CN110145698B

CN110145698B - LED bulb lamp with organic silicon modified polyimide resin composition as filament base layer

Info

Publication number: CN110145698B
Application number: CN201910400938.5A
Authority: CN
Inventors: 江涛; 徐卫洪; 斎藤幸广; 鳗池勇人; 熊爱明; 徐俊锋
Original assignee: Jiaxing Super Lighting Electric Appliance Co Ltd
Current assignee: Jiaxing Super Lighting Electric Appliance Co Ltd
Priority date: 2018-05-23
Filing date: 2019-05-15
Publication date: 2020-09-25
Anticipated expiration: 2039-05-15
Also published as: CN110145698A; CN110081323A; CN110081323B

Abstract

An LED bulb lamp comprises a lamp shell, wherein inert gas is filled in the lamp shell; the lamp holder is connected with the lamp shell; the core column is connected with the lamp holder and is positioned in the lamp shell, and the core column is provided with a vertical rod vertically extending to the center of the lamp shell; LED filament encircles the pole setting and is located the lamp body, LED filament includes: the LED comprises a plurality of LED sections, a plurality of LED sections and a plurality of LED modules, wherein each LED section comprises at least two LED chips which are electrically connected with each other, and the shortest distance between the two LED chips which are respectively positioned in the two adjacent LED sections is greater than the distance between the two adjacent LED chips in the LED sections; the conductor section is positioned between two adjacent LED sections and comprises a conductor connecting the two adjacent LED sections; the electrode is electrically connected with the LED section; and the light conversion layer is coated on at least two sides of the LED chip or the electrode and exposes a part of the electrode, the light conversion layer at least comprises a top layer and a base layer, the top layer and the base layer are respectively positioned on two sides of the LED chip or the electrode, and the base layer is formed by coating and drying the organic silicon modified polyimide resin composition.

Description

LED bulb lamp with organic silicon modified polyimide resin composition as filament base layer

Technical Field

The invention relates to the field of illumination, in particular to an LED bulb lamp taking an organic silicon modified polyimide resin composition as a filament base layer.

Background

Incandescent light bulbs have been widely used for decades for illumination in homes and businesses, however, incandescent light bulbs are generally less efficient in their energy usage, with approximately 90% of the energy input going to be dissipated as heat. And because incandescent bulbs have a very limited life (about 1,000 hours), they need to be replaced often. These conventional lamps are gradually replaced by other more efficient lamps, such as fluorescent lamps, high intensity discharge lamps, Light Emitting Diodes (LEDs), etc. Among these lamps, LED lamps are the most attractive lighting technology. The LED lamp has the advantages of long service life, small volume, environmental protection and the like, so the application of the LED lamp is continuously increased.

In recent years, an LED bulb lamp with an LED filament is available on the market. The LED bulb lamp using the LED filament as a luminous source in the market at present still has the following problems to be improved:

first, an LED hard filament is used having a substrate (e.g., a glass substrate) and a plurality of LED chips on the substrate. However, the lighting effect of the LED bulb lamp can be better only by combining a plurality of hard filaments, and the lighting effect of a single hard filament cannot meet the general demand in the market. Traditional ball bubble lamps and lanterns have the tungsten filament, can produce even light-emitting because the nature of the nature bendable of tungsten filament, however the effect of this kind of even light is difficult to reach to the hard filament of LED. There are many reasons why it is difficult to achieve this effect for the LED filament, except for the foregoing inflexibility, one of them is that the substrate can block the light emitted by the LED, and the light generated by the LED is a point light source, which can lead to light concentration. In contrast, a uniform light distribution results in a uniform illumination effect, while a concentrated light distribution results in an uneven and concentrated illumination effect.

In addition, there is also a soft filament of LED, which is similar to the above filament structure, and the glass substrate is partially replaced by a flexible substrate (hereinafter referred to as FPC), so that the filament can have a certain degree of bending. However, the soft filament made of the FPC has a thermal expansion coefficient different from that of the silica gel coating the filament, and the displacement and even the degumming of the LED chip are caused by long-term use; or the FPC is not favorable for flexible change of the process conditions and the like. In addition, the stability of the metal routing between the chips of the filament structure during bending is challenged, when the chips in the filament are arranged compactly, if the adjacent LED chips are connected in a metal routing mode, the stress is easily concentrated on the specific part of the filament due to the bending of the filament, so that the metal routing for connecting the LED chips is damaged or even broken,

in addition, the LED filament is generally disposed in the LED bulb, and in order to present an aesthetic feeling in appearance and to make an illumination effect of the LED filament more uniform and wide, the LED filament may be bent to present various curves. However, the LED filament has LED chips arranged therein, and the LED chips are relatively hard objects, so that the LED filament is difficult to bend into a desired shape. Further, the LED filament is also prone to cracking due to stress concentration during bending.

The existing LED bulb lamp is provided with a plurality of LED lamp filaments in order to increase aesthetic feeling in appearance and enable illumination effect to be more uniform, and the LED lamp filaments are set to be different placing angles. However, since a plurality of LED filaments need to be installed in a single LED bulb, and the LED filaments need to be individually fixed, the manufacturing process is more complicated, and the production cost is increased.

Patent No. CN202252991U discloses that the upper and lower surfaces of a chip or the periphery thereof are coated with fluorescent powder respectively, the chip is fixed on a flexible PCB and is bonded and packaged by an insulating glue, the insulating glue is epoxy resin glue; the electrodes of the chip are connected with the circuit on the flexible PCB board through gold wires; the flexible PCB board is transparent or semitransparent, and the flexible PCB board is printed circuit preparation on polyimide or polyester film base plate and forms, adopts the flexible PCB board to replace aluminium base board support lamp radiating part, improves the heat dissipation. Patent publication No. CN105161608A discloses an LED filament light-emitting strip and a manufacturing method thereof, in which non-overlapping chip light-emitting surfaces are arranged in a face-to-face manner, so as to improve light-emitting uniformity and heat dissipation. Patent publication No. CN103939758A discloses that a transparent and heat-conducting heat dissipation layer is formed between the bearing surface of the carrier and the bonding surface of the LED chip for heat exchange with the LED chip. The aforesaid patent adopts PCB board, adjustment chip to arrange or form the heat dissipation layer respectively, though can improve the filament heat dissipation to a certain extent, nevertheless because of the radiating efficiency is low, and the heat is easy to be gathered. Finally, patent publication No. CN204289439U discloses a full-circle light-emitting LED filament, which includes a substrate mixed with phosphor, electrodes disposed on the substrate, at least one LED chip mounted on the substrate, and a packaging adhesive covering the LED chip. Through the base plate that contains the silicone resin of phosphor powder formed, avoided glass or sapphire as the cost of base plate, use the filament of base plate preparation has avoided glass or sapphire to the influence of chip light-emitting, has realized 360 degrees light-emitting, and light-emitting homogeneity and light efficiency improve greatly. However, the substrate is formed of silicone resin, which has a disadvantage of poor heat resistance.

Disclosure of Invention

It is specifically noted that the present disclosure may actually encompass one or more inventive aspects that may or may not have been presently claimed, and that several of the inventive aspects that may be present herein may be collectively referred to as "the invention" during the course of writing the description to avoid obscuring the unnecessary distinction between such possible inventive aspects.

This summary describes many embodiments relating to the "invention". The term "present invention" is used herein to describe only some embodiments disclosed in the specification (whether or not in the claims), and not a complete description of all possible embodiments. Certain embodiments of various features or aspects described below as "the invention" may be combined in different ways to form an LED bulb or portion thereof.

According to another embodiment of the invention, an LED bulb is disclosed, comprising:

the lamp shell is filled with inert gas;

the lamp holder is connected with the lamp shell;

the core column is connected with the lamp cap and is positioned in the lamp shell, and the core column is provided with a vertical rod vertically extending to the center of the lamp shell;

LED filament encircles the pole setting just is located in the lamp body, LED filament includes:

the LED comprises a plurality of LED sections, each LED section comprises at least two LED chips which are electrically connected with each other, and the shortest distance between the two LED chips respectively positioned in the two adjacent LED sections is greater than the distance between the two adjacent LED chips in the LED sections;

the conductor section is positioned between two adjacent LED sections and comprises a conductor connecting the two adjacent LED sections;

the electrode is electrically connected with the LED section; and

a light conversion layer coated on at least two sides of the LED chip or the electrode and exposing a part of the electrode, wherein the light conversion layer at least has a top layer and a base layer, the top layer and the base layer are respectively positioned on two sides of the LED chip or the electrode, the base layer is formed by coating and drying an organic silicon modified polyimide resin composition, the composition comprises an organic silicon modified polyimide containing a repeating unit represented by the following general formula (I), a thermal curing agent, fluorescent powder and heat dissipation particles, and the thermal curing agent is epoxy resin, isocyanate or a bisoxazoline compound;

in the general formula (I), Ar1 is a 4-valent organic group with a benzene ring or an alicyclic hydrocarbon structure, Ar2 is a 2-valent organic group, R is independently selected from methyl or phenyl, and n is 1-5;

in a space rectangular coordinate system XYZ, a Z axis is parallel to the core column, and the total length of the projection of the LED filament on an XY plane is a length L1; the total length of the projection on the YZ plane is length L2; the total length of projection on the XZ plane is length L3, length L1: length L2: length L3 equals 1: 0.5-1: 0.6 to 0.9;

the spectrum of the LED bulb lamp has three peaks P1, P2 and P3, wherein the peak P1 is between 430nm and 480nm in wavelength, the peak P2 is between 580nm and 620nm in wavelength, the peak P3 is between 680nm and 750nm in wavelength, the intensity of the peak P1 is smaller than that of the peak P2, and the intensity of the peak P2 is smaller than that of the peak P3.

Due to the adoption of the technical scheme, the invention can at least achieve one of the following beneficial effects or any combination thereof: (1) the filament can be bent and lightened, the falling probability of the lead is reduced, and the reliability of the product is improved; (2) the LED filament structure is divided into the LED section and the conductor section, so that stress is easily concentrated on the conductor section when the LED filament is bent, and the probability of breakage of gold wires connected with adjacent chips in the LED section is reduced when the gold wires are bent, so that the overall quality of the LED filament is improved; (3) the LED filament structure is designed through an ideal formula, so that the overall luminous efficiency can be improved; (4) an included angle exists between the conductor or a lead connecting the LED chip unit and the conductor and the length extension direction of the LED filament, so that the internal force on the sectional area of the conductor when the filament is bent can be effectively reduced, the probability of bending and breaking of the LED filament is reduced, and the overall quality of the LED filament is improved; (5) the organic silicon modified polyimide resin composition prepared by adding a thermal curing agent into organic silicon modified polyimide serving as a main body has excellent heat resistance, mechanical strength and light transmittance; the organic silicon modified polyimide resin composition is used as the filament base layer, and the filament has good flexibility, so that the filament presents various shapes, and 360-degree full-circumference illumination is realized; (6) the special spectrum design is different from the traditional LED spectrum distribution pattern, is more close to the spectrum distribution of the traditional incandescent light and the spectrum distribution of natural light, and improves the comfort of the human body to illumination.

Drawings

FIG. 1A is a schematic structural view of another embodiment of a segmented LED filament of the present invention;

FIGS. 1B-1J are schematic structural views of various embodiments of segmented LED filaments according to the present invention;

FIGS. 1K and 1L are schematic perspective views of another embodiment of a segmented LED filament of the present invention;

FIG. 1M shows a partial top view of FIG. 1L;

FIGS. 2A and 2B are schematic cross-sectional views of different embodiments of a filament;

FIG. 3 is a schematic view of an interface through which light emitted by an LED chip according to the present invention passes;

fig. 4A is a schematic cross-sectional view of the LED filament unit in the axial direction of the LED filament;

FIG. 4B is a schematic cross-sectional view of the LED filament unit in the radial direction of the LED filament;

FIG. 5 is a schematic cross-sectional view of various embodiments of a filament according to the present invention;

FIGS. 6A-6C are schematic top views of various embodiments of the present invention;

FIG. 7A is a schematic structural diagram of an embodiment of an LED filament layered structure according to the present invention;

FIG. 7B is a schematic diagram of a wire bonding structure of an LED chip according to an embodiment;

FIG. 8 is a graph showing a distribution of sizes of heat dissipating particles of different specifications;

FIG. 9A is a SEM image of a composite film of the silicone modified polyimide resin composition of the present invention;

FIGS. 9B and 9C are schematic cross-sectional views showing examples of composite films of silicone-modified polyimide resin compositions according to the present invention;

fig. 10A to 10D are a schematic diagram, a side view, another side view and a top view of an LED bulb according to an embodiment of the invention;

fig. 11A to 11D are a schematic diagram, a side view, another side view and a top view of an LED bulb according to an embodiment of the invention;

fig. 12 is a schematic diagram of an output light spectrum of an LED bulb according to an embodiment of the invention.

Detailed Description

The present disclosure provides a new LED filament and an LED bulb using the same, which will be described in the following embodiments with reference to the accompanying drawings. The following description of various embodiments of the present invention has been presented for the purposes of illustration and example only and is not intended to be exhaustive or limited to the precise forms disclosed. These example embodiments are merely examples, and many implementations and variations are possible that do not require the details provided herein. It should also be emphasized that this disclosure provides details of alternative examples, but that these alternative displays are not exclusive. Moreover, any agreement in detail between the various examples should be understood as requiring such detail as, after all, to be impractical for every possible variation of the feature set forth herein.

In the drawings, the size and relative sizes of components may be exaggerated for clarity. Like reference numerals refer to like elements throughout the drawings.

It will be understood that, although the terms first, second, third, etc. may be used herein to describe various components, members, regions, layers or steps, these components, members, regions, layers and/or steps should not be limited by these terms. Unless the context indicates otherwise, these terms are only used to distinguish one component, region, layer or step from another component, region, layer or step, e.g., as a naming convention. Thus, a first component, member, region, layer or step discussed below in one section of the specification can be termed a second component, member, region, layer or step in another section of the specification or in the claims without departing from the teachings of the present invention. Furthermore, in some cases, even if the terms "first", "second", and the like are not used in the specification to describe terms, the terms may be referred to as "first" or "second" in the claims to distinguish different components described from each other.

The

LED chip units

102 and 104, or referred to as

LED segments

102 and 104, may be a single LED chip, or two LED chips, or may include a plurality of LED chips, i.e., equal to or greater than three LED chips.

