Leadframe Support Leads for IC Packaging Planarity Control

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Solution Overview

Problem

Conventional semiconductor packaging methods face challenges in reducing size and increasing density while minimizing manufacturing defects and costs, as the decreasing size and strength of components lead to increased defects and competitive pressures.

Innovation Solution

The method involves a leadframe with a partially removed portion, including a conductive pattern with a support lead for encapsulation, an integrated circuit die mounted above the pattern, and an encapsulation process that exposes the lower surface of the conductive pattern, forming a contact lead with a textured surface, which helps prevent overetching and maintain structural integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the size of semiconductor components is reduced and density is increased, then more functions and connections can be packed into smaller packages, but manufacturing defects increase

Engineering Contradiction:

Improvepackage sizeVSAvoidmanufacturing defect rate

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The leadframe is pre-formed with a partially removed portion and support leads before the encapsulation process. This preliminary structural preparation ensures that during high-pressure molding, the support leads maintain planarity and prevent warping, thereby reducing manufacturing defects even as package size decreases

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The support leads act as intermediary structural elements between the conductive pattern and the encapsulation mold. They transfer and distribute the molding pressure evenly, preventing localized stress concentrations that could cause defects in miniaturized packages

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If conventional molding under high pressure is used, then components can be packaged, but manufacturing defects increase due to decreasing component size and strength

Engineering Contradiction:

Improvepackaging processVSAvoidmanufacturing defect rate

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The support leads provide beforehand structural reinforcement to the leadframe in the partially removed portion. This cushioning effect prevents warping and deformation during the high-pressure molding process, protecting the fragile miniaturized components from damage

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Device complexity

If the leadframe is fully removed to form contact leads, then the packaging structure is simplified, but the structural integrity during encapsulation is compromised

Engineering Contradiction:

Improveleadframe structureVSAvoidstructural integrity during encapsulation

Core Design Contradiction:

Device complexityVSStrength

Solution Approach 1:

The leadframe is segmented into different functional portions: a partially removed portion that forms contact leads, and support leads that remain to provide structural integrity during encapsulation. This segmentation allows simultaneous achievement of simplified contact structure and maintained structural strength

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Only the necessary portions of the leadframe are removed to form contact leads, while the support leads are intentionally retained. This selective extraction removes excess material for simplification while preserving the structural elements needed for integrity during the encapsulation process

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS9293351B2Integrated circuit packaging system with planarity control and method of manufacture thereof

Publication Date: 2016.03.22 STATS CHIPPAC LTD

AI summary

A method of manufacture of an integrated circuit packaging system includes: providing a leadframe having a partially removed portion including: a conductive pattern having a lower surface on a top frame surface of the leadframe, a contact protrusion and a support lead on the lower surface of the conductive pattern, the support lead for supporting the partially removed portion of the leadframe during an encapsulation process, and a contact pad on a bottom surface of the contact protrusion; mounting an integrated circuit die above the conductive pattern; applying an encapsulation on the integrated circuit die and the conductive pattern, the lower surface of the conductive pattern exposed from the encapsulation; and removing at least a portion of the leadframe to form a contact lead and expose a bottom surface of the encapsulation.