CN115719755A

CN115719755A - Circuit board assembly, manufacturing method thereof and chip transfer method

Info

Publication number: CN115719755A
Application number: CN202110972863.5A
Authority: CN
Inventors: 翟峰; 萧俊龙; 蔡明达
Original assignee: Chongqing Kangjia Photoelectric Technology Research Institute Co Ltd
Current assignee: Chongqing Kangjia Photoelectric Technology Research Institute Co Ltd
Priority date: 2021-08-24
Filing date: 2021-08-24
Publication date: 2023-02-28

Abstract

The invention relates to a circuit board assembly and a manufacturing method thereof, and a chip transfer method.A circuit board is provided with an insulating adhesive layer covering each chip bonding area, each chip bonding area is respectively provided with a first metal bonding pad and a second metal bonding pad, the insulating adhesive layer is positioned in the area above each chip bonding area, and a first through hole and a second through hole which are communicated with the first metal bonding pad and the second metal bonding pad are respectively formed; when the chip is transferred to the circuit board, the target light-emitting chip to be transferred on the growth substrate can be directly transferred to the insulating adhesive layer of the corresponding chip bonding area, and the first electrode and the second electrode of the target light-emitting chip respectively fall into the corresponding first through hole and the corresponding second through hole to be connected with the corresponding first metal bonding pad and the corresponding second metal bonding pad. When the circuit board assembly provided by the invention is used for transferring the light-emitting chips, the corresponding light-emitting chips on the growth substrate are captured and limited by directly utilizing the insulating layer structure, the transfer efficiency is higher, and the transfer cost is lower.

Description

Circuit board assembly, manufacturing method thereof and chip transfer method

Technical Field

The invention relates to the field of light-emitting chips, in particular to a circuit board assembly and a manufacturing method and a chip transfer method thereof.

Background

Micro LEDs are a new generation of display technology. Compared with the existing liquid crystal display, the flexible display panel has higher photoelectric efficiency, higher brightness, higher contrast ratio and lower power consumption, and can be combined with a flexible panel to realize flexible display.

The Micro LED display panel comprises a plurality of pixel regions SPR (sub-pixel Rendering), and each pixel region SPR comprises a red light Micro LED chip, a blue light Micro LED chip and a green light Micro LED chip. In the manufacturing process of the display panel, the red light Micro LED chip, the blue light Micro LED chip and the green light Micro LED chip need to be transferred to the display backplane from respective growth substrates (refer). The chip transfer technology adopted at present needs to transfer Micro LED chips from a growth substrate to a temporary substrate, then from the temporary substrate to a transfer substrate, and finally from the transfer substrate to a display backplane.

In the chip transfer process, two types of glue materials are required to be selected to respectively manufacture the first bonding layer and the second bonding layer on the temporary substrate and the transfer substrate, the viscosity of the first bonding layer is required to be lower than that of the second bonding layer, appropriate materials are difficult to find, the Micro LED chip is required to be sequentially transferred to the temporary substrate and the transfer substrate from the growth substrate in the transfer process, the transfer efficiency is low, the temporary substrate and the transfer substrate are required to be prepared, and the transfer cost is also high.

Therefore, how to improve the transfer efficiency of the LED chip and reduce the transfer cost is a problem that needs to be solved.

Disclosure of Invention

In view of the above disadvantages of the prior art, an object of the present invention is to provide a circuit board assembly, a manufacturing method thereof, and a chip transferring method, so as to solve the problems of improving the transferring efficiency of LED chips and reducing the transferring cost in the related art.

The present invention provides a circuit board assembly for array bonding a plurality of light emitting chips as a display, comprising:

the circuit board is provided with a plurality of chip bonding areas, and a first metal bonding pad and a second metal bonding pad which respectively correspond to a first electrode and a second electrode of the light-emitting chip are arranged in the chip bonding areas; wherein, the first and the second end of the pipe are connected with each other,

the circuit board assembly further includes:

and the insulating adhesive layer is arranged on the circuit board and covers the chip bonding areas, is positioned in the area above the chip bonding areas, and is respectively provided with a first through hole and a second through hole which are communicated with the first metal bonding pad and the second metal bonding pad.

In the circuit board assembly, the circuit board is provided with an insulating adhesive layer covering each chip bonding area, each chip bonding area is internally provided with a first metal bonding pad and a second metal bonding pad, the insulating adhesive layer is positioned in the area above each chip bonding area and is respectively provided with a first through hole and a second through hole which are communicated with the first metal bonding pad and the second metal bonding pad; when the chip is transferred to the circuit board, a target light-emitting chip to be transferred on the growth substrate can be directly transferred to the insulating adhesive layer of the corresponding chip bonding area, the first electrode and the second electrode of the target light-emitting chip respectively fall into the corresponding first through hole and the corresponding second through hole to be connected with the corresponding first metal bonding pad and the corresponding second metal bonding pad, and the first through hole and the second through hole limit the target light-emitting chip at the same time, so that the form and the position of the target light-emitting chip are prevented from changing; therefore, when the circuit board assembly provided by the invention is transferred with the light-emitting chips, the corresponding light-emitting chips on the growth substrate can be captured and limited by directly utilizing the insulating layer structure, the light-emitting chips do not need to be transferred from the growth substrate to the temporary substrate and then transferred from the temporary substrate to the transfer substrate in the whole transfer process, the temporary substrate and the transfer substrate do not need to be prepared, the transfer efficiency is higher, and the transfer cost is lower.

