I'm thinking of using a standard mSATA / PCIe card-edge connector in a miniature pocket-sized project. Its small 30mm width, with 52-contacts at 0.8mm, is good. The typical 50 max-uses spec is a bit troubling, but we may not need more uses than that. Inserted PCBs swing down into place. Its low price and reliability reputation are good. Does anybody have some advice to offer? I'm not yet under an NDA on this project, but maybe ...
A typical p/n is Molex 67910-0002, although that one only allows for 1mm = 40mils of space under. We do need to use both sides of our PCB, but the attached PCB won't have any parts on its bottom.
Is there a reason why you need such a fine pitch connector? I suppose you can manage the mechanical issues, but an older spec with larger pin spacing and tolerance will likely give you more room to manage the mechanical issu es. It sounds like some sort of automated something if the boards are not inserted by hand and "swing" down into the connectors.
I seem to recall the now ancient ISA connector was very durable and had ver y generous tolerances.
Why a card edge connector rather than a two piece connector? They can be b ought with guide pins to prevent mangling. Or is the "swing" insertion som ething other than automated?
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Winfield Hill wrote in news:r65l47030l1 @drn.newsguy.com:
Is the plan to utilize it for multiple insertions/releases?
I mean it is low stress on the pins because of the method by which it works, which is a good thing for insertion count MTBF.
So, if you are incorporating it because it and the art is available, it sounds like a good choice. Insertion is easy and single screw lockdown insures high connection reliability over long time periods, just like when it gets used on a storage device as the connection to a computer. You said pocket device though, so short of carrying a computer in your pocket... weird visions come to mind... Could be a drive duplicator with quick external 'hot bay' for putting drives in and out. Anyway. permanent install or not, it is a good coice for your pin count need and size and part availablity. Sounds great to me.
Like we used cheap cat6 wire for proprietary module to module interrack communications links at one place I was at.
I would not gang them width wise though and try to double up on pin count on a bigger board kind of thing. The clamping pressure increases and alignment precision has to be there...
We have used a bunch of these in the past - Mouser 694-498-0090 They stand taller. There is no issue with placement for most components under the daughter card. You can also hand solder them if needed.
I think these are rated at 100 cycles for a given contact resistance. We never went anywhere near 100 cycles in the field but I know in the lab we went well over that number with no issues.
There is a mating spring latch we used but our units where not in a rough and tumble environment either.
The 30mm width is critical, it's fitting where a 32mm 20-pin card-edge connector goes now. The cards will be inserted by hand, usually by professionals. My experience with using mSATA cards in computers, is that with a good connector, and a PCB that carefully follows the spec details, it's hard to get it wrong.
We need more pins. Since I started considering a 0.5mm pitch, 0.8mm seems huge! Most connectors are one fixed piece, but some have a swinging portion.
We need to use card edge, because it's best if the cards can be assembled without any soldering; they will have considerable other lithographic treatments.
That motto's a subset, a specialized case of the super-motto "connectors don't connect." Soldered connections give me the best luck. IIRC, either in his book or in here, Win ranked bad connections near the top as a source of failure. That certainly mirrors my own modest experience. OTOH, the card connectors that you enumerate almost always connect without a problem for me. Memory modules are handled a lot more by me and they are probably more reliable.
Don Kuenz KB7RPU
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Roger that comment with the exception of large parts (e.g. DC/DC converter bricks) through hole soldered to a multi-layer board. The solder tends to crack due to mechanical stress/less than perfect soldering.
Note that while I have found card edge connectors to be problematic, I have had good success with all pin & socket type connectors (once connected - bent pins don't count!)
The suggested Digi mSATA version provides 4.4mm of space below the PCB, compared to 3.9mm with our present 20-pin connector. And it'll use up only about half the PCB space. Nice!
One issue, standard mSATA and PCIe devices use a 1.0mm thick PCB, compared to the usual 62-mil 1.57mm-thick PCB. We can probably change to 1.0mm, but it also appears these connectors won't mind a thicker PCB. Comments about that?
Ok, I get the space constraint. Two other questions. What did you mean when you said, "Inserted PCBs swing down into place" if they are hand inserted? Is one edge of the board hooked in a slot and the board levered into the connector.
Can you help me picture what you meany about "considerable other lithographic treatments". What sort of card is this that won't be soldered???
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Not fully understanding the need to not solder a connector to a board I wou ld recommend the Amphenol Conan series of connectors. They have a vertical receptacle and a right angle header in 1 mm, 51 pin configuration which is 30.3 mm wide. Using alignment pins along with the mechanical solder pads will help relieve strain on the pins when inserting.
