burn-in & test socket workshop• caf is the acronym for conductive anodic filament. •...
TRANSCRIPT
Sponsored By The IEEE Computer SocietyTest Technology Technical Council
Burn-in & TestSocket Workshop
March 2 - 5, 2003Hilton Phoenix East / Mesa Hotel
Mesa, Arizona
tttc™
COPYRIGHT NOTICE• The papers in this publication comprise the proceedings of the 2003BiTS Workshop. They reflect the authors’ opinions and are reproduced aspresented , without change. Their inclusion in this publication does notconstitute an endorsement by the BiTS Workshop, the sponsors, or theInstitute of Electrical and Electronic Engineers, Inc.· There is NO copyright protection claimed by this publication. However,each presentation is the work of the authors and their respectivecompanies: as such, proper acknowledgement should be made to theappropriate source. Any questions regarding the use of any materialspresented should be directed to the author/s or their companies.
Burn-in & Test SocketWorkshop Technical Program
Session 3Tuesday 3/04/03 8:00AM
Socket And Board Development“CAF Effect: Challenges For Fine Pitch Burn-in Board Design”
K. W. Low - Intel CorporationAnthony Yeh Chiing Wong - Intel Corporation
Hon Lee Kon - Intel Corporation
“Automated Burn-in Socket Testing And Evaluation”Holger Hoppe - Infineon Technologies AG
“Thermal Testing Of Burn-In Sockets”James Forster - Texas Instruments
Savithri Subramanyam - Texas Instruments
CAF Effect:Challenges for Fine Pitch BIB Design
Anthony Wong Yeh ChiingKon Hon Lee
Low KWIntel Corporation
Anthony WongHL Kon/Low KW
BiTS 2003 2
Agenda• Overview• Background & Definition• CAF Formation• Factors Contributing to CAF• Fine Pitch BIB Design Rules• Best Known Test Methods & Issues.• Findings on PCB Materials Investigated• Technical Challenges.
Anthony WongHL Kon/Low KW
BiTS 2003 3
Overview• Most Wireless & Networking products have continuously
shrunk in size due to consumer need for smaller, lighter,powerful, and portable devices.
• Over the years, technology companies have migrated theproduct pin pitch from 1.27mm to 0.5mm and less.
• Due to the tight pitch, fine pitch PCBs are moresusceptible to CAF failure which will cause the board tofail electrically in the field after some time in use.
1.27mm pitch0.5mm pitch
Anthony WongHL Kon/Low KW
BiTS 2003 4
Background & Definition• CAF is the acronym for Conductive Anodic Filament.• Discovered by Bell Lab in 1976.• Further research has been performed by U of Maryland
(CALCE), Georgia Institute of Technology & SunMicrosystems.
• CAF is the growth of a copper-containing filament subsurfacealong the epoxy-glass interface,from anode to cathode.
Source:School of Materials Science & Engineering,GIT, Atlanta, GA
Anthony WongHL Kon/Low KW
BiTS 2003 5
CAF Formation• Glass/epoxy bonds degrade – due to mechanical stress,
poor quality coupling agent, etc.• In a humid environment, water absorption occurs and creates
an aqueous medium that provides an electrochemicalpathway that facilitates the transport of corrosion products.
• Water acts as the electrolyte, copper circuitry as anode &cathode and operating voltage as driving potential.
• H+ (pH lower) and OH- (pH higher) creates a pH gradient.• Copper is passivated in region of pH 7 to 11 but becomes
corrosive at pH below 7 and potentials greater than 0.2V.• The anodic copper ions travel along the epoxy/fiber interface
attracted to the cathode.
Anthony WongHL Kon/Low KW
BiTS 2003 6
Factors Contributing to CAF(1)• Material:• Several experiments have been done by PCB laminate
suppliers.• Most PCB Materials are only CAF Resistive
Anthony WongHL Kon/Low KW
BiTS 2003 7
• Conductor Configuration:
• Voltage Gradient Effects: 3-8V/mils• Solder Flux/HASL(Hot Air Solder Leveling) Fluid
Composition:• Testing shows that polyglycols diffuse into epoxy during
soldering and increases moisture absorption by thesubstrate.
• Thermal Excursions:• Temperature , amount of polyglycol absorption• Will weaken the bonding between epoxy and glass fibers
due to difference in Coefficient of Thermal Expansion.
