Fast Cure Non-Conductive Epoxy for Automated Substrate Attachment
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Solution Overview
Problem
Conductive epoxies require high temperatures for curing, which can damage temperature-sensitive electronic device components and result in prolonged curing times, making them unsuitable for high-speed automated processes.
Innovation Solution
A combination of fast cure non-conductive and slow cure conductive epoxies is used, where the fast cure epoxy provides mechanical attachment at temperatures below 100°C for less than 5 seconds, while the slow cure epoxy forms electrical interconnections over a longer period, allowing for attachment of temperature-sensitive components in automated processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high temperature curing is used for conductive epoxy, then electrical interconnection is achieved, but temperature-sensitive components are damaged
Solution Approach 1:
The patent divides the single epoxy material into two separate epoxy materials: a fast-curing non-conductive epoxy for mechanical attachment and a slow-curing conductive epoxy for electrical interconnection. This segmentation allows each epoxy to be optimized for its specific function, enabling the fast-curing epoxy to provide immediate structural support at lower temperatures while the slow-curing conductive epoxy gradually establishes electrical connections without requiring high temperatures that would damage sensitive components.
Solution Approach 2:
The patent changes the curing temperature parameter from traditional high temperature (above 100°C) to low temperature (below 100°C, preferably 20-80°C). This parameter change is made possible by using a fast-curing epoxy formulation that can achieve adequate cure at lower temperatures, thereby preventing thermal damage to temperature-sensitive electronic components while still achieving the desired mechanical and electrical properties.
2Object-affected harmful factors
If low temperature curing is used for conductive epoxy, then components are protected from thermal damage, but curing time increases excessively
Solution Approach 1:
The patent segments the curing process into two phases using two different epoxies: the fast-curing non-conductive epoxy provides rapid initial cure (within seconds to minutes) for immediate mechanical attachment, while the slow-curing conductive epoxy continues to cure over a longer period to establish electrical connections. This segmentation of the curing function eliminates the need for prolonged low-temperature curing of a single material, as the fast-curing component handles the time-critical mechanical bonding.
Solution Approach 2:
The fast-curing non-conductive epoxy performs the preliminary action of mechanical attachment and structural stabilization before the slow-curing conductive epoxy completes the electrical interconnection. This preliminary mechanical bonding provides immediate structural integrity and positions components correctly, allowing the conductive epoxy to cure slowly without causing production delays or component misalignment.
3Productivity
If fast cure non-conductive epoxy is used for mechanical attachment, then attachment speed increases, but electrical interconnection capability is lost
Solution Approach 1:
The patent segments the functional requirements into two separate epoxy materials: the fast-curing non-conductive epoxy is dedicated to mechanical attachment and structural bonding, while the slow-curing conductive epoxy is dedicated to electrical interconnection. This functional segmentation allows each material to be optimized for its specific purpose without compromise, enabling rapid mechanical assembly while ensuring reliable electrical connections through the specialized conductive epoxy.
Solution Approach 2:
The patent creates a multi-functional epoxy system where the combination of two epoxies provides both mechanical attachment and electrical interconnection capabilities. The fast-curing non-conductive epoxy handles the mechanical bonding function with high speed, while the slow-curing conductive epoxy handles the electrical connection function. Together, they provide universal functionality that neither epoxy could achieve alone, satisfying both productivity and electrical reliability requirements.
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 method enables rapid attachment of electronic substrates with reduced tact time, ensuring both mechanical and electrical integrity without damaging temperature-sensitive components, and allows for complete curing of conductive epoxy interconnections outside the assembly process.
Implementation Method 1
Heat curing epoxies consist of a pre-made mixture of two or more components that when heat is applied the components react and cross-link
Implementation Method 2
The slow cure electrically conductive epoxy continues to cure over a longer second period of time, such as a few hours to a day
Data Source
AI summary
Two substrates are mechanically and electrically coupled together using a combination of a fast cure electrically non-conductive epoxy for mechanical attachment and a slow cure electrically conductive epoxy for electrical interconnects. The two epoxies are selectively applied between the two substrates as a stack, and the stack is subjected to a temperature that is sufficient to cure the fast cure electrically non-conductive epoxy in a short period of time but does not damage the substrates or components coupled thereto. In some applications, the temperature is less than 100 degrees Celsius and the time period is less than 5 seconds. The stack is removed from the heat and the slow cure electrically conductive epoxy continues to cure over a longer second period of time, such as a few hours to a day.