TWI757796B - Healing particle and method for thermoforming - Google Patents

Abstract

A method for thermoforming includes adding a plurality of healing particles into a stack, heating the stack to transform a core of the healing particle into a conductive fluid, stretching the stack that forms a plurality of cracks in a conductive layer of the stack and brakes a shell of the healing particle, releasing the conductive fluid formed of the core from the healing particle which fills the cracks, and forming a plurality of conductive connections by the conductive fluid in the cracks.

Description

Thermoforming repair particles and method

The present disclosure relates to thermoforming repair particles and methods.

In the manufacturing process of non-planar electronic products, forming a curved surface or a non-planar surface of any shape is an important step, and thermoplastic forming is more suitable for electronic products that already carry wires or electronic components. However, in the stretching process of thermoplastic forming, it is easy to damage the conductive material on the substrate and cause wire breakage. With various conductive materials having stretch limit limitations, new development directions are required to increase the stretchability and shapeability of conductive materials.

A repair particle for thermoplastic forming, the repair particle includes an inner core and an outer shell, wherein the inner core has conductivity and a melting point of the inner core lower than the temperature of the thermoplastic forming process, and the outer shell covering the inner core has a temperature higher than the process temperature of the thermoplastic forming. The melting point of the outer shell, and the conductive liquid formed by the inner core will be released after the outer shell is ruptured by force.

A laminate for thermoplastic forming, comprising a substrate, a conductive layer on the substrate, a protective layer on the conductive layer, and a plurality of repair particles added to the laminate, wherein the repair particles include an inner core and an outer shell, and the inner core is heated The conductive liquid is formed during the plastic forming, and the casing is ruptured during the thermoplastic forming to release the conductive liquid.

A method of thermoplastic forming, comprising adding a plurality of repair particles in a laminate, heating the laminate to form a conductive liquid in the inner core of the repair particles, stretching the straight laminate into a curved shape, and forming a plurality of conductive layers in the laminate. The cracks and the outer shells of the repair particles are ruptured by force, the repair particles release the conductive fluid formed by the inner core and fill the cracks, and the conductive fluid forms a plurality of repair conductors in the cracks.

The following disclosure provides many different embodiments or examples for implementing different features of the mentioned subject matter. Specific examples of components, materials, configurations, etc. are described below to simplify the present disclosure. Of course, these are only examples and not limiting. Other components, materials, configurations, etc. are also under consideration. For example, in the following description, forming a first feature on or over a second feature may include embodiments in which the first feature and the second feature are formed in direct contact, and may also include an embodiment between the first feature and the second feature Embodiments in which additional features are formed between them so that the first feature and the second feature may not be in direct contact. Additionally, the present disclosure may repeat reference numerals and/or letters in various instances. This repetition is for the purpose of simplicity and clarity, and does not in itself represent a relationship between the various embodiments and/or configurations discussed.

Furthermore, spatially relative terms, such as "below", "below", "lower", "above", "above", etc., may be used herein to facilitate describing an element or feature as relationship to another element or feature shown. In addition to the orientation shown in the figures, spatially relative terms are intended to encompass different orientations of the device in use or operation. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

The present disclosure discloses a repair particle, which can be applied to a molding process including thermoplastic forming, such as In-Mold Forming (IMF), In-Mold Electron (IME), and the like. Substrates with wires, such as touch layers of flexible or curved touch panels, are heated and stretched in a thermoplastic forming process. Thermoforming examples will be described below, however it should be understood that other variations involving heating and stretching are within the scope of the present disclosure.

The present disclosure discloses a repair particle with a low melting point core, and the repair particle is added to a stack having a conductive layer. When the conductive layer has different degrees of cracks due to different forces on each part during the thermoplastic forming, the repair particles release the conductive liquid formed by the inner core at the same time. The conductive liquid forms a stable conductor in the cracks of the conductive layer, and reduces the resistance value of the conductive layer that was originally increased due to damage, so as to solve the problem of wire breakage caused by thermoplastic forming.

