This document describes the development of an electromigration testing apparatus. Initially, porcelain mounts were used but retained too much heat. Glass mounts proved better as heat dissipated faster. Samples were prepared from Sn-Ag-Cu alloy and tested on the apparatus by applying constant current for two days at 100°C. Future work will utilize glass mounts, copper heat sinks, and mechanical bracing to improve heat distribution and support the sample during testing.
On the anodic reaction of the co2 corrosion process, Iron carbonate nucleatio...Omar Yepez, PhD
The anodic reaction of the carbonic acid corrosion process controls the outcome of the degradation of the material. This is because it might produce an FeCO3 scale. In turn, the quality of this crystal will influence the corrosion rate. At the interphase, a colloid of iron carbonate forms. This is fed by Fe+2 coming from the metal dissolution and reacting with the HCO3- coming from the solution. In the colloid, different aggregates of iron carbonate molecules occur. This is until a critical nucleus of the siderite phase occurs, thus forming a siderite crystal. All parameters that normally affect corrosion rate, will affect directly the nucleation, growth and quality of this crystal. Particularly, the metal surface texture and pH of the solution. The nucleation of siderite was studied with anodic chronoamperometry at different surface textures and pH values. It was found that the surface texture is determinant on the law governing siderite nucleation and therefore its scale. FeCO3 formation is required but not sufficient to produce a protective siderite scale. Even after producing such scale, it needs to grow to a certain thickness to offer any protection. Higher pH and rougher surfaces help to achieve good protection. Weight loss corrosion rates measured in autoclave experiments, is controlled by the siderite nucleation phenomena occurring at the interphase.
In this paper the key property differences between solders and TLPS interconnect technologies are compared in detail for MLCC interconnects. The development of a new range of nickel Base Metal Electrode C0G MLCC stacks rated for 200oC is described and performance compared to traditional Precious Metal Electrode (PME) stacks. Thermal cycling performance to 200oC of BME X7R stacks made with 10Sn/88Pb/2Ag solders are compared to similar stacks made with TLPS interconnects of Cu-Sn and In-Ag. The development of leadless stacks, a new bulk capacitance form factor enabled by TLPS technology, is described and their properties compared to traditional stacks.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Electrochemical impedance spectroscopy on thermal ageing evaluation of epoxy ...eSAT Journals
Abstract This research concentrates on the thermal ageing of a full 3-coat system with sacrificial pigment (zinc rich) primer on mild steel where the temperature dependence test is conducted to explore the correlation between the coating resistances with the corrosion rate underneath the coating. Electrochemical impedance spectroscopy (EIS) is introduced over a range of temperature to extract activation energies for the rate of controlling processes in the corrosion reactions. It is expected that the zinc rich primer does not form a barrier coating for the metal substrate rather it will be the most active component of the substrate in the electrochemistry. Full 3-coat system with zinc rich primer show the extracted activation energy from coating resistance is significantly lower than the activation energy extracted from the charge transfer resistance. This suggested that the coating resistance from EIS cannot be controlling the corrosion reaction. The activation energies generated for the corrosion process here (78–97 kJmol-1) are very much higher than those of ion transport through the coating (19–37 kJmol-1) during early immersion. Further interesting findings come from the activation energy trends over time particularly for the corrosion process which shown that the value is decreasing where at the end of exposure, the activation energy values for coating and charge transfer resistance become quite similar. It is suggested that at this stage ion transport in the coating might be controlling the corrosion process unlike at the beginning; the activation energy is getting smaller due to coating degradation. Index Terms: epoxy coating, electrochemical impedance spectroscopy, thermal effect, zinc rich primer
The Bucket Barricade protects a lineman from weather, inadvertent contact with energized equipment, and flying debris.
These are all very good reasons to have the Bucket Barricade at your work site. As with any new product, questions always arise as to the design. This slideshow answers some of those questions.
On the anodic reaction of the co2 corrosion process, Iron carbonate nucleatio...Omar Yepez, PhD
The anodic reaction of the carbonic acid corrosion process controls the outcome of the degradation of the material. This is because it might produce an FeCO3 scale. In turn, the quality of this crystal will influence the corrosion rate. At the interphase, a colloid of iron carbonate forms. This is fed by Fe+2 coming from the metal dissolution and reacting with the HCO3- coming from the solution. In the colloid, different aggregates of iron carbonate molecules occur. This is until a critical nucleus of the siderite phase occurs, thus forming a siderite crystal. All parameters that normally affect corrosion rate, will affect directly the nucleation, growth and quality of this crystal. Particularly, the metal surface texture and pH of the solution. The nucleation of siderite was studied with anodic chronoamperometry at different surface textures and pH values. It was found that the surface texture is determinant on the law governing siderite nucleation and therefore its scale. FeCO3 formation is required but not sufficient to produce a protective siderite scale. Even after producing such scale, it needs to grow to a certain thickness to offer any protection. Higher pH and rougher surfaces help to achieve good protection. Weight loss corrosion rates measured in autoclave experiments, is controlled by the siderite nucleation phenomena occurring at the interphase.
