Chip transfer method, backplane, manufacturing method of backplane and display panel

Abstract

The present application relates to a chip transfer method, a backboard, a manufacturing method of the backboard and a display panel. The chip transfer method comprises: providing a backboard, the backboard comprising a substrate, a flexible circuit layer and a plurality of deformation units; controlling a first group of deformation units on the backboard to deform, so that a region of the flexible circuit layer corresponding to the first group of deformation units forms a height difference with a region of the flexible circuit layer corresponding to other deformation units; abutting a side of a chip carrier plate on which chips are arranged against the backboard, at least part of the chips on the chip carrier plate being in contact with a region of the flexible circuit layer closer to the chip carrier plate; and transferring the chips in contact with the flexible circuit layer to the flexible circuit layer. The chip transfer method realizes selective chip transfer and direct chip transfer to the backboard to shorten the manufacturing process.

Description

Technical Field

[0001] This invention relates to the field of chip transfer, and more particularly to a chip transfer method, a backplane, a method for manufacturing the backplane, and a display panel. Background Technology

[0002] Micro-LED (Micro-Light Emitting Diode) technology is an emerging display technology. Compared with conventional display technologies, displays based on Micro-LED technology have the characteristics of fast response speed, self-illumination, high contrast, long lifespan, and high photoelectric efficiency.

[0003] In the manufacturing processes of Micro-LED, Mini-LED (Mini-Light Emitting Diode), and conventional LED (Light Emitting Diode), tens of thousands or even millions of chips need to be transferred to a backplane. Wafer production costs are a significant factor limiting the mass production of Micro-LEDs. According to current technology, the wafer arrangement must match the backplane arrangement, and may even require RGB (Red, Green, Blue) multi-color transfer, necessitating chip spacing and reducing utilization. Furthermore, existing RGB transfer methods require multiple transfers and cannot be directly transferred onto the backplane.

[0004] Therefore, how to selectively transfer chips to the backplane is an urgent problem to be solved. Summary of the Invention

[0005] In view of the shortcomings of the above-mentioned related technologies, the purpose of this application is to provide a chip transfer method, a backplane, a backplane manufacturing method, and a display panel, in order to solve the problem that the related technologies cannot achieve the selective transfer of chips directly to the backplane.

[0006] A chip transfer method, comprising:

[0007] A backplane is provided, the backplane including a substrate, a flexible circuit layer and a plurality of deformation units, the deformation units being disposed between the substrate and the flexible circuit layer, each deformation unit corresponding to at least one chip bonding region on the flexible circuit layer, the chip bonding region being used to bond with the electrode of a chip, each deformation unit being capable of deforming along the thickness direction of the substrate under predetermined conditions, so as to cause the height of the flexible circuit layer region corresponding to the deformation unit to change in the thickness direction of the substrate;

[0008] The first group of deformation units on the backplane is controlled to deform, so that the area of ​​the flexible circuit layer corresponding to the first group of deformation units forms a height difference with the area of ​​the flexible circuit layer corresponding to other deformation units.

[0009] The side of the chip carrier with the chips arranged is attached to the backplate, and at least a portion of the chips on the chip carrier are in contact with the area of ​​the flexible circuit layer that is closer to the chip carrier.

[0010] The chip that is in contact with the flexible circuit layer is transferred onto the flexible circuit layer.

[0011] The aforementioned chip transfer method uses deformation units to deform the flexible circuit layer, creating regions of varying heights. When the chip carrier and backplane are bonded together, only the higher regions contact the chip, while the regions corresponding to the remaining deformation units do not. This prevents the chip from being bonded to the other regions; only the chip in contact with the flexible circuit layer is bonded. This achieves selective chip transfer and also allows for direct transfer of the chip to the backplane, shortening the manufacturing process. Because of the selective chip transfer capability, the chip carrier can be densely packed with chips, improving utilization.

[0012] Optionally, after transferring the chip that is in contact with the flexible circuit layer onto the flexible circuit layer, the method further includes:

[0013] The second set of deformation units on the backplane is controlled to deform so that the area on the flexible circuit layer where the chip needs to be placed is higher than the chip currently placed on the backplane.

[0014] The side of the chip carrier with the chips arranged is attached to the back plate, and at least a portion of the chips on the chip carrier are in contact with the region in the flexible circuit layer corresponding to the second group of deformation units.

[0015] The chip that is in contact with the flexible circuit layer is transferred onto the flexible circuit layer.

[0016] Understandably, by controlling the deformation unit, other chips can be selectively transferred to the backplane as well.

[0017] Based on the same inventive concept, this application also provides a backplane, comprising: a substrate; a flexible circuit layer; and a plurality of deformation units, wherein the deformation units are disposed between the substrate and the flexible circuit layer, each deformation unit corresponds to at least one chip bonding region on the flexible circuit layer, the chip bonding region being used to bond with the electrode of a chip, and each deformation unit being capable of deforming along the thickness direction of the substrate under predetermined conditions, thereby causing the height of the flexible circuit layer region corresponding to the deformation unit to change in the thickness direction of the substrate.