Based on the same inventive concept, the invention also provides a manufacturing method of the circuit board assembly, which comprises the following steps:

forming the insulating glue layer covering the chip bonding area on the circuit board;

and respectively heating the insulating adhesive material on the first metal bonding pad and the second metal bonding pad so as to shift the insulating adhesive material to respectively form the first through hole and the second through hole.

The manufacturing method of the circuit board assembly is simple in process and high in manufacturing efficiency, when the light-emitting chips are transferred to the manufactured circuit board assembly, the light-emitting chips do not need to be transferred from the growth substrate to the temporary substrate and then from the temporary substrate to the transfer substrate, the temporary substrate and the transfer substrate do not need to be prepared, the chip transfer efficiency is higher, and the transfer cost is lower.

Based on the same inventive concept, the invention also provides a chip transfer method for transferring a light emitting chip to the circuit board assembly, which comprises the following steps:

arranging the light-emitting chip grown on the growth substrate and the chip bonding area on the circuit board in an alignment manner;

and stripping a target light-emitting chip to be transferred on the growth substrate from the growth substrate, so that the target light-emitting chip falls on the insulating adhesive layer on the chip bonding region aligned with the target light-emitting chip, and a first electrode and a second electrode of the target light-emitting chip respectively fall into the corresponding first through hole and the corresponding second through hole.

According to the chip transfer method, when the light-emitting chip is transferred to the circuit board assembly, a target light-emitting chip to be transferred on the growth substrate can be directly transferred to the insulating glue layer of the corresponding chip bonding area, so that the first electrode and the second electrode of the target light-emitting chip respectively fall into the corresponding first through hole and the corresponding second through hole to be connected with the corresponding first metal bonding pad and the corresponding second metal bonding pad, and the first through hole and the second through hole limit the target light-emitting chip at the same time, so that the form and the position of the target light-emitting chip are prevented from being changed; the whole transfer process does not need to transfer the light-emitting chip from the growth substrate to the temporary substrate and then from the temporary substrate to the transfer substrate, and the temporary substrate and the transfer substrate do not need to be prepared, so that the chip transfer efficiency is higher, the transfer cost is lower, the manufacturing efficiency of the light-emitting component is higher, and the manufacturing cost is lower.

Drawings

FIG. 1-1 is a schematic diagram illustrating the transfer of three colors of Micro LED chips from a growth substrate to a display backplane, respectively, in a related art;

FIG. 1-2 is a schematic diagram of a process for transferring a red light Micro LED chip in the related art;

FIGS. 1-3 are schematic views of a bonding region between a temporary substrate and a growth substrate in the related art;

FIGS. 1-4 are schematic diagrams of a temporary substrate carrying a red Micro LED chip according to the related art;

FIGS. 1-5 are schematic diagrams of a temporary substrate after a portion of red Micro LED chips are picked up;

FIGS. 1-6 are schematic views of a display backplane after transfer and bonding of Micro LED chips is completed;

fig. 2 is a graph showing a relationship between the viscosity and the temperature of the insulating adhesive material according to the embodiment of the present invention;

fig. 3 is a first schematic structural diagram of a circuit board assembly according to an embodiment of the present invention;

fig. 4 is a second schematic structural diagram of a circuit board assembly according to an embodiment of the present invention;

fig. 5 is a schematic structural diagram of a circuit board assembly according to an embodiment of the present invention;

FIG. 6 is a schematic flow chart of a method for manufacturing a circuit board assembly according to another alternative embodiment of the present invention;

fig. 7 is a schematic flow chart illustrating a process for fabricating a first via and a second via according to another alternative embodiment of the present invention;

FIG. 8 is a first schematic diagram illustrating a circuit board assembly manufacturing process according to another alternative embodiment of the present invention;

fig. 9 is a second schematic diagram illustrating a manufacturing process of a circuit board assembly according to another alternative embodiment of the present invention;

fig. 10 is a schematic flow chart of a light emitting chip transfer method according to yet another alternative embodiment of the present invention;

fig. 11 is a schematic diagram illustrating a light emitting chip transferring process according to yet another alternative embodiment of the present invention;

FIG. 12 is a schematic diagram of a bad chip replacement process according to yet another alternative embodiment of the present invention;

description of the reference numerals:

10-growth substrate, 101-red Micro LED chip, 102-chip vacancy, 20-temporary substrate, 201-first adhesive layer, 30-transfer substrate, 301-second adhesive layer, 302-display backplane, 4-circuit board, 40-chip bonding region, 41-first metal pad, 42-second metal pad, 5-insulating glue layer, 51-first through hole, 52-second through hole, 53-third through hole, 6-heating substrate, 61-first heating bump, 62-second heating bump, 63-third heating bump, 7-growth substrate, 8-light emitting chip, 81-first electrode, 82-second electrode, 9-pressure plate.

