ANSYS for Tablet Computer Design · 2012. 10. 26. · Perform Drop test of Tablet PC from height of 4 feet onto a concrete floor at an angle of 45 degree using ANSYS Explicit Dynamics

© 2011 ANSYS, Inc. June 18, 2012 1

ANSYS for Tablet Computer Design

Steven G. Pytel, PhD.

Signal Integrity Product Manager

Confidence by Design

Chicago, IL June 14, 2012

© 2011 ANSYS, Inc. June 18, 2012 2

Tablets are very entertaining, stylish and powerful

• Shopping, reading, emailing, accessing social network, playing games

• Schools, operating rooms, sports events

Tablets in our daily lives

Pictures source: www.istockphoto.com

© 2011 ANSYS, Inc. June 18, 2012 3

Problem Predict the performance of a tablet design while meeting strict electrical standards and design specifications

Solution Automated modeling and optimized analysis using ANSYS Electromagnetics tools allows for system simulation approach

Result Detailed and accurate system simulation approach enables tablets to be put on market on time with reduced testing costs

ANSYS for Tablet Designs


© 2011 ANSYS, Inc. June 18, 2012 4

3D CAD

Layout

Virtual Prototype

Vendor Specific Driver/Receiver Models

Vendor Specific VRM Models

Electronics

Virtual Compliance

Virtual System

Electromagnetic Extraction

Mechanical and Thermal

Virtual System Prototyping

© 2011 ANSYS, Inc. June 18, 2012 5

Designing the impossible

• Touchscreen

• Tablet Case

• Packages

• Flex circuitry

• Antenna

• ESD

• EMI

Tablets Design Challenges

© 2011 ANSYS, Inc. June 18, 2012 6


• Touchscreen

• Tablet Case

• Packages

• Flex circuitry

• Antenna

• ESD

• EMI


© 2011 ANSYS, Inc. June 18, 2012 7

No moving parts present

• Use a thin layer of ITO (indium tin oxide) to sense the presence of a finger by capacitive coupling.

• Capacitive sensors are mounted underneath of hardened glass

• Finger adds a measurable capacitive change in the touch sensor

• Change in sensor capacitance relies on RC time constant change

Capacitive Touchscreen

© 2011 ANSYS, Inc. June 18, 2012 8

Model size, complexity and ….

• Simulate “projected” and/or “mutual-capacitance”

• Include Skin and Proximity Effects

• Build detailed 3D model

Touchscreen Design Challenges

© 2011 ANSYS, Inc. June 18, 2012 9

Parameterized Example 10x10 electrodes model

Capacitive Touchscreen

© 2011 ANSYS, Inc. June 18, 2012 10

Adaptive Mesh Refinement

• Automatically tunes the mesh to the electrical performance of the device. This ensures simulations are correct the first time.

Mesh Convergence

• Real-Time update of performance per adaptive solution

Automatic and Robust Adaptive Meshing

Initial Mesh

Refined Mesh

© 2011 ANSYS, Inc. June 18, 2012 13

Focus on

• Area of contact

• Glass thickness

Finger Tip Effect

© 2011 ANSYS, Inc. June 18, 2012 14

Receiver Signal

Electrode scanning change at contacted ITO (Indium Tin Oxide) position

Non-contact

Proximity Effects (0.1mmGap)

Contact!

© 2011 ANSYS, Inc. June 18, 2012 15


• Touchscreen

• Tablet Case

• Packages

• Flex circuitry

• Antenna

• ESD

• EMI


© 2011 ANSYS, Inc. June 18, 2012 16

• Perform Drop test of Tablet PC from height of 4 feet onto a concrete floor at an angle of 45 degree using ANSYS Explicit Dynamics

• The geometry of the Table PC was created from scratch using ANSYS DesignModeler

• The parts are simplified representations of parts in an actual Tablet PC.

Tablet Computer Case

© 2011 ANSYS, Inc. June 18, 2012 17

• The geometry of the Tablet PC was created from scratch using ANSYS DesignModeler

Tablet Case Project Schematic

© 2011 ANSYS, Inc. June 18, 2012 18

• Meshing: – ANSYS Workbench meshing with Explicit

Dynamics preference is used to create a mesh. – Hex dominant mesh is created to reduce the

number of elements – Total number of elements ~25,000

• Analysis settings: – Analysis is solved for 4 e-4 seconds. – Initial velocity of 4.9 m/sec is assigned to the

Tablet – The concrete floor is modeled as a rigid shell

body with fixed constraints – Automatic contact definition is use between

all parts. – Parts that are in contact but may separate due

to the drop test are assigned bonded contacts. – Bonded contacts are modeled as breakable

based on stress criteria for debonding.

Drop test

© 2011 ANSYS, Inc. June 18, 2012 19

Equivalent Stress Contours Back Cover Off

Equivalent Stress Contours Front

Drop Test Simulation Results

© 2011 ANSYS, Inc. June 18, 2012 21


• Touchscreen

• Tablet Case

• Packages

• Flex circuitry

• Antenna

• ESD

• EMI


© 2011 ANSYS, Inc. June 18, 2012 22

CPU and Memory Applications

• Flip-chip BGA

• NAND Flash (BGA, FD-BGA SiP, PoP etc.)