In this paper the key property differences between solders and TLPS interconnect technologies are compared in detail for MLCC interconnects. The development of a new range of nickel Base Metal Electrode C0G MLCC stacks rated for 200oC is described and performance compared to traditional Precious Metal Electrode (PME) stacks. Thermal cycling performance to 200oC of BME X7R stacks made with 10Sn/88Pb/2Ag solders are compared to similar stacks made with TLPS interconnects of Cu-Sn and In-Ag. The development of leadless stacks, a new bulk capacitance form factor enabled by TLPS technology, is described and their properties compared to traditional stacks.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Electrochemical impedance spectroscopy on thermal ageing evaluation of epoxy ...eSAT Journals
Abstract This research concentrates on the thermal ageing of a full 3-coat system with sacrificial pigment (zinc rich) primer on mild steel where the temperature dependence test is conducted to explore the correlation between the coating resistances with the corrosion rate underneath the coating. Electrochemical impedance spectroscopy (EIS) is introduced over a range of temperature to extract activation energies for the rate of controlling processes in the corrosion reactions. It is expected that the zinc rich primer does not form a barrier coating for the metal substrate rather it will be the most active component of the substrate in the electrochemistry. Full 3-coat system with zinc rich primer show the extracted activation energy from coating resistance is significantly lower than the activation energy extracted from the charge transfer resistance. This suggested that the coating resistance from EIS cannot be controlling the corrosion reaction. The activation energies generated for the corrosion process here (78–97 kJmol-1) are very much higher than those of ion transport through the coating (19–37 kJmol-1) during early immersion. Further interesting findings come from the activation energy trends over time particularly for the corrosion process which shown that the value is decreasing where at the end of exposure, the activation energy values for coating and charge transfer resistance become quite similar. It is suggested that at this stage ion transport in the coating might be controlling the corrosion process unlike at the beginning; the activation energy is getting smaller due to coating degradation. Index Terms: epoxy coating, electrochemical impedance spectroscopy, thermal effect, zinc rich primer
The Bucket Barricade protects a lineman from weather, inadvertent contact with energized equipment, and flying debris.
These are all very good reasons to have the Bucket Barricade at your work site. As with any new product, questions always arise as to the design. This slideshow answers some of those questions.
Perovskite Solar Cells
a short general overview presentation
hadi maghsoudi
device structure
crystal structure
preparation synthesis method
review papers
This paper presents information about fast warm cathode for microwave tubes applications. Its mechanical profile and thermal characteristics are discussed.
CIGS solar cells are one of the leading thin film solar cells to be made commercially viable. There are a lot of ways in manufacturing it and we have specialized a two stage process which gives advantages over material growth during commercial manufacture. An advancement of the two stage process is done to increase the throughput and maximize profits. A lab scale emulation of the commercial process is done to study device performance as a result of the advanced process. Factors such as reproducibility and elemental optimization were a concern and the reason behind these concerns were researched. This thesis serves as an experimental test bed to study device performance before up-scaling the growth recipe for pilot production.
In the material testing laboratory, a Charpy impact test was performed on three different types (hot,cold,and steel alloy)of steels testing each variety at four different temperatures (32°C(RT), 100°C,0°C and -22°C ). From results (shown below), we determined that the a transition is from ductile failures to brittle failures
1. Tests - ResultsSample Preparation
The solder joints tested in this study were composed of a Sn-Ag-Cu
alloy of Sn-3.0Ag-0.5Cu wt.% (SAC 305). To construct these
polycrystalline specimens, Cu blocks were cut to dimensions of
11mm x 13mm x 6mm, and their broad faces were polished to 4000
grit. After the blocks are soldered they are cut into sheets. These
sheets are then polished with various slurries to produce a damage
free surface suitable for examination under a Polarized Light
Microscope (PLM) or Electron Backscatter Diffraction (EBSD) .
Abstract
The restriction of toxic leaded solders by recent policies has
made Sn-Ag-Cu alloys the prevailing replacement for solder
systems. However, the electromigration damage they must
withstand poses a major reliability issue. In order to
quantify the electromigration damage a simple and efficient
testing apparatus was built to conduct electromigration
tests under desirable conditions. Joule heating, temperature
gradients, and current crowding in the solder joints
contribute and complicate the analysis of electromigration.
Thus, this project attempted to build an electromigration
testing apparatus that provided constant temperatures and
current densities through a solder sample. Results showed
that porcelain mounts were great electrical insulators but
had a low thermal conductivity which retained heat in the
system, proving detrimental to the experiment. Glass on the
other hand proved to be an adequate base for the mount
since it did not retain heat in the system as much. We
expect future electromigration tests will utilize glass
mounts with three mechanically braced Cu heat sinks.
