Metal Core Solder Ball Heat Dissipation Structure
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Solution Overview
Problem
Conventional semiconductor devices lack effective heat dissipation structures that can efficiently transfer heat from the device to the substrate without affecting the electronic elements or the heat conductivity of solder balls, which are crucial for maintaining high bonding reliability and heat management in high-density circuit chips.
Innovation Solution
A metal core solder ball with a specific composition and structure, comprising a metal core, a nickel-based first plating layer, and a tin-based second plating layer, is used to connect semiconductor devices to substrates, ensuring high heat conductivity and bonding reliability by optimizing the volume ratios and materials of the layers to satisfy the condition aA+bB+cC < ⅔a, where a, b, and c represent the heat conductivities of the metal core and plating layers, and A, B, and C are their respective volume ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional solder ball is used to connect semiconductor device and substrate, then bonding reliability is maintained through melting at reflow temperature, but heat dissipation capability is insufficient and heat conductivity is low
Solution Approach 1:
The patent employs a composite structure consisting of a metal core (high heat conductivity material such as copper or aluminum) surrounded by a solder shell (tin-based alloy). This composite design combines the high heat conductivity of the metal core with the bonding capabilities of the solder material, achieving both improved heat dissipation and reliable bonding. The metal core acts as a heat dissipation pathway while the solder shell provides bonding functionality.
Solution Approach 2:
The solder ball is segmented into distinct functional layers: an inner metal core dedicated to heat dissipation and conduction, and an outer solder shell dedicated to bonding. This segmentation allows each component to optimize its specific function - the metal core maximizes heat conductivity while the solder shell ensures reliable mechanical and electrical bonding to both the semiconductor device and substrate.
2Temperature
If heat is emitted toward the substrate including electronic elements, then heat dissipation from semiconductor device is improved, but it may affect the electronic elements or heat conductivity of the solder ball
Solution Approach 1:
The metal core acts as an intermediary heat conduction pathway that provides a dedicated thermal management route. By routing heat through the high-conductivity metal core, the system efficiently dissipates heat away from the semiconductor device without requiring direct thermal coupling to the substrate that could affect sensitive electronic elements. The TIM (thermal interface material) also serves as an intermediary between the heat sink and semiconductor device, optimizing heat transfer while protecting components.
Solution Approach 2:
The patent applies different material properties to different regions of the connection structure. The metal core provides high heat conductivity in the radial direction for efficient heat dissipation, while the solder shell provides appropriate thermal and mechanical properties at the bonding interfaces. The TIM is applied locally at the semiconductor device interface to optimize heat transfer without affecting other parts of the system.
3Loss of energy
If metal core solder ball with optimized structure is used, then heat conductivity is enhanced by at least five times, but manufacturing complexity increases due to multi-layer plating process
Solution Approach 1:
The manufacturing process utilizes self-service mechanisms where the electroless plating process automatically deposits the first plating layer (nickel or nickel alloy) uniformly on the metal core surface through chemical reduction reactions. The electroplating process then automatically deposits the second plating layer (tin-based alloy) uniformly on the first plating layer through electrochemical reactions. These self-regulating processes reduce the need for complex manual control and intervention, making the multi-layer structure manufacturable despite its complexity.
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 metal core solder ball enhances heat conductivity by at least five times compared to traditional solder balls, ensuring reliable electrical and thermal connections while preventing Kirkendall voids and maintaining structural integrity under thermal stress.
Implementation Method 1
a metal core solder ball comprising an inner core made of metal and a solder layer formed thereon... high heat conductivity between a semiconductor device and a substrate
Implementation Method 2
the first plating layer is preferably formed by subjecting nickel (Ni) or a Ni alloy to electroless plating
Implementation Method 3
the second plating layer is preferably formed by electroplating a tin (Sn) alloy
Data Source
AI summary
Disclosed is a metal core solder ball having improved heat conductivity, including a metal core having a diameter of 40˜600 μm, a first plating layer formed on the outer surface of the metal core, and a second plating layer formed on the outer surface of the first plating layer.