CN113193094B - Batch transfer method and display panel - Google Patents

Batch transfer method and display panel Download PDF

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Publication number
CN113193094B
CN113193094B CN202110460227.4A CN202110460227A CN113193094B CN 113193094 B CN113193094 B CN 113193094B CN 202110460227 A CN202110460227 A CN 202110460227A CN 113193094 B CN113193094 B CN 113193094B
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photoresist layer
photoresist
transfer method
batch transfer
thickness
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CN113193094A (en
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董小彪
姚志博
盛翠翠
钱先锐
葛泳
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Chengdu Vistar Optoelectronics Co Ltd
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Chengdu Vistar Optoelectronics Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L25/00—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof
    • H01L25/03—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes
    • H01L25/04—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes the devices not having separate containers
    • H01L25/075—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes the devices not having separate containers the devices being of a type provided for in group H01L33/00
    • H01L25/0753—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes the devices not having separate containers the devices being of a type provided for in group H01L33/00 the devices being arranged next to each other
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/15—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission
    • H01L27/153—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission in a repetitive configuration, e.g. LED bars
    • H01L27/156—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission in a repetitive configuration, e.g. LED bars two-dimensional arrays
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/62—Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2933/00—Details relating to devices covered by the group H01L33/00 but not provided for in its subgroups
    • H01L2933/0008—Processes
    • H01L2933/0033—Processes relating to semiconductor body packages
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2933/00—Details relating to devices covered by the group H01L33/00 but not provided for in its subgroups
    • H01L2933/0008—Processes
    • H01L2933/0033—Processes relating to semiconductor body packages
    • H01L2933/0066—Processes relating to semiconductor body packages relating to arrangements for conducting electric current to or from the semiconductor body

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Computer Hardware Design (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Manufacturing & Machinery (AREA)
  • Electroluminescent Light Sources (AREA)

Abstract

The embodiment of the invention discloses a batch transfer method and a display panel. The batch transfer method comprises the following steps: forming at least two patterned photoresist layers on the back plate, wherein the patterns of the at least two patterned photoresist layers are the same; forming a solder column in the opening of the photoresist layer; wherein the solder columns are used for welding the light-emitting device; removing at least a portion of the photoresist layer and bonding the light emitting device to the backplane. Compared with the prior art, the embodiment of the invention reduces the risk of short circuit of the welding points in the processing and using processes of the display panel.

Description

Batch transfer method and display panel
Technical Field
The embodiment of the invention relates to the technical field of display, in particular to a batch transfer method and a display panel.
Background
With the development of Display technology, the Display mode gradually changes from Cathode Ray Tube (CRT), liquid Crystal Display (Liquid Crystal Display), organic Light-Emitting Diode (OLED) to Micro LED (Micro LED).
The Micro-LED display technology has the advantages of high brightness, high response speed, low power consumption, long service life and the like, and becomes a research hotspot of a new generation of display technology. In the process of manufacturing Micro-LED display panels, it is a crucial one-step process to realize physical bonding and electrical connection of light emitting devices (typically light emitting device chips) and a backplane. In the prior art, a batch transfer method is adopted for connecting the light emitting device and the back plate, however, with the improvement of the PPI, the conventional batch transfer method causes the risk of short circuit of welding points in the processing and using processes of the Micro-LED display panel.
Disclosure of Invention
The embodiment of the invention provides a batch transfer method and a display panel, which are used for reducing the risk of short circuit of welding points of the display panel in the processing and using processes.
In order to achieve the technical purpose, the embodiment of the invention provides the following technical scheme:
a batch transfer method, comprising:
forming at least two patterned photoresist layers on the back plate, wherein the patterns of the at least two patterned photoresist layers are the same;
forming a solder column in the opening of the photoresist layer; wherein the solder columns are used for welding the light-emitting device;
removing at least a portion of the photoresist layer and bonding the light emitting device to the backplane.
Optionally, the removing at least part of the photoresist layer comprises:
removing a portion of the photoresist layer and leaving a portion of the photoresist layer on the backplate.
Optionally, the corrosion resistance of the remaining photoresist layer is greater than the corrosion resistance of the removed photoresist layer;
preferably, the remaining material of the photoresist layer includes: polybenzocyclobutene or epoxy resin polymers.