Detailed Description

To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

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

In the Micro LED display technology, as shown in fig. 1-1, a red Micro LED chip, a blue Micro LED chip and a green Micro LED chip need to be transferred from their respective growth substrates to a display backplane. For example, the transferring process for red light Micro LED chips can be seen in fig. 1-2 to fig. 1-5, which includes:

s201: attaching the surface of the temporary substrate 20 provided with the first adhesive layer 201 (i.e., the photolysis layer) to the surface of the growth substrate 10 on which the red Micro LED chip 101 grows; one of which is shown in top view in fig. 1-3 after application;

s202 to S203: peeling the growth substrate 10, and transferring the red light Micro LED chip 101 to a temporary substrate 20; a top view of the temporary substrate 20 at this time is shown in fig. 1-4;

s204: attaching the surface, provided with the second adhesive layer 301, of the transfer substrate 30 to the surface, carrying the red light Micro LED chips 101, of the temporary substrate 20, providing laser to irradiate from the back surface of the temporary substrate 20, and debonding the photolysis adhesive on the temporary substrate 20, so as to selectively pick up the corresponding red light Micro LED chips 101 from the temporary substrate 20; referring to fig. 1-5, the red Micro LED chips 101 at corresponding positions on the temporary substrate 20 are picked up to leave corresponding chip vacancies 102;

s205: and transferring the red light Micro LED chips picked up by the transfer substrate 30 to the corresponding chip bonding areas on the display back plate 302.

The blue light Micro LED chips and the green light Micro LED chips are also transferred to the display back panel in sequence by adopting the chip transfer process, and the display back panel for completing the transfer of all the Micro LED chips is shown in the figures 1-6.

In the chip transfer process, two types of glue materials are required to be selected to respectively manufacture the first adhesive layer 201 and the second adhesive layer 301, the viscosity of the first adhesive layer 201 needs to be lower than that of the second adhesive layer 301, and a suitable material is difficult to find, and in the transfer process, the Micro LED chip needs to be transferred from the growth substrate 10 to the temporary substrate 20 and from the temporary substrate 20 to the transfer substrate 30, so that the transfer efficiency is low, the temporary substrate 10 and the transfer substrate 30 need to be prepared, and the transfer cost is high.

Based on this, the present invention intends to provide a solution to the above technical problem, the details of which will be explained in the following embodiments.

The present embodiment provides a circuit board assembly, including:

the circuit board in this embodiment may be a display backplane, or may be various circuit boards for lighting, or may be a flexible circuit board, or may be a rigid circuit board. When the display back plate is a glass back plate, the display back plate can be, but is not limited to, a glass back plate or a PCB plate.

In this embodiment, the circuit board is provided with a plurality of chip bonding regions, and the chip bonding regions are provided with a first metal pad and a second metal pad corresponding to a first electrode and a second electrode of the light emitting chip, respectively. It should be understood that, in this embodiment, the number of the chip bonding regions disposed on the circuit board and the distribution of each chip bonding region on the circuit board may be flexibly set according to application requirements, for example, each chip bonding region may be distributed on the circuit board in an array, may also be flexibly distributed according to other rules, and may even be flexibly distributed according to requirements; in some application examples, in order to facilitate the direct transfer of the light emitting chips from the growth substrate to the circuit board, the distribution of the chip bonding regions on the circuit board may correspond to the layout and positions of the corresponding light emitting chips on the growth substrate.

It should be understood that the chip bonding region in this embodiment is not limited to be bonded with the light emitting chip, and the light emitting chip may be replaced with other electronic chips according to application requirements, such as a resistor chip, a capacitor chip, a driving chip, a control chip, and the like, and therefore, the description is not repeated here. The shape and size of the first metal pad and the second metal pad in the chip bonding region in this embodiment can be flexibly set. And In this embodiment, the first metal pad and the second metal pad may be composed of corresponding electrodes In the chip bonding region and a metal solder (for example, but not limited to, indium In) disposed on the electrodes. The first metal pad and the second metal pad may have the same shape, such as a rectangle, an ellipse, a circle, etc., and the shapes of the first metal pad and the second metal pad may also be different; and the shape of at least one of the two can be set to be a regular shape, and can also be set to be an irregular shape.

It should be understood that the light emitting chip in the present embodiment may be a Micro light emitting chip with a chip size less than 200 micrometers, for example, but not limited to, at least one of a Mini LED chip and a Micro LED chip; the light emitting chip in the present embodiment may also be a general light emitting chip having a size of 200 μm or more. The light emitting chip in this embodiment may be, but is not limited to, a flip light emitting chip, and may be flexibly configured according to application requirements. In this embodiment, the light emitting surface of the light emitting chip grown on the growth substrate is attached to the growth substrate, and the first electrode and the second electrode of the light emitting chip are located on a side away from the growth substrate.

The circuit board assembly in this embodiment further includes an insulating adhesive layer disposed on the circuit board and covering the chip bonding regions, and the insulating adhesive layer is disposed in a region above the chip bonding regions and is respectively formed with a first through hole and a second through hole communicated with the first metal pad and the second metal pad. Namely, the first metal bonding pad and the second metal bonding pad in each chip bonding region can be respectively exposed out of the insulating adhesive layer through the first through hole and the second through hole; the insulating glue layer positioned on each chip bonding area, the first through hole and the second through hole form a chip catching structure. When the light-emitting chips are transferred to the circuit board assembly, target light-emitting chips to be transferred on the growth substrate can be directly transferred to the insulating glue layers of the corresponding chip bonding areas, the first electrodes and the second electrodes of the target light-emitting chips respectively fall into the corresponding first through holes and the corresponding second through holes to be connected with the corresponding first metal bonding pads and the corresponding second metal bonding pads, the first through holes and the second through holes can play a limiting role in the target light-emitting chips, the change of the shapes and the positions of the target light-emitting chips is avoided, and the follow-up transfer of other light-emitting chips to the circuit board is not influenced. Therefore, when the circuit board assembly provided by the invention is transferred with the light-emitting chips, the corresponding light-emitting chips on the growth substrate can be captured and limited by directly utilizing the insulating layer structure, the light-emitting chips do not need to be transferred from the growth substrate to the temporary substrate and then from the temporary substrate to the transfer substrate in the whole transfer process, the temporary substrate and the transfer substrate do not need to be prepared, the transfer efficiency is higher, and the transfer cost is lower.

