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March 4 - 7, 2018
Hilton Phoenix / Mesa Hotel
Mesa, Arizona
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Speedy Reflections - Electrical Simulation BiTS 2018 Session 4 Presentation 1
March 4-7, 2018 Burn-in & Test Strategies Workshop www.bitsworkshop.org
Application of Uncertainty Quantification in
RF Simulations of Test Socket
Noah Weichselbaum Ph.D., PE
Frank Zhou Ph.D.
Resty Querubin
Smiths Interconnect
BiTS Workshop
March 4 - 7, 2018
Conference Ready
mm/dd/2014
Speedy Reflections - Electrical Simulation BiTS 2018 Session 4 Presentation 1
March 4-7, 2018 Burn-in & Test Strategies Workshop www.bitsworkshop.org
Contents
• Introduction
• Experimental Measurements for Verification Data Set
• Setup of 3D EM Simulations for IC chip test sockets – DaVinci 35G
• Implementation of mechanical tolerances and coupling of mechanical FEA
with EM simulations
• Need for frequency dependent material measurements – DaVinci 45G
• Application of simulations with uncertainty quantification to new low return
loss single end probe design
• Summary and Future Work
Application of Uncertainty Quantification in RF Simulations of Test Socket 2
Speedy Reflections - Electrical Simulation BiTS 2018 Session 4 Presentation 1
March 4-7, 2018 Burn-in & Test Strategies Workshop www.bitsworkshop.org
Introduction
Application of Uncertainty Quantification in RF Simulations of Test Socket 3
• The objective of this work was to develop a more
robust simulation tool for designing new high speed
interconnects.
• Designs focused on are Smiths Interconnect
impedance controlled sockets:
– DaVinci 35G – capable to 20 Gbps
• Insertion Loss @ -1 dB > 35 GHz
• Return Loss @ -10 dB > 35 GHz
– DaVinci 45G – capable to 26 Gbps
• Insertion Loss @ -1 dB > 40 GHz
• Return Loss @ -10 dB > 40 GHz
Speedy Reflections - Electrical Simulation BiTS 2018 Session 4 Presentation 1
March 4-7, 2018 Burn-in & Test Strategies Workshop www.bitsworkshop.org
Introduction
Application of Uncertainty Quantification in RF Simulations of Test Socket 4
• Benefit of impedance controlled probes for high
speed applications:
– Pitch and location of grounds have greatly reduced
impact on impedance.
– Socket material does not impact impedance due to
Smiths Interconnect proprietary material.
• To demonstrate this six 3D EM simulations are
presented with the following patterns (3 w/
standard socket and 3 w/ impedance controlled):
G
G
S
G
G G
G
G
S
G
G
G G
G
S
G
G G
G
G
G
Edge Corner Center
DaVinci 45G - Impedance Controlled
Speedy Reflections - Electrical Simulation BiTS 2018 Session 4 Presentation 1
March 4-7, 2018 Burn-in & Test Strategies Workshop www.bitsworkshop.org
Introduction
Application of Uncertainty Quantification in RF Simulations of Test Socket 5
Legend:
Standard Socket Edge DaVinci 45G Socket Edge
Standard Socket Corner DaVinci 45G Socket Corner
Standard Socket Center DaVinci 45G Socket Center
Single End Return Loss Single End Insertion Loss
Speedy Reflections - Electrical Simulation BiTS 2018 Session 4 Presentation 1
March 4-7, 2018 Burn-in & Test Strategies Workshop www.bitsworkshop.org
Introduction
Application of Uncertainty Quantification in RF Simulations of Test Socket 6
• Use of worst case tolerance stack analysis or Monte Carlo simulations are common tools for
mechanical designers.
