Semiconductor Package Synthetic Models Provide:

Analysis of Thermal Transient Data www.analysistech.com 1

Semiconductor Package Synthetic Models Provide:

• Insight into the thermal performance of various package designs and improvements

“Why isn’t the performance of this new package much better than that of the old design?”

“Why has the change in die size had such a large effect on package ‘A’ and so little effect on package ‘B’?”



• The basis for intelligent selection of alternate package thermal enhancement approaches

“Would a heat spreader or heat sink provide greater package enhancement?”

“Would a different die attachment provide significant enhancement?”



• The basis for estimation of probable results for proposed enhanced package-designs

“What is the greatest improvement in thermal performance that can be expected from this new package enhancement?”



• Direct simulation of the thermal behavior of devices to non-steady or cyclic powering conditions

“What is the thermal impedance of this device for a 50 hertz power waveform?”

“What is the peak junction temperature expected during the high-power start-up and initializing cycle?”


Mock Empirical Data from Hypothetical Mechanical System


Selected Candidate Model for Mechanical System Example

Optimal Assignments Based on Response Data:

• MASS: 0.03 grams• SPRING: 10 dynes/cm• DAMPER: 0.02 dynes/cm/sec


Junction Temperature Step-ResponsePlotted Using Linear-Time Axis


Junction Temperature Step-ResponsePlotted Using Log-Time Axis


Candidate Thermal Model forSemiconductor Packages, Third Order


Model Step-Response Expressed asImpedance Versus Log-Time


Test Response of Plastic 24 Lead DIPwith Overlaid Synthesized Model


Test Response of Ceramic 24 LeadDIP with Overlaid Synthesized Model


Comparison of Plastic Packagevs. Ceramic Package


Assumed Segmentation Boundaries


Heat Capacity ComparisonEstimated Heat Capacities Relative to Synthetic Model Values


Test Response of 208 Lead Copper-SlugPackage with Overlaid Model

(good die attachment, second order model)


Conditions Indicative of Model Degeneration:

• The multiple between two time constants is less than 3 - 4• One constituent resistance or heat capacitance is

insignificantly small• One time constant is larger than the duration spanned by the

test data

Solutions for Model Degeneration

• Reduce the order of the candidate model (number of RC pairs)

• Expand the test duration



(failed die attachment, third order model)



(failed die attachment, second order model)


Comparison of Failed Die Attachto Good Die Attach


TO-247 Test Response, Junction-to-Case,Thermocouple Under Tab


Junction-to-Case Candidate Model


Model Response of Junction & ThermocoupleNodes, Junction-to-Case Model


TO-247 Test Response, Junction-to-Case,With Overlaid Synthetic Model

(thermocouple on center lead)


Junction-to-Case Synthetic ModelOverlaid on TO-247 Test Response Data

(thermocouple under tab)


TO-247 Test Response with Alternate Synthetic Model which Excludes the Bump Anomaly


Model Response for Square Waves of Various Periods and Duty Cycles


Test Response of Device #1 with Overlaid Model(3 Time Constants, Linear-Log Plot)


Test Response of Device #1 with Overlaid Model (3 Time Constants, Log-Log Plot)


Test Response of Device #1 with Overlaid Model(4 Time Constants, Linear-Log Plot)




Test Response of Device #2 with Overlaid Model (3 Time Constants, Linear-Log Plot)


Test Response of Device #2 with Overlaid Model (4 Time Constants, Linear-Log Plot)



Documents

Semiconductor Package Synthetic Models Provide: