Wire Coating Nozzle With Spiral Transport Wind for Full Circumference Coverage
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Solution Overview
Problem
Conventional methods for manufacturing semiconductor devices face challenges in forming a primary layer on the outer periphery of wires, leading to weakened bonding strength and potential peeling of the sealant due to insufficient application of the coating liquid, especially on the back surface of the wires.
Innovation Solution
A method using a nozzle with a transport wind generating function to supply a coating liquid spirally along a liquid transport wind, ensuring the silane coupling agent is accurately applied to the entire outer periphery of the wires, including the back surface, followed by a drying process to form a primary layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a spinner or sprayer is used to apply coating liquid after the semiconductor element is attached to the case, then the coating process can be performed, but a liquid pool is generated on the inner wall of the case causing insufficient reaction in the film thickness region
Solution Approach 1:
The patent applies the coating liquid to the wire surface before the wire is bonded to the semiconductor element. This preliminary application ensures that the primary layer is formed on the wire surface prior to bonding, avoiding the liquid pool problem that occurs when coating is performed after assembly. The coating liquid is applied to the wire in a state where it can be uniformly distributed without forming pools.
Solution Approach 2:
Instead of the conventional approach of coating after assembly (which causes liquid pooling), the patent inverts the sequence by coating the wire before assembly. This reversal of the process sequence eliminates the harmful liquid pool formation while ensuring complete coverage of the wire surface including the back surface that will be bonded.
2Ease of manufacture
If droplets of coating liquid are applied from above by the atomizer, then the coating process is simplified, but the coating liquid is less likely to be applied to the back surface of the wire causing no primary layer formation
Solution Approach 1:
The patent introduces a transport wind that blows the coating liquid from the front surface of the wire to the back surface, adding a horizontal dimension to the coating process. Instead of relying solely on vertical droplet application from above, the transport wind carries the coating liquid along the wire surface, ensuring coverage of the back surface that would otherwise be inaccessible.
Solution Approach 2:
The transport wind acts as an intermediary that transports the coating liquid from the application point to the back surface of the wire. This intermediary mechanism (the wind flow) enables the coating liquid to reach areas that would be difficult to access with direct droplet application, ensuring complete coverage without complicating the overall process.
3Manufacturing precision
If a pre-coating process is used before the semiconductor element is attached to the case, then the coating liquid can be applied, but it affects adhesion between the case and substrate and strength of the wire bonded to the semiconductor element
Solution Approach 1:
The patent applies the coating liquid locally to specific surfaces that require primary layer formation (the wire surface and selected areas of the substrate), rather than coating all surfaces. This localized application ensures that primary layers are formed only where needed for sealing adhesion, while bonding surfaces maintain their original properties for optimal bonding strength.
Solution Approach 2:
The patent carefully controls the parameters of coating liquid application, including the timing, amount, and distribution of the coating liquid. By adjusting these parameters, the primary layer is formed with appropriate thickness and properties that do not interfere with subsequent bonding processes, while still providing the necessary adhesion enhancement for the sealant.
4Ease of manufacture
If coating liquid is scattered in a mist form, then the coating process can be performed, but the coating liquid is less likely to be uniformly applied over the entire outer periphery of the wire and may be applied to prohibited regions
Solution Approach 1:
The patent replaces the mechanical scattering method (mist form application) with a wind-based transport system. Instead of relying on mechanical scattering that produces unpredictable mist distribution, the coating liquid is applied and then transported by a controlled wind flow, providing more precise and uniform coverage of the wire outer periphery without overspray to prohibited regions.
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 method enables a reliable primary layer formation on the entire circumference of the wires, maintaining strong bonding strength with the sealant and preventing peeling during thermal stress, thus enhancing the semiconductor device's durability.
Implementation Method 1
The coating liquid contains a silane coupling agent... forming a primary layer on the outer periphery of the wire... maintaining strong bonding strength with the sealant
Implementation Method 2
supplying the coating liquid from the coating liquid supply port along a flow of a liquid transport wind that spirally swirls downward
Implementation Method 3
drying the coating target structure after the step (b) is performed
Data Source
AI summary
A coating process of a coating liquid using a nozzle is performed on a coating target structure including a semiconductor element and a wire bonded to the semiconductor element by a wire bonding process. The nozzle has a transport wind generating function of generating a liquid transport wind in a spiral manner. Thus, the coating liquid discharged from the coating liquid supply port of the nozzle is supplied to the coating target structure along the directivity of the liquid transport wind. Then, a drying process is performed on the coating target structure to form a primary layer containing a silane coupling agent as a constituent material on an outer periphery of the wire.