Factors Contributing to CAF(2)
Most susceptible Least susceptibleSource:School of Materials Science & Engineering, GIT, Atlanta, GA
Anthony WongHL Kon/Low KW
BiTS 2003 8
• Cleaning:• Polyglycol residues from soldering process.• PCB Storage & Use: Ambient Humidity Effects.• Humidity threshold depends upon operating voltage and
temperature.• Moisture absorption can occur during any part of the PCB’s
lifetime.• PCB exposure to high humidity conditions during
transportation and storage can be problematic.
Factors Contributing to CAF(3)
Anthony WongHL Kon/Low KW
BiTS 2003 9
Fine Pitch BIB Design Rules
X
Y
Z-Via or Pin hole size
11.7819.70.50mm
13.7619.70.50mm
15.410.225.60.65mm
15.7515.7531.50.80mm
14.42539.41.00mm
1733501.27mm
9.7615.70.40mm
Y – edge to edgedistance (mils)
Z – Holesize (mils)
X-Pitch(mils)
Product PinPitch
Fine Pitch PCB design distances
Reduction inedge to edgedistance
• Y is a critical dimension; closer it is, more susceptible to CAF• Hole/Via determined by drill bit size and positional accuracy.
Anthony WongHL Kon/Low KW
BiTS 2003 10
Best Known Test Methods & Issues(1)• Two primary test methods for CAF testing:• Surface Insulation Resistance (SIR) Test method
introduced by Telcordia.– GR-78-CORE (IPC-TM-650, Section 2.6.14.1)– Test for surface electro migration and for characterizing
PCB laminates, soldering fluxes, solder masks &conformal coating.
– Test valid for a 25 year desired minimum product life.
Anthony WongHL Kon/Low KW
BiTS 2003 11
Best Known Test Methods & Issues(2)• CAF Test method
– Sun Microsystems’ CAF Pattern (IPC in review)– Use to evaluate Alternate materials, design and PCB
manufacturing processes.– Valid for a 20 year desired minimum product life.– Four test patterns available to cover the four critical
PCB designs.• In Line Test Pattern A
10.8 mils29.2 mils34 milsA1
20.0 mils20 mils30 milsA3
25.5 mils14.5 mils27 milsA4
15.0 mils25 mils32 milsA2
Via edge to edgedistance
Drill hole sizePad sizeTestPattern
Anthony WongHL Kon/Low KW
BiTS 2003 12
Best Known Test Methods & Issues(3)• Staggered Test Pattern B
10.4 mils32 mils37 milsB1
19.9 mils22.5 mils33 milsB3
24.4 mils18 mils30 milsB4
14.4 mils28 mils35 milsB2
Via edge to edgedistance
Drill hole sizePad sizeTestPattern
• Via to Plane Test Pattern C
• Trace to Trace Test Pattern D
5.25 mils14.5 mils25 milsC1
9.25 mils14.5 mils33 milsC3
11.75 mils14.5 mils38 milsC4
6.75 mils14.5 mils28 milsC2
Via edge to antipadedge
Drill hole sizePad sizeTestPattern
Anthony WongHL Kon/Low KW
BiTS 2003 13
Best Known Test Methods & Issues(4)• Sun Microsystems test pattern are used to test:
• Process• Drilled hole roughness• Hole clean process• Drilled hole to inner layer registration
• Material• Reinforcement type• Adhesion treatment used on electrical glass• Resin type• Copper tooth profile
• PCB design• Layer to layer dielectric thickness• Via edge to via edge spacing• Via location (In or out of line with the reinforcement weave direction)• Via edge to antipad clearance• Hole size and board thickness – drill wander
• Environmental• Temperature• Humidity• Voltage Bias
Anthony WongHL Kon/Low KW
BiTS 2003 14
Best Known Test Methods & Issues(5)
9.7 – 17 mils1-3 years40-85%65-125C
1.3-4.6V
Typical BIRequirements
10V & 100VPower
65%Humility
10.4 – 25.5 milsDesign –via edge to edge20 yearsProduct life
85CTemperature
Sun CAF testProduct Pin Pitch
• SIR test is only valid for surface test.• Sun’s CAF testing setup does not represent today’s fine
pitch Burn-in board environment.• Does not comprehend the current expectation of 1-3 years
usage.• Slightly variation in the PCB via edge to edge design.
