LED packaging structure and packaging method

Abstract

The present invention discloses an LED packaging structure and packaging method, which relate to the field of semiconductor technology. The LED packaging structure includes a substrate, an LED chip, and a packaging adhesive; wherein the front side of the substrate is provided with a front circuit, the back side of the substrate is provided with a back circuit, the LED chip includes at least two LED flip chips, and the LED flip chips are electrically connected to the front circuit, and the packaging adhesive covers the LED chip; the front circuit includes multiple solid crystal areas and connection areas, the number of solid crystal areas is the same as the number of LED chips, connection areas are provided between different solid crystal areas, and discontinuities are provided on the connection areas. By connecting different discontinuities, different LED flip chips can be connected in series or in parallel. By implementing the present invention, multiple series and parallel connection modes of LED chips can be realized, and LED packaging structures with multiple voltage specifications can be obtained. The LED packaging structure has strong versatility and good performance.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to an LED packaging structure and a packaging method. Background Art

[0002] Conventional LED packaging structures consist of a face-mounted chip, a bracket, metal wire, and fluorescent adhesive. High-voltage LEDs integrate multiple LED chips in series within a single package, connected by wirebonds. This process is extremely inefficient and, in addition, wirebonds offer poor thermal shock resistance. Wirebonds also increase resistance, heat generation, and light efficiency, leading to higher costs. Using a single high-voltage flip-chip package to create a high-voltage LED results in high chip cost and low brightness. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide an LED packaging structure and packaging method, which can realize multiple series and parallel connection modes of LED chips, obtain LED packaging structures with multiple voltage specifications, have strong versatility, and the obtained LED packaging structure has good performance.

[0004] In order to solve the above problems, the present invention discloses an LED packaging structure, comprising a substrate, an LED chip, and a packaging adhesive; wherein the front surface of the substrate is provided with a front circuit, the back surface of the substrate is provided with a back circuit, the LED chip comprises at least two LED flip chips and the LED chip is electrically connected to the front circuit, and the packaging adhesive covers the LED chip;

[0005] The front circuit includes multiple solid crystal areas and connecting areas. The number of the solid crystal areas is the same as the number of the LED chips. Connecting areas are provided between different solid crystal areas. Discontinuities are provided on the connecting areas. By connecting different discontinuities, series or parallel connection between different LED flip chips is achieved.

[0006] As an improvement to the above technical solution, the connection area includes a plurality of connection lines, the connection lines are disconnected at the discontinuity portion, and the length of the discontinuity portion is 0.15 mm to 0.35 mm;

[0007] Conductive points are formed by dotting conductive material on the discontinuous portion to achieve conduction between the connecting line and the discontinuous portion.

[0008] As an improvement of the above technical solution, the ratio of the length of the conductive point to the length of the discontinuity is 1:(1~1.3), the ratio of the width of the conductive point to the length of the conductive point is 1:(0.8~1.2), and the ratio of the height of the conductive point to the length of the conductive point is 1:(1~1.5).

[0009] As an improvement to the above technical solution, the connection area includes a first connection line, a second connection line and a third connection line; the first pads of the plurality of crystal-bonding areas are respectively connected to the first pad on the back side through the first connection line, and the first connection line is provided with a discontinuity; the second pads of the plurality of crystal-bonding areas are respectively connected to the second pad on the back side through the second connection line, and the second connection line is provided with a discontinuity; the second pad of one crystal-bonding area is connected to the first pad of another crystal-bonding area through a third connection line, and the third connection line is provided with a discontinuity, so as to form a sequential connection of the plurality of crystal-bonding areas;

[0010] The number of the first connecting lines is N, and at least (N-1) first connecting lines are provided with discontinuities; the number of the second connecting lines is N, and at least (N-1) second connecting lines are provided with discontinuities.

[0011] As an improvement to the above technical solution, the solid crystal area includes a first solid crystal area, a second solid crystal area, a third solid crystal area and a fourth solid crystal area, and the connection area includes a first connection line, a second connection line and a third connection line; the first pads of the first solid crystal area, the second solid crystal area, the third solid crystal area and the fourth solid crystal area are respectively connected to the first pad on the back through the first connection line, and a discontinuity is provided on the first connection line; the second pads of the first solid crystal area, the second solid crystal area, the third solid crystal area and the fourth solid crystal area are respectively connected to the second pad on the back through the second connection line, and a discontinuity is provided on the second connection line; the second pad of the first solid crystal area and the first pad of the second solid crystal area, the second pad of the second solid crystal area and the first pad of the third solid crystal area, and the second pad of the third solid crystal area and the first pad of the fourth solid crystal area are respectively connected through the third connection line, and a discontinuity is provided on the third connection line;

[0012] The LED chips include a first LED flip chip, a second LED flip chip, a third LED flip chip and a fourth LED flip chip, and the first LED flip chip, the second LED flip chip, the third LED flip chip and the fourth LED flip chip are electrically connected to the first solid crystal area, the second solid crystal area, the third solid crystal area and the fourth solid crystal area respectively;

[0013] The first, second, third and fourth crystal-bonding areas are arranged in a matrix manner, and the first, second, third and fourth crystal-bonding areas are respectively arranged in the upper left area, lower left area, upper right area and lower right area of ​​the front line.

