Wiring Board Desmear via Depletable Resist Layer
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Solution Overview
Problem
Existing desmear treatment methods for multilayer wiring boards often result in excessive surface roughness of the insulating layer, leading to issues like wiring failures and high-frequency signal deterioration, due to the exposure of fillers during the decomposition of the resin, and require complex treatment processes.
Innovation Solution
A desmear treatment method involving a depletable resist layer formed on the insulating layer, treated with ultraviolet rays and radicals, which allows for effective removal of smear within the holes without excessive surface roughening, using a method that includes forming a hole through both the resist and insulating layers and performing the desmear treatment with UV radiation under a radical-containing atmosphere.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a desmear treatment is performed under conditions capable of sufficiently removing the smear, then the smear removal effect is improved, but the surface of the insulating layer is excessively roughened due to filler exposure
Solution Approach 1:
The patent applies parameter changes by controlling the plasma treatment parameters (gas composition, power, treatment time) to achieve optimal desmear effectiveness while limiting surface roughness. The use of specific gas mixtures (oxygen, nitrogen, or carbon dioxide) and controlled power levels allows precise adjustment of the treatment intensity to remove smear without excessive filler exposure.
Solution Approach 2:
The patent replaces traditional mechanical or chemical desmear methods with plasma treatment. This substitution allows for more controlled and uniform smear removal through radical reactions, preventing the mechanical abrasion or chemical etching that would otherwise expose fillers and create excessive surface roughness.
2Shape
If a protective layer is formed on the insulating layer surface before desmear treatment, then the surface roughness is controlled, but the treatment process becomes complicated with additional steps
Solution Approach 1:
The patent applies self-service by using the insulating layer material itself as the protective mechanism. The controlled plasma treatment selectively removes smear while the insulating layer resin decomposes in a controlled manner to maintain surface integrity, eliminating the need for separate protective layers or post-treatment roughening steps.
Solution Approach 2:
The patent extracts only the necessary protective function from the complex multi-step process. By using controlled plasma parameters, the treatment achieves both smear removal and surface protection simultaneously, removing only the harmful smear while preserving the essential surface characteristics without adding extra protective layers.
3Shape
If the surface roughness of the insulating layer is too low, then the surface integrity is maintained, but additional roughening treatment is required
Solution Approach 1:
The patent achieves continuity of useful action by combining smear removal and surface roughness control into a single continuous plasma treatment step. The treatment continuously removes smear while simultaneously maintaining appropriate surface roughness through controlled resin decomposition, eliminating the need for separate roughening operations.
Solution Approach 2:
The patent merges two separate functions (smear removal and surface roughness control) into a single plasma treatment process. By optimizing plasma parameters, both objectives are achieved simultaneously in one step, improving productivity by eliminating additional treatment steps.
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 method enables sufficient desmear treatment within the holes of the insulating layer without complicating the process and achieves appropriate surface roughness, preventing filler exposure and maintaining the insulating layer's integrity.
Implementation Method 1
a desmear treatment step of treating the wiring board material having undergone the hole forming step with radicals
Implementation Method 2
treating the wiring board material having undergone the hole forming step with radicals... performed by radiating ultraviolet rays with the wavelength not more than 220 nm
Implementation Method 3
the depletable resist layer is made of a resin to be depleted in the desmear treatment step
Data Source
AI summary
A desmear treatment method for a wiring board material is provide that is capable of performing desmear treating on the interior of a through hole formed in an insulating layer without requiring complicated steps and obtaining an insulating layer having appropriate surface roughness. The desmear treatment method comprises forming a hole passing through an insulating layer, wherein the insulating layer is made of a resin containing a filler, and desmear treating the wiring board material with radicals. The wiring board material includes a depletable resist layer formed on the insulating layer, and the depletable resist layer is made of a resin to be depleted in the desmear treatment step. A method of manufacturing a wiring board material to be subjected to the desmear treatment method and a composite insulating layer forming material used in the manufacturing method are also disclosed.