[0018] The aforementioned substrate can be used in the chip transfer process. By controlling the deformation units to cause the flexible circuit layer to deform, regions of different heights are formed. In this way, when the chip carrier and the backing plate are bonded together, only the higher regions can contact the chip, while the regions corresponding to the other deformation units will not contact the chip due to the height difference. Thus, the chip will not be bonded to the other regions. Only the chip that contacts the flexible circuit layer is bonded, achieving selective direct transfer of the chip.

[0019] Optionally, the substrate is further provided with a positioning groove, the size of which matches the deformation unit, and the deformation unit is disposed in the positioning groove.

[0020] Understandably, the positioning groove is designed to ensure that the position of the deformation unit is accurately set and that the position of the deformation unit does not shift.

[0021] Optionally, the flexible circuit layer includes a flexible substrate and a conductive layer, the conductive layer including a flexible redundant portion; the total length of the flexible redundant portion is greater than the straight-line distance between its two ends, and it is used to deform with the substrate when the substrate deforms in order to maintain the electrical connection between the two ends of the flexible redundant portion.

[0022] It is understandable that by setting the above-mentioned flexible redundant part in the conductive layer, the conductive layer is not easy to break, thus ensuring that electrical connection can be achieved.

[0023] Optionally, the deformation unit includes a piezoelectric module;

[0024] The piezoelectric module includes a length-deformable piezoelectric crystal, positive and negative electrodes disposed at both ends of the piezoelectric crystal, and a power controller connected to the positive and negative electrodes. The extension direction of the length-deformable piezoelectric crystal is parallel to the thickness direction of the substrate.

[0025] It is understandable that piezoelectric modules using length-deformable piezoelectric crystals are stable and easy to control.

[0026] Based on the same inventive concept, this application also provides a method for manufacturing a backplane, comprising: providing a substrate; disposing of a plurality of deformation units on the substrate; disposing of a flexible circuit layer on the substrate; after the flexible circuit layer is disposed, each deformation unit corresponds to at least one chip bonding region on the flexible circuit layer, the chip bonding region being used for bonding with the electrode of a chip, and each deformation unit being capable of deforming along the thickness direction of the substrate under predetermined conditions, thereby causing the height of the flexible circuit layer region corresponding to the deformation unit to change in the thickness direction of the substrate.

[0027] The backplane fabricated by the above method has deformation units that can raise or lower the corresponding areas of the flexible circuit layer, creating a height difference between the various areas of the flexible circuit layer. This ensures that during chip transfer, the chip can only contact the highest area of ​​the flexible circuit layer, while other areas remain off-limits, preventing chip bonding to other regions. Selective bonding is possible when transferring the chip to this backplane.

[0028] Based on the same inventive concept, this application also provides a display panel, the display panel including a back plate and a light-emitting chip electrically connected to the back plate;

[0029] The light-emitting chip is transferred to the backplane using the chip transfer method described in the above example.

[0030] Because the aforementioned display panel uses the chip transfer method described above, the chip transfer can be performed in a shorter manufacturing process, and the chip utilization rate during the transfer is high. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the basic process of the chip transfer method provided in the embodiments of the present invention;

[0032] Figure 2 A schematic diagram of the backplate provided in an embodiment of the present invention. Figure 1 ;

[0033] Figure 3 A schematic diagram of a substrate with a positioning groove provided in an embodiment of the present invention;

[0034] Figure 4 This is a schematic diagram illustrating the relationship between the depth of the positioning groove and the length of the deformation unit provided in an embodiment of the present invention;

[0035] Figure 5 A schematic diagram of a backplane with a chip transferred according to an embodiment of the present invention;

[0036] Figure 6 A schematic diagram of the flexible circuit layer provided in an embodiment of the present invention. Figure 1 ;

[0037] Figure 7 A schematic diagram of the flexible circuit layer provided in an embodiment of the present invention. Figure 2 ;

[0038] Figure 8 A schematic diagram of the flexible circuit layer provided in an embodiment of the present invention. Figure 3 ;

[0039] Figure 9 This is a schematic diagram of the structure of the piezoelectric module provided in an embodiment of the present invention;

[0040] Figure 10 This is a schematic diagram illustrating the deformation of the first group of deformation units provided in an embodiment of the present invention.

[0041] Figure 11 This is a schematic diagram showing the side of the chip carrier board with the chips arranged on it being bonded to the backplate in an embodiment of the present invention.

