Jaman42:
Is this true with solid electrolytes as well?
Tantalum capacitors are considered solid enough to replace electrolytics in spacecraft but not sure how they would fare at high pressure.
Their construction is normally sintered ( has voids ) and what is called a solid manganese dioxide cathode.
That may not be a solid at high pressure as its basically a pressed powder.
Thinking on if the ic is not liquid filled you would have a problem there, im fairly sure ther is a void where the chip is bonded to the package
Boardburner2:
Thinking on if the IC is not liquid filled you would have a problem there, I'm fairly sure there is a void where the chip is bonded to the package
That's what I was commenting on earlier.
That said, I figure that one atmosphere is 14 psi, so 100 atmospheres is (3000 feet) 1,400 psi but the die and void size is of the order of a tenth of an inch, so one hundredth of a square inch would see 14 pounds pressure. Visualising this, it seems that it may or may not fail under that pressure, uniformly applied. The DIP package would clearly be more rugged in this regard, than the SMD.
If the housing is oil filled and pressure neutral, then a good thermal heat sink could be built into the sides of the housing. Interesting is the notion of making an inexpensive pressure vessel to test the components.
High pressures and cheap can easily result in explosions.
The test rig would be completely filled with fluid with no significant amount of trapped gas. If there were to be a failure it would be just a quick squirt of liquid. That is the way hydrostatic testing is done.
zoomkat:
The test rig would be completely filled with fluid with no significant amount of trapped gas. If there were to be a failure it would be just a quick squirt of liquid. That is the way hydrostatic testing is done.
Apples vs. oranges. Heating the water adds tremendous amounts of energy to the water, raising its temperature/pressure. If the water heater tank has any voids that are filled with high pressure steam, even more energy is trapped. When the tank fails, the hot water flashes to steam, and the steam goes thru an expansion energy transfer to its surroundings (think steam engine piston). In hydrostatic testing very little energy is transferred into the test setup, mostly being the forced expansion of the pressure containment parts (or test parts with compressible voids).
Jaman42:
It's also a matter of hull penetrations, they are quite pricey so I would prefer making my own. Making those to withstand really high pressure seems to be quite difficult (now I am thinking ahead, deep, deep).
I have been thinking about that and I think my earlier idea applies.
Main tether connector will require a proper one but for unit to unit everything at same depth.
So a simple gland to keep the oil in as there is no differential pressure to contend with ??
The underwater electronics I have worked with were not oil filled. Vessels were sealed and heavy metal to prevent crushing. I would be looking for a container that prevents the crushing under the needed pressures and then put the electronics within that. Air pressure wouldn't be going up that much.
I have worked with underwater sensors in the Arctic ocean and underwater camera housings for medium depths.
Another way of testing housings is to put a vacuum into the vessel. If it crushes, then there is an issue.
zoomkat:
The test rig would be completely filled with fluid with no significant amount of trapped gas. If there were to be a failure it would be just a quick squirt of liquid. That is the way hydrostatic testing is done.
I've seen high pressure hydraulic fluid cause amputations when it came out of a pin hole. Think water jet cutter, but in a random direction.
Boardburner2:
Are you proposing to use flooded motors as well ?
I'm going for a brushless motor setup, if I don't pott my own I will probably buy bluerobotics T100 thrusters. They even have a upcoming version with integrated ESC in the thruster to eliminate any heat issues
