Solder Joint Die Attachment for IC Package Thermal Resistance
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Solution Overview
Problem
The semiconductor industry faces challenges in reducing die alignment issues, thermal resistance, and manufacturing costs in packaging integrated circuit dies, particularly in forming stacked semiconductor devices like 3DICs, where traditional methods are inefficient and costly.
Innovation Solution
The proposed solution involves a die attachment method that reduces overlay shifts and thermal resistance by using solder joints instead of adhesive films, and modifies seed layers for redistribution layers to reduce contact resistance, allowing for the formation of integrated circuit packages with through-molding vias directly on the underlying redistribution layer, thereby simplifying the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If adhesive films are used to attach dies to carriers, then the packaging process is simplified, but thermal resistance increases and die alignment precision deteriorates
Solution Approach 1:
The patent replaces the mechanical/adhesive bonding system with a solder-based electrical and mechanical bonding system. Solder joints provide both mechanical attachment and thermal conduction pathways, eliminating the thermal barrier introduced by adhesive films while maintaining ease of manufacture through standardized soldering processes.
Solution Approach 2:
The patent changes the bonding material from organic adhesive to metallic solder, fundamentally altering the thermal and electrical properties of the joint. This parameter change reduces thermal resistance by several orders of magnitude while maintaining acceptable manufacturing complexity through controlled solder reflow processes.
2Ease of manufacture
If traditional die attachment methods are used, then manufacturing costs are reduced, but die alignment precision and overlay accuracy worsen
Solution Approach 1:
The patent applies solder paste to the carrier substrate before die attachment, creating pre-formed solder joints that guide die placement. This preliminary action establishes precise alignment references that improve overlay accuracy while maintaining cost-effectiveness through a single-step reflow process.
Solution Approach 2:
The patent replaces mechanical alignment methods with a solder-based self-alignment system where solder paste patterns and reflow physics provide inherent alignment tolerance compensation, achieving high precision without complex mechanical alignment equipment.
3Device complexity
If adhesive films are used for die attachment, then the packaging process is simpler, but contact resistance increases
Solution Approach 1:
The patent replaces adhesive-based mechanical bonding with solder-based metallurgical bonding, creating direct metal-to-metal contact between die pads and carrier bond pads. This substitution eliminates the insulating adhesive layer and reduces contact resistance through intimate metallic contact and intermetallic compound formation.
Solution Approach 2:
The patent employs composite solder joint structures with multiple metallurgical layers including base metal, intermetallic compounds, and solder matrix, creating a composite material system that provides both low contact resistance and mechanical strength while maintaining process simplicity.
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 reduces thermal resistance, minimizes die alignment issues, and decreases manufacturing costs by simplifying the packaging process, while maintaining electrical connectivity and alignment through the use of solder joints and optimized seed layers.
Implementation Method 1
attaching the backside surface of the integrated circuit die to the bond pad using a solder joint
Implementation Method 2
reflowing the solder paste to form the solder joint
Data Source
AI summary
An integrated circuit package and a method of forming the same are provided. A method includes forming a first redistribution layer over a carrier, the first redistribution layer including a contact pad and a bond pad. A conductive pillar is formed over the contact pad. A backside surface of an integrated circuit die is attached to the bond pad using a solder joint. An encapsulant is formed along a sidewall of the conductive pillar and a sidewall of the integrated circuit die, a front-side surface of the integrated circuit die being substantially level with a topmost surface of the encapsulant and a topmost surface of the conductive pillar. A second redistribution layer is formed over the front-side surface of the integrated circuit die, the topmost surface of the encapsulant and the topmost surface of the conductive pillar.