TW201322523A - Manufacturing method of flexible light-emitting module - Google Patents

Abstract

The present invention relates to a manufacturing method of flexible light-emitting module, mainly comprising the following steps: coating the photo-curing glue on the flexible substrate to provide for the adhesion of the light-emitting chip, additionally coating conductive glue on the positive/negative electrodes of the light-emitting chip for bonding to the conducting wire of the flexible substrate, and subsequently carrying out heating under a predetermined temperature for the flexible substrate together with the light-emitting chip, wherein the predetermined temperature needs to be simultaneously lower than the thermal deformation temperature and the glass transition temperature of the flexible substrate, or carrying out an irradiation treatment for the flexible substrate together with the light-emitting chip to cure the conductive glue, in order to complete the production of the flexible light-emitting module. Thus, the manufacturing method of the present invention does not need the high-temperature curing treatment in order to avoid damage to the structure of the flexible substrate, while avoiding the use of the wire bonding pattern to achieve the purpose of reducing the module volume.

Description

Method for manufacturing flexible light emitting module

The invention relates to a light-emitting module, and in particular to a method for manufacturing a flexible light-emitting module.

Light-Emitting Diode (LED) is a principle that uses electric energy to directly convert into light energy. Voltage is applied to the positive and negative electrodes of the diode. When electrons and holes are injected into the semiconductor layer, they are combined inside the luminescent material. When the luminescent material is excited and then transitions back to the ground state energy level, the energy is released in the form of light, and different wavelengths of light can be released depending on the luminescent material. Since the LED element is different from the general bulb and needs to operate at a high temperature of more than 3 kilowatts, it does not have to use a high voltage to excite the electron beam like a fluorescent lamp, so its service life is longer than that of a conventional light source. However, in practical applications, the high resistance value of the transparent electrode is generated for the light transmissiveness of the light-emitting surface of the component, and a voltage gradient is formed at different local electrodes, so that the current density needs to be increased to avoid uneven illumination; After the package is encapsulated, it is more necessary to face the test of the heat dissipation efficiency of the thermal power generated by the operating current. Otherwise, the high temperature effect causes the luminescent material to deteriorate and the component life is reduced.

Therefore, in the current manufacturing method of the LED component module, the surface mount packaging technology needs to wire the component electrode through the wire bond to the carrier substrate; however, for circuit space considerations, or even to prevent The high thermal current of the leads at the high current density results in a reduction in the life of the components, which is generally more commonly applied in flip-chip package technology. The LED chips are mainly inverted to make the die pads set. The bonding ball is reflowed and heat-pressed on a hard substrate (such as a ceramic heat-dissipating substrate or a metal heat-conducting substrate), so that the LED module has the advantages of high heat dissipation and high power operation, thus becoming The mainstream packaging technology of LED modules. However, due to the heavy weight of the rigid substrate and the lack of flexibility, the products that can be applied to the LED module using the rigid substrate are easily limited, and the current industry has gradually adopted the trend that the electronic products are becoming increasingly thin and portable. A flexible substrate replaces the rigid substrate as a carrier substrate for the LED wafer.

Under various cost considerations, plastic becomes the most commonly used material for flexible substrates, but the plastic itself has the problem of heat resistance. Therefore, when the LED module using the plastic substrate is heated, the heating temperature exceeds the thermal deformation temperature of the plastic substrate ( Heat deflection temperature (HDT) or glass transition temperature (Tg), it is inevitable to cause irreversible changes or damage (such as shrinkage or warping deformation) on the physical properties of the plastic substrate or even the mechanical structure. Therefore, LED modules using plastic substrates are not suitable for manufacturing in a conventional flip chip package, because the package contacts provided by the die pads are required to be reflowed, whether they are conductive materials such as gold, silver or tin. The high temperature melting point almost exceeds the heat distortion temperature and glass transition temperature of common plastic materials (such as PET, PMMA or PES). Therefore, the high temperature of the crystallizing hot pressing process must also act on the plastic substrate, which also causes physical properties on the plastic substrate. Changes or damage to the mechanical structure. Even if the research and development and characteristics of the process of flexible LED light panels (published on August 27, 2011) discussed by Chen Wenzhao and others in the National Engineering Department of the Department of Materials Engineering in 2006, the system was revealed Conductive silver glue is arranged on the electrode of the element, so that the electrode of the element is directly facing the line on the flexible substrate, and the conductive silver glue is heated and cured to adhere to each other; however, the conductive silver glue is liquid-viscous at normal temperature, and must pass through about 150 degrees Celsius. The high temperature heating can achieve the effect of complete curing. If the heating temperature is insufficient and the touch is slight, the component electrode and the substrate line will be misaligned, but the high temperature required for complete curing limits the application of most plastic materials, especially PET. The softer plastic material with more deformation characteristics, the heat distortion temperature or the glass transition temperature is only about 100 degrees Celsius or even lower.