[0014] As an improvement to the above technical solution, a first line connecting the first solder pad in the first solid crystal area and the first solder pad on the back side, a second line connecting the second solder pad in the fourth solid crystal area and the second solder pad on the back side, a third line connecting the second solder pad in the first solid crystal area and the first solder pad in the second solid crystal area, a third line connecting the second solder pad in the second solid crystal area and the first solder pad in the third solid crystal area, and a third line connecting the second solder pad in the third solid crystal area and the first solder pad in the fourth solid crystal area are connected to form a series connection of a first LED flip chip, a second LED flip chip, a third LED flip chip and a fourth LED flip chip.

[0015] As an improvement to the above technical solution, the first line connecting the first solder pad in the first solid crystal area and the first solder pad on the back side, the first line connecting the first solder pad in the second solid crystal area and the first solder pad on the back side, the first line connecting the first solder pad in the third solid crystal area and the first solder pad on the back side, the first line connecting the first solder pad in the fourth solid crystal area and the first solder pad on the back side, the second line connecting the second solder pad in the first solid crystal area and the second solder pad on the back side, the second line connecting the second solder pad in the second solid crystal area and the second solder pad on the back side, the second line connecting the second solder pad in the third solid crystal area and the second solder pad on the back side, and the second line connecting the second solder pad in the fourth solid crystal area and the second solder pad on the back side are connected to form a parallel connection of the first LED flip chip, the second LED flip chip, the third LED flip chip and the fourth LED flip chip.

[0016] As an improvement to the above technical solution, a first line connecting the first solder pad in the first solid crystal area and the first solder pad on the back side, a first line connecting the first solder pad in the third solid crystal area and the first solder pad on the back side, a second line connecting the second solder pad in the second solid crystal area and the second solder pad on the back side, a second line connecting the second solder pad in the fourth solid crystal area and the second solder pad on the back side, a third line connecting the second solder pad in the first solid crystal area and the first solder pad in the second solid crystal area, and a third line connecting the second solder pad in the third solid crystal area and the first solder pad in the fourth solid crystal area are connected. The first LED flip chip and the second LED flip chip form a first series group, the third LED flip chip and the fourth LED flip chip form a second series group, and the first series group and the second series group are connected in parallel.

[0017] Accordingly, the present invention also discloses an LED packaging method for forming the above-mentioned LED packaging structure, comprising the following steps:

[0018] A substrate is provided, a front circuit is formed on the front surface of the substrate, and a back circuit is formed on the back surface of the substrate, the front circuit includes a plurality of crystal bonding areas and connection areas, connection areas are provided between different crystal bonding areas, and discontinuities are provided on the connection areas;

[0019] According to the requirements of series and parallel connection, conductive material is applied on the discontinuous parts of the preset area;

[0020] Apply conductive material on the die-bonding area and place the LED chip;

[0021] Reflow soldering to complete the electrical connection between the LED chip and the die-bonding area and the conduction of the discontinuity in the preset area;

[0022] Fluorescent glue is applied on the LED chip to complete the LED packaging.

[0023] The implementation of the present invention has the following beneficial effects:

[0024] In the LED package structure provided by the present invention, the front-side circuitry of the substrate includes multiple die-bonding areas and wiring areas. The LED chips are flip-chip mounted on the die-bonding areas. Wiring areas are provided between the different die-bonding areas, and the wiring areas are provided with discontinuities. By conducting different discontinuities, different LED chips can be connected in series or in parallel. Using the same substrate, multiple series and parallel connection modes of LED chips can be achieved, resulting in LED package structures with various voltage specifications. This provides high versatility and significantly improves the heat dissipation performance and thermal shock resistance of the resulting LED package structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 1 is a schematic structural diagram of an LED packaging structure provided by an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of the circuit arrangement of an LED packaging structure provided by one embodiment of the present invention;

[0027] Figure 3 It is the use of Figure 2 A schematic diagram of a top view of an LED package structure that implements serial connection of LED chips;

[0028] Figure 4 It is the use of Figure 2 A schematic diagram of a top view of an LED package structure that implements parallel connection of LED chips;