Figures 1A-1C are cross-sectional views of a thermoplastic forming apparatus in the X-Z plane, according to some embodiments. For the purpose of clarity of illustration, FIGS. 1A to 1C only illustrate a simplified thermoplastic forming apparatus. Accordingly, within the scope of the present disclosure, the thermoplastic forming apparatus may include additional components not shown in the figures. The steps of thermoplastic forming include heating, stretching, and cooling, which are shown in Figures 1A to 1C, respectively. Thermoforming, including steps other than heating, stretching, and cooling, is also within the scope of this disclosure.

Figure 1A is a cross-sectional view of a thermoplastic forming apparatus during a heating step, according to some embodiments. The stack 100 is on the mold 110 and the heater 120 is on and covering the stack 100 . The stack 100 includes a stack of substrates, conductive layers, and protective layers, and may include layers of other materials or electronic components therein or thereon. The mold 110 is used in the stretching process, and may include any shape of the laminate 100 after being thermoformed. The heater 120 may heat the stack 100 to a process temperature to soften the substrate, to a degree sufficient to stretch the substrate into a desired shape during subsequent processes.

FIG. 1B is a cross-sectional view of a thermoplastic forming apparatus during a stretching step and the laminate 100 is being stretched, according to some embodiments. In some embodiments, the heater 120 may have an air intake hole H, so that Clean Dry Air (CDA) A may pass through the air intake hole H and be pressurized on the stack 100 in the mold 110 , as described in Section 1. As shown in Figure 1B. In the mold 110 , the softened laminate 100 is gradually stretched and deformed by the pressure of clean and dry air A, so that the originally flat laminate 100 is stretched into a curved shape, and finally the laminate 100 is attached to the upper surface of the mold 110 . In some embodiments, the heater 120 is a pressing plate without an air intake hole H, and the bottom of the mold 110 may have an air suction hole penetrating the mold 110, and the air suction hole can extract the air between the stack 100 and the mold 110, so that the In the stretching step, the laminate 100 is drawn by vacuum to be stretched against the upper surface of the mold 110 . In some embodiments, the heater 120 may have an air inlet hole H, and the bottom of the mold 110 may have an air suction hole penetrating the mold 110 , so that the laminate 100 can be stretched by the pressure and vacuum suction of the clean dry air A at the same time. Fit the upper surface of the mold 110 .

Figure 1C is a cross-sectional view of a thermoplastic forming apparatus during a cooling step, according to some embodiments. The laminate 100 is attached to the upper surface of the mold 110 and is gradually cooled to a non-softening temperature so that the laminate 100 has a stretched shape when released from the mold 110 .

According to some embodiments, FIG. 2 is an enlarged top view of the region R in the X-Y plane of FIG. 1B . For the purpose of clarity of illustration, FIG. 2 only shows the conductive material 104 in the stack 100, however, as mentioned above, the stack 100 may include a substrate, a protective layer, other material layers, electronic components, and the like. During the stretching step, the stretching deformation of the substrate has a destructive force on the conductive material, so that the conductive material 104 in the stack 100 may generate cracks 200 . The cracks 200 may be irregular in shape and are mostly elongated, and the longitudinal direction of the cracks 200 is approximately perpendicular to the direction of the tensile deformation of the laminate 100 . Cracks 200 may occur in conductive material 104 or may occur at the edges of conductive material 104 . The cracks 200 can increase the resistance value of the laminate 100 and cause disconnection.

In order to overcome the phenomenon that the conductive material is cracked and broken during the thermoplastic forming and stretching process, the present disclosure provides a repair particle, and the repair particle is added to the stack including the conductive material, so that the conductive material can be stretched during the stretching process. While damaged, the repair particles repair cracks in the conductive material, reducing resistance differences and component drive issues caused by stretching.

Figure 3 is a cross-sectional view of the stack 300 in the X-Z plane, according to some embodiments. The composition of the stack 300 is similar to that of the stack 100, including but not limited to substrates, conductive materials, protective layers, other material layers, electronic components, etc., and the stack 300 can also be used as depicted in FIGS. 1A-1C in the thermoplastic stretching process. In some embodiments, the flat laminate 300 is curved after the stretching process shown in FIG. 1B , so that the laminate 300 can be a touch layer of a curved or flexible touch panel.

