Large-area LED light source packaging structure and packaging method

Abstract

The present invention discloses a large-area LED light source packaging structure and a packaging method. The large-area LED light source packaging structure includes a substrate, an LED chip, and a heat conduction connection structure disposed between the LED chip and the substrate. The heat conduction connection structure includes a plurality of insulating heat conductors spaced apart from each other. One end of each insulating heat conductor is bonded to the LED chip through an insulating heat conduction adhesive, and the other end is thermally connected to the substrate through a heat conduction solder, thereby forming a plurality of insulating heat conduction channels between the substrate and the LED chip. In the large-area LED light source packaging structure provided by the present invention, the distribution pattern of the plurality of insulating heat conductors matches the warping structure of the LED chip. One end of the insulating heat conductor is pasted on the substrate by the heat conduction solder, thereby forming a good insulating heat conduction channel, and solving the problem of uneven heat dissipation caused by the warping of the large-area LED chip. Since the contact area between a single insulating heat conductor and the LED chip is small, the thermal expansion stress can be reduced, and the reliability of the device can be improved.

Description

Technical Field

[0001] The present invention relates to an LED light source packaging structure, and particularly to a large-area LED light source packaging structure and a packaging method, belonging to the field of semiconductor technology. Background Art

[0002] With the increase in the area of LED chips, the warpage of the chips will increase accordingly. Different distances between various parts of the chips and the substrate result in different thermal resistances at various parts, thereby leading to uneven heat dissipation and affecting the device performance. Summary of the Invention

[0003] The main purpose of the present invention is to provide a large-area LED light source packaging structure and a packaging method to overcome the deficiencies in the prior art.

[0004] To achieve the foregoing invention purpose, the technical solutions adopted by the present invention include:

[0005] An embodiment of the present invention provides a large-area LED light source packaging structure, which includes a substrate, an LED chip, and a heat conduction connection structure disposed between the LED chip and the substrate. The heat conduction connection structure includes a plurality of insulating heat conductors spaced apart from each other. One end of the insulating heat conductor is bonded to the LED chip through an insulating heat conduction adhesive, and the other end is thermally connected to the substrate through a heat conduction solder, thereby forming a plurality of insulating heat conduction channels between the substrate and the LED chip.

[0006] Further, the heat conduction connection structure further includes a plurality of metal heat conductors that are electrically isolated from each other and disposed at one end of at least one of the insulating heat conductors. One end of the insulating heat conductor is thermally connected to the LED chip through a plurality of metal heat conductors that are electrically isolated from each other.

[0007] Further, the metal heat conductor is in an island shape.

[0008] Further, the shape of the insulating heat conductor includes a cuboid shape or a column shape.

[0009] In some more specific implementation schemes, the LED chip is a flip chip. The first surface of the flip chip having electrodes is thermally connected to the substrate through the heat conduction connection structure. The second surface of the flip chip is a light-emitting surface, and the first surface and the second surface are disposed opposite to each other.

[0010] Further, an insulating layer is disposed on the surface of the substrate, and a conductive layer is disposed on the insulating layer. The electrodes of the LED chip are electrically connected to the conductive layer through a hard conductive material or a conductive lead.

[0011] In some more specific embodiments, the LED chip is a flip chip, and one end of the insulating heat conductor is thermally connected to the LED chip through a plurality of metal heat conductors that are electrically isolated from each other. The distance c between two adjacent metal heat conductors is c≥1 μm. At least a pair of P electrodes and N electrodes of the LED chip are thermally connected to the front surface of the substrate through the plurality of spaced metal heat conductors. The maximum dimension a of any metal heat conductor in the direction parallel to the surface of the LED chip having electrodes is less than the minimum distance d between the P electrode and the N electrode, and d>a≥2μm.

[0012] In some more specific embodiments, the LED chip is a front-mounted chip. The second surface of the front-mounted chip is thermally connected to the substrate through a thermal connection structure. The first surface of the front-mounted chip is a light-emitting surface and has electrodes, and the first surface and the second surface are arranged back to back.

[0013] Further, an insulating layer is provided on the surface of the substrate, and a conductive layer is provided on the insulating layer. The electrodes of the LED chip are electrically connected to the conductive layer through a hard conductive material or a conductive lead.