[0029] Figure 5 is a schematic diagram of the circuit arrangement of an LED packaging structure provided by another embodiment of the present invention;

[0030] Figure 6 It is the use of Figure 5 A schematic diagram of a top view of an LED package structure that implements serial connection of LED chips;

[0031] Figure 7 It is the use of Figure 5 A schematic diagram of a top view of an LED package structure that implements parallel connection of LED chips;

[0032] Figure 8 It is the use of Figure 5 A schematic diagram of a top view of an LED packaging structure in which LED chips are connected in series first and then in parallel;

[0033] Figure 9 1 is a schematic structural diagram of the LED packaging method after step S11 according to an embodiment of the present invention;

[0034] Figure 10 1 is a schematic structural diagram of the LED packaging method after step S12 provided in an embodiment of the present invention;

[0035] Figure 11 1 is a schematic structural diagram of the LED packaging method after step S13 according to an embodiment of the present invention;

[0036] Figure 12 3 is a schematic structural diagram of the LED packaging method after step S3 provided by an embodiment of the present invention;

[0037] Figure 13 1 is a schematic structural diagram after step S4 of the LED packaging method provided by an embodiment of the present invention;

[0038] Figure 14 1 is a schematic structural diagram of the LED packaging method after step S5 provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0039] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is described in further detail below.

[0040] like Figure 1 and Figure 2 As shown, the present invention provides an LED packaging structure, including a substrate 100, an LED chip 200 and a packaging glue 300; wherein, the front side of the substrate 100 is provided with a front circuit 110, the back side of the substrate 100 is provided with a back circuit 120, the LED chip 200 includes at least two LED flip chips and the LED chip 200 is electrically connected to the front circuit 110, and the packaging glue 300 covers the LED chip 200.

[0041] The front circuit 110 includes multiple solid crystal areas 130 and connecting areas 140. The number of the solid crystal areas 130 is the same as the number of the LED chips 200. Connecting areas 140 are provided between different solid crystal areas 130. Discontinuities 150 are provided on the connecting areas 140. By connecting different discontinuities 150, series or parallel connection between different LED chips 200 is achieved.

[0042] In the LED package structure provided by the present invention, the front circuit 110 of the substrate 100 includes multiple die-bonding areas 130 and wiring areas 140. The LED chips 200 are flip-chip mounted on the die-bonding areas 130. Wiring areas 140 are provided between different die-bonding areas 130, and discontinuities 150 are provided on the wiring areas 140. By conducting different discontinuities 150, different LED chips 200 can be connected in series or in parallel. Using the same substrate 100, multiple series and parallel connection modes of the LED chips 200 can be achieved, resulting in LED package structures with various voltage specifications. This provides high versatility. Furthermore, the use of flip-chip packaging reduces the need for wirebonds, significantly improving the heat dissipation performance and thermal shock resistance of the resulting LED package structure.

[0043] It is understood that the discontinuity 150 is equivalent to a vacant space on the connection area 140 that is not covered with conductive material. Without any subsequent operation, the connection area 140 where the discontinuity 150 is located cannot be conductive. By applying conductive material on the discontinuity 150, a conductive point is formed to achieve conductivity between the connection line and the discontinuity 150. In one embodiment, the length of the discontinuity 150 is 0.15mm~0.35mm. It is understood that the length of the discontinuity 150 is the distance between the two ends of the discontinuity 150. If the length of the discontinuity 150 is too short, it will cause accidental conductivity in the connection area 140 where the discontinuity 150 is located; if the length of the discontinuity 150 is too long, it will increase the amount of conductive material used. Excessive conductive material may also extend between different connection areas 140, causing conductivity between different connections.

[0044] The connection line is generally a copper connection line obtained by direct printing or stamping, and the conductive material can be solder paste, conductive glue, etc. It is understandable that in the cross section, the shape of the conductive point can be circular, elliptical, rectangular, trapezoidal, etc., but is not limited to this. In one embodiment, the ratio of the length of the conductive point to the length of the discontinuity is 1:(1~1.3), and is exemplarily 1:1.05, 1:1.1, 1:1.15, 1:1.2 or 1:1.25, but is not limited to this. It is understandable that the length direction of the conductive point is consistent with the length direction of the discontinuity 150. In the cross section where the conductive point contacts the front of the substrate 100, the conductive point covers the discontinuity 150 and contacts at least the two ends of the discontinuity 150. Preferably, the conductive point covers the discontinuity 150 and overlaps with the connection line at both ends of the discontinuity 150 to ensure conduction stability. In one embodiment, the ratio of the width of the conductive dot to the length of the conductive dot is 1:(0.8-1.2), and is exemplarily 1:0.85, 1:0.9, 1:0.95, 1:1, or 1:1.15, but is not limited thereto. It is understood that the width direction of the conductive dot is perpendicular to the length direction of the conductive dot. A width that is too large or too small is not conducive to the stability of current transmission. In one embodiment, the ratio of the height of the conductive dot to the length of the conductive dot is 1:(1-1.5), and is exemplarily 1:1.1, 1:1.2, 1:1.25, 1:1.3, or 1:1.4, but is not limited thereto. It is understood that the height direction of the conductive dot is consistent with the thickness direction of the substrate 100. If the height of the conductive dot is too low, it may cause the conductive dot to collapse. If the height of the conductive dot is too high, it may cause bridging of different connecting lines. By defining the shape of the conductive dot, the bonding strength between the conductive dot and the connecting line can also be improved, preventing the conductive dot from falling off during subsequent operation.

