Asymmetric Die Bonding for Thermal Expansion Alignment
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Solution Overview
Problem
Traditional integrated circuit package substrates (ICPSs) face challenges in achieving precise thermal compensation and alignment of connectors due to differing coefficients of thermal expansion between the die and substrate, leading to potential misalignment and increased strain on solder bumps during the thermocompression bonding process.
Innovation Solution
The ICPS system employs a method where the die is positioned asymmetrically with respect to the substrate center, and the connectors on the substrate are adjusted at an alignment temperature below the solder melting point to account for thermal expansion, ensuring accurate alignment and bonding at a temperature above the solder melting point through thermocompression bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the die is positioned symmetrically with respect to the substrate center, then the alignment process is simpler, but thermal expansion causes misalignment between connectors at bonding temperature
Solution Approach 1:
The patent applies asymmetry by positioning the die asymmetrically with respect to the substrate center and adjusting the connector array asymmetrically with respect to the die center. This asymmetric configuration is specifically designed to compensate for differential thermal expansion between the die and substrate, ensuring that connectors remain aligned at bonding temperature despite the temperature-induced expansion differences.
Solution Approach 2:
The patent implements preliminary action by adjusting the locations of connectors in the second array at the alignment temperature (below solder melting point) to pre-compensate for thermal expansion. This preliminary adjustment ensures that when the system reaches bonding temperature, the connectors are already positioned to account for the expected thermal expansion, preventing misalignment during the actual bonding process.
2Manufacturing precision
If connectors are aligned at bonding temperature, then alignment precision is achieved, but thermal expansion differences cause strain on solder bumps
Solution Approach 1:
The patent applies parameter changes by performing the connector alignment at a specific temperature parameter (alignment temperature below solder melting point) rather than at bonding temperature. This temperature parameter change allows for alignment without subjecting the solder bumps to the high temperatures and associated thermal stress that would occur if alignment were performed at bonding temperature.
Solution Approach 2:
The patent implements preliminary anti-action by adjusting connector locations at the lower alignment temperature to pre-compensate for thermal expansion effects. This preliminary adjustment counteracts the expected thermal expansion that would otherwise cause misalignment and strain on solder bumps during the high-temperature bonding process, thereby preventing the harmful effect before it occurs.
3Manufacturing precision
If the die is positioned asymmetrically on the substrate, then thermal expansion compensation is achieved, but the positioning process becomes more complex
Solution Approach 1:
The patent applies asymmetry in two dimensions: first, by positioning the die asymmetrically with respect to the substrate center, and second, by adjusting the connector array asymmetrically with respect to the die center. This dual asymmetric configuration is specifically designed to compensate for differential thermal expansion between the die and substrate, achieving precise thermal expansion compensation despite the increased positioning complexity.
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 alignment and bonding of connectors with fine pitch arrays, minimizing strain on solder bumps and enabling heterogeneous integration of multiple dies on a single substrate, enhancing high-performance computing capabilities.
Implementation Method 1
differing coefficients of thermal expansion between the die and substrate
Implementation Method 2
heating the first array of connectors to the bonding temperature, heating the second array of connectors to the bonding temperature
Implementation Method 3
bonding temperature that is above a solder melting temperature
Data Source
AI summary
An integrated circuit package substrate (ICPS) system includes a die including a first array of connectors and a substrate including a second array of connectors that is configured to be thermocompression bonded to the first array of connectors at a bonding temperature that is above a solder melting temperature. The first die is bonded to the substrate such that the first die is asymmetric with respect to a substrate center, and the second array of connectors is adjusted, at an alignment temperature that is below the solder melting temperature, for thermal expansion to the bonding temperature with respect to a reference point that is not a first die center.