Global Citizenship: Understanding Global Citizenship as a Competitive Advantage
Global Sourcing Spotlight: Tariffs—The New Reality
Knocking Down the Bone Pile: Gold Mitigation for Class 2 Electronics
Pad Cratering Susceptibility Testing with Acoustic Emission
July 22, 2015 | B.S. Wong and J. Silk, Keysight Technologies, and R. Nordstrom, Ph.D., Emerson Process ManagementEstimated reading time: 16 minutes
Figure 7 shows that Laminate F is a frequent AE emitter as evidenced by the significant number of AE events with amplitude greater than 40 dB that occurred when both the applied load at 30lbs and 50lbs compared to other five laminates. Figure 8 shows that Laminate F released significantly more energy than other laminates when both the applied load at 30lbs and 50lbs. Both the number of AE events at given applied load and the cumulative energy of AE events at given applied load indicates that Laminate F is prone to pad cratering.
Our empirical experience with laminates is that Laminate F is inferior and that Laminate A, our control laminate that is dicy-cured, is superior. Laminate F proved to be a frequent AE emitter, confirming our experience. The expected superiority of Laminate A is not evident; this may be because of degradation due to incompatibility of this laminate with the multiple high temperature reflows. The degradation with additional reflow cycles seen in the other test methods reported in our earlier paper [8] was not found, although with this test method we compared only 5 and 7 reflows.
Verification of pad cratering was done with cross-sections. To enhance the visibility of the pad craters, two methods were tried: powder filling and polarized light. Polarized light produced much more visible pad craters. The vast majority of the pad crater failures were, not surprisingly, at the corners of the largest BGA. Fig. 9 shows examples of pad cratering.
As indicated in Figure 5, not all AE events are associated with pad cratering because some AE events are located outside of the package. Figure 10 shows two examples of laminate cracks indicated by AE events, but not associated with pad cratering. The cross-sectioning results confirm this finding.
Table 2 compares results of various test methods for evaluating pad cratering. Note that the results of six different laminates’ resistance to pad cratering using the ball pull, ball shear, and hot pin pull tests (please refer to our earlier paper [8]). This ranking of laminate materials shows quite a bit of inconsistency of results among the methods. No conclusion can be drawn at this time as to which test method is better able to distinguish the laminate materials’ resistance to pad cratering.
Figure 6: (a) The applied load at first locatable AE event with amplitude greater than 40dB, (b) Average applied load when first four AE events with amplitude greater than 40dB.
Figure 7: (a) Number of AE events with amplitude greater than 40dB when the applied load is 30 lbs, (b) Number of AE events with amplitude greater than 40dB when the applied load is 50lbs.
Figure 8: (a) natural log of cumulative energy of all AE events with amplitude greater than 40 dB when the applied load is less than 30lbs, (b) natural log of cumulative energy of all AE events with amplitude greater than 40dB when the applied load is less than 50lbs.
Page 4 of 5
Share on:
Suggested Items
KYZEN to Focus on Aqueous Cleaning and Stencil Cleaning at SMTA Juarez
05/20/2025 | KYZEN'KYZEN, the global leader in innovative environmentally responsible cleaning chemistries, will exhibit at the SMTA Juarez Expo and Tech Forum, scheduled to take place Thursday, June 5 at the Injectronics Convention Center in Ciudad Jarez, Chihuahua.
Koh Young Installs 24,000th Inspection System at Top 20 EMS
05/14/2025 | Koh YoungKoh Young, the global leader in True 3D measurement-based inspection and metrology solutions, proudly announces the installation of its 24,000th inspection system at a Top 20 Global EMS in Thailand.
Indium’s Karthik Vijay to Present on Dual Alloy Solder Paste Systems at SMTA’s Electronics in Harsh Environments Conference
05/06/2025 | Indium CorporationIndium Corporation Technical Manager, Europe, Africa, and the Middle East Karthik Vijay will deliver a technical presentation on dual alloy solder paste systems at SMTA’s Electronics in Harsh Environments Conference, May 20-22 in Amsterdam, Netherlands.
SolderKing Achieves the Prestigious King’s Award for Enterprise in International Trade
05/06/2025 | SolderKingSolderKing Assembly Materials Ltd, a leading British manufacturer of high-performance soldering materials and consumables, has been honoured with a King’s Award for Enterprise, one of the UK’s most respected business honours.
Knocking Down the Bone Pile: Gold Mitigation for Class 2 Electronics
05/07/2025 | Nash Bell -- Column: Knocking Down the Bone PileIn electronic assemblies, the integrity of connections between components is paramount for ensuring reliability and performance. Gold embrittlement and dissolution are two critical phenomena that can compromise this integrity. Gold embrittlement occurs when gold diffuses into solder joints or alloys, resulting in mechanical brittleness and an increased susceptibility to cracking. Conversely, gold dissolution involves the melting away of gold into solder or metal matrices, potentially altering the electrical and mechanical properties of the joint.