In order to avoid the influence of the high-temperature module process on the plastic substrate, the LED module packaging process applied to the flexible substrate generally adheres to the die pad and the substrate line by the surface bonding and other packaging technology; the Taiwanese M403720 patent For example, a "soft-plate type light-emitting diode display device" disclosed in the present invention has the main technical feature of achieving electrical connection between the light-emitting diode element and the PET substrate by conventional wire bonding, although the patent may Avoiding high-temperature thermal curing, but it is subject to the high thermal power of the lead, which leads to the disadvantage of the old packaging technology, which reduces the life of the component, so that the current power of the LED component applied to the flexible substrate can only be specified to low-power operating conditions. And the overall manufacturing process is quite time consuming, and it is also affected by the number of pins, so that the LED module has a considerable volume after the completion of manufacturing.

In view of this, the inventors of the present invention have been working to improve the above disadvantages to provide a suitable manufacturing method for manufacturing a flexible light-emitting module.

The main object of the present invention is to provide a method for manufacturing a flexible light-emitting module, which does not need to be subjected to high-temperature curing treatment, and can effectively reduce the volume of the module.

In order to achieve the above object, the first manufacturing method of the present invention comprises the steps of: a) laying a conductive paste on each of the positive and negative electrodes on the same surface of a light-emitting chip; b) forming a relative surface on one of the flexible substrates. a second wire; c) laying a photo-curable adhesive between the two wires of the flexible substrate; d) bonding the light-emitting chip to the flexible substrate through the photo-curable adhesive, and illuminating the conductive paste The positive and negative electrodes of the wafer are bonded to the two wires of the flexible substrate; e) the photocurable adhesive is photo-cured to be cured to fix the luminescent wafer to the flexible substrate; and f) The flexible substrate is thermally cured together with the illuminating wafer at a predetermined temperature to cure each of the conductive pastes, and the predetermined temperature is simultaneously lower than the heat distortion temperature and the glass transition temperature of the flexible substrate.

In the first manufacturing method of the present invention, the method further comprises a step g) of covering a photocurable adhesive on the luminescent wafer, and then pressing the surface of the photocurable adhesive with a mold, and then illuminating the photocurable adhesive. And curing the mold, and finally removing the mold; further, before covering the photo-curable adhesive, the light-emitting chip may be further disposed with at least one light-curing adhesive between the position of the positive and negative electrodes and the flexible substrate, and The photocurable adhesive between the luminescent wafer and the flexible substrate is subjected to an illuminating treatment to cure to form a reinforcing layer, thereby reinforcing the fixing of the luminescent wafer.

In the first manufacturing method of the present invention, the flexible substrate is made of a plastic material and has a Flexural Strength of less than 200 MPa according to the ASTM test specification, wherein PET, PMMA or PES is the best material.

In order to achieve the above object, the second manufacturing method of the present invention comprises the following steps: a) coating a surface of a hard carrier with a photocurable adhesive and performing an illumination treatment to form a substrate having flexibility; b) forming two opposite wires on the surface of the substrate; c) laying a photocurable adhesive between the two wires; d) laying a conductive paste on the positive and negative electrodes on the same surface of a light-emitting chip; e) Bonding the light-emitting chip to the substrate through the photo-curable adhesive, and bonding the positive and negative electrodes of the light-emitting chip to the two wires by using the conductive paste; f) the hard carrier plate together with the light-emitting layer The wafer is subjected to an illumination treatment to cure the photocurable adhesive and each of the conductive adhesive; and g) the hard carrier is removed.

In the second manufacturing method of the present invention, before removing the hard carrier, a photo-curable adhesive may be coated on the luminescent wafer, and then the photo-curable adhesive covering the luminescent wafer is irradiated to cure. A protective layer is formed to provide good protection of the luminescent wafer.

In the second manufacturing method of the present invention, before the photocurable adhesive is subjected to the illuminating treatment, the surface of the photocurable adhesive may be pressed by a mold, and then cured to form the protective layer by illuminating, and then Remove the mold.