Referring next to fig. 1A to fig. 1G, fig. 1A is a schematic structural diagram of another embodiment of the segmented LED filament according to the present invention. As shown in fig. 1A, the LED filament 400 has: a light conversion layer 420;

LED segments

402, 404; the

electrodes

410, 412; and a conductor segment 430 for electrically connecting between two

adjacent LED segments

402, 404. The LED segments 402,404 include at least two LED chips 442 electrically connected to each other by wires 440. In the present embodiment, the conductor segment 430 includes a conductor 430a connecting the

LED segments

402 and 404, wherein the shortest distance between two LED chips 442 respectively located in two

adjacent LED segments

402 and 404 is greater than the distance between two adjacent LED chips in the LED segment 402/404, and the length of the conducting wire 440 is less than the length of the conductor 430 a. Therefore, the conductor segments are prevented from being broken by the stress generated when the two LED segments are bent. The light conversion layer 420 is coated on at least two sides of the LED chip 442/

electrodes

410, 412. The light conversion layer 420 exposes a portion of the

electrodes

410, 412. The light conversion layer 420 may have at least a top layer 420a and a bottom layer 420b as the upper layer and the lower layer of the filament, respectively, in this embodiment, the top layer 420a and the bottom layer 420b are located on two sides of the LED chip 442/the

electrodes

410 and 412, respectively. It should be noted that, the thickness, diameter or width of the top layer 420a in the LED segments 402,404 or the conductor segment 430 described in fig. 1A to 1M in the radial direction of the LED filament, or the thickness, diameter or width of the top layer of the LED segments 402,404 or the conductor segment 430 in the radial direction of the LED filament refers to the distance from the top surface of the top layer 420a in the LED segments 402,404 or the conductor segment 430 to the interface between the top layer 420a and the base layer 420b, or to the interface between the LED chip 442 or the conductor 430a and the base layer 420b, respectively, in the radial direction of the LED filament, and the top surface of the top layer 420a is a surface away from the base layer.

As shown in fig. 1B, in the present embodiment, the conductor segment 430 is also located between two

adjacent LED segments

402 and 404, and the LED chips 442 in the

LED segments

402 and 404 are electrically connected to each other through the wires 440. However, the conductor 430a in the conductor segment 430 of fig. 1B is not in the form of a wire, but in the form of a sheet or film. In some embodiments, conductor 430a may be a copper foil, gold foil, or other material that is electrically conductive. In the present embodiment, the conductor 430a is attached to the surface of the base layer 420b and adjacent to the top layer 420a, i.e. between the base layer 420b and the top layer 420 a. The conductor segment 430 and the

LED segments

402 and 404 are electrically connected by a wire 450, that is, the two LED chips 442 located in the two

adjacent LED segments

402 and 404 and having the shortest distance from the conductor segment 430 are electrically connected to the conductor 430a in the conductor segment 430 by the wire 450. Wherein the length of the conductor segment 430 is greater than the distance between two adjacent LED chips in the

LED segments

402 and 404, and the length of the wire 440 is less than the length of the conductor 430 a. Such a design ensures good bendability of the conductor segment 430. Assuming that the maximum thickness of the LED chip in the radial direction of the filament is H, the thickness of the electrode and the conductor in the radial direction of the filament is 0.5H to 1.4H, preferably 0.5H to 0.7H. Therefore, the wire bonding process can be implemented, the quality of the wire bonding process (namely, good strength) is ensured, and the stability of the product is improved.

As shown in fig. 1C, in this embodiment, both the LED segments 402,404 and the conductor segment 430 of the LED filament have different structural characteristics. In the present embodiment, the LED segments 402,404 and the conductor segment 430 have different widths, thicknesses or diameters in the radial direction of the LED filament. As shown in fig. 1C, the conductor segments 430 are thin relative to the LED segments 402,404, the conductor segments 430 serve as the primary bending portion when the LED filament is bent, and the thin conductor segments 430 help to be bent into a variety of curves. In this embodiment, the base layer 420b, whether in the LED segments 402,404 or in the conductor segment 430, is uniform in width, thickness or diameter in the radial direction of the LED filament; while the top layer 420a has a different width, thickness or diameter in the radial direction of the LED filament between the LED segments 402,404 and the conductor segment 430. As shown in fig. 1C, the top layer 420a of the LED segments 402,404 has the largest diameter D2 in the radial direction of the LED filament, and the top layer 420a of the conductor segment 430 has the largest diameter D1 in the radial direction of the LED filament, D2 being larger than D1. The diameter of the top layer 420a gradually decreases from the

LED segments

402 and 404 to the conductor segment 430, and then gradually increases from the conductor segment 430 to the

LED segments

402 and 404, so that the top layer 420a forms a smooth and concave curve along the axial direction of the LED filament.

As shown in fig. 1D, in the present embodiment, the top layer 420a of the

LED segments

402 and 404 has the largest diameter (or the largest thickness) in the radial direction of the LED filament, the diameter of the top layer 420a gradually decreases from the

LED segments

402 and 404 to the conductor segment 430, and a part (e.g., the middle part) of the conductor 430a is not covered by the top layer 420 a. And the base layer 420b is uniform in width, thickness or diameter in the radial direction of the LED filament, whether in the LED segments 402,404 or in the conductor segment 430. In this embodiment, the number of LED chips 442 in each LED segment 402,404 may be different, for example, there is only one LED chip 442 in one LED segment 402,404, and there are two or more LED chips 442 in one

LED segment

402, 404. In addition to the number of LED chips 442, the

LED segments

402, 402 may have different types of LED chips 442.

As shown in fig. 1E, in this embodiment, the top layer 420a, whether in the

LED segments

402 and 404 or the conductor segments 430, has a uniform width, thickness or diameter in the radial direction of the LED filament, and the base layer 420b may be recessed or hollowed out at least one conductor 430a, such that a portion (e.g., a middle portion) of at least one conductor 430a is not covered by the base layer 420b, and another at least one conductor 430a is completely covered by the base layer 420 b.

As shown in fig. 1F, in this embodiment, the top layer 420a has a uniform width, thickness or diameter in the radial direction of the LED filament, whether in the LED segments 402,404 or the conductor segments 430, and the base layer 420b is recessed or hollowed out at all of the conductors 430a, so that a portion (e.g., the middle portion) of each conductor 430a is not covered by the base layer 420 b.

As shown in fig. 1G, in the present embodiment, the top layer 420a of the

LED segments

402 and 404 has the largest diameter in the radial direction of the LED filament, the diameter of the top layer 420a gradually decreases from the

LED segments

402 and 404 to the conductor segment 430, and a part (e.g., the middle part) of the conductor 430a is not covered by the top layer 420 a. While base layer 420b is recessed or hollowed out at conductor 430a such that a portion (e.g., a middle portion) of conductor 430a is not covered by base layer 420 b. In other words, at least two opposite sides of the conductor 430a are not covered by the top layer 420a and the base layer 420b, respectively.

As described above with reference to the embodiments of fig. 1E to 1G, when the base layer 420b has recesses or hollows in some or all of the conductor segments 430, the recesses or hollows may also be in the form of slits or slits, i.e., to provide good flexibility of the conductor segments 430 without exposing the conductors 430 a.

As shown in fig. 1H, in the present embodiment, the conductor 430a is, for example, a conductive metal sheet or strip. Conductor 430a has a thickness Tc, and since LED chip 442 is thinner relative to conductor 430a, thickness Tc of conductor 430a is significantly greater than the thickness of LED chip 442. In addition, the thickness Tc of the conductor 430a is closer to the thickness of the top layer 420a in the conductor segment 430 than the thickness of the LED chip 442 (the thickness of the top layer 420a in the conductor segment 430 can refer to the diameter D1 of the top layer 420a in the radial direction), and Tc is (0.7-0.9) D1, preferably Tc is (0.7-0.8) D1. Also, in this embodiment, the thickness of the top layer 420a at the conductor segment 430 is consistent with the thickness of the LED segments 402,404 (the thickness of the top layer 420a at the LED segments 402,404 can refer to the diameter D2 of the top layer 420a in the radial direction).

As shown in fig. 1I, in the present embodiment, the thickness Tc of the conductor 430a is also significantly larger than the thickness of the LED chip 442, and the thickness Tc of the conductor 430a is closer to the thickness (diameter D1) of the top layer 420a at the conductor segment 430 than the thickness of the LED chip 442. Also, in this embodiment, the top layer 420a is not uniform in thickness between the conductor segment 430 and the

LED segments

402, 404. As shown in fig. 1I, the top layer 420a of the LED segments 402,404 has the smallest diameter D2 in the radial direction of the LED filament, and the top layer 420a of the conductor segment 430 has the largest diameter D1 in the radial direction of the LED filament, D1 being larger than D2. The diameter of the top layer 420a gradually increases from the

LED segments

402 and 404 to the conductor segment 430, and then gradually decreases from the conductor segment 430 to the

LED segments

As shown in fig. 1J, in the present embodiment, the thickness Tc of the conductor 430a is also significantly larger than the thickness of the LED chip 442, however, the top layer 420a of the

LED segments

402 and 404 has the largest diameter in the radial direction of the LED filament, the diameter of the top layer 420a is gradually reduced from the

LED segments

402 and 404 to the conductor segment 430, and a part (e.g., the middle part) of the conductor 430a is not covered by the top layer 420 a.

As shown in fig. 1K, in the present embodiment, the thickness of the conductor 430a is also significantly larger than the thickness of the LED chip 442, and the thickness of the conductor 430a is closer to the thickness of the top layer 420a on the conductor segment 430 than the thickness of the LED chip 442. In the width direction of the LED filament (the width direction is perpendicular to the axial direction and the aforementioned thickness direction), the top layer 420a has a width W1, and the LED chip 442 has a width W2, the width W2 of the LED chip 442 being close to the width W1 of the top layer 420 a. That is, the top layer 420a is slightly larger than the LED chip 442 in the width direction and slightly larger than the conductor 430a in the thickness direction. In other embodiments, width W1 of top layer 420 a: the width W2 of the LED chip 442 is 2-5: 1. In the present embodiment, the base layer 420b and the top layer 420a have the same width W1, but are not limited thereto. In addition, as shown in fig. 1K, in the present embodiment, the conductor segment 430 further includes a wavy concave structure 432a, and the wavy concave structure 432a is disposed on a side surface of the conductor segment 430. In the present embodiment, the recessed structure 432a is recessed from the upper surface of the top layer 420a of the conductor segment 430. The plurality of concave structures 432a are arranged at intervals along the axial direction, and are parallel to each other, and present a continuous wave shape. In some embodiments, the plurality of recessed structures 432a are arranged consecutively and closely along the axial direction. In some embodiments, the wavy concave structure 432a may also be disposed around the entire outer circumferential surface of the conductor segment 430 centering on the axial direction of the LED filament. In some embodiments, the wavy concave structure 432a may be changed to a wavy convex structure. In some embodiments, the wavy concave structures and the wavy convex structures may be alternately arranged together to form wavy concave-convex structures.

As shown in fig. 1L, in the present embodiment, the LED chip 442 has a length in the axial direction of the LED filament and a width in the X direction, and the ratio of the length to the width of the LED chip 442 is 2:1 to 6: 1. For example, in one embodiment, two LED chips are electrically connected as a chip unit, and the length-to-width ratio of the LED chip unit can be 6:1, so that the filament has a larger luminous flux. Moreover, the LED chip 442, the

electrodes

410 and 412 and the conductor 430a have thicknesses in the Y direction, the thicknesses of the

electrodes

410 and 412 are smaller than the thickness of the LED chip 442, the thickness Tc of the conductor 430a is also smaller than the thickness of the chip 442, that is, the conductor 430a and the

electrodes

410 and 412 are seemingly thinner than the chip 442. In addition, the top layer 420a and the base layer 420b have a thickness in the Y direction, and the thickness of the base layer 420b is smaller than the maximum thickness of the top layer 420 a. In the present embodiment, the conductor 430a appears parallelogram rather than rectangle in the top view along the Y direction, i.e. the included angle of the four sides of the conductor 430a appears in the top view is not 90 degree. In addition, two ends of the LED chip 442 are respectively connected to the

wires

440 or 450 to connect to another chip 442 or the conductor 430a through the

wires

440 or 450, and two ends of the LED chip 442 are used to connect to connection points of the

wires

440 or 450, which are not aligned with each other in the axial direction of the LED filament. For example, the connection point at one end of the chip 442 is shifted toward the negative X direction, and the connection point at the other end of the chip 442 is shifted toward the positive X direction, i.e., the two connection points at the two ends of the chip 442 are separated by a distance in the X direction.

As shown in fig. 1K, the wavy concave or convex structures 432a are wavy in the Y direction, but are kept linear in the axial direction of the LED filament (in a top view, the wavy concave or convex structures 432a are straight lines arranged along the axial direction of the LED filament), or a line connecting the lowest points of the concave structures 432a in the Y direction or a line connecting the highest points of the convex structures 432a in the Y direction is a straight line. The wavy concave structure 432a shown in fig. 1L is not only wavy in the Y direction, but also curved in the axial direction of the LED filament (in top view, the wavy concave or convex structure 432a is a curve arranged along the axial direction of the LED filament), or a line connecting the lowest points of the concave structure 432a in the Y direction or a line connecting the highest points of the convex structure 432a in the Y direction is a curve.

As shown in fig. 1M, which is a partial top view of the conductor segment 430 of fig. 1L, it exhibits a wavy concave or convex structure 432a, and fig. 1L exhibits a bent form of the conductor segment 430 in the axial direction of the LED filament. In addition, in the present embodiment, the width of each concave structure 432a itself in the axial direction of the LED filament is irregular, that is, the width of any two positions of each concave structure 432a in the axial direction of the LED filament is unequal, for example, two positions of a certain concave structure 432a in fig. 1M have a width D1 and a width D2, respectively, and the width D1 is not equal to the width D2. In addition, in the present embodiment, the widths of the concave structures 432a in the axial direction of the LED filament are also irregular, for example, the widths of the concave structures 432a are not equal to each other where the concave structures are aligned in the axial direction of the LED filament, for example, two adjacent concave structures 432a in fig. 1M have a width D1 and a width D3 at two positions aligned in the axial direction, respectively, and the width D1 is not equal to the width D3. In other embodiments, the shape of the concave or convex structure 432a is a straight strip or a combination of a straight strip and a wave, and the shape of the concave or convex structure 432a of the top layer 420a at the conductor segment 430 can be a straight line or a combination of a straight line and a wave in a top view of the conductor segment.

According to the embodiments of the present invention, since the LED filament structure is divided into the LED section and the conductor section, the LED filament easily concentrates the stress on the conductor section when being bent, so that the gold wire connecting the adjacent chips in the LED section reduces the probability of breakage when being bent, thereby improving the overall quality of the LED filament.

The relevant design of the layered structure of the filament structure is explained next. Fig. 2A and 2B are schematic cross-sectional views of different embodiments of the filament, and as shown in fig. 2A and 2B, W1 is the width of the base layer 420B or the top layer 420a, and W2 is the width of the LED chip 442. When the widths of the base layer 420b or the top layer 420a are not uniform, W1 represents the width of the upper surface of the base layer 420b or the width of the lower surface of the top layer 420a, W1: w2 is 1: 0.8-0.9, the upper surface of the base layer 420b contacts the LED chip 402, and the lower surface of the base layer 420a is far away from the LED chip 442 and opposite to the upper surface of the base layer 420 b; the top surface of the top layer 420b is away from the LED chip 442, and the bottom surface of the top layer 420b is opposite to the top surface of the top layer 420b and contacts the base layer 420 a. W1 in fig. 2A indicates the width of the upper surface of the base layer 420b (or the minimum value of the width of the base layer 420 b); w1 shown in FIG. 2B is the width of the lower surface of top layer 420B (or the maximum of the width of top layer 420 a); since the LED chip 442 is a hexahedral light emitter on one hand, in order to ensure that the filament emits light laterally (i.e., the side of the LED chip 442 is still covered by the top layer 402 a), W1 and W2 may be designed to be unequal, and W1> W2; on the other hand, in order to ensure a certain flexibility of the filament and a small radius of curvature when the filament is bent (to ensure a certain flexibility of the filament), the ratio of the thickness and the width of the cross section of the filament perpendicular to the drawing length direction is preferably uniform. By adopting the design, the filament can easily realize the full-period lighting effect and has better bending property.