– Example presented is alignment of BGA DUT in an
interconnect pocket with worst case tolerance stack
• Application of similar analysis for mechanical properties to RF - Attenuation per length (α)
through a uniform transmission line can be estimated with the following first order
approximations: 𝛼𝑑𝐵 = 𝛼𝑐𝑜𝑛𝑑𝑢𝑐𝑡𝑜𝑟 + 𝛼𝑑𝑖𝑒𝑙𝑒𝑐𝑡𝑟𝑖𝑐
𝛼𝑐𝑜𝑛𝑑𝑢𝑐𝑡𝑜𝑟 =36
𝑤𝑍𝑜𝑓
𝛼𝑑𝑖𝑒𝑙𝑒𝑐𝑡𝑟𝑖𝑐 = 2.3𝑓𝑡𝑎𝑛(𝛿) 휀𝑟
𝜎 = 𝐷1 + 𝐷1,𝑡𝑜𝑙 +𝐻1 + 𝐻𝑡𝑜𝑙 + 𝐹𝑡𝑟𝑢𝑒 𝑝𝑜𝑠 +𝐻𝑡𝑟𝑢𝑒 𝑝𝑜𝑠
2+ 𝐹 + 𝐹𝑡𝑜𝑙
+ 𝐽𝑡𝑜𝑙 − 𝐽 + 𝐵𝑃𝑡𝑜𝑙 + 𝐶𝑡𝑜𝑙
𝜎 = 𝑇𝑖
Speedy Reflections - Electrical Simulation BiTS 2018 Session 4 Presentation 1
March 4-7, 2018 Burn-in & Test Strategies Workshop www.bitsworkshop.org
Experimental Measurement Setup
Application of Uncertainty Quantification in RF Simulations of Test Socket 7
• Each signal/return configuration is measured on an Agilent VNA
utilizing Smiths Interconnect designed fixtures to characterize the
S-parameters through 67 GHz.
• The fixture influence is de-embedded from the S-parameter result
to determine the S-parameters for the socket only.
• Have conducted measurement-to-measurement verification with
measurements from an outside lab using the same socket
• Data presented here for DaVinci 35G but limited to 20 GHz due to
proprietary nature, validated performance to 37 GHz by outside lab
~4mm
Speedy Reflections - Electrical Simulation BiTS 2018 Session 4 Presentation 1
March 4-7, 2018 Burn-in & Test Strategies Workshop www.bitsworkshop.org
DaVinci 35G Measurement Verification Data Set
Application of Uncertainty Quantification in RF Simulations of Test Socket 8
Single End Return Loss Single End Insertion Loss
Magnitude [
dB
]
Legend:
Measured Data
Speedy Reflections - Electrical Simulation BiTS 2018 Session 4 Presentation 1
March 4-7, 2018 Burn-in & Test Strategies Workshop www.bitsworkshop.org
3D EM Simulation Setup
Application of Uncertainty Quantification in RF Simulations of Test Socket 9
• 3D geometry setup in test condition in
SolidworksTM and imported directly to ANSYS
HFSSTM.
• Geometry is parameterized in SolidworksTM to
allow for sensitivity study of manufacturing
tolerances impact on RF performance.
• Material properties and boundary conditions
assigned and frequency sweep analyzed for
setup.
• For parameterization chose to assess worst
case tolerance stack up instead of statistical
analysis with Monte Carlo Simulation
HFSS setup Solidworks setup
Speedy Reflections - Electrical Simulation BiTS 2018 Session 4 Presentation 1
March 4-7, 2018 Burn-in & Test Strategies Workshop www.bitsworkshop.org
Comparison of Measured Data w/ Simulation with
Nominal Dimensions for Probe and Cavity
Application of Uncertainty Quantification in RF Simulations of Test Socket 10
Magnitude [
dB
]
Legend:
Measured Data
Baseline Simulation
Single End Return Loss Single End Insertion Loss
Speedy Reflections - Electrical Simulation BiTS 2018 Session 4 Presentation 1
March 4-7, 2018 Burn-in & Test Strategies Workshop www.bitsworkshop.org
Simulation Results for Best and Worst Case Based on
Parameterization of Probe and Cavity Tolerances
Application of Uncertainty Quantification in RF Simulations of Test Socket 11
Magnitude [
dB
]
Legend:
Measured Data Simulation with optimum performance
Baseline Simulation Simulation with worst case performance
Single End Return Loss Single End Insertion Loss
Speedy Reflections - Electrical Simulation BiTS 2018 Session 4 Presentation 1
March 4-7, 2018 Burn-in & Test Strategies Workshop www.bitsworkshop.org
Implementation of Mechanical FEA Simulations in
3D EM Simulation
Application of Uncertainty Quantification in RF Simulations of Test Socket 12
• Mechanical FEA simulations conducted in Solidworks CosmosWorks.
• Utilized to determine maximum stress and deflection within the socket
during the worst case scenario which will be when the socket is in the pre-
load condition.