Electrical and Thermal simulations

Tablet packages

Courtesy of EEMS

Courtesy of Amkor

© 2011 ANSYS, Inc. June 18, 2012 23

Design Challenges

• Accurate SYZ and RLGC solution

• Dealing with multiple vendors

Solution

• Automated merging capabilities

• Full-wave and Quasi-static solution

Tablet packages

Courtesy of EEMS

© 2011 ANSYS, Inc. June 18, 2012 24

Inside of Cadence SiP and APD and Allegro

• Setup of the HFSS ready to solve project in the Cadence environment

• Signal and pwr/gnd net selection

• Auto port creation on solderballs and bumps/bondwires

• Plane Extent and HFSS Solution Setup Options

HFSS in Cadence

HFSS Solution in progress

© 2011 ANSYS, Inc. June 18, 2012 25


• Touchscreen

• Tablet Case

• Packages

• Flex circuitry

• Antenna

• ESD

• EMI


© 2011 ANSYS, Inc. June 18, 2012 26

Parameterized Transmission line model

• Accurate Zo analysis

• Trace spacing and offsets

• Solid vs. patterned ground

FLEX circuit analysis

HFSS Transient

© 2011 ANSYS, Inc. June 18, 2012 27

Interconnect Transmission line model

• Trace Thickness and Width

• Trace to Ground Space

• Ground Shape (Solid vs. Meshed) – Reduce the Interference with High Speed signal Traces or noisy LCD surface

FLEX circuit analysis

© 2011 ANSYS, Inc. June 18, 2012 28

Flex Optimization analysis

• Impact of multiple variables on overall designs

• Goal driven optimization

Design of Experiments

Parametric HFSS Design

WB DX Setup

Response Surface - TDR

© 2011 ANSYS, Inc. June 18, 2012 29


• Touchscreen

• Tablet Case

• Packages

• Flex circuitry

• Antenna

• ESD

• EMI


© 2011 ANSYS, Inc. June 18, 2012 30

Antenna Design Challenges

• Location, Beam Forming

• Antenna type

• Human Body Effect – Hand, Body

• Operation Environments – Metal Desk

– Wooden Desk

Tablet Antenna

© 2011 ANSYS, Inc. June 18, 2012 31


• Location, Beam Forming

• Human Body Effect – Hand holding tablet at different locations

– Close to antenna and away from antenna

Tablet Antenna

Radiation Efficiency @2.4Ghz :0.967907 Radiation Efficiency @2.4Ghz : 0.480466

© 2011 ANSYS, Inc. June 18, 2012 32


• Operation Environments – Human Tissue

– Metal Desk

– Wooden Desk

Tablet Antenna

Human Tissue Metal Desk

Wooden Desk

Radiation Efficiency @2.4Ghz : 0.994337



© 2011 ANSYS, Inc. June 18, 2012 33


• Touchscreen

• Tablet Case

• Packages

• Flex circuitry

• Antenna

• ESD

• EMI


© 2011 ANSYS, Inc. June 18, 2012 34

Circuit and Numerical Modeling of ESD Coupling to Shielded Cables HFSS Transient solver for numerical Modeling ESD approach

0.00 5.00 10.00 15.00 20.00 25.00 30.00Time [ns]

-1.00

0.00

1.00

2.00

3.00

4.00

5.00

6.00

V(V

olt

ag

e1)

[kV

]

HFSSDesign1Input Voltage ANSOFT

Curve InfoV(Voltage1)

Setup1 : Transient

ESD Analysis

Courtesy of: HUWIN

© 2011 ANSYS, Inc. June 18, 2012 35

ESD Gun Simulation Results

: 6kV

: 5kV

: 4kV

: 2kV

Applied Voltage (kV)

Peak Current (A) IEC 61000-4-2 (ESD Test)

Peak Current (A) Simulation Results

2 7.5 7.75

4 15 15.5

5 18.75 19.3

6 22.5 23.25

Courtesy of: HUWIN

© 2011 ANSYS, Inc. June 18, 2012 36

ESD Gun Simulation Time length: 0 ns ~ 118 ns

ESD Gun and Metal Plate

ESD Animation

Courtesy of: HUWIN

© 2011 ANSYS, Inc. June 18, 2012 37

ESD gun applied on 1 driver and 1 receiver full length electrode

ESD Gun on Tablets touch electrodes

© 2011 ANSYS, Inc. June 18, 2012 38

ESD Gun Simulation Time length: 0 ns ~ 118 ns

ESD Gun effect on Tablets touch electrodes

© 2011 ANSYS, Inc. June 18, 2012 40


• Touchscreen

• Tablet Case

• Packages

• Flex circuitry

• Antenna

• ESD

• EMI


© 2011 ANSYS, Inc. June 18, 2012 41

EMI Design Challenges

• Entire PCB + Case

• Driver & Receiver

• Near field, Fairfield

• Immunity

Tablet EMI

: Digital source Termination

Slot

=

+

© 2011 ANSYS, Inc. June 18, 2012 42

EMI Design Results • Near Field and Far Field Spectrum

Tablet EMI

Simulation vs. Measurement

Simulation

Measurement

© 2011 ANSYS, Inc. June 18, 2012 43

Tablet Design Simulations were performed using

• Touchscreen – Q3D Extractor and DesignerSI

• Tablet Case – ANSYS Explicit Dynamic

• Packages – – Electrical: HFSS in Cadence, Q3D Extractor and TPA

– Thermal: ANSYS Icepak

• Flex circuitry – HFSS and Q3D Extractor

• Antenna - HFSS

• ESD - HFSS Transient and DesignerSI

• EMI – HFSS, DesignerSI

Tablets Design Solution

© 2011 ANSYS, Inc. June 18, 2012 44

Problem Meeting numerous tablet design options while meeting strict electrical standards and design specifications

Solution Automated modeling and optimized analysis using ANSYS Electromagnetics tools allows for system simulation approach

Result Detailed system simulation enabled tablets to be put on market on time with reduced testing costs

Conclusions


Documents

ANSYS for Tablet Computer Design · 2012. 10. 26. · Perform Drop test of Tablet PC from height of 4 feet onto a concrete floor at an angle of 45 degree using ANSYS Explicit Dynamics