Insulative Coating for Semiconductor Packages Exposed to Moisture and Arcing
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Solution Overview
Problem
Semiconductor packages with plastic housings are prone to moisture ingress, corrosion of conductive terminals, and arcing issues due to their porosity and susceptibility to environmental factors, leading to potential device failure, especially in high-voltage applications.
Innovation Solution
A coated semiconductor device is developed with a mold compound housing and a conductive terminal, where an insulative coat, such as a polymer or ceramic, covers the housing and at least a portion of the terminal, sealing pores, preventing moisture ingress, corrosion, and arcing, while maintaining the benefits of the underlying mold compound.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an insulative coat is applied to cover the mold compound housing and conductive terminal, then protection against moisture ingress and corrosion is improved, but the device complexity increases
Solution Approach 1:
An insulative coat is applied as an intermediary layer between the mold compound housing/conductive terminal and the external environment. This coat acts as a mediator that prevents direct contact between moisture/corrosive elements and the underlying structures, thereby improving reliability without fundamentally changing the device architecture.
Solution Approach 2:
The solution employs composite material construction by combining the mold compound housing, conductive terminal, and insulative coat into a multi-material system. The insulative coat material is selected to provide both electrical insulation and environmental protection properties, creating a composite structure that addresses multiple protection requirements simultaneously.
2Reliability
If an insulative coat is applied to seal pores and prevent moisture ingress, then reliability is improved, but the manufacturing process complexity increases
Solution Approach 1:
The insulative coat is applied in advance to seal the pores of the mold compound housing before the device is put into service. This preliminary action prevents moisture ingress from occurring in the first place, eliminating the need for subsequent repair or maintenance actions and simplifying the overall manufacturing process by addressing the protection requirement upfront.
Solution Approach 2:
The harmful porosity of the mold compound housing is effectively removed or neutralized by applying the insulative coat that seals the pores. This extracts the vulnerability from the system, allowing the mold compound to retain its beneficial properties while eliminating its detrimental porous characteristic.
3Reliability
If an insulative coat covers the conductive terminal, then protection against arcing is improved, but the tracking index performance may be affected
Solution Approach 1:
The insulative coat is applied selectively to specific areas where arcing protection is most critical, such as on the conductive terminal surfaces and high-stress regions. This local application maintains the tracking index performance in areas where electrical performance is paramount while providing enhanced arcing protection where needed most.
Solution Approach 2:
The insulative coat material is selected and formulated with specific physical and electrical parameters optimized for both arcing resistance and tracking index performance. By carefully controlling the coat's thickness, composition, and curing parameters, the system achieves improved arcing protection while maintaining acceptable tracking index characteristics.
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 insulative coat effectively seals the semiconductor package, reducing the risk of moisture damage, corrosion, and arcing without increasing package size, and can be designed to maintain high tracking indices, thus enhancing the reliability and performance of semiconductor devices.
Implementation Method 1
The insulative coat seals pores on a surface of the mold compound housing, preventing ingress of moisture into the mold compound housing
Implementation Method 2
an insulative coat, such as a polymer or ceramic, covers the housing and at least a portion of the terminal
Implementation Method 3
the insulative coat seals the interface at which the conductive terminal exits the mold compound housing. The insulative coat may extend to cover portions of adjacent conductive terminals, thereby increasing the creepage distance between the conductive terminals
Implementation Method 4
The coat material is then cured to form the coat
Data Source
AI summary
In examples, a semiconductor device comprises a semiconductor die, an opaque mold compound housing covering the semiconductor die, a conductive terminal extending from the mold compound housing, and an insulative coat covering the mold compound housing and at least a portion of the conductive terminal.