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DIP placement with heavy gauge PCBs

Discussion in 'Electronic Design' started by Bruce Varley, May 26, 2007.

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  1. Bruce Varley

    Bruce Varley Guest

    Hi, I'm using a thick-substrate PCB, so that I can include screw terminals
    on the board and it won't flex too much when the screwdriver is applied. The
    board thickness is such that DIP pins only just poke through to the copper
    layer, to the point where soldering could be unreliable. The problem is
    solvable by drilling larger diameter holes from the non-copper side
    partially through, so that the packages sit lower on the board. Do PCB
    manufacturers routinely provide program-controlled drilling of this sort,
    does it have a name? TIA
  2. couldn't you use wire wrap dil sockets?

  3. Winfield

    Winfield Guest

    Soldering shouldn't be an issue even if the lead is
    not visible, if you use proper plated-through holes.
    But if the holes are too large, the desired wicking
    effect might not work as reliably, so I'd use the
    ordinary hole size. Afterwards you can inspect the
    joints from the top. Or, you could use SMD parts.
  4. feebo

    feebo Guest

    you don't say if the holes are hru-plated? if so, assuming all other
    factors are ok, they should solder in nicely.
  5. You should be able to get a rectangular depression with rounded
    corners machined into the board so the package will sit lower. It's
    called a "milled pocket". There is a lower limit to the internal
    radius (caused by the cutter radius, of course)-- too small a radius
    and it will take too long to make or the cutter will break too easily.
    Think of something like a 0.05"~0.1" radius. You won't be able to
    reliably run conductors over the milled edge, so if it's a two-sided
    board you'll have to run all the conductors from the opposite side to
    the milled depression. SMT DIP sockets might end up being cheaper.

    Best regards,
    Spehro Pefhany
  6. Mike Monett

    Mike Monett Guest

    Screw terminals don't work well on pcb fiberglass. They can work

    Use a proper connector with screw terminals, and provide support
    under the pcb to handle any excessive force.

    Now you can use a standard pcb thickness and solve the DIP problem!


    Mike Monett
  7. Hello,

    It's named back drilling. I's sometimes used to shorten the via-stub
    of traces used for very high speed signals.

    You will find a lot of links with Google: back drilling.

    Best regards,
  8. Phil Allison

    Phil Allison Guest

    "Bruce Varley"

    ** Install the DIPs on the copper side of the PCB - don't matter a damn
    how thick it is then.

    ........ Phil
  9. MooseFET

    MooseFET Guest

    You don't need a thick PCB.

    Put rubber feet or standoffs behind where the phoenix connector is
    placed. Rubber feet also help you to withstand vibration.

    Milmax 111-XX-YZZ-41-001100
    XX=plating type 13 for gold
    Y=width in 0.1 inch
    ZZ=number of pins
  10. John Larkin

    John Larkin Guest

    Are the screws squeezing the board? If so, the epoxy will cold-flow
    over time, and the screws will loosen. If there's much current
    flowing, the screws will get hot and the process will run away.

    Use a regular board thickness. It will compress *less* for a given
    screw pressure. Use belleville washers to define the compression force
    or, better yet, use barrier strips that don't depend on board
    compression at all.

  11. John Larkin

    John Larkin Guest

    I've done the opposite, countersinking holes before they were plated.
    The shiny funnels look cool, and countersunk screw heads can be flush
    with the board surface.

  12. Jasen

    Jasen Guest

    if you get no answer here try sci.electronics.manufacture

    plate thru holes could be anorther solution, sticking the dips in
    wire-wrap sockets (which have long pins) yet another.
  13. Bruce Varley

    Bruce Varley Guest

    Thanks for all the suggestions, guys.
  14. TT_Man

    TT_Man Guest

  15. Ross Herbert

    Ross Herbert Guest

    If such a process were conducted by any pcb maker (which it isn't) it
    would probably be termed "counterboring".

    I can suggest two options. One is to use wire wrap dil IC sockets
    because these have longer legs than standard sockets (simply cut off
    the excess length). The second is to use individual turned pin sockets
    which were made by companies such as Cambion back in the 70's. These
    items were much longer than a standard pin on a dil IC and would
    extend through to the copper layer on a thicker pcb.Due to their
    diameter thay are only suitable for standard 0.1" pitch dil IC's - and
    they are/were expensive.

    I am sure I still have some of these in stock.
  16. Ross Herbert

    Ross Herbert Guest

    Apologies,I didn't see that this post had been thoroughly answered in
    a previous thread (since it didn't show up with a RE: prefix).
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