It should be understood that in the present embodiment, at least one of the shape and the size of the first through hole and the second through hole formed in the insulating adhesive layer over the chip bonding region may be the same or different. The method can be flexibly set according to application requirements. In this embodiment, the sizes of the first through hole and the second through hole may be matched with the sizes of the first electrode and the second electrode of the light emitting chip, so that at least the first electrode and the second electrode can fall into the first through hole and the second through hole, respectively. In addition, in this embodiment, the first through hole and the second through hole are isolated by the insulating adhesive material of the insulating adhesive layer, so that the short circuit between the first electrode and the second electrode of the subsequent light-emitting chip and the corresponding first metal pad and second metal pad can be prevented better. Of course, in some examples, the first through hole and the second through hole may also be communicated to form a large third through hole, and the size of the third through hole may only allow the first electrode and the second electrode of the light emitting chip to fall into the third through hole, or may allow the entire surface of the light emitting chip on which the first electrode and the second electrode are formed to fall into the third through hole, which may be flexibly set according to application requirements.

In an example of the present embodiment, the first through hole and the second through hole may be, but are not limited to, formed by respectively heating the insulating adhesive material on the first metal pad and the second metal pad, so that the insulating adhesive material is displaced. Because the wettability of the insulating adhesive material and the metal is poor, after the insulating adhesive material on the first metal pad and the second metal pad is respectively heated and melted, the insulating adhesive material which originally covers the first metal pad and the second metal pad can respectively fall off the first metal pad and the second metal pad, namely, displacement is generated, so that the part of the space originally occupied by the part of the insulating adhesive material forms a first through hole and a second through hole respectively. In this example, the above-mentioned formation methods of the first through hole and the second through hole are realized simply and reliably, and do not need to remove the insulating glue material, can avoid the influence of the residue in the process of removing the glue material. It should be understood that the specific material of the insulating adhesive material in the embodiment can be flexibly set when the above conditions are satisfied. For example, the insulating adhesive layer may be provided as an NCF (Non Conductive Film). In one application scenario, the non-conductive adhesive film may be, but is not limited to, a glue material manufactured by japan shin-Etsu chemical corporation and having a product model number of LPS-7585, and the viscosity of the glue material has a significant responsiveness with temperature, and as shown in fig. 2, when the first through hole and the second through hole are formed, the corresponding heating temperature may be flexibly controlled according to the viscosity of the specific insulating glue material used and the significant responsiveness with temperature.

Of course, in other examples of this embodiment, the insulating material may also be other sacrificial materials such as, but not limited to, photoresist, and the insulating material on the first metal pad and the second metal pad is removed through a corresponding photolithography process, so as to form the first via and the second via.

In some examples of the embodiment, the thickness of the insulating glue layer may be set to be equal to or less than an electrode height of the light emitting chip, where the electrode height is a minimum height of the first electrode and the second electrode of the light emitting chip; therefore, after the light-emitting chip falls on the insulating glue layer on the corresponding chip bonding area, the first electrode and the second electrode of the light-emitting chip can be contacted with the corresponding first metal pad and the corresponding second metal pad through the first through hole and the second through hole, and the subsequent reliable bonding of the first electrode and the second electrode with the first metal pad and the second metal respectively is facilitated. Of course, in some examples, the thickness of the insulating adhesive layer may also be slightly greater than the height of the electrode of the light emitting chip, and the insulating adhesive layer may be heated to be slightly softened during the bonding process, so as to facilitate pressing down the light emitting chip so that the first electrode and the second electrode of the light emitting chip are reliably bonded with the first metal pad and the second metal pad, respectively.

For the convenience of understanding, the present embodiment will be described below with reference to a circuit board assembly shown in the drawings as an example.

An exemplary circuit board assembly is shown in fig. 3, which includes a circuit board 4, a plurality of chip bonding regions 40 (one chip bonding region is shown by a dashed line frame in fig. 4) disposed on the circuit board 4, and a first metal pad 41 and a second metal pad 42 respectively corresponding to a first electrode and a second electrode of a light emitting chip are disposed in the chip bonding regions 40. The circuit board assembly further includes an insulating adhesive layer 5 disposed on the circuit board 4, the insulating adhesive layer 5 covers the chip bonding regions 40, and a first through hole 51 and a second through hole 52, which are specifically communicated with the first metal pad 41 and the second metal pad 42 in each chip bonding region 40, are formed in an area above each chip bonding region 40, that is, the first metal pad 41 and the second metal pad 42 are respectively exposed out of the insulating adhesive layer 5 through the corresponding first through hole 51 and the corresponding second through hole 52. In the example shown in fig. 3, the first through hole 51 and the second through hole 52 are isolated by an insulating adhesive material, and the first metal pad 41 and the second metal pad 42 are also isolated by the insulating adhesive material, so that the occurrence of short circuit caused by pad melting when the first electrode and the second electrode of the light-emitting chip are subsequently bonded between the corresponding first metal pad 41 and the corresponding second metal pad 42 is ensured, and the reliability and the yield of chip bonding are improved.

