Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
A micro-device, such as a micro-led chip, refers to an array of micro-led chips with a small size integrated on a donor substrate (e.g., a donor wafer) at a high density, and the size of the micro-led chip is generally less than 100 μm. In the manufacturing process of the display, it is generally necessary to transfer the micro-led chips from the donor substrate to the target substrate in batch by using techniques such as electrostatic adsorption, magnetic adsorption, van der waals force, vacuum adsorption, etc.
Referring to fig. 1, fig. 1 is a schematic structural diagram of an embodiment of a transfer device for micro devices according to the present application, where the transfer device 1 includes a transfer substrate 10, a control circuit 12, and a plurality of transfer heads 14. It should be noted that the transfer substrate 10 referred to in this application is on the transfer device 1 providing the suction force, and not the substrate carrying the microcomponents referred to in the other patents.
Specifically, the plurality of transfer heads 14 are disposed on at least one surface 100 of the transfer substrate 10, the transfer heads 14 may be fixed or movably disposed on the transfer substrate 10, the transfer heads 14 include adhesive members 142 and protrusions 140 protruding from at least one surface 100 of the transfer substrate 10, the adhesive members 142 are disposed on end surfaces a of the protrusions 140, and the adhesive members 142 may be fixed, or detachable, or attachable, or detachable to the protrusions 140. The adhesiveness of the adhesive member 142 changes with temperature change. The convex portion 140 may be a cylinder, a truncated cone, or the like. The control circuit 12 may be located inside or outside the transfer substrate 10 for independently controlling the temperature of the adhesive member 142 of each transfer head 14 to selectively control the attachment or release of selected micro-components by the transfer head 14. The spacing between the protrusions 140 can be determined by the spacing between the desired adhered micro-components, with the greater the spacing between the micro-components, the greater the spacing between the protrusions 140.
In one embodiment, the adhesive member 142 includes at least one of epoxy glue, polyurethane glue, and pressure sensitive adhesive, and the viscosity of the adhesive member 142 can change significantly with temperature. The control circuit 12 controls the temperature of the corresponding adhesive member 142 to rise above a predetermined temperature, thereby deactivating the adhesive properties of the adhesive member 142 to release the selected micro-component. The predetermined temperature is selected according to the type of the adhesive member 142, and the predetermined temperature range is 70-100 degrees celsius, such as 70 degrees celsius, 80 degrees celsius, 90 degrees celsius, 100 degrees celsius, and the like. In addition, in order to control the time when the adhesion of the adhesive member 142 fails, the temperature rising rate of the corresponding adhesive member 142 may be further controlled by the control circuit 12, and generally speaking, the temperature rising rate is positively correlated with the preset temperature, i.e., the higher the preset temperature is, the faster the temperature rising rate is.
In another embodiment, referring to fig. 2, fig. 2 is a schematic structural diagram of an embodiment of the control circuit in fig. 1, in which the control circuit 12 includes a temperature control sub-circuit 120 and heating bodies 122 disposed in a space of the convex portion 140 or the transfer head 14 except the convex portion 140, the temperature control sub-circuit 120 is connected to the heating bodies 122, and outputs electrical energy to each heating body 122.
In an application scenario, to realize that the temperature control sub-circuit 120 outputs the electric energy to each heating body 122, please continue to refer to fig. 2, the control circuit 12 includes a plurality of branches connected in parallel at two ends of the temperature control sub-circuit 120, each branch includes a switch 124 and a heating body 122 connected to each other, and each heating body 122 is independently controlled by controlling the on and off of the switch 124 on the corresponding branch. Of course, in other application scenarios, other circuit design manners may also be adopted, for example, each heating body 122 is correspondingly connected with one temperature control sub-circuit 120, and the like, which is not limited in the present application. In addition, in the present application, the temperature control sub-circuit 120 may adopt any circuit design method with a temperature control function in the prior art, which is not described herein too much.
