Printed Wiring Board Land Segmentation for Vibration Resistance
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Solution Overview
Problem
Conventional printed wiring boards in electric tool switches face challenges in securing peeling strength against vibrations while preventing solder flux from extending onto the back face, with existing solutions either enhancing peeling strength at the cost of allowing flux through or vice versa, and complicating the production process.
Innovation Solution
A printed wiring board design featuring a main land with a metallic film covering the peripheral region of a first hole on the front and back faces but not the sidewall, and a sub-land with a metallic film covering both faces of a second hole, connected to the main land through a metallic pattern, which enhances peeling strength and prevents flux from reaching the back face by using a resist film to contain solder material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metallic film is formed on the sidewall of the hole to enhance peeling strength, then the peeling strength of the wiring pattern is improved, but solder flux extends onto the back face of the printed wiring board
Solution Approach 1:
The land is divided into two separate holes: a first hole without metallic film on the sidewall to prevent flux extension, and a second hole with metallic film on the sidewall to enhance peeling strength. This segmentation allows each hole to serve its specific function independently, resolving the contradiction between flux prevention and strength enhancement.
Solution Approach 2:
The metallic film is selectively applied only to the sidewall of the second hole, not the first hole. This local differentiation allows the region needing flux containment (first hole) to remain free of metallic film, while the region needing strength (second hole) receives the metallic film coating.
2Object-generated harmful factors
If a metallic film is formed only on the front face to prevent flux extension, then solder flux is contained on the front face, but the peeling strength of the wiring pattern is reduced
Solution Approach 1:
The solution segments the land into two separate holes with different metallic film configurations. The first hole has metallic film only on the front face to contain flux, while the second hole has metallic film on the sidewall to provide peeling strength, thus resolving the contradiction.
Solution Approach 2:
The invention transitions from a single-hole configuration to a multi-hole configuration, adding spatial dimensionality. By distributing the functional requirements across multiple holes (first hole for flux containment, second hole for strength), the contradiction is resolved through dimensional expansion.
3Strength
If through-hole land configuration is used to enhance peeling strength, then peeling strength is improved, but the production process becomes more complex
Solution Approach 1:
The land is segmented into two holes that can be formed using standard drilling and plating processes. This segmentation allows the use of conventional manufacturing techniques rather than requiring complex new processes, thus enhancing strength without significantly increasing production complexity.
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 configuration effectively secures peeling strength against vibrations and prevents solder flux from reaching the back face, simplifying the production process and improving the reliability of the wiring pattern in electric tool switches.
Implementation Method 1
the main land is constructed with a metallic film configured to cover a peripheral region of the first hole in at least a front face of the printed wiring board including the front face and the back face
Implementation Method 2
using a resist film to contain solder material
Implementation Method 3
a sub-land that is connected to the main land through the metallic pattern
Data Source
Figure 1A~1C
Figure 2A~3
Figure 4~5
AI summary
One aspect of the present invention provides a printed wiring board (10) that satisfies both securement of a peeling strength against a vibration in a wiring pattern of the printed wiring board (10) and prevention of a flux from flying onto a back face (10b) side of the printed wiring board (10). Connection part (10A) includes hole (11) in which a projecting portion of an external member is inserted, soldering land (12) in which a metallic film is formed only on front face (10a) to which the projecting portion is soldered, at least one lead pattern (13) that is drawn from soldering land (12), and micro-hole through-hole land (14) that is connected to soldering land (12) through lead pattern (13).