Semiconductor Substrate Protection Layer for Oxidation Prevention
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Solution Overview
Problem
The reliability of automotive electronic components is compromised due to oxidation of exposed metal layers in conventional substrate structures, which are prone to degradation during the pre-cut or half-etching process for forming wettable flanks.
Innovation Solution
A substrate structure is developed with a first passivation layer, a first circuit layer, and a first protection layer, where the outer lateral surface of the circuit layer is covered by the passivation or protection layer to prevent oxidation, comprising a solder wettable flank and depression structure, with a predetermined distance between the circuit layer and encapsulant to enhance reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pre-cut or half-etching process is performed to form wettable flank, then the wettable flank is exposed from encapsulant, but the metal layer becomes prone to oxidation and reliability degrades
Solution Approach 1:
A protection layer is introduced as an intermediary between the metal layer and the oxidizing environment. This protection layer covers the outer lateral surface of the circuit layer, preventing direct contact between oxygen and the metal layer, thus eliminating the oxidation problem while maintaining the wettable flank functionality.
Solution Approach 2:
The protection layer is formed in advance before the final packaging structure is completed. By applying the protection layer to the outer lateral surface of the circuit layer before exposure to the oxidizing environment, the metal layer is pre-protected from oxidation, ensuring long-term reliability.
2Reliability
If outer lateral surface of circuit layer is exposed to form wettable flank, then soldering is enabled, but oxidation occurs and joint quality deteriorates
Solution Approach 1:
The protection layer is selectively applied only to the outer lateral surface of the circuit layer that requires protection, while maintaining the wettable flank functionality at the bottom surface. This localized protection approach prevents oxidation on the lateral surface without interfering with the soldering process at the bonding interface.
3Reliability
If conventional substrate structure is used with exposed metal layer, then manufacturing is simpler, but oxidation-prone structure reduces reliability
Solution Approach 1:
The protection layer formation process is merged with the existing packaging工艺流程. By integrating the protection layer application into the standard manufacturing sequence (forming circuit layer, forming passivation layer, then forming protection layer on exposed surfaces), the additional complexity is minimized while achieving the reliability improvement.
Data Source
AI summary
A substrate structure, a semiconductor package structure including the same and a method for manufacturing the same are provided. The substrate structure includes a first passivation layer, a first circuit layer and a first protection layer. The first passivation layer has a first surface and a second surface opposite to the first surface. The first circuit layer has an outer lateral surface. A first portion of the first circuit layer is disposed in the first passivation layer. The first protection layer is disposed on a second portion of the first circuit layer and exposed from the first surface of the first passivation layer. The outer lateral surface of the first circuit layer is covered by the first passivation layer or the first protection layer.