1, characterized in that, before etching the encapsulation layer (2), a masking layer (7) is prepared on the encapsulation layer (2), and according to the The structure of the flexible electronic device, removing part of the masking layer (7), so that the masking layer (7) is formed into the same or similar shape as the conductive layer (1), and the masking layer (7) is used to protect The conductive layer (1) and the encapsulation layer (2).
The method for preparing a flexible electronic device according to claim 1, wherein the etching depth is measured before being transferred to the stamp (8),

If the etching depth does not reach the first critical point, continue etching;

If the etching depth is just at the first critical point or between the first critical point and the second critical point, the expected requirement is met;

If the etching depth reaches the second critical point, the flexible electronic device is scrapped; wherein

The first critical point is to etch the encapsulation layer (2) until the upper edge of the encapsulation layer (2) is flush with the lower edge of the conductive layer (1),

The second critical point is to etch the encapsulation layer (2) to the sacrificial layer (4) in contact with the encapsulation layer (2).
The preparation method of the flexible electronic device according to claim 1, characterized in that, when peeling off the encapsulation layer (2), a load is applied to the stress concentration area by pressurized gas.
The method for preparing a flexible electronic device according to claim 1, wherein the conductive layer (1) comprises a conductive layer body (11) and an adhesive layer (12), and the conductive layer body (11) passes through the An adhesive layer (12) is attached to the encapsulation layer (2).
The method for preparing a flexible electronic device according to claim 1, characterized in that, after forming the conductive layer (1) of a predetermined shape, removing substances that affect the resistance change sensitivity of the conductive layer (1) and/or structure.
The method for preparing a flexible electronic device according to claim 1, characterized in that the encapsulation layer (2) is made of polymer.
The method for preparing a flexible electronic device according to claim 1, characterized in that the encapsulation layer (2) is made of polyimide.