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Transistor case.

Discussion in 'Electronic Design' started by Brian, Oct 26, 2004.

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  1. Brian

    Brian Guest

    It looks like a TO-3, but maybe 50% larger. What is it?
     
  2. Jim Thompson

    Jim Thompson Guest

    Perhaps your thinking is reversed? TO-66 looks like a _size-reduced_
    TO-3.

    ...Jim Thompson
     
  3. legg

    legg Guest

    There are oversized TO-5 and TO-39 packages which are TO8.

    Oversized TO-3 is an "X-87", first associated with Toshiba products
    since the late '70s.(46mm or 43.3 mm between mounting holes vs the
    standard 30mm depending on mfr)

    Usually when the TO-3 is 'improved', the solution involves taking the
    lead-outs through the lid, or sidewalls without signifigantly
    increasing the mounting imprint. This allows for a larger wafer
    bonding area.

    The altered packages are usually associated with parts that have
    current ratings in excess of 30A or power ratings above 300W, and may
    be most often seen in rarer types of thyristors, bridges and static
    induction devices from SE Asia. (Tokin Sanyo)

    The function is more easily/economically performed by other packages,
    though hermetic parts will be ceramic rather than metal-bonded.

    Any part number or mfr logo?

    RL
     
  4. Brian

    Brian Guest

    This may sound odd, but I am looking for the cover for one to complete a
    restoration. Probably going to be a hell of a hunt.
     
  5. legg

    legg Guest

    Is this for cosmetic purposes, or do you expect near-full function
    from the restoration? Unless the part has been passivated or otherwise
    sealed in some way, it's likely to be compromised by ingress of
    contaminants.

    These parts, being difficult to obtain, are more likely to be decapped
    for inspection only AFTER they go boom, unless accessed by gremlins.

    Missing cap means no ID - check the wafer under an inspection
    microscope to look for vendor marks - or sketch/photograph it. It's
    often possible to identify function/mfr by pattern, if it isn't sealed
    with an opaque material. Evidence of a kaboom or any slip of the
    decapping tools would also likely visible.

    Otherwise, a sketch of the immediate interconnectons and connected
    devices (schematic), or top assembly/model type number could give a
    fair idea of device type and origin.

    The cap's seams were likely impedance welded, at least for the steel
    and copper varieties - rather difficult to remove without damage to
    both parts. Reclaiming one half for recapping would be tricky, if you
    had the equipment.

    Cleaning, baking, testing and sealing, before any cosmetic
    restoration, might be advised, depending on your aims.

    RL
     
  6. Brian

    Brian Guest

    this cap was just the cover over the device, not part of the device itself,
    similar to the ones over TO-3 devices that Keystone makes. Just to protect
    it or as a heat sink.
     
  7. legg

    legg Guest

    A strange combination of technologies, then.

    Any cover with mounting holes in the same position could be fixed with
    appropriate non-conductive standoffs.

    I believe the aim is to protect the end user, and prevent component
    fault due to accidental contact with the live case. Required as a
    result of incompetent mechanical design, though this could result also
    in misguided attempts at enhanced heatsinking.

    I'm increasingly curious. What is the equipment and who was the
    bodger?

    RL
     
  8. Brian

    Brian Guest

    My guess is it is to protct the user from heat off of the device or protect
    the device from a bump as it sticks out the back.
     
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