Semiconductor Sealing Structure for Moisture-Resistant High-Voltage Switching
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Solution Overview
Problem
Semiconductor devices with high rating voltages fail to meet the H3TRB test for high temperature and high humidity conditions due to moisture ingress leading to dielectric breakdown and leak current, which reduces their withstand time.
Innovation Solution
A semiconductor device design incorporating a substrate, mounting layers, switching elements, a moisture-resistant layer, and a sealing resin, where the moisture-resistant layer covers the side surfaces of the switching elements and is in contact with the mounting layer, forming a barrier against moisture ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a semiconductor device uses high rating voltage, then the power handling capability is improved, but the withstand time under high temperature and high humidity conditions deteriorates due to moisture ingress causing dielectric breakdown
Solution Approach 1:
The sealing structure is divided into multiple layers: an outer sealing resin layer and an inner moisture-resistant layer. This segmentation allows each layer to perform its specific function - the sealing resin provides overall protection while the moisture-resistant layer specifically blocks moisture ingress, thereby protecting high voltage switching elements from dielectric breakdown in humid environments
Solution Approach 2:
A moisture-resistant layer is introduced as an intermediary barrier between the external humid environment and the internal switching elements. This intermediate layer prevents moisture from reaching the dielectric surfaces of high voltage switching elements, thereby maintaining their insulation performance and extending withstand time under H3TRB test conditions
2Reliability
If moisture enters the sealing resin, then the dielectric breakdown voltage deteriorates, but adding moisture protection increases device complexity
Solution Approach 1:
A thin film moisture-resistant layer is applied over the switching elements and sealing resin. This thin film structure provides effective moisture barrier protection without significantly increasing device volume or structural complexity, thereby maintaining dielectric breakdown voltage while adding minimal complexity to the device design
3Reliability
If the switching elements are covered with sealing resin, then the overall sealing is improved, but moisture can still ingress through the sealing resin under high humidity conditions
Solution Approach 1:
The sealing system uses a composite structure combining sealing resin and moisture-resistant layer. The sealing resin provides mechanical protection and basic sealing, while the moisture-resistant layer (made of materials with low moisture permeability) provides specialized moisture barrier functionality. This composite approach addresses both general sealing requirements and specific moisture resistance needs
Data Source
AI summary
The present disclosure provides a semiconductor device. The semiconductor device includes a substrate, a mounting layer, switching elements, a moisture-resistant layer and a sealing resin. The substrate has a front surface facing in a thickness direction. The mounting layer is electrically conductive and disposed on the front surface. Each switching element includes an element front surface facing in the same direction in which the front surface faces along the thickness direction, a back surface facing in the opposite direction of the element front surface, and a side surface connected to the element front surface and the back surface. The switching elements are electrically bonded to the mounting layer with their back surfaces facing the front surface. The moisture-resistant layer covers at least one side surface. The sealing resin covers the switching elements and the moisture-resistant layer. The moisture-resistant layer is held in contact with the mounting layer and the side surface so as to be spanned between the mounting layer and the side surface in the thickness direction.