Hockey puck SCRs

Discussion in 'Electronic Basics' started by KW, Dec 12, 2007.

  1. KW

    KW Guest

    I recently bought a hockey-puck SCR, without realising it needs to be
    clamped to a heatsink. I'm trying to decide whether to return it or
    whether to build a mount.

    The SCR in question is an Internation Rectifier 250PA140, specs pasted at
    the end of this topic.

    First of all, I haven't managed to find any information about how much
    force you need to clamp these things with. I'm assuming 2 metal plates
    with 3x6mm bolts should be ample.

    Secondly, do I need to apply force or displacement? For example, if I need
    to apply exactly 1mm of displacement to the plates of the puck, then the
    puck contracts by 0.1mm this might be a disaster, unless there is some
    kind of springy contact inside that will take up the slack. Perhaps I
    should use some kind of springy bar to apply a constant pressure despite
    changes in temperature etc...

    Thirdly, I presume that too much force will break the die, and too little
    will mean the contact has insufficient area for the device to function
    properly? How can I know when I've tightened the clamp the right amount?

    Finally, I understand there is meant to be a snubber resistor between the
    gate and the cathode. But I get very low resistances of < 0.1 ohm and I
    wonder whether this implies it is broken?

    If I(GT) Max. is 150m and the parallel resistance is < 0.1 ohms then as I
    see it the voltage can't rise high enough to cause the device to trigger -
    I'm assuming it needs at least a diode drop.

    Thanks in advance for any help.

    K


    V(DRM) Max.(V)Rep.Pk.Off Volt.=1.4k
    I(T) Max.(A) On-state Current=250?
    @Temp. (?C) (Test Condition)=70
    I(TSM) Max. (A)=4.2k
    I(GT) Max. (A)=150m
    V(GT) Max.(V)=2.5
    I(H) Max.(A) Holding Current=500m
    I(D) Max. (A) Leakage Current=11m
    @Temp. (?C) (Test Condition)=125
    V(T) Max. (V)=2.3
    @I(T) (A) (Test Condition)=250
    dv/dt Min. (V/us)=200
    t(q) Typ. (s)=60u
    Package=TO-200AB
     
    KW, Dec 12, 2007
    #1
    1. Advertising

  2. On Wed, 12 Dec 2007 03:15:03 +0000, KW <>
    wrote:

    >I recently bought a hockey-puck SCR, without realising it needs to be
    >clamped to a heatsink. I'm trying to decide whether to return it or
    >whether to build a mount.
    >
    >The SCR in question is an Internation Rectifier 250PA140, specs pasted at
    >the end of this topic.
    >
    >First of all, I haven't managed to find any information about how much
    >force you need to clamp these things with. I'm assuming 2 metal plates
    >with 3x6mm bolts should be ample.
    >
    >Secondly, do I need to apply force or displacement? For example, if I need
    >to apply exactly 1mm of displacement to the plates of the puck, then the
    >puck contracts by 0.1mm this might be a disaster, unless there is some
    >kind of springy contact inside that will take up the slack. Perhaps I
    >should use some kind of springy bar to apply a constant pressure despite
    >changes in temperature etc...
    >
    >Thirdly, I presume that too much force will break the die, and too little
    >will mean the contact has insufficient area for the device to function
    >properly? How can I know when I've tightened the clamp the right amount?
    >
    >Finally, I understand there is meant to be a snubber resistor between the
    >gate and the cathode. But I get very low resistances of < 0.1 ohm and I
    >wonder whether this implies it is broken?
    >
    >If I(GT) Max. is 150m and the parallel resistance is < 0.1 ohms then as I
    >see it the voltage can't rise high enough to cause the device to trigger -
    >I'm assuming it needs at least a diode drop.
    >
    >Thanks in advance for any help.
    >
    >K
    >
    >
    >V(DRM) Max.(V)Rep.Pk.Off Volt.=1.4k
    >I(T) Max.(A) On-state Current=250?
    >@Temp. (?C) (Test Condition)=70
    >I(TSM) Max. (A)=4.2k
    >I(GT) Max. (A)=150m
    >V(GT) Max.(V)=2.5
    >I(H) Max.(A) Holding Current=500m
    >I(D) Max. (A) Leakage Current=11m
    >@Temp. (?C) (Test Condition)=125
    >V(T) Max. (V)=2.3
    >@I(T) (A) (Test Condition)=250
    >dv/dt Min. (V/us)=200
    >t(q) Typ. (s)=60u
    >Package=TO-200AB


