Resin Flow Control in Electrical Equipment Sealing
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Solution Overview
Problem
The existing methods for resin sealing in electrical equipment face challenges in preventing air bubbles, especially when the chassis has a rectangular shape and the resin injection hole is centrally located, leading to uneven resin flow and attachment to the nozzle, which complicates the process and often results in air bubbles remaining, especially with high viscosity resins.
Innovation Solution
The implementation of a flow suppression portion in the chassis, comprising ribs and air bubble escape holes, which adjusts the resin flow timing and prevents air bubbles by delaying resin ejection and ensuring even filling without requiring new processes or special apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If resin injection hole is provided in central portion of printed circuit board, then resin can be injected into internal space, but resin springs out at different timing from different sides causing air bubbles to remain
Solution Approach 1:
The patent applies local quality by providing flow suppression portions at specific locations where resin flows first (long sides) rather than uniformly across all sides. These flow suppression portions create localized resistance to resin flow, delaying resin ejection timing at specific gaps to synchronize with other sides, thereby preventing air bubbles while maintaining central injection hole configuration
Solution Approach 2:
The flow suppression portions act as intermediaries between the resin injection hole and the gaps between chassis side portions and printed circuit board edges. They mediate the resin flow by providing controlled resistance, adjusting the timing of resin ejection to prevent air bubbles from being trapped
2Temperature
If resin with high viscosity is used to secure thermal conductivity, then heat radiation performance is improved, but air bubbles are more likely to remain in internal space
Solution Approach 1:
The flow suppression portions provide localized flow control specifically where high viscosity resin tends to pool and eject prematurely (long sides). By creating controlled resistance at these specific locations, the patent enables use of high viscosity resin with better thermal conductivity properties while preventing the air bubble formation that would otherwise occur with such viscous materials
3Productivity
If resin injection is continued after resin attaches to nozzle, then internal space filling is completed, but air bubbles remain and process becomes complicated
Solution Approach 1:
The flow suppression portions provide preliminary anti-action by preemptively controlling resin flow velocity and timing before resin can attach to the injection nozzle. By delaying resin ejection at flow suppression portions, the patent prevents the sequence of events that leads to nozzle attachment and subsequent air bubble formation, allowing complete filling without compromising reliability
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 solution effectively suppresses air bubble formation by synchronizing resin ejection through multiple gaps, preventing nozzle attachment and complete resin filling, while enhancing adhesive strength and structural integrity without additional processes or equipment.
Implementation Method 1
a flow suppression portion that decreases a drift velocity of the sealing resin pressed into the internal space through the resin injection hole
Data Source
AI summary
Electrical equipment 1 includes a chassis 2 that has a bottom portion 3 and side portions 4 and 5, a printed circuit board 10 that is stored in the chassis 2 such that one principal surface 10a faces an inner surface 3a of the portion 3, a sealing resin 20 that is filled in internal space S formed by the chassis 2 and the circuit board 10, embeds the circuit board 10, and a flow suppression portion 8 that decreases a drift velocity of the resin 20 pressed into the space S through the resin injection hole 11, and that is provided in at least part of region A from a position immediately below the hole 11 in the inner surface 3a to an inner surface 4a of a side portion 4 closest to the hole 11 out of the side portions 4 and 5.