Calibration Block for Warpage Test System Thermal Expansion Compensation

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Solution Overview

Problem

Existing warpage test systems for semiconductor packages are not accurately calibrated across a broad temperature range, leading to potential bond failures between packages due to unaccounted thermal expansion variations, which can result in manufacturing defects.

Innovation Solution

A calibration method and system using a calibration block with two bonded metal blocks of different coefficients of thermal expansion (CTE) to measure warpage over a temperature profile, recording deviations between measured and known thermal expansions to calibrate the warpage test system accurately.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If warpage test system is calibrated at room temperature with a calibration block, then calibration is simple and quick, but measurement accuracy deteriorates across broad temperature range

Engineering Contradiction:

Improvecalibration timeVSAvoidwarpage measurement accuracy

Core Design Contradiction:

Loss of timeVSMeasurement precision

Solution Approach 1:

The calibration block is pre-designed with multiple metal blocks having different known CTEs, and the system performs preliminary calibration measurements at various temperatures to establish a deviation database before actual warpage testing, enabling accurate compensation during production testing

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system changes the temperature parameter during calibration to measure warpage at multiple temperature points, and uses the known CTE values of different metal blocks to calculate and store deviation data that compensates for thermal expansion effects across the operating temperature range

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If room temperature calibration is used, then the calibration process is straightforward, but thermal expansion variations cause measurement errors at high temperatures

Engineering Contradiction:

Improvecalibration process simplicityVSAvoidwarpage measurement accuracy

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The calibration block serves as an intermediary reference object with known thermal expansion characteristics, allowing the system to indirectly measure and compensate for thermal expansion effects by comparing measured warpage against calculated expected warpage based on known CTE values

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The calibration block incorporates multiple metal blocks with different known coefficients of thermal expansion, enabling the system to characterize and compensate for thermal expansion effects by measuring how these known materials warp at different temperatures and using that data to correct measurements of actual semiconductor packages

Inventive Principle:

Principle #37Thermal expansion

3Measurement precision

If multi-temperature calibration is performed, then measurement accuracy across temperature range is improved, but calibration time and complexity increase

Engineering Contradiction:

Improvewarpage measurement accuracyVSAvoidcalibration time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The calibration block is segmented into multiple metal blocks with different known CTEs, allowing the system to efficiently characterize thermal expansion across multiple material types in a single calibration setup, reducing the number of separate calibration operations needed

Inventive Principle:

Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach allows for precise measurement and compensation of warpage across varying temperatures, reducing manufacturing defects and improving the reliability of semiconductor packages by accurately identifying and addressing thermal expansion-induced stress.

Implementation Method 1

providing a calibration block including a first metal block bonded to a second metal block, the first metal block including a CTE different than a CTE of the second metal block

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS9279673B2Semiconductor device and method of calibrating warpage testing system to accurately measure semiconductor package warpage

Publication Date: 2016.03.08 STATS CHIPPAC MANAGEMENT PTE LTD

AI summary

A warpage test system uses a calibration block to calibrate the warpage test system over a temperature profile. The calibration block includes a first metal block bonded to a second metal block. The first metal block includes a first metal and a second different metal. The first metal block includes a CTE different than a CTE of the second metal block. The calibration block is disposed in the warpage test system. A warpage of the calibration block is measured over a temperature profile ranging from 28° C. to 260° C. A deviation between the measured warpage of the calibration block and a known thermal expansion of the calibration block over the temperature profile is recorded. The warpage measurement in a semiconductor package is compensated by the deviation between the measured warpage of the calibration block and the known thermal expansion or warpage of the calibration block over the temperature profile.