[0014] Further, the LED chip as a whole has a warped structure, and the distribution pattern of the plurality of insulating heat conductors matches the warped structure.

[0015] The embodiment of the present invention also provides a method for packaging a large-area LED light source, which includes:

[0016] Bonding one end of a plurality of insulating heat conductors that are spaced apart from each other to the LED chip through an insulating heat-conducting adhesive, so that the distribution pattern of the plurality of insulating heat conductors matches the overall structure of the LED chip; and

[0017] Thermally connecting the other ends of the plurality of insulating heat conductors to the substrate through a thermally conductive solder, so as to form a plurality of insulating heat-conducting channels between the substrate and the LED chip.

[0018] Further, the substrate is a metal substrate or a non-metal substrate. The material of the metal substrate includes aluminum or copper, and the material of the non-metal substrate includes ceramics, but is not limited thereto.

[0019] Compared with the prior art, in the large-area LED light source packaging structure provided by the embodiment of the present invention, a plurality of insulating heat conductors are arranged between the substrate and the high-voltage, high-power and large-size LED chips. Among them, the distribution pattern of the plurality of insulating heat conductors matches the warping structure of the LED chips. One end of the insulating heat conductor is pasted on the substrate by a heat-conducting solder, thereby forming a good insulating heat conduction channel, which well solves the problem of uneven heat dissipation caused by the warping of the large-area LED chips; and, because the contact area between a single insulating heat conductor and the LED chip is small, the thermal expansion stress can be reduced, and the reliability of the device can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic diagram of the principle structure of a large-area LED light source packaging structure in a typical embodiment of the present invention;

[0021] Figure 2 is a schematic diagram of the structure of a large-area LED light source packaging structure in Embodiment 1 of the present invention;

[0022] Figure 3 is a schematic diagram of the structure of a large-area LED light source packaging structure in Embodiment 2 of the present invention;

[0023] Figure 4 is a schematic diagram of the structure of a large-area LED light source packaging structure in Embodiment 3 of the present invention;

[0024] Figure 5 is a schematic diagram of the structure of a large-area LED light source packaging structure in Embodiment 4 of the present invention;

[0025] Figure 6 is a schematic diagram of the structure of the connection part between the chip and the metal heat conductor in a large-area LED light source packaging structure in Embodiment 3 or 4 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] In view of the deficiencies in the prior art, the inventor of this case has proposed the technical solution of the present invention through long-term research and a large number of practices. The following will further explain the technical solution, its implementation process and principle, etc.

[0027] Embodiment 1

[0028] Please refer to Figure 1 and Figure 2, a large-area LED light source packaging structure, including a substrate 10, an LED chip 20, and a heat conduction connection structure 30 disposed between the substrate 10 and the LED chip 20. The heat conduction connection structure 30 includes a plurality of insulating heat conductors 31 spaced apart from each other. One end of the insulating heat conductor 31 is bonded to the LED chip 20 via an insulating heat conduction adhesive 40, and the other end is thermally connected to the substrate 10 via a heat conduction solder 50, thereby forming a plurality of insulating heat conduction channels between the substrate 10 and the LED chip 20; the LED chip is integrally in a warped structure, and the distribution pattern of the plurality of insulating heat conductors 31 matches the warped structure, that is, one end of the plurality of insulating heat conductors 31 forms an arc surface matching the surface of the LED chip; and, an electrode lead-out structure is further disposed on the substrate 10, and the electrodes of the LED chip are electrically connected to the electrode lead-out structure.

[0029] Specifically, the LED chip 20 is a flip chip. The LED chip 20 has a first surface and a second surface disposed back to back. Electrodes are provided on the first surface of the LED chip 20. The LED chip 20 is connected and combined with the insulating heat conductor 31 with the first surface having electrodes. The electrode lead-out structure includes a solder 63 and a pad 65. The solder 63 and the pad 65 are electrically connected via a conductive layer 51. The solder 63 is electrically connected to the electrodes of the LED chip via a hard conductive material (such as a conductive metal sheet) 64; wherein, an insulating layer 62 is disposed between the electrode lead-out structure and the substrate 10, and an insulating layer 61 is further disposed on the upper surface of the conductive layer 51.