In the second manufacturing method of the present invention, the hard carrier may be made of glass, and the surface may be cleaned before being coated with the photocurable adhesive.

According to the above description, the manufacturing method of the present invention can complete the curing of the conductive adhesive without high temperature, so as to avoid the structure of the flexible substrate being damaged by high temperature, and avoiding the use of the wire bonding method to effectively reduce the flexible type. The volume of the lighting module.

In order to explain the steps, features and functions of the present invention in detail, the following two preferred embodiments are described below with reference to the drawings.

Referring to FIG. 1 , a method for manufacturing a flexible light emitting module 30 according to a first preferred embodiment of the present invention includes the following steps: Step a): providing an illuminating wafer 10 and the same surface of the illuminating wafer 10 There are two positive and negative electrodes 12 at the edges. In order to make the two electrodes 12 have better insulation separation, the two electrodes 12 can be respectively disposed at two opposite corners, as long as they are located on the same surface of the light-emitting chip 10. The conductive paste 14 is mainly disposed on the positive and negative electrodes 12 of the luminescent wafer 10, and the conductive adhesive 14 is mainly composed of a conductive material having high conductivity and an insulating rubber material having heat curing or photocuring properties. For example, but not limited to conductive silver paste.

Step b): forming a pair of opposite wires 18 on a surface of one of the flexible substrates 16 by metal plating such as sputtering or evaporation, and each of the wires 18 has a conductive portion 182 at one end or from a portion. The flexible substrate 16 is a plastic material having high flexibility, that is, a flexural strength of less than 200 MPa according to the ASTM test specification, and such as polyethylene terephthalate (PET). Or Polymethylmethacrylate (PMMA) has an optimum material for bending strength close to or even less than 100 MPa; the wire 18 is made of a conductor such as Indium tin oxide (ITO) or metal. The material, of course, if the flexible substrate 16 is made of a material having light transmissivity, the conductive light-emitting material can be formed by a transparent conductive material such as indium tin oxide or a transparent metal formed by a thin film process. It has the characteristics of double-sided illumination.

Step c): laying a photocurable adhesive 20 between the conductive portions 182 of the two wires 18 of the flexible substrate 16, such as but not limited to UV glue made of acrylic material or epoxy material.

Step d): aligning the electrodes 12 of the illuminating wafer 10 and the electrodes 12 to the conductive portions 182 of the two wires 18 of the flexible substrate 16 respectively, and the positive and negative electrodes 12 of the luminescent wafer 10 are viscous by the adhesion of the conductive pastes 14 The conductive portion 182 of the flexible substrate 16 is bonded together.

Step e): The photocurable adhesive 20 is subjected to an illuminating treatment to be cured to fix the luminescent wafer 10 to the flexible substrate 16.

Step f): The flexible substrate 16 is thermally cured at a predetermined temperature together with the luminescent wafer 10 to cure the conductive paste 14 between the positive and negative electrodes 12 of the luminescent wafer 10 and the wires 18 of the flexible substrate 16. The predetermined temperature for performing the heat curing treatment is lower than the heat deflection temperature (HDT) and the glass transition temperature (Tg) of the flexible substrate 16, for example, if the material of the flexible substrate 16 is PET, The HDT of PET is 80 ° C ~ 100 ° C (under the load of ASTM D648 thermal deformation measurement of 1820 KPa), and the Tg of PET is 79 ° C, therefore, the predetermined temperature required for thermal curing must be lower than 79 °C does not cause structural damage to the flexible substrate 16.

Step g): at the other edge of the illuminating wafer 10 different from the positive and negative electrodes 12, for example, at the other two opposite corners, a photocuring adhesive 22 is respectively disposed, and the photocurable adhesive 22 is injected into the side of the luminescent wafer 10 and the flexible substrate. Between the 16 and the photo-curing adhesive 22, the photo-curing adhesive 22 is cured to form a reinforcing layer for increasing the fixing effect of the luminescent wafer 10, and then covering another photo-curing adhesive 24 (such as UV glue) on the luminescent wafer 10. Then, a mold 26 is used to press the surface of the photocurable adhesive 24. If the photocurable adhesive 24 is more viscous and the mold 26 is pressed, the photocurable adhesive 24 may be briefly illuminated, but it is not necessarily necessary. The mold 26 may be made of polydimethyl siloxane (PDMS) having a microstructured surface 262 that structuring or planarizing the surface of the photocurable adhesive 24, and then illuminating the photocurable adhesive 24 The process is cured to form a protective layer for protecting the luminescent wafer 10. The surface of the photocurable adhesive 24 is flat after being pressed by the mold 26 or complementary to the microstructured surface 262 of the mold 26, and finally the mold is removed. 26, whereby the manufacture of the flexible light module 30 is completed. It is worth mentioning that the surface 262 of the mold 26 in contact with the photo-curing adhesive 24 can be made into a zigzag shape, and the surface of the photo-curable adhesive 24 is jagged after being pressed by the mold 26, as shown in the second figure, so that the light-emitting chip is made. When the generated light passes through the sawtooth surface 242 of the photocurable adhesive 24, the scattering effect can be generated to improve the luminous efficiency of the light-emitting wafer 10.