[0045] In a preferred embodiment, the length of the conductive dots formed after dot coating is 0.2 mm to 0.24 mm, the width of the conductive dots is 0.18 mm to 0.26 mm, the height of the conductive dots is 0.24 mm to 0.34 mm, and the conductive dots are deposited in a spherical crown shape with a circular cross section.

[0046] In a preferred embodiment, solder paste is applied to the discontinuous portion 150 to achieve conductivity. Accordingly, the discontinuous portion 150 is equivalent to a soldering point on the connection area 140. In a preferred embodiment, the viscosity of the solder paste is 200kcps to 500kcps, ensuring that the conductive dots are formed without causing conductivity between different connections.

[0047] By limiting the structure and material of the conductive point, the bonding strength between the conductive point and the connection line can be improved while ensuring the conductive stability of the connection line. The welding tension at the conductive point is ≥5N / mm 2, it will not fall off during subsequent use.

[0048] Specifically, each of the die-bonding regions 130 includes a first solder pad 131 and a second solder pad 132, and the two electrodes of each of the LED chips 200 are electrically connected to the first solder pad 131 and the second solder pad 132, respectively. The back circuit 120 includes a first back solder pad 121 and a second back solder pad 122. It is understood that the first solder pad 131 can be a positive electrode solder pad or a negative electrode solder pad. In one embodiment, the first solder pad 131 is a positive electrode solder pad, the second solder pad 132 is a negative electrode solder pad, the first back solder pad 121 is a back positive electrode solder pad, and the second back solder pad 122 is a back negative electrode solder pad.

[0049] The connection area 140 includes a first connection line 141, a second connection line 142 and a third connection line 143; the first pads 131 of the plurality of the solid crystal areas 130 are respectively connected to the first pad 121 on the back side through the first connection line 141, and the first connection line 141 is provided with a discontinuity 150; the second pads 132 of the plurality of the solid crystal areas 130 are respectively connected to the second pad 122 on the back side through the second connection line 142, and the second connection line 142 is provided with a discontinuity 150; the second pad 132 of one solid crystal area 130 is connected to the first pad 131 of another solid crystal area 130 through the third connection line 143, and the third connection line 143 is provided with a discontinuity 150, so as to form a connection between the plurality of solid crystal areas 130;

[0050] The number of the first connection lines 141 is N, and at least (N-1) first connection lines 141 are provided with discontinuities 150. In other words, one of the first connection lines 141 may not be provided with the discontinuity 150 and may be directly connected.

[0051] In one embodiment, Figures 2 to 4 As shown, the solid crystal area 130 includes a first solid crystal area 130a and a second solid crystal area 130b, and the connection area 140 includes a first connection line 141, a second connection line 142 and a third connection line 143; the LED chip 200 includes a first LED flip chip 210 and a second LED flip chip 220, and the first LED flip chip 210 and the second LED flip chip 220 are electrically connected to the first solid crystal area 130a and the second solid crystal area 130b respectively.

[0052] Assume that the first solder pad 131 of the first solid crystal area 130a is connected to the first solder pad 121 on the back side through the first connection line 141, and no discontinuity 150 is set on the first connection line 141; the first solder pad 131 of the second solid crystal area 130b is connected to the first solder pad 121 on the back side through the first connection line 141, and a first discontinuity 1 is set on the first connection line 141; the second solder pad 132 of the first solid crystal area 130a is connected to the second solder pad 122 on the back side through the second connection line 142, and a second discontinuity 2 is set on the second connection line 142; the second solder pad 132 of the second solid crystal area 130b is connected to the second solder pad 122 on the back side through the second connection line 142, and no discontinuity 150 is set on the second connection line 142; the second solder pad 132 of the first solid crystal area 130a is connected to the first solder pad 131 of the second solid crystal area 130b through the third connection line 143, and a third discontinuity 3 is set on the third connection line 143.