When the LED filament emits light in the LED bulb lamp packaged with inert gas, as shown in fig. 3, the light emitted by the LED chip 442 passes through interfaces a to F, where the interface a is an interface between GaN in the LED chip 442 and the top layer 420a, the interface B is an interface between the top layer 420a and the inert gas, the interface C is an interface between the substrate in the LED chip 442 and the die attach adhesive 450, the interface D is an interface between the die attach adhesive 450 and the base layer 420B, the interface E is an interface between the base layer 420B and the inert gas, and the interface F is an interface between the base layer 420B and the top layer 420 a. When light passes through the interfaces A-F, the refractive indexes of two substances at any interface are n1 and n2 respectively, and then | n1-n2| < 1.0, preferably | n1-n2| < 0.5, and more preferably | n1-n2| < 0.2. In one embodiment, B, E, D, F the refractive index of two substances at any one of the four interfaces is n1 and n2, respectively, such that | n1-n2| < 1.0, preferably | n1-n2| < 0.5, and more preferably | n1-n2| < 0.2. In one embodiment, the refractive index of the two substances at any one of the D, F interfaces is n1 and n2, respectively, such that | n1-n2| < 1.0, preferably | n1-n2| < 0.5, and more preferably | n1-n2| < 0.2. The smaller the absolute value of the difference in refractive index between the two substances at each interface, the higher the light extraction efficiency. For example, when light emitted by the LED chip 442 passes through the base layer 420b to the top layer 420a, the incident angle is θ 1, and the refraction angle is θ 2, assuming that the refractive index of the base layer 420b is n1 and the refractive index of the top layer 420a is n2, according to sin θ 1/sin θ 2 ═ n2/n1, the smaller the absolute value of the difference between n1 and n2, the closer the incident angle and the refraction angle are, the higher the light extraction efficiency of the LED filament is.

As shown in fig. 4A, an LED filament unit 400a1 including a single LED chip 442 is cut out of the LED filament 400 with the midpoint of two adjacent LED chips 442 as a boundary line, fig. 4A is a cross-sectional view of the LED filament unit 400a1 in the axial direction of the LED filament, and fig. 4B is a cross-sectional view of the LED filament unit 400a1 in the radial direction of the LED filament. As shown in fig. 4A and 4B, the light emitting angle of the LED chip 442 in the axial direction of the LED filament is α, the light emitting angle of the LED chip 442 in the radial direction of the LED filament is β, the surface of the LED chip 442 away from the base layer 420B is defined as the upper surface of the LED chip 442, the distance from the upper surface of the LED chip 442 to the outer surface of the top layer in the radial direction of the LED filament is H, the length of the LED filament unit 400a1 in the length direction of the LED filament is C, the light emitting area of one LED chip 442 in the LED filament in the axial direction of the LED filament is a central angle α, the top layer 420a has a sector area corresponding to the thickness H from the upper surface of the LED chip 442, and the linear distance parallel to the axial direction of the LED filament between two end points of the arc length in the sector area is set as; the light emitting area of one LED chip 442 in the LED filament in the radial direction of the LED filament is a central angle beta, the distance from the top layer 420a to the upper surface of the LED chip 442 is a sector area corresponding to the thickness H, and the linear distance between two end points of the arc length in the sector area, which is parallel to the radial direction of the LED filament, is set to be L2. Meanwhile, the LED filament has an ideal light emitting area, better bending property and heat dissipation performance, an obvious dark area of the LED filament is avoided, material waste is reduced, the value of L1 can be designed to be 0.5C-L1-10C, and preferably C-L1-2C. If the value of L1 is smaller than the value of C, the light emitting areas of the adjacent LED chips 442 in the axial direction cannot obtain an intersection, and the LED filament may have a dark area in the axial direction; when the L2 value is smaller than the W1 value, the LED chip 442 is too large in the radial/width direction of the LED filament, which may also cause the top layer 420a to generate dark areas on both sides of the radial/width direction. The appearance of dark space not only can influence the whole luminous efficiency of LED filament, indirectly causes the waste in the material use simultaneously. The specific values of α and β depend on the type or specification of the LED chip 442.

In one embodiment, in the axial direction of the LED filament:

h is L1/2tan0.5 alpha, L1 is more than or equal to 0.5C and less than or equal to 10C, and 0.5C/2tan0.5 alpha is more than or equal to H and less than or equal to 10C/2tan0.5 alpha;

in the radial direction of the LED:

h is equal to L2/2tan0.5 beta, L2 is equal to or more than W1, and H is equal to or more than W1/2tan0.5 beta;

thus, Hmax is 10C/2tan0.5 α, Hmin is a; a is set to the maximum value of 0.5C/2tan0.5 alpha and W1/2tan0.5 beta, and A is set to the maximum value of C/2tan0.5 alpha and W1/2tan0.5 beta.

Thus, a.ltoreq.H.ltoreq.10C/2 tan0.5 α, preferably A.ltoreq.H.ltoreq.2C/2 tan0.5 α. When the types of the LED chips 442, the distance between adjacent LED chips, and the width of the filament are known, the distance H from the light emitting surface of the LED chip 442 to the outer surface of the top layer can be determined, so that the filament can have an excellent light emitting area in both the radial direction and the axial direction of the filament.

The light emitting angles of most LED chips in the axial direction and the radial direction of the LED filament are 120 degrees, B is set to be the maximum value of 0.14C and 0.28W1, B is set to be the maximum value of 0.28C and 0.28W1, and then B is more than or equal to H and less than or equal to 2.9C; preferably B.ltoreq.H.ltoreq.0.58C.

In one embodiment, in the axial direction of the LED filament:

H＝L1/2tan0.5α，0.5C≤L1≤10C；

in the radial direction of the LED filament:

h is L2/2tan0.5 beta, L2 is more than or equal to W1; w1 is less than or equal to 2Htan0.5 beta;

then 0.5Ctan0.5 beta/tan 0.5 alpha is more than or equal to L2 is more than or equal to 10Ctan0.5 beta/tan 0.5 alpha, and L2 is more than or equal to W1;

therefore, W1 is less than or equal to 10Ctan0.5 beta/tan 0.5 alpha. Thus W1max ═ min (10Ctan 0.5. beta./tan 0.5. alpha., 2Htan 0.5. beta.)

The relation between the LED chip width W2 and the base layer width W1 has been set to W1: w2 is 1:0.8 to 0.9, and thus W1min is W2/0.9

When D is the minimum value of 10Ctan0.5 beta/tan 0.5 alpha and 2Htan0.5 beta and D is the minimum value of 2Ctan0.5 beta/tan 0.5 alpha and 2Htan0.5 beta, W2/0.9. ltoreq. W1. ltoreq.d, preferably W2/0.9. ltoreq. W1. ltoreq.D.

Knowing the type of the LED chip 442, the distance between two adjacent LED chips in the LED filament, and the H value, the range of the width W of the filament can be known, so that the filament can have a relatively excellent light emitting area in both the radial direction and the axial direction of the filament.

The light emitting angles of most LED chips in the axial direction and the radial direction of the LED filament are 120 degrees, E is set to be the minimum value of 10C and 3.46H, and E is the minimum value of 2C and 3.46H, so that 1.1W 2-W1-E, preferably 1.1W 2-W1-E.

In one embodiment, in the axial direction of the LED filament:

h is L1/2tan0.5 alpha, L1 is more than or equal to 0.5C and less than or equal to 10C, and then 0.2Htan0.5 alpha is more than or equal to C and less than or equal to 4Htan0.5 alpha;

in the radial direction of the LED filament:

h is L2/2tan0.5 beta, L2 is more than or equal to W1, and L1 is more than or equal to W1tan0.5 alpha/tan 0.5 beta;

therefore, W1tan0.5 alpha/tan 0.5 beta is less than or equal to 10C, so that C is more than or equal to 0.1W1tan0.5 alpha/tan 0.5 beta;

cmax is 4htan0.5 α;

setting F to be the maximum of 0.2Htan0.5 alpha and 0.1W1tan0.5 alpha/tan 0.5 beta, and F to be the maximum of Htan0.5 alpha and 0.1W1tan0.5 alpha/tan 0.5 beta, so that F is less than or equal to C less than or equal to 4Htan0.5 alpha, preferably F is less than or equal to C less than or equal to 2Htan0.5 alpha;

when the width and the height H of the LED filament and the type of the LED chip 442 are determined, the range of the width C of the filament can be known, so that the LED filament can have an excellent light emitting area in both the radial direction and the axial direction of the filament.

The light emitting angles of most LED chips in the axial direction and the radial direction of the LED filament are 120 degrees, G is set to be the maximum value of 0.34H and 0.1W1, G is set to be the maximum value of 1.73H and 0.1W1, and then G is less than or equal to C and less than or equal to 6.92H, preferably G is less than or equal to C and less than or equal to 3.46H.

In the above embodiment, the thickness of the LED chip 442 is small relative to the thickness of the top layer 420a, and therefore can be ignored in most cases, i.e., H can also represent the actual thickness of the top layer 420 a. In other embodiments, the light-converting layer is similar to that of FIG. 1A, for example, differing only in the location of the electrodes as shown in FIG. 1A, the height of the top layer 420a being adapted to the above-mentioned range of H.

As shown in fig. 5, the center O of the top layer 420a indicated by a solid line does not overlap with the light-emitting surface a of the LED chip, the center O 'of the top layer 420a indicated by a dashed line overlaps with the light-emitting surface of the LED chip, and the radius of the semicircle with the center O being equal to the radius of the semicircle with the center O', as can be seen from the figure, tan α is m1/r, tan β is m2/r, and m1 is greater than m2, so α is greater than β, and therefore, when the light-emitting surface overlaps with the center (i.e., the distance from the center point of the light Ca emitted by the LED chip to the outer surface of the top layer is substantially the same), the light.

The LED chip can be replaced by a back-plated chip, the plated metal is silver or gold alloy, and when the back-plated chip is adopted, the mirror reflection can be improved, and the light emitting quantity of the light emitting surface A of the LED chip can be increased.

The chip wire bonding related design of the LED filament is described next. The

LED chip units

302 and 304 may be a single LED chip, or may include a plurality of LED chips, i.e., two or more LED chips.

As shown in fig. 6A, the LED filament 300 includes a plurality of

LED chip units

302, 304, a conductor 330a, and at least two

electrodes

310, 312, the conductor 330a is located between two adjacent

LED chip units

302, 304, and the

LED chip units

302, 304 are located at substantially the same position in the Y direction, so that the overall width of the LED filament 300 is smaller, and further the heat dissipation path of the LED chip is shortened, and the heat dissipation effect is improved. The

electrodes

310 and 312 are disposed corresponding to the

LED chip units

302 and 304 and electrically connected to the

LED chip units

302 and 304 through the wires 340, the LED chip unit 302/304 is electrically connected to the conductor 330a through the wires 350, the conductor 330a is substantially Z-shaped, which can increase the mechanical strength of the conductor and the area where the LED chip is located and can prevent the wires connecting the LED chip and the conductor from being damaged when the LED filament 300 is bent, and the wires 340 are disposed parallel to the X direction.

As shown in fig. 6B, the LED filament 300 includes a plurality of

LED chip units

302, 304, a conductor 330a, and at least two

electrodes

310, 312, the

LED chip units

302, 304 are at the same position in the Y direction, the conductor 330a is parallel to the X direction, the conductor 330a includes a first conductor 3301a and a second conductor 3302a, which are respectively located at two sides of the LED chip unit 302/304, the first conductor 3301a is located between two adjacent LED chip units, and is electrically connected to the LED chip unit 302/304 through a wire 350. The lead 350 is perpendicular to the X direction, so that the internal stress on the cross section area of the lead when the LED filament 300 is bent is reduced, and the bending resistance of the lead is improved. The second conductor 3302a and the LED chip 142 are not electrically connected, and the second conductor 3302a extends to the wire 340 along the X direction, so that when the LED filament 300 is subjected to an external force, the stress buffering effect can be achieved, the LED chip is protected, the product stability is improved, and then the stress on the two sides of the LED chip is balanced. The

electrodes

310, 312 are disposed corresponding to the

LED chip units

302, 304 and electrically connected to the

LED chip units

302, 304 through wires 340.

As shown in fig. 6C, the first conductor 3301a and the second conductor 3302a extend to the wire 340 along the X direction, and the first conductor 3301a and the second conductor 3302a are connected to the LED chip unit 302 and the LED chip unit 304 by the wire 350. In other embodiments, for example, the first conductor 3301a connects the LED chip unit 302 and the LED chip unit 304 through the wire 350, and the second conductor 3302a may not be electrically connected to the LED chip unit 302/304. Through setting up the conductor in LED chip both sides for when LED filament 300 buckles, can play the effect that increases LED filament 300 intensity and can disperse the produced heat of some LED chips when luminous again.

Fig. 7A is a schematic view of an embodiment of the layered structure of the LED filament 400 of the present invention, the LED filament 400 having: a light conversion layer 420;

LED chip units

402, 404; the

electrodes

410, 412; and a conductor segment 430 for electrically connecting the two adjacent

LED chip units

402, 404. The

LED chip units

402 and 404 include at least two LED chips 442, which are electrically connected to each other through a wire 440. In the present embodiment, the conductor segment 430 includes a conductor 430a, the conductor segment 430 is electrically connected to the

LED segments

402 and 404 through a wire 450, wherein a shortest distance between two LED chips 442 respectively located in two adjacent

LED chip units

402 and 404 is greater than a distance between two adjacent LED chips in the LED chip unit 402/404, and a length of the wire 440 is less than a length of the conductor 430 a. The light conversion layer 420 is coated on at least two sides of the LED chip 442/

electrodes

410, 412. The light conversion layer 420 exposes a portion of the

electrodes

410 and 412, respectively. When the chip is being bonded along the X direction, for example, the wires and the conductors are gold wires, as shown in fig. 7B, the quality of the bonding wires is mainly determined by A, B, C, D, E five points, a is the connection between the chip pad 4401 and the gold ball 4403, B is the connection between the gold ball 4403 and the gold wire 440, C is between two sections of the gold wire 440, D is the connection between the gold wire 440 and the two solder bars 4402, and E is between the two solder bars 4402 and the surface of the chip 442, because point B is the first bending point when the gold wire 440 goes through the wire arc, and the wire diameter of the gold wire 440 at point D is relatively thin, the gold wire 440 is easily broken at points B and D, and thus, for example, when implementing the structure shown in fig. 7A, the top layer 420a only needs to cover points B and D when the LED filament 300 is packaged, and a part of the gold wire is exposed outside the light conversion layer. If the surface of the LED chip 442 farthest from the base layer 420b is defined as the upper surface of the LED chip 442, the distance from the upper surface of the LED chip 442 to the surface of the top layer 420a is 100-200 μm.