Another exemplary circuit board assembly is shown in fig. 4, which is different from the circuit board assembly shown in fig. 3 mainly in that the region of the insulating glue layer 5 located above each die bonding area 40 is provided with a third via 53 communicating with the first metal pad 41 and the second metal pad area 42 in each die bonding area 40, and the third via 53 can be seen as formed after the communication between the first via 51 and the second via 52 shown in fig. 3. The maximum diameter of the third through hole 53 may be smaller than the maximum diameter of the surface of the light emitting chip on which the first electrode and the second electrode are formed, or may be larger than the maximum diameter of the surface of the light emitting chip on which the first electrode and the second electrode are formed, and the third through hole may be flexibly disposed, and is not described herein again.

It should be understood that in this embodiment, the insulating glue layer 5 may cover the area between adjacent chip bonding areas 40 on the circuit board, for example, see the examples shown in fig. 3 and 4. In some examples, however, the layer of insulating glue 5 may not cover the area of the circuit board between adjacent chip bond pads 40, for example, see the example shown in fig. 5. Of course, the insulating glue layer 5 may also be arranged to cover a portion of the area between adjacent chip bonding regions 40, as desired. The configuration can be flexibly set according to application requirements and environment, and is not repeated herein.

When the light emitting chip is transferred to the circuit board assembly in each of the above examples, the target light emitting chip to be transferred on the growth substrate may be directly transferred to the insulating glue layer 5 of the corresponding chip bonding region 40 on the circuit board 4, and the first electrode and the second electrode of the target light emitting chip respectively fall into the corresponding first through hole 51 and the second through hole 52 to be connected with the corresponding first metal pad 41 and the corresponding second metal pad 42, and the first through hole 51 and the second through hole 52 can limit the position of the target light emitting chip, so as to avoid the change of the shape and the position of the target light emitting chip; the light-emitting chips do not need to be transferred from the growth substrate to the temporary substrate and then transferred from the temporary substrate to the transfer substrate in the whole transfer process, and the temporary substrate and the transfer substrate do not need to be prepared any more, so that the transfer efficiency is higher, and the transfer cost is lower.

Another alternative embodiment:

for ease of understanding, the present embodiment is described below with reference to fig. 6, which illustrates an exemplary method for manufacturing the circuit board assembly, including but not limited to:

s601: and forming an insulating glue layer covering the bonding areas of the chips on the circuit board.

It should be understood that the process of forming the insulating adhesive layer on the circuit board according to the present embodiment may be flexibly selected, for example, the insulating adhesive layer may be formed by, but not limited to, coating, molding, spraying, printing, etc. And the formed insulating glue layer can cover the whole surface of the circuit board, on which the chip bonding regions are arranged, or only partially cover the surface, for example, at least a part of the area between adjacent chip bonding regions can be uncovered.

S602: and respectively heating the insulating adhesive material on the insulating adhesive layer above each first metal bonding pad and each second metal bonding pad, so that the insulating adhesive material is displaced to form a first through hole and a second through hole respectively.

Because the insulating glue material and the metal have poor wettability, after the insulating glue material on the first metal bonding pad and the second metal bonding pad is respectively heated and melted, the insulating glue material which originally covers the first metal bonding pad and the second metal bonding pad can respectively fall off the first metal bonding pad and the second metal bonding pad, namely displacement is generated, so that the part of the space originally occupied by the part of the insulating glue material respectively forms a first through hole and a second through hole. Therefore, the forming mode of the first through hole and the second through hole is simple and reliable, the insulating glue material is not required to be removed, and the influence of residues in the glue material removing process can be avoided. In the embodiment, after the insulating adhesive material on each of the first metal pad and the second metal pad is heated and displaced, the heat source can be rapidly removed, so that the heated temperature of the part of the insulating adhesive material is rapidly attenuated and shaped, and the first through hole and the second through hole are maintained.

In this embodiment, the manner of heating the insulating adhesive layer on each of the first metal pads and the second metal pads respectively can be flexibly selected, for example, a heat source can be purposefully sprayed to the insulating adhesive layer in these areas to locally heat the insulating adhesive layer, or a heating device can be disposed on the insulating adhesive layer in these areas to locally heat the insulating adhesive layer. For ease of understanding, the present embodiment is described below in the form of forming a first through hole and a second through hole as shown in fig. 7, and includes:

s701: the heating substrate is provided with a plurality of first heating bulges and a plurality of second heating bulges, one side of each first heating bulge and one side of each second heating bulge are attached to the insulating glue layer, and the first heating bulges and the second heating bulges are respectively arranged in one-to-one alignment with the first metal bonding pads and the second metal bonding pads.

S702: the first heating bulge and the second heating bulge respectively heat the insulating adhesive material on the first metal pad and the second metal pad, so that the insulating adhesive material is separated from the first metal pad and the second metal pad after being melted, and a first through hole and a second through hole are formed.

S703: and removing the heating substrate, and cooling, solidifying and shaping the melted insulating glue material to keep the first through hole and the second through hole.

In this embodiment, the heating substrate may be made of various materials with good thermal conductivity, for example, a silicon-based heating plate, or a metal heating plate or a ceramic heating plate.

