A method for bonding LED chips and LED device

Abstract

The present application provides a method for bonding LED chips and an LED device, the method for bonding LED chips comprising: making a printed circuit layer on a flexible substrate, and coating solder paste on the pads of the printed circuit layer; arranging and fixing a plurality of LED chips on an optical film in advance according to the distribution of the pads on the printed circuit layer; controlling the optical film and the flexible substrate to maintain the same expansion and contraction, and embossing the optical film and the flexible substrate and heating and curing. The method for bonding LED chips of the present application has a fast bonding speed, high efficiency and a simple process flow.

Description

Technical Field

[0001] The present application relates to the field of display technology, and in particular to a method for bonding a LED chip and an LED device. Background Art

[0002] With the development of flexible technology, flexible circuits have attracted people's attention. Compared with traditional wiring and rigid PCBs, flexible circuits have the characteristics of low price, high wiring density, light weight, thin thickness and good bending properties. In addition, flexible circuits can not only perform three-dimensional wiring, but also adjust their shape appropriately to adapt to the available space.

[0003] At present, the method of bonding Mini LED chips is to fix the chips one by one on the light board in sequence, which leads to problems such as slow bonding speed, low efficiency and low alignment accuracy. These problems will seriously affect the use of Mini LED in the future. Summary of the invention

[0004] The embodiments of the present application provide a LED chip bonding method and an LED device to solve the problems of slow bonding speed, low efficiency and complicated process flow of existing LED chips.

[0005] The LED chip bonding method provided in the embodiment of the present application includes:

[0006] Manufacturing a printed circuit layer on a flexible substrate, and coating solder paste on pads of the printed circuit layer;

[0007] Arrange and fix a plurality of LED chips on the optical film in advance according to the distribution of the pads on the printed circuit layer;

[0008] The optical film and the flexible substrate are controlled to maintain the same expansion and contraction, and the optical film and the flexible substrate are pressed and heated for curing.

[0009] Optionally, the step of arranging and fixing a plurality of LED chips on the optical film in advance according to the distribution of the pads on the printed circuit layer includes:

[0010] Applying pressure adhesive on the optical film;

[0011] The light emitting surface of the LED chip is pasted on the pressure adhesive, and the pins of the LED chip are oriented away from the optical film.

[0012] Optionally, the step of controlling the optical film and the flexible substrate to maintain the same expansion and contraction, and printing and heating the optical film and the flexible substrate to cure the optical film includes:

[0013] Controlling the optical film and the flexible substrate to maintain the same expansion and contraction, so that the pins of the LED chip are in contact with the solder paste on the corresponding pads;

[0014] The flexible substrate is heated so that the pins of the LED chip are fixed to the soldering pads.

[0015] Optionally, the pressure adhesive is made of a material that does not contain acid, carboxyl, or water-soluble components.

[0016] Optionally, the step of manufacturing a printed circuit layer on the flexible substrate and coating solder paste on the pads of the printed circuit layer includes:

[0017] A printed circuit layer is manufactured on the flexible substrate by screen printing, and solder paste is coated on the pads of the printed circuit layer.

[0018] The embodiment of the present application provides an LED device, which is manufactured by using the above-mentioned LED chip bonding method, and the LED device includes:

[0019] Flexible substrates;

[0020] A printed circuit layer, wherein the printed circuit layer is disposed on the flexible substrate;

[0021] a light-emitting layer, wherein the light-emitting layer is disposed on the printed circuit layer,

[0022] A pressure adhesive layer, the pressure adhesive layer being disposed on the flexible substrate, the printed circuit layer and the light-emitting layer;

[0023] An optical film is arranged on the pressure adhesive layer.

[0024] Optionally, the printed circuit layer and the light-emitting layer are located in the pressure adhesive layer, and the pressure adhesive layer has a thickness of 85 μm to 115 μm.

[0025] Optionally, the light-emitting layer is composed of a plurality of LED chips arranged in an array, and the LED chip is a Micro LED chip or a Mini LED chip.

[0026] Optionally, the printed circuit layer has a thickness of 5 μm to 15 μm.

[0027] Optionally, the flexible substrate is made of polyimide or polyester film as a base material, and the thickness of the flexible substrate is 100 μm to 300 μm.