The material content of the inventive LED filament with respect to the base layer is explained next. Materials suitable for manufacturing the soft LED filament base layer or the light conversion layer must have characteristics of excellent light transmittance, good heat resistance, excellent thermal conductivity, appropriate refractive index, excellent mechanical properties, and difficulty in warping. These properties can be satisfied by adjusting the kinds and content ratios of the main material, the modifier and the additive contained in the silicone-modified polyimide composition. The invention provides a filament base layer or a light conversion layer formed by a composition containing organic silicon modified polyimide, which can meet the characteristics, and can also adjust the characteristics of the filament base layer or the light conversion layer by adjusting the types and the contents of a main material, a modifier and an additive in a specific or partial composition so as to meet special requirement environments. The adjustment of each characteristic is as follows.

Blending mode of organic silicon modified polyimide

The organic silicon modified polyimide provided by the invention comprises a repeating unit represented by the following general formula (I):

in the general formula (I), Ar¹Is a 4-valent organic group. The organic group may have a benzene ring or an alicyclic hydrocarbon structure, and the alicyclic hydrocarbon structure may be a monocyclic alicyclic hydrocarbon structure or an alicyclic hydrocarbon structure having a bridged ring. The organic group may be a benzene ring structure or an alicyclic hydrocarbon structure containing an active hydrogen functional group, and the active hydrogen functional group may be any one or more of a hydroxyl group, an amino group, a carboxyl group, an amide group, or a thiol group.

Ar²Is a 2-valent organic group, and the organic group can have an alicyclic hydrocarbon structure of a monocyclic system, or a 2-valent organic group containing an active hydrogen functional group, wherein the active hydrogen functional group is any one or more of a hydroxyl group, an amino group, a carboxyl group, an amide group or a thiol group.

Each R is independently selected from methyl or phenyl.

n is 1-5, preferably n is 1 or 2 or 3 or 5.

The number average molecular weight of the general formula (I) is 5000 to 100000, preferably 10000 to 60000, and more preferably 20000 to 40000. The number average molecular weight is a polystyrene conversion value based on a calibration curve prepared by a Gel Permeation Chromatography (GPC) apparatus using standard polystyrene. When the number average molecular weight is 5000 or less, it is difficult to obtain good mechanical properties after curing, and particularly, the elongation tends to decrease. On the other hand, when it exceeds 100000, the viscosity becomes too high, making the resin difficult to form.

Ar¹Is a component derived from a dianhydride which may comprise an aromatic acid anhydride and an aliphatic seriesThe acid anhydride and the aromatic acid anhydride include aromatic acid anhydrides containing only benzene rings, fluorinated aromatic acid anhydrides, aromatic acid anhydrides containing amide groups, aromatic acid anhydrides containing ester groups, aromatic acid anhydrides containing ether groups, aromatic acid anhydrides containing sulfur groups, aromatic acid anhydrides containing sulfone groups, aromatic acid anhydrides containing carbonyl groups, and the like.

Examples of the aromatic acid anhydride containing only a benzene ring include pyromellitic anhydride (PMDA), 2,3,3',4' -biphenyltetracarboxylic dianhydride (bpda), 3,3',4,4' -biphenyltetracarboxylic dianhydride (sBPDA), 4- (2, 5-dioxotetrahydrofuran-3-yl) -1,2,3, 4-tetrahydronaphthalene-1, 2-dicarboxylic anhydride (TDA), and the like; fluorinated aromatic anhydrides such as 6FDA 4,4' - (hexafluoroisopropylene) diphthalic anhydride; aromatic acid anhydrides containing an amide group include N, N ' - (5,5' - (perfluoropropyl-2, 2-diyl) bis (2-hydroxy-5, 1-phenylene)) bis (1, 3-dioxo-1, 3-dihydroisobenzofuran) -5-carboxamide) (6FAP-ATA), N ' - (9H-fluoren-9-ylidene-di-4, 1-phenylene) bis [1, 3-dihydro-1, 3-dioxo-5-isobenzofurancarboxamide ] (FDA-ATA), and the like; the aromatic acid anhydride containing an ester group includes p-phenyl bis (trimellitate) dianhydride (TAHQ), etc.; the aromatic acid anhydride containing an ether group includes 4,4' - (4,4' -isopropyldiphenoxy) bis (phthalic anhydride) (BPADA), 4' -oxydiphthalic anhydride (sODPA), 2,3,3',4' -diphenylether tetracarboxylic dianhydride (aODPA), 4' - (4,4' -isopropyldiphenoxy) bis (phthalic anhydride) (BPADA), etc.; the sulfur-group-containing aromatic acid anhydride includes 4,4' -bis (phthalic anhydride) sulfide (TPDA), etc.; sulfone group-containing aromatic acid anhydrides include 3,3',4,4' -diphenylsulfone tetracarboxylic acid dianhydride (DSDA) and the like; the carbonyl group-containing aromatic acid anhydride includes 3,3',4,4' -benzophenonetetracarboxylic dianhydride (BTDA) and the like.

Alicyclic acid anhydrides include 1,2,4, 5-cyclohexane tetracarboxylic dianhydride abbreviated as HPMDA, 1,2,3, 4-Butanetetracarboxylic Dianhydride (BDA), tetrahydro-1H-5, 9-methanopyrano [3,4-d ] oxanone-1, 3,6,8(4H) -Tetraone (TCA), hexahydro-4, 8-ethylene-1H, 3H-benzo [1, 2-C: 4,5-C' ] difuran-1, 3,5, 7-tetraone (BODA), cyclobutanetetracarboxylic dianhydride (CBDA), 1,2,3, 4-cyclopentanetetracarboxylic dianhydride (CpDA), etc., or an alicyclic acid anhydride having an olefin structure such as bicyclo [2.2.2] oct-7-ene-2, 3,5, 6-tetracarboxylic dianhydride (COeDA). If an acid anhydride having an ethynyl group such as 4,4' - (acetylene-1, 2-diyl) diphthalic anhydride (EBPA) is used, the mechanical strength of the light conversion layer can be further ensured by post-curing.

From the viewpoint of solubility, 4,4 '-oxydiphthalic anhydride (sODPA), 3',4,4 '-benzophenonetetracarboxylic dianhydride (BTDA), cyclobutanetetracarboxylic dianhydride (CBDA), and 4,4' - (hexafluoroisopropylidene) diphthalic anhydride (6FDA) are preferable. The above dianhydrides can be used singly or in combination of two or more.

Ar²And a component derived from a diamine which can be classified into an aromatic diamine and an aliphatic diamine, and the aromatic diamine includes an aromatic diamine containing only a benzene ring structure, a fluorinated aromatic diamine, an aromatic diamine containing an ester group, an aromatic diamine containing an ether group, an aromatic diamine containing an amide group, an aromatic diamine containing a carbonyl group, an aromatic diamine containing a hydroxyl group, an aromatic diamine containing a carboxyl group, an aromatic diamine containing a sulfone group, an aromatic diamine containing a sulfur group, and the like.

Aromatic diamines having only a benzene ring structure include m-phenylenediamine, p-phenylenediamine, 2, 4-diaminotoluene, 2, 6-diamino-3, 5-diethyltoluene, 4 '-diamino-3, 3' -dimethylbiphenyl, 9-bis (4-aminophenyl) Fluorene (FDA), 9-bis (4-amino-3-tolyl) fluorene, 2-bis (4-aminophenyl) propane, 2-bis (3-methyl-4-aminophenyl) propane, 4 '-diamino-2, 2' -dimethylbiphenyl (APB); fluorinated aromatic diamines including 2,2' -BIS (trifluoromethyl) diaminobiphenyl (TFMB), 2-BIS (4-aminophenyl) hexafluoropropane (6FDAM), 2-BIS [4- (4-aminophenoxy) phenyl ] Hexafluoropropane (HFBAPP), 2-BIS (3-amino-4-tolyl) hexafluoropropane and the like) (BIS-AF) and the like; the aromatic diamine containing an ester group includes [4- (4-aminobenzoyl) oxyphenyl ] -4-Aminobenzoate (ABHQ), di-p-aminophenyl terephthalate (BPTP), p-aminobenzoate (APAB), etc.; the aromatic diamine containing an ether group includes 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane) (BAPP), 2 '-bis [4- (4-aminophenoxy phenyl) ] propane (ET-BDM), 2, 7-bis (4-aminophenoxy) -naphthalene (ET-2,7-Na), 1, 3-bis (3-aminophenoxy) benzene (TPE-M), 4' - [1, 4-phenylbis (oxy) ] bis [3- (trifluoromethyl) aniline ] (p-6FAPB), 3,4 '-diaminodiphenyl ether, 4' -diaminodiphenyl ether (ODA), 1, 3-bis (4-aminophenoxy) benzene (TPE-R), 1, 4-bis (4-aminophenoxy) benzene (TPE-Q), 4,4' -bis (4-aminophenoxy) biphenyl (BAPB), and the like; the aromatic diamine containing an amide group includes N, N ' -bis (4-aminophenyl) benzene-1, 4-dicarboxamide (BPTPA), 3,4' -diaminobenzanilide (m-APABA), 4' -Diaminobenzanilide (DABA), etc.; the aromatic diamine containing carbonyl group includes 4,4 '-diaminobenzophenone (4,4' -DABP), bis (4-amino-3-carboxyphenyl) methane (or referred to as 6,6 '-diamino-3, 3' -methylene dibenzoic acid), etc.; the hydroxyl group-containing aromatic diamine includes 3,3' -dihydroxybenzidine (HAB), 2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane (6FAP), etc.; the aromatic diamine containing carboxyl group includes 6,6 '-diamino-3, 3' -methylene dibenzoic acid (MBAA), 3, 5-diaminobenzoic acid (DBA), etc.; the sulfone group-containing aromatic diamine includes 3,3' -diaminodiphenyl sulfone (DDS), 4' -diaminodiphenyl sulfone, bis [4- (4-aminophenoxy) phenyl ] sulfone (BAPS) (or 4,4' -bis (4-aminophenoxy) diphenyl sulfone), 3' -diamino-4, 4' -dihydroxydiphenyl sulfone (ABPS); the sulfur group-containing aromatic diamine includes 4,4' -diaminodiphenyl sulfide.

The aliphatic diamine is diamine without aromatic structure (such as benzene ring), the alicyclic diamine includes monocyclic alicyclic diamine, straight chain aliphatic diamine, the straight chain aliphatic diamine includes silicon oxygen type diamine, linear alkyl diamine, and linear aliphatic diamine containing ether group, the monocyclic alicyclic diamine includes 4,4' -diaminodicyclohexylmethane (PACM), 3-dimethyl-4, 4-diaminodicyclohexylmethane (DMDC); the silicone type diamine (also called amino modified silicone) includes alpha, omega- (3-aminopropyl) polysiloxane (KF8010), X22-161A, X22-161B, NH15D, 1, 3-bis (3-aminopropyl) -1,1,3, 3-tetramethyldisiloxane (PAME), etc.; the number of carbon atoms of the linear alkyl diamine is 6-12, and the linear alkyl diamine without a substituent is preferred; the ether group-containing linear aliphatic diamine includes ethylene glycol di (3-aminopropyl) ether and the like.

The diamine can also be selected from diamine containing fluorenyl, wherein fluorenyl has huge free volume and rigid condensed ring structure, and can ensure that polyimide has good heat resistance, thermal oxidation stability, mechanical property, optical transparency and good solubility in organic solvent, and the diamine containing fluorenyl, such as 9, 9-bis (3, 5-difluoro-4-aminophenyl) fluorene, which can be obtained by the reaction of 9-fluorenone and 2, 6-dichloroaniline. The fluorinated diamine can also be 1, 4-bis (3 '-amino-5' -trifluoromethylphenoxy) biphenyl, the diamine is meta-substituted fluorine-containing diamine with a rigid biphenyl structure, the meta-substituted structure can block charge flow along the molecular chain direction, and the intermolecular conjugation effect is reduced, so that the absorption of visible light to light is reduced, and the diamine or anhydride with an asymmetric structure can improve the transparency of the organic silicon modified polyimide resin composition to a certain extent. The above diamines may be used alone or in combination of two or more.

Examples of the diamine having an active hydrogen include diamines having a hydroxyl group such as 3,3 '-diamino-4, 4' -dihydroxybiphenyl, 4 '-diamino-3, 3' -dihydroxy-1, 1 '-biphenyl (or referred to as 3,3' -dihydroxybiphenylamine) (HAB), 2-bis (3-amino-4-hydroxyphenyl) propane (BAP), 2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane (6FAP), 1, 3-bis (3-hydroxy-4-aminophenoxy) benzene, 1, 4-bis (3-hydroxy-4-aminophenyl) benzene, 3 '-diamino-4, 4' -dihydroxydiphenyl sulfone (ABPS) can be exemplified, as the diamine having a carboxyl group, 3, 5-diaminobenzoic acid, bis (4-amino-3-carboxyphenyl) methane (otherwise known as 6,6 '-diamino-3, 3' -methylenedibenzoic acid), 3, 5-bis (4-aminophenoxy) benzoic acid, 1, 3-bis (4-amino-2-carboxyphenoxy) benzene are exemplified. Diamines having an amino group include, for example, 4' -Diaminobenzanilide (DABA), 2- (4-aminophenyl) -5-aminobenzimidazole, diethylenetriamine, 3,3' -diaminodipropylamine, triethylenetetramine, and N, N ' -bis (3-aminopropyl) ethylenediamine (or N, N-bis (3-aminopropyl) ethylethylamine). Diamines containing thiol groups, for example 3, 4-diaminobenzenethiol. The above diamines may be used alone or in combination of two or more.

The organic silicon modified polyimide can be synthesized by a known synthesis method. Dianhydrides and diamines can be produced by dissolving them in an organic solvent for imidization in the presence of a catalyst, examples of which include acetic anhydride/triethylamine type, valerolactone/pyridine type, etc., preferably, water generated by an azeotropic process in imidization, and removal of water is promoted by using a dehydrating agent such as toluene.

In other embodiments, a small portion of amic acid can be present in the main chain of the polyimide, for example, the ratio of amic acid to imide in the polyimide molecule is 1-3: 100, and there is an interaction force between amic acid and epoxy resin, so that the base layer has a better performance. In other embodiments, the solid material (such as the thermal curing agent, the inorganic heat-dissipating particles, and the phosphor) can be added in the state of the polyamic acid to obtain the base layer. In addition, the alicyclic anhydride and the diamine can be directly heated and dehydrated to obtain the solubilized polyimide, and the solubilized polyimide is used as a glue material, has good light transmittance and is liquid, so that other solid substances (such as inorganic heat dissipation particles and fluorescent powder) can be more fully dispersed in the glue material.

In one embodiment, when preparing the silicone-modified polyimide, the diamine and the anhydride are heated and dehydrated to obtain polyimide, and the silicone-type diamine is dissolved in a solvent to obtain the silicone-modified polyimide. In another embodiment, the reaction is carried out with a silicone-type diamine in the state of amic acid (amic-acid) before the polyimide is obtained.

