Silicon Bridge Interconnect Layout for Mixed-Pitch Chip Attach
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Solution Overview
Problem
Current Direct Chip Attach (DCA) technologies face limitations due to mismatched bump pitch scaling between System On Chip (SOC) dies and board design rules, restricting the number of interconnects that can be made, especially in high-density interconnect applications.
Innovation Solution
The use of a silicon bridge with high-density interconnects having a low bump pitch to interconnect microelectronic dies, allowing for dense connections while accommodating board pad size and line/space rules, and the creation of a recess in the circuit board to receive the bridge, enabling relaxed tolerances in board production and assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If Direct Chip Attach (DCA) is used with large bump pitch to accommodate board design rules, then board compatibility is improved, but interconnect density deteriorates
Solution Approach 1:
The invention segments the interconnection system into three parts: the SOC die with high-density fine-pitch interconnects, the bridge die with matching interconnects on both sides, and the board with standard-pitch pads. This segmentation allows each component to have optimized pitch characteristics, resolving the contradiction between board compatibility and interconnect density.
Solution Approach 2:
The bridge die serves as an intermediary component between the SOC die and the board. It has fine-pitch interconnects facing the SOC die and standard-pitch pads facing the board, effectively mediating the pitch mismatch and enabling both high-density interconnection and board compatibility.
2Quantity of substance
If C4 bump pitch is scaled down for high-density interconnects, then interconnect density is improved, but board pad size compatibility deteriorates
Solution Approach 1:
The bridge die exhibits local quality by having different pitch characteristics on different sides. The side facing the SOC die has fine pitch matching the high-density interconnects, while the side facing the board has standard pitch matching board pad sizes. This local differentiation resolves the contradiction between interconnect density and board pad compatibility.
3Quantity of substance
If high-density interconnects with low bump pitch are used, then interconnect density is improved, but manufacturing precision requirements worsen
Solution Approach 1:
The bridge die is pre-formed with fine-pitch interconnects in a controlled manufacturing environment where high precision is feasible. This preliminary creation of the precision component allows the final assembly to tolerate broader variations in board pad positioning, effectively transferring the precision requirement to the manufacturing stage rather than the assembly stage.
Data Source
AI summary
Embodiments that allow both high density and low density interconnection between microelectronic die and motherboard via Direct Chip Attach (DCA) are described. In some embodiments, microelectronic die have a high density interconnect with a small bump pitch located along one edge and a lower density connection region with a larger bump pitch located in other regions of the die. The high density interconnect regions between die are interconnected using an interconnecting bridge made out of a material that can support high density interconnect manufactured into it, such as silicon. The lower density connection regions are used to attach interconnected die directly to a board using DCA. The high density interconnect can utilize current Controlled Collapsed Chip Connection (C4) spacing when interconnecting die with an interconnecting bridge, while allowing much larger spacing on circuit boards.