Stackable Semiconductor Packages with Partially Exposed Connecting Elements
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Solution Overview
Problem
Conventional stackable semiconductor device packages face challenges such as large solder balls occupying valuable space, low stacking yields due to inadequate adherence, and susceptibility to bending or warping, which hinder the reduction of footprint area and increase in solder ball density.
Innovation Solution
The design includes a substrate unit with connecting elements and a package body that exposes these elements through openings, allowing for the use of smaller, fused conductive bumps to form stacking elements, which provide improved adherence and structural rigidity, reducing the distance between solder balls and increasing their number.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If large solder balls are used to connect stacked packages, then adequate adherence and structural strength are achieved, but valuable area on the substrate surface is occupied and the distance between solder balls cannot be reduced
Solution Approach 1:
The connection structure is segmented into multiple parts: smaller solder balls on the first substrate, fusible material in between, and connection to the second substrate. This segmentation allows each component to be optimized independently, enabling smaller overall footprint while maintaining adequate strength through the combined structure.
Solution Approach 2:
The patent uses composite connection structures combining solder balls with fusible material (such as eutectic glass-solder composites). This composite approach creates a multi-phase connection system that achieves both small footprint and adequate adherence strength by leveraging the complementary properties of different materials.
2Area of stationary object
If solder balls are placed close together to reduce footprint area, then space efficiency is improved, but manufacturing precision and stacking yields deteriorate due to inadequate adherence
Solution Approach 1:
The patent changes the physical and chemical parameters of the connection system by using fusible material with specific melting points and flow characteristics. This allows the connection structure to transition from a rigid single-phase system to a controllable multi-phase system, enabling precise control over adherence strength even at reduced spacing between connection elements.
3Area of stationary object
If the package body lateral extent is reduced to minimize footprint, then space efficiency is improved, but the assembly becomes prone to bending and warping
Solution Approach 1:
The patent addresses the rigidity issue by extending the package body laterally beyond the substrate edges, creating an overhanging structure. This dimensional extension provides additional structural support and rigidity in the horizontal plane without increasing the footprint area, as the extended portions hang over the edges rather than expanding the base footprint.
4Strength
If molding material is applied to form the package body, then protection and structural integrity are achieved, but the material may overflow and contaminate the peripheral portion of the substrate
Solution Approach 1:
The patent applies masking material to the peripheral portions of the substrate before the molding process. This preliminary protective action prevents molding material overflow from contaminating the substrate edges, allowing the molding material to be applied freely to achieve the desired package body structure without harmful side effects.
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 enhances the stacking yield, reduces the footprint area, and increases the density of semiconductor devices by ensuring better adherence and structural integrity, allowing for a higher number of smaller solder balls with improved electrical connections.
Implementation Method 1
solder balls, including solder balls 124a and 124b, which are initially part of the top package 102 and are reflowed during stacking operations to electrically connect the top package 102 to the bottom package 104
Data Source
AI summary
In one embodiment, a semiconductor device package includes: (1) a substrate unit; (2) connecting elements disposed adjacent to a periphery of the substrate unit and extending upwardly from an upper surface of the substrate unit; (3) a semiconductor device disposed adjacent to the upper surface of the substrate unit and electrically connected to the substrate unit; and (4) a package body disposed adjacent to the upper surface of the substrate unit and covering the semiconductor device. A lateral surface of the package body is substantially aligned with a lateral surface of the substrate unit. The package body defines openings that at least partially expose respective ones of the connecting elements. At least one of the connecting elements has a width WC, and at least one of the openings has a width WU adjacent to an upper surface of the package body, such that WU>WC.