A flip-chip LED implementation structure and method

Abstract

The present invention discloses a novel flip-chip LED implementation structure and method, which includes a flip-chip LED chip, a flip-chip LED bracket and epoxy solder paste; the flip-chip LED chip is bonded to the pad area of ​​the flip-chip LED bracket through the epoxy solder paste; the P pole and the N pole of the flip-chip LED chip are coated with tin layers respectively to form a P pole tin-plated layer and an N pole tin-plated layer; the P pole tin-plated layer and the N pole tin-plated layer are respectively pasted to the corresponding pad groove pits of the flip-chip LED bracket; the epoxy solder paste is dotted in the pad groove pit of the flip-chip LED bracket, and the pad groove pit is surrounded by a resin overflow groove, and a slope-type isolation block is arranged between the pad groove pits, and an EMC adhesive is filled around the pads of the P pole and the N pole, and the flip-chip LED bracket is also filled with a bracket etching sheet. The present invention suppresses short-circuit failure caused by irregular flow of solder paste after melting during reflow soldering of the flip-chip LED packaging process, and at the same time solves the short-circuit risk caused by the remelting flow of solder paste that may be caused by the secondary reflow soldering of the terminal.

Description

Technical Field

[0001] The present invention relates to the technical field of LED packaging, and in particular to a flip-chip LED implementation structure and method. Background Art

[0002] In recent years, with the rapid growth of the lighting industry and the display industry, the market demand for LED light-emitting diodes has also increased. With the continuous technological breakthroughs in the industry, end customers have higher and higher requirements for LED light-emitting diodes, especially the requirements for packaging power, light efficiency, and reliability. In this context, the scale of flip-chip LED products has continued to expand and impact the mid-to-high-end market.

[0003] The biggest problem in the existing flip-chip LED packaging technology is that in the packaging process, the P and N electrodes of the flip-chip are on the same plane; after the flip-chip die bonding, the solder is reflowed and the solder paste melts, which can easily cause the P and N electrodes of the chip to short-circuit, thus causing product failure. Even for products with normal packaging, there is still a secondary board mounting operation in the terminal process, which needs to go through reflow again. The original normal product may fail due to short circuit caused by the melting of solder paste.

[0004] In this context, solving the technical difficulties of short circuit-induced failures in the flip-chip process during packaging and terminal use has become an urgent need in the industry.

[0005] In summary, the present invention designs a flip-chip LED implementation structure and method. Summary of the invention

[0006] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a flip-chip LED implementation structure and method to suppress short-circuit failure caused by irregular flow of melted solder paste during reflow soldering in the flip-chip LED packaging process, while solving the short-circuit risk caused by the remelted flow of solder paste that may be caused by secondary reflow soldering at the terminal.

[0007] In order to achieve the above-mentioned purpose, the present invention is realized through the following technical scheme: a flip-chip LED implementation structure, comprising a flip-chip LED chip, a flip-chip LED bracket and epoxy solder paste; the flip-chip LED chip is bonded to the pad area of ​​the flip-chip LED bracket through the epoxy solder paste; the P pole and the N pole of the flip-chip LED chip are respectively coated with tin layers to form a P pole tin-plated layer and an N pole tin-plated layer; the P pole tin-plated layer and the N pole tin-plated layer are respectively correspondingly pasted into the pad groove pits corresponding to the flip-chip LED bracket; the epoxy solder paste is dotted into the pad groove pits of the flip-chip LED bracket, and resin overflow grooves are arranged around the pad groove pits, and slope-type isolation blocks are arranged between the pad groove pits, and EMC glue is filled around the pads of the P pole and the N pole, and the flip-chip LED bracket is also filled with a bracket etching sheet, and the epoxy solder paste is a solder paste with a resin component, and the height of the slope-type isolation block is higher than the P pole tin-plated layer and the N pole tin-plated layer.

