Die-Level Lid Stiffeners for Low-Warpage IC Packages
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Solution Overview
Problem
IC packages suffer from warpage due to mismatched thermal expansion coefficients between thin dies and substrates, leading to poor soldered joints, intermittent contacts, and yield losses during assembly, particularly in ultra-thin packages.
Innovation Solution
Incorporation of a lid-framed stiffener around individual dies, with sides attached to the substrate using an underfill material and curing process, eliminating the need for solder connections and adhesive steps, and reducing the keep-out zone for smaller package form factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional separate adhesive and solder connection steps are used, then mechanical attachment is achieved, but device complexity and assembly time increase
Solution Approach 1:
The patent combines the adhesive attachment step and solder connection step into a single concurrent operation. The underfill material is applied and cured while the die is attached to the substrate, eliminating the need for separate adhesive application, curing, and soldering steps. This merging of operations reduces assembly complexity and manufacturing time.
Solution Approach 2:
The underfill material serves multiple functions simultaneously: it acts as both the adhesive bonding agent that attaches the die to the substrate and as the medium that enables solder connection. This multi-functionality eliminates the need for separate adhesive and solder materials, simplifying the assembly process.
2Stability of the object's composition
If larger keep-out zones are used around dies, then warpage is reduced, but package area increases
Solution Approach 1:
The patent changes the material parameters of the underfill substance to achieve superior mechanical properties. By selecting an underfill material with appropriate modulus, thermal expansion coefficient, and bonding characteristics, the patent reduces warpage control to a minimum keep-out zone, thereby minimizing package area while maintaining stability.
Solution Approach 2:
The patent applies local quality enhancement by concentrating the warpage control function in the immediate vicinity of the die through the underfill material. The underfill provides localized mechanical support and thermal management exactly where needed at the die-substrate interface, eliminating the need for extended keep-out zones across the entire package.
3Reliability
If sequential adhesive and solder steps are used, then reliable bonding is achieved, but assembly throughput decreases
Solution Approach 1:
The patent implements continuous useful action by performing adhesive bonding and solder connection in a single uninterrupted process. The underfill material is applied, the die is attached, and soldering occurs concurrently without removing the assembly from the processing line. This continuous operation maintains bonding reliability while maximizing assembly throughput.
Solution Approach 2:
The underfill material is applied in advance before the die attachment and soldering operations. This preliminary action prepares the bonding interface and enables subsequent steps to proceed concurrently, improving throughput without compromising the reliability of the final bond.
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
Enhances package planarity, improves solder joint integrity, reduces assembly steps, and minimizes warpage-induced failures, enabling efficient handling and higher yield in manufacturing.
Implementation Method 1
an underfill material surrounds the interconnects and couples the two or more sides of the lid to the substrate
Data Source
AI summary
Disclosed herein are microelectronic assemblies, as well as related apparatuses and methods. In some embodiments, a microelectronic assembly may include a substrate; a lid surrounding an individual die, wherein the lid includes a planar portion and two or more sides extending from the planar portion, and wherein the individual die is electrically coupled to the substrate by interconnects; and a material surrounding the interconnects and coupling the two or more sides of the lid to the substrate.