IC Package Two-Step Molding for Bond Wire Defect Reduction

Solution Overview

Problem

Bond wire defects occur during the bending of leads in integrated circuit packages due to flexing, which can result in broken connections or wire breaks at the bond pads or die, and conventional methods like using tape to reduce flexing are not always effective due to design limitations.

Innovation Solution

A two-step molding process is employed where the bond wires, die, and bond pads are encapsulated with an encapsulant material to form a first mold cap before bending the leads, and then a second mold cap is formed over the first cap and inner leads to further encapsulate the bent portions, maintaining the vertical relationship between the bond pad and die pad and reducing flexing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If leads are bent to form gull wing leads or J leads, then ease of operation is improved, but bond wire defects increase due to flexing

Engineering Contradiction:

Improveease of handlingVSAvoidbond wire connection reliability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent applies preliminary action by performing the encapsulation of the die, bond wires, and bond pads with an encapsulant material before bending the leads. This sequence stabilizes the bond wires and connections in advance, preventing flexing-induced defects during the subsequent lead bending operation that forms gull wing leads or J leads.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If tape is used to reduce flexing during lead bending, then bond wire defects are reduced, but device complexity increases and effectiveness is limited by design constraints

Engineering Contradiction:

Improvebond wire connection reliabilityVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and removes the tape from the manufacturing process entirely. Instead of using tape to reduce flexing during lead bending, the invention uses a two-step molding process where encapsulation is performed first, eliminating the need for tape and its associated complexity and design constraints.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies preliminary action by performing the encapsulation of the die, bond wires, and bond pads with an encapsulant material before bending the leads. This sequence stabilizes the bond wires and connections in advance, preventing flexing-induced defects during the subsequent lead bending operation that forms gull wing leads or J leads.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If leads are bent before encapsulation, then manufacturing productivity is improved, but bond wire defects increase due to flexing during bending

Engineering Contradiction:

Improvemanufacturing efficiencyVSAvoidbond wire connection reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies preliminary action by performing the encapsulation of the die, bond wires, and bond pads with an encapsulant material before bending the leads. This sequence stabilizes the bond wires and connections in advance, preventing flexing-induced defects during the subsequent lead bending operation that forms gull wing leads or J leads.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS11784112B2Integrated circuit package and method to manufacture the integrated circuit package to reduce bond wire defects in the integrated circuit package

Publication Date: 2023.10.10 NXP USA INC

AI summary

An integrated circuit package is formed by positioning an integrated circuit die on a die pad of a leadframe; connecting a bond wire between the die and a bond pad of the leadframe; encapsulating the bond wire, die, and bond pad with an encapsulant material to form a first mold cap of the integrated circuit package; after the encapsulating, bending one or more leads of the leadframe to form one or more bent leads; and encapsulating the first mold cap and a portion of a bend of the one or more bent leads with the encapsulant material to form a second mold cap.