Lead Electrode Bonding Structure for Visible Bond Layer Inspection
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Solution Overview
Problem
Conventional semiconductor devices with directly bonded lead electrodes and semiconductor elements face challenges in visually verifying the thickness of the bonding layer, which is crucial for preventing peeling due to thermal expansion differences.
Innovation Solution
A semiconductor device structure featuring a lead electrode with a cantilevered plate embedded in the bonding layer, allowing visual inspection to determine if the bonding layer has a predetermined thickness, thereby ensuring adequate coverage and preventing peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bonding layer is formed between the lead electrode and semiconductor element, then peeling is prevented through adequate thickness, but visual inspection of the bonding layer thickness becomes difficult
Solution Approach 1:
A transparent or translucent adhesive layer is introduced as an intermediary between the lead electrode and semiconductor element. This adhesive layer serves dual purposes: it provides adequate bonding thickness to prevent peeling, and its transparency enables visual inspection of the bonding interface and thickness without requiring complex non-destructive testing equipment.
Solution Approach 2:
The patent utilizes the optical properties (transparency/translucency) of the adhesive layer to enable visual detection. By selecting materials with appropriate optical characteristics, the bonding layer thickness and quality become visually detectable, transforming an otherwise invisible parameter into an observable one for quality control purposes.
2Measurement precision
If non-destructive inspection methods are used to verify bonding layer thickness, then measurement precision is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The adhesive layer is designed to be self-inspectable through its transparent or translucent property. The bonding layer itself provides the means for its own quality verification, eliminating the need for separate, complex non-destructive inspection equipment. Quality control becomes a simple visual check that can be performed during or after assembly without additional measurement devices.
Data Source
AI summary
Provided is a semiconductor device having a structure of directly bonding a lead electrode to a semiconductor element through a bonding layer, in which whether the bonding layer has a predetermined thickness can be checked through a visual inspection. The semiconductor device includes: a semiconductor element mounted on an insulating substrate or a lead frame; a bonding layer on the semiconductor element; and a lead electrode including a main body plate electrically connected to an external electrode, and a cantilevered plate having one end being connected to the main body plate as a connection part, and being cut from the main body plate, wherein the cantilevered plate is bent in a direction of the semiconductor element with respect to the main body plate, and has an other end embedded in the bonding layer, and the bonding layer covers at least a part of an upper surface of the cantilevered plate.