Optionally, doping a colored material in the remained photoresist layer;
preferably, the coloured material comprises: white pigments or gray pigments.
Optionally, the remaining thickness of the photoresist layer is less than or equal to the thickness of the solder pillar.
Optionally, the thickness of the photoresist layer removed is less than the thickness of the remaining photoresist layer.
Optionally, the photoresist layer comprises a first photoresist layer and a second photoresist layer;
the forming of the patterned at least two photoresist layers on the backplane comprises:
forming a patterned first photoresist layer on the back plate;
forming a patterned second photoresist layer on the first photoresist layer;
the removing of the portion of the photoresist layer includes:
and stripping the second photoresist layer, wherein the first photoresist layer remains on the back plate.
Optionally, the removing at least part of the photoresist layer comprises:
and removing all the photoresist layer.
Optionally, the total thickness of the photoresist layer is 10% to 50% higher than the thickness of the solder column. For example, the total thickness of the photoresist layer is 10%, 20%, 30%, 40%, or 50% higher than the thickness of the solder pillar.
Optionally, the photoresist layer is a negative photoresist.
Accordingly, the present invention also provides a display panel comprising: the light emitting device is transferred onto the back plate by using the batch transfer method according to any embodiment of the invention.
According to the embodiment of the invention, at least two photoresist layers are respectively manufactured in the process of manufacturing the photoresist layers, so that the thickness of each photoresist layer is thinner, the difficulty of patterning holes on the photoresist layers is reduced, the risk of lateral erosion at the bottoms of the photoresist layers is reduced, and the uniformity of the holes is improved. Thus, uniformity in the size of the solder column is improved in the step of fabricating the solder column. Therefore, the uniformity of electrical connection between each light-emitting device and the back plate is improved in the bonding process of the light-emitting devices and the back plate, and the risk of short circuit of welding points in the processing and using processes of the display panel is reduced.
Drawings
FIG. 1 is a schematic diagram of a batch transfer method according to the prior art, which is formed in each step;
FIG. 2 is a schematic flow chart of a batch transfer method according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of the structure formed at various steps of the method of FIG. 2;
fig. 4 is a schematic top view of a support layer disposed on a back plate according to an embodiment of the present invention;
FIG. 5 is a schematic structural diagram of another batch transfer method provided in an embodiment of the present invention at various steps;
FIG. 6 is a schematic flow chart diagram illustrating another batch transferring method according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of the structure formed at various steps of the method of FIG. 6;
fig. 8 is a schematic structural diagram formed in each step by another batch transfer method according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
As mentioned in the background, existing batch transfer methods risk solder joint shorts. The inventors have found, through their studies, that the reason for this problem is as follows.
In the existing batch transfer method, the electrical connection mode of the light emitting device is mostly realized by performing thermal compression bonding between the electrode of the light emitting device and the welding point on the back plate. Specifically, fig. 1 is a schematic structural diagram formed in each step by a conventional batch transfer method. Referring to fig. 1, the conventional batch transfer method includes the steps of:
s010, a patterned photoresist layer 200 is formed on the backplane 100.
Wherein the patterned photoresist layer 200 includes a plurality of openings 210, the openings 210 are used for accommodating solder columns 400 (i.e., solder bumps), such that the solder columns 400 are separated by the photoresist layer 200 to avoid short circuits between different solder columns 400.
S020, forming solder columns 400 in the openings 210 of the photoresist layer 200.
The process of forming the solder column 400 generally adopts a metal evaporation process, in which a metal material forms the solder column 400 at the bottom of the opening 210 and adheres to the sidewall of the opening 210 and the surface of the photoresist layer 200.
And S030, removing the photoresist layer 200.
Wherein, while the photoresist layer 200 is removed, the metal materials on the sidewalls of the opening 210 and the surface of the photoresist layer 200 are simultaneously removed, so that the solder columns 400 are insulated from each other.
S040, bonding the light emitting device 500 to the back plate 100.
