DDR Chip Pinmap Layout for Crosstalk Reduction and High Density
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Solution Overview
Problem
The increasing number of channels in DDR systems leads to larger chip package sizes, thermal stress, and electromagnetic crosstalk issues, which affect yield and cost, and existing methods to reduce crosstalk increase package size.
Innovation Solution
A pinmap arrangement on the package substrate with cross-shaped patterns of data and control signal pins, staggered arrangements, and ground pins to minimize electromagnetic crosstalk while maintaining high density and controlling package size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the number of channels in DDR system is increased to improve performance, then the data transmission capacity is improved, but the chip package size becomes larger
Solution Approach 1:
The patent transitions from traditional linear or grid arrangements to a cross-shaped pinmap pattern that utilizes two-dimensional spatial distribution more efficiently. The cross-shaped pattern allows pins to be arranged along both horizontal and vertical axes, maximizing the use of available package area and enabling higher channel density without proportionally increasing package size.
Solution Approach 2:
The pinmap is segmented into multiple cross-shaped patterns, each handling specific channels. This segmentation allows independent optimization of each cross-pattern and enables systematic scaling of channel capacity by adding or removing complete cross-patterns rather than individually placing pins throughout the package.
2Quantity of substance
If the chip package size is increased to accommodate more pins, then the pin density can be maintained, but the thermal stress and welding reliability deteriorate
Solution Approach 1:
The patent changes the spatial distribution parameters of pins by adopting a cross-shaped pattern with specific spacing relationships. The distance between adjacent pins in different arms of the cross is optimized to reduce thermal coupling, while the overall compact structure minimizes the maximum distance from any pin to the package center, thereby reducing thermal stress gradients and improving welding reliability.
3Object-affected harmful factors
If ground solder balls are disposed around pins to reduce electromagnetic crosstalk, then the electromagnetic interference is reduced, but the chip package size increases
Solution Approach 1:
The patent introduces control signal pins as intermediaries positioned between data signal pins in the cross-shaped pattern. These control signal pins act as electromagnetic shields that reduce crosstalk between adjacent data pins without requiring additional ground pins, thereby maintaining signal integrity while avoiding increased package size.
Solution Approach 2:
The control signal pins serve multiple functions: they provide timing/control signals for DDR operations and simultaneously act as electromagnetic shields between data pins. This multi-functionality eliminates the need for dedicated ground pins solely for crosstalk reduction, maintaining high pin density without increasing package area.
4Speed
If the DDR interface rate is increased to improve performance, then the data transmission speed is improved, but the electromagnetic crosstalk between adjacent signals increases
Solution Approach 1:
The patent creates a composite signal arrangement where data signal pins and control signal pins are interleaved in the cross-shaped pattern. This composite structure provides inherent electromagnetic shielding at the pin level, reducing crosstalk effects that would otherwise limit high-speed operation, thereby enabling higher DDR interface rates.
Data Source
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AI summary
A chip, a chip manufacturing method, a computing device, and a signal transmission method are provided. A package substrate of the chip includes a basic pattern with six signal pins. A first pin, a second pin, a third pin, and a fourth pin in the six signal pins are sequentially spaced apart in a first direction, and a fifth pin and a sixth pin are spaced apart in a second direction. The fifth pin and the sixth pin are respectively located on two sides of a connection line between the second pin and the third pin. The first pin, the fourth pin, the fifth pin, and the sixth pin are data signal pins, and the second pin and the third pin are control signal pins. In this solution, the data signal pins are respectively arranged at four extension ends of a cross-shaped pattern, the data signal pins are far away from each other, and each data signal pin has no adjacent data signal pin that may form a crosstalk source. In this way, electromagnetic crosstalk between pins can be effectively reduced. In addition, density of a pinmap can be improved, and a package area can be reduced.