Three-Cavity Bar Molding System for IC Packaging

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Solution Overview

Problem

Conventional molding systems for integrated circuits risk damaging the back surface of integrated circuit dice due to pressure applied during encapsulation, especially when the back surface is uneven or not coplanar with the cavity bar, leading to potential damage and inadequate heat dissipation.

Innovation Solution

A three-cavity bar molding system with a tape positioned between the middle and bottom cavity bars to absorb pressure and prevent molding material from covering the back surface of the die, using flexible and elastic materials to form a protective seal around the die while allowing heat dissipation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional two-cavity bar molding system is used to encapsulate integrated circuit dice, then the molding process can be completed with a simple structure, but the back surface of the dice is at risk of pressure-induced damage and heat dissipation is inadequate

Engineering Contradiction:

Improveprotection of integrated circuit diceVSAvoidmolding system structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The molding system is divided into three separate cavity bars (top, middle, bottom) instead of using a conventional two-cavity bar system. This segmentation allows the middle cavity bar to apply pressure while the bottom cavity bar supports the dice with a gap in between, preventing direct pressure contact with the back surface of the dice and reducing the risk of damage.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A gap or spacer is introduced between the bottom cavity bar and the middle cavity bar to act as an intermediary element. This gap prevents direct transmission of pressure to the back surface of the dice while still allowing the molding material to encapsulate the dice effectively, thus protecting the dice from pressure-induced damage.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If pressure is applied directly to the back surface of integrated circuit dice during molding, then the encapsulation process is simplified, but the dice may suffer from damage and heat dissipation capability deteriorates

Engineering Contradiction:

Improveencapsulation processVSAvoidpressure-induced damage to dice

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The gap between the bottom cavity bar and middle cavity bar serves as a pre-established cushioning element. This gap is designed in advance to absorb and distribute the pressure during the molding process, preventing direct contact between the pressure source and the back surface of the dice, thus protecting them from damage before the harmful effect can occur.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Strength

If molding material completely covers the back surface of integrated circuit dice, then the protective housing is more complete, but heat dissipation from the dice is reduced

Engineering Contradiction:

Improveprotective housing integrityVSAvoidheat dissipation capability

Core Design Contradiction:

StrengthVSTemperature

Solution Approach 1:

The molding system is designed to provide different levels of encapsulation at different locations. The top and sides of the dice are fully encapsulated for protection, while the back surface remains partially exposed through the gap between cavity bars. This local differentiation maintains protective housing integrity where needed while preserving heat dissipation capability at the back surface.

Inventive Principle:

Principle #3Local quality

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

The solution effectively protects the integrated circuit dice from pressure-induced damage and ensures the back surface remains exposed for improved heat dissipation, while maintaining a protective housing around the die using the molding material.

Implementation Method 1

The tape is sandwiched between the middle cavity bar and a bottom cavity bar to help relieve pressure on the integrated circuit dice within the mold cavities

Methodology Applied

Scientific EffectPressure absorption: Absorption (physical)

Implementation Method 2

Molding material is injected into the one or more mold cavities to encapsulate the integrated circuits and portions of the electronic substrate

Methodology Applied

Scientific EffectInjection molding:

Implementation Method 3

The top cavity bar and the middle cavity bar are aligned over the electronic substrate to form one or more mold cavities around the dice

Methodology Applied

Scientific EffectMold cavity formation: Physical Containment

Data Source

PatentUS8105063B1Three piece mold cavity design for packaging integrated circuits

Publication Date: 2012.01.31 NAT SEMICON CORP

AI summary

One aspect of the present invention relates to a molding system for use in packaging integrated circuits. The molding system includes a top cavity bar, a middle cavity bar, a bottom cavity bar, a tape and an injection unit. When an electronic substrate is positioned between the top and middle cavity bars, the top and middle cavity bars are arranged to sandwich the electronic substrate. The top and middle cavity bars are also arranged to help form one or more mold cavities over device areas of the electronic substrate. The tape is positioned below the middle cavity bar and is arranged to cover and relieve pressure on a bottom of each mold cavity. The bottom cavity bar is positioned below the tape and is arranged to support the tape. The injection unit is arranged to inject a molding material into the mold cavities.