Lead Frame With Progressive Inner Lead Pitch And Shoulder Height

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Solution Overview

Problem

High-volume manufacturing of semiconductor devices faces challenges such as shorted, open, or cracked leads, which lead to manufacturing failures and increased costs due to the complexity of packaging and heat management in consumer electronics.

Innovation Solution

The integration of a lead frame with progressively increasing inner lead pitch and shoulder height, along with a radius between the inner and outer leads, to prevent short circuits, handling damage, and cracking, allowing for adhesive-free assembly and improved heat dissipation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the number of leads is increased to provide more external terminals, then the functionality of the semiconductor device is improved, but the complexity of the package structure increases and manufacturing defects such as shorted or cracked leads occur more frequently

Engineering Contradiction:

Improvenumber of external terminalsVSAvoidpackage structure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The lead frame is segmented into multiple leads with progressively increasing pitch values, dividing the terminal functions across spatially distributed segments. This segmentation allows high terminal count without requiring a uniformly complex structure throughout, as each lead segment can be independently optimized.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the lead frame are assigned different pitch values locally, with inner leads having smaller pitch and outer leads having larger pitch. This local quality variation optimizes the package structure for both high terminal density (in inner regions) and manufacturing reliability (in outer regions), resolving the contradiction between terminal count and structural complexity.

Inventive Principle:

Principle #3Local quality

2Adaptability or versatility

If the leads are made closer together to increase terminal density, then the number of external terminals increases, but the risk of shorted leads and manufacturing defects increases

Engineering Contradiction:

Improveterminal densityVSAvoidmanufacturing yield

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The pitch between leads is varied locally across different regions of the lead frame. Inner leads have smaller pitch to achieve high terminal density, while outer leads have progressively larger pitch to reduce the risk of shorted leads and manufacturing defects. This local differentiation resolves the contradiction between terminal density and manufacturing reliability.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The lead frame is divided into segments with different pitch characteristics, allowing high-density inner lead regions to be separated from lower-density outer lead regions. This segmentation enables each region to be optimized for its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

3Reliability

If adhesive is used to secure the semiconductor chip to the lead frame, then the chip mounting reliability is improved, but the manufacturing process complexity and cost increase

Engineering Contradiction:

Improvechip mounting reliabilityVSAvoidmanufacturing process simplicity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The lead frame structure itself provides the securing function through its geometric configuration and mechanical interlocking features, eliminating the need for separate adhesive materials. The progressive pitch design and lead geometry enable the structure to self-secure the chip during assembly, achieving both reliability and manufacturing simplicity.

Inventive Principle:

Principle #25Self-service

4Temperature

If heat spreader is added to improve heat radiation performance, then the heat dissipation capability is improved, but the device complexity and manufacturing cost increase

Engineering Contradiction:

Improveheat dissipation capabilityVSAvoidpackage component count

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The lead frame is designed to perform multiple functions simultaneously: it provides electrical connections, structural support, and heat dissipation pathways. The progressive pitch geometry and material properties enable the lead frame to conduct heat effectively without requiring a separate heat spreader component, thus achieving thermal management while maintaining device simplicity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS8110913B2Integrated circuit package system with integral inner lead and paddle

Publication Date: 2012.02.07 STATS CHIPPAC LTD

AI summary

An integrated circuit package system includes: fabricating a lead frame including: providing inner leads having an inner lead pitch of progressive length, forming a lead shoulder, on the inner leads, having a shoulder height of a progressive height, and forming outer leads coupled to the lead shoulder and the inner leads; mounting an integrated circuit die on the lead frame; and molding a package body on the lead frame and the integrated circuit die.