Recessed PCB Via Structure for Thin Fine-Pitch Packages
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Solution Overview
Problem
The increasing size and thickness of electronic components, such as application processors and memory modules, pose challenges in reducing the size and thickness of electronic component packages, particularly in package-on-package structures, necessitating a reduction in substrate thickness to achieve fine pitch electrical connections.
Innovation Solution
A printed circuit board design featuring recessed portions in the insulating layer with exposed vias and embedded fine-pitch wiring layers, allowing for direct electrical connections without separate lands, thereby minimizing thickness and enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the substrate thickness is reduced to achieve fine pitch electrical connections, then the package size is reduced, but the structural strength and reliability may deteriorate
Solution Approach 1:
The substrate is divided into a first substrate and a second substrate coupled together, forming a layered structure. This segmentation allows each substrate to be optimized independently - the first substrate can have reduced thickness for fine pitch connections while the second substrate provides additional structural support, resolving the contradiction between package size reduction and structural strength maintenance.
Solution Approach 2:
The invention transitions from a single-substrate approach to a multi-substrate stacked architecture. By adding the vertical dimension through substrate stacking, the design achieves fine pitch electrical connections in the horizontal plane while maintaining overall structural integrity through the vertical coupling of multiple substrates, effectively resolving the size-strength tradeoff.
2Manufacturing precision
If the height of electrical connection metal is lowered to reduce package thickness, then the fine pitch between electrical connection metal bumps is achieved, but the electrical connection reliability may worsen
Solution Approach 1:
The electrical connection path is segmented into multiple sections distributed across different substrates and layers. Instead of relying on a single tall metal structure, the connection is distributed through multiple lower-height metal elements across the first and second substrates, achieving fine pitch while maintaining reliability through redundancy and distributed connectivity.
Solution Approach 2:
The electrical connection approach moves from vertical height dominance to horizontal distribution. By utilizing the vertical stacking of substrates, the design achieves fine pitch horizontal spacing between connection points while the overall connection reliability is maintained through the multi-layer vertical architecture, effectively resolving the pitch-reliability contradiction.
3Volume of moving object
If circuit patterns with fine pitch are embedded in the substrate surface, then the overall thickness is reduced, but the manufacturing complexity increases
Solution Approach 1:
The manufacturing complexity is segmented and distributed across two separate substrates. Each substrate can be manufactured with standard fine pitch circuit patterns using conventional processes, avoiding the need for single-substrate ultra-fine pitch manufacturing. The segmented approach allows each substrate to be optimized for manufacturability while achieving reduced overall thickness through stacking.
Solution Approach 2:
Instead of attempting to embed all circuit patterns at ultra-fine pitch in a single substrate surface, the invention uses partial action by distributing circuit patterns across multiple substrates. Each substrate contains a portion of the overall circuitry at manageable pitch, and the excessive action of stacking multiple substrates compensates for the distributed architecture, achieving reduced thickness without prohibitive manufacturing complexity.
Data Source
AI summary
A printed circuit board includes: a first insulating layer having at least one recess portion in one surface thereof; a first wiring layer embedded in one surface of the first insulating layer; and a first via layer including a first via penetrating through at least a portion of the first insulating layer, one surface of the first via being exposed externally through the recess portion.