I'm looking for a removable SMD power connector with minimum footprint to connect Li-ion batteries, and the best candidate I've found at the moment is Panasonic R35K series, which has tiny 2.24x1.3mm footprint and provide robust connection but conveniently removable at the same time. The only problem I've found on the datasheet is, its "Lifetime characteristics - Insertion and removal life" is only 10 times. My question is, does this indeed mean that it might get broken after around 10 cycles of insertion/removal on average? Is this connector not supposed/allowed to be inserted/removed for multiple (at least hundreds of) times? If that is the case, would there be any alternative battery connector with similar characteristics but better durability?
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1\$\begingroup\$ What's a "power connector" to you, in terms of current? And what's the maximum size (xyz dimensions) that you can tolerate? \$\endgroup\$– LundinCommented Aug 15 at 11:22
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1\$\begingroup\$ @Lundin Thanks for the response. By power connector I mean a board-to-board connector that is designed to be conveniently and constantly removable. ~5V, ~100mA, ~4x3mm, 300~ mating cycles, 2~ signals (just pwr and gnd). \$\endgroup\$– K JCommented Aug 15 at 12:13
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\$\begingroup\$ I like to use 2mm pitch "bottom entry" sockets/headers. They have very low mated height but are much more rugged than "mezzanine" connectors. Gold plated is probably a good idea in this case. \$\endgroup\$– LundinCommented Aug 15 at 12:31
3 Answers
does this indeed mean that it might get broken after around 10 cycles of insertion/removal on average?
It means that the manufacturer guarantees the contact resistance specification ("Max. 30 mΩ ( power terminal )") only if the connectors are mated up to 10 times.
Every time the connectors are mated, part of the contact plating is scraped off. The manufacturer guarantees that 10 mating cycles will not remove all the plating.
When the plating is removed and contact is through the base metal, the contact resistance increases, especially as time goes by and oxidation sets in.
My question is, does this indeed mean that it might get broken after around 10 cycles of insertion/removal on average?
Yes. Or at least the manufacturer is not making any guarantees beyond 10 cycles.
Is this connector not supposed/allowed to be inserted/removed for multiple (at least hundreds of) times?
No. These are typically meant just connected once during production and then maybe a few times more during repairs. Typical applications would be consumer electronics like phones.
If that is the case, would there be any alternative battery connector with similar characteristics but better durability?
A proper specification is required for that. Number of signals, currents, measurements, intended environment, number of connector cycles. Etc etc.
Just like anything in a datasheet, it just says that beyond that point all bets are off.
Perhaps one of the metrics from the datasheet reliably goes out of spec at the 11th mating (indicating the manufacturer really knows what they're doing and have optimised wear surfaces for cost), perhaps the manufacturer only bothered to qualify for 10 times (because their market doesn't care about more) and has in fact a lot more capability.
You could buy a couple and do your own qualification, with your own criterias and procedure, if you wanted. That's what the NewSpace trend does for example with industrial components that are not hardened before making their way to space.
It may sound silly to have only 10 matings, but it's plenty when you use what is called a connector saver which role is to be connected once to your equipment, and then take most of the necessary connections from its rear end before being replaced by the real deal.
