Background
A smart window uses electrochromic technology to switch between clear and tinted states on demand to block sunlight and solar heat while still providing an unobstructed view of the outdoors.
Each smart window is connected to a a network of window controller which is powered by a control panel:
Previous generation window controller
Project Objective
To lower the cost/sq ft of Smart Windows, I worked on making the controls cheaper. The new generation smart window controller aims to power four windows at once, requiring it to be designed from the ground up to enclose the new PCBA that generates more heat.
New smart window controller
Design
Material
The housing is made of AL 6061 for the prototyping and initial prodoction run due to its availability and machinability. As we shifted and enabled die casting for production, the final material was ADC 6. Both alloys were chosen also due to their high thermal conductivity to dissipate heat generated from the PCBA.
Heat Transfer Features
Fins were added to the top of the housing to act as a heat sink. Thermal interface bosses were also created to reduce the gap between the hot components on the PCBA and thermal pads are inserted in between to facilitate heat transfer. Chamfers were also added to the bosses to increase cross sectional area for conductive heat transfer.
EMI Shield
A custom designed stamped sheet metal was used as an EMI shield to contain the radio frequency from the PCBA to stay compliant with FCC commercial and residential regulations.
Seal
An Urethane based resin is dispensed to the bottom of the assembly to seal the opening once it cures.
Custom silicone gasket and plastic retainer were designed and made to seal the connectors
Manufacturing Fixture
A custom manufacturing fixture was designed and fabricated to automate the resin dispensing process. It's a combination of a XY gantry with additional accessories connected to a resin dispenser:
A platform that is able to hold an assembled unit was installed to the XY gantry and I programmed it to move in an optimized path while having it synced with the dispense pressure and volume to ensure the resin covers the surface area and prevent material overflow/undershot
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