Stack Package Supporter Geometry for Void-Free Encapsulant Filling
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Solution Overview
Problem
Existing stack package technologies face challenges in efficiently filling gaps between semiconductor dies and supporters with encapsulants, leading to voids and defects due to varying surface configurations and thermal expansion coefficient differences, which affect the stability and reliability of integrated circuits.
Innovation Solution
A stack package design featuring a supporter with a variably configured second side, including inclined and parallel sub-portions, that allows for smooth encapsulant flow and filling between the semiconductor die and the supporter, reducing voids and enhancing thermal stability by using a semiconductor die cut from a wafer with a similar thermal expansion coefficient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a flat supporter surface is used, then the manufacturing process is simple, but voids and defects occur in the encapsulant layer due to poor flow filling
Solution Approach 1:
The supporter's second side is designed with an inclined surface instead of a flat surface. This curved/angled configuration facilitates the flow of encapsulant material during the encapsulation process, enabling complete filling of gaps between the first semiconductor die and the supporter, thereby eliminating voids and defects while maintaining manufacturing feasibility
Solution Approach 2:
The inclination angle of the supporter's second side is optimized to balance two requirements: it must be sufficiently steep to promote encapsulant flow and prevent void formation, but not so steep as to cause encapsulant overflow. This parameter optimization resolves the contradiction between achieving high encapsulant layer quality and maintaining simple device structure
2Stability of the object's composition
If supporters with different thermal expansion coefficients are used, then stress relief is achieved, but thermal stability deteriorates
Solution Approach 1:
The supporter is designed with uniform material composition and homogeneous thermal expansion characteristics that match the semiconductor dies. This homogeneity ensures consistent thermal behavior across the entire stack package, maintaining thermal stability while the inclined surface design provides alternative stress relief through geometric configuration rather than material mismatch
3Manufacturing precision
If the encapsulant flows freely to fill gaps, then voids are prevented, but encapsulant overflow occurs
Solution Approach 1:
The inclination angle of the supporter's second side is precisely optimized to control encapsulant flow. The angle is sufficiently steep to promote complete filling and prevent void formation, but controlled to be within a range that prevents overflow. This parameter optimization resolves the contradiction between achieving complete gap filling and preventing harmful encapsulant overflow
Data Source
AI summary
A stack package is disclosed. A first semiconductor die and a supporter are disposed on a package substrate. The supporter may include a second side facing a first side of the first semiconductor die having a substantially inclined surface. A second semiconductor die is stacked on the first semiconductor die and on the supporter. An encapsulant layer is formed to fill a portion between the supporter and the first semiconductor die.