In-Cavity Epoxy Placement for Reliable Low-Loss Interconnects
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Solution Overview
Problem
Conventional capillary underfill processes used for solder joint reliability introduce insertion loss issues in high-speed interconnects, necessitating a solution that enhances solder joint reliability without compromising signal quality.
Innovation Solution
In-cavity epoxy placement is employed to selectively address areas of stress between solder contacts, using a thermal-cured epoxy that is screen printed or jetted into cavities and edges, forming a strong bond without the need for capillary underfill.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capillary underfill is used to improve solder joint reliability, then bond strength between die and substrate is improved, but signal quality deteriorates due to insertion loss
Solution Approach 1:
The patent applies local quality by placing epoxy material only in specific locations where stress concentration occurs, rather than using capillary underfill that contacts all solder contacts. The epoxy is positioned in regions of high mechanical stress to provide localized reinforcement without interfering with high-speed signal paths, thus maintaining signal quality while improving solder joint reliability.
2Reliability
If capillary underfill is used to strengthen the bond between die and substrate, then reliability is improved, but processing time increases due to curing requirements
Solution Approach 1:
The patent applies preliminary action by pre-positioning epoxy material in strategic locations before die attachment, rather than relying on post-attachment capillary underfill curing. The epoxy is placed in cavities or recesses formed in the substrate before the die is mounted, allowing the material to be in place before the bonding process begins, thereby reducing overall processing time while maintaining bond strength.
3Strength
If capillary underfill is used to improve solder joint reliability, then mechanical strength is improved, but material volume and cost increase
Solution Approach 1:
The patent applies the extraction principle by removing the epoxy material from areas where it is not needed, specifically excluding high-speed signal areas. Instead of using capillary underfill that distributes epoxy across the entire interface, the invention extracts and places epoxy only in specific cavities or recesses where mechanical reinforcement is most beneficial, thereby reducing the total quantity of epoxy material required while maintaining solder joint strength.
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 improves solder joint reliability while minimizing insertion loss, enabling more complex and integrated devices with reduced material volume and cost, and faster processing times.
Implementation Method 1
The material flows into the void and cures to form a strong, flexible bond between the die and its substrate
Data Source
AI summary
An apparatus is provided which comprises: a device surface, wherein the device surface comprises an array of solder contacts, a substrate surface, wherein the substrate surface comprises an array of pads, the array of solder contacts coupled with the array of pads, and a formation of epoxy coupled with the device surface and the substrate surface, wherein the formation of epoxy is entirely within an area of the array of solder contacts. Other embodiments are also disclosed and claimed.