TW201427093A - LED chip unit and method for manufacturing the same - Google Patents

Abstract

An LED chip unit includes a flexible base and a chip mounted on the base. The chip includes a first semiconductor layer, a light emitting layer, a second semiconductor layer and an electrode. The electrode is connected to the base through a flexible insulative layer doped with conductive particulates. The conductive particulates electrically connect the base with the electrode. The chip is difficult to be separated from the base by effect of the flexible insulative layer so that the chip is reliably electrically connected to the base. A method for manufacturing the LED chip unit is also disclosed.

Description

Light-emitting chip combination and manufacturing method thereof

The present invention relates to a wafer assembly, and more particularly to a light emitting wafer assembly.

As an emerging light source, light-emitting diodes have been widely used in various applications. The light emitting diode generally includes a susceptor, a wafer mounted on the pedestal, and a package covering the wafer. The wafer is composed of a substrate and an N-type semiconductor layer, a light-emitting layer, and a P-type semiconductor layer which are sequentially grown on the substrate. The wafer also forms a P electrode and an N electrode on the N-type semiconductor layer and the P-type semiconductor layer, respectively, to be electrically connected to the pedestal, thereby introducing a current into the wafer to drive the luminescent layer to emit light.

In order to improve the light extraction efficiency, some wafers are currently fixed on the pedestal in a flip-chip form. The two electrodes of the flip chip are respectively soldered to the two conductive layers on the pedestal through a tin ball, thereby achieving electrical connection with the susceptor. A manufacturer uses a soft material to fabricate a susceptor to obtain a flexible light-emitting diode. However, since the two electrodes of the wafer are soldered to the conductive layer of the flexible pedestal by rigid solder balls, the electrodes, the solder balls and the conductive layer are easily generated by internal stress during the bending of the soft pedestal. Separation causes the light-emitting diode to open.

Therefore, it is necessary to provide an illuminating wafer combination which is less prone to breakage and a method of manufacturing the same.

An illuminating wafer assembly comprising a wafer and a flexible susceptor carrying the wafer, the wafer comprising a substrate and a first semiconductor layer, a luminescent layer, a second semiconductor layer and an electrode sequentially stacked on the substrate, the electrode being electrically insulated by doping with conductive particles The layers are bonded to the pedestal to effect electrical connection between the wafer and the pedestal.

A manufacturing method of a light emitting wafer assembly, comprising: providing a flexible base and a light emitting chip, wherein the light emitting chip comprises a first semiconductor layer, a light emitting layer, a second semiconductor layer and an electrode which are sequentially stacked; and a soft insulating layer containing conductive particles is coated on the base a layer; placing the luminescent wafer on the flexible insulating layer to bring the electrode into contact with the soft insulating layer; applying pressure to gradually bring the luminescent wafer closer to the substrate until the electrode is electrically connected to the pedestal through the conductive particles.

Since the electrode and the susceptor of the wafer are bonded by a soft insulating layer, the stress caused to the electrode of the wafer due to the bending of the susceptor can be offset, and the electrode and the susceptor are less likely to fall off. Moreover, the conductive particles doped in the soft insulating layer ensure electrical connection between the electrode and the susceptor, so that current can enter the wafer from the susceptor, and the driving wafer is normally illuminated.

Referring to Figure 1, an illuminating wafer assembly 10 in accordance with one embodiment of the present invention is illustrated. The illuminating wafer assembly 10 includes a susceptor 20 and a luminescent wafer 30 affixed to the susceptor 20.

The susceptor 20 includes a substrate 22 and a first conductive layer 24 and a second conductive layer 26 covering the top surface of the substrate 22. The pedestal 20 can be a pedestal integrated inside the illuminating diode or a flexible circuit board. In this embodiment, the substrate 22 is made of a soft material such as a polyimide or a polyester film. The substrate 22 can be bent to some extent under the action of an external force. The first conductive layer 24 and the second conductive layer 26 are formed on the top surface of the substrate 22 by printing or the like. The first conductive layer 24 and the second conductive layer 26 are preferably fabricated using a metal film to provide excellent electrical conductivity. The first conductive layer 24 and the second conductive layer 26 are separated by a gap to prevent direct conduction between the two.

