Multilayer Wiring Board Flat Surface Formation for Resistance Accuracy
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Solution Overview
Problem
Conventional multilayer wiring boards experience errors in resistive element values due to the formation of resistive elements on convexo-concave surfaces, leading to increased length and thickness variations, which affect the accuracy of resistance values.
Innovation Solution
A method is introduced to form a flat surface on the multilayer wiring board using a dummy layer, allowing for the deposition of resistive elements on a stable surface, preventing length and thickness variations, and improving the accuracy of resistance values by using a conductive material for the dummy layer and electroplating with pulse current to achieve a flat surface without additional polishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If resistive elements are formed on the convexo-concave surface of the multilayer wiring layer, then the manufacturing process is simplified, but the resistance value accuracy deteriorates due to length and thickness variations
Solution Approach 1:
A flat surface is formed on the multilayer wiring layer before depositing the resistive element material. This preliminary surface preparation ensures that the resistive elements are deposited on a flat surface, preventing the formation of waved shapes and eliminating length and thickness variations that would otherwise occur on convexo-concave surfaces, thereby maintaining resistance value accuracy
Solution Approach 2:
An intermediate layer is introduced between the multilayer wiring layer and the resistive element material. This intermediate layer serves as a mediator that provides a flat deposition surface for the resistive elements, while the convexo-concave surface of the underlying multilayer wiring layer is preserved. The intermediate layer effectively decouples the surface topology from the deposition process
2Reliability
If the multilayer wiring layer has convexo-concave surface, then via connection is achieved, but the resistive element length increases due to meandering path
Solution Approach 1:
The flat surface is prepared before resistive element deposition, ensuring that the resistive elements follow a straight path rather than meandering along the convexo-concave surface. This preliminary surface flattening action prevents unnecessary length increase while maintaining the via connection functionality of the underlying convexo-concave structure
Solution Approach 2:
The solution addresses the surface topology issue by working in a different dimensional approach - either by adding an intermediate dimension (intermediate layer) or by modifying the surface dimension (forming flat surface). This allows the via connection to be maintained in the vertical dimension while the horizontal dimension provides a straight path for resistive elements
3Ease of manufacture
If resistive elements are deposited on convexo-concave surface, then material deposition is simplified, but thickness variation increases leading to resistance error
Solution Approach 1:
The flat surface is formed before depositing the resistive element material, providing a uniform baseline for material deposition. This preliminary surface preparation ensures that the deposited material has uniform thickness across the resistive element area, eliminating the thickness variations that would occur on convexo-concave surfaces
Solution Approach 2:
An intermediate layer is introduced as a mediator between the convexo-concave multilayer wiring layer and the resistive element material. This intermediate layer provides a flat deposition surface that ensures uniform material thickness, while the underlying convexo-concave structure is preserved for via connection purposes
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 multilayer wiring boards with reduced resistance value variations, enabling more accurate electrical matching and testing by restricting noise and ensuring precise resistance values.
Implementation Method 1
electroplating with pulse current to achieve a flat surface
Implementation Method 2
depositing the resistive element material on the flat surface
Data Source
AI summary
A method of manufacturing a multilayer wiring board is provided. A flat surface is formed on a surface of a multilayer wiring layer, and resistive material is deposited on the flat surface. The multilayer wiring board comprises a multilayer wiring layer on whose surface convexo-concave is formed, a dummy layer burying the convexo-concave, a resistance material layer made of an electrical resistance material deposited on the dummy layer and at an area going beyond the dummy layer, and a wire made of a conductive material deposited on the resistance material layer and ranging from the area going beyond the dummy layer to a part of the flat surface area of the dummy layer, wherein a resistive element is formed at an area of the resistance material layer that the wire does not reach.