Anthony WongHL Kon/Low KW
BiTS 2003 15
Findings on PCB Materials Investigated• Evaluation done on one material showed that no surfaceelectro migration occurred and it is CAF resistive.• Others investigated include non-woven Aramid enforcedmaterial.
Laminate VoidsLaminate Voids
Anthony WongHL Kon/Low KW
BiTS 2003 16
• CAF test standardization• An approved industry standard.• Better CAF test data interpretation method.• Must be able to validate CAF free for product lifetime
durations (1-3 years).• New CAF free PCB material• Need to develop a CAF free PCB material for the future.• Should not have any side effect such as high CTE or high
water absorption.• New Manufacturing process• Stability of process and consistent PCB yield.• CAF test data sharing and collaboration.• PCB material - BT Resin, Polyimide, FR4, Thermount etc.• Lack of conclusive data from Laminate suppliers.• Accredited forum for technical consultation.
Technical Challenges
BiTS Burn-in & Test Socket WorkshopMarch 2-5, 2003
Holger HoppePage 1 .
Automated Burn-in SocketAutomated Burn-in Socket
Testing and EvaluationTesting and Evaluation
Holger HoppeHolger Hoppe
Infineon Technologies AGInfineon Technologies AG
[email protected]@infineon.com
BiTS Burn-in & Test Socket WorkshopMarch 2-5, 2003
Holger HoppePage 2 .
A g e n d aA g e n d aRequirements for Burn-in sockets
Release of Burn-in sockets
Burn-in process simulation
Conclusions
BiTS Burn-in & Test Socket WorkshopMarch 2-5, 2003
Holger HoppePage 3 .
IntroductionIntroduction
Burn-in sockets: more complicated than obvious in order to havea stable and reliable burn-in process
Burn-in sockets in memory mass production: very cost intensive
Life time expectation: > 2 years respectively > 600 burn-in cycles
Burn-in cycle:
loading (opening socket, contacting, closing socket) temperature cycling (room temp high temp room temp) unloading (opening, unloading, closing).
Better to know burn-in socket performance before big volumeBetter to know burn-in socket performance before big volumeorders than after 1 year production experience.orders than after 1 year production experience.
BiTS Burn-in & Test Socket WorkshopMarch 2-5, 2003
Holger HoppePage 4 .
Requirements for burn-in socketsRequirements for burn-in sockets
Electrical demandGood (low and stable resistance) and reliable contact of theDUT (device under test) to the test and burn-in equipmentfor proper electrical function and ageing process in the burn-in systems
Mechanical demandStability (springs, contact force) for long term use
Good device guidance during load (drop off) for massproduction
BiTS Burn-in & Test Socket WorkshopMarch 2-5, 2003
Holger HoppePage 5 .
ObjectiveEvaluate electrical and mechanical performance of new burn-insockets in the lab
Approaching real burn-in conditions: to simulate all processesdone with burn-in sockets in real production in short time
Thermal stress with electrical function: Burn-in simulation
Mechanical stress + tests : Loader/Unloader simulation
Also possible: Ageing evaluation of used burn-in sockets aftera few hundreds runs in production (in comparison with anunused socket of same type)
Evaluation and release of burn-in socketsEvaluation and release of burn-in sockets
BiTS Burn-in & Test Socket WorkshopMarch 2-5, 2003
Holger HoppePage 6 .
General featuresFully automated system running LabView software(mechanical control, heating control, measurement control)
Loader / Unloader function with industrial robot
Heating / Cooling ramp freely programmable
Device exchange after each cycle, freely programmable
Simultaneously 4 (different) sockets testable
Engineering field for further investigations andLoader/Unloader simulation
Highly flexible system
Fully Automated Burn-In Socket Tester (FABIST) Fully Automated Burn-In Socket Tester (FABIST) II
BiTS Burn-in & Test Socket WorkshopMarch 2-5, 2003
Holger HoppePage 7 .
General features (cont.)