[0042] Figure 12 A schematic diagram of laser selective stripping of an LED chip provided in an embodiment of the present invention;

[0043] Figure 13 This is a further flowchart illustrating the chip transfer method provided in an embodiment of the present invention;

[0044] Figure 14 This is a schematic diagram of a backplane with a chip transferred according to an embodiment of the present invention;

[0045] Figure 15 This is a schematic diagram illustrating the deformation of the second set of deformation units provided in an embodiment of the present invention.

[0046] Figure 16 A schematic diagram of the transfer of a green LED chip provided in an embodiment of the present invention;

[0047] Figure 17 This is a schematic diagram illustrating the deformation of the third group of deformation units provided in an embodiment of the present invention.

[0048] Figure 18 A schematic diagram of the transfer of a red LED chip provided in an embodiment of the present invention;

[0049] Figure 19 A schematic diagram illustrating the completion of LED chip transfer for three colors provided in an embodiment of the present invention;

[0050] Figure 20 A schematic diagram of the basic process of a method for manufacturing a backplate according to another optional embodiment of the present invention;

[0051] Figure 21 A schematic diagram of forming a positioning groove provided for another optional embodiment of the present invention;

[0052] Figure 22 This is a schematic diagram of a deformation unit disposed in a positioning groove, which is provided as another optional embodiment of the present invention;

[0053] Explanation of reference numerals in the attached figures:

[0054] 1-Substrate; 11-Positioning groove; 2-Deformation unit; 201-First group of deformation units; 202-Second group of deformation units; 203-Third group of deformation units; 21-Piezoelectric crystal; 22-Positive and negative electrodes; 23-Power controller; 3-Flexible circuit layer; 31-Flexible substrate; 32-Pad; 33-Flexible redundancy part; 4-Chip; 41-Blue LED chip; 42-Green LED chip; 43-Red LED chip. Detailed Implementation

[0055] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0057] In related technologies, it is not possible to selectively transfer chips directly to the backplane.

[0058] Therefore, this application aims to provide a solution that can solve the above-mentioned technical problems, the details of which will be described in subsequent embodiments.

[0059] Example:

[0060] This embodiment provides a chip transfer method; please refer to [link to relevant documentation]. Figure 1 The chip transfer method includes:

[0061] S101, Provide back panel;

[0062] S102. The first set of deformation units on the control backplane deforms so that the area of ​​the flexible circuit layer corresponding to the first set of deformation units forms a height difference with the area of ​​the flexible circuit layer corresponding to other deformation units.

[0063] S103, The side of the chip carrier with the chips arranged is attached to the backplate, and at least some of the chips on the chip carrier are in contact with the area of ​​the flexible circuit layer that is closer to the chip carrier.

[0064] S104. Transfer the chip that is in contact with the flexible circuit layer onto the flexible circuit layer.

[0065] The chip transfer method provided in this embodiment uses deformation units to deform the flexible circuit layer, creating regions of different heights. When the chip carrier and backplane are bonded together, only the higher (closer to the chip carrier) regions can contact the chip. The regions corresponding to the remaining deformation units will not contact the chip due to the height difference, thus preventing chip bonding to these regions. Only the chip in contact with the flexible circuit layer is bonded. This achieves selective chip transfer and also allows for direct chip transfer to the backplane, shortening the manufacturing process. Because selective chip transfer is possible, the chip carrier can be densely packed with chips, improving utilization.

[0066] The chips transferred in this embodiment include, but are not limited to, various LED chips, such as Mini-LED chips and Micro-LED chips. When the chip is a variety of LED chips, the backplane may include an LED display backplane, and the flexible circuit layer includes a driving circuit structure for driving the LED chips. However, it is understood that, in addition to LED chips, the chip transfer method of this embodiment can also be applied to other chips.

[0067] To facilitate understanding of the chip transfer method in this embodiment, the backplane described above will be explained first. For example... Figure 2 The backplane described in this embodiment includes a substrate 1, a flexible circuit layer 3, and a plurality of deformation units 2. The deformation units 2 are disposed between the substrate 1 and the flexible circuit layer 3. Each deformation unit 2 corresponds to at least one chip bonding region on the flexible circuit layer 3. The chip bonding region is used to bond with the electrodes of the chip. Each deformation unit 2 can deform along the thickness direction of the substrate 1 under predetermined conditions, so as to change the height of the flexible circuit layer 3 region corresponding to the deformation unit 2 in the thickness direction of the substrate 1. It can be understood that the region of the flexible circuit layer 3 corresponding to the deformation unit 2 includes the chip bonding region.