[0030] Specifically, the structure or shape of the insulating heat conductor 31 is a cuboid, a cube, a cylinder, a frustum of a cone, a prism, etc. The plurality of insulating heat conductors 31 can be of equal length or unequal length.

[0031] Specifically, the bonding method between the insulating heat conductor 31 and the LED chip 20 can be bonding with an insulating connection adhesive, a self-aligning isolation technique, etc.; the bonding method between the insulating heat conductor 31 and the substrate 10 can be reflow soldering, silver paste, solder, etc.

[0032] Among them, the substrate 10 can be a metal substrate or a non-metal substrate. The material of the metal substrate can be a metal with good thermal conductivity such as aluminum or copper, and the material of the non-metal substrate includes ceramics, etc.

[0033] More specifically, one end of the insulating heat conductor 31 is adaptively pasted onto the surface of the high-voltage, high-power, large-size LED chip. One ends of a plurality of insulating heat conductors 31 form a curved surface adapted to the surface of the LED chip. Then, the other ends of the insulating heat conductors 31 are pasted onto the substrate through heat-conducting solder, thereby forming a good insulating heat conduction channel, which well solves the problem of uneven heat dissipation caused by the warping of the large-area LED chip. Moreover, since the contact area between a single insulating heat conductor and the LED chip is small, the thermal expansion stress can be reduced, and the reliability of the device can be improved.

[0034] Embodiment 2

[0035] Please refer to Figure 1 and Figure 3 In this embodiment, the structure of the large-area LED light source packaging structure is basically the same as that of the large-area LED light source packaging structure in Embodiment 1. The difference is that: in this embodiment, the LED chip 20 is a flip-chip, the insulating heat conductor 31 is connected to the second surface of the LED chip 20, and a soft conductive connecting wire is used to electrically connect the electrodes of the LED chip to the solder 63.

[0036] Embodiment 3

[0037] Please refer to Figure 4 A large-area LED light source packaging structure includes a substrate 10, an LED chip 20, and a heat conduction connection structure 30 disposed between the substrate 10 and the LED chip 20. The heat conduction connection structure 30 includes a plurality of insulating heat conductors 31 spaced apart from each other. At one end of the insulating heat conductor 31, a plurality of metal heat conductors 32 electrically isolated from each other are provided. One end of the metal heat conductor 32 is welded to the LED chip 20, and the other end of the insulating heat conductor 31 is thermally connected to the substrate 10 through heat-conducting solder 50, thereby forming a plurality of insulating heat conduction channels between the substrate 10 and the LED chip 20 (each insulating heat conduction channel in this embodiment is mainly composed of an insulating heat conductor and a plurality of metal heat conductors disposed at one end of the insulating heat conductor); the LED chip as a whole has a warped structure, and the distribution patterns of the plurality of insulating heat conductors 31 and the metal heat conductors 32 match the warped structure; and, an electrode lead-out structure is further provided on the substrate 10, and the electrodes of the LED chip are electrically connected to the electrode lead-out structure.

[0038] Specifically, the LED chip in this embodiment is a flip chip. The LED chip 20 has a first surface and a second surface disposed back to back. Electrodes are provided on the first surface of the LED chip 20. The electrode lead-out structure includes solder 63 and a pad 65. The solder 63 and the pad 65 are electrically connected through a conductive layer 51. The solder 63 is electrically connected to the electrode of the LED chip through a hard conductive material (conductive metal sheet) 64. Among them, an insulating layer 62 is provided between the electrode lead-out structure and the substrate 10, and an insulating layer 61 is also provided on the upper surface of the conductive layer 51.

[0039] More specifically, please refer to Figure 6 , the LED chip 20 includes an insulating layer 25, a P-type GaN layer 24, an active layer 23, an N-type GaN layer 22, and a substrate 21 stacked in sequence. A P electrode 26 and an N electrode 27 are provided at intervals on the insulating layer 25. A part of the P electrode 26 penetrates through the insulating layer 25 and is connected to the P-type GaN layer 24. A part of the N electrode 27 continuously penetrates through the insulating layer 25, the P-type GaN layer 24, and the active layer 23 and is provided in the N-type GaN layer 22. The distance between the P electrode 26 and the N electrode 27 is d. The P electrode 26 and the N electrode 27 are respectively thermally connected to at least one metal heat conductor 32, and at least the P electrode 26 and the N electrode 27 are also electrically connected to the electrode lead-out structure.

