2ND Generation High Speed Cold Bump Pull

Cold Bump Pull is a DAGE invention and offers some advantages over shear:

* The load is simpler and symmetrical, almost pure tensile

* Less deformation of the bump, ensuring test of the whole bond interface

* Closely mimics the load on corner balls in drop testing

High-speed testing is now added to these, and all the features available with high-speed shear are also provided with 2nd generation high-speed cold bump pull. Digital data capture from the high bandwidth transducer yields force-displacement graphs and energy values. These can be used to easily discriminate between different failure modes, eliminating subjective evaluation.

Remember, high-speed offers so much more than traditional bondtesting, especially with the introduction of lead-free materials. High-speed testing is particularly suitable for detecting brittle fracture failures and can be used to evaluate different alloys, the influence of various pad finishes and the effects of aging on solder joint reliability.

The equipment is capable of test speeds up to 1.3m/s. Most customers have been collecting meaningful data at much lower speeds, in the range of 10 to 400mm/s. Especially important is the transition speed, the point at which the dominant failure mode switches from ductile failure to brittle fracture or pad lift. Often this is in the range of 10 to 100mm/s.

Studies recently completed using the 4000HS and high-speed CBP have shown an excellent correlation with board level drop testing when looking at the effects of thermal aging or different pad finishes.

Of course, not all bumps will have a profile suitable for pull testing, but DAGE has devised a simple guide enabling you to decide on the eligibility of your particular sample. A range of four standard jaw sizes from 300 to 750microns are stocked, but custom jaws can be ordered at intermediate sizes, with back-relief on the jaws if required (to accommodate very fine ball pitches).

Last year JEDEC published a standard for shear, including high-speed testing, and very shortly there will be a new one for Cold Bump Pull, also including high-speed.

© 2008 Dage Holdings Limited