Detection of solder joint cracking of high power leds on AI-IMS during temperature shock test by transient thermal analysis

Author

Elger, Gordon ; Kandaswamy, Shri Vishnu ; Derix, Robert ; Conti, Francesco

Author_Institution

Tech. Hochschule Ingolstadt, Ingolstadt, Germany

fYear

2014

fDate

24-26 Sept. 2014

Firstpage

1

Lastpage

6

Abstract

An innovative sensitive test method is developed to detect solder joint cracking for high power LED packages. The method is based on transient thermal analysis and can replace the dominating Light-On test. Test groups of LED packages were soldered with two different lead free solders (SnAgCu 305 and Innolot FL-640) on Aluminum Insulated Metal Substrate and exposed to temperature cycles. Transient thermal measurements were performed directly after assembly and after specific cycle numbers. After data processing the increase of the relative thermal resistance between the initial signal at `0´ cycles and `n´ cycles is obtained and correlated with cracks in the solder joint by cross sections. The transient curves are reproduced by time resolved finite element analysis. Based on the simulation, a failure criterium is defined representing a crack length of 30% of the solder joint area. A higher creep resistance for the test group soldered with Innolot FL-640 compared to the test group soldered with SAC 305 is observed.

Keywords

aluminium; copper alloys; crack detection; creep; finite element analysis; insulating materials; light emitting diodes; packaging; silver alloys; solders; thermal resistance; tin alloys; Al; Innolot FL-640 solders; SnAgCu; SnAgCu 305 solders; SnAgCuNiSbBi; aluminum insulated metal substrate; crack length; creep resistance; failure criterium; high power LED packages; lead free solders; relative thermal resistance; solder joint cracking detection; temperature shock test; time resolved finite element analysis; transient curves; transient thermal analysis; Electronic packaging thermal management; Light emitting diodes; Soldering; Temperature measurement; Thermal analysis; Thermal resistance;

fLanguage

English

Publisher

ieee

Conference_Titel

Thermal Investigations of ICs and Systems (THERMINIC), 2014 20th International Workshop on

Conference_Location

London

Type

conf

DOI

10.1109/THERMINIC.2014.6972530

Filename

6972530