Flip Chip Bonding via Super-Atmospheric Pressure
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Solution Overview
Problem
Current flip chip bonding methods face challenges in minimizing defects such as voids and fillets, which affect the density and thickness of semiconductor packages, and hinder high-speed assembly with minimal mounting area.
Innovation Solution
A flip chip bonding method involving a die with a substrate and an adhesive layer, where the adhesive layer is heated and subjected to air pressure greater than atmospheric pressure to remove voids and fillets, optimizing bonding by controlling temperature and pressure conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional flip chip bonding methods are used, then bonding speed and assembly efficiency are maintained, but defects such as voids and fillets occur in the adhesive layer
Solution Approach 1:
The patent changes the pressure parameter from atmospheric pressure to super-atmospheric pressure (e.g., 2-10 atm) during the bonding process. This parameter change forces air into the adhesive layer, eliminating voids and preventing fillet formation, thereby improving bonding quality without sacrificing assembly efficiency
Solution Approach 2:
The patent replaces the conventional vacuum-based void removal method with a pressure-based air injection method. Instead of using vacuum to pull air out, the system uses pressurized air to push air into the adhesive layer, which is more effective at eliminating voids and maintaining bonding speed
2Manufacturing precision
If the adhesive layer is heated to high temperature to melt and remove voids, then void defects are reduced, but the bonding process time increases and productivity decreases
Solution Approach 1:
The patent applies pressure to the adhesive layer before or during the heating process, pre-positioning air in the adhesive layer to prevent void formation. This preliminary action eliminates the need for extended high-temperature holding times, reducing the overall bonding process time while maintaining adhesive layer quality
Solution Approach 2:
The patent modifies the temperature parameter by using moderate heating temperatures combined with high pressure, rather than relying solely on high temperatures for extended periods. This parameter change reduces the thermal processing time required while achieving the same void elimination effect
3Area of stationary object
If the bonding area is minimized to reduce mounting area, then package density increases, but the risk of void formation and bonding defects increases
Solution Approach 1:
The patent uses pneumatic pressure (super-atmospheric air pressure) to actively manage the adhesive layer during bonding. This pneumatic approach ensures complete filling of small bonding areas, preventing void formation even when the bonding area is minimized, thereby maintaining bonding reliability in high-density packages
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 significantly reduces defects like voids and fillets, enhancing the density and capacity of semiconductor packages while enabling high-speed assembly with reduced thickness and mounting area.
Implementation Method 1
heating the second substrate to melt the adhesive layer
Implementation Method 2
providing the adhesive layer and the second substrate with air having pressure greater than atmospheric pressure
Data Source
AI summary
A flip chip bonding method includes obtaining a die including a first substrate and an adhesive layer on the first substrate; bonding the die to a second substrate different from the first substrate; and curing the adhesive layer. The curing the adhesive layer includes heating the second substrate to melt the adhesive layer, and providing the adhesive layer and the second substrate with air having pressure greater than atmospheric pressure.