[0028] In the technical solution proposed in this application, a printed circuit layer is made on a flexible substrate, and solder paste is applied on the pads of the printed circuit layer; multiple LED chips are arranged and fixed on the optical film in advance according to the distribution of the pads on the printed circuit layer; the optical film and the flexible substrate are controlled to maintain the same expansion and contraction, and the optical film and the flexible substrate are pressed and heated to cure. By arranging and fixing multiple LED chips on the optical film in advance, the arrangement and fixation of the LED chips are set according to the distribution of the pads, so that when the optical film and the flexible substrate are pressed and heated to cure, the electrodes of the LED chips will correspond one by one to the pads in the printed circuit layer; compared with the existing single LED chip solidification method, the solution of this application can double the solidification efficiency of LED chips, especially suitable for the layout requirements of small spacing and large quantities between Micro LED chips or MiniLED chips, avoiding the viscosity and conductivity of the solder paste printed on the substrate pads from deteriorating due to long solidification time, thereby improving the quality and reliability of LED device products. At the same time, since the LED chip is pre-fixed on the optical film, compared with the existing LED crystal bonding method, the present application directly combines the crystal bonding and the subsequent optical film production, and there is no need to remove the backing plate carrying the LED chip after crystal bonding, which simplifies the production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0030] In order to more completely understand the present application and its beneficial effects, the following description will be given in conjunction with the accompanying drawings, wherein the same figure numbers represent the same parts in the following description.

[0031] Figure 1 It is a schematic flow chart of a die bonding method for an LED chip provided in an embodiment of the present application;

[0032] Figure 2 This is a schematic diagram of the structure of the LED device before die bonding provided in an embodiment of the present application;

[0033] Figure 3 It is an overall structural diagram of the LED device provided in the embodiment of the present application.

[0034] Description of Figure Numbers:

[0035] Label name Label name 10 LED Devices 13 Luminescent layer 11 Flexible Substrates 131 LED Chips 12 Printed circuit layer 14 Pressure adhesive layer 121 Pads 15 Optical Film

[0036] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of this application.

[0038] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are used only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0039] In this application, the word "exemplary" is used to mean "used as an example, illustration, or description." Any embodiment described in this application as "exemplary" is not necessarily to be construed as being preferred or advantageous over other embodiments. The following description is given to enable any technician in the field to implement and use the present application. In the following description, details are listed for the purpose of explanation. It should be understood that a person of ordinary skill in the art can recognize that the present application can be implemented without using these specific details. In other instances, well-known structures and processes will not be elaborated in detail to avoid obscuring the description of the present application with unnecessary details. Therefore, the present application is not intended to be limited to the embodiments shown, but is consistent with the widest scope consistent with the principles and features disclosed in the present application.

[0040] The embodiment of the present application provides a method for bonding LED chips, which is described in detail below.

[0041] See also Figure 1 and Figure 2 , Figure 1 A schematic diagram of a process for a LED chip die bonding method provided in an embodiment of the present application. Figure 2 : is a schematic diagram of the structure of the LED device before die bonding provided in an embodiment of the present application. In an embodiment of the present application, the die bonding method of the LED chip includes:

[0042] S10 , manufacturing a printed circuit layer 12 on the flexible substrate 11 , and coating solder paste on the pads 121 of the printed circuit layer 12 .

[0043] Specifically, in the embodiment of the present application, the printed circuit layer 12 is made on the flexible substrate 11 by screen printing, and then a solder paste is applied on the pad 121 of the printed circuit layer 12. The solder paste is generally solder paste or silver paste. In other embodiments, if an LED chip 131 with its own solder is used, it is not necessary to print a conductive material such as silver paste or solder paste on the pad 121 of the printed circuit layer 12.

[0044] S20 , according to the distribution of the pads 121 on the printed circuit layer 12 , a plurality of LED chips 131 are arranged and fixed on the optical film 15 in advance.

[0045] It is understandable that, since the positions of the pads 121 on the printed circuit layer 12 are fixed, the existing die bonding method is to use a die bonding machine to fix the LED chips 131 one by one to the corresponding pads 121. In the present application, first, according to the distribution of the pads 121 on the printed circuit layer 12, the LED chips 131 are pre-fixed on the optical film 15 one by one, so that the pins of the LED chips 131 correspond to the pads 121 in the printed circuit layer 12 one by one, so that the batch die bonding of the LED chips 131 can be completed, and the die bonding efficiency is improved; and the LED chips 131 are pre-fixed according to the distribution of the pads 121, which also ensures the accuracy of the die bonding of the LED chips 131.

