Research
Technologies and Standards to Realize Smart Manufacturing
SIR Test Method for Developing Evidence for the Production Assembly
Attributes of Cored Solder Wire in LED Luminaire Soldering
Selective Removal of Conformal Coatings by Pulsed Ultraviolet Lasers
Effect of Assembly Pitch and Distance on Solder Joint Thermal Cycling Life
Hybrid Conformal Coatings for Mitigating Tin Whiskers
Printing and Assembly Challenges for QFN Devices
Pad Cratering Susceptibility Testing with Acoustic Emission
MORE RESEARCH
Latest Industry News
Will iPhone 13 Trigger Headaches and Nausea?
You'll hear a lot about how boring the iPhone 13 is, but Apple is still poised to continue its sales super cycle
Foxtron, Taiwan's First EV, Leaks After Arriving in the Country: How Come?
NI, Elektro-Automatik Join Forces for EV Battery Testing
China's manufacturing growth slows
To Manage Your Time Better, Think Of It Like A Balloon
Out of the Verification Crisis: Improving RTL Quality
Deep Learning Method Produces Holograms Instantly
MORE INDUSTRY NEWS

Reliability of Lead-Free LGAs and BGAs



Reliability of Lead-Free LGAs and BGAs
A theory is proposed that substantial differences in SAC305 solder joint Sn grain morphology may explain, at least partially.
Analysis Lab

DOWNLOAD

Authored By:


Denis Barbini Ph.D. & Michael Meilunas
Universal Instruments Corporation
Conklin, NY, USA

Summary


An accelerated thermal cycle experiment comparing similarly constructed area array devices representing Land Grid Array(LGA) and Ball Grid Array (BGA) technology with 0.254, 0.30, and 0.40mm diameter SAC305 solder balls was performed. The devices were subjected to three thermal cycle conditions in order to promote 2nd level solder fatigue. Failure data was compared using Weibull analyses.

The results show that time to failure is highly influenced by the package pitch and thermal cycle temperatures in a manner predicted by simple mechanics. However, there were instances in which the effect of solder ball size did not fit the traditional solder joint reliability model in which increasing solder joint standoff height improves reliability (i.e. more cycles to failure). A theory is proposed that substantial differences in SAC305 solder joint Sn grain morphology may explain, at least partially, the discrepancies and evidence to support this theory is presented.


Conclusions


A strain rate approach for analyzing the ATC reliability data appears to better describe the results than a strain range approach. Using the strain rate approach it has been shown that SAC305 solder joints approximating LGA-like joint qualities (shape, height and microstructure) can be more reliable than larger BGA-like SAC305 solder joints for a given strain rate.

Evidence from this experiment and from literature suggests that the 'small' SAC305 solder joints tend to develop an interlaced twinned Sn grain morphology which has significantly different thermal-mechanical properties than the single grain or beach ball morphology commonly formed in BGA-sized solder joints. These findings suggest that low-profile packages like LGA can be quite reliable in ATC testing - if the proper microstructure forms.

Initially Published in the IPC Proceedings

Comments

No comments have been submitted to date.

Submit A Comment


Comments are reviewed prior to posting. You must include your full name to have your comments posted. We will not post your email address.

Your Name


Your Company
Your E-mail


Your Country
Your Comments



Board Talk
01005 Component Challenges and Bugs
Insulation Between Overhanging Component Lead and Circuit Conductor
Sticky Residue Under Low Clearance Parts
Finding the Cause of Cold Solder Joints
Soldering Relays Intrusively in Lead Free Process
Printing vs. Dispensing
Maximum Board Temperature During Tin-Lead
Is There a Spacing Spec for SMD Components?
MORE BOARD TALK
Ask the Experts
Options for Reballing BGA Components
Solder Paste Viscosity
MSD Components Baked Too Long
Aluminum Trays and Rapid Static Discharge
Seeking IPC and J-STD Definitions
Is Component Lead Damage Reparable?
BGA Solder Ball Shelf Life
Conformal Coating Press Fit Connectors
MORE ASK THE EXPERTS