Semiconductor Package Intermediate Layer for Pad Protection
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Solution Overview
Problem
Current semiconductor packaging technologies face challenges in ensuring reliable bonding and preventing damage to external pads due to exposure, leading to reduced reliability and increased risk of cracks and electric shorts.
Innovation Solution
A semiconductor package design featuring a fan-out structure with an intermediate layer containing a noble metal, such as aurum (Au), formed by electro-less plating, which covers the external pad and includes a solder external connection terminal with a different metal material, providing enhanced wettability and coverage to prevent exposure and damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the external pad is exposed for bonding, then bonding is enabled, but the external pad becomes vulnerable to damage and cracks
Solution Approach 1:
An intermediate layer comprising a noble metal (such as Au, Ag, or Pd) is introduced between the external pad and the external connection terminal. This intermediate layer acts as a mediator that enables bonding while protecting the external pad from direct exposure and damage. The intermediate layer has superior wettability and forms a reliable bonding interface without compromising the external pad's integrity.
Solution Approach 2:
The patent employs a composite structure where the intermediate layer is formed by combining a noble metal with other metal materials. This composite material provides both the wettability needed for bonding and the mechanical strength to protect the external pad, resolving the contradiction between bonding capability and pad integrity.
2Reliability
If the external connection terminal directly contacts the external pad, then electrical connection is established, but the risk of electric shorts increases
Solution Approach 1:
The intermediate layer of noble metal serves as an electrical mediator between the external pad and the external connection terminal. It maintains electrical conductivity while providing isolation that prevents direct contact between potentially incompatible materials, thereby reducing the risk of electric shorts while ensuring reliable electrical connection.
3Reliability
If the external pad is fully covered, then protection is enhanced, but bonding capability is reduced
Solution Approach 1:
The intermediate layer is selectively positioned and dimensioned to provide local protection where needed. It covers the external pad sufficiently to prevent damage and exposure, while its material properties (noble metal with superior wettability) ensure that bonding capability is maintained or even enhanced at the bonding interface.
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 solution improves the reliability of the semiconductor package by buffering external shocks, preventing cracks, and ensuring complete coverage of the external pad, thereby enhancing bonding and reducing the risk of electric shorts.
Implementation Method 1
the intermediate layer is formed by an electro-less plating method
Data Source
AI summary
A semiconductor package includes a semiconductor chip including a chip pad on a first surface thereof, an external pad electrically connected to the chip pad of the semiconductor chip, an external connection terminal covering the external pad, and an intermediate layer between the external pad and the external connection terminal, the intermediate layer including a third metal material that is different from a first metal material included in the external pad and a second metal material included in the external connection terminal.