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From: Richard Rasker on 11 Apr 2010 15:53
Hello,

I've been asked to design a simple motor-driven pump for medical use, and
one of the primary requirements is that the device can be sterilized using
an autoclave, which works with steam at 135 degrees Centigrade.

Basically, there's no need to use any semiconductors or electrolytic
capacitors in the device, but my client asked if I could include LED's in
the design. From what I can find, LED's are specified for a maximum of
80~85 degrees C storage temperature, whereas most semiconductors have a
range up to 150 degrees C (bipolar) or even 175 degrees C (FET's). So it
would appear that using LED's may pose a problem in this particular case.

Does anyone have any more information about this?

Thanks in advance, best regards,

Richard Rasker
--
http://www.linetec.nl
From: John Larkin on 11 Apr 2010 16:31
On Sun, 11 Apr 2010 21:53:37 +0200, Richard Rasker
<spamtrap(a)linetec.nl> wrote:

>Hello,
>
>I've been asked to design a simple motor-driven pump for medical use, and
>one of the primary requirements is that the device can be sterilized using
>an autoclave, which works with steam at 135 degrees Centigrade.
>
>Basically, there's no need to use any semiconductors or electrolytic
>capacitors in the device, but my client asked if I could include LED's in
>the design. From what I can find, LED's are specified for a maximum of
>80~85 degrees C storage temperature, whereas most semiconductors have a
>range up to 150 degrees C (bipolar) or even 175 degrees C (FET's). So it
>would appear that using LED's may pose a problem in this particular case.
>
>Does anyone have any more information about this?
>
>Thanks in advance, best regards,
>
>Richard Rasker

Try some! The big problem is that the transparent plastics tend to
soften up at high temps, and the leads/chips can move around and break
wirebonds. But 135C isn't very hot; we reflow solder boards with
surface-mount LEDs at well over 200C.

Infineon makes some nice surface-mount led's with inner transparent
plastic and an outer white shell of high-temp stuff. They hold up to
heat very well.

John

From: George Jefferson on 11 Apr 2010 16:38


"Richard Rasker" <spamtrap(a)linetec.nl> wrote in message
news:4bc228c1$0$736$7ade8c0d(a)textreader.nntp.internl.net...
> Hello,
>
> I've been asked to design a simple motor-driven pump for medical use, and
> one of the primary requirements is that the device can be sterilized using
> an autoclave, which works with steam at 135 degrees Centigrade.
>
> Basically, there's no need to use any semiconductors or electrolytic
> capacitors in the device, but my client asked if I could include LED's in
> the design. From what I can find, LED's are specified for a maximum of
> 80~85 degrees C storage temperature, whereas most semiconductors have a
> range up to 150 degrees C (bipolar) or even 175 degrees C (FET's). So it
> would appear that using LED's may pose a problem in this particular case.
>
> Does anyone have any more information about this?
>
> Thanks in advance, best regards,


Is an LED absolutely necessary? Seems like there are alternatives that will
work just fine. The main problem with the LED's is going to be the
packaging. Most of the time they are made of clear plastic like material
that is not designed for high temp. Possibly there are some with glass bulbs
rather than plastic. Potentially you could make your own housed in a small
glass build if your really up to it.


From: whit3rd on 11 Apr 2010 16:45
On Apr 11, 12:53 pm, Richard Rasker <spamt...(a)linetec.nl> wrote:
> Hello,
>
> I've been asked to design a simple motor-driven pump for medical use, and
> one of the primary requirements is that the device can be sterilized using
> an autoclave, which works with steam at 135 degrees Centigrade.
>
> Basically, there's no need to use any semiconductors or electrolytic
> capacitors in the device, but my client asked if I could include LED's in
> the design. From what I can find, LED's are specified for a maximum of
> 80~85 degrees C storage temperature, whereas most semiconductors have a
> range up to 150 degrees C (bipolar) or even 175 degrees C (FET's). So it
> would appear that using LED's may pose a problem in this particular case.

Most LEDs use packages that aren't appropriate (plastic lens); and the
autoclave, in addition to heat, applies condensing moisture, which is
a
corrosion issue. Can you put the LEDs in a separate box, and use
light pipes (plastic optical fiber) to get the light into the
sterilized unit?
There are connectors that accept light-emitter 'pins'.

Otherwise, I'd think of using grain-of-wheat incandescent lamps.
From: Spehro Pefhany on 11 Apr 2010 17:00
On Sun, 11 Apr 2010 21:53:37 +0200, the renowned Richard Rasker
<spamtrap(a)linetec.nl> wrote:

>Hello,
>
>I've been asked to design a simple motor-driven pump for medical use, and
>one of the primary requirements is that the device can be sterilized using
>an autoclave, which works with steam at 135 degrees Centigrade.
>
>Basically, there's no need to use any semiconductors or electrolytic
>capacitors in the device, but my client asked if I could include LED's in
>the design. From what I can find, LED's are specified for a maximum of
>80~85 degrees C storage temperature, whereas most semiconductors have a
>range up to 150 degrees C (bipolar) or even 175 degrees C (FET's). So it
>would appear that using LED's may pose a problem in this particular case.
>
>Does anyone have any more information about this?
>
>Thanks in advance, best regards,
>
>Richard Rasker

Lumex has ceramic-substrate (non-hermetic, though) SMT LEDs with
storage temperature ratings of 120�C. Steam is fairly aggressive at
corroding aluminum bonding wires AFAIUI-- you may not be able to find
a part that is actually guaranteed for this kind of service. There
used to be visible LEDs in the old hermetic TO-46 package, but perhaps
no more, at least not at an affordable price. Here's one that's rated
for 150�C storage.

http://www.micropac.com/pdf/products/62096.pdf


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff(a)interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
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