Segmented Circuit Layer Substrate for Semiconductor Package Reliability

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current pre-mold lead frame substrates in semiconductor packages are prone to delamination and oxidation due to mismatched thermal expansion coefficients, leading to reliability issues.

Innovation Solution

A substrate structure featuring a circuit layer with a dielectric structure that separates and connects sections, and a protection layer to prevent oxidation, is designed. The dielectric structure covers part of the circuit layer's bottom surface and exposes other parts, while the protection layer covers the circuit layer to prevent oxidation and intermetallic compound formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional substrate structure with continuous pad and dielectric layer is used, then the structure is simple to manufacture, but thermal expansion mismatch causes cracks and delamination at interfaces

Engineering Contradiction:

Improveinterface reliabilityVSAvoidsubstrate structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The continuous pad is divided into multiple separated pads, and the dielectric layer is segmented into multiple sections. This segmentation reduces the continuous stress path that causes delamination, allowing each segment to independently accommodate thermal expansion differences without propagating cracks across the entire interface.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the substrate are given different properties: the pad regions are conductive and bonded to terminals, while the dielectric sections provide insulation and stress relief. The interface between pad and dielectric is locally optimized with proper adhesion layers and geometry to prevent crack initiation at this critical junction.

Inventive Principle:

Principle #3Local quality

2Reliability

If the pad is exposed at corners to enable terminal connection, then electrical connection is achieved, but oxidation occurs at exposed surfaces

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidoxidation at pad corners

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A protective coating is applied to the pad corners before final assembly, creating a barrier against oxidation in advance. This preliminary protection ensures that even though the pad corners are exposed for electrical connection, they remain protected from environmental degradation throughout the product lifecycle.

Inventive Principle:

Principle #10Preliminary action

3Object-affected harmful factors

If a protection layer is added to cover the circuit layer, then oxidation is prevented, but manufacturing process complexity increases

Engineering Contradiction:

Improveoxidation preventionVSAvoidmanufacturing process simplicity

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The protection layer functionality is merged with existing structural elements. The dielectric sections themselves serve as protective elements, and the same manufacturing steps that create the segmented structure also provide oxidation protection, eliminating the need for separate protection layers and simplifying the overall process.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS11631633B2Substrate structure, semiconductor package structure and method for manufacturing semiconductor package structure

Publication Date: 2023.04.18 ADVANCED SEMICON ENG INC

AI summary

A substrate structure and a semiconductor package structure including the same are provided. The substrate structure includes a circuit layer and a dielectric structure. The circuit layer has a bottom surface and a top surface opposite to the bottom surface. The dielectric structure around the circuit layer. The dielectric structure covers a first part of the bottom surface of the circuit layer, and exposes a second part of the bottom surface and the top surface of the circuit layer. The dielectric structure exposes the top surface of the circuit layer. In addition, a method of manufacturing a semiconductor package structure is also provided.