[0068] In this embodiment, the backplane uses deformation units to cause the flexible circuit layer to undulate. In one example, the deformation units can be fixed to the flexible circuit layer to better facilitate changes in the flexible circuit layer. For instance, the side of the deformation unit closest to the flexible circuit layer is bonded to it. Regardless of whether the deformation unit lengthens or shortens in the thickness direction of the substrate, the corresponding area of ​​the flexible circuit layer changes position accordingly. It is understood that the area of ​​the flexible circuit layer corresponding to the first group of deformation units includes at least one chip bonding area. In another example, the deformation units may not be fixed to the flexible circuit layer. The deformation units simply push the flexible circuit layer away from the substrate to achieve the effect of changing the height of the corresponding flexible circuit layer area in the thickness direction of the substrate. In this example, the flexible circuit layer can be a flexible circuit layer with a certain degree of elasticity. When the deformation unit retracts, the flexible circuit layer also returns to its original height. It should be noted that the height referred to in this embodiment can be considered as the height when the backplane is placed horizontally with the side used to set the chip facing upwards, for example, with reference to the placement direction in the accompanying drawings provided in this embodiment. The distance between the side of the substrate closest to the flexible circuit layer and the flexible circuit layer can be considered as the height of the flexible circuit layer in the thickness direction of the substrate. In some examples, for flexible circuit layer areas without corresponding deformation units, they can also be bonded and fixed to the substrate by means including but not limited to adhesive bonding.

[0069] To better fix and support the deformation unit, the substrate used for the back plate in this embodiment can be a rigid substrate, that is, a rigid material, including but not limited to silicon, quartz, etc.

[0070] In some embodiments, the substrate is further provided with positioning grooves, such as Figure 3 As shown, the dimensions of the positioning groove 11 match those of the deformation unit 2, and the deformation unit 2 is disposed in the positioning groove 11. The positioning groove 11 ensures that the position of the deformation unit 2 can be accurately set and that the position of the deformation unit 2 does not shift.

[0071] The depth of the positioning groove can be the same as or different from the length of the deformation unit, for example... Figure 3 In the example backplane, the depth of the positioning groove is less than the default length of the deformation unit. This means that even without any control over the deformation unit, it still lifts up a portion of the flexible circuit layer by default. Of course, in other examples, such as... Figure 4 As shown, the depth of the positioning groove 11 can also be greater than the default length of the deformation unit 2, see [reference]. Figure 5In this example, after chip 4 is transferred to the backplane, the control of deformation unit 2 can be removed, so that deformation unit 2 can be restored to its default length. A part of chip 4 can be lowered below the plane of substrate 1, that is, the distance between chip 4 and the other side of substrate 1 is less than the thickness of substrate 1. This can reduce the overall thickness of the backplane after the chip is set, or achieve other effects.

[0072] In this embodiment, both the internal space of the positioning groove and the overall shape of the deformation unit are cylindrical structures, which facilitates the deformation of the deformation unit in the length direction.

[0073] The flexible circuit layer can be fixed to the substrate in areas where no deformation units are provided. This portion of the flexible circuit layer fixed to the substrate will not deform. It is understood that the circuit layer fixed to the substrate can also be non-flexible. At the interface between the deformation unit and the substrate, a portion of the flexible circuit layer is not fixed to the substrate or the deformation unit, allowing this portion of the flexible circuit layer to be stretched to a certain extent. In some embodiments, the flexible circuit layer includes a flexible substrate and a conductive layer. The conductive layer includes a flexible redundant portion, the total length of which is greater than the straight-line distance between its two ends. This redundant portion deforms with the substrate when it deforms, maintaining the electrical connection between the two ends of the flexible redundant portion.

[0074] As a concrete example, see Figure 6 As shown, the flexible substrate 31 of the flexible circuit layer has pads 32 for soldering the positive and negative electrodes of the chip, and other parts of the conductive layer except for the flexible redundancy portion 33. One end of the flexible redundancy portion 33 is connected to the pad 32, and the other end is connected to other parts of the conductive layer. The flexible redundancy portion 33 is arranged on the flexible substrate 31 in a serpentine manner and is not adhered to the flexible substrate 31. The length of the flexible redundancy portion 33 is greater than the straight-line distance between the pad 32 and other parts of the conductive layer. When the flexible circuit layer is deformed by the deformation unit, the flexible substrate 31 may be stretched. At this time, the straight-line distance between the pad 32 and other parts of the conductive layer is increased, and correspondingly, the flexible redundancy portion 33 is stretched and unfolded to a certain extent to ensure that the overall electrical connection of the flexible circuit layer remains unbroken. Figure 7 as well as Figure 8 For example, in other embodiments, the flexible redundancy portion 33 may also be arc-shaped, zigzag-shaped, etc. The material of the flexible redundancy portion 33 may be a conductive metal, including but not limited to copper, aluminum, iron, silver, and gold; to better ensure electrical connection, a metal material with good ductility or elasticity may be selected. As an example of the flexible substrate 31, the flexible substrate 31 may be selected from an insulating flexible material, which may be a polymer including but not limited to polyimide (PI) film.

