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Microwave and Millimeter-Wave Packaging and
Manufacturing 101
Accuracy of Package and
Interconnect Simulation Models
HeeSoo LEEAgilent TechnologiesEEsof
3DEM Technical Lead
Jonathan StorieAgilent TechnologiesHigh Frequency Technology
Center
Packaging Engineer
Microwave and Millimeter-Wave Packaging and
Manufacturing 101
Packages and Interconnects
• Packages and interconnects are common parts in modern
microwave and high speed digital designs
• Smaller form factor (higher pin counts and smaller pitch size)
and higher operating frequency increase design challenges
Package
Connectors
Interconnect
Transitions
Transitions
Interconnect
DUT Board
Microwave and Millimeter-Wave Packaging and
Manufacturing 101
Common Model Types for
Package and Interconnect
1. Lumped Models
2. Measured Data Models
3. Electro-Magnetic (EM) Models
4. Broadband Spice Models
Microwave and Millimeter-Wave Packaging and
Manufacturing 101
1. Lumped Models
• Extracted and optimized from measured or simulation data
• Increased complexity with higher pin counts
• Intuitive physical meaning for models but only good for low
frequency or narrow band applications
• Time consuming model development process
Red: Measured
Blue: Modeled
S11Package
Models
Microwave and Millimeter-Wave Packaging and
Manufacturing 101
What Affects the Lumped
Model’s Accuracy
• Accuracy of measured or simulated data
• Accuracy of circuit models
– Topology and complexity
– Number of ports/pins for packages
Microwave and Millimeter-Wave Packaging and
Manufacturing 101
2. Measured Data Models
• Very accurate black box s-parameter models
• No intuitive physical meaning for models
• Limited port numbers for measurement
• Tedious and expensive measurement setup and process
Microwave and Millimeter-Wave Packaging and
Manufacturing 101
What Affects the Measured Data
Model’s Accuracy?
• Accuracy of Calibration– Type of calibrations, calibration standard, etc
• Fabrication/assembly tolerances and repeatability– Board to board, connector to connector, wirebond to wirebond variations
– Measurement engineers’ experience level
Microwave and Millimeter-Wave Packaging and
Manufacturing 101
= Pre-measurement error correction
= Post-measurement error correction
Most
Accurate
Easiest
S-Parameter De-embedding
Port ExtensionTime Domain Gating
Normalization
Reference Plane Calibration
Thru-Reflect-Line (TRL)
Line-Reflect-Match (LRM)
Short-Open-Load-Thru (SOLT)
Typical Fixture Error Correction
Techniques for Measurements
Microwave and Millimeter-Wave Packaging and
Manufacturing 101
3. Electro-Magnetic (EM) Models
• Very accurate Electro-Magnetic (EM) simulation based s-
parameter models
• Allows to easily model fabrication/assembly tolerances for
DFM (design for manufacturing) or design centering
• No limitation on number of ports
• Versatile EM visualization provides an extra benefit for
performance and model enhancement
Microwave and Millimeter-Wave Packaging and
Manufacturing 101
FDTD
FEM MoM3D Planar structures
Full Wave and Quasi-Static
Dense & Compressed Solvers
Frequency Domain
Multiport simulation at
no additional cost
High Q
3D Arbitrary Structures
Full Wave EM Simulation
Direct, Iterative Solvers
Frequency Domain EM
Multiport simulation at
no additional cost
High Q
3D arbitrary structures
Full Wave EM simulations
Handles much larger and complex problems
Time Domain EM
Simulate full size cell phone antennas
EM simulations per each port
GPU based hardware acceleration
FDTD ( Finite Difference Time Domain )
FEM ( Finite Element Method )
MoM ( Method of Moment )
3DEM Simulation Technologies
Microwave and Millimeter-Wave Packaging and
Manufacturing 101
What Affects the EM Model’s
Accuracy
• Accuracy of Material Properties– Conductivity, dielectric constant, loss tangent, conductor roughness, etc
• Accuracy of 3D (drawing) model – simulated vs. measured
– Fabrication/assembly tolerances may not be captured
• Simulation Accuracy – solvers, basis functions, delta-s,etc
Same bondwires? – length, bond height Vendor provided material properties are accurate?
