Micro-transfer Printed Interconnects Using Temperature-Cycled Resin
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Solution Overview
Problem
Existing methods for electrically interconnecting micro-transfer printed chiplets to destination substrates are costly and complex, requiring multiple manufacturing steps and facing challenges with topographical differences between chiplets and substrates, which complicates the formation of continuous conductors and increases the risk of damage during laser ablation and adhesive curing.
Innovation Solution
A printed electrical connection structure using a substrate with connection pads and micro-transfer printed components featuring connection posts, where a resin with a reflow temperature below the cure temperature is used to facilitate electrical contact and a solder with a melting temperature between the reflow and cure temperatures enhances the connection, allowing for mechanical pressure to wedge the connection posts into the pads and potentially using a heat treatment for welding, while also providing redundant connections for reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If laser ablation is used to form continuous conductors between chiplets and substrates, then electrical connections can be established, but the topographical differences between chiplets and substrates complicate the process and increase the risk of damage
Solution Approach 1:
The patent introduces an adhesive layer as an intermediary substance between the chiplet and substrate. This adhesive mediator fills the topographical gaps and enables continuous conductor formation without requiring complex laser ablation processes, thereby reducing process complexity while maintaining connection reliability
Solution Approach 2:
The patent replaces the mechanical laser ablation process with a chemical adhesive bonding process. Instead of using high-energy laser beams to create conductive paths through mechanical vaporization, the solution uses adhesive materials to chemically bond and electrically connect components, eliminating the complexity and damage risk associated with laser ablation
2Reliability
If multiple manufacturing steps are used for electrical interconnection, then connections can be formed, but manufacturing costs increase
Solution Approach 1:
The patent merges multiple manufacturing steps into a single adhesive bonding operation. Instead of performing separate steps for alignment, bonding, and conductor formation, the adhesive layer accomplishes all these functions simultaneously, reducing manufacturing complexity and cost while ensuring reliable electrical interconnections
Solution Approach 2:
The adhesive layer serves multiple functions simultaneously: it provides mechanical bonding between chiplet and substrate, fills topographical gaps, enables electrical conduction, and facilitates alignment. This multi-functionality eliminates the need for separate specialized steps for each function, thereby reducing manufacturing cost while maintaining connection reliability
3Reliability
If connection posts are pressed into pads using mechanical pressure, then electrical connections are formed, but the process may damage fragile components
Solution Approach 1:
The patent applies an adhesive layer beforehand to cushion and protect components during the connection process. This adhesive cushioning layer distributes mechanical pressure uniformly, preventing direct impact forces from damaging fragile chiplets or substrates while still enabling reliable electrical connections through the bonded interface
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 simplifies the electrical interconnection process, reduces manufacturing costs, and improves connection reliability by using a resin that flows at the reflow temperature to embed connection posts into pads, ensuring robust and efficient electrical connections between chiplets and substrates, with the ability to replace defective components without disrupting functional connections.
Implementation Method 1
the resin having a reflow temperature less than a cure temperature, wherein the resin repeatedly flows at the reflow temperature when temperature cycled between an operating temperature and the reflow temperature
Implementation Method 2
a solder with a melting temperature between the reflow and cure temperatures enhances the connection
Data Source
AI summary
A printed electrical connection structure includes a substrate having one or more electrical connection pads and a micro-transfer printed component having one or more connection posts. Each connection post is in electrical contact with a connection pad. A resin is disposed between and in contact with the substrate and the component. The resin has a reflow temperature less than a cure temperature. The resin repeatedly flows at the reflow temperature when temperature-cycled between an operating temperature and the reflow temperature but does not flow after the resin is exposed to a cure temperature. A solder can be disposed on the connection post or the connection pad. After printing and reflow, the component can be tested and, if the component fails, another component is micro-transfer printed to the substrate, the resin is reflowed again, the other component is tested and, if it passes the test, the resin is finally cured.