[0075] The deformation unit in this embodiment may include, but is not limited to, electro-deformable materials, thermo-deformable materials, etc., which deform when predetermined conditions are met in terms of voltage, temperature, etc. As a specific example, the deformation unit includes a piezoelectric module, which is based on the inverse piezoelectric effect, that is, it can be induced to deform under the action of an electric field. For example, the structure of a piezoelectric module is as follows... Figure 9 As shown, it includes a piezoelectric crystal 21, positive and negative electrodes 22 disposed on both sides of the piezoelectric crystal 21, and a power controller 23 connected to the positive and negative electrodes 22. The power controller 23, in conjunction with the positive and negative electrodes 22, applies an external electric field to the piezoelectric crystal 21. Under the action of the external electric field, the piezoelectric crystal 21 generates internal tensile stress, and the piezoelectric crystal 21 extends along the direction of the electric field. By controlling the intensity of the applied external electric field, the elongation of the piezoelectric crystal 21 can also be changed. When using the above-mentioned piezoelectric module, the piezoelectric crystal can be a length-deformable piezoelectric crystal, and the extension direction of the length-deformable piezoelectric crystal is parallel to the thickness direction of the substrate.

[0076] Based on the reasonable control of the backplane illustrated above, the chip transfer method of this embodiment can selectively and directly transfer the chip to the backplane. The chip transfer method of this embodiment will be further described below with reference to the accompanying drawings, based on the backplane described above.

[0077] like Figure 10 In step S102 above, controlling the deformation of the first set of deformation units 201 can be to elongate the first set of deformation units 201 in the thickness direction of the substrate 1. The first set of deformation units 201 raises the area corresponding to the flexible circuit layer 3, making the flexible circuit layer 3 in this area higher than other areas. In other examples, the first set of deformation units 201 can also undergo shortening deformation, pulling down the area corresponding to the flexible circuit layer 3, similarly creating a height difference with the flexible circuit layer 3 in other areas.

[0078] In this embodiment, the first set of deformation units can be selected according to the chip transfer requirements. For example, when the deformation unit is extended, the first set of deformation units can be the deformation unit corresponding to the area of ​​the flexible circuit layer of the chip to be transferred. The first set of deformation units raises the area of ​​the flexible circuit layer where the chip will be placed, so that the chip can be placed on this area in subsequent steps of the chip transfer method in this embodiment. Conversely, if the deformation unit is shortened, the first set of deformation units can be the deformation unit corresponding to the area of ​​the flexible circuit layer where the chip will not be transferred during this chip transfer process. The flexible circuit layer in this area is pulled down, so that it does not contact the chip on the chip carrier in subsequent steps, and therefore the chip will not be transferred. In some examples, if the deformation unit can both extend and shorten, the first group of deformation units can be all the deformation units on the backplane. The deformation units corresponding to the areas where the flexible circuit layer of the chip needs to be set are extended, while the deformation units corresponding to the other areas where the chip does not need to be set are shortened. This makes the height difference between different areas of the final flexible circuit layer twice the deformation amount of each deformation unit. That is, a larger height difference is formed with a smaller deformation amount, which helps to reduce the requirements for the flexibility of the flexible circuit layer.

[0079] In some practical applications, the aforementioned height difference is set to be greater than a predetermined value to avoid the influence of tolerances. For example, the height difference is made greater than the overall thickness variation that chips and other structures may experience due to warping or other reasons, ensuring that only the higher regions of the flexible circuit layer can contact the chip's electrodes. In other words, the specific degree of deformation of the first set of deformation units can be selected according to actual needs and tolerance requirements.

[0080] The chip carrier can be a chip growth substrate on which chips are grown, or a transfer substrate with chips, etc., with the chips arranged on at least one side of the chip carrier. For example... Figure 11 In step S103 above, the side of the chip carrier with the chips 4 arranged therein is bonded to the backplane. Due to the height difference formed by different regions in the flexible circuit layer 3, when the higher region of the flexible circuit layer 3 contacts the chip 4 on the chip carrier, the lower region of the flexible circuit layer 3 cannot contact the chip 4. It is understood that before the chip 4 contacts the flexible circuit layer 3 on the backplane, the two poles of the chip 4 are aligned with the chip bonding area, for example, by using CCD (Charge-coupled Device) alignment technology.

[0081] In step S104 above, the chip is detached from the chip carrier and transferred to the flexible circuit layer. For example, the chip can first be bonded to a backplane, meaning the electrodes of the chip are fixed to the chip bonding area of ​​the flexible circuit layer by methods including but not limited to soldering and bonding. After the chip is bonded to the backplane, it is then detached from the chip carrier. The chip detached from the chip carrier should be the chip currently being transferred; that is, chip removal is selective. As a specific example, the chip carrier includes a growth substrate on which LED chips are grown. The LED chip includes a buffer layer, which is connected to the growth substrate. For example, the buffer layer of the LED chip can be, but is not limited to, gallium nitride (GaN) material. When irradiated by a laser, GaN absorbs laser energy, thereby heating up and decomposing into nitrogen gas and metallic gallium. Figure 12 As shown, after the LED chips on the growth substrate are bonded to the backplane, the LED chips that need to be transferred are selectively irradiated with a laser A of a set wavelength, causing the buffer layer of the LED chips to decompose and the LED chips that need to be transferred to be peeled off from the growth substrate.