In another application scenario, please refer to fig. 3, and fig. 3 is a schematic structural diagram of an embodiment of the heating body in fig. 2. The heating body 122 includes a heat generating layer 1220, the heat generating layer 1220 may be a resistance wire, etc., and the heat generating layer 1220 is connected to the temperature control sub-circuit 120 for supplying heat to the adhesive member 142 to change the temperature of the adhesive member 142. In other application scenarios, the heating body 122 further includes a protective layer 1222 and a heat conducting layer 1224, the protective layer 1222 may be an insulating material and is wrapped around the heat generating layer 1220, and the heat conducting layer 1224 may be a metal or alloy material and is wrapped around the protective layer 1222. In one embodiment, when the heating body 122 is disposed in the protrusion 140, the heat generating layer 1220 of the heating body 122 may be located in the protrusion 140, the protrusion 140 may serve as the heat conductive layer 1224, and the heat generating layer 1220 and the protrusion 140 are separated by the protective layer 1222. Of course, in other embodiments, the heating body 122 may also be independently disposed at a position outside the transfer head 14, which is not limited in this application.
In another embodiment, during the batch transfer of microcomponents using the transfer device 1 provided herein, a performance test can also be performed on the microcomponents to discover and remove microcomponents that fail the performance test. Referring to fig. 4, fig. 4 is a schematic structural diagram of another embodiment of the control circuit of fig. 1. The control circuit 12a provided herein includes a sensing sub-circuit 120a and a conductor 122a disposed in the adhesive member 142, wherein one end of the conductor 122a is connected to the sensing sub-circuit 120a, the other end of the conductor 122a is exposed to the outer surface of the adhesive member 142, and the sensing sub-circuit 120a is used for providing a voltage/current to the conductor 122 a. In one application scenario, the conductor 122a may be a metal needle or a nano-silver wire, etc.
In another embodiment, referring to fig. 1 again, the transferring apparatus 1 provided by the present application further includes a conductive temporary substrate 16, at least one surface of the conductive temporary substrate 16 is provided with a conductive layer 160, the material of the conductive layer 160 can be metal, such as aluminum foil, copper foil, and the like, when the micro device is a vertical micro led chip, two electrodes of the micro led chip are respectively located at two opposite sides of the micro led chip, the conductive temporary substrate 16 and the conductor 122a are respectively in contact with the two electrodes, and the conductive temporary substrate 16 is used for cooperating with the conductor 122a to provide voltage/current to two ends of the micro device for performance detection. The conductive layer 160 can be a patterned structure or an unpatterned structure, and when the conductive layer 160 is a patterned structure, the patterned portion thereof contacts the electrode of the micro-component. In addition, in the present embodiment, the portion of the conductive temporary substrate 16 other than the conductive layer 160 may be conductive or non-conductive. In this embodiment, the two electrodes of the vertical micro led chip are located on two opposite sides, wherein one of the electrodes is made of metal and is opaque, and when the one of the electrodes contacts the conductive temporary substrate 16, the conductive temporary substrate 16 may be transparent or opaque.
In other embodiments, when the micro-component is other, for example, a lateral micro-led chip (i.e. two electrodes of the lateral micro-led chip are located on the same side), the performance of the micro-component can be tested during the batch transfer of the micro-component by using the transfer device 1 provided in the present application. Referring to fig. 5, fig. 5 is a schematic structural diagram of another embodiment of the control circuit of fig. 1. The control circuit 12b includes a first detection sub-circuit 120b, a second detection sub-circuit 124b, and a conductor 122b, wherein one end of the conductor 122b is connected to the first detection sub-circuit 120b or the second detection sub-circuit 124b, and the other end of the conductor 122b is exposed on the outer surface of the adhesive member 142. In the present embodiment, the two electrodes of the micro-component are adhered to the adjacent set of adhesive members 142, the adjacent set of conductors 122b is in contact with the two electrodes of the micro-component, the adjacent set of conductors 122b is connected to the first detection sub-circuit 120b and the second detection sub-circuit 124b, and the first detection sub-circuit 120b and the second detection sub-circuit 124b are used to cooperate with the conductors 122b to provide a test voltage/test current to the two electrodes of the micro-component, so as to energize the micro-component for performance testing. In this embodiment, the conductive temporary substrate 16 may also be introduced as a carrier substrate for the micro-components, and the conductive performance of the conductive temporary substrate 16 is not utilized in the micro-component detection process. In this embodiment, since both sides of the lateral micro-led chip can transmit light, the temporary conductive substrate 16 on one side of the lateral micro-led chip needs to be transparent so as to observe the light emitting effect of the lateral micro-led chip.
