1. Fall 2015 Probe Testing
ANSYS Study
For ON SEMICONDUCTOR
By: Justin Smith
2. Background
ON SEMICONDUCTOR has completed previous
Finite Element Analysis (FEA) studies to make a
comparison with a Probe testing tip and the
Bonding Pads of a wafer board. A wafer board is
an 8” disk with layers of Silicon, SiO2, and
Aluminum, which creates a circuit board chip
used in cell phones and other technologies.
During physical testing, the SiO2 layers between
the aluminum at times will crack, causing a short
circuited malfunctioning part. After Static FEA
analysis was completed, it was suggested that a
Dynamic analysis should be made to further
better understand the causing of the cracking
layers.
Photo credit: Wikipedia.com
Figure 1: 8” Wafer Board Probe Tester
3. Discussion
The results of a Dynamic Study, once completed would allow for more
accurate results. This study serves as a “standard work process” (step
by step instruction manual) to allow for future studies done with
different Probe Models with different shapes and angles to suggest as
which probe should be implemented in future physical probe testing.
4. 0.8um-0.9Tip-13-Low
To begin the study it is necessary to first select an IGES (.igs) file as
described in the next slide. We will proceed with 0.8um-0.9Tip-13-Low.
5. Import Selected IGES.igs from the Google Drive
• Start up ANSYS Workbench 16.2
• Create a new “Static Structural” Study and save project workbook as the
IGES File name.
• Right click GeometryImport
GeometryBrowse . . .
• Locate IGES File: My DriveBYU-I
ANSYSProbe IGES Models
• Ex: 0.8um-0.9Tip-13-Low.igs
7. • The material data for each material was referenced from the data
sheet located on the Google Drive [Material Properties.xlsx].
• Aluminum
• Silicon
• SiO2
• Tungsten
• Make sure to double check the material properties under the
“Engineering Data” section before running your program, once you
load the Project Workbook on a new computer, the default units may
be chosen, if so, you may have to change the units as shown in the
next slide.
• Don’t forget to check the units as you open the “Geometry” or “Model”
sections.
• Units should be in Metric.
Engineering Data: Material properties
12. Model: Connections (Contacts)
• Contact Type used
between probe tip
and aluminum pad:
Frictional.
• The ‘X’ distinguishes
a suppressed contact
that is unrelated of
the 105 contacts
automatically
generated from an
IGES File.
• Once a contact is
accepted, it
automatically
receives a new
name:
• Ex: “Contact Region
2” -> “Frictional – Al
To Probe – Tip”
18. As shown in the previous slide, the right hand
side shows two windows with a red and blue
shape. The red depicts the face of the ‘Contact
Body’(top layered body with contacting face at
the bottom of that part) while the ‘Target Body’
(is the lower leveled part with the upper face as
the contact face) is shown in blue.
It is standard for .igs files to select both top and
bottom faces for each part. Since one face of the
contact body is in contact with one face of the
target body,
Model: Connections
45. Model: Mesh
• Due to the limited amount of nodes
and elements, the element size has
been reduced.
• If you are able to have enough nodes
and elements, you will have a much
better success rate.
Nodes: 15,798
Elements: 6,648
47. Model: Mesh (Hex Dominant Method Probe Body)
• This Meshing Method has not been utilized due to a restraint on the
number of nodes and element sizes. It was however used in previous
FEA simulation models.
48. Model: Mesh (Hex Dominant Method Probe Tip)
• In comparison to the previous slide, this method was utilized because
the part is relatively small and able to be calculated.
49. Model: Mesh (Body Sizing Outer)
• This shows the Method for body sizing of the outer pieces. *Note: the
Element Size is a lot smaller than previous ANSYS studies done January
through August 2015, where most body sizing are X.XXXe-6, because of
the restriction of Element and Nodes, this remains true for all of the
Body Sizing Meshes.
50. Model: Mesh (Body Sizing Probe Body)
• This was adapted to create a mesh on the Probe Body due to the
restriction of Nodes and Elements made in this study. *This Mesh
Method replaces the Hex Dominant Method for the Probe Body.
51. Model: Mesh (Face Meshing)
• This is an additional Mesh Study, to see if there would be any drastic
changes in the model.
53. Static Structural: Fixed Support
38 Faces: All Pad Exterior Faces(4 Sides X 9 Pad Layers)=36
Inside and Outside Bottom faces =2
54. Static Structural: Displacement
1 Face: As shown in Yellow.
The Displacement should be directed in the –Y Direction as shown in the coordinates
55. Static Structural: Solution
(Maximum Principal Stress)
*SiO2 Ultimate
Tensile Strength
is 76 MPa
*Exceeds
tensile strength
for SiO2
(2.81E8 Pa is
larger than
76E6 Pa)
*This wafer
board will crack
during probe
testing
*Top 3 Layers*
56. Static Structural: Solution
(Maximum Principal Stress 2)
*SiO2 Ultimate
Tensile Strength
is 76 MPa
*Exceeds
tensile strength
for SiO2
(1.63E9 Pa is
larger than
76E6 Pa)
*This wafer
board will crack
during probe
testing
*Top 3 Layers
with Probe*
57. Static Structural: Solution
(Directional Deformation)
*The Max Deformation
is going to be pushed in
the negative Y-Direction
and will have a value of
1.22E-7 m.
*Top 3 Layers
with Probe*
58. Static Structural: Solution
(Directional Deformation 2)
*The Max Deformation
is going to be pushed in
the negative Y-Direction
and will have a value of
2.28E-7 m.