[0046] Furthermore, in the embodiment of the present application, the optical film 15 is a film with optical function that needs to be covered on the light-emitting layer 13 in the subsequent production of the LED device 10. The optical function of the optical film 15 is not limited here and can be formulated according to the requirements of different LED devices 10. Since the LED chip 131 is pre-fixed on the optical film 15, compared with the existing LED die bonding method, the present application directly combines the die bonding and the subsequent production of the optical film 15, and there is no need to remove the liner supporting the LED chip 131 after the die bonding, which simplifies the production process.

[0047] Specifically, in the embodiment of the present application, the step S20 further includes: applying pressure glue on the optical film 15; pasting the light-emitting surface of the LED chip 131 on the pressure glue, and the pins of the LED chip 131 face away from the optical film 15. The purpose of applying the pressure glue on the optical film 15 is to facilitate the pasting of the LED chip 131. At the same time, when the optical film 15 is connected to the flexible substrate 11, the pressure glue will cover the flexible substrate 11, the printed circuit layer 12 and the LED chip 131, and play a role in encapsulating the LED chip 131 and the flexible substrate 11, eliminating the step of making the encapsulation glue layer, further improving the production efficiency of the product, and simplifying the product production process.

[0048] As a preferred embodiment, the pressure adhesive is made of a material that does not contain acid, carboxyl, or water-soluble components.

[0049] S30 , controlling the optical film 15 and the flexible substrate 11 to maintain the same expansion and contraction, and pressing and heating the optical film 15 and the flexible substrate 11 to cure.

[0050] It is understandable that the LED chip 131 and the pad 121 may not correspond to each other due to the expansion and contraction of the flexible substrate 11 during heating, thereby affecting the precision of die bonding. In the present application, during the process of imprinting the optical film 15 and the flexible substrate 11 and heating and curing, the optical film 15 and the flexible substrate 11 are controlled to maintain the same expansion and contraction, so that the LED chip 131 and the pad 121 are always in corresponding positions, thereby ensuring the precision of die bonding of the LED chip 131.

[0051] Specifically, in the embodiment of the present application, the optical film 15 preferably has a material, thickness, haze, transmittance and expansion / contraction structure that matches the flexible substrate 11, so as to play a corresponding optical role and ensure that during the process of imprinting and heating and curing the optical film 15 and the flexible substrate 11, the optical film 15 and the flexible substrate 11 maintain the same expansion / contraction, thereby ensuring the accuracy of the LED chip 131 die bonding.

[0052] In the technical solution proposed in the present application, a printed circuit layer 12 is manufactured on a flexible substrate 11, and solder paste is coated on the pads 121 of the printed circuit layer 12; a plurality of LED chips 131 are pre-arranged and fixed on an optical film 15 according to the distribution of the pads 121 on the printed circuit layer 12; the optical film 15 and the flexible substrate 11 are controlled to maintain the same expansion and contraction, and the optical film 15 and the flexible substrate 11 are embossed and heated for curing. By pre-arranging and fixing a plurality of LED chips 131 on the optical film 15, the arrangement and fixing of the LED chips 131 is set according to the distribution of the pads 121, so that when the optical film 15 and the flexible substrate 11 are pressed and heated and cured, the electrodes of the LED chips 131 will correspond one by one to the pads 121 in the printed circuit layer 12; compared with the existing single LED chip 131 solidification method, the solution of the present application can double the solidification efficiency of the LED chip 131, especially suitable for the layout requirements of small spacing and large quantities between Micro LED chips or Mini LED chips, avoiding the viscosity and conductivity of the solder paste printed on the substrate pad 121 from deteriorating due to the long solidification time, thereby improving the quality and reliability of the LED device 10 product. At the same time, since the LED chip 131 is pre-fixed on the optical film 15, compared with the existing LED solidification method, the present application directly combines solidification with the subsequent production of the optical film 15, and does not need to remove the liner carrying the LED chip 131 after solidification, which simplifies the production process.