In some embodiments, stack 300 includes substrate 302 , conductive layer 304 and protective layer 306 on substrate 302 . The material of the substrate 302 may be a plastic film (eg, a polycarbonate (PC) film). The melting point (eg, greater than 200° C.) of the substrate 302 is higher than the process temperature (eg, 145° C.) of the heating step in thermoplastic forming, but at the process temperature, the substrate 302 can be softened for subsequent stretching. The material of the conductive layer 304 can be a conductive material such as silver paste, nano-silver, a compound of polydioxyethylthiophene and polystyrene sulfonic acid (PEDOT:PSS), and the melting point of the conductive material can be selected to be in the heat. The plastic forming process temperature will not form a molten state. For example, when the process temperature is 145°C, silver paste (melting point of 960°C), nano-silver (melting point of 150°C), etc. can be used. The material of the protective layer 306 may be oxide, and covers the conductive layer 304 under the protective layer 306 .

Unlike stack 100 , stack 300 incorporates repair particles 400 in conductive layer 304 . In some embodiments, the repairing particles 400 are added to the solution of the conductive layer 304 and coated on the substrate 302 together to form the conductive layer 304 of the stack 300 , as shown in FIG. 3 .

FIG. 4 is a cross-sectional view of conductive particle 400, according to some embodiments. The repair particle 400 is a spherical double-layer structure including a core 402 and an outer shell 404 . In some embodiments, the diameter W of the repair particles 400 may be 1 to 5 microns, although larger or smaller diameters W may also be used.

The inner core 402 of the repairing particle 400 is a conductive material, and is also the main component of the repairing crack in the conductive layer 304 . In some embodiments, the inner core 402 has the property of being flowable during the heating step of thermoforming. The melting point of the inner core 402 may be selected to be between the thermoplastic forming process temperature and room temperature, so that the inner core 402 is in a molten state during the stretching step. The conductive liquid formed by the molten inner core 402 can simultaneously fill the cracks caused by the stretching during the process of the conductive layer 304 being stretched and stressed, so that the increased resistance value of the conductive layer 304 due to damage decreases, so as to repair the conductive layer 304 the goal of.

In some embodiments, the molten core 402 can form a solid at room temperature during the cooling step of thermoplastic forming and become a stable conductor connecting the cracks in the conductive layer 304 . In other embodiments, the melting point of the inner core 402 may be lower than room temperature. After the conductive layer 304 is repaired, the conductive liquid of the inner core 402 may form an oxide layer on the surface of the fluid during the thermoplastic forming and cooling step to limit the flow behavior of the inner core 402 fluid. , to form stable conductors in the cracks of the conductive layer 304 . In some embodiments, the material of the core 402 includes gallium (melting point 29.76°C), gallium indium alloy (eutectic point 21.4°C) or tin-bismuth alloy (eutectic point 139°C).

In some embodiments, the inner core 402 may include carbon black dissolved in an organic solvent (eg, toluene). The inner core 402 including carbon black has flowable properties during the stretching step of thermoplastic forming, fills the cracks in the conductive layer 304, and removes the organic solvent by drying, so that the carbon black in the inner core 402 forms a conductive conductive layer with a stable connection in the cracks. solid.

The outer shell 404 of the repair particles 400 is a layer of material that keeps the repair particles 400 dispersed. In some embodiments, the inner core 402 forms or maintains a conductive liquid state during the heating step of thermoplastic forming, but before the conductive layer 304 cracks due to stretching, the outer shell 404 can protect the inner core 402 and isolate the conductive liquid of the inner core 402 from the conductive liquid. Conductive layer 304 . When the conductive layer 304 is cracked during the stretching step, the outer shell 404 is also broken by the tensile stress, so that the conductive liquid formed by the inner core 402 is released and the conductive layer 304 is repaired. In some embodiments, in order to prevent the outer shell 404 from prematurely breaking and releasing the inner core 402 before the conductive layer 304 is stretched and fractured, the outer shell 404 may include heat resistance and solvent resistance, so that the outer shell 404 will not melt or generate at the process temperature. Chemical reaction, wherein the solvent is the solvent for coating the conductive layer 304 solution (eg, water, ethanol, diethyl ether, isopropanol, diethylene glycol monobutyl ether, etc.). In some embodiments, the housing 404 includes an organic polymer (eg, poly(urea-formaldehyde) (PUF)) or a metal oxide (eg, tin dioxide, gallium oxide).