5 axis robot (Mitsubishi) for automatic cycles (load / unload/ open+close chamber / engineering), accuracy 0.02mm2 x 6 Jedec trays or waffle pack for >= 1200 device (300cycles)Universal presizerMax. socket size 50x50mmTemperature range: RT - 150°C (+/- 1°)Temperature ramp: >=10 K / min (up / down) freelyprogrammable = approx. 7 days for 300 cylcesNI - Industrial controller (PC-based)Keithley 22 bit Multimeter with 4 x 32 channels
Fully Automated Burn-In Socket Tester Fully Automated Burn-In Socket Tester IIII
BiTS Burn-in & Test Socket WorkshopMarch 2-5, 2003
Holger HoppePage 8 .
Fully Automated Burn-In Socket Tester Fully Automated Burn-In Socket Tester IIIIII
Overview I
5-axis-robot
BiTS Burn-in & Test Socket WorkshopMarch 2-5, 2003
Holger HoppePage 9 .
Fully Automated Burn-In Socket Tester Fully Automated Burn-In Socket Tester IVIV
Overview II
Temperature Chamber
BiTS Burn-in & Test Socket WorkshopMarch 2-5, 2003
Holger HoppePage 10 .
Minimum 300 Burn-in cycles (approx. 1 year use)
Load Device
Measure contact resistance [Rc]
Heat up to burn-in temperature
Measure Rc
Cool down
Measure Rc
Unload Device
Restart
Optical inspection of contact tips and solder balls
Burn-in Simulation Burn-in Simulation II
BiTS Burn-in & Test Socket WorkshopMarch 2-5, 2003
Holger HoppePage 11 .
Burn-in Simulation Burn-in Simulation IIII
Contact resistance: supplier “A”
Contact resistance: supplier “B”
BiTS Burn-in & Test Socket WorkshopMarch 2-5, 2003
Holger HoppePage 12 .
Burn-in Simulation Burn-in Simulation IIIIII
Contact resistance: supplier “C”
* Plating: Gold
* Contact shape: Sharp
Contact resistance: supplier “D”
* Plating: Gold
* Contact shape: Sharp
BiTS Burn-in & Test Socket WorkshopMarch 2-5, 2003
Holger HoppePage 13 .
Burn-in Simulation Burn-in Simulation IVIV
Contact resistance: supplier “F”
* Plating: Rhodium
* Contact shape: Standard
Contact resistance: supplier “E”
* Plating: NiB
* Contact shape: Sharp
BiTS Burn-in & Test Socket WorkshopMarch 2-5, 2003
Holger HoppePage 14 .
Mechanical Reliability10.000 cover actuation cycles
without device or with one device or with device exchange
with / without Rc measurement
Socket actuation force by way chartSocket actuation force by way chart
Loader/Unloader simulationdevice shift test: X-/ Y-directiondevice shift test: X-/ Y-direction maximum allowed shift
device rotation test maximum allowed angel
device drop height optimum
Loader/Unloader Simulation Loader/Unloader Simulation II
BiTS Burn-in & Test Socket WorkshopMarch 2-5, 2003
Holger HoppePage 15 .
Loader/Unloader Simulation Loader/Unloader Simulation IIII
Automated device X-/Y-shift test starting in the center of the socket @ (0;0)
short circuit device:
align in the presizer
load device with growing shift
measure RC of all 4 corner pins [Open/Close?]
unload and back to presizer
step-by-step shift to all 4 corners
resolution 0.05 mm; min +/-0.5mm = matrix 21 x 21
repetition with varying angles for device rotation test
BiTS Burn-in & Test Socket WorkshopMarch 2-5, 2003
Holger HoppePage 16 .
Loader/Unloader Simulation Loader/Unloader Simulation IIIIII
Spiral for X-/Y-Shift
Possible Results for X-/Y-Shift
BiTS Burn-in & Test Socket WorkshopMarch 2-5, 2003
Holger HoppePage 17 .
Loader/Unloader Simulation Loader/Unloader Simulation IVIV
Engineering field with
force sensor
Force sensor block above TSOP66
BiTS Burn-in & Test Socket WorkshopMarch 2-5, 2003
Holger HoppePage 18 .
Force by way chart: supplier 1
* stroke 2.1 mm
* actuation force max 13.9 N
Loader/Unloader Simulation Loader/Unloader Simulation VV
Force by way chart: supplier 2
* stroke 2.1 mm
* actuation force max 17.6 N
BiTS Burn-in & Test Socket WorkshopMarch 2-5, 2003
Holger HoppePage 19 .