[0053] Specifically, such as Figure 3 As shown, in one embodiment, the first connection line 141 connecting the first solder pad 131 in the first solid crystal area 130a and the first solder pad 121 on the back side, the second connection line 142 connecting the second solder pad 132 in the fourth solid crystal area 130d and the second solder pad 122 on the back side, and the third connection line 143 connecting the second solder pad 132 in the first solid crystal area 130a and the first solder pad 131 in the second solid crystal area 130b are connected, that is, the third discontinuity 3 is connected, forming a series connection of the first LED flip chip 210 and the second LED flip chip 220.

[0054] Specifically, such as Figure 4 As shown, in another embodiment, the first connection line 141 connecting the first solder pad 131 in the first solid crystal area 130a and the first solder pad 121 on the back side, the first connection line 141 connecting the first solder pad 131 in the second solid crystal area 130b and the first solder pad 121 on the back side, the second connection line 142 connecting the second solder pad 132 in the first solid crystal area 130a and the second solder pad 122 on the back side, and the second connection line 142 connecting the second solder pad 132 in the second solid crystal area 130b and the second solder pad 122 on the back side are connected, that is, the first discontinuity 1 and the second discontinuity 2 are connected, forming a parallel connection of the first LED flip chip 210 and the second LED flip chip 220.

[0055] In another embodiment, Figures 5 to 8As shown, the solid crystal area 130 includes a first solid crystal area 130a, a second solid crystal area 130b, a third solid crystal area 130c and a fourth solid crystal area 130d, and the connection area 140 includes a first connection line 141, a second connection line 142 and a third connection line 143; the first solid crystal area 130a, the second solid crystal area 130b, the third solid crystal area 130c and the fourth solid crystal area 130d are arranged in a matrix manner, and the first solid crystal area 130a, the second solid crystal area 130b, the third solid crystal area 130c and the fourth solid crystal area 130d are respectively arranged in the upper left area, the lower left area, the upper right area and the lower right area of ​​the front line 110. The LED chip 200 includes a first LED flip chip 210, a second LED flip chip 220, a third LED flip chip 230 and a fourth LED flip chip 240. The first LED flip chip 210, the second LED flip chip 220, the third LED flip chip 230 and the fourth LED flip chip 240 are electrically connected to the first solid crystal area 130a, the second solid crystal area 130b, the third solid crystal area 130c and the fourth solid crystal area 130d respectively.

[0056] Assume that the first pad 131 of the first solid crystal region 130a is connected to the first pad 121 on the back side via the first connection line 141, and the first connection line 141 is not provided with the discontinuity 150; the first pad 131 of the second solid crystal region 130b is connected to the first pad 121 on the back side via the first connection line 141, and the first connection line 141 is provided with the first discontinuity 1; the first pad 131 of the third solid crystal region 130c is connected to the first pad 121 on the back side via the first connection line 141, and the first connection line 141 is provided with the tenth discontinuity 10; the first pad 131 of the fourth solid crystal region 130d is connected to the first pad 121 on the back side via the first connection line 141 The first pad 121 is connected, and the first connection line 141 is provided with a sixth discontinuity 6; the second pad 132 of the first solid crystal area 130a is connected to the second pad 122 on the back through the second connection line 142, and the second connection line 142 is provided with a third discontinuity 3, the second pad 132 of the second solid crystal area 130b is connected to the second pad 122 on the back through the second connection line 142, and the second connection line 142 is provided with a seventh discontinuity 7, the second pad 132 of the third solid crystal area 130c is connected to the second pad 122 on the back through the second connection line 142, and the second connection line 142 is provided with a fourth discontinuity 4, the fourth solid crystal area The second pad 132 of the first solid crystal region 130d is connected to the second pad 122 on the back side through a second connection line 142, and the second connection line 142 is not provided with a discontinuity 150; the second pad 132 of the first solid crystal region 130a is connected to the first pad 131 of the second solid crystal region 130b through a third connection line 143, and the third connection line 143 is provided with a second discontinuity 2, the second pad 132 of the second solid crystal region 130b is connected to the first pad 131 of the third solid crystal region 130c through a third connection line 143, and the third connection line 143 is provided with an eighth discontinuity 8 and a ninth discontinuity 9, and the third solid crystal region 130 c's second solder pad 132 is connected to the first solder pad 131 of the fourth solid crystal area 130d through a third line 143, and a fifth discontinuity 5 is provided on the third line 143. In order to further streamline the connection area 140 and improve the conduction stability of the connection area 140, the second line 142 of the first solid crystal area 130a and the second line 142 of the third solid crystal area 130c intersect at the fourth discontinuity 4 and are connected to the second solder pad 122 on the back side, and the third line 143 between the second solid crystal area 130b and the third solid crystal area 130c intersects with the second line 142 of the first solid crystal area 130a at the eleventh discontinuity 11.