As can be seen from the above steps, a photoresist layer 200 is used to assist in evaporating the solder columns 400 in the batch transfer method. However, in order to ensure soldering performance of the solder column 400, the thickness of the solder column 400 is thick, and accordingly, the thickness of the photoresist layer 200 is thick. For a display panel with high PPI, the light emitting device 500 is further reduced in size, and the horizontal pitch of its electrodes is also narrowed accordingly. This narrows the pitch of the solder columns 400 and reduces the aperture of the opening in the photoresist layer 200. On one hand, the thickness of the photoresist layer 200 is thicker and the opening 210 is smaller, so that the etching difficulty is increased, and the bottom of the photoresist layer 200 is easy to have the risk of side etching; on the other hand, since the sidewall of the opening 210 is thin, when the bottom of the photoresist layer 200 is undercut, the undercut region 220 becomes thin, even risking penetration. Therefore, there is a risk of short-circuiting the solder columns 400 during the evaporation of the solder columns 400.
In view of this, the embodiment of the present invention provides a batch transfer method. Fig. 2 is a schematic flowchart of a batch transfer method according to an embodiment of the present invention, and fig. 3 is a schematic structural diagram formed in each step of the method in fig. 2. Referring to fig. 2 and 3, the batch transfer method includes the steps of:
s110, forming at least two patterned photoresist layers 300 on the back plate 100, wherein the patterns of the at least two patterned photoresist layers 300 are the same.
The backplate 100 may be a silicon-based backplate, a low temperature polysilicon backplate, or the like. The at least two patterned photoresist layers 300 formed on the backplate 100 means that one photoresist layer in the prior art is manufactured at least twice, so that the thickness of the photoresist layer 300 formed in the embodiment of the present invention is smaller than that of the photoresist layer in the prior art. The same pattern of the photoresist layers 300 means that the openings of the photoresist layers 300 are overlapped in vertical projection on the back plate 100, so as to expose the back plate 100, thereby facilitating the solder columns 400 to be formed in the openings, and achieving the electrical connection between the solder columns 400 and the back plate 100. The number of photoresist layers 300 is exemplarily shown in fig. 3 as two layers, a first photoresist layer 310 and a second photoresist layer 320, respectively. The openings 311 in the first photoresist layer 310 and the openings 321 in the second photoresist layer 320 coincide in vertical projection on the back plate 100.
The step of forming at least two photoresist layers 300 includes: first, a patterned first photoresist layer 310 is formed on the backplate 100, the first photoresist layer 310 including an opening 311; in the process of forming the first photoresist layer 310, since the thickness of the first photoresist layer 310 is thinner than that of the photoresist layer in the prior art, the difficulty of patterning is low, so that the risk of occurrence of undercut at the bottom of the first photoresist layer 310 is reduced, and the uniformity of the openings 311 is improved. Then, a patterned second photoresist layer 320 is formed on the first photoresist layer 310, the second photoresist layer 320 including an opening 321; in the process of manufacturing the second photoresist layer 320, a photoresist material is first formed on the first photoresist layer 310, and the photoresist material covers the surface of the first photoresist layer 310 and fills the openings 311 of the first photoresist layer 310; and then, etching the position of the photoresist material corresponding to the opening 311 to form an opening 321, wherein in the process, the photoresist material in the opening 311 protects the opening 311, which is beneficial to avoiding side etching of the opening 311. And so on, at least two photoresist layers 300 are formed.
Therefore, in the embodiment of the invention, the at least two photoresist layers 300 are respectively manufactured, so that the thickness of each photoresist layer 300 is relatively thin, the difficulty of patterning the opening of the photoresist layer 300 is reduced, the risk of lateral erosion at the bottom of the photoresist layer 300 is reduced, and the uniformity of the opening is improved.
S120, forming solder columns 400 in the openings of the photoresist layer 300.
The solder columns 400 may also be referred to as solder joints, and are used for soldering the light emitting device 500, so as to bond the light emitting device 500 to the backplane 100. The solder column 400 may be made of a metal solder with good electrical conductivity, such as elemental metal, e.g., indium, tin, or tin-bismuth alloy. Illustratively, the solder columns 400 may be evaporated into the openings of the photoresist layer 300 using an evaporation process. During the evaporation process, the material of the solder pillar 400 is evaporated not only on the bottom of the opening of the photoresist layer 300, but also on the sidewall of the opening and the upper surface of the photoresist layer 300. In fig. 3, the cross-sectional shape of the solder column 400 is shown as a rectangle for illustrative purposes, but in actual practice, the cross-sectional shape of the solder column 400 may be spherical, hemispherical, or the like.