Force by way chart: supplier 3
* stroke 2.1 mm
* actuation force max 15,5 N@ 2.1mm
Loader/Unloader Simulation Loader/Unloader Simulation VIVI
BiTS Burn-in & Test Socket WorkshopMarch 2-5, 2003
Holger HoppePage 20 .
Loader/Unloader Simulation Loader/Unloader Simulation VIIVII
Force by way chart: supplier 4
* stroke 3.5 mm
* actuation force max 19.6 N
Force by way chart: supplier 5* stroke 3.5 mm
* actuation force 19.6N / max 26.46N
BiTS Burn-in & Test Socket WorkshopMarch 2-5, 2003
Holger HoppePage 21 .
ConclusionsConclusions
Simulations approach certain burn-in process conditions
Fast way to evaluate and release burn-in sockets
Better results for socket life time estimation
Better purchasing decision and recommendation
Better burn-in socket development together with socket suppliers -
- fast customer feedback
Fast test of new contact types, plating etc.
Direct comparison of different sockets / mechanical principles /
contacts / platings etc.
BiTS Burn-in & Test Socket WorkshopMarch 2-5, 2003
Holger HoppePage 22 .
Investigation of behavior of Green Packages (TSOP and FBGA) in
conventional burn-in sockets
Investigation of new plating types (anti-sticking)
Investigation of vibration stability of contacts
Installation of simple tester - equipment in order to apply real
memory devices
OutlookOutlook
Thank you !Thank you !
Thermal Testing of Burn-In Sockets
James ForsterSavithri Subramanyam
Texas Instruments,Sensors & Controls, Attleboro, MA
2003 Burn-in Test Socket Workshop - March 2-5, 2003Hilton Phoenix East/Mesa Hotel
Mesa, Arizona
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 2
Outline
• Brief introduction of the problem
• Definition of thermal resistance
• Theoretical and experimentaltechniques to evaluateperformance
• Examples of some experimentalresults
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 3
Thermal Difficulties
From paper by Mark Miller titled:Burn-in & Test System for Athlon Microprocessors : Hybrid Burn-in.BiTS Conference Session 5, 2001
Remember this image from 2001?
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 4
Computers and PowerNot a New problem
Jan 1946 - ENIAC18,000 electron tubes233 sq. metres140 kW30 Tons
Jan 2000 - Sony8.8 million transistors0.15 sq. metres40W7 lb.
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 5
The Problem
• As processor speed increases powerincreases
• Packages dissipate more power today – willdissipate more power tomorrow
• For burn-in socket suppliers - heatgenerated during burn-in of high powerpackages can lead to thermal runawaycausing damage the socket, the board andpotentially the oven or system
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 6
Some Types of Packages
Ceramic LGA with heat spreader
Ceramic LGA with heat spreader
Ceramic PGA with heat spreader
Ceramic LGA NO heat spreader
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 7
Types of Socket
Socket Type:• Open top• Clamshell
Board Mount:• Through hole• Compression
Mount
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 8
Types Of SocketOpen Top
No Integral Heat Sink With Integral Heat Sink
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 9
Types Of SocketClamshell With Integral Heat Sink
Clamshell for LGACompression Mount
Clamshell for PGAThru-hole
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 10
Thermal Difficulties
• Thermal runawayduring burn-in cancause catastrophicfailure.
• Defective sockets canbe difficult to remove.
• Reduced burn-incapacity.
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 11
Burn-in• Historically
Systems were “ovens” used to heat thedevices with appropriate controls and systemsfor generating test patterns
• Today SystemsOven is an environmental chamberHeat generated by device under testSystem controls temperature of individualdevices on a board to reduce temperaturevariability
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 12
Burn-inConventional System - Passive Thermal Control
• Indirect heating from air - socket is “Passive”• As air travels through the oven the “ambient”
temperature increases• Device in socket 1 experiences different burn-in
conditions than devices in sockets 2 or 3
90°c80°c 85°c
Socket 1 Socket 2 Socket 3
AIR FLOW
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 13
Burn-inNew System - Active Thermal Control
• Direct heating/cooling of each socket.• Each socket/device has individual
temperature monitoring and “Active ThermalControl” to maintain specific temperature.
• Cooling/heating of each socket controlled byindividual fans or heaters for each socket.