[0057] Specifically, such as Figure 6As shown, in one embodiment, the first connection line 141 connecting the first pad 131 in the first solid crystal area 130a and the first pad 121 on the back side, the second connection line 142 connecting the second pad 132 in the fourth solid crystal area 130d and the second pad 122 on the back side, the third connection line 143 connecting the second pad 132 in the first solid crystal area 130a and the first pad 131 in the second solid crystal area 130b, and the third connection line 143 connecting the second pad 132 in the second solid crystal area 130b and the third solid crystal area 1 The third connecting line 143 of the first solder pad 131 in 30c, and the third connecting line 143 connecting the second solder pad 132 in the third solid crystal area 130c and the first solder pad 131 in the fourth solid crystal area 130d, that is, conducting the second discontinuity 2, the fifth discontinuity 5, the eighth discontinuity 8, the ninth discontinuity 9 and the eleventh discontinuity 11, forming a series connection of the first LED flip chip 210, the second LED flip chip 220, the third LED flip chip 230 and the fourth LED flip chip 240.

[0058] Specifically, such as Figure 7 As shown, in another embodiment, the first connection line 141 connecting the first pad 131 in the first solid crystal area 130a and the first pad 121 on the back side, the first connection line 141 connecting the first pad 131 in the second solid crystal area 130b and the first pad 121 on the back side, the first connection line 141 connecting the first pad 131 in the third solid crystal area 130c and the first pad 121 on the back side, the first connection line 141 connecting the first pad 131 in the fourth solid crystal area 130d and the first pad 121 on the back side, the second connection line 142 connecting the second pad 132 in the first solid crystal area 130a and the second pad 122 on the back side, and the first connection line 142 connecting the second solid crystal area 130 b and the second solder pad 132 and the second solder pad 122 on the back side, the second solder pad 132 and the second solder pad 122 in the third solid crystal area 130c and the second solder pad 122 on the back side, and the second solder pad 132 and the second solder pad 122 in the fourth solid crystal area 130d are connected, that is, the first discontinuity 1, the third discontinuity 3, the fourth discontinuity 4, the sixth discontinuity 6, the seventh discontinuity 7, the tenth discontinuity 10 and the eleventh discontinuity 11 are connected, forming a parallel connection of the first LED flip chip 210, the second LED flip chip 220, the third LED flip chip 230 and the fourth LED flip chip 240.

[0059] Specifically, such as Figure 8As shown, in another embodiment, the first connection line 141 connecting the first pad 131 in the first solid crystal area 130a and the first pad 121 on the back side, the first connection line 141 connecting the first pad 131 in the third solid crystal area 130c and the first pad 121 on the back side, the second connection line 142 connecting the second pad 132 in the second solid crystal area 130b and the second pad 122 on the back side, the second connection line 142 connecting the second pad 132 in the fourth solid crystal area 130d and the second pad 122 on the back side, and the second connection line 142 connecting the second pad 132 in the first solid crystal area 130a and the second pad 132 on the back side are connected. 2 and the first pad 131 in the second die-bonding area 130b, and the third connection line 143 connecting the second pad 132 in the third die-bonding area 130c and the first pad 131 in the fourth die-bonding area 130d, that is, the second discontinuity 2, the fifth discontinuity 5, the seventh discontinuity 7 and the tenth discontinuity 10 are connected, the first LED flip chip 210 and the second LED flip chip 220 form a first series group, the third LED flip chip 230 and the fourth LED flip chip 240 form a second series group, and the first series group and the second series group are connected in parallel.

[0060] Alternatively, the voltage of the LED chip 200 can be 3V, and four die-bonding regions 130 are provided. That is, with four LED chips 200, high-voltage LEDs of 3V, 6V, and 12V can be realized, respectively. If a high-voltage flip-chip (chip voltage of 6V, 9V, etc.) is used, high-voltage LEDs with a wider range of voltage specifications can be realized. It is understood that if the voltage of a single LED chip 200 is 18V, and four die-bonding regions 130 are provided, a 72V high-voltage LED can be obtained by connecting them in series, an 18V high-voltage LED can be obtained by connecting them in parallel, and a 36V high-voltage LED can be obtained by connecting them in series and then in parallel.

[0061] Accordingly, the present invention also provides an LED packaging method for forming the above-mentioned LED packaging structure, comprising the following steps:

[0062] S1. Provide a substrate 100, form a front circuit 110 on the front side of the substrate 100, and form a back circuit 120 on the back side of the substrate 100, the front circuit 110 includes a plurality of solid crystal areas 130 and connection areas 140, connection areas 140 are provided between different solid crystal areas 130, and a discontinuity 150 is provided on the connection area 140.