[0082] After a chip has been transferred onto the backplane for the first time, more chips can be transferred onto the backplane. Please refer to [link / reference]. Figure 13 After step S104 above, the following may also be included:

[0083] S105. Control the second set of deformation units on the backplane to deform so that the area on the flexible circuit layer where the chip needs to be placed is higher than the chip currently placed on the backplane.

[0084] S106. The side of the chip carrier with the chips arranged is attached to the back plate, and at least some of the chips on the chip carrier are in contact with the area in the flexible circuit layer corresponding to the second set of deformation units.

[0085] S107. Transfer the chip that is in contact with the flexible circuit layer onto the flexible circuit layer.

[0086] Similarly, the second set of deformation units is also selected based on the chip transfer requirements. The deformation units can be controlled to raise the flexible circuit layer area where the chip needs to be installed during the transfer, or to lower the flexible circuit layer area where the chip does not need to be installed during the transfer.

[0087] like Figure 14 As an example, deformation unit 2 can only elongate under predetermined conditions. After the first chip transfer is completed, the control over the first set of deformation units is removed, and the first set of deformation units can return to its original length. Depending on the desired location of the chip to be transferred, the second set of deformation units is controlled to deform, that is, the second set of deformation units elongates, to raise the corresponding area of ​​the flexible circuit layer 3. For example... Figure 15As shown, since chip 4 is already disposed on the backplane, to prevent subsequent chips from touching the already transferred chip 4 on the backplane, in any subsequent chip transfer process except the first chip transfer, the height of the area where the chip needs to be disposed on the flexible circuit layer 3 should be greater than the height of the top surface of the currently disposed chip 4. In this embodiment, the top surface of the chip refers to the side of chip 4 away from the substrate 1.

[0088] In some implementation processes, when transferring chips, it is also necessary to ensure that there is a certain safe distance between the chips on the backplane and the chips on the chip carrier. That is, the height difference between the regions of each flexible circuit layer corresponding to the deformation unit is greater than the sum of the height and tolerance of the chips already set on the backplane and the safe distance that the chips need to be spaced apart.

[0089] For subsequent chips, the transfer process after contact with the flexible circuit layer can be the same as described above, and will not be repeated here.

[0090] Other chips can be transferred using the steps described above. Simply control the deformation unit to perform the corresponding deformation according to the chip transfer requirements. This embodiment does not limit the number of chip transfers.

[0091] As a more specific example, a single-color LED chip is set on a single chip carrier board, and the RGB three-color display backplate can be made using the chip transfer method described above.

[0092] In this example, one color of LED chip is first transferred to the backplane, for example... Figure 10 As shown, the first set of deformation units 201 is first controlled to extend. Since no chips are yet installed on the backplane, the first set of deformation units 201 only needs to raise the corresponding flexible circuit layer area to a level higher than other areas of the flexible circuit layer 3. This can be achieved through methods including but not limited to the above. Figures 11-12 In this example, the blue LED chip is transferred to the corresponding area of ​​the flexible circuit layer.

[0093] After the blue LED chip transfer is complete, the first set of deformation units 201 can be restored to its default shape, and the second set of deformation units 202 can be controlled to extend. The structure at this time is as described above. Figure 15 In this example, the second set of deformation units 202 corresponds to the area on the flexible circuit layer 3 used to set the green LED chip 42. At this time, the second set of deformation units raises the corresponding area of ​​the flexible circuit layer above the top surface of the existing blue LED chip on the backplate. Figure 16As shown, the side of the growth substrate or chip carrier on which the green LED chip 42 is grown or supported is attached to the back plate. The green LED chip 42 contacts the area of ​​the flexible circuit layer 3 raised by the second set of deformation units 202, but does not contact other areas or the already placed blue LED chips 41. Similarly, by means including but not limited to the above example, the green LED chip 42 is transferred to the back plate. The green LED chip 42 on the chip carrier can only contact the area of ​​the flexible circuit layer 3 corresponding to the second set of deformation units 202. Therefore, only this part of the area is transferred with the green LED chip 42.