S130, removing at least part of the photoresist layer 300.
Removing at least a portion of the photoresist layer 300 means that a portion of the photoresist layer 300 may be removed, or the entire photoresist layer 300 may be removed, and the removal of a portion of the photoresist layer 300 is exemplarily shown in fig. 3. In the process of removing the photoresist layer 300, the solder on the surface of the photoresist layer 300 is simultaneously removed, so that the solder columns 400 are insulated from each other. Illustratively, the photoresist layer 300 and the solder on the surface of the photoresist layer 300 may be stripped using a metal lift-off technology (metal lift-off technology).
S140, bonding the light emitting device 500 to the back plate 100.
The light emitting device 500 may be, for example, a micro light emitting diode chip, and the type of the micro light emitting diode chip may be a gallium nitride LED or a gallium arsenide LED. The electrodes of the light emitting device 500 are bonded to the back plate 100 through the solder columns 400, which may be implemented by a hot pressing process. Illustratively, the light emitting device 500 includes two electrodes, a cathode (N) 510 and an anode (P) 520, the cathode 510 being electrically connected to the back plate 100 through one solder post 400, and the anode 520 being electrically connected to the back plate 100 through the other solder post 400.
In summary, in the embodiment of the invention, at least two photoresist layers 300 are respectively fabricated in S110, so that the thickness of each photoresist layer 300 is relatively thin, and the difficulty of patterning the opening of the photoresist layer 300 is reduced, thereby reducing the risk of occurrence of lateral erosion at the bottom of the photoresist layer 300 and improving the uniformity of the opening. Thus, the uniformity of the size of the solder column 400 is improved in S120. Accordingly, the uniformity of electrical connection between each light emitting device 500 and the rear panel 100 is improved in S140, thereby facilitating prevention of a short circuit of solder joints during the processing and use of the display panel.
With continued reference to FIG. 3, in one embodiment of the present invention, a portion of the photoresist layer 300 is preferably removed to leave a portion of the photoresist layer 300 on the backplate 100. Illustratively, the number of the photoresist layers 300 is two, i.e., a first photoresist layer 310 and a second photoresist layer 320, respectively, the second photoresist layer 320 is removed, and the first photoresist layer 310 remains. The part of the photoresist layer 300 that is removed is the photoresist layer 300 located at the side away from the back plate 100, i.e. the photoresist layer 300 located at the upper layer, as will be understood by those skilled in the art. The remaining photoresist layer 300 is the photoresist layer 300 located on the side close to the back plate 100, i.e. the underlying photoresist layer 300, corresponding to the remaining photoresist layer 300 being the support layer for the removed photoresist layer 300. Illustratively, the first photoresist layer 310 is a support layer for the second photoresist layer 320.
Fig. 4 is a schematic top view of a support layer disposed on a back plate according to an embodiment of the present invention. Referring to fig. 3 and 4, the first photoresist layer 310 (supporting layer) includes an opening 311, the opening 311 exposes the backplate 100, a solder column 400 is disposed in the opening 311, and the solder column 400 is soldered to an electrode of the light emitting device 500. In the embodiment of the invention, a portion of the photoresist layer 300 (e.g., the first photoresist layer 310) is reserved as a supporting layer, which is equivalent to manufacturing a supporting layer (i.e., the first photoresist layer 310) before manufacturing the photoresist layer (i.e., the second photoresist layer 320) on the backplate 100, so that the thickness of the second photoresist layer 320 required for metal solder bonding can be reduced, and the risk that the bottom of the photoresist layer 300 is penetrated is reduced. And on the basis of this, the arrangement of the support layer can be used as shielding between the solder columns 400, thereby reducing the risk of short circuit of the PN electrodes in the process of manufacturing and using the display panel, and protecting the solder columns 400, thereby improving the reliability of the display panel.
