Mixed-Core Solder Ball Layout for Semiconductor Package Heat Dissipation

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Solution Overview

Problem

Semiconductor packages face challenges with heat dissipation due to mismatched thermal expansion coefficients between chips, packaging adhesives, and substrates, leading to thermal stress and potential failures, as well as the limitations of existing ball grid array (BGA) packages in balancing heat transfer and substrate area usage.

Innovation Solution

A semiconductor package design incorporating multiple types of solder balls, including those with copper cores for enhanced thermal conductivity and resin cores for mechanical support, to improve heat dissipation and mechanical stability, with larger solder balls on the rear surface for better heat transfer and smaller ones on the front for higher density.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If larger solder balls are used to improve heat transfer capability, then heat dissipation efficiency is improved, but substrate area occupied increases which reduces BGA density and pin output

Engineering Contradiction:

Improveheat dissipation efficiencyVSAvoidsubstrate area occupied

Core Design Contradiction:

TemperatureVSArea of stationary object

Solution Approach 1:

The patent applies local quality by using different solder ball sizes at different locations on the substrate. Larger solder balls are placed in regions requiring better heat dissipation, while smaller solder balls are used in regions where space efficiency is more critical. This spatial variation in solder ball characteristics allows simultaneous optimization of heat transfer and substrate utilization.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The solder ball array is segmented into multiple size categories rather than using uniform solder balls. This segmentation enables different functional zones on the substrate to be served by appropriately sized solder balls, resolving the contradiction between heat dissipation requirements and area efficiency.

Inventive Principle:

Principle #1Segmentation

2Ease of manufacture

If uniform solder balls are used in BGA packages, then manufacturing simplicity is maintained, but heat dissipation efficiency is insufficient due to mismatched thermal expansion coefficients

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidheat dissipation efficiency

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent changes the parameter of solder ball size from uniform to varied. By implementing a distribution of different solder ball sizes rather than a single size, the system achieves better thermal management and mechanical stress distribution while maintaining compatibility with existing BGA manufacturing processes.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If larger solder balls are used to improve mechanical stability, then thermal stress resistance is improved, but substrate area occupied increases reducing package density

Engineering Contradiction:

Improvemechanical stabilityVSAvoidpackage density

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

Larger solder balls are strategically placed in regions experiencing higher thermal stress or requiring greater mechanical stability, while smaller solder balls are used in regions where mechanical demands are lower. This localized approach optimizes mechanical reliability without unnecessarily increasing overall substrate area consumption.

Inventive Principle:

Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The design significantly reduces the risk of package failures by enhancing heat dissipation and mechanical stability, allowing for more efficient transfer of heat from semiconductor chips to external structures, even under continuous thermal loads.

Implementation Method 1

The solder ball has the function of signal conduction, electrical connection, and heat conduction. The larger the solder ball, the stronger the heat transfer capability.

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

Methodology Applied

Scientific EffectThermal expansion mismatch: Thermal Expansion

Data Source

PatentUS20250006682A1Semiconductor packages with multiple types of solder balls

Publication Date: 2025.01.02 JCET MANAGEMENT CO LTD

AI summary

A semiconductor package comprise: a package substrate having a front surface and a rear surface, wherein the package substrate comprises: a set of front conductive patterns formed on the front surface; a set of rear conductive patterns formed on the rear surface; and a set of interconnects electrically coupling the set of front conductive patterns with the set of rear conductive patterns, respectively; at least one electronic component mounted on the front surface of the package substrate and electrically coupled to the set of front conductive patterns via a set of front solder balls; a set of rear solder balls electrically connected to the set of rear conductive patterns, respectively; wherein the set of front solder balls comprises one or more first-type solder balls and one or more second-type solder balls, and the set of rear solder balls comprises one or more first-type solder balls and one or more second-type solder balls; and wherein the first-type solder balls of the set of front solder balls are electrically coupled to the first-type solder balls of the set of rear solder balls.