Mounting Substrate Conductor Thickness Control
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Solution Overview
Problem
In planar coil structures, non-uniform film thickness caused by electroplating leads to bonding failures when the coil component is mounted on a substrate, as the varying conductor thickness results in inconsistent solder wrapping and increased bonding failure rates.
Innovation Solution
A mounting substrate with a resin layer and a first conductor having a non-uniform thickness, where the difference in distance between the first and second surfaces is minimized on the mounting surface side, ensuring uniform solder wrapping and reducing bonding failures, while the second surface with a larger difference can still function as a mounting electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electroplating is used to form the conductor, then the conductor can be formed with controlled thickness, but the film thickness becomes non-uniform leading to bonding failures
Solution Approach 1:
The conductor is designed with non-uniform thickness where different regions serve different functions: the first surface has controlled thickness variation (≤10μm) for reliable solder wrapping, while the second surface can have larger thickness variation (>10μm) since it functions as a mounting electrode rather than a bonding surface. This local differentiation resolves the contradiction by optimizing each region's thickness characteristics for its specific function.
Solution Approach 2:
The conductor is segmented into two distinct surfaces with different thickness characteristics: the first surface facing the mounting surface with minimal thickness variation for bonding reliability, and the second opposite surface with larger thickness variation that is acceptable for electrode function. This segmentation allows each surface to independently optimize for its specific requirement.
2Reliability
If the conductor thickness is reduced for uniform solder wrapping, then bonding reliability improves, but the conductor's electrical performance and mechanical strength may be compromised
Solution Approach 1:
The conductor structure provides different thickness characteristics at different locations: the first surface has controlled thickness variation to ensure reliable solder wrapping, while the overall conductor maintains sufficient thickness and cross-sectional area to preserve electrical performance and mechanical strength. The non-uniform thickness distribution optimizes both bonding reliability and conductor strength simultaneously.
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 effectively reduces bonding failures by ensuring sufficient solder wrapping on the first surface and allows for efficient manufacturing with reduced distance variations, enhancing the bonding strength and reliability of the mounting process.
Implementation Method 1
a printed circuit board technique is applied to a structure of a coil component. For example, Japanese Laid-Open Patent Publication No. 2012-248630 describes a coil component including a planar spiral conductor formed by electroplating on both surfaces of a substrate.
Data Source
AI summary
A mounting substrate includes a resin layer and a first conductor including a contact surface in contact with the resin layer. The first conductor includes a first surface facing toward the mounting surface and a second surface on a side opposite to the first surface and extends in a direction parallel or substantially parallel to the mounting surface. The first conductor has a difference of a maximum value and a minimum value of a distance between the first surface and the mounting surface smaller than a difference of a maximum value and a minimum value of a distance between the second surface and the mounting surface. The resin layer includes a resin wall portion surrounding an opening portion partially exposing the first conductor on the mounting surface side, and the first conductor includes an exposed portion defining a mounting electrode.