IC Package with Non-Planar Leads and Segmented Encapsulation

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Solution Overview

Problem

Conventional integrated circuit packaging systems face challenges in miniaturization, reliability, and cost-effectiveness, particularly in portable devices, where they struggle to achieve improved yield, reliability, and reduced costs while maintaining performance.

Innovation Solution

The development of an integrated circuit packaging system involving a peripheral lead with a non-horizontal side exposed, an inner lead and paddle formed non-planarly, and an encapsulation that covers the integrated circuit while exposing the inner lead and paddle, enhancing thermal management and manufacturing efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If conventional molding techniques are used to encapsulate the entire package, then manufacturing simplicity is maintained, but thermal performance deteriorates due to resin insulation

Engineering Contradiction:

Improvethermal performanceVSAvoidmanufacturing simplicity

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The encapsulation is segmented into two distinct parts: a mold compound covering the IC die and a potting compound covering the leads. This segmentation allows each material to be optimized for its specific function - the mold compound provides structural support and partial protection, while the potting compound provides thermal management and lead protection, thereby improving thermal performance without significantly complicating the manufacturing process.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different materials with different properties are used in different regions of the package. The mold compound (first encapsulation material) is used where structural support and die protection are needed, while the potting compound (second encapsulation material) is used where thermal management and lead protection are prioritized. This local differentiation of material properties optimizes thermal performance while maintaining manufacturing feasibility.

Inventive Principle:

Principle #3Local quality

2Volume of moving object

If package size is reduced for miniaturization, then portability is improved, but reliability deteriorates due to increased stress on components

Engineering Contradiction:

Improvepackage sizeVSAvoidcomponent reliability

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The leads are provided with stress relief features (such as bends or loops) before final assembly, which allow the leads to absorb thermal expansion and mechanical stresses that occur during operation. This pre-built stress relief mechanism protects the solder joints and IC die from stress-induced failures, thereby maintaining reliability in the miniaturized package structure.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Temperature

If leads are made coplanar for simplified manufacturing, then manufacturing ease is improved, but thermal management deteriorates due to restricted air flow

Engineering Contradiction:

Improvethermal managementVSAvoidmanufacturing ease

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The leads are configured to extend in multiple dimensions rather than being strictly coplanar. Some leads extend beyond the plane of the IC die, creating a three-dimensional arrangement that allows air to flow between and around the leads. This dimensional variation improves convective heat dissipation while the leads remain relatively simple in structure, maintaining manufacturing ease.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

4Adaptability or versatility

If I/O density is increased for better performance, then functionality is improved, but manufacturing precision requirements worsen

Engineering Contradiction:

ImproveI/O densityVSAvoidlead alignment precision

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The leadframe structure incorporates self-aligning features such as recesses that receive the IC die and corresponding protrusions or contact pads that automatically position the leads during assembly. The mold compound is molded to precisely fit these features, creating a self-aligning assembly process that accommodates high I/O density without requiring extremely tight manufacturing tolerances, thereby maintaining manufacturing feasibility.

Inventive Principle:

Principle #25Self-service

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach improves thermal performance, simplifies manufacturing, increases yield, and reduces costs by allowing for smaller, more reliable packaging with enhanced air flow and higher I/O density, addressing the need for miniaturization and cost-effectiveness in the industry.

Implementation Method 1

improves thermal performance

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

enhanced air flow

Methodology Applied

Scientific EffectConvection: Convection

Data Source

PatentUS8482109B2Integrated circuit packaging system with dual connection and method of manufacture thereof

Publication Date: 2013.07.09 STATS CHIPPAC LTD

AI summary

A method of manufacture of an integrated circuit packaging system includes: forming a peripheral lead having a peripheral contact layer surrounding the peripheral lead with a non-horizontal side exposed from the peripheral contact layer; forming an inner lead and a paddle non-planar with the peripheral lead; mounting an integrated circuit to the paddle; and forming an encapsulation covering the integrated circuit and exposing the inner lead, the paddle, and the non-horizontal side.