In addition, referring to the third figure, a manufacturing method of the flexible lighting module 60 according to the second preferred embodiment of the present invention includes the following steps: Step a): providing a rigid carrier 40, a rigid carrier 40 The material is hereby exemplified by glass. After cleaning the surface of the hard carrier 40 with acetone, isopropyl alcohol and deionized water, a light-curing adhesive is uniformly applied on the cleaned surface (for example, acrylic material). Or a UV glue made of an epoxy resin material, and subjected to an illuminating treatment to form a planarized substrate 42.

Step b): forming two opposing wires 44 on the surface of the substrate 42 by metal plating such as sputtering or evaporation, and each of the wires 44 has a conductive portion 442 extending at one end or from a portion. The wire 44 is made of a material such as indium tin oxide (ITO) or a metal. Of course, if the photocurable adhesive is made of a light transmissive material, it can be transparent such as indium tin oxide. The conductive material or the transparent metal formed by the thin film process forms the wire 44, so that the flexible light emitting module 60 has the characteristics of double-sided light emission.

Step c): laying a photocurable adhesive 46 between the conductive portions 442 of the two wires 44, such as but not limited to UV glue made of acrylic material or epoxy resin material.

Step d): providing an illuminating wafer 50 having opposite positive and negative electrodes 52 at the edge of the same surface of the illuminating wafer 50. In order to provide better insulation separation between the two electrodes 52, the two electrodes 52 may be respectively disposed on the two electrodes 52. The conductive paste 54 is mainly disposed on the positive and negative electrodes 52 of the light-emitting chip 50, and the conductive paste 54 is mainly made of a conductive material having high conductivity, as long as it is located on the same surface of the light-emitting chip 50. The particles are mixed with an insulating rubber material having heat curing or photocuring properties such as, but not limited to, a conductive silver paste.

Step e): bonding the luminescent wafer 50 to the substrate 42 through the photo-curing adhesive 46, and bonding the positive and negative electrodes 52 of the luminescent wafer 50 to the conductive portions 442 of the two wires 44 by the adhesion of the conductive paste 54 together.

Step f): The hard carrier 40 is irradiated with the luminescent wafer 50 to cure the photocurable adhesive 46 and the conductive paste 54 for fixing the luminescent wafer 50 to the substrate 42.

Step g): covering a light-curing adhesive 48 on the light-emitting wafer 50, and then photo-curing the photo-curable adhesive 48 covering the light-emitting chip 50 to cure it to form a protective layer, which can be provided as in the above first preferred embodiment. The surface of the photo-curable adhesive 48 is structured or planarized by a mold 26 made of PDMS to protect the light-emitting wafer 50 and to cause an atomization effect to cause scattering phenomenon when the light generated by the light-emitting chip 50 passes. The luminous efficiency of the light-emitting chip 50 is increased, and finally the hard carrier 40 is removed, thereby completing the manufacture of the flexible light-emitting module 60.

According to the above two embodiments, the manufacturing method of the present invention can complete the curing of the conductive adhesive without high temperature, and can effectively prevent the structure of the flexible substrate from being damaged by high temperature, and can also avoid the use of the wire bonding method to reduce the flexible illumination. The volume of the module is such that the object of the invention is achieved.

Finally, it is to be noted that the constituent elements disclosed in the foregoing embodiments are merely illustrative and are not intended to limit the scope of the present invention, and alternative or variations of other equivalent elements should also be the scope of the patent application of the present application. Covered.