With continued reference to fig. 3, based on the above embodiment, the corrosion resistance of the remaining photoresist layer 300 is optionally greater than the corrosion resistance of the removed photoresist layer 300. The embodiment of the invention is arranged in such a way, thereby further being beneficial to avoiding the problem of the bottom side corrosion of the photoresist layer 300; and, in the step of removing the photoresist layer 300, the photoresist layer 300 (i.e., the support layer) having the stronger corrosion resistance is not removed.
With continued reference to fig. 3, in addition to the above-described embodiment, optionally, the material of the remaining photoresist layer 300 (e.g., the first photoresist layer 310) includes benzocyclobutene (BCB) or an epoxy-based polymer, such as SU-8, etc. Benzocyclobutene (BCB) or epoxy-based polymer is a corrosion-resistant photoresist material, and thus is advantageous to improve the corrosion resistance of the remaining photoresist layer 300 (e.g., the first photoresist layer 310) so as to prevent the first photoresist layer 310 from being removed when the second photoresist layer 320 is removed at S130. Accordingly, the material of the photoresist layer 300 (e.g., the second photoresist layer 320) that is removed is an NR series photoresist. The NR series photoresist is a photoresist used for common evaporated metal and has the characteristic of easy cleaning. This is provided to facilitate stripping of the photoresist layer 300 (e.g., the second photoresist layer 320) that needs to be removed in S130.
With continued reference to fig. 3, based on the above embodiments, the remaining photoresist layer 300 (e.g., the first photoresist layer 310) is optionally doped with a colored material. By the arrangement, light leakage of the light emitting device 500 from the electrode surface is reduced, and the front light emitting effect of the display panel is improved.
Preferably, the colored material includes a white pigment or a gray pigment, or the like. The white pigment or the gray pigment does not interfere with the color of the light emitting device 500, and the white pigment or the gray pigment can effectively reflect light, which is beneficial to enhancing the light extraction rate of the light emitting device 500.
It should be noted that, as exemplarily shown in fig. 3, the remaining photoresist layer 300 (e.g., the first photoresist layer 310) has a thickness greater than that of the solder pillar 400, so that light leakage from the electrode surface of the light emitting device 500 can be maximally prevented. Meanwhile, since the electrodes 510 and 520 of the light emitting device 500 have a certain thickness, even if the remaining photoresist layer 300 has a large thickness, it does not cause a shadow in the bonding process of the light emitting device 500.
Fig. 5 is a schematic structural diagram formed in each step by another batch transfer method according to an embodiment of the present invention. Referring to fig. 5, it can be seen from S210 to S240 that, in an embodiment of the present invention, the remaining photoresist layer 300 (e.g., the first photoresist layer 310) optionally has a thickness less than or equal to the thickness of the solder pillar 400. Preferably, the remaining photoresist layer 300 (e.g., the first photoresist layer 310) is slightly thinner than the solder pillar 400. By such an arrangement, it is beneficial to avoid the remaining photoresist layer 300 (e.g., the first photoresist layer 310) from blocking the light emitting device 500 during bonding, and further improve the yield of batch transfer.
In conjunction with fig. 3 and 5, based on the above embodiments, the thickness of the removed photoresist layer 300 (e.g., the second photoresist layer 320) is optionally smaller than the thickness of the remained photoresist layer 300 (e.g., the first photoresist layer 320). Meanwhile, the thickness of the removed photoresist layer 300 (e.g., the second photoresist layer 320) is smaller than that of the solder pillar 400, which is beneficial to reducing the etching difficulty of the removed photoresist layer 300 (e.g., the second photoresist layer 320), improving the uniformity of the openings of the photoresist layer 300, and facilitating the stripping of the photoresist layer 300 (e.g., the second photoresist layer 320).
