Dielectric Ridge Arcing for Compact Wirebonding

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Solution Overview

Problem

The challenge in chip-scale packaging of systems-in-package devices is the size reduction constraint, particularly in height and footprint, which poses challenges for wire bonding due to issues like wire sweep and bond wire-to-bond wire shorts during protective overmolding and processing.

Innovation Solution

The implementation of a dielectric ridge structure that allows bond wires to arc and pivot over the ridge, reducing the Z-profile and minimizing wire sweep, while using a capillary device to shape and heat the bond wires, ensuring they do not touch the active surface and thereby preventing shorts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional wire bonding is used in stacked-chip packaging, then electrical connections can be established, but the Z-height increases and wire sweep causes bond wire-to-bond wire shorts

Engineering Contradiction:

Improvebond wire short preventionVSAvoidZ-height

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

The bond wire is configured to arc over the dielectric ridge in the vertical dimension, transforming the wire path from a planar arc to a three-dimensional path that clears adjacent bonds. This dimensional change allows the wire to maintain electrical connection while preventing shorts and reducing overall Z-height

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

A dielectric ridge is introduced as an intermediary structure between the bond pad and the wire path. This ridge serves as a pivot point that the bond wire contacts and arcs over, mediating the wire's path to achieve both compact Z-height and short prevention without requiring complex wire routing

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If bond wires are positioned to avoid shorts, then reliability improves, but manufacturing precision requirements increase

Engineering Contradiction:

Improvebond wire positioning accuracyVSAvoidwire bonding precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The dielectric ridge structure enables self-aligning wire bonding where the wire naturally arcs over the ridge and positions itself correctly. The ridge acts as a physical guide that automatically ensures proper wire placement and clearance, reducing dependence on high-precision wire bonding equipment and operator skill

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 results in a lower Z-height package with reduced wire sweep and fewer bond wire-to-bond wire shorts, enabling more compact and reliable chip-scale packaging configurations.

Implementation Method 1

using a capillary device to shape and heat the bond wires

Methodology Applied

Scientific EffectFriction heating: Heating

Implementation Method 2

using a capillary device to shape and heat the bond wires

Methodology Applied

Scientific EffectElectrical resistance heating: Joule Heating

Data Source

PatentUS10847450B2Compact wirebonding in stacked-chip system in package, and methods of making same

Publication Date: 2020.11.24 SK HYNIX NAND PRODUCT SOLUTIONS CORP

AI summary

A bond-wire system including a wire bond that is deflected above a dielectric ridge at a die edge. The deflected wire bond allows for both a lowered Z-profile and a reduced X-Y footprint. The bond-wire system may include a stacked-die configuration where a stacked die is wire bonded and the stacked-die bond wire is deflected above a dielectric ridge at the stacked die edge.