[0063] In one embodiment, the method of forming the front line 110 and the back line 120 includes the following steps:

[0064] S11, such as Figure 9 As shown, a die-bonding area 130 and a connection area 140 for soldering the flip chip are made by etching or stamping to form the front circuit 110 .

[0065] S12, such as Figure 10 As shown, a plastic layer, namely, a substrate 100 , is formed on the back side of the front circuit 110 .

[0066] S13, such as Figure 11 As shown, the outwardly extending portion of the front circuit 110 is bent to a side of the plastic layer away from the front circuit 110 to form a back circuit 120 .

[0067] In one embodiment, an LED bracket bowl is further formed on the front surface of the front circuit 110 .

[0068] S2, such as Figure 12 As shown, according to the series-parallel connection requirements, conductive material is dotted on the discontinuous portion 150 in the preset area.

[0069] S3, such as Figure 12 As shown, a conductive material is spot-coated on the die-bonding area 130 and an LED chip 200 is placed thereon.

[0070] S4, such as Figure 13 As shown, reflow soldering is performed to complete the electrical connection between the LED chip 200 and the die-bonding area 130 and the conduction of the discontinuity 150 in the preset area.

[0071] S5, such as Figure 14 As shown, the packaging glue 300 is applied at least on the LED chip 200 to complete the LED packaging.

[0072] In one embodiment, fluorescent glue is injected into the bracket bowl to cover the LED chip 200. The fluorescent glue is obtained by mixing phosphor powder with encapsulating glue 300. The material of encapsulating glue 300 can be epoxy encapsulating glue, silicone encapsulating glue, polyurethane encapsulating glue, or UV light curing encapsulating glue, etc., without specific limitation.

[0073] Taking four 3V voltage LED flip chips as an example, the LED packaging structure of the present invention has a thermal resistance of 10℃ / W~12℃ / W. The thermal resistance of the LED packaging structure obtained by conventionally connecting four 3V voltage upright LEDs in series is usually around 25℃ / W. The heat dissipation performance of the LED packaging structure provided by the present invention is significantly improved; conventional LEDs fail after 300 cycles in a cycle test of -45℃ / 15min→125℃ / 15min, while the LED packaging structure provided by the present invention does not fail after more than 1000 cycles under the same test conditions, and its resistance to cold and hot shock is significantly improved; in addition, the luminous efficiency of the LED is improved by 5%~10%, and since the wire bonding process is eliminated, the LED production efficiency is improved by 20%~30%.

[0074] The above is a preferred embodiment of the invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. An LED packaging structure, characterized in that: The device comprises a substrate, an LED chip and a packaging adhesive; wherein the front side of the substrate is provided with a front circuit, the back side of the substrate is provided with a back circuit, the LED chip comprises at least two LED flip chips, the LED chip is electrically connected to the front circuit, and the packaging adhesive covers the LED chip; The front circuit includes multiple solid crystal areas and connecting areas. The number of the solid crystal areas is the same as the number of the LED chips. Connecting areas are provided between different solid crystal areas. Discontinuities are provided on the connecting areas. By conducting different discontinuities, series or parallel connection between different LED flip chips is achieved; the connecting area includes multiple connecting lines, which are disconnected at the discontinuities. The length of the discontinuities is 0.15mm~0.35mm; conductive points are formed by applying conductive material on the discontinuities to achieve conduction between the connecting lines and the discontinuities.

2. The LED packaging structure according to claim 1, wherein: The ratio of the length of the conductive dot to the length of the discontinuity is 1:(1-1.3), the ratio of the width of the conductive dot to the length of the conductive dot is 1:(0.8-1.2), and the ratio of the height of the conductive dot to the length of the conductive dot is 1:(1-1.5).

3. The LED packaging structure according to claim 1, wherein: Each of the die-bonding areas includes a first pad and a second pad, and two electrodes of each of the LED flip chips are electrically connected to the first pad and the second pad, respectively; The back side circuit includes a first back side pad and a second back side pad.

4. The LED packaging structure according to claim 3, wherein: The connection area includes a first connection line, a second connection line and a third connection line; the first pads of the plurality of crystal-bonding areas are respectively connected to the first pad on the back side through the first connection line, and the first connection line is provided with a discontinuity; the second pads of the plurality of crystal-bonding areas are respectively connected to the second pad on the back side through the second connection line, and the second connection line is provided with a discontinuity; the second pad of one crystal-bonding area is connected to the first pad of another crystal-bonding area through the third connection line, and the third connection line is provided with a discontinuity, so as to form a connection between the plurality of crystal-bonding areas; The number of the first connecting lines is N, and at least (N-1) first connecting lines are provided with discontinuities; the number of the second connecting lines is N, and at least (N-1) second connecting lines are provided with discontinuities.

