A study on Laser-Assisted Bonding (LAB) and its Influence on Luminescence Characteristics of Blue and YAG Phosphor Encapsulated InGaN LEDs<\/h1><\/div> <\/p>\n<\/div><\/div><\/div><\/div><\/div>
Abstract:<\/strong><\/span><\/h2>\nThis work is a sincere attempt to answer the question whether laser assisted bonding (LAB) is a feasible method for producing stable and reliable solder interconnections of LED devices without any negative impact on the LED chip performance. To meet these requirements, a bonding process was evaluated that
\ninduces marginal thermal and mechanical loads into the LED chip to prevent any changes in the quantum well (QW) structure. The bonding process uses a LAB
\n\u201cLAPLACE\u00a0\u00ae\u201d system with a 280W Q-CW solid-state, near infrared (NIR) laser source.<\/p>\n
By varying the laser parameters, the functionality of the bonded LED was characterized and a suitable process window, along with the corresponding energy threshold, was examined for the chosen LED configuration. A 700 \u03bcm thick copper lead-frame test substrate was selected, and subjected to AgNi metallization.
\nFurthermore, InGaN blue LED test chips (type EDIFA445B) with 150 \u03bcm pad-to-pad spacing, and 3 \u03bcm SnAu 20\/80 solder connections were used. Overall, this
\nstudy compares a non-encapsulated LED version to an encapsulated (NYAG4454-L) one.<\/p>\n
To determine a suitable LAB process window, metallurgical properties of the soldered interface were examined microscopically by polishing a cross-section on
\nthe one hand, and conducting electrical qualification on the other. The mechanical load capacity was measured with a shear test unit, and the corresponding metallurgical fractures were optically inspected. The optical spectrum of the LED after bonding was studied with a “spectroradiometer” to identify shifts in the wavelength corresponding to electroluminescent emissions peaks. The impact of a “thermal-test” on the bonding quality was further evaluated. Additionally, the interface quality was correlated with the performance data in relation to LAB bonding parameters.<\/p>\n
Finally, this work introduces a laser assisted rework process i.g. laser assisted de-bonding (LAdB) for the de-bonding of faulty LEDs. The future prospects of
\nintended reliability and stability for LED placement as well as a skillful approach for rapid, laser-assisted placement of mini- and micro-LEDs using the \u201cLAPLACE\u00a0\u00ae\u201d systems are elucidated.<\/p>\n
Keywords – LED, mini LED, \u03bc LED, die attach, bonding, laser-reflow, low-stress, InGaN, de-bonding, rework<\/em><\/p>\n<\/div><\/div><\/div>
<\/p>\n<\/div><\/div><\/div><\/div><\/div>
Abstract:<\/strong><\/span><\/h2>\nThis work is a sincere attempt to answer the question whether laser assisted bonding (LAB) is a feasible method for producing stable and reliable solder interconnections of LED devices without any negative impact on the LED chip performance. To meet these requirements, a bonding process was evaluated that
\ninduces marginal thermal and mechanical loads into the LED chip to prevent any changes in the quantum well (QW) structure. The bonding process uses a LAB
\n\u201cLAPLACE\u00a0\u00ae\u201d system with a 280W Q-CW solid-state, near infrared (NIR) laser source.<\/p>\n
By varying the laser parameters, the functionality of the bonded LED was characterized and a suitable process window, along with the corresponding energy threshold, was examined for the chosen LED configuration. A 700 \u03bcm thick copper lead-frame test substrate was selected, and subjected to AgNi metallization.
\nFurthermore, InGaN blue LED test chips (type EDIFA445B) with 150 \u03bcm pad-to-pad spacing, and 3 \u03bcm SnAu 20\/80 solder connections were used. Overall, this
\nstudy compares a non-encapsulated LED version to an encapsulated (NYAG4454-L) one.<\/p>\n
To determine a suitable LAB process window, metallurgical properties of the soldered interface were examined microscopically by polishing a cross-section on
\nthe one hand, and conducting electrical qualification on the other. The mechanical load capacity was measured with a shear test unit, and the corresponding metallurgical fractures were optically inspected. The optical spectrum of the LED after bonding was studied with a “spectroradiometer” to identify shifts in the wavelength corresponding to electroluminescent emissions peaks. The impact of a “thermal-test” on the bonding quality was further evaluated. Additionally, the interface quality was correlated with the performance data in relation to LAB bonding parameters.<\/p>\n
Finally, this work introduces a laser assisted rework process i.g. laser assisted de-bonding (LAdB) for the de-bonding of faulty LEDs. The future prospects of
\nintended reliability and stability for LED placement as well as a skillful approach for rapid, laser-assisted placement of mini- and micro-LEDs using the \u201cLAPLACE\u00a0\u00ae\u201d systems are elucidated.<\/p>\n
Keywords – LED, mini LED, \u03bc LED, die attach, bonding, laser-reflow, low-stress, InGaN, de-bonding, rework<\/em><\/p>\n<\/div><\/div><\/div>
\ninduces marginal thermal and mechanical loads into the LED chip to prevent any changes in the quantum well (QW) structure. The bonding process uses a LAB
\n\u201cLAPLACE\u00a0\u00ae\u201d system with a 280W Q-CW solid-state, near infrared (NIR) laser source.<\/p>\n
\nFurthermore, InGaN blue LED test chips (type EDIFA445B) with 150 \u03bcm pad-to-pad spacing, and 3 \u03bcm SnAu 20\/80 solder connections were used. Overall, this
\nstudy compares a non-encapsulated LED version to an encapsulated (NYAG4454-L) one.<\/p>\n
\nthe one hand, and conducting electrical qualification on the other. The mechanical load capacity was measured with a shear test unit, and the corresponding metallurgical fractures were optically inspected. The optical spectrum of the LED after bonding was studied with a “spectroradiometer” to identify shifts in the wavelength corresponding to electroluminescent emissions peaks. The impact of a “thermal-test” on the bonding quality was further evaluated. Additionally, the interface quality was correlated with the performance data in relation to LAB bonding parameters.<\/p>\n
\nintended reliability and stability for LED placement as well as a skillful approach for rapid, laser-assisted placement of mini- and micro-LEDs using the \u201cLAPLACE\u00a0\u00ae\u201d systems are elucidated.<\/p>\n
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