Ideas for making edge connectors

Discussion in 'The Projects Forum' started by sirch2, Feb 25, 2015.

  1. sirch2

    Thread Starter Well-Known Member

    Jan 21, 2013
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    I have just received a small(12mmx22mm) motion sensor module which is all surface mount and has very small edge pads for interconnections. The module is reasonably expensive and for prototyping and just getting it going I would like to connect it up without soldering it down. My thinking is to make some small springy bent L edge connectors sort of like shown below and solder these on to a copper clad board as a breakout
    Code (Text):
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    2.    \                /
    3.   _/................\_              ....... Module
    4.   -------------------           ----- PCB
    5.  
    6.  
    Now I am no watch-maker, I have tried similar things in the past and whilst in my head they always look professional, the end result is usually a lash-up. So are there any other ideas of how to do this or any tips on forming tiny parts, it is all going to be hand made and hand soldered. Not all the pins I need to connect are on one edge and the big concern is accuracy of making and positioning the spring connector so that they both hold the board and make reliable contact.
     
  2. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    I would use zebra strip connectors (Google it) but that needs PCB pads that match your board so it's a chicken and egg solution.

    A picture of the board or link would help.
     
  3. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    google 'header pin connector'
    you csn drill small holes for the pin and solder them. you could silicon the pins snd connect with small wires instead of drilling. using pins makes the board removeable
     
  4. sirch2

    Thread Starter Well-Known Member

    Jan 21, 2013
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    Thanks those elastomeric connectors look like the right sort of thing but none of the regular suppliers seem to stock them. Making a PCB of the right dimensions is not a problem in fact I drew up a part in Eagle last night before I got to thinking that soldering it initially is probably not the best approach. I'll post a picture this evening.

    But... what I am now thinking is to make my own elastomeric connector - solder loops of wire to pads on a PCB at the correct spacing for the module contacts, embed these in something like bathroom silicone and press the module down onto this once the silicon has set.
     
  5. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    pressing against metal and relying on the spring tension to keep the connection secure will work for awhile. eventually the metal sets in the new position and all the spring tension disappears. FYI
     
  6. sirch2

    Thread Starter Well-Known Member

    Jan 21, 2013
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    I know what you are getting at but it's all about elastic vs plastic deformation, the shocks in my car haven't set in a new position yet. As I said this is just for initial trials before the unit gets permanently fixed into the final project.
     
  7. MaxHeadRoom

    Expert

    Jul 18, 2013
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    If you measure the pad size, you could check out the various insertion pin/sockets for miniature & sub-miniature in line connectors, if you find a suitable type, a solid or flex wire could be attached as it would be in a connector.
    Digikey is one of the best sources.
    Max.
     
  8. ericgibbs

    Senior Member

    Jan 29, 2010
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  9. alfacliff

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    Dec 13, 2013
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    be careful using silicon calk on electrical connections, chemicals in it can corrode some metals.
     
  10. RichardO

    Well-Known Member

    May 4, 2013
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    Be warned that there are 2 types of elastomeric connectors. The ones used in LCD modules are carbon loaded and have a high resistance. Others have "needles" and have low resistance. You may not be able to the carbon ones. You can take apart a broken LCD character or graphic display to get some zebra strip to play with.

    Edit: I should have mentioned that the strips must be very well supported or they flop over and don't work.
     
  11. sirch2

    Thread Starter Well-Known Member

    Jan 21, 2013
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    Thanks all I'll investigate those suggestions. As promised, here's some pictures

    PNI 004.JPG PNI 001.JPG
     
  12. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    It is a little hard to tell the center-to-center distance. It looks around 3 mm. If it is actually 2.54 mm or 4 mm (or some nice multiple), then a standard pinheader will work with solder.

    John
     
  13. sirch2

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    Jan 21, 2013
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  14. ErnieM

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    Apr 24, 2011
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    The pads are not horribly off a 0.1" grid such as a breadboard. I took the pad layout on sheet 28 and sketched it in autocad and pasted that on a breadboard grid.

    Not too bad a match, and you can use the breadboard to hold some fly wires; I use 30 AWG for stuff like this.

    [​IMG]
     
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  15. sirch2

    Thread Starter Well-Known Member

    Jan 21, 2013
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    That's great, thanks for taking the time, another set of eyes is always a good thing, I think I was a bit bogged down in 2.54 != 3.0
     
  16. ErnieM

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    One last thing: (two actually) when I say "breadboard" I mean the ones I use which that are a sea of plated thru holes on 0.1" centers, not a solderless breadboard.

    But do be careful there are no features on the device's backside that could be shorted by the unused pads.
     
  17. sirch2

    Thread Starter Well-Known Member

    Jan 21, 2013
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    Thanks, may well make up a little board and as you said earlier just connect it with short flying leads
     
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