1. Power Temp Cycle Information
Trent Uehling
JUNE

2. Comparison of Hardware Solutions
Freescale
(CC4)
(CC5)
Rel Inc
(C20A)
MCC
(HPB5A)
Unisys
(ATS500)
DUT Voltage Control / Monitor
Yes
Multiple DUT / PS
DUT Thermal Control / Monitor
DUT Heat Dissipation
Up to 20+ Watts
Up to 40+ Watts
Up to 50 Watts
Up to 150 Watts
Up to 400 Watts
Primary Current Per BIB
160 Amps
5A or 10A)
240 Amps
15A or 30A)
960 Amps
80A)
800 Amps
100A)
2250 Amps
150A)
Devices Per BIB
16 or 32
8 or 16
Up to 24 15
Slots Per System 60 24 16 8
DUT Per System
Up to 1920
Up to 960
Up to 576
Up to 384
120
System Heat Dissipation
18KW
20KW
25KW
48KW
Features
Individual control
BITT support
It Works!
Re-use of CC4 / C18HP
Higher power
Individual Control Higher power
Issues
Insufficient power
Not sufficient for CPD
Not yet designed
Batch PS’s
High capital $
Prototype
Long lead time
Best for short BI
Poor track record
Cost
Medium
High
High / Very High
Very High

3. Burn-in System Chamber Integrated Burn-in Environment
Rel Inc C18HP upgrade
High velocity airflow (>1000 lfpm)
High thermal capacity 90C)
60 slots per system / 1.75” pitch
Liquid cooling for better thermal control
Four power 20kW each
Integrated Burn-in Environment
Interface to driver
Oven control
Burn-in Board / Driver
High density interconnect (HDI)
Pwr / Gnd bars and power blocks
Burn-in Board
Driver
HDI
Bus Bar
Power Block
Backplane

4. Flip Chip Power Temp Cycle Model
quarter symmetry considered
Model considers center, edge and outermost corner C4 sphere
Die and underfill layer transparent
substrate model considers real routing design and metal coverage per layer
Quarter symmetry used
Substrate model reflects copper coverage per layer correctly

5. Simulated Scenarios
Scenario #
Loading Condition 1
Temperature Cycling °C to 150°C 2
Temperature Cycling °C to 125°C 3
Temperature Cycling °C to 125°C 4
Power Temp. Cycling 25°C to 85°C
Underfill Tg
Scenario 4 (considering 40°C temperature rise at junction during active phase)
For scenario 4, a thermal analysis was conducted prior to the thermo-mechanical analysis step in order to calculate the temperature field over time required as a load
The underfill material was considered using a visco-elastic material model
Solder alloy SAC305 considered , using a visco-plastic material model

6. Assumed Power Cycling
Transient thermal simulation was conducted first to extract temperature field over time required as the thermal load for the thermo-mechanical simulation.
Temperature contour for powered phase
Temperature contour for unpowered phase
The temperature gradient over the package that results from powering the die, is a significant thermo-mechanical load increase which adds to the load from the CTE mismatch in the package.

7. Volume Averaging Creep
Select volume with highest creep strain and volume average the accumulated creep strain of one temperature cycle.
Eqv. creep strain contour excample of outermost corner sphere after 2 cycles 85°C to 125°C
In order to compare the results, accumulated creep strain is averaged over full sphere volume as well as a small sphere segment that is impacted the most (thin segment at die side, usually the volume a fatigue crack would propagate through)

8. Max. Creep Strain over 1 Temperature Cycle
The highest max. equivalent creep strain for one temperature cycle is found for power cycling test, (ambient temperature cycles from 25°C to 85°C)
The results reveal that especially the junction temperature increases at high ambient temperature cause significant creep strain increase
This is explained by the underfill material property changes above Tg (around 115°C)

9. 45x45mm FC-PBGA Package Warpage - 3D Plots

10. 45x45mm FC-PBGA Package Warpage - Diagonal Plots