Referring to fig. 6 to 7, fig. 6 is a schematic flow chart diagram illustrating an embodiment of a transfer method for micro devices according to the present application, and fig. 7 is a schematic structural diagram illustrating an embodiment corresponding to steps S101 to S102 in fig. 6, where the transfer method includes:
s101: a donor substrate 2 is provided, on which donor substrate 2a plurality of microcomponents 3 is disposed.
Specifically, referring to fig. 7a, in the present embodiment, the donor substrate 2 may be a donor wafer, the micro-devices 3 may be vertical micro-led chips or lateral micro-led chips, and the micro-devices 3 may be micro-led chips of the same color (e.g., red, green, or blue) or different colors.
S102: transferring a plurality of microcomponents 3 from a donor substrate 2 by means of a transfer device 1, wherein the transfer device 1 comprises a transfer substrate 10, a plurality of transfer heads 14 and a control circuit 12; wherein, several transfer heads 14 are located on at least one surface 100 of the transfer substrate 10, the transfer heads 14 include adhesive members 142 and convex parts 140 protruding from at least one surface of the transfer substrate 10, the adhesive members 142 are located on the end surfaces of the convex parts 140, and the adhesiveness of the adhesive members 142 changes with the temperature change; the control circuit 12 controls the temperature of the adhesive members 142 of the plurality of transfer heads 14, the plurality of transfer heads 14 independently adhering or releasing selected micro-components 3.
Specifically, referring to fig. 7b, in the present embodiment, the specific structure of the transferring device 1 can be referred to the above embodiments, and is not described herein again.
In an application scenario, before the step S102, the transfer method provided by the present application further includes: providing a whole piece of adhesive glue, wherein the material of the adhesive glue is the same as that of the adhesive piece 142; the transfer substrate 10 is disposed with the transfer heads 14 side close to and in contact with the adhesive paste, so that a part of the adhesive paste, i.e., the adhesive member 142, adheres to the end surface of the convex portion 140 of each transfer head 14. Of course, in other embodiments, the adhesive member 142 may be formed on the end surface of each protrusion 140 by dispensing.
In another application scenario, when the micro-device is a vertical micro-led chip, two electrodes of the micro-led chip are respectively located on two opposite sides of the epitaxial layer of the micro-led chip. The step S102 specifically includes: the transferring device is provided with a plurality of adhesive members 142 at one side thereof adjacent to and contacting one electrode of the plurality of micro light emitting diode chips so that one adhesive member adheres to one electrode of one micro light emitting diode chip correspondingly.
In another application scenario, when the micro-component is a lateral micro-led chip (e.g., a front-side or flip-chip micro-led chip), the two electrodes of the micro-led chip are located on the same side of the epitaxial layer of the micro-led chip. The step S102 specifically includes: the transfer device is provided with a plurality of adhesive members 142 on one side adjacent to and in contact with the two electrodes of the plurality of micro-led chips such that an adjacent set of first and second adhesive members respectively adheres to the two electrodes of the micro-led chips. Of course, in other application scenarios, one adhesive member may be used to adhere the two electrodes of the micro light emitting diode chip at the same time, or one adhesive member may be used to adhere the area between the two electrodes of the micro light emitting diode chip.
In addition, in one embodiment, the methods provided herein can also be used to perform performance testing of multiple micro-components during their transfer from a donor substrate using a transfer device. Specifically, referring to fig. 8, fig. 8 is a schematic flowchart illustrating an embodiment of step S102 in fig. 6. The step S102 specifically includes:
s201: and performing performance detection on the plurality of micro-components to obtain a plurality of micro-components with passed performance detection and failed performance detection.
S202: the temperature control subcircuit in the control circuit corresponding to the micro-component failing in performance detection controls the adhesive member to fail, so as to release the plurality of micro-components failing in performance detection.
S203: and transferring the plurality of micro-components passing the performance detection to the preset positions of the target substrate.
In an embodiment, the above steps S201 to S202 are further described in detail by taking the micro device as a vertical micro led as an example.
