Shaped Lead Retention Structure for High Density IC Packaging

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Solution Overview

Problem

Current integrated circuit packaging technologies face challenges in scalability, lead density, structural integrity, and cost reduction while maintaining reliability and defect reduction, especially in compact electronic devices.

Innovation Solution

The method involves forming package leads with a retention structure featuring concave surfaces and ridges, a die attach paddle with similar retention structures, attaching an integrated circuit die, connecting conductive connectors, and applying encapsulation that conforms to these structures while exposing a portion of the package lead, enhancing structural integrity and lead retention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If conventional leadframe packaging is used, then manufacturing process is simple, but lead density is low and package footprint is large

Engineering Contradiction:

Improvelead densityVSAvoidpackage footprint

Core Design Contradiction:

Quantity of substanceVSArea of stationary object

Solution Approach 1:

The leadframe is segmented into individual leads with retention structures rather than a continuous stamped structure. Each lead is independently formed with concave surfaces and ridges, allowing higher density packing while maintaining manufacturing simplicity through automated assembly processes

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The retention structure adds vertical dimension features (concave surfaces and ridges) to the leadframe leads, enabling increased lead density without proportionally increasing package footprint. The three-dimensional retention features allow leads to be packed more closely while maintaining structural integrity

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Quantity of substance

If lead density is increased, then package footprint is reduced, but manufacturing scalability is limited

Engineering Contradiction:

Improvelead densityVSAvoidmanufacturing scalability

Core Design Contradiction:

Quantity of substanceVSProductivity

Solution Approach 1:

Retention structures are pre-formed on leads during leadframe manufacturing, enabling automated die attachment processes. The pre-configured concave surfaces and ridges allow for high-speed automated assembly, maintaining manufacturing scalability while achieving high lead density

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The retention structures are self-forming during the leadframe manufacturing process, eliminating the need for additional complex assembly steps. The leads inherently possess the retention features needed for die attachment, simplifying the overall manufacturing process while enabling high density

Inventive Principle:

Principle #25Self-service

3Area of stationary object

If package size is reduced, then footprint area is minimized, but structural integrity may be compromised

Engineering Contradiction:

Improvepackage sizeVSAvoidstructural integrity

Core Design Contradiction:

Area of stationary objectVSStrength

Solution Approach 1:

Retention structures are applied locally at critical interfaces between leads and die, rather than requiring overall package size increase. The concave surfaces and ridges are concentrated where mechanical strength is needed, providing local reinforcement without increasing overall package dimensions

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The retention structure combines multiple material properties in the leadframe leads, utilizing metallurgical bonding and mechanical interlocking features. The composite structure of metal leads with formed retention features provides high strength-to-size ratio, maintaining structural integrity in compact packages

Inventive Principle:

Principle #40Composite materials

4Reliability

If conventional packaging is used, then manufacturing cost is lower, but reliability and defect reduction are insufficient

Engineering Contradiction:

Improvepackage reliabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The retention structures are extracted as distinct geometric features (concave surfaces and ridges) from the leadframe manufacturing process. This extraction allows for improved reliability through better die attachment while using standard metallurgical processes, minimizing additional manufacturing costs

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The retention structures modify geometric parameters of the leads (concave depth, ridge height, surface area) to optimize both reliability and manufacturability. These parameter changes are achieved through controlled forming processes that balance performance improvement with manufacturing cost

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS8502357B2Integrated circuit packaging system with shaped lead and method of manufacture thereof

Publication Date: 2013.08.06 STATS CHIPPAC LTD

AI summary

A method of manufacture of an integrated circuit packaging system includes: forming a package lead having a retention structure around a perimeter of the package lead with a first concave surface, a ridge, and a second concave surface; forming a die attach paddle adjacent the package lead and having an another retention structure around a perimeter of the die attach paddle with an another first concave surface, an another ridge, and an another second concave surface; attaching an integrated circuit die to the die attach paddle; connecting a conductive connector to the integrated circuit die and the package lead; and applying an encapsulation over the integrated circuit die, the encapsulation conformed to the retention structure and exposing a portion of the package lead.