IC Package Recess Prevents Mold Bleed

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Solution Overview

Problem

Integrated circuit package systems face mold bleed issues due to the lifting of the die paddle during encapsulation, which is not effectively addressed by existing technologies, leading to defects and increased costs.

Innovation Solution

The integration of a recess in the support structure's top edge, surrounded by a lead-finger system, which redirects mold flow stresses downward, preventing the lifting of the support structure and enhancing the interlocking of the encapsulation material with the electrical interconnect system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a leadframe with die paddle and terminal leads is used for integrated circuit packaging, then electrical interconnection is achieved, but mold bleed occurs at the periphery of the die paddle during encapsulation

Engineering Contradiction:

Improveencapsulation qualityVSAvoidmold bleed

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

A recess is formed around the periphery of the die paddle before encapsulation to pre-position the encapsulation material and prevent mold bleed during molding. This preliminary structural preparation ensures that the encapsulation material flows into the recess rather than bleeding outward at the die paddle periphery.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The recess acts as an intermediary structure between the die paddle and the encapsulation material, controlling the flow and positioning of the encapsulation material to prevent direct contact and potential bleeding at the sharp edges of the die paddle.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If chemical processes are used for mold flash removal, then some mold bleed can be addressed, but the process is not very effective

Engineering Contradiction:

Improvemold flash removalVSAvoidmold bleed prevention effectiveness

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

Instead of attempting to remove mold flash after encapsulation, the recess is formed beforehand to prevent mold bleed from occurring in the first place, making post-encapsulation removal unnecessary and improving overall manufacturing precision.

Inventive Principle:

Principle #10Preliminary action

3Ease of operation

If the die paddle periphery is exposed during encapsulation, then wire bonding can be performed, but the support structure lifts causing mold bleed

Engineering Contradiction:

Improvewire bonding accessVSAvoidsupport structure position

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

The recess is formed before encapsulation to pre-position the encapsulation material around the die paddle periphery, providing immediate support and preventing lift during the encapsulation process while still allowing wire bonding to be performed.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The encapsulation material that would otherwise cause lifting and mold bleed is redirected into the recess, converting a harmful force into a beneficial support mechanism that stabilizes the die paddle during encapsulation.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS8422243B2Integrated circuit package system employing a support structure with a recess

Publication Date: 2013.04.16 STATS CHIPPAC LTD

AI summary

An integrated circuit package system that includes: providing an electrical interconnect system including a support structure and a lead-finger system; processing a top edge of the support structure along an outermost periphery thereof, to include a recess for preventing mold bleed, the recess surrounded by the lead finger system; and encapsulating the recess and the electrical interconnect system with an encapsulation material to interlock the encapsulation material.