Semiconductor Package Adhesion via Particle Matrix Crevices

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Solution Overview

Problem

The adhesion between epoxy mold compounds and conductive lead frames or laminate substrates in semiconductor packaging is inadequate, leading to reliability issues such as stress on semiconductor chips and potential moisture contamination.

Innovation Solution

A matrix of particles is added to the surface of the substrate, forming crevices or shapes that mechanically lock with the epoxy mold compound during the encapsulation process, enhancing adhesion between the epoxy mold compound and the substrate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional epoxy mold compounds are used without surface modification, then the manufacturing process is simple, but the adhesion between epoxy mold compound and substrate is inadequate

Engineering Contradiction:

Improveadhesion between epoxy mold compound and substrateVSAvoidsubstrate surface preparation complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The substrate surface is preliminarily prepared by depositing a particulate layer and forming crevices before the epoxy molding process. This preliminary action creates mechanical lock features in advance, allowing the epoxy to interlock with the substrate surface, thereby improving adhesion strength without requiring complex post-processing or specialized adhesion promoters during molding

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A particulate layer is deposited on the substrate surface to create a porous structure with crevices and voids. This porous morphology allows the epoxy mold compound to penetrate and interlock mechanically with the substrate, significantly enhancing the bonding interface between the epoxy and substrate without adding complex chemical adhesion systems

Inventive Principle:

Principle #31Porous materials

2Strength

If adhesion promoter additives are used in epoxy mold compounds, then adhesion may be improved, but the manufacturing cost and process complexity increase

Engineering Contradiction:

Improveadhesion between epoxy mold compound and substrateVSAvoidmolding process simplicity

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The invention replaces chemical adhesion mechanisms (adhesion promoters) with a mechanical interlocking system. By creating crevices and voids in the substrate surface through particulate deposition, the epoxy mechanically locks into the substrate structure, eliminating the need for complex adhesion promoter formulations and simplifying the molding process

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If the epoxy mold compound adhesion is poor, then manufacturing is simpler, but the long-term reliability and resistance to moisture ingress deteriorates

Engineering Contradiction:

Improvelong-term device reliabilityVSAvoidmoisture ingress and contaminant penetration

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The invention converts the potential harm of surface imperfections into a benefit by deliberately creating crevices and voids through particulate deposition. These surface irregularities, which might otherwise be considered defects, are transformed into mechanical lock features that enhance adhesion and block moisture ingress paths

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS7382059B2Semiconductor package structure and method of manufacture

Publication Date: 2008.06.03 SEMICON COMPONENTS IND LLC

AI summary

In one embodiment, a semiconductor package is formed by adding a layer of particles to desired portions of a packing substrate. The layer of particles forms a matrix of crevices that provides a micro-lock feature for mechanically locking or engaging encapsulating materials.