For ease of understanding, the present embodiment will be described below by taking two circuit board assemblies shown in fig. 3 and 4 as examples.

One example of making the circuit board assembly of fig. 3 is shown in fig. 8, which includes but is not limited to;

s801: an insulating glue layer 5 is formed on the circuit board 4, and the insulating glue layer 5 covers each chip bonding area on the circuit board 4.

S802: aligning and attaching one surface of the heating substrate 6, which is provided with the plurality of first heating protrusions 61 and the plurality of second heating protrusions 62, to the insulating adhesive layer 4, and aligning the first heating protrusions 61 and the second heating protrusions 62 to the first metal pads 41 and the second metal pads 42 one by one after attaching; and the heating substrate 6 is heated so that the first heating bump 61 and the second heating bump 62 are heated to the insulating paste material on the first metal pad 41 and the second metal pad 42, respectively.

S803: the insulating glue material on the first metal pad 41 and the second metal pad 42 is heated and melted, and is separated from the first metal pad 41 and the second metal pad 42, so that a first through hole 51 and a second through hole 52 are formed.

S804: the heated substrate 6 is removed, and the temperature of the melted insulating paste rapidly decays, so that the part of the insulating paste is cured and shaped, and the first through hole 51 and the second through hole 52 are remained.

One example of making the circuit board assembly of fig. 4 is shown in fig. 9, which includes but is not limited to;

s901: an insulating glue layer 5 is formed on the circuit board 4, and the insulating glue layer 5 covers each chip bonding area on the circuit board 4.

S902: aligning and attaching one surface of the heating substrate 6 provided with the plurality of third heating bulges 63 to the insulating glue layer 4, and aligning and arranging one third heating bulge 63 to the first metal pad 41 and the second metal pad 42 in one chip bonding region 40 after attaching; and the heating substrate 6 is heated so that the third heating bumps 63 heat the insulating paste material on the first and

second metal pads

41 and 42.

S903: the insulating glue material on the first metal pad 41 and the second metal pad 42 is heated and then melted, and is separated from the first metal pad 41 and the second metal pad 42, so as to form a third through hole 53.

S904: the heating substrate 6 is removed, and the temperature of the melted insulating glue material is rapidly attenuated, so that the part of the insulating glue material is solidified and shaped, and the third through holes 53 are reserved.

Therefore, the circuit board assembly manufacturing method provided by the embodiment is simple, convenient and efficient. When the light-emitting chip is transferred to the manufactured circuit board assembly, the light-emitting chip does not need to be transferred from the growth substrate to the temporary substrate and then from the temporary substrate to the transfer substrate, and the temporary substrate and the transfer substrate do not need to be prepared, so that the chip transfer efficiency is higher, and the transfer cost is lower.

Yet another alternative embodiment:

for ease of understanding, the present embodiment will be described below by taking a chip transfer method as an example. The chip transfer method includes transferring the light emitting chip to the circuit board assembly shown in the above embodiments, and the transfer process is shown in fig. 10, which includes but is not limited to:

s1001: and aligning the light-emitting chip grown on the growth substrate with the chip bonding region on the circuit board.

Of course, it should be understood that in some application scenarios, the growth substrate in the present embodiment may be replaced by other substrates, such as but not limited to a transient substrate (or referred to as a temporary substrate) or a transfer substrate, etc.

In some examples of this embodiment, in order to further improve the yield of transferring the light emitting chips, after the light emitting chips grown on the growth substrate are aligned with the chip bonding regions on the circuit board, the distance between the growth substrate and the circuit board may be set to be greater than the warpage of the growth substrate and less than or equal to 10 times the height of the light emitting chips. For example, when the growth substrate is a 4-inch growth substrate, the distance between the growth substrate and the circuit board may be set to be, but not limited to, greater than 20 micrometers and less than 70 micrometers, and the specific distance value may be flexibly set according to specific application requirements, which is not described herein again.

S1002: transferring a target light emitting chip to be transferred on a growth substrate onto a circuit board, comprising:

and stripping a target light-emitting chip to be transferred on the growth substrate from the growth substrate, so that the target light-emitting chip falls on the insulating glue layer on the chip bonding region aligned with the target light-emitting chip, and the first electrode and the second electrode of the target light-emitting chip respectively fall into the corresponding first through hole and the corresponding second through hole.

In some examples, after the target light-emitting chip to be transferred on the growth substrate is transferred onto the circuit board each time, the first electrode and the second electrode of the currently transferred target light-emitting chip are respectively bonded with the corresponding first metal pad and the corresponding second metal pad, and due to the arrangement of the insulating glue layer during bonding, the first metal pad and the second metal pad of the chip bonding region where the light-emitting chip is not currently arranged can be prevented from being melted by heating. In other examples, after all the light emitting chips are transferred onto the circuit board, the first electrodes and the second electrodes of all the light emitting chips can be bonded with the corresponding first metal pads and second metal pads respectively in one chip bonding process. An example of controlling bonding of electrodes of a target light emitting chip and corresponding metal pads may be, but is not limited to:

after target light-emitting chips to be transferred on the growth substrate are transferred onto a circuit board, heating and melting a first metal pad and a second metal pad in each chip bonding area, and applying pressure towards the circuit board to each target light-emitting chip through a pressure plate so that a first electrode and a second electrode of each target light-emitting chip are bonded with the corresponding first metal pad and the corresponding second metal pad; and the pressure plate is used for pressing, so that the bonding consistency and reliability of each target light-emitting chip can be ensured as much as possible. The pressure plate in this embodiment can be, but is not limited to, a soft pressure plate, such as a PDMS (Polydimethylsiloxane) pressure plate or a TPU (Thermoplastic polyurethane elastomer rubber) pressure plate, so as to avoid damage to the light emitting chip as much as possible.

