Selective Laser Roughening for Electroless Plating Adhesion
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Solution Overview
Problem
Existing methods for selectively forming electroless plating on circuit forming portions of synthetic resin bases using laser irradiation face challenges such as residual catalyst nucleating agents leading to unwanted plating on non-circuit areas, decreased insulating properties, and labor-intensive processes for removing palladium from non-circuit areas.
Innovation Solution
The method involves selectively irradiating the circuit forming portion of a synthetic resin base with a laser to roughen and modify the surface, using an ion catalyst composed of a single metal ion like palladium, and reducing it with a reducing agent to prevent unwanted electroless plating on non-circuit areas by ensuring tight adsorption of the catalyst only on the modified surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If chemical etching using hexavalent chromium sulfate is used to roughen the surface, then adhesiveness with electroless plating is improved, but work environment deteriorates and cumbersome treatment processes are required
Solution Approach 1:
The invention changes the chemical parameters by replacing hexavalent chromium sulfate with a different etching composition that does not contain hexavalent chromium, thereby maintaining the surface roughening effect while eliminating the toxic harmful factors
Solution Approach 2:
The invention uses a disposable masking layer made of water-soluble polymer that can be easily removed by washing, replacing the need for complex and cumbersome treatment processes required for hexavalent chromium neutralization and precipitation
2Strength
If the entire surface is roughened by chemical etching, then adhesiveness is improved, but insulating property decreases under high humidity environment
Solution Approach 1:
The invention applies surface roughening only to the circuit forming portion where it is needed for adhesiveness, while leaving the non-circuit forming portion smooth to maintain its insulating properties and hydrophobicity under high humidity conditions
Solution Approach 2:
The invention segments the surface treatment by using a masking layer to divide the base surface into circuit forming portions (to be roughened) and non-circuit forming portions (to be kept smooth), allowing differential treatment of different areas
3Strength
If laser irradiation is used to selectively roughen the surface, then adhesiveness is improved and environment is protected, but residual catalyst may cause unwanted plating on non-circuit areas
Solution Approach 1:
The invention introduces a masking layer as an intermediary substance that prevents catalyst adsorption on non-circuit forming portions during the electroless plating process, thereby eliminating unwanted plating while maintaining the benefits of laser roughening on circuit areas
Solution Approach 2:
The masking layer is applied in advance to non-circuit forming portions to prevent catalyst adsorption before the electroless plating process occurs, thereby preemptively avoiding unwanted plating on areas where it should not occur
4Manufacturing precision
If mask is used to cover non-circuit forming portion, then selective roughening is achieved, but labor hour increases
Solution Approach 1:
The invention uses a water-soluble polymer masking layer that can be easily and quickly removed by washing with water, significantly reducing the time and labor required compared to traditional masking methods that require solvent-based removal or mechanical stripping
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 effectively prevents electroless plating on non-circuit areas, maintains insulating properties under high humidity, conserves precious metals, and enhances adhesiveness and durability of the electroless plating layer by ensuring the catalyst is only adsorbed on the modified circuit areas.
Implementation Method 1
selectively irradiating the circuit forming portion of a synthetic resin base with a laser to roughen and modify the surface
Implementation Method 2
using an ion catalyst composed of a single metal ion like palladium, and reducing it with a reducing agent
Implementation Method 3
ensuring tight adsorption of the catalyst only on the modified surface
Data Source
Figure 1(A)~1(F)
Figure 2(A)~2(G)
AI summary
An electroless plating layer having strong adhesiveness is selectively formed on only a circuit forming portion, and other non-circuit forming portion is not roughened. A circuit forming portion 11 of a base 1 of a synthetic resin is selectively irradiated with a laser beam 2 having a wavelength of from 405 to 1, 064 nm, and an ion catalyst of palladium is adsorbed thereon and reduced to metal palladium by a reducing agent. An electroless plating layer 3 is then formed on the circuit forming portion 11. Since the surface of the circuit forming portion 11 is modified and roughened, the ion catalyst is fixed strongly, and the electroless plating layer 3 adheres strongly. The electroless plating layer 3 is not formed on a non-circuit forming portion 12 since the ion catalyst is not adsorbed on the portion wherein the portion has not been irradiated with the laser beam 2.