[Source: "High-tech LED - Technology and Applications" August issue]
Wafer die bonding is an important part of LED packaging. The thermal conductivity of solid crystal materials has a considerable impact on the heat dissipation capability of LEDs. Power LED packages are more obvious. In this paper, the solid crystal solder paste ES1000 and high thermal conductivity solid crystal silver paste are used for package comparison. The reliability test of the lamp bead includes testing the light decay of the lamp bead and the temperature of the chip surface and the die pad. The result shows that the solid crystal tin The heat dissipation effect of the lamp-packaged lamp bead is significantly better than that of the silver-glued package. In addition, the comparison also shows that the solid crystal solder paste can not only effectively improve the LED reliability caused by the heat dissipation performance in the power LED package, but also improve the production efficiency, reduce the cost, and greatly improve the process. The price of the product.
I. Introduction
Junction temperature is an important factor affecting the performance of LED. If the junction temperature is too high, it will cause the quantum efficiency of the LED to decrease, the life of the chip is shortened, and the encapsulation material is aging [1]. The thermal conductivity of the solid crystal material used in the LED package directly affects the thermal resistance of the package, and the thermal resistance has a great influence on the junction temperature of the LED. The solid crystal thermal resistance is the thermal resistance introduced by the die bond layer between the wafer and the pedestal, which has a great influence on the heat dissipation effect of the chip [2]. At present, most of the solid-crystal glues in the power LED package use the traditional solid-crystal silver glue, and the thermal conductivity of the epoxy resin in the silver glue is very poor, and the heat transfer can only be carried out by the silver powder, so that the thermal conductivity of the silver glue is poor, and cannot be It satisfies the requirements of power LED packaging very well; at the same time, silver glue is expensive and has a long curing time, which is not conducive to production cost control. To this end, this paper introduces LED solid crystal solder paste, and compares the solid crystal solder paste with the solid crystal silver paste through experiments, and proposes a solid crystal material that can replace the solid crystal silver glue applied to the power LED package--solid crystal tin paste.
Second, the reliability experiment comparison and analysis
Power LEDs are currently mainly encapsulated in silver plastic. The composition of silver paste is a mixture of epoxy and silver powder. The thermal conductivity is generally low, not higher than 25W/mK. We choose thermal conductivity of 25 (W/mK). The Japanese high thermal conductivity silver paste was compared with the solid crystal solder paste ES1000 (Table 1). The Japanese high thermal conductivity silver paste mentioned below is abbreviated as silver paste.
       Table 1 Solid-state adhesive materials and brand introduction
In order to ensure the comparability of the experimental data, the encapsulating material is made of the same material except for the solid crystal glue (solid crystal solder paste ES1000 and silver glue).
At the same time, in order to increase the random contrast of the experiment, 500PCS finished products were respectively made for the two kinds of solid crystal materials, and then 10PCS numbers were randomly selected from each to be compared.
2.1 Package curing process comparison
Similar to eutectic soldering, ES1000 solid crystal solder paste is different from traditional silver paste solid crystal curing process (Table 2). The traditional silver glue is made by the high temperature heating of the oven to completely cure the internal epoxy resin, and the adhesive is fixed. The chip, the silver glue and the base of the bracket do not change, which is a physical connection; and the ES1000 solid crystal solder paste is melted by heating. After the wafer and the heat sink are integrated, the back gold layer of the chip and the plating metal of the support react with the solder paste metal in the solder paste melting process to produce a new intermetallic compound, which is a chemical connection, and the ES1000 solid The crystalline solder paste has a melting point of 217 ° C and is reflow cured by a chain reflow soldering machine.
        Table 2 curing process comparison
(unfinished)
For more information, please refer to: "High-tech LED - Technology and Applications" August issue
Wafer die bonding is an important part of LED packaging. The thermal conductivity of solid crystal materials has a considerable impact on the heat dissipation capability of LEDs. Power LED packages are more obvious. In this paper, the solid crystal solder paste ES1000 and high thermal conductivity solid crystal silver paste are used for package comparison. The reliability test of the lamp bead includes testing the light decay of the lamp bead and the temperature of the chip surface and the die pad. The result shows that the solid crystal tin The heat dissipation effect of the lamp-packaged lamp bead is significantly better than that of the silver-glued package. In addition, the comparison also shows that the solid crystal solder paste can not only effectively improve the LED reliability caused by the heat dissipation performance in the power LED package, but also improve the production efficiency, reduce the cost, and greatly improve the process. The price of the product.
I. Introduction
Junction temperature is an important factor affecting the performance of LED. If the junction temperature is too high, it will cause the quantum efficiency of the LED to decrease, the life of the chip is shortened, and the encapsulation material is aging [1]. The thermal conductivity of the solid crystal material used in the LED package directly affects the thermal resistance of the package, and the thermal resistance has a great influence on the junction temperature of the LED. The solid crystal thermal resistance is the thermal resistance introduced by the die bond layer between the wafer and the pedestal, which has a great influence on the heat dissipation effect of the chip [2]. At present, most of the solid-crystal glues in the power LED package use the traditional solid-crystal silver glue, and the thermal conductivity of the epoxy resin in the silver glue is very poor, and the heat transfer can only be carried out by the silver powder, so that the thermal conductivity of the silver glue is poor, and cannot be It satisfies the requirements of power LED packaging very well; at the same time, silver glue is expensive and has a long curing time, which is not conducive to production cost control. To this end, this paper introduces LED solid crystal solder paste, and compares the solid crystal solder paste with the solid crystal silver paste through experiments, and proposes a solid crystal material that can replace the solid crystal silver glue applied to the power LED package--solid crystal tin paste.
Second, the reliability experiment comparison and analysis
Power LEDs are currently mainly encapsulated in silver plastic. The composition of silver paste is a mixture of epoxy and silver powder. The thermal conductivity is generally low, not higher than 25W/mK. We choose thermal conductivity of 25 (W/mK). The Japanese high thermal conductivity silver paste was compared with the solid crystal solder paste ES1000 (Table 1). The Japanese high thermal conductivity silver paste mentioned below is abbreviated as silver paste.
       Table 1 Solid-state adhesive materials and brand introduction
In order to ensure the comparability of the experimental data, the encapsulating material is made of the same material except for the solid crystal glue (solid crystal solder paste ES1000 and silver glue).
At the same time, in order to increase the random contrast of the experiment, 500PCS finished products were respectively made for the two kinds of solid crystal materials, and then 10PCS numbers were randomly selected from each to be compared.
2.1 Package curing process comparison
Similar to eutectic soldering, ES1000 solid crystal solder paste is different from traditional silver paste solid crystal curing process (Table 2). The traditional silver glue is made by the high temperature heating of the oven to completely cure the internal epoxy resin, and the adhesive is fixed. The chip, the silver glue and the base of the bracket do not change, which is a physical connection; and the ES1000 solid crystal solder paste is melted by heating. After the wafer and the heat sink are integrated, the back gold layer of the chip and the plating metal of the support react with the solder paste metal in the solder paste melting process to produce a new intermetallic compound, which is a chemical connection, and the ES1000 solid The crystalline solder paste has a melting point of 217 ° C and is reflow cured by a chain reflow soldering machine.
        Table 2 curing process comparison
(unfinished)
For more information, please refer to: "High-tech LED - Technology and Applications" August issue
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