[0008] A method for implementing a flip-chip LED comprises the following steps:

[0009] (1) First, the tinning process is used to complete the tinning of the flip chip electrode; when the flip chip bracket is injection molded, the EMC glue is filled around the P-pole pad and the N-pole pad around the bracket pad area, higher than the surface of the pad; and in the middle of the two pads, the glue is injected into a raised slope-shaped isolation block, and its height is higher than other positions; in addition, a circle of completely closed resin overflow grooves is made around the inner side of the P-pole pad and the N-pole pad by stamping;

[0010] (2) During the die bonding process, first apply epoxy solder paste to the soldering pad groove of the flip-chip LED bracket; then, the flip-chip LED chip and its tin-plated electrode are inverted and fixed on the soldering pad groove of the flip-chip LED bracket;

[0011] (3) The bracket with the die bonded is put through a reflow soldering device, and the tinned layer of the flip chip is fused with the solder pad groove and the epoxy solder paste dotted in the solder pad groove of the flip-chip LED bracket; after reflow soldering and curing, the chip and the bracket form a conductive circuit;

[0012] (4) Finally, fill the fluorescent glue into the bowl of the bracket.

[0013] Beneficial effects of the present invention:

[0014] 1. Completely solve the short-circuit failure risk of flip-chip LED products in the packaging process; improve the product yield rate and eliminate invisible electrical abnormalities; current flip-chip products mainly rely on testing methods to screen defective products, which has the risk of misjudgment; this solution of isolating the short-circuit path can completely avoid this hidden risk;

[0015] 2. At the same time, this solution also solves the short-circuit risk of the downstream process in the industry; when used at the terminal, it needs to be soldered again through reflow soldering; this structure can eliminate the P and N pole short-circuit problem caused by the irregular flow of secondary solder paste remelting. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments;

[0017] Figure 1 It is a front view of the flip chip of the present invention;

[0018] Figure 2 is a side view of a flip chip of the present invention;

[0019] Figure 3 A front view of the support of the present invention

[0020] Figure 4 is a side view of the bracket of the present invention;

[0021] Figure 5 for Figure 4 A magnified schematic diagram of part A;

[0022] Figure 6 It is a structural cross-sectional view of the present invention. DETAILED DESCRIPTION

[0023] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0024] Reference Figure 1-6 , this specific implementation adopts the following technical solutions: a flip-chip LED implementation structure, including a flip-chip LED chip, a flip-chip LED bracket and epoxy solder paste; the flip-chip LED chip is bonded to the pad area of ​​the flip-chip LED bracket through the epoxy solder paste; the P pole 1 and the N pole 2 of the flip-chip LED chip are respectively coated with tin layers to form a P pole tin-plated layer 3 and an N pole tin-plated layer 4; the P pole tin-plated layer 3 and the N pole tin-plated layer 4 are respectively correspondingly pasted to the pad grooves 5 corresponding to the flip-chip LED bracket; the epoxy solder paste is dotted in the pad grooves 5 of the flip-chip LED bracket, and the pad grooves 5 are surrounded by resin overflow grooves 6, and slope-type isolation blocks 7 are arranged between the pad grooves 5, and EMC glue 8 is filled around the pads of the P poles 1 and the N poles 2, and the flip-chip LED bracket is also filled with a bracket etching sheet 9.

[0025] The flip chip of this specific embodiment is provided with conductive electrodes, P pole 1 and N pole 2; a layer of 15um solder paste is coated on the P pole 1 and N pole 2 of the chip respectively to form a P pole tinning layer 3 and an N pole tinning layer 4; the flip-chip LED bracket is provided with a solder pad groove 5, a resin overflow groove 6, and a slope-type isolation block 7, and the remaining positions are the same as the EMC brackets on the market, which are filled with EMC glue 8 and bracket etching sheet 9. The solder paste is epoxy solder paste.

[0026] A method for implementing a flip-chip LED comprises the following steps:

[0027] (1) First, the tinning process is used to complete the tinning of the flip chip electrode; when the flip chip bracket is injection molded, the EMC glue is filled around the P-pole pad and the N-pole pad around the bracket pad area, higher than the surface of the pad; and in the middle of the two pads, the glue is injected into a raised slope-shaped isolation block, and its height is higher than other positions; in addition, a circle of completely closed resin overflow grooves is made around the inner side of the P-pole pad and the N-pole pad by stamping;

[0028] (2) During the die bonding process, first apply epoxy solder paste to the soldering pad groove of the flip-chip LED bracket; then, the flip-chip LED chip and its tin-plated electrode are inverted and fixed on the soldering pad groove of the flip-chip LED bracket;

[0029] (3) The bracket with the die bonded is put through a reflow soldering device, and the tinned layer of the flip chip is fused with the solder pad groove and the epoxy solder paste dotted in the solder pad groove of the flip-chip LED bracket; after reflow soldering and curing, the chip and the bracket form a conductive circuit;

[0030] (4) Finally, fill the fluorescent glue 11 into the bracket bowl.

