Mechanical modelling of high power lateral IGBT for LED driver applications

Bailey, Chris; Rajaguru, Pushparajah; Lu, Hua; Castellazzi, Alberto; Antonini, Mattia; Pathirana, Vasantha; Udugampola, Nishad; Udrea, Florin; Mitchelson, Paul; Aldhaher, Samer

Abstract

An assembly exercise was proposed to replace the vertical MOSFET by lateral IGBTs (LIGBT) for LED driver systems which can provide significant advantages in terms of size reduction (LIGBTs are ten times smaller than vertical MOSFETs) and lower component count. A 6 circle, 5V gate, 800 V LIGBT device with dimension of 818μm x 672μm with deposited solder balls that has a radius of around 75μm was selected in this assembly exercise. The driver system uses chip on board (COB) technique to create a compact driver system which can fit into a GU10 bulb housing. The challenging aspect of the LIGBT package in high voltage application is underfill dielectric breakdown and solder fatigue failure. In order to predict the extreme electric field values of the underfill, an electrostatic finite element analysis was undertaken on the LIGBT package structure for various underfill permittivity values. From the electro static finite element analysis, the maximum electric field in the underfill was estimated as 38 V/μm. Five commercial underfills were selected for investigating the trade-off in materials properties that mitigate underfill electrical breakdown and solder joint fatigue failure. These selected underfills have dielectric breakdown higher than the predicted value from electrostatic analysis. The thermo-mechanical finite element analysis were undertaken for solder bump reliability for all the underfill materials. The underfill which can enhance the solder reliability was chosen as prime candidate.

Citation

Bailey, C., Rajaguru, P., Lu, H., Castellazzi, A., Antonini, M., Pathirana, V., Udugampola, N., Udrea, F., Mitchelson, P., & Aldhaher, S. (2018, May). Mechanical modelling of high power lateral IGBT for LED driver applications. Presented at 2018 IEEE 68th Electronic Components and Technology Conference (ECTC), San Diego, California, USA

• Presentation Conference Type: Edited Proceedings
• Conference Name: 2018 IEEE 68th Electronic Components and Technology Conference (ECTC)
• Start Date: May 29, 2018
• End Date: Jun 1, 2018
• Acceptance Date: Jan 1, 2018
• Online Publication Date: Aug 9, 2018
• Publication Date: May 29, 2018
• Deposit Date: Nov 26, 2018
• Publicly Available Date: Nov 27, 2018
• Publisher: Institute of Electrical and Electronics Engineers
• Pages: 1375-1381
• Series ISSN: 2377-5726
• Book Title: IEEE 68th Electronic Components and Technology Conference
• ISBN: 978-1-5386-5000-4
• DOI: https://doi.org/10.1109/ECTC.2018.00210
• Keywords: LIGBT; LED; Fatigue; Underfill
• Public URL: https://nottingham-repository.worktribe.com/output/1307425
• Publisher URL: https://ieeexplore.ieee.org/document/8429723
• Additional Information: © 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works
• Contract Date: Nov 26, 2018