mSATA PCIe connector

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 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.


--  
 Thanks,
    - Win

Re: mSATA PCIe connector
On Thursday, April 2, 2020 at 5:23:38 PM UTC-4, Winfield Hill wrote:
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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?  

--  

  Rick C.

  - Get 1,000 miles of free Supercharging
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Re: mSATA PCIe connector
Rick C wrote...
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 Thanks, Rick, for your comments.

 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.


--  
 Thanks,
    - Win

Re: mSATA PCIe connector
On Friday, April 3, 2020 at 6:16:33 AM UTC-4, Winfield Hill wrote:
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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???  

--  

  Rick C.

  + Get 1,000 miles of free Supercharging
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Re: mSATA PCIe connector
@drn.newsguy.com:

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  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...

Re: mSATA PCIe connector
On Thu, 02 Apr 2020 14:23:19 -0700, Winfield Hill wrote:

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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.

--  
Chisolm
Texas-American


Re: mSATA PCIe connector
Joe Chisolm wrote...
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 That looks good, but the Mouser datasheet is a disaster!
 But the company's website has a better copy.  I like the
 huge 4.4mm clearance.


--  
 Thanks,
    - Win

Re: mSATA PCIe connector
On 4/2/20 2:23 PM, Winfield Hill wrote:
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Card edge connectors, in my experience, always have connectivity  
problems. (STD-BUS, ISA, EISA, PCI, PCI-X, PCIe, DIMM ... )

Had the best luck with dual wiper DIMM connectors (I think they were  
sourced from Fujitsu).

My motto is "Card edge connectors don't connect."

Re: mSATA PCIe connector
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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.  

Thank you,

--  
Don Kuenz KB7RPU
There was a young lady named Bright Whose speed was far faster than light;
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Re: mSATA PCIe connector
On 4/3/20 8:52 AM, Don Kuenz wrote:
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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!)


Re: mSATA PCIe connector
@gioia.aioe.org:

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  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.

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were  
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  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.

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  You should see some restoration videos of old computers and uprigt  
video games, and old Oscopes and such.  Lots of fun and very  
informative.

Re: mSATA PCIe connector, card thickness
Winfield Hill wrote...
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 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?


--  
 Thanks,
    - Win

Re: mSATA PCIe connector, card thickness
On Friday, April 3, 2020 at 1:07:32 PM UTC-4, Winfield Hill wrote:
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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.  

--  

  Rick C.

  -- Get 1,000 miles of free Supercharging
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Re: mSATA PCIe connector, card thickness
Ricky C wrote...
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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.


--  
 Thanks,
    - Win

Re: mSATA PCIe connector, card thickness
On Friday, April 3, 2020 at 4:52:38 PM UTC-4, Winfield Hill wrote:
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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.  


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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???  


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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.  

--  

  Rick C.

  -+ Get 1,000 miles of free Supercharging
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Re: mSATA PCIe connector, card thickness

[snip]

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.

Just my opinion, take it for what it's worth...

RD

Re: mSATA PCIe connector, card thickness
On Friday, April 3, 2020 at 7:10:05 PM UTC-4, Randy Day wrote:
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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.  

--  

  Rick C.

  +- Get 1,000 miles of free Supercharging
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Re: mSATA PCIe connector, card thickness
snipped-for-privacy@gmail.com says...

[snip]

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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.

RD

Re: mSATA PCIe connector, card thickness
Randy Day wrote...
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 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.


--  
 Thanks,
    - Win

Re: mSATA PCIe connector, card thickness
@drn.newsguy.com:

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  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!

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