[0094] See Figure 17 After the green LED chip 42 is transferred, the second set of deformation units 202 can be restored to its default shape, and the third set of deformation units 203 can be extended. In this example, the third set of deformation units 203 corresponds to the area on the flexible circuit layer 3 used to set the red LED chip 43. At this time, the third set of deformation units 203 raises the area corresponding to the flexible circuit layer 3 to a height above the top surface of the blue LED chip 41 and the green LED chip 42. Figure 18 As shown, the side of the growth substrate or chip carrier on which the red LED chip 43 is grown or supported is attached to the backplate. The red LED chip 43 contacts the area of ​​the flexible circuit layer 3 raised by the third set of deformation units 203, but does not contact other areas or the already placed blue LED chips 41 and green LED chips 42. The red LED chip 43 is then transferred to the backplate. Of course, after the transfer of the red LED chip 43 is completed, the third set of deformation units 203 can also be restored to its default shape, such as... Figure 19 As shown. By directly transferring the RGB chips using the above chip transfer method, the manufacturing process of the display backplane can be shortened, and the selective transfer also improves chip utilization. The chips can be grown and manufactured in a close-packed manner.

[0095] This embodiment also provides a display panel, which includes a backplane and light-emitting chips electrically connected to the backplane. The light-emitting chips are transferred to the backplane using the chip transfer method described above. Because the display panel employs the chip transfer method described above, the chip transfer can be performed through a shorter manufacturing process, and the chip utilization rate during transfer is high.

[0096] Another optional embodiment of the present invention:

[0097] This embodiment provides a backplane and a method for manufacturing the backplane. As described in the foregoing examples, the backplane provided in this embodiment can be used in the chip transfer process to achieve selective direct chip transfer. For the structure and use of the backplane, please refer to the relevant descriptions related to the backplane in the above embodiments.

[0098] The method for manufacturing the backplate in this embodiment can be used to manufacture the aforementioned backplate. Please refer to [link to relevant documentation]. Figure 20 The method for manufacturing the backplate provided in this embodiment includes:

[0099] S201, Provide a substrate;

[0100] S202. Multiple deformation units are disposed on the substrate;

[0101] S203. A flexible circuit layer is disposed on the substrate;

[0102] After the flexible circuit layer is set, each deformation unit corresponds to at least one chip bonding area on the flexible circuit layer. The chip bonding area is used to bond with the electrode of the chip. Each deformation unit can deform along the thickness direction of the substrate under predetermined conditions, so as to change the height of the flexible circuit layer area corresponding to the deformation unit in the thickness direction of the substrate.

[0103] In some implementations, the surface of the substrate may be treated before the deformation units are installed. When the deformation units are installed, their arrangement follows the layout of the chips to be installed on the substrate. For example, in one embodiment, for a display backplane, where LED chips are arranged in an array of RGB pixels, the deformation units are also arranged in an array of pixels.

[0104] When setting up a flexible circuit layer, care should be taken to align the chip bonding area of ​​the flexible bonding layer with the positions of each deformation unit. This alignment process can also be achieved using CCD alignment technology or other methods. The flexible circuit layer can be bonded to the substrate using adhesive bonding processes. In some implementations, the flexible circuit layer is also bonded to the deformation units. It is understandable that, since the deformation units deform in the thickness direction of the backplane, at least a portion of the flexible circuit layer at the interface between the deformation unit and the substrate is not bonded to the substrate or the deformation unit, leaving a stretchable area.

[0105] In some embodiments, a positioning groove is also provided on the back plate to better fix the deformation units and ensure accurate positioning. Therefore, before setting multiple deformation units on the back plate, the following may also be included:

[0106] S204. Form a positioning groove on the substrate;

[0107] Understandably, the dimensions of the resulting positioning groove match the deformation unit.

[0108] In the embodiment where a positioning groove is formed, S203 above includes placing the deformation unit in the positioning groove.

[0109] As an example, the following illustrates a process for making a back panel.

[0110] This example provides a rigid substrate made of silicon or quartz, and the surface of the substrate is treated. The substrate 1 is etched, for example, by photolithography, to create positioning grooves 11 on the substrate 1. Figure 21 As shown; during the etching process, the etching area can be selected according to the final layout of the chip to be set, thereby forming the positioning groove 11. Through high-precision photolithography, the positioning groove 11 is formed in a very accurate position, and the final backplane is of good quality.

[0111] like Figure 22 The deformation unit 2, including but not limited to piezoelectric modules, is set into the positioning groove 11. In this example, the default length of the deformation unit 2 is greater than the depth of the positioning groove 11, so the deformation unit 2 protrudes from the positioning groove 11.

[0112] The backplate is fabricated by bonding the flexible circuit layer to the substrate and the surface of the deformation unit away from the substrate using an adhesive bonding process, as described above. Figure 2 As shown. The flexible circuit layer on the side of the deformation unit is not bonded to the substrate or the deformation unit. When the deformation unit elongates or shortens, this part of the flexible circuit layer deforms accordingly.

[0113] The backplane fabrication method of this embodiment produces a backplane in which the deformation units can raise or lower the corresponding areas of the flexible circuit layer, creating a height difference between the various areas of the flexible circuit layer. This ensures that during chip transfer, the chip can only contact the highest area of ​​the flexible circuit layer, while other areas remain uncontacted, preventing the chip from being bonded to other areas. When transferring the chip to this backplane, selective bonding with the backplane is possible, achieving selective transfer.