In the field of Micro LED display, such as Micro LED display, the number of Micro LED chips transferred to the display backplane is generally in the order of tens of thousands or more. Therefore, after the Micro LED chip is completed, the defective pixel on the display backplane is difficult to detect, and even if the defective pixel is detected, the defective pixel is difficult to repair, and even if the defective pixel is repaired, the repair process is complicated. In addition, when the Micro LED chips are transferred, the Micro LED chips on the growth substrate are subjected to laser lift-off in a whole surface manner, and all the Micro LED chips are transferred to the temporary substrate, so that the quality of the chips on the finally prepared Micro LED display device is uncontrollable, and the later maintenance cost is higher; in addition, the light-emitting wavelength of the Micro LED chip cannot be selected in advance, so that the finally prepared display device is poor in light-emitting uniformity. In view of this problem, in this embodiment, before transferring the light emitting chip on the growth substrate onto the circuit board, for example, before peeling the target light emitting chip to be transferred on the growth substrate off the growth substrate and dropping the target light emitting chip onto the insulating glue layer on the chip bonding region aligned with the target light emitting chip, the method may further include:

and detecting each light-emitting chip on the growth substrate so as to detect unqualified light-emitting chips (namely, dead-spot chips). In some examples, detected bad dies may be removed from the growth substrate; therefore, the light-emitting chips left on the growth substrate are qualified, and the condition that the light-emitting chips transferred to the circuit board have dead spots is avoided as much as possible. The detected defective pixel chips can be kept on the growth substrate, but are marked or recorded, and the defective pixel chips are not transferred onto the circuit board during subsequent transfer, so that the subsequent defective pixel detection and repair are avoided as much as possible, the product quality is improved, and the maintenance cost is reduced.

In the present embodiment, the detecting of each light emitting chip on the growth substrate may include, but is not limited to, at least one of:

detecting the appearance of each light-emitting chip;

the optical characteristics of each light emitting chip are detected.

For example, in one example, a failed bad point chip can be determined from the optical characteristics and appearance quality of the light emitting chip on the growth substrate by generating mapping data in advance, not limited to the Micro PL/AOI detection mode.

In some examples of the present embodiment, detecting the optical characteristics of each light emitting chip may include, but is not limited to: the main wavelength of each light-emitting chip is detected, and the light-emitting chips with the main wavelength difference value larger than the preset difference value with the preset standard main wavelength are judged as dead pixel chips, so that the main wavelength consistency of the light-emitting chips screened out on the growth substrate is good, the light-emitting uniformity of the light-emitting component is improved to be higher, and the display effect or the lighting effect of the light-emitting component is better.

In some application examples of this embodiment, in order to ensure that the light emitting chip transferred onto the circuit board is a qualified light emitting chip as much as possible, before peeling the target light emitting chip to be transferred on the growth substrate from the growth substrate and dropping the target light emitting chip onto the insulating glue layer on the chip bonding region aligned with the target light emitting chip, the method may further include:

when the target luminescent chip to be transferred on the growth substrate is a defective dot chip, the growth substrate and/or the circuit board can be moved (i.e. the growth substrate or the circuit board can be moved, or both the growth substrate and the circuit board can be moved) so as to align the luminescent chip qualified for detection on the growth substrate onto the chip bonding region where the defective dot chip is aligned, and the luminescent chip is taken as the target luminescent chip to be transferred; therefore, the bad point chips are prevented from being transferred to the circuit board, and the chip transfer yield and the quality of the display panel or the lighting device manufactured after transfer are improved.

For ease of understanding, the present embodiment will be explained below with an example of transferring a light emitting chip to a circuit board assembly shown in fig. 3. The transfer process is illustrated in fig. 11, which includes but is not limited to:

s1101: the light emitting chip 8 grown on the growth substrate 7 is positioned with respect to the chip bonding region 40 on the circuit board 4. The first electrode 81 and the second electrode 82 of the light emitting chip 8 on the growth substrate 7 correspond to the first metal pad 41 (and the first via 51) and the second metal pad 42 (and the second via 52) in the corresponding chip bonding region 40, respectively.

S1102: and peeling off the target light-emitting chip to be transferred on the growth substrate 7 from the growth substrate 7, so that the target light-emitting chip falls on the insulating glue layer 5 on the chip bonding region 40 aligned with the target light-emitting chip, and the first electrode 81 and the second electrode 82 of the target light-emitting chip respectively fall into the corresponding first through hole 51 and the corresponding second through hole 52.

Wherein, when the bad point chip exists on the growth substrate, a transferring process is shown in fig. 12. In S1201, the light-emitting chip detected as being qualified on the growth substrate 7 may be peeled off from the growth substrate 7 as a target light-emitting chip to be transferred, and the light-emitting chip on the chip bonding region is not peeled off when the light-emitting chip is a defective chip (for example, the leftmost light-emitting chip in 12 is a defective chip). Then, aligning the qualified light-emitting chips detected on the growth substrate 7 to the chip bonding region 40 of the dead chip alignment by moving the growth substrate 7 and/or the circuit board 4 to be used as target light-emitting chips to be transferred; therefore, the bad point chips are prevented from being transferred to the circuit board, and the chip transfer yield and the quality of the display panel or the lighting device manufactured after transfer are improved.

