Semiconductor Device Solder Reflow Control via Plating Oxide Barrier
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Solution Overview
Problem
In semiconductor devices, the reflow process during soldering can cause solder to flow out and lead to uneven thickness and short-circuit failures due to the use of copper conductive layers, resulting in inclined semiconductor chips and poor connections.
Innovation Solution
A semiconductor device configuration that includes a substrate with a conductive layer and a plating layer with an oxide film, where a solder layer is bonded to the plating layer, preventing solder outflow during reflow by forming a strong adhesion between the solder and the plating layer, thus maintaining even thickness and preventing short-circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a copper conductive layer is used for soldering, then good electrical conductivity is achieved, but solder flows out during reflow process causing short-circuit failures
Solution Approach 1:
A plating layer (nickel or palladium) is introduced as an intermediary between the copper conductive layer and the solder layer. This plating layer forms an oxide film that acts as a barrier to prevent solder from directly contacting and flowing along the copper conductive layer, while still allowing for reliable solder bonding.
Solution Approach 2:
The conductive structure is transformed from a single copper layer to a composite multi-layer structure consisting of copper conductive layer + plating layer (nickel/palladium) + oxide film. This composite structure combines the electrical conductivity of copper with the solder-resistance properties of the plating layer and oxide film.
2Strength
If solder is heated during reflow process, then bonding is achieved, but solder thickness becomes uneven and chips become inclined
Solution Approach 1:
The oxide film on the plating layer serves as a mediator that controls solder wetting and spreading behavior. It allows the solder to bond effectively to the underlying copper through the plating layer while preventing uncontrolled lateral flow, thereby maintaining uniform solder thickness during the reflow process.
Solution Approach 2:
The surface properties of the plating layer are changed by forming an oxide film, which modifies the wettability and adhesion characteristics. This parameter change enables the solder to maintain its shape better during heating while still achieving strong bonding, thus improving thickness uniformity.
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 effectively suppresses solder outflow and maintains even solder thickness, preventing semiconductor chip inclination and ensuring reliable connections, thereby enhancing the performance and reliability of semiconductor devices.
Implementation Method 1
a first plating layer which is provided on the first conductive layer and on which an oxide film is formed
Implementation Method 2
forming a strong adhesion between the solder and the plating layer
Data Source
AI summary
A semiconductor device includes: a substrate including a main surface; a wiring portion including a first conductive layer formed on the main surface, and a first plating layer which is provided on the first conductive layer and on which an oxide film is formed; a semiconductor element including an element mounting surface and an element electrode formed on the element mounting surface; a bonding portion including a second plating layer made of the same material as the first plating layer and laminated on the first conductive layer, and a solder layer laminated on the second plating layer and bonded to the element electrode; and a sealing resin covering the semiconductor element.