Multilayer PCB Selective Corrosion Layer for Drop Impact Buffering
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Solution Overview
Problem
Conventional multilayer printed wiring boards face challenges in maintaining reliability and connectivity due to uniform corrosion-resistant layers, which lead to stress transmission and increased vulnerability to warping and cracking under temperature changes and mechanical stress.
Innovation Solution
A multilayer printed wiring board design where corrosion-resistant layers are selectively formed on specific solder pads, allowing for mixed stiffness and flexibility, enabling better stress buffering and reduced risk of cracking, while maintaining electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a uniform corrosion-resistant layer is formed on all solder pads, then corrosion protection is improved, but stress transmission increases leading to warping and cracking
Solution Approach 1:
The patent applies local quality by forming corrosion-resistant layers selectively on specific solder pads rather than uniformly across all pads. The mask layer is removed only from pads requiring corrosion resistance, creating local differentiation. This allows pads subject to higher stress to remain flexible while pads requiring protection gain corrosion resistance, resolving the contradiction between uniform protection and stress resistance.
2Reliability
If corrosion-resistant layer is formed on all solder pads, then protection is improved, but flexibility and stress buffering capability deteriorate
Solution Approach 1:
The invention implements local quality by differentiating the treatment of solder pads based on their functional requirements. Some pads receive corrosion-resistant layers while others remain exposed, allowing the board to adapt to different stress conditions in different regions. This selective approach maintains stress buffering capability in critical areas while providing protection where needed.
3Strength
If selective corrosion-resistant layer formation is implemented, then stress buffering is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by forming the mask layer before the corrosion-resistant layer deposition. The mask layer is patterned in advance to define which pads will receive corrosion resistance. This preliminary patterning simplifies the subsequent corrosion-resistant layer formation process, as it can be applied uniformly and then selectively removed, rather than requiring complex selective deposition techniques.
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 selective formation of corrosion-resistant layers enhances the board's reliability and connectivity, reducing the likelihood of warping and cracking, and improving long-term durability and functionality.
Implementation Method 1
a corrosion resistant layer formation pad in which the corrosion resistant layer is formed and a corrosion resistant layer non-formation pad in which no corrosion resistant layer is formed coexist as said solder pad
Data Source
AI summary
A method of manufacturing multilayer printed wiring hoard in which electric connectivity and functionality are obtained by improving reliability and particularly, reliability to the drop test can be improved. In the inventive method, no corrosion resistant layer is formed on a solder pad on which a component is to be mounted so as to obtain flexibility. Thus, if an impact is received from outside when a related product is dropped, the impact can be buffered so as to protect any mounted component from being removed. On the other hand, a land in which the corrosion resistant layer is formed by the method is unlikely to occur contact failure even if a carbon pillar constituting an operation key makes repeated contacts.