[0053] The present application also provides an LED device 10. Figure 2 and Figure 3 , Figure 2 is a schematic diagram of the structure of the LED device before die bonding provided in an embodiment of the present application, Figure 3 1 is an overall structural diagram of an LED device provided in an embodiment of the present application. In the implementation of the present application, the LED device 10 is manufactured by the LED chip bonding method described in the above embodiment; the LED device 10 includes:

[0054] Flexible substrate 11;

[0055] A printed circuit layer 12, wherein the printed circuit layer 12 is disposed on the flexible substrate 11;

[0056] A light emitting layer 13, wherein the light emitting layer 13 is disposed on the printed circuit layer 12,

[0057] A pressure adhesive layer 14, wherein the pressure adhesive layer 14 is disposed on the flexible substrate 11, the printed circuit layer 12 and the light-emitting layer 13;

[0058] The optical film 15 is disposed on the pressure adhesive layer 14 .

[0059] Specifically, the flexible substrate 11 is made of polyimide or polyester film as a base material, and the thickness of the flexible substrate 11 is 100 μm to 300 μm. The flexible substrate 11 plays a supporting role.

[0060] Furthermore, the printed circuit layer 12 is made by screen printing, and the main material of the printed circuit layer 12 is nano silver paste, and its thickness is 5μm to 15μm. The printed circuit layer 12 has a plurality of pads 121, and the pads 121 are coated with solder paste, and the solder paste is generally solder paste or silver glue, which is used to fix the LED chip 131 and play the role of electrical connection. In other embodiments, if an LED chip 131 with its own solder is used, it is not necessary to print conductive materials such as silver glue or solder paste on the pads 121 of the printed circuit layer 12.

[0061] Furthermore, the light-emitting layer 13 is composed of a plurality of LED chips 131 arranged in an array, and the LED chip 131 is a Micro LED chip or a Mini LED chip. In the embodiment of the present application, the size of the LED chip 131 is 300 μm×630 μm, and the thickness is 80 μm to 100 μm, and the LED chip 131 acts as a backlight source.

[0062] Further, the pressure adhesive layer 14 is a layer of pressure adhesive covering the flexible substrate 11, the printed circuit layer 12 and the light-emitting layer 13. The pressure adhesive is made of a material that does not contain acid, carboxyl, and water-soluble components, and the thickness of the pressure adhesive layer 14 is 85 μm to 115 μm. It can be understood that the printed circuit layer 12 and the light-emitting layer 13 are located in the pressure adhesive layer 14, and the pressure adhesive layer 14 plays a role in encapsulating the LED chip 131 and the flexible substrate 11.

[0063] Furthermore, the optical film 15 is a film with optical effects that covers the light-emitting layer 13. The optical effects of the optical film 15 are not limited here and can be formulated according to the requirements of different LED devices. The optical film 15 preferably has a structure that matches the flexible substrate 11 in terms of material, thickness, haze, transmittance, and expansion and contraction. While being able to play a corresponding optical role, it is ensured that during the process of imprinting and heating and curing the optical film 15 and the flexible substrate 11, the optical film 15 and the flexible substrate 11 maintain the same expansion and contraction, thereby ensuring the accuracy of the LED chip die bonding.

[0064] The above is a detailed introduction to a LED chip bonding method and an LED device provided in an embodiment of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for technical personnel in this field, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A method for bonding LED chips, characterized in that: include: Manufacturing a printed circuit layer on a flexible substrate, and coating solder paste on pads of the printed circuit layer; Applying pressure adhesive on optical film; Pasting the light-emitting surface of the LED chip onto the pressure adhesive, with the pins of the LED chip facing away from the optical film; Controlling the optical film and the flexible substrate to maintain the same expansion and contraction, so that the pins of the LED chip are in contact with the solder paste on the corresponding pads; The flexible substrate is heated so that the pins of the LED chip are fixed to the soldering pads.

2. The LED chip bonding method according to claim 1, characterized in that: The pressure adhesive is made of a material that does not contain acid, carboxyl, or water-soluble components.

3. The LED chip bonding method according to claim 1, characterized in that: The steps of manufacturing a printed circuit layer on a flexible substrate and coating solder paste on pads of the printed circuit layer include: A printed circuit layer is manufactured on the flexible substrate by screen printing, and solder paste is coated on the pads of the printed circuit layer.

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