S1103: after the target light-emitting chips are transferred onto the circuit board 4, the growth substrate 7 is removed, the first and

second metal pads

41 and 42 in each chip bonding region 40 are heated to be melted, and a pressure F is applied to each target light-emitting chip toward the circuit board 4 by the pressure plate 9.

S1104: the first electrode 81 and the second electrode 82 of each target light emitting chip are bonded to the corresponding first metal pad 41 and second metal pad 42.

S1105; the pressure plate 9 is removed.

Therefore, in the chip transfer process, the light-emitting chip does not need to be transferred from the growth substrate to the temporary substrate and then transferred from the temporary substrate to the transfer substrate, and the temporary substrate and the transfer substrate do not need to be prepared, so that the chip transfer efficiency is higher, the transfer cost is lower, the manufacturing efficiency of the light-emitting component is higher, and the manufacturing cost is lower.

The present embodiment further provides a display screen, which may be a flexible display screen or a rigid display screen, and which may be a display screen with a regular shape, such as a rectangle, a circle, an ellipse, or an irregular display screen. The display screen comprises a display screen frame and a display panel as shown in the above examples, wherein the display panel is made of the light-emitting component and is fixedly arranged in the display screen frame. It should be understood that the display screen in the present embodiment may be applied to various electronic devices, such as a display, a computer, a mobile phone, a smart watch, an in-vehicle device, a billboard, and the like. The display screen is higher in manufacturing efficiency, lower in cost, better in yield, higher in light emitting efficiency and better in display effect.

It is to be understood that the invention is not limited to the examples described above, but that modifications and variations may be effected thereto by those of ordinary skill in the art in light of the foregoing description, and that all such modifications and variations are intended to be within the scope of the invention as defined by the appended claims.

Claims

1. A circuit board assembly for array bonding a plurality of light emitting chips as a display, comprising:

the circuit board is provided with a plurality of chip bonding areas, and a first metal bonding pad and a second metal bonding pad which respectively correspond to a first electrode and a second electrode of the light-emitting chip are arranged in the chip bonding areas; wherein the content of the first and second substances,

the circuit board assembly further includes:

and the insulating glue layer is arranged on the circuit board and covers the chip bonding regions, is positioned in the region above the chip bonding regions, and is respectively provided with a first through hole and a second through hole which are communicated with the first metal bonding pad and the second metal bonding pad.

2. The circuit board assembly of claim 1, wherein the thickness of the insulating glue layer is less than or equal to an electrode height, the electrode height being a minimum height of the first and second electrodes.

3. The circuit board assembly of claim 1 or 2, wherein the insulating glue layer is a non-conductive glue film.

4. A method of making a circuit board assembly according to any of claims 1-3, comprising:

5. The method of claim 4, wherein the applying heat to the insulating glue layer over the first metal pad and the second metal pad, respectively, such that the insulating glue displaces to form the first via and the second via, respectively, comprises:

attaching one surface of a heating substrate provided with a plurality of first heating bulges and a plurality of second heating bulges to the insulating adhesive layer, wherein the first heating bulges and the second heating bulges are respectively arranged in one-to-one alignment with the first metal bonding pads and the second metal bonding pads;

heating the insulating adhesive material on the first metal pad and the second metal pad through the first heating bulge and the second heating bulge respectively, so that the insulating adhesive material is separated from the first metal pad and the second metal pad after being melted, and the first through hole and the second through hole are formed;

and removing the heating substrate, cooling and solidifying the melted insulating glue material and keeping the first through hole and the second through hole.

6. The method of claim 5, wherein the heated substrate is a silicon-based heater plate.

7. A chip transfer method for transferring a light emitting chip to the circuit board assembly according to any one of claims 1 to 3, comprising:

aligning the light-emitting chip grown on the growth substrate with the chip bonding region on the circuit board;

8. The chip transfer method according to claim 7, wherein before the target light emitting chip to be transferred on the growth substrate is peeled off from the growth substrate and falls on the insulating glue layer above the chip bonding region aligned with the target light emitting chip, the method further comprises:

detecting the light-emitting chips growing on the growth substrate to determine defective chips which are unqualified in detection;

and when the target luminescent chip to be transferred on the growth substrate is the dead pixel chip, moving the growth substrate and/or the circuit board to align the luminescent chip which is detected to be qualified on the growth substrate onto the chip bonding area in which the dead pixel chip is aligned, and taking the luminescent chip as the target luminescent chip to be transferred.

9. The chip transfer method according to claim 7 or 8, wherein after the light emitting chip grown on the growth substrate is aligned with the chip bonding region on the circuit board, the distance between the growth substrate and the circuit board is greater than 20 micrometers and less than 70 micrometers.

10. The chip transfer method according to claim 7 or 8, wherein after transferring the target light emitting chip to be transferred on the growth substrate onto the circuit board, further comprising:

heating and melting the first metal pad and the second metal pad in each chip bonding area, and applying pressure towards the circuit board to each target light-emitting chip through a pressure plate, so that the first electrode and the second electrode of each target light-emitting chip are bonded with the corresponding first metal pad and second metal pad.