The light-emitting wafer 30 includes a substrate 32 and a first semiconductor layer 34, a light-emitting layer 36, and a second semiconductor layer 38 which are sequentially formed on the substrate 32. In the present embodiment, the substrate 32 is made of a light transmissive material such as sapphire, so that the light emitted from the light emitting layer 36 is transmitted outside the light emitting chip 30. Of course, the substrate 32 can also be removed by grinding, laser lift-off or the like to directly expose the top surface of the first semiconductor layer 34, so that the light emitted by the light-emitting layer 36 can be directly emitted from the first semiconductor layer 34. The first semiconductor layer 34, the second semiconductor layer 38, and the light-emitting layer 36 are made of a material such as gallium nitride, indium gallium nitride, or aluminum indium gallium nitride. In this embodiment, the first semiconductor layer 34 is an N-type layer, the second semiconductor layer 38 is a P-type layer, and the light-emitting layer 36 is a multiple quantum well layer. The area of the light-emitting layer 36 and the second semiconductor layer 38 is smaller than the area of the first semiconductor layer 34, so that an exposed region 340 is formed on the bottom surface of the first semiconductor layer 34. A first electrode 31 is formed on the exposed region 340 of the first semiconductor layer 34 by vapor deposition or the like, and a second electrode 33 is formed on the bottom surface of the second semiconductor layer 38 by vapor deposition or the like. The first electrode 31 and the second electrode 33 are each preferably made of a metal material to introduce current from the outside into the light-emitting wafer 30. The first electrode 31 is higher than the second electrode 33 and spaced apart from each other.

The luminescent wafer 30 is secured to the susceptor 20 by a bonding layer 40. In this embodiment, the bonding layer 40 is an anisotropic conductive paste. The bonding layer 40 includes a soft insulating layer 42 and a large number of conductive particles 44 doped in the soft insulating layer 42. The flexible insulating layer 42 is preferably made of an insulating material such as epoxy resin or silicone rubber, and has a thickness of 20 to 85 μm. The conductive particles 44 are nickel-plated resin balls which have a certain elasticity and can be deformed by an external force. The particle diameter of the conductive particles 44 is between 1 and 15 μm. The conductive particles 44 are uniformly doped in the soft insulating layer 42. The conductive particles 44 in the soft insulating layer 42 are only conducted in the thickness direction (ie, vertical direction) of the bonding layer 40, and are not conductive in the length or width direction (ie, lateral direction) of the bonding layer 40, and thus the bonding layer 40 is only vertically conductive. To prevent short-circuiting due to lateral conduction.

Referring to FIG. 2 together, the bonding layer 40 is in a flowable adhesive shape before being uncured, and is pre-coated on the top surface of the susceptor 20 to cover the first conductive layer 24, the second conductive layer 26, and both. The gap between them. Then, the first electrode 31 and the second electrode 33 of the light-emitting wafer 30 are moved toward the bonding layer 40 until they are embedded in the bonding layer 40. Thereafter, the bonding layer is heated to about 40 degrees Celsius, and at the same time, a downward pressure is applied to the luminescent wafer 30 such that the first electrode 31 and the second electrode 33 face the first conductive layer 24 and the second conductive layer 26 of the susceptor 20. mobile. At this time, the conductive particles 44 in the bonding layer 40 are compressed and elastically deformed to form an ellipsoidal structure. The pressure is maintained at a temperature of about 200 degrees Celsius for a period of time until the soft insulating layer 42 of the bonding layer 40 is cured into a gel state, at which time the second semiconductor layer 38, the light emitting layer 36, and a portion of the first semiconductor layer 34 are immersed in the soft insulating layer 42. . After the soft insulating layer 42 is cured, the pressure is released, and at this time, the conductive particles 44 tend to recover deformation. Since the thickness of the bonding layer 40 is reduced, the space of the rebound of the conductive particles 44 is compressed and the original shape cannot be completely restored, so that the conductive particles 44 are pressed against each other during the recovery deformation, thereby being closely connected together. It is kept continuous in the thickness direction along the bonding layer 40. Preferably, the final shape variable of the conductive particles 44 is preferably greater than 40%, thereby providing the bonding layer 40 with better vertical conductivity. The first electrode 31 of the luminescent wafer 30 is electrically connected to the first conductive layer 24 of the susceptor 20 through the conductive particles 44 located directly below it, and the second electrode 33 passes through the conductive particles 44 directly under it and the second conductive portion of the susceptor 20 Layer 26 is conductive to effect electrical connection between luminescent wafer 30 and susceptor 20.