Specifically, referring to fig. 9 and 10, fig. 9 is a schematic flow chart of an embodiment of steps S201 to S203 in fig. 8, and fig. 10 is a schematic structural diagram of an embodiment of steps S301 to S306 in fig. 9. The steps S201 to S203 specifically include:
s301: a conductive temporary substrate 4 is disposed on the other side of the plurality of micro light emitting diode chips 3a, one electrode 30a of the micro light emitting diode chip 3a is in contact with a conductor (not illustrated) disposed in the adhesive member 142, and the other electrode 32a of the micro light emitting diode chip 3a is in contact with the conductive temporary substrate 4. Specifically, please refer to fig. 10 a. In this embodiment, a conductive layer is disposed on a side of the conductive temporary substrate 4 contacting the micro light emitting diode chip 3a, and other portions of the conductive temporary substrate 4 may be conductive or non-conductive. In addition, in the present embodiment, since the micro light emitting diode chip 3a is a vertical micro light emitting diode chip, the conductive temporary substrate 4 may be transparent or opaque.
S302: the conductors in the adhesive member 142 and the conductive temporary substrate 4 apply voltage/current to both electrodes 30a, 32a of the micro light emitting diode chip 3a simultaneously. Specifically, referring to fig. 10a again, in the present embodiment, the voltage/current of the conductor and the conductive temporary substrate 4 can be provided by both the detection sub-circuit, but of course, in other embodiments, can be provided by two different circuits. In addition, in the present embodiment, the performance detection method is an electroluminescence method, and in other embodiments, the performance of the micro light emitting diode chip 3a may be detected in other manners, for example, by an electromagnetic induction method
S303: if the performance of the micro light-emitting diode chip 3a meets the preset condition, judging that the performance of the micro light-emitting diode chip 3a passes; otherwise, the performance of the micro light emitting diode chip 3a is determined to be not passed. Specifically, in the present embodiment, the above-mentioned properties include any one or more properties of electricity, optics, color, etc., and all or part of the above-mentioned properties can be selectively detected according to the actual detection requirement. Each performance is provided with a preset condition, and the performance of the micro light emitting diode chip 3a is judged to pass only if the performance meets all the preset conditions.
S304: the temperature control sub-circuit corresponding to the micro light emitting diode chip 3a failing in performance detection controls the adhesion of the corresponding adhesive member 142 to fail, so as to release the plurality of micro light emitting diode chips 3a failing in performance detection; in particular, see fig. 10 b.
S305: the plurality of micro light emitting diodes 3a, through which the performance test is passed, are transferred to predetermined positions of the target substrate 5 and released (not shown). In particular, see fig. 10 c. After the transferring device 1 transfers the micro light emitting diodes 3a with passed detection performance to the predetermined position of the target substrate 5, the temperature control sub-circuit corresponding to the micro light emitting diode chips 3a with passed performance controls the adhesion of the corresponding adhesive member 142 to fail, so as to release the micro light emitting diode chips 3 a.
S306: bonding or bonding the micro light emitting diode chip 3a with a predetermined position, and removing the residual adhesive member on the micro light emitting diode chip 3a by using a solvent. Specifically, referring to fig. 10d, in this embodiment, the bonding and bonding process may refer to any one of the embodiments in the prior art, and is not described herein again. In addition, the solvent may be an organic solvent capable of dissolving the adhesive member, for example, alcohol, acetone, or the like.
In addition, in this embodiment, after the step S306, the transferring method further includes filling the predetermined position on the target substrate 5 where the micro led chip 3a is not located.
In another embodiment, in an embodiment, the micro-device is a lateral micro-led, and the steps S201 to S203 are further described in detail. Note that, before the following transfer method is performed, a set of the first adhesive member 142a and the second adhesive member 142b adjacent to the transfer device 1 adheres the two electrodes 30b, 32b of the micro light emitting diode chip 3b, respectively. Referring to fig. 11 and 12, fig. 11 is a flowchart illustrating an embodiment of steps S201 to S203 in fig. 8, and fig. 12 is a structural diagram illustrating an embodiment of steps S401 to S407 in fig. 11.