In conjunction with fig. 3 and 5, based on the above embodiments, the number of the photoresist layers 300 is optionally two, including the first photoresist layer 310 and the second photoresist layer 320. The more the number of the photoresist layers 300 is, the thinner the thickness of the photoresist layer 300 can be set, however, the more times the alignment is required, the more difficulty in the alignment is. Therefore, the embodiment of the invention has the advantage that the number of the photoresist layers 300 is only two, that is, only one alignment process is needed, thereby being beneficial to reducing the difficulty of batch transfer. Further, in combination with the foregoing embodiments, the first photoresist layer 310 is made of a material with strong corrosion resistance, so as to avoid the risk of lateral etching of the bottom of the first photoresist layer 310; the first photoresist layer 310 is set to have a thicker thickness to reduce the thickness of the second photoresist layer 320, so that the embodiment of the present invention can reduce the thickness of the second photoresist layer 320 on the basis of reducing the number of the photoresist layers 300, thereby achieving the effects of high precision and strong stability.
Fig. 6 is a schematic flowchart of another batch transfer method according to an embodiment of the present invention, and fig. 7 is a schematic structural diagram formed in each step of the method in fig. 6. Referring to fig. 6 and 7, on the basis of the above embodiments, optionally, the batch transferring method includes the following steps:
s310, a first photoresist material 312 is formed on the back plate 100.
Wherein the first photoresist material 312 covers one side surface of the back plate 100. Illustratively, the first photoresist material 312 may be formed on the backplate 100 using a spin-on process.
S320, the first photoresist material 312 is patterned to form an opening 311.
The process of patterning the first photoresist material 312 may, for example, sequentially perform processes of baking, exposing, and developing to form an opening 311, and the opening 311 exposes the electrode of the backplate 100, thereby forming the patterned first photoresist layer 310.
S330, forming a second photoresist material 322 on the backplane 100.
Wherein the second photoresist material 322 covers the surface of the first photoresist layer 310 and fills the opening 311. Illustratively, the second photoresist material 322 may be formed on the backplate 100 using a spin-on process.
S340, the second photoresist material 322 is patterned to form an opening 321.
The process of patterning the second photoresist material 322 may, for example, sequentially perform photoresist baking, exposure and development to form the same opening 321 at the position of the opening 311, where the size of the opening 321 is the same as that of the opening 311, and expose the electrode of the backplane 100, thereby forming the patterned second photoresist layer 320.
S350, forming solder columns 400 in the openings of the photoresist layer 300.
S360, the second photoresist layer 320 is removed, and the first photoresist layer 310 remains on the back plate 100.
S370, bonding the light emitting device 500 to the back plate 100.
It can be seen that the batch transfer of the light emitting devices 500 is realized through S310 to S370, the risk of the occurrence of the undercut at the bottom of the photoresist layer 300 is reduced, and the uniformity of the openings is improved.
It should be noted that, in the above embodiments, the number of the photoresist layers 300 is exemplarily shown as two, one photoresist layer 300 is removed, and one photoresist layer 300 is remained, which is not a limitation of the present invention. In other embodiments, the number of photoresist layers 300 may also be provided as three layers, four layers, or other numbers. For example, if the number of the photoresist layers 300 is three, one photoresist layer 300 is removed, and two photoresist layers 300 remain; alternatively, both photoresist layers 300 are removed, leaving one photoresist layer 300. The number of the removed photoresist layers 300 and the number of the remained photoresist layers 300 can be arbitrarily selected, and the technical scheme thereof is within the protection scope of the present invention.
It should be noted that, in the above embodiments, the remaining portions of the photoresist layer 300 are exemplarily shown, which is not a limitation of the present invention. Fig. 8 is a schematic structural diagram formed at each step of another batch transfer method according to an embodiment of the present invention. Referring to fig. 8, as can be seen from S410 to S440, in one embodiment of the present invention, the photoresist layer 300 is optionally entirely removed. The arrangement of the embodiment of the invention is beneficial to avoiding the reserved photoresist layer 300 from forming shielding when the light-emitting device 500 is bonded.
Alternatively, the material of each photoresist layer 300 is the same, so that all photoresist layers 300 (including the first photoresist layer 310 and the second photoresist layer 320) may be removed together in S430.
Alternatively, the photoresist layers 300 are made of different materials, for example, the first photoresist layer 310 has a stronger corrosion resistance than the second photoresist layer 320, so that the second photoresist layer 320 may be removed first and then the first photoresist layer 310 may be removed in S430.
