Peeling Resistance Testing of BGA Chips
If the electronic device in which a BGA package is mounted is subjected to repeated external forces due to deformations, for example, the surface-mounted board may bend, causing the BGA chip to peel off (ball contacts peel off to cause discontinuity). A quantitative understanding of the relationship between repeated bending deflections of the surface-mounted board and the number of cycles to BGA peeling permits the design of lighter, more compact housings.
Bending durability testing was performed on printed circuit boards with a surface-mounted BGA package using a Microservo electromagnetic force micro material tester.
The specimens were subjected to 3-point bending and sinusoidal loads applied at 2 Hz.
Sample A: 110 (L) × 42 (W) × 0.8 (t) mm; bending span 90 mm; deflection 3 mm
Sample B: 70 (L) × 42 (W) × 0.8 (t) mm; bending span 50 mm; deflection 1 mm
The number of cycles until the any ball contact became open was Sample A: 715,516, Sample B: 317,833.
It is apparent that the durability differs little due to the bending deflection.
Closed-loop servo control of the electromagnetic loading mechanism provides accurate control of the micro forces. This tester offers a range of dynamic force patterns applied to the sample, down to the milligram/submicron order. Different microscopes can be attached for observations during testing.