S401: the conductors in the first adhesive member 142a and the conductors in the second adhesive member 142b simultaneously apply voltage/current to the two electrodes 30b, 32b of the micro light emitting diode chip 3b, respectively. Specifically, as shown in fig. 12 a.
S402: if the performance of the micro light-emitting diode chip 3b meets the preset condition, judging that the performance of the micro light-emitting diode chip 3b passes; otherwise, it is determined that the performance of the micro light emitting diode chip 3b does not pass. Specifically, in the present embodiment, the above-mentioned properties include any one or more properties of electricity, optics, color, etc., and all or part of the above-mentioned properties can be selectively detected according to the actual detection requirement. Each performance is provided with a preset condition, and the performance of the micro light emitting diode chip 3b is judged to pass through only if the performance meets all the preset conditions. The performance detection method is an electroluminescence method, and in other embodiments, the performance of the micro light emitting diode chip 3b may be detected in other manners, for example, by an electromagnetic induction method.
S403: the temperature control sub-circuit corresponding to the micro light-emitting diode chip 3b which fails in performance detection controls the adhesion of the corresponding first adhesive member 142a and second adhesive member 142b to fail, so as to release the plurality of micro light-emitting diode chips 3b which fail in performance detection; specifically, please refer to fig. 12 b.
S404: the transfer device 1 transfers the micro light-emitting diodes 3b passing the performance detection to the upper part of the conductive temporary substrate 4, and the temperature control sub-circuit corresponding to the micro light-emitting diode chips 3b passing the performance detection controls the adhesion failure of the corresponding first adhesive member 142a and second adhesive member 142b, so as to release the micro light-emitting diode chips 3b to the conductive temporary substrate 4; specifically, please refer to fig. 12 c. In this embodiment, the conductive temporary substrate 4 may be replaced with a non-conductive temporary substrate.
S405: arranging an electrostatic or magnetic adsorption device 6 on the side of the conductive temporary substrate 4 far away from the micro light-emitting diode chip 3b so as to adsorb the micro light-emitting diode chip 3b passing the performance detection on the conductive temporary substrate 4; specifically, referring to fig. 12d, in the present embodiment, the electrostatic or magnetic attraction device 6 may be any one of the prior art, which is not described herein again.
S406: the side of the conductive temporary substrate 4 on which the micro-led chip is adsorbed is directed to the target substrate 5, and both electrodes of the micro-led chip are brought into contact with predetermined positions of the target substrate 5 and released. See, in particular, fig. 12 e. After the transfer device 1 transfers the micro light emitting diodes 3b with passed detection performance to the predetermined position of the target substrate 5, the temperature control sub-circuit corresponding to the micro light emitting diode chips 3b with passed performance control the corresponding adhesive members 142a, 142b to lose adhesion, so as to release the micro light emitting diode chips 3 b.
S407: bonding or bonding the micro light emitting diode chip 3b with a predetermined position, and removing the residual adhesive member on the micro light emitting diode chip 3b by using a solvent. In particular, see fig. 12 f. In this embodiment, the bonding and bonding processes may be referred to in any embodiment of the prior art, and are not described herein again. In addition, the solvent may be an organic solvent capable of dissolving the adhesive member, for example, alcohol, acetone, or the like.
In summary, unlike the prior art, the micro-component transferring apparatus provided in the present application employs a control circuit capable of independently controlling the temperature of the adhesive member on each transferring head, so as to selectively control the transferring head to adsorb or release selected micro-components, thereby implementing individual operation on each micro-component during batch transferring; meanwhile, the adhesive property of the adhesive part on the transfer head is controlled by temperature, so that the structure of the transfer head can be simplified, and the efficiency of grabbing the micro-element can be improved.
In addition, in the batch transfer process, all the micro-components can be subjected to performance tests, and for the micro-components which do not pass the performance tests, the corresponding control circuits control the temperature of the adhesive member of the transfer head so as to ensure that the adhesiveness of the adhesive member fails, thereby achieving the purpose of removing bad micro-components in the batch transfer process.
The above description is only for the purpose of illustrating embodiments of the present application and is not intended to limit the scope of the present application, and all modifications of equivalent structures and equivalent processes, which are made by the contents of the specification and the drawings of the present application or are directly or indirectly applied to other related technical fields, are also included in the scope of the present application.