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TO-220 Failures due to lead bending?

I have a small 480v 5w flyback power supply that has had a large number of field failures. In general the failure rate is about 0.4%, one out of 250 units. This I can live with. One particular customer in Northern California has had a 25% failure rate. Most of the units come back filthy so that there may be an environmental aspect to the problem as well. I think units are in an air stream which may be blown in from a rooftop intake. We have beat the crap out of the power supplies here at the factory and have not been able to kill them. Heated transistors to 150c, put 1500v dc on the supply, etc and they keep on running. I am begining to think there may be a stress related problem with the lead bend. Production is bending a complete 90degree at the drain lead of the mosfet directly at the package. It looks like the package ruptures and sends plasma out and destroys the clamp diodes and control chip and so forth. Destruction is very complete here.

So question is then - has anybody ever heard of failures related to this type of handling? I will contact mosfet vendor after discussing here.

thanks, Bob

Reply to
Yzordderrex
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"directly at the package" would imply that the lead is bent without any support at the package side of the lead?

I've seen such failures with DIP I/C's. I think such bends destroy the little "hermeticity" afforded by the molding process.

I'd support the lead adjacent to the package with some kind clamp so that the plastic is not stressed.

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.
Reply to
Jim Thompson

Not in particular but since semiconductor manufacturers give 'No No' imformation about this sort of thing elsewhere you might assume that it is BAD practice. They also give good practice recommendations.

As a result of such warnings it is not something I would 'design in'.

But I'm totally gay and spend most of my time hoping some nice person will post a Candy Samples movie in the Pornstars80s newsgroup.

DNA

Reply to
Genome

Yuk. She was a stripper on Bourbon Street back when I lived in New Orleans. Way high on the bovine-osity scale, in my opinion.

Tempest Storm was pretty classy in her day.

John

Reply to
John Larkin

What was that gal's name who performed in SF, in a swing, around

1968... about 5', very petite except for 44's ?:-)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.
Reply to
Jim Thompson

Shanda Lear?

Cheers,

Phil Hobbs

Reply to
Phil Hobbs

What kind of filthy? Black filthy or white streaks filthy?

Best regards, Spehro Pefhany

--
"it\'s the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
Reply to
Spehro Pefhany

Carol Doda, the original silicone diva; she performed at the Condor. I saw her show when I was here on a business trip, and aside from the dual deformities, she was actually pretty talented and funny.

"The Condor Club on the corner of Columbus and Broadway was also reputedly the world's first officially recognized strip club. It is now a night club and a municipal landmark."

John

Reply to
John Larkin

But this is the first time she has appeared in a thread about TO-220 lead failures!

Reply to
mc

[snip]

Carol Doda, that's the name I was trying to remember. I was only 28 at the time... I was "entranced" ;-)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.
Reply to
Jim Thompson

I remember having a KitKat with chocolate all the way through.....

Didn't Dolly Parton have similar proportions when she was in 9-5...... and was that a leather dress she wore?

DNA

Reply to
Genome

I got photos from my stag just about being smothered by 'Suzy Boobies'. She must have found a criminally insane doctor to insert that much silicone in a single chest. If she hasn't had them reduced, they're probably dragging on the floor now (almost exactly 17 years ago now). whew.

Best regards, Spehro Pefhany

--
"it\'s the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
Reply to
Spehro Pefhany

CD's silicone was directly injected, no baggies. Sounds medically scairy to me.

I like skinny women anyway.

John

Reply to
John Larkin

She also performed at the Brass Rail in Mountain View in the early 70's. One of her tricks was to hold a full pitcher of beer under one tit and pour it into a beer mug held under the other. Both were frosted from the humidity.

A bunch of us from the engineering group at Memorex often went there for lunch. The roast beef was excellent. One day she came to our table after her act and sat down beside me. I asked her how long did it take to learn how to do that - she replied "A Very Long time."

We gave her a good tip and went back to work.

Regards,

Mike Monett

Reply to
Mike Monett

Slender plus grapefruits ;-)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.
Reply to
Jim Thompson

She had her own club (or at least, she worked in a club that bore her name) when I visited SF with some friends in 70 or 71. Due to quirks in the law of the time, she performed nude on stage (as other apprentice strippers performed nude on little side stages) between acts of a xxx-rated film in which she performed acts which would not be legal to do live.

Reply to
Richard Henry

Sure.

Reply to
Richard Henry

Yes, I saw that same live/film act about that time.

That place was, and still is, the Condor, though she had top billing for some time. It's now a cajun/creole restaurant, I think.

John

Reply to
John Larkin

Smirk. I was thinking the same thing ;-)

...Jim Thompson

-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |

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| 1962 | I love to cook with wine. Sometimes I even put it in the food.

Reply to
Jim Thompson

Parts should be bent BEFORE placement in the board. This eliminates the tendency for the part to want to spring back and always have tension on it. Under certain conditions, this tension can cause the part to crack apart.

Reply to
Brian

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