Further, an acid anhydride and a diamine may be used, and an imide compound obtained by dehydrating, ring-closing and polycondensing the acid anhydride and the diamine may be used, for example, an acid anhydride and a diamine having a molecular weight ratio of 1: 1. In one example 200 millimoles (mmol) of 4,4'- (hexafluoroisopropylidene) diphthalic anhydride (6FDA), 20 millimoles (mmol) of 2, 2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane (6FAP), 50 millimoles (mmol) of 2,2' -bis (trifluoromethyl) diaminobiphenyl (TFMB), and 130 millimoles (mmol) of aminopropyl terminated poly (dimethylsiloxane) were used to obtain a PI synthesis solution.

Although the polyimide compound having an amino group as a terminal can be obtained by the above method, a polyimide compound having a carboxyl group as a terminal can be obtained by other methods. In addition, in the reaction of the acid anhydride and the diamine, when the main chain of the acid anhydride contains carbon-carbon triple bonds, the bonding force of the carbon-carbon triple bonds can strengthen the molecular structure; or a diamine containing a vinyl siloxane structure.

The molar ratio of dianhydride to diamine is 1: 1. Wherein the molar fraction of the diamine containing active hydrogen functional groups in the whole diamine is 5-25%. The reaction temperature for synthesizing the polyimide is preferably 80-250 ℃, more preferably 100-200 ℃, and the reaction time can be adjusted according to the size of the batch, for example, the reaction time for obtaining 10-30 g of polyimide is 6-10 hours.

The silicone-modified polyimide can be classified into two types, i.e., fluorinated aromatic silicone-modified polyimide and aliphatic silicone-modified polyimide. The fluorinated aromatic silicone-modified polyimide is synthesized from a silicone-type diamine, an aromatic diamine having a fluorine (F) group (or referred to as an F-substituted aromatic diamine), and an aromatic dianhydride having a fluorine (F) group (or referred to as an F-substituted aromatic anhydride); the aliphatic organosilicon modified polyimide is synthesized by dianhydride, silicon-oxygen type diamine and at least one diamine (also called aliphatic diamine) without aromatic structures (such as benzene rings), or the diamine (one diamine is silicon-oxygen type diamine) and at least one dianhydride (also called aliphatic anhydride) without aromatic structures (such as benzene rings), the aliphatic organosilicon modified polyimide comprises semi-aliphatic organosilicon modified polyimide and full-aliphatic organosilicon modified polyimide, and the full-aliphatic organosilicon modified polyimide is synthesized by at least one aliphatic dianhydride, silicon-oxygen type diamine and at least one aliphatic diamine; at least one aliphatic dianhydride or aliphatic diamine is used in the raw materials for synthesizing the semi-aliphatic organic silicon modified polyimide. The raw materials required for synthesizing the organic silicon modified polyimide and the silicon oxygen content of the organic silicon modified polyimide have certain influence on the transmittance, the color change performance, the mechanical performance, the warping degree and the refractive index of the base layer.

The silicone-modified polyimide of the present invention has a siloxane content of 20 to 75 wt%, preferably 30 to 70 wt%, a glass transition temperature of 150 ℃ or lower, and the glass transition temperature (Tg) is measured by using TMA-60 manufactured by shimadzu corporation, a thermal curing agent, and the test conditions are as follows: loading: 5 g; temperature rise rate: 10 ℃/min; measuring the atmosphere: a nitrogen atmosphere; nitrogen flow rate: 20 ml/min; measurement temperature range: -40 to 300 ℃. When the siloxane content is less than 20%, a film made of the silicone-modified polyimide resin composition may become very hard and brittle due to the filling of the phosphor and the thermally conductive filler, and also warp after drying and curing, resulting in low processability; in addition, the resistance to thermal discoloration is reduced; when the siloxane content is more than 75%, the film made of the silicone-modified polyimide resin composition becomes cloudy, the light transmittance decreases, and the tensile strength of the film decreases. The content of siloxane in the invention is the weight ratio of silicon-oxygen type diamine (the structural formula is shown as formula (A)) to organic silicon modified polyimide, and the weight of the organic silicon modified polyimide is the sum of the weight of diamine and dianhydride used for synthesizing the organic silicon modified polyimide minus the weight of water generated in the synthesis process.

R in the formula (A) is selected from methyl or phenyl; r is preferably methyl, and n is 1-5, preferably 1,2,3, 5.

The organic solvent required for synthesizing the silicone-modified polyimide may be one that can dissolve the silicone-modified polyimide and ensure affinity (wettability) with the phosphor or filler to be added, but a large amount of the solvent is not left in the product, and the solvent is generally used in an amount of 1mol when the number of moles of the solvent is equal to the number of moles of water formed from the diamine and the acid anhydride, for example, 1mol of water formed from 1mol of the diamine and 1mol of the acid anhydride. In addition, the boiling point of the selected organic solvent at normal atmospheric pressure is 80 ℃ or higher and less than 300 ℃, more preferably 120 ℃ or higher and less than 250 ℃. Since drying and curing at a low temperature are required after coating, if the temperature is lower than 120 ℃, during the implementation of the coating process, it may not be well coated because the drying speed is too fast. If the boiling temperature of the organic solvent is selected to be higher than 250 deg.C, drying at a low temperature may be delayed. Specifically, the organic solvent is an ether organic solvent, an ester organic solvent, dimethyl ether, a ketone organic solvent, an alcohol organic solvent, an aromatic hydrocarbon solvent or the like. The ether organic solvent comprises ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether and propylene glycol monoethyl ether; the ester organic solvent comprises acetate, the acetate comprises ethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, butyl acetate, isobutyl acetate and 3-methoxybutyl acetate, and the ester solvent can also be ethyl lactate, butyl acetate, methyl benzoate or ethyl benzoate; dimethyl ether solvents include triglyme or tetraglyme; the ketone solvent includes acetylacetone, methyl isobutyl ketone, cyclopentanone, acetylacetone, cyclopentanone, or 2-heptanone; the alcohol solvent comprises isobutanol, amyl alcohol, 3-methyl-2-butanol and diacetone alcohol; the aromatic hydrocarbon solvent includes toluene or xylene; other solvents include gamma-butyrolactone, N-methylpyrrolidone, N-dimethylformamide, dimethyl sulfoxide.

The invention provides an organic silicon modified polyimide resin composition which comprises the organic silicon modified polyimide and a thermal curing agent, wherein the thermal curing agent is epoxy resin, isocyanate or a bisoxazoline compound. In one embodiment, the amount of the thermal curing agent is 5 to 12% of the weight of the silicone modified polyimide based on the weight of the silicone modified polyimide. The organic silicon modified polyimide resin composition can further comprise heat dissipation particles and fluorescent powder.

Light transmittance

Factors affecting the light transmittance of the silicone-modified polyimide resin composition are at least the type of the main material, the type of the modifier (thermal curing agent), the type and content of the heat-dissipating particles, and the siloxane content. The light transmittance refers to the transmittance of light in the vicinity of the main light-emitting wavelength range of the LED chip, for example, in the vicinity of 450nm in the main light-emitting wavelength range of a blue LED chip, the absorbance of the composition or polyimide in the vicinity of 450nm is low enough or even not absorbed, so that most or all of the light can be ensured to pass through the composition or polyimide. In addition, when light emitted by the LED chip passes through the interface of the two substances, the closer the refractive indexes of the two substances are, the higher the light extraction efficiency is, the refractive index of the substance (such as the solid crystal glue) which is in contact with the filament substrate (or the substrate) is, and therefore, the refractive index of the organic silicon modified polyimide composition is 1.4-1.7, preferably 1.4-1.55. The organic silicon modified polyimide resin composition is used for the filament base layer, and needs to have good light transmittance at the peak wavelength of InGaN of a blue excitation white LED. In order to obtain good transmittance, the raw materials for synthesizing the organic silicon modified polyimide, the thermal curing agent and the heat dissipation particles can be changed, and since the fluorescent powder in the organic silicon modified polyimide resin composition has a certain influence on the transmittance test, the organic silicon modified polyimide resin composition for measuring the transmittance does not contain the fluorescent powder, and the transmittance of the organic silicon modified polyimide resin composition is 86-93%, preferably 88-91%, or preferably 89-92%, or preferably 90-93%.

The acid anhydride and the diamine react to form the polyimide, wherein the acid anhydride and the diamine can be respectively selected from different compositions, namely, the polyimides formed by the reaction of different acid anhydrides and different diamines have different light transmittances. The aliphatic organic silicon modified polyimide resin composition comprises aliphatic organic silicon modified polyimide and a thermal curing agent, and the F-type aromatic organic silicon modified polyimide resin composition comprises F-type aromatic organic silicon modified polyimide and a thermal curing agent. The aliphatic silicone-modified polyimide resin composition has a high light transmittance because the aliphatic silicone-modified polyimide has an alicyclic structure. In addition, the fluorinated aromatic, semi-aliphatic and fully aliphatic polyimides have good light transmittance for blue LED chips. The fluorinated aromatic silicone-modified polyimide is synthesized from a silicone-type diamine, an aromatic diamine having a fluorine (F) group (or referred to as an F-substituted aromatic diamine), and an aromatic dianhydride having a fluorine (F) group (or referred to as an F-substituted aromatic anhydride), that is, Ar¹And Ar²Both of which have fluorine (F) groups. The semi-aliphatic and full-aliphatic organosilicon modified polyimide is synthesized by dianhydride, silicon-oxygen type diamine and at least one diamine (or called aliphatic diamine) without aromatic structures (such as benzene rings), or synthesized by diamine (one of which is silicon-oxygen type diamine) and at least one dianhydride (or called aliphatic anhydride) without aromatic structures (such as benzene rings), namely Ar¹And Ar²At least one of the two is an alicyclic hydrocarbon structure.

Although the main emission wavelength of the blue LED chip is 450nm, the blue LED chip may emit a small amount of light with a short wavelength of about 400nm due to the difference in the process conditions of the chip and the influence of the environment. The absorption rates of fluorinated aromatic, semi-aliphatic and fully aliphatic polyimides are different for light with a short wavelength of 400nm, and the absorption rate of the fluorinated aromatic polyimide for light with a short wavelength of about 400nm is about 20%, that is, the light transmittance of light with a wavelength of 400nm through the fluorinated aromatic polyimide is about 80%. The absorbance of the semi-aliphatic and fully aliphatic polyimides at a short wavelength of 400nm is lower than that of the fluorinated aromatic polyimides at a short wavelength of around 400nm, and the absorbance is only about 12%. Therefore, in one embodiment, if the LED chip used in the LED filament has a uniform quality and emits less blue light with a short wavelength, the fluorinated aromatic silicone modified polyimide can be used to fabricate the filament base layer or the light conversion layer. In another embodiment, if the LED chips used in the LED filament have different qualities and emit more blue light with short wavelength, the filament base layer or the light conversion layer can be made of semi-aliphatic or full-aliphatic silicone modified polyimide.

The addition of different thermal curing agents has different effects on the light transmittance of the organic silicon modified polyimide. Table 1-1 shows the effect of adding different thermal curing agents on the light transmittance of the all-aliphatic silicone modified polyimide, and under the condition that the main light-emitting wavelength of a blue LED chip is 450nm, the light transmittance of the all-aliphatic silicone modified polyimide is not significantly different by adding different thermal curing agents, but under the condition that the main light-emitting wavelength is 380nm, the light transmittance of the all-aliphatic silicone modified polyimide is affected by adding different thermal curing agents. The transmittance of the silicone-modified polyimide itself for light having a short wavelength (380nm) is inferior to that for light having a long wavelength (450nm), but the degree of difference varies depending on the addition of different thermosetting agents. For example, when the full-aliphatic silicone modified polyimide is added with the thermal curing agent KF105, the degree of decrease in light transmittance is small, but when the full-aliphatic silicone modified polyimide is added with the thermal curing agent 2021p, the degree of decrease in light transmittance may be large. Therefore, in one embodiment, if the LED chip used for the LED filament has a uniform quality and emits less blue light with a short wavelength, the thermal curing agent BPA or 2021p may be added. In contrast, in an embodiment, if the LED filament has different LED chip qualities and emits more blue light with short wavelength, the thermal curing agent KF105 may be optionally added. Tables 1-1 and 1-2 were each subjected to a light transmittance test using Shimadzu UV-1800. It has light transmittance at wavelengths of 380nm, 410nm and 450nm, respectively, according to the light emission of the white LED.

TABLE 1-1

Even if the same thermosetting agent is added, the light transmittance is affected differently when the amount of the thermosetting agent added is different. Tables 1-2 show that the light transmittance is improved when the addition amount of the heat-curing agent BPA of the all-aliphatic silicone-modified polyimide is increased from 4% to 8%. However, when the addition amount is further increased to 12%, the light transmittance is hardly exhibited. It was shown that the light transmittance became better as the amount of the heat-curing agent added increased, but when the amount was increased to a certain extent, the effect of adding more heat-curing agent on the light transmittance was considerably limited.

Tables 1 to 2

TABLE 2

Different heat-dissipating particles have different transmittances, and if the heat-dissipating particles with low transmittances or low light reflectivities are used, the light transmittance of the organic silicon modified polyimide resin composition is reduced. The heat-dissipating particles in the silicone-modified polyimide resin composition of the present invention are preferably transparent powders, or particles with high transmittance, or particles with high light reflectance, because the LED soft filament is mainly used for light emission, and thus the filament base layer needs to have good transmittance. In the case where two or more types of heat-dissipating particles are mixed, particles having high transmittance and particles having low transmittance are used in combination, and the proportion of the particles having high transmittance is made larger than that of the particles having low transmittance. For example, in one embodiment, the weight ratio of the particles with high transmittance to the particles with low transmittance is 3-5: 1.

Different siloxane contents also have an effect on light transmission. As can be seen from Table 2, the light transmission was only 85% at a siloxane content of only 37% by weight, but the light transmission was shown at a level of more than 94% as the siloxane content increased to more than 45%.

Heat resistance

Factors affecting the heat resistance of the silicone-modified polyimide resin composition are at least the type of main material, the silicone content, and the type and content of a modifier (thermal curing agent).

The organic silicon modified polyimide resin composition synthesized by organic silicon modified polyimide with fluorinated aromatic, semi-aliphatic and full aliphatic has excellent heat resistance, and is suitable for manufacturing a filament substrate or a light conversion layer. If carefully distinguished again, it was found that the fluorinated aromatic silicone-modified polyimide had better heat resistance properties than the aliphatic silicone-modified polyimide in the accelerated heat aging test (300 ℃ C.. times.1 hr). Therefore, in one embodiment, if the LED filament uses a high-power and high-brightness LED chip, the filament base layer or the light conversion layer can be made of fluorinated aromatic silicone modified polyimide.

