Wiring Board Multi-Layer Pad Layout for Alignment Tolerance
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Solution Overview
Problem
As IC chips become finer and more integrated, the increased number of mounting pads on package substrates at finer pitches poses challenges in maintaining proper positional alignment during mounting, leading to potential connection failures due to positional shifting.
Innovation Solution
A wiring board design featuring a first insulation layer with first mounting pads, a wiring structure within a second insulation layer with second conductive patterns and mounting pads, and additional third mounting pads positioned above the second pads to create a wider spacing between adjacent pads, allowing for increased tolerance in positional shifting during semiconductor element mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the number of mounting pads is increased at finer pitches to accommodate higher integration, then the mounting precision requirement increases, but the positional alignment reliability deteriorates due to potential positional shifting during mounting
Solution Approach 1:
The patent introduces a multi-layer structure with first mounting pads on the upper surface and second mounting pads on the lower surface, utilizing the third dimension (depth/layering) to provide alternative mounting options. This dimensional transition allows semiconductor elements to be mounted on either surface, compensating for positional shifting issues on the finer-pitched first mounting pads by potentially using the second mounting pads instead.
2Quantity of substance
If the distance between adjacent mounting pads is reduced to increase integration density, then the number of mounting pads increases, but the tolerance for positional shifting decreases
Solution Approach 1:
The patent divides the mounting pad system into two separate groups: first mounting pads on the upper surface and second mounting pads on the lower surface. This segmentation allows the total number of mounting pads to be doubled while maintaining larger effective spacing, as elements can be distributed across both surfaces. The finer pitch requirement is relaxed because the segmented structure provides alternative mounting locations that are not constrained by the tight spacing on a single surface.
Data Source
AI summary
A wiring board includes a first insulation layer, first conductive patterns formed on the first insulation layer and including first mounting pads positioned to mount a semiconductor element, a wiring structure positioned in the first insulation layer and having a second insulation layer, second conductive patterns formed on the second insulation layer, and second mounting pads connected to the second conductive patterns, and third mounting pads formed on the first insulation layer above the second mounting pads and connected to the second mounting pads such that the third mounting pads are positioned to mount the semiconductor element and form a distance between adjacent first and third mounting pads which is greater than a distance between adjacent first mounting pads.