According to some of the above embodiments, the repairing particles 400 are added in the conductive layer 304 . When the stack 300 is heated to the process temperature, the inner core 402 of the repairing particles 400 is in the form of conductive liquid and is separated from the conductive layer 304 through the outer shell 404 . When the conductive layer 304 is stretched and molded to produce cracks with different degrees of fracture, the outer shells 404 of the repair particles 400 around the cracks are also cracked, and the released conductive liquid of the inner core 402 fills the cracks in the conductive layer 304 . When the laminate 300 is cooled, the conductive liquid in the inner core 402 in the cracks also forms a stable conductor, connecting the cracks in the conductive layer 304 and reducing the resistance value originally increased due to the damage of the conductive layer 304 . In some embodiments, when the volume of the conductive layer 304 and the repairing particles 400 is used as the denominator, the addition amount of the repairing particles 400 has a repairing effect when the amount is 10 vol% to 30 vol%.

Referring to FIGS. 3 and 5, FIG. 5 shows an enlarged top view of the conductive layer 304 in the region R in the X-Y plane during the stretching step of the stack 300 in FIG. 1B. In the stretching step, the substrate 302 softened by the process temperature is stretched and deformed, so that the conductive layer 304 on the substrate 302 is deformed and cracks 500 are generated. At the same time, the outer shells 404 of the repair particles 400 around the cracks 500 in the conductive layer 304 are ruptured by tensile stress, and the conductive liquid formed by the inner core 402 is released. The crack 500 in the conductive layer 304 formed by the conductive liquid formed by the inner core 402 forms the repair conductor 402 ′, and is cured to form a stable conductor in the crack 500 in the subsequent process. In some embodiments, the repair conductor 402' filling the crack 500 in the conductive layer 304 may be completely filled. In some embodiments, the repair conductor 402 ′ fills the crack 500 in the conductive layer 304 , and the repair conductor 402 ′ can contact the opposite part of the sidewall on both sides of the crack. In some embodiments, the crack 500 may have a plurality of repair conductors 402' in it.

6-8 are cross-sectional views of stack 600, stack 700, and stack 800 in the X-Z plane, according to some embodiments. The composition of stacks 600 to 800 is similar to that of stack 300 containing repair particles 400, including but not limited to substrates, conductive materials, protective layers, other material layers, electronic components, etc., and stacks 600 to 800 can also be used In the thermoplastic stretching process as depicted in Figures 1A to 1C.

Stacks 600 to 800 differ from stack 300 in that repair particles 400 are added at different locations in the stack. In some embodiments, as shown in FIG. 6 , the repair particles 400 may be added to the solution of the protective layer 606 and coated on the conductive layer 604 together to form the protective layer 606 of the stack 600 . In some embodiments, as shown in FIG. 7, the repair particles 400 may be added in a solvent and coated on the substrate 702 to form a particle layer 708 under the conductive layer 704, wherein the solvent may be water or an organic solvent (eg , ethanol, ether). In some embodiments, as shown in FIG. 8, the repair particles 400 can be added in a solvent and coated on the conductive layer 804 to form a particle layer 808 on the conductive layer 804, wherein the solvent can be water or an organic solvent ( For example, ethanol, ether). The repair particles 400 in the stacks 600 to 800 repair the cracks in the conductive layer in the same manner as the stack 300, although the locations where the repairing particles 400 are added are different.