The high or low siloxane content in the silicone-modified polyimide can affect the thermochromic resistance of the silicone-modified polyimide resin composition. The resistance to thermal discoloration means that the sample was left to stand at 200 ℃ for 24 hours, and the transmittance at a wavelength of 460nm of the sample after the standing was measured. As can be seen from Table 2, the transmittance after 200 ℃ C.. times.24 hours was only 83% when the siloxane content was only 37% by weight, the transmittance after 200 ℃ C.. times.24 hours was gradually increased as the siloxane content was increased, and the transmittance after 200 ℃ C.. times.24 hours was as high as 95% when the siloxane content was 73% by weight, so that increasing the siloxane content was effective in improving the thermal discoloration resistance of the silicone-modified polyimide.

When the organosilicon modified polyimide and the thermal curing agent are subjected to crosslinking reaction, the thermal curing agent only needs to have an organic group capable of reacting with an active hydrogen functional group in the polyimide, and the dosage and the type of the thermal curing agent have certain influence on the color change performance, the mechanical performance and the refractive index of the base layer, so that some thermal curing agents with better heat resistance and transmittance can be selected, and examples of the thermal curing agent comprise epoxy resin, isocyanate, bismaleimide or bisoxazoline compounds. The epoxy resin may be a bisphenol A type epoxy resin, such as BPA, and may also be a silicone type epoxy resin, such as KF105, X22-163, X22-163A, and may also be an alicyclic epoxy resin, such as 3, 4-epoxycyclohexylmethyl 3, 4-epoxycyclohexylformate (2021P), EHPE3150 CE. Through the bridging reaction of the epoxy resin, a three-dimensional bridging structure is formed between the organic silicon modified polyimide and the epoxy resin, and the structural strength of the rubber material is improved. In one embodiment, the amount of the thermal curing agent used can also be determined according to the molar amount of the thermal curing agent reacting with the active hydrogen functional groups in the silicone modified polyimide. In one embodiment, the molar amount of active hydrogen functional groups reacted with the thermal curing agent is equal to the molar amount of the thermal curing agent, e.g., 1mol of active hydrogen functional groups reacted with the thermal curing agent, the molar amount of the thermal curing agent is 1 mol.

Thermal conductivity

Factors influencing the thermal conductivity of the organic silicon modified polyimide resin composition include at least the type and content of fluorescent powder, the type and content of heat dissipation particles and the addition and type of coupling agent. Among them, the particle size and particle size distribution of the heat dissipating particles also affect the thermal conductivity.

The organosilicon modified polyimide resin composition may further contain a phosphor for obtaining desired light emitting characteristics, the phosphor may convert the wavelength of light emitted from the light emitting semiconductor, for example, a yellow phosphor may convert blue light into yellow light or red lightThe color phosphor is capable of converting blue light to red light. Yellow phosphors, e.g. (Ba, Sr, Ca)₂SiO₄:Eu、(Sr,Ba)₂SiO₄Eu (barium orthosilicate (BOS)) and the like transparent phosphor, Y₃Al₅O₁₂Ce (yttrium aluminum garnet) and Tb₃Al₃O₁₂Silicate phosphors having a silicate structure such as Ce (yttrium aluminum garnet), oxynitride phosphors such as Ca- α -SiAlON, and red phosphors including nitride phosphors such as CaAlSiN₃:Eu、CaSiN₂Eu. Green phosphors such as rare earth-halide phosphors, silicate phosphors, and the like. The content ratio of the phosphor in the silicone-modified polyimide resin composition can be arbitrarily set according to the desired light emission characteristics. In addition, since the thermal conductivity of the phosphor is much higher than that of the silicone-modified polyimide resin, the thermal conductivity of the entire silicone-modified polyimide resin composition is also improved as the content ratio of the phosphor in the silicone-modified polyimide resin composition is improved. Therefore, in one embodiment, on the premise of satisfying the light emitting characteristics, the content of the phosphor can be moderately increased to increase the thermal conductivity of the silicone modified polyimide resin composition, which is beneficial to the heat dissipation property of the filament base layer or the light conversion layer. When the silicone-modified polyimide resin composition is used as a filament base layer, the content, shape and particle size of the phosphor in the silicone-modified polyimide resin composition also have a certain influence on the mechanical properties (e.g., elastic modulus, elongation, tensile strength) and warpage of the base layer. In order to make the base layer have excellent mechanical properties, thermal conductivity and small warping degree, the fluorescent powder contained in the organic silicon modified polyimide resin composition is granular, the shape of the fluorescent powder can be spherical, plate-shaped or needle-shaped, and the shape of the fluorescent powder is preferably spherical; the phosphor has a maximum average length (average particle diameter in a spherical shape) of 0.1 μm or more, preferably 1 μm or more, more preferably 1 to 100 μm, and still more preferably 1 to 50 μm; the amount of the phosphor is not less than 0.05 times, preferably not less than 0.1 times, and not more than 8 times, preferably not more than 7 times, the weight of the silicone-modified polyimide, for exampleWhen the content of the phosphor is not less than 5 parts by weight, preferably not less than 10 parts by weight, and not more than 800 parts by weight, preferably not more than 700 parts by weight based on 100 parts by weight, and the content of the phosphor in the silicone-modified polyimide resin composition exceeds 800 parts by weight, the mechanical properties of the silicone-modified polyimide resin composition may not reach the strength required as a filament base, resulting in an increase in the fraction defective of the product. In an embodiment, two phosphors are added simultaneously, for example, when red phosphor and green phosphor are added simultaneously, the ratio of red phosphor to green phosphor is 1: 5-8, and preferably 1: 6-7. In another embodiment, two phosphors are added simultaneously, for example, when red phosphor and yellow phosphor are added simultaneously, the ratio of red phosphor to yellow phosphor is 1: 5-8, preferably 1: 6-7. In other embodiments, three or more phosphors may be added simultaneously.

The purpose of adding the heat dissipation particles is mainly to increase the heat conductivity of the organic silicon modified polyimide resin composition, maintain the luminous color temperature of the LED chip and prolong the service life of the LED chip. Examples of the heat dissipating particles include silica, alumina, magnesia, magnesium carbonate, aluminum nitride, boron nitride, diamond, or the like. From the viewpoint of dispersibility, silica, alumina, or a combination of both thereof is preferably used. The heat dissipating particles may be spherical, block-shaped, etc., and the spherical shape includes a shape similar to the spherical shape, and in one embodiment, spherical and non-spherical heat dissipating particles may be used to ensure the dispersibility of the heat dissipating particles and the thermal conductivity of the base layer, and the weight ratio of the spherical to non-spherical heat dissipating particles is 1: 0.15-0.35.

Table 3-1 shows the relationship between the content of heat-dissipating particles and the thermal conductivity of the silicone-modified polyimide resin composition, and the thermal conductivity of the silicone-modified polyimide resin composition increases with the increase in the content of heat-dissipating particles, but when the content of heat-dissipating particles in the silicone-modified polyimide resin composition exceeds 1200 parts by weight, the mechanical properties of the silicone-modified polyimide resin composition may not reach the strength required as a filament base layer,resulting in an increase in the defective rate of the product. In one embodiment, high-content and high-transmittance or high-reflectivity heat-dissipating particles (e.g., SiO) can be added₂、Al₂O₃) The light transmittance of the silicone-modified polyimide resin composition can be maintained, and the heat dissipation of the silicone-modified polyimide resin composition can be improved. Tables 3-1 and 3-2 show the thermal conductivity of the silicone-modified polyimide resin composition obtained as a test piece cut into a circle having a film thickness of 300um and a diameter of 30mm, measured by a thermal conductivity measuring device DRL-III manufactured by Hunan science, and the test conditions: hot plate temperature: 90 ℃; cold electrode temperature: 20 ℃; loading: 350N.

TABLE 3-1

The weight ratio is [ wt%]

0.0％

37.9％

59.8％

69.8％

77.6％

83.9％

89.0％

The volume ratio is [ vol%]

0.0％

15.0％

30.0％

40.0％

50.0％

60.0％

70.0％

Thermal conductivity [ W/m.K ]]

0.17

0.20

0.38

0.54

0.61

0.74

0.81

TABLE 3-2

Specification of	①	②	③	④	⑤	⑥	⑦
								Average particle diameter [ mu ] m]	2.7	6.6	9.0	9.6	13	4.1	12
Particle size distribution [ mu m ]]	1～7	1～20	1～30	0.2～30	0.2～110	0.1～20	0.1～100
								Thermal conductivity [ W/m.K ]]	1.65	1.48	1.52	1.86	1.68	1.87	2.10

Please refer to table 3-2 and fig. 8 for the effect of the particle size and distribution of the heat dissipating particles on the thermal conductivity of the silicone modified polyimide resin composition. Tables 3-2 and fig. 8 show the results of adding 7 kinds of heat dissipating particles of different specifications in the same ratio to the silicone-modified polyimide resin composition and the influence on the thermal conductivity thereof. The particle size of the heat-dissipating particles suitable for addition to the silicone-modified polyimide resin composition can be roughly classified into a small particle size (less than 1 μm), a medium particle size (1 to 30 μm), and a large particle size (greater than 30 μm).

The first specification, the second specification and the third specification are compared, and the first specification, the second specification and the third specification are all only added with heat dissipation particles with medium particle size and are different from each other in average particle size. The results show that the average particle size of the heat-dissipating particles does not significantly affect the thermal conductivity of the silicone-modified polyimide resin composition when only the heat-dissipating particles having a medium particle size are added. Comparison of the specification (c) and (c) shows that the addition of the specification (c) having a small particle size and a medium particle size under the condition of similar average particle sizes exhibits a thermal conductivity significantly superior to the addition of the specification (c) having only a medium particle size. Comparison of the specifications (a) and (b) shows that, in the case where both the small particle size and the medium particle size are added, the average particle size of the heat-dissipating particles is different, but there is no significant influence on the thermal conductivity of the silicone-modified polyimide resin composition. Comparison of the specifications (c) and (c) shows that the specification (c) of adding a large-sized heat dissipating particle in addition to a small-sized heat dissipating particle and a medium-sized heat dissipating particle has the most excellent thermal conductivity. The specifications are compared with the specification of the fifth part and the seventh part, and although the heat dissipation particles with large, medium and small particle sizes are added in the specifications of the fifth part and the seventh part, the average particle size is similar, the thermal conductivity of the specification of the seventh part is obviously superior to that of the specification of the fifth part, and the reason for the difference is related to the proportion of particle size distribution. Referring to fig. 8, the size distribution of the specification (c), the curve of the specification (c), and the slope are mostly very small, showing that the specification (c) includes not only each size but also a proper proportion of each particle size, and shows a normal distribution, for example, the small particle size content is about 10%, the medium particle size content is about 60%, and the large particle size content is about 30%. Reversely viewing the specification, the curve of the specification has two areas with large slopes, the areas are respectively in the particle size of 1-2 μm and the particle size of 30-70 μm, which means that most of the particle size of the specification is distributed in the particle size of 1-2 μm and the particle size of 30-70 μm, only a small amount of heat dissipation particles with the particle size of 3-20 μm are contained, and the two areas are distributed.

Therefore, the degree of influence of the particle size distribution of the heat dissipating particles on the thermal conductivity is larger than the average particle size of the heat dissipating particles, and the silicone modified polyimide resin has the best thermal conductivity when the heat dissipating particles with three kinds of particle sizes, namely large, medium and small, are added, and the content of the small particle size is about 5-20%, the content of the medium particle size is about 50-70%, and the content of the large particle size is about 20-40%. Because the heat dissipation particles are densely packed and contacted to form an efficient heat dissipation path in the same volume under the condition of three kinds of particle sizes, namely large, medium and small particle sizes.

In one embodiment, for example, alumina with a particle size distribution of 0.1-100 μm and an average particle size of 12 μm or alumina with a particle size distribution of 0.1-20 μm and an average particle size of 4.1 μm is used, wherein the particle size distribution is within the particle size range of alumina. In another embodiment, from the viewpoint of smoothness of the base layer, 1/5 to 2/5, preferably 1/5 to 1/3, having an average particle size of the base layer thickness, may be selected. The amount of the heat dissipation particles is 1-12 times of the weight (amount) of the organosilicon modified polyimide, for example, 100 parts by weight of the organosilicon modified polyimide, 100-1200 parts by weight of the heat dissipation particles, preferably 400-900 parts by weight of the heat dissipation particles, two kinds of heat dissipation particles are simultaneously added, for example, silicon dioxide and aluminum oxide are simultaneously added, and the weight ratio of the aluminum oxide to the silicon dioxide is 0.4-25: 1, preferably 1-10: 1.

When the organic silicon modified polyimide resin composition is synthesized, the adhesion between solid substances (such as fluorescent powder and heat dissipation particles) and a glue material (such as organic silicon modified polyimide) can be improved by adding a coupling agent (such as a silane coupling agent), the dispersion uniformity of the whole solid substances can be improved, and further the heat dissipation performance and the mechanical strength of a light conversion layer can be improved. The amount of the coupling agent is related to the amount of the heat dissipating particles added and the specific surface area thereof, and the amount of the coupling agent is (the amount of the heat dissipating particles is the specific surface area of the heat dissipating particles)/the minimum coating area of the coupling agent, for example, an epoxy titanate coupling agent is used, and the amount of the coupling agent is (the amount of the heat dissipating particles is the specific surface area of the heat dissipating particles)/331.5.

In other embodiments of the present invention, in order to further improve the properties of the silicone-modified polyimide resin composition in the synthesis process, additives such as a defoaming agent, a leveling agent or an adhesive may be optionally added during the synthesis process of the silicone-modified polyimide resin composition, as long as they do not affect the optical rotation resistance, mechanical strength, heat resistance and discoloration of the product. The defoaming agent is used for eliminating bubbles generated at the time of printing, coating and curing, and for example, an acrylic or silicone based surfactant is used as the defoaming agent. The leveling agent is used to eliminate irregularities on the surface of the coating film generated during printing and coating. Specifically, the composition preferably contains 0.01 to 2 wt% of a surfactant component, can suppress bubbles, can smooth a coating film by using a leveling agent such as an acrylic or silicone type, and preferably contains no ionic impurities. Examples of the binder include imidazole compounds, thiazole compounds, triazole compounds, organoaluminum compounds, organotitanium compounds, and silane coupling agents. Preferably, these additives are used in an amount of not more than 10% by weight based on the silicone-modified polyimide. When the blending amount of the additive exceeds 10% by weight, the physical properties of the resulting coating film tend to be lowered, and there also arises a problem of deterioration in optical rotation resistance caused by volatile components.

Mechanical strength

The factors influencing the mechanical strength of the organic silicon modified polyimide resin composition are at least the type of main material, the content of siloxane, the type of modifier (thermal curing agent), the content of fluorescent powder and the content of heat dissipation particles.

Different silicone-modified polyimide resins possess different properties, and table 4 shows the main properties of three silicone-modified polyimides, fluorinated aromatic, semi-aliphatic and fully aliphatic, respectively, at a siloxane content of about 45% (wt%). Fluorinated aromatics possess the best resistance to thermal discoloration, while full-aliphatic have the best light transmittance. The fluorinated aromatics have both higher tensile strength and elastic modulus. The mechanical strength test conditions shown in tables 4 to 6 were: the silicone-modified polyimide resin composition had a thickness of 50 μm and a width of 10mm, and the tensile properties of the film were measured using ISO527-3:1995 standard at a tensile rate of 10 mm/min.