5. The LED packaging structure according to claim 3, wherein: The solid crystal area includes a first solid crystal area, a second solid crystal area, a third solid crystal area and a fourth solid crystal area, and the connection area includes a first connection line, a second connection line and a third connection line; the first pads of the first solid crystal area, the second solid crystal area, the third solid crystal area and the fourth solid crystal area are respectively connected to the first pad on the back through the first connection line, and a discontinuity is provided on the first connection line; the second pads of the first solid crystal area, the second solid crystal area, the third solid crystal area and the fourth solid crystal area are respectively connected to the second pad on the back through the second connection line, and a discontinuity is provided on the second connection line; the second pad of the first solid crystal area and the first pad of the second solid crystal area, the second pad of the second solid crystal area and the first pad of the third solid crystal area, and the second pad of the third solid crystal area and the first pad of the fourth solid crystal area are respectively connected through the third connection line, and a discontinuity is provided on the third connection line; The LED chips include a first LED flip chip, a second LED flip chip, a third LED flip chip and a fourth LED flip chip, and the first LED flip chip, the second LED flip chip, the third LED flip chip and the fourth LED flip chip are electrically connected to the first solid crystal area, the second solid crystal area, the third solid crystal area and the fourth solid crystal area respectively; The first, second, third and fourth crystal-bonding areas are arranged in a matrix manner, and the first, second, third and fourth crystal-bonding areas are respectively arranged in the upper left area, lower left area, upper right area and lower right area of ​​the front line.

6. The LED packaging structure according to claim 5, wherein: Conductive connection includes a first connection line connecting the first solder pad in the first solid crystal area and the first solder pad on the back side, a second connection line connecting the second solder pad in the fourth solid crystal area and the second solder pad on the back side, a third connection line connecting the second solder pad in the first solid crystal area and the first solder pad in the second solid crystal area, a third connection line connecting the second solder pad in the second solid crystal area and the first solder pad in the third solid crystal area, and a third connection line connecting the second solder pad in the third solid crystal area and the first solder pad in the fourth solid crystal area, forming a series connection of a first LED flip chip, a second LED flip chip, a third LED flip chip and a fourth LED flip chip.

7. The LED packaging structure according to claim 5, wherein: Conductive connection is provided between the first solder pad in the first solid crystal area and the first solder pad on the back side, the first solder pad in the second solid crystal area and the first solder pad on the back side, the first solder pad in the third solid crystal area and the first solder pad on the back side, the first solder pad in the fourth solid crystal area and the first solder pad on the back side, the second solder pad in the first solid crystal area and the second solder pad on the back side, the second solder pad in the second solid crystal area and the second solder pad on the back side, the second solder pad in the third solid crystal area and the second solder pad on the back side, and the second solder pad in the fourth solid crystal area and the second solder pad on the back side, forming a parallel connection of the first LED flip chip, the second LED flip chip, the third LED flip chip and the fourth LED flip chip.

8. The LED packaging structure according to claim 5, wherein: Conductive connection includes the first connection line connecting the first solder pad in the first solid crystal area and the first solder pad on the back side, the first connection line connecting the first solder pad in the third solid crystal area and the first solder pad on the back side, the second connection line connecting the second solder pad in the second solid crystal area and the second solder pad on the back side, the third connection line connecting the second solder pad in the first solid crystal area and the first solder pad in the second solid crystal area, and the third connection line connecting the second solder pad in the third solid crystal area and the first solder pad in the fourth solid crystal area. The first LED flip chip and the second LED flip chip form a first series group, the third LED flip chip and the fourth LED flip chip form a second series group, and the first series group and the second series group are connected in parallel.

9. An LED packaging method for forming the LED packaging structure according to any one of claims 1 to 8, characterized in that: The following steps are involved: A substrate is provided, a front circuit is formed on the front surface of the substrate, and a back circuit is formed on the back surface of the substrate, the front circuit includes a plurality of crystal bonding areas and connection areas, connection areas are provided between different crystal bonding areas, and discontinuities are provided on the connection areas; According to the requirements of series and parallel connection, conductive material is applied on the discontinuous parts of the preset area; Apply conductive material on the die-bonding area and place the LED chip; Reflow soldering to complete the electrical connection between the LED chip and the die-bonding area and the conduction of the discontinuity in the preset area; Fluorescent glue is applied on the LED chip to complete the LED packaging.

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