I've always found two piece connectors to be great for reliability as well as making the circuit board easy to design and fabricate. Having an odd nu mber of pins, the connectors are self orienting needing no alignment key.
Just thought I'd mention these. I've used them before and they have a nice , gentle snap action to hold the board in place while securing it mechanica lly. For light duty work the snap action can replace using a screw. No do ubt the connector is mated fully which is not an uncommon failure mode for other connectors.
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That's an attractive connector set. Its 7mm board-to-board height spacing is a little excessive, but only by about 3mm.
There are four others involved in the project. I checked again, and they prefer to have stacks of various board patterns and build their microchannels, etc., on that, without any soldering or other non-PDMA0-style technology. However, they envision some applications with more than 50 to 100 connector cycles, so there may be pressure to accept a reliable two-piece connector solution instead.
Not sure what you are looking at. With the right angle header you would ne ed there is no minimum board to board height is there? The right angle con nector is surface mount so the board can project below that as much as desi red until it hits the other board. The top of the receptacle is 3.28 mm ta ll but even that should clear the mating board easily.
The 7 mm board to board height is for the "vertical" connectors which mount the boards parallel. Even then, 7.52 mm is the largest spacing. The sma llest is 4.15 mm.
Sorry, I don't follow any of this. What is a microchannel and what does it have to do with this? Don't know what you meany by "board patterns", do y ou just mean they will use various board shapes? I have no idea what PDMA0 is, Google thinks it's something biological.
I really don't get what you are saying about not soldering. Aren't these b oards electronics? How do you build boards without soldering???
Interesting. The Conan connectors are only rated for 30 cycles. So maybe this isn't the connector for you.
It seems like insertion cycles is something that would be relatively standa rdized into categories. Anyone know if 30 cycles is common for gear that i s typically built and never touched again? Sounds right to me. If the con nectors are going to get any real use, I expect there is a separate class o f connector that is constructed very differently.
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Avoid SMT connectors in multi-cycle applications if at all possible. Actually, we have problems with them even in insert-once situations.
Ham-fisted insertion/removal, dropped units, vibration; anything that introduces lateral forces can and will peel the traces off the board. At least with through-hole, it takes a lot more force to do an equivalent amount of damage to traces.
Buzz McCool wrote in news:r67kgd$ql3$1 @gioia.aioe.org:
Early stuff was not even Gold microinch eplating like everything is now.
I got paid full repair session pay for showing up at the game room where the PacMan or Centipede was on the fritz, for merely shutting down and then pulling the edge connectors on and off a few times. One could always tell if that was the problem too because there would be garbage characters drawn on the screen. Otherwise, it was a real repair like a fuse or such. ;-) had to charge a full 30 minutes even though it only takes a few, and to keep game room operators from going apeshit, we had to hang around in the back of the machine for a while passing the time.
Memory module realm knew what they were doing and DIM tech is the best tech for that many pins on a replaceable module. (leaving out CPUs). But his choice is like DIMM because of they way it gets fixed into place. They are very high integrity for very long term and trhough vibe even.
You should see some restoration videos of old computers and uprigt video games, and old Oscopes and such. Lots of fun and very informative.
That is certainly true of connectors without alignment pins. The alignment pins take strain off the solder joints. I use a surface mount connector o n my board with mating surface mount parts on the motherboard (which I didn 't design). The motherboard parts don't have alignment pins and get used o ver and over with no failures so far, so I'm expecting my boards to do just fine. So far, no problems in around 10,000 units, 20,000 connectors. Can 't be all bad.
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It will be interesting to see how they hold up long-term. Your users must be less ham-fisted than ours. :)
If the alignment pins press-fit into the alignment holes, yes, they can take up much of the strain. If it's the common small-pin-in-a-larger-PCB-hole alignment, not so much. If the alignment pins are soldered through-hole, why not all the pins?
We tried an SMT USB connector with through-hole solder tabs to hold it to the board; our crews still found ways to break them loose. I've got name-brand laptops on the dead equipment shelf with trashed charge jacks (SMT) that ripped loose over time.
Even with alignment pins/tabs, I stand by my previous statement: avoid SMT connectors if you can.
The issue is less of concern if the connector has many pins, providing strength, such as the 52-pin mSATA connector. And its users are (carefully) installing and fastening in place a fixed PCB, rather than a connector with an attached cable.
Winfield Hill wrote in news:r6aeiq01c02 @drn.newsguy.com:
It is a good choice. I even think one could make (design) a small PCB that mounts there, and attach (solder in) a (presumably up to 52 pin) cable to THAT solidly mounted PCB (do it before you mount it). Then, any tensions applied to the cable will never make it to the connector header because the PCB is a mounted piece. Hey! That would work!