Reactive Conductive Adhesive Tape for PV Cell Fabrication
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Solution Overview
Problem
Conductive adhesives used in photovoltaic cells face challenges in maintaining electrical reliability under harsh conditions and high temperatures due to the viscous nature of conventional non-reactive pressure sensitive adhesives, which can lead to increased joint resistance and instability.
Innovation Solution
A reactive conductive adhesive tape with a curable pressure sensitive adhesive and conductive filler is developed, allowing for immediate room temperature bond formation and curing during photovoltaic cell fabrication, resulting in improved electrical reliability and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional non-reactive pressure sensitive adhesive is used in conductive tape, then immediate room temperature bonding is achieved, but electrical reliability deteriorates under high temperature and harsh conditions due to increased joint resistance
Solution Approach 1:
The patent applies parameter changes by transitioning the adhesive from a permanent non-reactive state to a reactive state that can be cured. The curable PSA changes its physical and chemical parameters through curing (thermal, UV, or other energy input), transforming from a soft viscous material to a crosslinked network structure. This parameter change enables the adhesive to maintain low joint resistance and high electrical reliability under high temperature and harsh conditions while still providing immediate room temperature bonding capability before curing.
Solution Approach 2:
The patent uses composite materials by combining curable PSA with conductive fillers (metal particles, carbon, or conductive polymers) to create a conductive adhesive composition. This composite structure allows the material to exhibit both adhesive properties from the PSA and electrical conductivity from the fillers, while the curing process creates a crosslinked network that stabilizes the composite structure under harsh conditions, preventing joint resistance increase.
2Reliability
If curable pressure sensitive adhesive is used to improve electrical reliability, then processing complexity increases due to additional curing steps
Solution Approach 1:
The patent merges the adhesive bonding function with the electrical conductivity function into a single integrated conductive adhesive tape. The curable PSA combined with conductive fillers creates a material that simultaneously provides adhesion and electrical connection, eliminating the need for separate adhesive and conductive material application steps. The curing process can be integrated into existing manufacturing workflows, reducing overall processing complexity despite the added curing requirement.
3Ease of manufacture
If conventional conductive PSA is used, then application simplicity is maintained, but mechanical strength decreases under thermal stress due to adhesive flow
Solution Approach 1:
The patent applies preliminary action by performing the curing process during or after the assembly process. The curable PSA is applied in its uncured state, allowing simple application like conventional PSAs, then cured subsequently to develop full mechanical strength. This preliminary curing action prevents adhesive flow and maintains joint integrity under thermal stress and mechanical loading, while preserving application simplicity.
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
The reactive conductive adhesive tape provides stable electrical performance and mechanical strength under thermal cycling and harsh conditions, reducing the risk of joint instability and extending the lifespan of photovoltaic cells.
Implementation Method 1
The adhesive layer includes a curable pressure sensitive adhesive and a conductive filler
Implementation Method 2
reactive adhesive layer... curable pressure sensitive adhesive
Implementation Method 3
conductive particles that either individually bridge the bondline or form a percolation network that bridges the bondline
Implementation Method 4
PSA resins are viscoelastic systems that exhibit a certain degree of molecular level flow/viscous character
Implementation Method 5
The adhesive layer is laminated on and in contact with the electrically conductive substrate
Data Source
AI summary
A reactive pressure sensitive adhesive composition is disclosed. A tape formed using the reactive pressure sensitive adhesive is also disclosed. In its cured state, the pressure sensitive adhesive shows superior mechanical and electrical properties compared to conventional, non-curable charge collection tapes. The tape has a cure profile pre-selected to correspond to that of a photovoltaic cell fabrication process, such that curing can take place during cell fabrication and may occur simultaneously with one or more other curing steps employed in cell fabrication.