• Deflection of socket then implemented in 3D EM simulation.
Speedy Reflections - Electrical Simulation BiTS 2018 Session 4 Presentation 1
March 4-7, 2018 Burn-in & Test Strategies Workshop www.bitsworkshop.org
Simulation Results with Implementation of Mechanical
FEA Results
Application of Uncertainty Quantification in RF Simulations of Test Socket 13
Magnitude [
dB
]
Legend:
Measured Data Simulation with optimum performance
Baseline Simulation Simulation with worst case and FEA deflection
Single End Return Loss Single End Insertion Loss
Speedy Reflections - Electrical Simulation BiTS 2018 Session 4 Presentation 1
March 4-7, 2018 Burn-in & Test Strategies Workshop www.bitsworkshop.org
Assessment of Probe Tilt from Cartridge
Alignment and FEA Analysis
Application of Uncertainty Quantification in RF Simulations of Test Socket 14
• Utilized information from the FEA analysis
coupled with worst case tolerance stack
analysis where cavity alignment is taken into
consideration.
• Impact of allowable probe tilt from this worst
case tolerance analysis presented.
Speedy Reflections - Electrical Simulation BiTS 2018 Session 4 Presentation 1
March 4-7, 2018 Burn-in & Test Strategies Workshop www.bitsworkshop.org
Simulation Results with Implementation of Mechanical
FEA Results and Probe Tilt
Application of Uncertainty Quantification in RF Simulations of Test Socket 15
Magnitude [
dB
]
Legend:
Measured Data Simulation with optimum performance
Baseline Simulation Sim with worst case, FEA deflect, & Probe Tilt
Single End Return Loss Single End Insertion Loss
Speedy Reflections - Electrical Simulation BiTS 2018 Session 4 Presentation 1
March 4-7, 2018 Burn-in & Test Strategies Workshop www.bitsworkshop.org
Impact of Frequency Dependent Dielectric
Properties on DaVinci 45G
Application of Uncertainty Quantification in RF Simulations of Test Socket 16
DaVinci 35G:
Coaxial
Structure
DaVinci 45G:
Optimized
Coaxial Structure
Speedy Reflections - Electrical Simulation BiTS 2018 Session 4 Presentation 1
March 4-7, 2018 Burn-in & Test Strategies Workshop www.bitsworkshop.org
Impact of Frequency Dependent Dielectric
Properties on DaVinci 45G
Application of Uncertainty Quantification in RF Simulations of Test Socket 17
𝛼𝑑𝑖𝑒𝑙𝑒𝑐𝑡𝑟𝑖𝑐 = 2.3𝑓𝑡𝑎𝑛(𝛿) 휀𝑟
Magnitude [
dB
]
Legend:
Measured Data
Baseline Simulation
Simulation with uncertainty for mechanical performance
Simulation with uncertainty for mechanical performance
and frequency dependent material properties*
* Frequency dependent data for materials
through 20 GHz from 2003 BiTS presentation
by Mroczkowski, J.
Single End Return Loss Single End Insertion Loss
Speedy Reflections - Electrical Simulation BiTS 2018 Session 4 Presentation 1
March 4-7, 2018 Burn-in & Test Strategies Workshop www.bitsworkshop.org
Implementation of Uncertainty Analysis for Development of
Low Return Loss Single End Probe Design
Application of Uncertainty Quantification in RF Simulations of Test Socket 18
Legend:
Measured Data
Simulation Data
Single End Return Loss
Speedy Reflections - Electrical Simulation BiTS 2018 Session 4 Presentation 1
March 4-7, 2018 Burn-in & Test Strategies Workshop www.bitsworkshop.org
Summary and Future Work
Application of Uncertainty Quantification in RF Simulations of Test Socket 19
• Benefits of parameterized studies in HFSS to better understand impact of
uncertainty for both mechanical tolerance and material properties.
– Application of unilateral tolerances typical for mechanical fit to RF performance
• Clear need for frequency dependent measurements of material properties to have
successful simulations at higher frequency.
– Smiths Interconnect test lab in process of developing these capabilities.
• Utilizing these design techniques for development of next generation high frequency
test sockets.
𝛼𝑑𝑖𝑒𝑙𝑒𝑐𝑡𝑟𝑖𝑐 = 2.3𝑓𝑡𝑎𝑛(𝛿) 휀𝑟