Wiring Substrate Blind Hole Structure for Stronger Conductive Paste Bonding

Solution Overview

Problem

The existing methods for forming blind vias in wiring substrates do not effectively enhance the strength of the connection between the metal bottom surface and conductive paste, leading to potential electrical resistance and reliability issues.

Innovation Solution

A method involving laser processing to create blind holes with recesses and lateral walls on the metal bottom surface, allowing for improved bonding with conductive paste, which includes forming primary and secondary blind holes using different wavelengths of laser light to remove anti-rust layers and create recesses for enhanced adhesion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If laser processing is used to form blind holes in wiring substrates, then the holes can be formed efficiently, but the connection strength between the metal bottom surface and conductive paste is insufficient

Engineering Contradiction:

Improvehole formation efficiencyVSAvoidconnection strength between metal and conductive paste

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

The patent applies preliminary action by forming recesses on the metal bottom surface before filling with conductive paste. The laser processing creates predetermined凹陷 structures that prepare the surface for enhanced paste adhesion, ensuring better connection strength before the bonding step occurs.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies local quality by creating non-uniform surface structures (recesses) at specific locations on the metal bottom surface. These localized凹陷 features concentrate the bonding interface areas, providing enhanced adhesion precisely where the conductive paste contacts the metal surface, while maintaining smooth areas elsewhere.

Inventive Principle:

Principle #3Local quality

2Device complexity

If conventional laser processing is used to form blind holes, then the process is simple, but electrical resistance increases due to poor adhesion

Engineering Contradiction:

Improveprocess complexityVSAvoidelectrical connection reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent applies preliminary action by forming recesses on the metal bottom surface before filling with conductive paste. The laser processing creates predetermined凹陷 structures that prepare the surface for enhanced paste adhesion, ensuring better connection strength before the bonding step occurs.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies local quality by creating non-uniform surface structures (recesses) at specific locations on the metal bottom surface. These localized凹陷 features concentrate the bonding interface areas, providing enhanced adhesion precisely where the conductive paste contacts the metal surface, while maintaining smooth areas elsewhere.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If the metal bottom surface is left flat, then manufacturing is easier, but the adhesion and filling of conductive paste is insufficient

Engineering Contradiction:

Improvemanufacturing easeVSAvoidpaste filling quality

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by forming recesses on the metal bottom surface before filling with conductive paste. The laser processing creates predetermined凹陷 structures that prepare the surface for enhanced paste adhesion, ensuring better connection strength before the bonding step occurs.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies local quality by creating non-uniform surface structures (recesses) at specific locations on the metal bottom surface. These localized凹陷 features concentrate the bonding interface areas, providing enhanced adhesion precisely where the conductive paste contacts the metal surface, while maintaining smooth areas elsewhere.

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

This approach strengthens the connection between the metal and conductive paste, reducing electrical resistance and improving the reliability of the wiring substrate by ensuring better adhesion and filling of the blind holes with conductive material.

Implementation Method 1

forming a primary blind hole by irradiating a first surface of the insulating portion with first laser light and removing at least a part of the insulating portion

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Implementation Method 2

forming a blind hole having a portion of the metal portion as a bottom surface by irradiating a bottom surface defining the primary blind hole with second laser light having a shorter wavelength than the first laser light

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Data Source

PatentUS20240204158A1Wiring substrate, light-emitting device, and manufacturing methods thereof

Publication Date: 2024.06.20 NICHIA CORP

AI summary

A wiring substrate including a substrate including an insulating portion with a through hole connecting a first surface and a second surface, and a metal portion faces the second surface and closes the through hole to form a blind hole. A conductor is disposed in the blind hole. The metal portion being a bottom surface defining the blind hole includes a first recess, a second recess, and a first lateral wall between the first and second recesses. In a cross-sectional view, the first lateral wall includes a first lower end portion in the first recess, a second lower end portion in the second recess, and a first top portion between the first and second lower end portions, The first top portion is immediately above a bottom surface defining the first recess, and the first lower end portion is closer to the second recess than the first top portion.