IC Package Strip Stiffener for Thinner Substrate Rigidity
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Solution Overview
Problem
The existing flip-chip ball grid array (BGA) technology faces challenges in efficient underfilling due to the time-consuming process of dispensing encapsulant between the chip and substrate, and thinner substrates suffer from mechanical weakness and warping, limiting large-scale industrialization.
Innovation Solution
An integrated circuit package with an encapsulant retention structure and a stiffener layer that reduces the number of encapsulant applications and maintains mechanical properties, allowing for thinner substrates with improved thermal and mechanical performance, and a method for manufacturing compact strips or arrays with minimal waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the substrate thickness is reduced to achieve thinner substrates, then the ability to use smaller drill heads and reduce manufacturing time is improved, but the mechanical strength and stability of the substrate deteriorate
Solution Approach 1:
The patent applies composite materials by combining the substrate with a stiffener layer made of different material properties. The stiffener is attached to the substrate to create a composite structure that provides enhanced mechanical strength and rigidity while maintaining the thin profile of the original substrate, thus resolving the contradiction between thinness and strength
2Manufacturing precision
If the number of dispense passes is increased to ensure complete underfilling, then the filling completeness is improved, but the production time and cycle time increase
Solution Approach 1:
The patent applies preliminary action by pre-forming retention structures (such as dams or barriers) on the substrate before the underfilling process. These pre-formed structures guide and contain the encapsulant material, ensuring complete underfilling in a single or reduced number of dispense passes, thereby improving productivity without sacrificing filling completeness
3Speed
If a less viscous encapsulant is used to increase seep rate, then the underfilling speed is improved, but the encapsulant spreads in unwanted directions
Solution Approach 1:
The patent introduces retention structures (dams, barriers, or confined channels) as intermediary elements that act as physical guides for the encapsulant material. These intermediaries constrain the flow path of the less viscous encapsulant, allowing it to seep rapidly in the desired direction while preventing unwanted spreading, thus resolving the contradiction between speed and placement control
4Quantity of substance
If multiple sequential dispense passes are performed to fill the gap, then the underfilling completeness is improved, but the cycle time and manufacturing efficiency deteriorate
Solution Approach 1:
The patent applies preliminary action by pre-configuring retention structures and guide features on the substrate before encapsulant application. These pre-formed features ensure that a single dispense pass can achieve complete and uniform encapsulant distribution throughout the gap, eliminating the need for multiple sequential passes and thereby reducing cycle time while maintaining filling completeness
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
The solution significantly reduces the time needed for underfilling and enhances the mechanical stability of thinner substrates, enabling cost-effective large-scale industrialization of flip-chip BGA packages with reduced waste and improved thermal conduction.
Implementation Method 1
a stiffener layer that reduces the number of encapsulant applications and maintains mechanical properties, allowing for thinner substrates with improved thermal and mechanical performance
Implementation Method 2
Capillary action, in association with liquid viscosity, seeps the dispensed encapsulant inwards to open spaces
Implementation Method 3
These balls also provide better thermal conduction from the printed circuit board or substrate to the chip
Data Source
AI summary
An integrated circuit package strip employs a stiffener layer that houses a passive electronic component to maintain mechanical properties when a thinner substrate is used. The use of either a retention wall or a stiffener allows for the manufacture of these integrated circuit package using strip, matrix, or array technology where a larger board with a plurality of integrated circuit packages is produced industrially and then cut to individual units.