Resin Sealing Interface Gap Prevention in Circuit Devices
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Solution Overview
Problem
Existing resin-sealing methods for circuit elements often result in voids due to incomplete filling, and thermal curing of different resin materials can lead to gaps and reduced moisture resistance and withstand voltage at the interface between the resin sheet and molding resin.
Innovation Solution
A method involving the use of a first sealing resin injected into a cavity and a second sealing resin formed from a melted resin sheet, where the second resin is allowed to cure after the injection of the first resin, ensuring integration and preventing voids and interface issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the gap between the bottom surface of the island and the lower mold half is set narrow to achieve thin resin sealing, then heat dissipation performance is improved, but the sealing resin cannot be fully filled in the gap causing voids
Solution Approach 1:
A resin sheet is placed on the bottom surface of the lower mold half before the resin sealing process. This preliminary placement ensures that when the sealing resin is injected, the resin sheet is already positioned to fill narrow gaps and prevent void formation, thereby enabling thin resin sealing with complete filling even in challenging geometries
Solution Approach 2:
The resin sheet acts as an intermediary material between the lower mold half and the sealing resin. It facilitates complete resin filling in narrow gaps by providing a base layer that the sealing resin can bond to, eliminating voids while maintaining the thin profile needed for heat dissipation
2Stability of the object's composition
If the resin sheet is thermally cured before the molding resin is injected, then the resin sheet structure is stabilized, but gaps form at the interface reducing moisture resistance and withstand voltage
Solution Approach 1:
The curing process is divided into periodic stages: first, the resin sheet is partially cured to achieve initial structural stability; then, the molding resin is injected while the resin sheet is still somewhat pliable, allowing intimate contact and bonding; finally, the entire assembly is fully cured. This periodic curing approach prevents interface gaps while achieving both structural stability and reliability
Solution Approach 2:
The resin sheet is preliminarily cured to a state that provides structural stability but retains enough flexibility to bond with the molding resin. This preliminary curing state allows the resin sheet to maintain its shape while still forming a gap-free interface with the injected molding resin, ensuring both stability and moisture resistance
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
This approach ensures complete resin filling, enhances moisture resistance and withstand voltage by preventing gaps between the resins, and improves heat dissipation through controlled thermal curing.
Implementation Method 1
The above-mentioned mold has been heated, and thus, the tablet 228 housed in the pod 220 is gradually melted into a sealing resin in liquid form
Implementation Method 2
the sealing resin in liquid form pressurized by a plunger 222 is fed to the cavity 214 via the runner 218 and a gate 216
Implementation Method 3
melting the compressed sheet into a second sealing resin
Implementation Method 4
the second sealing resin formed of the molten compressed sheet is caused to cure after the injection of the first sealing resin into the cavity
Data Source
AI summary
Provided is a method of manufacturing a circuit device in which a circuit element is resin-sealed with sealing resins formed integrally with each other. In the present invention, a resin sheet and a circuit board are housed in a cavity of a mold, and thereafter a first sealing resin formed of a tablet in melted form is injected into the cavity. At the time of injecting the first sealing resin, a second sealing resin formed of the resin sheet in melted form is not yet cured and is maintained in liquid form. Accordingly, the injected first sealing resin and the second sealing resin are mixed at the boundary therebetween, preventing the generation of a gap in the boundary portion and therefore preventing the deterioration of the moisture resistance and withstand voltage at the boundary portion.