TABLE 4

When the filament is manufactured, the LED chip and the electrode are fixed on the filament base layer formed by the organic silicon modified polyimide resin composition through the die bond adhesive, then the routing procedure is carried out, and the adjacent LED chip, the LED chip and the electrode are electrically connected through the conducting wires. In order to ensure the quality of die bonding and wire bonding and improve the product quality, the elastic modulus of the filament base layer should have a certain level to resist the lower pressure degree of the die bonding and wire bonding processes, so the elastic modulus of the filament base layer should be greater than 2.0Gpa, preferably 2-6 Gpa, and most preferably 4-6 Gpa. Table 5 shows the effect of varying siloxane content and the presence or absence of particle (phosphor and alumina) addition on the elastic modulus of silicone modified polyimide resin compositions. Under the condition that fluorescent powder and alumina particles are not added, the elastic modulus of the organic silicon modified polyimide resin composition is less than 2.0Gpa, and the elastic modulus is reduced along with the increase of the siloxane content, namely the organic silicon modified polyimide resin composition is softened. However, the elastic modulus of the organosilicon modified polyimide resin composition can be greatly improved and is more than 2.0GPa under the condition of adding the fluorescent powder and the alumina particles. Therefore, the increase in the siloxane content can soften the silicone-modified polyimide resin composition, facilitating the addition of more fillers, such as more phosphors or heat-dissipating particles. In order to provide the base layer with superior elastic modulus and thermal conductivity, the particle size distribution and mixing ratio of the heat dissipating particles may be appropriately selected so that the average particle size is in the range of 0.1 μm to 100 μm, or in the range of 1 μm to 50 μm.

In order to make the LED filament have better bending performance, the elongation at break of the filament base layer should be greater than 0.5%, preferably 1-5%, and most preferably 1.5-5%. Referring to table 5, the silicone modified polyimide resin composition has excellent elongation at break without adding phosphor and alumina particles, and the elongation at break increases with increasing siloxane content, and the elastic modulus decreases with decreasing, thereby reducing the occurrence of warpage. On the contrary, in the case where the phosphor and the alumina particles are added, the silicone-modified polyimide resin composition exhibits a decrease in elongation at break, an increase in elastic modulus, and an increase in warpage.

TABLE 5

The addition of the thermal curing agent can improve the heat resistance and glass transition temperature of the organic silicon modified polyimide resin, and can also improve the mechanical properties of the organic silicon modified polyimide resin, such as tensile strength, elastic modulus and elongation at break. And different heat curing agents are added, so that different promotion effects can be achieved. Table 6 shows the effect of the silicone-modified polyimide resin composition showing different tensile strength and elongation at break after the addition of different heat curing agents. The full aliphatic organic silicon modified polyimide has better tensile strength after the thermal curing agent EHPE3150 is added, and has better elongation when the thermal curing agent KF105 is added.

TABLE 6

Table 7: specific information of BPA

Table 8: 2021P details of

Table 9: specific information of EHPE3150 and EHPE3150CE

Table 10: the refractive index can be called refractive index, and the specific information of PAME, KF8010, X22-161A, X22-161B, NH15D, X22-163, X22-163A and KF-105.

The silicone-modified polyimide resin composition of the present invention can be used as a base layer in the form of a film or attached to a support. The film formation process includes three steps, (a) a coating step: spreading the organic silicon modified polyimide resin composition on a stripping body, and coating to form a film; (b) a drying and heating procedure: heating and drying the film together with the peeling body to remove the solvent in the film; (c) stripping: after completion of the drying, the film was peeled from the peeled body to obtain a film-form silicone-modified polyimide resin composition. The peeling body may be a centrifugal film or other material that does not chemically react with the silicone-modified polyimide resin composition, and for example, a PET centrifugal film may be used.

The organic silicon modified polyimide resin composition is attached to a carrier to obtain a component film, the component film can be used as a base layer, and the forming process of the component film comprises two procedures: (a) a coating process: spreading and coating the organic silicon modified polyimide resin composition on a carrier to form a composition film; (b) a drying and heating procedure: the constituent film is heat-dried to remove the solvent in the film.

As the coating method in the coating step, a roll-to-roll type coating apparatus such as a roll coater, a die coater, a knife coater, or the like, or a simple coating method such as a printing method, an ink jet method, a dispensing method, a spray method, or the like can be used.

The above silicone-modified polyimide resin composition can be dried and cured after coating to obtain a high thermal conductive film (composite film) to obtain a film having the characteristics of any one or a combination of the following: excellent light transmission, chemical resistance, heat resistance, thermal conductivity, film mechanical properties and optical rotation resistance. The temperature and time used in the drying and curing process may be appropriately selected depending on the solvent in the silicone-modified polyimide resin composition and the film thickness to be coated, and whether or not the drying and curing are complete may be determined based on the change in weight of the silicone-modified polyimide resin composition before and after drying and curing and the change in peak value of the thermal curing agent functional group on an infrared spectrum, for example, when an epoxy resin is used as the thermal curing agent, the difference in weight of the silicone-modified polyimide resin composition before and after drying and curing is equal to the weight of the added solvent and the increase or decrease in peak value of the epoxy group before and after drying and curing is determined as whether or not the drying.

In one embodiment, the amidation reaction is performed in a nitrogen atmosphere, or a vacuum defoaming method or both methods are used during the synthesis of the organic silicon modified polyimide resin composition, so that the volume percentage of the cells in the organic silicon modified polyimide resin composition composite film is 5-20%, preferably 5-10%. As shown in fig. 9B, the organic silicon modified polyimide resin composite film is used as a base layer of an LED soft filament (as in the previous LED filament embodiments), the base layer 420B has an upper surface 420B1 and an opposite lower surface 420B2, and fig. 9A shows the surface morphology of the base layer obtained by spraying gold on the surface of the base layer and observing under a vega3 electron microscope of Tescan corporation. As can be seen from the SEM images of the surface of the base layer shown in fig. 9B and 9A, there are foam holes 4d in the base layer, the volume percentage of the foam holes 4d in the base layer 420B is 5-20%, preferably 5-10%, the cross section of the foam holes 4d is irregular, as shown in the schematic cross section of the base layer 420B shown in fig. 9B, the dotted line in fig. 9B is a reference line, the upper surface 420B1 of the base layer includes a first region 4a and a second region 4B, the second region 4B includes the foam holes 4d, the surface roughness of the first region 4a is smaller than that of the second region 4B, light emitted from the LED chip is scattered by the foam holes of the second region, and the light emission is more uniform; the lower surface 420b2 of the base layer comprises a third area 4c, the surface roughness of the third area 4c is larger than that of the first area 4a, when the LED chip is placed in the first area 4a, the first area 4a is relatively flat, so that the subsequent fixed routing is facilitated, when the LED chip is placed in the second area 4b and the third area 4c, the contact area between the die bond glue and the base layer is large during die bonding, the bonding strength between the die bond glue and the base layer can be increased, therefore, the LED chip is placed on the upper surface 420b1, and the die bond and the bonding strength between the die bond glue and the base layer can be simultaneously ensured. When the organic silicon modified polyimide resin composition is used as the LED soft filament base layer, light emitted by an LED chip is scattered through bubbles in the base layer, the light is emitted more uniformly, and the glare phenomenon can be further improved. In one embodiment, the surface of the base layer 420b may be treated with a silicone resin or titanate coupling agent, preferably a silicone resin containing methanol or titanate coupling agent containing methanol, or a silicone resin containing isopropyl alcohol, and the treated base layer has a cross-sectional view as shown in fig. 9C, the upper surface 420b1 of the base layer has a relatively uniform surface roughness, the lower surface 420b2 of the base layer includes a third region 4C and a fourth region 4e, and the surface roughness of the third region 4C is greater than that of the fourth region 4 e. The surface roughness of the upper surface 420b1 of the base layer may be equal to the surface roughness of the fourth region 4 e. The surface of the base layer 420b is treated to allow a highly reactive and strong substance to enter a part of the pores 4d, thereby enhancing the strength of the base layer.

When the organosilicon modified polyimide resin composition is prepared by a vacuum defoaming method, the vacuum degree during vacuum defoaming is-0.5 to-0.09 MPa, preferably-0.2 to-0.09 MPa.

According to the invention, the resin with excellent light transmittance, chemical resistance, heat discoloration resistance, thermal conductivity, film mechanical property and optical rotation resistance required by the LED soft filament base layer can be obtained. Further, the highly thermally conductive resin film can be formed by a simple coating method such as a printing method coating method, an ink-jet method, a dispensing method, or the like.

When organosilicon modified polyimide resin composition complex film was as filament basic unit (or basic unit), the LED chip was six luminous bodies, and during the preparation of LED filament, at least biplanar by the top layer parcel of LED chip, current LED filament when lighting, can appear top layer and the inhomogeneous phenomenon of basic unit colour temperature, or granular sensation can appear in the basic unit, therefore the complex film as filament basic unit needs to possess excellent transparency. In addition, in order to realize the full-period light emitting effect of the bulb lamp adopting the filament, the composite film as the base layer needs to have certain flexibility,

the description of the application of the silicone modified polyimide to the filament structure is only represented by the description of fig. 1A, but not limited thereto. The same remarks apply to all similar LED filament configurations of the present invention.

The LED filament structure in each embodiment can be mainly applied to LED bulb lamp products, so that the LED bulb lamp can achieve the light emitting effect of full-period light through the flexible bending characteristic of the single LED filament. The following further describes a specific embodiment of applying the aforementioned LED filament to an LED bulb lamp.

The definition of the full-cycle light depends on the area where the LED bulb lamp is used, and can change along with the time. According to different organizations and countries, the LED bulb lamp capable of providing full-cycle light is declared to be capable of meeting different standards. The american energy star project lamp qualification criteria, first edition (bulb) 24, defines eligibility criterion version1.0, which requires that the emitted light between 135 and 180 degrees should be at least 5% of the total luminous flux (lm) at a full perimeter lamp base up setting, while 90% of the luminance measurements are variable, but not more than 25% different from the average of the total luminance measurements over all planes. Luminance (cd) is measured in each vertical plane at a vertical angle of 5 degrees increase (maximum) between 0 and 135 degrees. In JEL801 specifications of japan, the LED lamp is required to have a luminous flux within 120 degrees of the optical axis, which is not less than 70% of the total luminous flux of the bulb lamp. Based on the arrangement of the LED filaments with the symmetrical characteristic in the embodiment, the LED bulb lamp with the LED filaments can meet different standards of a full-cycle light lamp.

Referring to fig. 10A and 10B to 10D, fig. 10A is a schematic diagram of an LED bulb 40A according to an embodiment of the invention, and fig. 10B to 10D are a side view, another side view and a top view of the LED bulb 40A of fig. 10A, respectively. In the present embodiment, the LED bulb 40a includes a lamp housing 12, a base 16 connected to the lamp housing 12, a stem 19, and a single LED filament 100. Moreover, the LED bulb 40a and the single LED filament 100 disposed in the LED bulb 40a can refer to the LED bulbs, the LED filaments and their related descriptions of the previous embodiments, wherein the same or similar components and the connection relationship between the components are not described in detail.

In the embodiment, the stem 19 is connected to the base 16 and located inside the lamp housing 12, the stem 19 has a vertical rod 19a extending vertically to the center of the lamp housing 12, the vertical rod 19a is located on the central axis of the base 16, or the vertical rod 19a is located on the central axis of the LED bulb 40 a. The LED filament 100 is disposed around the vertical rod 19a and located in the lamp housing 12, and the LED filament 100 can be connected to the vertical rod 19a through a cantilever (the detailed description of the cantilever can refer to the previous embodiment and the attached drawings) to maintain the predetermined curve and shape. The LED filament 100 includes two

electrodes

110, 112 at both ends, a plurality of

LED segments

102, 104, and a plurality of conductor segments 130. As shown in fig. 10A to 10D, in order to separate the conductor segment 130 from the

LED segments

102 and 104, the LED filament 100 is distributed in a plurality of points on the conductor segment 130, which is only for the reader to understand more easily and is not intended to be limiting, and the following embodiments and related drawings are also separated from the

LED segments

102 and 104 by the conductor segment 130 exhibiting a point distribution. As described in the previous embodiments, each

LED segment

102, 104 may include a plurality of LED chips connected to each other, and each conductor segment 130 may include a conductor. Each conductor segment 130 is located between two

adjacent LED segments

102, 104, the conductor in each conductor segment 130 connects the LED chips in the two

adjacent LED segments

102, 104, and the LED chips in the two LED segments adjacent to the two

electrodes

110, 112 connect the two

electrodes

110, 112, respectively. The stem 19 may be connected to the two

electrodes

110, 112 by conductive brackets (the detailed description of which refers to the previous embodiments and figures).

As shown in fig. 10A to 10D, in the present embodiment, there are three conductor segments of the LED filament 100, wherein there are two first conductor segments 130, one second conductor segment 130', and four

LED segments

102 and 104, and each two

adjacent LED segments

102 and 104 are bent through the first conductor segment 130 and the second conductor segment 130'. Moreover, since the first and second conductor segments 130, 130 'have higher flexibility than the

LED segments

102, 104, the first and second conductor segments 130, 130' between two

adjacent LED segments

102, 104 can be bent to a greater extent, so that the included angle between two

adjacent LED segments

102, 104 can be relatively small, for example, the included angle can reach 45 degrees or less. In the present embodiment, each of the

LED segments

102, 104 has little or no bending compared to the first and second conductor segments 130, 130', so that the single LED filament 100 in the LED bulb 40a can be bent greatly by the first and second conductor segments 130, 130' and has a significant bending variation, and the LED filament 100 can be defined as a segment that is continuous after each of the bent first and second conductor segments 130, 130', so that each of the

LED segments

102, 104 forms a corresponding segment.

As shown in fig. 10B and 10C, in the present embodiment, each of the first conductor segment 130, the second conductor segment 130 'and the two

adjacent LED segments

102 and 104 form a U-shaped or V-shaped bent structure together, and the U-shaped or V-shaped bent structure formed by each of the first conductor segment 130, the second conductor segment 130' and the two

adjacent LED segments

102 and 104 is bent and divided into two segments, where the two

LED segments

102 and 104 are the two segments, respectively. In the present embodiment, the LED filament 100 is bent into four segments by the first conductor segment 130 and the second conductor segment 130', and the four

LED segments

102 and 104 are the four segments respectively. Also, in the present embodiment, the number of

LED segments

102, 104 is 1 more than the number of conductor segments.

