Embedded Solder Ball Substrate Structure for Dense PCB Packaging

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Solution Overview

Problem

Current semiconductor packaging technologies face challenges in increasing packaging density due to the substantial volume occupied by solder balls, which also leads to warpage and stress issues during the packaging process.

Innovation Solution

A substrate structure is fabricated with a core substrate, conductive pads, and a metal layer on opposite surfaces, where solder balls are formed on the pads and encapsulated by a molding compound with discrete portions to manage stress and improve mechanical strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If solder balls are formed on the substrate structure to enable connection to PCB, then electrical connectivity is achieved, but packaging density decreases due to substantial volume occupation

Engineering Contradiction:

Improveelectrical connectivityVSAvoidpackaging volume

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

The solder balls are embedded within cavities formed in the molding compound, nesting the connection elements within the package structure rather than having them protrude externally. This reduces the overall package volume while maintaining electrical connectivity functionality

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent transitions from traditional surface-mounted solder balls to vertically embedded solder balls within the molding compound. This dimensional change allows connection elements to be integrated within the package thickness rather than occupying lateral space, improving packaging density

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If solder balls are formed on the substrate structure, then external connection is enabled, but warpage and stress issues occur during packaging

Engineering Contradiction:

Improveexternal connection capabilityVSAvoidstructural stability

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

Cavities are pre-formed in the molding compound at the locations where solder balls will be embedded. This preliminary structural preparation prevents stress concentration and warpage that would occur with traditional solder ball formation, as the cavities provide stress relief zones during the packaging process

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The molding compound is formulated as a composite material with embedded cavities, combining the structural support function with stress management. The composite structure of solid molding material with void spaces provides both mechanical strength and stress relief, preventing warpage while enabling external connections

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS12334361B2Substrate structure, and fabrication and packaging methods thereof

Publication Date: 2025.06.17 YANGTZE MEMORY TECH CO LTD

AI summary

A method for fabricating a substrate structure for packaging includes providing a core substrate, a plurality of conductive pads at a first surface of the core substrate, and a metal layer at a second surface of the core substrate opposite to the first surface; forming a conductive structure, for pasting the substrate structure onto an external component, on each of the plurality of conductive pads; forming a molding compound on the first surface of the core substrate and to encapsulate the conductive structure; and forming a plurality of packaging pads by patterning the metal layer at the second surface of the core substrate.