[0114] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A chip transfer method, characterized in that, include: A backplane is provided, the backplane including a substrate, a flexible circuit layer and a plurality of deformation units, the deformation units being disposed between the substrate and the flexible circuit layer, each deformation unit corresponding to at least one chip bonding region on the flexible circuit layer, the chip bonding region being used to bond with the electrode of a chip, each deformation unit being capable of deforming along the thickness direction of the substrate under predetermined conditions, so as to cause the height of the flexible circuit layer region corresponding to the deformation unit to change in the thickness direction of the substrate; The first group of deformation units on the backplane is controlled to deform, so that the area of ​​the flexible circuit layer corresponding to the first group of deformation units forms a height difference with the area of ​​the flexible circuit layer corresponding to other deformation units. The side of the chip carrier with the chips arranged is attached to the backplate, and at least a portion of the chips on the chip carrier are in contact with the area of ​​the flexible circuit layer that is closer to the chip carrier. The chip that is in contact with the flexible circuit layer is transferred onto the flexible circuit layer; After transferring the chip that is in contact with the flexible circuit layer onto the flexible circuit layer, the process further includes: The second set of deformation units on the backplane is controlled to deform so that the area on the flexible circuit layer where the chip needs to be placed is higher than the chip currently placed on the backplane. The side of the chip carrier with the chips arranged is attached to the back plate, and at least a portion of the chips on the chip carrier are in contact with the region in the flexible circuit layer corresponding to the second group of deformation units. The chip that is in contact with the flexible circuit layer is transferred onto the flexible circuit layer.

2. The chip transfer method as described in claim 1, characterized in that, After transferring the chip that is in contact with the flexible circuit layer onto the flexible circuit layer, the process further includes: The third set of deformation units on the backplane is controlled to deform so that the area on the flexible circuit layer where the chip needs to be placed is higher than the chip currently placed on the backplane. The chip carrier with the chips arranged on it is attached to the backplate, and at least a portion of the chips on the chip carrier are in contact with the region in the flexible circuit layer corresponding to the third group of deformation units.

3. The chip transfer method as described in claim 1 or 2, characterized in that, The chip transfer method further includes: After all the chips have been transferred, the deformation unit is restored to a preset state.

4. A backplane for performing the chip transfer method as described in any one of claims 1 to 3, characterized in that, include: substrate; Flexible circuit layer; The system includes multiple deformation units disposed between the substrate and the flexible circuit layer. Each deformation unit corresponds to at least one chip bonding region on the flexible circuit layer. The chip bonding region is used to bond with the electrode of the chip. Each deformation unit can deform along the thickness direction of the substrate under predetermined conditions, thereby causing the height of the flexible circuit layer region corresponding to the deformation unit to change in the thickness direction of the substrate.

5. The backplate as described in claim 4, characterized in that, The substrate is also provided with a positioning groove, the size of which matches the deformation unit, and the deformation unit is disposed in the positioning groove.

6. The backplate as described in claim 4, characterized in that, The flexible circuit layer includes a flexible substrate and a conductive layer, and the conductive layer includes a flexible redundant portion. The total length of the flexible redundant part is greater than the straight-line distance between its two ends, and it is used to deform with the substrate when the substrate deforms in order to maintain the electrical connection between the two ends of the flexible redundant part.

7. The backplate as described in any one of claims 4-6, characterized in that, The deformation unit includes a piezoelectric module; The piezoelectric module includes a length-deformable piezoelectric crystal, positive and negative electrodes disposed at both ends of the piezoelectric crystal, and a power controller connected to the positive and negative electrodes. The extension direction of the length-deformable piezoelectric crystal is parallel to the thickness direction of the substrate.

8. A method for manufacturing a back panel, used to manufacture the back panel as described in any one of claims 4 to 7, characterized in that, include: Provide substrate; Multiple deformation units are disposed on the substrate; A flexible circuit layer is disposed on the substrate; After the flexible circuit layer is set, each deformation unit corresponds to at least one chip bonding area on the flexible circuit layer. The chip bonding area is used to bond with the electrode of the chip. Each deformation unit can deform along the thickness direction of the substrate under predetermined conditions, so as to change the height of the flexible circuit layer area corresponding to the deformation unit in the thickness direction of the substrate.

9. The method for manufacturing the back panel as described in claim 8, characterized in that, Before the plurality of deformation units are disposed on the substrate, the method further includes: A positioning groove is formed on the substrate, the size of which matches the deformation unit; The provision of multiple deformation units on the substrate includes: placing the deformation units within the positioning groove.

10. A display panel, characterized in that, The display panel includes a backplate as described in any one of claims 4 to 7 and a light-emitting chip electrically connected to the backplate; The light-emitting chip is transferred to the backplane using the chip transfer method according to any one of claims 1-3.

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