Development of mechanical fatigue test method for flip-chip solder joints

Due to the hazard which lead poses to health and the environment the EU is banning its use in electrical and electronic equipment from July 2006. This ban along with the market drive to more environmentally friendly products means that tin-lead solders must be replaced with lead-free alternatives. This paper presents the results of an experimental investigation of the mechanical fatigue properties of tin-silver-copper (SnAgCu) solder joints with a baseline of tin-lead (SnPb). The test vehicle comprised of an 8-layer FR4 printed circuit board (PCB) mounted with four micro-ball grid array (BGA) components — each with a total of 100 solder balls in a 10×10 array. The solder joints were formed using surface mount reflow processes optimised for both solder types. A torsion mechanical fatigue test was employed to evaluate the solder joints — the principle of which was to stress the solder joints repetitively in order to determine the number of cycles to failure. The BGA components were daisy-chained — the resistance across each daisy-chain was monitored continuously during the cyclic defection of the test board. A profile of the increase in resistance with cycle number was established and the number of cycles to failure determined. The failure mechanism induced by the cycling was examined using cross-section and scanning electron microscopy (SEM) techniques. The results for SnAgCu joints show a superior performance during torsion mechanical fatigue testing than SnPb joints; giving a greater number of cycles to failure. The results from the tests presented in this paper show that the torsion test method provides a viable alternative to ATC as a qualification method for solder joints, while also providing substantial time savings — taking weeks rather than months to complete.

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Mechanical fatigue test method for chip/underfill delamination in flip-chip packages

IEEE Transactions on Electronics Packaging Manufacturing ◽

10.1109/tepm.2002.804617 ◽

2002 ◽

Vol 25 (3) ◽

pp. 217-222 ◽

Cited By ~ 22

Author(s):

K. Hirohata ◽

N. Kawamura ◽

M. Mukai ◽

T. Kawakami ◽

H. Aoki ◽

...

Keyword(s):

Fatigue Test ◽

Flip Chip ◽

Test Method ◽

Mechanical Fatigue

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Failure Analysis of the Solder Joints in Flip-Chip BGA Packages under Free-Drop Test

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.936.628 ◽

2014 ◽

Vol 936 ◽

pp. 628-632 ◽

Cited By ~ 1

Author(s):

Guo Zheng Yuan ◽

Xia Chen ◽

Xue Feng Shu

Keyword(s):

Flip Chip ◽

Solder Joints ◽

Ball Grid Array ◽

Test Method ◽

Drop Test ◽

Test Reliability ◽

Internal Crack ◽

The Real ◽

Plastic Ball ◽

Free Drop

The failure of plastic ball grid array under intense dynamic loading was studied in the project. This paper presents the drop test reliability results of SnPb flip-chip on a standard JEDEC drop reliability test board. The failure mode and mechanism of planar array package in the drop test was comprehensively analyzed. High acceleration dropping test method was used to research the reliability of BGA (ball grid array) packages during the free-drop impact process. The model RS-DP-03A drop device was used to simulate the falling behavior of BGA chip packages under the real conditions, The drop condition meets the JEDEC22-B111 standards (pulse peak 1500g, pulse duration 0.5 ms) when dropping from the 650mm height . In the testing, according to the real-time changes of dynamic voltage, the relationship between drop times and different phases of package failure was analyzed. With the dye-penetrated method and optical microscopy, it was easy to observe the internal crack and failure locations. The growth mechanism of the cracks in solder joints under the condition of drop-free was analyzed and discussed.

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