Acknowledgments
• J.W. Morris, Jr., Ph.D., & Xioranny Linares – Mentors
• Rhonda La Grande, Aaron Chan, & Linda Dada – Lab partners
• Cal NERDS Staff and Scholars – Support & Encouragement
• Cal NERDS & UC Leads program – Funding
Tests - Results
• Prepared samples are connected to the anode and cathode using
silver paste.
• Current applied to the system varies between 20A – 25A, in
order to achieve a current density of 11.5 kAcm-2 across the
sample.
• The sample is placed in an oven until thermal equilibrium is
sustained at about 100°C.
• Constant current is applied for 2 days.
Conclusions
• Although both the porcelain tile and glass have a low
thermal conductivity, using a glass mount proved a lot
more beneficial because it dissipates heat a lot faster
than the traditional ceramic.
• Leveled heat sinks are vital for support and help prevent
the sample from deformation.
• Mechanically bracing the system alleviates stresses on
the JB Weld epoxy and extends the apparatuses’ lifetime.
Alejandro Cota, Xioranny Linares, Rhonda La Grande, Aaron Chan, J.W. Morris, Jr., Ph. D.
Department of Materials Science and Engineering, University of California, Berkeley, CA 94720
References
Linares, Xioranny, et al. 2013. The Influence of Sn Orientation on Intermetallic
Compound Evolution in Idealized SnAgCu 305 Interconnects: An Electron
Backscatter Diffraction Study of Electromigration>. Accessed 2013 Aug 2.
Figure 2: Simple schematic of
testing a sample.
Figure 6: Current design uses a
glass base, but lacks mechanical
braces on cathode and anode.
For further information
Please contact acota@berkeley.edu or visit:
http://www.mse.berkeley.edu/groups/morris/Research.html. Alejandro Cota
is a Mechanical & Materials Science Engineering major at UC Berkeley.
Step 1: Polish
block faces,
coat with flux,
and match
together while
separated by
250μm spacers.
MAKING A TESTING APPARATUS FOR CONDUCTING
ELECTROMIGRATION TESTS
Background
Many efforts to study electromigration in the past have
proven unsuccessful due to the lack of a competent
electromigration testing apparatus. The goal of this
experiment is to build and improve a test apparatus
capable of upholding a constant temperature, and constant
current density during the length of the sample testing
period. Achieving these constant conditions allow us to
isolate and study the effects of specific electromigration
parameters, such as the effects of varying current densities.
Future Work
Figure 7: Ideal
Electromigration
testing apparatus
with a glass base.
e-
jeZDCJ SnkTSnCu
EM
SnCu
SnCu
*
,,
,
CCu,Sn : Atomic density of Cu in Sn
DCu,Sn : Diffusivity of Cu in Sn
Z* : Effective charge
e : Electron charge
ρ : Resistivity
j : Current density
k : Boltzmann Constant
T : Temperature
Electromigration Equation
Three types of drill bits can be successfully used on glass:
tungsten carbide spear-tipped drill bits, diamond-tipped drill
bits, or diamond-coated drill bits.
Obtain appropriate drill bit to build five testing apparatuses,
all with mechanical braces and Cu heat sinks.
Use an Infrared Camera to evaluate the thermal gradient of the
entire apparatus including the specimen.
Step 2: The
composite block
was placed in
molten Sn-Ag-Cu
at 375°C for 30
seconds.
Step 3: Quickly
quench in ice-
water until block
cools.
Figure 4: New and modified testing
apparatus uses porcelain tile base.
Figure 5: Five
samples were
tested using the
new apparatus.
Figure 3: Glass base, cathode and
anode, missing a failed idealized
Cu||Sn||Cu interconnect due to failure
after running the sample through
the experimental procedure.
• Glass base electrically
insulates the experiment
from the oven.
• Both anode and cathode use
a Cu heat sink.
• Samples failed due to uneven
heat distribution.
• An additional Cu heat sink
must be introduced to the
system.
• JB Weld epoxy becomes
brittle causing cathode and
anode to fall off.
• A mechanical brace would
reduce stresses on JB Weld.
Step 4: Once
cooled, all blocks
were cut into
sheets roughly
500μm thick.
Figure 1: Sample preparation diagram.
• Porcelain base electrically
insulates the experiment
from the oven.
• Applied a third Cu heat sink.
• Machined a bronze-coated
sheet metal brace for both
anode and cathode.
• Samples deformed as they softened from high heat and unleveled
heat sinks.
• Extracting samples required an additional 4-6 hours compared to
glass base due to porcelain’s high heat insulation and low thermal
conductivity.
• Porcelain tiles acted as a radiant heat source and generated
unwanted thermal profiles throughout the system.
• Cu heat sinks were made level. Twice as much JB Weld epoxy aids
in heat distribution away from the sample.
• Design proved successful. Addition of mechanical brace will
further improve the design.
• Samples survived the two day experimental procedure, and have
been extracted for further analysis.
