Reinforced Tape Substrate for Low-Warpage Flip-Chip Packaging
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Solution Overview
Problem
The use of wirebond packages in semiconductor devices results in increased thickness and processing costs, and thin, flexible substrates are not suitable for flip-chip bonding due to deformation during mass reflow and the high cost of thermal compression bonding.
Innovation Solution
A reinforcement layer is formed over the tape substrate to increase stiffness, allowing for flip-chip ball grid array (FCBGA) bonding without specialized handling equipment, using a mass reflow process that maintains substrate integrity and reduces warpage, and pillars are used for additional electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wirebond packaging is used, then electrical connections can be established, but package thickness increases and processing costs increase
Solution Approach 1:
The patent removes the wirebonding step entirely by using flip-chip bonding where solder bumps directly connect the die to the substrate. This extraction of the intermediate wirebonding process eliminates the need for wirebond pads and reduces overall package thickness while maintaining electrical connection reliability.
Solution Approach 2:
Instead of bonding wires to the top surface of the die (wirebonding), the patent inverts the approach by bonding the die upside down with solder bumps on the bottom surface facing the substrate. This inversion enables direct electrical connection through solder bumps, reducing package thickness and eliminating wirebonding processing costs.
2Reliability
If wirebond packaging is used, then electrical connections can be established, but additional processing operations are required
Solution Approach 1:
The patent extracts and eliminates the wirebonding process step, removing the need for specialized wirebonding equipment and processing operations. The electrical connection is achieved directly through solder bumps in a flip-chip configuration, simplifying the manufacturing process.
Solution Approach 2:
The patent replaces the mechanical wirebonding process with a thermal-based solder reflow process. Instead of mechanically bonding wires, the solder bumps are melted and reflowed to create direct electrical connections, eliminating the need for wirebonding equipment and operations.
3Reliability
If flip-chip bonding is used on thin substrates with mass reflow, then bonding can be achieved, but substrate deformation occurs
Solution Approach 1:
The patent applies a reinforcement layer to the thin substrate before performing the mass reflow bonding process. This preliminary reinforcement prevents substrate deformation during heating by providing structural support, allowing the bonding to proceed without compromising substrate integrity.
Solution Approach 2:
The patent creates a composite structure by adding a reinforcement layer to the thin substrate. This composite construction combines the flexibility and thinness of the original substrate with the structural support of the reinforcement layer, enabling it to withstand the thermal stress of mass reflow without deforming.
4Stability of the object's composition
If thermal compression bonding is used instead of mass reflow, then substrate deformation is reduced, but processing cost increases
Solution Approach 1:
The patent applies a reinforcement layer before mass reflow bonding, which preliminary strengthens the substrate to prevent deformation. This allows the use of cost-effective mass reflow processing instead of expensive thermal compression bonding while maintaining substrate integrity.
Solution Approach 2:
The patent uses a relatively inexpensive reinforcement layer that can be added to enable mass reflow processing. This cheap reinforcement approach is more economical than using expensive thermal compression bonding equipment, achieving the same goal of preventing substrate deformation at lower cost.
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 solution enables flip-chip bonding on thin substrates with reduced warpage and processing costs, using standard equipment and maintaining the integrity of the substrate during reflow, while also providing increased stand-off height and decreased pitch between connections.
Implementation Method 1
A reinforcement layer is formed over the tape substrate to increase stiffness
Implementation Method 2
bonding the device die to the substrate by reflowing one or more solder bumps
Implementation Method 3
The reinforcement layer increases the stiffness of the substrate and reduces the warpage of the tape substrate that is caused by the reflowing process
Data Source
AI summary
Embodiments of the invention include device packages and methods of forming such packages. In an embodiment, the method of forming a device package may comprise forming a reinforcement layer over a substrate. One or more openings may be formed through the reinforcement layer. In an embodiment, a device die may be placed into one of the openings. The device die may be bonded to the substrate by reflowing one or more solder bumps positioned between the device die and the substrate. Embodiments of the invention may include a molded reinforcement layer. Alternative embodiments include a reinforcement layer that is adhered to the surface of the substrate with an adhesive layer.