[0031] By spot coating, the epoxy solder paste is applied to the groove 5 of the flip-chip LED bracket; the flip chip is turned upside down in the flip-chip LED bracket so that the P pole 1 and the N pole 2 of the flip chip fit and fix with the pad groove; after completing this step, the semi-finished product is soldered through the reflow soldering equipment; in this process, heating and curing are carried out, and at low temperature, the epoxy component in the solder paste reaches the melting point and melts, diffuses and flows outward, and overflows into the resin overflow groove 6 around the flip-chip bracket pad, and then in the high temperature zone, the tin component reaches the melting point and melts, flows to fill the entire pad groove 5 area, and hardens in the low temperature zone at the end of the reflow soldering. During this process, the resin overflow groove is first filled with the resin in the epoxy solder paste to form an outer protective layer. When the tin component melts, the tin is locked into the groove 5 of the bracket pad and cannot overflow. At the same time, the sloped isolation block 7 between the flip-chip bracket P and N pads effectively blocks the solder paste from flowing and connecting the P pole 1 and N pole 2 of the chip to cause a short circuit. During the secondary reflow soldering operation of the terminal customer, the one-time molding characteristics of the epoxy resin and the pad resin overflow groove 6 enable it to lock the remelted solder paste in the pad groove 5, which cannot overflow to avoid the connection between the chip P pole 1 and N pole 2, effectively avoiding short circuit failure caused by terminal use. After the chip 10 welding process is completed, the remaining process flow is the same as that of conventional LEDs.

[0032] This specific implementation method suppresses short-circuit failure caused by irregular flow of solder paste after melting during reflow soldering of flip-chip LED packaging process, and at the same time solves the short-circuit risk caused by the remelting flow of solder paste that may be caused by secondary reflow soldering of the terminal.

[0033] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for implementing a flip-chip LED. It is characterized in that The LED structure includes a flip-chip LED chip, a flip-chip LED bracket and epoxy solder paste; the flip-chip LED chip is bonded to a solder pad area of ​​the flip-chip LED bracket by epoxy solder paste; a P pole (1) and an N pole (2) of the flip-chip LED chip are coated with tin layers to form a P pole tin-plated layer (3) and an N pole tin-plated layer (4); the P pole tin-plated layer (3) and the N pole tin-plated layer (4) are respectively bonded to corresponding solder pad grooves (5) of the flip-chip LED bracket; the epoxy solder paste is dotted on the flip-chip LED In the pad groove (5) of the D bracket, a resin overflow groove (6) is arranged around the pad groove (5), a slope-type isolation block (7) is arranged between the pad grooves (5), an EMC adhesive (8) is filled around the pads of the P pole (1) and the N pole (2), and a bracket etching sheet (9) is also filled on the flip-chip LED bracket, the epoxy solder paste is a solder paste with a resin component, and the height of the slope-type isolation block (7) is higher than the P pole tin-plated layer (3) and the N pole tin-plated layer (4). The implementation method comprises the following steps: (1) First, the tinning process is used to complete the tinning of the flip chip electrode; when the flip chip bracket is injection molded, the EMC glue is filled around the P-pole pad and the N-pole pad around the bracket pad area, higher than the surface of the pad; and in the middle of the two pads, the glue is injected into a raised slope-shaped isolation block, and its height is higher than other positions; in addition, a circle of completely closed resin overflow grooves is made around the inner side of the P-pole pad and the N-pole pad by stamping; (2) During the die bonding process, first apply epoxy solder paste to the soldering pad groove of the flip-chip LED bracket; then, the flip-chip LED chip and its tin-plated electrode are inverted and fixed on the soldering pad groove of the flip-chip LED bracket; (3) The bracket with the die bonded is put through a reflow soldering device, and the tinned layer of the flip chip is fused with the solder pad groove and the epoxy solder paste dotted in the solder pad groove of the flip-chip LED bracket; after reflow soldering and curing, the chip and the bracket form a conductive circuit; (4) Finally, fill the fluorescent glue into the bowl of the bracket.

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