Research
In-Line Testing of Highly Panelized PCBAs with Parallel Functional Test
Electrochemical Reliability as a Function of Component Standoff
Reliable Nickel-Free Surface Finish for High-Frequency-HDI PCB
Enclosed Media Printing as an Alternative to Metal Blades
Risk for Ceramic Component Cracking Dependent
Nanocopper Based Paste for Solid Copper Via Fill
Fluxless Die Attach by Activated Forming Gas
Embracing a New Paradigm: Electronic Work Instructions (EWI)
MORE RESEARCH
Latest Industry News
Global Chip Shortage Is Impacting Carmakers
VIEWPOINT 2021: Raymond M. LaFleur, General Manager of Overseas Sales and Marketing, DEN-ON
VIEWPOINT 2021: Mark Cottom, Vice President of Sales & Marketing, National Circuit Assembly
Geely and Foxconn form partnership to build cars for other automakers
Samsung Debuts World's First Wi-Fi 6E Mobile Phone
IBM tops US patent list for 28th year in a row with more than 9,100 patents granted
5G Makes Waves At CES 2021
4 Reasons a Retreat Into Nature Will Increase Productivity
MORE INDUSTRY NEWS

Bending Strength of Solder Joints as a Function of Joint Length



Bending Strength of Solder Joints as a Function of Joint Length
The effect of joint length on the fracture of copper-solder-copper joints is investigated using double cantilever-beam specimens of various joint lengths.
Analysis Lab

DOWNLOAD

Authored By:


Saeed Akbari, Amir Nourani, Jan K. Spelt
University of Toronto
Toronto, ON, Canada

Summary


The effect of the joint length on the fracture of coppersolder-copper joints were investigated using doublecantilever-beam (DCB) specimens of various joint lengths. It was found that for solder joints shorter than a certain characteristic length the strength increased with increasing joint length. This characteristic length was found numerically using a finite element model to plot the maximum peel stress of the solder joint versus the joint length.

The length at which the plot reaches a plateau was considered as the characteristic length. Characteristic lengths obtained from experiment and finite element analysis were in close agreement, indicating the validity of the numerical method. The practical importance of the characteristic length is that solder joints longer than the characteristic length have a maximum peel stress that remains unchanged with joint length, causing the joint strength to become independent of the joint length. In other words, the use of joints longer than the characteristic length provides no additional strength to the joint.

Conclusions


The fracture strength of mode-I copper DCB specimens were measured with SAC305 solder joints of various lengths. Joint strength increased with increasing solder length before reaching a plateau value of constant strength. The corresponding finite element model showed that the maximum peel stress became independent of the length of the solder layer beyond a characteristic length which was very close to the solder length corresponding to the initiation of the measured joint-strength plateau.

This supported the hypothesis that solder joints reach a maximum strength at the characteristic solder length, and that further increases in length do not result in stronger joints. The concept of the characteristic length was illustrated in a hypothetical chip resistor assembly loaded by board bending. The characteristic length of a typical chip resistor solder joint was predicted to be about 1 mm, as determined from the finite element predictions of the maximum solder peel stress as a function of the joint length.

Initially Published in the SMTA 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
Is There a Spacing Spec for SMD Components?
Maximum Board Temperature During Tin-Lead
Is HASL a Good Choice for Surface Finish?
Connector Bowing During Reflow Process
Has My Flux Expired?
Long Term Component Storage
Processing Circuit Boards with BGAs On Both Sides
What Causes Solder Balls During Hand Soldering?
MORE BOARD TALK
Ask the Experts
Mixing Different SAC305 Solders
Dross Particles Sticking to PCBs
Cleaning with Sodium Bicarbonate
Conformal Coating Over Heat Sinks
Flux Oozing from Insulated Wires
Conformal Coating in Low Humidity Environments
Tiny Solder Balls After Reflow
Solder Paste Alloy Check
MORE ASK THE EXPERTS