• Temperature uniformity +/- 5 deg.C
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 14
Burn-inActive Thermal Control - MCC
Cool Air Duct
Burn-in Board
Burn-in Socket
Fan
V(Socket tray)
V(Fan tray)
MCC HPB-3 System
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 15
Burn-in Active Thermal Control - Unisys System
Unisys STS 3000
Thermal Button whichinterfaces with the package
From: A Large Capacity and High-Performance Burn-Inand Test System for High-Power Dissipating ComponentsBy Dr. Jerry Tustaniwskyj et al, BiTS Workshop 2002
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 16
Heat Transfer MechanismsCeramic Lidded Package
ConductionThrough heat sink
ConductionThrough silicon
Interface material –conduction/convection
ConductionThrough lid CuW, Al,AlSiC or ?
InterfacePackage to heat sinkconduction/convection
ConvectionHeat sink to air
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 17
Thermal Issues - Analysis
Analytical/Computational CapabilitiesFEA – Finite Element AnalysisCFD – Computational Fluid Dynamics
ExperimentalWind TunnelThermal Imaging using infra-red Camera
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 18
Thermal Issues – Heat Transfer
Conduction –Through silicon to surface of package.Well understoodPhysical constant
Convection –From heat sink surface to air.Less understoodDependent on many variables.
Temperature.Surface finish.Local flow velocity
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 19
Thermal Issues – Heat Transfer
Interface ResistanceHeat transfer between mating surfaces.Least understood – most variable. - Chip to thermal interface material - Thermal interface material to heat spreader/lid - Package to heat sink - Heat sink to air
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 20
Thermal Resistance - θθθθjaThermal resistance is defined by θθθθja(Theta j-a). Where
θθθθja = Tjunction - Tambient
Power– T(Junction) - Temperature of the device,
measured by an “on-chip” sensor– T(Ambient) - Temperature of the ambient
air.– Power - Power the package is
dissipating.
T(Junction) Temp of Die
T(Ambient) Temp of air
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 21
Thermal Testing Standards - EIA /JEDEC
Test methods for determination of θθθθja and otherbasic thermal characteristics:
EIA/JEDEC: (Electronic Industries Association Joint Electron Device Engineering Council)
JESD51: Methodology for the Thermal Measurement of Component Packages (Single Semiconductor Device)
JESD51-4: Thermal Test Chip Guidelines (Wire-Bond-Type-Chip)JESD51-6: Integrated Circuit Thermal Test Method Environmental
Conditions – Forced Convention (Moving Air)JESD51-8: Integrated Circuit Thermal test method Environmental
Conditions – Junction-to-BoardSee: http://www.thermengr.com/tea041.html
http://www.jedec.org/
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 22
Thermal Testing Standards- SEMI
Test methods for determination of θθθθja and otherbasic thermal characteristics.
SEMI (Semiconductor Equipment and Materials International.):G-30-88: Test Method for Junction-to-Case Thermal Resistance
measurement for Ceramic packagesG32-094: Guideline for Unencapsulated Thermal Test Chip Design
G42-0996: Specification for Thermal Test Board Standardization for Junction-to-ambient thermal resistance of Semi-Conductor
PackageG38-0996: Test Method for Still- and Forced-Air Junction-to-ambient.
See: http://www.thermengr.com/tea041.htmlhttp://www.semi.org/PUBS/SEMIPUBS.NSF/92796f5466497e4
0882565f6000d07af?OpenView
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 23
Experimental Tools– Wind Tunnel
Provides a stable, controlled, repeatableenvironment for testing and comparison ofsockets and systems.• Includes flow straightener• Turbulence dampers• Hot wire anemometer• Flow control
0 to 2,000 Linear Feet per Minute (LFM)
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 24
Wind Tunnel
Working Section
Inlet
Thermal Imaging Camera
Airflow
Exit
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 25
Thermal Test ChipDescription
• A custom semiconductor chip.• Flexible solution which allows the thermal
characterization of semiconductor packages.• Usually a resistor network which acts as a
heater.• Diodes or transistors used as temperature
sensors.• Allows conventional processing of package
through all normal packing processes.
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 26
Thermal Test ChipSuppliers
Delphi:http://delphi.com/automotive/microelectronics/testdie/available/
Thermal Engineering Associates:http://www.thermengr.com/tea51.html
Micred Ltd:http://www.micred.com/index3.html
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 27
Thermal Test ChipCalibration
• Each temperature sensormust be calibrated.
