keeping electronics without silica and without a vacuum is very difficult because they will corrode by oxygen and moisture?
I guess you didn't read the second half of post #7 where I said...
If you are so intent on preserving data and electronics store them in a airtight vault and pump if full of argon gas and use archival CDs and archival paper, that should preserve everything for a few decades at least...might be a tad expensive doing this though. Me I'd just copy the data to whenever new medium comes out and get another 10 years or more.
This will preserve your cartridges for an indefinite period of time as Argon is an inert gas and won't react to anything inside the chamber.
Why do you think solder, gold plated leads, tinned leads, or other board mounted metallic connections on a board will corrode? I've had 25+ year old computers just sitting on the floor in my house that still boot fine, all you want to do before using it is make sure there isn't too much dust, bugs, rats, mice, etc inside of it or anything metal inside that might short something. All of my old computers have some surface contamination of the solder (primarily dust and cooking grease that gets in the air) but solder doesn't "rust" like a hunk of iron or steel. The only times I've seen bad corrosion inside a piece of electronics is when the item was damaged by something that leaves a
corrosive residue. Things like batteries that end up leaking into your remote control, calculator, gameboy etc.
Letting an electronic device drop in water is bad as there are always tons of non-H2O stuff in water some of which can cause corrosion. Pure H2O (like distilled water) isn't all that corrosive for electronics. Condensation is how they make distilled water so if condensation occurs on the internal electronics of a device it's pure H2O only if there is already something that can dissolve into water and become corrosive will that become a problem. AFAIK the current crop of no-clean solder flux resins don't become corrosive and actually leave a film on all the solder surfaces from the boards I've seen produced. Older devices would have had the flux residue cleaned in some sort of spray/rinse process post reflow/wave-solder. If the cleaning wasn't performed properly then there is a potential for corrosion to occur with more acidic solder fluxes. I've seen in the past boards that QA detected prior to being shipped that had the start of corrosion due to lack of cleaning on the board where flux was left (months after the board was manufactured).
So if you are trying to preserve your game cartridges as pristine till you can make a fortune on them. I'd say good luck with that. You may end up paying more than they end up being worth trying to "preserve" them. I'd say it would be cheaper to remove any batteries and toss all the cartridges and the nintendo into the bottom of your sock drawer for the next 20+ years and when you pull it out it will more than likely still work fine. Most of the working stuff that you see on ebay that collectors pay a premium for was just thrown in a drawer or sat in someone's closet for 20+ years when it was found to be worth something. The key thing was the item was stored without any batteries in it. HP calculators are a perfect example of this. The ones you see that don't work for sale usually have had batteries that leaked into the calculator, those that are sold as working like new have no corrosion inside because they got stored without batteries installed.