Castellated PCB Cut-in Features Prevent Conductor Delamination
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Solution Overview
Problem
The existing castellated printed circuit boards (PCBs) face issues with peel-off of the conductor layer due to mechanical forces and stress induced by the sawing process during PCB separation, leading to poor solder joints and device malfunction.
Innovation Solution
The introduction of cut-in features that overlap with the castellated contacts, reducing the area of the side wall covered by the conductor layer and preventing interaction with the sawing blade, thereby preventing delamination and improving the quality of solder joints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the PCB substrate is separated by sawing across the castellated contacts, then the individual PCBs can be obtained, but mechanical forces and stress are induced that cause peel-off of the conductor layer
Solution Approach 1:
The castellated contact structure is segmented into discrete quarter-through-holes at the corners of each PCB, allowing the sawing process to follow defined paths that minimize stress concentration on the conductor layer while maintaining separation efficiency
Solution Approach 2:
The conductor layer is pre-applied to the inner walls of the castellated contacts before the sawing process, ensuring that the plating is already in place and can withstand the mechanical forces during separation, preventing peel-off and delamination
2Ease of manufacture
If the sawing blade trails directly across the castellated contacts, then the PCBs can be separated, but the conductor layer is damaged leading to poor solder joints
Solution Approach 1:
The conductor layer is selectively positioned only on the inner walls of the castellated contacts rather than covering the entire edge, creating a localized conductive path that is protected from sawing damage while maintaining electrical functionality for solder joints
Solution Approach 2:
The castellated contact structure acts as an intermediary between the sawing process and the conductor layer, with the quarter-through-hole geometry and plating providing a protective barrier that shields the conductive material from direct mechanical contact with the sawing blade
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 implementation of cut-in features effectively prevents delamination of the conductor layer during the sawing process, enhancing the reliability of solder joints and reducing device failures caused by conductor layer damage.
Implementation Method 1
The side walls of these quarter-through-holes at each PCB is subsequently plated by a conductive material
Data Source
Figure 1A~1B
Figure 2A
Figure 2B
AI summary
Castellated printed circuit board, PCB, comprising a PCB substrate comprising a first side and an opposite second side, one or more castellated contact comprising a conductor extending from the first side of the PCB substrate to the second side, wherein the one or more castellated contact is arranged at a corner and/or an edge of the PCB substrate, at least one cut-in feature arranged to at least partially overlap with the one or more castellated contact.