[0040] Specifically, the metal heat conductor 32 may be a cuboid structure, with a width of a, a height of b, and a distance of c between two adjacent metal heat conductors 32. Among them, a≥2μm, c≥1μm, and the distance d between the P electrode 26 and the N electrode 27 > the width a of the metal heat conductor 32.

[0041] It should be noted that the aforementioned "the distance d between the P electrode 26 and the N electrode 27 > the width a of the metal heat conductor 32" can be understood that the distance between the P electrode and the N electrode and the width of the metal heat conductor are the distances in the same reference direction, and this direction can be the width direction of the metal heat conductor; when the metal heat conductor is a cylindrical or frustum structure, the preset direction can be the direction parallel to the side surface of the LED chip with electrodes.

[0042] Since the metal heat conductors are electrically isolated from each other, and the width of the metal heat conductor is smaller than the distance between the P and N electrodes, no short-circuit problem will occur, thereby reducing the requirement for the device alignment accuracy. The alignment error is half of the area of the P and N electrodes, reducing the cost; among them, the contact area between a single metal heat conductor and the P electrode or the N electrode is small, and the thermal stress of the contact surface is greatly reduced, increasing the reliability of the device.

[0043] Specifically, the structure or shape of the insulating heat conductor 31 is cuboid, cube, cylindrical, frustum-shaped or prismatic, etc. A plurality of insulating heat conductors 31 can be of equal length.

[0044] Specifically, the bonding method between the metal heat conductor 32 and the LED chip 20 can be welding, pasting with insulating connection glue, self-alignment isolation technology, etc.; the bonding method between the insulating heat conductor 31 and the substrate 10 can be reflow soldering, silver paste, solder, etc. Self-alignment isolation technology: Since there are electrically isolated metal islands (i.e., island-shaped metal heat conductors) on the substrate with a size smaller than the chip electrode pitch, when the flip chip is welded to the substrate, the chip electrodes and the metal islands can achieve self-alignment welding of the chip without precise alignment and there is no short circuit between the electrodes. Among them, the substrate 10 can be a metal substrate or a non-metal substrate. The material of the metal substrate can be a metal with good thermal conductivity such as aluminum or copper, and the material of the non-metal substrate includes ceramics, etc.

[0045] More specifically, a plurality of metal heat conductors 32 can be provided at one end of each insulating heat conductor 31 in advance, and then the hot end of the metal conductor is adaptively bonded to the surface of the high-voltage, high-power, large-size LED chip. One end of the plurality of metal heat conductors 32 forms a curved surface adapted to the surface of the LED chip. Then, the other end of the insulating heat conductor 31 is pasted on the substrate through a heat-conducting solder, thereby forming a good insulating heat-conducting channel, which well solves the problem of uneven heat dissipation caused by the warping of the large-area LED chip; and, since the contact area between a single insulating heat conductor and the LED chip is small, the thermal expansion stress can be reduced, and the reliability of the device can be improved.

[0046] Example 4

[0047] Please refer to Figure 5 , the structure of the large-area LED light source packaging structure in this embodiment is basically the same as that of the large-area LED light source packaging structure in Example 3. The difference is that: the LED chip 20 in this embodiment is a face-up chip, one end of the metal heat conductor 32 is connected and bonded to the second surface of the LED chip 20 without electrodes, and a soft conductive connection wire is used to electrically connect the electrodes of the LED chip 20 and the solder 63.

[0048] In addition, it should be noted that the plurality of insulating conductors 31 used in Examples 1-4 are all insulating heat conductors of equal length; in some more specific implementation schemes, non-equal-length insulating heat conductors can also be used. First, one end of the plurality of insulating heat conductors 31 is connected and bonded to the substrate, and the surface where the other end of the plurality of insulating heat conductors 31 (when there is a metal heat conductor, this should be the end of the metal heat conductor) is located is a curved surface matching the surface of the chip. Then, the chip is connected and bonded to the insulating heat conductor 31 (when there is a metal heat conductor, this should be the metal heat conductor).

