Printed Wiring Board Adhesion via Laser Ablation
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Solution Overview
Problem
Conventional printed wiring boards experience insufficient adhesion strength between the insulating layer and the metal layer due to exposure of insulating fillers, which affects the bonding and heat dissipation performance.
Innovation Solution
A board structure with an insulating layer containing a resin and insulating filler, where the resin is present partially between the insulating filler and the metal layer, and the metal layer is formed using electroless or dry-plating techniques, with a controlled depth of metal penetration into the insulating layer to enhance adhesion and reduce interlayer insulation distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If wet roughening treatment is performed to roughen the insulating layer surface, then surface roughness is improved, but insulating filler is exposed and adhesion strength between metal layer and insulating layer deteriorates
Solution Approach 1:
The invention changes the fundamental parameter of surface treatment from chemical wet roughening to physical laser ablation. This parameter change achieves surface roughness improvement without the harmful side effect of filler exposure, as laser ablation removes only the resin matrix while preserving the filler structure within the depth control range.
Solution Approach 2:
The invention replaces the chemical mechanism of wet roughening (using potassium permanganate or sodium permanganate solutions) with a physical mechanism (laser ablation). This substitution eliminates the chemical interaction that causes filler exposure while achieving the desired surface roughness through controlled material removal.
2Strength
If metal layer penetrates deeply into the insulating layer to improve adhesion, then adhesion strength is improved, but interlayer insulation distance is reduced and electrical conductivity deteriorates
Solution Approach 1:
The invention changes the parameter of metal penetration depth from deep penetration to controlled shallow penetration (0.5-2.0 μm). This parameter change is achieved through laser ablation which creates a rough surface that provides adequate adhesion area without requiring deep metal intrusion, thereby maintaining electrical insulation while achieving sufficient adhesion strength.
Solution Approach 2:
The invention applies local quality by creating surface roughness only in the top layer through laser ablation, while maintaining the integrity and insulation properties of the bulk insulating layer. The roughness is confined to a shallow depth (0.5-2.0 μm metal penetration), providing localized adhesion enhancement without compromising overall electrical insulation.
3Shape
If laser ablation is performed with high output and long pulse width to achieve sufficient roughness, then surface roughness is improved, but heat dissipation performance deteriorates and environmental impact increases
Solution Approach 1:
The invention optimizes laser parameters by using low output (≤1 W) and short pulse width (≤1 ps), which is a significant parameter change from conventional laser settings. This optimized parameter combination achieves sufficient surface roughness through cumulative effect of multiple pulses while minimizing heat input, thereby preserving heat dissipation performance and reducing environmental impact.
Solution Approach 2:
The invention uses periodic pulsed laser action with very short pulse widths (≤1 ps) and low output (≤1 W). The periodic pulsing allows heat to dissipate between pulses, preventing cumulative heating that would degrade heat dissipation performance. The multiple shallow pulses collectively achieve the required surface roughness without excessive thermal input.
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 provides sufficient adhesion strength and improved heat dissipation performance by utilizing the functional groups of the resin between the insulating filler and metal, while maintaining a reduced metal penetration depth, thus enhancing electrical conductivity and reducing environmental impact.
Implementation Method 1
the insulating layer is a layer obtained by performing a laser ablation on a surface of the resin containing the insulating filler
Implementation Method 2
a surface of the resin containing an insulating filler is subjected to a laser ablation
Implementation Method 3
a layer in direct contact with the insulating layer of the metal layer is an electroless-plated layer or a dry-plated layer
Implementation Method 4
a layer in direct contact with the insulating layer of the metal layer is an electroless-plated layer or a dry-plated layer
Data Source
AI summary
Provided is a new board with a sufficient adhesion strength between an insulating layer and a metal layer. A board of the embodiment is a board including an insulating layer and a metal layer. The insulating layer contains a resin containing an insulating filler. The metal layer is disposed on a surface of the insulating layer. The resin is present partially between at least a part of the insulating filler present in the surface of the insulating layer and a metal constituting the metal layer. In an interface between the insulating layer and the metal layer, a depth of the metal present at a deepest portion in the insulating layer is 1.2 µm or less based on the resin or the insulating filler present in an outermost surface of the insulating layer.