Dear XANSYS community,
I’m writing to discuss something that has come to my attention recently.
During my search of research papers in the area of modeling and simulations
of electronic assemblies, I have found a recent article published in a
ultra reputable journal in the field. No need to mention specifics.
In this paper, the authors have done creep tests on a new technology
bonding method and they’ve extracted Anand’s creep model coefficients (the
famous 9 parameters) using nonlinear curve fitting process. Interestingly,
many values of such constants are reported to be “negative” and some other
parameters do not match with the conditions of Anand’s law. What makes it
even more interesting is that the authors didn’t comment at all on such
weird observations. Additionally, no FEA simulations using such material
model were provided.
In my knowledge, all Anand’s parameters have to be positive values and one
specific parameter (a - the strain rate sensitivity coefficient of the
hardening/softening process) is equal to or greater than one. I triple
checked!
Which comes to my conclusion is that the parameters provided in that paper
are questionable? Right?
Am I missing something? I would love to hear some thoughts on this.
Best Regards,
MG
I quickly checked limited amount of material data we have from our “Solder Joint Reliability” class notes and I can confirm that all Anand constants are positive values. In full disclosure, we have never done creep tests; just went through papers published on this.
In the past, we have noticed one inconsistency in one of the published papers that one of Anand constants was way off (it was not a negative number but orders of magnitude off); was it a typo or was it done on purpose? We just moved on and used data from other published papers…
From: Mohammad Gharaibeh via Xansys xansys-temp@list.xansys.org
Date: Saturday, August 19, 2023 at 2:47 AM
To: XANSYS Mailing List Home xansys-temp@list.xansys.org
Cc: Mohammad Gharaibeh mgharai1@binghamton.edu
Subject: [Xansys] Negative values and f Anand’s parameters?
Dear XANSYS community,
I’m writing to discuss something that has come to my attention recently.
During my search of research papers in the area of modeling and simulations
of electronic assemblies, I have found a recent article published in a
ultra reputable journal in the field. No need to mention specifics.
In this paper, the authors have done creep tests on a new technology
bonding method and they’ve extracted Anand’s creep model coefficients (the
famous 9 parameters) using nonlinear curve fitting process. Interestingly,
many values of such constants are reported to be “negative” and some other
parameters do not match with the conditions of Anand’s law. What makes it
even more interesting is that the authors didn’t comment at all on such
weird observations. Additionally, no FEA simulations using such material
model were provided.
In my knowledge, all Anand’s parameters have to be positive values and one
specific parameter (a - the strain rate sensitivity coefficient of the
hardening/softening process) is equal to or greater than one. I triple
checked!
Which comes to my conclusion is that the parameters provided in that paper
are questionable? Right?
Am I missing something? I would love to hear some thoughts on this.
Best Regards,
MG
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Thanks, Metin, for the response.
First of all, I have to declare that I am not trying to pick up a fight or
attack anyone or anything. Just trying to have a scientific discussion with
the experts here.
Back to the topic, in the paper I was referring to, there were “four”
parameters with negative values. So I would not just assume this was a
typo. I cannot say it was on purpose either.
The confusion here is that how could this have slipped off the reviewers
hands in such a high-profile journal? Again, a little discussion on the
negative values would’ve been helpful to further justify.
ANSYS Theory Manual, In Anand Option section, explicitly mentions that all
the parameters have to be positive and, as stated earlier, the “a”
coefficient is equal to or greater than 1.
Of course I’ll be moving on from this and literature is flooded with solder
joints creep models. It is Not the end of the world!
Just something I thought might of interest for the scientific community.
Kind Regards,
Mohammad
On Saturday, August 19, 2023, Metin Ozen metin@ozeninc.com wrote:
I quickly checked limited amount of material data we have from our “Solder
Joint Reliability” class notes and I can confirm that all Anand constants
are positive values. In full disclosure, we have never done creep tests;
just went through papers published on this.
In the past, we have noticed one inconsistency in one of the published
papers that one of Anand constants was way off (it was not a negative
number but orders of magnitude off); was it a typo or was it done on
purpose? We just moved on and used data from other published papers…
*From: *Mohammad Gharaibeh via Xansys xansys-temp@list.xansys.org
*Date: *Saturday, August 19, 2023 at 2:47 AM
*To: *XANSYS Mailing List Home xansys-temp@list.xansys.org
*Cc: *Mohammad Gharaibeh mgharai1@binghamton.edu
*Subject: *[Xansys] Negative values and f Anand’s parameters?
Dear XANSYS community,
I’m writing to discuss something that has come to my attention recently.
During my search of research papers in the area of modeling and simulations
of electronic assemblies, I have found a recent article published in a
ultra reputable journal in the field. No need to mention specifics.
In this paper, the authors have done creep tests on a new technology
bonding method and they’ve extracted Anand’s creep model coefficients (the
famous 9 parameters) using nonlinear curve fitting process. Interestingly,
many values of such constants are reported to be “negative” and some other
parameters do not match with the conditions of Anand’s law. What makes it
even more interesting is that the authors didn’t comment at all on such
weird observations. Additionally, no FEA simulations using such material
model were provided.
In my knowledge, all Anand’s parameters have to be positive values and one
specific parameter (a - the strain rate sensitivity coefficient of the
hardening/softening process) is equal to or greater than one. I triple
checked!
Which comes to my conclusion is that the parameters provided in that paper
are questionable? Right?
Am I missing something? I would love to hear some thoughts on this.
Best Regards,
MG
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account settings to Digest mode which will send a single email per day.
Please send administrative requests such as deletion from XANSYS to
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--
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Mohammad A Gharaibeh, Ph.D.
Associate Professor
Department of Mechanical Engineering
The Hashemite University
P.O. Box 330127
Zarqa, 13133, Jordan
Tel: +962 - 5 - 390 3333 Ext. 4771
Fax: +962 - 5 - 382 6348
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