[0049] Alternatively, in some more specific embodiments, a substrate having the same warping structure as that of the LED chip can also be used, and an insulating heat conductor or an insulating heat conductor and a metal heat conductor are provided between the LED chip and the substrate to form a heat conduction channel, thereby solving the problem of uneven heat dissipation caused by the warping of the large-area LED chip.

[0050] It should be noted that the material of the insulating heat conductor in the embodiments of the present invention can be a material with good heat conduction performance, such as ceramics.

[0051] Compared with the prior art, in the large-area LED light source packaging structure provided by the embodiments of the present invention, a plurality of insulating heat conductors are provided between the substrate and the high-voltage, high-power, large-size LED chip. Among them, the distribution pattern of the plurality of insulating heat conductors matches the warping structure of the LED chip. One end of the insulating heat conductor is pasted on the substrate by a heat-conducting solder, thereby forming a good insulating heat conduction channel, which well solves the problem of uneven heat dissipation caused by the warping of the large-area LED chip; and, since the contact area between a single insulating heat conductor and the LED chip is small, the thermal expansion stress can be reduced, and the reliability of the device can be improved.

[0052] It should be understood that the above embodiments are only used to illustrate the technical concept and features of the present invention, and their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and should not be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. A large-area LED light source packaging structure, characterized in that it includes a substrate, an LED chip, and a heat-conducting connection structure disposed between the LED chip and the substrate. The heat-conducting connection structure includes a plurality of insulating heat-conducting bodies spaced apart from each other. One end of each insulating heat-conducting body is bonded to the LED chip via an insulating heat-conducting adhesive, and the other end is heat-conductively connected to the substrate via a heat-conducting solder, thereby forming a plurality of insulating heat-conducting channels between the substrate and the LED chip; the overall shape of the LED chip is a warped structure, and the distribution pattern of the plurality of insulating heat-conducting bodies matches the warped structure; the heat-conducting connection structure further includes a plurality of metal heat-conducting bodies that are electrically isolated from each other and disposed at one end of at least one of the insulating heat-conducting bodies. One end of the insulating heat-conducting body is heat-conductively connected to the LED chip via the plurality of metal heat-conducting bodies that are electrically isolated from each other.

2. The large-area LED light source packaging structure according to claim 1, characterized in that: the metal heat-conducting body is in an island shape.

3. The large-area LED light source packaging structure according to claim 1 or 2, characterized in that: the shape of the insulating heat-conducting body includes a cuboid shape or a cylindrical shape.

4. The large-area LED light source packaging structure according to claim 1, characterized in that: the LED chip is a flip chip. The first surface of the flip chip having electrodes is heat-conductively connected to the substrate via the heat-conducting connection structure. The second surface of the flip chip is a light-emitting surface, and the first surface and the second surface are disposed opposite to each other.

5. The large-area LED light source packaging structure according to claim 4, characterized in that: an insulating layer is disposed on the surface of the substrate, and a conductive layer is disposed on the insulating layer. The electrodes of the LED chip are electrically connected to the conductive layer via a hard conductive material or a conductive lead.

6. The large-area LED light source packaging structure according to claim 1, characterized in that: the LED chip is a direct chip. The second surface of the direct chip is heat-conductively connected to the substrate via the heat-conducting connection structure. The first surface of the direct chip is a light-emitting surface and has electrodes, and the first surface and the second surface are disposed opposite to each other.

7. The large-area LED light source packaging structure according to claim 6, characterized in that: an insulating layer is disposed on the surface of the substrate, and a conductive layer is disposed on the insulating layer. The electrodes of the LED chip are electrically connected to the conductive layer via a hard conductive material or a conductive lead.

8. A large-area LED light source packaging method, characterized in that it includes: bonding one end of a plurality of insulating heat-conducting bodies spaced apart from each other to the LED chip via an insulating heat-conducting adhesive, so that the distribution pattern of the plurality of insulating heat-conducting bodies matches the overall structure of the LED chip; and heat-conductively connecting the other ends of the plurality of insulating heat-conducting bodies to the substrate via a heat-conducting solder, thereby forming a plurality of insulating heat-conducting channels between the substrate and the LED chip.

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