The present disclosure discloses a repair particle for thermoplastic forming. The repair particle includes a core and a shell, wherein the core has conductivity and a melting point of the core lower than the temperature of the thermoplastic forming process. . The present disclosure also discloses a method of thermoplastic forming, which includes adding a plurality of repairing particles in a laminate, the repairing particles release a conductive liquid formed by an inner core due to the force of the outer shell during the stretching process of the thermoplastic forming, and the conductive liquid is filled into Cracks in the conductive layer are formed and repaired conductors are formed. In the cracks, the resistance value raised by the conductive layer due to cracks is reduced, and the tensile ability of the conductive material is improved.

The foregoing outlines the features of some embodiments so that those skilled in the art may better understand the concepts of the disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments described herein. It should also be understood by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the present disclosure.

100: Laminate 104: Conductive layer 110: Mold 120: Heater 200,500: Rift 300,600,700,800: Laminate 302,602,702,802: Substrates 304,604,704,804: Conductive layer 306,606,706,806: Protective Layer 400: Fix Particles 402: Kernel 404: Shell 402′: Repair conductor 708,808: Particle Layer A: Clean and dry air H: air intake R: area W: diameter X, Y, Z: axis

Aspects of the present disclosure are best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be noted that in accordance with standard methods in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or decreased for clarity of reference. FIGS. 1A-1C illustrate cross-sectional views of a thermoplastic forming apparatus during various steps of the thermoplastic forming process, according to some embodiments. FIG. 2 illustrates a top view of a conductive material during a stretching process, according to some embodiments. FIG. 3 is a cross-sectional view of a stack of adding repair particles to a conductive layer, according to some embodiments. FIG. 4 illustrates a cross-sectional view of a repair particle, according to some embodiments. FIG. 5 is a top view of a conductive material to which repair particles are added during a stretching process, according to some embodiments. FIGS. 6 to 8 illustrate stacked cross-sectional views of material layers other than the conductive layer with repair particles added, according to some embodiments.

300: Laminate 302: Substrate 304: Conductive layer 306: Protective Layer 400: Fix Particles X, Z: axis

Claims (9)

A laminate for thermoplastic forming, comprising: a substrate; a conductive layer on the substrate, wherein the conductive layer includes a plurality of cracks after the thermoplastic forming; a protective layer on the conductive layer; a plurality of A repair particle is added to the stack, wherein each repair particle includes a core and a shell surrounding the core, wherein the core has electrical conductivity and a core melting point lower than the thermoplastically formed one process temperature, the core forms a conductive liquid in the thermoplastic forming, wherein the shell has a melting point of the shell is higher than the process temperature of the thermoplastic forming, the shell ruptures in the thermoplastic forming to release the conductive liquid, so that The conductive liquid forms a plurality of repair conductors in the cracks that reduce the resistance value of the conductive layer. The laminate according to claim 1, wherein the addition positions of the repair particles include in the conductive layer, between the conductive layer and the substrate, between the conductive layer and the protective layer, or in the protective layer. The laminate according to claim 1, wherein with the volume of the conductive layer and the repair particles as the denominator, the addition amount of the repair particles is in the range of 10vol% to 30vol%. The laminate of claim 1, wherein the longitudinal directions of the cracks are approximately perpendicular to the stretching direction of the thermoplastic, and the repair conductors connect opposite sidewalls of the cracks. The laminate according to claim 1, wherein the laminate is a touch layer of a touch panel. A method of thermoplastic forming, comprising: adding a plurality of repair particles in a stack; heating the stack to make a core of each repair particle form a conductive liquid; stretching the stack to make the stack straight The layer is stretched into a curved shape, a conductive layer of the stack forms a plurality of cracks and has a rising resistance value, and at the same time, an outer shell of each repair particle is broken by force; each repair particle releases the conductive layer formed by the inner core. liquid, the conductive liquid fills the cracks; and the conductive liquid forms a plurality of repair conductors in the cracks, so that the resistance value of the conductive layer decreases. The method of claim 6, wherein the inner core is in a molten state after being heated, and the conductive liquid formed by the inner core is cooled to form the repair conductors. The method of claim 6, wherein the inner core is in a liquid state after heating, and the conductive liquid formed by the inner core is dried to form the repairs complex conductor. The method of claim 6, wherein the method is applied to in-mold forming or in-mold electronics.

Images