Coreless Wiring Board Warpage Control via Segmented Molding Resin
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Solution Overview
Problem
Coreless wiring boards suffer from warpage issues due to the lack of a core substrate, making it difficult to accurately mount electronic components and connect external terminals, leading to potential connection failures.
Innovation Solution
A wiring board design featuring laminated insulating layers with a molding resin on top, where the molding resin is set to a specific thickness that does not protrude above the external connection terminals, providing support to the layers and reducing warpage without increasing the board's size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a coreless structure is used to reduce thickness, then the board thickness is reduced, but warpage occurs making it difficult to accurately mount components
Solution Approach 1:
The support function is segmented from the traditional core substrate and distributed to multiple molding resin layers positioned at different locations (first molding resin on the first surface, second molding resin on the second surface, and optionally third molding resin on the third surface). This segmentation provides localized support to reduce warpage while maintaining the overall coreless thin-structure design.
Solution Approach 2:
The molding resin acts as an intermediary material that provides mechanical support and warpage control without requiring a full core substrate. The molding resin layers are positioned between the insulating layers to provide structural stability, enabling accurate component mounting while maintaining reduced thickness.
2Manufacturing precision
If molding resin is added to support layers and reduce warpage, then mounting accuracy improves, but board thickness increases
Solution Approach 1:
The molding resin is applied locally at specific positions where support is needed rather than uniformly throughout the board. The first molding resin is positioned on the first surface near external connection pads, the second molding resin on the second surface near electronic component pads, and the third molding resin on the third surface near external connection terminals. This local application provides warpage control while minimizing overall thickness increase.
Solution Approach 2:
Instead of adding thickness uniformly in the vertical dimension, the support structure is distributed across multiple surfaces (first, second, and third surfaces) of the board. This multi-dimensional distribution of molding resin layers provides comprehensive warpage control while maintaining compact overall dimensions.
Data Source
AI summary
There is provided a wiring board. The wiring board includes: a plurality of laminated insulating layers including a first insulating layer, the first insulating layer being either one of an uppermost layer or a lowermost layer; wiring patterns formed in the plurality of insulating layers; external connection pads provided on the first insulating layer; external connection terminals provided on the external connection pads; and a molding resin provided on a surface of the first insulating layer on which the external connection pads are provided, the molding resin having openings from which the external connection pads are exposed. A thickness of the molding resin is set such that the molding resin does not protrude above the external connection terminals.