    I found another device datasheet with TO-200AB. At the end of the
    datasheet, it says 700-900 lb, or 320-400 Kg.

    http://www.powersemiconductors.com/images/pdfs/phase_control/DT03N series.pdf

    http://tinyurl.com/2c8fau


    I don't think you'd be looking at displacement for a ceramic case.

    --
    John
     
    John O'Flaherty, Dec 12, 2007
    #2
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  3. KW

    Mike Guest

    On Wed, 12 Dec 2007 03:15:03 +0000, KW <> wrote:

    >I recently bought a hockey-puck SCR, without realising it needs to be
    >clamped to a heatsink. I'm trying to decide whether to return it or
    >whether to build a mount.
    >
    >The SCR in question is an Internation Rectifier 250PA140, specs pasted at
    >the end of this topic.
    >
    >First of all, I haven't managed to find any information about how much
    >force you need to clamp these things with. I'm assuming 2 metal plates
    >with 3x6mm bolts should be ample.
    >
    >Secondly, do I need to apply force or displacement? For example, if I need
    >to apply exactly 1mm of displacement to the plates of the puck, then the
    >puck contracts by 0.1mm this might be a disaster, unless there is some
    >kind of springy contact inside that will take up the slack. Perhaps I
    >should use some kind of springy bar to apply a constant pressure despite
    >changes in temperature etc...
    >
    >Thirdly, I presume that too much force will break the die, and too little
    >will mean the contact has insufficient area for the device to function
    >properly? How can I know when I've tightened the clamp the right amount?
    >
    >Finally, I understand there is meant to be a snubber resistor between the
    >gate and the cathode. But I get very low resistances of < 0.1 ohm and I
    >wonder whether this implies it is broken?
    >
    >If I(GT) Max. is 150m and the parallel resistance is < 0.1 ohms then as I
    >see it the voltage can't rise high enough to cause the device to trigger -
    >I'm assuming it needs at least a diode drop.
    >
    >Thanks in advance for any help.
    >
    >K
    >
    >
    >V(DRM) Max.(V)Rep.Pk.Off Volt.=1.4k
    >I(T) Max.(A) On-state Current=250?
    >@Temp. (?C) (Test Condition)=70
    >I(TSM) Max. (A)=4.2k
    >I(GT) Max. (A)=150m
    >V(GT) Max.(V)=2.5
    >I(H) Max.(A) Holding Current=500m
    >I(D) Max. (A) Leakage Current=11m
    >@Temp. (?C) (Test Condition)=125
    >V(T) Max. (V)=2.3
    >@I(T) (A) (Test Condition)=250
    >dv/dt Min. (V/us)=200
    >t(q) Typ. (s)=60u
    >Package=TO-200AB


    My old GE manual specifies 700-900lbs force for their
    press pak mounted SCRs. I mounted some where I didn't have
    to be concerned about dissipating heat (single pulse operation)
    and found an online calculator to determine clamping force resulting
    from a given torque on a bolt then used a small torque wrench to
    tighten it up. I don't remember the numbers, but it took surprisingly
    little torque to get 800lbs clamping force. You might try googling
    "presspack" to see what you come up with.

    Mike
    When truth is absent politics will fill the gap.
     
    Mike, Dec 12, 2007
    #3
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