"First Embodiment"

10. . . Light emitting chip

12. . . electrode

14. . . Conductive plastic

16. . . Flexible substrate

18. . . wire

182. . . Conductive part

20,22,24. . . Light curing adhesive

242. . . Serrated surface

26. . . Mold

262. . . surface

30. . . Flexible light module

"Second embodiment"

40. . . Hard carrier

42. . . Substrate

44. . . wire

442. . . Conductive part

46,48. . . Light curing adhesive

50. . . Light emitting chip

52. . . electrode

54. . . Conductive plastic

60. . . Flexible light module

The first figures A to B are flowcharts of the first preferred embodiment of the present invention.

The second figure is a schematic diagram mainly showing that the surface of the photocurable adhesive is sawtoothed after being pressed by the mold.

3A to B are flow charts of a second preferred embodiment of the present invention.

10. . . Light emitting chip

12. . . electrode

14. . . Conductive plastic

16. . . Flexible substrate

18. . . wire

182. . . Conductive part

20,22. . . Light curing adhesive

Claims (15)

1. A method for manufacturing a flexible light-emitting module, comprising the steps of: a) laying a conductive adhesive on each of the positive and negative electrodes on the same surface of a light-emitting chip; b) forming a relative surface on one surface of a flexible substrate a light-curing adhesive is disposed between the two wires of the flexible substrate; d) the light-emitting chip is adhered to the flexible substrate through the light-curable adhesive, and the light-emitting chip is The positive and negative electrodes are bonded to the two wires of the flexible substrate; e) curing the photocurable adhesive to fix the luminescent wafer to the flexible substrate; and f) the flexible substrate The conductive paste is cured together with the luminescent wafer at a predetermined temperature, and the conductive paste is cured at a temperature lower than the thermal deformation temperature and the glass transition temperature of the flexible substrate.
2. The manufacturing method of claim 1, further comprising a step g) of covering a photocurable adhesive on the luminescent wafer, and then pressing a surface of the photocurable adhesive with a mold, and then illuminating the photocurable adhesive. It is allowed to cure and then the mold is removed.
3. The manufacturing method of claim 2, wherein before the step of gapping the photocurable adhesive on the luminescent wafer, at least the position of the luminescent wafer different from the positive and negative electrodes and the flexible substrate is at least A photocurable adhesive is obtained, and the photocurable adhesive between the luminescent wafer and the flexible substrate is subjected to an illuminating treatment to cure to form a reinforcing layer.
4. The manufacturing method according to claim 2, wherein the surface of the photocurable adhesive is flat after being pressed by the mold.
5. The manufacturing method according to claim 2, wherein the surface of the photocurable adhesive is serrated after being pressed by the mold.
6. The manufacturing method according to claim 4 or 5, wherein the mold is a microstructured mold made of polydimethyl siloxane (PDMS).
7. The manufacturing method according to claim 1, wherein the flexible substrate is made of a plastic material and has a Flexural Strength of less than 200 MPa according to the ASTM test specification.
8. The manufacturing method of claim 7, wherein the flexible substrate is made of polyethylene terephthalate (PET) or polymethylmethacrylate (PMMA).
9. The manufacturing method according to claim 1, wherein each of the wires is made of a conductor such as indium tin oxide (ITO) or a metal.
10. A method for manufacturing a flexible light-emitting module, comprising the steps of: a) coating a surface of a hard carrier with a light-curing adhesive and performing photo-processing to form a planarized substrate; b) The surface of the substrate forms opposite wires; c) a photo-curable adhesive is disposed between the two wires; d) a conductive paste is respectively disposed on the positive and negative electrodes on the same surface of a light-emitting chip; e) the light is emitted The wafer is bonded to the substrate through the photocurable adhesive, and the positive and negative electrodes of the light emitting chip are bonded to the two wires by each of the conductive paste; f) the hard carrier is illuminated together with the light emitting chip Processing, curing the photocurable adhesive and each of the conductive adhesive; and g) removing the hard carrier.
11. The manufacturing method of claim 10, wherein the step g) is performed by coating a photocurable adhesive on the luminescent wafer before removing the hard carrier, and then illuminating the photocurable adhesive covering the luminescent wafer. It cures to form a protective layer.
12. The manufacturing method according to claim 11, before the photocurable adhesive is subjected to the illuminating treatment, the surface of the photocurable adhesive is pressed by a mold, and then cured to form the protective layer by illuminating, and then removed. The mold.
13. The manufacturing method according to claim 10, wherein each of the wires is made of a conductor such as indium tin oxide (ITO) or a metal.
14. The manufacturing method of claim 10, wherein the hard carrier is made of glass.
15. The method of claim 14, wherein the surface of the rigid carrier of step a) is first cleaned and then coated with the photocurable adhesive.