• Simple procedure –Placed in oven at knowntemperatures - resistancemeasured at minimum of4 different temperatures.
• Relationship betweentemperature andresistance is linear.
• Equation developed foreach sensor.
T = 337.62 R - 248.27T - Temp R - ResistanceCorrelation Coeff R2 = 1
RTD(4) y = 338.05x - 249.09R2 = 1
0
20
40
60
80
100
120
0.75 0.8 0.85 0.9 0.95 1 1.05Resistance (k-ohm)
Tem
pera
ture
(C)
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 28
Thermal Test ChipPackaging
Ceramic LGA packageFlip chip bare die
Ceramic LGA packageCu/W lid/heat spreader
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 29
Thermal Test Chip
Size 22*22 mmDie composite of 34 individual
die5*5 Array of thermal die3 Die have smaller 4*4 arrayEach die has resistor and RTDIndividual die heater
resistance 130 ohms
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 30
Thermal Test Chip
• Initiated thermal testingusing 4 heaters(highlighted in red)
• Heaters wired in parallel• Resistance 33 ohms• Easily powered to 50
watts.Voltage - 40.62Current – 1.23 amps
1,3 3,3
1,1 3,1
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 31
Experimental Tools – Thermal Imaging
AdvantagesBest method for determining temperature fieldsNon contact, Non invasiveProvides pictorial representation of thermalinteraction of different parts of the socketFull field visibility – not temperature of adiscrete point
DifficultiesEmissivity of different surfaces and materials.
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 32
ExampleTemperature Distribution on Package
Objective: Evaluate temperature distributionin die due to use of 4 modulesCompare results for the lidded andlidless (bare die)
Method: Modify burn-in socket to providewindow to package.Paint socket and package with flatblack paint to eliminate emissivityproblems.
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 33
ResultsOriginal Socket for Ceramic LGA
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 34
ResultsSocket Modifications – Lidded Package
The central area of the heat sinkwas removed so that the lid of thepackage is visible.Note flat black paint on CuW lid
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 35
ResultsThermal Image Lidded Package - No Power
Heat loss by conductioninto socket and naturalconvection.No air flow over socket
No PowerNote uniformity of temperature
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 36
ResultsThermal Image - Lidded Package – 2.9 Watts
Image demonstratesuniform temperatureon lid
Temperature on Package Lid39.5 +/- 1°C
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 37
ResultsThermal Image - Lidless Package – No Power
Temperature on Lid+/- 0.6°C
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 38
ResultsThermal Image Lidless Package – 3.0 Watts
Slot in frame for heater
Holes for shoulder screw
Die Temperature42 +/- 2.0°C
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 39
RESULTSComparison of FEA versus Wind Tunnel Testing
FEA Prediction ½ model of heat sink on flip chip bare diePredicted θθθθja – 3.0 °C/watt Actual 3.2°C/watt
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 40
ResultsExperimental Thermal Image of Heat Sink
• Comparison of thermal images for:a) lidded and b) bare die package.
• Both images indicate that impinging air keeps “forward”heat sink cooler.
Air Flow
a) b)
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ExampleUse of Thermal Imaging to Resolve Problem
Wind tunnel test results on open top socketindicated θθθθja was higher than predicted.
Use of thermal imaging helpedprovide insight to solveproblem (see next slide)
–Poor contact between heatsink and package.–Mechanism not functioningproperly.
Thermal Testing of Burn-in Sockets – Forster et al. BiTS Workshop, Phoenix, Az March 2 - 5, 2003 42
ExampleUse of Thermal Imaging to Resolve Problem
After modificationθθθθja – 3.1 °C/watt
Poor contact between heat sink and packageInitial resultθθθθja – 4.4 °C/watt
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Conclusions/Summary
• Analytical tools such as FEA and simpleanalyses reduce socket design cycle timeand cost by allowing evaluation of differentconcepts before cutting metal.
• Experimental tools such as the wind tunneland infra-red thermography provide
• confirmation of basic assumptions.
• visual records of the actual testconditions and insight into the thermalpath and heat flow.
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AcknowledgementsWork presented here was the result of much
effort by many people.
The authors gratefully acknowledge thework by the following: …….
• Design Teams in USA, Japan and Korea.
• Manufacturing Teams in Japan, andKorea
• Technical Services and Thermal TestLab.