It should be noted that fig. 8 illustrates the number of the photoresist layers 300 as two layers, which is not a limitation of the present invention. In other embodiments, the number of photoresist layers 300 may also be provided as three layers, four layers, or other numbers. The number of the photoresist layers 300 can be arbitrarily selected, and the technical solution thereof is within the protection scope of the present invention.
On the basis of the foregoing embodiments, optionally, the material of each photoresist layer 300 is a negative photoresist, which is beneficial to reducing the cost on the basis of ensuring the preparation precision, and improving the wet method resistance and the corrosion resistance of the remaining photoresist layer 300, thereby being beneficial to further improving the stability of the display panel.
With reference to fig. 3, 5, 7 and 8, on the basis of the foregoing embodiments, optionally, the total thickness of the photoresist layer 300 is 10% to 50% higher than the thickness of the solder pillar 400. For example, the total thickness of the photoresist layer 300 is 10%, 20%, 30%, 40%, or 50% higher than the thickness of the solder pillar 400, etc. This arrangement facilitates formation of solder columns 400 in the openings of the photoresist layer 300 and avoids shorting of adjacent solder columns 400.
In summary, in the embodiments of the invention, at least two photoresist layers 300 are respectively formed during the process of forming the photoresist layers 300, so that the thickness of each photoresist layer 300 is relatively thin, and the difficulty of patterning the openings of the photoresist layers 300 is reduced, thereby reducing the risk of occurrence of undercut at the bottom of the photoresist layers 300 and improving the uniformity of the openings. In this way, the step of fabricating the solder post 400 promotes uniformity in the size of the solder post 400. Therefore, the uniformity of electrical connection between each light emitting device 500 and the rear panel 100 is improved in the bonding process of the light emitting devices 500 and the rear panel 100, thereby being beneficial to reducing the risk of short circuit of welding points in the processing and using processes of the display panel.
The embodiment of the invention also provides a display panel which can be a micro light-emitting diode display panel. The display panel includes: the light-emitting device is transferred onto the back plate by adopting a batch transfer method according to any embodiment of the invention, the technical principle and the generated effect are similar, and the description is omitted here.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims (12)

1. A batch transfer method, comprising:
forming at least two patterned photoresist layers on the back plate, wherein the patterns of the at least two patterned photoresist layers are the same;
forming a solder column in the opening of the photoresist layer; wherein the solder columns are used for welding the light-emitting device;
removing at least a portion of the photoresist layer and bonding the light emitting device to the backplane.
2. The batch transfer method of claim 1, wherein said removing at least a portion of said photoresist layer comprises:
removing a portion of the photoresist layer and leaving a portion of the photoresist layer on the backplate.
3. The batch transfer method of claim 2, wherein the photoresist layer remaining has a corrosion resistance greater than the corrosion resistance of the photoresist layer being removed.
4. The batch transfer method of claim 3, wherein said remaining photoresist layer material comprises: polybenzocyclobutene or epoxy resin polymers.
5. The batch transfer method of claim 2, wherein the remaining photoresist layer is doped with a colored material.
6. The batch transfer method of claim 5, wherein the colored material comprises: white pigments or gray pigments.
7. The batch transfer method of claim 2, wherein the remaining photoresist layer has a thickness less than or equal to the thickness of the solder columns.
8. The batch transfer method of claim 2, wherein the thickness of the photoresist layer removed is less than the thickness of the photoresist layer remaining.
9. The batch transfer method of claim 2, wherein the photoresist layer comprises a first photoresist layer and a second photoresist layer;
the forming of the patterned at least two photoresist layers on the backplane comprises:
forming a patterned first photoresist layer on the backplane;
forming a patterned second photoresist layer on the first photoresist layer;
the removing of the portion of the photoresist layer includes:
and stripping the second photoresist layer, wherein the first photoresist layer remains on the back plate.
10. The batch transfer method of claim 1, wherein said removing at least a portion of said photoresist layer comprises:
and removing all the photoresist layer.
11. The batch transfer method of any of claims 1-10, wherein the total thickness of the photoresist layer is 10% to 50% greater than the thickness of the solder columns.
12. A display panel, comprising: a backsheet and a light emitting device positioned on the backsheet, wherein the light emitting device is transferred onto the backsheet using the batch transfer method of any one of claims 1-11.
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