As shown in fig. 10B, in a spatial rectangular coordinate system XYZ, the Z axis is parallel to the stem, and in the present embodiment, the

electrodes

110, 112 are located between the highest point and the lowest point of the LED filament 100 in the Z direction. The highest point is located at the first conductor segment 130 'that is highest in the Z direction, and the lowest point is located at the second conductor segment 130' that is lowest in the Z direction. The lower second conductor segments 130' represent closer to the burner 16 than the

electrodes

110, 112, while the higher first conductor segments 130 represent farther from the burner 16 than the

electrodes

110, 112. Viewed in the YZ plane (see fig. 10B), the

electrodes

110, 112 may be connected to one another in a line LA, two of the first, higher conductor segments 130 above the line LA and one of the second, lower conductor segments 130' below the line LA. In other words, the number of first conductor segments 130 located above the line LA connecting the

electrodes

110, 112 is 1 more than the number of second conductor segments 130' located below the line LA in the Z direction. It can also be said that the number of first conductor segments 130 remote from the burner 16 with respect to the

electrodes

110, 112 is 1 more than the number of second conductor segments 130' close to the burner 16 with respect to the

electrodes

110, 112, as a whole. When the LED filament 100 is projected on the YZ plane (see fig. 10B), at least one intersection point exists between the projection of the

LED segments

102 and 104 and the line LA connecting the

electrodes

110 and 112. In the present embodiment, on the YZ plane, the straight line LA formed by the

electrodes

110 and 112 respectively intersects the projections of the two LED segments 104, so that two intersection points exist between the straight line LA and the projections of the two adjacent LED segments 104.

As shown in fig. 10C, in the present embodiment, if the LED filament 100 is projected on the XZ plane (see fig. 10C), the projections of the two opposing

LED segments

102 and 104 are overlapped with each other. In some embodiments, the projections of the opposing two

LED segments

102, 104 onto a particular plane may be parallel to each other.

As shown in fig. 10D, in the present embodiment, if the LED filament 100 is projected on the XY plane (see fig. 10D), the projections of the

electrodes

110 and 112 on the XY plane may be connected to form a straight line LB, and the projections of the first conductor segment 130 and the second conductor segment 130 'on the XY plane do not intersect or overlap with the straight line LB, and the projections of the first conductor segment 130 and the second conductor segment 130' on the XY plane are located on one side of the straight line LB. For example, as shown in fig. 10D, the projections of the first conductor segments 130 and the second conductor segments 130' on the XY plane are located above the straight line LB.

As shown in fig. 10B to 10D, in the present embodiment, the projection lengths of the LED filament 100 on three projection surfaces perpendicular to each other have a designed ratio to make the illumination more uniform. For example, the projection of the LED filament 100 on a first projection plane (e.g., XY plane) has a length of L1, the projection of the LED filament 100 on a second projection plane (e.g., YZ plane) has a length of L2, and the projection of the LED filament 100 on a third projection plane (e.g., XZ plane) has a length of L3. The first projection plane, the second projection plane and the third projection plane are perpendicular to each other, and the normal line of the first projection plane is parallel to the axis of the LED bulb 40a from the center of the lamp housing 12 to the center of the lamp head 16. Further, the projection of the LED filament 100 on the XY plane can be seen in fig. 10D, the projection thereof will appear like an inverted U, and the total length of the projection of the LED filament 100 on the XY plane is the length L1; the projection of the LED filament 100 on the YZ plane can be shown in fig. 10B, the projection will appear like an inverted W shape, and the total length of the projection of the LED filament 100 on the YZ plane is length L2; the projection of the LED filament 100 on the XZ plane can be seen in fig. 10C, and the projection appears like an inverted V shape, and the total length of the projection of the LED filament 100 on the XZ plane is the length L3. In the present embodiment, the length L1: length L2: length L3 is approximately equal to 1: 1: 0.9. in some embodiments, length L1: length L2: length L3 is approximately equal to 1: 0.5 to 1: 0.6 to 0.9. For example, if the ratio of the length L1, the length L2, and the length L3 is closer to 1: 1:1, the more uniform the illumination effect of the single LED filament 100 in the LED bulb 40a is, the better the full-cycle light effect is.

In some embodiments, the projected length of the LED filament 100 in the XZ plane or in the YZ plane is, for example, but not limited to, the minimum of the height difference of the first conductor segment 130, the second conductor segment 130' in the Z direction multiplied by the quantity value of the

LED segments

102, 104 or the minimum of the height difference of the highest point and the lowest point of the LED filament in the Z direction multiplied by the quantity value of the

LED segments

102, 104. In the present embodiment, the total length of the LED filament 100 is about 7 to 9 times the total length of the first conductor segment 130 or the second conductor segment 130'.

In the present embodiment, the LED filament 100 can be bent to form various curves through the first conductor segment 130 and the second conductor segment 130', which not only increases the aesthetic feeling of the whole LED bulb 40a in appearance, but also makes the light emitted from the LED bulb 40a more uniform, thereby achieving better illumination effect.

Referring to fig. 11A and 11B to 11D, fig. 11A is a schematic diagram of an LED bulb 40h according to an embodiment of the invention, and fig. 11B to 11D are a side view, another side view and a top view of the LED bulb 40h of fig. 11A, respectively. In the present embodiment, the LED bulb 40h includes a lamp housing 12, a base 16 connected to the lamp housing 12, a stem 19, a rod 19a, and a single LED filament 100. The LED filament 100 includes two

electrodes

110, 112 at both ends, two LED segments 102, and a single conductor segment 130. In addition, the LED bulb 40h and the single LED filament 100 disposed in the LED bulb 40h may refer to the LED bulb, the LED filament and the related descriptions thereof in the foregoing embodiments, wherein the same or similar components and the connection relationship between the components are not described in detail.

As shown in fig. 11A to 11D, in the present embodiment, there is one conductor segment 130 of the LED filament 100, and there are two LED

segments

102 and 104, and every two

adjacent LED segments

102 and 104 are connected through the conductor segment 130, and the LED filament 100 is curved in an arc shape in a bending state at a highest point, that is, the

LED segments

102 and 104 are curved in an arc shape at the highest point of the LED filament 100, and the conductor segment is also curved in an arc shape at a low point of the LED filament. The LED filament 100 may be defined as a succession of segments following each bent conductor segment 130, with the

individual LED segments

102, 104 forming corresponding segments.

Moreover, since the LED filament 100 employs a flexible base layer, and the flexible base layer preferably employs an organic silicon modified polyimide resin composition, the

LED segments

102 and 104 themselves also have a certain degree of bending capability. In the present embodiment, the two LED segments 102 are bent to form an inverted U shape, and the conductor segment 130 is located between the two LED segments 102, and the bending degree of the conductor segment 130 is the same as or greater than that of the LED segments 102. That is, the two LED segments 102 are bent into an inverted U shape at the high point of the filament and have a bending radius R1, and the conductor segment 130 is bent at the low point of the filament LED filament 100 and have a bending radius R2, wherein R1 is greater than R2. By virtue of the arrangement of the conductor segments 130, the LED filament 100 can be bent with a small turning radius in a limited space. In one embodiment, the bending points of the

LED segments

102 and 104 are at the same height in the Z-direction. In addition, the rod 19a of the present embodiment has a lower height in the Z direction than the rod 19a of the previous embodiment, and the height of the rod 19a corresponds to the height of the conductor segment 130. For example, the lowest portion of the conductor segment 130 may be connected to the top of the rod 19a, so that the overall shape of the LED filament 100 is not easily deformed. In various embodiments, the conductor segments 130 can be connected to each other through a through hole in the top of the upright rod 19a, or the conductor segments 130 can be glued to the top of the upright rod 19a and connected to each other, but is not limited thereto. In one embodiment, the conductor segment 130 and the vertical rod 19a can be connected by a guide wire, for example, a guide wire is led out from the top of the vertical rod 19a to connect the conductor segment 130.

As shown in fig. 11B, in the present embodiment, in the Z direction, the height of the conductor segment 130 is higher than the two

electrodes

110 and 112, and the two LED segments 102 extend upward from the two

electrodes

110 and 112 to the highest point, and then bend and extend downward to the conductor segment 130 connecting the two LED segments 102. As shown in fig. 11C, in the present embodiment, the profile of the LED filament 100 in the XZ plane is similar to a V shape, that is, the two LED segments 102 extend upward and outward in an oblique manner, and after being bent at the highest point, extend downward and inward in an oblique manner to the conductor segment 130. As shown in fig. 11D, in the present embodiment, the profile of the LED filament 100 in the XY plane has an S-shape. As shown in fig. 11B and 11D, in the present embodiment, the conductor segment 130 is located between the

electrodes

110, 112. As shown in fig. 11D, in the present embodiment, the bending point of the LED segment 102, the bending point of the LED segment 104, and the

electrodes

110 and 112 are located on a circumference with the conductor segment 130 as a center on the XY plane.

Referring to fig. 12, fig. 12 is a schematic view of an output light spectrum of an LED bulb lamp according to an embodiment of the invention. In this embodiment, the LED bulb may be any one of the LED bulbs disclosed in the previous embodiments, and the LED bulb is provided with any one single LED filament disclosed in the previous embodiments. The light emitted by the LED bulb is measured by the spectrum measuring apparatus, and the spectrum diagram shown in fig. 12 can be obtained. From the spectrum diagram, the spectrum of the LED bulb lamp is mainly distributed between wavelengths of 400nm and 800nm, and three peaks P1, P2 and P3 appear at three positions in the range. The peak P1 is between about 430nm and 480nm, the peak P2 is between about 580nm and 620nm, and the peak P3 is between about 680nm and 750 nm. In intensity, the intensity of peak P1 is less than the intensity of peak P2, and the intensity of peak P2 is less than the intensity of peak P3. As shown in fig. 12, such a spectral distribution is close to that of a conventional incandescent filament lamp and also close to that of natural light.

The term "one LED filament" and "one LED filament" as used herein refers to a single LED filament structure which is formed by connecting the aforementioned conductor segments and LED segments together, has the same and continuous light conversion layer (including the same and continuously formed top layer or bottom layer), and has two conductive electrodes electrically connected to the bulb conductive support only at two ends.

The above description of the embodiments has specifically disclosed a multi-segment dimmable configuration for one filament by combining two, three and four segments of LED segments. The configuration of multi-segment dimming of one filament by combining more than four LED segments can be easily deduced by those skilled in the art with reference to the above description.

The features of the various embodiments of the invention described above may be combined and changed arbitrarily without being mutually exclusive and are not limited to a specific embodiment. Such as those described in the embodiment of fig. a, although features not described in the embodiment of fig. C may also be included in the embodiment of fig. a, it will be apparent to those of ordinary skill in the art that such features may be applied to fig. C without inventive faculty based on the description of fig. a.

While the invention has been described in terms of preferred embodiments, it will be understood by those skilled in the art that the examples are intended in a descriptive sense only and not for purposes of limitation. It should be noted that equivalent variations and substitutions to those of the embodiments are intended to be included within the scope of the present invention.

Claims

1. An LED bulb lamp, characterized by comprising:

the lamp shell is filled with inert gas;

the lamp holder is connected with the lamp shell;

the LED comprises a plurality of LED sections, each LED section comprises at least two LED chips which are electrically connected with each other, and the shortest distance between the two LED chips respectively positioned in the two adjacent LED sections is larger than the distance between the two adjacent LED chips in the single LED section;

the conductor section is positioned between two adjacent LED sections and comprises a conductor for connecting the two adjacent LED sections;

the electrode is electrically connected with the LED section; and

a light conversion layer coated on at least two sides of the LED chip or the electrode and exposing a portion of the electrode,

the light conversion layer comprises at least one top layer and one base layer, the top layer and the base layer are respectively positioned on two sides of the LED chip or the electrode, the base layer is formed by coating and drying an organic silicon modified polyimide resin composition, the composition comprises organic silicon modified polyimide containing a repeating unit represented by the following general formula (I), a heat curing agent, fluorescent powder and heat dissipation particles, and the heat curing agent is epoxy resin, isocyanate or a bisoxazoline compound;

in the general formula (I), Ar¹Is a 4-valent organic group having a benzene ring or alicyclic hydrocarbon structure, Ar²Is a 2-valent organic group, R is independently selected from methyl or phenyl, and n is 1-5;

the spectrum of the LED bulb lamp has three peaks P1, P2 and P3, the peak P1 is between 430nm and 480nm, the peak P2 is between 580nm and 620nm, the peak P3 is between 680nm and 750nm, the intensity of the peak P1 is smaller than that of the peak P2, and the intensity of the peak P2 is smaller than that of the peak P3.

2. The LED bulb lamp according to claim 1, wherein the maximum thickness of the LED chip in the radial direction of the LED filament is H, the thickness of the conductor in the radial direction of the LED filament is 0.5H-1.4H, the top layer of the LED segment has the largest diameter D2 in the radial direction of the LED filament, and the top layer of the conductor segment has the largest diameter D1 in the radial direction of the LED filament, D2 being larger than D1.

3. The LED bulb lamp of claim 2, wherein a solid crystal glue is arranged between the LED chip and the base layer, light emitted by the LED chip passes through an A-F interface, the A interface is an interface between GaN in the LED chip and the top layer, the B interface is an interface between the top layer and the inert gas, the C interface is an interface between a substrate in the LED chip and the solid crystal glue, the D interface is an interface between the solid crystal glue and the base layer, the E interface is an interface between the base layer and the inert gas, the F interface is an interface between the base layer and the top layer, when the light emitted by the LED chip passes through the A-F interface, refractive indexes of two substances in any interface are n1 and n2, and | n1-n2| is less than 1.0.

4. The LED bulb lamp of claim 3, wherein the upper surface of the base layer comprises a first region and a second region, the second region comprising foam cells, the first region having a surface roughness less than a surface roughness of the second region, the lower surface of the base layer comprising a third region having a surface roughness greater than a surface roughness of the first region.

5. The LED bulb lamp as claimed in claim 4, wherein the LED chips in the LED segment have an emission angle α in the axial direction of the LED filament, an emission angle β in the radial direction of the LED filament, a distance H from the upper surface of the LED chip to the outer surface of the top layer in the radial direction of the LED filament, a length C of the LED segment in the length direction of the LED filament, a width W1 of the base layer, H being in the range of a ≦ H ≦ 10C/2tan0.5 α, a being the greater of 0.5C/2tan0.5 α and W1/2tan0.5 β.

6. The LED bulb lamp according to claim 5, wherein H is in the range A ≦ H ≦ 2C/2tan0.5 α, A being the larger of C/2tan0.5 α, W1/2tan0.5 β.

7. The LED bulb lamp of claim 1, wherein the Ar is¹Is a 4-valent organic group with a benzene ring structure or an alicyclic hydrocarbon structure containing active hydrogen functional groups, wherein the active hydrogen functional groups are any one of hydroxyl, amino, carboxyl or thiol, and Ar is²The functional group is a 2-valent organic group containing active hydrogen, and the active hydrogen functional group is any one of hydroxyl, amino, carboxyl or thiol.

8. The LED bulb lamp of claim 7, wherein the Ar is¹From dianhydride of said Ar²The siloxane content of the organic silicon modified polyimide is 20-75 wt% from diamine.

9. The LED bulb lamp according to claim 8, wherein the conductor segments comprise a first conductor segment and a second conductor segment, the LED filament is projected on an XY plane, the projections of the electrodes on the XY plane are connected to form a straight line, the projections of the first and second conductor segments on the XY plane do not intersect or overlap with the straight line, and the projections of the first and second conductor segments on the XY plane are located on one side of the straight line.

10. The LED bulb according to claim 9, wherein the number of the first conductor segments located above a line on which the electrodes are connected is more than 1 than the number of the second conductor segments located below the line in a YZ plane.