Oxygen-Free Copper Soldering Surface to Block Solder Flow
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Solution Overview
Problem
Conventional soldering boards face issues with insulating solder masks, such as delamination, peeling, cracking, and contamination due to the difficulty in accurately forming insulating solder masks around closely positioned solder pads, and the use of insulating materials leads to restrictions.
Innovation Solution
An electronic assembly with an oxygen-free copper layer that includes soldering surfaces and an anti-soldering surface, where the anti-soldering surface is formed without an insulating layer and has specific roughness and height differences to prevent solder flow, eliminating the need for an insulating solder mask.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an insulating solder mask is used on conventional soldering boards, then soldering protection is provided, but manufacturing precision deteriorates due to difficulty in accurately forming the mask around closely positioned solder pads
Solution Approach 1:
The invention extracts and removes the insulating solder mask layer entirely, replacing it with an anti-soldering structure formed directly on the copper surface through roughness control. This eliminates the manufacturing precision issues associated with mask formation while maintaining soldering protection through the anti-soldering surface's ability to prevent unwanted solder adhesion.
Solution Approach 2:
The invention changes the surface parameter (roughness) of the copper layer to create anti-soldering properties. By controlling the arithmetic mean roughness (Ra) and maximum height roughness (Rz) of the copper surface, the patent achieves soldering protection without requiring an insulating mask, thus resolving the manufacturing precision problem.
2Reliability
If an insulating solder mask is used on conventional soldering boards, then soldering protection is provided, but reliability deteriorates due to delamination, peeling, and cracking
Solution Approach 1:
The invention removes the insulating solder mask layer that causes delamination, peeling, and cracking. By replacing the mask with a surface-roughness-based anti-soldering structure on the copper layer, the patent eliminates these reliability issues while maintaining soldering protection.
Solution Approach 2:
The invention uses the copper layer itself with modified surface properties (roughness control) to provide both structural support and anti-soldering functionality, eliminating the need for composite mask structures that are prone to delamination and cracking.
3Reliability
If an insulating solder mask is used on conventional soldering boards, then soldering protection is provided, but device complexity increases due to additional layers and processes
Solution Approach 1:
The invention extracts and eliminates the insulating solder mask layer and associated formation processes, reducing device complexity. The anti-soldering function is achieved through surface roughness control of the copper layer, which is integrated into the existing board structure.
Solution Approach 2:
The invention merges the anti-soldering function into the copper layer itself by controlling its surface roughness, eliminating the need for separate insulating mask layers and simplifying the overall structure while maintaining soldering protection.
4Reliability
If an insulating solder mask is used on conventional soldering boards, then soldering protection is provided, but manufacturing precision deteriorates due to positioning accuracy issues with closely positioned solder pads
Solution Approach 1:
The invention applies different surface roughness characteristics to different regions of the copper layer: smooth regions for soldering surfaces and rough regions for anti-soldering surfaces. This local quality differentiation enables precise soldering control without requiring insulating masks, thus maintaining manufacturing precision for closely positioned pads.
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 anti-soldering surface effectively blocks solder flow, avoiding issues like delamination, peeling, and contamination, while eliminating the need for insulating solder masks.
Implementation Method 1
the anti-soldering surface has a second Ra and a second Rz. The second Ra is greater than the first Ra, and a Ra difference between the second Ra and the first Ra is within a range from 0.15 μm to 10 μm. The second Rz is greater than the first Rz, and a Rz difference between the second Rz and the first Rz is within a range from 0.5 μm to 16 μm. The solders are respectively fixed to the soldering surfaces of the oxygen-free copper layer. The electronic component is fixed to the solders and is electrically coupled to the oxygen-free copper layer. The anti-soldering surface is configured to block the solders in a melted state from flowing thereon through the Ra difference and the Rz difference.
Data Source
AI summary
An electronic assembly, a soldering board, and an oxygen-free copper layer are provided. The oxygen-free copper layer has a plurality of soldering surfaces and an anti-soldering surface that is connected to the soldering surfaces. Each of the soldering surfaces has a first arithmetic mean roughness (Ra) and a first maximum height roughness (Rz), and the anti-soldering surface has a second Ra and a second Rz. The second Ra is greater than the first Ra, and a Ra difference between the second Ra and the first Ra is within a range from 0.15 μm to 10 μm. The second Rz is greater than the first Rz, and a Rz difference between the second Rz and the first Rz is within a range from 0.5 μm to 16 μm. The anti-soldering surface is configured to block a solder in a melted state from flowing thereon.