Teardrop Connection Pads for Semiconductor Package Base Substrates
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Solution Overview
Problem
The challenge in the electronics industry is to enhance the reliability of semiconductor packages with stacked semiconductor chips, as the limit of high integration is nearing, and existing solutions fail to effectively prevent defects in the package base substrate.
Innovation Solution
A package base substrate design featuring a base layer with lower surface connection pads, wiring patterns, and a solder resist layer, including teardrop-shaped pads with a ball land portion, extension line, and corner reinforcement to secure connections and prevent cracking under stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional connection pads with simple shapes are used, then the manufacturing process is simple, but the connection reliability deteriorates due to cracking under stress
Solution Approach 1:
The connection pad is segmented into multiple functional regions: a ball land portion for solder ball attachment, an extension line portion for stress distribution, and a corner reinforcement portion for crack prevention. This segmentation allows each region to perform its specific function optimally, improving overall connection reliability while managing structural complexity through functional specialization.
Solution Approach 2:
Different regions of the connection pad are designed with different geometric properties tailored to their specific functions. The ball land portion has a circular shape optimized for solder ball attachment, the extension line portion has a linear shape for stress distribution, and the corner reinforcement portion has an enlarged geometry for crack prevention. This local quality approach ensures each area has the precise characteristics needed for its role.
2Reliability
If the extension line portion length is increased to improve stress distribution, then connection reliability improves, but the pad area increases
Solution Approach 1:
The extension line portion extends only partially from the ball land portion, with its length specifically controlled to be greater than the radius of the ball land portion but not excessively long. This partial extension provides sufficient stress distribution capability while minimizing the additional area occupied, achieving an optimal balance between reliability improvement and area consumption.
3Reliability
If the corner reinforcement portion is added to prevent cracking, then connection reliability improves, but the manufacturing complexity increases
Solution Approach 1:
The corner reinforcement portion is designed in advance at the pad layout stage, with its geometry predetermined to prevent cracking before they occur. By pre-positioning this reinforcement structure at vulnerable corner areas, the design proactively addresses potential failure points without requiring complex manufacturing processes or additional assembly steps.
Data Source
AI summary
A package base substrate includes a base layer; a plurality of lower surface connection pads disposed on a lower surface of the base layer; a plurality of lower surface wiring patterns disposed on a lower surface of the base layer and respectively connected to a set of lower surface connection pads of the plurality of lower surface connection pads; and a lower surface solder resist layer covering a portion of each of the plurality of lower surface connection pads and the plurality of lower surface wiring patterns on a lower surface of the base layer, wherein each of at least some of the lower surface connection pads of the set of lower surface connection pads has a teardrop shape in a plan view, and includes a ball land portion having a planar circular shape, including a terminal contact portion exposed without being covered by the lower surface solder resist layer, and an edge portion surrounding the terminal contact portion and covered by the lower surface solder resist layer; and a connection reinforcement portion between the ball land portion and the lower surface wiring pattern, including an extension line portion having a width that is the same as a line width of the lower surface wiring pattern and extending from the ball land portion to the lower surface wiring pattern, and a corner reinforcement portion filling a corner between the ball land portion and the extension line portion, and wherein an extension length of the extension line portion has a value greater than a radius of the terminal contact portion.