Microstructure Influence of SACX0307-TiO<sub>2</sub> Composite Solder Joints on Thermal Properties of Power LED Assemblies
The effect of the microstructure of solder joints on the thermal properties of power LEDs is investigated. Solder joints were prepared with different solder pastes, namely 99Sn0.3Ag0.7Cu (as reference solder) and reinforced 99Sn0.3Ag0.7Cu–TiO<sub>2</sub> (composite solder). TiO<sub>...
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MDPI AG
2020-03-01
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| Series: | Materials |
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| Online Access: | https://www.mdpi.com/1996-1944/13/7/1563 |
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| author | Agata Skwarek Przemysław Ptak Krzysztof Górecki Tamás Hurtony Balázs Illés |
| author_facet | Agata Skwarek Przemysław Ptak Krzysztof Górecki Tamás Hurtony Balázs Illés |
| author_sort | Agata Skwarek |
| collection | DOAJ |
| description | The effect of the microstructure of solder joints on the thermal properties of power LEDs is investigated. Solder joints were prepared with different solder pastes, namely 99Sn0.3Ag0.7Cu (as reference solder) and reinforced 99Sn0.3Ag0.7Cu–TiO<sub>2</sub> (composite solder). TiO<sub>2</sub> ceramic was used at 1 wt.% and with two different primary particle sizes, which were 20 nm (nano) and 200 nm (submicron). The thermal resistance, the electric thermal resistance, and the luminous efficiency of the power LED assemblies were measured. Furthermore, the microstructure of the different solder joints was analyzed on the basis of cross-sections using scanning electron and optical microscopy. It was found that the addition of submicron TiO<sub>2</sub> decreased the thermal and electric thermal resistances of the light sources by 20% and 16%, respectively, and it slightly increased the luminous efficiency. Microstructural evaluations showed that the TiO<sub>2</sub> particles were incorporated at the Sn grain boundaries and at the interface of the intermetallic layer and the solder bulk. This caused considerable refinement of the Sn grain structure. The precipitated TiO<sub>2</sub> particles at the bottom of the solder joint changed the thermodynamics of Cu<sub>6</sub>Sn<sub>5</sub> formation and enhanced the spalling of intermetallic grain to solder bulk, which resulted in a general decrease in the thickness of the intermetallic layer. These phenomena improved the heat paths in the composite solder joints, and resulted in better thermal and electrical properties of power LED assemblies. However, the TiO<sub>2</sub> nanoparticles could also cause considerable local IMC (Intermetallic Compounds) growth, which could inhibit thermal and electrical improvements. |
| first_indexed | 2024-03-11T10:11:02Z |
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| id | doaj.art-972f9e1835b645a49b3e8d661ec4864d |
| institution | Directory Open Access Journal |
| issn | 1996-1944 |
| language | English |
| last_indexed | 2024-03-11T10:11:02Z |
| publishDate | 2020-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Materials |
| spelling | doaj.art-972f9e1835b645a49b3e8d661ec4864d2023-11-16T14:32:33ZengMDPI AGMaterials1996-19442020-03-01137156310.3390/ma13071563Microstructure Influence of SACX0307-TiO<sub>2</sub> Composite Solder Joints on Thermal Properties of Power LED AssembliesAgata Skwarek0Przemysław Ptak1Krzysztof Górecki2Tamás Hurtony3Balázs Illés4Department of Marine Electronics, Gdynia Maritime University, 81-255 Gdynia, PolandDepartment of Marine Electronics, Gdynia Maritime University, 81-255 Gdynia, PolandDepartment of Marine Electronics, Gdynia Maritime University, 81-255 Gdynia, PolandDepartment of Electronics Technology, Budapest University of Technology and Economics, 1111 Budapest, HungaryDepartment of Electronics Technology, Budapest University of Technology and Economics, 1111 Budapest, HungaryThe effect of the microstructure of solder joints on the thermal properties of power LEDs is investigated. Solder joints were prepared with different solder pastes, namely 99Sn0.3Ag0.7Cu (as reference solder) and reinforced 99Sn0.3Ag0.7Cu–TiO<sub>2</sub> (composite solder). TiO<sub>2</sub> ceramic was used at 1 wt.% and with two different primary particle sizes, which were 20 nm (nano) and 200 nm (submicron). The thermal resistance, the electric thermal resistance, and the luminous efficiency of the power LED assemblies were measured. Furthermore, the microstructure of the different solder joints was analyzed on the basis of cross-sections using scanning electron and optical microscopy. It was found that the addition of submicron TiO<sub>2</sub> decreased the thermal and electric thermal resistances of the light sources by 20% and 16%, respectively, and it slightly increased the luminous efficiency. Microstructural evaluations showed that the TiO<sub>2</sub> particles were incorporated at the Sn grain boundaries and at the interface of the intermetallic layer and the solder bulk. This caused considerable refinement of the Sn grain structure. The precipitated TiO<sub>2</sub> particles at the bottom of the solder joint changed the thermodynamics of Cu<sub>6</sub>Sn<sub>5</sub> formation and enhanced the spalling of intermetallic grain to solder bulk, which resulted in a general decrease in the thickness of the intermetallic layer. These phenomena improved the heat paths in the composite solder joints, and resulted in better thermal and electrical properties of power LED assemblies. However, the TiO<sub>2</sub> nanoparticles could also cause considerable local IMC (Intermetallic Compounds) growth, which could inhibit thermal and electrical improvements.https://www.mdpi.com/1996-1944/13/7/1563TiO<sub>2</sub> ceramicSAC composite alloymicrostructure characterizationthermal resistanceluminous efficiencypower LED |
| spellingShingle | Agata Skwarek Przemysław Ptak Krzysztof Górecki Tamás Hurtony Balázs Illés Microstructure Influence of SACX0307-TiO<sub>2</sub> Composite Solder Joints on Thermal Properties of Power LED Assemblies Materials TiO<sub>2</sub> ceramic SAC composite alloy microstructure characterization thermal resistance luminous efficiency power LED |
| title | Microstructure Influence of SACX0307-TiO<sub>2</sub> Composite Solder Joints on Thermal Properties of Power LED Assemblies |
| title_full | Microstructure Influence of SACX0307-TiO<sub>2</sub> Composite Solder Joints on Thermal Properties of Power LED Assemblies |
| title_fullStr | Microstructure Influence of SACX0307-TiO<sub>2</sub> Composite Solder Joints on Thermal Properties of Power LED Assemblies |
| title_full_unstemmed | Microstructure Influence of SACX0307-TiO<sub>2</sub> Composite Solder Joints on Thermal Properties of Power LED Assemblies |
| title_short | Microstructure Influence of SACX0307-TiO<sub>2</sub> Composite Solder Joints on Thermal Properties of Power LED Assemblies |
| title_sort | microstructure influence of sacx0307 tio sub 2 sub composite solder joints on thermal properties of power led assemblies |
| topic | TiO<sub>2</sub> ceramic SAC composite alloy microstructure characterization thermal resistance luminous efficiency power LED |
| url | https://www.mdpi.com/1996-1944/13/7/1563 |
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