Since the light-emitting wafer 30 and the susceptor 20 are bonded by the flexible insulating layer 42, the internal stress caused by the bending of the susceptor 20 can be canceled, thereby preventing the detachment of the luminescent wafer 30 from the susceptor 20. Moreover, since the conductive insulating layer 44 is also doped with the conductive particles 44, the electrical connection between the luminescent wafer 30 and the susceptor 20 can be ensured, so that current can enter the illuminating from the first conductive layer 24 and the second conductive layer 26. The inside of the wafer 30 drives the light-emitting layer 36 to emit light.

It can be understood that when the illuminating wafer 30 is provided with a vertical conduction type structure (ie, the first electrode 31 and the second electrode 33 are respectively located at the bottom and the top of the illuminating wafer 30, and the first electrode is usually replaced by a conductive substrate), Only one of the electrodes needs to be connected to the conductive layer of the susceptor 20 by the bonding layer 40, and the other electrode may be connected to another conductive layer of the susceptor 20 through a wire (not shown).

It will also be appreciated that with the substrate 32 of the luminescent wafer 30 removed, the top surface of the first semiconductor layer 34 will be exposed. At this time, the top surface of the first semiconductor layer 34 may be roughened by etching or the like to form a rough surface. Thereby, the light emitted from the light-emitting layer 36 can be emitted from the rough surface of the first semiconductor layer 34 with a greater probability, thereby improving the light-emitting efficiency of the light-emitting chip 30.

In summary, the present invention complies with the requirements of the invention patent and submits a patent application according to law. The above description is only the preferred embodiment of the present invention, and equivalent modifications or variations made by those skilled in the art will be included in the following claims.

10. . . Illuminated wafer combination

20. . . Pedestal

twenty two. . . Base

twenty four. . . First conductive layer

26. . . Second conductive layer

30. . . Light emitting chip

31. . . First electrode

32. . . Substrate

33. . . Second electrode

34. . . First semiconductor layer

340. . . region

36. . . Luminous layer

38. . . Second semiconductor layer

40. . . Bonding layer

42. . . Soft insulation

44. . . Conductive particle

1 shows a light emitting wafer assembly in accordance with an embodiment of the present invention.

2 is a manufacturing process of the illuminating wafer assembly of FIG. 1.

10. . . Illuminated wafer combination

20. . . Pedestal

twenty two. . . Base

twenty four. . . First conductive layer

26. . . Second conductive layer

30. . . Light emitting chip

31. . . First electrode

32. . . Substrate

33. . . Second electrode

34. . . First semiconductor layer

340. . . region

36. . . Luminous layer

38. . . Second semiconductor layer

40. . . Bonding layer

42. . . Soft insulation

44. . . Conductive particle

Claims (10)

An illuminating wafer assembly includes a flexible pedestal and a luminescent wafer mounted on the susceptor, the illuminating wafer comprising a first semiconductor layer, a luminescent layer, a second semiconductor layer and an electrode stacked in sequence, the improvement being that the electrode is doped with conductivity A soft insulating layer of particles is bonded to the pedestal, and the conductive particles conduct the electrodes to the pedestal. The illuminating wafer assembly of claim 1, wherein the second semiconductor layer and the luminescent layer are embedded in the flexible insulating layer. The luminescent wafer assembly of claim 1, wherein the conductive particles are elastic nickel-plated resin balls. The luminescent wafer assembly of claim 1, wherein the conductive particles are pressed against each other along a thickness direction of the flexible insulating layer. A method of manufacturing a light emitting wafer assembly, comprising:
Providing a flexible base and a light emitting chip, the light emitting chip comprising a first semiconductor layer, a light emitting layer, a second semiconductor layer and an electrode stacked in sequence;
Coating a soft insulating layer containing conductive particles on the susceptor;
Laying the luminescent wafer on the flexible insulating layer to bring the electrode into contact with the soft insulating layer;
Pressure is applied to bring the luminescent wafer closer to the substrate until the electrodes are electrically connected to the pedestal through the conductive particles. The method of claim 5, wherein the soft insulating layer is further heated during the application of the pressure until the soft insulating layer is cured into a gel to release the pressure. The method of claim 6, wherein the conductive particles are deformed during the application of the pressure, and the partial deformation is restored after the pressure is released to be pressed against each other along the thickness direction of the soft insulating layer. The method of claim 7, wherein the shape variable of the conductive particles after the deformation of the restored portion is still greater than 40%. The method of claim 6, wherein the second semiconductor layer and the light-emitting layer are both embedded in the flexible insulating layer after the soft insulating layer is cured. The method of claim 5, wherein the conductive particles are nickel-plated resin balls.