Microwave and Millimeter-Wave Packaging and
Manufacturing 101
EM Models - Thru Line
• 1 inch long, simple 50 ohm transmission line
• Roger’s 4350B PC board: εr=3.66, TanD= 0.0037
• Southwest 1492-04A-5 End Launch 2.4mm connectors
EMPro 3D Model
Without
Connectors
Real Board Assembly
Microwave and Millimeter-Wave Packaging and
Manufacturing 101
Measured Data For Thru Line
• Measured various sample combinations of thru line boards
and connectors up to 50GHz
• Less variations at low frequencies but a bit more at higher
frequencies More Variations
on
Higher Frequencies
10+dB
Microwave and Millimeter-Wave Packaging and
Manufacturing 101
Factors on Measurement
Variations
• Connector to board ground contacts
• Connector launch on board trace
• Cleanness of plated side board contact to
connectors
• Copper thickness and etching (over, under)
variations
• Solder joint thickness and void (coverage)
• Assembly variations
• Poor wetting
Microwave and Millimeter-Wave Packaging and
Manufacturing 101
EM Model Data for Thru Line
(EMPro FEM)
• Various 3D model combinations
– Gap between board and connectors, 0 ~ 3mil gap
– Point ground vs. no-ground for connector to board contacts
– Recessed PTFE vs. non-recessed PTFE
Microwave and Millimeter-Wave Packaging and
Manufacturing 101
Factors on EM Data Variations
• Are modeled (drawn) vs. measured
(assembled) the same?
– Connector to board gap and ground contacts
– Cleanness of plated side board contact to
connectors
– Copper thickness and etching (over or under?)
– Measured includes the connector but not in
modeled
• Are material properties accurate at higher
frequencies?
– Conductivity, dielectric constant, loss tangent
Microwave and Millimeter-Wave Packaging and
Manufacturing 101
S11 Modeled vs. Measured
• Excellent agreement up to 20GHz
• Very good agreement for 30-40GHz
Diverging more at
Higher Frequencies
Thick Black Trace (EM)
Microwave and Millimeter-Wave Packaging and
Manufacturing 101
• EM models underestimated the loss, which is about 1dB at 50GHz but
the trend agree very well
• The accuracy of material property for conductors and dielectric (4350B)
is questionable at 50GHz
– The modified conductivity and loss tangent provide very good agreement
– The optimum εr and loss tangent can be easily found
S21 Modeled vs. Measured
With given material
properties
1dBWith modified material
properties
MeasuredCond=3e7, tand=0.009
Cond=5.8e7, tand=0.0037
Microwave and Millimeter-Wave Packaging and
Manufacturing 101
Radiated Loss Increases at
Higher Frequencies
• Radiated power (loss) increases at higher frequencies
Significant
Increase of
radiated power
Input power
Radiated power
E field at 26G
E field at 50G
Directivity at
26G
Directivity at
50G
Microwave and Millimeter-Wave Packaging and
Manufacturing 101
50 Ohm Termination on QFN2x2
• 50 ohm Termination on QFN 2mm X 2mm package
EMPro 3D Model Without Connectors
Microwave and Millimeter-Wave Packaging and
Manufacturing 101
S11 Modeled vs. Measured
• Reasonable agreement
Measured
Samples
Thick Black Trace (EM)
Microwave and Millimeter-Wave Packaging and
Manufacturing 101
Factors on Data Variations for
QFN2x2 with 50Ohm Term
• Are modeled (drawn) vs. measured
(assembled) the same?
– Connector to board gap and ground contacts
– Cleanness of plated side board contact to
connectors
– Copper thickness and etching (over or under?)
– Measured includes the connector but not in
modeled
– Bondwires length and height
• Are material properties accurate at higher
frequencies?
– Conductivity, dielectric constant, loss tangent
– Compound mold
Microwave and Millimeter-Wave Packaging and
Manufacturing 101
4. Broadband Spice Models
• Broadband model
performance
• Circuit models include
R,L,C, and sources
• Various netlist format
– Hspice
– Spectre
– Spice3
– ADS
• Very fast model
generation
Microwave and Millimeter-Wave Packaging and
Manufacturing 101
What Affects the Broadband
Spice Model’s Accuracy
• Accuracy of Input data (modeled or measured)
• Generally BB models are very accurate not only for
magnitude but also offers excellent phase match
Microwave and Millimeter-Wave Packaging and
Manufacturing 101
Summary of Package and
Interconnect Models
Lumped Measured EM Broadband
Spice
Model Format R,L, C circuit
models
S-parameters S-parameters Circuit models
Frequency Low High High High
Accuracy Good Excellent Excellent Excellent
Time Domain
Compatibility
Yes Convolution
Required
Convolution
Required
Yes
Base Data for
Modeling
Measured or
EM data
Direct
Measurement
Full Wave EM
Simulation
Measured or
EM data
Engineering
Efforts
High Medium Low Low
Cost High High Medium Low
Microwave and Millimeter-Wave Packaging and
Manufacturing 101
Summary
• Packages and interconnects are common parts in modern
microwave and high speed digital designs
• Four types of packages and interconnect models have
advantages and disadvantages
• EM and Broadband spice models offer the most economical
solution for packages and interconnect models
• The accuracy of EM models depends on various factors
such as material properties, fabrication/assembly tolerances
• Corner case, worst-case, or even statistical models may be
required for packages and interconnect models
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Product specifications and descriptions
in this document subject to change
without notice.
© Agilent Technologies, Inc. 2012
Printed in USA, May 5, 2012
5990-6364EN
www.agilent.com
