Conductive Adhesive Solar Cell Assembly for Thermal Stress Relief
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Solution Overview
Problem
Current methods of manufacturing space-grade solar arrays face challenges in properly coupling solar cells to printed circuit boards from both thermal and electrical perspectives, leading to issues with thermal stresses and labor-intensive manual processes.
Innovation Solution
The use of an electrically conductive adhesive with a coefficient of thermal expansion (CTE) that acts as a thermal and mechanical buffer between solar cells and printed circuit boards, combined with integrated coverglass and automated pick and place technology, to securely and efficiently attach solar cells to the PCB, minimizing thermal stresses and reducing manual labor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If solder is used to attach solar cells to printed circuit boards, then strong mechanical bonding is achieved, but high thermal stresses are induced due to CTE mismatch and mechanical rigidity
Solution Approach 1:
The patent changes the material parameters of the adhesive, specifically selecting an adhesive with a CTE value intermediate between the solar cell and PCB, and with lower mechanical modulus than solder. This parameter optimization allows the adhesive to provide adequate bonding strength while reducing thermal stress induction through its compliant mechanical properties and thermal buffering capability.
Solution Approach 2:
The patent employs a composite material solution by using a specially formulated adhesive that combines electrical conductivity with optimized mechanical and thermal properties. This composite adhesive material integrates multiple functions: electrical connection, mechanical bonding, thermal stress buffering, and CTE mismatch compensation, replacing the traditional solder material.
2Manufacturing precision
If manual assembly processes are used for solar cell attachment, then precise placement is achieved, but manufacturing efficiency is reduced and labor costs increase
Solution Approach 1:
The patent replaces manual mechanical assembly operations with automated pick-and-place machinery. The adhesive formulation is optimized to work with automated dispensing and bonding processes, enabling precise solar cell placement through automated systems rather than manual operations, thereby increasing manufacturing efficiency while maintaining placement precision.
3Stress or pressure
If electrically conductive adhesive is used instead of solder, then thermal stress is reduced and manufacturing is simplified, but electrical conductivity may be compromised
Solution Approach 1:
The patent uses a composite adhesive material that integrates electrical conductivity with optimized mechanical and thermal properties. This composite adhesive material integrates multiple functions: electrical connection, mechanical bonding, thermal stress buffering, and CTE mismatch compensation, replacing the traditional solder material.
Solution Approach 2:
The patent optimizes the electrical conductivity parameter of the adhesive by selecting or formulating an adhesive with sufficient electrical conductivity for the application, balancing it with other critical parameters such as CTE, mechanical modulus, and bonding strength to achieve overall system reliability.
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 reduces thermal stresses, increases manufacturing efficiency, and eliminates the need for costly touch labor, resulting in a more reliable and cost-effective space-grade solar array with improved power density and reduced human error.
Implementation Method 1
an adhesive that is configured to conduct an electrical current
Implementation Method 2
the adhesive has a coefficient of thermal expansion (CTE) that acts as a thermal buffer... The adhesive acts to limit or eliminate thermal stresses induced into the solar cell as a result of the CTE difference between the solar cell and the printed circuit board
Data Source
AI summary
A space-grade solar array has a plurality of solar cells with an electrically conductive adhesive between a back side of each diced solar cell and a printed circuit board. A method of manufacturing such a space grade solar array includes dicing a multi-junction solar wafer having a plurality of solar cells to form a plurality of diced multi-junction solar cells, and positioning an electrically conductive adhesive between a back side of each diced solar cell and a printed circuit board; and adhesively securing the diced solar cells onto the printed circuit board via the adhesive.