PCB Pad Concavity and Electrode Layout for Solder Overflow Control
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Solution Overview
Problem
The existing printed circuit boards face issues with trace collapse due to lack of support and electrical shorts caused by solder ball overflow, especially with finer trace widths and increased performance demands.
Innovation Solution
A circuit board structure is introduced, featuring a first insulating layer with a first circuit pattern layer and a second circuit pattern layer, along with electrode parts and concave portions on the pads to prevent solder ball overflow and enhance support for traces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the opening region of the solder resist is entirely opened in the first region, then the pad and trace are fully exposed for connection, but the trace collapses easily due to lack of support layer
Solution Approach 1:
The solder resist is selectively opened only in the second region where the pad is located, while remaining closed in the first region where the trace is located. This local differentiation allows the pad to be exposed for soldering while the trace remains covered and supported by the solder resist, preventing trace collapse without interfering with the connection process.
2Ease of operation
If the opening region of the solder resist is entirely opened in the first region, then the pad is accessible for solder ball connection, but solder balls overflow and cause electrical shorts
Solution Approach 1:
The solder resist opening is locally configured to expose only the pad area in the second region while maintaining coverage over the trace area in the first region. This selective opening allows solder balls to be properly contained around the pad during connection, preventing overflow and electrical shorts while still enabling effective pad access for soldering operations.
3Productivity
If the trace width is reduced to improve performance, then the circuit board density increases, but the trace becomes more prone to collapse without support
Solution Approach 1:
The solder resist provides continuous support coverage over the trace region, creating a protective layer that reinforces the trace structure. This local support mechanism allows the use of finer trace widths for improved circuit board density while preventing trace collapse through the underlying solder resist support layer.
Data Source
AI summary
A circuit board according to an embodiment includes a first insulating layer; a first circuit pattern layer disposed on the first insulating layer and including a first pad; a second circuit pattern layer disposed on a lower surface of the first insulating layer; and a first electrode part disposed in the first insulating layer and vertically overlapping the first pad, wherein a lower surface of the first electrode part is located higher than an upper surface of the second circuit pattern layer, and wherein the first pad includes a first concave portion formed in a region that vertically overlaps the first electrode part.