*Top 3 Layers*
59. Static Structural: Solution
(Equivalent Stress)
*SiO2 Ultimate
Tensile Strength
is 76 MPa
*Exceeds
tensile strength
for SiO2 (4.0E8
Pa is larger
than 76E6 Pa)
*This wafer
board will crack
during probe
testing
*Top Layer*
60. Static Structural: Solution
(Equivalent Stress 2)
*SiO2 Ultimate
Tensile Strength
is 76 MPa
*Exceeds
tensile strength
for SiO2
(3.68E8 Pa is
larger than
76E6 Pa)
*This wafer
board will crack
during probe
testing
*Top 3 Layers*
61. Static Structural: Solution
(Maximum Principal Stress 3)
*SiO2 Ultimate
Tensile Strength
is 76 MPa
*Exceeds
tensile strength
for SiO2
(2.19E8 Pa is
larger than
76E6 Pa)
*This wafer
board will crack
during probe
testing
*Top Layer*
62. Static Structural: Solution
(Maximum Principal Stress 4)
*SiO2 Ultimate
Tensile Strength
is 76 MPa
*Exceeds
tensile strength
for SiO2
(2.65E8 Pa is
larger than
76E6 Pa)
*This wafer
board will crack
during probe
testing
*2nd Layer*
64. Transient Structural: Fixed Support
38 Faces: All Pad Exterior Faces(4 Sides X 9 Pad Layers)=36
Inside and Outside Bottom faces =2
65. Transient Structural: Displacement
1 Face: As shown in Yellow.
The Displacement should be directed in the –Y Direction as shown in the coordinates
66. Transient Structural: Solution
(Maximum Principal Stress)
*SiO2 Ultimate
Tensile Strength
is 76 MPa
*Exceeds
tensile strength
for SiO2
(5.03E8 Pa is
larger than
76E6 Pa)
*This wafer
board will crack
during probe
testing
*Top 3 Layers*
67. Transient Structural: Solution
(Maximum Principal Stress 2)
*SiO2 Ultimate
Tensile Strength
is 76 MPa
*Exceeds
tensile strength
for SiO2
(4.15E9 Pa is
larger than
76E6 Pa)
*This wafer
board will crack
during probe
testing
*Top 3 Layers
with Probe*
68. Transient Structural: Solution
(Directional Deformation)
*The Max Deformation
is going to be pushed in
the negative Y-Direction
and will have a value of
5.08E-5 m.
*Top 3 Layers
with Probe*
70. Transient Structural: Solution
(Directional Deformation 2)
*The Max Deformation
is going to be pushed in
the negative Y-Direction
and will have a value of
3.66E-7 m.
*Top 3 Layers*
71. Transient Structural: Solution
(Equivalent Stress)
*SiO2 Ultimate
Tensile Strength
is 76 MPa
*Exceeds tensile
strength for SiO2
(6.58E8 Pa is
larger than 76E6
Pa)
*This wafer
board will crack
during probe
testing
*Top Layer*
72. Transient Structural: Solution
(Equivalent Stress 2)
*SiO2 Ultimate
Tensile Strength
is 76 MPa
*Exceeds tensile
strength for SiO2
(6.58E8 Pa is
larger than 76E6
Pa)
*This wafer
board will crack
during probe
testing
*Top 3 Layers*
73. Transient Structural: Solution
(Maximum Principal Stress 3)
*SiO2 Ultimate
Tensile Strength
is 76 MPa
*Exceeds
tensile strength
for SiO2 (4.17E8
Pa is larger than
76E6 Pa)
*This wafer
board will crack
during probe
testing
*Top Layer*
74. Transient Structural: Solution
(Maximum Principal Stress 4)
*SiO2 Ultimate
Tensile Strength
is 76 MPa
*Exceeds
tensile strength
for SiO2
(4.36E8 Pa is
larger than
76E6 Pa)
*This wafer
board will crack
during probe
testing
*2nd Layer*
75. Results and Conclusion
• Through the duration of the Semester, I have made progress on the Dynamic FEA Study
using ANSYS Workbench 16.2 software. A greater understanding of Finite Element
Methodology was gained through many hours of real life application of a real life
problem. Some areas of concentration include:
• Static V.S. Dynamic Simulations, loading .igs files, Engineering Data, Geometry, Contact
Connections, Mesh Methods, Emphasis of the number of nodes and elements, along with solving
and comparing results to Tensile Stresses of a material found in Engineering Data.
• Once a deeper interest if the study was centered on the Contacts Connections of the
Model, a successful Analysis was made. The most noticeable contribution was that
during the Dynamic Modeling, the Probe Tip did not puncture or poke through the
bonding pad.
• The results from this study show a great step forward in the Dynamic Modeling of the
Probe Tip Analysis.
• Through this power point presentation, a person would be able to follow the steps in
creating other Dynamic Model Simulations using the 60+ IGES files provided by ON
SEMICONDUCTOR.
76. Suggestions for Improvement
• Where possible, work at the same computer workstation and save your work to
that hard drive. I’ve found that when I save work on an academic computer
where the capability has a limit of 250,000 Nodes and Elements and copy or save
my work to a flash drive or the Google Drive, and work on a personal laptop
computer with the student version which has a limit of 32,000 Nodes and
Elements, it sometimes cannot open or read the .wbpj files.
• Refer to previous documentation located on the Google Drive:
• Increase amount of Elements and/or reduce the Element Sizing for more concise results.
• Replicate the settings for the Max Principle Stress etc. found under the Solution Tab of the
Model.
• If applicable, divide the probe into different sections or parts (as depicted in the “Excel
Worksheet for Probe Models.xlsx” under slide 2 “Base Model Map”) and unite them together
as one Part in the Geometry Developer, switch to the Modeling Developer and make sure
that the contact points are bonded. Then create a mesh type with smaller body sizing for
each part to be uniform with each other, the smaller the better.
• Refer to “ANSYS Simulation Results-Short.pptx” as a guide for accumulating results when
carrying out a simulation study and while gathering information for writing a report.
