Sealing a lighting fixture with dry gas
An underwater light fixture and a method for making the underwater light fixture are provided. The method includes assembling a light fixture in a housing, leaving a fastener out of the light fixture, wherein an opening for the fastener fluidically couples to open volume in the housing. The housing is placed in a vacuum chamber, and a vacuum is pulled on the vacuum chamber to remove air from the open volume of the housing. A dry gas is introduced into the vacuum chamber to fill the open volume in the housing, and the fastener is installed in the light fixture to seal the open volume.
1 . A method for making an underwater light fixture, the method comprising:
assembling a light fixture within a housing, leaving a fastener out of the light fixture, wherein an opening for the fastener fluidically couples to an open volume in the housing;
placing the housing in a vacuum chamber;
pulling a vacuum on the vacuum chamber to remove air from the open volume of the housing;
introducing a dry gas into the vacuum chamber to fill the open volume in the housing;
installing the fastener in the light fixture to seal the open volume; and
sealing the housing with the fastener in the light fixture within the housing.
2 . The method of claim 1 , comprising cycling between pulling the vacuum and introducing the dry gas for at least two iterations before installing the fastener.
3 . The method of claim 1 , comprising performing the assembly in a clean room.
4 . The method of claim 3 , comprising maintaining a temperature between about 22° C. and about 28° C. during the assembly of the light fixture.
5 . The method of claim 3 , comprising maintaining a relative humidity between about 30% and about 40% during the assembly of the light fixture.
6 . The method of claim 1 , wherein assembling the light fixture in the housing comprises:
attaching a thermal pad to a back of a lighting circuit board;
mounting the lighting circuit board in the housing with lighting elements mounting on the lighting circuit board facing an opening in the housing;
sealing a clear plate to the housing over the lighting circuit board; and
mounting a control circuit board to the back of the lighting circuit board.
7 . The method of claim 6 , comprising mounting a lens plate over the lighting circuit board before sealing the clear plate to the housing.
8 . The method of claim 6 , comprising heating the lighting circuit board to about 80° C. for about 30 minutes to volatilize organic compounds before attaching the thermal pad.
9 . The method of claim 6 , comprising soldering a cable to the control circuit board.
10 . The method of claim 6 , comprising disposing a layer of potting compound over the control circuit board.
11 . The method of claim 10 , wherein the layer of potting compound seals the underwater light fixture.
12 . The method of claim 10 , wherein the layer of potting compound seals the underwater light fixture.
13 . The method of claim 12 , wherein installing the fastener comprises inserting the screw into a mounting hole.
14 . The method of claim 10 , mounting a back plate to the housing over the layer of potting compound.
15 . The method of claim 6 , wherein installing the fastener mounts the control circuit board to the lighting circuit board.
16 . The method of claim 6 , wherein installing the fastener mounts the control circuit board to the lighting circuit board.
17 . The method of claim 1 , wherein the fastener is a screw.