LED temperature range
in [Design]
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From: Richard Rasker on 11 Apr 2010 16:55 John Larkin wrote: > 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. Sure, but these devices will have to withstand not just one short reflow cycle, but dozens of 5-minute sterilization cycles at 135C. > 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. OK, if the transparent plastic is the main problem, I guess I'll have to look for LED's with a ceramic substrate to ensure stability of the semiconductor chip, and a heat-resistant outer shell like you mention. Thanks for the swift response, best regards, Richard Rasker -- http://www.linetec.nl
From: Jon Kirwan on 11 Apr 2010 17:33 On Sun, 11 Apr 2010 21:53:37 +0200, Richard Rasker <spamtrap(a)linetec.nl> wrote: >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, The die itself shouldn't be the problem, so it's not a fundamental barrier. I don't suppose this is an infusion pump, as those generally require some means by which to measure cam rotation angles, which implies quadrature detection to me. I don't know what your volumes might be, but some companies making diode detectors have been fairly cooperative about accomodating specific needs at surprisingly reasonable quantities. Not exactly the same business area as LEDs, but perhaps close enough. You might contact a few LED manufacturers and at least give them a chance to suggest their thoughts about meeting your specs. You might be pleasantly surprised by the response. (My contacts have been with both US and Japanese manufacturers. I believe Spehro Pefhany has more personal experience than many here about Chinese sources and may be able to reflect a little on that possibility.) Jon
From: hamilton on 11 Apr 2010 17:47 On 4/11/2010 2:55 PM, Richard Rasker wrote: > > Sure, but these devices will have to withstand not just one short reflow > cycle, but dozens of 5-minute sterilization cycles at 135C. If the LED was captured and sealed, how would you connect the leads to the outside ? How is this usually done with internal wiring ? hamilton
From: John Fields on 11 Apr 2010 18:03 On Sun, 11 Apr 2010 15:38:44 -0500, "George Jefferson" <phreon111(a)gmail.com> wrote: > > >"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. --- HahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHaha hahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHaha hahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHaha hahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHaha hahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHaha hahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHaha hahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHaha hahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHaha hahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHaha hahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHaha hahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHaha hahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHaha hahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHaha hahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHaha hahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHaha hahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHahaHaha Thanks, George, I needed that laff! JF
From: Kevin McMurtrie on 11 Apr 2010 19:47 In article <4bc228c1$0$736$7ade8c0d(a)textreader.nntp.internl.net>, 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 That low temperature rating is for the clear epoxy case. You can probably heat them to 130C as long as there's no stress on the pins and you don't mind the lens degrading. Power LEDs have a ceramic and silicone case that has no problem with high temperatures. The sapphire chips (green, blue, white) can even operate moderately well at 135C. They'll cost you dearly - maybe $4 to $10 each. Keep moisture out of them or they'll blister when they get hot. -- I won't see Google Groups replies because I must filter them as spam
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